Role of Acidothermophilic Autotrophs in Bioleaching of Mineral Sulphide Ores (original) (raw)
Related papers
2010
The development of biotechnological processes, based mainly on the activity of the acidophilic chemolithotrophic, proved their efficiency in recovering metals from sulphides ores and mining drains and in bioremediation of the polluted environment with residual inorganic substances, like the heavy metals ions and their compounds. Due to the influence of the physical-chemical factors on the development and the metabolic activity of the microorganism's present in the industrial effluents, the study of these parameters was imposed for raising the efficiency of the processes of adsorption and biosolubilization of the metallic ions. A special importance for using bacteria of the genus Acidithiobacillus in the biosolubilization processes of heavy metals from acid mine tailings is represented by the resistance of these bacteria to high concentrations of metal ions. The experiments prove a strong relationship between the acidity of the medium and the behaviour of the acidophilic chemolithotrophic bacteria. The comparative analyses regarding the influence of metallic ions (Cu 2+ , Zn 2+ and Fe 2+) on the physiologic diversity of the Acidithiobacillus populations, isolated from the mining sites, demonstrated the higher resistance of these bacteria to higher concentrations of metallic ions.
Factors affecting bioleaching kinetics of sulfide ores using acidophilic micro-organisms
BioMetals, 1999
Recovery of metal values from sulfide ores by use of acidophilic microorganisms is gaining importance. A number of commercial/pilot plants are setup to find out the techno-economic feasibility of the overall process. The main drawback in the process is the slow kinetics of dissolution of metal values from the sulfide ores. To make the technology more attractive the kinetics should be improved considerably. There are various factors which determine the overall kinetics such as bacterial activity and concentration, iron and sulfur oxidation, oxygen consumption, reactor design and nature of ore. A brief review has been made dealing with the above parameters.
IntechOpen eBooks, 2023
The analysis of the variables, bacterial population, and oxidation-reduction potential (ORP) during the bioleaching of sulfide ores by a bacterial strain of Acidithiobacillus ferrooxidans, isolated from acid mine effluent, aims at the solubilization of copper and the liberation of the gold present in an ore containing more than 80% sulfides. It was studied at different pulp densities (1, 2, and 6%-W/V) and with a 9 k medium at different ferrous sulfate concentrations (0, 3, 6, 9, 12, and 15 g/L), keeping temperature and pH constant. The tests were carried out in three consecutive stages, starting with inoculum, whose cell content was 7.05x10 7 Cell/mL, then the strain with the highest population obtained in the previous stage was used, observing the variation in the periods of adaptation and growth. During the bioleaching of sulfide ores, in the first stage, the maximum bacterial population achieved was 4.75x10 7 Cell/mL in 24 days with 6 g/L ferrous sulfate, in the second stage, the maximum population was 6.30x10 7 Cell/mL without the addition of ferrous sulfate, and in the third stage, the bacterial population became 4.51x10 7 Cell/mL. The exponential characteristic growth of the population started at approximately 13, 8, and 3 days, respectively in each stage.
Transactions of Nonferrous Metals Society of China, 2008
Mining companies have become increasingly aware of the potential of microbiological approaches for recovering base and precious metals from low-grade ores, and for remediating acidic, metal-rich wastewaters that drain from both operating and abandoned mine sites. Biological systems offer a number of environmental and (sometimes) economical advantages over conventional approaches, such as pyrometallurgy, though their application is not appropriate in every situation. Mineral processing using microorganisms has been exploited for extracting gold, copper, uranium and cobalt, and current developments are targeting other base metals. Recently, there has been a great increase in our knowledge and understanding of both the diversity of the microbiology of biomining environments, and of how the microorganisms interact with each other. The results from laboratory experiments which have simulated both stirred tank and heap bioreactor systems have shown that microbial consortia are more robust than pure cultures of mineral-oxidizing acidophiles, and also tend to be more effective at bioleaching and bio-oxidizing ores and concentrates. The paper presented a concise review of the nature and interactions of microbial consortia that are involved in the oxidation of sulfide minerals, and how these might be adapted to meet future challenges in biomining operations.
Chemolithotrophic bacteria in copper ores leached at high sulfuric Acid concentration
Applied and environmental microbiology, 1997
Extensive bacterial growth was observed when copper sulfide ores were leached with 0.6 N sulfuric acid. The bacterial population developed in this condition was examined by characterization of the spacer regions between the 16S and 23S rRNA genetic loci obtained after PCR amplification of the DNA extracted from the leached ore. The spacers observed had the sizes found in strains of "Leptospirillum ferrooxidans" and Thiobacillus thiooxidans, except for a larger one, approximately 560 bp long, that was not observed in any of the strains examined, including those of Thiobacillus ferrooxidans. The bacteria with this last spacer were selected after culturing in mineral and elemental sulfur media containing 0.7 N sulfuric acid. The spacer and the 16S ribosomal DNA of this isolate were sequenced and compared with those in species commonly found in bioleaching processes. Though the nucleotide sequence of the spacer showed an extensive heterologous region with T. thiooxidans, the s...
Systematic and Applied Microbiology, 1985
Acidophilic microorganisms were enriched from acid mine water samples and differentiated by their growth in liquid media containing either glucose or different inorganic compounds as electron donors. The choice of substrate for enrichment cultures determined the substrate utilization pattern on subsequent transitions. The solubilization of aluminum, cobalt, copper, iron, nickel and zinc from sulfide ore material was determined with three selected enrichment cultures. Relative differences with respect to the oxidation of sulfide minerals could be attributed to the previous growth history of the test cultures.
