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Bioleaching of hexavalent chromium from soils using acidithiobacillus thiooxidans

Fonseca, Bruna; Rodrigues, Joana; Queiroz, A.M.; Tavares, Teresa
Fonte: Universidade do Minho, Centro de Engenharia Biológica, Portugal Publicador: Universidade do Minho, Centro de Engenharia Biológica, Portugal
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
37.69%
The continuous and growing degradation of the environment, due to several anthropogenic activities, is a main concern of the scientific community. Consequently, the development of low cost techniques to clean air, water and soils are under intense investigation. In this study, the focused problem is the soil contamination by hexavalent chromium, which is known for its several industrial applications - production of stainless steel, textile dyes, wood preservation and leather tanning - its high toxicity and mobility. Bioleaching has been presented as a low cost effective technique to decontaminate soils polluted with heavy metals. Sulphur oxidizing bacteria, like Acidithiobacillus thiooxidans, were already applied with this technique as they produce sulphuric acid, lowering the pH and promoting the dissolution of heavy metals [1, 2]. On the other hand, it also known that polythionates, generated during the oxidation process, have high reducing power. Considering this information and since few studies have been made concerning the bioleaching of hexavalent chromium from soils, this work pretended to investigate this matter. Specifically, eighteen Erlenmeyers flasks (250 mL) with a working volume of 150 mL, containing 10% ( V / V ) of inoculum (Acidithiobacillus thiooxidans DSM 504)...

Biolixiviação de cobre de sucata eletrônica; Bioleaching of copper from electronic scrap

YAMANE, Luciana Harue; ESPINOSA, Denise Crocce Romano; TENÓRIO, Jorge Alberto Soares
Fonte: Escola de Minas Publicador: Escola de Minas
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
37.57%
O presente trabalho investigou a influência da suplementação de ferro e da adaptação bacteriana sobre a biolixiviação de cobre de placas de circuito impresso usando a bactéria Acidithiobacillusferrooxidans-LR. Placas de circuito impresso de computadores obsoletos foram mecanicamente processadas através de cominuição seguida de separação magnética. A bactéria Acidithiobacillusferrooxidans-LR foi crescida e adaptada à presença de amostras de placas de circuito impresso cominuídas. Um estudo de frascos agitados foi realizado usando um shaker a 30ºC e 185 rpm. Os parâmetros analisados foram pH, concentração de íon ferroso e concentração de metais (ICP-OES). Os resultados demonstram que o processo de adaptação bacteriana aumentou a taxa de extração de cobre. A biolixiviação com Acidithiobacillusferrooxidans-LR adaptada lixiviou 56% do cobre das placas de circuito impresso (fração não-magnética) no meio suplementado pelo íon ferroso após 30 dias.; The present work investigated the influence of ferrous iron supplementation on bioleaching to recover copper from printed circuit boards using Acidithiobacillus ferrooxidans-LR bacteria. Printed wiring boards from obsolete computers were mechanically processed through cominution followed by magnetic separation. The Acidithiobacillus ferrooxidans-LR bacteria were grown and adapted in the presence of printed wiring board samples. A shake flask study was carried out on the printed circuit board samples using a rotary shaker at 30ºC and 185 rpm. The analyzed parameters were: the pH of the medium...

Recuperação de metais de placas de circuito impresso de computadores obsoletos através de processo biohidrometalúrgico.; Metals recovery from printed circuit boards of obsolete computers by biohydrometallurgical process.

Yamane, Luciana Harue
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 26/04/2012 PT
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27.78%
O consumo de produtos eletroeletrônicos, em especial de computadores pessoais, aliado ao avanço tecnológico, diminui a vida útil dos equipamentos a cada geração e o intenso marketing gera um rápido processo de substituição. As placas de circuito impresso são encontradas em praticamente todos os equipamentos eletroeletrônicos e são particularmente problemáticas para reciclar devido à mistura heterogênea de material orgânico, metais e fibra de vidro. As placas de circuito impresso são industrialmente recicladas através de processos hidrometalúrgicos e pirometalúrgicos. A biolixiviação, que é baseada na capacidade de microrganismos solubilizarem metais, pode ser usada para recuperar metais de placas de circuito impresso de computadores. O presente trabalho investigou a recuperação de metais de placas de circuito impresso de computadores obsoletos através de processo biohidrometalúrgico. Para isto, as placas de circuito impresso foram processadas através de cominuição seguida de separações magnética e eletrostática. A bactéria Acidithiobacillus ferrooxidans-LR foi cultivada e adaptada na presença de placas de circuito impresso. Um estudo de frascos agitados foi realizado com amostras do material não-magnético das placas de circuito impresso para avaliar a influência da adaptação bacteriana...

