Submit manuscript...
eISSN: 2575-906X

Biodiversity International Journal

Review Article Volume 1 Issue 3

The catalytic role of Acidithiobacillus ferrooxidans for metals extraction from mining – metallurgical resource

Maluckov BS

University of Belgrade, Serbia

Correspondence: Biljana S Maluckov, Technical Faculty in Bor, University of Belgrade, Vojske Jugoslavije 12, 19210 Bor, Serbia

Received: July 28, 2017 | Published: October 25, 2017

Citation: Maluckov BS. The catalytic role of Acidithiobacillus ferrooxidans for metals extraction from mining - metallurgical resource. Biodiversity Int J. 2017;1(3):109-119. DOI: 10.15406/bij.2017.01.00017

Download PDF

Abstract

Mining and metallurgy are the necessary economy branch in the global technological development on which relies a large part of other industries. Mining and ore processing are changing geological conditions, producing a tremendous amounts of waste worldwide, causing negative consequences for the environment and lead to climate change. Negative effect on the environment can be mitigated by treatment of resource from mining and metallurgy with microorganisms. Microorganisms can be used for the leaching of metals from ore, concentrates and waste materials, but also for the bioremediation of acide mine drainage. On that way, it reduces the release of metals into the environment. In this paper is considered the application of Acidithiobacillus ferrooxidans in biological treatment of resource from mining and metallurgy of copper in order to utilization of it for recovery of metals.

Keywords: mining, bioleaching, a. ferrooxidans, copper

Introduction

Mining and metallurgy have negative consequences for the environment1‒3 and lead to changes in geological4 and climatic conditions.5 Mining-metallurgy operations include the extraction, preparing of ores (crushing ore and flotation), processing of concentrates, and the disposal of waste rock and by-products. The main waste in mining and metallurgy are waste rocks, flotation tailings and slag, which often contain significant amounts of valuable metals; sometimes even more than the ore. Because of the increased exposure of surface and quantity of minerals in ores and waste to water and air, the natural dissolution of sulfides is increased in mining regions which leads to formation of acid mine drainage (AMD) rich with metals.The ores, concentrates and waste from copper mining and metallurgy can be subjected to biological treatment in order to utilize this resource for recovery of metals.In addition, the microorganisms can be used for remediation of AMD.

The dissolution of metals from mineral ores by action of microorganisms, and subsequently recovery of metals from solution is known as bioleaching. It is a cost-effective method for recovery of metals from minerals, particularly low-grade ore, and waste from current mining operations; requiring moderate capital investment and low operating costs.6 There are many publications on development of bioleaching i.e. biohydrometallurgy.7‒13 The advantages of bioleaching of ores and concentrates are compared to conventional metodes, such as pyrometallurgy,reflected in: the potential for processing of low-grade deposits and deposits with significant amounts of arsenic,14‒18 reprocessing waste, lower energy consumption, as well as environmental benefits (e.g., no toxic gases).19

In the industrial leaching processes, microorganisms that are found in nature can be used. Dumps of sulphide ores, waste rocks and acid mine water are very complex microbial habitats. Most acidophilic microorganisms can be isolated from these sources.19‒22 The most important role in the development of industrial bacterial leaching is played by the acidophilus bacteria Acidithiobacillus ferrooxidans.12,23,24 In this paper we review the physiology of acidophilic microorganisms, and application areas of bioleaching with Acidithiobacillus ferrooxidans in copper mining and metallurgy, as well as the impacts of electrochemistry, type of minerals and addition of catalysts to recovery of metals on the catalytic activity of the bacteria .

Physiology of acidophilic microorganisms

Many microorganisms can survive extreme physical and geochemical conditions (extreme temperature, pH values, salinity, pressure, drying, radiation, etc). They are extremophiles. Acidophiles are a type of extremophiles which progress in an acid environment with pH < 3,6,19,25 and many of them cannot grow in neutral pH environments.19 They grow up in naturally acidic environments (sulfur basins, geysers) and human made acidic environments (coal mining and metal ores). This diverse group of organisms includes archaea, bacteria, fungi, algae, and protozoa.26

The Acidithiobacillus group of microorganisms is important for dissolution of Cu, Zn, Fe and As, from different ores and waste.21 They accelerate the dissolution of sulfide minerals, which leads to an increased production acid mine drainage.3,27 Bacteria possess genes for most of elements known to human society. These genes determine transport systems of nutrient substances, including K, P and Fe, which are necessary to intercellular balance between needs and toxicity, as well as for detoxication or elimination of toxic elements such as Hg, Pb, As, Cr, Cd and Ag.28

Acidithiobacillus ferrooxidans (A. ferrooxidans) is a Gram negative, acidophilic, chemolithoautotrophic bacteria involved in bioleaching and acidic drainage.29 Its previous name was Thiobacillus ferrooxidans, and it was reclassified in 2000.30 This microorganism plays a key role in the microbial communities involved in bacterial- chemical processes of bioleaching under mesophilic conditions. It uses Fe2+, H2S, S0, reduced sulfur inorganic compounds and molecular hydrogen as energy sources.31 In aerobic conditions, the ferrous iron and/or reduced sulfur compounds present in ores, are oxidized to the ferric iron and sulfuric acid, respectively. Following an initial oxidation of the substrate, the electrons from the ferrous iron and sulfur are included in the respiratory chain and climb over several redox proteins on oxygen. However, the oxidation of ferrous iron and reduced sulfur compounds also must provide electrons for the reduction of NAD (P), which is later required for many metabolic processes, including CO2 fixation. Oxidation products then chemically attack the metal sulfides, which leads to solubilization of metal ore, and removal of sulfur.29 The oxidation of sulfur to sulfuric acid produces a strongly acidified environment.31 When A. ferrooxidans grows under anaerobic conditions, it accelerates the dissolution of the ferric iron oxy-hydroxide by oxidation of elemental sulfur, which is a common reduction of iron. This is a key reaction in the "Ferredoks" process for extracting nickel from ore laterite.32

Biological copper is generally associated with the three types of ligand: the chains of histidine (His), cysteine (Cys), and methionine (Met), with a few exceptions. Combinations of Met/His or Met/Cys provide organisms with a dynamic, multi-functional domains that may facilitate the transfer of copper at different extracellular, subcellular and tissue specific conditions in terms of pH, redox environment, as well as the presence of other carriers of copper, or target protein.33 A lot of sulfur is incorporated in proteins, as thiolate or thioether. Sulfur which is bound to metal centres of enzymes give specific properties to Cu enzymes. Sulfur atoms from thiolates, thioethers or rarely disulfide, or inorganic sulfur donors, act as ligands in a variety of copper complexes.34

The iron-oxidizing bacteria A. ferrooxidans produces a type I copper protein, rusticyanin, which is involved in the oxidation processes of Fe2+ .35‒37 Rusticyanin is blue colored, as well as the other type I copper protein.38 It is an acid stable protein, distinct from other types of copper protein I, which are unstable at low pH values.26 In addition, it characterized by a high redox potential (+680mV),39,40 and is functional at pH 2 [41]. The copper in this copper protein is bound to one molecule of cysteine and methionine, and two molecules of histidine.39,42 Cys138 is crucial for bonding of Cu.42 This protein is the main component in the iron respiratory electron transport chain. It is assumed the next respiratory transport chain of electrons from Fe2+ to oxygen:36,37

Cyc2 → rusticyanin → Cyc1(c552) → cytochrome aa3 oxidase(1)

From A. ferrooxidans, a Hip iron sulfur protein with a high potential (high-potential iron-sulfur protein, HPIP) was isolated. This is a redox protein with a high redox potential, required to achieve electron transfer reactions at extreme pH values. Structural analysis of the protein showed the presence of two cysteine residues and a high content of proline residues. The high content of proline is essential for stabilizing the folding of proteins at low pH. Unusual is the presence of a disulfide bridge, which fixes the N terminus of the protein.43 During the contact A. ferrooxidans with chalcopyrite, a significant increase occurs in the activity of the enzymes glutathione reductase (GR), superoxide dismutase (SOD) and thioredoxin reductase (TrxR),44 indicating the formation of reactive oxygen species (ROS).44,45

Chemistry and mechanism of bioleaching

In natural conditions, sulfide minerals chemically oxidize in the presence of oxigen/chemical oxidans and water/wet air (Figure 1). The reactions of the natural chemical oxidation of chalcopyrite and pyrite are shown in Table 1. When the microorganisms are present, they are using Fe+2 and S0 for metabolism where upon Fe+3 and SO-24 are formed (Figure 1). Because of the increased concentration of Fe+3 and SO-24 as a result the metabolism of microorganisms, the dissolution of sulfide minerals and the amount of acidic water increase. Thus, the microorganisms play the role of biological catalysts.

