Synthesis of Mullite from Fly Ash and Alumina Powder Mixture

Synthesis of mullite from fly ash mixed with alumina powder was studied. A suitable fly ash containing small amounts of flux components such as alkali, alkali earth metal and iron oxides and contents of the flux components reduced by pretreatment like magnetic led to separation, a mullite-like material with relatively good quality. When a 1:1 mixture of pretreated fly ash and γ-alumina was heated to above 1673K, 80% mullite yield was achieved. Properties of sintered bodies of mullite powder made from fly ash and γ-alumina were almost comparable to those of a synthetic commercial grade mullite body.