Bioleaching of metals from anaerobic sewage sludge: Effects of total solids, leaching microorganisms, and energy source

Lombardi, A. T.; Garcia, O.; Mozeto, A. A.
Fonte: Marcel Dekker Inc Publicador: Marcel Dekker Inc
Tipo: Artigo de Revista Científica Formato: 793-806
ENG
Relevância na Pesquisa
37.57%
The effects of municipal sewage sludge solids concentration, leaching microorganisms (Thiobacillus thiooxidans or Thiobacillus ferrooxidans) and the addition of energy source (SO or Fe(II)) on the bioleaching of metals from sewage sludge has been investigated under laboratory conditions using shake flasks. The results show that metal solubilization was better accomplished if additional energy source is supplemented to the microorganisms and that T. thiooxidans furnishes, in general, more adequate conditions for the bioleaching than T. ferrooxidans. At a total solids concentration of 70 g L-1 (originally present in the sludge) pH drop and ORP increase are attenuated, so metal solubilization is negatively affected. Tt was also demonstrated that if lead (Pb) solubilization is to be achieved, than a special combination of microorganism/energy source must be applied.

Solubilization profiles of metal ions from bioleaching of sewage sludge as a function of pH

Villar, L. D.; Garcia, O.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica Formato: 611-614
ENG
Relevância na Pesquisa
37.38%
Two patterns of solubilization of metal ions resulting from bioleaching of sewage sludge by sulphur-oxidizing Thiobacillus spp. were established as a function of pH. Chromium and copper ions required a pH of 2-3 to initiate their solubilization, whereas nickel and zinc ions had their solubilization initiated at pH 6-6.5. The patterns obtained were independent of the sludge solids concentrations investigated (10, 17, 25, 32.5 and 40 g l(-1)).

Assessment of anaerobic sewage sludge quality for agricultural application after metal bioleaching

Villar, L. D.; Garcia, O.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1553-1559
ENG
Relevância na Pesquisa
27.78%
The effects of metal bioleaching on nutrient solubilization, especially nitrogen and phosphorous, from anaerobically-digested sewage sludge were investigated in this work. The assessment of the sanitary quality of the anaerobic sludge after bioleaching was also carried out by enumerating indicator (total coliforms, fecal coliforms, and fecal streptococci) and total heterotrophic bacteria. The experiments of bioleaching were performed using indigenous sulphur-oxidizing bacteria (Thiobacillus spp.) as inoculum and samples of anaerobically-digested sludge. Nitrogen and phosphorous solubilization from sewage sludge was assessed by measuring, respectively, the concentration of Total Kjeldahl Nitrogen, ammonia, nitrate/nitrite, and soluble and total phosphorous before and after the bioleaching assays. At the end of the experiment, after 4 days of incubation (final pH of 1.4), the following metal solubilization yields were obtained: zinc, 91%; nickel, 87%; copper, 79%; lead, 52%; and chromium, 42%. As a result of sludge acidification, the viable counts of selected indicator bacteria were decreased to below the detection limit (4 × 103 cfu 100 ml-1), followed by an increase in the mineral fraction of nitrogen (from 6 to 10%) and in the soluble fraction of phosphorous (from 15 to 30%). Although some loss of sludge nutrients can occur during solid-liquid separation following bioleaching...

Effect of Na-chloride on the bioleaching of a chalcopyrite concentrate in shake flasks and stirred tank bioreactors

