1.Bentonite Properties and Applications
Bentonite is a clay mineral with montmorillonite as the main component. Its chemical composition is quite stable and it is known as the “universal stone”. Montmorillonite is a 2:1 type silicate mineral containing crystal water, consisting of two layers of silicon-oxygen tetrahedron sheets connected at the same top and one layer of aluminum (magnesium) oxygen (hydrogen-oxygen) octahedron sheets connected at the same edges.
It is one of the minerals with the strongest variation in crystal structure among the clay mineral family. Under watery conditions, the crystal structure of bentonite is very fine. This special fine crystal structure determines its many excellent properties, such as high dispersion, suspension, swelling, adhesion, adsorption, cation exchange, etc.
Therefore, bentonite is known as the “thousand-purpose mineral” and is widely used at home and abroad in metallurgical pellets, casting, drilling mud, textile printing and dyeing, rubber, papermaking, fertilizers, pesticides, improved soil, desiccants, cosmetics, toothpaste, Cement, ceramic industry, nanomaterials, inorganic chemicals and other fields.
2. Conventional application fields of bentonite
① Bentonite for casting is the largest user of sodium bentonite.
Sodium bentonite is popular in the foundry industry for its good reusability and high wet compressive strength. Due to its good plasticity, it can prevent sand inclusion, scarring, falling blocks, sand mold collapse and other phenomena in castings. In addition, its strong formability and high cavity strength make it convenient for the metal industry to cast wet or dry molds, making it the first choice for precision castings. Molding sand binder.
② Bentonite for drilling mud is the second largest user of sodium bentonite.
When carrying out oil and gas drilling and other tasks, mud is used to cool the drill bit, remove debris, protect the well wall and balance the ground pressure. Bentonite has strong water absorption, can absorb water equal to 8 times its own volume, expands 10 to 30 times in volume, is suspended and gelled in aqueous solution, has good dispersion and large slurry output, so it is the best choice for manufacturing drilling mud. Ideal material.
③ Bentonite desiccant: Bentonite desiccant has the functions of adsorption activity, static dehumidification and odor removal.
It is widely used in dry air sealing of optical instruments, electronic products, medical health care, food packaging, military products and civilian products. Compared with silica gel, it has the advantages of low price, fast adsorption speed and low preparation cost. Compared with other types of desiccants currently on the market, it not only has fast adsorption speed, but also has high adsorption capacity and is non-toxic, odorless, non-contact corrosive, and non-environmental pollution. It is especially used in food packaging and does no harm to the human body.
④ Bentonite for iron ore pellets is the third largest user of bentonite.
Bentonite for iron ore pellets is one of the important accessories in the modern metallurgical industry. The concentrated iron powder is mixed with an appropriate amount of bentonite and water, and then rolled into balls in a pelletizing machine. It is then dried, preheated, and roasted to form a high-strength pellet. The pellets are then smelted.
In addition to traditional application fields, bentonite will have great development in agricultural feed, environmental protection, organic bentonite adsorption, decolorization, and chemical catalysts.
