Heap Leach systems generate aggressive liquors over large footprints that present significant risk to traditional earth lining systems. The consistency of a Quality Controlled Geomembrane that can be pre-qualified with specific site testing presents the optimum lining solution that can be demonstrated with suitable longevity. Once qualified by immersion testing, the geomembrane should be chosen in consideration of the stresses created by differential subgrade settlement, and the point load impacts of the granular ore above during installation and over the long term.
Geofabrics Geomembranes can include Polyethylene liner, specialist polymer Cooley Liners or Terenap Bituminous Geomembranes according to the site chemistry and robustness required.
Geosynthetic Clay Liners
The traditional heap leach pad liner is a composite soil and geomembrane liner system but a Geosynthetic Clay Liners (GCL) presents as a technically better composite liner than standard soils. These products are select polymer geotextile outer layers needled punched to each other to ensure shear strength with a uniform core of premium quality powdered sodium bentonite to provide the hydraulic barrier. Geofabrics ELCOSEAL® GCL’s can reduce contaminant transport and help achieve environmental compliance but only if the bentonite contained in the GCL is pre-qualified with the leach chemistry to ensure maximum performance.
Geotextile filters - Geofabrics bidim® or Texcel
The choice of Geotextile will depend on the pregnant liquor impacts on the polymer, and mechanical damage risks of the project stresses and environment.
The first choice to maximise costs is a bidim® polyester, continuous filament, non-woven, needle-punched geotextile, with a high strength to mass ratio. bidim® is manufactured to the highest quality control standards from both virgin and recycled polymer depending on the site chemistry.
Texcel Staple Fibre Geotextiles are an alternative that can be manufactured in both Polyester and Polypropylene according to the damage risks, but also according to the site chemistry risk on polymer degradation. Testing the Geotextile to match the project conditions is a must for Heap Leach applications, the Geofabrics GRID Laboratory links has techniques to ensure that the Geotextile can serve as a filter, protection layer to the environment over the project design life.