Sec Law Stripping To Reduce Alkali Consumption Of Red Mud

Our country is abundant in bauxite which has the property of high-alumina content and high-silica content. High content of silica results in the problem of high soda consumption, which limits the use of high-silica bauxite. So it is of great significance for the efficient use of high silica content bauxite in our country to develop a process that can reduce soda consumption in the alumina production.In order to reduce soda consumption in digestion of high silica content bauxite,a low fixed soda desilication products is produced by means of modifying the digestion process.And the two-stage digestion process is a new method to reduce soda consumption of red mud by producing low fixed soda desilication products.The process contains two stages, the predesilication stage and the digestion stage. In the predesilication stage, bauxite was predesilicated with high ak and high alkali soda content solution, after that, in the digestion stage, bauxite was digested with concentrated spent liquor.The predesilication property of Guizhou bauxite was investigated in this paper at first.And the digestion conditions of the two stage digestion process for Guizhou bauxite were also optimized. The result showed that in the optimal conditions of the two stage digestion, the N/S of red mud of Guizhou bauxite reached the lowest value:0.36.In addition, it was found that N/S of red mud showed different value when using the two stage digestion process to digest Pingguo bauxite in the autoclave and steel bomb.And the reasons were discussed in this paper. The results illustrated that there were two reasons resulted in the difference. At first, the rubbing effect of steel balls in the steel bomb favored reducing the soda consumption of red mud; secondly, the predesilication effect of Pingguo bauxite in autoclave was not as good as that in steel bomb. And then, the results of digesting roasted Pingguo bauxite in autoclave with the two stage digestion process showed that by roasting Pingguo bauxite and using the two stage digestion process, the N/S of red mud of Pingguo bauxite could be reduced to 0.26,which meant that the two-stage digestion process could reduce the soda consumption of red mud of Pingguo bauxite.In the end, the optimum experimental conditions for the chemical phase analysis of red mud were obtained in this paper. And the chemical phase analysis of red mud which produced from the predesilication stage of the two stage digestion was carried out.The results indicated that in the two stage digestion process, the content of low fixed soda desilication products of red mud could be increased by increasing the ak of aluminate solution in the predesilication stage.