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Biorecovery of metals

#KR-2302


Development of biotechnological basis for gold and non- ferrous metals recovery from sulphidic concentrates of Kyrgyzstan ore processing enterprises

Tech Area / Field

  • BIO-IND/Industrial Biotechnology/Biotechnology
  • BIO-MIB/Microbiology/Biotechnology

Status
3 Approved without Funding

Registration date
09.08.2016

Leading Institute
National Academy of Sciences of Kyrgyzstan / Institute of Chemistry and Chemical Technology, Kyrgyzstan, Bishkek

Collaborators

  • School of Biological Sciences, Bangor University, UK, Bangor\nOhio State University, USA, OH, Columbus\nTU Bergakademie Freiberg, Germany, Freiburg

Project summary

Goal of the Project is to reduce loses of gold and non-metals in waste during the process of sulphidic gold bearing concentrates of ores.
The Project researches orient at the development of new selective method for iron-oxidizing microorganisms and creation of biotechnological basis for sulphidic gold bearing concentrate processing with use of indigenous microorganisms (biohydrometallurgy).
Extraction of metals in solution through cycling biooxidation / bioleaching is one of the most often used methods of biohydrometallurgy. The microorganisms that applied in the biotechnological processing of concentrates have capacity to oxidize / leach sulphidic minerals and utilize energy from the oxidation for their own growth and reproduction. Iron, contained in sulphidic minerals (such as pyrite, arsenopyrite, chalcopyrite and some others) transfers into oxidized form and becomes active leaching agent for the minerals. Sulphidic compounds oxidize into sulphuric acid. Due to the reactions of oxidation and reduction on the mineral surfaces, which the microorganisms catalyze, the process of leaching continues. As a result, the smallest particles of gold (mkm and nm size) closed within the minerals become accessible for cyanidation process and extraction.
The biotechnology of processing sulphidic concentrates of ores is ecological friendly, as during the process there is no dangerous gas waste in atmosphere. In addition, many metals can be dissolved and recovered without waste. Arsenic compounds absorb on ferrihydrate sediment in this process.
First of all the biotechnology for processing concentrates depends on their mineral composition and chemical compounds. In addition, it depends on indigenous microorganisms that live on the initial ore. Indigenous microorganisms are already adapted to the ore chemical compounds and they show better oxidative ability during laboratory cultivation then museum strains. Therefore, it is important to find out microorganisms capable of carrying out the required task for every kind of concentrate.
Optimal cultural conditions for biooxidation usually are achieved by adjusting acidity, temperature, aeration and medium composition for microorganism’s growth.
Our experiments with museum mesophilic strain of Acidithiobacillus ferrooxidans revealed that biooxidation of iron can be accelerated with the use of selected microbial cells. Electromagnetic field treatment of the microorganisms leads to the selection cells, capable to oxidize iron more actively.
In the frame of the Project, the following works will be carried out:
    · Isolation and identification of indigenous microorganisms capable of sulphidic minerals oxidation.
    · Determination of minerals and chemical elements of the sulphidic gold bearing concentrates and ores where indigenous microorganisms inhibit.
    · Optimization of cultural conditions for intensive biooxidation.
    · Electromagnetic field treatment of museum and indigenous microorganisms and determination their iron oxidative activity for the selection
    · Creation of the laboratory model construction for modeling technological biooxidation process.
    · Development of the technological scheme of gold and non-ferrous metals biorecovery from gold bearing sulphidic concentrates.
    · Creation of microbial cultures museum for biooxidation process.
    · Presentation of the Project results to the International Scientific Community.
      Expected results and benefits include:
        1-new industrial strains; 2- patents; 3- new approach in biooxidation process.
Participants of the Project are scientific researchers of National Academy of Sciences: chemical analytics, microbiologists,
geologists, mineralogists and biotechnologists.


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