Strip mining is a type of surface mining which involves the removal of a thin layer of material known as an “overburden” to access buried deposits of useful minerals. This type of mining is only effective in areas where mineral deposits are very close to the surface, making it feasible to quickly and easily remove the overburden to get to them. Classically, strip mining is used to mine tar sand and coal. This technique is also referred to as open cast, open cut, or stripping.
In this technique, the first step is the removal of trees, shrubs, and structures on the area to be mined, a process which is usually accomplished with heavy duty bulldozers. Next, holes are drilled for the placement of explosives, which will loosen the overburden so that it can be removed by earthmoving equipment. Some of the largest industrial equipment in the world is utilized in strip mining, with the overburden being piled next to the site or hauled away for disposal, depending on how the mine is being handled. Once exposed, the minerals can be extracted.
In many cases, mining operations work a little like mowing the lawn: one row at a time. When this technique is used, mined strips are used to hold the removed overburden from the neighboring row, so that it does not have to be hauled off site. This technique also makes it easier to control stability and conditions at the mine, as only a small segment is being actively worked at any given time.
Area strip mining is designed for relatively flat areas of ground which can be worked quickly and easily. The main concern in flat areas tends to be containment and proper disposal of overburden, to keep the site under control. In contour strip mining, strips are dug out around the contours of a mountain, and miners must be more careful to avoid collapses and other problems which can cause injuries or deaths.
As one might imagine from the description, strip mining can be extremely disruptive. The unwanted overburden often consists of nutrient rich topsoil which may have been built up over centuries, and when the overburden is carelessly disposed of, this constitutes an enormous waste. Even when the overburden is replaced, it can take decades or longer for plant and animal life in the area to recover. Pollution can also become an issue, depending on what is being mined and whether it is being processed on site.