Study On Preparation Of Sodium Stannate From Cassiterite Concentrate By Soda Roasting-Leaching Process

Sodium stannate is a tin-containing inorganic compound which is widely used in electroplating industry and tin alloy production. At present it is usually made from sodium hydroxide,but the preparation process is characterized by high cost, strict demand for the equipment and unsafe. In order to solve the shortage of the preparation,A novel made from sodium stannate from Cassiterite concentrate and soda which roasted in the medium of CO/CO2and water leaching was researched in this study. The article identfies thermodynamic and phase transformation of cassiterite concentrate soda roasting, and discusses reaction course of tin dioxide soda roasting.According to the research of the preparation of Sodium Stannate from Cassiterite Concentrate by Soda Roasting-Leaching, appropriate roasting parameters are acquired as the following:the content of CO is15%,the mole ratio of Na2CO3/SnO2is1.5,the roasting temperature is875℃,the roasting time is20min. the roasting product is Leached in0.05mol/L sodium hydroxide solution under the water bath, ppropriate leaching parameters are acquired:the liqiud solid ratio is4,the leaching temperature is40℃,the leaching time is3.5h,the mixing speed is300r/min. the leaching of Sn could be75.16%under the optimal conditions.The produch of sodium stannate purity meet the requirements of industrial product.The mechanism of tin doxide soda roasted which in the CO/CO2reduction system has showed that the reaction of tin doxide soda roasting is spontaneous, and it is priority to the reduction reaction of tin doxide.it is significant of the effect of the CO content and roasting temperature on the phrase composition of rosting product, when the CO content is15%-20%and roasting temperature is875℃,most of the product is sodium stannate, the lattice parameter of a and c values of tin doxide crystal which roased in CO/CO2reduction atmosphere are bigger than those roasted in doxide atmosphere.it indicates that the CO/CO2gas can reduce the activation energy of the reaction between tin dioxide and sodium carbonate, therefore accelerate the speed of the reaction between tin dioxide and sodium carbonate.