High Calcium Wolframite Concentrate Leaching Process

China has abundant tungsten resources, for the mixed materials containing wolframite, such as high calcium wolframite concentrate, refractory tungsten material, tungsten fine slime and scheelite ammonia leaching residue, only sodium hydroxide leaching can only dissolve wolframite and it can not leach scheelite. If hydrochloric acid leaching alone can only dissolve scheelite, the wolframite can not be leached.

Some researchers have created a method of simultaneous leaching of wolframite and scheelite under normal pressure by adding phosphate and ammonium salts in alkaline leaching solution.

High calcium wolframite concentrate 100g (containing WO₃ 69.9%, Ca 3.56%, Mn 7.44%, Fe 12.02%, P 0.044%, As 0.012%, SiO₂1.85%) with particle size of - 320 mesh. Add 130ml of water and add Na₃PO46g (equivalent to 0.7 times the theoretical amount needed to generate calcium hydroxyphosphate). The concentration of NaOH in leaching solution is 430g/ liter, the amount of sodium hydroxide is 0.77 of NaOH/WO₃ weight ratio. The leaching temperature is 110°C, the pressure is soaked for 4 hours at normal pressure. The total leaching rate of tungsten is 98.8%.

The advantage of the method is that it can simultaneously leaching wolframite and scheelite at atmospheric pressure, and the total leaching rate of tungsten is 98%. It is not necessary to add expensive high pressure leaching equipment and high pressure boiler. It has little change to the existing process and equipment. It can make full use of the existing plant's normal pressure alkali leaching equipment, and can reduce energy consumption. It is easier to be used in industry.

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