Article

Copper and Cobalt Recovery from Pyrite Ashes of a Sulphuric Acid Plant

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Abstract

The pyrite ashes formed as waste material during the calcination of concentrated pyrite ore used for producing sulphuric acid not only has a high iron content but also contains economically valuable metals. These wastes, which are currently landfilled or dumped into the sea, cause serious land and environmental pollution problems owing to the release of acids and toxic substances. In this study, physical (sulphation roasting) and hydrometallurgical methods were evaluated for their efficacy to recover non-iron metals with a high content in the pyrite ashes and to prevent pollution thereby. The preliminary enrichment tests performed via sulphation roasting were conducted at different roasting temperatures and with different acid amounts. The leaching tests investigated the impact of the variables, including different solvents, acid concentrations and leach temperatures on the copper and cobalt leaching efficiency. The experimental studies indicated that the pre-enrichment via sulphation roasting method has an effect on the leaching efficiencies of copper and cobalt, and that approximate recoveries of 80% copper and 70% cobalt were achieved in the H2O2-added H2SO4 leaching tests.

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... This treatment recovers metals which can be then used for other processes. One of the options is to enhance metal leaching by treatment with sulphuric acid (Antonijevi c et al., 1997;Erust and Akcil, 2016;Mulligan, et al., 2001). The main disadvantage of the mobilisation treatments is the cost since the wastes are typically processed in specific facilities. ...
... The mobilisation test was carried out under the same laboratory conditions but using H 2 SO 4 for metal release into soil solution (Antonijevi c et al., 1997;Erust and Akcil, 2016). Pyrite samples (in triplicate for each treatment) were placed in 100 mL plastic containers and mixed with H 2 SO 4 (1:10 ratio) at four concentrations (0.25 M, 0.5 M, 1 M and 2 M) and contact times (60, 120, 180 and 240 min) under constant shaking speed (170 rpm) as used in Erust and Akcil (2016). ...
... The mobilisation test was carried out under the same laboratory conditions but using H 2 SO 4 for metal release into soil solution (Antonijevi c et al., 1997;Erust and Akcil, 2016). Pyrite samples (in triplicate for each treatment) were placed in 100 mL plastic containers and mixed with H 2 SO 4 (1:10 ratio) at four concentrations (0.25 M, 0.5 M, 1 M and 2 M) and contact times (60, 120, 180 and 240 min) under constant shaking speed (170 rpm) as used in Erust and Akcil (2016). Metal content at each obtained solution was analysed by Atomic Absorption spectrometer AAnalyst 800 (Perkin Elmer, United States). ...
Article
The main objective was to evaluate and optimise strategies for the immobilisation or mobilisation of Cd, Cu, Cr, Ni, Pb, and Zn from pyrite ash. Alkaline amendments were used for the immobilisation test: cement, sandstone, marl, marble waste and calcareous crust. The amendments were mixed with pyrite ash at a 1:2 rate, incubated for 28 days, and leachates analysed at the beginning of the experiment (day 0) and after 2, 7, 14 and 28 days. The mobilisation experiment tested metal release from pyrite ash by four concentrations of H2SO4(0.25 M, 0.5 M, 1 M and 2 M) and contact times (60, 120, 180 and 240 min). Results for the immobilisation/mobilisation tests for Cr and Ni are not presented due to the low concentration in pyrite ash. In the immobilisation test, optimum results across metals and amendments were obtained after two days with percentages of retention being about 90% compared to leachates from pyrite ash only. The release success (in % of total content) using sulphuric acid followed the order: Cd (75%) > Zn (62%) > Cu (37%) > Pb (7%). The concentration of acid was more important than contact time (release enhanced at higher concentrations) except for Zn. The two strategies tested were successful to reduce the risk posed by metals. In terms of optimization, all alkaline materials showed high efficiency for metal retention after a short contact time; for mobilisation, treatment with sulphuric acid at high concentration (up to 2 M tested) resulted to be the optimum with contact time having limited influence.
... The cobalt sulfur concentrate was oxidized roasted at 850-900 °C, and the cinder was mixed with some cobalt sulfur concentrate and chlorinating agent to carry out medium-temperature chlorination sulfuric acid roasting at about 650 °C. This way had a high bed capacity (17-18 t/m 2 •d), but the SO2 concentration in the flue gas was only 1-2%, which is difficult for acid production, and there was a certain amount of hydrogen chloride gas in the flue gas, which will lead to serious corrosion of the equipment [7][8][9][10]. ...