Bevilaqua, Denise; Lahti, Heidi; Suegama, Patrícia H.; Garcia Jr., Oswaldo; Benedetti, Assis V.; Puhakka, Jaakko A.; Tuovinen, Olli H.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1-13
ENG
Relevância na Pesquisa
37.78%
Oxidative dissolution of chalcopyrite at ambient temperatures is generally slow and subject to passivation, posing a major challenge for developing bioleaching applications for this recalcitrant mineral. Chloride is known to enhance the chemical leaching of chalcopyrite, but much of this effect has been demonstrated at elevated temperatures. This study was undertaken to test whether 100-200 mM Na-chloride enhances the chemical and bacterial leaching of chalcopyrite in shake flasks and stirred tank bioreactor conditions at mesophilic temperatures. Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and abiotic controls were employed for the leaching experiments. Addition of Na-chloride to the bioleaching suspension inhibited the formation of secondary phases from chalcopyrite and decreased the Fe(III) precipitation. Neither elemental S nor secondary Cu-sulfides were detected in solid residues by X-ray diffraction. Chalcopyrite leaching was enhanced when the solution contained bacteria, ferrous iron and Na-chloride under low redox potential (< 450 mV) conditions. Scanning electron micrographs and energy-dispersive analysis of X-rays revealed the presence of precipitates that were identified as brushite and jarosites in solid residues. Minor amounts of gypsum may also have been present. Electrochemical analysis of solid residues was in concurrence of the differential effects between chemical controls...

Bioleaching of hexavalent chromium from soils using Acidithiobacillus thiooxidans

Fonseca, Bruna; Rodrigues, Joana Lúcia; Queiroz, A.; Tavares, M. T.
Fonte: Elsevier; Elsevier BV Publicador: Elsevier; Elsevier BV
Tipo: Artigo de Revista Científica
Publicado em //2010 ENG
Relevância na Pesquisa
37.69%
The continuous and growing degradation of the environment, due to several anthropogenic activities, is a main concern of the scientific community. Consequently, the development of low cost techniques to clean air, water and soils are under intense investigation. In this study, the focused problem is the soil contamination by hexavalent chromium, which is known for its several industrial applications - production of stainless steel, textile dyes, wood preservation and leather tanning - its high toxicity and mobility. Bioleaching has been presented as a low cost effective technique to decontaminate soils polluted with heavy metals. Sulphur oxidizing bacteria, like Acidithiobacillus thiooxidans, were already applied with this technique as they produce sulphuric acid, lowering the pH and promoting the dissolution of heavy metals. On the other hand, it also known that polythionates, generated during the oxidation process, have high reducing power. Considering this information and since few studies have been made concerning the bioleaching of hexavalent chromium from soils, this work pretended to investigate this matter. Specifically, eighteen Erlenmeyers flasks (250 mL) with a working volume of 150 mL, containing 10% (V/V) of inoculum (Acidithiobacillus thiooxidans DSM 504)...

Combined remediation technology for the reduction and bioleaching of hexavalent chromium from soils using Acidithiobacillus thiooxidans

Fonseca, B.; Rodrigues, Joana Lúcia; Mendes, T. S.; Queiroz, A.; Tavares, M. T.
Fonte: Academia Oamenilor de Știință din România Publicador: Academia Oamenilor de Știință din România
Tipo: Artigo de Revista Científica
Publicado em //2014 ENG
Relevância na Pesquisa
37.57%
Contamination of soils due to the release of effluents or deposition of wastes containing hexavalent chromium has been arising serious environmental problems. Therefore, the development of cost effectiveness but also ecological cleaning techniques is a matter of great concern among the scientific community. Bioremediation is attracting more and more attention due to its efficiency, low impact in the ecosystems and low cost. In particular, this study approaches a bioleaching technique using an Acidithiobacillus thiooxidans DSM504 pure culture to clean a soil contaminated with hexavalent chromium. Eight batch tests were performed in order to evaluate the effect of combined parameters: operational temperature (26ºC and Troom), hexavalent chromium concentration (50 mg kg-1 and 100 mg kg-1) and pH of the contaminant solution (2 and pHfree). The bioleaching technique herein exposed presented removal values between 33.3% and 83.3%, undergoing higher deviations due to changes on the contamination pH. Generally, it was more efficient when applied to soils contaminated with acid solutions. The lowest and highest values were both observed for operational temperatures of 26ºC and hexavalent chromium concentrations of 50 mg kg-1. Moreover...

Influences of Extracellular Polymeric Substances on the Dewaterability of Sewage Sludge during Bioleaching

