磷对泥/煤混燃灰熔融特性的影响及矿物相演变规律

采用灰熔点仪、X射线荧光仪(XRF)研究了无机非金属P2O5对城市污水污泥与烟煤的混烧灰熔融特性的影响,利用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)研究在各混烧温度下灰中含磷矿物在晶体和非晶体间的演变。结果表明,对于Al_2O_3含量较多且熔点较高的灰样,磷含量的增加可显著降低其灰熔点,P2O5含量在0-4%时影响最大,使其灰熔点降低126℃;但对碱性含量高的灰样的影响较小。低温灰中主要以磷酸铝(AlPO_4)晶体为主,温度升高后,与硬石膏(CaSO_4)等含钙矿物和赤铁矿(Fe_2O_3)反应生成晶体Ca_3(PO_4)_2和玻璃相(Fe_2O_3)_(0.252)(P_2O_5)_(0.748),磷含量增加可使灰中玻璃相(Fe_2O_3)_(0.252)(P_2O_5)_(0.748)增加,是磷降低灰熔点的主要原因。

Effect of phosphorus on ash fusion characteristics and mineral transformation during co-combustion of sewage sludge and coal

The influence of inorganic phosphorus on ash fusion characteristics of sewage sludge and coal were investigated by ash fusion temperature (AFT) detector and X-ray fluorescence (XRF), and the transformation of containing phosphate minerals of blended ashes with different temperatures between crystal and amorphous were explored using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). For the ash sample with high contents of Al₂O₃, which has higher AFT, raising content of phosphorus significantly results in a reduced ash fusion point, in particular it is lowered by 126℃ at 0-4% P₂O₅ content. But it has little effect on ash with high alkaline content. Aluminum phosphate (AlPO₄) crystals is the major phosphor containing minerals in low temperature ashes, witch react with calcium minerals (CaSO₄) and hematite (Fe₂O₃) to form Ca₃(PO₄)₂ crystal and (Fe₂O₃)_0.252(P₂O₅)_0.748 glass phase along with increasing temperature. Meanwhile,(Fe₂O₃)_0.252(P₂O₅)_0.748 in glass phase increases with an increase in phosphorus content, which may be the primary cause of AFT decreasing.