The mechanisms at different pH for the stabilization of arsenic (As) in mine tailings (MTs) using steelmaking slag were investigated using laboratory experiments. Two types of steelmaking slag were used in the experiments. Ca-slag has high pH and high calcium oxide content due to its short period of aging. In contrast, Fe-slag is oxidized for a long time and is richer in Fe than in Ca. The As-contaminated MTs were taken from a tailing-storage dam around an abandoned gold mine in Korea. The tailings had an average As concentration of 2225.3 mg/kg. The As-removal batch experiment was performed to investigate the As-removal characteristics of the steelmaking slag. From SEM/EDS analyses after each batch experiment, Ca-As bearing precipitates were broadly found on the surface of Ca-slag particles and the final pH of the solution increased to 12.3. However, for Fe-slag, the As was locally found as forms adsorbed to the surface of Fe and Mn oxides contained in the Fe-slag particles. The final pH of this solution was 8.4. The efficiency of removal of As from water using the Ca-slag was >97% and that with Fe-slag was 79%. This suggests that As ions in solution were removed by Ca-(co-)precipitation (which occurs comprehensively on the Ca-slag surface), or by restrictive adsorption of Fe- and Mn-oxides (on limited parts of the Fe-slag). To determine the efficiency of As-extraction reduction from MTs using steel slags, arsenic-extraction batch experiments with two slags were performed under acidic conditions, simulating the leaching environment formed around a mine tailing storage dam. The As concentration in the extracted solution was decreased by 69.9% (even at pH 2) after the addition of 5% Fe-slag. However, when 5% Ca-slag was added, the As concentration decreased by 42.3% at pH 2. These results suggest that Fe-rich steel slag can be more effective than Ca-rich steel slag as a stabilizer for As in contaminated mine tailings at low pH.

中文翻译：

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炼钢矿渣在不同pH值下稳定尾矿中砷的机理

通过实验室实验研究了在不同pH值下利用炼钢渣稳定矿山尾矿（MT）中砷（As）的机理。实验中使用了两种类型的炼钢渣。钙渣由于其短时效而具有高pH值和高氧化钙含量。相反，铁渣被长时间氧化，并且铁中的钙比钙中的铁丰富。被污染的MTs是从韩国一个废弃金矿周围的一个尾矿库中提取的。尾矿的平均砷浓度为2225.3 mg / kg。进行除砷分批实验以研究炼钢炉渣的除砷特性。根据每批实验后的SEM / EDS分析，在Ca渣颗粒表面上广泛发现了带有Ca-As的沉淀物，溶液的最终pH值升至12.3。然而，对于铁渣，As被局部发现为吸附在铁渣颗粒中所含的Fe和Mn氧化物的表面上的形式。该溶液的最终pH为8.4。使用钙渣从水中去除As的效率> 97％，使用铁渣去除As的效率为79％。这表明通过Ca-（共）沉淀（全面发生在Ca渣表面上）或通过有限吸附Fe-和Mn-氧化物（在Fe-渣的有限部分上）除去了溶液中的As离子。 。为了确定使用钢渣从MT中还原As的效率，在酸性条件下用两个矿渣进行了砷萃取分批实验，模拟了矿山尾矿库附近形成的浸出环境。提取液中的As浓度降低了69。加入5％铁渣后达到9％（即使在pH值为2的情况下）。但是，当添加5％的Ca渣时，在pH 2下，As的浓度降低了42.3％。这些结果表明，富Fe钢渣比受Ca渣影响的矿山尾矿中的As稳定剂更有效。在低pH下。