矿渣-钢渣基胶凝材料固砷机理

来源期刊:中南大学学报(自然科学版)2019年第7期

论文作者:倪文 鄢琪慧 高巍 李云云 张钰莹

文章页码:1544 - 1551

关键词:矿渣;钢渣;固化;砷;胶结充填

Key words:blast furnace slag; steel slag; solidification; arsenic; cemented backfilling

摘    要:为降低广西某选矿厂铅锌矿尾砂对环境的危害,同时达到固废减量化、资源化的目的,以矿渣、钢渣为主要原料制备胶凝材料(metallurgical slag cementitious material,MSC),并与尾矿砂混合制备膏体充填料协同固化砷。研究结果表明:尾砂中As质量分数为0.11%,As原始浸出质量浓度为0.66 mg/L,经MSC固化后As浸出质量浓度为0.031 mg/L,固化率达95.3%;As可以通过类质同象替换进入C-S(A)-H凝胶或类沸石相中代替Si原子或Al原子的位置,AsO 可与Mg(OH)2和Ca(OH)2反应生成溶解度较低的复盐沉淀,且砷可以被水化产物C-S(A)-H凝胶包裹、吸附,Na2SO4与Na3AsO4反应生成低溶解度复盐类沉淀,这些都是砷被稳定固化的机制。

Abstract: In order to reduce the environmental risk of lead and zinc tailings in a concentrator in Guangxi, and at the same time achieve the purpose of reducing and recycling solid waste, blast furnace slag and steel slag were used as the main raw materials to prepare cementitious materials (metallurgical slag cementitious material, MSC), and mixed with tailings to prepare paste backfilling materials, which could also immobilize arsenic. The results show that the arsenic in tailings is 0.11%. The leaching mass concentrations of arsenic is 0.66 mg/L. After metallurgical slag cementitious material’s solidification, the leaching mass concentrations of arsenic is 0.031 mg/L, and the curing efficiency is 95.3%. Arsenic atom can replace the aluminum atom or silicon atom which is in the structure of C-S(A)-H gel and zeolite-like phase, can also react with Mg(OH)2 and Ca(OH)2 in formation of calcium arsenate with lower solubility, and arsenic can be adsorbed and encapsulated by C-S(A)-H gel, furthermore, Na2SO4 reacts with Na3AsO4 resulting in the formation of double salt precipitates with low solubility, which is all the mechanism for solidification of arsenic.

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