Article

Coal-Gold Agglomeration: An Alternative Separation Process in Gold Recovery

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Abstract

Considering the increasing environmental concerns and the potential for small gold deposits to be exploited in the future, the uses of environmentally friendly processes are essential. Recent developments point to the potential for greatly increased plant performance through a separation process that combines the cyanide and flotation processes. In addition, this kind of alternative treatment processes to the traditional gold recovery processes may reduce the environmental risks of present small‐scale gold mining. Gold recovery processes that applied to different types of gold bearing ore deposits show that the type of deposits plays an important role for the selection of mineral processing technologies in the production of gold and other precious metals. In the last 25 years, different alternative processes have been investigated on gold deposits located in areas where environmental issues are a great concern. In 1988, gold particles were first recovered by successful pilot trial of coal‐gold agglomeration (CGA) process in Australia. The current paper reviews the importance of CGA in the production of gold ore and identifies areas for further development work.

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... Several gold recovery processes were proven to efficiently beneficiate a gold ore on an economical profitable and environment friendly way [4]. Coal-oil gold agglomeration (CGA) process is one of these alternatives. ...
... Further, the oil droplets spreading on the coal surfaces form the "oil bridges" which combine the coal particles to agglomerates (Fig.1 a) due to the interfacial tension of the oil and capillary attraction of the oil bridges between particles. Once coal-oil agglomerates form, they are added into gold-bearing ore slurry under intensive agitation; the gold particles thus collide, contact and attach with the coal-oil agglomerates, and eventually penetrate into the agglomerates ( Fig.1 b) [4]. Then, the CGA agglomerates can be recovered by flotation or other methods (e.g. ...
... coal fines, oil, collectors, lime). In addition, the tank storage should be much less than it is required for a conventional cyanidation plant, since the residence time needed for CGA is low [4]. ...
Article
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This study aimed to investigate the applicability of coal-oil gold agglomeration (CGA) assisted flotation to recover gold from a refractory ore. The ore with the grade of 2-5 g/t was tested with the CGA-flotation process in six different size fractions from 38 to 300 urn using different collector types and dosages. In addition, the flotation without CGA was performed under the same condition for comparison. The results showed that the higher gold grade and recovery were achieved by applying the CGA-flotation, compared with the flotation without CGA. More than 20-60 times grade increase from the head grade was obtained with CGA-flotation. The elemental analysis of gold and sulphur explained their relationship with gold recovery. The results well indicated the applicability of CGA to upgrade the refractory gold ore.
... Several gold recovery processes were proven to efficiently beneficiate a gold ore on an economical profitable and environment friendly way [4]. Coal-oil gold agglomeration (CGA) process is one of these alternatives. ...
... Further, the oil droplets spreading on the coal surfaces form the "oil bridges" which combine the coal particles to agglomerates (Fig.1 a) due to the interfacial tension of the oil and capillary attraction of the oil bridges between particles. Once coal-oil agglomerates form, they are added into gold-bearing ore slurry under intensive agitation; the gold particles thus collide, contact and attach with the coal-oil agglomerates, and eventually penetrate into the agglomerates ( Fig.1 b) [4]. Then, the CGA agglomerates can be recovered by flotation or other methods (e.g. ...
... coal fines, oil, collectors, lime). In addition, the tank storage should be much less than it is required for a conventional cyanidation plant, since the residence time needed for CGA is low [4]. ...
... Centrifugal dewatering is a process of removing the processed water from solids or products by applying high gravitational forces. The centrifugal force, G, may be calculated based on the rotational speed (or angular velocity) ω of the vessel and radius r of the same centrifuge vessel [12][13][14][15][16][17][18]: ...
... Centrifugal dewatering is a widely used method for the separation of solids from liquids in several industries due to higher gravitational forces acting on the particles [12][13][14][15]. In this method, if the applied centrifugal force created by the angular velocity of a rotating basket is larger than capillary force (5), liquid in the capillary tubes will be spontaneously removed from the filter cakes [3]. ...
... Centrifugal dewatering is a process of removing the processed water from solids or products by applying high gravitational forces. The centrifugal force, G, may be calculated based on the rotational speed (or angular velocity) ω of the vessel and radius r of the same centrifuge vessel [12][13][14][15][16][17][18]: ...
