The microporous structure and heating dehydration of gypsum and its products make it have excellent sound insulation, heat insulation and fire prevention properties.
Chinese name: gypsum mbth: gypsum alias: gypsum type: hydrated sulfate chemical formula: CaSO4 2H2O molecular weight: 172 color: white, colorless, yellow-red luster when containing impurities: glass, spun silk or pearl luster transparency: transparent to translucent stripes: white crystal system: monoclinic cleavage: extremely complete fracture: shell-shaped, sometimes fibrous hardness: 2 brittleness:. Distribution: widely distributed classification, basic properties, chemical composition, structural form, resource status, main producing areas, metallogenic types, identification characteristics, medical applications, pharmacological effects, drug taboos, drug compatibility, traditional Chinese medicine prescriptions, clinical applications, commonly used prescriptions, food industry applications, industrial applications and industrial production. Generally gypsum can refer to gypsum and anhydrite. Gypsum is calcium sulfate dihydrate (Ca [SO4] 2H2O), also known as dihydrate gypsum, hydrated gypsum or soft gypsum. The theoretical components are CaO32.6%, SO346.5% and H2O+20.9%. The crystal is monoclinic, usually in dense block or fiber shape, white or gray, red and brown, with glass or silk luster and Mohs hardness. Anhydrous calcium sulfate (Ca [SO4]) is anhydrite, and its theoretical composition is CaO4 1.2% and SO358.8%. The crystal is rhombic, usually dense, massive or granular, white and off-white, with glass luster, Mohs hardness of 3-3.5, and perfect cleavage parallel {0 10}. Two kinds of gypsum are often produced together and can be transformed into each other under certain geological conditions. The basic properties of natural gypsum dihydrate (CaSO4 2H2O) are also called gypsum. After calcination and grinding, β -type semi-hydrated gypsum (2caso4 H2O) can be obtained, that is, building gypsum, also called plaster and gypsum. If the calcination temperature is190 C, model gypsum can be obtained, and its fineness and whiteness are higher than those of building gypsum. If raw gypsum is calcined at 400-500℃ or above 800℃, floor gypsum can be obtained. Its setting and hardening are slow, but the strength, wear resistance and water resistance after hardening are better than ordinary building gypsum. Usually white, colorless and colorless transparent crystals are called transparent gypsum, and sometimes they are gray, light yellow, light brown and other colors because of impurities. The stripes are white. Transparent. Glass luster, cleavage pearl luster, fiber aggregate silk luster. Cleavage is extremely complete and moderate, and the cleavage sheet splits into rhombuses with plane angles of 66 and114 respectively. Sexually fragile. The hardness is 1.5~2. Slight changes in different directions. The relative density is 2.3. Under the polarizer: colorless. Biaxial crystal (+). 2V=58 .Ng= 1.530, Nm= 1.523, Np= 1.52 1 .2V decreases with the increase of temperature, and 2V is zero around 90℃.
During the heating process, the crystal water is discharged in three stages: 105~ 180℃. First, 1 water molecule is discharged, and then half of the water molecule is immediately discharged, which is converted into calcined gypsum Ca [SO4] 0.5H2O, also known as plaster of Paris or gypsum hemihydrate. In the temperature range of 200 ~ 220℃, the remaining half of the water molecules are discharged and converted into type Ⅲ anhydrite Ca [SO4] ε H2O (0.06
Diamond crystal, C2h-2/m(L2PC). Crystals often develop into flakes or granules. Ordinary simple forms: parallel double-sided B, P, oblique square column M, L, etc. Crystal plane and usual longitudinal stripes; Sometimes it is lentil-shaped. Twins are common, one is Gary twin or dovetail twin with (100) as crystal plane, and the other is Paris twin or arrowhead twin with (10 1) as crystal plane. Aggregates are mostly dense granular or fibrous. Fine-grained blocks are called alabaster; Fiber aggregate is called fiber gypsum. Rare rose-like polymer formed by lentil crystals. There are also soil-like and flaky aggregates. Natural gypsum is a kind of gypsum stone in nature, mainly gypsum dihydrate and anhydrite. China is rich in gypsum mineral resources. The total proven gypsum reserves are about 57 billion tons, ranking first in the world. It is distributed in 23 provinces, municipalities and autonomous regions, of which 10 exceeds 1 100 million tons, followed by Shandong, Inner Mongolia, Qinghai, Hunan, Hubei, Ningxia, Tibet, Anhui, Jiangsu and Sichuan, and gypsum resources are relatively poor.
