Decomposition of Tungsten Concentrates and Other Mineral Raw Materials Decomposition method

Many have studied the decomposition of tungsten mineral raw materials, in addition to several domestic and industrial production in the application of methods, chlorination and fluoride salt solution is also moving towards industrialization, while the high temperature carbonization melt extraction from the direct production of tungsten tungsten carbide technology have reached the industrial applications. In addition, the complexation of scheelite acid leaching method, EDTA sodium salt leaching method has also been reported.

Scheelite Chloride Leaching

Fundamental

Scheelite sodium or ammonium fluoride can be used to break down. Sodium fluoride and scheelite reaction following formula: CaWO4 (s) +2 NaF (aq) = Na2WO (aq) + CaF2 (s)

The use of NH4F + NH4OH as a leaching agent, the reaction with scheelite obtained directly (NH4) 2WO4 solution. At 225 ℃, the measured decomposition scheelite NaF concentration equilibrium constant Kc 24.5, and sodium carbonate decompose under the same conditions scheelite, measured Kc value of only 1.52, so the sodium fluoride and ammonium is oxidized one kind is more effective than sodium carbonate decomposition scheelite reagents. Scheelite NaF decomposition below 100 ℃ under the conditions of mineral particles CaF2 film formed on the surface, hindering further reaction; temperature higher than 100 ℃, the CaF2 film off, the reaction speed is mainly affected by the chemical reaction speed control.

Process and Lndicators

Zhen-Gang YAO White tungsten leaching tests carried out NaF, when the temperature is 190 ℃, NaF dosage is 1.2 times the theoretical amount, adding a small amount of additives, pressure cooking 1.5h, decomposition rate remained stable at around 99%. The resulting crude sodium tungstate solution containing P · As · SiO2 impurities is low, basically achieve the technical requirements after purification. For low molybdenum scheelite by NaF pressure cooking crude sodium tungstate solution can be directly used defluorinated plus molybdenum addition of acid curing agent. Obtained by extraction and crystallization APT quality can be reached international zero Need requirements.


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