Study On Basic Question About The Combustion Of Sludge In Cement Rotary Kiln

There is trend around the world for cement industry to dispose waste using cement rotary kiln. This paper chooses municipal sludge and electroplating sludge as objects and researches problems about disposing sludge in cement rotary kiln such as physicochemical property of sludge,impact on clinker's structure and composition,function of heavy metals during clinker formation on the basis of associating with technology characteristics of cement kiln. The results are as followed:Firstly, this paper studies physicochemical property of sludge about disposing sludge with cement kiln.sludge with high water ratio affects calorific balance of cement kiln because of desiccation decalescence, so sludge must be desiccated, the desiccation craft of drying sludge with discharge gas and of fluidization furnace may be choosed. High calm value of municipal sewage sludge may replace part of fuel, clinker of municipal sewage sludge and electroplating sludge are used to proportion mixing instead of clay and iron raw respectively. Thermolysis course includes three phases: first phase is moisture volatilization; second phase is volatile matter volatilization mainly organic matter; the third phase is inorganic substance and residual organic matter decomposition.Secondly, incineration character of sludge is studied. The research shows: it has high weight loss in lower temperature and the tend of weight loss is moderate in higher temperature; Ni and Cr belong to difficult volatile heavy metal, they are solidified in the clinker through participate in solid state reaction and liquid sintering, excessive Cr can make C3S decompose; non volatile heavy metals such as Zn and Pb are easy to form sulfate and chloridate and generate internal recycle in kiln and preheater system; Cd,As and Hg is apt to volatilize and exist in the fume, so it is easy to lead to discharge pollution; the change of mineral composition and chemical component is that because mineral substance and salt decompose in high temperature; Ash's structure is loose and surface has Stomata and pore as temperature gets higher.Thirdly, the tests study the effects of municipal sludge and electroplating sludge No. four on the burnability of raw meal under the clinker factors of KH=0.91,SM=2.6,IM=1.6,KH=0.94,SM=2.6,IM=1.6 and KH=0.97,SM=2.6,IM=1.6.The result shows that under three clinker factors, the range of filling municipal sludge is from 15 percent to 20 percent, for electroplating sludge No. four, the best adding quantity is 1.91 percent. As saturation coefficient is improved, the burnability of cement raw meal falls. Because of exotic trace element by filling sludge, the burnability of cement raw meal can improve on the certain degree and pattern of clinker is better in contrast to blank clinker. The incorporation ratio of heavy metals in lab is(percent):Cr 86.2 t;Cd 80.4;Ni 84.0;Co 80.45;Cu 81.8;Zn 70.1;Pb 80.4.