Process for treating molten steel slag with red mud from aluminum industry

A process for treating slag from known converter and electric furnaces to improve the structural stability of such slag and render such slag suitable such as a landfill and construction material as well as a substitute for base material or crushed stone for road construction, comprising the steps of:

• (1) providing molten slag produced from a conventional converter or electric furnace in which the furnace is used in conventional steel production and wherein the molten slag when cooled contains Free CaO and 2CaO.SiO.sub.2 which render such cooled slag unsuitable for landfill purposes due to swelling and structural instability of the Free CaO and 2CaO.SiO.sub.2 therein,
• (2) adding red mud obtained as a by-product from the aluminum industry to the molten slag thereby creating a thermochemical reaction between the red mud and the molten slag to transform a composition of said cooled slag containing the Free CaO and 2CaO.SiO.sub.2 to a relatively non-swelling and non-crumbling composition, said red mud accounting for 5 to 20 percent of said molten slag after the addition of said red mud, said red mud comprising as a major component Fe.sub.2 O.sub.3 and as a lesser component Na.sub.2 O, said red mud melting at a temperature lower than the melting temperature of said slag, and
• (3) utilizing the heat value of the molten slag to melt said red mud into said molten slag and cause said thermo-chemical reaction, whereby the thus processed cooled slag has structural ability rendering it suitable as a landfill.