33 Applications of Dolomite

2021-03-18

Summary:What fields can dolomite be applied? And how much profit they can bring for us?

1. Dolomite Brick

Dolomite bricks are made of dolomite sand calcined from natural dolomite. They are mainly used in stainless steel refining furnaces (such as AOD and VOD furnaces) and cement kiln firing zones. It is the most widely used cement kiln firing zone in Europe and the United States. A common refractory material, of which 86% of the cement kiln firing zone in the United States uses this product.

2. Magnesia-calcium brick (magnesia dolomite brick)

The fired magnesia-calcium brick (magnesia dolomite brick) with w(CaO) of 20% is the largest synthetic magnesia-calcium refractory product in my country in terms of output and consumption. It is mainly used as the lining material for stainless steel refining furnaces (AOD furnaces, VOD furnaces, etc.). It replaces the magnesia chrome brick which is extremely harmful to the environment and the human body, and the use effect is good. my country's fired magnesia-calcium bricks have become the main refractory material in the stainless steel industry.

3. Unburned magnesia calcium (carbon) bricks

It is a refractory material that uses sintered dolomite sand, magnesia sand and/or graphite with different particle sizes as the main raw materials and can be used directly without firing. At present, the non-burned magnesia-calcium (carbon) bricks produced in our country have a w (CaO) of 10% to 30%, which are magnesia-calcium products with medium and low calcium, which are mainly used in refining furnaces such as LF-VD or LF, VOD furnaces. The bottom and the molten pool are located at the bottom of the GOR furnace, and the effect is good.

4. Magnesium-calcium unshaped refractory

Dolomite is also used to prepare a variety of magnesium-calcium amorphous refractories, such as electric furnace bottom ramming material, tundish coating material, ladle gunning material, converter gunning material, RH furnace gunning material, artesian hot filling material, etc. Refractory materials. In addition, the gunning material developed by using dolomite is used to repair parts such as converters, electric furnaces, ladle slag lines, and RH insertion pipes, with good results.

5. Calcium aluminate cement

Calcium aluminate cement (CMA) containing microcrystalline magnesia-aluminum spinel is a new type of binder for refractories. Wuhan University of Science and Technology uses natural dolomite with a particle size of 5-50μm and industrial oxidation with a particle size of 5~44μm. Aluminum (purity ≥95.0%) is used as raw material, after ball milling, sintering and crushing process, aluminate cement containing nano-magnesium-aluminum spinel (particle size only 50~500nm) is obtained.

6. Sintering flux

my country's ironmaking industry often uses raw dolomite, limestone, quicklime, etc. together as a flux for iron ore sintering. Depending on the type of iron ore used, the amount of dolomite added is 3% to 10%. For example, the unit consumption of dolomite per ton of sintering plant in Wuhan Iron and Steel is 55~63kg/t.

7. Raw materials for converter slagging in steel mills

Light-burned dolomite is one of the important slagging raw materials in the converter steelmaking production process. Most steel plants in my country use light-burned dolomite for converter slagging at about 13-25kg/t steel. At present, some domestic enterprises have begun to use raw dolomite to replace light burned dolomite.

8. Silicon thermal smelting of magnesium

Dolomite with a raw material size of 30-120mm is an important raw material for the production of metallic magnesium. About 98% of magnesium smelting companies in my country use the Pidgeon method (silicothermic method) to smelt magnesium, and dolomite is one of the main raw materials for magnesium smelting by the Pidgeon method. .

9. Light magnesium carbonate

Light calcium carbonate is a high-grade inorganic filler, reinforcing agent and good flame retardant in the rubber and plastic industry, a filler for high-grade inks, pigments, toothpaste and cosmetics, and a raw material for high-grade ceramics, glass and fireproof coatings. Stone is the raw material, and the CO2 in the lime kiln is recycled to produce light magnesium carbonate, which is the most widely used method.

