Improvements to the Waelz process for the treatment of dusts in steel mills

摘要

Improvements to the Waelz process for the treatment of dusts in steel mills.It is a modification of the Waelz process, with improvement of the quality of resulting products, slag and oxide Waelz relative to the minimum contents of halogens (0.01%), especially fluorine. Firstly, the raw material is reduced to pellets with crushed coal or coke, small additions of silica and sulphurous products if the raw material does not contain any. In the oil or pulverized coal furnace it reaches a temperature above 1200 degrees C with excess of air introduced in the part opposite the entrance of pellets, with sulphur, so as to create an atmosphere of SO2 that is able to react with the fluorides carried by the gases, forming HF that will fix on the ZnO collected. Finally, the ZnF2 and ZnCl2 fixed onto the particles of ZnO will be transformed into soluble alkaline salts by washing with a solution of sodium carbonate.