How are pebbles made

sand is a naturally occurring, unconsolidated sedimentary rock that is composed of individual grains of sand with a grain size of 0.063 to 2 mm. The sand is thus classified between fine gravel (grain size 2 to 6.5 mm) and silt (grain size 0.002 to 0.063 mm). Sand is one of the non-cohesive soils and is an important raw material for the construction, glass and semiconductor industries.

Sand forms a fundamental raw material component in many branches of the economy and is therefore of major economic importance. It is primarily used as a building material in civil engineering, traffic routes and earthworks.
Furthermore, sand is an essential aggregate (aggregate) in building materials such as concrete and mortar, which is also used as an easily malleable compound for decorating the interior and facade of buildings. In construction, a distinction is made between pit sand, broken sand, crushed sand, river sand and sea sand. Quartz-rich sand is also a rust material for cement production.

gravel (from Middle High German kis = coarse-grained stony sand) is a widespread loose sediment. It is a naturally deposited or artificially poured body made of small stones, commonly known as pebbles, ground in flowing waters. The transport in streams or rivers is carried out as ground freight. On the other hand, non-circular or sharp-edged shapes in the geological sense are rubble, as a technical building material of the construction gravel (also broken minerals)

The construction material gravel, which is the most important mass raw material next to sand, is extracted in gravel mining.

Gravel is an important raw material for the construction industry. It is used as an aggregate (aggregate) in concrete, as a bulk material in earthworks. Pure gravel has a pore volume and is therefore also used as a filter layer for drainage in moist subsoil due to its high water permeability. The property of high water permeability also makes it an aquifer.
Since gravel, in contrast to humus, does not contain any nutrients for plants and surface water seeps away quickly, it is only sparsely overgrown by vegetation (poor grassland)

 

Extraction of sand and gravel

In the case of dry extraction, the raw material lying above the groundwater line is picked up by wheel loaders and fed to the processing plant via conveyor belts.

 

Processing of sands and gravel

After the coarse screening (> 32 mm), the material is washed so that components that can be washed off are dissolved and rinsed out. The water required is only fed to the sedimentation tank to separate the fines so that it can be used again. After the washing process, the classification takes place through sieves (0/2, 2/8, 8/16, 16/32 mm).

The different fractions are then poured onto free heaps.