Microflora for biogeotechnology
Development of New Microorganisms to Extract Gold
Tech Area / Field
- BIO-IND/Industrial Biotechnology/Biotechnology
- CHE-ANL/Analytical Chemistry/Chemistry
- ENV-EHS/Environmental Health and Safety/Environment
3 Approved without Funding
National Academy of Sciences of Kyrgyzstan / Institute of Chemistry and Chemical Technology, Kyrgyzstan, Bishkek
- University of Michigan / Colledge of Engeneering / Department of Chemical Engineering, USA, MI, Ann Arbor
Project summaryThe purpose of the work - (1) to search and select microflora strains from natural objects of gold ore deposits of Kyrgyztan, and (2) to produce technogenic strains (on the basis of microbe banks) perspective for their further use in biogeotechnology.
The resources of Kyrgyztan gold reserves are estimated by different authors to be 2.5-3 thousand tons.
The current Kyrgyztan technologies allow extraction of only 70-80% of the gold in the ore. The rest goes to the waste.
To reduce gold losses possible only through application of various biotechnological methods (bioleaching, biosorbtion ect.)
Two main problems of gold extraction exist that prevent completed extraction:
1. when gold is in crystal lattice of sulphide minerals (hard ores);
2. when gold is in solution, but is not extracted by ordinary flotation methods as its particles have microscopic
(0.1-100 mcm) or submicroscopic (0.0001-0.1 mkm) dimensions (finely dispersed).
The first problem can be solved by bioleaching of metals from hard ores using microbes like Acidithiobacillus ferrooxidans.
The second problem can be solved by using living microorganisms to biosorb the dispersed gold
Firstly, to have effective biogeotechnology for this area of research, the isolation of highly productive microflora strains, capable of carrying out concrete technology tasks, such as metals oxidation or reduction, metals biosorption or sedimentation is critical. A second important task of these strains is in the purification of industrial sewages from heavy metals and various toxic substances such as cyanides. New approaches that showed marked improvements in solving these tasks include the use of microorganisms.
At present a new technological line of biogeotechnology has been adapted for a wide use of metal extraction from ores, concentrates, mountaineous minerals and solutions using microorganisms and their metabolites. A whole series of similarly successfully applied technologies have been used for absorption of noble metals. However, there are problems in the application of these biotechnologies because of variations between different deposits. It has been shown that it is necessary for each deposit to select its own microflora (know-how), because components of industrial solutions may render inhibiting effect on non-adapted microflora. More effective processes can be based on isolating aborigenic microbial strains from natural deposits followed by their propagation and later use.
In this application, we propose to produce new aborigenic microflora strains for extraction of gold as follows:
bioleaching of gold and accompanying metals from sulphide minerals (biooxidation)
Destruction of cyanides and their complexes in industrial waters of Gold Extraction Factories (GEF) with liberation of gold from KAu(CN)2 or NaAu(CN)2.complex.
Our Preliminary laboratory tests using iron-oxidizing, sulphur-oxidizing, metal sorbing strains obtained from gold containing ores Makmal and Kumtor deposits show very encouraging results since we are able to obtain 99.5% extraction by gold bioleaching
This development of this technology is very timely in connection with depletion of world's reserves of goldcontaining ores, an urgency of application of ecologically safe technologies and economical for applications to gold extraction from ores and industrial waste of Kyrgyz Republic.
In the case of Project successful completion new complex biotechnologies for gold-ore deposits allowing to increase gold extraction on 15-20% without additional deposits exploitation will be offered.
It is important to notice that these methods are environment and energy friendly and that at present biogeotechnology is not used in Kyrgyztan. One of the main reasons is the absence of technogenic strains of microflora, adapted to composition of the ore of each concrete deposit. The creation of collection of new aborigenic strains isolated from different natural deposits of Kyrgyztan and tested on possibility of their using in hydrometallurgy, will help to solve very significant energetic, environmental and economically important problems and can be used not only in Kyrgyzstan, but also in other gold mining countries
1. Ensure ecological purity of Kyrgyztan natural medium in expense of cyanide decontamination in industrial GEF waters
2. Develop technology of increasing gold manufacture in expense of cutting down its loss in waste
3. Create the bank of technogenic microorganisms perspective for biohydrometallurgy.
Executors of the Project will be weapon specialists and research workers of National Academy of Sciences of Kyrgyz Republic.