Dolomite has many uses:
1. Dolomite is mainly used in glass, ceramics, stone casting ingredients, magnesium-containing cement raw materials and building stones in building materials industry.
2. Dolomite is widely used in chemical industry and light industry.
The application of dolomite in metallurgical field is mainly used as basic refractory, flux, smelting metal magnesium, etc.
4. Dolomite has a broad application prospect in agriculture and animal husbandry.
Five, two practical new technologies of dolomite
1. Dolomite is mainly used in glass, ceramics, stone casting ingredients, magnesium-containing cement raw materials and building stones in building materials industry.
And other fields.
Adding a certain amount of dolomite powder to glass can effectively reduce the high temperature viscosity of glass and improve the chemical stability and mechanical strength of products. The practice also shows that the introduction of dolomite powder into the preparation of low temperature ceramics and float glass ingredients can significantly save energy consumption. After the application in Tangshan Ceramic Research Institute, Qinhuangdao Hua Yao Glass Factory and other units or enterprises, good social and economic benefits have been achieved. Generally, the quality requirements of dolomite for glass ceramics are: MgO≥ 19%, CaO≥26%, Al2O3 < 1% and Fe2O3 < 0.2%. ?
Making magnesium oxychloride cement is another important use of dolomite. This magnesium-containing cement has good compressive strength, flexural strength and corrosion resistance. In particular, magnesium oxychloride cement prepared from caustic powder prepared from refractory forged dolomite has better stability. Magnesium-containing cement has been widely used in floor slab, rapid curing pavement and pavement crack repair. The chemical composition requirements of dolomite for magnesium-containing cement are: MgO > 18%, (Te2O3+MnO2) ≤ 0.5%, R2O3 ≤ 4%. ?
Dolomite is an additional raw material in the production of cast stone, and the acidity coefficient can be effectively adjusted by introducing appropriate amount of dolomite into the ingredients. The quality requirements of dolomite used are generally: MgO > 18%, Cao > 30%. Suggest free silica SiO 2? 4% or less is appropriate. ?
In recent years, with the sustainable development of construction industry, the development and application of siliceous dolomite have been promoted. Dolomite has not only become the main mineral raw material of artificial marble and polished stone, but also some dolomite with dense structure and fine texture has developed rapidly as decorative and technological materials. It is reported that magnesium composite materials fired with high-quality dolomite as the main raw material are further processed into new decorative materials such as floor tiles, wall tiles and plates, which have many characteristics such as light weight, high strength, anti-aging and elegant appearance, and are deeply favored by people. ?
2. Dolomite is widely used in chemical industry and light industry.
There are more than ten kinds of magnesium salts prepared from dolomite. For example, Mg (OH) 2, MgO, MgO3, MgSO4 7H2O, etc. The development of magnesium salt has effectively promoted the development of papermaking, printing, coatings, rubber, plastics, reagents and other industries, and the potential economic benefits are very considerable. In recent years, dolomite ultrafine powder and its coupling products have also been widely used; Filling high-silicon dolomite powder into ordinary alcohol-based primer according to a certain amount, and then making a "special" coating with anticorrosion performance; Dolomite powder can be made into fire retardant coatings, which can be used for fire fighting in large buildings in factories and warehouses, and can also be used as a purifying agent in environmental protection. ?
It should be pointed out that silica in chemical-grade dolomite used to produce magnesium salts should exist in a timely state. If it exists in dolomite in the form of silicate, it will affect the quality of light magnesium carbonate and other products. The quality requirements of chemical grade dolomite are: Mg O ≥ 19%, Cao ≥ 29%, (SiO2+Al2O3+Fe2O3+Mn3O4 < 7%, in which SiO2 ≤ 3.5%; At present, there is no uniform requirement for the chemical composition of rubber-plastic filled dolomite. However, the content of impurities such as iron, copper and manganese should be strictly controlled, and MnO ≤ 0.045% is appropriate. ?
The application of dolomite in metallurgical field is mainly used as basic refractory, flux, smelting metal magnesium, etc?
Basic refractory is divided into stable dolomite bricks and water-resistant dolomite bricks, which are mainly used for lining of converters, electric furnaces and cupolas. Dolomite for refractories must meet the following quality requirements: MgO ≥ 20%, (Fe2O3+Al2O3+Mn3O4+SiO2) ≤ 3%, in which SiO2 ≤ 1.5%. Dolomite for refractories only requires MgO ≥ 20%, and a small amount of impurities such as Fe2O3 and Al2O3 are allowed. This is mainly to keep the refractory bricks with good fire resistance and reduce the consumption of coke in the process of brick making. If dolomite contains high silica, 2cao silica crystals will be produced during calcination, which is a harmful substance, so the content of silica must be strictly controlled. ?
