ZA200708339B - Use of minig waste and concentrates containing pyrite, in the culture of iron-oxidizing and sulfur-oxidizing micro-organisms as an energy source for bacteria growth - Google Patents
Use of minig waste and concentrates containing pyrite, in the culture of iron-oxidizing and sulfur-oxidizing micro-organisms as an energy source for bacteria growth Download PDFInfo
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- ZA200708339B ZA200708339B ZA200708339A ZA200708339A ZA200708339B ZA 200708339 B ZA200708339 B ZA 200708339B ZA 200708339 A ZA200708339 A ZA 200708339A ZA 200708339 A ZA200708339 A ZA 200708339A ZA 200708339 B ZA200708339 B ZA 200708339B
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- microorganisms
- oxidizing
- culture
- pyrite
- waste
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- 244000005700 microbiome Species 0.000 title claims description 71
- 229910052683 pyrite Inorganic materials 0.000 title claims description 28
- 239000011028 pyrite Substances 0.000 title claims description 28
- NIFIFKQPDTWWGU-UHFFFAOYSA-N pyrite Chemical compound [Fe+2].[S-][S-] NIFIFKQPDTWWGU-UHFFFAOYSA-N 0.000 title claims description 28
- 239000002699 waste material Substances 0.000 title claims description 19
- 239000012141 concentrate Substances 0.000 title claims description 12
- 241000894006 Bacteria Species 0.000 title description 5
- 238000000034 method Methods 0.000 claims description 26
- 239000002516 radical scavenger Substances 0.000 claims description 25
- 230000001580 bacterial effect Effects 0.000 claims description 9
- 238000005065 mining Methods 0.000 claims description 9
- 238000005188 flotation Methods 0.000 claims description 7
- 230000001590 oxidative effect Effects 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 6
- 239000004576 sand Substances 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 24
- 229910052802 copper Inorganic materials 0.000 description 19
- 239000010949 copper Substances 0.000 description 19
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 18
- 239000000243 solution Substances 0.000 description 17
- 239000001963 growth medium Substances 0.000 description 13
- 238000002386 leaching Methods 0.000 description 13
- 239000002609 medium Substances 0.000 description 13
- 229910052717 sulfur Inorganic materials 0.000 description 11
- 239000002028 Biomass Substances 0.000 description 10
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 10
- 239000011593 sulfur Substances 0.000 description 10
- 229910052742 iron Inorganic materials 0.000 description 9
- 239000002253 acid Substances 0.000 description 8
- 241000605272 Acidithiobacillus thiooxidans Species 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 7
- 241000605222 Acidithiobacillus ferrooxidans Species 0.000 description 6
- 238000010348 incorporation Methods 0.000 description 6
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical class [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 6
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 239000011790 ferrous sulphate Substances 0.000 description 4
- 235000003891 ferrous sulphate Nutrition 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 3
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 3
- 235000011130 ammonium sulphate Nutrition 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 239000002054 inoculum Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000003753 real-time PCR Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000007790 solid phase Substances 0.000 description 3
- 150000003464 sulfur compounds Chemical class 0.000 description 3
- DHCDFWKWKRSZHF-UHFFFAOYSA-N sulfurothioic S-acid Chemical compound OS(O)(=O)=S DHCDFWKWKRSZHF-UHFFFAOYSA-N 0.000 description 3
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000011081 inoculation Methods 0.000 description 2
- 238000011031 large-scale manufacturing process Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000000813 microbial effect Effects 0.000 description 2
- 235000015097 nutrients Nutrition 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000000638 solvent extraction Methods 0.000 description 2
- 241000894007 species Species 0.000 description 2
- LWIHDJKSTIGBAC-UHFFFAOYSA-K tripotassium phosphate Chemical compound [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 2
- 235000005956 Cosmos caudatus Nutrition 0.000 description 1
