Bentonite is a clay mineral formed from the volcanic ashes which represents extraordinary properties widely used in a daily life and in the numerous of industries. The basic constituent is montmorillonite the mineral from the smectite group. According to the world standards the mineral clay with higher content of montmorillonite than 75 % is called bentonite.
Bentonites are composed of complexed microcrystalline and laminar molecular internal structure with very small and elongated crystals.
Characteristic property of bentonite is remarkable ability of massive sorption of water. It causes the loosness of the structure and creates dispersion having colloidal size of particles. Particulary sodium bentonite has strong s w e l l i n g properties on account of the high hydration degree of sodium ions - swells over a dozen times its dry size when wetted by water.
Foundry is one of the largest consumer of sodium bentonite as a b i n d e r for preparation of moulding mixes for the production of iron, steel and non-ferrous castings.
Sand particles are clumping whereas bentonite is softened by the water due to its high aggregation capacity. This feature is as well used in the production of i n s u l a t i n g materials.
Properly processed and enriched bentonites are used in various branches of industry. Construction industry applies bentonite for performance of watertight screens (diaphragm walls).
Production of hydroinsulating materials is based on strong colloidal properties of bentonite causing that its volume increases several times when coming into contact with water. Hybrid membranes are based on bentonite protect landfills, water works and underground building objects such a tunnels, dams against ground water. Application of special tapes s e a l i n g joints rising during successive stages of concrete works. Also linings for sealing swimming pools, lagoons or sludge and retention tanks are based on bentonite.
Bentonite due to its viscosity and plasticity is also used in cements and mortars. In pharmacy, bentonite due to its sorption functions is used as plasticizer and filler in production of cosmetic creams, ointments, pills and tablets. Personal care product such as mud packs, sunburn paint, baby and facepowders and face creams may all contain bentonite. In medicine, bentonite is used as an counterpoison in heavy metal intoxication.
Due to its thixotropic properties, bentonite acts as a thickening or suspension agent in high build solvent and waterborne paints.
High sorption capacity and high level of cation exchange are basic properties useful in production of feeding stuffs. It gives the favourable effect in alimentary canal causing better absorption of unorganic additives consisting of nitrogen for protein synthesis and increase przyswajalność(?) of fodder ingredients.
Therapeutic function of bentonite is also applicable in case of animal,s dysyntery. Bentonite in mixture with other elements causes demission of disease symptons. Food industry uses bentonite for cleaning, decolourization and stabilization of vegetable and animal fats and oils. In beverage such a wine, cider and mineral water bentonite is applied for clarification, beer stabilization and for products like honey, sugar bentonite is used as a cleaning and clarification agent.
Other field of application is bentonite-based hygienic litter (cat litter) due to high absorption of animal refuses by forming clumps which can be easily removed and leaving the remaining product intact for further use. In papermaking imdustry bentonit improves the efficiency of conversion of pulp into paper and improves the quality of the paper.