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Characteristic / Bentonites

North-Bohemian bentonites are mined and processed since 1953. In 1969 based on geological survey and evaluation of raw material resources our factory in Obrnice near Most was put in operation. Its production secured the whole of foundry industry in that time ČSFR. The quality of input raw material, its huge reserves and implementation of modern technological processes brought KERAMOST, Plc. at the level of leading European producers of processed bentonites.
In course of further development the use of bentonites was extended into the area of drying agents, re-cultivating materials for coal pit heaps and sand soils, fillings of water clarifiers, pet-care goods as cat-litters and into many other activities. Production of building and geological bentonites series G provides reliable material for grouting, drilling fluid and many other industry branches operating with bentonite suspensions. The importance of North-Bohemian bentonites increased in connection with exploiting their properties for building waste materials depots. They area applied either directly as a mineral seal or as a component in mixture with other soils. Herewith they prove invaluable services to environment protection.
An export to a lot of European countries for many years confirms stable production and row material reserves. Co-operation with Czech and European experts secures dynamic development of assortment of bentonite products in conformity with the world-wide trend and customers’ requirements.

Non-activated bentonites

This category is represented by dehydrated and ground natural calcareous-magnesium bentonites being originated mostly in mineral districts of northern Bohemia.
BENTONIT 75 is a quality bentonite suitable for preparation of moulding mixtures for castings with short casting time of max. 15 sec. It is especially suitable also for activating of filling moulding mixtures.
It can be further used as a flocculation heavy medium by waste water purifying, buffer for improving soil imperviousness, retaining of moister and nutrients in soil, powder extinguishers, thickening agents for farm waste and dung, plastification additive in mortars, facades and ceramic masses, additive to granulated fodder.

Activated bentonites

This bentonites are produced from selectively exploited raw materials, homogenized, carefully dried and ground. Sodium carbonate is added to naturally damp mined bentonite in pug mills. The whole production process is carefully controlled and managed. Activated bentonites are suitable for preparation of pattern and unified moulding mixtures for all kinds of alloys.
Further use as: plastification additive to mortars, concrete and ceramic masses, anti-crusting additive to fertilizers, binding agent to fodder granules and ore pellets, thickening agent to agricultural waste, buffer for increasing of soil imperviousness.

ČSN EN ISO 14001 and ČSN EN ISO 9001

Bentonit manufacturing is subject to Quality Management System as per ČSN EN ISO 9001 and to Environmental Management System as per ČSN EN ISO 14001.


By ČSN 72 1077 and by internal regulations.


Services for our customers are free of charge. We analyze facing sands and offer consultations. We can recommend the most suitable bentonite product for your foundry.

Storage life

Unlimited in a dry place.

Packaging and shipping

Quality guarantee

The guaranteed parameters are stated on the catalogued material sheet of the product and form an integral part of the purchase.

Separation agent

This product is made of natural materials, so minor divergences from the properties given in the technical documents may occur.

Average chemical analysis

Chemical content
Content of montmorillonit 65,0 - 80,0 %
SiO2 50,0 - 57,0 %
Al2O3 15,7 - 17,3 %
Fe2O3 8,8 - 17,3 %
FeO 0,1 - 1,0 %
MnO 0,1 - 0,3 %
MgO 2,5 - 3,5 %
CaO 1,7 - 3,1 %
Na2O 0,1 - 0,4 %
K2O 0,3 - 1,2 %
Li2O 0,1 %
P2O5 0,1 %
H2O+ 5,3 - 6,3 %

Attached documents

Safety data sheet - Non-activated bentonite
Safety data sheet - Activated bentonite

Related links

Video - production of bentonite

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