The investigation of dissolution behavior of gangue materials during the dissolution of scheelite concentrate in oxalic acid solution

Abstract Scheelite mineral which includes CaWO 4 as a main compound is one of the most important raw materials used for the industrial production of W. Scheelite concentrate used in this study included CaMoO 4 and the oxides of Fe, Ca, Si, P, Al, Mn, S, Zn, Mg, Ba, K, Ti and Sr as gangue materials. CaWO 4 reacts with oxalic acid (H 2 C 2 O 4 ) to form water-soluble hydrogen aqua oxalato tungstate (H 2 [WO 3 (C 2 O 4 )H 2 O]) and insoluble calcium oxalate monohydrate (CaC 2 O 4 H 2 O). Additionally, the dissolution behavior of gangue materials during the leaching of the scheelite concentrate in H 2 C 2 O 4 solution must be known for the designing of the purification process applied in the industrial production of pure W. The aim of this study was to investigate the effects of temperature and H 2 C 2 O 4 concentration on the dissolution of gangue materials in the scheelite concentrate. It was found that while the oxides of Si, P, Al, S, Zn, Ba, K, Ti and Sr were not dissolved in H 2 C 2 O 4 solution, the oxides of Ca, Mo, Fe and Mn were dissolved forming complex oxalate ions. MgC 2 O 4 which was formed from MgO in the scheelite concentrate was also dissolved due to its high solubility.