Bentonite is a non-metallic mineral with montmorillonite as the main mineral component. The montmorillonite structure is a 2:1 type crystal structure composed of two silicon oxide tetrahedrons sandwiched with a layer of aluminum oxide octahedron. Due to the layered structure formed by the montmorillonite crystal cell, there are certain cations, such as Cu, Mg, Na, K, etc., and the interaction between these cations and the montmorillonite crystal cell is very unstable, which is easy to be exchanged by other cations, so it has good ion exchange properties. Overseas, it has been applied in more than 100 departments in 24 fields of industrial and agricultural production, with over 300 products, so people call it “universal soil”.

Bentonite is also known as bentonite, bentonite, or bentonite. China has a long history of developing and using bentonite, which was originally only used as a detergent. (There were open-pit mines in Renshou area of Sichuan hundreds of years ago, and local people called bentonite soil powder.). It has only been widely used for over a hundred years. The earliest discovery in the United States was in the ancient strata of Wyoming, where yellow-green clay, which can expand into a paste after adding water, was collectively referred to as bentonite. In fact, the main mineral component of bentonite is montmorillonite, with a content of 85-90%. Some properties of bentonite are also determined by montmorillonite. Montmorillonite can take on various colors such as yellow green, yellow white, gray, white, and so on. It can form dense lumps or loose soil, with a slippery sensation when rubbed with your fingers. After adding water, the small body expands several times to 20-30 times in volume, and appears suspended in water. When there is little water, it appears mushy. The properties of montmorillonite are related to its chemical composition and internal structure.

Natural bleached soil

Namely, naturally occurring white clay with inherent bleaching properties is a white, white gray clay mainly composed of montmorillonite, albite, and quartz, and is a type of bentonite.

It is mainly the product of decomposition of vitreous volcanic rock, which does not expand after absorbing water, and the pH value of the suspension is weak acid, which is different from alkaline bentonite; Its bleaching performance is worse than that of activated clay. The colors generally include light yellow, green white, gray, olive color, brown, milk white, peach red, blue, and so on. Very few are pure white. Density: 2.7-2.9g/cm. The apparent density is often low due to porosity. The chemical composition is similar to that of ordinary clay, with the main chemical components being aluminum oxide, silicon dioxide, water, and a small amount of iron, magnesium, calcium, etc. No plasticity, high adsorption. Due to its high content of hydrous silicic acid, it is acidic to litmus. Water is prone to cracking and has a high water content. Generally, the finer the fineness, the higher the decolorization power.

During the exploration phase, when conducting quality evaluation, it is necessary to measure its bleaching performance, acidity, filtration performance, oil absorption, and other items.

Bentonite ore
Bentonite ore is a mineral with multiple uses, and its quality and application fields mainly depend on the content and attribute type of montmorillonite and its crystal chemical properties. Therefore, its development and utilization must vary from mine to mine and from function to function. For example, the production of activated clay, calcium based to sodium based, drilling grouting for petroleum drilling, replacing starch as a slurry for spinning, printing and dyeing, using interior and exterior wall coatings on building materials, preparing organic bentonite, synthesizing 4A zeolite from bentonite, producing white carbon black, and so on.

Difference between calcium based and sodium based

The type of bentonite is determined by the type of interlayer cation in the bentonite. When the interlayer cation is Na+, it is called sodium based bentonite; Calcium based bentonite is called when the interlayer cation is Ca+. Sodium montmorillonite (or sodium bentonite) has better properties than calcium based bentonite. However, the distribution of calcareous soil in the world is far wider than that of sodium soil. Therefore, in addition to strengthening the search for sodium soil, it is necessary to modify the calcareous soil to make it become sodium soil.