Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea.
Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea.
Chemosphere. 2020 Jun;248:126111. doi: 10.1016/j.chemosphere.2020.126111. Epub 2020 Feb 4.
Leaching of toxic metallic elements (Cu, Zn, As, Cd, and Pb) from two solid mine wastes was characterized under different drying treatments. During 14 batch decant-refill leaching steps, samples were intermittently dried four times in 40 °C oven or -20 °C freezer. For all leachates, the pH, pE, Fe/Fe, and SO were analyzed. The parameters of the two-site model (k, k, and f) and labile fractions (F1 + F2) were determined. High levels of toxic metallic elements were determined in waste samples; however, their leaching was limited, as evidenced by the magnitudes of F1 + F2, f, and k. Leachate solutions were acidic, at pH 3-4, and oxic, at 150 mV < Eh 300 < mV, thus having negligible Fe. Leachate concentrations of toxic metallic elements increased (4-58%) after drying at 40 °C and were strongly correlated (r = 0.780) with those of sulfate in liquid phase. The mass of element elution was in the order of 40 °C drying > -20 °C drying ≥ continuous wetting. Results indicate that the element leachability is increased through drying events and the leachate concentration is associated with the dissolution reaction of sulfur-bearing minerals. Frequent occurrence of prolonged droughts along with high temperatures over the mine waste disposal site, can enhance the leaching potential of toxic metallic elements.
从两种固体矿山废物中浸出有毒金属元素（Cu、Zn、As、Cd 和 Pb）的特性在不同的干燥处理下进行了研究。在 14 批倾析-再填充浸出步骤中，样品在 40°C 烘箱或-20°C 冷冻箱中间歇干燥四次。对于所有浸出液，分析了 pH、pE、Fe/Fe 和 SO。确定了双位点模型（k、k 和 f）和不稳定分数（F1+F2）的参数。废样品中测定了高水平的有毒金属元素；然而，由于 F1+F2、f 和 k 的数值较大，表明浸出有限。浸出液呈酸性，pH 值为 3-4，氧化还原电位为 150 mV<Eh<300 mV，因此几乎没有 Fe。在 40°C 干燥后，浸出液中有毒金属元素的浓度增加了（4-58%），并且与液相中硫酸盐的浓度呈强相关性（r=0.780）。元素洗脱的质量顺序为 40°C 干燥>-20°C 干燥>连续润湿。结果表明，干燥事件会增加元素的浸出率，浸出液浓度与含硫矿物的溶解反应有关。矿山废物处置场地经常发生长时间干旱和高温，这可能会增强有毒金属元素的浸出潜力。
