Preparation of Ceramic Membrane Filters Suitable for Hot Gas Cleaning from Waste Fly Ash
The preparation and performance of ceramic membrane filters made from fly ash from coal-fired power stations were investigated. The porous and crack-free ceramic composite membrane was prepared by dip-coating a stainless steel mesh in a slurry of fly ash. Membrane properties investigated included pore structure, permeability and mechanical strength. The ash membrane filter shows great potential for the filtration and microfiltration of high-temperature gas-particulate streams, and reuses waste fly ash composed of multiple oxides with a wide size distribution. The median pore size of the tested membrane was 2.3 μm and the differential pressure gradient was 0.9 kPa 1-1 min-1, which is comparable to fabric filters currently in use in some New South Wales power stations. The high mechanical strength of the membrane was caused by fusion of the glassy material in the fly ash. Since the membrane consists of metal and ceramic composities, it also shows good flexibility.