Which one has a lower production cost to produce magnesium metal from magnesite or dolomite as raw m

Theoretically, magnesite.

Only magnesium and dolomite can be produced by electrolysis.

Magnesium metal can be produced by the reduction method.

In the last century, European and American countries generally used the process of electrolytic magnesite to produce magnesium metal, but in the later period, especially at the beginning of this century, a large number of enterprises in China promoted the process of reducing magnesium metal by the Pijiang method to the end, and in many regions of China, only the Pijiang method was used to reduce dolomite to refine magnesium metal. From a cost point of view, the cost per ton of magnesium for reducing dolomite by Pijiang method can be controlled at 10,000 to 15,000, while the electrolytic treatment of magnesite will be at least 30% higher.

In the late 90s, after the closure of the largest magnesite electrolytic refining plant in North America, the main trend in the world was the reduction of dolomite to magnesium metal.

It should be pointed out that the current global magnesium consumption is about 80-1 million tons per year, and China's output has exceeded 1 million tons, so the control and research of refining costs are mainly in China. At present, more than 90% of China's magnesium metal production enterprises are using the Pijiang method of dolomite reduction, and only recently Qinghai Salt Lake Magnesium Industry is launching large-scale electrolysis, but their raw material is not magnesite, but their own by-product magnesium chloride.

1. Both of them are not suitable for the production of magnesium metal, because they cannot be produced by reduction method, but can only be produced by electrolysis, but the cost of electrolysis is high and there is no market.

2. From the perspective of composition, magnesite does not contain CA, and the production cost is relatively low.

Magnesite Magnesium carbonate.

Dolomite: Magnesium carbonate, calcium.

Both are used. It is related to the difficulty of raw materials. Generally speaking, the former is slightly lower.

Do you produce electrolytic magnesium or crystalline magnesium? The cost is not only related to the raw material, but also related to the production process.

I don't know if you said that the hole is missing magnesium metal or industrial magnesium powder. The main chemical component of magnesite is MGC3, which contains more than 80% magnesium, and can obtain higher purity magnesium oxide by direct calcination.

The process is simple. Dolomite.

The main chemical component is CAMGCO32, which contains about 30% magnesium, and nano-dolomite can be extracted by pressure carbonization Qingchi method, but the process is more complicated.

The chemical formula of dolomite is CAMG(CO3)2 is formed by the same image of MG and CA, the beneficiation method of magnesite is relatively simple, reverse flotation to remove silicate minerals, positive flotation to select MGC3, and then according to the index you want, light roasting and heavy roasting can be, dolomite is different, there are both calcium and MG in it, if you want to get MGO, in fact, there is one more step, inhibiting Ca ions can select MGC3

The method of making magnesium from dolomite is generally used in China, and the Pijiang method is generally used in China, using ferrosilicon as a reducing agent to reduce and calcine dolomite, and the crude magnesium is obtained in a vacuum furnace.

Magnesite is expensive to make magnesium and is generally made by electrolysis. First, magnesite is turned into magnesium oxide, and then electrolyzed to obtain coarse magnesium from hall dust.

Magnesium is found in magnesite MGC3, dolomite CAMG(CO3)2, and carnallite KCL·MGCL2·H2O. Industrially, magnesium metal is prepared by electrolytic molten magnesium oxide or reduced by ferrosilicon in an electric furnace, the former is called molten salt electrolysis, and the latter is called silicon thermal reduction method. Magnesium chloride can be extracted from seawater, which contains about 12 billion pounds of magnesium per cubic mile of seawater.

It is often used as a reducing agent to replace metals such as titanium, zirconium, uranium, and beryllium. It is mainly used in the manufacture of light metal alloys, ductile iron, dehydrogenation of desulfurization agents for scientific instruments and Grignard reagents, and can also be used to make pyrotechnics, flash powder, magnesium salts, etc. The structural characteristics are similar to aluminum, which has various uses as a light metal, and can be used as an alloying material for aircraft and missiles.

But magnesium is flammable at the ignition point of gasoline, which limits its application. Daily use: Gymnasts often apply magnesium powder to increase friction.

