Synthesis of scheelite with wolframite and calcium carbonate by a direct solid-state synthesis route

• Scheelite was successfully prepared by solid-state calcination synthesis in air atmosphere.
• Effects of processing parameters on the conversion ratio of wolframite were presented.
• Optimal processing parameters in the process of synthesizing scheelite were selected.

Scheelite was successfully prepared by solid-state calcination synthesis using wolframite [(Fe,Mn)WO4] and calcium carbonate as materials in air atmosphere. The effects of processing parameters, such as calcination temperature, holding time and calcium carbonate dosage on conversion ratio of wolframite were investigated. The conversion of wolframite increased with increasing of temperature, holding time and calcium carbonate dosage. The results demonstrated that 97.58% of wolframite was converted to scheelite in 2 h at temperature of 800 °C under the condition of calcium carbonate stoichiometric ratio of 1.3, and the corresponding reaction products are scheelite, iron oxide and manganese dioxide.