Processing technology in the Intermediate section of tungsten-molybdenum ores of the Koktenkol deposit

Brief profile of the deposit The deposit has two types of ore in its composition: molybdenum and tungsten. Molybdenum ore is well-developed in all three deposit sections (the South, the Intermediate and the North). The amount of molybdenum ore reserves is 627 748 kilotons Tungsten ore, with maximum concentration in the Intermediate section, are of independent industrial interest and considered to be the high-priority development target. The amount of tungsten ore reserves is 71 133 kilotons

Mineral resources of the Intermediate section Mineral resources, according to the reserves confirmed by the State Commission for Reserves (a report 10579 of 27.12.1988), are represented with such commercial ores as complex (Com), scheelite (Sch) and skarn-greisen (S-G) ore types, and unpayable ores of argillaceous (Ar) type. At this, the table only includes resources being in the pit envelope. The table lists C1 and C2 reserves.

Tungsten world reserves and mining Tungsten world reserves equal 3.5 m tons. More than half of these reserves locate in China. China also produces more than 80% of the world tungsten. The Intermediate section of Koktenkol deposit reserves 254 630 tons of tungsten, which makes 7.3% of world-wide tungsten reserves. When reached maximum capacity, overall production at Dala Mining LLP will amount to 4% of world tungsten production. Countries Reserves, t Mining 2014 2015 China 1 900 000 71 000 Vietnam 100 000 4 000 5000 Russia 250 000 2 800 2 500 Canada 290 000 2 340 1 700 Bolivia 53 000 1 250 1 200 Rwanda n/a 1 000 Austria 10 000 870 Spain 32 000 800 730 Portugal 4 200 671 630 Great Britain 51 000 - 600 USA 140 000 Other states 670 000 2 060 2 100 Total: 3 500 200 86 791 87 330

Traditional processing schemes Wolframite sintering with sodium and saltpeter Open pit Gravity Floatation Fluorite making WO3 Autoclave-sodium leaching APT Fluorite Scheelite concentrate S-G Clay, Com, Sch Tailings Sintering Open pit Gravity Floatation Fluorite making WO3 Autoclave-sodium leaching APT Fluorite Scheelite concentrates Scheelite concentrate S-G, Sch Clay, Com Tailings An open-pit method requires a traditional open pit construction. Also a construction of two concentrating plants: Gravitational - for processing clay and mixed ores and Flotating for processing skarn-greisen and scheelite ores. End products after these processes would be wolframite concentrate. Construction of hydrometallurgical plant (autoclave-sodium leaching of sheelite concentrates) would provide for an APT production.

Tungsten minerals Clay ores of the Koktenkol deposit, spreading over 50 meters of the weathering crust layer and primarily associate with goethite and manganite, form part of wolframites, garnets, hydromicas and smectites group, which does not allow to use traditional flotation methods for tungsten concentrate production.

Distribution of valued components (W, Mo, Cu) over the depth and ore types

In-situ recovery (ISR) Method Leaching solution is pumped into four injection wells Influenced by chemical reagents, the solution becomes saturated with valuable components (becomes a pregnant /productive solution) and is then recovered through an extraction well Pregnant solution is then settled and directed into the processing module, where end- products are being produced Mother solution returns to the head of the process. This process continues being repeated until targeted amount of the valuable components have been extracted form the block APT

Advantages of in-situ recovery In-situ recovery method in comparison to traditional mining methods is less capital-intensive and more responsive. It avoids heavy costs connected to an open-pit construction, acquisition of mining machinery and construction of flotation plants. Requires significantly lower capital expenditures for processing clay and mixed ores, involvement of which would hardly be possible (or at very high costs) using traditional mining methods. Absence of the disturbance to the ground surface, no stock piles of “off-balance” ores and empty ores, and also no tailings dams (in-situ recovery is one of the most eco-friendly methods of deposit development); Efficient management of the total output units and mining staff ISR entirely excludes any source of dust release.

In-situ recovery application at the Koktenkol Favorable geological and hydrogelogical conditions Geological Presence of ground water Valuable components of weathering crust easily react with chemical reactant aggregating water-soluble compounds Hydrological Appropriate level of well flow rate, capacity, filtration and permeability of ores. Two-stages technological scheme has been developed Acidification with a hydrochloric acid Leaching with a mixture of hydrochloric and oxalic acids Field-testing project and construction have been completed at the site Field-testing to confirm application of the ISL at Koktekol will be completed by the end of summer 2018

ICR technology for tungsten-molybdenum ore Our technology for complex processing of tungsten-molybdenum ore (mixed and clay ore types), with in-situ recovery method, is pioneering and unique throughout the world. Application of the ISR technology will provide low production costs of valued components and be able to meet necessary quality requirements for the metallurgical extraction. The derived productive solution may be processed with sorbate, extractive or combined method to produce ammonium polyvanadate (APT), ferrotungsten polyvanadate, and also tungsten, molybdenum and copper concentrates. The possibility for producing of cathode copper has been established according to the following scheme: extracting – re-extracting – electro-extracting.

Koktenkol Development Pilot production is planned to begin in 2020 with initial APT production at 500 tons p/a Initial CapEx estimated at USD 20 mln, which is 3 times less than what it would be using an open pit method Company plans to gradually increase it production capacity to 3000 tons of APT p/a An estimated life of mine is 35 years Company also plans to extract copper and molybdenum as side products

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