Zhou, Jun; Zheng, Guanyu; Zhang, Xueying; Zhou, Lixiang
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 22/07/2014 EN
Relevância na Pesquisa
27.78%
Extracellular polymeric substances (EPS) play important roles in regulating the dewaterability of sludge. This study sought to elucidate the influence of EPS on the dewaterability of sludge during bioleaching process. Results showed that, in bioleaching system with the co-inoculation of Acidithiobacillus thiooxidans TS6 and Acidithiobacillus ferrooxidans LX5 (A. t+A. f system), the capillary suction time (CST) of sludge reduced from 255.9 s to 25.45 s within 48 h, which was obviously better than the controls. The correlation analysis between sludge CST and sludge EPS revealed that the sludge EPS significantly impacted the dewaterability of sludge. Sludge CST had correlation with protein content in slime and both protein and polysaccharide contents in TB-EPS and Slime+LB+TB layers, and the decrease of protein content in slime and decreases of both protein and polysaccharide contents in TB-EPS and Slime+LB+TB layers improved sludge dewaterability during sludge bioleaching process. Moreover, the low sludge pH (2.92) and the increasing distribution of Fe in the solid phase were another two factors responsible for the improvement of sludge dewaterability during bioleaching. This study suggested that during sludge bioleaching the growth of Acidithiobacillus species resulted in the decrease of sludge pH...

DEVELOPMENT OF AN INNOVATIVE PROCESS FOR THE SELECTIVE RECOVERY OF METALS FROM SPENT REFINERY CATALYSTS

CIBATI, ALESSIO
Fonte: La Sapienza Universidade de Roma Publicador: La Sapienza Universidade de Roma
Tipo: Tese de Doutorado
EN
Relevância na Pesquisa
27.98%
In the present work was studied and developed the treatment of spent refinery catalysts to recovery valuable metals contained in them. It was hypothesized that, using the sulfide precipitation could be possible obtain a selective precipitation of molybdenum, nickel, vanadium and aluminium after the early solubilisation of them by leaching or bioleaching processes. The refinery catalysts are used extensively in the hydro-treating processes for the production of clean fuels from fractions distilled from crude oil. The hydro-treating processes include the elimination of nitrogen compounds, sulphur and metals from charged of the catalytic cracking. The metals present in the charged cause the poisoning of the catalysts reducing their activity; the catalysts deactivated are classified as solid wastes by the United States Environmental Protection Agency (USEPA). Environmental regulations and interesting amounts of strategic metals guide towards the development of new feasible and sustainable process not only to treat this waste but also to recover valuable metals such as V, Al, Ni and Mo. The work was divided in two phases: the first phase consisted in the solubilization of spent refinery catalysts by bioleaching processes with sulphur-oxidising bacteria or leaching process by sulphuric acid. Once solubilised the spent catalysts...

Bioleaching Model of a Copper-Sulfide Ore Bed in Heap and Dump Configurations; METALLURGICAL AND MATERIALS TRANSACTIONS B. VOLUME 29B, AUGUST 1998—899

Moreno, L.; Vargas, T.; Martínez, J.; Casas de Prada, Jesús Manuel
Fonte: Universidade do Chile Publicador: Universidade do Chile
Tipo: Artículo de revista
EN_US
Relevância na Pesquisa
37.57%
A two-dimensional (2-D) model for a heap or dump bioleaching of a copper ore containing mainly chalcocite and pyrite has been developed. The rate of the mineral sulfide dissolution was related to the rate of oxidation by bacteria attached onto the ore surface. The latter was calculated using the model of Michaelis–Menten, where both temperature and dissolved oxygen in the leach solution were taken into account by the kinetic equation. Oxygen transport through the ore bed was associated with natural air convection originating from the decrease in gas density inside the ore bed, which was attributable not only to heating, but also to humidification and decrease in the oxygen concentration. The model was used to estimate air-velocity fields and profiles of temperature and oxygen concentrations as well as mineral conversions during the bioleaching operation for ore beds with different pyrite contents, bacterial populations, widths, heights, and permeabilities. The model provides a useful tool for the design, improvement, and optimization of industrial operating conditions.

Comparison of chalcopyrite bioleaching after different microbial enrichment in shake flasks

Yu, Chu; Qiu, Wenqin; Chai, Liyuan; Uribe, Paulina; Liu, Xinxing; Qiu, Guanzhou; Liu, Jianshe; Xia, Lexian
Fonte: Universidade do Chile Publicador: Universidade do Chile
Tipo: Artículo de revista
EN_US
Relevância na Pesquisa
37.78%
Artículo de publicación ISI; The bioleachings of chalcopyrite ore were compared after inoculating different cultures enriched from the original acid mine drainage sample. The results showed that the higher bioleaching performance was achieved for inoculation with the enrichment D (0.5 % S, 2 % iron and 1 % chalcopyrite) compared to other enrichment systems. The generated ferric precipitation during bioleaching had a key influence on the final copper extraction. After enrichment, higher ratio of iron-oxidizer and higher ratio of sulfur-oxidizer existed in enrichment B and C, respectively. These caused the different bioleaching behaviours from other systems. Maintaining a suitable equilibrium between iron- and sulfur-oxidizers is significant to decrease ferric precipitation or postpone its formation, finally prolong efficient bioleaching period and improve copper extraction.

