High grade cement made from steelworks slags - by melting with lime in oxygen converter, using lance to heat slag mixt.

摘要

Binders esp. high grade cements are made from waste in metallurgical works, using (by wt.), 60-90% waste and 40-10% lime, melted under oxidising conditions and then quenched to make a granulate which is milled with 3-8% gypsum. The melt is pref. heated to 1600-1750 degrees C., esp. 1650-1700 degrees C.; and 80-100% of the water is pref. blast furnace slag, steelworks slag, and/or other metallurgical waste. The granulate of slag and CaO pref. has a compsn. according to Bogue, of 10-75% tricalcium silicate (C3S); 10-60% C2S; 15-40% brownmillerite (C4AF); 0-10% of either dicalcium ferrite (C2F) or tricalcium aluminate (C3A); and 0-8% remainder. The pref. melting plant consists of a top blown oxygen steelworks converter, in which the slag and CaO are melted using the lance as a burner and also for adding fine materials. Alternatively, a bottom-blown converter may be used, the tuyere being employed for both heating and adding fine material; a Aldo converter may also be used.