Leaching Process of High Calcium Wolframite Concentrate

China has abundant tungsten resources, and reserves and concentrate output rank first in the world. However, the tungsten concentrates produced in several important tungsten mines belong to high calcium wolframite concentrates. At the same time, a considerable amount of refractory tungsten slime containing calcium is produced in each tungsten concentrator. There is no suitable treatment method at present.

For mixed materials containing wolframite, such as high-calcium wolframite concentrate, refractory wolframite, tungsten slime and ammonia leaching residue of scheelite, only wolframite can be dissolved by sodium hydroxide alkali leaching method, but scheelite can not be leached by hydrochloric acid leaching method.

For this reason, some researchers have created a method that can leach wolframite and scheelite simultaneously at atmospheric pressure, breaking the problem of refractory high-calcium wolframite concentrate, avoiding the use of expensive high-pressure leaching equipment. The method is to add phosphate and ammonium salts in the alkaline leaching solution.

High calcium wolframite concentrate 100 g (containing WO₃ 69.9%, Ca 3.56%, Mn 7.44%, Fe 12.02%, P 0.044%, As 0.012%, SiO 21.85%) with particle size of - 320 mesh. Add 130 ml of water and add Na₃PO₄₆ grams (equivalent to 0.7 times the theoretical amount needed to generate calcium hydroxyphosphate). The concentration of NaOH in leaching solution is 430 grams / liter, and the amount of sodium hydroxide is 0.77 of NaOH/WO₃ weight ratio. The leaching temperature was 110 degrees and 4 hours at atmospheric pressure. The total leaching rate of tungsten is 98.8%.

The advantage of this method is that wolframite and scheelite can be leached simultaneously at atmospheric pressure. It is especially suitable for treating mixed materials containing wolframite and scheelite, such as high calcium wolframite concentrate, refractory tungsten material, tungsten slime and ammonia leaching residue of scheelite, etc. The total leaching rate of wolframite and scheelite can reach 98%. There is no need to add expensive high-pressure leaching equipment and high-pressure boiler, the existing process and equipment are not changed, can make full use of the existing plant's atmospheric alkali leaching equipment, and can reduce energy consumption, more easily practical in industry.

• < Prev
• Next >