含砷废渣高温烧结过程砷的矿物相结构变化与环境释放行为

Structural Changes in Mineral Phases and Environmental Release Behavior of Arsenic During Sintering of Arsenic-containing Waste

研究了含砷废渣高温烧结过程引起的砷挥发和砷发生的矿物相结构变化,并分析了烧结体的砷浸出释放行为.在10MPa下加压成型制样,进空气流量为2 000 mL·min-1,烧结温度1 000～1 350℃,烧结时间60 min.结果表明,烧结温度对砷挥发的影响很小,As的固定率保持在90%以上,但对砷浸出毒性的影响明显.烧结温度低于1 000℃时,FeAsS被氧化生成钙砷、铝砷和铁砷,以Ca3(AsO4)2矿物相为主,导致砷的浸出释放水平提高;烧结温度达到1 200℃,Ca3(AsO4)2被玻璃熔融态所包围,并被转换为硅钙砷酸盐化学键接,导致砷的浸出水平显著降低.从烧结体的环境安全性考虑,最佳烧结温度为1 200℃.

An experimental work was carried out to investigate the effect of sintering temperature on arsenic volatility,arsenic leaching of the sinter and structural changes in mineral phases of arsenic in the sinter.The raw materials were shaped under the pressure of 10 MPa and sintered at 1 000-1 350℃ for 60 min with the air flow rate of 2 000 mL·min-1.The results showed that there was little impact between the volatilization of arsenic before and after sintering,and arsenic fixed-rate remained above 90%,however,the sintering temperature had an important influence on the leaching concentration of arsenic.When sintering temperature was lower than 1 000℃,FeAsS was oxidized into calcium arsenate,aluminum arsenate,and iron-arsenate.Ca3（AsO4）2 was the main compound,and the release of arsenic leaching was high.When sintering temperature was up to 1 200℃,the arsenic was surrounded by a glass matrix and became chemically bonded inside the matrix.Arsenates can be converted into silicoarsenates during sintering,which led to the leaching of arsenic was significantly lower.Considering the product＇s environmental safety,the best sintering temperature was 1 200℃.