Sulfide Minerals

Chalcopyrite

Pyrite

CuFeS2 +2H2O + 3O2 → Cu+2+ Fe+2 +2H2SO4     (2)

FeS2 +2H2O + 3O2 →Fe+2 +2H2SO4                     (9)

CuFeS2+ H2SO4→ Cu+2 + FeSO4 + 2H+ + 2S0                          (3)

FeS2+ H2SO4→ FeSO4 + 2H+ + 2S0                       (10)

CuFeS2 +4H+ + O2→Cu+2+ Fe+2+ 2H2O+2S0                      (4)

FeS2 +4H+ + O2→Fe+2 + 2H2O+2S0                     (11)

4FeSO4 + 2H2SO4→2Fe2(SO4)3 + 4H+                 (5)

4FeSO4 + 2H2SO4→ 2Fe2(SO4)3 + 4H+                (12)

4Fe+2 + O2+ 4H+→ 4Fe+3+ 2H2O                         (6)

4Fe+2 + O2+ 4H+→ 4Fe+3+ 2H2O         (13)

The resulting Fe+3 disolves CuFeS2:

The resulting Fe+3 disolves FeS2:

CuFeS2 + 2Fe2(SO4)3→CuSO4+ 5FeSO4 + 2S0   (7)

FeS2 + 2Fe2(SO4)3→ 5FeSO4 + SO2-4 +2S0         (14)

CuFeS2 +4Fe+3 → Cu+2 + 5Fe+2 + 2S0   (8)

FeS2 +4Fe+3 → 5Fe+2 + 2S0   (15)

Table 1 Reactions of chemical oxidation of sulphide minerals

Figure 1 Natural oxidation of sulfide minerals in mining area.

The resulting primary sulfur product during metal sulfide dissolution, depends on which sulfide mineral is bioleached. The resulting primary sulfur product is subsequently chemically or biologically transformed into elemental sulfur or sulfate.46 Disulfides FeS2, MoS2 and WS2 are degraded over thiosulfate as the main intermediate. Exclusively iron (III) ions are oxidative solubilizing agents. Thiosulfate degrades to sulfate, with elemental sulfur as a by-product. This explains why only iron (II) ion-oxidizing bacteria are capable of oxidize these metal sulfide.47

All sulfide minerals, which are soluble in acid to a certain degree, produce elemental sulfur by reacting with the ferric ions, formed from the intermediate polysulfides.48 Metal sulfides, PbS, ZnS, CuFeS2, MnS2, As2S3, As4S4 decompose by the iron (III) ions and proton attack. The main intermediates are polysulfides and elemental sulfur (thiosulfate is only a byproduct in later degradation stages). The dissolution takes place by means of H2S*- radicals and polysulfides to elemental sulfur. These metal sulfides can be decomposed by any bacteria capable to oxidize the sulfur compounds.47

There are two mechanisms that improve the degree of leaching the metals from mineral ores by microorganisms in comparison to the pure physically chemical processes. In the direct action, the microorganism directly oxidized minerals and dissolved metals:49

MS + H2SO4 + 1/2O2 →MSO4 + S0 + H2O and S0 +11/ 2O2 + H2O → H2SO4,(16)

where M is bivalent metal.

In the indirect action of microorganisms, Fe3+ is an oxidizing agent for minerals, and the role of organisms is a simple regeneration of Fe3+ from Fe2+ :49

MS+ 2Fe3+→M2+ + 2Fe2+ +S0 and 2Fe2+ + 1/2O2+2H+→2Fe3+ +H2O.(17)

In real microbial leaching, leaching of mineral sulfides is probably a combination of both direct and indirect mechanisms.50 Fowler & Crudwell,51 found no evidence that there is a direct mechanism for bacterial leaching.51 The observations from the scanning slectron microscopy suggested a greater involvement of the indirect oxidation mechanism which utilises the oxidant ferric iron than direct bacterial attachment.52 Today, some scientists believe that only an indirect mechanism is present.

Application of acidithiobacillus ferrooxidans in bioleaching of metals in mining – metallurgical operations

Industrial bioleaching processes can be: In situ bioleaching, bioleaching of dump, bioleaching of heap and bioleaching in reactor (Figure 2). After bioleaching processes, metals are recovery by solvent extraction and electrowinning from the collected pregnant leach solution.

Figure 2 Processes for bioleaching.

The application A. ferrooxidans in bioleaching of metals in mining-metallurgical operations, is possible starting from leaching metals from ores, to leaching of metals from concentrate, till waste (Table 1) Besides that, A. ferrooxidans can be used for pretreatment of acid mine drainage,53,54 as well as for the pretreatment of gold containing ores to the dissolution of sulfides in which the gold is encapsulated55 and bioassisted phytomining.56 Because of tolerance to metals57 and potential absorption of metals,28 A. ferrooxidans can be very effective for bioremediation of heavy metals from polluted environments.28,58 Biological oxidation of ferrous ions by A. ferrooxidans has a positive application and for desulphurization of coal 59,60 and the removal of hydrogen sulfide from gaseous effluents,61 also.

Bioleaching, as each process involving living creatures, is influenced by the environment, physico-chemical and biological factors, which affect the yield of metal extraction. Once the optimal conditions are maintained, the yield of Cu can be high. The optimal conditions for the growth of microorganisms, such as aeration, humidity, pH, temperature, energy sources and nutrients, as well as the absence of potential inhibitors have to be ensured.62 Selection of the suitable microorganisms for the leaching is one of the important factors. Various studies have shown that a mixed culture containing the iron and sulphur oxidizing bacteria is more effective than pure culture.23,63‒65 Iron and sulfur-oxidizing cultures are important for efficient degradation of chalcopyrite, probably due to demands for ferric iron as an oxidizing agent; and for the removal of elemental sulfur that could be formed on the mineral surface64(Table 2).

Type of Substrate

Culture

Technological process

Reference

Waste rocks

mix: Acidithiobacillus ferrooxidans,
Acidithiobacillus thiooxidans,
Leptospirillum ferrooxidans

 

collumn

 

66

Waste rocks

mix: Acidithiobacillus ferrooxidans,
pure Acidithiobacillus thiooxidans
mix: Acidithiobacillus ferrooxidans,
Acidithiobacillus thiooxidans

 

collumn

 

67

Tailing

pure Acidithiobacillus ferrooxidans

shake flasks

68

Tailing

mix: Acidithiobacillus ferrooxidans,
Acidithiobacillus thiooxidans

 

shake flasks

 

69

Low grade
chalcopyrite ore

pure Acidithiobacillus ferrooxidans

 

percolation columns

 

70

Low grade
chalcopyrite ore

mixed culture of predominantly of Acidithiobacillus ferrooxidans

 

heap

 

71

Low grade
chalcopyrite ore

mixed culture of predominantly of Acidithiobacillus ferrooxidans

 

heap

 

72

Low grade copper ore

pure Acidithiobacillus ferrooxidans

collumn

73

Low grade
complex sphalerite

 

pure Acidithiobacillus ferrooxidans

 

collumn

 

74

Low grade copper ore

mix: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans,
Leptospirillum ferrooxidans

 

collumn

 

75

Pyritic chalcopyrite concentrate

pure Acidithiobacillus ferrooxidans
mix: Acidithiobacillus ferrooxidans,
Acidithiobacillus thiooxidans,
Leptospirillum ferrooxidans

 

shake flasks

 

64

Anilite concentrate

pure Acidithiobacillus ferrooxidans

shake flasks

76

Pyrite concentrate
Fly lignite ash

pure Acidithiobacillus ferrooxidans

 

shake flasks

 

77

Chalcopyrite concentrate

mix:Acidithiobacillus ferrooxidans,
Acidithiobacillus thiooxidans,Leptospirillum ferriphilum

