Research On Suspension Rapid Calcining Kaolin From Coal Gangue

In this paper, experiments on spension rapid calcining kaolin from coal gangue were carried out based on analyzing the disadvantages of traditional kaolin calcining technologies (such as fixed bed process, moving bed process and fludized bed process). The effects of particle size of raw material, calcining temperature and time on the quality of calcined kaolin, such as brightness, activity and oil absorption, were investigated. With the consideration of the above effects, a set of optimal process parameters of suspension calcining process were determined. At last, the feasibility of the suspension calcination was proved based on the comparison between the indices of products from suspension calcining process and lump calcining process.The results shows that the suspension calcining process is feasible and can produce higher quality products with higher brightness (beyond ninety percents), higher porosity and better activity. With the increase of temperature, the brightness of calcined product is improved remarkably, and the activity of calcined product is notably enhanced in some temperature range but decreased beyond a certain temperature. The change of temperature has no effect on oil absorption. With calcining time increasing, the brightness of calcined product is increased significantly within certain range and then become stable, the activity of calcined product is also increased within certain range but decreased after a certain time, and the oil absorption changes very little. With the size of particles enlarged, the indices of brightness, activity and oil absorption of calcined product all declined. As the result, smaller particle size of raw material and well controlling of calcining temperature and time provide perfect quality of products.With the coal gangue from Inner Mongolia, the perfect performance could be achieved by calcining the raw material (mean particle size is 22.22μm) at 1000°C for 10 minutes. The ideal product indices are of the brightness beyond ninety percent, activity of 15.22 %, and oil absorption of 0.51 ml/g.