ISL Mining in Kazakhstan and Technology Development Vienna, IAEA, April 2013

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1 ISL Mining in Kazakhstan and Technology Development Vienna, IAEA, April 2013 O. Gorbatenko

Uranium resources in Kazakhstan Kazakhstan Identified Resources of uranium amount to 900 thousand tons, and Prognosticated and Speculative Resources about 800 thousand tons More than 70 % of uranium

2 Uranium resources in Kazakhstan Kazakhstan Identified Resources of uranium amount to 900 thousand tons, and Prognosticated and Speculative Resources about 800 thousand tons More than 70 % of uranium resources in sandstone deposits: - roll-front deposits in the south - basal channel in the north Chu-Sarysu, Syrdarya and Northern Kazakhstan ore provinces are being exploited by Kazatomprom Kazatomprom is using in-situ leaching method since 1973 ( 25 license, 22 mines, 14 companies) 2

3 ISL mine 3

4 Characteristics of Uranium Roll-Front Deposits Age of uranium deposits: Upper Cretaceous and Paleogene Sandstones with good porosity and permeability Depth: meters Uranium mineralization: Coffinite U(SiO4) 1-x (OH) 4x, Pitchblende UO 2 U 3 O 8 Uranium Average Grade : 0,01 0,5 % Recovery target: 90 % Carbonate (CO 2 ) < 2 % Organics < 3 % Mudstones < 20% CONFIDENTIAL 4

5 Ground Water Hydraulic conductivity : 1 25 m/day Ground water velocity: 5-15 m/year Water mineralization: 0,6-5 g/l ph: Aquifuge (bounding shales / clays) Water pressure: m Water table level: 150 m below surface 30 m above surface Temperature of ground waters: 14 C - 45 C CONFIDENTIAL 5

6 CONFIDENTIAL

7 ISL Mining Sulfuric acid easily dissolves uranium minerals. ISL is based on injection of sulfuric acid solution through injection wells to uranium ore and pumping out productive solution containing dissolved uranium through productive wells. Solutions are pumped through filters (screens) located at the bottom side of the wells. CONFIDENTIAL 7

8 h 2 0 h 1 h H S 2 0 H S 1 L H п л H H 2 H 1 М 1 2 A A R R б CONFIDENTIAL

9 CONFIDENTIAL

10 CONFIDENTIAL Reagents being used

11 General characteristics of uranium in-situ leaching process Leaching agent: sulfuric acid - H 2 SO 4 Sulfuric acid consumption : kg/kg of mined uranium kg/ ton of ore mass Stages of ISL: Acidic treatment - H 2 SO 4 : g/l, рн=1,5-2,0 Active leaching - H 2 SO 4 : 8 10 g/l Leaching - H 2 SO 4 : 3 g/l Residual leaching no H 2 SO 4 CONFIDENTIAL 11

12 Productive solution Parameter Content Parameter Content U 6+ 0,06 0,8 g/l NO 3-0,2 0,8 g/l Fe 3+ 0,3 0,7 g/l SO 4 2-7,0 15,0 g/l Fe 2+ 0,1 0,8 g/l Cl - 0,1 0,5 g/l Ca 2+ 0,3 0,6 g/l SiO 2 0,12 0,2 g/l Mg 2+ 0,2 0,7 g/l Total mineralization 10-20,0 g/l Al 3+ 0,5 0,8 g/l Eh mv K + + Na + 0,2 0,5 g/l рн 1,7 2,3 H 2 SO г/л CONFIDENTIAL 12

13 CONFIDENTIAL

14 Colmatation types Colmatation - decreasing the permeability of the filter and the area around it. Chemical (temporary and permanent) Gas Ion-exchange Mechanical Temporary chemical colmatation Fe(OH) 3 precipitates at PH 1,5 4,1 Al(OH) 3 precipitates at PH 3,3 5,2 Colmatation is eliminated provided raising acid content in injection solution Permanent chemical colmatation Gypsum precipitation H 2 SO 4 + CaCO 3 + 2H 2 O = H 2 CO 3 + CaSO 4 *2H 2 O hardly soluble Eliminates by injection of strong acids (hydrochloric - HCl or nitric HNO 3 ) CONFIDENTIAL 14

