New Technology For Short Process Preparation Of Tungsten Carbide By Scheelite Resources

In industry,tungsten smelting process is long and has high energy consumption.Any method that can shorten the preparation process from tungsten ore to WC will be a technological progress.In this paper,the intermediate product scheelite（CaWO₄）in the leaching process of tungsten ore was used as the experimental raw material,and the steps for preparing APT by ammonia dissolution were omitted to shorten the preparation process of tungsten carbide.In the first part,scheelite（CaWO₄）was decomposed by nitric acid,and a small amount of organic surfactant was added in the process,then tungsten carbide was prepared by direct carbonization.The effects of separation and retention of Ca and addition of organic surfactant on the morphology and particle size of tungsten carbide were studied.In the second part,scheelite（CaWO₄）was leached by mechanochemical method,and then tungsten carbide was prepared by hydrogen reduction,carbonization and direct carbonization,respectively.The morphology,particle size and other characteristics were studied.Yttrium was added to prepare WC powder containing yttrium,and the effect of yttrium on the preparation process of tungsten carbide was studied.The main conclusions of the study are as follows:（1）Scheelite（CaWO₄）was decomposed by nitric acid.After filtration and separation of Ca,the WC particles were coarse,and the average particle size was about0.94μm.The tungsten carbide particles obtained by carbonization and pickling after calcium retention are relatively small,and the average particle size is about 0.31μm.After adding an appropriate amount of organic surfactant in the process of nitric acid decomposition,the encapsulation effect of organic surfactant hindered the growth of tungstic acid to a certain extent.The primary particle size of WO₃ prepared after calcination was significantly smaller than that of the sample without adding organic matter,and more uniform and finer WC was obtained after carbonization.Adding organic surfactant b has the best effect.After adding organic surfactant b,the average particle size of WC prepared by filtration and separation of Ca carbonization is about0.67μm,and the particle size distribution is 0.45-1.0μm.The average particle size of WC particles prepared after Ca retention carbonization and pickling was about 0.19μm,and the particle size distribution was 0.10-0.30μm.（2）After oxalic acid leaching of scheelite（CaWO₄）,the average particle size of WC prepared by direct carbonization is about 0.36μm,which is smaller than that of WC prepared by hydrogen reduction and carbonization（0.79μm）.The WC particles prepared by adding appropriate amount of Y（NO₃）₃·6H₂O into the leaching tungsten complex solution are smaller.When the addition amount of Y was 0.1wt%,the average particle size of WC prepared by hydrogen reduction and carbonization was about0.31μm,and the average particle size of WC prepared by direct carbonization was about 0.18μm.