Many industries start out producing large volumes of what appears to be waste material, only to discover many uses for it as time goes by. This is true for surface mining as well with the production of overburden. While this mix of clay, sand, and rock doesn’t contain enough ore or oil to be worth processing for the main product of the mine, it is still surprisingly valuable for alternative purposes. Identifying nearby demand for fill or aggregate material can help add a small bump to profit margin of the project and thereby increases its success. Before consigning overburden to dumping in empty valleys or refilling the mine pit alone, consider these potential uses for the material.
Reprocessing
The first step in making good use of overburden material is to process is for ore or oil if it is worth the energy. Grading steps that sort overburden into different levels of value will limit the amount of processing needed. The lowest grades of overburden are unlikely to be worth the energy and effort, so they should be directed to other uses or stored for remediation only. Depending on the type of ore, coal, or oil being harvested by the mining operation, it may be necessary to sort the overburden material by its depth of excavation, the weight of the grains, or other measurable statistics.
Brick Production
Due to its high mineral and sand content, oil sand overburden in particular can be put to good use in the production of various types of bricks. Ceramic bricks are produced in countries like Russia with the help of overburden materials and similar waste products from mining projects. These bricks are strong, durable, lightweight, and considered defect-free despite the mixed nature of the crushed material.
Construction and Roadwork
Depending on the specific bitumen content of the overburden material, it is likely useful for one or more construction techniques. High bitumen materials are often used for road surfacing if they’re not up to reprocessing. Low bitumen sands and gravel are ideal for other more general building purposes like mixing into concrete, serving as a rough base for supporting roadways, and even preparing sites for large scale paving. Almost any construction project that demands a physically stable and unsorted fill material may provide demand for the overburden of a mine.
Contours for Embankments and Ponds
Contouring is a challenging site management task that requires both careful grading and long-term efforts to stabilize the exposed surface of soil. When it is not possible to cover embankments, dykes, and berms with live plant cover with grass, it is essential to use a resilient surface cover that isn’t lost to erosion over time. High bitumen overburden materials often settle together over time to create a sort of asphalt-like skin that can serve as contour reinforcement in a wide variety of situations. Depending on the intended use for the water feature, it may be possible to stabilize the sides and banks of a pond with this material as well before applying an impermeable geomembrane like a liner from BTL Liners.
Remediation
The most common use for the large volumes of overburden produced by a surface mine is to remediate and reclaim the area where it was first removed. Putting the sand, rock, and clay back where it came from helps rebuild the level of the soil so that plant life can return. However, the type of overburden determines exactly what kind of plant life can be supported by it. For example, studies found that brown sandstone removed from Appalachian coal mining sites supports over 65 different plant species native to the region. In contrast, grey sandstone layers from the same site only supported 7 species. Making sure to keep the right material set aside for the final cover can make a big difference in how quickly the site reestablishes a natural plant layer.
No matter the final use intended for the overburden, it must be stored safely until it is time to deliver it. Even keeping it on site to use for remediation and recovery means building a secure containment area to ensure there’s little to no environmental impact. Line the storage area for all overburden storage areas, but especially those set aside for reprocessing, with impermeable liners from BTL Liners. Our geomembranes help make the most of the material by keeping it in place and preventing loss for months or even years as the mine operates.
