Rhenium Bioextraction while Uranium Underground Leaching
Biotechnology of Rhenium Associated Extraction while Uranium Underground Leaching
Tech Area / Field
- BIO-IND/Industrial Biotechnology/Biotechnology
- OBS-NAT/Natural Resources and Earth Sciences/Other Basic Sciences
8 Project completed
Senior Project Manager
Emel'yanov V K
Conversion Enterprise "KK Interconnect", Kazakstan, Almaty
- Institute of Microbiology and Virology, Kazakstan, Almaty\nNational Atomic Company "Kazatomprom", Kazakstan, Almaty
- Universität Stuttgart / Institut fur Siedlungswasserbau, Germany, Stuttgart
Project summaryThe goal of the Project is to develop and try out:
– biotechnological schemes of rhenium associated extraction while uranium mining by underground leaching (UL);
– construction development of pilot installations for rhenium biosorption from the working solutes of uranium sulphuric-acid UL devices.
Project background and foundation.
The sphere of rhenium utilization in world production (heat-resistant and hard alloying compositions, space and aircraft industry, oil reforming catalysts, exhaust gas neutralizes, et al.), has broadened significantly of late years. The maim volumes of rhenium are passingly extracted at non-ferrous (copper) metallurgy plants in Kazakhstan, Chile, Germany and Canada. However, stable demand for rhenium at world market stimulates searching new sources of raw materials, uranium deposits being one of them.
The increased rhenium contents (1 to 7 g per t) of ores of some Kazakhstan's sheet-infiltration uranium deposits has been determined, up to singling out complex rhenium-uranium fields. Apart of rhenium, other valuable impurities increased contents of the ores (selenium, germanium, scandium, molybdenum, vanadium, yttrium, rare earthes, silver) has been ascertained.
These deposits occur at a depth of several hundred meters. The ore fields are located in scarcely lithified terrigenous deposits on the pinching out of regional zones of bed oxidation. They are usually treated by the technique of bore-hole sulphuric-acid underground leaching (UL). The UL technological scheme includes uranium leaching in interhole space, its sorption by ion-exchange resins with subsequent desorption and concentrating resulting in flooded yellow cake production. Three mine enterprises of the National Stock Company (NSC) "Kazatomprom" (Stepnoe, Tsentralnoe and RU-6) are working now according to the scheme.
Rhenium is ascertained to extract together with uranium by UL sulphuric-acid method and to accumulate concentrations sufficient for industrial processing – 0.2 mg per l – in working recycled solutes and by ion-exchange resins. In the beginning of 90-s trial and production tests were carried out at two mine enterprises (Stepnoe, Tsentralnoe). The technological schemes included consecutive rhenium desorption (after uranium) from ion-exchange resins and its extraction concentrating (up to 30 g per l) with the help of kerosene in the presence of emulsifying agents ТБФ and ТАД. At the last stage final rhenium commercial product – ammonium perrhenat (NH4ReO4) – corresponding to the standard ТУ-48-7-1-90 is obtained. Beginning from 1993 all trial and production installations of associated rhenium extraction are put in dead storage and partly disassembled because of high cost of this production. At present about 2,500 kg of rhenium is accumulated in working recycled solutes and by ion-exchange resins of UL installations of Kazakhstan's uranium enterprises. Development of more effective techniques of this valuable element associated extraction is necessary. Approximate level of annual rhenium associated extraction from uranium-containing ores and its accumulation in separate links of the UL technological chain will be constantly maintained proceeding from the planned volumes of uranium treatment. This will determine the stability of raw material supply as well as probable scope of rhenium production at uranium mining enterprises.
While uranium mining, biosorption technologies of rhenium and other rare element associated extraction can become a competitive trend. The authors of the present project have the RK priority of the schemes of rare element biosorption by microorganisms and microbial surfactants (MS). As for rhenium accompanied by osmium, the biometallurgical schemes of their extraction from cuprous sandstone are worked out at the Zhezkazgan integrated mine-and-nonferrous metallurgy complex. Thus, priority established for three cultures of MS producing microorganisms, for two methods of osmium biometallurgical extraction from osmium-ccntaining phase and one for osmium selective sorbent.
An analogous complex of scientific researches is envisaged while realizing the proposed Project of rhenium associated extraction at uranium enterprises. To achieve the goal of scientific investigations the following subtasks should be solved:
– to study the rhenium content of working technological solutes of operative uranium UL installations;
– to select the most active rhenium biosorbents;
– to develop the scheme of rhenium biotechnological extraction at uranium UL installations;
– to bring about development engineering of the installations of rhenium biotechnological extraction at operative uranium UL enterprises.
Working solutes from three uranium UL installations (NSC "Kazatomprom", "KK Interconnect"), 30 assays of total volume, will be sampled within the framework of the present Project. Every sample will be analyzed for rhenium content at the chemical laboratories Alex Stewart and NSC "Kazatomprom" under the certified analytical technique.
To select the most active rhenium biosorbents, the Project envisages micro-organism screening of thirty potentially perspective strains of different classification groups and determination of optimal physiological conditions of rhenium biosorption (the Institute of Microbiology and Virology, "KK Interconnect"). As a result, a biotechnological scheme of rhenium associated extraction will be elaborated, and the proposals on its introduction into production will be substantiated.
At the last stage of the Project all participants submit proposals on industrial utilization of this biotechnological scheme.
All the complex of micro-biological and biotechnological investigations is supervised by the Project foreign collaborator – Prof., D. Karl Karl-Henrik Engesser, Stuttgart University (Germany).
The Project meets ISTC tasks and aims, since:
– more then 60 % of the personnel, being engaged in the designed work carrying out, are scientists and engineers, that earlier occupied themselves with weapons development and production;
– scientific investigations conducted will make available substantiation of a new method of rhenium drawing into industrial processing from non-traditional sources of mineral resources;
– installations of rhenium associated extraction being introduced while uranium deposits mining and treating, the sphere of production commercial activity will broaden in the direction of conversion intensification.