Article

The formulation and use of mixed collectors in sulphide flotation

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Mixtures of collectors have been widely used for many years in sulphide flotation, and a range of performance benefits have been reported for many different systems. The combinations of collector types have varied, as have the ratios that have been used. Synergistic effects have been obtained (greater than the sum of the parts) and in some cases the mechanisms of this improved behaviour have been identified. These benefits have been attributed to increased carrying capacity of the froth phase, faster kinetics, and more successful recovery of middling or coarse particles. It is the interaction between the various components of the mixed collector system, rather than the individual main effects, that dominate the performance benefits. The process benefits include increased paymetal recoveries and grades – as well as increased rates of recovery whilst using lower dosages of reagents. Various mechanisms have been reported and are discussed. These have been shown to affect different composition/liberation classes and sizes of mineral particles. In recent years, automated quantitative mineralogy and surface analysis technology such as ToF-SIMS have enabled the development of better information, to establish what aspect of the process has been affected. This has been successful mostly for use in a diagnostic capacity. Candidate selection for the mixed collector suite is presently based on experience and contextual knowledge. Predictive properties from these systems are a desirable future goal. Currently optimum combinations are preferably identified experimentally at laboratory scale prior to any plant trial. It is recommended that such laboratory work be performed using a factorial design with replicates and quality controls, such as may be delivered from High-Confidence Flotation Testing. The purpose of this paper is to summarise and review current theory and practice in the usage of mixtures of collectors in sulphide flotation – both in the application and in research in order to develop insights and guidelines to develop a methodology for use in a predictive capacity. A case study demonstrating this approach will be published at a later date.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Thiol collectors; xanthates, dithiophosphates and dithiocarbamate have been investigated in the flotation of these sulphides (Dunne 2005, Chanturiya et al., 1998. Although xanthates are widely used, a synergistic effect have been reported elsewhere to exists between collector admixtures (Lotter and Bradshaw 2010). Improvement in rate of flotation (Adkins and Pearse 1992), improvement in coarse particle recovery (Plaksin and Glembockii 1954), reduction in dosage requirement (Lotter and Bradshaw 2010) and high recoveries for optimum ratio of constituents (Valdiviezo andOliveira 1993, Deng et al., 2010) are but a few of their confirmed benefits. ...
... Although xanthates are widely used, a synergistic effect have been reported elsewhere to exists between collector admixtures (Lotter and Bradshaw 2010). Improvement in rate of flotation (Adkins and Pearse 1992), improvement in coarse particle recovery (Plaksin and Glembockii 1954), reduction in dosage requirement (Lotter and Bradshaw 2010) and high recoveries for optimum ratio of constituents (Valdiviezo andOliveira 1993, Deng et al., 2010) are but a few of their confirmed benefits. Undoubtedly, the aforementioned benefits improve overall flotation recovery and reduces loss of values to tailings. ...
... Xanthate are easily oxidised to its dimer; dixanthogen which chemisorbs on the mineral surface (López Valdivieso et al., 2005). Oxidation of dithiophosphate to its dimer (dithiophosphatogen) is however difficult and suggest a different form of collector interaction on the mineral surface (Lotter and Bradshaw 2010). The different collector species and adsorption mechanisms may have complemented each other and enhanced the flotation recovery in the process. ...
Conference Paper
Full-text available
Sulfhydryl collectors have received wide applications in sulphide value mineral flotation. Blends of this group of collectors have shown the existence of synergism in collecting action when utilized in flotation. In this study, sodium isobutyl xanthate and sodium alkyl dithiophosphates at different mixing ratios are employed in flotation. Results for single mineral flotation show that better flotation response was achieved for collector admixtures compared with singular uses. The highest recovery of 87.78% and 67.74% respectively for pyrite and arsenopyrite was achieved with a blend ratio of 20:80 SIBX to DTP.
... The electron releasing tendency of the R 2 N in DTC increases the electron density around the donor S atom, rendering DTC more reactive (Raju and Forsling, 1997). Thus, on that basis, the reactivity decreases in the following order: DTC > X > DTP (Somasundaran and Nagaraj, 1984;Lotter and Bradshaw, 2010). ...
... It must be emphasised that all collector dosages were calculated based on active content and the total molar dosage was maintained constant at 2.88 × 10 −6 mol/m 2 of the available surface area in all the Table 1 Generic molecular structures of thiol collectors used in this work (Lotter and Bradshaw, 2010 experiments. This was equivalent to approximately 50% pseudo monolayer coverage. ...
... The main difference in the heat of adsorption of the collectors on a sulphide mineral for a given alkyl group is probably due to the differences in the electronegativity of the O, C, P and N atoms in the polar head group (Somasundaran and Nagaraj, 1984;McMurry, 1996;Lotter and Bradshaw, 2010). The DTP is less reactive than the diethyl-DTC because the two RO groups, which are electron-withdrawing, reduce the electron density around the donor sulphur atoms. ...
... Previously, several researchers demonstrated that collector mixtures were better reagents for th flotation of valuable minerals than the single collector systems [16][17][18][19][20][21]. The rate of flotation is reported to be higher with collector blends as compared to the single collector system [16,[22][23][24]. ...
... Previously, several researchers demonstrated that collector mixtures were better reagents for th flotation of valuable minerals than the single collector systems [16][17][18][19][20][21]. The rate of flotation is reported to be higher with collector blends as compared to the single collector system [16,[22][23][24]. Plaskin et al., [22].; Lotter and Bradshaw, [16] also observed other advantages, such as improvement in coarse particle recovery and middlings recovery. ...
... The rate of flotation is reported to be higher with collector blends as compared to the single collector system [16,[22][23][24]. Plaskin et al., [22].; Lotter and Bradshaw, [16] also observed other advantages, such as improvement in coarse particle recovery and middlings recovery. Additionally, the total collector dosage of the mixed collector was lower than the single collector concentration in several studies [20,23]. ...
Article
Full-text available
Norway has newly seen an upsurge of interest in exploiting its mineral deposits influenced by fresh Government focus and survey support for previously under-prospected areas. One of the major areas of interest is a huge copper deposit, operated by Nussir ASA, located in the Repparfjord tectonic window in the Caledonides of west Finnmark. The latest mineral resource estimation is from July 2014, which states that Nussir consists of 5.8 million tonnes of indicated resources and 60.2 million tonnes of inferred resources, giving 66 million tonnes of copper ore. This paper represents the first study on processing characteristics of this ore to date. Our parallel studies using xanthates and dithiophosphates as collectors for Nussir ore flotation examined the grade and recovery of copper, silver, gold, and platinum group (PGM) minerals. Therefore, in this subsequent study, a chelating agent n-Butoxycarbonyl-O-n-butyl thionocarbamate (BBT) is used as a collector and it was found that the recovery and grades of the economically interesting minerals are improved at as low as 2 × 10−5 M collector concentration. Zeta potential, Hallimond flotation and adsorption studies were initially performed in order to assess the selective interaction of BBT and its blend with SIBX (Sodium Isobutyl xanthate) on the three copper minerals of the ore. The bench scale flotation experiments were performed using mixtures of xanthate and thionocarbamate collectors of the Nussir ore and both the resulting copper recovery and grade employing these collector mixtures is observed to be 2–8% superior to the use of a single collector system. Additionally, the current study revealed that the metallurgical results are strongly influenced by the ratio of the collectors in the mixture and particularly the sequence of the collector addition.
... From the background and literature presented, it is evident that inorganic electrolytes which are found in plant water and their ionic strength may affect mineral recovery by altering mineral-collector adsorption. The practice of using mixtures of different collectors is widely implemented in the minerals processing industry [28][29][30][31][32]. Nagaraj and Ravishankar [33] submit that the use of single collectors in the flotation of poly-sulfide ores may not cover the full spectrum of sulfide minerals present in the ore; the use of mixed collector reagent recipes is therefore justifiable due to notable synergism and selectivity improvements that may be realised. ...
... On the impact of collector mixtures in Cu-Ni-PGM ores, literature has shown that mixtures of collectors can result in froth flotation performance improvements such as increased grades and recoveries, increased flotation rate, and improved flotation of coarse particles; all of these achieved under lower collector dosages compared to when a single collector is used [11,14,32,[36][37][38][39]. Lotter and Bradshaw [32] suggested that though mixtures of collectors do show improvements in flotation performance, the valuable-gangue composite particles may be targeted, resulting in more non-valuable solids reporting to the concentrate at the expense of the concentrate grade. ...
... On the impact of collector mixtures in Cu-Ni-PGM ores, literature has shown that mixtures of collectors can result in froth flotation performance improvements such as increased grades and recoveries, increased flotation rate, and improved flotation of coarse particles; all of these achieved under lower collector dosages compared to when a single collector is used [11,14,32,[36][37][38][39]. Lotter and Bradshaw [32] suggested that though mixtures of collectors do show improvements in flotation performance, the valuable-gangue composite particles may be targeted, resulting in more non-valuable solids reporting to the concentrate at the expense of the concentrate grade. However, it is not known whether the benefits reported from these thiol collector mixtures would still be realised in changing water chemistry, particularly in degrading water quality as Cu-Ni-PGM concentrators move more towards the use of recycled water and dithiophosphates for all the suggested benefits, both the positive socio-economic and environmental footprint associated with water re-use and the use of dithiophosphates compared to xanthates. ...
Article
Full-text available
The use of mixtures of thiol collectors is reportedly beneficial in sulfide flotation. This is becoming standard practice for many concentrators, but process water recirculation and re-use in flotation circuits may compromise the behaviour of such mixtures owing to changes in physicochemical interactions occurring in the pulp phase as a result of water quality variations. It is expected that changes in the pulp chemistry would in turn affect both the pulp and froth phase phenomena, thereby affecting flotation performance. Thus, this study considers mixtures of thiol collectors, sodium iso-butyl xanthate (SIBX), and sodium di-ethyl dithiophosphate (SEDTP) in degrading water quality. Bench-scale flotation tests were conducted on various molar ratios of the selected thiol collectors under different ionic strengths (0.0242 mol·dm−3 and 0.1212 mol·dm−3) of synthetic plant water. Increasing the ionic strength of synthetic plant water and SEDTP molar ratio resulted in an increase in water, solids, Cu, and Ni recoveries. Cu-Ni grades decreased in increasing SEDTP molar ratios. The highest Cu-Ni grades were obtained in degrading water quality. The increase in water and solids recoveries in increasing SEDTP and ionic strength of plant water is attributed to an increase in froth stability. It can be concluded that the increase in the ionic strength of plant water increased water recoveries and therefore froth stability in parallel with SEDTP’s froth stabilizing effect, thus suggesting an additive interaction on the froth stabilisation effect seen.
... Collectors are surfactants composed of heteropolar molecules with a non-polar and a polar group [1]. In a froth flotation process, the function of collector is to improve the hydrophobicity of target minerals and selectively float them with the aid of gas bubbles. ...
