芒硝制纯碱和硫酸新工艺探讨

Novel process for manufacturing soda ash and sulfuric acid from sodium sulfate

我国芒硝储量世界第一 ,大部分位于欠发达的西部地区 ,芒硝还是许多工业过程的副产物 ,大多含有环境污染物 .芒硝本身利用价值低 ,市场容量小 ,开发新的利用途径具有重要意义 .提出了一种芒硝制纯碱和硫酸的新工艺 ,它是以氧化钙和重铬酸钠水溶液为转化介质 ,硫酸钠先和氧化钙在重铬酸钠水溶液中反应 ,得到硫酸钙沉淀和铬酸钠水溶液 ,前者高温还原分解再生氧化钙 ,同时得到二氧化硫和二氧化碳 ,二氧化硫经转化吸收得硫酸 ;后者和二氧化碳反应再生重铬酸钠水溶液 ,同时得到碳酸氢钠沉淀 ,碳酸氢钠经脱铬处理制得纯碱 .该工艺借鉴了工业上成熟的石膏分解制硫酸技术和铬酸钠碳化制重铬酸钠技术 ,具有成本低、腐蚀轻、无废物排放等特点 ,有望为我国丰富的芒硝资源开辟新的应用途径 .

China has the richest resource of sodium sulfate in the world, mostly located in its undeveloped western area. Sodium sulfate is also a byproduct of many industrial processes, mostly containing pollutants. The market capacity of sodium sulfate is limited and its economics is poor. Therefore, it is important to develop a new process to utilize sodium sulfate economically. A novel process for manufacturing soda ash and sulfuric acid from sodium sulfate is presented in this paper. It uses calcium oxide and aqueous sodium dichromate solution as a working medium and consists of the following reactions. Reaction of sodium sulfate and calcium oxide in aqueous sodium dichromate solution to get calcium sulfate precipitate and aqueous sodium chromate solution; reduction and decomposition of calcium sulfate to regenerate calcium oxide and get sulfur dioxide; transformation of sulfur dioxide to produce sulfuric acid; carbonation of aqueous sodium chromate solution to regenerate sodium dichromate and get sodium bicarbonate precipitate; removal of chromate from sodium bicarbonate and production of sodium carbonate. The process has the features of low cost, little corrosion and pollution. Hopefully it would become a new way to utilize sodium sulfate.