Mineral characteristics, economic use and related research of dolomite

The crystal of dolomite is a carbonate mineral of trigonal crystal. The chemical composition is CaMg(CO3) 2. Iron, manganese and other similar qualities (replace magnesium) are common. When the number of iron or manganese atoms exceeds magnesium, it is called the iron dolomite or the manganese dolomite. The trigonal crystal system, the crystal is the homing body, the crystal surface is often curved into a saddle shape, the cluster twin crystals are common. Collections are usually granular. The pure is white; Iron is grey in color; The weathering is brown. The glass sheen. It is the main mineral that forms dolomite. The dolomite of Marine sedimentary formation is often interlayered with the siderite and limestone strata. In the sediment of the lake, dolomite and gypsum, hard gypsum, stone salt, potassium salt and other symbiosis.

1 basic introduction

pinyin

Baiyun shi

English names

dolomite

The name of the mineral

dolomite

profile

The dolomite is carbonate mineral, with iron dolomite and manganese dolomite. Its crystal structure is like calcite, often with rhomboid. The cold and dilute hydrochloric acid will gradually bubble out. Some dolomite glow orange in the cathode ray. Dolomite is the main mineral composition of dolomite and dolomite limestone. Dolomite can be used in building materials, ceramics, glass and refractory materials, chemical industry and agriculture, environmental protection, energy conservation and other fields. It is mainly used as the melting agent of alkaline refractory material and blast furnace. Production of calcium magnesium phosphate and magnesium sulfate; And the production of glass and ceramic ingredients.

Quality dolomite series products: dolomite ore, dolomite sand 6-10 orders, 10-20, 20 to 40, 40-80 mesh, 80-120 mesh, 10 mesh by dolomite fines, ultrafine dolomite powder, 140 mesh, 325 mesh, 600 mesh, 1000 mesh, 1600 mesh.

Chemical composition

CaMg (CO3) 2; It can contain Fe, Mn, Pb, Zn, etc. Crystalline state: crystalline mass or crystalline mass.

Theoretical chemistry

CaO 30.4% [1]

MgO style 21.7% [1]

CO_247. 9% [1]

Ignition loss

44.5 47.0 [1]

Crystal system

Trigonal crystal system.

Crystal habit

The rhombohedron is often lumped.

Common color

Colorless, white, yellow or brown.

luster

The glass luster to the pearly luster.

cleavage

The dolomite has three sets of completely cleavage.

Mohs hardness

3 ~ 4.

The density of

2.86 g/cm3 ~ 3.20 g/cm3.

Optical characteristics

The dolomite is an axis crystal and negative light. It is often a heterogeneous aggregate.

pleochroism

It is not weak, it is not.

The refractive index

1.505 ~ 1.743.

birefringence

0.179 ~ 0.184, the collection cannot be measured.

Ultraviolet fluorescence

Orange, blue, green, green and white.

Absorption spectrum

No features.

Zoom in check

So three groups are completely cleavable. Special properties

The cold and dilute hydrochloric acid bubbles.

Optimization of processing

The unknown.

Stone range

Shandong yantai laizhou area, liaoning province.

3 mineral characteristics

Dolomite is mainly used to commemorate the French chemist DOLOMIEU(1750~ 1843). Dolomite is a trigonal crystal system. The chemical composition is CaMg(CO3) 2, mainly composed of calcium carbonate and magnesium carbonate (the ratio of CaCO3 to MgCO3 is roughly 1:1), with the complete cleavage and the crystal of the diamond surface. The color is white, grey, meat color, colorless, green, brown, black, dark pink, etc., transparent to translucent, with glass luster, hardness 3.5-4, proportion of 2.85-2.9. Remember when college was out in the wild, it was always unclear on the beach how to distinguish between dolomite and marble. If you have a can of cold hydrochloric acid next to it you can do it. The massive dolomite meets the cold dilute hydrochloric acid not easy to bubble, while the marble will emit many small bubbles immediately.

4 origin and origin

The causes of

According to mineral bureau of Taiwan (1996) mentioned in Taiwan's main mineral and rock, dolomite in crystalline limestone and other metamorphic rocks that are rich in magnesium, part from hydrothermal veins and carbonate rock in the cavity, occasionally as cement of all kinds of sedimentary rocks, as one of the most common in the carbonate rock forming minerals. The formation of the calcareous limestone of the Taiwan dolomite in the form of calcareous limestone is mainly deposited in the crystalline limestone belt at the lower part of the first tertiary period, which is a convex mirror, lamellar or irregular ore deposit.