... From previous studies [e.g. 1,4,[7][8][9], it is well known that there are synergistic effects in flotation when using mixed collectors. The word "synergism" means that the effect of the collector combinations on the flotation performance is better than the effect of simple summation of single collector performances [4]. ...
... Glembotskii [10] also stated that the larger the difference between the structures and compositions in two collectors, the stronger the synergistic effect. This effect is more noticeable at lower collector dosage [1]. Experimental evidence indicated an improved flotation performance with mixed collectors, but there is no clear understanding about the synergistic mechanism. ...
Article
Full-text available
This paper discusses the primary collector adsorption onto a sulphide mineral in mixed collector systems to further understand its adsorption mechanism. UV-Vis measurements were performed to identify the primary collector concentration adsorbed on pyrite, and the adsorption kinetics under different conditions were compared to distinguish their difference between single and mixed collector systems. Small amount of secondary collector addition prior to the primary collector addition significantly improved the adsorption kinetics of primary one. The result was explained by the combination of two previously proposed mechanisms (i.e., different adsorption site mechanism and multi-layer product mechanism). This study showed UV-Vis measurement as an effective tool to study mixed collector adsorption behavior.
... Collectors can be used either as a single reagent or a mixed system. Glembotskii (1958), Lotter and Bradshaw (2010), and Ngobeni and Hangone (2013) have proven that it is beneficial to mix or blend collectors. These benefits included faster kinetics, increased carrying capacity of the froth phase, and recovery of middling and coarse particles (Lotter and Bradshaw, 2010). ...
... Glembotskii (1958), Lotter and Bradshaw (2010), and Ngobeni and Hangone (2013) have proven that it is beneficial to mix or blend collectors. These benefits included faster kinetics, increased carrying capacity of the froth phase, and recovery of middling and coarse particles (Lotter and Bradshaw, 2010). The performance benefits are derived from the interaction between various components of the mixed collectors rather than the singular main effects. ...
... According to Glembotskii (1958), and Lotter and Bradshaw (2010), blends of xanthates and DTCs exhibit synergistic effects. However, the SNPX-DTC blend achieved an overall cumulative recovery similar to that of SNPX alone (Figure 1). ...
Article
Full-text available
Different thiol collectors are widely used to improve the flotation performance of PGM-containing ore. They are used either as a single collector or as a collector blend. The performance of sodium n-propyl xanthate (SNPX), dithiocarbamate (DTC), and O-isopropyl-N-ethyl thionocarbamate (IPETC) collectors was evaluated in order to improve the recovery of PGMs from UG2 ore. SNPX was used as single collector, followed by SNPX blends with DTC and IPETC. The best blend improved the 3PGM + Au recovery from 81% to 86% without compromising the grade. As thiols remain the most widely used collectors in the recovery of PGMs from sulphide ores, particularly with leaner and more complex occurrences, there is room for continued research on the most effective blends.
... The effect of a collector on the mineral surface depends on the length and structure of the above alkyl chain. It is wise to choose the collector with long-chain hydrocarbons and structure as well as functional groups for the flotation of sulfides and PGE minerals (Lotter and Bradshaw 2010). Butyl and isobutyl alkyl chains are highly recommended because the xanthates with longer chain are easy to oxidize to dixanthogen. ...
... Catalysis of isobutyl xanthate radical to dixanthogen by n-butyl DTC(Lotter and Bradshaw 2010). ...
... Chemical collectors such as sodium xanthate salts are among the most widely used compounds in mining industries at selective separating of sulfide minerals by froth flotation. Sodium xanthate salts are also utilized in some other processes, such as cellulose synthesis, pesticide manufacturing, and as a corrosion inhibitors in engine oil additives (Lotter and Bradshaw, 2010;Molina et al., 2013). ...
... These compounds are harmful to biota and have an extended inhibitory effect on nitrifying bacteria. Hence, it is necessary to remove sodium xanthate salts from mining wastewater before its discharge to the environment (Lotter and Bradshaw, 2010;Molina et al., 2013). ...
Article
In the present work, the sonocatalytic degradation of sodium isopropyl xanthate (SIPX) was investigated in the presence of Cu2S nanoparticles. Cu2S nanoparticles were produced by means of a high-energy planetary mechanical ball milling method within the processing times of 0.5, 1.5, 3 and 4.5 h. The physical and chemical characteristics of Cu2S particles were studied before and after ball milling process using various analytical techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) coupled Energy-dispersive X-ray spectroscopy (EDX), atomic absorption spectroscopy (AAS) and nanoparticles size distribution (NSD). The XRD pattern of the samples confirmed the presence of tetragonal and cubic crystalline phases of Cu2S. In addition, the results of SEM and NSD analysis showed that the increase in the ball milling time from 0.5 to 4.5 h notably decreased the size of nanoparticles to the range of 20-40 nm. Furthermore, AAS result showed that the concentration of Cu+ ions was much lower than that of the accepted value in the aqueous media (0.009 mg/L) after 60 min of the sonocatalysis. The study on the effects of the main key parameters showed that 93.99% of SIPX (10 mg/L) was removed during 60 min of the sonocatalytic process under the optimum conditions: pH of 7.3, Cu2S concentration of 1.5 g/L, and ultrasonic power of 150 W. The sonocatalytic degradation mechanism was thoroughly examined in the presence of different organic and inorganic scavenger compounds, including ethanol, EDTA, NaCl and Na2SO4. The obtained results confirmed OH and holes (h+) as the dominant oxidizing species in Cu2S catalyzed sonolysis. In order to get the benefits of the integrated sonocatalytic process, different rate enhancing compounds were introduced into the system. For the first time, the S2O82- and Cu2S catalyzed sonolysis (US/Cu2S/S2O82-) system was introduced as an efficient and novel sonocatalytic system for fast degradation of SIPX. Moreover, the phyto-toxicological assessments proved the reduction in the toxicity of the sonocatalytic-treated SIPX solution by increase in the reaction time, from 20 to 60 min.
... This can be ascribed to the composition of collector DF245, as dithiophosphate collectors are known to be more selective. Collector DF507B has a thiocarbamate structure which is a strong but relatively unselective collector (Lotter and Bradshaw, 2010). This is evident from the first point of the grade-recovery curve, where DF245 produces the highest grade but DF507B the highest recovery. ...
... This is ascribed to the inactivity of cobalt ions. Even though dithiophosphate collectors are known to be more selective, DF245 does produce a relatively high recovery of gangue minerals compared to the xanthate and thiocarbamate types, which are known to be stronger and less selective (Lotter and Bradshaw, 2010). Considering this information and the grade-recovery curves in Section 3.2.1, it can be stated that the dithiophosphate is more selective in the beginning of the flotation process but that effect dissipates with increasing flotation time. ...
... Xanthates are usually less selective than dithiophosphates and dithiocarbamates (25). In order to improve selectivity, mixtures of sulfhydryl collectors are used (26,27). Better results are observed when in the collector mixtures, xanthates are used as the primary collector while xanthic acid, xanthogen formats, dithiophosphates, and dithiophosphinates are used as the secondary collectors (3,21,27). ...
... Chelating collectors have been used industrially as secondary collectors to increase the selectivity of sulfide mineral separation (26,42). These collectors present polydentate ligands capable of forming strong coordination complexes with multivalent metal ions. ...
... It is also hypothesised in this study that a collector of relatively lower strength and potency may provide more room for realisation of selectivity within a narrow separation window. The strength of thiol collectors has been noted to follow the order Dithiocarbamate> Xanthates> Dithiophosphate (Lotter and Bradshaw, 2010;Wills and Finch, 2016) relating to differences in structure and electronegativity of donor atoms; O > N > P. This paper therefore aims at investigating the influential role of hydrogen peroxide and collector type on pyrite-arsenopyrite differential flotation identifying surface species responsible for flotation behaviour under different conditions. ...
... Higher flotation recovery was realised for both pyrite and arsenopyrite under acidic condition with mineral recovery decreasing with increasing pulp pH beyond 4. Arsenopyrite was more depressed compared with pyrite and markedly for DTP than PAX. The depression of pyrite and arsenopyrite with increasing pulp pH was attributed to the formation of surface oxidation product as long as the pulp oxidation potential exceeds values required for the formation of the collector dimers, that is, dithiophophatogen and dixanthogen (López Valdivieso et al., 2006;López Valdivieso et al., 2005;Lotter and Bradshaw, 2010;Petrus et al., 2011;Wang and Forssberg, 1990). Figure 3C shows the pulp redox potentials during single pyrite and arsenopyrite flotation with DTP and PAX. ...
Article
Full-text available
The present work investigates the role of hydrogen peroxide and collector type in differential flotation of pyrite and arsenopyrite model minerals without acid pretreatment. Ethylenediaminetetraacetic acid (EDTA) extraction and X-ray photoelectron spectroscopy (XPS) analysis were employed to determine the oxidation extent supplemented with zeta potential, UV–Vis and Time-of-Flight secondary ion mass spectrometry (TOF-SIMS) towards elucidating collector adsorption behaviour and surface species formation. The results showed higher extent of ferric hydroxide was generally observed for arsenopyrite compared to pyrite using EDTA extraction and XPS analysis. A 2 kg/t hydrogen peroxide addition and 120 g/t PAX collector concentration gave the best separation efficiency with 63.1% pyrite and 5.1% arsenopyrite recovery into the flotation concentrate. The addition of hydrogen peroxide (2 kg/t) had a minor effect on the mineral surface oxidation state according to XPS analysis. Thus, the oxidation of adsorbed xanthate ions into hydrophilic monothiocarbonate ion was the more apparent reason for remarkable arsenopyrite depression compared with pyrite. The observation was not affected with change in sequence of reagent addition and presents great opportunity in better, profitable processing of low-grade refractory auriferous sulphide ores.
... For mineral processing applications, we envisage a special set of alkynes that increase colloidal stability and/or specific affinity to the target mineral surfaces. Based on conventional flotation collector chemistry, the obvious mineral affinity alkynes would include functional groups such as xanthate, imidazole, amine, and dithiocarbamate [22][23][24][25][26]. Alkynes designed to increase colloidal stability would either have charged groups (negative, positive or zwitterionic) for electrostatic stabilization, and hydrophilic, short oligomers (oligosaccharides, polyethylene glycol, polyvinyl alcohol) for steric stabilization. ...
Article
A paper based litmus test has been developed using modulation of urease enzyme activity for detection of C-C mismatch single nucleotide polymorphisms (SNPs) by the naked eye. Urease is first inactivated with silver ions and printed onto paper microzones. Addition of DNA containing C-C mismatches reactivates urease via binding of Ag(I), allowing restoration of urease activity, hydrolysis of urea to produce ammonia, and an increase in pH, which is monitored colorimetrically using a pH indicator with a limit of detection of 11 nM DNA in 40 min. The assay system is easy to use, portable, and stable for at least 30 days at ambient temperature. To assess the versatility and practical application of the paper sensor, we used it to identify a G > C transversion present in human genomic DNA from a ductal carcinoma cell line, a mutation commonly found in breast cancer. We believe this new assay system has the potential to be a low-cost method for rapidly identifying DNA with the C-C mismatch SNP as a means of cancer screening in resource-limited areas.
