Abstract: Based on the physical and chemical characteristics of the sulfuric acid residue from a sulfuric acid manufacture in the west of Guangdong Province, a flow sheet was developed with sieve classification, gravity concentration and pyrite flotation as well as coagulant making by chemical aggregation from light fraction of gravity separation. A result of 18.61% admixture for cement slurry, 49.76% iron ore concentrate with a grade of 63%Fe and coagulant for waste water treatment had been obtained from the slag by applying a new process. The rate of slag recycling was up to 98.23% leaving only little waste, and thus the pollution caused in the area was controlled. The removal rate of CODcr was 93% when the developed coagulant was used in the treating petrochemical waste water.