 

column reactor

 

78

Conventer slag

pure Acidithiobacillus ferrooxidans

conical flasks

79

Final slag

mix: Acidithiobacillus ferrooxidans,
Acidithiobacillus thiooxidans,
Acidithiobacillus caldus,
Leptospirillum ferrooxidans,
Sulfobacillus thermotolerans

 

stirred tank reactor

 

80

Smelter's dust

mix: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans,
Leptospirillum ferrooxidans

stirred tank reactor

81

Table 2 Application of A. ferrooxidans in bioleaching of metals in mining metallurgical operations

In addition, the strain which is used should also be taken in to account, because there are variations of the biological characteristics of the bacterium with the same genome.82 Unadapted mixed cultures of mesophiles are able to tolerate moderate concentrations of different metal ions. By continual growth of the bacteria in an environment that contains an increasing concentration of metals, the bacteria adapts and becomes tolerant to increasing toxic metals and copper.83,84,85 Treatment of adapted cells A. ferrooxidans which are more tolerant of copper than unadapted cells by protein hydrolyzing enzymes leads to a loss of tolerance to copper.86

Application of acidithiobacillus ferrooxidans in leaching of metals from ores

Leaching of metals from ores in situ (Figure 2) is classified as solvent mining, and according to some, a preparatory process in mining operations. In this type in situ of mining, the effect of microorganisms in these operations and the occurrence of bioleaching are observed. Commercial bioleaching of dumps can be economically justified, since it is considered a cheap technological process. However, the process of bioleaching and metal extraction can be more efficient by constructing specially designed heaps. The planned forming of the heaps creates favorable conditions for optimization of the bioleaching process. By crushing ore and putting it on an impervious surface is more efficient for the distribution of the leaching solution, aeration and collection system.

When the heaps are stacked and irrigated, there is a lag period of the growth and metabolism of the bacteria which contribute to the oxidation of the sulfide. Lag period may be shortened by recirculation of the solution (e.g. raffinate from the solvent extraction) which already contains populations of microorganisms adapted to the conditions of leaching. This ensures that the active bacterial population is distributed throughout the ore. By using the recirculating solution for irrigating the heap with a similar population, the active bacterial population is maintained during the leaching process and it can be used to inoculate the following heap.6

Quantity of leached Cu is proportional to the heap height.70 By increasing the aeration degree, the leaching of Cu is improved.87 Also, the leaching degree is increased with decreasing dimensions of particles and flow of the leaching agent.70 Addition of sulphuric acid to maintain pH 2.0, addition of nutrients and a shorter time of leaching agent recycling lead to an increased concentrations of bacteria in the leaching agent and thus improving the efficiency of the leaching.88

Application of acidithiobacillus ferrooxidans in bioleaching of the ore concentrate

Replacement of pyrometallurgy by biohydrometallurgy in the production of metals from centrates is desirable, due to reduced production cost.11 For commercial bioleaching of the concentrates used projected heaps or reactors. The favorable conditions for bacterial growth can be better controlled in reactors than on heaps.89 Efficiency of leaching depends on retention time of the leaching solution in the reactor.78 The supply of oxygen and carbon-dioxide is very important for cells. Carbon-dioxide is needed as a source of carbon, while oxygen is significant as final electron acceptor in the oxidation process. In reactors, these gases are usually obtained by injection of air into fluid.89 Due to the relatively high costs of supplying the reactor with air, knowing the volume of oxygen consumption of A. ferrooxidans during the oxidation of iron in combination with the external parameters, concentration of dissolved metal ions and the pH of the solution, it is possible to estimate the amount of air required for the commercial bacterial leaching process.82

Application of acidithiobacillus ferrooxidans in bioleaching of waste in mining and copper metallurgy

The main waste - waste rocks, flotation tailings and slag- from mining and metallurgy of copper, are often rich in metal content, and sometimes an even richer source of metals than natural ores. Therefore, different possibilities to recover metals from waste90 have been examined. Bioleaching processes cause significant changes in the mechanical and chemical properties of the waste rocks, and this way they affect stability of dumps and dissolution of metals.

Release of Cu2+ from waste rock by action of acid and bacteria is continuous, and erosion of rocks increases with increasing height of dump and leaching time.67,75 The mineral content of the leached rocks affects the degree of dissolution and precipitation during bioleaching. Porosity of dump and change of size of the rocks are influenced by dissolving, precipitation and clay transport.66 Grinding of particles under pressure from rocks is another factor that affects the stability of dump.67,75 From waste rocks,66,67 flotation tailings68,69 and slag formed in the pyrometallurgy production of copper,79, 80, 91 a significant amount of metals can be recovery by bioleaching although they contain arsenic. The results of Bakhtiari et al,81 indicated that bioleaching is a feasible process for copper recovery from a smelter's dust,81 also.

Application of acidithiobacillus ferrooxidans in treatment of acid mine drainage

Flotation tailings and waste rock containing sulfides of heavy metals, which oxidize by weather processes and the action of native sulfur and iron oxidizing bacteria, as well as dissolved metals, contaminate ground and surface water. This leads to the occurrence of acid mine waters - acid mine drainage (AMD), which adversely affect the ecosystem. Therefore, various methods have been developed92 for the treatment of the acidic, metal-rich mine waters. One of these methods is the biological remediation of acidic mine waters.

A. ferrooxidans, which is primarily responsible for the generation of AMD, is used to oxidize ferrous iron in the contaminated flows before the addition of neutralization materials as an alternative for the addition of chemical oxidants or post-neutralization aeration AMD.53 Oxidation of ferrous iron in to ferric form is possible selectively to precipitate the iron from the solution, because the ferric iron is precipitated at a much lower pH than ferrous iron. Another advantage of this procedure is that after the ferric iron is precipitated (typically at a pH of 2-3), the calcium carbonate can be used for neutralization, which is a much less expensive reagent than calcium hydroxide.54

Electrochemical aspects of the catalytic activity of the bacteria

The understanding of interfacial processes during bacterial leaching and biocorrosion generally is very matters. Good knowledge of electrochemical processes can enables to improve bioleaching93 and prevention, monitoring and control of biocorrosion.94 Magnin et al.95 are created an original process for the production of porous materials by improving the bacterial corrosion of iron in the iron-titanium hot-pressed plates by A. ferrooxidans.95

In the bioleaching of sulfide, a significant part of the bacteria is usually either temporarily or permanently attached to a solid substrate. These attached bacteria form a biofilm.96 Extra polymeric substances (EPS) allow bacteria to attach easily to the metal sulfide,97 which is useful for bacteria in unfavorable environments.98 The initial degree of adsorption of A. ferrooxidans is improved for the hydrophilic substrate, indicating that the affinity the mineral-to - bacteria is dictated by wetting properties of the substrate.99,100 The hydrophobic surface repels oxidation ions, reducing the degree of oxidation of the treated pyrite.101 Electrostatic interactions do not control the attachment of A. ferrooxidans to minerals. The number of accessible binding sites is dictated by the chemosensory system of A. ferrooxidans, which regulates the chemotaxis response of bacteria to initiate contact of bacteria-to- mineral, and the production of extracellular polymeric substances that mediate the attachment of bacteria.99 Attachment is facilitated by the extracellular polymeric substances, which render the non-polar surface more polar and allow for water penetration, promoting the attachment of A. ferrooxidans cells.102 The change of surface charge on cells is due to differences in the protein content which is synthesized by the bacteria when exposed to different conditions.103

The extracellular polymeric substances of Acidithiobacillus ferrooxidans consist mainly of neutral sugars and lipids.104 Bacterial EPS release H+ and concentrate Fe3+. Layers of EPSs with Fe3+ are precipitated on the surface of chalcopyrite, and become a barrier for oxygen transport to chalcopyrite; and create an area of high redox potential through the concentration of Fe3+ ions.98 The EPS concentrate ferric ions, probably complexed by glucuronic acid or other residues at the mineral surface.104 Ions of Cu2+ can be more stimulative than Fe3+ ions for bacteria production of EPS.105

A. ferrooxidans can grow by using the Fe3+/Fe2+ redox pair either as an electron donor or aceptor, depending on the relative value of the potential of other existing redox pairs in the system. It is interesting to note that in that case, bacteria can increase energy for growth when the electron acceptor and donor are in the periplasmic zone.46 Strains of A. ferrooxidans with a high amount of ferric ions in extra polymeric substances have higher oxidation activity than those with lower ferric ions.104,106 If the bacterial activity of oxidation of ferric ions is much higher than their consumption by ore, then each further bacterial activity can be harmful for the process of bioleaching.107 A specific degree of oxidation of ferrous ions is decreased by the increasie of ferric ions: with the increase of ferric ions in A. ferrooxidans, the iron-oxidizing enzyme system is competitively inhibited with ferric ions.108

The life of microorganisms occurs roughly at -500 mV to +800 mV.109 The bioleaching conditions typically exhibit a relatively high redox potential around 0.65-0.70 V SHE.6 Ferric ions and high Eh formed by action of bacterial metabolism inhibit leaching,107 because at the high solution potential ferric ion readily precipitates as a basic sulfate, like jarosite Eq. (18) in an environment containing monovalent alkali cations and sulfate ions,6

3Fe3++ 2SO42- +6H2O + M+ → MFe3(SO4)2(OH)6 + 6H+                                                                                                                                                (18)            

where: M = K+, Na+ or NH4+.

