First, the nature and use of tungsten
Belonging tungsten refractory metal, having a melting point of up to 3410 ± 20 ℃, the highest melting point metal, and having a vapor pressure high-temperature strength and hardness remain very low at a high temperature 2000 ~ 2500 ℃. Tungsten density 19.3 g / cm 3, 2.5 times that of steel, and gold is quite. Tungsten has good electrical conductivity, small expansion coefficient, high hardness, high modulus of elasticity and good ductility. Tungsten has strong corrosion resistance and does not work with any concentration of acid and alkali at room temperature; at 380~400 °C, tungsten trioxide begins to be reduced by hydrogen; above 630 °C, hydrogen can reduce tungsten dioxide to metal. Tungsten powder. Tungsten reacts with carbon and some carbon-containing gases at high temperatures to form hard, wear-resistant, refractory tungsten carbide with important industrial value.
Tungsten carbide-based hard alloys are used as cutting tools, die-cutting tools, drilling tools, rolls, armor-piercing warheads and heat-resistant wear parts; cast tungsten carbide for surfacing and coating of wear parts; tungsten carbide grain manufacturing No tooth saw blade. The consumption of tungsten in the form of tungsten carbide accounts for more than half of the total consumption of tungsten.
Tungsten is an important alloying element of steel, which increases the strength, hardness and wear resistance of steel. The main tungsten steels are high-speed tool steel, hot work die steel, series tools, die steel, ordnance steel, turbine steel, magnetic steel and so on. Application of a small amount of tungsten steel, accounting for about 20 to 30% of total consumption of tungsten.
Special alloys with tungsten as the main component are: refractory alloys for gas turbine blades, rocket nozzles, missiles, nuclear reactor components, etc.; high specific gravity alloys for heavy armor piercing warheads, navigation gyroscope rotors, flat street weights and automatic watches brakes; tungsten-nickel alloy, copper or the like is used as the X- and γ- rays shield, radiation material and other containers; tungsten copper, tungsten, silver alloy is a high-frequency electrical contact material; tungsten-rhenium alloy thermocouple measurable Temperatures range from room temperature to 2835 °C.
Metal tungsten materials, including wires, rods, strips, tubes and sheets, are important electrical light source materials, electronic components and high temperature materials for various lighting fixtures, tubes, X-ray tubes, non-consumable electrodes, Metal spraying and thermal components. Tungsten compounds can be used as the catalyst petrochemical industry, textiles, plastics industry flame retardants, mordant, pigments, dyes, fluorescent materials, decorative paints, solid lubricants and the like.
In short, tungsten is used in industries such as steel, machinery, mining, petroleum, rocket, aerospace, electronics, nuclear power, military and light industry in the form of alloying elements, tungsten carbide, metal materials or compounds. It is not a part of the national economy and cutting-edge technology. Missing important materials.
Second, the tungsten mineral nature of tungsten minerals have been found to have 20 kinds of industrial value which is wolframite (wolframite) and scheelite (scheelite) two kinds. Wolframite ore include tungsten (FeWO 4), wolframite ore (MnWO 4) and wolframite [(FeMn) WO 4], is a tungsten acid salts of iron and manganese continuous interstitial solid solution is a mixture of the same image, In fact, it rarely appears in a pure state. The tungsten-iron ore is a rich iron-tungsten mineral, the tungsten-manganese ore is a manganese-rich tungsten mineral, and the tungsten-manganese ore is a mixture of pure tungsten iron and tungsten manganese ore in a range of 20 to 80%. FeWO 4 : MnWO 4 ≤ 20: 80 is a tungsten manganese ore, and the ratio ≥ 80: 20 is tungsten iron ore.
The scheelite (CaWO 4 ) is a calcium tungstate with a tetragonal crystal. The molybdenum may replace the tungsten in the scheelite to form a similar calcium molybdate (CaMoO 4 ) ore. The scheelite emits a distinct blue-white fluorescence under the induction of ultraviolet radiation. When molybdenum is present in the mineral, it changes the color of the fluorescent light. As the content of molybdenum increases, it gradually changes from blue to beige, yellowish or orange. Table 1 shows the physical and chemical properties of the wolframite and scheelite.