... Centrifugal dewatering is a widely used method for the separation of solids from liquids in several industries due to higher gravitational forces acting on the particles [12][13][14][15]. In this method, if the applied centrifugal force created by the angular velocity of a rotating basket is larger than capillary force (5), liquid in the capillary tubes will be spontaneously removed from the filter cakes [3]. ...
Article
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An air pressure-assisted centrifugal dewatering method was developed and used for the dewatering of concentrated finesulfide particles, such as sphalerite, galena, and chalcopyrite. This filtration method was mainly designed to increase the filtration rate during the drainage cycle and, hence, produce drier filter cakes, which in turn could reduce the cost and emission problems/concerns of thermal dryers in the preparation plants. Several dewatering parameters, including applied pressure, centrifugal force (G-force), spin time, cake thickness, and surface hydrophobization, were tested to optimize the processing conditions. Test results showed that, at higher air pressure and centrifugal force, the cake moisture reduction was more than 70%, depending on the testing conditions. As a result, it can be-concluded that the novel filtration method effectively works on the dewatering of fine particles (–150 μm).
... Furthermore, the oil droplets spreading on the coal surfaces form the "oil bridges" which combine the coal particles to agglomerate due to the interfacial tension of the oil and capillary attraction of the oil bridges between particles. Once coal-oil agglomerates form, they are added into gold-bearing ore slurry under intensive agitation; the gold particles thus collide, contact, and attach with the coal-oil agglomerates, and eventually penetrate into the agglomerates [115]. Then, the CGA agglomerates can be recovered by flotation or other methods (e.g., screening), dewatering to reject water and coal, and burning remained agglomerates to extract gold [36,113]. ...
Article
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This paper summarizes and discusses previous investigations into the correlation between the rheology and flotation process of fine particle suspensions. This summary provides a better understanding of the challenges and current status of this subject and useful feedback based on the revision of relevant theories and practical implications for fine particle characterization and processing. Such processes include the sustainable beneficiation of complex ores and wastes for valuable material extraction and the segregation of toxic substances. For example, there has been increasing demand for the beneficiation of complex ores often carrying the values (e.g., critical raw materials) in fine grains, due to the noticeable decrease in the accessibility of high-grade and easily extractable ores. To maintain the sustainable use of limited resources, the effective beneficiation of complex ores is urgently required. It can be successfully achieved only with selective particle/mineral dispersion/liberation and the assistance of mineralogical and fine particle characterization including a proper understanding of the rheological behavior of complex ores in the context of fine particle separation/processing. In correlating flotation with suspension rheology, previous works were summarized and we found that the modeling of their correlations as well as comprehensive contributions of pulp and froth rheology on flotation performance have been studied very limitedly, and comprehensive developments in these aspects are thus strongly suggested.
... Oil serves as a bridge between coal and gold particles, used oils are diesel oil, kerosene and vegetable oil as agglomerating liquids to process gold-containing materials, while coal acts as a carrier and facilitates effective separation of the gold-bearing agglomerates. The CGA method has proven to be effective if used to process liberated/free gold particles, such as those contained within alluvial deposits and some process tailings (Akcil et al., 2009;Calvez et al., 1998;Kotze and Petersen, 2000). The CGA method is a quicker, cleaner and more effective method than conventional gold processing techniques, including cyanidation. ...
Article
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This paper presents an overview of the various methodologies used in the recovery of gold from secondary sources. Gold recovery is interesting due to its vast industrial applications, high market prices and extensively used precious metal, the sanctuary value attributed to gold during international political and economical crises, and the limited resource of this metal may explain the recent increasing gold share value. The state of art in recovery of gold from spent sources by pyrometallurgy; hydrometallurgy; bio-hydrometallurgy techniques is highlighted in this paper. This article also provides an overview of past achievements and present scenario of recovery studies carried out on the use of some promising methods which could serve as an economical means for recovering gold. The present review also highlights the used varieties of leaching, cementing, reducing agents, peeling, coagulants, adsorbents, agglomeration solvents, ion exchange resins and bio-sorbents in real situations and hopes to provide insights into recovery of gold from spent sources. Evaluation of lucrative and environmentally friendly technologies to recover gold from primary and secondary spent sources was made in this study.
... Such minerals include mainly the metallic sulphides gangue [3,4]. The presence of low amounts of sulphides in the ore up to 5% chalcopyrite is reported to have little effect on gold recoveries [5,6]. ...
