Study On Comprehensive Utilization Of Chromium Aluminum Mud

Chromium salt plays an indispensable role in the national economy and its demand increases year by year. Aluminum residue containing chromate is the main solid waste, and quite a few virulent Cr6+exists in the form of Na2 Cr O4 or combined with other components in the aluminum mud,so it must be innocent treatment before discharge.The research and development of comprehensive utilization of aluminum residue containing chromate can not only greaty increase the economic benefits of aluminum residue, but also realize the protection of environment.This paper takes aluminum residue from a chromium salt factory in Chongqing as raw materials, put forward a set of process route of comprehensive utilization of aluminum residue on the basis of experiment.First most soluble hexavalent chromium salts was separated by washing,which makes the content of hexavalent chromium reduce to less than 5%. And then use the method of electrodialysis,namely applying an electric field at the ends of aluminum sludge containing chromium, using the migration force of electric field to pull out sodium chromate from aluminium migration in the mud, by this method the content of sodium chromate can be reduced to to 1% or less. The remaining 1% of the hexavalent chromium is mainly combined state, a reducing agent was used to restore it as a non-toxic trivalent chromium.Chrome aluminum mud after detoxification was used to isolate the trivalent aluminium and produce high purity alumina,and the remaining mud was returned device to recycle.In this paper,we explored optimization of the following experiment processes: dechromisation by washing、dechromisation by electrodialysis method、restoring and extracting aluminum metal by alkaline leaching etc;In the process of extraction of trivalent aluminium, the effects of caustic concentration, temperature and reaction time on the Al(OH)3 leaching rate was studied respectively. In the proess of carbonation decomposition,highly pure Al2O3 was obtained by controlling the decomposition temperature, the amount of additive, stirring speed and other conditions.