- 244000293323 Cosmos caudatus Species 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000012620 biological material Substances 0.000 description 1
- 229910052948 bornite Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 229910052951 chalcopyrite Inorganic materials 0.000 description 1
- DVRDHUBQLOKMHZ-UHFFFAOYSA-N chalcopyrite Chemical compound [S-2].[S-2].[Fe+2].[Cu+2] DVRDHUBQLOKMHZ-UHFFFAOYSA-N 0.000 description 1
- 229910052955 covellite Inorganic materials 0.000 description 1
- 238000012258 culturing Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000003306 harvesting Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000004060 metabolic process Effects 0.000 description 1
- 150000001455 metallic ions Chemical class 0.000 description 1
- 229910052961 molybdenite Inorganic materials 0.000 description 1
- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 description 1
- 230000017066 negative regulation of growth Effects 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 229910000160 potassium phosphate Inorganic materials 0.000 description 1
- 235000011009 potassium phosphates Nutrition 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052569 sulfide mineral Inorganic materials 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
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- Micro-Organisms Or Cultivation Processes Thereof (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Preparation Of Compounds By Using Micro-Organisms (AREA)
Description
o IN oO
PATENT SPECIFICATIONS. ? Q Q 7 f \ 83 39
The invention publishes the use of pyrite-containing mining products and sub- products, such as for example, copper concentrates, and the waste from the process in which these concentrates are obtained, known as “scavenger tail”, as an energy source for the large-scale culture of an association of microorganisms that are useful in ore bioleaching, and which includes both isolated micro-organisms, and native microorganisms present in the worked ore. In particular, the invention publishes the use of mining waste, known as “scavenger tail”, from the flotation process, in the culture of an association of isolated microorganisms of the Acidithiobacillus ferrooxidans and
Acidithiobacillus thiooxidans type together, with or without other native microorganisms of the worked ores.
STATE OF THE ART
Typically, in microorganism culture, artificial or expressly prepared culture mediums are used, frequently starting from highly pure organic and/or inorganic chemical products. This normally has the purpose of controlling to a maximum the variables related to the requirements of the microorganisms, and avoiding all potential sources of contamination or inhibition of microbial growth.
For example, the laboratory-scale growth of At. ferrooxidans and At. thiooxidans has been described by Silverman, M.P. & Lundgren D.G. 1959. “Studies on the chemoautotrophic iron bacterium ferrobacillus ferroooxidans I. An Improved
Medium and a Harvesting Procedure for Securing High Cell Yields”. Journal of
Bacteriology. 77: 642-647, and Cook, T.M. 1964. “Growth of Thiobacillus thiooxidans in shaken culture”. Journal of Bacteriology. 88: 620-623.
TA
®
The previous approach is highly appropriate for the culture of microorganisms at a laboratory level, and even sometimes at a pilot-test level. However, due to economic considerations it could become impractical, above all if it deals with the large-scale production of biomass. This problem is normally solved by using reagents of a technical-industrial grade, which decreases the cost of the medium, but increases potential sources of contamination, besides adding impurities that could inhibit microorganism growth.
Thus, for culturing microorganisms in industrial conditions, formulations based on ammonium sulfate and potassium phosphate of a technical level (Hackl et al.
United States patent number US 5.089.412) have been described. Likewise, in the applications for Chilean patents CL 2731-2004, and CL 2101-2005, the culture mediums known as 9K modified (3.0 g/L of (NH4)2SO4, 0.5 g/L of
KoHPOy4, 0.5 g/L of MgS04*7H,0, 0.1 g/L of KCI and 0.1 g/L of Ca(NO3),, 30 g/L of FeS04-7H,0) and 9KS (3.0 g/L of (NH4)2SO4, 0.5 g/L of K;HPO,, 0.5 g/L of
MgS0O,4*7H,0, 0.1 g/L of KCI, 0.1 g/L of Ca(NOs),, 1% of elementary sulfur or another reduced sulfur compound, are respectively used.
