Production of Calcium Tungstate by Corrosion Reaction Synthesis

We attempted to produce calcium tungstate (CaWO4) using metal corrosion reaction, and compared it with that produced by solid-state reaction. Tungsten corroded in hydrogen peroxide containing ammonia and eventually dissolved completely. When calcium was added to this solution, the calcium corrosion reaction proceeded easily without the addition of a corrosion-accelerating substance. Oxide powder was obtained by drying and calcinating the above mixed solution. It was identified that the powder which was calcinated at 973 K was CaWO4 and the particle size was 1.8 ~ 18.5 μⅿ. In the case of the solid-state reaction method using tungsten oxide and calcium carbonate as raw materials, CaWO4 powder with particle sizes ranging from 0.4 μⅿ to 22.0 μⅿ was synthesized at 1173 K.