Stone vermiculite

Stone vermiculite

Vermiculite is a natural, inorganic, non-toxic mineral, which will expand under the action of high temperature. It is a relatively rare mineral and belongs to silicate. Its crystal structure is monoclinic, which looks like mica from its shape. Vermiculite is produced by hydration of certain granite. It is generally produced simultaneously with asbestos. Because vermiculite has the ability of ion exchange, it plays a great role in soil nutrition. In 2000, the total output of vermiculite in the world exceeded 500000 tons. The main producing countries are China, South Africa, Australia, Zimbabwe and the United States.
essential information
Chinese name
Vermiculite
Foreign name
Vermiculite
brief introduction
Layered silicate mineral rich in magnesium and iron
characteristic
It will expand under the action of high temperature
belong to
silicate
Place of Origin
Xinjiang, Lingshou, Shanxi, Inner Mongolia
Fire resistance
1300-1350
Thermal conductivity
0.047-0.081W/(m·K)
Crystalline system
Monoclinic system
catalogue
1 basic information
2 nature and structure
3 structure and form
4 occurrence and combination
5 main uses
6 chemical composition
7 formation and distribution
8 quality grade division
9 expanded vermiculite
10 product specifications
11 vermiculite slab
12 production, storage and transportation
essential information
Vermiculite, also known as vermiculite powder, is called vermiculite in English, with a density of 2.4 ~ 2.7g/cm3;
CAS No.: 1318-00-9;
Molecular formula: (Mg, Fe, Al) 3 [(Si, Al) 4 o 10 (OH) 2]. 4H 2O
[1]
Nature and structure
Vermiculite (Mg, CA) 0.3-0.45 (H2O) n{(Mg, Fe3, Al) 3 [(Si, Al) 4o12] (OH) 2}
The name of vermiculite mineral comes from Latin, with the meaning of "wormlike" and "wormhole". [2] Vermiculite is suddenly heated to 200 to 300 ℃, which will produce worm like peeling along the c-axis of its crystal, so it also gets its name. Vermiculite is a kind of magnesium bearing hydroaluminosilicate secondary metamorphic mineral with layered structure. The shape of the raw ore is like mica. It is usually formed by hydrothermal alteration or weathering of biotite (phlogopite). It is called vermiculite because it is flexible when it is heated, dehydrated and expanded, and its shape is similar to leech.
Vermiculite is a kind of clay mineral similar to montmorillonite, which is silicate with layered structure. It is generally formed from biotite by hydrothermal alteration or weathering. It sometimes appears as thick biotite (this is the illusion of vermiculite biotite), and sometimes it is as fine as soil. When vermiculite is heated to 300 ℃, it can expand 20 times and bend. At this time, vermiculite is a bit like leech (commonly known as leech), so it has such a name. Vermiculite is generally brown, yellow and dark green, with oil like luster, and turns gray after heating. Vermiculite can be used as building materials, adsorbents, fire insulation materials, mechanical lubricants, soil improvers and so on.
The main chemical formula of vermiculite is (Mg, CA) 0.7 (Mg, Fe, Al) 6.0 [(al, SI) 8.0] (oh4.8h2o). The common chemical formula is (mg2.36fe0.48al0.16) (si2.72al1.28o10 (OH) 2) (mg0.32 (H2O) 4.32)
Vermiculite can be divided into vermiculite flakes and expanded vermiculite according to stages, and can be divided into golden vermiculite, silver vermiculite and milky vermiculite according to color.
Vermiculite flakes can expand 6-20 times in volume after high temperature roasting, and the specific gravity after expansion is 60-180kg / m3, which has strong thermal insulation performance.
