Sand processing. Sand types
Sands (geological material) is unconsolidated sedimentary rock and an artificial material at least 50% of which consists of geological material grains; quartz and other minerals and rock debris 0.05 to 2 mm in size; it contains admixture of aleurite and clay particles. It often consists of almost pure quartz mineral (silicon dioxide).
Sand is the most popular type of mineral raw material. Sand is a mixture of grains of geological material decomposed as a result of weathering as weathering of granite results in formation of sand containing quartz grains, clay particles and granite grains consisting of minerals.
The water carrying sand from highlands to flats rounds grains by means of friction against each other and carries them away.
There are many types of sand. Differences are mainly in terms of content of argillous and slime, and size.
Depending on their origin, sands can be:
- artificial sand is a product obtained as a result of crushing of granites, marble, limestones, slag and other geological materials.
- Natural sand is a loose mixture of grains sized 0.10 to 5 mm formed as a result of destruction of hard rock. Natural sands can be alluvial, deluvial, marine, lake and anemoarenyte. Sands formed as a result of action of water bodies and water courses are more rounded and waterworn.
- Heavy artificial sand is a loose mixture of grains obtained by crushing of hard and dense rocks. The crushed sand grain shape is sharp and surface is rough.
Depending on production method:
- river sand is mortar sand produced in rivers. Its characteristic feature is high purity and absence of any foreign inclusions, argillaceous admixtures and stones.
- washed pit sand is sand produced in a pit by washing with water which results in washing out of clay and slime.
- screened pit sand is screened sand produced in a pit, free of stones and oversized particles. Screened pit sand is widely used in production of mortar for masonry, plasterwork and foundation work. It is also used for preparation of asphalt-concrete mixes.
In terms of sand grain shape and in terms of field all sands are divided into:
- mountain sand – it is at location of its original formation, not processed with flowing water, as a result of which sand grain surface is rough, grain sizes vary, grains are ribbed, the sand contains angular grains, and larger non-destroyed rock lumps occur among sand grains.
- Ground, cellar or ravine sand is only different from mountain sand in that its deposits are covered with alluvia, sometimes earth admixtures occur in it. Both of such sands are valued due to angular grain shape ensuring good adhesion in mortars, but argillaceous admixtures and vegetable earth admixtures occur often in them and deteriorate their quality.
- Marine sand grains are rounded, marine sand is usually finer than river sand and, besides, it contains salts contained in sea water;
- lake sand;
- fluvioglacial sand – sand formed a result of combined action of ice and water;
- eolian sand.
In terms of mineralogical composition the most common sand types are (rock) quartz, glauconitic quartz, feldspathic quartz, micaceous and other types. Quartz sand is considered to be the best SiO2. It is one of the most widely spread rock-forming minerals.
Mortar sand is inorganic bulk material with up to 5 mm grain size. It was formed as a result of natural destruction of hard rocks and it is produced by developing sand and sand and gravel fields with or without any use of special preparation equipment.
The sand density depends heavily on clay contained in it – pure sand density can be 1.3 t/m3, and sand with greater clay and moisture content – 1.8 t/m3.
Different industrial equipment is used for sand processing – sand mills, drying drums for drying sand, vibrating sieves for screening sand with admixtures of larger sizes. The Samara Strommashina plant manufactures all types of sand processing equipment. Our equipment is highly reliable, durable and easy in operation.