Preparation of HCl Gas Scavenger from Blast Furnace Slag through Alkali Fusion

Abstract

Blast furnace (BF) slag, one of the byproducts of iron- and steel-making plants, was converted to a product, including a hydrogrossular, through the alkali fusion method for HCl gas removal. BF slag was transformed to the alkali-fused slag with reactive phases via alkali fusion, and then, the fused slag was added to distilled water and stirred at room temperature to prepare the precursor for the synthesis of the product including a hydrogrossular by heating. The effects of the mixing ratio of NaOH to slag (NaOH/slag ratio), fusion temperature, ratio of the fused slag mass to distilled water volume (W/V ratio), stirring time, heating time, and heating temperature of the product phase were investigated, and the HCl gas removal ability of the obtained product was determined. The optimal conditions for hydrogrossular synthesis are NaOH/slag ratio of 1.6, fusion temperature of 600°C, W/V ratio of 125 g/L, stirring time of 24 h, heating temperature of 80°C, and heating time of 3–6 h. The product removed more HCl gas than the BF slag and showed higher Cl fixation than lime. These results suggest that a novel scavenger for HCl gas removal at high temperature can be synthesized from the BF slag through alkali fusion.