Wolframite Calcined to Convert Scheelite

Wolframite mainly adopts the classical process, extraction and ion exchange process for smelting. Because of the use of sodium hydroxide and hydrochloric acid in these processes, the chemical properties of sodium and chloride ions are active, the precipitation can not be separated by economic and effective methods. It is difficult to open the process in the process and will produce acid and alkali waste liquid and pollute the environment.

So some scholars proposed a method for transformation of wolframite into scheelite and obtained a patent. The understanding of this method should be the conversion of wolframite to artificial scheelite.

Turn the wolframite into scheelite: The wolframite and calcium salt are mixed and calcined to obtain the burned material containing scheelite composition, further processing to get the solution of ammonium tungstate by sintering material.

Wolframite mixed with calcium, the chemical reaction occurred:

FeWO₄+Ca²⁺=CaWO₄+Fe²⁺

MnWO₄+Ca²⁺=CaWO₄+Mn²⁺

The test process is as follows: in a muffle furnace, containing 65% WO₃ to 500g and the particle size was: adding 1.2 times amount of 320 to theory in wolframite concentrate (i.e., 168g) of calcium carbonate, the reaction temperature is 1000 degrees Celsius, 2 hour calcination time, get burned object.

Firing by hand breaking ball mill - wet grinding, particle size of 320 mesh, decomposition in high pressure kettle, at a temperature of 180 degrees Celsius and under the pressure of 1.7MPa, the decomposition of scheelite with twice the theoretical amount of ammonium phosphate (ie, 193.7 g) for 3 hours with ammonium phosphate resulted in 98.2% decomposition.

Under the optimum conditions, the transformation of wolframite scheelite ammonium phosphate decomposition rate can reach 99.5%; the transformation of wolframite technology to solve the key technology of scheelite wolframite in closed smelting process, provides a technical approach to achieve zero discharge of black tungsten smelting and recycling wastewater; The raw materials and energy consumption of the tungsten smelting process can be reduced by 20%, and the cumulative benefits of the national wolframite smelting can be 100 million.

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