... Разом з тим, сьогодні такі дослідження проводять в ряді закордонних наукових центрів, зокрема, Туреччини, Китаю, Танзанії (Akcil, Wu, & Aksay, 2009;Mlaki, Katima, & Kimweri, 2011;Sen, Akar, Cilingir, Malayoglu, Tanriverdi, & Ipekoglu, 2013;Kopgli et al., 2015). Це також актуалізує сучасні зусилля в розвитку вітчизняних технологій процесу адгезійного збагачення золота. ...
... Разом з тим, сьогодні такі дослідження проводять в ряді закордонних наукових центрів, зокрема, Туреччини, Китаю, Танзанії (Akcil, Wu, & Aksay, 2009;Mlaki, Katima, & Kimweri, 2011;Sen, Akar, Cilingir, Malayoglu, Tanriverdi, & Ipekoglu, 2013;Kopgli et al., 2015). Це також актуалізує сучасні зусилля в розвитку вітчизняних технологій процесу адгезійного збагачення золота. ...
Article
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Purpose. To summarize domestic experience in creating technology for adhesive gold dressing and to describe key research results. Methods. Laboratory experimental and pilot research into the process of obtaining adhesively active coal and oil granules carrying particles of gold and adhesive extraction of nano-, thin-and fine gold from ore slurry, preparing carrying granules and their microscopy, spectroscopy of the water phase, designing an experiment to obtain a statistical model of adhesive abilities of coal and oil granules-carriers. Findings. Regime map of oil granulation process to produce coal granules carrying particles of gold was experimentally obtained. Rational regime parameters for pelleting granules have been determined: consumption of coupling reagent; granulometric composition of initial coal; slurry concentration; pelleting duration; slurry agitation intensity. It is recommended to use as original material coal with ash content A d = 10%; particle size-0.074 mm. Oil agent is oil of brand M100 and kerosene. The rational process schematics for adhesive gold dressing was developed, in particular, by cleaning flotation, which increases the extraction of Au up to 90% and allows to reach its environmental cleanliness nearly at the level of flotation. It is discovered for the first time that when the surface of coal oil granules is modified by crown ether, gold nanoparticles of the size 20-30 nm concentrate on it, which can be explained by the formation of supramolecular ensemble "crown ether-nano-gold". The rational mode of pelleting has been substantiated and patented for the turbulence estimated by Reynolds number Re within 900-12000. Theoretical foundations of the mechanism for producing coal and oil granules-carriers were developed, including its phenomenological scheme. Subprocesses lying behind adhesive "coal-oil" contact have been analyzed and the elementary act of aggregation and granules-carriers' formation has been investigated. The experiment was designed to obtain statistical models that describe the impact of various factors on stickability of "adhesive-substrate" ("coal-oil granules-gold") combination. Originality. The scientific basis was laid and experimental testing was performed to prove feasibility of gold dressing adhesive technology. Rational regime schematics and process parameters of adhesive gold dressing were grounded , it was discovered that under the impact of crown ether nano-gold concentrates on the surface of granules-carriers. Practical implications. The results of laboratory and bench experimental studies can be used with sufficient accuracy to implement adhesive gold dressing of fine and nano-size particles within a "few hundred microns-a few tens of nanometers".
... The spherical agglomeration process offers the possibility of a selective agglomeration of one specific solid component out of a heterogeneous suspension (Aktaş, 2002;Bensakhria et al., 2001). Akcil et al. (2009) showed that a selective agglomeration of gold out of a suspension of mineral matter, coal and gold particles results in a gold recovery of up to 95.5 %. Typically, primary particle sizes for spherical agglomeration processes range from 0.1 µm up to 425 µm (Dawei et al., 1986;Drzymala et al., 1991;Gürses et al., 1996;House and Veal, 1989;Kelsall and Pitt, 1987;Laskowski and Yu, 2000;Petela et al., 1995;Sadowski, 1995;Sirianni et al., 1969;Slaghuis and Ferreira, 1987;Wahl and Baker, 1971). ...
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This study aims to an automated evaluation of contact angles in a three-phase system of selective agglomeration in liquids. Wetting properties, quantified by contact angles, are essential in many industries and their processes. Selective agglomeration as a three-phase system consists of a suspension liquid, a heterogeneous solid phase and an immiscible binding liquid. It offers the chance of establishing more efficient separation processes because of the shape-dependent wetting properties of fine particles (size ≤ 10 µm). In the present paper, an experimental setup for contact angle measurements of fine particles based on the Sessile Drop Method is described. Moreover, a new algorithm is discussed, which can be used to automatically compute contact angles from image data captured by a high-speed camera. The algorithm uses a marker-based watershed transform to segment the image data into regions representing the droplet, the carrier plate coated by fine particles, and the background. The main idea is a parametric modelling approach forthe time-dependent droplet’s contour by an ellipse. The results show that the development of the dynamic contact angles towards a static contact angle can be efficiently determined based on this novel technique. These findings are useful for a detailed discrimination of wetting properties of spherical and irregularly shaped particles as well as their wetting kinetics. Also, a better understanding of selective agglomeration processes will be promoted by this user-friendly method.