... Of these three collectors, the dialkyl dithiphosphates (DTP) do not bond as strongly with the mineral surface due to the two electronwithdrawing oxygen atoms attached to the phosphate (Lotter and Bradshaw, 2010). In contrast, dithiocarbamates (DTC's) have electron donating properties resulting in a higher electron density in the dithiol headgroup resulting in a stronger bond with the mineral surface. ...
Article
Dialkyl dithiophosphates (DTP) are commonly used as primary or secondary collectors in base metal sulfide and platinum group mineral flotation. However, evidence in the literature suggests that, under basic conditions, DTP does not adsorb onto certain minerals. The purpose of this study was to investigate the interactions between DTP or xanthate collectors and frothers at the solid-liquid and air-liquid interfaces. Microflotation and contact time tests showed that DTP synergistically improved recoveries and attachment probabilities of galena and pyrite in the presence of frother. These improvements were not seen for any of the single reagents or, most importantly, for mixtures of a xanthate collector and frother. By measuring the residual collector concentration in solution, it was shown that no DTP adsorbed onto the galena surface and only minimal amounts onto the pyrite surface, either in the presence or absence of frother. In contrast, all of the xanthate collector adsorbed onto both pyrite and galena. Investigations at the air-water interface included surface tension and bubble size measurements. These showed that DTP, unlike xanthate, was weakly active at the air-water interface, but did not show evidence of synergistic interaction with frother. It was concluded that DTP can have an alternative mechanism of flotation enhancement to conventional collectors by adsorbing at the air-liquid interface and not the solid-liquid interface. Various theories of the detailed mechanism are discussed in the paper.
... The governing factor that influences the adsorption of thiol collectors onto sulphide minerals is the electron withdrawing and donating groups that control electron density around the sulphur donor atoms. DTP does not bond as strongly with the mineral surface due to two electron-withdrawing oxygen atoms attached to the phosphate (Lotter and Bradshaw, 2010). ...
Conference Paper
Dialkyl dithiophosphates (DTP) are thiol collectors typically used as co-collectors in base metal sulfide and platinum group mineral flotation. Evidence has shown that DTP does not adsorb onto a number of sulphide minerals and, notwithstanding this, it synergistically enhances sulphide mineral recovery. Yet, no clear evidence exists indicating an interaction between DTP and frothers, either. The purpose of this study was to elucidate the interaction between DTP and frothers using microcalorimetry and determine the mechanism of how this interaction enhances sulphide mineral recovery using microflotation and contact time measurements. Microflotation and contact time tests revealed that mineral surface dosages at 50% monolayer coverage do not promote a flotation response, but higher pulp concentration dosages activate a synergistic response on pyrite. Quartz microflotation tests showed no synergistic response, indicating that the interaction is only present for sulphide minerals. It was found that sodium diethyl dithiophosphate (SDEDTP) completely adsorbed onto chalcocite, and a small synergistic increase was observed in the presence of hexanol. Isothermal titration calorimetry (ITC) measurements revealed that SDEDTP weakly interacts with hexanol compared to SEX. It was proposed that DTP interacts with frothers at the air-water interface. During bubble-particle attachment, DTP and frother diffuse through the thin film residing between the bubble and the particle. The movement of the frother through the thin film destabilizes the film, enhances film thinning kinetics and bubble particle attachment in the pulp zone.
... For example, the nitrogen in thiocarbamates suggests a more covalent arrangement than the oxygen in traditional xanthates, but the phosphorus in the dithiophosphinates suggests an even more covalent arrangement in the functional group. According to Lotter and Bradshaw (2010), the differences in the behaviours of the collectors are attributable to the differences in the structure and consequent behaviour of the donor atom. ...
... The formula of xanthate is R-OCSSM, where R is the alkyl group with different chain lengths (C 1−8 ), and M is the metal ion (K + or Na + ). Functional group of OCS 2 has a strong adsorption capacity for copper ions [10]. It is necessary to investigate the adsorption thermodynamics and kinetics of xanthate on copper sulfide for improved separation efficiency. ...
Article
In this paper, the effect of sodium butyl xanthate (NaBX) adsorption on the surface of bornite at different pH on flotation was studied by adsorption kinetic and thermodynamic. The flotation results demonstrated that the recovery was the highest when pH was 9 in NaBX solution (4×10⁻⁵ mol/L). The adsorption kinetics showed the reaction of NaBX on the bornite conformed to the second order kinetic equation; it belonged to the multimolecular layer adsorption of Freundlich model; the maximum adsorption rate constant was 0.30 g/(10⁻⁶ mol·min), and the equilibrium adsorption capacity was 2.70×10⁻⁶ mol/g. Thermodynamic calculation results indicated that the adsorption process was spontaneous chemisorption, and the adsorption products of NaBX on bornite surface were cupric butyl xanthate, ferric butyl xanthate and dixanthogen, which were confirmed by infrared spectrum measurements.
... When a continuous flow of air bubbles is pumped through a sinter into a flotation column filled with heavy-metal contaminants, specific ion binding to the surfactant head-groups exposed to the solution surrounding each rising bubble produces an efficient separation process whereby the ions are carried in the foam removed at the top of the column. In particleflotation technology, the term 'collectorʼ is used for these surfactant molecules, which bond to a metal ion with different selectivities and ratios to form complex structures (Lotter and Bradshaw, 2010;Polat and Erdogan, 2007) and facilitate particle attachment to the bubble surface. ...
Article
Full-text available
An improved method has been developed for the efficient synthesis of octanoyl-cysteine in single-chain form (N-octanoyl-cys) which operates as a surfactant over a wide pH range, is easily decomposed into natural products and has a high product yield. The compound offers an environmentally acceptable agent for the adsorption of a range of heavy metals from contaminated waters/soils, and it could also be used in general household detergents or personnel-cleaner formulations, and even in toothpastes. The surfactant was used as a co-surfactant for flotation of perfluorooctanoic acid (PFOA), a per/poly-fluoroalkyl substance (PFAS). The new surfactant produced significant foaming and removed 70% of the PFOA after 30min of foam fractionation. The compound is also potentially useful in facilitating the release of PFAS compounds; these are negatively charged and often bound to charged particles in sand, clay, and humic-acid-coated materials and microorganisms via bridging multivalent ions, such as Ca2+, Mg2+, Al3+ and Fe3+, as well as a range of other heavy-metal ions present in soil to varying degrees. In soils (and also in contaminated water), the common chelating agent EDTA is often used to encapsulate these ions (e.g. Ca2+, the dominant ion in soil) at moderately high pH to aid in the release of the bound PFAS compounds. However, it would be more environmentally acceptable to use this new biodegradable surfactant, which could combine chelation with foam-fractionation separation of surface-active (e.g. PFAS) components in soils.
... For example, the nitrogen in thiocarbamates suggests a more covalent arrangement than the oxygen in traditional xanthates, but the phosphorus in the dithiophosphinates suggests an even more covalent arrangement in the functional group. According to Lotter and Bradshaw (2010), the differences in the behaviours of the collectors are attributable to the differences in the structure and consequent behaviour of the donor atom. ...
Article
This paper presents a study to obtain sulphide as byproducts of a concentrated cleaner of gold generated from the flotation process of sulphide gold ore of mine Morro do Ouro. Chemical analysis of the concentrated of gold showed a content of approximately 22.05% S, in the form of a bulk sulphides. The liberation of the sulphides was measured using a SEM with second generation automated mineralogy (MLA). For the chalcopyrite recovery step, the fraction of liberated gangue particles is above 90%, for galena up to 92% and sphalerite above 96%, in all sizes. Moreover, the fractions of particles of minerals of interest that are completely liberated is below 0.52% for the chalcopyrite recovery step, 0.65% for galena and 0.28% for sphalerite, in all sizes. The use of collectors Aero 3894, 3418A and 5100 allowed greater selectivity in the flotation circuit presented. The recoveries of chalcopyrite, galena and sphalerite in the Rougher steps were 82%, 73% and 62%, respectively.
... Although xanthates are the most widely used collectors in the suite of thiol collectors, they yield an unselective float and have led to the development of collectors with higher selectivity against most iron sulphides [21,31]. Dithionocarbamate collectors, developed by Cytec, falls within this category credited for its high selectivity against pyrite in the flotation of copper ores under alkaline conditions [14]. ...
Article
Thionocarbamate collectors are noted for their high flotation selectivity against pyrite under alkaline condition. In this study, selectivity of O-isopropyl-N-ethyl thionocarbamate (IPETC) is investigated in decoupling flotation response of pyrite and arsenopyrite under single mineral and artificial composite systems. The influence of copper addition, collector adsorption behaviour and mineral surface speciation on flotation response were characterised using complementing electrokinetic and spectroscopic techniques. The results showed no pyrite and arsenopyrite flotation at pH 11 until CuSO4 (2.5 × 10⁻⁵ mol/l) addition where arsenopyrite displayed remarkably good, CuSO4 concentration dependent flotation response relative to pyrite. Collector concentration (> 4 × 10⁻⁶ mol/l IPETC) had little effect whilst the flotation response was highly pH dependent. The preferential IPETC adsorption on copper-treated arsenopyrite at pH ≥11, yielding 90% arsenopyrite and 11% pyrite concentrate recovery, was ascribed to chelate formation between sulphur and copper and a synergistic coordination of the σ bond of arsenic and deprotonated nitrogen of IPETC.
... There are a number of technological parameters depending on the flotation pulp conditions that indicate the successfulness of the flotation process (Magdalinovic, 2017;Langa et al., 2014;Lotter and Bradshaw, 2010;Bulatovic, 2007). In the cases of copper sulfide ore flotation, the following parameters could be stated as some of the most significant: ...
... Compared to other available collectors such as dithiocarbamate, xanthates are the most widely used as flotation reagent, the maximum consumption of collectors and the most economical sulfide ores collectors [18,19]; a medium-sized producer in China can sell 30,000 tons per year domestically and internationally [20]. Xanthates (R-O-CSSMe) have been shown to have weaker selectivity and better collectivity for sulfide minerals than dithiophosphate [21][22][23][24]. ...
Article
Full-text available
Xanthates are by far the most widely used collectors in the froth flotation beneficiation of sulfide ores. However, the xanthate production process suffers from low yield, low productivity, long reaction time and environmental pollution. To address these issues, an effective method was developed for the synthesis of xanthates using phase transfer catalyst. Sodium isobutyl xanthate was synthesized from isobutyl alcohol ((CH3)2CHCH2OH), sodium hydroxide (NaOH) and carbon disulfide (CS2) with dichloromethane (CH2Cl2) as solvent and cetyltrimethylammonium bromide (CTAB), cetyltrimethylammonium chloride (CTAC), tetrabutylammonium bromide (TBAB) and tetrabutylammonium chloride (TBAC) as phase transfer catalyst. The compound was characterized by elemental analysis, infrared spectrum, 1H NMR and 13C NMR. The influencing factors on the content and yield of sodium isobutyl xanthate including phase transfer catalyst type, phase transfer catalyst dosage and reaction time were studied by single-factor experiments. The influencing factors on the product purity and yield including reaction temperature, solvent volume, material ratio and rotating speed were studied by orthogonal experiments. The results showed that when the amount of TBAC was 3.0%malcohol, the reaction temperature was 35 °C, the solvent volume was 3.5 Valcohol, the rotating speed was 180 rpm, the reaction time was 4 h and the material ratio was n[(CH3)2CHCH2OH]:n(NaOH):n(CS2) = 1:1:1.10, the product yield could be up to 86.66% and the product purity reached 82.56%.
