Study On Performance Of Sewage Sludge In The Metallurgical Sintering Process

With the increasing of wastewater year by year,the increasing sewage sludge(SS)from urban sewage treatment plant has become a prominent environmental pollution problem.Therefore,it is important and practical for us to study the recycling of the SS.In this paper,the physical and chemical properties of SS in Chongqing,adding SS and carbon for the influence of sinter metallurgical properties in sintering process were studied.By researching the characteristics of the sludge of sewage treatment plant,the particle size distribution of SS mainly concentrated in the range of 0-0.2mm where the volume fraction is about 84.01%.The main elements included Si,Ca,Fe,Al,Mg,S and P in the dry SS.S and P were 0.8% and 0.69%,respectively.Adding a small amount of SS had little effect on the sintering process.At the same time,the content of heavy metals in dry sludge was relatively less.ZnO was 0.15% in the dry SS,and other heavy metals were not detected.Adding appropriate SS can improve the combustion performance of blended fuel because of the abundant organic compound in SS.Sludge combustion process is divided into three stages.After the analysis of the combustion characteristics and calorific value about SS,the calorific value per kilogram of dewatered SS is 5325.66 kJ,equivalent to 0.182 kg of standard coal calorific value.The experimental results showed that the particle size distribution of the mixture can be improved with the addition of the sludge increasing from 0% to 4%.The permeability of the sintered mixture was improved,the strength of the sinter was enhanced,and the metallurgical properties of the sinter are also boosted.However,when the addition of SS exceeded 4%,the permeability of the sintering bed would recede and the metallurgical properties of the sinter would be affected.Considering the production and metallurgical properties of the sinter,the reasonable addition of SS that has 72% moisture content is about 4%.It was studied on the reasonable proportion of the carbon after adding sludge showed.When the amount of SS was 4% and the proportion of the carbon was changed from 5.04% to 5.34%,the sinter product ratio decreased gradually,and the yield of the sinter increased inch by inch.According to the economic cost of SS treatment and sintering production,the appropriate ratio of SS should be operated in about 4% and the suitable addition of the carbon should be controlled at about 5.04%.