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The aim was to assess the technological feasibility of generating sodium cyanide by coal gasification, to study the effects of the process parameters (temperature, experiment duration, coal type) on the concentration of sodium cyanide in the resulting solutions, as well as to identify optimal modes of the process. Experiments were carried out on a laboratory setup consisting of a tubular cylindrical furnace equipped with a working compartment in the form of a corundum tube. Lignite and charcoal, preliminarily crushed to increase the specific surface area, were investigated. A solution of sodium cyanide was produced by sorption of gaseous hydrocyanic acid (a syngas component) with a sodium carbonate solution. A NaOH solution (pH = 10) installed in an ice bath was used in the system of absorbers. The content of sodium cyanide in the solution was determined by the titrimetric method. The HSC Chemistry 5.1 software package was used for thermodynamic calculations. During the gasification of charcoal in the temperature range 600–800oC, sodium cyanide solutions with a concentration of 0.03–0.08 wt% were obtained. An increase in temperature from 600 to 900oC led to a 4-fold decrease in the concentration of sodium cyanide in an alkaline solution, under the same duration of the experiments. A regression equation was derived for the dependence of the NaCN concentration in solution on the temperature of coal gasification and the duration of the process. It was shown that the generation of sodium cyanide by coal gasification under laboratory conditions yields sodium cyanide concentrations in solution comparable to those used for gold cyanidation at gold recovery plants. The installation of sodium cyanide generation lines directly at the production areas of gold recovery plants will reduce the production costs by eliminating expenses for purchasing, transporting and storing reagents.
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Gold recovery methods, which include gravity, flotation, amalgamation and leaching are again under scrutiny today to improve the recovery and decrease the deleterious affects of the processes on environment and human health. On the other hand, new gold recovery methods, which should be less harmful to the environment, in addition to providing higher recoveries than conventional gold processing methods, are also being investigated.In this study, the effects of the assay and particle size of gold ores on the efficiency of the coal-oil-gold agglomeration processes are investigated experimentally. The effects of these parameters are very important for determining the process efficiency for different ore types. In order to establish the effects of the parameters mentioned above, artificial ores, which have different grades and particle sizes, were utilized as feed materials in the experiments. In last decade, many researchers have studied the optimum oil, coal type and their consumption. Very encouraging results have been obtained (over 90% recovery) by working with high oil and coal consumption. In this study, the experiments were done by using these materials at minimum dosages to provide a method in the range of economic availability. At the end of our studies, it can be clearly said that applying the coal-oil-gold agglomeration method to assist gold flotation gives more desirable results in view of the agglomeration reagents and material consumption.
Article
The recovery of arsenopyrite from an arsenopyrite/pyrite ore is desirable for a number of reasons. This can be optimized using a two stage flotation process in which a dithiophosphate is added at pH=11 in the first stage and copper sulphate and a dithiocarbamate in the second stage. It was found that better separations were obtained when aged ore was used. It was possible to simulate this ageing process by heating. Various alkyl functional groups of the collectors were tested and the best separations were obtained using sodium isobutyl dithiophosphate and a mixture of 10% : 90% sodium cyclohexyl : n-propyl dithiocarbamate. This suite of collectors led to a recovery of 74.8% arsenopyrite and 8.4% pyrite with grades of 37.9% arsenopyrite and 11.6% pyrite respectively. The grades of gold in the feed, concentrate and tailings for these conditions were 8.10 g/ton, 271 g/ton and 2.55 g/ton respectively. This represented a gold recovery of 83.6%.
