Modification of steelmaking slag by additions of salts from aluminum production

Abstract

The most common slag fluidizer in steelmaking is fluorspar, a mineral primarily composed of CaF2. Because of increasing consumption and decreasing availability of cheap fluorspar, steelmakers are seeking alternative means of achieving slag fluidity. One possible alternative to fluorspar is spent salt from secondary aluminum production. This salt is obtained from the used flux in remelting aluminum scrap and dross. This material is widely available and considered toxic (meaning that use in steelmaking helps to reduce environmental impacts from diposal). This project is an investigation of spent salt as a replacement for fluorspar in slag-fluidizing applications by viscosity measurements and weight loss measurements at high temperatures (to evaluate the amounts of gases are formed). In addition, characterization of raw materials and melted slags by XRD, chemical analysis, and EPMA have been undertaken. The spent salt addition has a positive effect on slag fluidity, and shows promise for use in slags.