Papers by Keyword: Bioleaching

Abstract: The extraction and processing of silver minerals produce significant amounts of waste, which poses environmental challenges due to their low metal content and the potential release of toxic elements. The study investigates the application of Acidithiobacillus ferrooxidans (AF) bacteria to the bioleaching of these waste materials, with the aim of maximizing the recovery of iron, copper and arsenic. The objectives of the study include characterizing waste materials, optimizing the bioleaching process parameters and evaluating metal extraction efficiency. The samples were leached with additives (CuSO₄ 5H₂O and AgNO₃) to accelerate the kinetics of metal dissolution in solution and reduce the bacterial leaching time. The results showed that samples 1-2 and 2-2 containing additives had higher values of dissolved iron and copper in the leachate compared to samples 1-1 and 2-1 without additive application.

Abstract: The cobalt content in LIB (Lithium-ion Battery) can be recycled using green technology through a bioleaching process with the help of microorganisms to have high efficiency, low cost, easy method, and environmentally friendly. The bacterial strain of A. ferrooxidans in the bioleaching process isolated from acid mine water was capable to extracting cobalt in LIB to obtain pure metal ions. The aim of this research is to isolate bacteria A. ferrooxidans from acid mine water in order to extract the element cobalt from a LIB. This study has recovery with culture time of 0-14 days, aerobic systems, inoculum concentrations of 5%, 10%, and 20%. The optimization of bacterial growth was done by aerating the culture. The recovered cobalt were analyzed from the filtrate after the bioleaching process using ICP analysis. LIB and sediment of the bioleaching process were analyzed by XRD, SEM and EDX. The conclusion of this study showed that the recovery of cobalt metal (Co) using the bacterial strain of A. ferrooxidans was obtained at 73.95% for 14 days with the addition of a battery cathode of 1 gram/100 ml at the optimum conditions obtained when the addition of 20% inoculum, pH: 2-4, temperature: 30°C, and the aeration system uses an aerator. Bacterial strains isolated from acid mine drainage have the potential as oxidizing agents for lithium and cobalt metals in bioleaching processes.

Abstract: Spent catalyst is listed as one of the hazardous wastes. Based on the toxicity characteristic shows that spent catalyst contains some heavy metals at concentration above the regulations limits. This situattion becomes an important issue in nowadays. In this research, fungus Aspergillus niger was investigated to produce weak organic acid (citric acid). Batch experiments were performed to compare the leaching efficiency from spent catalyst of pulp density (2% and 4%) and particle size (212 µm, 150 µm and 75 µm). Result showed that after direct bioleaching process, maximum recovery of valuable metal 24.94%, 7.42%, 1.09%, 3.51%, 4.87% and 1.66% were achieved for aluminum, calcium, iron, copper, silver and platinum respectively at 2% pulp density. Overall data shows that metal recovery at pulp density 2% are higher than 4% pulp density. The maximum recovery based on particle size shows that the smaller particle (75 µm) the higher metal recovery (Al, Ag and Pt) and for some metals was different such as Fe, Cu and Ca.

Abstract: The goal of the present work was to perform bioleaching of uranium from low grade ore from Vostok deposit (Republic of Kazakhstan), which was previously subjected to long-term acid leaching. The ore initially contained from 0.15 to 0.20% of uranium in the form of uraninite, but ore samples used in the study contained about 0.05% of uranium, as it was exhausted during acid leaching, and uranium was partially leached. Representative samples of ore were processed in 1 m columns, leach solutions containing 5, 10, 20 g/L of sulfuric acid and bacterial cells (about 10⁴) were percolated through the ore. Leaching was performed at ambient temperature for 70 days. In one of the percolators, the leaching was performed with leaching solution containing 10 g/L of H₂SO₄, cells of A. ferrooxidans, and 0.5 g/L of formaldehyde. Leaching with the solution containing 5, 10, and 20 g/L of sulfuric acid made it possible to extract 50, 53, and 58% of uranium. Addition of formaldehyde in leach solution led to the decrease in uranium extraction extent down to 37%. Thus, the results of the present work demonstrated that uranium ore exhausted during long-term acid leaching may be successfully subjected to bioleaching, that allows extracting residual quantities of uranium. Leaching rate of uranium from exhausted ore depended on both sulfuric acid concentration and microbial activity of bacteria isolated from acid mine drainage, formed on uranium deposit. In the same time, acid mine drainage may be used as a source of inoculate, to start bioleaching process.

Abstract: This study was a continuation of previous work designed to further explore the effect of different culture condition on the recovery of the valuable metals by bacteria. The experiment focused on the Nandan lead-zinc tailings from different depths. First of all, the study systematically performed multi-elements analysis. Subsequently, the effect of the temperature and agitation speed on the bacterial growth was investigated. The data revealed that the temperature of 35°C and the agitation of 160 rpm were the optimum culture conditions for the bacteria. Finally, the bioleaching experiments were performed to explore the ability of bioleaching the tailings. The study illustrated that the microorganism was able to effectively extract valuable metals from different depths samples.