Producing area

Dolomite is mainly produced in taiping water in yilan county, east of Taiwan, Hualien county, qingchang mountain, peace, benevolence, wanrong and papaya mountain. Other areas of the world of dolomite are the south of tirol, Switzerland, the south of tirol, the finches of piont in Italy, and guanahua in northern England and Mexico. The United States is produced in the joplin region of Missouri, forming a lump in the sedimentary rock or a pink saddle crystal in a rock fracture.

5 economic use

Conversion of dolomite can be used in steelmaking furnace refractory lining, slagging agent, flux cement raw material, glass, ceramic industry, fertilizer, construction and decorative stone, paint, pesticides and medicine and other purposes. It can be used in building materials, ceramics, glass and refractory materials, chemical industry and agriculture, environmental protection, energy saving and other fields.

6 characteristics study

The mineral reports on dolomite can be detailed in the Taiwan provincial minerals bureau's survey report of the baiyunshi marble mine survey in eastern Taiwan. Liu xinfu (1980) studied "the latent property of dolomite in the eastern part of Taiwan" in the postgraduate thesis of the national institute for mining and materials science. Liang jiquan (1980) studied the design of the underground mining of baiyun stone mine in qingchang county, Hualien county, and studied the master thesis of the institute of metallurgical and materials science of national successful university. National Taiwan university associate professor of geological sciences Deng Maohua study in the master thesis, institute of geology, national Taiwan university to taroko area in eastern Taiwan peace marble stable carbon isotope and mineral chemistry, mentioned analysis calcite marble carbon and oxygen isotopes, and by using dolomite and calcite specimens of symbiosis, analysis of dolomite and calcite isotope values, respectively, to infer the equilibrium conditions.

7 differences and protection

The main component of dolomite is calcium carbonate, MOH hardness value (MOH) between 3.5 and 4.

Dolomite is mainly composed of calcium carbonate and magnesium carbonate. The stone is very close to limestone in appearance, and in fact, it is often found in areas where limestone deposits are found. Most dolomite deposits contain a certain percentage of limestone. The important basis for distinguishing dolomite is not less than 50% of the mineral content of dolomite in the rock. In addition, dolomite is porous stone. Because the chemical composition of dolomite is not sensitive to acid, dolomite has better weather resistance.

Generally speaking, people usually use the method of hardness test and acid test to distinguish limestone from dolomite.

MOH is a simple mechanical test that USES another known hardness of metal to scrape the stone. The hardness of the dolomite is between three and four. The acid test rule is to apply the diluted hydrochloric acid to the surface of the stone. The limestone reaction is strong, while the dolomite reaction is not obvious, and the surface will form a powder. If the above test results are not obvious, laboratory analysis will be required. If you can know the source of the stone, the mineral types and ingredients will be clear.

Generally speaking, marble, limestone and dolomite can be used alternately as building materials. But even in the same category of stone, its physical properties are different. Before deciding which kind of stone is most suitable for use, the absorption, density and structural integrity of the stone should be taken into account. Can learn from other buildings stone use situation. For example, the outer wall of a 100-year-old building can be used as a reference to the outer wall project.

The absorption of limestone is stronger. In view of this characteristic, it is important to take the littering and scribble on the ground and other areas of limestone to take into account the future pollution. High density and small absorbent stones are used in areas vulnerable to environmental damage and stress.

Historically, dolomite has been used as a facade, weathered or eroded more than marble or limestone. Because of its low calcite content, the air pollution (mainly acid) is strong.

In general, marble, dolomite and limestone belong to materials with softer material. Therefore, in the process of construction and in the future use, it is easy to be exposed to the external pollution, exposed to the weak vulnerability of the poor, such as vulnerable to rain, dirt and other pollution. Compared with granite, these three kinds of stone are more permeable and more vulnerable to pollution. The best way to solve this problem is to protect it.

International stone dedicated permeability is widely used in the protective agent, its protective principle is protective agent penetrated into the interior of the natural stone material, deposit on the internal between the small particles of stone wool stoma, or attach to the individual mineral stone material surface molecules, in order to prevent water, oil and dirt into stone. Osmotic agents can be waterborne and solvent, and usually contain silicon, silicon, methyl silicate or other similar silicon compounds. The permeable protective agent can be divided into two categories: waterproofing and oil-proof. Waterproofing is mainly used to block the chemicals of water and water, such as fruit juice drinks, coffee, tea and soda. And oil-resistant permeable protective agents are used to prevent water and oil - based liquids from seeping into stone, such as cooking oil, grease and other oils. Oil-proof permeable protective agent has waterproof function at the same time, but waterproof product may not prevent oil pollution.

