Determination of Cu and Ni incorporation ratios in Portland cement clinker P.G. Ract, D.C.R. Espinosa, J.A.S. Teno´rio* Department of Metallurgical and Materials Engineering, University of Sa ˜o Paulo. Av. Prof. Mello Moraes 2463, Sa ˜o Paulo-SP, 05508-900, Brazil Abstract Cu and Ni are metals found in galvanic sludges; these sludges are considered hazardous due to their heavy metal content. The main objective of this work is to determine the incorporation amount of Cu and Ni in Portland clinker when a galvanic sludge containing these metals is added to the clinker raw-material. The influence of this addition on the clinkering reactions is evaluated as well as the possibility of co-incinerating galvanic sludges containing Cu and Ni in rotary cement kilns. This study also char- acterizes the galvanic sludge. Samples were prepared by additions from 0.25 to 5 wt.% of a galvanic sludge to an industrial clinker raw-material. The clinkering process was simulated in a laboratory device. The following techniques were applied to characterize the raw materials and the products of the tests: chemical analysis, differential thermal analysis (DTA) and thermogravimetric ana- lysis (TG). Leaching tests were performed in the produced clinker samples in order to verify the incorporation of the studied metals in the clinker structure. The results led to the conclusion that additions of up to 2 wt.% of a galvanic sludge containing 2.4 wt.%Cu and 1.2 wt.% Ni to clinker raw-material do not affect the clinkering reactions and that these metals are totally incorporated into the clinker. # 2002 Elsevier Science Ltd. All rights reserved. 1. Introduction This work studies the possibility of co-incinerating a galvanic sludge containing Cu and Ni along with Port- land cement clinker. A laboratory device was assembled to simulate the thermal cycle imposed to the clinker raw-material during the burning process. The incor- poration percentages of Cu and Ni are evaluated as well as the influence of additions of this galvanic sludge on the clinkering reactions. The co-incineration technique consists of partial sub- stitution of raw material or fuel for waste in a high temperature industrial process in such a manner that the waste is destroyed, the generated ash is incorporated in the product, and the product quality is not affected (Pollmann et al., 1996; Conselho Nacional De Meio Ambiente, 1999). Therefore, the co-incineration process provides an economy to the process in addition to pro- viding a hazardous waste treatment method. Some industrial furnaces have similar features to hazardous wastes incinerators, including calcination furnaces, rotary cement kilns, blast furnaces and some metal- refining furnaces (Theodore and Reynolds, 1987). Brazilian law establishes two classes of waste that can be co-incinerated in an industrial process: wastes that can partially substitute for raw material or fuel. Waste might partially substitute for raw material if the waste has similar characteristics to a commonly used raw material, i.e. the waste must react with the other raw materials generating suitable products for clinker formation. Waste might also be used as a fuel partial substitute; in this case an energy surplus must be proved (Conselho Nacional De Meio Ambiente, 1999). Rotary cement kilns and rotary incinerators have similar features. However, in making a comparison between them one can verify that the first have advan- tages concerning waste treatment, since for clinker pro- duction the furnace achieves approximately 2000  C and provides a longer residence time at high temperature (Oliveria et al., 1996). These characteristics are inherent in clinker production process and end up ensuring the waste’s destruction and/or incorporation into the clin- ker structure (Lin et al., 1993). Furthermore, the pro- duct of an incinerator is ash that contains heavy metals 0956-053X/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved. PII: S0956-053X(02)00061-2 Waste Management 23 (2003) 281–285 www.elsevier.com/locate/wasman * Corresponding author.