Preparation of Ultrafine Aluminum Hydroxide from Coal Fly Ash by Alkali Dissolution Process

摘要

A new two-step alkali dissolution technique was used to prepare ultrafine aluminum hydroxide from coal fly ash in this study. The first step alkali dissolution was to leach SiO_2 from the coal fly ash using sodium hydroxide solution for obtaining the desilicated product with higher Al_2O_3/SiO_2 ratio. The leaching efficiency of SiO_2 reached to 40% when the coal fly ash was leached with 8 M sodium hydroxide solution at 95° C for 150 min. The second step alkali dissolution was that the mixtures of the as-desilicated product and white lime were leached with 20 M sodium hydroxide solution at 260° C for 60 min for extracting alumina from the desilicated product.