Description

Basic Property

Vermiculite (Vermiculite) (Mg, Ca) 0.3 0.45 (H2O) n {(Mg, Fe3, Al) 3/4 o12 (Si, Al) (OH) 2}
Vermiculite mineral name comes from Latin, with the meaning of “wormlike”, “wormlike”. [2] Vermiculite, when suddenly heated to 200 to 300℃, produces wormlike flakings along the C-axis of its crystal, from which it derives its name. Vermiculite is a kind of layered structure of magnesium containing hydroaluminosilicate secondary metamorphic minerals, raw ore appearance like mica, usually mainly by black (gold) mica through hydrothermal alteration or weathering, because of its heat and water loss expansion is curved, the shape resembles leeches, so called vermiculite.
Vermiculite is a clay mineral similar to montmorillonite. It is a layered silicate. It is usually formed by hydrothermal alteration or weathering of biotite. Sometimes it appears as coarse biotite (the biotite illusion of vermiculite), and sometimes as fine as soil. When vermiculite is heated to 300℃, it expands 20 times and bends. The vermiculite is a bit like a leech, hence its name. Vermiculite is generally brown, yellow and dark green, with an oily sheen that turns gray when heated. Vermiculite can be used as building materials, adsorbents, fireproof insulation materials, mechanical lubricants, soil amendments 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 the stage, according to the color classification can be divided into golden vermiculite, silver vermiculite, milky white vermiculite.
Vermiculite flakes after high temperature roasting its volume can rapidly expand 6-20 times, the proportion of expansion is 60-180kg/m3, has a strong thermal insulation performance.

Structure and morphology

Monoclinic system; a0=0.535nm, b0=0.925nm, c0=n*1.45 nm, β=97. 07 ‘; Z is equal to 2. This is the lattice constant of the common 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 substitution of Si by Al in the tetrahedral sheet generates layer charge, resulting in interlayer filling with exchangeable cations and water molecules. The water molecules are connected with the bridging oxygen on the surface of the structural layer by hydrogen bonds, and are connected with each other by weak hydrogen bonds in the water molecular layer. Some water molecules form coordination octahedrons around the interlayer cations to form hydration complex ions [Mg(H2O)6]2, which occupy a fixed position in the structure. Some of the water molecules are free. This structure makes vermiculite have strong cation exchange ability. Under normal temperature and humidity, the c0 of MG-saturated vermiculite is 1.436nm, and there are two water molecular layers between the layers, but the water molecular layer is incomplete. After water saturation, c0 increased to 1.481nm, and the interlayer was filled with a complete layer of water molecules. After the vermiculite was partially dehydrated by slow heating, its c0 changed from 1.436 nm to 1.382nm. With further dehydration, the double layer of water molecules will be reduced to a single layer of water molecules, and c0 will become 1.159nm. After further dehydration, the completely dehydrated structure (c0=0.902nm) and monolayer water substructure (c0=1.159nm) were interphase arranged, and the c0 was 2.06nm. After complete dehydration, the structure is similar to talc, c0 is 0.902nm.

Vermiculite heated to 500℃ after dehydration, placed at room temperature can be absorbent again; But after heating to 700℃, it no longer absorbs water.

Often imitated by biotite or mica. Mostly brown, yellowish brown, golden, bronze, sometimes with green. Luster weaker than mica, grease luster or pearl luster. The cleavage is complete and the lamellar is flexible. Hardness 1~1.5. The relative density is 2.4~2.7.

Polarizoscope: 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; Heat insulation and fire resistance; Frost resistance; The chemical properties of expanded vermiculite are stable. Insoluble in water. pH 7~8. Non-toxic, tasteless, no side effects.

Occurrence and Combination

It is mainly the product of biotite and gold mica by low temperature hydrothermal alteration. Some vermiculite is slowly formed from biotite by weathering.

[Identification characteristics] It is similar to biotite in appearance, but its luster, cleavage degree, hardness and sheet elasticity are weaker than biotite. Its main characteristic is the strong expansion of volume during burning.

Main use

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., specifications can be produced according to requirements.

