黄铁矿焙烧过程中铊析出影响因素及其烧渣中重金属的相态分布研究

Research on effect factors of thallium release in the process of roasting pyrite and phase distribution of heavy metals in its cinder

通过模拟硫酸厂的沸腾焙烧炉，考察了黄铁矿焙烧过程中铊（Tl）析出的影响因素，并通过分级提取法考察了黄铁矿烧渣中重金属的相态分布。结果表明，Tl释放率随焙烧温度的升高而增加，随停留时间的增长而增加；当O2流量在20～300mL／min范围变化时，Tl释放率先增后减。环境中备受关注的重金属（如Pb、Cd、Cr等）在黄铁矿烧渣中以Pb为主，各相态Pb的总量达到1429．20μg／g，且黄铁矿烧渣中的重金属（除Cu和Sr外）主要是以分布于硅酸盐矿物相中的残余态形式存在，因此在环境中不易迁移释放。尽管黄铁矿烧渣中的重金属（除Cu和sr外）不是以非残余态分布为主，但非残余态重金属的总量也不少，因此黄铁矿烧渣在环境中的潜在污染风险应当引起重视。

The effect factors of thallium release in the process of roasting pyrite were studied by simulating the boiled furnace in sulfuric acid plant, and phase distribution of heavy metals in pyrite cinder were also analyzed with sequential extraction procedure. The results showed that the release ratio of thallium increased with the increases of calcination temperature and resident time. The release ratio of thallium first increased and then decreased when the oxygen gas flux changed in the range of 20-300 mL/min. In concerning of heavy metals such as Pb, Cd, and Cr and so on, in the pyrite cinder, Pb was the dominant one. Its total content in all phases reached to 1 429.20 μg/g. The heavy metals in pyrite cinder mostly distributed in silicate phase with residual fraction except Cu and Sr, hence its potential to release into environment is not active. Though the heavy metals distributing in the nonesidual fractions were not in dominant in the pyrite cinder except Cu and Sr, the sum of the total concentrations of them could not be ignored; consequently, pyrite cinder＇s potential risk of pollution to environment must be paid attention to.