Gypsum resources in China are mainly ordinary gypsum and anhydrite, of which anhydrite accounts for more than 60% of the total, while super-grade and first-grade gypsum only accounts for 8% of the total, and fiber gypsum only accounts for 1.8% of the total. Therefore, we are a large country with gypsum reserves and a poor country with high-quality gypsum reserves. High-quality gypsum resources are mainly distributed in Yingcheng and Jingmen in Hubei, Hengshan in Hunan, Sanshui in Guangdong, Zaozhuang in Shandong and Pinglu in Shanxi. Some mines have been overexploited and almost exhausted, and some are difficult to separate from low-grade gypsum, resulting in a waste of high-quality resources. Therefore, the proportion of high-quality gypsum resources that can be actually exploited and effectively utilized in China is even less.
Although China's gypsum industry started late and has a poor foundation, it has developed rapidly. 195 gypsum output soared to 26.59 million tons, surpassing the United States and becoming the world's largest gypsum consumer. By 2004, the annual output of China's gypsum mines is more than 30 million tons, and the total consumption of gypsum is about 35 million tons. There are more than 500 gypsum mining mines in China, about 50 large and medium-sized mines, with an annual output of over 654.38+10,000 tons, accounting for 40% of the total output, and the output of small township mines accounts for about 60% of the total output. According to the mode of production, open-pit mining accounts for about 30%, and underground mining accounts for about 70%. Due to various reasons, the average recovery rate of underground gypsum mine is lower than 30%, and the high-quality resources that have been given priority to mining have not been rationally developed and effectively utilized, which is a serious waste of resources, which is sad!
Gypsum dihydrate is the most widely used natural gypsum, and its effective component is calcium sulfate dihydrate. Gypsum is generally classified according to the content of calcium sulfate dihydrate in ore. Gypsum has a wide range of uses and products. Different uses have different requirements for the quality of gypsum raw materials. High-grade gypsum is mostly used as raw material for producing special gypsum products, such as food, medicine, art, model and chemical filler. Gypsum mine with calcium sulfate dihydrate content less than 60% is rarely used; According to the content, more than 60% gypsum mines are used in building materials, architecture and other fields.
The consumption structure of gypsum in different countries in the world is different, and the consumption of gypsum deep-processed products in developed countries accounts for a large proportion. The consumption structure of gypsum is: products account for 45%, cement production accounts for 45%, and other fields account for 10%. The development of China is mostly focused on the primary utilization of ore, which depends on the cement industry, and the proportion of gypsum products is gradually increasing with the economic development. The consumption structure of China is roughly as follows: 84% is used as retarder in cement production, 6.5% is used for ceramic molds, 4.0% is used for gypsum products and wall materials, and 5.5% is used in chemical industries; With the increase of cement production in China, the demand for gypsum also increases accordingly. At the same time, with the rapid economic growth in China, the gypsum industry, especially gypsum products, will have great development space. Various gypsum products and gypsum walls will develop at a high speed, and the demand for gypsum will increase sharply. With the development of traditional ceramics and other special industries, high-quality gypsum resources will continue to decrease, and the development and utilization of gypsum resources will be paid more attention. Therefore, in order to ensure the sustainable development of the whole gypsum industry, green, environmentally friendly and healthy gypsum building materials and products are widely used in people's lives, and the limited gypsum resources must be optimized. The largest gypsum producer in the world is the United States. In the United States, gypsum deposits are distributed in 22 States, and there are 69 mines in * * *, with the largest production area in Fort Dodge, Iowa; Followed by Canada; France is in a leading position in Europe in gypsum production; Once again for Germany, Britain and Spain. China gypsum mine is rich in resources. There are gypsum mines in 23 provinces (regions) of China. There are 0/69 mining areas with proven reserves, with a total ore reserve of 57.6 billion tons. In terms of regional distribution, Shandong gypsum mine is the largest, accounting for 65% of the national reserves; Inner Mongolia, Qinghai and Hunan followed closely. The main gypsum mining areas are Dige Town, Zaozhuang, Shandong, Otog Banner, Inner Mongolia, Yingcheng, Hubei, Hunjiang, Nanjing, Dawenkou, Shandong, Qinzhou, Guangxi, Taiyuan, Shanxi and Zhongwei, Ningxia. Ore-forming gypsum deposits are mainly sedimentary deposits, accounting for more than 90% of the national reserves. Supergene and hydrothermal metasomatism gypsum deposits are not very important. Gypsum deposits have been produced in various geological ages, among which the early Cretaceous and tertiary sedimentary gypsum deposits are the most important.
