The degradation behaviour of a 4.8 mm thick elastomeric bituminous geomembrane (BGM) immersed in pH 0.5, 9.5, and 11.5 synthetic mining solutions is examined over 26 months at 22, 40, 55 and 70°C. The low pH solution simulates the leach solutions found in copper, nickel, and uranium heap leach pads while the two high pH solutions simulate the chemistry and pH found in gold and silver heap leaching facilities. The mechanical, rheological, and chemical properties are examined at different incubation times to assess the degradation in the BGM at different temperatures. It is shown that the degradation rates of all properties are faster in pH 11.5 and 9.5 than in pH 0.5. Additionally, the BGM started to exhibit degradation in its mechanical properties even with a slightly degraded bitumen coat in all the mining solutions at elevated temperatures. The time to nominal failure of the BGM is predicted at different field temperatures using Arrhenius modelling. Due to the relatively fast degradation in the mechanical properties of the BGM, especially at temperatures above 50^oC, the tensile strains in the BGM in the field should be limited so it can meet the required liner design life of heap leaching applications.

中文翻译：

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堆浸垫应用中沥青土工膜 (BGM) 的化学耐久性

在 22、40、55 和 70°C 的 26 个月内，研究了浸入 pH 0.5、9.5 和 11.5 合成采矿溶液中的 4.8 毫米厚弹性沥青土工膜 (BGM) 的降解行为。低 pH 溶液模拟铜、镍和铀堆浸垫中的浸出溶液，而两种高 pH 溶液模拟金和银堆浸设施中的化学和 pH 值。在不同的孵育时间检查机械、流变学和化学性质，以评估 BGM 在不同温度下的降解。结果表明，所有性能的降解速率在 pH 11.5 和 9.5 下比在 pH 0.5 下更快。此外，BGM 开始表现出其机械性能的下降，即使在高温下所有采矿溶液中的沥青涂层略有下降也是如此。使用 Arrhenius 模型在不同的现场温度下预测 BGM 标称失效的时间。由于 BGM 的机械性能退化相对较快，尤其是在温度高于 50^o C，应限制现场 BGM 中的拉伸应变，以便满足堆浸应用所需的衬里设计寿命。