Metal extractability in acidic and neutral mine tailings from the Cartagena-La Unión Mining District (SE Spain)

详细信息	查看全文 | 推荐本文 |

• 作者：Hé ; ctor M. Conesa ; Brett H. Robinson ; Rainer Schulin ; Bernd Nowack
• 关键词：Five-axis machining ; Flank milling ; Ruled surface ; Dynamic programming ; Optimization
• 刊名：Applied Geochemistry
• 出版年：2008
• 期刊代码：5_08832927
• 类别：ce
• 出版时间：May 2008
• 卷：23
• 期：5
• 页码：1232-1240
• 文件大小：172 K

摘要

Mine tailings are ubiquitous in the landscapes of mined areas. Metal solubilities were compared in two chemically distinct mine tailings from the old Mining District of Cartagena-La Unión (SE Spain). One of the tailings was acidic (pH 3.0) with 5400 mg/kg Zn, 1900 mg/kg As and 7000 mg/kg Pb. The other was neutral (pH 7.4) with 9100 mg/kg Zn, 5200 mg/kg Pb and 350 mg/kg As. In samples from the acidic tailings, more than 15%of the Zn and 55%of the Cd were extractable with 0.1 M NaNO₃, and distilled water. In the neutral tailings, using the same reagents, less than 1%of the metals were extractable. A sequential extraction procedure revealed that the sum of the residual and the Fe oxide fractions of Cu, Zn and Pb comprised 80–95%in the acidic tailings and 70–90%in the neutral tailings. The acidic mine tailings had a higher metal solubility, resulting in more metal leaching in the short-term, but also a higher fraction of inert metal. In contrast, in the neutral tailings, the metals were evenly distributed between, oxides and the residual fraction. This implies lower metal mobility in the short-term, but that metal mobility may increase in the long-term. When applied to mine tailings, sequential extractions may provide misleading results because the strong cation exchange capacity of some extractants may induce pH changes and thereby significantly change metal solubility.