制备方法对臭葱石浸出稳定性的影响

Effects of Synthesis Methods for Scorodite on Its Leaching Stability

采用常压法、水热法和改进常压法,分别在添加和不加晶种的情况下制备臭葱石,对其物相、结晶度、形貌、粒度、比表面积、Fe/As摩尔比、浸出稳定性进行表征,揭示制备方法与臭葱石组成、结构性能及浸出稳定性之间的关系.结果表明,制备方法对臭葱石组成与结构性能有显著影响,结晶度高、比表面积小和Fe/As摩尔比低的臭葱石浸出稳定性高.3种方法制备的臭葱石浸出稳定性顺序为:常压法-水热法-改进常压法.改进常压法在不加晶种条件下制备的臭葱石形貌呈由{111}晶面族包围的角锥状大颗粒晶体,结晶度为84.56%,粒度(D50)为28.2-m,比表面积为3.72 m2/g,Fe/As摩尔比为1.05;参照HJ/T300方案对其浸出稳定性进行评价,浸出10 d后,浸出液中总砷浓度仅为1.14 mg/L.

Scorodite was synthesized under both addition and without addition of crystal seed by atmospheric, hydrothermal and improved atmospheric synthesis methods, ASP, HSP and IASP in abbreviation, and its crystal structure, crystallinity, morphology, particle size, specific surface area, Fe/As mole ratio and leaching stability were characterized, aiming at revealing the relationships among the synthesis methods, composition, structural properties and leaching stability of scorodite. The results show that the synthesis method has significant effect on the composition and structural properties. Scorodite with high crystallinity, small specific surface area, and low Fe/As mole ratio possesses high leaching stability. The order of leaching stability of synthesized scorodite samples follows the order of ASP 〈 HSP 〈 IASP. The scorodite sample synthesized by IASP without addition of crystal seed appears in crystalline particles with large size and pyramidal morphology enclosed by {111}, and possesses the crystallinity of 84.5%, particle size （D_50） of 28.2μm, BET specific surface area of 3.72 m2/g and Fe/As mole ratio of 1.05. With HJ/T300 method, the leaching stability of scorodite sample was tested, after leaching for 10 d, the total arsenic concentration in the leaching solution is only 1.14 mg/L.