After roasting at high temperature, the volume of raw vermiculite can rapidly expand several times to dozens of times. The volume of vermiculite after expansion is called expanded vermiculite.

It is a layered structure, containing crystalline water between layers, bulk density of 50-200kg/m3, small thermal conductivity, is a good insulation material. Good quality expanded vermiculite, the highest use temperature can reach 1100℃. In addition, expanded vermiculite has good electrical insulation. Expanded vermiculite is widely used in insulation materials, fireproof materials, seedlings, flowers, trees, friction materials, sealing materials, electrical insulation materials, coatings, boards, paint, rubber, refractory materials, hard water softener, smelting, construction, shipbuilding, chemical and other industries.

Expanded vermiculite has a wide range of uses, but its main use is still as a building material. In 1986, expansive vermiculite used as mortar and cement premix and lightweight concrete aggregate accounted for 52% of the consumption structure in the United States. Britain used for concrete, wall coating mud, cement coagulant accounted for 40%.

Main uses of vermiculite:

Construction: lightweight material lightweight concrete aggregate (lightweight wall powder, lightweight mortar)
Heat-resistant material wall material, fire-proof board, fireproof mortar, fireproof brick.
Heat preservation and insulation: sound absorbing materials, underground pipes, greenhouse pipes, insulation materials, indoor and tunnel installations, walls and ceilings in public places.
Metallurgy: steel frame cladding material, iron, casting slag removal high-rise building steel frame cladding material, vermiculite bulk.
Agriculture and forestry: horticulture, golf course lawn, seed preservatives, soil regulators, wetting agents, plant growth agents, feed additives.
Marine Fishing Industry: Bait fishing.
Other aspects: adsorbent, filter aid, active carrier of chemical products and chemical fertilizers, sewage treatment, seawater oil adsorption, cigarette filter, explosive density regulator.
Vermiculite of different size has different uses
+20 mesh: building insulation equipment, household refrigerator, automobile sound-reducer, sound-proof plaster, safe and cellar lining pipes, boiler heat jacket, ladle for ironworks, firebrick insulation cement.
20~40 items: automobile insulation equipment, aircraft insulation equipment, cold storage insulation equipment, bus insulation equipment, wall board water cooling tower, steel annealing, fire extinguisher, filter, cold storage.
40~120 mesh: linoleum, roof board, eaves board, dielectric ram.
120~270 mesh: wallpaper printing, outdoor advertising, paint, increase the viscosity of paint, fireproof card paper for corkboard photography.
-270 mesh: gold and bronze ink, paint, external supplement.

1: The expansion vermiculite on the roof, can play a good heat insulation effect, make the building warm in winter and cool in summer. Vermiculite bricks built into high-rise building wall panels, can play the role of sound insulation, fire prevention, moisture-proof, but also reduce the load of the building.
2: Vermiculite used in the greenhouse, with loose soil, good air permeability, strong water absorption, small temperature changes and other characteristics, conducive to the growth of crops, but also reduce the input of fertilizer. It is an essential ingredient in the nascent technology of soilless cultivation.
3: Vermiculite and the right amount of insulation glue mixed, can be made of insulation board.
4: Vermiculite can be used for artificial breeding reptile incubation pad.
5: Vermiculite is also used in medicine and health, animal feed and other lines.
In tetrahedral tablets, Al replaces Si by 1/3~1/2, and Fe3 can also replace Si. The substitution of Si by Al and Fe3 is the main cause of layer charge. The charge per chemical formula is between 0.6 and 0.9. Layer charge compensation is caused by Al instead of Mg in the octahedron on the one hand and by interlayer cations on the other hand. Interlayer cations are mainly Mg, Ca, Na, K, (H3O), Rb, Cs, Li, Ba, etc. The cations in octahedral tablets are mainly Mg, but can also include Fe3, Al, Cr, Fe2, Ni, Li, etc. The content of interlayer water depends on the hydration capacity of interlayer cations and the ambient temperature and humidity. With higher hydration capacity Mg, the unit chemical formula can contain 4~5 water molecules under high temperature and humidity. However, when cations are Cs with weak hydration ability, almost no water molecules can be found.

