Vermiculite is a natural, inorganic, non-toxic mineral that will expand under high temperature.It is a relatively rare mineral, belonging tosilicate。Its crystal structure is monoclinic system, which looks like mica from its appearance.Vermiculite is composed ofGraniteIt is generated during hydration.It is generally produced at the same time as asbestos.Because vermiculite hasIon exchangeIt has a great effect on soil nutrition.In 2000, the total output of vermiculite in the world exceeded 500000 tons.The main producing countries are ChinaSouth Africa, AustraliazimbabweAnd the United States.
Chinese name
Vermiculite
Foreign name
Vermiculite
Introduction
Layered silicate mineral rich in magnesium and iron
The name of vermiculite mineral comes from Latin, which means "worm like" and "worm trace like".[2]Vermiculite is suddenly heated to 200 to 300 ℃, and will produce worm like peeling along the c-axis of its crystal, so it also gets its name.Vermiculite is a kind ofLayered structureOf magnesium containing waterAluminosilicateSecondary metamorphic mineral, the original ore looks like mica, and is usually formed by hydrothermal alteration or weathering of biotite (phlogopite), which is in flexure shape when it is heated, dehydrated and expanded, similar in shapeLeech, so it is called vermiculite.
Vermiculite is a kind ofmontmorillonitealikeclay mineral, silicate with layered structure.GenerallyBiotitethroughHydrothermal alterationOr weathering.Sometimes it appears in the form of coarse biotite (this is the biotite illusion of vermiculite), and sometimes it is so fine that it becomes soil like.When the vermiculite is heated to 300 ℃, it can expand 20 times and bend.At this time, vermiculite is a little like leech (commonly known as leechLeech）, so it has such a name.Vermiculite is generally brown, yellow, dark green, with oil like luster, and turns gray after heating.Vermiculite can be used as building materialsAdsorbentFire insulation materials, machinerylubricant、Soil conditionerAnd so on.
Vermiculite flakes can be quickly calcined at high temperatureexpand6-20 times, the specific gravity after expansion is 60-180kg/mthreeIt has strong thermal insulation performance.
Structure and form
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Vermiculite can absorb water again at room temperature after being heated to 500 ℃ for dehydration;However, when heated to 700 ℃, it will no longer absorb water.
Constant dependenceBiotiteorPhlogopiteFalse appearance.It is mostly brown, yellowish brown, golden yellow, bronze, and sometimes green.The luster is weaker than mica,Grease sheenorPearly luster。cleavage Complete, flexible sheet.The hardness is 1~1.5.relative density2.4~2.7。
PolarizerBottom: Multicolor colorless to light brown.Biaxial crystal(-), the optical axis angle is very small.Ng=1.545~1.585，Nm =1.540~1.580，Np=1.525~1.560。
MainlyBiotiteandPhlogopiteThe product of low-temperature hydrothermal alteration.Part of vermiculite is slowly formed from biotite through weathering.
[Identification characteristics] The appearance is similar to biotite, but the gloss, cleavage degree, hardness and sheet elasticity are weaker than biotite.It is characterized by strong volume expansion during burning.[2]
Main purpose
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Product specifications: 8-12mm, 4-8mm, 2-4mm, 1-2mm, 0.3-1mm, 40-60 mesh, 60-80 mesh, 80-100 mesh, 100 mesh, 150 mesh, 200 mesh, 325 mesh, etc. The specifications can be produced according to requirements.
Vermiculite
After roasting at high temperature, the volume of raw vermiculite flakes can rapidly expand several times to dozens of times. The expanded vermiculite is calledExpanded vermiculite, which isLayered structureThere is crystal water between layers, and the unit weight is 50-200kg/mthree, low thermal conductivity, goodThermal insulation material。The expanded vermiculite with good quality can be used up to 1100 ℃.In addition, expanded vermiculite has good electrical insulation.Expanded vermiculite is widely usedThermal insulation material、Fireproof material, seedling raising, flower planting, tree plantingfriction material, sealing materials, electrical insulation materials, coatings, plates, paints, rubber, refractory materialsHard waterSoftener, smelting, construction, shipbuilding, chemical and other industries.[4]
The expanded vermiculite is widely used, but its main use is still as building materials.In the consumption structure of the United States in 1986, it was used as mortar and cement premix andLightweight concreteAggregateExpanded vermiculite52%;40% of them are used as concrete, wall mud and cement coagulant in Britain.
Other aspects: adsorbent, filter aid, active carrier of chemical products and fertilizers, sewage treatment, seawater oil adsorption, cigarette filter tip, explosive density regulator.
Vermiculites with different diameters have different uses
+20 mesh: house insulation equipment, household refrigerator, automobile sound attenuator, sound insulation plaster, safe and cellar lining pipes, heat protective clothing for boilers, ladle for ironworks, refractory brick insulation cement.
120~270 mesh: wallpaper printing, outdoor advertising, paint, increase the viscosity of paint, fireproof card paper for photographic cork.
