真空热还原石灰固化法处理铝电解槽废耐火材料的研究

A study on the treatment of spent refractory materials of aluminum electrolytic cell by vacuum thermal reduction and lime solidification process

铝电解槽大修过程中产生大量的废耐火材料,由于其含有大量的可溶氟化物,是一种危险废弃物.对真空热还原石灰固化法无害化处理铝电解槽废耐火材料的工艺进行研究,通过对真空热还原石灰固化后的物料进行物相与成分分析,研究了处理后物料中氟化物的存在形式和钠元素含量变化.研究结果表明,真空热还原石灰固化过程中,废耐火材料中的98%以上的钠元素被还原为金属钠,处理后的物料中钠元素含量低于0.2%,氟元素主要以不溶于水的氟化钙形式存在,处理后渣的浸出毒性达到了普通固废的要求,可实现废耐火材料的无害化处理.

A large amount of spent refractory materials is generated during the overhaul of aluminum electrolytic cells.The spent refractory materials is a hazardous waste due to the presence of soluble fluorides.In this paper,a harmless process for treating the spent refractory materials by vacuum thermal reduction and lime solidification is studied.The phase and composition of the slag(i.e.,residue after treatment)are analyzed,and the existing form of fluorides and the variation of sodium content are investigated.The results show that more than 98%of the sodium in the spent refractory materials is reduced to metallic sodium,and the content of sodium in the slag is less than 0.2%.In the slag,moreover,fluorides mainly present in the form of insoluble calcium fluoride.The toxicity of the slag therefore meets the requirements of common solid waste,which indicates that the spent refractory materials can be treated by the harmless process based on vacuum thermal reduction and lime solidification.