Synthesis of aluminum ammonium sulfate from waste aluminum processing solution by crystallization

Experimental tests were conducted in the present study to investigate synth esis of aluminum ammonium sulfate (aluminum alum) by crystallization from t he waste acid solution of aluminum surface finishing industry. Effects of v arious operating conditions including the molar ratio of ammonia and alumin um ion, temperature, mixer speed, seed alum dosage, initial sulfuric acid a nd aluminum ion concentrations on the aluminum alum formation, crystal size distribution, acid remaining and aluminum ion removal were examined. The c rystallization process was found to be quite effective in recovering resour ce materials (sulfuric acid and aluminum) in the form of aluminum alum from the waste acid solution. Based on the test results, optimum operating cond itions were recommended for efficient operation of the crystallization proc ess. (C) 1998 Elsevier Science B.V. All rights reserved.