In-Situ Leaching Scheme

Long-term investigations prove that the in-situ leaching technique (ISL) used by Kazatomprom has no adverse impact on the environment with the International Atomic Energy Agency (IAEA) recognizing the technique as the most ecologically sound and safe method of deposit development.
 
In-situ leaching is a method for development of sandstone bedded infiltration type uranium deposits without the use of mining by selective in-situ transfer of natural uranium ions in pregnant solution. The uranium-bearing ore remains underground as opposed to conventional methods (shafts and pits), which require significant reclamation costs, and thus the ISL method differs in terms of high ecological safety, low costs and ease of technological operations.
 
ISL is a closed cycle process with the following major stages:
1.      Drilling of wells, installation of technical equipment and arrangement of well sites.

2.      Supply of low-sulfuric solution via injection wells into the ore body

3.      The key leaching process takes place underground where the uranium is transferred into the so called pregnant solution.

4.      The pregnant solution rises to the surface and sorption and desorption processes takes place in the ion-exchange columns. Uranium then precipitates from eluate and is dried to the state of yellow cake.

5.      Yellow cake is converted into U3O8 in one of Kazatomprom’s three refineries.

6.      In the future all uranium mining enterprises plan to produce the end product in a form of uranium concentrate of ASTM quality at mining sites.

The total area of an ISL facility including refinery, for example, for 500 tons of U/year U3O8 would occupy one fourth part of a typical hydrometallurgical plant with the same capacity.
With the in-situ leaching method, used in the development of deposits, the necessity for construction of tailing ponds (for storage of high radiation level waste) is eliminated - as distinguished from mining of uranium in pits or shafts.

It has been identified that the natural hydrogeochemical environment at uranium mines of South Kazakhstan has a unique capability for self-recovery from technogenic impact. Due to gradual reinstatement of natural oxidation-reduction conditions the remediation process of underground water of ore-hosting aquifer, though slowly, irreversibly takes place. Kazatomprom has developed a method of significant intensification of this process accelerating remediation tenfold.  The result of observations over 13-years at the Irkol deposit serves as an example of natural demineralization of residual solutions. Thus the Irkol scheme in-situ leaching method used in South Kazakhstan is, without exaggeration, the most cost-efficient and ecologically safe mining method known.

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