Preparation Of Porous Ceramic Membranes & Their Application In Hot Gas-Solid Separation

It has been a major duty to develop proper techniques for the removal of dusts in hot gases and the collection of ultra-fine ceramic powders made by chemical processes. The ceramic filters based on porous ceramic membranes appear the right solution as they have showed high efficiency of duct removal, high thermal shock resistance, long life and lower operation expense as well as none secondary pollution.Recently, there are many achievements on ceramic filters, but some disadvantages limit their wider applications, such as expensive starting materials and complex preparation process.This thesis aims to develop some ceramic filters made from low cost porous ceramic membranes for de-dust and the collection of the ultra-fine solid particles from hot gaseous ambient. Mullite and cordierite porous ceramic membrane materials from waste fly ash were prepared and characterized. The thesis includes the following sections:1. Preparation of porous ceramic membranes with mullite as major phase from waste fly ashPorous ceramics with mullite as major phase exhibit good strength and thermal shock resistance, and they has been used as the ceramics filters of high temperature de-dusting and dust-collecting. In traditional fabrication process, the starting powders are first synthesized, and then a slurry is made to prepare membranes on a macro-porous support. Both expensive starting materials and the rather high heat treatment temperature will lead to high cost that limited the large scale applications. In this work we have developed an one step preparation process of the ceramic materials with mullite as major phase by using the waste fly ash as raw material. Effects of additives and sintering temperature on porosity, pore structure, phase structure and strength of porous ceramic specimens were studied. It is discovered that solid sintering and reaction sintering were the main sintering mechanism. The mean pore size, porosity and N₂ permeability is 3.72μm, 51.2%, and 1.4×l0⁴m³m^-2h^-1bar^-1 for specimens with starch content of 20% respectively. It can get bigger if more starch...