It is mainly the product of chemical deposition, often forming a huge seam or lens, occurring in limestone, red shale and sandstone, marl and clay rock series, and often coexisting with anhydrite and halite. The anhydrite layer near the surface is transformed into gypsum under the action of surface water due to the decrease of external pressure: caso4+2h2o-caso4.2h2o; At the same time, the volume increased by about 30%, which caused the destruction of gypsum layer. The distinguishing feature is low hardness, a set of perfect cleavage, and the shapes of various features can be distinguished. Dense massive gypsum can be distinguished from carbonate because of its low hardness and no foaming when exposed to acid. One of the standard minerals in hardness classification. Pharmacological action of medical application 1. Antipyretic effect Gypsum has no cooling effect on normal body temperature, but it has certain antipyretic effect on artificially febrile animals and obvious antipyretic effect on artificially febrile rabbits, and its antipyretic effect may have nothing to do with the effect of its main component calcium. Gypsum plaster soup 1.5g/kg has no antipyretic effect on rabbits with fever caused by injection of typhoid pentavaccine. If the rabbits were given gypsum decoction 1.5g/kg, and then injected with typhoid pentavaccine, the body temperature could not be greatly increased. The antipyretic effect of gypsum is rapid, but the duration is short. The cooling effect of 5g/kg gypsum on rabbits with typhoid fever was similar to that of 0.2g/kg antipyrine, and the cooling effect was significant half an hour after taking the medicine, with the strongest effect of 1 ~ 1.5 hours. Baihu decoction and Danshi decoction have certain antipyretic effects on experimental fever rabbits; Anemarrhena and Glycyrrhiza mixture and decalcified Baihu decoction without gypsum have no obvious antipyretic effect. It can be considered that gypsum is the main antipyretic drug of Baihu decoction, and its effect can be enhanced by other drugs in the prescription, but it does not increase with the increase of gypsum dosage. The blood calcium level of experimental animals was measured before and after administration, which showed that the increase of blood calcium level was closely related to antipyretic effect. It is reported that the antipyretic effect of gypsum combined with Anemarrhena asphodeloides is stronger than Anemarrhena asphodeloides. The antipyretic component of Anemarrhena asphodeloides is mangiferin, and pure calcium sulfate is ineffective. Therefore, it is speculated that the antipyretic effect of gypsum is caused by components other than calcium sulfate. The experimental results show that the antipyretic effect of Maxingshi dry soup combined with gypsum (after decoction and crushing) is stronger than that of gypsum combined with gypsum. It is also reported that the supernatant of gypsum and gypsum powder 1: 1 decoction was given to rabbits with fever caused by typhoid vaccine, and no obvious antipyretic effect was found. Foreign experiments on experimental febrile rats have proved that gypsum has no obvious antipyretic effect, but when animals are thirsty by banning drinking water, causing fever by endotoxin, giving diuretics, feeding salt and radiating heat, gypsum can reduce the water consumption of rats, that is, relieve their thirst. 2. Effect on cardiovascular system Gypsum extract has no effect on frog's in situ heart, but a small dose of Gypsum extract can excite toad's heart and rabbit's isolated heart, while a large dose can inhibit it, and the heart can return to normal after rehydration. Intravenous injection of 4% gypsum supernatant (0. 