Bentonite: a mineral for one thousand uses
Foundry
Bentonite is used as a bonding material in the preparation of moulding sand for the production of iron, steel and non-ferrous casting. The unique properties of bentonite yield green sand moulds with good flowability, compactability and thermal stability for the production of high quality castings.
Bentonite is used as a binding agent in the production of iron ore pellets. Through this process, iron ore fines are converted into spherical pellets, suitable as feed material in blast furnaces for pig iron production, or in the production of direct reduction iron (DRI).
Bentonite in civil engineering applications
is traditionally used as a thixotropic, support and lubricant agent in diaphragm
walls and foundations, in tunnelling, in horizontal directional drilling
(HDD) and pipe jacking.
Bentonite, due to its viscosity and plasticity, is also used in Portland
cement and mortars.
Environmental
MarketsBentonite's adsorption/absorption properties
are very useful for wastewater purification.
EU directives recommend low permeability soils, which naturally should contain
bentonite, as a sealing material in the construction and rehabilitation
of landfills to ensure the protection of groundwater from the pollutants.
Bentonite is the active protective layer of the Geosynthetic Clay Liners.
DrillingAnother conventional use of bentonite is as a mud constituent for oil- and water- well drilling. Its role is mainly to seal the borehole walls, to remove drill cuttings and to lubricate the cutting head.
Bentonite is utilized in the removal of impurities in oils where its adsorptive properties are crucial in the processing of edible oils and fats (Soya / palm / canola oil). In drinks such as beer, wine, mineral water and in products like sugar or honey, bentonite is used as a clarification agent.
AgricultureBentonite is used as an animal feed supplement, as a pelletising aid in the production of the animal feed pellets, as well as a flowability aid for unconsolidated feed ingredients such as soy meal. It is also used as an ion exchanger for improvement and conditioning of the soil. When thermally treated, it can be used as a porous ceramic carrier for various herbicides and pesticides.
Pharmaceuticals,
Cosmetics and Medical MarketsBentonite is used as filler in pharmaceuticals
and due to its absorption/adsorption functions, allows paste formation.
Such applications include industrial protective creams, calamine lotion,
wet compresses, and anti-irritants for eczema.
In medicine, bentonite is used as an antidote in heavy metal poisoning.
Personal care products such as mud packs, sunburn paint, baby and face powders,
and face creams may all contain bentonite.
Laundry detergents and liquid hand cleansers/soaps rely on the inclusion of bentonite, in order to remove the impurities in solvents and to soften the fabrics.
Due to its thixotropic properties, bentonite and organoclays function as a thickening and/or suspension agent in varnishes, and in water and solvent-based paints. Its adsorption properties are appreciated for the finishing of indigo dying cloth, and in dyes (lacquers for paints & wallpapers).
When used for cat litter, bentonite posses
an advantage because of its ability to absorb refuse by forming clumps (which
can be easily removed, leaving the remaining product intact for further use).
Paper
Bentonite is crucial to paper making, where
it is used in pitch control (i.e. absorption of wood resins that tend to
obstruct the machines), to improve the efficiency of the conversion of pulp
into paper, and to improve the quality of the paper. Bentonite also offers
useful de-inking properties for paper recycling. In addition, acid activated
bentonite is used as the active component in the manufacture of carbonless
copy paper.
Bentonite is stabilizing fine-, heavy- and technical- ceramic products. It is a used as antisettling agent in engobes and glazes, as fluxing agent, and as plasticizer.
Chemically modified clay catalysts find application in a diverse range of duties where acid catalysis is a key mechanism. Most particularly, they are employed in the alkylation processes to produce fuel additives.
