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锌精矿脱硫焙烧烟气降温过程中,烟尘的性质及其中铅汞存在形态的变化规律是冶炼烟气重金属(Pb和Hg)污染控制的重要依据。通过电感耦合等离子体-原子发射光谱(ICP-AES)、激光粒度分析及筛分分析了不同降温收尘环节烟尘元素成分及粒度变化。烟尘主要含Zn、Fe、Ca、Cd、S、Pb元素,其累积质量分数达69.90%~77.62%,而Hg含量较低。烟尘粒径随烟气温度降低呈先增大后减小的变化规律,中位径由沸腾焙烧炉排出的28μm升至经余热锅炉降温后的36μm,再逐级降至经电收尘器后的5.6μm。据此,重点分析了Pb和Hg在烟气中的分布,并借助X射线光电子能谱(XPS)分析了其存在形态。结果表明,随烟气温度降低,烟气中Pb和Hg含量呈上升趋势,Pb由2.8%增至9.2%,Hg由4.8μg/g增至109.1μg/g。不同工艺环节的烟尘中Pb均以PbSO_4和含Pb—O键的复杂Pb配合物的形式存在。Hg变化较为明显,仅沸腾焙烧炉烟尘样品中能够检测到HgS与HgSO_4,其余工艺环节烟尘样品中无含Hg化合物的特征峰。
During the process of desulfurization and roasting flue gas desulfurization of zinc concentrate, the properties of flue dust and the variation of the existing forms of lead and mercury in the desulfurization roasting flue gas are the important basis for the pollution control of heavy metals (Pb and Hg) in smelting flue gas. The elemental composition and particle size of soot were analyzed by inductively coupled plasma-atomic emission spectrometry (ICP-AES), laser particle size analysis and sieving. The main dust contains Zn, Fe, Ca, Cd, S and Pb, the cumulative mass fraction reaches 69.90% ~ 77.62%, while the Hg content is low. The particle size of flue dust increased firstly and then decreased with the decrease of flue gas temperature. The median diameter was increased from 28μm discharged from boiling roaster to 36μm after cooling by waste heat boiler, Of 5.6 μm. Based on this, the distribution of Pb and Hg in flue gas is analyzed emphatically, and its existing morphology is analyzed by X-ray photoelectron spectroscopy (XPS). The results showed that with the decrease of flue gas temperature, the content of Pb and Hg in flue gas was on the rise, Pb increased from 2.8% to 9.2% and Hg increased from 4.8μg / g to 109.1μg / g. Pb in soot from different process stages exists in the form of complex Pb complexes of PbSO 4 and Pb-O bonds. Hg changes more obvious, only HgS and HgSO_4 can be detected in the roaster soot sample only, and the other peaks in the soot sample containing no Hg compound can be detected.