Abstract: A series of the experiments were carried out on the Nandan lead-zinc tailings management and one bioleaching method was proposed with the purpose of recovering the valuable metal such as Zn. Firstly, multi-elements analysis was performed to provide theoretical data. Secondly, the effect of the pH on the bacterial growth and Fe²⁺ oxidation was investigated. The results showed that pH at 2.5 was the optimum for the bacteria. The concentration of the bacteria at pH 2.5 can be up to 9.3×10⁷ cells/mL. Finally, the bioleaching treatment was performed to study the potential of bioleaching the tailings. The data illustrated that the method of bioleaching can extremely recover metals such as zinc from the tailings, which provided novel insights into metal recycling.

Abstract: Acidiphilium sp. DSM 27270 (Yenapatur) forms part of a microbial consortium isolated from copper mines in Chile, that is currently used in state of the art industrial-scale biotechnology. Its taxonomic assignment is still tentative and is metal resistance and homeostatic responses poorly characterized. Here we report the genomic taxonomy evaluation of the Yenapatur strain and the preliminary characterization of its metal resistance and homeostatic responses. The genome of Yenapatur was re-assembled, annotated and compared to other sequenced strains of the genus. Genomic signatures were derived to better define the taxonomy of the strain. The minimum inhibitory concentrations of diverse cations and anions (Cu (II), Fe (II), Mg (II), Mn (II), Zn (II), Al (III), As (III), Fe (III), chloride and nitrate) were determined. Known resistance determinants were profiled in the genome of Yenapatur and publically available sequenced Acidiphilium strains. Results are presented and discussed under the light of the operational conditions in which Yenapatur thrives.

Abstract: Environmentally friendly mining technologies have to be developed extensively to avoid the impact of mining activities with respect to environmental concern. One example of such technology is bioleaching which has been developed worldwide and is regarded as an appropriate technology for the extraction of metals from polymetallic ores such as supergene porphyry copper ores, mainly consisting of secondary copper sulfides, including chalcocite (Cu₂S), covellite (CuS), or oxide minerals, i.e., cuprite (Cu₂O) and tenorite (CuO). The extraction process for this complex ore generally requires high temperature, high pressure and/or high acid concentration. For the economic extraction of valuable copper from such ores, the bioleaching of supergene porphyry copper ore from Sungai Max in Southeast Sulawesi of Indonesia was investigated in shake-flask experiments at room temperature (28 °C) for 14 days using an iron- and sulfur-oxidizing bacterium (Alicyclobacillus sp.) indigenous to an Indonesian mine site. The main mineralogical composition of gangue minerals contained in this ore sample included quartz, muscovite, kaolinite and alunite. The relatively high copper extraction efficiencies were obtained over a 14-day period of the bioleaching experiments as a function of pH, pulp density and NaCl concentration. Therefore, the findings of this study provide the first information of bioleaching process of supergene porphyry copper ores in Indonesia that may highly be useful for developing an economical and environmentally friendly extraction process of such complex ores.

Abstract: After 24h of exposure to acidic media, pyrite generates reactive oxygen species (ROS). Freshly-crushed pyrite with grain sizes between 50-100 μm at a 5 % (w/v), pulp density generated 0.17 ± 0.01 mM H₂O₂, while 10% pyrite generated 0.29 ± 0.01 mM and 30 % pyrite generated approximately 0.83 ± 0.06 mM. These levels of H₂O₂ inhibit iron oxidation in iron-grown cells of Acidithiobacillus ferrooxidans^T but not in pyrite-grown cells. ROS originating from pyrite, which was incubated for 24 h in acidic medium, prohibited pyrite dissolution by iron-grown cells, while pyrite-grown cells were adapted to these concentrations of ROS. Periodical addition of 100 μM H₂O₂ to pyrite cultures inoculated with pyrite-grown cells did not lower iron dissolution as it was observed with iron-grown cells. By high throughput proteomics analysis, an increased expression of proteins related to oxidative stress management, iron-and sulfur oxidation systems, carbon fixation and biofilm formation was observed in biofilm cells grown on pyrite compared to iron-grown cells.

Abstract: The thermophilic archaean, Acidianus brierleyi, was examined for its feasibility to bioleach copper from a low-grade chalcopyrite ore (1.15 % copper, 20.4 % iron and 2.63 wt% sulfur) at 65°C and pH 1.8-2.5. The chalcopyrite leaching was markedly accelerated in the presence of A. brierleyi, and an extremely high 80% leaching of copper in the low-grade ore (25-38 μm particles) was achieved in 14 days in a batch stirred reactor. By comparison, the leaching of iron was very slow and only a slight 5 % iron was leached in 14 days in the presence or absence of A. brierleyi. In other words, A. brierleyi selectively leached chalcopyrite while magnetite leaching by A. brierleyi was negligible. Moreover, bioleaching of the low-grade ore (53-75 μm particles) yielded 55% copper recovery after 20 days of operation in a column reactor. The good results for the copper bioleaching in the column reactor are very similar to those in the stirred reactor. These results lead to the conclusion that the thermophile bioleaching with A. brierleyi is attractive as an economical and environmentally friendly process for good copper extraction from low-grade chalcopyrite ore.