PROCESSING OF MULLITE AND MULLITE-BASED CERAMIC COMPOSITES FROM METAL WASTES AND BY-PRODUCTS OF MINING

The present work is part of a wide investigation on processing of mullite and mullite-based ceramic composites from Al metal wastes and waste by-products of mining tin ores with high kaolinite content. The Al wastes were dissolved in acid solution, mixed with aqueous suspension of kaolinite and precipitated the oxy-hydroxide using two alkaline bases. Kaolinite and α-alumina mixtures were also used to compare the results. Porous mullite and mullite-based composites (52-45 vol %) can be obtained by firing some precursors at 1500-1600 ºC for 120-30 min. They have interesting potential applications, such as ceramic substrates, refractories, filters and thermal barriers. The method has implications for the recovery and recycling of Al wastes, besides the application of waste by-products of mining as valuable raw ceramic materials