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首页> 外文期刊>Journal of Environmental Management >Reclamation of an arsenic-bearing gypsum via acid washing and CaO-As stabilization involving svabite formation in thermal treatment
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Reclamation of an arsenic-bearing gypsum via acid washing and CaO-As stabilization involving svabite formation in thermal treatment

机译：通过酸洗和CaO-As稳定化处理含砷石膏，在热处理中涉及形成锯齿状

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摘要

As one of the biggest hazardous solid waste in the metallurgical industry, arsenic-bearing gypsum (ABG) is a great threat to environmental safety owing to possible leakage and diffusion contamination. However, the reclamation of ABG suffers great challenges due to its worthless constituents and high arsenic leaching. In this study, an ABG was reclaimed as more valuable bassanite (CaSO4 center dot 0.5H(2)O) and anhydrite (CaSO4). Firstly, the overmuch arsenic in ABG was removed to below 150 mg/kg (Japan standard value) using acid extraction. Then, the sludge was mixed with a small amount of CaO and heated at 150 degrees C and 900 degrees C to produce bassanite and anhydrite, respectively. In this calcination, gypsum dehydration and arsenic stabilization were combined. In Japan standard leaching test (JSLT), the arsenic leaching concentrations from bassanite (5.1 mu g/L) and anhydrite (1.3 mu g/L) satisfied the environmental criteria ( 10 mu g/L) set by Japan government and remained stable for three months. In toxicity characteristic leaching procedure (TCLP), arsenic leaching concentrations remained at 1.61 and 0.61 mg/L, much lower than the limitation ( 5 mg/L). Moreover, the arsenic leaching behavior implied that higher temperature was benefited to arsenic stability, which indicated that the arsenic stabilization process was temperature dependent. By XRD analyses, it was found that heating (over 100 degrees C) could effectively promote arsenic immobilization through reducing the carbonation influence. And the temperature dependence was attributed to the formation of insoluble svabite (Ca-5(AsO4)(3)OH) at high temperature (300-900 degrees C).
机译：作为冶金工业中最大的有害固体废物之一，含砷石膏（ABG）由于可能的泄漏和扩散污染而对环境安全构成了巨大威胁。但是，ABG的回收由于其毫无价值的成分和高砷浸出而遭受了巨大的挑战。在这项研究中，ABG被回收为更有价值的重锰矿（CaSO4中心点0.5H（2）O）和硬石膏（CaSO4）。首先，使用酸萃取将ABG中过量的砷去除至150 mg / kg（日本标准值）以下。然后，将污泥与少量的CaO混合，并分别在150℃和900℃下加热，以生成重钙铝石和硬石膏。在该煅烧中，将石膏脱水和砷稳定化相结合。在日本标准浸出试验（JSLT）中，从重晶石（5.1μg / L）和硬石膏（1.3μg / L）浸出的砷满足日本政府设定的环境标准（<10μg / L），并且保持稳定三个月。在毒性特征浸出程序（TCLP）中，砷的浸出浓度保持在1.61和0.61 mg / L，远低于限值（<5 mg / L）。此外，砷的浸出行为表明较高的温度有利于砷的稳定性，这表明砷的稳定过程与温度有关。通过XRD分析，发现加热（超过100℃）可以通过减少碳酸化影响而有效地促进砷的固定。并且温度依赖性归因于高温（300-900℃）下不溶性西维比特（Ca-5（AsO4）（3）OH）的形成。

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