H_(2)O_(2)氧化-CaO化学稳定一步法联合处置钙砷渣

One step treatment of arsenic calcium residues by combining H_(2)O_(2) oxidation and CaO chemical stabilization

针对钙砷渣的稳定化处置,建立了H_(2)O_(2)氧化-CaO化学稳定的一步处理法,并探究了稳定化机理.实验结果表明:当CaO和H_(2)O_(2)的加入量分别为6%(质量分数)和0.6%(质量分数)时,钙砷渣的砷浸出质量浓度由650 mg/L降至0.97 mg/L;H_(2)O_(2)可氧化钙砷渣中的As(Ⅲ),使其在总砷中的质量分数从33.8%降至22.7%;CaO既能提高体系pH值又能提供活性钙离子,使之与As形成更稳定、难溶的Ca3(AsO_(4))_(2)·2H_(2)O晶体化合物;二者共同作用,促使砷的赋存形态由不稳定的酸可溶态转化为稳定的可还原态和残渣态,增加了钙砷渣中砷的稳定性.

To treat the arsenic calcium residues,a treatment method by combining H_(2)O_(2) pre-oxidation and CaO chemical stabilization was developed to greatly decreased the arsenic leaching content of the arsenic calcium residues from 650 mg/L to 0.97 mg/L,and the stabilization mechanism was explored.Experimental results show that H_(2)O_(2) could oxidize As(III)in arsenic calcium residues to reduce the mass proportion of As(III)in the total arsenic from 33.8%to 22.7%.CaO could provide active calcium ions while increasing the pH of the system,making it form a more stable and insoluble Ca3(AsO_(4))_(2)∙2H_(2)O crystal compound with As,and transforming the existing form of arsenic from an unstable acid-soluble state to stable states such as reducible state and residue state,which increases the stability of arsenic in arsenic calcium residues.