... It is required to use new beneficiation methods and flotation reagents to increase the efficiency of flotation of ore minerals to improve the processing of finely disseminated ores. Particular difficulties are associated with the processing of the slurry part of the crushed ore, which is usually enriched with non-ferrous, rare, and noble metals [1][2][3][4][5]. Improving the efficiency of flotation can be achieved by using a combination of different collectors [6][7][8][9][10]. ...
Article
The article presents the results of laboratory studies on ore flotation of copper-molybdenum deposits in the East Kazakhstan region of Kazakhstan using a combined reagent. It is required to use new beneficiation methods and flotation reagents to increase the efficiency of flotation of ore minerals to improve the processing of finely disseminated ores. The problem can be solved by using a combination of different collectors. The objective of the research is to increase the recovery of copper and molybdenum during flotation of copper-molybdenum ore using a combined reagent. The studied ore sample contains 0.42% copper; 0.009% molybdenum. A combination of sodium butyl xanthate, TS-100 thionocarbamate, and reaflot in a ratio, in %: 15: 3: 1, was used as a combined flotation reagent. The combined flotation reagent was preliminarily passed through an ultrasonic homogenizer JY96-IIN to obtain a reagent microemulsion before flotation. The optimum dispersion time for the combined flotation reagent is 60 seconds. At the same time, 99.4% are microemulsion particles with a particle size of fewer than 3.7 microns. The use of a combined reagent microemulsion increases the extraction of copper into the copper-molybdenum concentrate by 3.69%, and the extraction of molybdenum by 6.05%. The copper content in the copper-molybdenum concentrate increases by 1.26%. The copper content in the flotation tailings decreases from 0.07 to 0.056%. The consumption of the combined reagent is reduced by 15% in comparison with the basic butyl xanthate.
... Bagci et al. (2007) proposed a similar theory of strong and weak sites to account for improvements seen when using mixtures of xanthate and dithiophosphinate. In a report on the synergistic interactions involving xanthates and dithiocarbamates Lotter and Bradshaw (2010) have suggested that DTC catalyses the formation of dixanthogen from xanthate. Since dixanthogen is more hydrophobic than xanthate, this would result in enhanced flotation performance. ...
Article
In order to recover minerals by flotation, the sub-processes of collector adsorption onto the valuable minerals followed by bubble-particle attachment should occur efficiently. This paper investigates both of these sub-processes for various thiol collectors and their mixtures onto base metal sulfide minerals. The aim of the work was to investigate whether there is a correlation between the strength of the collector interaction with the mineral and the subsequent bubble-particle attachment. The collector-mineral interaction was measured experimentally using an isothermal titration calorimeter in order to determine the molar enthalpy of adsorption for each collector-mineral system. The bubble-particle attachment was measured using a microflotation device which essentially determines the hydrophobicity of the mineral. Sodium ethyl xanthate (SEX) and sodium diethyl dithiocarbamate (diethyl-DTC) and mixtures thereof were used as collectors with either single minerals or binary mixtures of pyrite and chalcopyrite, respectively. The adsorption enthalpies of the collectors were interpreted with reference to the chemical structure of the collector molecule and showed that the greater the positive inductive effect of the collector, which may be qualitatively related to their pKa values, the greater their affinity for the mineral surface. When mixtures of collectors were used there was clear evidence of synergistic effects in enhanced enthalpies of interaction between collectors and the mineral surface and in increased microflotation recoveries. When mixtures of pyrite and chalcopyrite were used the flotation recovery and enthalpy of adsorption of SEX onto the individual pyrite particles in the mixture also increased substantially compared to the case of pyrite alone. Mechanisms are proposed to interpret these observations.
... The main function of collectors is to induce selectivity of desired mineral. The use of surfactant mixtures as collector can have a synergistic effect over the single collector using [4]. Of all the minerals studied thus far, pyrite depression with cyanide is the best understood. ...
... In the past, Glembotskii [9] demonstrated that when a weaker collector is added to a stronger collector, the mixture results in an increase in recovery as compared to the individual strong collector system. Later, Bradshaw et al. [10,11] and Lotter and Bradshaw [12] reviewed the use of various mixtures of collectors in sulphide flotation where the selectivity and, thereby, the recovery and grade increase depending on the proportions of constituents of the collector blend. Additionally, the same authors indicated that the recoveries of middlings could be increased with the usage of mixtures of collectors in optimum ratios. ...
Article
Full-text available
The Norwegian mining industry is currently showing increasing interest in the production of metals. Recent research has demonstrated promising results identifying the high potential of the Nussir deposit for the production of copper and other valuable minerals. Mineralogical characterization for Nussir ore samples and their flotation concentrates was performed with optical microscopy and Zeiss automated mineralogy (Mineralogic) where the fine copper sulphide middlings were not completely recovered with a traditional sodium isobutyl xanthate (SIBX) collector. In the current study, dithiophosphate and a mixture of xanthate and dithiophosphate collectors’ interaction on copper and other gangue mineral components of the ore sample were investigated with zeta potential, quantitative adsorption, FTIR studies and Hallimond tube flotation. All the results for single mineral experiments confirmed the feasibility of selective copper sulphide flotation by disecondary butyl dithiophosphate (DBD) as collector. The blend of xanthate and dithiophosphate was chemically adsorbed as individual entities on the surface of the copper minerals via competitive adsorption. A systematic study with DBD and a mixed collector (SIBX and DBD) system was conducted on the coarse grind (−105 µm) of the Nussir ore sample, and the results showed a synergistic interaction between the two reagents. The beneficiated copper concentrate using this mixture of collectors is indeed of improved copper grade and recovery. The highest copper recovery in bench scale flotation was 95.3% with a concentrate grade of 19.4% Cu for DBD collector, whereas mixtures of dithiophosphate and xanthate collectors in the ratio of 3:1 resulted in the highest copper grade (24.7%) and recovery (96.3%).
Article
Various studies have been increasingly performed on the reduction of sulfur content of iron ores and concentrates. The presence of sulfur in these materials causes technical problems in steel and alloys and environmental issues in the sintering of iron ore process. The achievement of higher sulfur removal rates has been an important goal since the development of sulfur removal techniques. In this research, an effort is made to separately introduce the various processes, industrial practices, and fundamental research activities to remove sulfur from iron ores, concentrates, or roasted iron ores. In this way, the optimized condition and latest innovations in sulfur removal using flotation are reviewed and the development of leaching and bioleaching techniques for sulfur reduction is introduced; following the development of thermal decomposition, physical separation methods, and magnetic separation technique are discussed. In each section, a brief introduction of fundamentals for the sulfur removal techniques and their potential advantages for sulfur removal are described and challenges for each technique are presented. Finally, the techniques are compared from technical, economic and environmental viewpoints, and future trends in desulfurization of iron ores are presented.
Chapter
The formulation and use of mixed collector suites in sulphide flotation can be traced back as far as 1957 with the work of Glembottskii and his co-workers in Moscow. The subject was reviewed by Lotter and Bradshaw in 2010, and proposed a synergy between ideally-selected different reagent types to deliver improved performance, in particular the in-situ catalysis of a xanthate to dixanthogen by a dithiocarbamate. Correctly formulated for a particular application, an optimally arranged mixed collector suite delivers the following improvements to the flotation process: • An increase in the flotation kinetics • Improvement in coarse, or middling, particle recovery • Reduction in total dosage requirement • Best results are found from testing the ratios of the collectors. This is of critical importance. In all an optimally formulated mixed collector system usually delivers an increase in paymetals recovery of 1-4% absolute, with a gain in concentrate grade in the range 10-20% relative. In recent years, the addition of semi-conductor theory and associated electrochemistry has contributed significantly to this toolbox by way of identifying optimum domains of Eh and pH for the flotation of individual minerals. In the case of mixtures of minerals, this is where the mixed collector system delivers significant value by way of presenting a mixed set of collector radicals and dimers in a common Eh and pH domain for overall performance. This calls on a fundamental understanding of organic chemistry, mineralogy, semiconductor theory, and electrochemistry. Whereas the selection of grinding media type effectively influences the Eh, the pH can be easily controlled by pH modifiers. The theory of this system, and some industrial case studies, are discussed.
Article
The influence of two biopolymers (xanthan gum and locust bean gum) on the interaction between bubbles and graphite has been elucidated using a combination of direct measurement techniques. Bubble-surface collisions (monitored using high speed video capture) reveal that when graphite is exposed to low concentration solutions of the two polymers, the timescale of bubble attachment is prolonged by 1 − 2 orders of magnitude, and the final receding water contact angle achieved on such surfaces is reduced by approximately 30 degrees. Single bubble flotation studies confirm the significant effect of such aspects of bubble-particle collisions on the collection efficiency of graphite particles, with marked reduction in flotation recovery across the particle size range, with greatest effect on the coarser particle sizes. The differences in performance of the two polymers in reducing bubble-particle attachment is seen to be partly due to variation in adsorbed layer coverage of the two polymers on the graphite surface, as revealed by atomic force microscopy imaging. Both polymers can be expected to perform well in the prevention of flotation of graphitic/carbonaceous minerals.
Article
The effect of sodium butyl xanthate (NaBX) and dodecylamine (DDA) as combined collector on the sulphidizing flotation of copper oxide was investigated by flotation test, fluorescent pyrene probe, zeta potential, and infrared spectroscopy analyses. The micro-flotation results show that combined use of NaBX+DDA yields better effect than using NaBX at pH 7-11 only, and the optimal molar ratio of NaBX to DDA is 2: 1. The actual ores flotation shows that when the dosage of NaBX+DDA is (100+54) g/t, the copper concentrate grade and recovery are 15.93% and 76.73%, respectively. The fluorescent pyrene probe test demonstrates that the NaBX+DDA can reduce the micelle concentration in the pulp. The zeta potential and the infrared spectroscopy analyses indicate that chemical adsorption, hydrogen-bonding and electrostatic interaction can help to adsorb NaBX+DDA on the surface of malachite. Meantime, copper xanthate and copper-amine complexes may be generated during the adsorption process.