Article
Fundamental studies were undertaken to evaluate the underlying principles by which gold is recovered by coal-oil agglomerates. The effects of various parameters such as oil:coal ratios, agglomerate:ore ratios, pH and coal particle size on gold recovery were evaluated using synthetic gold bearing samples; bituminous coal; and diesel oil and kerosene. The effects of sulfides on gold recovery and the depth of gold particle penetration within the agglomerates were also investigated. Results showed that gold recovery was increased by increasing agglomerate:ore ratio, decreasing oil:coal ratio and decreasing coal particle size. There was no significant difference in gold recoveries at pH range of 4–12 and at up to 5% sulfides in the feed. Microscopic studies indicated that at prolonged mixing time, some gold particles were observed to have penetrated the agglomerates some 60 μm from the surface.
Article
Oil agglomeration is an effective technique for recovering and reducing the ash of coal fines. In this study, the effects of some parameters that markedly influence the effectiveness of selective oil agglomeration, such as solids concentration, amount of agglomeration oil and agglomeration time, on the recovery of agglomerate and the ash and the pyritic sulphur content of the agglomerates were investigated. In order to delineate the relation between the formation rate of coal–oil agglomerates and the removal of ash and pyritic sulphur, the rates of agglomeration for Balkaya and Aşkale lignites were also calculated by using experimental data. It was found that the success of the process in terms of both recovery and selectivity for lignites was highly dependent on the parameters and control of the agglomeration rate.
Article
Oil agglomeration is a surface property based on the differences in the surface properties of the organic and inorganic constituents of coal. A bituminous coal was agglomerated using kerosene, diesel oil, Kirkuk Crude Petroleum, extract fractions (obtained from Soxhlet extraction)—kerosene or toluene mixtures and toluene. The amounts of bridging oils were varied from 5% to 30% of the initial coal loading. Centrifugal float–sink separations of the coal in dense media were conducted and the results of their grade recovery performances were compared with those of the agglomeration of the particles. Factors affecting the agglomeration performance, such as the amount of bridging oils and washing water, type of bridging oil, solid content of the slurry and finer particles, were determined. The relationship between the agglomerate sizes and their ash content was also determined. Higher recovery values (>95%) were obtained from the agglomeration tests. Extract-oil fraction of the coal extract at various ratios in kerosene decreased the agglomeration recovery from 98.99% to 88.44%. A sharp decrease (from 90.52% to 56.01%) in the recovery was observed for asphaltane fraction of the coal extract in toluene. Increase in finer particle portion in the bulk solids decreased the grade values of the final product.
Article
Using coal–oil agglomeration method for free or native gold recovery has been a research subject for many researchers over the years. In this study, a new approach “coal–oil assisted gold flotation” was used to recover gold particles. The coal–oil–gold agglomeration process considers the preferential wetting of coal and gold particles. The method takes advantage of the greater hydrophobicity and oleophilicity of coal and gold compared to that the most gangue materials. Unlike the previous studies about coal–oil–gold agglomeration, this method uses a very small amount of coal and agglomerating agents. Some experiments were conducted on synthetic gold ore samples to reveal the reaction of the coal–oil assisted gold flotation process against the size and the number of gold particles in the feed. It was observed that there is no significant difference in process gold recoveries for feeds assaying different Au. Although there was a slight decrease for coarse gold particles, the process seems to be effective for the recovery of gold grains as coarse as 300 μm. The decrease in the finest size (<53 μm) is considered to be the decrease in the collision efficiency between the agglomerates and the finest gold particles. The effect of changing coal quantity for constant ore and oil amounts was also investigated. The experiments showed that the process gives very similar results for both artificial and natural ore samples; the best results have been obtained by using 30/1 coal–oil ratio.
Article
This paper is aimed at producing a conceptual model for gold flotation based on the discussion of a number of experimental results where the behaviour of free and refractory gold has been studied under different chemical and physical conditions. A review of the literature suggests that there have been numerous studies on the flotation of free gold particles and refractory sulphides, but these investigations have typically focused on the individual flotation behaviour of each gold bearing species in synthetic mixtures and not when they are present together in “real” ores in the same pulp. The model discussed here shows that the flotation of refractory gold follows a similar trend to the recovery of refractory pyrite and pyrrhotite and is mainly affected by chemical conditions in the pulp such as redox potential, aeration conditions, copper activation, reagent synergism and galvanic interaction. Refractory gold is usually recovered by true flotation that is hydrophobic particle-bubble attachment, unless under certain conditions the physical transport of water and gangue provides a washing effect and detaches some of the sulphide material from the air bubbles. The flotation recovery of free gold is largely affected by physical constraints like the shape and size of the particles, the degree of water and gangue transport to the froth, the stability of the froth, and the extent of bubble loading of sulphide particles which can provide a barrier towards the hydrophobic bubble attachment of free gold. In each individual study the results suggest that the recovery of free gold follows a proportional trend with regard to water and gangue recovery. However, there is an inverse relationship between the true flotation of free and refractory gold due to the fact that free gold particles cannot attach to air bubbles properly in the presence of physical barriers.