10. Light magnesium oxide and active magnesium oxide

Light magnesia is made by calcining light magnesia carbonate at high temperature in a reverberatory furnace; the preparation of active magnesia from dolomite mainly includes semi-baked dolomite method and bischofite dolomite method.

11. Magnesium hydroxide

In view of the low product purity, complex process, and difficulty in industrialization in the traditional process for preparing Mg(OH)2, Chang Jiang et al. used dolomite as the raw material and used the brine precipitation method to prepare flake Mg with a purity of greater than 98%. (OH) 2, can be used as an additive flame retardant.

12. Calcium carbonate

Cao Ling et al. used dolomite as a raw material to prepare ultra-fine calcium carbonate with an average particle size of 5 μm using a carbonization method. Tong Mengliang used dolomite as the raw material to prepare CaCO3 nanorods with an average diameter of about 150nm, an average length of 1μm, and an average aspect ratio of 6-8 by using the secondary carbonization method.

13. Magnesium-containing cement

Magnesium-containing cement blended with light-burned dolomite ore and magnesium chloride solution or magnesium sulfate solution. It has high cohesiveness and plasticity, short setting time, strong binding force with organic substances, hard and beautiful color after hardening, and is used for construction. The material has good heat insulation, sound insulation and wear resistance, and its hardness and elasticity are stronger than ordinary cement.

14. Building boards

Light-burned dolomite mixed with organic aggregates can be used to manufacture particleboard, wood chipboard, artificial marble, heat insulation materials and other products, which are widely used in the construction industry.

15. Interior and exterior wall coatings

Dolomite is properly calcined and processed into dolomite, which has whiteness, strong adhesion, solidification and good fire resistance and heat insulation properties, and is suitable for interior and exterior wall coatings.

16. Glass ingredients

Dolomite is one of the main raw materials for glass production. It can provide calcium oxide and add soda-ash-silica system to act as a flux. It can also greatly reduce glass aging, improve the plasticity of colored glass, and increase glass strength.

17. Ceramic raw materials

Dolomite can not only be used as raw materials for traditional ceramic blanks and glazes, but also can be used to prepare new structural ceramics and functional ceramics, such as porous ceramic balls, inorganic ceramic membranes, andalusite-based ceramics.

18. Fertilizer and soil conditioner

In agriculture, dolomite is used to make calcium magnesium phosphate fertilizer and magnesium carbonate granular fertilizer. In addition, dolomite can also be used as a neutralizer for acid soils to compensate for calcium and magnesium elements and improve soil.

19. Titanium dioxide substitute filler

High-quality dolomite powder can be used as a substitute for expensive titanium dioxide fillers. When used as fillers such as adhesives, sealing plastics, paints, detergents, cosmetics, etc., it can improve the chromaticity, weathering resistance, mechanical strength, and shrinkage of products. And internal tension, reduce water absorption, oil absorption capacity and crack expansion.

20. Papermaking filler

Dolomite powder can be obtained by sorting, crushing and grinding the dolomite ore, which can be used as a filler in the papermaking industry after surface modification.

21. Paint filler

Dolomite powder can be used as a pigment filler in the coating industry to improve the weather resistance, oil absorption and scrub resistance of coatings. However, the surface and interface properties of inorganic dolomite powder and organic polymer matrix are very different. Surface modification treatment.

22. Plastics and thermoplastic elastomers

Jia Jianye et al. developed an active dolomite powder and applied it to plastics and thermoplastic elastomers. Active dolomite powder can replace light calcium in plastics and rubber products. In some aspects, the performance of active dolomite powder exceeds light calcium.

23. Fracturing proppant

When dolomite is used as a sintering aid to produce low-density and high-strength fracturing proppants, dolomite can promote the formation of liquid phase during the calcination process, thereby reducing the sintering temperature of the product and promoting the crystalline phase of rod-shaped mullite It develops, fills the pores, strengthens the bonding between the grains, and leads to the improvement of the mechanical properties of the material.