15 Gypsum aggregates formed during supersaturation of solutions for CaSO4. CONFIDENTIAL 15

16 Colmatation types Gas colmatation Formation of carbon dioxide and hydrogen sulfide in the layer due to reaction of sulfuric acid with carbonate rocks. Depends on water pressure and ph of the solutions. ph water pressure, m Ion-exchange colmatation Swelling of clayey substances. The decrease (in 2 or more times) the permeability of sand-clay rocks as a result of swelling of clay particles in the replacement of their micelles of divalent cations (Ca2 +, Mg2 +) by monovalent ions (Na +, K +). CONFIDENTIAL

17 Colmatation types Mechanical colmatation Mechanical colmatation may occur as a result of: injection of contaminated solutions (particles of clay, quartz sand and powdered sorbent) suffusion processes due to high hydraulic gradient or improper selection of the filter design. In the solid phase found the newly formed aluminum compounds (aluminit), iron (sulfates and hydroxides) and calcium (gypsum) In addition to the above, in our opinion, should be allocated as a separate type - colmatation due to clay particles from the drilling fluid at the time of construction of wells. The content of clay particles (less than 0.05 mm) is from 5 to 45%. Appearance of all types of colmatation, as a rule, is complex and each individual types develops, promotes the formation and development of other types of colmatation. CONFIDENTIAL

18 Content of colmatant in well filter, % Element Content Element Content Element Content Ag La Te Al Mg Ti As Mn V Ba Mo W Be Na Y Bi Ni Zn Ca P Zr Cd Pb Moisture 42,73 Co Sb U 0,345 Cr Sc СO 2-3 1,7 Cu Se SiO Fe Sn S 2.94 K Sr SO CONFIDENTIAL 18

19 Demonstration of chemical colmatation CONFIDENTIAL 19

20 Colmatation reasons Geological structure of ore body Drilling technique Construction of well and filter Way of filter setting Hydrochemical composition of underground water Type of pumping out equipment Leaching agent type Well operation type Other reasons Ways of colmatation elimination Airlift pumping Pneumatic-impulse treatment Reagent treatment CONFIDENTIAL

21 Pneumatic-impulse unit CONFIDENTIAL 21

22 Well output, m3/h Well output, m3/h Ways of colmatation elimination 9 Airlift pumping efficiency 12 Pneumatic-impulse treatment after treatment before treatment after treatment before treatment Injection well Production well 0 Injection well Production well CONFIDENTIAL 22

23 Conclusion New types of drilling fluids Assess the impact of backwash wells to reduce colmatation. New types of filters (screens) Improvement of methods of pumping in the construction of wells. The use of new equipment and reagents Development of effective methods of conducting a comprehensive repair work (acid treatment, pneumatic and another impulse treatment, pumping). The use of inhibitors to prevent the precipitation colmatant CONFIDENTIAL 23

24 Self-recovery within 12 years after completion of mining operations In the course of ISL sites operation in balanced mode, there is no significant contamination, boundary is at 25 m from end wells. CONFIDENTIAL

25 CONFIDENTIAL Thank you for your attention!

THE NEW METHOD FOR ISL WELLS PERFORMANCE IMPROVEMENT AT ZARECHNOYE DEPOSIT (KAZAKHSTAN)

THE NEW METHOD FOR ISL WELLS PERFORMANCE IMPROVEMENT AT ZARECHNOYE DEPOSIT (KAZAKHSTAN) A.Boytsov, M.Niyetbayev, M.Pershin, I. Avdassyov, A. Yermilov URAM-2014 Vienna, June, 2014 Uranium deposits and mines