Laboratory testing of the use of phosphate-coating sludge in cement clinker

Abstract The present work studies, in a laboratory apparatus, the co-processing of phosphating coating process sludge in the process of clinker production. A mixture of raw clinker materials and increasing concentrations of phosphating sludge produced the samples analysed. These mixtures were burned at 1450°C for 10 min in an electric furnace. The sludge used basically contained water, ferrous and zinc phosphates, apart from minor elements such as Na, K, S, Pb, Cr and Cu. The raw meal used was obtained in a Brazilian cement plant. The results showed no damage to the clinkerization process with an addition of up to 7.0% sludge. The formation of atypical phases was not observed with additions of up to 5.0%. The major element of the sludge, zinc, shows an average of incorporation of 75%.