Precipitation of ferric ions (as jarosite) is responsible for passivation of chalcopyrite.110,111 Potassium jarosite is the initial product which cover chalcopyrite in the presence A. ferrooxidans. The next stage is formation of ammonium jarosite.112 In addition to the jarosite, the formation of a layer of secondary minerals on mineral surface becomes a diffusion barrier to fluxes of reactants and products. Covellite and elemental sulfur were also detected in passivation layer. Passivation can be reduced by controlling the precipitation of jarosite and by previous adaptation of bacteria.112 Addition of ferrous ions increases the leaching degree,113 and the external addition of high concentrations of ferric ions is unfavorable for the leaching.114 Accordingly, it is useful to know the significant conditions for precipitation of jarosite and biofilm formation leaching,114‒116 that is to say the limited bacterial activity and control of ferric ions are preferable for effective bioleaching.107

Influence of the type of mineral in leaching process on the catalytic activity of bacteria

The main contribution of A. ferrooxidans to the extraction of metals, is its capability to attack sulphide minerals and convert insoluble sulfides of metals like copper, lead, zinc, or nickel to the corresponding soluble sulphates of metals.117 It is considered that differences in crystal structure of minerals cause different sensibility to oxidation with A. ferrooxidans.118‒120 Purified recombinant aporusticianine and intact cells of A. ferrooxidans showed an identical pattern of adherence to same minerals. Addition of ferrous ions or organic chelating compounds prevents the binding of any aporusticianine or intact cells to pyrite. Binding of apoprotein to solid pyrite is realized partially by coordination of free ligands of copper with iron atoms on the exposed edge of the crystal lattice of pyrite.121 When A. ferrooxidans LR is exposed to bornite, its metabolic activity changes, where in the detoxication routes generally are activated. This response is not found for chalcopyrite. The exposition of the A. ferrooxidans cell to bornite causes a reaction against the oxidation stress, to protect the cell’s functions and to maintain homeostasis. Due to the higher solubility of bornite compared to chalcopyrite, the concentration of copper ions realized in the medium is increased, and this probably causes higher stress in bacteria.119 Mineral sulfides as semiconducting materials show galvanic interactions in the mixture in the electric contacts, which is often the case in ores. In the interaction, a mineral with a higher electrode potential becomes the cathode, while a corroded (oxidized) mineral with a lower electrode potential becomes the anode. An example of galvanic coupling is the acceleration of copper leaching from chalcopyrite in contact with pyrite. Pyrite, which is characterized by higher potential, acts as a cathode:49

O2 + 4H+ + 4e- → 2H2O                                                                                                                                                      (19)

While chalcopyrite with lower potential, acts as an anode:

CuFeS2 → Cu2+ + Fe2+ + 2S0+ 4e-                                                                                                                                      (20)

Pyrite may erode sphalerite (ZnS), which has a lower potential. It was found that the mineral with the lowest potential always possesses the highest extent of microbial colonization and dissolution. Thus, the physico-chemical effect (in this case, the galvanic effect) is highly beneficial for bacteria.49

Addition of pyrite to chalcopyrite concentrate significantly increases the efficiency of the extraction of copper.122 When adding activated carbon, A. ferrooxidans improves the galvanic interaction between chalcopyrite and carbon, which in turn speeds up the copper dissolution in the bioleaching of chalcopyrite concentrate with A. ferrooxidans.123

Influence of silver on the catalytic activity of the bacteria

Silver is an effective catalyst for bioleaching of copper from low-grade chalcopyrite ore.124128 The use of chelating agents (thiosulfate or thiosulfate plus cupric ions) does not influence the extraction yield of copper and iron.125 Dissolution of copper in the initial phase of bioleaching is increased by addition of a silver chloride solution with respect to the case with silver sulfate.129 However, a high concentration of chloride (5g/l) represses the catalyst effect of silver.125 Investigations have shown that use of concentrates or rock with argenit (Ag2S) as catalyst, improves bioleaching of copper from low-grade chalcopyrite ore.130 Argenit improves the yield of chalcopyrite bioleaching but inhibits biooxidation of pyrite.131 Metal ions, Ag+ and Cu2+, can improve the leaching degree by forming Ag2S, and in smaller quantity CuS, on the surface of realgar.132 Nutrient composition and pH significantly affect the bioleaching of copper. At pH~3.0, the catalyst effect of Ag vanishes. Bioleaching of low grade copper ore requires a minimum amount of nutrient salts to obtain maximum efficiency. Increasing content of ferric ions has a negative impact on the silver catalyzed bioleaching, but the effect is very positive for silver catalyzed chemical leaching.124

Bioleaching of complex sulfide concentrates at low temperature is catalyzed by different ions, such as silver, bismuth and tin.133‒135 The presence of different cations in the leach solution has a different catalytic activity on the dissolution of copper from concentrates: Ag (I)>>Hg(II)>Co(II)>Bi(III)>As(V)>Ru(III). The density of the pulp affects the efficiency of the bioleaching in the presence of silver. The optimal density is 5%.136 Presence of some cations (e.g. Hg (II), Ag (I), Pb (II) i Cd (II) in concentration of 10 mg / l, inhibits microbe oxidation of Fe (II). On the other hand, presence of 10 mg / l of As (III), Mn (II), Sn (II), Co (II), Cu (II) i Zn (II) and anions (as Cl-i NO3-), do not affect oxidative activity of bacteria on Fe (II).137 Silver probably inhibits Fe (II) oxidative capability of bacteria by several mechanisms in which Ag has to compete with Ferro Fe for active sites in the enzyme, and they are also bound to enzym-substrat complex.138 If the concentrate contains high quantities of silver, it simplifies the design and operation of reactors. These reactors may be used for concentrate processing at relatively low temperatures (30°C), with simple and known acidophilus.139 Ultraviolet radiation induces mutations in the silver-resistant isolate,and the mutant exhibits a much higher ferrous ion oxidation capacity and tolerance to silver ions.140

In the Indirect Bioleaching with Effective Separation (IBES) process, applied to chalcopyrite/sphalerite concentrates after separation of solid / liquid, ferrous iron in the leach solution, can be biologically oxidized with A. ferrooxidans to regenerate ferric iron (phase IBES biological processes); silver can be obtained from the residues and is recycled in this way.141,142

Influence addition of amino acids on the catalytic activity of the bacteria

Bacterial attack on the sulphide surface is based on the use of secondary chemical species (H, Fe2+, thiol compounds) that lead to the break of chemical bonds on the sulphide surface and thus causes decay.143 By adding a small amount of cysteine amino acid in acid solution in contact with pyrite, the activity of A. ferrooxidans is greatly improved, while at higher concentration of cysteine, a deleterious impact on bacterial activity is observed.144,145 In the presence of cysteine, pyrite can be oxidized in the absence of bacteria with a degree of leaching comparable to that obtained with bacteria under normal leaching conditions.143,145,146 Pyrite surface modified by adsorption of cysteine is a simplified model for the simulation of electron transfer in iron sulfur centers.147 Chemical interactions regulate the entire process of adsorption.148 Cysteine can act as a bridge or conductor, to facilitate the transfer of an electronic charge from the pyrite to the final product.149 The addition of methionine is harmful for bioleaching of pyrite with A. ferrooxidans at all concentrations of methionine.144 Ghosh et al.150 have found that the addition of aspartate, glutamine, serine or histidine increases the solubility of chalcopyrite in the presence of A. ferooxidans, but the efficiency of leaching of aspartate, glutamine and histidine reduces after a few days.150