It is a known fact that in the cultivation of microorganisms in mediums such as those described, the final biomass concentration is limited by the concentration of the substrate used as an energy source and by the inhibition of growth exercised both by the substrate and the products of its metabolism generated during microbial growth [LaCombe, J., Lueking, D. 1990. “Growth and maintenance of Thiobacillus ferrooxidans cells”. Applied and Environmental
Microbiology. 56: 2801-2806; Nagpal, S. 1997. “A structured model for
Thiobacillus ferrooxidans growth on ferrous Iron”. Biotechnology and
Bioengineering. 53. 310-319].
On the other hand, the type of microorganism obtained depends on the type of : energy source used, iron in the form of Fe?" compounds for iron-oxidizing micro-
® organisms, and sulfur compounds — in a -2, 0 y +4 state of oxidation — for sulfur- oxidizing microorganisms. The above constitutes a limiting factor for the design of a mixed biomass (iron and sulfur oxidizing) production process, because it imposes different production conditions — substrates and pH — for each strain.
In the event of wanting to cultivate two or more microorganism species, it seems attractive to use the same culture medium, or even culture the microorganisms together. In this way, the number of stages in the process is decreased, the complexity of the operation is simplified, and in some cases, it is possible to take advantage of the inherent characteristics of the underlying biochemistry.
Iron sulfates, such as pyrite (FeS;) or the materials that contain it, are sources of reduced iron and sulfur and therefore constitute an interesting alternative for the production of mixed leaching biomass.
Schippers, A., Jozsa, P.G., Sand, W. 1996. “Sulfur chemistry in bacterial leaching of pyrite”. Applied and Environmental Microbiology. 62: 3424-3431, propose the formation of thiosulfate (S203%) during the pyrite degradation cycle.
This compound can follow a series of abiotic reactions, or be used as an energy source by sulfur-oxidizing bacteria, which gives occasion to propose the joint culture of iron-oxidizing and thio-oxidizing microorganisms on materials containing pyrite.
Finally, regarding the use of pyrite, or materials that contain it, the existing studies propose different approaches, for example, patents WQ00136693,
WOO0071763 and W0O2004027100 propose its use as a source of sulfuric acid.
In document WO0136693 the use of pyrite is associated to leaching systems in which sulfuric acid is not added; in document WO0071763 its use is associated with the replenishment of acid when the ore shows a high demand for it; and in document WO2004027100 they are used to replace part of the necessary acid.
In other documents such as patent US 6.110.253 and application
, oo
US2005103162, pyrite is used as a mechanism to increase the temperature in : the heap, as when it is bio-oxidized, it generates heat, which according to the previously-mentioned text, makes it possible to practice bioleaching with thermophile microorganisms.
Other uses of pyrite are found for example, in the works of de Bacelar-Nicolau,
P. & Jonson, B. 1999. “Leaching of pyrite by acidophilic heterotrophic iron- oxidizing bacteria in pure and mixed cultures’. Applied and Environmental
Microbiology. 65: 585-590, and Chong, N., Karamanev, D.G., Margaritas, A. 2002. “Effect of particle-particle shearing on the bioleaching of sulfide minerals”. :
Biotechnology and Bioengineering. 80: 349-357, in which the growth of micro- organisms such as At. ferrooxidans on pyrite as a source of energy is shown at laboratory scale. Nevertheless, the rate of growth in this material appears to be affected by friction between the solid particles.
Therefore, as far as we know, there is still a lack of lower-priced culture mediums to enable the feasible large-scale production of microorganisms useful in bioleaching; and we don’t know of processes in which pyrite is effectively used as an energy source for biomass growth either.
For a better understanding of the processes, the following should be understood as: a) ATCC: “American Type Culture Collection”, b) Ore bioleaching in troughs: a process that is carried out in a tank with a false bottom where the ore is loaded and flooded with the leaching solution which is made to circulate through the ore particles in the presence of acidophilic microorganisms, and the copper is extracted dissolved in an acid solution.
