High-alumina cement production from FeNi-ERF slag, limestone and diasporic bauxite E. Dourdounis a , V. Stivanakis a , G.N. Angelopoulos a , E. Chaniotakis b , E. Frogoudakis c , D. Papanastasiou d , D.C. Papamantellos a, * a Laboratory of Metallurgy, Chemical Engineering Department, School of Engineering, University of Patras, Karatheodori 1, 26500 Patras, Greece b Department of Research and Development, Titan Cement Company SA, Kamari Plant Viotias, P.O. Box, 19200 Elefsis, Greece c GMMSA LARCO, Amalias 20 and Souri 5, 10557, Athens, Greece d Silver and Baryte Ores Mining Co. S.A., 21A Amerikis Street, 106 72, Athens, Greece Received 6 December 2001; accepted 2 November 2003 Abstract In this paper the utilization of ferronickel electroreduction furnace (FeNi-ERF) slag for the production of high-alumina cement (HAC) is investigated through laboratory and pilot-scale tests. The process followed consisted of smelting reduction of slag mixtures with low-grade diasporic bauxite and limestone. In the laboratory-scale trials the main process parameters were defined, concerning raw material proportions, kinetics of the reductions and cooling rate of the product. The presence of a carbon-containing iron bath enhances FeO x reduction from the slag. Products from laboratory tests developed satisfactory compressive strengths relative to those of commercial HAC. According to the results of the laboratory tests, pilot-scale heat treatments were carried out in a 5-t electric arc furnace (EAF) and about 4 t of final mixture were produced. D 2004 Elsevier Ltd. All rights reserved. Keywords: ERF slag; Waste management; Cement manufacture; Calcium aluminate cement 1. Introduction Ferronickel (FeNi; 100 kt/y, Ni 20% wt) and alumina/ aluminium (750 and 160 kt/y, respectively) are among the main industrial products of Greece. The production of FeNi leads to ‘‘metallurgical wastes’’ at LARCO in Larymna of about 2000 kt/y of ERF slag, 180 kt/y rotary kiln gas- cleaning-system dust and 120 kt/y converter slag. Alumin- ium production, on the other hand, is related with the production of about 600 kt/y red mud and other by-products from bauxite beneficiation prior to its refining into alumina. The most important contribution in the recycling of these wastes is made by the local cement industries, which are using about 25% of the above-mentioned slags in the production of Portland cement. However, increased indus- trial production during the last few years and at the same time the implementation of new environmental legislation forces the respective metallurgical industries to find either new applications or better disposal solutions for their generated residues other than depositing them in the North Euboian and Corinthian Bay. Two principal methods are used today for the manufac- ture of high-alumina cement (HAC); one is sintering, as in the case of Portland cement manufacture, and the other, most widespread method, is fusion. The latter may be subdivided into [1,2] the following: (1) Continuous fusion method, originally, the blast furnace/ cupola process (with replacement of iron burden/scrap with bauxite in the raw feed but in the presence of coke, i.e., under reducing conditions) and, mainly today, the L-type furnace or Lafarge process [2,3] (with propor- tional amounts of bauxite and limestone charged into the vertical part and fuel injected in the horizontal one, i.e., under oxidizing conditions). (2) Batch smelting method, using electric arc furnaces (EAFs), as in the case of ferroalloy production. In this paper, a new process for the production of HAC from FeNi-ERF slag, low-grade diasporic bauxite 0008-8846/$ – see front matter D 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.cemconres.2003.11.004 * Corresponding author. Fax: +30-61-990917. E-mail address: pap@chemeng.upatras.gr (D.C. Papamantellos). Cement and Concrete Research 34 (2004) 941 – 947