Article
In order to improve the stability of silicon-based heavy metals adsorbents and reduce ions release (Zn, Mg, etc) in the ion exchange process, a novel adsorbent with excellent heavy metal adsorption was synthesized by loading sodium isobutyl xanthate (SIBX) onto the surface of silicon-zinc mesoporous (SZM) material. For comparison, two silicon-zinc materials using silicate (Na 2 SiO 3 , inorganic silicon) and tetraethyl orthosilicate (C 8 H 20 O 4 Si, organic silicon) were synthesized separately. Among them, inorganic silicon-zinc mesoporous (SZM-1) material was used to verify its ions exchange properties, organic silicon-zinc mesoporous (SZM-2) material acts as matrix and modified with SIBX. The copper sulfate solution was employed to evaluate the adsorption ability of as-prepared adsorbents. Above materials were characterized by a set of complementary techniques: SEM-EDS, XRD, TEM, BET, FT-IR, and XPS. The analyses prove that the SIBX can be attached to the surface of the SZM-2, the presence of SIBX can simultaneously immobilize Zinc atoms and adsorb Copper ions.
Conference Paper
Full-text available
The collectors used in sulfide flotation have not changed for decades. Xanthates were first used in mineral processing in 1924 and have been the workhorse of mineral flotation ever since. In the last decade the difficult to process deposits have become viable and as a result an increased interest in finding different collectors. Tecflote is a new family of patented collectors based on nitrile chemistry, which can supplement or replace xanthates and other thiol collectors, depending on the ore type and process design. The insolubility of the Tecflote collectors has a profound effect on the mechanism of hydrophobicity and bubble attachment of particles and is significantly different to other collectors available for sulfide flotation. ToF-SIMS surface analysis results are presented to support the observations and help explain the mechanism. Using Tecflote as the main collector for the rougher and cleaner steps allows the steep grade recovery curve typical of Tecflote collectors to give a better recovery compared to PAX. An example will be given where further improvement is achieved by addition of PAX in the scavenger. The synergy of mixed collector systems will be discussed with other examples from mine lab tests from Australia and Europe, which support the published theory.
Article
The microflotation experiments were systematically carried out to investigate the inhibitory effect of citric acid (CA) on the flotation behavior of hornblende and magnesite. When the mixture consisted of sodium oleate and dodecyl phosphate was utilized as a mixed trapping reagent, CA could obviously inhibit the hornblende flotation but had little inhibitory effect on magnesite flotation. The desilication of magnesite flotation was accomplished when CA was employed as the hornblende inhibitor. Moreover, to reveal the adsorption mechanism of CA on the surfaces of hornblende and magnesite, a series of surface analysis techniques, such as X-ray photoelectron spectroscopy (XPS), zeta potential and Fourier transform infrared spectroscopy (FTIR), were conducted. Based on the zeta-potential and FTIR analyses, it is revealed that CA or CA together with collector (sodium oleate and dodecyl phosphate mixture) was applicable for the magnesite flotation tests. In the meanwhile, the introduced CA had obviously hindered the adsorption of sodium oleate and dodecyl phosphate mixtures on the hornblende surface, resulting in a significant difference in the flotation performance of hornblende and magnesite minerals. Moreover, XPS measurements revealed that the strong adsorption of CA on the hornblende surface can be ascribed to its affinity for the negative electron groups of CA and Ca ions.
Article
Although extensive research has been done on improving the separation performance of coarse coal in the minerals processing industry, there is still a gap between the current recovery of the coarse coal and the optimal separation performance. We developed a lab-scale aerated fluidized bed in this paper to investigate the effects of slurry concentration, superficial water velocity, aeration rate, concentration of frother and concentration of collector on the separation performance of coarse coal (1–0.125 mm). The aerated fluidized bed has an inside diameter of 0.15 m, a total height of 0.85 m, and a cross-sectional area of 0.018m². The test result showed that the ash separation degree increased initially and then decreased with the increase of slurry concentration, aeration rate, superficial water velocity, concentration of frother and concentration of collector, respectively. The optimal separation performance was achieved in an aerated fluidized bed under the conditions of 500g/L slurry concentration, 30mm/s superficial water velocity, 0.36 m³/h aerated rate, 0.06285mmol/L concentration of frother, and 200g/t-coal concentration of collector. Compared to the conventional liquid-solid fluidized bed, the use of the aerated fluidized bed in this study produced a much higher yield of clean coal, reduced tailings, and achieved 29.12% higher recovery of coarse particles.
Article
Serpentine, a typically magnesium phyllosilicate gangue mineral, is often associated with chalcopyrite. In the process of flotation, serpentine is easy to get into the concentrate together with useful minerals, which seriously affects the quality of concentrate products. In this study, galactomannan (GM) was introduced for effectively separating chalcopyrite from serpentine with sodium butyl xanthate used as the collector. Its depression performance and adsorption mechanism were investigated through micro-flotation tests, zeta potential, FTIR, and XPS measurements. Micro-flotation test results showed that GM depressed serpentine more stronger than that of the chalcopyrite at a wide pH range of 3–8. An excellent separation of chalcopyrite and serpentine was achieved using GM as the depressant with a lower dosage of 40 mg/L, for which the flotation recovery of chalcopyrite was more than 80% and that of serpentine was close to 0. Zeta potential, FTIR, and XPS results illustrated that GM was chemically adsorbed on the serpentine surface through the interaction of the hydroxyl groups of GM with the Mg atoms on the serpentine surface. The formation of Mg(OH)2 enhanced the hydrophilicity of serpentine and inhibited the adsorption of flotation reagents onto the serpentine surface, and thereby decreasing its floatability. Therefore, GM could be used as a potential depressant of serpentine owing to its high selectivity, low dosage, environment protection, and low cost.
Chapter
In this chapter, the most salient nanoscience and nanotechnology concepts related to extractive metallurgy, specifically mineral froth flotation, are discussed. The most relevant and current findings of nanotechnology‐based research in the domain of mineral processing and a concise overview of recent advances in the application of nanotechnology for improved mineral recovery using froth flotation technology is reported. In this ever‐expanding age of technologies to improve mineral processing, nanotechnology stands as one of the technologies which can revolutionize the mineral processing industry in general. Nanomaterials present novel properties, which can be exploited to generate exceptionally good reagents to improve recoveries and grades of minerals of interest during the froth flotation process. In light of these current developments, insight into potential future research directions for nanotechnology research in the domain of froth flotation of minerals is given.
Article
Polymer and small molecules are often used to modify the wettability of mineral surfaces which facilitates the separation of valuable minerals such as molybdenum disulfide (MoS2) from gangue material through the process of froth flotation. By design, traditional methods used in the field for evaluating the separation efficacy of these additives fail to give proper access to adsorption kinetics and molecule conformation, crucial aspects of flotation where contact times may not allow for full thermodynamic equilibrium. Thus, there is a need for alternative methods for evaluating additives that accurately capture these features during the adsorption of additives at the solid/liquid interface. Here, we present a novel method for preparing MoS2 films on quartz crystals used for Quartz Crystal Microbalance with Dissipation (QCM-D) measurements through an electrochemical deposition process. The resulting films exhibit well-controlled structure, composition, and thickness and therefore are ideal for quantifying polymer adsorption. After deposition, the sensors can be annealed without damaging the quartz crystal, resulting in a phase transition of the MoS2 from the as-deposited, amorphous phase to the 2H semiconducting phase. Furthermore, we demonstrate the application of these sensors to study the interactions of additives at the solid/liquid interface by investigating the adsorption of a model polymer, dextran, onto both the amorphous and crystalline MoS2 surfaces. We find that the adsorption rate of dextran onto the amorphous surface is approximately twice as fast as the adsorption onto the annealed surface. These studies demonstrate the ability to gain insight into the short-term kinetics of interaction between molecules and mineral surface, behavior that is key to designing additives with superior separation efficiency.
Article
Flotation separation is determined by chemical additives which can enlarge the hydrophobicity difference of minerals. Herein, S-[(2-hydroxyamino)-2-oxoethyl]-N,N-dipropyl dithiocarbamate (HAPTC) was firstly developed for the flotation separation of galena and sphalerite. In situ AFM imaging elucidated a much stronger adsorption affinity of HAPTC towards galena (PbS) than that to sphalerite (ZnS) at pH 6.2 and 9.0. The AFM force findings and the extended DLVO theory analyses indicated that HAPTC adsorption promoted the hydrophobicity of galena surface more significantly than that of sphalerite. The micro-flotation results showed that HAPTC achieved a selective flotation separation of galena against sphalerite at pH around 9.0. FTIR and XPS uncovered that both dithiocarbamate and hydroxamate groups in HAPTC participated in the bonding interaction with Pb sites on galena surface with the formation of Pb-S and Pb-O bonds. The results provide implications on developing novel reagents, and the fundamental understanding of their adsorption and hydrophobization to minerals at nanoscale.
Article
Flotation reagents have a complex behaviour in the beneficiation of base minerals in clayey ores. Interaction effects of reagents on the efficiency of copper flotation for a highly clayey low-grade sulphide ore were investigated using a central composite design. Preliminary results showed that sodium-isopropyl-xanthate (SIPX) and O-isopropyl-N-ethyl-thionocarbamate (IPETC) were found to be the most efficient collectors in the presence of lime as the pH regulator. The effects of dosage of collectors (SIPX and IPETC) and the dosage of methyl-isobutyl-carbonyl (MIBC) as frother on the separation efficiency were evaluated at different pH levels. Based on the analysis of variance (ANOVA), the interaction effects of the collector−pH and collector−frother were significant for the separation efficiency. At the low level of collector dosage, increasing pH from 9 to 11 enhanced copper separation efficiency from 81% to 86% for IPETC and from 77% to 86% for SIPX. Results of ANOVA showed that the maximum copper separation efficiency (88.7%) was obtained at the dosages of 8.6 g/t SIPX, 7 g/t IPETC and 20 g/t MIBC at pH 11. Finally, it was concluded that a mixture of SIPX and IPETC collectors was more suitable to treat highly clayey sulphide ores.
Article
Effective collector is essential in columbite-tantalite flotation from gravity tailings, as well as in the sustainable utilisation of Ta–Nb resources. In this study, benzohydroxamic acid (BHA) and sodium isobutyl xanthate (SIBX) were introduced as a mixed collector system to improve the flotation of columbite–tantalite at reduced cost. An increase in columbite-tantalite recovery was observed in the presence of BHA–SIBX mixtures relative to those with BHA alone. The 3:1 BHA–SIBX mixture exhibited the highest columbite-tantalite recovery. The synergistic enhancement of the flotation performance was attributed to the improved adsorption of the BHA–SIBX mixture on the columbite-tantalite surface compared to that on BHA alone. Batch flotation tests of real ore showed that, compared with BHA (600 g/t), a smaller amount of the BHA–SIBX mixture (400 g/t) was needed to achieve better Ta2O5 recovery. Additionally, an economic evaluation confirmed the economic efficiency of recovering fine columbite-tantalite from gravity tailings using the mixed BHA–SIBX collector.