® ..2007/7883 39 c) Bioleaching of ores in dumps: ores below the cut-off grade, which are extracted from an open-pit mine, are stored as run of mine or after primary crushing, in gorges that have the appropriate characteristics to control the infiltration of solutions or on surfaces where a waterproof sheet has been previously installed. The surface is irrigated with leaching solution, in the presence of acidophilic microorganisms, and the copper dissolved in an acid solution is extracted from the base. d) Ore heap bioleaching: In this process, the ore that has been crushed down to a specific grading is collected on a water-proof surface with a slight slope, and the leaching solution is irrigated over the surface in the presence of acidophilic microorganisms, and the copper dissolved in an acid solution is extracted from the base. e) Bioleaching of on-site ore: deposits of ore in their natural state or that have been broken up during previous mining operations are directly leached on-site, irrigating the surface with leaching solution, in the presence of acidophilic microorganisms, and the copperr dissolved in an acid solution is extracted from the base. f) Ore bioleaching in stirred tanks or reactors: the bioleaching process takes place in a mechanically stirred tank where the finely divided ore is mixed with the leaching solution, forming a slurry with a solid content of up to 20%, with the presence of acidophilic microorganisms, extracting the copper dissolved in an acid solution. g) Bioleaching of tailing ponds: tailings that originate in the flotation process and contain lower quantities of the metal present in the ore are stored in dams, from where they are then extracted for leaching, either in heaps or by stirring, in the presence of acidophilic microorganisms, and the copper is extracted dissolved in an acid solution. h) Biomass: mass of live organisms produced in a specific area or volume. i) Scavenger Tail: Sand resulting from a flotation cell circuit of the sand from the main ore cleaning circuit. j) DSM: “Deutsche Sammlung von Mikroorganismen und Zellkulturen
GmbH” German Type Microorganism Culture.
® k) Inoculum: pure or mixed bacterial culture which will act as active biological material during the bioleaching process.
I) Passivation: decrease in ore leaching speed as a consequence of the accumulation of layers of sulfur and poli-sulfurs on its surface. m) PLS: aqueous solution generated during the bioleaching process that contains the metallic ions that have been leached from the ore. This solution constitutes the feed for the PLS solvent extraction plant. n) Raffinate: copper-depleted aqueous solution, resulting from the process of copper solvent extraction. 0) Mixed energy source: substrate that allows simultaneous growth of iron and sulfur oxidizing microorganisms. p) Mixed biomass: mass of microorganisms capable of oxidizing reduced iron and sulfur compounds.
In order to produce isolated microorganisms on a large scale, that will be useful for the bioleaching of sulfide metal ores, a process has been developed that is based on the use of bioreactors, in which it is possible to lower the costs of culture mediums in order to grow these microorganisms. This cost reduction is based on the use of concentrates, or of pyrite-containing waste ore from the ore flotation process, such as for example, the waste known as scavenger tail, to partly replace the standard culture medium, as an energy source for two different types of microorganisms that grow together: Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans.
This process also furnishes advantages regarding the quantity of microorganisms, their adaptation to the solid phase, and furnishes advantages related to copper recovery and to the obtaining of iron in an oxidized state +3 as well.
Of the waste products that can be used, the scavenger tail from the flotation process has a typical composition which is shown in Table 1. This composition contains a not inconsiderable amount of pyrite of approximately 20%, which
- 83 39 ® «2007 /0 may be used advantageously for the joint cultivation of the above-mentioned microorganisms.
