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本文介绍了从锡精矿直接制取锡酸钠的工艺流程及某些关键过程的理论研究。对精矿中的SnO_2、SiO_2、Fe_2O_3及FeWO_4等与NaOH反应的热力学进行了计算分析;根据在550—700℃加热30—120分针的条件下,SnO_2转化成Na_2SnO_3的转化率结果,分析计算了反应的速度常数、反应级数及活化能,推测反应是受扩散控制及加热时伴随Na_3SnO_4的生成及分解。对净液脱砷进行了平衡计算分析,提出用锡粉活化脱砷新方法。所得产品完全满足质量要求,精矿中锡总回收率达90—95％。
This paper introduces the technological process of preparing sodium stannate directly from tin concentrate and the theoretical research of some key processes. The thermodynamics of reaction of SnO_2, SiO_2, Fe_2O_3 and FeWO_4 with NaOH in the concentrate were calculated and analyzed. According to the result of conversion of SnO_2 to Na_2SnO_3 under the condition of heating 30-120 minutes at 550-700 ℃, The reaction rate constant, reaction order and activation energy are presumed to be caused by diffusion control and heating with the formation and decomposition of Na 3 SnO 4. Arsenic balance of net solution was calculated and analyzed. A new method of activating arsenic removal with tin powder was proposed. The resulting product fully meet the quality requirements, the total recovery of tin concentrate 90-95%.