Microbiological extraction of fine-dispersed gold
Development of the Biotechnology for Fine-Dispersed Gold Extraction out of the Ore and Wastes on the Basis of Microbiological Method
Tech Area / Field
- BIO-IND/Industrial Biotechnology/Biotechnology
3 Approved without Funding
National Academy of Sciences of Kyrgyzstan / Institute of Chemistry and Chemical Technology, Kyrgyzstan, Bishkek
- Universität Tübingen / Center for Applied Geoscience, Germany, Tübingen\nRensselaer Polytechnic Institute, USA, NY, Troy\nLaurentian University, Canada, ON, Sudbury\nMichigan Technological University, USA, MI, Houghton
Project summaryAim of this proposal is the creation of a complex of biotechnologies for auriferous ores concentration including the process of biofloccular flotation at the first stage and biological disclosure of sulfides as a preparatory stage with the purpose of liberation of gold extracted during the main process.
The advantages of such complex technology are in the possibility of increasing the gold extraction by 5-25% for ores of different mineralogical content, in attraction of base ores with metal content 0.8-2 g/ton, tails of concentration mills, other technogenic wastes into processing and at the same time it resolves environmental problems by utilization of wastes from gold-extracting industry, which contain, as a rule, the toxic organic reagents, cyanides, heavy metals, poisoning soil and water springs.
Actuality of this proposal is connected with the fact that Kyrgyzstan is one of the leading countries in the world by the reserves of auriferous ores; for the last 20 years the gold-extracting factories have used the methods of gold dissolution in sufficiently concentrated solutions of cyanides, in this situation the main danger is in the waste repositories (tailing dumps) being created at present and existed for many years, containing heightened concentrations of toxic substances and heavy metals. Factories located up in the mountains directly near the glaciers, where the water resources are formed, are of especial danger. Besides, many gold-extracting factories are situated, as a rule, in the inhabited regions, in agricultural lands. That is why using such methods as the ore cyaniding in the industry is categorically impossible and it is also necessary to construct the whole technological process on the very high level of environmental safety.
Such a situation makes to search for new methods of indicated ores processing and environment protection in addition to the conventional ones when organizing the appropriate production. These new methods, first of all, are the environmentally safe, relatively cheap biotechnological processes allowing at the same time to increase the efficiency of gold extraction. Among them are the biofloccular flotation of highly dispersed gold; biological lixiviation of metals with the liberation of gold and other noble metals.
Creation and industrial mastering of these technologies are based on the results of basic researches of the processes of microorganisms’ interaction with metals in ionic and colloidal states. The fundamental moment is the discovery of a new basic phenomenon of selective heterocoagulation of intact cells of metallophilic microorganisms with the particles of metals and minerals, which results in bioadhesion of particles of a certain nature on the cells surface with their further flocculation and formation of bioaggregates extracted by flotation or sedimentation methods. And the most important concomitant processes based on oxidation-reduction reactions of cells, are the oxidation of sulfides, changes of the valency of iron, lead and arsenic in the processes of biodestruction of sulfide ores.
The preliminary researches held using more typical auriferous ores of Kyrgyzstan from Kumtor and Taldybulak deposits have shown that these ores contain a significant amount of free highly dispersed gold (in some tests – over 50%), the heightened content of sulfides, and also it was detected that the ledge is not uniform by the content of valuable component. The result of performed laboratory works is the realization of a scheme: biofloccular flotation with preliminary biological destruction of sulfide component. The gold extraction exceeded the indices of the technology using cyanides, there was obtained the high-quality concentrated product easily processed by metallurgical method without additional purifying operations, the wastes of processing did not contain toxic components. At the same time the metallophilic and metal-resistant strains of bacteria educed out of the ores of appropriate deposits subjected to a special selection and genetic design have been used.
The main concept of the project suggested by weapon scientists (formerly – experts on biological weapon) of the Kyrgyz Republic and also of world community is to obtain new developments of peaceful nature. Our Republic needs new technologies for environment protection and biopersity preservation.
Implementation of the Project will allow achieving the following results:
- to create a complex of colloidal biotechnologies including processes of biofloccular flotation and preliminary destruction of sulfides for concentration of gold-containing ores allowing to increase the efficiency of gold extraction and to process the ore in the conditions of high environmental safety;
- to create the bank of metallophilic metal-resistant strains of bacteria able to selectively accumulate gold in complex mineral dispersions by educing the latter ones out of the ores of respective deposits with following selection and genetic design;
- to investigate the optimal technological conditions for implementation of the processes developed and to conduct testing on ores of respective deposits. To prepare scientific and technological reports and to give recommendations on application of a new complex of technologies in the industry.