Dolomite is used as flux, that is, a certain amount of dolomite ore is added when smelting steel. The purpose is to reduce the melting point, save energy, improve the basicity of slag, which is beneficial to desulfurization and phosphorus, improve smelting conditions and stabilize product quality. The biggest advantage of using dolomite as slagging material is to prolong the furnace life by about 20-30%. Dolomite used as cosolvent has strict requirements on impurities such as brick and phosphorus. The quality of dolomite used for ironmaking is as follows: MgO > 16%, SiO2 ≤ 4%, P < 0.09%; Dolomite for converter steelmaking: MgO ≥ 20%, Cao ≥ 30%, SiO2 ≤ 1.5%.
In recent years, the application of dolomite in smelting has made new progress. If dolomite is used to prepare a new type of gunning material containing calcium and magnesium oxides, it is not only cheap, but also has a good purification effect on molten steel. The popularization and application of this kind of gunning material for alkaline steelmaking furnace will produce great economic and social benefits. ?
Smelting metallic magnesium is one of the important uses of dolomite. ? There are mature experiences at home and abroad in extracting magnesium metal from dolomite by silicothermic method, especially with the appearance of new silicothermic magnesium smelting process, the output and quality of magnesium metal have been greatly improved. There is no uniform quality standard for dolomite used in magnesium smelting in China. The reply of China Nonferrous Metals Industry Corporation to the industrial index of dolomite used in Minhe magnesium plant in Qinghai can be used for reference by all localities: MgO ≥ 20%, K2O+Na2O ≤ 0.3%, and SiO2 ≤ 3%.
It should also be pointed out that the composition of calcium and magnesium in dolomite is not completely equimolar, while the molar ratio of Cao to MgO in dolomite for magnesium smelting by silicothermic method should be kept between 1.035 ~ 1.065. Because when Cao/MgO < 1 (molar ratio), part of magnesium silicate (slag) will be precipitated in the smelting process, which will cause part of magnesium loss and affect the yield, which is particularly noteworthy. In recent years, the application and popularization of new calcination technology in external combustion rotary kiln has effectively improved the activity of calcined dolomite, thus playing a good role in stabilizing the output of magnesium. ?
4. Dolomite has a broad application prospect in agriculture and animal husbandry.
Dolomite is mainly used in agriculture to prepare calcium, magnesium, phosphorus (potassium) fertilizer, mineral micro-fertilizer and neutralizing agent for acid soil improvement. Magnesium divalent ions can promote the formation of chlorophyll and the absorption of phosphorus, and can supplement the loss of magnesium in soil. Generally speaking, the chemical composition of dolomite is required to be MgO ≥ 20% and Cao ≥ 30%, and a small amount of impurities such as SiO2 _ 2, Fe _ 2O _ 3 and Al _ 2O _ 3 are allowed to exist in the production of calcium magnesium phosphate fertilizer or calcium magnesium potassium fertilizer. Dolomite powder can be used as soil improver. For example, mixing dolomite powder with urea in Kuwait and other countries not only makes full use of fertilizer efficiency and improves crop yield, but also has obvious "mediation" effect on acidic soil. Both calcium and magnesium are essential nutrients for animals. Add appropriate amount of dolomite powder (or 0. 1 ~ 1? .5 mm particles), which is very beneficial to promote the growth and development of animals and reduce diseases. It is worth noting that the development and utilization of feed dolomite must strictly control the content of harmful elements. The specific requirements are as follows: Pb ≤ 30 ppm, AS≤ 10PPM, Hg ≤ 0. 1 ppm, and F≤20.
00PPM, acid insoluble matter ≤5%, -2mm magnetic metal particles ≤ 0.8%. ?
Five? Two practical new technologies of dolomite (patent introduction)?
A physique pigment and its preparation process (CN1114665a): The new physique pigment is made from secondary dolomite through conventional processes such as water separation, drying, crushing, grinding, grading, chemical treatment, surface treatment, PH adjustment, rinsing and the like. Its chemical composition is stable, and it has the advantages of weather resistance, anti-sedimentation, fine powder, easy dispersion, high whiteness, low cost and unique technology, and can be used in various coatings. ?
A composite magnesia cementitious material and its manufacturing method (CN 1 137027A): The key point of this invention is that dolomite ore is calcined at 650-750℃, crushed into materials with particle size less than170-325 mesh, and then mixed with magnesite in a certain proportion. The composite magnesia cementitious material can be used to produce magnesite tiles, mechanical and electrical equipment packaging boxes, building partition boards, etc. It opens up a new way for the industrial production and application of new composite materials. ?
China dolomite is rich in mineral resources and widely distributed. On the question of how to turn resource advantage into economic advantage, the author thinks that on the basis of learning from successful economies at home and abroad, combining local reality and market demand, relying on scientific and technological progress, being brave in practice and pioneering, the precious resources endowed by nature will be developed and utilized reasonably and effectively.