... Therefore, there are many complex phase changes in the segregation roasting process. Combined with the analysis results, the possible chemical reactions in the segregation roasting process are shown in Equations (3) (7) CoCl2 + H2 → Co + HCl (8) FeCl3 + 3H2 → 2Fe + 6HCl (9) 2Co + 2FeCl3 + 3H2→ 2[Co]Fe + 6HCl (10) In the system, the relationship between the difficulties in the reduction of iron cobalt metal chloride is FeCl3 < CoCl2, and cobalt is a kind of iron-soluble oxide. FeCl3 itself is a kind of chlorinating agent, promoting the chlorination and segregation of cobalt, and forms the solid solution of [Co] Fe. ...
Article
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In this study, oxidizing roasting, segregation roasting, and magnetic separation are used to extract cobalt and iron from refractory Co-bearing sulfur concentrate. The Co-bearing sulfur concentrate containing 0.68% Co, 33.26% Fe, and 36.58% S was obtained from V-Ti magnetite in the Panxi area of China by flotation. Cobalt pyrite and linneite were the Co-bearing minerals, and the gangue minerals were mica, chlorite, feldspar, and calcite in Co-bearing sulfur concentrate. The results show that cobalt is transformed from Co-pyrite and linneite to a Co2FeO4-dominated new cobalt mineral phase, and iron is transformed from pyrite to Fe2O3 and an Fe3O4-dominated new iron mineral phase after oxidizing roasting. Cobalt changed from CoFe2O4 to a new cobalt mineral phase dominated by [Co] Fe solid solution, and iron changed from Fe2O3 to a new iron mineral phase dominated by metal Fe and Fe3O4 after segregation roasting. Cobalt concentrate with a cobalt grade of 15.15%, iron content of 71.22%, and cobalt recovery of 90.81% as well as iron concentrate with iron grade of 60.06%, cobalt content of 0.11%, and iron recovery of 76.23% are obtained. The main minerals in the cobalt concentrate are Fe, [Co]Fe, Fe3O4, and SiO2, and the main minerals in the iron concentrate are Fe3O4, FeO, Ca2Si2O4, and Ca2Al2O4.
... In case of this industry, the source of sulphur (as in step 1) is FeS 2 . Overall oxidation of pyrite can be represented as: FeS 2 (s) + 11/4O 2 (g) → ½Fe 2 O 3 (s) + 2SO 2 (g) (5) The combustion of pyrite ore is accompanied by generation of a waste material commonly known as "pyrite ash". Although this byproduct is a waste material, it has got a number of advantages that finds application in different sectors. ...
... For example, it is used: (a) as an iron ore in the iron-steel industry since it contains around 50-60% Fe [1,3]; (b) in the preparation of bricks (for giving colour due to presence of iron oxides); (c) as an additive in the cement industry; (d) as a pigment in the paint industry [1] and (e) in the pelletization process for treatment of low grade iron ores [4] etc. Although, the above mentioned management practices offer numerous benefits on one hand, an alternative evaluation of such wastes for metal recovery can offer attractive advantages on the other. Investigation on the utilization of pyrite ash for metal recovery have indicated that an appreciable amount of Cu, Co etc. can be recovered by hydrometallurgical (chemical leaching) routes [1,5,6]. However, such routes use high temperatures, strong and hazardous chemicals etc. that limits the use of these processes from an environmental and economical perspective. ...
Article
Simultaneous multi-metal leaching from industrial pyrite ash is reported for the first time using a novel bioreactor system that allows natural diffusion of atmospheric O2 and CO2 along with the required temperature maintenance. The waste containing economically important metals (Cu, Co, Zn & As) was leached using an adapted consortium of meso-acidophilic Fe(2+) and S oxidising bacteria. The unique property of the sample supported adequate growth and activity of the acidophiles, thereby, driving the (bio) chemical reactions. Oxido-reductive potentials were seen to improve with time and the system's pH lowered as a result of active S oxidation. Increase in sulphur dosage (>1g/L) and agitation speed (>150rpm) did not bear any significant effect on metal dissolution. The consortium was able to leach 94.01% Cu (11.75% dissolution/d), 98.54% Co (12.3% dissolution/d), 75.95% Zn (9.49% dissolution/d) and 60.80% As (7.6% dissolution/d) at 150rpm, 1g/L sulphur, 30°C in 8days.