Proceedings of the Institute of Biology, Romanian Academy, Bucharest, 2002
The study of the research regarding the acidophilic procaryote microorganisms (eubacteria and archaea) is very new because of the importance of these microorganisms in biotechnology and in the depollution of the environment. The growth and activity of bacteria in the acidic biotopes depend greatly on the ecological conditions of the environment. Through their activity the acidophilic bacteria determine changes of the environment pH and of the oxido-reduction potential and during their metabolism, they can elaborate different useful substances, which have complex oxidizing or reductive properties. The acidity influences in a different way the life and activity of the different types of microorganisms present in low pH media. In this context, this paper presents the effects of acidity in static and continuous agitation conditions on the growth and activity of the acidophilic chemolithotrophic sulphur-oxidizing bacteria, isolated from the acidic mining effluents from two mines: Baia and Valea Şesei.
Potential of Chemolitotrophic Bacteria From Gold Mining Area in Sulfur Oxidation Process
Biosaintifika: Journal of Biology & Biology Education
Gold in nature is covered by rocks which contain sulfide minerals such as pyrite, chalcopyrite, arsenopyrite, and others sulfide minerals. Chemolithotrophic bacteria have the ability to oxidize the sulfur compounds and can be used in the process of releasing gold from carrier rocks which contain sulfide minerals. This research aimed to explore and identify the chemolithotrophic bacteria from gold mining areas as well as determine their potential for sulfur oxidation. The methods used in this study were exploring the potential of bacteria in sulfur oxidation and describing the variety of bacteria that were isolated from gold mining areas by 16s rRNA identification. The results showed that there were six isolates from isolation with Starkey solid medium, i.e. Bl-1, B1-2, B1-3, B1-4, B1-5 and B1-6 that were similar to Paenibacillus sp., Enterobacter ludwigiis train E8-13, uncultured Burkholderia sp., Uncultured bacterium clone N4.5, Bacillus subtilis strain CICC 10023, and Bacterium en...
Effect of Substrates During the Adaptation of Indigenous Bacteria in Bioleaching of Sulphide Ores
American Scientific Research Journal for Engineering, Technology, and Sciences, 2017
It is well known that thermophile bacteria (40-60°C) are indicated for leaching chalcopyrite. However, it is a long bioleaching process and this kind of bacteria is not available in indigenous areas. On the other hand, mesophilic bacteria (20-40°C) are easily found in many acidic drainage mines, which could be an opportunity to decrease investment costs as well as operation cost during the treatment. However, to achieve that mesophilic bacteria are able to leach chalcopyrite, it is necessary to select the appropriate conditions such as the choice of an adequate substrate, the pulp density, the pH, and oxidation reduction potential. In addition, a decrease in the latency period during bacterial adaptation and bioleaching process is necessary. Accordingly, the objective of this research is to study the bacterial adaptation of stocks in three culture media containing various sources coming from local sites of acidic drainage mines (Kipushi, Kisenda, Kamoto)at Katanga copperbelt (Democr...
Microbiological and geochemical dynamics in simulated-heap leaching of a polymetallic sulfide ore
Biotechnology and Bioengineering, 2008
The evolution of microbial populations involved in simulated-heap leaching of a polymetallic black schist sulfide ore (from the recently-commissioned Talvivaara mine, Finland) was monitored in aerated packed bed column reactors over a period of 40 weeks. The influence of ore particle size (2-6.5 mm and 6.5-12 mm) on changes in composition of the bioleaching microflora and mineral leaching dynamics in columns was investigated and compared to fine-grain (<2 mm) ore that was bioprocessed in shake flask cultures. Both column reactors and shake flasks were inoculated with 24 different species and strains of mineral-oxidizing and other acidophilic microorganisms , and maintained at 378C. Mineral oxidation was most rapid in shake flask cultures, with about 80% of both manganese and nickel and 68% of zinc being leached within 6 weeks, though relatively little of the copper present in the ore was solubilised. The microbial consortium that emerged from the original inoculum was relatively simple in shake flasks, and was dominated by the iron-oxidizing autotroph Leptospirillum ferriphilum, with smaller numbers of Acidimicrobium ferrooxidans, Acidithiobacillus caldus and Leptospirillum ferrooxidans. Both metal recovery and (for the most part) total numbers of prokaryotes were greater in the column reactor containing the medium-grain than that containing the coarse-grain ore. The bioleaching communities in the columns displayed temporal changes in composition and differed radically from those in shake flask cultures. While iron-oxidizing chemoautotrophic bacteria were always the most numerically dominant bacteria in the medium-grain column bioreactor, there were major shifts in the most abundant species present, with the type strain of Acidithiobacillus ferrooxidans dominating in the early phase of the experiment and other bacteria (At. ferrooxidans NO37 and L. ferriphilum) dominating from week 4 to week 40. With the coarse-grain column bioreactor, similar transitions in populations of iron-oxidizing chemoautotrophs were observed, though heterotrophic acidophiles were often the most abundant bacteria found in mineral leach liquors. Four bacteria not included in the mixed culture used to inoculate the columns were detected by biomolecular techniques and three of these (all Alicyclobacillus-like Firmicutes) were isolated as pure cultures. The fourth bacterium, identified from a clone library, was related to the Gram-positive sulfate reducer Desulfotomaculum salinum. All four were considered to have been present as endospores on the dried ore, which was not sterilized in the column bioreactors. Two of the Alicyclobacillus-like isolates were found, transiently, in large numbers in mineral leachates. The data support the hypothesis that temporal and spatial heterogeneity in mineral heaps create conditions that favour different mineral-oxidizing microflora, and that it is therefore important that sufficient microbial diversity is present in heaps to optimize metal extraction.