Effect of Cr-solidified/stabilized Water-quenched Slag on Strength and Leaching Characteristics of Blast Furnace Slag Cement

Abstract

Abstract This article presents an original study into the feasibility of using blast furnace slag and stainless steel pickling sludge to produce solidified/stabilized Cr slag micro-powder and its application in slag cement. A process route for utilizing blast furnace slag to dispose of pickling sludge online is proposed. The characteristics of Cr-solidified/stabilized water-quenched slag and composite slag cement are characterized, and the feasibility and economic viability of preparing mineral slag micro-powder are evaluated. The results demonstrate that the addition of sludge increases the grindability of water-quenched slag, with a specific surface area increasing from 971m²/kg to 1125m²/kg, and a glass phase content reaching 99%. Chromium in the mineral slag micro-powder exists either in solid solution within the glass network structure or in the form of spinel phase, significantly reducing its leaching toxicity. The prepared composite slag cement, with BP5 sample as the highest compression strength of 51.4MPa, achieves an activity index of S105. SEM analysis shows that the cement mortar samples cured for 28 days form a dense gel-like structure with good hydration performance. The leaching concentration of Cr in BP5 is the lowest, only 11.6 ug/L. The evaluation of process feasibility and economics shows that the solidified Cr slag powder prepared by large-scale online disposal of sludge is feasible. It can not only bring direct economic benefits, but also eliminate the environmental threats caused by hazardous waste, reduce energy consumption, and indirectly Reduce carbon emissions.