Table 1: Mineralogical composition of scavenger tail, taking into account 100% of opaque ore
Ore Weight % Vol. % S % Cu % Fe % Zn
Chalcopyrite 2.08 1.51 0.73 0.72 0.63
Chalcosite 0.53 0.29 0.11 0.43
Covellite 062 0M 0.21 0.41
Bornite 1.37 0.82 0.35 0.86 0.15
Pyrite 19.28 11.76 10.30 8.98
Molybdenite ~~ 0 94 0.61 0.38 057
Sphalernte 0.05 0.04 0.02 0.04
Magnetite 021 0.12 0.15
Limonite 0.20 0.16 013
Rutile 0.17 0.12
Gangue 74 54 84.16
As it has been known for a long time, pyrite can be used as an energy source by Acidithiobacillus ferrooxidans type microorganisms, the activity of which may be represented by the following formula:
FeS, + 6Fe” + 3H,0 — 7Fe* + S,05% + 6 H* 7Fe® + 7/4 Oy + TH* — 7Fe® + 7/2 H,0 + At. ferrooxidans
FeS, + 7/4 0 + H" — Fe* + S,05% + 1/2 H,0 + At. ferrooxidans reaction (i)
As observed in reaction (1), one of the products is thiosulfate, which contemplates sulfur in an intermediate state of oxidation, and which is useful as an energy source for microorganisms of the Acidithiobacillus thiooxidans type, in accordance with the following reaction:
S,03% + HO + 20, —» 2S04% + 2H" + At. thiooxidans reaction (ii)
Therefore, simultaneous cultivation of Acidithiobacillus ferrooxidans type and
Acidithiobacillus thiooxidans type microorganisms, together with other micro-
organisms, takes advantage of the presence and formation of species that can be used as an energy source, iron (ll) and thiosulfate, respectively. :
Taking into consideration that part of the conventional culture medium has not been replaced by a waste product such as scavenger tail that costs nothing, it appears obvious that this culture is less expensive than the culture that uses conventional medium. Furthermore, as two microorganisms are cultivated simultaneously, there are further decreases in costs associated with facilities, reactors, control systems, etc. that would otherwise have to be doubled.
In addition, joint cultivation using scavenger tail waste makes it possible to obtain a higher concentration of microorganisms than what is normally obtained when the same microorganisms are cultivated separately. This has economic significance, which may be evaluated by the reduction of the equipment needed to achieve a given target concentration when new facilities are being planned, or by a higher production capacity in currently operating facilities.
Based on the studies carried out presented below in the examples, it is possible to affirm that the association of microorganisms that includes isolated microorganisms mixed with native microorganisms from the ore, grows normally in the medium modified with scavenger tail waste. The above constitutes progress in regard to the state of the art, as it lowers culture costs by reducing the costs of the culture medium.
Furthermore, in accordance with the reactions set forth previously, a higher concentration of the Acidithiobacillus thiooxidans species will naturally be produced, or likewise, a higher relative growth of the Acidithiobacillus thiooxidans species will naturally also be produced. This may or may not be an advantage, depending on considerations regarding subsequent processes in which the generated biomass is used. Nevertheless, if it is desired or necessary, microorganism growth may be balanced by incorporating Fe? as ferrous sulfate (FeSO4-7H20).
® ;
As indicated, in practice the invention is verified by replacing part of the standard microorganism culture medium of the microorganisms by waste that contains pyrite, such as scavenger tail from the ore flotation process. The fraction of the culture medium that is replaced is the one that corresponds to iron and sulfur species, and it is possible to replace a sizeable part of it. For example in a cultivation medium modified in accordance with the invention, 1 to 100 g/L of scavenger tail may be used.
Furthermore, and because waste such as scavenger tail contains solids, the microorganisms are able to adapt to solid phase sulfur oxidizing. This adaptation is useful, and also represents a technical step forward, because, as the microorganisms are adapted to the solid phase, they will rapidly populate the materials stationed in heaps, dumps, tailing dams or other on-site operations in which they are used, decreasing the time associated to their leaching.
In addition, copper in pyrite-containing waste, particularly in scavenger tail, where copper constitutes almost 2.5%, shall be released into the solution, remaining free to be recovered by means of the usual copper recovery processes, and therefore increasing the general productivity of the process.
Once again, this means progress, seeing as in state-of-the-art processes the copper found in this waste is lost.