... Several studies reported the leaching of cobalt from pyrite cinders as well as concentrates and cobalt-bearing pyrite/ores. Many investigators (Acarkan, et al. 2008, Akdağ, 2008, Canbazoğlu, et al. 1985, Erust and Akcil, 2016, Tugrul, et al. 2003) agreed that sulphation roasting as a pretreatment for conversion of cobalt to soluble cobalt sulphate followed by acid/water leaching is more effective than direct leaching. In this respect, pyrite concentrates are often subjected to roasting (calcination) and/or sulphation roasting prior to leaching of cobalt and other metals (Acarkan et al., 2008, Akdağ, 2008, Canbazoğlu et al., 1985, Çolak et al., 1993, Studentsov et al., 1996, Ziyadanogullari, 2000. ...
Conference Paper
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Magnesium compounds which are caustic magnesia, sinter or dead-burnt magnesia, magnesium chloride, magnesium hydroxide, magnesium carbonate (magnesite) are produced from seawater, lake brines and minerals deposits. Magnesite ore (MgCO3) is a natural mineral mainly composed of magnesium carbonate and it is the primary source for production of magnesium and its compounds. Magnesite ore is composed of serpentine, quartz-based silica, opal and limestone, and SiO2, Fe2O3, CaO, Al2O3 content is important to determining the quality of magnesite ore and economic evaluation is done according to these values. Beneficiation of magnesite ore is performed using physical and chemical methods to produce a high-grade product to be used in the manufacture of magnesium compounds. Magnesite ore is separated from impurity silica and iron by crushing, grinding, screening and beneficiations methods. In this study is aimed to determine that beneficiation methods which used for magnesite ore is how successful. According to experiment results, the best result has been obtained by chemical beneficiation method so it is the best suitable method for beneficiation magnesite ore.
... Vol. 08 Issue 01, January 2020, ISSN: 2347-6532 Impact Factor: 6 ...
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Mining and the assessment of compliance with environmental obligations, the process used by RUASHI Mining for the production of copper, cobalt hydroxides and the production of sulfuric acid produced on site within the concession, a impact Study Environmental and Social (ESIA) company RUASHI MINING SAS, a field visit to the assessment of the environmental status of sites, the physical, biological and sociological environments. Hydrometallurgical production of copper by electrolysis and cobalt by magnesia precipitation, after leaching with sulfuric acid and extraction with organic solvent. To know the processes RUASHI MINING (the flows sheets), the communes RUASHI and Annex in quest for the social and the durable development, the environmental plans of the project taking care of the measures to be developed to avoid, to mitigate the unavoidable impacts, to rehabilitate the affected sites or offset the impacts of condemned sites.water management during periods of heavy rain, waste and unused reagents on its site and that of Févier 2018. The environmental impact study according to article 463 litera c of the DR Congo Mining Regulation which stipulates the revision of the EIA and the Project Management Plan see if with the changes that may also intervene in the activities of RUASHI MINING, justify this said revision during this year 2019.that RUASHI MINING has considered techniques and technologies that take into account changing operating conditions in order to pursue its production objectives. The 2006 and February 2018 RUASHI MINING Environmental Revisions are partially compliant with the ESIA guidelines when developing the Environmental Impact Statement and the Environmental Management Plan for the project as many steps are not not followed in practice. RUASHI MINING should ensure the establishment of environmental monitoring registers and the implementation of the environmental management measures freely granted in its EIA / EMPP. Results after the samples taken are shown in APPENDIX this work Table A: Results of water samples Table B: Result of soil samples EIE/PGEP�In addition to sulfuric acid production, the company has a project for sulphide roasting, so monitoring dangerous products is essential, climate management in the causes and effects of rainfall, water, soil and air its impacts ; of the program of mitigation and rehabilitation measures, the measures of RUASHI MINING: Avoid, minimize, rehabilitate and compensate must be scrupulously respected. the respect of international agreements from the positive meaning in the Paris agreements to COP 21 in France in 2015 to COP 25 proposal in Brazil AMOZONE the first green after COP24 carbon industry countries in 2018. Key words :Cobalt hydroxides.Sulfuricacid, Copper by electrosis, Water, soil, air, rains,
... Cobalt in cobalt pyrite is closely related to pyrite in the form of isomorphism, and the flotability difference between (Fe,Co)S2 and FeS2 is smaller and it is very difficult to select reasonable inhibitors to achieve separation, which makes it difficult to separate cobalt and sulfur by flotation. Therefore, cobalt preconcentration is easy realized in the actual flotation separation process [33][34][35]. Cobaltsulfur concentrate can be used as raw material for further separation of cobalt and sulfur in smelting by pyrometallurgical or hydrometallurgical methods. ...