Medical uses: Magnesium deficiency and cramps. Sports Uses:

Inject a few hours before intense exercise or after intense exercise to compensate for the loss of magnesium. Magnesium metal reacts with most non-metals and acids; Under high pressure, magnesium hydride can be directly synthesized with hydrogen; Magnesium can react with halogenated hydrocarbons or halogenated aromatic hydrocarbons to synthesize Griard reagent, which is widely used in organic synthesis. Magnesium has a distinct tendency to produce coordination compounds.

Magnesium is an important material in the aviation industry, and magnesium alloy is used in the manufacture of aircraft, forest, engine parts, etc.; Magnesium is also used in the manufacture of photographic and optical instruments, among others; The non-structural applications of magnesium and its alloys are also wide; Magnesium is also used in the production of titanium, zirconium, beryllium, uranium and hafnium as a strong reducing agent.

For a long time, chemists regarded magnesium oxide bitter soils obtained from the roasting of magnesite containing magnesium carbonate as an inseparable substance. It is listed in Lavoisier's list of elements published in 1789. In 1808, after David succeeded in producing calcium, he used the same method to successfully produce magnesium metal.

Since then magnesium has been identified as an element and named magnesium, the element symbol is from the Greek city of Magnesia, because of the production of magnesium oxide near this city, known as magnesiaalba, that is, white magnesium oxide. However, the name magnesium is easily confused with the name manganum, and although some people have proposed to change it, it has been used.

mg[co3

Tripartite crystal system. no

ne-)none

Figure 3-21 Optical orientation of siderite magnesite.

Chemical composition between magnesite and siderite can form a complete homogeneous series, generally MGC3

Feco3 is contained

The molecule, containing 8%, is called iron magnesite (breunnerite), and some people divide the solid solution series in detail, from pure magnesite to pure siderite, with feco3

The increase of content includes varieties of iron magnesite, siderite, magnesite, magnesite, etc., and the mg in magnesite can be limited by Mn2+

Ca2+ is replaced, and a few are Ni2+

CO2+ instead.

Crystalline characteristics Trigonal crystal system, the crystal is rhombohedral, usually fine-grained aggregates, sometimes dense block, columnar, plate-like, earth-like, Chun's fibrous, radial, etc. {

Cleavage development with an angle of 72°30.

Phototic characteristics are white or colorless, while iron-containing varieties can be yellow or brown, colorless in thin sections, and colored varieties are mostly brown, and absorbent pappels can be seen

NO containing 5% COO has red or purple-red pleochroism. The flash protrusion is obvious, the interference color is high-grade white, the polysilicon double crystal is not visible, the one-axis crystal is negative, and the refractive index dispersion is strong.

Change magnesite can be produced by ultramafic rock-peridotite, serpentine by the action of carbonated water, often forming talc magnesite schist, according to the experiment when magnesite is heated to about 550, it becomes galvanite in about 1 hour.

Identification characteristics The difference with calcite and dolomite is that the refractive index of magnesite is larger, and there is no polycrystal. The difference with siderite, rhodochrosite is magnesite ne

are negative low protrusions, while the latter two are positive low protrusions (see Distinguishing features of calcite). In addition, due to the development of rhomboid cleavage of carbonate minerals, the crystal plane or cleavage plane will naturally lie flat when crushed, so the NE on this surface is measured by oil immersion method

Values are also one of the ways to distinguish the above minerals. The refractive index values of each mineral debris are shown in Table 3-7 (due to the fact that some minerals NO

The value is large, and it is not easy to select oil, so only NE is measured in practical application

Table 3-7 Refractive index of carbonate mineral debris.

Occurrence and other magnesite usually occurs as altered minerals in serpentine and peridotite, and is symbiotic with chlorite and talc as metamorphic minerals in metamorphic rocks. It can also be produced as a primary mineral in igneous rocks, such as as a primary mineral in spike magnesite bronze, which is symbiotic with bronze pyroxene and talc. In sedimentary rocks, magnesite can be found as a sedimentary mineral or as a product of recrystallization, occurring in dolomite and dolomite-shaped limestone or some evaporite.

Magnesite has also been found in meteorites. Magnesite is mainly used in the manufacture of refractory bricks and magnesium-containing cement, and the chemical industry makes magnesium sulfate and other magnesium-containing compounds, and can extract magnesium metal.