Production of belite rich cement by using water treatment plant sludge

• Main Authors: Mu-Jung Liao, 廖慕蓉
• Other Authors: Juu-En Chang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/63898070794336739398

碩士 === 國立成功大學 === 環境工程學系碩博士班 === 95 === In recent years, the water supply in Taiwan was stable, and therefore the water treatment plants produced enormous amount of sludge. This sludge, namely water treatment plant sludge (WTPS), was generated from the purification processes and it should be considered for reusing or recycling. WTPS can be reused as a raw material in cement production because its main compositions are Si, Al, and Fe. In this research, WTPS partially replaced the cement raw materials on the basis of controlled parameters. The raw meal was sintered at lower temperature to produce belite-rich clinker. In order to evaluate the burnability of the clinker, the free lime content was analyzed. The quantification of calcium-silicate phases was performed by X-ray diffraction and the reference intensity ratio (RIR) method. Based on the results, WTPS can partially replace the raw materials to form cement raw meal. The parameters of the raw meal, LSF, SR, and AR, were controlled at 0.7-0.9, 1.8, and 0.6, respectively. When using the maximum replacement of WTPS, proper LSF values and sintering temperatures can make the calcium oxide react completely, and consequently reduce the free lime in the clinker. The main phases of clinkers sintered at 1200ºC are belite. However, when the LSF of raw meal is 0.9, the clinker sintered at 1300ºC contains some C3S. The C2S would mainly exist in γ phase at room temperature. To prevent the transformation to γ-C2S from taking place, Cr2O3 was doped as a stabilizer to replace Si4+ of C2S and to preserve β-C2S at room temperature. By means of doping with 1% Cr2O3, most C2S in clinkers can be stabilized in β phase at room temperature.