Pressurized Steam Aging Process for Steel Slag

摘要

Steel slag has hydraulic property and becomes rigid; it is useful for roadbed material. On the other hand, unprocessed steel slag generally includes unmelted quicklime (CaO). CaO expands when it reacts with water. The unprocessed slag is not used for an industrial product immediately. Steel slag needs aging treatment before used as roadbed material. Through aging, steel slag certainly hydrates with water and then it finishes expansion completely. A primal aging stores steel slag under natural atmosphere at open yard for two years. An open yard steam aging accelerates reaction but it still needs a few days. Anyway, both need a longer process time, a wider yard and manpower. Sumitomo Metals has developed pressurized steam aging process; it can reduce the conventional aging time dramatically. This process carries out hydration under pressurized steamy atmosphere, it increases reaction speed 24 times higher than that of the open yard steam aging and shortens aging time to only two hours. Equipment of this process needs a small installation space. Because of the fully automatic process, it reduces labor cost and energy consumption. The most remarkable merit is enhancing stability of product quality by uniform reaction. This process has been operated stably for more than ten years at Wakayama steelworks.