-270 mesh: external supplement for gold and bronze ink and paint.
chemical composition
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Chemical composition of vermiculite (%)
SiOtwo
AltwoOthree
FetwoOthree
MgO
HtwoO
37-43
9-17
5-24
11-23
0.5-9
1: PutExpanded vermiculitePaved on the roof, it can play a good thermal insulation effect, making the building warm in winter and cool in summer.useVermiculite brickThe partition board built into a high-rise building can play the role of sound insulation, fire prevention, moisture-proof, and can also reduce the load of the building.
2: Vermiculite is used in greenhouse and has loose soil,Air permeabilityGood, strong water absorption, small temperature change and other characteristics, which are conducive to crop growth and can also reduce the input of fertilizer.In the newly emergingSoilless culture technologyIt is an indispensable raw material.
3: Vermiculite mixed with proper amount of insulating glue can be made intoInsulating board。
4: Vermiculite can be used as hatching mat for artificial reproduction of reptiles.
5: Vermiculite is also used in medicine, health, animal feed, etc.[2]
Formation distribution
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Formation and origin
Golden vermiculite
In nature, minerals such as biotite are produced in the solution of hot springs.In nature, they are similar toclayThey are mixed together and cannot be separated from clay.Vermiculite in Xinjiang of China, Kola Peninsula of Russiazimbabwe, Australia, South Africa and the United States.The world has about 600 million tons of vermiculite reserves, of which China and Russia account for about two-thirds, and the rest are mainly distributed in the United States and South Africa.Vermiculite in the United States is mainly distributed in LIBBY, Montana, with a reserve of about 80 million tons, accounting for two-thirds of the total vermiculite reserves in the United States;The total reserves of South Africa are about 73 million tons, mainly produced in Parabola, which accounts for more than 90% of the total reserves of vermiculite in South Africa;There are more than 20 vermiculite deposits in the former Soviet Union, among which the super large ones are the Kordof and Bodanin deposits, with an estimated total reserves of about 200 million tons.Vermiculite is widely distributed in China, but mostly in northern China, mainly in Xinjiang, Hebei, Inner Mongolia, Liaoning, Shanxi, Shaanxi and other provinces and regions;It is also distributed in Sichuan, Henan, Hubei, Gansu and other provinces, mainly in metamorphic rock areas.The largest and most representative vermiculite deposit in Yuli County, Xinjiang is the Qiaganbarak vermiculite deposit. Its reserves account for more than 90% of the total reserves of the country, ranking second in the world (only second to South Africa), with a prospective reserves of 100 million tons. Among them, the proven reserves of ore body 2 are 14 million tons, which is a rare super large ore deposit in the world. The burning experiment results show that Xinjiang vermiculite has the advantages of high expansion ratio and less impurities.Lingshou CountyGolden vermiculiteThe main producing area is Shikai, Donghai County, which is rich in vermiculite minerals, especially in the 33rd Regiment of the Second Agricultural Division of Xinjiang Production and Construction Corps. The vermiculite here is not only rich in reserves, but also of good quality.
Vermiculite mineral characteristics
The chemical formula of vermiculite is (Mg, Ca)zero point seven（Mg，Fe，Al）six[（Al，Si）eight]（OHfour point eightHtwoO） 。Monocline system, usually in sheet shape.Brown, yellowish brown or bronze.Grease gloss.The hardness is 1~1.5.The density is 2.4~2.7g/cm3, vermiculite is roasted at 800~1000 ℃, and its volume expands rapidly, increasing by 6~15 times, and the higher one can reach 30 times.The average unit weight of expanded vermiculite is 100~200Kg/m3, because the vermiculite after roasting expansion has a small air barrier, it has excellent thermal insulation performance.
Quality grade division
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The quality grade of vermiculite is divided according to the expansion ratio of vermiculite, the plane size of thin slice and the amount of impurities.However, due to the great changes in the appearance and composition of vermiculite, it is difficult to carry out an accurate classification.Therefore, it is mainly based on its volume expansion multiple as the basis for grading.Several grading standards are described as follows:
1. Grading according to volume expansion ratio.
Grade I: Vermiculite has large leaves and cannot be split into complete thin pieces.The color is brass, bronze or light green, with pearl or fat luster. After calcination, it becomes golden yellow, and the volume of vermiculite expands more than 8 times.
Grade II: Vermiculite has large leaves and is not easy to split and peel into complete sheets.The color is brown, dark copper and green, with pearl or glass luster.After calcination, the volume of vermiculite expands 6-8 times.
Grade III: Vermiculite leaves are small, thin and elastic, and the surface is uneven.The color is dark brown, dark green, and some glass luster.After calcination, the volume of vermiculite expands 3-5 times.
Grade IV: Vermiculite slightly hydrated has a similar appearance to mica and is mixed with non hydrated mica. It is easy to split and peel into thin pieces, dark green or nearly black, with glass luster. After calcination, the volume of vermiculite expands by less than 3 times.
2. Grades according to the plane size of vermiculite leaves.
Grade I: above 15mm.
Grade II: 4-15mm.
