{"id":3369,"date":"2025-10-09T16:37:18","date_gmt":"2025-10-09T14:37:18","guid":{"rendered":"https:\/\/www.atarfil.com\/?p=3369"},"modified":"2025-10-10T11:56:30","modified_gmt":"2025-10-10T09:56:30","slug":"not-all-leachates-are-equal-why-mining-demands-chemically-tailored-geomembranes","status":"publish","type":"post","link":"https:\/\/www.atarfil.com\/en\/not-all-leachates-are-equal-why-mining-demands-chemically-tailored-geomembranes\/","title":{"rendered":"Not All Leachates Are Equal: Why Mining Demands Chemically-Tailored Geomembranes"},"content":{"rendered":"\n

When designing containment systems for mining, engineers often begin with GRI-GM13 \u2014 the long-standing benchmark for HDPE geomembranes. But as Warren Hornsey, Scheirs, Will Gates, <\/strong>and Malek Bouazza<\/strong>\u00a0demonstrated in their landmark paper \u201cImpacts of Mining Solutions\/Liquors on Geosynthetics\u201d<\/em>, the realities of chemical exposure in mining environments stretch well beyond what GM13 was ever intended to cover.<\/p>\n\n

Their research compared the performance of geomembranes and other geosynthetics when immersed in various acidic, alkaline, and metal-laden liquors\u00a0typical of heap leach and tailings facilities. The findings remain some of the clearest evidence that site-specific conditions directly determine polymer performance and lifetime.<\/strong><\/p>\n\n

Key findings from the research<\/strong><\/h2>\n\n
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  1. Mining solutions are far more aggressive than MSW leachates.<\/strong> Liquors from gold, copper, and nickel operations routinely reach pH values below 2, with sulphate concentrations above 20,000 mg\/L, and temperatures nearing 70 \u00b0C.<\/strong> Under these conditions, oxidation and stress crack initiation accelerate dramatically \u2014 particularly at welded seams and wrinkles under sustained load.<\/strong><\/li>\n\n\n\n
  2. Standard stabilisers can fail in strong acids.<\/strong> The paper identified that HALS<\/strong> (hindered amine light stabilisers), widely used in polyolefins, lose effectiveness in low-pH environments. Once deactivated, antioxidants are consumed rapidly, leading to chain scission<\/strong> and early embrittlement.<\/strong><\/li>\n\n\n\n
  3. Organic solvents can swell and weaken HDPE.<\/strong> In solvent extraction circuits where kerosene or other organics are present<\/strong>, HDPE can experience swelling and localised softening<\/strong>\u00a0\u2014 creating wrinkles and stress zones<\/strong> that promote cracking.<\/li>\n\n\n\n
  4. Brines and high-pH residues degrade materials differently.<\/strong> Highly alkaline solutions, such as Bayer liquors<\/strong>, attack polymers and even the mineral components of GCLs<\/strong>. The paper emphasised that oxidative ageing<\/strong> pathways differ completely\u00a0between acidic and basic chemistries.<\/li>\n\n\n\n
  5. MSW test data doesn\u2019t represent mining exposure.<\/strong> Immersion studies revealed that antioxidant depletion<\/strong> in MSW leachate can be two to four times faster<\/strong>\u00a0than in acidic solutions \u2014 proof that there is no universal ageing model<\/strong>. Longevity must be predicted using chemistry-specific testing.<\/strong><\/li>\n<\/ol>\n\n

    The real takeaway: formulation must follow exposure<\/strong><\/h2>\n\n

    The core message from Hornsey et al. is not simply that geomembranes degrade \u2014 it\u2019s that the mechanism and rate of degradation depend on the environment.<\/strong> Two sites may specify the same GM13 liner and achieve entirely different outcomes depending on:<\/p>\n\n