In: Civil Engineering
Describe a “windrow” and its purpose in mining.
Define Windrow.
A windrow is a row of cut (mown) hay or small grain crop. It is allowed to dry before being baled, combined, or rolled. For hay, the windrow is often formed by a hay rake, which rakes hay that has been cut by a mowing machine or by scythe into a row, or it may naturally form as the hay is mown. For small grain crops which are to be harvested, the windrow is formed by a swather which both cuts the crop and forms the windrow.
By analogy, the term may also be applied to a row of any other material such as snow, earth or materials for collection.
Windrow composting is a large scale vermicomposting system where garden and other biodegradable waste is shredded, mixed and windrowed for composting.
USE IN MINING
Windrows along road edges are normally a standard safety feature at open pit mines. They are typically trapezoidal mounds used to redirect wandering vehicles on the haul road or to absorb the impact energy if the vehicle hits the windrow.
A typical design uses trapezoidal windrows along any road edge where the drop off exceeds 2m. The following items should be considered when designing the windrows:
The standard batter angle for these structures, is 60°. A width of 2m across the top, which is crowned with a crossfall of 2%, is specified. Crossfall across the top is important to prevent pooling of water on the surface, seepage into the windrows and, eventually, weakening of the structure due to water infiltration. Windrows should be kept clean from jagged rocks capable of cutting tyres.
Windrows are an effective guard against the severe consequences of a runaway vehicle. The standard design provides enough strength and height so that in the event of an uncontrolled vehicle, a serious accident may be avoided.
Typical Windrow Design