Division of Geosciences and Environmental Engineering, Luleå University of Technology, 971 87, Luleå, Sweden,
Environ Sci Pollut Res Int. 2013 Nov;20(11):7907-16. doi: 10.1007/s11356-013-1838-z. Epub 2013 Jun 6.
Backfilling of open pit with sulfidic waste rock followed by inundation is a common method for reducing sulfide oxidation after mine closure. This approach can be complemented by mixing the waste rock with alkaline materials from pulp and steel mills to increase the system's neutralization potential. Leachates from 1 m3 tanks containing sulfide-rich (ca.30 wt %) waste rock formed under dry and water saturated conditions under laboratory conditions were characterized and compared to those formed from mixtures. The waste rock leachate produced an acidic leachate (pH<2) with high concentrations of As (65 mg/L), Cu (6 mg/L), and Zn (150 mg/L) after 258 days. The leachate from water-saturated waste rock had lower concentrations of As and Cu (<2 μg/L), Pb and Zn (20 μg/L and 5 mg/L), respectively, and its pH was around 6. Crushed (<6 mm) waste rock mixed with different fractions (1-5 wt %) of green liquid dregs, fly ash, mesa lime, and argon oxygen decarburization (AOD) slag was leached on a small scale for 65 day, and showed near-neutral pH values, except for mixtures of waste rock with AOD slag and fly ash (5% w/w) which were more basic (pH>9). The decrease of elemental concentration in the leachate was most pronounced for Pb and Zn, while Al and S were relatively high. Overall, the results obtained were promising and suggest that alkaline by-products could be useful additives for minimizing ARD formation.
采用露天矿回填硫化物废石并淹没的方法是减少矿山关闭后硫化物氧化的常用方法。这种方法可以通过混合废石与纸浆和钢厂的碱性材料来补充，以增加系统的中和潜力。在实验室条件下，对干条件和水饱和条件下形成的富含硫化物（约 30wt%）废石的 1m3 罐中的浸出液进行了特征描述，并与混合物形成的浸出液进行了比较。废石浸出液在 258 天后产生了酸性浸出液（pH<2），其中 As（65mg/L）、Cu（6mg/L）和 Zn（150mg/L）浓度很高。水饱和废石浸出液中 As 和 Cu 的浓度较低（<2μg/L），Pb 和 Zn 的浓度分别为 20μg/L 和 5mg/L，其 pH 值约为 6。将粒径小于 6mm 的废石与不同比例（1-5wt%）的绿泥渣、粉煤灰、 mesa 石灰和氩氧脱碳（AOD）渣混合，进行小规模浸出 65 天，除了废石与 AOD 渣和粉煤灰（5%w/w）的混合物呈碱性（pH>9）外，其余混合物的 pH 值接近中性。除了 Pb 和 Zn 的浓度明显降低外，浸出液中元素浓度的降低最为明显，而 Al 和 S 的浓度相对较高。总的来说，所得结果很有希望，表明碱性副产物可能是减少 ARD 形成的有用添加剂。
