Bentonite powder is derived from bentonite, a type of clay - like rock. Its main component is the clay mineral montmorillonite, which accounts for 85 - 90% in high - quality bentonite. This mineral gets its name from the Montmorillonite deposit in southern France.
Bentonite is formed by the alteration of volcanic ash, mainly composed of smectite minerals. After being quarried from deposits, the extracted bentonite, despite containing about 30% moisture, is solid. It is first crushed. Depending on the final use, it may be milled, sieved, or go through further processing. For special applications, gangue minerals are removed through purification. Additionally, it can be treated with soda ash for activation, acids to produce acid - activated bentonite, or organics to create organo - clays.
Bentonite powder can be classified in different ways. Based on the main exchangeable cations, it includes sodium - bentonite (with Na⁺ as the main exchangeable cation, showing high swelling ability in water and forming colloids), calcium - bentonite (dominated by Ca²⁺, having lower swelling ability compared to sodium - bentonite), and transitional or mixed - type bentonite (with both Na⁺ and Ca²⁺, showing medium swelling ability).
It has a series of excellent properties. Its swelling property is remarkable, especially for sodium - bentonite which can absorb several times its own weight of water, becoming gelatinous and sticky. It also shows strong adsorption capacity, capable of adsorbing various substances such as impurities and heavy metal ions. Moreover, it has good ion - exchange properties, with the cation exchange capacity (CEC) of natural montmorillonite in a pH 7 water medium usually ranging from 0.7 - 1.4 mmol/g.
In the foundry industry, bentonite powder is used as a bonding material in molding sand for producing non - ferrous metals, steel, and iron. Its good flowability, thermal stability, and compatibility help to make high - quality castings. In the production of iron ore pellets, it serves as a binding agent, converting iron ore fines into spherical pellets for use in blast furnaces to produce pig iron. In drilling operations, especially in the oil and gas industry, bentonite - based drilling fluids are widely used. These fluids help to cool and lubricate the drill bit, carry cuttings to the surface, and maintain the stability of the borehole wall. It also has applications in the environmental field, such as in water treatment to adsorb pollutants, and in soil improvement projects. In the cosmetic and pharmaceutical industries, its adsorption and thickening properties make it useful in some formulations.
In summary, bentonite powder, with its unique properties, plays a significant role in multiple industries.
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