Converting molten blast furnace slag to Portland cement - by feeding slag, lime and iron oxide into rotary drum furnace

摘要

Slag is recovered from a blast furnace in a molten or softened state; and fine lime is added to the slag to produce portland cement. The lime is pref. added in a carrier, e.g. a slag obtd. during sulphur removal via lime or calcium carbide; and ferrous prods. are pref. added so the cement contains 2-5% iron. The lime, its carriers, and/or the ferrous materials may be suspended in a carrier gas for injection into the blast furnace slag, esp. using gas from a burner fed with an oxidant, possible pure O2, and a fuel gas, e.g. natural gas fed through an outer annulus surrounding an axial stream of air or O2. The powdered addns. and their carrier gas may be fed into a molten stream of slag leaving a blast furnace. Pref. the molten slag flows from the blast furnace down a launder and into an inclined rotary drum furnace fitted with feeders for the addn. of the lime etc.