The degradation of a HDPE geomembrane in heap leaching environments is evaluated using immersion tests at five temperatures. The incubation solutions had a pH of 9.5, 11.5, and 13.5, relevant to gold and silver pregnant liquor solutions. After 9.3 years, the geomembrane's mechanical properties had reached nominal failure at 95, 85, and 75 °C in all three solutions. It is shown that the pH 13.5 solution had the greatest effect on the antioxidant depletion (Stage I) and polymer degradation (Stage III), but was the least aggressive to initiate the degradation (Stage II) compared to the pH 11.5 and 9.5 solutions. Overall, the time to nominal failure (time to 50% of the initial or specified property value) in pH 13.5 was slightly shorter than the pH 9.5 and 11.5 solutions. Based purely on immsersion tests, the time to nominal failure of this specific geeomembrane at 30oC is predicted to be 150 years in the pH 9.5 and 11.5 solutions, and 140 years in the pH 13.5 solution. Assuming a good liner design that limits the tensile strains in the GMB, nominal failure in a composite liner configuration is predicted to exceed 260 years at 30 °C and the expected value could exceed 1000 years at 10 °C.

中文翻译：

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对用于不同高 pH 采矿应用的 HDPE 土工膜衬垫的降解进行了 9 年的研究


使用五个温度下的浸泡测试来评估 HDPE 土工膜在堆浸环境中的降解。孵育溶液的 pH 值为 9.5、11.5 和 13.5，与金和银孕液溶液相关。9.3 年后，在所有三种溶液中，土工膜的机械性能在 95、85 和 75 °C 时均达到标称失效。结果表明，pH 13.5 溶液对抗氧化剂消耗（I 阶段）和聚合物降解（III 阶段）的影响最大，但与 pH 11.5 和 9.5 溶液相比，引发降解（II 阶段）的侵略性最小。总体而言，在 pH 13.5 中达到标称失效的时间（达到初始或指定特性值的 50% 的时间）略短于 pH 9.5 和 11.5 溶液。仅根据阻抗测试，预计这种特定地质膜在 30oC 下达到标称失效的时间在 pH 9.5 和 11.5 溶液中为 150 年，在 pH 13.5 溶液中为 140 年。假设良好的衬垫设计限制了 GMB 中的拉伸应变，则复合衬垫配置的标称失效预计在 30 °C 时将超过 260 年，在 10 °C 时预期值可能超过 1000 年。