Grade III product: 2~4mm.
Grade IV: below 2mm.
3. Classification according to the content of other mineral impurities in vermiculite raw ore.
Grade I: impurity content is less than 3% (by weight).
Grade II: impurity content accounts for 4~9% (by weight).
Grade III product: impurity content accounts for 10 -, -, 15% (by weight).
Vermiculite is a kind of hydrate, which is massive and flaky.The volume of interlayer water molecules increases 6-15 times after high-temperature burning.Rich in nitrogen, phosphorus, potassiumaluminum、iron, magnesium, silicate, etc.Vermiculite has higher layer charge number, so it has higher cation exchange capacity and stronger cation exchange adsorption capacity.It is characterized by light weight, good water and fertilizer absorption performance, non rotting, and can be used for 3-5 years (unlike humus soil, coconut shell clothing, etc., which are easily rotted).
Raw vermiculite becomes expanded vermiculite after high temperature roasting.The conventional particle sizes of expanded vermiculite are 0.5-1mm, 1-3mm 2-4mm, 3-6mm, 4-8mm, 1-6mm, etc.In addition, other granularity models can also be produced according to customer production needs.Vermiculite powderRaw vermiculite is roasted at high temperature, screened and ground into powder.The main models are 40 mesh, 60 mesh, 100 mesh, 200 mesh and 325 mesh.Applications: house insulation equipment, household refrigerators, automobile sound attenuators, sound insulation plaster, safe and cellar lining pipes, heat jackets for boilers, ladle for ironworksrefractory bricksInsulating cement, automobile insulation equipment, aircraft insulation equipment, refrigerator insulation equipment, bus insulation equipment, wallboard water cooling tower, steel annealingFire Extinguisher、filter, cold storage, linoleum, roof slabCornice board, dielectric switch board, wallpaper printing, outdoor advertising, paint, increase the viscosity of paint, fireproof card paper, golden yellow and bronze color for photographic corkprinting ink, paint additives, etc.
Agriculture
In agriculture, vermiculite can be used as a soil conditioner. Because of its good cation exchange and adsorption, vermiculite can improve the structure of soil, store water and keep moisture, and improve theAir permeabilityAnd water content, making acidic soil become neutral soil;Vermiculite can also play a buffer role, blocking the rapid change of PH value, making the fertilizer slowly released in the crop growth medium, and allowing slightly excessive use of fertilizer without harm to plants;Vermiculite can also provide crops with K, Mg, Ca, Fe and trace elements such as Mn, Cu, Zn.Vermiculite has the characteristics of water absorption, cation exchange and chemical composition, which makes it play multiple roles in fertilizer, water, water storage, air permeability and mineral fertilizer.The test shows that 0.5-1%Expanded vermiculiteWhen mixed with compound fertilizer, the crop yield can be increased by 15-20%.
Horticulture
In horticulture, vermiculite can be used for flowers, vegetables, fruit cultivation, seedling raising, etc.In addition to being potted soil and regulator, it is also used for soilless cultivation.As a nutritional base for planting potted trees and commercial seedbeds, it is particularly beneficial for transplanting and transporting plants.Vermiculite can effectively promote the growth of plant roots and the stable development of seedlings.It can provide water and nutrition necessary for plant growth for a long time, and can keep the sun temperature of roots stable.Vermiculite can enable crops to obtain sufficient water and minerals from the initial stage of growth, promote rapid growth of plants and increase yield.
The main types of vermiculite include 20-40 mesh, 40-60 mesh, 60-80 mesh, 200 mesh and 325 mesh.
vermiculite
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Vermiculite slab is usedExpanded vermiculiteAnd a certain amount of adhesive, after hot or cold pressing and made of plates.The board has the characteristics of heat preservation, heat insulation and fire prevention.This product can be used in fireproof door core, fireplace lining and wall material.
Vermiculite slab is a new typeInorganic materialsThe expanded vermiculite is used as the main raw material, mixed with a certain proportion of inorganic binder, and processed through a series of processes. It is a board with high temperature resistance, fire resistance, green environmental protection, heat insulation, sound insulation, and no harmful substances.When heated to 1200 ℃ at high temperature, no gas harmful to human health will be generated, and the combustion performance reaches Grade A.
Vermiculite slabs are widely used in construction, shipbuilding, metallurgy, power, aerospace and other fields abroad;Vermiculite slab can be used for furniture, firewall, suspended ceiling, fire passage, steel beam coating, pipeline coating, lining plate in real fire fireplace, wall partition, etc.1. Fire door core;2. High class kitchenware and furniture;3. Hull plating;4. Fire fighting access and ventilation system;5. Commercial bank, library, hotel, hotel, entertainment place, senior residence, ordinary residence, etc;6. Furnace insulation;7. Fireplace insulation;8. IndustrialThermal insulation material。
Production, storage and transportation
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Vermiculite is generally usedopen-pit miningMost of them are manual drilling, explosive blasting, etc. They need to be sealed and stored in a dry, ventilated place at room temperature and away from light.