Mineral properties of vermiculite:

The chemical formula of vermiculite is (Mg, Ca)0.7(Mg, Fe, Al)6.0[(Al, Si)8.0](OH4.8H2O). Monoclinic, usually lamellar. Brown, tan or bronze. Grease luster. Hardness 1~1.5. When the density of vermiculite is 2.4-2.7g /cm3 and it is roasted at 800-1000 ℃, the volume of vermiculite expands rapidly and increases 6-15 times, and the height of vermiculite can reach 30 times. The average bulk density of vermiculite after expansion is 100~200Kg/m3 because the vermiculite after roasting expansion has fine air insulation layer, so it has excellent thermal insulation performance.

Quality classification:

The grade of vermiculite quality is based on the expansion factor size, sheet plane size and impurity content of the vermiculite. But because vermiculite varies so much in appearance and composition, it is difficult to make an exact classification. Therefore, it is mainly based on its volume expansion multiple as the basis of classification. Several grading standards are described as follows:
1. Classification by volume expansion multiple.
Grade I: Vermiculite has large leaves, which cannot be split into complete flakes. Color is brass, bronze or light green, pearl or fat luster, after calcination becomes golden, vermiculite volume expansion of more than 8 times.
Second grade product: vermiculite leaves larger, not easy to split into a complete sheet. The colors are brown, dark bronze, and green, with a pearl or glass sheen. After calcination, the volume of vermiculite expands 6-8 times.
Grade 3: vermiculite leaves are small, thin section some elastic, uneven surface. The color is dark brown, dark green and somewhat glassy. The volume expansion of vermiculite after calcination is 3~5 times.
Grade four: slightly hydrated vermiculite, and mica have similar appearance, and sandwiched without hydration mica, easy to split into thin slices, color is dark green or nearly black, glass luster, after calcined vermiculite volume expansion below 3 times.
2. Grade according to the plane size of vermiculite blade.
Grade one: more than 15 mm.
Second grade :4~15 mm.
Grade 3 :2~4 mm.
Grade four: less than 2 mm.
3. Classification by impurity content of other minerals in vermiculite ore.
Grade 1: Impurity content less than 3% (by weight).
Second grade: impurity content of 4~9%(by weight).
Grade 3: Impurity content of 10-,-,15%(by weight).
Grade 4: Impurity content more than 15% (by weight)

Expanded vermiculite

Vermiculite is a kind of hydrate, in the form of lumps and sheets. The interlayer water molecules are heated at high temperature, and the volume increases by 6-15 times. Rich in nitrogen, phosphorus, potassium, aluminum, iron, magnesium, silicate and other components. Vermiculite has higher layer charge number, so it has higher cation exchange capacity and stronger cation exchange adsorption capacity. Characteristics are: light weight, good adsorption performance of water and fertilizer, non rot, can be used for 3-5 years (unlike humus, coconut shell, etc., easy to rot).

The raw vermiculite ore becomes expanded vermiculite after roasting at high temperature.

Expanded vermiculite conventional particle size specifications are 0.5-1mm, 1-3mm, 2-4mm, 3-6mm, 4-8mm, 1-6mm, etc. In addition, we can also produce other particle size models according to customer’s production needs. Vermiculite powder from raw vermiculite ore by high temperature roasting, screening, grinding processing into powder. The main models are 40 mesh, 60 mesh, 100 mesh, 200 mesh, 325 mesh. Applications: house insulation equipment, household refrigerator, automobile sound-reducer, sound insulation plaster, safe and cellar lining pipe, boiler heat coat, ironworks ladle, firebrick, insulating cement, automobile insulation equipment, aircraft insulation equipment, refrigerated storage equipment, bus insulation equipment, wall board water cooling tower, steel annealing, fire extinguisher, filter, refrigerated storage, linoleum, Roofing board, eaves board, dielectric ram, wallpaper printing, outdoor advertising, paint, increase the viscosity of paint, fireproof card paper for photographic corkboards, golden and bronzing ink, paint supplements, etc.