Article
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There is 0.032% cobalt and 0.56% sulfur in the cobalt-bearing V–Ti tailings in the Panxi Region, with the metal sulfide minerals mainly including FeS2, Fe1−xS, Co3S4, and (Fe,Co)S2, and the gangue minerals mainly including aluminosilicate minerals. The flotation process was used to recover cobalt and sulfur in the cobalt-bearing V–Ti tailings. The results showed that an optimized cobalt–sulfur concentrate with a cobalt grade of 2.08%, sulfur content of 36.12%, sulfur recovery of 85.79%, and cobalt recovery and 84.77% were obtained by flotation process of one roughing, three sweeping, and three cleaning under roughing conditions, which employed pulp pH of 8, grinding fineness of < 0.074 mm occupying 80%, flotation concentration of 30%, and dosages of butyl xanthate, copper sulfate, and pine oil of 100 g/t, 30 g/t, and 20 g/t, respectively. Optimized one sweeping, two sweeping, and three sweeping conditions used a pulp pH of 9, and dosages of butyl xanthate, copper sulfate, and pine oil of 50 g/t, 15 g/t, 10 g/t; 25 g/t, 7.5 g/t, 5 g/t; 20 g/t, 5 g/t, 5 g/t, respectively. Optimized one cleaning, two cleaning, and three cleaning condition dosages of sodium silicate of 200 g/t, 100 g/t, 50 g/t, respectively. Study of analysis and characterization of cobalt–sulfur concentrate by X-ray diffraction (XRD), automatic mineral analyzer (MLA), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) showed that the main minerals in cobalt–sulfur concentrate are FeS2, Co3S4 and (Fe,Co)S2, of which FeS2 and (Fe,Co)S2 accounted for 65.64% and Co3S4 for 22.64%. Gangue minerals accounted for 11.72%. The element Co in (Fe,Co)S2 is closely related to pyrite in the form of isomorphism, and the flotability difference between cobalt and pyrite is very small, which makes it difficult to separate cobalt and sulfur. Cobalt–sulfur concentrate can be used as raw material for further separation of cobalt and sulfur in smelting by pyrometallurgical or hydrometallurgical methods.
... The conducted procedure (H 2 SO 4 leaching tests performed following sulfation roasting at 250 o C and with a duration of 1 h) enables 80 % Cu and 70 % Co recovery. The recovery parameters were found to be appropriate for pilot-plant tests [156]. The treatment of slag with chlorine and chloride as lixiviant also enabled efficient dissolving of copper (75-80 %) and the most significant parameters were the particle size and the initial chlorine concentration [87]. ...
Chapter
Mineral extraction industries at each mining step generate large volume of waste, and most of them represent potentially sources of crucial metals. This chapter describes extraction and main mining processes, principal classifications of the generated wastes, as well as the chemical properties of the waste material, their disposal and further treatment to recover metals. Most of the presented technological solutions are or have been tested in real processes or using real waste materials
... The conducted procedure (H 2 SO 4 leaching tests performed following sulfation roasting at 250 o C and with a duration of 1 h) enables 80 % Cu and 70 % Co recovery. The recovery parameters were found to be appropriate for pilot-plant tests [156]. The treatment of slag with chlorine and chloride as lixiviant also enabled efficient dissolving of copper (75-80 %) and the most significant parameters were the particle size and the initial chlorine concentration [87]. ...
Article
Mineral extraction industries at each mining step generate large volume of waste, and most of them represent potentially sources of crucial metals. This chapter describes extraction and main mining processes, principal classifications of the generated wastes, as well as the chemical properties of the waste material, their disposal and further treatment to recover metals. Most of the presented technological solutions are or have been tested in real processes or using real waste materials.
... However, at pH-1.5 the dissolution of Cu and Co were about 81.5 and 84% respectively. Erust and Akcil [33] and Turgul et al. [3], however using chemical leaching routes, also observed a similar trend where higher concentration of sulphuric acid did not favour higher dissolution of Cu and Co. A maximum of 79% Zn could be extracted at pH-1.75. ...
Article
Pyrite ash, a waste by-product formed during roasting of pyrite ores, is a good source of valuable metals. The waste is associated with several environmental issues due to its dumping in sea and/or land filling. Although several other management practices are available for its utilization, the waste still awaits and calls for an eco-friendly biotechnological application for metal recovery. In the present study, chemolithotrophic meso-acidophilic iron and sulphur oxidisers were evaluated for the first time towards simultaneous mutli-metal recovery from pyrite ash. XRD and XRF analysis indicated higher amount of Hematite (Fe2O3) in the sample. ICP–OES analysis indicated concentrations of Cu > Zn > Co> As that were considered for bioleaching. Optimization studies indicated Cu −95%, Co −97%, Zn − 78% and As −60% recovery within 8 days at 10% pulp density, pH −1.75, 10% (v/v) inoculum and 9 g/L Fe²⁺. The productivity of the bioleaching system was found to be Cu −1696 ppm/d (12% dissolution/d), Co −338 ppm/d (12.2% dissolution/d), Zn −576 ppm/d (9.8% dissolution/d) and As −75 ppm/d (7.5% dissolution/d). Synergistic actions for Fe²⁺ −S° oxidation by iron and sulphur oxidisers were identified as the key drivers for enhanced metal dissolution from pyrite ash sample.