Conclusions

Acidithiobacillus ferrooxidans is a bacteria which exists naturally in mines; it participate in geochemical processes, where it brings about to the oxidation of sulfide ores and stimulates the formation of acid mine waters. But, this same A. ferrooxidans, which is primarily responsible for the generation of AMD, can be used for recovery metals by leaching from mining - metallurgical resource and for remediation of acid mine waters. It’s possible to isolate strains from acid mine waters with the best characteristics and perform their adaptation to increased metal concentrations. The application A. ferrooxidans for leaching of metals is possible starting from ores, over concentrate, till mining-metallurgical waste. The type of mineral affects on the catalytic activity of the A. ferrooxidans. The limited bacterial activity and control of ferric ions are preferable for effective bioleaching. Addition of cations or amino acids can increase the degree of bioleaching of metal sulfides. So, the significant yield of copper and other metals from mining - metallurgical resource can be recovery by addition of catalysts (Ag for example or cysteine) in bacterial inoculum and by control of Eh conditions, values of pH, nutrients, oxigen and other biological and physico-chemical factors. Besides the recovery of metals, this is an ecological and cost-effective manner to reduce the release of metals into the environment.

Acknowledgements

None.

Conflict of interest

The author declare that there is no conflict of interests regarding the publication of this paper.

References

  1. Tasić V, Kovačević R, Maluckov B, et al. The Content of As and Heavy Metals in TSP and PM10 Near Copper Smelter in Bor, Serbia. Water Air Soil Poll. 2017. p. 228‒230.
  2. Tasić V, Maluckov B, Kovačević R, et al. Analysis of SO2 Concentrations in the Urban Areas near Copper Mining and Smelting Complex Bor, Serbia. Chem eng trans. 2014;42:103‒108.
  3. Akcil A, Koldas S. Acid Mine Drainage (AMD): causes, treatment and case studies. J Clean Prod. 2006;14(12‒13):1139‒1145.
  4. Marschalko M, Hofrichterova L, Lahuta H. Enginering-Geological Conditions of the Effect of a Landslide from Mining Activity. Slovak J Civ Eng. 2010;18(4):8‒16.
  5. Phillips J. Climate change and surface mining: A review of environment-human interactions & their spatial dynamics. Appl Geogr. 2016;74:95‒108.
  6. Watling HR. The bioleaching of sulphide minerals with emphasison copper sulphides - a review. Hydrometallurgy. 2006;84(1‒2):81‒108.
  7. Olson GJ, Brierley JA, Brierley CL. Bioleaching review B: processing in bioleaching: applications of microbial processes by the minerals industries. Appl Microbiol Biot. 2003;63(3):249‒257.
  8. Rawlings DE, Dew D, Du Plessis C. Biomineralization of metal containing ores and concentrates. Trend Biotechnol. 2003;21(1):38‒44.
  9. Clark ME, Batty JD, Buuren CB, et al. Biotechnology in minerals processing: Technological breakthroughs creating value. Hydrometallurgy. 2006;83(1‒4):3‒9.
  10. Morin DHR. BioMinE: An integrated project for developing biohydrometallurgy in Europe Executive summary of its activities and outputs after three years. Trans Nonferrous met Soc China. 2008;18(6):1328‒1335.
  11. Morin D, Pinches T, Huisman J, et al. Progress after three years of BioMinE-Research and Technological Development project for a global assessment of biohydrometallurgical processes applied to European non-ferrous metal resources . Hydrometallurgy. 2008;94(1‒4):58‒68.
  12. Brierley JA. A perspective on developments in biohydrometallurgy. Hydrometallurgy. 2008;94(1‒4):2‒7.
  13. Domić ME. A Review of the Development and Current Status of Copper Bioleaching Operations in Chile: 25 Years of Successful Commercial Implementation. Biomining. 2007. p. 81‒95.
  14. Chen P, Yan L, Leng F, et al. Bioleaching of realgar by Acidithiobacillus ferrooxidans using ferrous iron and elemental sulfur as the sole and mixed energy sources. Bioresource Technol. 2011;102(3):3260‒3267.
  15. Cruz R , Lazaro I , Gonzalez I , et al. Acid dissolution influences bacterial attachment and oxidation of arsenopyrite. Miner Eng. 2005;18(10):1024‒1031.
  16. Márquez MA, Ospina JD, Morales AL. New insights about the bacterial oxidation of arsenopyrite: A mineralogical scope. Miner Eng 2012;39:248‒254.
  17. Canales C, Acevedo F, Gentina JC. Laboratory-scale continuous bio-oxidation of a gold concentrate of high pyrite and enargite content. Process Biochem. 2012;37(10):1051‒1055.
  18. Hol A, Weijden RD, Weert G, et al. Bio-reduction of elemental sulfur to increase the gold recovery from enargite. Hydrometallurgy. 2012;115‒116:93‒97.
  19. Johnson DB. Biodiversity and interactions of acidophiles: Key to understanding and optimizing microbial processing of ores and concentrates. Trans Nonferrous Met Soc China. 2008;18(6):1367‒1373.
  20. Malki M,González-Toril E, SanzJ L, et al. Importance of the iron cycle in biohydrometallurgy. Hydrometallurgy. 2006;83(1‒4):223‒228.
  21. Natarjan KA. Microbial aspects of acid mine drainage and its bioremediation. Trans Nonferrous met Soc China. 2008;18(6):1352‒1360.
  22. Baker JB, Banfield FJ. Microbial communities in acid mine drainage. FEMS Microbiol Ecol. 2003;44(2):139‒152.
  23. Mu-qing Q, Shui-ying X, Wei-min Z, et al. A comparison of bioleaching of chalcopyrite using pure culture or a mixed culture. Miner Eng. 2005;18(9):987‒990.
  24. Valdés J, Pedroso I, Quatrini R, et al. Acidithiobacillus ferrooxidansmetabolism: from genome sequence to industrial applications. BMC Genomics. 2008;9:597.
  25. Baker-Austin C, Dopson M. Life in acid: pH homeostasis in acidophiles. Trends Microbiol. 2007;15(4):165‒171.
  26. Sharma A, Kawarabayasi Y, Satyanarayana T. Acidophilic bacteria andarchaea: acid stable biocatalysts and their potential applications. Extremophiles. 2012;16(1):1‒19.
  27. Hallberg KB. New perspectives in acid mine drainage microbiology. Extremophiles. 2010;104(3‒4):448‒453.
  28. Umrania VV. Bioremediation of toxic heavy metals using acidothermophilic autotrophes. Bioresource Technol. 2006;97(10):1237‒1242.
  29. Quatrini R, Appia-Ayme C, Denis Y, et al. Insights into the iron and sulfur energetic metabolism of Acidithiobacillus ferrooxidans by microarray transcriptome profiling. Hydrometallurgy. 2006;83(1‒4):263‒272.
  30. Kelly DP, Wood AP. Reclassification of some species of Thiobacillusto the newly designated genera Acidithiobacillusgen. nov., Halothiobacillus gen. nov. and Thermithiobacillusgen. nov. Int J Syst Evol Micr. 2000;50:511‒516.
  31. An-na WU, Yan-fei Z, Chun-li Z, et al. Purification and enzymatic characteristics of cysteine desulfurase, IscS, in Acidithiobacillus ferrooxidansATCC 23270. Trans Nonferrous Met Soc. 2008;18(6):1450‒1457.
