Application of diatomite
Diatomaceous earth is a kind of biochemical sediment, mainly formed by the accumulation of fossil bone remains of single-celled plant algae in ancient geological period, and is a non-renewable natural resource. Its main mineral composition is opal and its variants, and its chemical composition is mainly SiO2, and contains a small amount of Al2O3, Fe2O3, CaO, Na2O, MgO, etc.
Diatomaceous earth is commonly known as mountain powder, fossil powder or radiolarian powder. It is an important high-efficiency non-metallic mineral. It has many advantages such as large porosity and strong adsorption. It can be used in building materials, light industry, chemical industry, petroleum, food grade and environmental protection field.
Pure diatomaceous earth is generally in the form of white soil. When it contains impurities, it is often polluted by iron oxides or organic matter and becomes gray, yellow, green, and black. Most diatomaceous earth is light, porous and easily broken, but the hardness of the diatomaceous earth bone particles is relatively large. The density of diatomaceous earth is very small, the average bulk density: 0.66g/cm3, thermal stability: After the original soil is calcined at 900℃ for 2h, the regularly arranged pore structure of the diatom shell wall remains intact. When it is calcined at 1200℃ for 2h, then The arrangement of diatom pores will be destroyed.
The particle structure of diatomaceous earth is closely related to diatoms. The individual diatoms are small, generally 1~100μm. The mineral composition of diatom remains is amorphous SiO2, which has good chemical stability and is thermal, acoustic and electrical of poor conductors.
The chemical composition of diatomaceous earth is mainly silicate, and the level of silica content is an important indicator to measure the quality of diatomaceous earth. It can be divided into high-grade diatomaceous earth and inferior diatomaceous earth.
Diatomaceous earth is a solid acid, which is weakly acidic. In addition to being soluble in hydrofluoric acid, it is insoluble in other acids and can react with weak bases. Its surface adsorption properties are related to its surface structure. The surface of diatomaceous earth is covered by a large number of silyl hydroxyl groups, and there are hydrogen bonds. OH groups are also distributed on the inner surface of the pores of the diatomaceous earth.
Diatomite is rich in resources and widely distributed around the world, mainly distributed in 122 countries and regions such as the United States, China, Argentina, Peru, Denmark, and Japan. However, the resource grade and economic value are high, and the mineral deposits that can be directly developed and utilized are not many. At present, dozens of countries and regions produce diatomite products with an annual output of hundreds of tons. The largest output is the United States, followed by Russia, France and Germany.
Application of diatomite
- Filter aid
Filter aid is a granular material with uniform particles, hard properties and small compressibility. Its function is to filter and separate small particles and prevent colloidal particles from clogging the medium. The most widespread use of diatomaceous earth is as a filter aid for separating suspended solids in liquids. The reason why diatomaceous earth is suitable as a filter aid is that it has poor solubility, suitable particle size distribution and porous structure.
- Application in building materials industry
(1) Application of diatomite in interior wall coatings
The diatom mud made of diatomite as a raw material is used in interior decoration coatings, especially interior wall coatings, and has very good effects on the purification of indoor air and the adjustment of temperature and humidity.
(2) Application of diatomite in environmental protection wall materials
Due to the unique physical structure of diatomite, the diatom mud can fully absorb the formaldehyde and benzene present in the air, and it also has a great promotion effect on indoor air purification, which is very helpful to keep the indoor air fresh.
(3) Application of diatomite in concrete
An obvious application of diatomite in the building materials industry is concrete. Determined by the nature of diatomaceous earth, the surface of diatomaceous earth is rough, and it has strong advantages in high temperature resistance and corrosion resistance. When used with asphalt materials, it can effectively improve the quality of concrete.
(4) Application of diatomite in lightweight wall materials
Diatomite is used in lightweight wall materials and has great advantages in plasticity and sintering molding. After processing, the hardness is also greatly improved. This is due to the fact that there are many pores on the surface of diatomaceous earth, which can allow other materials to merge into the pores. After processing, the wall can be insulated and the weight is greatly reduced.
- Catalyst carrier
Diatomaceous earth is inert to most chemical reactions and resistant to high temperatures, so it can be used as an ideal catalyst carrier. Generally used as a catalyst for chemical reactions such as oxidation, hydrogenation, dehydrogenation, hydration, and reduction. For example, the nickel catalyst in the hydrogenation process, the vanadium catalyst in the preparation of sulfuric acid, the phosphorus catalyst used in petroleum refining, and the catalyst for automobile exhaust gas treatment can all be supported by diatomaceous earth.
- Adsorbent
Diatomaceous earth adsorbent is mainly used for the decolorization and refining of mineral oil, animal and vegetable oils, adsorbing and removing asphaltenes, neutral collagen, sulfide olefins, naphthenic acid, minerals, carotene, lutein, chlorophyll, etc.
Article source: China Powder Network