... Several studies reported the leaching of cobalt from pyrite cinders as well as concentrates and cobalt-bearing pyrite/ores. Many investigators (Acarkan, et al. 2008, Akdağ, 2008, Canbazoğlu, et al. 1985, Erust and Akcil, 2016, Tugrul, et al. 2003) agreed that sulphation roasting as a pretreatment for conversion of cobalt to soluble cobalt sulphate followed by acid/water leaching is more effective than direct leaching. In this respect, pyrite concentrates are often subjected to roasting (calcination) and/or sulphation roasting prior to leaching of cobalt and other metals (Acarkan et al., 2008, Akdağ, 2008, Canbazoğlu et al., 1985, Çolak et al., 1993, Studentsov et al., 1996, Ziyadanogullari, 2000. ...
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Abstract: In this study, recovery of cobalt from a copper flotation tailing (pyrite concentrate) by oxidative acid leaching was investigated. The as-received tailings (d80: 64 μm) contained 6407 g/t Co, 3547 g/t Cu, 21.4% Fe and 1705 g/t Zn. Leaching tests were carried out using different mineral acids under oxidising conditions (i.e. H2SO4+H2O2, HCl+H2O2 and HNO3) over a period of 6 h. Extraction of cobalt was found to be limited in oxidative chloride (1 M HCl + H2O2) and sulphate (1 M H2SO4 + H2O2) solutions with 12% and 22%, respectively, over 6 h. In oxidative chloride and sulphate leaching tests, other metals were also dissolved to some extent i.e. 43-46% Cu, 9-14% Fe, 28-66% Zn. The result showed that oxidative leaching in chloride or sulphate media in the presence of H2O2 was not effective for obtaining high cobalt extractions from the tailings material. However, complete extraction of cobalt was achieved in nitric acid leaching test over the leaching period of 6 h. High correlation between Fe and Co dissolution rates was observed, indicating that extraction of cobalt can be hinges closely on oxidation of pyrite.
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Mining and the assessment of compliance with environmental obligations, the process used by RUASHI Mining for the production of copper, cobalt hydroxides and the production of sulfuric acid produced on site within the concession, a impact Study Environmental and Social (ESIA) company RUASHI MINING SAS, a field visit to the assessment of the environmental status of sites, the physical, biological and sociological environments. Hydrometallurgical production of copper by electrolysis and cobalt by magnesia precipitation, after leaching with sulfuric acid and extraction with organic solvent. To know the processes RUASHI MINING (the flows sheets), the communes RUASHI and Annex in quest for the social and the durable development, the environmental plans of the project taking care of the measures to be developed to avoid, to mitigate the unavoidable impacts, to rehabilitate the affected sites or offset the impacts of condemned sites.water management during periods of heavy rain, waste and unused reagents on its site and that of Févier 2018.
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Pyrite ash is a residue from the roasting of pyrite ores to obtain sulphuric acid used in the fertiliser industry and its production is widely extended worldwide. The mismanagement of this waste may result in environmental and health damages due to its physico-chemical characteristics. The main objective of this study was to examine the physico-chemical and mineralogical composition of roasted pyrite ash from an abandoned fertiliser company, and to evaluate the environmental risk caused by the wind and water dispersion of metals posed by this waste. In order to achieve these objectives, a sequential extraction procedure and a physical fractionation into six size fractions: >100, 100-50, 50-20, 20-10, 10-2.5 and < 2.5 μm were applied. Results showed that pyrite ash is composed mainly of iron-oxides such as hematite (46%) and secondary minerals as anglesite and shows high concentrations of Pb (7464 mg kg-1), Zn (2663 mg kg-1) and Cu (585 mg kg-1). The highest Risk Assessment Code (RAC) values were found for Cd, Pb and Zn, bound to the more labile fractions. Conversely, Pb showed the lowest water solubility due to the covering effect provided by a coating of anglesite in the pyrite ash surface. Most of the metals were associated to both the coarsest (>100 μm) and the finest (2.5-10 μm) fractions, although none represented an environmental risk according to the ecological risk index results. However, 30% of the metals were bound to the respirable fraction (≤100 μm) posing a potential risk for human health and a high potential dispersion by wind to the surrounding areas.