Finally, and in accordance with the reactions presented previously, iron enrichment to a state of oxidation +3 is produced in the cultivation medium. As technically known, the presence of Fe** promotes the leaching of secondary ores, and therefore this also represents an advantage over other processes.
Figure 1: This figure presents the batch mode growth curve of an association of microorganisms in a culture medium modified by the incorporation of scavenger i tail, as described in Example 1.
Figure 2: This figure presents the contents of At. ferrooxidans Wenelen DSM 16786 (black bars) and At. thiooxidans Licanantay DSM 17318 (white bars) in a biomass propagation bioreactor operated in continuous mode, using culture medium modified by the incorporation of scavenger tail, as described in
Example 2.
EXAMPLE 1
In order to determine the growth kinetics and biomass yield of the association of
Wenelen DSM 16786 and Licanantay DSM 17318 microorganisms, using medium modified by the incorporation of scavenger tail, an experiment is carried out using the following protocol:
PROTOCOL
Bacterial growth took place in a 6m? useful volume reactor.
The culture medium used to propagate the microorganisms was prepared by suspending scavenger tail (at a 1.25% pulp density) in a nutrient solution composed as follows: 75 g FeSO4L, 0.99 (NH4)SO4L, 0.128g
NaH2PO4-H20/L, 0.0525g KHoPO4/L, 0.1g MgSO4-7H0/L, 0.021g CaCl,/L. The pH of the cultivation medium was adjusted to 1.8.
To start the culture, 5,400 L of cultivation medium were mixed with 600 L of bacterial inoculum carrying Wenelen DSM 16786 and Licanantay DSM 17318 microorganisms.
To enable growth of the microorganisms in the reactor, air enriched with 0.5% of CO, was supplied. The temperature of the reactor was controlled at 30°C.
The pH in the reactor was controlled by adding H»SO4 ;
The reactor was operated in batch mode for 15 days. During reactor operation, microorganism growth was monitored by microscopic count, using a Petroff-
Hausser chamber.
RESULTS
As observed in Figure 1, the concentration of microorganisms in the culture medium modified with scavenger tail rapidly increased, attaining a maximum concentration of microorganisms of 1.7x10° cells/ml in 6 days. Based on the data obtained during the exponential growth period, it was possible to determine a specific growth speed of 0.069 ht.
EXAMPLE 2
In order to prove that the association of Wenelen DSM 16786 and Licanantay
DSM 17318 microorganisms can effectively be propagated continuously using a medium modified by the incorporation of scavenger tail, an experiment is carried out using the following protocol.
PROTOCOL
Bacterial growth took place in a 50m? industrial reactor.
The culture medium used in the propagation of the microorganisms was prepared suspending scavenger tail (at a 0.125% slurry density) in a nutrient solution composed as follows: 8 g FeSO4/L, 0.99 g (NH;),SO4/L, 0.128g
NaH;PO4-H,0/L, 0.0525g KH,PO,4/L, 0.1g MgS0,4-7H,0/L, 0.021g CaCl./L. The pH of the cultivation medium was adjusted to 1.8.
° &w2007/083 39
To start the culture, 44 m® of culture medium were mixed with 6 m> of bacterial inoculum, carrying Wenelen DSM 16786 and Licanantay DSM 17318 microorganisms.
To allow the growth of the microorganisms in the reactor, air enriched with 0.5% of CO, was supplied. The temperature of the reactor was controlled at 30°.
The pH in the reactor was controlled by adding H2SO..
During operation of the reactor, the growth of the microorganisms was monitored by microscopic count, using a Petroff-Hausser chamber.
Characterization of the microorganisms present in the reactor was carried out using the quantitative PCR (qPCR) technique.
The reactor was operated in batch mode for 7 days, after which the reactor was operated continuously, by feeding the culture medium of the indicated composition at a rate of 360 L/h.