Comparison of chalcopyrite bioleaching after different microbial enrichment in shake flasks

Liu, Jianshe; Liu, Xinxing; Qiu, Wenqin; Chai, Liyuan; Uribe, Paulina; Yu, Chu; Qiu, Guanzhou; Xia, Lexian
Fonte: Universidade do Chile Publicador: Universidade do Chile
Tipo: Artículo de revista
EN_US
Relevância na Pesquisa
37.78%
Artículo de publicación ISI; The bioleachings of chalcopyrite ore were compared after inoculating different cultures enriched from the original acid mine drainage sample. The results showed that the higher bioleaching performance was achieved for inoculation with the enrichment D (0.5 % S, 2 % iron and 1 % chalcopyrite) compared to other enrichment systems. The generated ferric precipitation during bioleaching had a key influence on the final copper extraction. After enrichment, higher ratio of iron-oxidizer and higher ratio of sulfur-oxidizer existed in enrichment B and C, respectively. These caused the different bioleaching behaviours from other systems. Maintaining a suitable equilibrium between iron- and sulfur-oxidizers is significant to decrease ferric precipitation or postpone its formation, finally prolong efficient bioleaching period and improve copper extraction.

Formation of hydrocarbon gaseous compounds during bioleaching of copper sulphide minerals with mesophilic microorganisms

Vargas, T.; Townley, B.; Escobar, B.; Luca, R.
Fonte: ELSEVIER Publicador: ELSEVIER
Tipo: Artículo de revista
EN
Relevância na Pesquisa
37.69%
An experimental study was conducted for assessing the formation of hydrocarbon gaseous compounds during bioleaching of copper sulphide ores with mesophilic microorganisms. Three different mineral samples were used: a pyrite concentrate, a chalcopyrite concentrate and a copper sulphide ore rock from El Teniente mine, Chile, containing 1.2% copper. Mineral samples were bioleached in 250 ml shake flasks containing 100 ml of basal medium inoculated either with a pure strain of Acidithiobacillus ferrooxidans or a natural bacteria consortium obtained from the acid leaching of the El Teniente copper ore in columns. Each sealed shake flask system was fed with a flow of synthetic air and the exit stream was passed through a column containing an adsorbent material and next through a water trap to avoid back-contamination with air from the environment. Compounds present in the adsorbent material after 90 days of bioleaching were analysed using a gas chromatography mass spectrometry technique with a procedure that detects 162 different hydrocarbon gaseous compounds. Experimental results permitted to identify the formation of significant amounts of five different types of hydrocarbon gaseous compounds: di-,tri- and penta-methyl benzene, 11th-ethyl alkane and branched alkanes. The number of formed gaseous hydrocarbon compounds increased in experiments conducted with the natural bacterial consortium...

The role of Acidithiobacillus Caldud in the bioleaching of metal sulfides

Semenza,M.; Viera,M.; Curutchet,G.; Donati,E.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2002 EN
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37.38%
In the absence of iron, dissolution of zinc sulfide was enhanced by the action of Acidithiobacillus caldus at 40ºC. The bioleaching mechanism was similar to that observed for mesophilic species of Acidithiobacillus at 30ºC, although the final metal recovery was lower. When iron was added to the cultures, the solubilization of zinc and copper from the sulfides was higher than that in sterile controls. The activity of the cells was through two indirect mechanisms (acid and oxidant mechanisms, for zinc and copper sulfides respectively). A. caldus did not enhance the dissolution of nickel sulfide neither in the absence nor in the presence of iron.