Article
The degradation of refractory aniline aerofloat (AAF) collector was investigated by an ozone/Vacuum-UV (O3/VUV) process. The effects of O3 dosage and initial pH on the AAF degradation were studied. The total organic carbon (TOC) and concentrations of SO42‒, PO43‒ and NO3‒ anions were measured to evaluate the AAF mineralization. The solid phase extraction and gas chromatography‒mass spectrometry (SPE/GC‒MS) was developed to identify byproducts. The results showed that 99.84% of AAF could be removed by the O3/VUV, and the AAF degradation was enhanced at higher O3 dosage and initial solution pH. The radical scavenging tests revealed that most of AAF was degraded by OH• radicals, and the O3/UV254nm made the main contribution in AAF degradation in the O3/VUV system. The mineralization extents of C, S, P and N elements of AAF at 180 min reached 47.74%, 93.94%, 17.71% and 45.81%, respectively. At initial pH >10.0, the EE/O values of AAF degradation by the O3/VUV was below 7.0 kWh•m‒3 per order, showing the energy consumption was acceptable. The SPE/GC‒MS analysis showed that toxic aniline was generated in the O3/VUV oxidation of AAF, but it was further degraded at longer time. Compared to the ozonation, the O3/VUV had much lower content of aniline at 180 min. The possible degradation pathways of AAF by the O3/VUV were proposed.
Article
Monohydric alcohols with varying chain lengths and isomeric structures, which had significant effects on improving the magnesite and dolomite flotation, were added separately to replace part of dodecylamine (DDA). The intensified effects of alcohols differ with different chain lengths and isomeric structures. Alcohols can enhance the adsorption of DDA and reduce the adsorption distance of DDA on both surfaces of magnesite and dolomite. And the adsorption energy of the mixed collector decreased with the increasing chain length of alcohol. The isomeric alcohols presented more significant effects on lowering the adsorption energy of the collectors. The co-adsorption of alcohol compressed the hydration layer and dilute the water concentration in the hydration layer. Changes of the hydration layer were greater with adding alcohol with a long carbon chain and isomeric structure. Thus, alcohols with long chain lengths and isomeric structures performed better in improving the flotation of magnesite and dolomite.
Article
Aniline aerofloat (AAF) is a biologically persistent flotation collector with potential hazards to aquaic lives and humans. In flotation wastewaters, transition metallic ions usually coexist with residual reagents. Thus, the homogenous catalytic ozonation can be formed while flotation wastewaters are treated by ozone. In this work, the catalytic ozonation of AAF collector was evaluated with transition metallic ions (Fe²⁺, Fe³⁺, Cu²⁺, Pb²⁺ and Zn²⁺). Particularly, the effects of Fe²⁺ dosage, initial pH and O3 dosage on the Fe²⁺ catalytic ozonation of AAF were studied. The AAF mineralization was evaluated by measuring the TOC, SO4²⁻ and NO3‒ concentrations. The degradation rate followed the order O3/Fe²⁺ > O3/Fe³⁺ > O3/Cu²⁺ > O3/Pb²⁺ > O3/Zn²⁺≈O3-alone. The reduction of EE/O values for AAF degradation reached 4.75–44.15 % by introducing transition metallic ions. For five metallic ions, Fe²⁺ ions had the highest catalytic activity. At the Fe²⁺ dosage of 10 mg L‒1, the O3/Fe²⁺ achieved an increase of 31.15 % for the degradation rate and of 42.26 % for the AAF mineralization compared to O3-alone. The SPE/GC–MS analysis showed that the byproducts generated by O3-alone were quite different from those by O3/Fe²⁺, and toxic aniline and phenol were not detected in the O3/Fe²⁺ system. The results indicated that transition metallic ions could well enhance the ozonation of flotation reagents with lower energy consumption.
Article
Flotation is an essential process in beneficiation production. The amount of flotation reagent has a significant influence on the quality of the product. An inappropriate dosing system will lead to metal loss and reagent waste, especially when the nature of the raw ore changes frequently. If the dosing system is not updated in time, it will cause economic losses. Based on digital twin technology and machine learning algorithms, this research designed a digital twin system for iron reverse flotation reagents. Based on the flotation froth image and transformer algorithm, a soft sensor model of tailings grade is established to monitor the product quality in real-time. The flotation dosing model established based on the ELM algorithm automatically updates the reagent system and intelligently assigns the controller. On the basis of stabilizing product quality, this research avoids the waste of reagents and improves the economic benefits of production efficiency. The system was applied in an iron flotation plant, and industrial operation effect verified the method.
Article
The flotation of coal with different ash content when using Sinterol modifier is studied. If the modifier consumption is 1.0–3.0 g/t of coal fines, the extraction of the coal’s combustible mass in the concentrate is increased; the selectivity of the process is increased; and the loss of the coal’s organic mass with the flotation wastes is decreased. The improved flotation may be explained as follows. The Sinterol modifier is adsorbed on active sections of the coal surface by means of hydrogen bonds with its polar groups, in a configuration such that the hydrocarbon groups face the water. That results in a more hydrophobic surface of the coal particles and improves their floatability. The modifier is more effective in flotation when supplied before the collection agent.
Article
The present study investigates the application of thiol collectors and their mixtures on the flotation of copper-silver-gold minerals from a new copper mine located in northern Norway. The copper minerals (chalcopyrite, chalcocite, and bornite) are uniformly distributed in all size ranges in the ore sample under study. Silver, gold and PGM (platinum group minerals) are closely associated with these copper sulphides, although only in trace amounts. The identified gold and silver particles occurred as fine inclusions (~10–32 µm) in copper minerals. In order to maximise the recovery of these economically interesting minerals, improvements in the recovery of the base copper minerals are required. Chemicals used in flotation greatly influence metallurgical results. Consequently, the feasibility of selective sulphides flotation using sodium iso-butyl xanthate (SIBX), n-butoxycarbonyl-O-n-butyl thionocarbamate (BBT), disecondary butyl dithiophosphate (DBD) and their mixtures as collectors were studied since these were identified as promising subjects of investigation. This paper presents a thorough analysis and comparison of results from the application of these three collectors and their mixtures to pure minerals. An increase in copper recovery was observed in the presence of collector mixtures relative to single collectors. It was found that xanthate and thionocarbamate in the ratio of 1:3 exhibited a highest grade of 29% and 98% copper recovery. Additionally, a significant increase in gold and silver recoveries/grades was also noticed in the presence of collector mixtures. The recovery of PGM increased marginally at the expense of concentrate grade while using the collector mixtures. The current study also revealed that all these metallurgical results are strongly influenced by the ratio of the collectors in the mixture and particularly the sequence of collector addition.
Article
The species adsorbed on Cu sulfide ore minerals from alkaline or near neutral solutions of blends of the flotation collectors dibutyl dithiophosphate (BDTP) and 2-mercaptobenzothiazole (MBT) have been established by X-ray photoelectron spectroscopy. Adsorption on air-exposed Cu metal, cuprite, chalcocite, covellite, chalcopyrite and pyrite was investigated from relatively high concentration solutions to simulate processing of variably oxidised ores or slug addition of collector under plant conditions, as well as from solutions of lower concentration. For air-exposed Cu metal, it was found that for a typical BDTP-MBT blend in which di-n-butyl DTP predominated, negligible BDTP was adsorbed at high concentration unless the pH was below 7. By contrast, at low concentrations but under non-starvation conditions, BDTP adsorption predominated even in the alkaline pH range. Both BDTP and MBT species were adsorbed following sequential conditioning in the two collectors. The dithiolate (MBT)2 was not adsorbed from high concentrations of the blend, whereas it was adsorbed from similar concentrations of MBT collector alone. Most of the observed behaviour can be explained by collector solution species reactivity with Cu decreasing in the order MBT⁻ > BDTP⁻ > HMBT. There was no evidence to suggest any surface chemical synergism between the two collectors. For the minerals, competitive chemisorption broadly similar to that for Cu metal was observed, but the formation and adsorption of multilayer molecular CuBDTP or CuMBT was lower, and that of (MBT)2 and HMBT was higher, when the surface availability of Cu was lower than at a native oxide layer. Open circuit potentials for Cu metal, chalcocite and covellite electrodes in 10⁻³ M solution of the collector blend were lower than for the corresponding values in MBT collector alone. For all concentrations in the alkaline pH range, surfaces conditioned in either BDTP alone or the blend were obviously hydrophobic, whereas surfaces conditioned in high concentrations of MBT were not obviously hydrophobic. Some surfaces conditioned sequentially in the two collectors, or in high concentrations of the blend at a pH below 7, were only moderately hydrophobic. Thus, depending on the collector concentration and pH, direct (albeit ex-situ) surface chemical characterisation established the adsorption of different species from a BDTP-MBT blend compared with sequential conditioning in the individual collectors, and hence potentially different hydrophobicities.
Article
Full-text available
The extraction technology for platinum-group metals (PGMs) has changed dramatically in the last 80 years, and the changes are likely to continue for years to come. This article will review advances in PGM extraction, including developments in semi-autogenous and fully autogenous milling; flotation equipment applications for treating high-chrome ores; increases in power densities for future smelting furnaces, and new methods for meeting rising environmental standards.
Article
Full-text available
This paper investigates the effects of thiol collectors: xanthates, dithiophosphates, dithiocarbamates and mixtures of these on the froth flotation performance obtained with a bornite-rich copper sulphide ore from Okiep Copper Mine with a feed grade of 1.8% copper. Batch flotation tests were used to assess the performance in terms of mass-water recovery, sulphur grade-recovery and copper grade-recovery relationships and the Klimpel rate constant for copper recovery. The results showed that the di-ethyl-dithiocarbamate (di C2-DTC) was the weakest collector of copper sulphide minerals. Highest copper recoveries were obtained with the di-ethyldithiophosphate (di C2-DTP), which were accompanied with more watery froths and lower copper grades demonstrating frothing properties in addition to collector action. Superior copper recoveries were obtained with the 90% ethyl xanthate (C2-X):10% di-ethyldithiophosphate (di C2-DTP) and 90% ethyl xanthate (C2-X):10% di-ethyl-dithiocarbamate (di C2-DTC) collector mixtures compared to that obtained with ethyl xanthate at an equivalent collector dosage of 0.139 mol/ton ore (a dosage equivalent to 20 g sodium ethyl xanthate per ton ore). A superior copper grade was obtained with the 90% ethyl xanthate:10% di-ethyl-dithiocarbamate collector mixture at a dosage of 0.0695 mol/ton ore compared to that obtained with ethyl xanthate at the same equivalent dosage.
Article
Synergism may be defined as the enhanced effect obtained from the use of a combination of reagents relative to their individual action. In flotation synergistic effects between collectors and between collectors and frothers have long been recognized in plant practice, although little attention has been paid to them in laboratory studies. The study of such effects between KEtX and sodium diethyl dithiocarbamate (Dtc) in reaction with heazlewoodite (Ni3S2) is described in this paper. Correlation was obtained between flotation recoveries obtained in a modified Hallimond tube, adsorption isotherms for the reagents on the mineral surface and simple measurements of surface tension carried out on a dropping mercury electrode at controlled potentials (the electrocapillary phenomenon). It was hoped that these techniques, together with cyclic voltammetry studies, could be developed into a compact method for studying synergism both for the evaluation of potentially useful systems and to obtain a better understanding of the underlying theoretical principles.
