The Formation of Sodium Stannate from Mineral Cassiterite by the Alkaline Decomposition Process with Sodium Carbonate (Na₂CO₃)

Extraction of cassiterite using alkaline decomposition of sodium carbonate (Na₂CO₃) has been studied. Cassiterite (SnO₂) is a mineral ore that contains tin (Sn) about 57.82 wt% and impurities like quartz, ilmenite, monazite, rutile and zircon. The initial step for the process was to remove the impurities in cassiterite through washing and separation by a high magnetic separator (HTS). The aim of this research is to increase the added value of cassiterite from local area Indonesia that using alkaline decomposition to form sodium stannate (Na₂SnO₃). The result shows that cassiterite from Indonesia can form sodium stannate (Na₂SnO₃) which soluble with water in the leaching process. The longer the time for decomposition, the more phases of sodium stannate that will be formed. Optimum result reached when the decomposition process was done in 850 °C for 4 hours with a mole ratio Na₂CO₃ to cassiterite 3:2. High Score Plus (HSP) was used in this research to analyze the mass of sodium stannate (Na₂SnO₃). HSP analysis showed that mass of sodium stannate (Na₂SnO₃) is 70.3 wt%.