Structure and form
Monoclinic system; a0=0.535nm，b0=0.925nm，c0=n*1.45 nm， β= 97。 07'; Z=2。 This is the common lattice constant of trioctahedral vermiculite with Mg as the main interlayer cation. The lattice constants of dioctahedral vermiculite are slightly different. The crystal structure is 2:1 (TOT) type. The layer charge is generated by replacing Si with Al in the tetrahedral sheet, resulting in the filling of exchangeable cations and water molecules between the layers. Water molecules are connected with the bridge oxygen on the surface of the structural layer by hydrogen bond, and they are connected with each other by weak hydrogen bond in the water molecular layer. Some water molecules form coordination octahedron around interlayer cations to form hydrated complex ion [Mg (H2O) 6] 2, which occupies a fixed position in the structure; Some water molecules are free. This structural feature makes vermiculite have strong cation exchange capacity. Under normal temperature and humidity, the C0 of Mg saturated vermiculite is 1.436 nm. There is a double water molecular layer between the layers, but the water molecular layer is incomplete. After water saturation, C0 increases to 1.481 nm, and the interlayer is filled with a complete water molecular layer. After partial dehydration of vermiculite by slow heating, its C0 changes from 1.436 to 1.382 nm. If the dehydration is continued, the double-layer water molecules will be reduced to single-layer water molecules, and C0 will become 1.159nm. If the dehydration is continued, it will become a structure with complete dehydration structure (C0 = 0.902nm) and single-layer water molecular structure (C0 = 1.159nm), and its C0 is 2.06nm. After complete dehydration, it becomes a structure similar to talc, with C0 of 0.902nm.
Vermiculite can absorb water again after being heated to 500 ℃ for dehydration and placed at room temperature; However, it will not absorb water after heating to 700 ℃.
It often appears as biotite or phlogopite. Most of them are brown, yellowish brown, golden yellow, bronze and sometimes green. The luster is weaker than mica, with grease luster or pearl luster. Cleavage is complete and the sheet is flexible. Hardness 1 ~ 1.5. The relative density is 2.4 ~ 2.7.
Under polarizer: polychromatic, 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。
Expansibility; Cation exchange and adsorption; Expanded vermiculite also has good water absorption; Sound insulation; Thermal insulation and fire resistance; Frost resistance; The chemical properties of expanded vermiculite are stable. Insoluble in water. PH value 7 ~ 8. Non toxic, tasteless, no side effects.
Occurrence and combination
It is mainly the product of low-temperature hydrothermal alteration of biotite and phlogopite. Part of vermiculite is formed slowly by weathering of biotite.
[identification characteristics] the appearance is similar to biotite, but the luster, cleavage degree, hardness and sheet elasticity are weaker than biotite. The main feature of burning is the strong expansion of volume.
Main purpose
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.
After high-temperature roasting, the volume of raw vermiculite flakes can expand rapidly several times to dozens of times. The vermiculite after volume expansion is called expanded vermiculite. It is a layered structure with crystalline water between layers, with a unit weight of 50-200kg / m3 and small thermal conductivity. It is a good thermal insulation material. Expanded vermiculite with good quality can be used at a maximum temperature of 1100 ℃. In addition, expanded vermiculite has good electrical insulation. Expanded vermiculite is widely used in industries such as thermal insulation materials, fireproof materials, seedling raising, flower planting, tree planting, friction materials, sealing materials, electrical insulation materials, coatings, plates, paints, rubber, refractory materials, hard water softener, smelting, construction, shipbuilding, chemistry and so on.
Expanded vermiculite is widely used, but its main use is still as building materials. In the consumption structure of the United States in 1986, expanded vermiculite used as mortar and cement premix and lightweight concrete aggregate accounted for 52%; In the UK, 40% of them are used as coagulants for concrete, wall plastering and cement.
Main uses of vermiculite:
Building: light material, light concrete aggregate (light wall powder, light mortar), expanded vermiculite, expanded vermiculite heat-resistant material, wall material, fireproof board, fireproof mortar and refractory brick.
Thermal insulation: sound absorbing materials, underground pipes, greenhouse pipes, thermal insulation materials, indoor and tunnel interior decoration, walls and ceilings in public places.
Metallurgy: steel frame cladding material, iron making, casting slag removal, cladding material of high-rise building steel frame, vermiculite bulk material.
Agriculture and Forestry: Horticulture, golf course lawn, seed preservation agent, soil conditioner, wetting agent, plant growth agent and feed additive.