Article
Sulfide mineral systems fall into those in which thiol collectors are adsorbed chemically and those in which dimer formation results from electrochemical oxidation of collector on the mineral surface. Galena, chalcocite, and sphalerite fall into the first category, while pyrite falls into the second. Chalcopyrite exhibits both chemisorption and dimer formation.
Article
The reliability of a set of flotation results is key to minimizing project risk, either at the commissioning of a concentrator or at the point of implementing an improvement to an existing concentrator operation. High-confidence flotation testing (HCFT) was developed for this purpose and is part of the list of technologies at various scales used by Xstrata Process Support (XPS) in addressing these projects. The methodology is based on two principles: one, to ensure that the ore sample is representative and has been well-blended and subsampled; two, to perform the flotation tests in sufficient numbers of replicates with appropriate quality controls, so as to improve the reproducibility of the test data. Across ten years of research on this methodology at Xstrata Process Support, Sudbury, several improvements to the HCFT method and complementary connections between sampling and quantitative mineralogy have been developed. Two case studies are reviewed. These show the capability of this system in both optimizing an existing concentrator operation and in serving a new mine scenario. Further work to improve the efficiency of this procedure has been identified.
Article
The concentrator has a 3075 mtpd copper flotation circuit capable of running twenty-four hours a day under the direct control of an optimizing supervisory computer. Three main streams, continuously monitored by an XRF analyzer, supply circuit information. Circuit efficiency calculations and target setpoints allow the computer to determine the optimum direction based on the grade/recovery relationship. Circuit manipulation is accomplished by pumping of collector and frother reagents together with control of flotation bank pulp levels. The former uses computer controlled diaphragm pumps and the latter is achieved by control loops utilizing a float type level transmitter, variable position dart plugs and a process computer working to setpoints determined by the optimizing computer.
Article
The promoters have found diverse applications in the flotation treatment of metallic and sulphide base and precious metals. Outstanding features include high collecting activity and selectivity, particularly in regard to iron sulphide minerals in alkaline circuit. The greatest usage of dithiophosphates lies in combination with another collector type to enhance the collecting properties of each.-J.M.H.
Article
Electrochemical investigations of the flotation of sulphide minerals are reviewed. Flotation with thiol collectors is interpreted in terms of a 'mixed potential' model. In this model, the process leading to hydrophobicity is the anodic oxidation of the collector at the mineral surface; this is driven by the cathodic reduction of oxygen. Electrochemical studies have identified the products of anodic oxidation as chemisorbed collectors, metal collector compounds, and dithiolates; the products formed in each situation depend on the collector used, the mineral under study and the pretreatment of the mineral surface. Investigations on galena, pyrite and chalcocite are discussed. Electrochemical and X-ray photoelectron spectroscopic studies have been used to determine the surface oxidation products of sulphide minerals in order to elucidate the mechanism of collectorless flotation. The mixed potential mechanism allows consideration of the methods of inhibiting flotation of sulphides with thiols. Examples of depressant action are presented and the relevance of electrochemical investigations to practical flotation is discussed. (Author's abstract)-J.M.H.
Article
The theory of stationary electrode polarography for both single scan and cyclic triangular wave experiments has been extended to systems in which preceding, following, or catalytic (cyclic) chemical reactions are coupled with reversible or irreversible charge transfers. A numerical method was developed for solving the integral equations obtained from the boundary value problems, and extensive data were calculated which permit construction of stationary electrode polarograms from theory. Correlations of kinetic and experimental parameters made it possible to develop diagnostic criteria so that unknown systems can be characterized by studying the variation of peak current, half-peak potential, or ratio of anodic to cathodic peak currents as a function of rate of voltage scan.
Article
Xanthate characteristics with relation to its hydrocarbon chain length has been considered. The free energy associated with one -CH2 group in homologous xanthates was calculated based on the standard redox potential of X2/X− couple and solubility products of transient metal xanthates. The estimated free energy using each method was found to be 690–920 cal and 799–824 cal, respectively, and was in good agreement with that for various homologues.
Article
The paper describes how sulphydryl collector chemistry affects the performance of base-metal sulphide flotation, particularly in terms of kinetics and selectivity. The influences of chemical manipulation on the major types of sulphydryl collectors are illustrated.Examples used include plant and laboratory data from flotation systems involving the following ore types:- •porphyry copper - molybdenum•sedimentary copper•copper - zinc•massive sulphide•copper-lead-zinc complex sulphideSome new developments in base-metal sulphide collectors are described. The responses of different collector types to variation in pulp Eh and pH are illustrated.
Article
Surface tension and contact angle experiments were conducted aiming at studying the synergism of surfactant mixtures on the reduction of surface tension of aqueous solutions and on the hydrophobicity of mineral surfaces. The following systems were studied: 1) Potassium ethyl xanthate with sodium oleate mixtures for pyrite and gold, and 2) Sodium oleate with cetyl trimethyl ammonium bromide (CTAB) mixtures for fluorite and calcite. A synergistic effect of combined reagents was found to enhance the hydrophobicity and also to reduce the surface tension, depending mainly on the proportion of the mixtures.
Article
Adsorption of xanthates on galena, pyrite and sphalerite in the virtual absence of oxygen is presented as a function of xanthate concentration and pH. Adsorption of ethyl xanthate on galena occurs at monolayer coverage independent of pH. In the case of pyrite and sphalerite, adsorption of short-chain xanthates occurs below monolayer coverage at pH values below 8.
Article
From the examination of data from detailed plant surveys and associated laboratory batch testing, the principal effects of particle size in flotation have been identified. The current state of knowledge concerning the role of this variable is discussed in terms of the evidence presented. It is concluded that the minimum degree of hydrophobicity necessary for the flotation of a particle depends upon its size and as a result, recovery-size curves are a valuable diagnostic aid to the assessment of flotation performance. Entrainment is shown to be an important contributory mechanism to the recovery of fine particles which, when coupled with a low rate of genuine flotation, can account for much of the observed behaviour of such fines. The significance of particle size and its consequences in flotation research, in plant operations and in control schemes has been under-rated. The separate conditioning or flotation or both of separate size fractions seems inevitable as ores become increasingly difficult to concentrate.
Article
This book is the premier text on the properties and applications of surfactants. The third edition is completely updated and revised, including new information on gemini surfactants (a new type of powerful surfactant), superspreading (or superwetting) by aqueous surfactant solutions of highly hydrophobic surfaces (important in agricultural applications), and dynamic surface tension (an important interfacial property not covered in the first two editions). * Clearly explains the mechanisms by which surfactants operate in interfacial processes * Uses a minimum of mathematics in explanation of topics, making it easy-to-understand and very user-friendly * Problems are included at the end of each chapter * Includes many tables of data as reference that are not compiled elsewhere * Milton J Rosen is an expert in the field of Surfactant research
Article
The reactions between chalcopyrite, CuFeS2, marcasite, FeS2, pentlandite, (Fe,Ni)9S8, pyrrhotite, FeS1-x, and troilite, FeS, and aqueous solutions of potassium ethylxanthate and decylxanthate have been studied. X-ray photoelectron spectroscopy (XPS) has been used to determine the oxidation state of copper at the chalcopyrite surface. The XPS measurements showed that copper at the surfaces of chalcopyrite is present as copper(I) Qualitative analysis of the alkylxanthate species present on the mineral surfaces after treatment with an aqueous solution of potassium alkylxanthate has been made by means of diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Solid copper(I) alkylxanthate is the only alkylxanthate species found on the chalcopyrite surfaces. Alkylxanthate ions are sorbed to chalcopyrite surfaces according to a dissolution—precipitation mechanism where copper(I) species are dissolved from the chalcopyrite surfaces, a concentration gradient of copper(I) species is formed around the chalcopyrite particles, and copper(I) alkylxanthate precipitates back on the chalcopyrite surface in the presence of small concentrations of alkylxanthate ions. Large amounts of dialkyl dixanthogen formed in a redox reaction between alkylxanthate ions and highly oxidising species on the marcasite surfaces are present on the marcasite surfaces after treatment with an aqueous solution of alkylxanthate. This oxidising agent is most probably a minor oxidation product of the disulphide ions in marcasite, e.g. S2O2−8 and/or S2O2−7 ions, which are probably formed during grinding in air. Dialkyl dixanthogen is the only alkylxanthate species found on the surfaces of pentlandite and pyrrhotite, but the amounts are substantially smaller than on marcasite. The sulphur in pentlandite and pyrrhotite is most probably mainly oxidised to sulphate ions, but very small amounts of a strong oxidising agent seem to be formed as well. No alkylxanthate species have been found on the surfaces of troilite after treatment with alkylxanthate ions. The relationship between the kind of alkylxanthate species formed on the sulphide mineral after treatment with an aqueous alkali alkylxanthate solution and the structure of the mineral is discussed.
Article
Electrochemical studies were conducted to determine if ions present in the Copper Cliff process water at INCa's Sudbury complex were interactive on pentlandite and pyrrhotite surfaces. It was found that Ca2+, S2O3 2− and SO4 2− were significantly surface active at the normal process pH. From comparisons of other voltammetric traces obtained for xanthate interactions it was concluded that these ions would influence the extent of adsorption of X− by the sulphide minerals as well as control the onset of hydrophobicity. Simple hydrophobicity tests confirmed that S2O3 2− and Ca2+ competed with xanthate for adsorption on the surface of pentlandite whereas only Ca2+ increased the xanthate dosage required to render pyrrhotite hydrophobic. Mechanisms for pentlandite and pyrrhotite flotability arising from xanthate reactions were put forward. Xanthate chemisorption took place on the nickel sites in the case of pentlandite, which was oxidized at the surface to form dixanthogen which enhanced hydrophobicity. No xanthate chemisorption took place on pyrrhotite, the surface being rendered hydrophobic by dixanthogen which was formed as part of a mixed potential reaction involving with the normal pyrrhotite oxidation process.
Article
Electrochemical behavior of chalcopyrite was investigated in the absence and presence of dithiophosphate (DTP) and dithiophosphinate (DTPI), selective thiols against Fe-sulfides in the flotation of sulfide ores, in potentiostatically controlled electrochemical condition. Diffuse reflectance Fourier transformation (DRIFT) spectroscopy was applied to determine the type of adsorbed collector species, and Hallimond tube flotation tests were performed to clarify the role of polarization potential and thiol collectors on the floatability of chalcopyrite. DRIFT spectroscopy study proposed that dithiolate of DTP, (DTP)2, was the major surface compound formed under oxidizing potentials in slightly acidic and neutral conditions. However, DTP species formed on mineral surface in alkaline condition could not be determined possibly due to heavy surface coating of metal oxyhydroxides. DTPI species formed on chalcopyrite was found to be in the form of CuDTPI + (DTPI)2. Additionally, presence of adsorbed DTPI, DTPI0, was also detected. Self-induced floatability was significantly high particularly in slightly acidic condition and decreased by increasing pH due to surface coating of metal oxyhydroxides. Addition of both collectors improved the flotation performance at all pH values. However, the positive effect of DTP at high alkaline pH values was lower than that of DTPI. This was attributed to weak collecting property and lower hydrocarbon chain length of DTP compared to DTPI. Effect of pulp potential could not be observed in slightly acidic condition, but it became apparent at higher pHs. Although better flotation responses were obtained in mildly oxidizing potentials, both collectors enlarged the floatability potential range of chalcopyrite.
