Process for extracting tungsten from scheelite

摘要

A method is provided for extracting tungsten from scheelite. This comprises: introducing mixed acid consisting of sulfuric acid and phosphoric acid into a decomposition reactor, heating to 70-100 ° C and then adding scheelite, maintaining the solid-liquid ratio at 3: 1-8: 1 L / kg, filters 1-6 the reaction, crystallizing the recovered filtrate, which is compensated with sulfuric acid consumed by the reaction to recover a phosphotungstic acid crystal, dissolving the phosphotungstic acid crystal in water and transforming it to obtain an ammonium tungstate solution, with 200- 300 g / L WO3, which is used to make the APW, while the recovered mother liquor crystal is returned to an initial level for ore leaching after compensating for phosphoric acid and water. The invention avoids phosphorus removal reagent cost and loss of tungsten, is capable of leaching scheelite at atmospheric pressure and overcomes problems such as Cl corrosion and strong volatilization of HCl in the traditional acid decomposition process, generally realizes and greatly reduces phosphoric acid recycling Cost of leaching and the quantity of waste water discharge, and has a short course and appropriate operation of the method, and is suitable for industrial application.