1ml/kg) had no effect on respiration, blood pressure and blood flow of rabbits and cats, but when the injection amount was above 1ml/kg, respiration was inhibited, blood pressure decreased, blood flow decreased and heart rate slowed down. Intravenous injection of 0.2ml/kg gypsum solution can temporarily reduce the femoral artery blood flow in rabbits and cats, and then increase it to reduce the coronary artery blood flow. 3. Effect on smooth muscle: A small dose of gypsum supernatant can increase the amplitude of isolated small intestine and uterus of rabbits, but a large dose can decrease it. Gypsum can also increase the urine volume of mice, slow down the intestinal propulsion function and increase the bile excretion of rats and cats. 4. Other functions: Gypsum is partially turned into soluble calcium salt after oral administration with gastric acid. When absorbed into the blood by the intestine, it can increase the concentration of calcium ion in serum, inhibit the ability of nervous stress (including the thermoregulation function of the central nervous system), reduce the excitability of skeletal muscle, relieve muscle spasm and reduce vascular permeability. In vitro culture experiment, the gypsum Hanks solution of 1: 1 can obviously enhance the phagocytosis of rabbit alveolar macrophages to Staphylococcus albus and colloidal gold, and promote the maturation of phagocytes. Ca++ can improve the capture rate of alveolar macrophages, enhance their phagocytic activity and accelerate their removal of dust particles, which is of great significance to maintain the physiological function of macrophages. Therefore, it can be considered that Ca++ plays an important role in the above functions of gypsum. Long-term feeding gypsum can increase the calcium content of pituitary gland, adrenal gland, submandibular gland, pancreas and thymus in rats. However, the content of calcium in thymus increased and the content of spleen decreased in rats with thyroidectomy and parathyroidectomy. In the presence of ATP in the body, gypsum is fractionated by enzymes and APG, which increases the plasma concentration of 34S, thus playing an antiviral role. Gypsum is cool, and it is forbidden to clear away heat and toxic materials 1, and it is forbidden for people with spleen and stomach weakness, blood deficiency, fever and yin deficiency.
2. "Notes on Materia Medica": "Chicken makes it. Evil grass and horses are poisonous to many people. "
3. Medicinal property theory: "Croton hates iron."
4, the dosage is too large, after taking it, there will be fatigue, listlessness, poor appetite and so on.
5, gypsum is a cold product, easy to hurt Yang.
6. Gypsum should not be used together with the following western medicines:
① Tetracycline antibiotics and gypsum will reduce the solubility and absorption rate of this group of antibiotics.
② It should not be taken with isoniazid, which will reduce its curative effect.
③ It is not suitable to take prednisone at the same time, which will reduce its bioavailability. Keywords drug compatibility 1, mulberry leaves, clearing lung heat;
2, with cassia twig, both inside and outside;
3, with angelica dahurica, clearing away heat and purging fire, reducing swelling and relieving pain;
4. Use Anemarrhena asphodeloides to clear away heat and trouble;
5, use Pinellia ternata, clear lung and stomach, reduce adverse flow and eliminate phlegm;
6, with licorice, clearing the lungs and relieving cough;
7. Use bamboo leaves to clear away heat and trouble. Chinese medicine prescription 1, Treatise on Febrile Diseases with Baihutang: Yangming's Qi and Heat;
2, bamboo leaf gypsum soup "Treatise on Febrile Diseases": After the typhoid fever is solved, the residual heat is not clear;
3, Maxing Shigan Tang "Treatise on Febrile Diseases": exogenous wind evil, lung heat cough and asthma.
4, Shuangyu San "Su Wen Pathogenesis and Life-saving Collection": phlegm heat asthma, phlegm is like a spring.
