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1. What is Bentonite? |
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Bentonite is a type of clay mineral formed by the earth from volcanic ash and lava deposited on the bottoms of seas and lakes.
Bentonite is a rock, which is a generic name for a mineral aggregate. Its components depend on the mining location.
The main component of bentonite is a mineral called montmorillonite. Other components are minerals such as, quartz, mica, feldspar, and zeolite.
Bentonite consists of many minerals, but currently, it is the special properties of the montmorillonite contained in bentonite that are exploited.
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2. Properties of Bentonite |
The montmorillonite crystals of bentonite have a specific structure that provides various useful characteristics. Bentonite is classified as either the Na type or Ca type, and these two types have different characteristics and are therefore used for different purposes. |
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Properties of bentonite
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Swelling |
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Thickening and caking property |
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Water absorption and adsorption |
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Suspension stability |
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Cation exchange |
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Thixotropy |
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Differences between Na type and Ca type
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Na type: |
Especially superior swelling, thickening , |
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and suspension stability |
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Ca type: |
Especially superior caking property |
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Bentonite has superior thermal stability and is not deteriorated at room temperature.
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(The molecular structure of bentonite is stable up to
400
.)
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| 3. Purposes of Bentonite |
| You may not use bentonite consciously in your everyday life, but it is already used in various areas. |
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Areas of use and purposes of bentonite
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Casting: Bond for greensand molds |
Civil engineering: Drilling mud
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| Building construction: Sealing materials to keep out water |
Cosmetics: Thickener and dispersant
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Pets: Toilet sand for pets |
Agriculture: Bond and dispersant
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| 4. Safety of Bentonite |
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Bentonite does not rot because it is completely inorganic.
It conforms to the environmental quality standards for soil and the standards of the Japanese Pharmacopoeia. It is assured that bentonite is harmless to humans and the environment. |
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5. Improvements of Bentonite
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Montmorillonite, the main component of bentonite, has the above characteristics in water systems, but does not have the expected characteristics in organic oil systems. To solve this problem, we developed pro-oil (pro-organic) bentonite. This type of bentonite disperses in organic solvents and resins and therefore opens up new application areas. Bentonite is also expected to become a key material for improving the properties nanocomposite resins. |
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Comparison of dispersion in toluen
Left: Ordinary product, Right: Pro-organic product
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How was bentonite created? |
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For a very long period (several tens of million of years), temperature and pressure were applied to the volcanic ash and lava deposited on the bottoms of seas and lakes.
This changed the molecular-level structure of the minerals, and bentonite as a mineral aggregate was created. Bentonite is a material that was created under very rare conditions, and it can be regarded as a gift from the earth.
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How is bentonite mined? |
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Minerals, including bentonite, are usually extracted from the earth using underground mining or open-pit mining. Kunimine Industries conducts underground mining in the Tsukinuno mine and open-pit mining in the Kawasaki and Dobuyama mines. We select the most suitable mining method according to the mineral deposit conditions. |
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Underground mining
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| If the layer to be mined is deep under the ground, extraction is done by building an underground road. |
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Open-pit mining
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| If the layer is near the surface, extraction is done by excavating from the surface. |
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