  32. Johnson DB. Reductive dissolution of minerals and selective recovery of metals using acidophilic iron- and sulfate-reducing acidophiles. Hydrometallurgy. 2012;127‒128:172‒177.
  33. Rubino JT, Franz KJ. Coordination chemistry of copper proteins: How nature handles a toxic cargo for essential function. J Inorg Biochem. 2012;107(1):129‒143.
  34. Belle C, Rammal W, Pierre JL. Sulfur ligation in copper enzymes and models. J Inorg Bioch. 2005;99(10):1929‒1936.
  35. Ida C, Sasaki K, Ando A, et al. Kinetic Rate Constant for Electron Transfer between Ferrous Ions and Novel Rusticianin Isoform in Acidithiobacillus ferrooxidans. J Biosci Bioeng. 2003;95(5):534‒537.
  36. Kanao T, Kamimura K, Sugio T. Identification of a gene encoding a tetrathionate hydrolase in Acidithiobacillus ferrooxidans. J Biotechnol. 2007;132(1):16‒22.
  37. Quatrini R, Appia-Ayme C, Denis Y, et al. Extending the models for iron and sulfur oxidation in the extreme Acidophile Acidithiobacillus ferrooxidans. BMC Genomics. 2009;10:394.
  38. Warren JJ, Lancaster KM, Richards JH, et al. Inner- and outer-sphere metal coordination in blue copper proteins. J Inorg Biochem. 2012;115:119‒126.
  39. Nunzi F, Woudstra M, Campese D, at al. Amino-acid sequence of rusticyanin from Thiobacillus ferrooxidans and its comparison with other blue copper proteins. Biochim Biophys Acta. 1993;1162(1‒2):28‒34.
  40. Liu J, Chakraborty S, Hosseinzadeh P, at al. Metalloproteins containing cytochrome, iron–sulfur, or copper redox centers. Chem Rev. 2014;114(8):4366‒4469.
  41. Nomenclature Committee of IUB. Nomenclature of iron sulfur proteins, Recommendations 1989. JBC. 1992;267(1):666‒677.
  42. Zeng J, Geng M, Liu Y, et al. The sulfhydryl group of Cys138 of rusticyanin from Acidithiobacillusferrooxidans is crucial for copper binding. Bioch Bioph Acta. 2007;1774(4):519‒525.
  43. Nouailler M, Bruscella P, Lojou E, et al. Structural analysis of the HiPIP from the acidophilic bacteria: Acidithiobacillus ferrooxidans. Extremophiles. 2006;10(3):191‒198.
  44. Rodrigues VD, Martins PF, Gaziola SA, et al.Antioxidant enzyme activity in Acidithiobacillusferrooxidans LR maintained in contact with chalcopyrite. Process Biochem. 2010;45(6):914‒918.
  45. Jones GC, Becker M, Hille RP, et al. The effect of sulfide concentrate mineralogy and texture on Reactive Oxygen Species (ROS) generation. Appl Geochem. 2013;29:199‒213.
  46. Hansford GS, Vargas T. Chemical and electrochemical basis of bioleaching processes. Hydrometallurgy. 2001;59(2‒3):135‒145.
  47. Sand W, Gehrke T, Jozsa P, et al. (Bio)chemistry of bacterial leaching-direct vs. indirect bioleaching. Hydrometallurgy. 2001;59(2‒3):159‒175.
  48. Schippers A, Sand W. Bacterial leaching of metal sulfides proceeds by two indirect mechanisms via thiosulfate or via polysulfides and sulphur. Appl Applied Environ Microb. 1999;65(1):319‒321.
  49. Suzuki I. Microbial leaching of metals from sulfide minerals. Biotechnol Adv. 2001;19(2):119‒132.
  50. Sampson MI, Phillips CV, Blake RC. Influence of the attachment of acidophilic bacteria during the oxidation of mineral sulfides. Miner Eng. 2000;13(4):373‒389.
  51. Fowler TA, Crundwell FK. Leaching of zinc sulfide by Thiobacillus ferrooxidans: Experiments with a controlled redox potential indicate no direct bacterial mechanism. Applied Environ Microb. 1998;64(10):3570‒3575.
  52. Sampson MI, Phillips CV, Ball AS. Investigation of the attachement of Thiobacillusferrooxidans to mineral sulfides using scanning electron microscopy analysis. Miner Eng. 2000;13(6):643‒656.
  53. Johnson DB. Acidophilic Microbial Communities: Candidates for Bioremediation of Acidic Mine Effluents. Int Biodeter Biodegr. 1995;35(1‒3):41‒58.
  54. Sandstroma A, Mattsson E. Bacterial ferrous iron oxidation of acid mine drainage as pre-treatment for subsequent metal recovery. Int J Miner Process. 2001;62(1‒4):309‒320.
  55. Maluckov BS. Biological oxidation of polymetallic ores as a potential possibility for the treatment of ores from the Čoka Marin. Tehnika. 2014;69(2):221‒224.
  56. Maluckov BS. Bioassisted Phytomining of Gold. JOM. 2015;67(5):1075‒1078.
  57. Orell A, Navarro CA, Arancibia R, et al. Life in blue: Copper resistance mechanisms of bacteria and Archaea used in industrial biomining of minerals. Biotechnol Adv. 2010;28(6):839‒848.
  58. Mathiyazhagan N, Natarajan D. Bioremediation on Effluents from Magnesite and Bauxite Mines using Thiobacillus Spp and Pseudomonas Spp. Bioremed Biodegrad. 2011;2(1):2‒6.
  59. Beškoski PV, Matić FV, Milić J, et al. Oxidation of dibenzothiophene as a model substrate for theremoval of organic sulphur from fossil fuels by iron(III) ions generated from pyrite by Acidithiobacillusferrooxidans. J Serb Chem Soc. 2007;72(6):533‒537.
  60. Jin-yan L, Xiu-xiang T, Pei C. Study of formation of jarosite mediated by Thiobacillusferrooxidans in 9K medium. Proc Earth Planetary Sci. 2009;1(1):706‒712.
  61. Nemati M, Harrison STL, Hansford GS, et al. Biological oxidation of ferrous sulphate by Thiobacillusferrooxidans: a review on the kinetic aspects. Biochem Eng. J 1998;1(3):171‒190.
  62. Pradhan N, Nathsarma KC, Rao KS, et al. Heap bioleaching of chalcopyrite: a review. Miner Eng. 2008;21(5):355‒365.
  63. Bo F, Hongbo Z, Rubing Z, et al. Bioleaching of chalcopyrite by pure and mixed cultures of Acidithiobacillus spp. and Leptospirillum ferriphilum. Int Biodeter Biodegr. 2008;62(2):109‒115.
  64. Akcil A, Ciftci H, Deveci H. Role and contribution of pure and mixed cultures of mesophilesin bioleaching of a pyritic chalcopyrite concentrate.Miner Eng. 2007;20(3):310‒318.
  65. Mu-qing Q, Shui-ying X, Wei-min Z. Efficacy of chalcopyrite bioleaching using a pure and a mixed bacterium. J Univ Sci Technol B. 2006;13(1):7‒10.
  66. Yin S, Wu A, Wang Sh, et al. Effects of bioleaching on the mechanical and chemical properties of waste rocks. Int J Min Met Mater. 2012;19(1):2‒8.
  67. Wu A, Yin Sh, Wang H, et al. Technological assessment of a mining-waste dump at the Dexing copper mine, China, for possible conversion to an in situ bioleaching operation. Bioresource Technol. 2009;100(6):1931‒1936.
  68.  Nguyen VK,Lee MH, Park HJ, et al. Bioleaching of arsenic and heavy metals from mine tailings by pure and mixed cultures of Acidithiobacillus spp. J IndEng Chem. 2015;21:451‒458.
  69. Nguyen VK, Lee JU. Effect of sulfur concentration on microbial removal of arsenic and heavy metals from mine tailings using mixed culture of Acidithiobacillus spp. J Geochem Explor. 2015;148:241‒248.
  70. Rao KS, Mishra A, Pradhan D, et al. Percolation bacterial leaching of low-grade chalcopyrite using acidophilic microorganisms. Korean J Chem Eng. 2008;25(3):524‒530.
  71. Panda S, Sarangi ChK, Pradhan N, et al. Bio-hydrometallurgical processing of low grade chalcopyrite for the recovery of copper metal. Korean J Chem Eng. 2012;29(6):781‒785.