5. Yulu San's "children's medical syndrome is straight": children are yellow and thin, with fever and vomiting.
6, gypsum powder "Puji Fang": hot cough. 7. Gypsum antihypertensive pillow According to the ninth volume of Li Shizhen's Compendium of Materia Medica in Ming Dynasty, "Gypsum is also called fine stone, also known as" cold stone ",which is mainly used to relieve cold and heat caused by stroke, such as muscle sweating, dry mouth, headache and toothache. It is a good medicine for reducing fever. According to the theory of traditional Chinese medicine and folk use, it is proved that hypertension is a fever with gypsum coldness. Gypsum hypotensive pillow made of gypsum can naturally regulate the normal temperature of brain and brain by using cold and hot energy, so that the cerebral vessels can work normally and the blood pressure can be effectively controlled. In China, people made pillows with natural gypsum very early. In the Tang Dynasty, there was a poem "Gypsum Pillow", which was "bright inside and outside without carving, but as white as Yao as cold in spring". Afraid of the wind blowing the sun and selling it. "Gypsum pillow is made of fine fiber gypsum (transparent) in natural gypsum mine and carefully carved and ground by hand. It is a pillow with multiple health care and medicinal effects such as lowering blood pressure, protecting the spine, relieving troubles and pains, helping sleep and calming the nerves. Clinical application 1, used for fever, lung and stomach fever, high fever, thirst, dysphoria, pulse sinking, etc. Gypsum is very cold, good at clearing qi and dividing excess heat, and is suitable for the symptoms of excess heat in lung and stomach. It is often used with Anemarrhena asphodeloides to enhance the effect of clearing interior.
2. A fever with high fever and rash. Febrile disease spots are mostly caused by stomach fire and blood heat, which is a phenomenon of qi and blood burning. Gypsum, which has a strong heat-clearing and fire-purging effect, is commonly used in clinic, and it is compatible with drugs such as Scrophularia, Cortex Moutan, Radix Paeoniae Rubra, Radix Rehmanniae and Radix Isatidis to cool blood and detoxify.
3. Used for headache, toothache and gum swelling and pain caused by excessive stomach fire. Gypsum can clear stomach fire, so it is compatible with Anemarrhena asphodeloides, Achyranthes bidentata and Radix Rehmanniae for diseases caused by excessive stomach fire.
4. Used for cough and asthma due to lung heat. Pathogenic heat attacks the lungs, causing high fever, cough, shortness of breath, nasal fan, thirst and other symptoms. Plaster can clear lung heat, and ephedra, almond and other products (i.e. Maxingshi dry soup) can clear lung heat, relieve cough and asthma.
5, used for eczema, fire and water burns, long-term unhealed sores and long-term unhealed wounds. Gypsum powder is used externally to treat the above surgical diseases, and has the functions of clearing away heat, astringing and promoting granulation. It is often used with Sheng Dan, Huang Bai and Indigo Naturalis. Commonly used prescription 1, treating Sanyang syndrome, abdominal heavy rollover, bad mouth, dirty face, sweating in enuresis, sweaty forehead, cold hands and feet, spontaneous sweating: Anemarrhena asphodeloides, gypsum, 1 kg (crushed), licorice (baked), japonica rice in six pairs. Boiling rice with water and cooking noodle soup serve four tastes. Take one liter of warm clothes three times a day. (White Tiger Decoction in Treatise on Febrile Diseases)
2. At the beginning of treating febrile diseases, the pulse is floating and the body is strong and hot, while at the beginning of treating colds, the heart is hot without aversion to cold: gypsum is two or two (rolled fine) and glutinous rice is two and a half. Fry the first two flavors with three bowls of water until the rice is cooked, and you can get about two bowls of clear juice. Drink as much as possible while it's hot, so that you are sweaty and disgusting. If Yangming's internal organs are already very hot, there is no need to take slow-warming drinks to eliminate their heat. (Gypsum japonica rice soup in The Journey to the West)
3, the treatment of typhoid fever, headache, high fever, salivation, palpitation, crying, unevenness, upset, the treatment of qi stagnation: gypsum, cold water stone, brain flower one or two, half a word each. The top is the bottom of Dengxin soup. Add and subtract sizes. ("Puji Fang" Tao Hongfen)