One of the factors that should be considered when using penetrant protection agent is the suitable choice of stone material and its laying position. According to the different characteristics of marble, limestone and dolomite, we should adopt different treatment methods according to the situation. For example, daily use of the kitchen marble floor, the choice of protective agent must have the anti-oil characteristics. For a busy hotel lobby on the ground, passers-by will leave many footprints, friction of the ground easily, at this time in order to protect the surface gloss, in addition to need to use osmotic protective agent, when necessary, still need to coating a layer of surface protective agent, even polished products for the polishing of the ground.

Another factor to consider is maintenance. If the dolomite or marble floor is swabbed daily, the likelihood of corrosion by acidic chemicals is greater. If the maintenance of the ground is neglected, the dirt will be blocked in the pores of the stone. If the stone itself has a high brightness, the gloss may be worn. In this way, no matter how good the protective effect of the stone surface, the surface will become dirty and dark. For example, the busy floors of the hotel lobby regularly dust and scrub daily, perhaps with a surface protectant that can be cleared away. But if change to the living room in the home, do not need to wash with cleaning agent completely every day, use waterproof and better permeative protection agent is ok.

Finally is important to emphasize that any kind of osmotic protective agent can forming a protective layer in the surface of stone material, so the permeability best stone protective agent protective again surface protection treatment, namely the need to use surface protective agent, this stone can only be truly is "double protection". Because any a kind of stone material excellent curing way is not to need to wax, wax layer does not breathe freely, and easy sticky, easy to make stone material surface color yellow, while the use of gas permeability and contains no wax type material on the surface of protective agent, can lead to further stone and protective layer of protection, and keep the stone natural bright color, really works.

Before choosing stone, its natural bright surface is also a factor that cannot be ignored. However, make sure that the physical properties of the stone are the most valuable. Only if the whole characteristic of stone material is considerate, the stone that you choose can maximize their adornment practicality and beautiful sex.

8 common products

Dolomite brick is made from calcined dolomite sand made of refractory products. It usually contains more than 40 percent of calcium oxide, more than 35 percent of magnesium oxide (MgO), and a small amount of silica (SiO2), aluminum oxide (Al2O3), iron oxide (Fe2O3) and other impurities. The CaO/MgO ratio of natural dolomite is larger than fluctuation. If the CaO/MgO ratio in brick is less than 1.39, it is called magnesium dolomite brick. White marble brick according to production process can be divided into: tar (asphalt) combine not to make brick, light burn oil immersed brick and burn oil to immerse brick. Dolomite brick contains free CaO, which is easy to hydrate and disintegrate in air, not suitable for long-term storage.

The raw material dolomite is the compound salt of calcium carbonate and magnesium carbonate, and the molecular formula is CaCO3· MgCO3, and the six-square crystal system, with the proportion of 2.80 ~ 2.99, mohs hardness of 3.5 ~ 4.5, the theoretical composition is CaO30.41 %, MgO21.87 %, CO247.72 %, CaO/MgO ratio of 1.39. China dolomite has abundant resources and excellent quality. Its composition is shown in table 1. Since the 21st century, we have used natural dolomite sand made from natural dolomitic sand, and the synthetic magnesia dolomite sand made from seawater and lime-milk has been used to make high quality magnesia dolomite brick.

China converter furnace lining mainly USES the tar combination of dolomite brick and tar combination of magnesium dolomite brick, some factories in vulnerable parts of the use of light oil immersion and oil-immersed magnesium dolomite brick. Countries such as Western Europe and Japan mainly use tar in combination with heat-treated and oil-immersed dolomite brick and magnesia dolomite brick. In addition, it is also used as lining for some furnace exterior refining furnace.

9 related research editor dolomite rock often symbiosis with oil and gas reservoirs, not only more close relationship with salt or metal ore deposits, and the formation of dolomite are still controversial, the focus for magnesium 2 + the source of the problems in the process of dolomitization. The dolomitization is often closely related to the deep activities of the basin, and is generally controlled by the deep hydrothermal activity. In the more developed basin of dolomitization, there is a middle crust low - high conductivity. According to the average temperature data of fluid inclusion body, the environment temperature of dolomite formation is higher than that of calcite and is usually much higher than normal formation temperature. Comprehensive research thinks, basin, deep in the earth's crust low-velocity - high conductivity layer is serpentinization peridotite, in the process of serpentinization release large amounts of magnesium 2 +, containing magnesium 2 + hydrothermal rise to basin with CaCO3 strong magnesium in carbonate metasomatism, dolomite formed; With halogen in the hydrothermal F, Cl, Br and alkali metal K, Na, Li and salt precipitation, hydrothermal in also including CO, CO2, H2, etc., they can occur in the serpentinization of peridotite fee - tropsch, synthetic hydrocarbon; In the process of serpentinization, the iron group metals such as Ni, Cr, Co and V are good catalysts.