Abstract The historical mining and processing of Zn–Pb–V ores at Berg Aukas in northern Namibia left large amounts of various wastes. This study focuses on the mineralogical and geochemical investigation of the V-rich slags issued from the processing of the local ores in the Waelz kiln, which was operational between 1968 and 1980 and left ca. 500 kt of slag deposited on the adjacent dump. A combination of mineralogical methods, bulk chemistry, leaching tests and speciation-solubility modeling was used to understand the binding of the major contaminants (Zn, Pb, V) in the solid phase and their potential release under the changing environmental conditions. The average concentrations of the metal(loid) contaminants in the slags are 3.78 wt% Zn, 3370 mg/kg Pb, 5880 mg/kg V, 767 mg/kg Cu, 578 mg/kg As and 92 mg/kg Sb. The mineralogy is dominated by high-temperature silicates (clinopyroxene, melilite, olivine-family phases) and Zn-bearing phases (willemite, zincite). All the primary silicates and oxides are Zn-rich, but vanadium is mainly concentrated in clinopyroxene (up to 5 wt% V2O3). Metallic Fe inclusions, formed under highly reducing conditions in the kiln, are highly weathered. Secondary Fe(III) (hydr)oxides, corresponding to the main weathering products in the slag, efficiently sequester the metal(loid)s (mainly As and Sb). The EU regulatory leaching tests indicated that the release of the metal(loid) contaminants is quite low at the natural pH (deionized water extract: 8.5–10.4) obtained by extraction in the deionized water and only Sb in all the slag samples exceeds the EU limits for the landfilling of inert waste. The pH-static leaching tests revealed up to 5 orders of magnitude higher release of Pb and Zn under acidic conditions (up to 38% and 63% of their total concentration, respectively), compared to the natural pH. In contrast, V exhibits relatively flat pH-dependent leaching patterns with only

中文翻译：

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来自 Berg Aukas（纳米比亚）Zn-Pb-V 矿石的历史加工的富钒矿渣：矿物学和环境稳定性

摘要 纳米比亚北部 Berg Aukas 历史上对 Zn-Pb-V 矿石的开采和加工留下了大量的各种废物。这项研究的重点是对 1968 年至 1980 年间运营的 Waelz 窑处理当地矿石时产生的富 V 矿渣进行矿物学和地球化学调查。500 kt 炉渣沉积在相邻的垃圾场上。矿物学方法、本体化学、浸出测试和形态溶解度模型相结合，用于了解固相中主要污染物（Zn、Pb、V）的结合及其在不断变化的环境条件下的潜在释放。炉渣中金属（类）污染物的平均浓度为 3.78 wt% Zn、3370 mg/kg Pb、5880 mg/kg V、767 mg/kg Cu、578 mg/kg As 和 92 mg/kg Sb。矿物学以高温硅酸盐（斜辉石、黄长石、橄榄石族相）和含锌相（硅锌矿、锌矿）为主。所有的原生硅酸盐和氧化物都富含锌，但钒主要集中在单斜辉石中（高达 5 wt% V2O3）。在窑内高度还原条件下形成的金属铁夹杂物是高度风化的。二次 Fe(III)（氢）氧化物对应于炉渣中的主要风化产物，可有效隔离金属（类）（主要是 As 和 Sb）。欧盟监管浸出测试表明，在去离子水中萃取得到的天然pH值（去离子水萃取：8.5-10.4）下，金属（液体）污染物的释放量非常低，所有渣样中只有Sb超过欧盟标准惰性废物填埋的限制。pH 静态浸出试验表明，与天然 pH 值相比，酸性条件下 Pb 和 Zn 的释放量高出 5 个数量级（分别高达其总浓度的 38% 和 63%）。相比之下，V 表现出相对平坦的 pH 依赖性浸出模式，仅