钛石膏中重金属元素的浸出特性研究

研究了钛石膏中重金属含量和不同浸出条件下钛石膏中重金属的浸出特性。结果表明,钛石膏中Mn、Hg、Zn、Cr、As含量相对较高,表现出对周围环境的潜在危害性。不同浸提剂浸出实验中,由于较强的离子强度效应,海水对重金属的浸出能力强于硫酸/硝酸、去离子水(除Zn外),且海水Hg浸出浓度超出标准限值近3倍。在连续静态浸出实验中,海水浸出和酸性浸出的重金属浓度均不断降低,但重金属海水浸出量始终高于酸性浸出,表明盐度对重金属的浸出具有持续促进作用,而钛石膏则表现出较强的酸缓冲能力。同时在连续浸出过程中海水及酸性浸出的重金属累积浸出率均显著增加,说明在标准加速浸出时间以外,钛石膏液固浸出体系仍具有较强的重金属释放能力,故认为钛石膏简易堆存可能存在环境风险。

STUDY ON LEACHING CHARACTERISTICS OF HEAVY METALS IN TITANIUM GYPSUM

The content and leaching characteristics with different leaching conditions of heavy metals in titanium gypsum were studied． The results indicated that the content of main trace elements of titanium gypsum such as Mn，Hg，Zn，Cr，As，were relatively high，showing the potential risk to the surrounding environment． The leaching under different extracting agents showed that the highest leaching concentration of heavy metals occurred in the seawater with the exception of Zn，and then H2 SO4 /HNO3 and deionized water，even the seawater concentration of Hg exceded standard limit． In the test of continuous static leaching，the leaching concentration of heavy metals continued to decrease both in saline and acid mixture，whereas the leaching amount in seawater was always higher，meaning that the promotion of salinity on heavy metals leaching could continue with time and a strong acid buffer capacity of titanium gypsum was observed． Simultaneously，with the continuous leaching process，the cumulative leaching rate of heavy metals increased significantly both in two agents，indicating a strong heavy metal release capability still in the liquid-solid leaching system of titanium gypsum in addition to the standard accelerated leaching time，and the pollution control measures should be taken for the titanium gypsum of simple stockpiling because of its potential environmental risk．