Article
In the history of Turkey the first use of cyanide for gold recovery has been at the Ovacik Gold Mine. During one-year test period, this mine has successfully been mining and processing after a complicated and extensive environmental impact procedure. In Turkey about 2500 ton of sodium cyanide are used with about 240 ton of sodium cyanide being used at this mine annually. During the test period, it has been shown that an effluent quality (CNWAD) between 0.06 ppm (min) and 1 ppm (max) was achievable after cyanide destruction with the Inco Process. It was also found that treated effluent values (CNWAD) of process water (decant) were between 0.04 ppm (min) and 0.59 ppm (max). This paper presents a review of the cyanidation and cyanide destruction processes at the Ovacik Gold Mine.
Article
Large quantities of fine coals are generated during mining and preparation stages and a significant portion of these fines is lost as refuse. Oil agglomeration shows promise of being able to minimise fine coal losses and to recover combustible matter from refuse ponds. This paper, based on a detailed literature review, presents: (a) physical-chemical and process engineering principles of oil agglomeration; (b) a comparative summary and specific process highlights of the more developed oil agglomeration processes; and (c) a critical evaluation of oil agglomeration in terms of selection of oil, process benefits and economic aspects.
Article
Gold flotation is often overlooked as a processing option as the precious metal is viewed as being associated with the sulphide particles present in the ore, even when a proportion of the gold is free. Gold does float readily, however, and the free gold can be selectively floated away from an ore containing sulphides. This may be an alternative treatment route for gold room applications where fine gold losses can occur when treating gravity concentrates with pyrite and copper sulphides present. Floating gold from the sulphides could produce a directly smeltable product. Copper sulphides are selectively floated from pyrite ores at high pH's in excess of 11. It is less clear how the free gold behaves under these conditions. In addition, for extra gold recovery, further collectors are added, such as the monothiophosphates, which are known to be selective gold collectors. What form does this additional gold recovery take? These are some of the questions left unanswered from the literature.To answer some of these questions, the effect of collector type, and various operating variables, including pH, grind size and collector additions on gold flotation performance were investigated.At high pH, selectivity of gold against pyrite was possible with a number of collectors. However, there was no selectivity against chalcopyrite in the flotation tests performed. Increasing the pH using lime showed no gold depression. Fine gold was easily floated while some coarse gold reported to the flotation tail.
Article
The captive bubble and sessile drop contact angle techniques have been used to evaluate the hydrophobicity of petrographically identified coal macerals. The magnitude of the contact angle on vitrinite is shown to be a function of coal rank (%C, %O and % vitrinite reflectance), increasing with increasing rank to a maximum for low volatile bituminous rank coals then decreasing for anthracite. The least data scatter is found when vitrinite reflectance is used as a rank parameter. Contact angles measured or estimated for other discrete macerals, indicate a variation in hydrophobicity based on coal type. These data correlate well with known flotation results.
Article
Microbial destruction of cyanide and its related compounds is one of the most important biotechnologies to emerge in the last two decades for treating process and tailings solutions at precious metals mining operations. Hundreds of plant and microbial species (bacteria, fungi and algae) can detoxify cyanide quickly to environmentally acceptable levels and into less harmful by-products. Full-scale bacterial processes have been used effectively for many years in commercial applications in North America. Several species of bacteria can convert cyanide under both aerobic and anaerobic conditions using it as a primary source of nitrogen and carbon. Other organisms are capable of oxidizing the cyanide related compounds of thiocyanate and ammonia under varying conditions of pH, temperature, nutrient levels, oxygen, and metal concentrations. This paper presents an overview of the destruction of cyanide in mining related solutions by microbial processes.
Article
In gold mining, cyanide has been the preferred lixiviant worldwide since 1887. Although cyanide can be destroyed and recovered by several processes, it is still widely discussed and examined due to its potential toxicity and environmental impact. Biological treatment of cyanide is a well-established process and has been commercially used at gold mining operations in North America. Biological treatment processes facilitate growth of microorganisms that are essential for the treatment. The present review describes the advances in the use of biological treatment for the destruction of cyanide in gold mill effluents.
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