Marine fishing industry: erbium fishing.
Other aspects: adsorbent, filter aid, active carrier of chemical products and chemical fertilizer, sewage treatment, seawater oil adsorption, cigarette filter, explosive density regulator.
Vermiculite with different diameter has different uses
+20 items: house insulation equipment, household refrigerator, automobile sound attenuator, sound insulation plaster, safe and cellar lining pipes, boiler heat protective clothing, long handle spoon of ironmaking plant, refractory brick insulation cement.
20 ~ 40 items: Automobile insulation equipment, aircraft insulation equipment, cold storage insulation equipment, bus insulation equipment, wallboard water cooling tower, steel annealing, fire extinguisher, filter and cold storage.
40 ~ 120 mesh: linoleum, roof slab, cornice board and dielectric gate board.
120 ~ 270 mesh: paste wallpaper printing, outdoor advertising, paint, increase the viscosity of paint, and fireproof card paper for photographic softwood.
-270 mesh: external supplement for golden yellow and bronze ink and paint.
application area
Main purpose
Architecture
Light material
Lightweight concrete aggregate, lightweight wall powder, lightweight mortar
Fireproof and heat-resistant materials
Wall material, fireproof board, fireproof mortar and refractory brick
Thermal insulation, heat insulation and sound absorption materials
Thermal insulation materials for pipes and greenhouse pipes, interior decoration of indoor and tunnel, walls and ceilings in public places
metallurgy
Steel frame cladding material, iron making, casting and impurity removal
Coating materials and vermiculite bulk materials for steel frames of high-rise buildings
Agriculture, forestry, fisheries and Gardens
gardens
Soil conditioner, plant production agent, feed additive, etc
Marine fishing
Bait
other aspects
Adsorbent, filter aid, active carrier of chemical fertilizer, sewage treatment, seawater oil adsorption
It is useful to see some warm paste products on the market
Fold and edit the chemical composition of this paragraph
Chemical composition of vermiculite (%)
SiO2
Al2 O3
Fe2O3
MgO
H2O
37-43
9-17
5-24
11-23
0.5-9
1: Spreading expanded vermiculite on the roof can have a good heat insulation effect and make the building warm in winter and cool in summer. The partition board of high-rise building made of vermiculite brick can not only play the role of sound insulation, fire prevention and moisture-proof, but also reduce the load of the building.
2: Vermiculite is used in greenhouse. It has the characteristics of loose soil, good air permeability, strong water absorption and small temperature change. It is conducive to the growth of crops and reduce the input of fertilizer. In the emerging soilless cultivation technology, it is an essential raw material.
3: Vermiculite can be mixed with an appropriate amount of insulating glue to make insulating board.
4: Vermiculite can be used as hatching material for artificial reproduction of reptiles.
5: Vermiculite is also used in medicine and health, animal feed and other industries.
In tetrahedral sheet, the substitution of Al for Si is generally 1 / 3 ~ 1 / 2, and Fe3 can also replace Si. The substitution of Al and Fe3 for Si is the main reason for the generation of layer charge. The number of charges per unit chemical formula is between 0.6 and 0.9. On the one hand, the layer charge compensation is caused by Al replacing mg in octahedron, on the other hand, it comes from interlayer cations. Interlayer cations are mainly mg, CA, Na, K, (H3O), Rb, CS, Li, Ba, etc. The cations in the octahedral sheet are mainly mg, but also Fe3, Al, Cr, Fe2, Ni, Li, etc. The content of interlayer water depends on the hydration capacity of interlayer cations and ambient temperature and humidity. When containing Mg with high hydration capacity, the unit chemical formula can contain 4 ~ 5 water molecules at high temperature and humidity; When the cation is CS with weak hydration capacity, it can hardly contain water molecules.