During the continuous operation phase of the reactor, samples were taken for its characterization by qPCR.
RESULTS
As shown in Figure 2, continuous operation of a bioreactor using a medium modified by the incorporation of scavenger tail, effectively allows propagation of the At. ferrooxidans and At. thiooxidans microorganism species.
Advantages of this invention:
®
In order to evaluate the lower costs of the cultivation medium as a result of the incorporation of scavenger tail, a 2,000-ton heap is contemplated, irrigated with a flow of 480 L/h during 365 days, with continuous inoculation at a concentration of 1x108 cells/mL.
The indicated conditions determine the need to produce microorganisms at 360
L/h at a concentration of 1.3x108 cells/ml. If a value of US$ 350.- per ton of ferrous sulfate is considered, at a concentration of 8 g/l of ferrous sulfate, the total substitution of this reagent by scavenger tail would produce savings of 8,830 dollars per year, as scavenger tail costs nothing. Typical copper mining operations involve bioleaching of over 2 million tons of ore per year (for example, the Cerro Colorado operation in Chile) and therefore, savings associated to the use of pyrite instead of ferrous sulfate and a separate source of sulfur is of more than US$ 8 million per year, making continuous inoculation of bacteria to the process sustainable.
In the event that copper concentrates containing pyrite are used as an energy source for bacterial growth, the fraction of bioleached copper is incorporated to the bioleaching solution together with the microorganisms, whereas the copper that remains in the concentrate can be sent to the smelter in the shape of higher grade copper concentrate, as a major part of the pyrite is eliminated during the bacterial growth process.
Claims (5)
1. Use of mining waste and concentrates containing pyrite, CHARACTERIZED ! because they are used in the culture of iron-oxidizing and sulfur-oxidizing \ : : , : microorganisms as a source of energy for bacterial growth in the process in which ores are bioleached in reactors.
2. Use of mining waste and concentrates containing pyrite, in accordance with : Claim 1, CHARACTERIZED because the waste that contains pyrite, used in the cultivation of microorganisms is scavenger tail, which corresponds to sand resulting from a flotation cell ore cleaning circuit.
3. Use of mining waste and concentrates containing pyrite, in accordance with Claim 1 or 2, CHARACTERIZED because the iron-oxidizing and sulfur- oxidizing microorganisms are mixtures of isolated microorganisms with native microorganisms from the ore that is worked.
4. Use of mining waste and concentrates containing pyrite, in accordance with Claim 3, CHARACTERIZED because the isolated micro-organisms used are Wenelen DSM 16786 and Licanantay DSM 17318.
5. Use of mining waste and concentrates containing pyrite, in accordance with any one of claims 1 to 4, substantially as herein described with reference to and/or as illustrated by any of the examples and/or the accompanying figures: Dated this 17th day of September 2007 s & Adanfs BN Applicants P ht Abtorneys
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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CL2006002910 | 2006-10-27 |
Publications (1)
Publication Number | Publication Date |
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ZA200708339B true ZA200708339B (en) | 2008-10-29 |
Family
ID=40908723
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
ZA200708339A ZA200708339B (en) | 2006-10-27 | 2007-09-17 | Use of minig waste and concentrates containing pyrite, in the culture of iron-oxidizing and sulfur-oxidizing micro-organisms as an energy source for bacteria growth |
Country Status (3)
Country | Link |
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AR (1) | AR069072A1 (en) |
MX (1) | MX2007011920A (en) |
ZA (1) | ZA200708339B (en) |
-
2007
- 2007-09-17 ZA ZA200708339A patent/ZA200708339B/en unknown
- 2007-09-26 MX MX2007011920A patent/MX2007011920A/en not_active Application Discontinuation
- 2007-09-27 AR ARP070104286 patent/AR069072A1/en not_active Application Discontinuation
Also Published As
Publication number | Publication date |
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AR069072A1 (en) | 2009-12-30 |
MX2007011920A (en) | 2008-10-28 |
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