4, treatment of typhoid fever, phlegm tide, stagnation, dizziness, headache, dizziness, ninja: gypsum (calcined fine powder) onion tea is two yuan each. Add and subtract the size of the child. ("Three Causes" Jade Chip Powder)
5. Treat Yangming's internal heat, polydipsia, headache, constipation, fever, macula, excessive phlegm, asthma and cough: gypsum 62 (raw) powder licorice 12. At the top, it's very fine. Every time you take a glass or two of water from San Qian, or hot soup, or ginseng chicken soup. It is also great to add cinnabar and San Qian to this formula. ("Jing Yue Quan Shu" Yuquan III)
6, the treatment of Taiyin fever can not sweat and sweat, but if you don't sweat, you will have a rash. If you sweat too much, you will be in a daze. Spotted: Gypsum Fibrosum, Anemarrhena rhizome, Siqian, Radix Glycyrrhizae, San Qian Scrophulariae, San Qian rhinoceros horn, Erqian and white glutinous rice. Boil eight cups of water, take three cups of residue, and cook for one night three times a day. According to China's Hygienic Standard for the Use of Food Additives, gypsum is used as a coagulant in the production of canned food and bean products, and the dosage depends on the needs of normal production. When used to make tofu, the addition of soybean milk is 2~ 14g/L, and excessive amount will produce bitterness, that is, gypsum is about 2.25% of raw materials in summer and 4. 1% of raw materials in winter. When used to make dried tofu, the amount of gypsum is about 2% of the raw material in summer and 4.3% of the raw material in winter. In the production of canned tomatoes and potatoes, calcium sulfate can be used as tissue enhancer, and 0. 1%~0.3% can be added according to the production formula. According to FAO/WHO 1984, it is used as coagulant in canned tomatoes, and the dosage is: 0.8g/kg；; Block; Complete package, 0.45g/kg (used alone or mixed with other coagulants). Industrial gypsum belongs to monoclinic system, which has high cleavage degree and is easy to crack into thin slices. Gypsum hemihydrate can be obtained by heating gypsum to100 ~ 200 C and losing part of crystal water. It is a kind of air-hardening cementitious material, which has two forms, α and β, both of which are rhombic crystals, but their physical properties are different. α-hemihydrate gypsum has good and firm crystallization; β-hemihydrate gypsum is a kind of flaky cracked crystal, and its specific surface area is much larger than that of α-hemihydrate gypsum. When producing gypsum products, α-hemihydrate gypsum uses less water than β-hemihydrate gypsum, and the compactness and strength of the products are higher. Generally, α -type hemihydrate gypsum, also known as high-strength gypsum, is obtained by distillation in an autoclave in saturated steam medium. β-hemihydrate gypsum, that is, building gypsum, is calcined in a wok or a rotary kiln opening device. Chemical gypsum is an industrial by-product, which has the same properties as natural gypsum and does not need too much processing. The slurry mixed with gypsum hemihydrate and water newly forms gypsum dihydrate, which quickly sets and hardens during drying to gain strength, but softens when it meets water.
Gypsum is the main raw material for producing gypsum cementitious materials and gypsum building products, and it is also the retarder of portland cement. Gypsum is calcined at 600 ~ 800℃, and a small amount of lime and other catalysts are added, and anhydrite cement (also known as Guinness cement) is obtained by grinding. After calcination and grinding at 900 ~ 1000℃, high temperature calcined gypsum can be obtained. The strength of products made of these two kinds of gypsum is higher than that of building gypsum products, anhydrite binder has better heat insulation, and gypsum calcined at high temperature has better wear resistance and water resistance. Gypsum board building gypsum production of building products mainly include:
(1) gypsum board. A small amount of adhesive, fiber, foaming agent, etc. Adde into building gypsum, then mix with water, continuously pouring between two layers of protective pap, and then rolling, curing, cutting and drying. The plate thickness is 9 ~ 25mm, and the dry bulk density is 750 ~ 850kg/m3. The plate is good in toughness, non-combustible, stable in size, smooth in surface, sawable and cut, and convenient in construction. Mainly used for indoor partition, interior wall veneer, ceiling, sound absorption board, etc. However, due to poor water resistance, it is not suitable for humid environment.
