Brief introduction of manganese and manganese ore


Manganese is a kind of grey metal which has hard and brittle nature. Its density is 7.4, the melting point is 1244 degrees celsius and the boiling point is 2097 degrees celsius. Manganese has four kinds of allotropes and their crystal structure will be changed according to different temperature. α-MN is stable in below the temperature of 710 degrees Celsius and appears to be body-centered cubic lattice; It will transform to β-MN in more than 710 degrees Celsius and appears to be a little complicated cubic lattice; when the temperature is up to 1070 degrees celsius, it will transform to γ-MN which is face-centered cubic lattice; it will transform to δ-MN in 1140 degrees celsius and again appears to be the body-centered cubic lattice. Metal manganese can burn like the iron in the wet oxygen or in the wet air. Manganese can be dissolved in the dilute acid where it can form divalent salts and generate hydrogen; when heated, manganese can react with fluorine, chlorine, bromine and other gases.

The known manganese-bearing minerals in the nature is about more than 150 kinds which are separately as the oxides, carbonates, silicates, sulphides, boric acid salts, tungslates, phosphates and so on. However, the minerals containing high content of manganese are not much and the common manganese minerals are as follows:

a. Pyrolusite, which belongs to the tetragonal system, its crystal appears to be slender prismatic or acicular and it is usually in massive and powder-like aggregate. Its mineral color and striation color are both black. Its gloss and hardness vary based on its crystallization thickness and shape. Usually the manganese with good crystal will be in semi-metallic luster and have high hardness; while the manganese with implicit crystalline block and powder form will have dim gloss and low hardness, of which the density is about 5. Pyrolusite is mainly formed by deposition, which is one of the main components of sedimentary manganese ore. In the oxidation zone part of manganese ore deposit, all native low state manganese ores can be oxidized to pyrolusite which is a very common mineral in the manganese ore and is an important raw mineral in smelting the manganese.

b. Psilomelane belongs to the monoclinic system. Its crystal is rare. It is generally appears to be stalactitic, kidney shape and botryoid aggregate, also in dense clumps and dendritic. Its mineral color and striation color are both black. It is in semi metallic luster, with the hardness of 4-6 and the density of 4.4-4.7. Psilomelane is mainly exogenous which can be found in the oxidizing zone of manganese ore deposit and in the sedimentary manganese deposit. It is also very common manganese mineral in manganese ore and is an important raw material in smelting the manganese.

c. Manganite, belongs to the monoclinic system, of which the crystal is in columnar shape and the cylinder has longitudinal grain on it. In some of geodes which contain manganese hydrothermal veins, it often yields in the form of vug. It mostly appears to be aphanitic block or oolith shape and stalactitic aggregate in the sedimentary manganese deposit. Its mineral color is black and the striation color is brown. It has semi metallic luster with the hardness of 3-4 and the density of 4.2-4.3. Manganite can be found both in some of the endogenous hydrothermal deposit and exogenous sedimentary manganese deposit, which is one of the raw materials in smelting the manganese.

d. Black manganese ore belongs to the tetragonal system and its crystal is in tetragonal-dipyramidal. It generally appears to be granular aggregate. It is in black and its striation is in brown-orange or reddish brown. It has semi metallic luster with the hardness of 5.5 and the density of 4.84. Black manganese ore is formed by endogenous process or metamorphyism, which can be found in some of the contact metasomatic deposits, hydrothermal deposits and sedimentary metamorphic deposits. It is symbiotic with braunite and is also one of the raw mineral materials in smelting the manganese.

e. Braunite belongs to the tetragonal system. Its crystal is in double cone shape and it is also yielded in granular and massive aggregate. It is in black while its striation is in brown-black. It has semi metallic luster, of which the hardness is 6 and the density is 4.7-5.0. Other nature of manganese is same with black manganese.

f. Rhodochrosite belongs to the trigonal system. Its crystal is in rhomb, which generally appears to be granular, massive or concretion forms. It is in rosiness and can be easily oxidized and transform into brown-black. It has vitreous luster and the hardness is 3.5-4.5 and the density is 3.6-3.7. The rhodochrosite formed by endogenous process can be mostly found in some of the hydrothermal deposits and contact metasomatic deposits; the rhodochrosite formed by exogenic process is largely distributed in the sedimentary manganese deposit. Rhodochrosite is an important raw mineral material in smelting the manganese.

g. Alabandite belongs to the isometric system. Its common simple forms are cube, octahedron, rhomboic dodecahedron and so on while its aggregates are granular or massive. Its color ranges from steel ash to iron black and will change to brown after the weathering. Its striation appears to be dark green. It has semi metallic luster, of which the hardness is 3.5-4 and the density is 3.9-4.1. Alabandite can be largely found in the sedimentary metamorphic manganese deposit, which is one of the raw mineral materials in smelting the manganese.

The smelting processes of metal manganese are electric furnace smelting, aluminothermic reduction method and electrolytic process. Manganese powder is mainly used as the deoxidizing agent and desulfurizing agent in the ironmaking and steelmaking process. It can also be used as the additives in producing high temperature alloy, stainless steel, non-ferrous alloy and low carbon high strength steel; most of the metal manganese powder are used in producing the aluminium-manganese alloy, stainless steel and stainless steel welding rod and so on. Besides, manganese dioxide is an important raw material in manufacturing the dry-cell batteries.

The distribution of china’s manganese ore resources is not balanced and most of its ore deposit scale is in medium and small size. Moreover, its ore quality is poor with lean ore in the majority. Its ore material composition is complex and the ore deposits are mostly in the types of deposition or sedimentary metamorphism, of which the mining condition is complicated. Currently china’s identified manganese ore zones are distributed in 21 provinces, municipalities and autonomous regions of the country in which the most important zones are Guangxi and Hunan provinces, Guizhou, Yunnan, Sichuang, Liaoning, Hubei and Shanxi provinces are followed by. In china, there are 8 areas that have the concentrated manganese ore reserves: a. the southwest of Guangxi province which includes Daxin, Jingxi, Tiandeng, Debao, Fusui and other counties. b. The sunni triangle of Hunan, Guizhou and Sichuan provinces which include Huayuan County in Hunan province, Songtao County in Guizhou province, Xiushan County in Sichuang province and other regions. c. Zunyi region in Guizhou province including Zunyi city and Zunyi County. d. Chaoyang region in Liaoning province. e. The southeast of Yunnan province including YanShan, Wenshan, Jianshui, Shiping, Mengzi, Kaiyuan, Gejiu and other counties (cities). f. Central Hunan including Ningxiang, Yiyang, Xiangtan, Xiangxiang, Shaoyang, Shaodong, Xinshao, Taojiang and Lianyuan counties (cities). g. In Daoxian region of Yongzhou city, Hunan province, the manganese ore is mainly distributed in Dongxiang bridge of Yongzhou city and Houjiang bridge of Daoxian. h. Ta-pa Shan in Hanzhong city, Shanxi province including Hanzhong city, Xixiang, Ziyang, Ningqiang counties in Shanxi province and Chengkou County in Sichuang province. The available manganese ore reserves of the above 8 areas occupy 82 percents of the total available reserves in China. They are also the important raw material sites for china’s manganese ore industry.