Formation distribution
Formation and origin
In nature, it is produced by biotite and other minerals in the solution of hot springs. In nature, they are mixed with the clay in the soil and cannot be separated from the clay. Vermiculite is produced in China's Xinjiang, Russia's Kola Peninsula, Zimbabwe, 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 others are mainly distributed in the United States and South Africa. American vermiculite is mainly distributed in Libby, Montana, with reserves of about 80 million tons, accounting for two-thirds of the total reserves of American vermiculite; The total reserves of South Africa are about 73 million tons, and the main origin is palabora region, 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, of which the super large ones are kordov and bodanin deposits, with a total estimated 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 is the Chagan Bulak vermiculite mine in Yuli County, Xinjiang, whose reserves account for more than 90% of the country's total reserves, ranking second in the world (second only to South Africa). The prospective reserves are 100 million tons, of which the proved reserves of No. 2 ore body are 14 million tons. It is a rare super large ore deposit in the world. The burning test results show that Xinjiang Vermiculite has the advantages of high expansion multiple and less impurities. There are abundant vermiculite mines in Lingshou County, Xinjiang. Besides, there are vermiculite mines in Lingshi County, where the quality of vermiculite is very good. Golden vermiculite
Vermiculite mineral characteristics
The chemical formula of vermiculite is (Mg, CA) 0.7 (Mg, Fe, Al) 6.0 [(al, SI) 8.0] (oh4.8h2o). Monoclinic system, usually flaky. Brown, tawny or bronze. Greasy luster. Hardness 1 ~ 1.5. The density is 2.4 ~ 2.7g/cm3. When vermiculite is roasted at 800 ~ 1000 ℃, the volume expands rapidly, increasing by 6 ~ 15 times, and the higher one can reach 30 times. The average bulk density of expanded vermiculite is 100 ~ 200kg / m3. Because the vermiculite expanded by roasting has a small air barrier, it has excellent thermal insulation performance.
Quality grade division
The quality grade of vermiculite is divided according to the expansion multiple of vermiculite, the plane size of flake and the content of impurities. However, due to the great changes in the appearance and composition of vermiculite, it is difficult to classify it accurately. Therefore, the classification is mainly based on its volume expansion multiple. Several classification standards are described below:
1. Grading according to volume expansion multiple.
Grade I product: vermiculite has large leaves and cannot be split into complete flakes. The color is brass, bronze or light green, with pearl or fat luster. After calcination, it turns golden yellow, and the volume of vermiculite expands more than 8 times.
Grade II product: vermiculite has large leaves and is not easy to split and peel into complete flakes. The colors are brown, dark brass and green, with pearl or glass luster. The volume of vermiculite expands 6-8 times after calcination.
Grade III product: vermiculite has small leaves, some elastic flakes and uneven surfaces. The color is dark brown and dark green, with some glass luster. After calcination, the volume of vermiculite expands 3 ~ 5 times.
Grade IV product: vermiculite slightly hydrated, which has similar appearance to mica and is sandwiched with mica without hydration. It is easy to split and peel into thin sheets. The color is dark green or similar to black and is glassy
2. Grade according to the plane size of vermiculite blade.
Grade I product: above 15mm.
Grade II product: 4 ~ 15mm.
Grade III product: 2 ~ 4mm.
Grade IV product: below 2mm.
3. Grade according to the content of other mineral impurities in vermiculite raw ore.
Grade I product: the impurity content accounts for less than 3% (by weight).
Grade II product: the impurity content accounts for 4 ~ 9% (by weight).
Grade III product: the impurity content accounts for 10 -, -, 15% (by weight).
Grade IV product: the impurity content is more than 15% (by weight). [3]
Fold and edit this section of expanded vermiculite
Vermiculite is a kind of hydrate, which is massive and flaky. The interlayer water molecules are burned at high temperature and the volume increases by 6-15 times. It is rich in nitrogen, phosphorus, potassium, aluminum, iron, magnesium, silicate and other components. Vermiculite has high layer charge number, so it has high cation exchange capacity and strong cation exchange adsorption capacity. It is characterized by light weight, good water and fertilizer adsorption performance, no rot, and can be used for 3-5 years (unlike humic soil, coconut shell, etc., which are easy to rot).
