铁岭煤中重金属元素的赋存形态及其在热解过程中的挥发行为研究

Modes of occurrence of Pb, Cr, Co, Ni, V in Tieling raw coal and two char samples were determinedusing density fractionation, demineralization and sequential chemical extraction methods. Volatilization behaviors of Pb, Cr, Co, Ni and V were investigated during pyrolysis of Tieling coal in a fluidized-bed reactor at temperatures ranging from 500 ℃ to 900 ℃. Pb, Cr, Co, Ni, V in Tieling coal are mainly associated with mineral matters such as silicates, sulfates, sulfides, and about 40%～60% of them are associated with alumino-silicate mineral matters. Lead associated with carbonates and organic bonded ion exchangeable forms has already decomposed below 600 ℃. Forms of Pb, Cr, Co, Ni, V associated with sulfates and sulfides are unstable, whereas the transformation behaviors of them are different. Thermally stable phases of Cr and V are formed under high pyrolysis temperatures. In the temperature range studied, Pb belongs to semi-volatile elements, while Cr, Co, Ni and V belong to non-volatile elements.