Gravel represents an important natural resource in the construction industry and is washed and separated in treatment plants prior to use in the building and construction industry.

There, it is used as an aggregate in concrete, for bulk in earthworks, as well as for rail track ballast in railway construction. Pure gravel has a large pore volume and is therefore suitable also as a filter layer for drainage in the moist subsoil due to its high water permeability. Its property of high water permeability also makes it an aquifer. Since gravel does not contain any plant nutrients, as opposed to humus, and since surface water seeps away quickly, only sparse vegetation can grow on it (nutrient-poor grassland).

A treatment plant serves to treat raw materials such as coal, ore as well as natural stone in order to modify their material composition and consistency such that further industry applications become possible. Thus, for example, hard coal or iron ore are separated from undesired components that were mined along with it. The treatment work step takes place between mining or quarrying of the raw material and its processing. To reduce transportation costs, the volume to be transported is strongly reduced by performing the processing steps near the mining areas.

Natural stone, gravel and sand

The raw materials gravel and sand as well as natural stone (such as limestone and gypsum) exists contaminated with impurities in nature, or in undesired composition ratios and must therefore be processed. Further applications such as for example in the production of concrete require the separation of aggregates into separate fraction groups.