In addition to protecting the ground from seepage with buried liners, mining facilities need to consider stopping rain from infiltrating heaps of raw material. Leaching heaps use the natural flow of water to loosen and carry particles of metal or minerals out of the crushed rock material and into the pad below where it can collect. Building the pad from an impermeable mining geomembrane isn’t enough if the heap is regularly flushed with too much rainfall. This creates a flooding situation in which valuable ore and minerals runs up and out of the pad by overflowing its sides. Maintain a steady leaching process and prevent these unnecessary losses by considering the temporary liners known as mining heap raincoats.
Short vs Long-term Use
Raincoat liners (RCLs) are generally used only for short-term processing. They’re pulled over the heap when it’s wet enough and needs no more water, then removed again if the pile dries out and stops releasing a steady supply of leachate. Since many mining heaps are dozens of feet tall, small cranes or pulley systems are generally used to place and remove these liners. This means a tough and tear resistant geomembrane is required that can take the wear. Choose a reinforced product for this kind of short-term use since the extra durability will help the raincoat liner last longer before needing replacement.
Surplus Water Control
These liners are generally used for controlling the amount of surplus water added to the heap as it leaches. Heaps are often soaked with reused wastewater or a specific mix of chemicals to achieve processing goals with difficult raw materials. If too much rainwater washes or falls into the heap, it dilutes the water and risks the chance of flooding the collection system. Temporary covers are a better idea than permanent ones in most cases since it’s possible dry conditions will call for exposing the pile again so it can be easily soaked from the top down.
Selecting a Cover Material
Covers, whether temporary or permanent, must have the same kind of chemical resistance required by the liners used for these leaching heaps. This means that it’s usually a good choice to use the same materials for both. If it’s necessary to create a vapor barrier by sealing the liner tightly to the cover, this is much easier when both layers are made from a material like RPE. Getting a reliable seal between a leach pad and cover is tricky when using two different polymers. Since both layers share many of the same requirements for durability and stretch resistance, matching products like ArmorPro and ArmorCover from BTL Liners are good choices.