24. Catalyst and its carrier

Dolomite has a large specific surface area, not only can itself be used as a catalyst, but also a good catalyst carrier. For example, dolomite can be used as a catalyst to upgrade rapeseed oil and sunflower oil to prepare biodiesel; adding MoO3 and MgO to the Ni/dolomite catalyst can improve the activity of the catalyst and increase the yield of hydrogen produced by glycerol reforming.

25. Seal the pressure transmission medium

Compared with pyrophyllite, dolomite does not contain crystal water, it can maintain the stability of the phase under high temperature and high pressure, and there is no decomposition of carbonate substances, and the thermal expansion rate of dolomite is higher than that of pyrophyllite. It can make up for the pressure drop in the synthesis cavity due to the pyrophyllite phase change volume shrinkage, and is suitable as a sealing pressure transmission medium material.

26. Cementitious materials

Magnesium cementitious materials mainly use magnesite as raw materials, and the use of dolomite to replace 50% to 60% of magnesite to prepare magnesite cement materials can not only reduce costs, but also solve the problem of shortage of raw materials for magnesite in some areas.

27. Desulfurization outside the molten iron furnace

Gou strives to propose a new process for in-situ desulfurization of molten iron by using ferrosilicon to reduce dolomite to generate magnesium steam desulfurizer in situ. It is found that the maximum desulfurization rate of dolomite-based desulfurizer for molten iron is 95.21%, and the sulfur content in molten iron is the lowest. 0.021‰. This method can not only achieve ultra-deep desulfurization effect, but also reduce the cost of desulfurization agent. Therefore, dolomite-based desulfurization agent is expected to be popularized and applied in hot metal desulfurization outside the furnace.

28, adsorption of heavy metals

Dolomite has basic properties such as surface adsorption, filtration of pores, and ion exchange between mineral layers. It can be used as an environmental mineral material in the field of adsorbents, and has the advantages of low cost and no secondary pollution. Chen Miao et al. found that the removal rate of Cd2+ with an initial concentration of 3.2mg/L by dolomite was 95.42%, and the Cd2+ desorption rate of dolomite adsorption by different desorbents was low, indicating that Cd2+ can be firmly adsorbed by dolomite , It is not easy to re-release into the environment.

29. Treatment of phosphorus pollution

Mei Xiang et al. used a calcium-magnesium dissolution system with dolomite as a filler to study its process for recovering phosphorus from sludge anaerobic digestion solution, and pointed out that under the optimal conditions, the recovery rate of phosphorus in anaerobic digestion solution reached 97.35%, ammonia nitrogen The recovery rate was 12.97%.

30. Treat boron pollution

Wei Zunli and others used light-burned dolomite to adsorb boron in wastewater. Under optimal conditions, the removal rate of boron in wastewater by dolomite was greater than 90%, and the concentration of boron in wastewater after treatment reached the drinking water standard.

31. Treatment of printing and dyeing wastewater

Pan Yongyue et al. used a sulfur/dolomite (mass ratio 1:1) autotrophic denitrification process to treat the secondary effluent of an actual industrial printing and dyeing wastewater treatment plant. The method has a concentration of 7-20mg at a temperature of 25-30℃. The removal rate of TN/L is 43.8%, which has the advantages of low cost, no need for external carbon source, and low sludge output.

32. Adsorption of flue gas CO2

Fang Fan et al. found that dolomite can effectively absorb CO2 in flue gas, and its cycle stability is better than limestone.

33. Reverse osmosis desalination water

Li Dongyang et al. used the dissolved dolomite method to mineralize reverse osmosis desalinated water. The study found that NaHCO3 is more suitable than NaOH as a water quality parameter regulator for the post-treatment of dolomite desalinated water. The concentration of Ca2+ in the produced water reaches 82.75mg/L (with CaCO3), the concentration of Mg2+ reaches 19.25mg/L, and the water quality is stable and non-corrosive.

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