Synthesis of Hydrocalumite-like Compound from Blast Furnace Slag by Alkali Fusion using Waste Molten-Slag Heat, and Its Anion Removal Ability

摘要

Blast furnace (BF) slag is a byproduct of iron- and steel-making plants and is produced by the forced cooling of the 1500°C molten state. The ability to create value-added products from BF slag has become an important sustainability issue. In this study, we converted this slag into a hydrocalumite-like compound capable of removing pollutant ions from water through alkali fusion us?ing the waste heat of the melting slag. The molten slag was transformed into a precursor with reactive phases by alkali fusion at 1500°C, after which the cooled melting slag was crushed and added to dis?tilled water containing NaAlO2 and stirred at room temperature to produce the hydrocalumite-containing product. The effects of the type of alkali salt, the Na2CO3-to-slag mixing ratio (Na2CO3/slag ratio), heating time, amount of added NaAlO2, and the ability of the product to remove certain ions from aqueous solution were examined. Na2CO3 was used to alkali fuse slag at 1500°C, and the optimal conditions for the synthesis of hydrocalumite were found to include a Na2CO3/slag ratio of 2:1, a heating time of more than 10 min, and a 60 g/L concentration of NaAlO2. The product was shown to remove more F~ and PO43~ than BF slag. These results suggest that a hydrocalumite-like adsorbent capable of removing pollutant ions from aqueous solution can be synthesized from BF slag through alkali fusion using waste slag-production heat.