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The aim of this study is to investigate the utilization of Pyrite Ash (PA) in the production of briquettes as a replacement of clay or soil. To achieve this, first, the characterization of the materials used (clayey soil and pyrite ash) was made using Fourier Transform Infrared Spectroscopy (FTIR/ATR). Particle size distribution and microstructure elemental analyses of these materials were also obtained using a particle size analyzer (Mastersizer) and a Scanning Electron Microscope (SEM). Following the characterization of the materials, the samples of briquettes made with or without addition of PA were prepared and sintered at 950 and 1000°C in the furnace. The PA replacement ratios with clayey soil were 0, 5, 10, 20% in mass basis (w/w). Compressive strength and bulk densities of briquettes produced were measured and the results were presented. Compressive strength results of the briquette samples indicated that pyrite ash containing briquettes with 35 MPa compressive strength, which was higher than the requirements of Turkish Standard Specification (TS EN 771-1), can be obtained. It is also recorded that for each mixture, compressive strength values obtained at 1000°C were higher than that of obtained at 950°C. XRD analyze was performed on sintered briquette sample made with 10% PA which have the highest compressive strength value. The XRD results showed that peaks are Quartz (SiO2), Hematite (Fe2O3), Ortoclase (KAlSi3O8), Albite (Na(AlSi3O8)), Anorthite (CaAl2Si2O8) and Gehlenite (2CaO.Al2O3.SiO2).
Article
The dissolution of copper from chalcopyrite was investigated in the presence of hydrogen peroxide and ethylene glycol. Hydrogen peroxide was used as oxidant in the leaching process. Addition of a small amount of ethylene glycol significantly improved the copper dissolution. The copper leaching mechanism was established by examining the influence of various parameters on the reaction rate in the presence of ethylene glycol. The effect of temperature on the reaction kinetics suggests that the leaching reaction follows the surface reaction-controlled model. The linear relationship between the log of reaction rate constant and log of particle radius supports the proposed reaction model. The reaction order was calculated with respect to hydrogen peroxide which indicates that hydrogen peroxide has greater influence on the leaching kinetics. Stirring speed and sulfuric acid concentration are not important variables. Most of the sulfide ions were transformed to elemental sulfur during the reaction. The elemental sulfur was present on the surface of chalcopyrite residue as discrete crystalline particles instead of a coating of continuous film which causes the passivation of chalcopyrite surface. Ethylene glycol was found to stabilize the hydrogen peroxide at elevated temperature which could be another reason for enhanced recovery.
Article
The kinetics of leaching pyrite with hydrogen peroxide in sulphuric acid were investigated. The parameters studied were: stirring speed, temperature, particle size and concentrations of H2O2 and H2SO4. The effects of SO42− and H+ additions were also investigated. The leaching rate decreases with increasing stirring speed and H2SO4 concentration. The kinetics of pyrite dissolution are described by means of the surface reaction control shrinking core model. This is supported by an activation energy of 68 kJ/mol and a linear relationship between the rate constant and the inverse of the particle radius. The consumption of H2O2 is greater than that stoichiometrically required, due to its catalytic decomposition. The leaching rate is first order with respect to H2O2. Additions of SO42− have a negative influence on the leaching rate, whereas H+ additions have a beneficial effect. A reaction mechanism is proposed.
Article
The extraction of sulphur produces a hematite-rich waste, known as roasted pyrite ash, which contains significant amounts of environmentally sensitive elements in variable concentrations and modes of occurrence. Whilst the mineralogy of roasted pyrite ash associated with iron or copper mining has been studied, as this is the main source of sulphur worldwide, the mineralogy, and more importantly, the characterization of submicron, ultrafine and nanoparticles, in coal-derived roasted pyrite ash remain to be resolved. In this work we provide essential data on the chemical composition and nanomineralogical assemblage of roasted pyrite ash. XRD, HR-TEM and FE-SEM were used to identify a large variety of minerals of anthropogenic origin. These phases result from highly complex chemical reactions occurring during the processing of coal pyrite of southern Brazil for sulphur extraction and further manufacture of sulphuric acid. Iron-rich submicron, ultrafine and nanoparticles within the ash may contain high proportions of toxic elements such as As, Se, U, among others. A number of elements, such as As, Cr, Cu, Co, La, Mn, Ni, Pb, Sb, Se, Sr, Ti, Zn, and Zr, were found to be present in individual nanoparticles and submicron, ultrafine and nanominerals (e.g. oxides, sulphates, clays) in concentrations of up to 5%. The study of nanominerals in roasted pyrite ash from coal rejects is important to develop an understanding on the nature of this by-product, and to assess the interaction between emitted nanominerals, ultra-fine particles, and atmospheric gases, rain or body fluids, and thus to evaluate the environmental and health impacts of pyrite ash materials.