  72. Panda S, Sanjay K, Sukla LB, et al. Insights into heap bioleaching of low grade chalcopyrite ores - A pilot scale study. Hydrometallurgy. 2012;125‒126:157‒165.
  73. Yang Y, Diao M, Liu K, et al. Column bioleaching of low-grade copper ore by Acidithiobacillus ferrooxidans in pure and mixed cultures with a heterotrophic acidophile Acidiphilium sp.. Hydrometallurgy. 2013;131‒132:93‒98.
  74. Mousavi SM, Jafari A, Yaghmaei S, et al. Bioleaching of low-grade sphalerite using a column reactor. Hydrometallurgy. 2006;82(1‒2):75‒82.
  75. Wu A, Yin S, Qin W, et al. The effect of preferential flow on extraction and surface morphology of copper sulphides during heap leaching. Hydrometallurgy. 2009;95(1‒2):76‒81.
  76. Hai-na C, Yue-hua H, Jian G, et al. Bioleaching of anilite by Acidithiobacillus ferrooxidans. Trans Nonferrous met Soc China. 2008;18:1410‒1414.
  77. Jekić JS, Beškoski VP, Gojgić-Cvijović G, et al. Bacterially generated Fe2(SO4)3 from pyrite, as a leaching agent for heavy metals from lignite ash. J Serb Chem Soc. 2007;72(6):615‒619.
  78. Xia L, Yin C, Dai S, et al. Bioleaching of chalcopyrite concentrate using Leptospirillum ferriphilum, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidansin a continuous bubble column reactor. J Ind Microbiol Biotechnol. 2010;37(3):289‒295.
  79. Mehta KD, Pandey BD, Premchand. Bio-assisted leaching of Copper, Nickel and Cobalt from copper converter slag. Mater Trans. 1999;40(3):214‒221.
  80. Kaksonen HA, Lavonen L, Kuusenaho M, et al. Bioleaching and recovery of metals from final slag waste of the copper smelting industry. Miner Eng. 2011;24(11):1113‒1121.
  81. Bakhtiari F, Atashi H, Zivdar M, et al. Continuous copper recovery from a smelter's dust in stirred tank reactors. Int J Miner Process. 2008;86(1‒4):50‒57.
  82. Sampson MI, Blake RC. The cell attachement and oxygen consumption of two strains of Thiobacillus Ferrooxidans. Miner Eng. 1999;12(6):671‒686.
  83. Sampson MI, Phillips CV. Influence of base metals on the oxidising ability of acidophilic bacteria during the oxidation of ferrous sulfate and mineral sulfide concentrates, using mesophiles and moderate thermophiles. Miner Eng. 2001;14(3):317‒340.
  84. Gericke M, Muller HH, Staden PJ, et al. Development of a tank bioleaching process for the treatment of complex Cu-polymetallic concentrates. Hydrometallurgy. 2008;94(1‒4):23‒28.
  85. Xia L, Liu X, Zeng J, et al. Mechanism of enhanced bioleaching efficiency of Acidithiobacillus ferrooxidans after adaptation with chalcopyrite. Hydrometallurgy. 2008;92(3‒4):95‒101.
  86. Das A, Modak MJ, Natarajan KA. Surface chemical studies of Thiobacillus ferrooxidanswith reference to copper tolerance, Anton Leeuw Int JG. 1998;73(3):215‒222.
  87. Lizama HM. Copper bioleaching behaviour in an aerated heap. Int J Miner Process. 2001;62(1‒4):257‒269.
  88. Jian-she L, Hai-bo C, Zhao-hui W, et al. Bacterial oxidation activity in heap leaching. J cent southuniv technol. 2004;11(4):375‒379.
  89. Acevedo F. The use of reactors in biomining processes. Electron J Biotechn. 2000;3(3):1‒11.
  90. Lee JC, Pandey BD. Bio-processing of solid wastes and secondary resources for metal extraction - A review. Waste Manage. 2012;32(1):3‒18.
  91. Carranza F, Romero R, Mazuelos A, et al. Biorecovery of copper from converter slags: Slags characterization and exploratoryferric leaching tests. Hydrometallurgy. 2009;97(1‒2):39‒45.
  92. Johnson DB, Hallberg KB. Acid mine drainage remediation options: a review. Sci of Total Environ. 2005;338(1‒2):3‒14.
  93. Gericke M, Govender Y, Pinches A. Tank bioleaching of low-grade chalcopyrite concentrates using redox control. Hydrometallurgy. 2010;104(3‒4):414‒419.
  94. Videla HA. Prevention and control of biocorrosion. Int Biodeter Biodegr. 2002;49(4):259‒270.
  95. Magnin JP, Garden J, Ozil P, et al. Preparation of porous materials by bacterially enhanced corrosion of Fe in iron-titanium hot-pressed plates.Mat Sci Eng. 1994;189(1‒4):165‒172.
  96. Crundwell F. The formation of biofilms of iron-oxidasing bacteria on pyrite.Miner Eng. 1996;9(10):1081‒1089.
  97. Bellenberg S, Leon-Morales CF, Sand W, et al. Visualization of capsular polysaccharide induction in Acidithiobacillusferrooxidans. Hydrometallurgy. 2012;129‒130:82‒89.
  98. Run-lan Y, Jian-xi T, Peng Y, et al. EPS-contact-leaching mechanism of chalcopyrite concentrates by A.ferrooxidans. Trans Nonferrous Met Soc China. 2008;18(6):1427‒1432.
  99. Tan SN, Chen M. Early stage adsorption behaviour of Acidithiobacillus ferrooxidans on minerals I: An experimental approach. Hydrometallurgy. 2012;119‒120:87‒94.
  100. Ming-lian Ch, Lin Z, Guo-hua G, et al. Effects of microorganisms on surface properties of chalcopyrite and bioleaching. Trans Nonferrous met Soc China. 2008;18(6):1421‒1426.
  101. Nyavor K, Egiebor NO, Fedorak PM. Suppression of microbial pyrite oxidation by fatty acid amine treatment. Sci Total Environ 1996;182(1‒3):75‒83.
  102. Milić JS, Beškoski VP, Randjelović DV, et al. Visualisation of the interaction between Acidithiobcillusferrooxidans and oil shale bz atomic force microscopy. J Min Metall Sect B-Metall. 2012;48(2):207‒217.
  103. Sharma PK, Das A, Hanumantha Rao K, et al.Surface characterization of Acidithiobacillus ferrooxidanscells grown under different conditions. Hydrometallurgy. 2003;71(1‒2):285‒292.
  104. Kinzler K, Gehrke T, Telegdi J, et al. Bioleaching-a result of interfacial processes caused by extracellular polymeric substances (EPS). Hydrometallurgy. 2003;71(1‒2):83‒88.
  105. Run-lan Y, Jing L, An C, et al. Interaction mechanism of Cu2+, Fe3+ ions and extracellular polymeric substances during bioleaching chalcopyrite by Acidithiobacillus ferrooxidansATCC2370. Trans Nonferrous Met Soc China. 2013;23(1):231‒236.
  106. Sand W, Gehrke T. Extracellular polymeric substances mediate bioleaching/biocorrosion via interfacial processes involving iron (III) ions and acidophilic bacteria. Res Microbiol. 2006;157(1):49‒56.
  107. Third KA, Cord-Ruwisch R, Watling HR. The role of iron-oxidizing bacteria in stimulation or inhibition of chalcopyrite bioleaching. Hydrometallurgy. 2000;57(3):225‒233.
  108. Kawabe Y, Inoue C, Suto K, et al. Inhibitory Effect of High Concentrations of Ferric Ions. J biosci bioeng. 2003;96(4):375‒379.
  109. Sand W. Microbial life in geothermal waters. Geothermics. 2003;32(4‒6):655‒667.
  110. Córdoba EM, Muñoz JA, Blázquez ML, et al. Leaching of chalcopyrite with ferric ion. Part IV: The role of redox potential in the presence of mesophilic and thermophilic bacteria. Hydrometallurgy. 2008;93(3‒4):106‒115.
  111. Run-lan Y, Jian-xi T, Gou-hua G, et al. Mechanism of bioleaching chalcopyrite by Acidithiobacillus ferrooxidansin agar-simulated extracellular polymeric substances media. J Cent South Univ Technol. 2010;17(1):56‒61.
