Study Of Municipal Sludge Ash On Physical And Chemical Properties And Simultaneous Thermal Analysis

As urban development accelerated, the production of sludge is increasing correspondingly. Since the complex composition of sludge is both hazardous and resources, it is becoming increasingly urgent to deal with municipal sludge reasonably for maximum resource utilization. Sludge incineration is need to be studied as a resource utilization method. The different sewage sludge was taken as the research object. The change process of sludge ash during incineration process was researched, which providing a reference for the actual sludge incineration.Five different temperature sludge ash were studied by SEM, EDX, XRD, STA methods. The ash appearance morphology and microscopic characteristics, the composition and evolution of ash mineral, weightlessness and thermal change of sludge ash during heating process are analyzed. Kinetic mechanism of the weight loss process and the sludge ash fusion characteristics was discussed.The study have shown that the color of low temperature sludge ash is dark gray. With the ashing temperature increase, the color gradually change to iron red, and the dendrites become more on micromorphology until fusion. The minerals in ashes varied significantly in the range of experiment temperature. Calcite, quartz, and pyrophosphate are mainly present in the lower temperatures ashes, in addition to sillimanite, magnetite, hematite, etc. With the temperature increase, feldspathic, anhydrite and phosphate, stanfieldite as well as quartz become the main components.STA experiment shows that the weightlessness of the same sludge in different temperature ash is unlike. The higher ashing temperature gets, the smaller weightlessness is. With the temperature rise, four kinds of sludge emerge loss of adsorbed water, dehydroxylation of mineral crystal, residual organics combustion, calcite and dolomite decomposition and volatilization of SO2 weightlessness stage. Kinetic analysis showed that most of reaction order of the ash weightlessness stages is not the reference value, which explains the actual process has a deviation with the ideal reaction process. Different experimental atmosphere will affect the weightlessness process and ash melting point. Oxidizing atmosphere not only promote the progress of the reaction which bring forward all weightlessness peak; it but also promote the conversion of organic matter in the sludge. In general, low temperature ash, which heat absorption is greater than the high temperature, retains many original features of sludge, melting onset temperature of all the ashes is low. And the low temperature corrosion of sludge incinerator is needed to focus on.