Article
The extraction of copper from a chalcopyrite concentrate by hydrogen peroxide in sulphuric acid solutions was studied. The influence of various parameters was investigated in order to elucidate the kinetics of chalcopyrite dissolution. It was determined that stirring speed had no effect on the rate of chalcopyrite dissolution, which suggested that reaction was not controlled by liquid-phase diffusion. Dissolution curves were found to conform to the surface reaction controlled shrinking core model, i.e., 1−(1−X)1/3=kst. Both the magnitude of the activation energy of 60 kJ/mol and the linear relationship between the rate constant and the inverse particle radius support the fact that dissolution is controlled by the surface reaction. Hydrogen peroxide had great influence on the rate of chalcopyrite dissolution; a reaction order of unity was calculated with respect to the concentration of this oxidant. Sulphuric acid also had influence on chalcopyrite dissolution, with a reaction order of 0.3 with respect to the acid concentration being established.
Article
Spent catalyst from manufacture of sulfuric acid production (main elemental composition: 3.5% V, 0.63% Ni, 7.9% Fe and 9.64% Si) can be used as a secondary source of vanadium and nickel. Extraction of these metals was studied using two different leaching systems (alkaline and acidic). Statistical design of the experiments and ANOVA (analysis of variance) were performed in order to determine the main effects and interactions of the factors under research, which were roasting, leaching temperature, concentration of the leaching reagent (H2SO4 and NaOH), liquid/solid (L/S) ratio (at 100 mL of liquid reagent), and presence of hydrogen peroxide.The results obtained after acidic treatment show that nickel extraction yield of 96% is achieved after roasting at 600 °C, followed by leaching with 5 mL/g 1 M sulfuric acid at 80 °C for a 30 min reaction time. The highest vanadium extraction yield was 59% after roasting at 400 °C and leaching at 80 °C by 0.3 M sulfuric acid for 6 h and 10 mL/g L/S ratio.A full factorial experiment was also performed by application of sodium hydroxide for vanadium extraction in the second leaching system. The highest vanadium extraction yield after alkaline treatment was 78%, obtained through roasting at 400 °C, leaching at 80 °C by 4 M NaOH for 2 h and 10 mL/g L/S ratio. Because nickel is not dissolved by sodium hydroxide, a sequential acidic leaching was conducted using the alkaline leaching residue, obtaining a nickel extraction yield of 88%.
Article
The combination of roasting and pressure leaching is an alternative process that offers advantages over conventional processes because of the shorter leaching time and higher metal recovery. The copper and iron sulphide minerals examined in this study were chalcopyrite (CuFeS2) and pyrite (FeS2). The best results obtained were with a pre-treatment by roasting followed by acid pressure leaching in an autoclave system. The extraction of copper achieved was over 85%. Copper dissolution in this system is affected by particle size, leaching time and oxygen pressure. This paper presents the preliminary research on acid leaching of pyritic copper ore in an autoclave system under laboratory conditions.
Article
Power plant process simulation software is well-suited for the modelling of energy systems and more importantly, tools for analysing the energy efficiency are often built into the software. This work presents the development of a simulation model for a sulphuric acid plant using a commercial software package for power plant process simulation. This will be of value to for instance small consultant and engineering companies involved with audits and analysis of energy systems. For small sized companies the cost of acquiring and maintaining many different specialised software packages will be noticeable. However, companies involved with audits and analysis of energy systems will in most cases have access to at least one software package for power plant process calculations. The use of this kind of software for also modelling chemical plants would be valuable to these companies. The results of this work shows that it is possible to use an inexpensive but powerful power plant process simulation software for modelling a common chemical process as a part of a large energy system.