  112. Sasaki K, Nakamuta Y, Hirajima T, et al. Raman characterization of secondary minerals formed during chalcopyrite leaching with Acidithiobacillus ferrooxidans. Hydrometallurgy. 2009;95(1‒2):153‒158.
  113. Mishra M, Singh S, Das T, et al. Bio-dissolution of copper from Khetri lagoon material by adapted strain of Acidithiobacillus ferrooxidans. Korean J Chem Eng. 2008;25(3):531‒534.
  114. Lin Z, Guan-zhou Q, Yue-hua H, et al. Bioleaching of pyrite by A. ferrooxidans and L. ferriphilum. Trans Nonferrous Met Soc China. 2008;18(6):1415‒1420.
  115. Pogliani C, Donati E. Immobilisation of Thiobacillus ferrooxidans: importance of jarosite precipitation. Process Biochem. 2000;35(9):997‒1004.
  116. Kodali B, Rao MB, Narasu ML, et al. Effect of biochemical reactions in enhancement of rate of leaching. Chem l Eng Sci. 2004;59:5069‒5073.
  117. Rawlings D, Kusano T. Molecular Genetics of Thiobacillus ferrooxidans. Microbiol rev. 1994;58(1):39‒55.
  118. Lei J, Huai Yang Z, XiaoTong P. Bio-oxidation of pyrite, chalcopyrite and pyrrhotite by Acidithiobacillus ferrooxidans. Chinese Sci Bull. 2007;52(19):2702‒2714.
  119. Felício AP, De Oliveira E, Odena MA, et al. Differential proteomic analysis of Acidithiobacillusferrooxidans cells maintained in contact with bornite or chalcopyrite: Proteins involved with the early bacterial response. Process Biochem. 2011;46(3):770‒776.
  120. Renman R, Zhou E, Xingyu L, et al. Comparison on the leaching kinetics of chalcocite and pyrite with or without bacteria. Rare metals. 2010;29(6):552‒556.
  121. Blake RC, Sasaki K, Ohmura N. Does aporusticyanin mediate the adhesion of Thiobacillus ferrooxidansto pyrite?. Hydrometallurgy. 2001;59(2‒3):357‒372.
  122. Ahmadi A, Ranjbar M, Schaffie M. Catalytic effect of pyrite on the leaching of chalcopyrite concentrates in chemical, biological and electrobiochemical systems. Miner Eng. 2012;34:11‒18.
  123. Nakazawa H, Fujisawa H, Sato H. Effect of activated carbon on the bioleaching of chalcopyrite concentrate. Int J Miner Process. 1998;55(2):87‒94.
  124. Muñoz JA, Dreisinger DB, Cooper WC, et al. Silver-catalyzed bioleaching of low-grade copper ores. Part I: Shake flasks tests. Hydrometallurgy. 2007;88(1‒4):3‒18.
  125. Muñoz JA, Dreisinger DB, Cooper WC, et al. Silver-catalyzed bioleaching of low-grade copper ores. Part II: Stirred tank tests. Hydrometallurgy. 2007;88(1‒4):19‒34.
  126. Muñoz JA, Dreisinger DB, Cooper WC, et al. Silver-catalyzed bioleaching of low-grade copper ores. Part III: Column reactors. Hydrometallurgy. 2007;88(1‒4):35‒51.
  127. Deng T, GuoY, Liao M, et al. Silver-catalyzed bioleaching for raw low-gradecopper sulphide ores. Front Chem Eng China. 2009;3(3):250‒254.
  128. Feng S, Yang H, Xin Y, et al. A novel and highly efficient system for chalcopyrite bioleaching by mixed strains of Acidithiobacillus. Bioresource Technol. 2013;129:456‒462.
  129. Sato H, Nakazawa H, Kudo Y. Effect of silver chloride on the bioleaching of chalcopyrite concentrate. Int J Miner Process. 2000;59(1):17‒24.
  130. Yuehua H, Guanzhou Q, Jun W, et al. The effect of silver-bearing catalysts on bioleaching of chalcopyrite. Hydrometallurgy. 2002;64(2):81‒88.
  131. Yuehua H, Jun W, Guan-zhou Q, et al. nfluences of silver sulfide on the bioleaching of chalcopyrite, pyrite and chalcopyrite-containing ore. J Cent South Univ Technol. 2002;9(1):11‒15.
  132. Guo P, Zhang G, Cao J, et al. Catalytic effect of Ag+ and Cu2+ on leaching realgar (As2S2). Hydrometallurgy. 2011;106(1‒2):99‒103.
  133. Ballester A, Gonzalez F, Blazuquez ML, et al. The use of catalytic ions in bioleaching. Hydrometallrgy. 1992;29(1‒3):145‒160.
  134. Gomez C, Bliizquez ML, Ballester A. Influence of various factors in the bioleaching of a bulk concentrate with mesophilic microorganisms in the presence of Ag (I). Hydrometallurgy. 1997;45:271‒287.
  135. Gomez E, Ballester A, Blazquez ML, et al. Silver-catalysed bioleaching of a chalcopyrite concentrate with mixed cultures of moderately thermophilic microorganisms. Hydrometallurgy. 1999;51(1):37‒46.
  136. Escudero ME, Gonzalez F, Blazquez ML, et al. The catalytic effect of some cations on the biological leaching of a Spanish complex sulphide. Hydrometallurgy. 1993;34(2):151‒169.
  137. De GC, Oliver DJ, Pesic BM. Effect of heavy metals on the ferrous iron oxidizing ability of Thiobacillus ferrooxidans. Hydrometallurgy. 1997;44(1‒2):53‒63.
  138. De GC, Oliver DJ, Pesic BM. Effect of silver on the ferrous iron oxidizing ability of Thiobacillus ferrooxidans. Hydrometallurgy. 1996;41(2‒3):211‒229.
  139. Johnson DB, Okibe N, Wakeman K, et al. Effect of temperature on the bioleaching of chalcopyrite concentrates containing different concentrations of silver. Hydrometallurgy. 2008;94(1‒4):42‒47.
  140. Xue-ling W, Guan-zhou Q, Jian G, et al. Mutagenic breeding of silver-resistant Acidithiobacillus ferrooxidans and exploration of resistant mechanism. Trans Nonferrous Met SOC C hina. 2007;17(2):412‒417.
  141. Romero R, Mazuelos A, Palencia I, et al. Copper recovery from chalcopyrite concentrates by the BRISA proces. Hydrometallurgy. 2003;70(1‒3):205‒215.
  142. Carranza F, Iglesias N, Mazuelos A, et al. Treatment of copper concentrates containing chalcopyrite and non-ferrous sulphides by the BRISA process. Hydrometallurgy. 2004;71(3‒4):413‒420.
  143. Tributsch H, Rojas-Chapana JA. Metal sulfide semiconductor electrochemical mechanisms induced by bacterial activity. Electrochim Acta. 2000;45(28):4705‒4716.
  144. Hu Y, He Z, Hu W, et al. Effect of two konds of amino-acids on bioleaching metal sulfide. Trans Nonferrous Met Sosc China. 2004;14(4):794‒797.
  145. Rojas-Chapana JA, Tributsch H. Bio-leaching of pyrite accelerated by cysteine. Process Biochem. 2000;35(8):815‒824.
  146. Rojas-Chapana JA, Tributsch H. Biochemistry of sulfur extraction in bio-corrosion of pyrite by Thiobacillus ferrooxidans. Hydrometallurgy. 2001;59(2‒3):291‒300.
  147. El-HalimAM, Alonso-Vante N, Tributsch H. Iron/sulphur centre mediated photoinduced charge transfer at (100) oriented pyrite surfaces. J Electroanal Chem. 1995;399(1‒2):29‒39.
  148. Jian-she L, Zhao-hui W, Bang-mei L, et al. Interaction between pyrite and cysteine. Trans Nonferrous Met Soc China. 2006;16(4):943‒946.
  149. Wang Z, Xie X, Xiao S, et al. Comparative study of interaction between pyrite and cysteine by thermogravimetric and electrochemical techniques. Hydrometallurgy. 2010;101(1‒2):88‒92.
  150. Ghosh B, Mukhopadhya BP, Bairagya HR. Effect of amino acids on bioleaching of chalcopyrite ore by Thiobacillusferrooxidans. Afr J Biotechnol. 2012;11(8):1991‒1996.
Creative Commons Attribution License

©2017 Maluckov. This is an open access article distributed under the terms of the, which permits unrestricted use, distribution, and build upon your work non-commercially.