Study On Pyrolysis Of The Sediment From Dianchi Lake And Pyrolysis Productions

Contaminated lake sediments are the main internal source of pollutants in the lake. Due to the unique geographical environment and history of pollution, the sediment from Dianchi Lake shows obvious pollution features. Most of the dredged sediment is stacked on the shore of Dianchi Lake, which not only takes up a lot of land, but also may leads to secondary pollution. How to dispose of them effectively is the urgent environmental problem. Pyrolysis, with the advantages of economic efficient and environmental friendly, is one of the solid waste diaposal technology aimming to reduction, recycle, detoxification. In this paper, pyrolysis technology was used to dispose of the sediment from Dianchi Lake, in order to provide a reference for the thermo-chemical treatment of the the sedimen from Dianchi Lake.The composition of the sediment from Dianchi Lake composition was analyzed, through proximate analysis, ultimate analysis and XRF analysis. The thermal decomposition characteristic of the sediment from Dianchi Lake was studied by TG-DTA. Based on the above analysis, pyrolysis experiment of the sediment from Dianchi Lake was arried out under final pyrolysis temperature varied from 500～1000℃and characteristics of representative pyrolysis products were analyzed. Results are as follows:(1) According to proximate analysis and ultimate analysis, the sediment from Dianchi Lake, lowest in fixed carbon and highest in ash, has a certain value of energy utilization as 36.56% of volatile matter. The concent of C, H elements in the sediment from Dianchi Lake sediment were higher, with certain amount of latent heat, and the concent of Si, Al, Fe elements were higher, with a development value of building materials, and sediment contains a variety of metallic elements which may play a catalytic role in pyrolysis process.(2) TG-DTA experiment of the sediment from Dianchi Lake was carried out in the air atmosphere, the result shows that the combustion of the sediment from Dianchi Lake sediments can be divided into four stages. The kinetic calculation results of TG curves indicate that the second stage (230.02℃-420.69℃) is a first order reaction, with 22.691kJ/mol for activation energy, and the third stage (420.69℃～530.89℃) is a second order reaction, with 15.390kJ/mol for activation energy.(3) H2, CO, CH4, CO2, C2H4 and C2H6 are the main components of pyrolysis gases of the sediment of Dianchi Lake. The flammable gases, H2, CO, CH4, were vastly generated in high-temperature section. LHV of the gas collected in the temperature vary from 820～860℃is about 12122.19kJ/m3, obtained by theoretical calculation, which belongs to the medium calorific value of gas fuel. The main component of liquid pyrolysis product is phenol and its hydroxy derivatives, there is no fuel use value, but abundance of phenol and its derivatives can be used as chemical raw materials. Solid products are in the enrichment of a large number of Si, Al, Fe and other mineral elements, which have the good prospects using as building materials.