Article
A hydrometallurgical route is proposed to recover zinc and manganese from spent alkaline batteries in order to separate base metals such as nickel, copper, aluminium, cadmium, lithium and cobalt which constitute the main metallic species of spent NiCd, NiMH and Li-ion rechargeable batteries. The route comprises the following main steps: (1) sorting batteries by type, (2) battery dismantling to separate the spent battery dust from plastic, iron scrap and paper, (3) leaching of the dust with sulphuric acid and (4) metal separation by a liquid–liquid extraction using Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) as extractant. The metal content of NiCd, NiMH and Li-ion batteries from three distinct manufacturers has been evaluated. A factorial design of experiments was used to investigate the leaching step using operational variables such as temperature, H2SO4 concentration, S/L ratio and H2O2 concentration. Analysis of metal separation by the liquid–liquid extraction with Cyanex 272 identified a pH1/2 2.5–3.0 for zinc and aluminium, pH1/2 4.0–4.5 for manganese, cadmium, copper and cobalt, pH1/2 6.5 for nickel and pH1/2 8.0 for lithium. These results indicate that batteries must be previously sorted by type and treated separately. In addition, data fitting to an equilibrium model proposed for the reactive test system by the European Federation of Chemical Engineering (EFChE) have indicated that MR2(RH)2 and MR2 complexes (where M = Zn, Mn, Co, Cd and Cu) co-exist in the organic phase with Cyanex 272 depending on the loading conditions. The route has been found technically viable to separate the main metallic species of all batteries considered in this study.
Article
Cobalt is an important metal which is being used in advanced technologies such as alloying and electronic industry; as well as in painting and ceramics. This paper attempts to research the possible ways of transferring possibilities of cobalt from calcine which is obtained as a waste from roasting pyrite concentrates.
Article
The Sotiel-Coronada abandoned mining district (Iberian Pyrite Belt) produced complex massive sulphide ores which were processed by flotation to obtain Cu, Zn and Pb concentrates. The crude pyrite refuses were roasted for sulphuric acid production in a plant located close to the flotation site, and waste stored in a tailing dam. The present study was focused on the measurements of flow properties, chemical characterization and mineralogical determination of the roasted pyrite refuses with the aim of assessing the potential environmental impact in case of dam collapse. Chemical studies include the determination of the total contaminant content and information about their bio-availability or mobility using sequential extraction techniques. In the hypothetical case of the tailing dam breaking up and waste spilling (ca. 4.54Mt), a high density mud flow would flood the Odiel river valley and reach both Estuary of Huelva (Biosphere Reserve by UNESCO, 1983) and Atlantic Ocean in matter of a couple of days, as it was predicted by numerical simulations of dam-break waves propagation through the river valley based on quasi-2D Saint-Venant equations. The total amount of mobile pollutants that would be released into the surrounding environment is approximately of 7.1.10(4)t of S, 1.6.10(4)t of Fe, 1.4.10(4)t of As, 1.2.10(4)t of Zn, 1.0.10(4)t of Pb, 7.4.10(3)t of Mn, 2.2.10(3)t of Cu, 1.5.10(2)t of Co, 36t of Cd and 17t of Ni. Around 90-100% of S, Zn, Co and Ni, 60-70% of Mn and Cd, 30-40% of Fe and Cu, and 5% of As and Pb of the mobile fraction would be easily in the most labile fraction (water-soluble pollutants), and therefore, the most dangerous and bio-available for the environment. This gives an idea of the extreme potential risk of roasted pyrite ashes to the environment, until now little-described in the scientific literature.
Küre Piritli Bakır Cevherlerinden Kobalt, Bakır, Altın ve Gümüşün Hidrometalurjik Süreçlerle Kazanılma Olanakları
  • M Canbazoglu
  • M Uzun
  • O Celik
Canbazoglu M, Uzun M, Celik O, et al. (1986) Küre Piritli Bakır Cevherlerinden Kobalt, Bakır, Altın ve Gümüşün Hidrometalurjik Süreçlerle Kazanılma Olanakları. Türkiye Madencilik Bilimsel ve Teknik Kongresi 9: 59-74.
İkincil kaynaklardan metal geri kazanımında çevresel bir yaklaşım: Biyoliç
  • C Erust
  • A Tuncuk
  • A Akcil
Erust C, Tuncuk A and Akcil A (2012) İkincil kaynaklardan metal geri kazanımında çevresel bir yaklaşım: Biyoliç [An Environmental Approach in Metal Recovery from Secondary Resources: Bioleaching]. Recycling Industry 61: 74-78.
A guide to tailings damsand impoundments. Design, construction, use and rehabilitation
International Commission on Large Dams (1996). A guide to tailings damsand impoundments. Design, construction, use and rehabilitation. Bulletin (United Nations Environment Programme) 106: 239.
Bioprocess/fermentation technology (chapter 4) Chemical Technology in Africa
  • Jw Steward
  • Pj Tourse
Steward JW and Tourse PJ (1984) Bioprocess/fermentation technology (chapter 4). Chemical Technology in Africa. Cambridge: Cambridge University Press, pp.83–86.