Article
Using the criteria of recovery and rate, the flotation of the principal copper sulfides and pyrite with sulfhydryl collectors was found to follow the pattern: xanthate > dithiophosphate = thionocarbamate = xanthogen ethyl formate > dixanthogen. Flotation rate was found to be a more sensitive parameter than recovery; especially as near-ultimate recovery is approached. The differing response of these five minerals to the anionic xanthate or dithiophosphate collectors was found to correspond to the mineral semiconductor type. As the pH increases from pH 5 to 10.5 both recovery and rate were generally found to decrease with all the sulphydryl collectors except dixanthogen.
Article
Historically, the process of reagent selection and optimization has been rather informal, reductionistic and frequently based on extension of personal experience from one mineral system or plant to another, gut feeling, anecdotes, and myths. There is no recognized “standard” practice, and the informal process is fraught with pitfalls. The complexity and variability in mineralogy and the complex interactions between chemical, physical-mechanical and operational factors in the plant are invariably ignored in such an approach, and the selected reagent will have a narrow, un-optimized window of performance. Thus the chemical solution to a plant’s demand will not be robust. This approach is also very costly in the long run and adds little to our knowledgebase. In this paper an expanded holistic view of the flotation system is described, and a rational, holistic process is discussed for reagent selection, optimization, and profitable implementation in the plant, using base metal sulfide flotation system as an example. Although such an approach in the flotation system may, at first glance, imply impracticality, an attempt is made in this paper to show that a manageable holistic approach can be practiced and that it is necessary in order to develop robust solutions to metallurgical needs in the plant.
Article
Linear sweep voltammetry has been used to study the electrochemical properties of platinum, copper and copper sulfide electrodes in the absence and in the presence of potassium diethyldithiophosphate. The influence of several variables, namely, sweep rate, solution pH, dithiophosphate concentration, etc. has been studied. Oxidation-reduction reactions at platinum, copper and copper sulfide electrodes are postulated to explain the observations. In the absence of any dithiophosphate in solution, the initial oxidation reaction is probably the discharge of hydroxyl ions. Dithiophosphate ions inhibit the oxidation reaction. Under suitable conditions, bis(diethoxythiophosphoryl)disulfide forms at platinum, whereas cuprous and cupric dithiophosphates form at copper and copper sulfide. The oxidation products can be reduced at the respective electrodes, however, the reactions are generally irreversible.
Article
Electroflotation tests were conducted with a chalcopyrite fines-sodium diethyldithiocarbamate system with normal variables such as effect of concentration, pH of the collector and conditioning time, separately with oxygen and hydrogen bubbles generated electrolytically. Studies were attempted to check the effect of pH changes and electrolyte gases on the surface products. The surface products were extracted with carbon tetrachloride and analysed by UV-visible and I.R. spectrophotometric methods. It was found from the results that the qualitative nature of the surface product was unaffected by the above parameters.
Article
On the basis of an analysis by spectrophotometric methods, it is concluded that, when xanthate reacts with a sulfide mineral surface, in general either dixanthogen or the metal xanthate is formed and not a mixture of the two. Exceptions are covellite and molybdenite. The nature of the reaction products does not vary with pH of the solution nor with the chain length of the xanthate homologue used. The results agree with rest potential measurements in showing that dixanthogen is formed on those minerals that assume a rest potential greater than the equilibpotential for the reduction of dixanthogen or xanthate.
Article
Thermochemical measurements were made of the reactions between sodium cyclohexyl dithiocarbamate, potassium n-butyl xanthate and mixtures thereof with pyrite at pH = 4. The initial steady state heat of adsorption for the potassium n-butyl xanthate and sodium cyclohexyl dithiocarbamate was −67 kJ/mole. When a mixture of these reagents was used this increased to −90 kJ/mole. In all cases the pH increased during the experiments. When FeS04 replaced the pyrite the ΔH for the xanthate decreased to −43.9 kJ/mole. The results indicated that for the xanthate, the metal thiolate was formed and subsequently oxidised to dixanthogen. The latter reaction did not occur in the case of the dithiocarbamate, however the extent of the first reaction between the dithiocarbamate and pyrite was controlled by proton availability. For the mixture of reagents it is proposed that the dithiocarbamate adsorbs preferentially due to its faster adsorption kinetics and the more stable nature of the surface complex. The dixanthogen species formed then aggregates around the “anchors” and results in enhanced hydrophobicity. This will contribute towards the enhanced flotation performance obtained when mixtures collectors are used [1].
Article
The adsorption of ethyl xanthate on pyrite, pyrrhotite, chalcopyrite and sphalerite has been studied using FTIR-ATR techniques and microflotation. Non-activated minerals and minerals activated with copper sulfate have been investigated at different pH values and xanthate concentrations. Diethyl dixanthogen is formed on non-activated pyrite, pyrrhotite and chalcopyrite. Iron xanthate co-exists with diethyl dixanthogen as a monolayer form on pyrite and a copper xanthate surface compound co-exists with diethyl dixanthogen on chalcopyrite. After copper sulfate activation a copper (I) type xanthate compound exists on all of the minerals studied. Acidic pH favours the adsorption of ethyl xanthate on non-activated minerals, whereas the neutral pH range is most favourable for xanthate adsorption on activated minerals.
Article
Adsorption of diethyldithiocarbamate (DTC) on covellite, cuprite and tenorite was investigated under different experimental conditions. The qualitative nature of surface species formed at the interface was examined by selective solvent extraction and UV—visible spectrophotometric techniques. The presence of surface species such as [Cu(DTC)]+, Cu(DTC)2 and Cu(I) DTC at different concentrations of the reagent and pH of the suspension was investigated. The results of this study indicate a surface reaction between DTC ligand molecules and surface copper sites. As a result of interaction with DTC, cations on the mineral surface are dislodged from the lattice and precipitated on the surface as copper dithiocarbamate complexes. Depending on the concentration of DTC, two types of copper complexes, i.e. [Cu(DTC)]+ at low concentration and Cu(DTC)2 at higher concentration, are noted on copper(II) substrates, whereas on cuprite Cu(I) DTC was formed along with [Cu(DTC)]+ and Cu(DTC)2. From the kinetic study, the overall adsorption was found to be mainly controlled by diffusion processes.
Article
The subject of inter facing plant grinding and flotation operations is addressed. Use is made of mineral distribution by size in the grinding circuit product combined with size-recovery performance of the flotation circuit. This establishes criteria for defining the economic value of the product from a grinding circuit. A case study is presented for illustration.
Article
The potential beneficial effects of using two or more reagents are widely known and using mixtures of collectors in flotation has shown to increase both the recovery and selectivity simultaneously. In this work, the adsorption behaviour of sodium isopropyl xanthate (SIPX) and dithiophosphinate (DTPI) was investigated. These collectors were selected as strong and selective collectors respectively for the flotation of chalcopyrite. The adsorption behaviour of these collectors, combined in different ratios and order of addition was investigated by electrochemical and adsorption experiments at pH 9.2.The results showed that both the ratio of collectors in mixtures and sequence of addition were important. The maximum synergistic effect was observed at 30:70 (SIPX:DTPI) ratio when DTPI was added initially and at 50:50 ratio when the collectors were added simultaneously.
Physicochemical properties of some flotation reagents and their salts with ions of heavy iron-ferrous metals
  • I A Kakovsky
Kakovsky, I.A., 1957. Physicochemical properties of some flotation reagents and their salts with ions of heavy iron-ferrous metals. In: Proceedings of 2nd International Congress Surface Activity, London, vol. 4, pp. 225-237.
Personal Communication. Rustenburg. Plaskin, I Investigations of the possible intensification of the flotation process using combinations of collectors. (Mintek translation Feb
  • M K N Oertel
  • V A Glembotskii
  • A M Okolovich
Oertel, M.K., 1981. Personal Communication. Rustenburg. Plaskin, I.N., Glembotskii, V.A. and Okolovich, A.M., 1954. Investigations of the possible intensification of the flotation process using combinations of collectors. (Mintek translation Feb. 1989). Naachnye Soobshcheniya Institut Gonnogo dela Imeni AA Skochinskogo, Akademiya Nauk SSSR, No. 1, pp. 213– 224.
Laboratory testwork of mixed xanthates for the raglan ore
  • T Deng
  • S Yu
  • N O Lotter
  • A Di Feo
Deng, T., Yu, S., Lotter, N.O., Di Feo, A., 2010. Laboratory testwork of mixed xanthates for the raglan ore. In: Proceedings of Canadian Mineral Processors, Ottawa, January 2010, Paper No. 16, pp. 253-268.
The dithiocarbamates and related compounds
  • G D Thorn
  • R A Ludwig
Thorn, G.D., Ludwig, R.A., 1962. The dithiocarbamates and related compounds. Elsevier Publishing Co., Amsterdam, New York.
Plant scale trial of isobutyl xanthate at Raglan concentrator using reference distributions
  • N O Lotter
  • G Comeau
  • L J Kormos
  • D Fragomeni
  • A Di Feo
Lotter, N.O., Comeau, G., Kormos, L.J., Fragomeni, D., Di Feo, A., 2009. Plant scale trial of isobutyl xanthate at Raglan concentrator using reference distributions. In: Proceedings of Canadian Mineral Processors, Ottawa, Paper No. 6, pp. 79-105.
Trial of X-333 Xanthate Mixture at Amplats. South Africa
  • N O Lotter
  • J Aupiais
Lotter, N.O., Aupiais, J., 1996. Trial of X-333 Xanthate Mixture at Amplats. South Africa, Personal Communication.
Experiences with computer control of the flotation at Kidd Creek Mines
  • P E Thwaites
Thwaites, P.E., 1986. Experiences with computer control of the flotation at Kidd Creek Mines. In: Proceedings of III Canadian Industrial Computer Society, Montreal, pp. 56-58.
Principles of Flotation. Australian Institute of Mining and Metallurgy
  • K L Sutherland
  • I W Wark
Sutherland, K.L., Wark, I.W., 1955. Principles of Flotation. Australian Institute of Mining and Metallurgy, Melbourne. pp. 95-101.
A quality control model for the development of high-confidence flotation test data
  • N O Lotter
Lotter, N.O., 1995. A quality control model for the development of high-confidence flotation test data. M.Sc. (Chem. Eng.) Thesis. University of Cape Town, South Africa, June 1995, 188 pp.