The Basic Experiment Of Treatmenting Urban Sludge By Cement Stove

With the rapid development of China’s socio-economic,urbanization andindustrialization,urban sewage production increased year by year. As a by-product ofurban sewage treatmention, sludge production will be rapid growth, the harmless andresources treatmention of sludge is imminent.Because of the benefits of cooperativetreatmenting of urban sludge by cement stove, it has become the focus of internationalexperts.This paper studies the impact of sludge incineration in the cement productionprocess to lay the foundation of the developing of cooperative treatmenting of urbansludge by cement stove.The paper analyzes the physical and chemical characteristics of the urban sewagesludge.Considering the actual conditions of the industrial, study the influence oftemperature on sludge drying characteristics and heat values, analyzes the energybalance of drird sludge during incineration,calculates the activation energy andpre-exponential factor in the process of drying sludge; studies the effect of sludgeaddition on clinker modular value, burnability and mineral composition of the cementclinker;analyzes the characteristic of volatile and curing of heavy metals in sludgeduring the process of sludge drying and cement clinker forming. The results show that:Dring temperature has a significant effect on the heat value of sludge,the heatvalue of sludge dried by300℃reduces30.3%.The sludge drying temperature shouldbe controlled under250℃. The heat value of sludge with moisture content of30%bemaintained9517KJ/Kg,is equivalent to0.325kg standard coal.By fitting the data ofsludge drying, the activation energy is5.95KJ/mol. K and pre-exponential factor is0.0468s^-1. Withing the addition of sludge,there is little effect on SM and IM,but KH willdecreased rapidly;the incorporation of the sludge will improve clinkers’ burnabilityand decreased the content of f-CaO.When the addition of sludge less than1%,the heavy metals will decrease thetemperature of forming liquid phase,change the structure of mineral in Portland clinkerand increase the content of C₃S;but with the addition of sludge, the proportion of SiO₂in raw meal increased and the content of C₃S decreased.When the water content in sludge less then65%,dried sewage sludge incineratedin calciner will replace some coal,the sludge with water content of65%incinerated incalciner need no more coal, sewage sludge which the water content of30%incineratedis equivalent to133.5kg/t standard coal.The mixture with sludge and the ash inhumidification tower incinerated will need more coal to maintain the temperture ofcalciner.With the sludge is dried under150℃³00℃, Pb、Cr、Cd、As volatilize a little,butHg will volatilize67%; the cement clinkers’ curing rate of the heavy metals: Pb62.38%, Cr59.53%, Cd61.3%, Hg26.14%,As64.24%.With the whole process ofdrying and incineration,more than90%Hg will volatilize.