② Fiber gypsum board. Building gypsum slurry mixed with fiber and other additives is formed by winding, filter pressing or rolling, and then cut, solidified and dried. The general thickness is 8 ~ 12mm. Compared with gypsum board, its bending strength is higher, and it does not need tissue paper and adhesive, but its bulk density is larger, and its use is the same as gypsum board.
③ Decorative gypsum board. The prepared building gypsum slurry is poured into the pattern frame of the bottom mold, and after smoothing, curing, demoulding and drying, the thickness of the board is about10 mm. In order to improve its sound absorption effect, it can also be made into boards with perforations and blind holes, which are often used as ceilings and decorative walls.
④ Gypsum hollow slats and gypsum blocks. The building gypsum slurry is poured into the mold, vibrated and solidified, then demoulded and dried. The thickness of hollow lath is generally 60 ~ 100 mm, and the porosity is 30 ~ 40%. The block size is generally 600×600 mm, the thickness is 60 ~ 100 mm, and there are tenons and grooves around it. Sometimes it can be made into a hollow block with a round hole. Hollow slats and blocks are built with special gypsum, which is convenient for construction and often used as non-load-bearing internal partition walls. Industrial production of gypsum ore According to the data of USGS Mineral Yearbook, in 2004, the natural gypsum mined and consumed in the world reached/kloc-0.06 million tons. The United States has the largest mining volume, reaching180,000 tons, accounting for 654.38+07% of the global mining volume; Followed by Iran (10.8%), Canada (8.5%), Spain (7. 1%) and China (6.5% or 6.9 million tons) (but according to statistics of relevant departments in China, it is 29 million tons, mainly used for cement production). The other country in the top 65,438+00 is Thailand. According to OneStone, a German consulting company, about 45% of natural gypsum in the world is processed into mature gypsum. The annual output of gypsum plaster in the world is about 66.5 million tons, of which 60% or 40 million tons comes from natural gypsum, and 40% or 26.5 million tons comes from synthetic gypsum and recycled waste gypsum. It is estimated that the global annual output of synthetic gypsum is about1600,000 tons, of which about 35 million tons comes from the desulfurization gypsum produced by the desulfurization system of power stations, about1/0,000 tons is phosphogypsum, a by-product of phosphate fertilizer production, and about/kloc-0,000 tons is titanium gypsum and other chemical gypsum. 90% of synthetic gypsum used in gypsum industry comes from desulfurization gypsum. For gypsum industry, about 80% of plaster of Paris is used to produce building wallboard. About 20% is used to produce gypsum plaster or other gypsum products. It is very important for gypsum board factory to shorten the setting time of gypsum. A combined production process of flash burning, grinding and calcination is usually used. For the utilization of desulfurized gypsum, the calciner and related supporting hammer mill are designed by each factory according to its own process. The grinding and calcining system and its supporting vertical roller mill account for about 40% of the market. The market leader is Claudius Peters Technology. In the past two years, he has won 9 orders for EM pulverizer systems. Gebr。 Pfeiffer AG's MPS gypsum mill can meet almost any production requirements, and it is allowed to add up to 45% desulfurization gypsum during calcination. Gypsum board factory uses downstream dryer or countercurrent dryer for drying. For fiber gypsum board drying, dry screen machine is used for drying. The stay time of gypsum board in the dryer with the smallest space can reach 32 ~ 40 minutes, and each group is designed with 6 ~ 16 boards and 3 drying areas. The accuracy of the feeding device of the downstream dryer is very important. Firstly, the plates are cut and arranged on a series of plates, and then stacking is started; The following board must keep the principle of "follow in, follow out" and keep the quality stable. The machine operation of gypsum board factory is becoming more and more important. This involves the coordination of wet dock equipment, drying feeding equipment and stacking equipment, as well as the coordination of drying dock equipment and stacking equipment. These equipments must be flexible to produce gypsum boards of different sizes, thicknesses and qualities. When producing different products, manual operation must meet the safety requirements. Although the transformation of mechanized production mode in modern factories can almost ensure the preparation of raw materials and the control of paper, the operation of cardboard is fully automatic. However, high-speed production also requires a perfect palletizing system at the end of production.