Though there are numerous geomembranes used across all industries, only a few of these will work well in mining environments. If you select the wrong material, it can cost more, break down early, or leak, which can have disastrous effects on community health, safety and profitability. To minimize the maintenance you will need to perform across the mine's lifespan, you'll need to start by choosing the best geomembrane liner material. Generally speaking, reinforced polyethylene (RPE) is considered to be one of the best options available on the market for the mining industry and is quickly becoming the standard by which other geomembrane polymers are judged. Knowing the best characteristics of each type of liner, the right polymer, the right texture, or reinforcement can make a big difference in how long your liner lasts, as well as how you'll be installing the liner in its final location. So, selecting the right one for the job is important. Let's take a look at the polymers commonly used in liners for mining reclamation and rehabilitation.
Geomembranes come in over a dozen different polymers that are commonly available. Each polymer has a number of further divisions based on the specific need for particular plasticizers and additives. To start, you'll want to find the best general polymer category for your needs, then determine which options to go for based on your project's specifications. Here are six of the most common polymer types used in mining geomembranes.
- High-density polyethylene (HDPE): Though this is a widely available durable material, it's much more prone to crack under stress than other polyethylene polymers. It does provide good chemical resistance but is less UV resistant than RPE. The welds in the material tend to be fairly strong, providing reliable seams, but it also has poor resistance to punctures and can expand and contract a lot under thermal stress from hot wastewater applications. For these reasons, it's not a good option by itself for active mining processes, but if handled properly, can work well in reclamation and rehabilitation projects that did not initially have progressive mining reclamation and rehabilitation in place.
- Polyvinyl chloride (PVC): Also commonly available, PVC is more flexible than HDPE liners, but it lacks the durability and chemical resistance needed for long-term mining use. It does resist wrinkling because of its overall flexibility, but has poor tear resistance and durability, especially in rocky soils. In most formulations, it isn't as UV resistant as most options and will break down when left exposed to sunlight. It also doesn't deal well with very high or low temperatures. These qualities make it a poor choice for mining operations and pond linings.
- Chlorosulfonated polyethylene (CSPE): If you need a specific type of chemical resistance, this formulation of polyethylene polymers is a good option, but it's not very popular in the mining industry because few of its advantages overcome its disadvantages. It has low tensile strength, making it a bad choice for leach pads and other high-weight situations, as the force of ore or sediment will cause many tears and punctures to form. Unless you need it for a specific chemical resistance, it's a poor choice in mining environments, and it should be paired with another geomembrane to provide solid protection.
- Flexible polypropylene (FPP): Though it's easy to manufacture into larger lining sizes, FPP can be harder to find and is usually more expensive than other options for liner materials. It also has a serious drawback - it's not resistant to hydrocarbons, such as natural gas, hydraulic fracturing, and petroleum operations, or mining that use these materials in regular operations. Because of its high cost and poor resistance to hydrocarbons, you'll probably want to pass on this one unless it's for very specific reasons, both in active operations as well as reclamation and rehabilitation processes.
- Low-density polyethylene (LDPE). When you need geomembranes with a good combination of flexibility and chemical resistance, LDPE works well in a number of situations. However, it's still not the top pick for most mining operations because of its lower UV resistance and lower chemical resistance. Though it won't wrinkle as easily as stiffer membranes, especially if you're working with a reinforced product, its low density makes its durability poor, making it a poor choice for mining where rough ore and sediment will wear out the liner and cause punctures and tears to appear. For this reason, it can work with other geomembranes but is not usually installed on its own in the mining industry unless used under very stable conditions.
- Reinforced polyethylene (RPE): To gain the best possible performance in your reclamation and rehabilitation process, RPE geomembranes provide the best performance. With the highest levels of UV and chemical resistance, the material combined both the flexibility of LDPE and the strength of HDPE along with reinforcement to resist wrinkles, conform with the flexibility to unusual curves in your design, superior strength, and outstanding tear resistance. It can be used as the liner for your mine while in operation, then as a cap seamed to the top once you've closed operations. Thus, providing you with a single, easy-to-use material for all of your mining projects. This is why it's becoming a solid industry standard over time.
Another aspect to take into account for mining geomembranes is whether they are woven or non-woven. Virtually all geomembranes used in mining are non-woven, usually of an extruded nature to provide the best levels of impermeability for your project. Geotextiles are commonly woven, which allows small openings that let water pass through, making them good options for stabilization as rehabilitation rolls forward, but not during production operations. Woven and matted geotextile fibers virtually never offer the level of impermeability to qualify as geomembrane liners, especially for water-bearing structures such as ponds or canals. To contain potentially contaminated water or vapor, you'll want to work with an extruded product to get the best benefits.
Not every geomembrane that you come across will work well for your purposes in the mining industry, with some designed specifically for agriculture, irrigation or recreational purposes because of their particular characteristics. If you're looking for an RPE geomembrane product that will bear up well to the heavy challenges of the mining industry, BTL Liners has an extensive selection of options and is ready to help you find the right one for your specific application.