Agriculture

Agriculture, vermiculite can be used as a soil conditioner, because of its good cation exchange and adsorption, can improve the structure of the soil, water storage and soil moisture, improve the soil permeability and water content, acid soil into neutral soil; Vermiculite can also play a buffer role, preventing the rapid change of PH value, so that fertilizer in the crop growth medium slow release, and allow slightly excessive use of fertilizer without harm to the plant; Vermiculite can also provide K, Mg, Ca, Fe and trace Mn, Cu, Zn elements to crops. Vermiculite has the characteristics of water absorption, cation exchange and chemical composition, so that it plays the role of fertilizer preservation, water retention, water storage, breathable and mineral fertilizer. The experiment showed that adding 0.5-1% vermiculite into compound fertilizer could increase crop yield by 15-20%.

Horticulture

Horticulture, vermiculite can be used for flowers, vegetables, fruit cultivation, seedling and other aspects. In addition to potting soil and conditioner, also used for soilless cultivation. As a nutritious base for growing potted trees and commercial beds, it is particularly advantageous for transplanting and transporting plants. Vermiculite can effectively promote the growth of plant roots and the stable development of seedlings. Provide water and nutrients necessary for plant growth for a long time, and keep the root temperature stable. Vermiculite can make crops from the early growth can obtain sufficient water and minerals, promote faster growth of plants, increase production.

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., specifications can be produced according to requirements.

After roasting at high temperature, the volume of raw vermiculite can rapidly expand several times to dozens of times. The volume of vermiculite after expansion is called expanded vermiculite.

It is a layered structure, containing crystalline water between layers, bulk density of 50-200kg/m3, small thermal conductivity, is a good insulation material. Good quality expanded vermiculite, the highest use temperature can reach 1100℃. In addition, expanded vermiculite has good electrical insulation. Expanded vermiculite is widely used in insulation materials, fireproof materials, seedlings, flowers, trees, friction materials, sealing materials, electrical insulation materials, coatings, boards, paint, rubber, refractory materials, hard water softener, smelting, construction, shipbuilding, chemical and other industries.

Expanded vermiculite has a wide range of uses, but its main use is still as a building material. In 1986, expansive vermiculite used as mortar and cement premix and lightweight concrete aggregate accounted for 52% of the consumption structure in the United States. Britain used for concrete, wall coating mud, cement coagulant accounted for 40%.

Vermiculite product specifications :0.5-1mm, 1-3mm, 2-4mm, 3-6mm, 4-8mm.
Vermiculite main types are :20-40 mesh, 40-60 mesh, 60-80 mesh, 200 mesh, 325 mesh.

Hirudite

Vermiculite is made of expanded vermiculite and a certain dose of adhesive, after hot or cold pressing and made of plate. The plate has the characteristics of heat preservation, heat insulation and fire prevention. This product can be used in fireproof door core, fireplace lining, wall material.

Hirudite SLATE is a new type of inorganic material, with expanded vermiculite as the main raw material, mixed with a certain proportion of inorganic adhesive, after a series of processes into a high temperature resistance, fire prevention, green environmental protection, heat insulation, sound insulation, does not contain harmful substances of the board. No gas harmful to human health is produced when heated to 1200℃ at high temperature, and the combustion performance reaches grade A.

Hirudite has been widely used in construction, shipbuilding, metallurgy, electric power, aerospace and other fields abroad. Hirudite SLATE can be used in furniture, firewall, ceiling, but also can be used for fire access, steel beam cladding, pipeline cladding, real fire fireplace lining board, wall partition. 1, fire door core; 2. Advanced kitchenware and furniture; 3. Hull plate; 4. Fire passage and ventilation system; 5. Commercial buildings, banks, libraries, hotels, restaurants, entertainment venues, senior residences, ordinary residences, etc.; 6, kiln insulation; 7. Fireplace insulation; 8, industrial thermal insulation materials

Production, storage and transportation

Vermiculite is generally used in open-pit mining, mostly artificial drilling, explosive blasting, etc., it needs to be sealed and preserved, and stored at room temperature, away from light, ventilated and dry place.