Raw vermiculite ore becomes expanded vermiculite after high temperature roasting. The conventional particle size specifications of expanded vermiculite include 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 the production needs of customers. Vermiculite powder is made from raw vermiculite ore by roasting at high temperature, screening, grinding and processing into powder. The main models are 40 mesh, 60 mesh, 100 mesh, 200 mesh and 325 mesh. Application: house insulation equipment, household refrigerator, automobile sound attenuator, sound insulation plaster, safe and cellar lining pipeline, boiler heat protection clothing, long handle spoon of ironmaking plant, refractory brick, insulating cement, automobile insulation equipment, aircraft insulation equipment, cold storage insulation equipment, passenger car insulation equipment, wallboard water cooling tower, steel annealing, fire extinguisher, filter, cold storage, linoleum, roof board, cornice board, dielectric shutter Paste wallpaper printing, outdoor advertising, paint, increase the viscosity of paint, fireproof card paper for photographic softwood, golden and bronze ink, external supplement of paint, etc.
Folding agriculture
In agriculture, vermiculite can be used as soil conditioner. Because of its good cation exchange and adsorption, it can improve the structure of soil, store water and preserve moisture, improve the permeability and moisture content of soil, and turn acidic soil into neutral soil; Vermiculite can also act as a buffer, hinder the rapid change of pH value, make the fertilizer release slowly in the crop growth medium, and allow a little 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 and Zn. Vermiculite has the characteristics of water absorption, cation exchange and chemical composition, which makes it play multiple roles such as fertilizer retention, water retention, water storage, air permeability and mineral fertilizer. The results show that the crop yield can be increased by 15-20% by adding 0.5-1% expanded vermiculite into compound fertilizer.
Folding gardening
In horticulture, vermiculite can be used in the cultivation of flowers, vegetables and fruits, seedling raising and so on. In addition to being used as potted soil and regulator, it is also used for soilless cultivation. As a nutrient base for planting potted trees and commercial seedbeds, it is particularly beneficial for plant transplanting and transportation. Vermiculite can effectively promote the growth of plant roots and the stable development of seedlings. Provide water and nutrition necessary for plant growth for a long time, and maintain the stability of root sunshine temperature. Vermiculite can enable crops to obtain sufficient water and minerals from the early stage of growth, promote rapid plant growth and increase yield.
Fold and edit the product specifications in this section
Vermiculite product specifications: 0.5-1mm, 1-3mm, 2-4mm, 3-6mm, 4-8mm.
The main types of vermiculite are: 20-40 mesh, 40-60 mesh, 60-80 mesh, 200 mesh and 325 mesh.
Fold and edit the vermiculite slab in this section
Vermiculite board is made of expanded vermiculite and a certain amount of adhesive through hot pressing or cold pressing. 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 materials.
Vermiculite board is a new type of inorganic material. It is made of expanded vermiculite as the main raw material, mixed with a certain proportion of inorganic adhesive and processed through a series of processes. It has the characteristics of high temperature resistance, fire prevention, green environmental protection, heat insulation, sound insulation and no harmful substances. After high temperature heating to 1200 ℃, there is no gas harmful to human health, and the combustion performance reaches class A.
Vermiculite slab is widely used in construction, shipbuilding, metallurgy, electric power, aerospace and other fields abroad; Vermiculite slab can be used for furniture, firewall, ceiling, fire passage, steel beam coating, pipeline coating, lining plate in real fire fireplace, wall partition, etc. 1. Fire door core; 2. Senior Kitchenware and furniture; 3. Hull plate; 4. Fire fighting access and ventilation system; 5. Commercial buildings, banks, libraries, hotels, restaurants, entertainment places, high-grade houses, ordinary houses, etc; 6. Kiln insulation; 7. Fireplace insulation; 8. Industrial thermal insulation materials.
Fold and edit the production, storage and transportation of this section
Vermiculite is generally mined in open-pit, mostly manual drilling, explosive blasting, etc. it needs to be sealed and stored at room temperature, away from light, ventilated and dry place.