BIOLEACHING OF COPPER SULPHIDE FLOTATION CONCENTRATE IN BATCH REACTION SYSTEM USING MESOPHILE AND THERMOPHILE MICROORGANISMS

DE BARROS LIMA,RENATA; GOMES FERREIRA LEITE,SELMA; SILVA FRANCISCO PEREIRA,GABRIELLA; CESARIO DE AMARAL,ISABELLA; GONZAGA SANTOS SOBRAL,LUIS
Fonte: DYNA Publicador: DYNA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2012 EN
Relevância na Pesquisa
37.38%
This work aims at optimizing the use of consortiaof mesophile and thermophile microorganisms (moderate and extreme ones) in the leaching process of copper sulphidesflotation concentrate, containing approximately 30% bornite (Cu5FeS4) and 70% chalcopyrite (CuFeS2), for extracting copper.The objective of the bioleaching tests was to evaluate the performance of those microorganisms, varying specific parameters such as: the composition of the leaching solution, the presence of an energy source (ferrous sulphate), and the inoculation of cultures . To ensure optimal conditions for the microorganisms to act, the pH, temperature, and stirring speed were controlled. Finally, from the microbial action and using agricultural fertiliser (N:P:K sources), a copper extraction of more than 85% was achieved.

A Mintek perspective of the past 25 years in minerals bioleaching

Gericke,M.; Neale,J.W.; van Staden,P.J.
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2009 EN
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SYNOPSIS The microbial leaching of metal sulfides is now an established biotechnological technology. Over the past 25 years, refinements in the engineering design of bioleaching processes have paralleled advances in our understanding of the diversity and role of the micro-organisms driving the process and the mechanisms by which micro-organisms enhance metal sulfide oxidation. Commercial success started with the treatment of refractory gold concentrates using mesophilic micro-organisms, followed by the development of tank bioleaching processes for the treatment of base metal concentrates. This was, initially, a mesophilic process with limited potential for recovery of copper from chalcopyrite concentrates due to slow rates and low copper extractions. The exploitation of thermophiles represents a major breakthrough in the development of bioleaching technology for the treatment of chalcopyritecontaining ores and concentrates. This development also opened the route to heap bioleaching of chalcopyrite ores, which is now a major focus of research programmes and piloting campaigns. This paper reviews the historical development of minerals bioleaching processes and gives an update on the current status of commercial tank and heap bioleach operations around the world.

Review of the role of microbiology in the design and operation of heap bioleaching processes

Gericke,M.
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
Relevância na Pesquisa
37.85%
Over the past few decades the commercial application of heap bioleaching technology for the extraction of base metals has become increasingly important, due mainly to the depletion of high-grade ore reserves. Heap bioleaching is widely used for the extraction of copper from secondary copper sulphide ores. The design and engineering aspects of the process have received considerable attention, but issues related to the microbiology of the process have been subjected to less rigorous scrutiny. The major role of micro-organisms in bioleaching processes is to catalyse the regeneration of ferric iron and protons, from ferrous iron and by sulphur oxidation respectively. It is accepted that even the most carefully engineered heaps are heterogeneous in terms of temperature, pH, the presence of anaerobic pockets, irrigation efficiency, and dissolved solutes. Since interactions between solution chemistry, mineralogy, and microbial populations exist in heaps, a better understanding of the correlation between microbial numbers and types with changes in these chemical and physical profiles with time would be beneficial during process design and operation of heaps, and could result in faster start-up times and higher metal recoveries. This paper reviews the role of microbiology in heap bioleaching processes. Aspects such as microbial diversity...

Potential for bioleaching copper sulphide rougher concentrates of Nchanga Mine, Chingola, Zambia

Manchisi,J.; Hansford,G.S.; GaylardI,P.; Simukanga,S.; Nyirenda,R.L.; Sichalwe,A.
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
Relevância na Pesquisa
37.78%
Laboratory investigations were conducted to establish the feasibility of bioleaching a mixed copper oxide/sulphide rougher concentrate from Nchanga Mine on the Zambian Copperbelt. The objective was to determine the kinetics and extent of copper extraction for this material. Batch experiments were conducted under different solution conditions in stirred tank bioreactors. The progress of (bio)leaching was monitored through measurements of soluble ferrous and ferric iron, copper, pH, and redox potentials, while bacterial activity was monitored online through O2 and CO2 gas utilization rates. About 20 per cent copper was solubilized within 2 hours in all cases of non-oxidative (abiotic), oxidative (abiotic), and bioleaching experiments. This was attributed to the dissolution of mainly copper oxides. Subsequently, bioleaching experiments resulted in an overall copper extraction of 93 per cent, with up to 8 g.L-1 copper after six leaching days, compared to 58 per cent copper extraction in the abiotic oxidative acid leaching experiments. However, there was little effect of time (i.e. poor dissolution kinetics) on copper recovery for abiotic non-oxidative acid leaching of the material. Hence, the rate of sulphide leaching increased due to the activity of bacteria. Thus...