Preparation and Application of Ceramic Membranes for Hot Metallurgical Gas Cleaning

Alumina-based ceramic filtration membranes were prepared on a large-pore silicon carbide supports using alumina and mullite particles as the raw materials by spray-coating, followed by dip-coating for modification. The preparation process, including the powder pre-treatment, the formation and sintering of membranes, was systematically studied. Optimization of the raw materials ratio was found to be necessary to avoid crack forming during sintering and application. The microstructure, pore properties and gas permeation flux of prepared membranes were investigated. The preferred sintering temperature for the membranes was in the range of 1190–1220 °C based on the results of SEM, pore-structure and pressure drop. Low cost alumina-based membrane tubes with average pore size 6.7μm and pressure drop of 470Pa under the filtration velocity of 1 m/s were obtained. The length, outer diameter, and wall thickness of the membrane tubes were 1600mm, 60 mm and 10 mm, respectively. A dust filter equipped with 1760 resulting membrane tubes (capacity:45000Nm³/h) was built at Huaian Special Steels (East China) to clean metallurgical sintering flue gas. Efficiencies of filtration of sintering flue gas were found to be greater than 99.95% which gave rise to very low dust content in the outlet fume gas (<10 mg/Nm³). These results make the ceramic membrane filter very promising for hot and corrosive industrial exhaust gas filtration applications.