nature | Black tungsten ore (wolframite) | Scheelite (scheelite) | ||
Tungsten iron ore (Ferberite) | Tungsten manganese ore (Wolframite) | Tungsten manganese ore (hubnerite) | ||
Chemical formula Contains WO 3 % Mn% Fe% Crystal structure Cleavage Density, g/cm 3 colour toughness luster Fracture Hardness (Mohs) magnetic Streak transparency Occurrence | FeWO 4 76.3 0 to 3.6 18.5~14.7 Monoclinic system Complete cleavage in one direction 7.5 black Extremely brittle Semi-metallic to metallic luster Uneven 5 Micro to weak magnetic Dark brown Opaque to translucent Crystallized bulk crystal | (FeMn)WO 4 76.5 3.6~14.5 14.7~3.7 Monoclinic system Complete cleavage in one direction 7.1 to 7.5 Dark gray to black Extremely brittle Semi-metallic to metallic luster Uneven 5 to 5.5 Micromagnetic Dark brown opaque Irregular block, plate crystal, radial aggregate | MnWO 4 76.6 14.5~18.1 3.7~0 Monoclinic system Complete cleavage in one direction 7.2 to 7.3 Reddish brown to black Extremely brittle Semi-metallic to metallic luster Uneven 5 Slight magnetic Brown red to green yellow Opaque to translucent Radial of thin plate crystal Aggregate | CaWO 4 80.6 - - Orthogonal system Good in four directions 5.4~6.1 Light yellow, brown, white Extremely brittle Glass to resin gloss Uneven 4.5~5 Non-magnetic white Transparent to translucent Generally square crystal |
Third, tungsten deposits, ore types
The formation of tungsten deposits is related to magma activity or metamorphism. Magmatic hydrothermal fluid, metamorphic hydrothermal fluid, sedimentation and reconstitution are the main mineralization effects. According to the genesis and occurrence of the deposit, combined with the mining and mineral processing technical conditions, the main tungsten deposits can be divided into four industrial types: quartz vein type tungsten deposit, skarn type scheelite deposit, fine vein disseminated tungsten deposit, and layer control. And layered tungsten deposits (Table 2).
The skarn-type scheelite deposit is produced in or near the contact zone of granite intrusions and calcareous rocks. According to the combination characteristics of useful minerals and industrial utilization, it can be divided into two types of mineralization: one is sulfide ore and scheelite skarn type, and its main features are sulfide ore such as chalcopyrite, pyrite, and square. The content of lead ore, sphalerite and chalcopyrite is high, and the content of lead-zinc ore is high. It can be used as an independent ore deposit and has a high silver content. It is an important target for comprehensive utilization, so it is both a scheelite deposit and a Polymetallic sulphide deposits; the other type is scheelite skarn, the sulphide ore content is relatively less than the former, the mineral composition is relatively simple, the main industrial mineral is scheelite, and the sulphide ore is only used as a by-product comprehensive recovery. The skarn-type scheelite deposits are mostly in foreign countries, accounting for more than half of the foreign tungsten reserves.
Fine vein-disseminated tungsten deposits in which tungsten minerals are produced in fine veins and are produced on the tops and edges of granite, shale or porphyry bodies. The ore bodies are massive or layered, lenticular, and few It is distributed in a strip shape. The deposits are large in scale, from large to medium to large. The main metal minerals are hematite, scheelite, cassiterite, beryl, molybdenite, stibnite, chalcopyrite and strontium and barium minerals. The ore grade is generally moderate to poor.
For layered and layered tungsten deposits, the ore body is controlled by a certain stratigraphic horizon and lithology. The occurrence is basically the same as that of the strata. The ore-bearing layer consists of one layer to several layers. The general range is wider, but the scale of industrial ore bodies is sizes, such as Western main gold metallic minerals are scheelite, stibnite, natural gold, purple calcium occurs in sericite slate layer. Another example is the Austrian Mittel Silt stellite deposit in the volcanic sedimentary metamorphic rocks. [next]
The formation of this type of deposit in porphyry-type tungsten deposits is mainly related to the shallow-super-shallow intrusion of the weakly acidic calcium-alkali series in the late volcanic-subvolcanic action. The porphyries associated with tungsten mineralization are mainly granodiorite porphyry, feldspar porphyry, granite porphyry and quartz porphyry. Mineralization is mainly distributed in the rock mass, and some are produced in the contact zone between the porphyry body and the surrounding rock, and some are produced in the surrounding rock. Mineralization is characterized by fine veins, low grade, large scale, often associated with molybdenum ore, shallow ore body output, and surrounding rock alteration has a zoning phenomenon. The mineralization is in the form of disseminated, reticular and fine veins. The ore body often appears as layered, lenticular, and irregular, with no obvious boundary with surrounding rock. The ore minerals mainly include scheelite, wolframite and molybdenite, followed by chalcopyrite, sphalerite, stibnite and pyrite. The representative deposits are the Lianhuashan tungsten deposit in Guangdong and the Yangcangling tungsten deposit in Jiangxi.
Some large deposits often include several types, such as the Shizhuyuan tungsten deposit, including skarn type, fine vein disseminated granite type, Yunying rock network type and other composite tungsten-tin-molybdenum polymetallic deposits. The Yaogangxian tungsten deposit is composed of a quartz vein type black tungsten deposit and a skarn type scheelite deposit. The Luokeng tungsten deposit includes a quartz vein type and a fine vein network-disseminated type deposit.
Tungsten ore is generally classified into black tungsten ore (often containing scheelite) and scheelite ore according to the class of tungsten minerals. According to the mineral crystal nature, it can be divided into coarse grain inlay, fine grain inlay, uniform distribution and uneven distribution. These classifications are closely related to the mineral processing technology of tungsten.
IV. Production and Consumption of Tungsten in the World Thirty-four countries and regions in the world produce tungsten, mainly in China, the Soviet Union, Canada, South Korea, Bolivia, Australia, the United States and Portugal. China is the world's most abundant tungsten resource, with more than half of the world's reserves. It is mainly concentrated in Hunan, Jiangxi, Guangdong, and Fujian provinces in the eastern fold of the Nanzhao Mountain. The reserves, production, and export volume all rank first in the world. . The major consumers and regions of tungsten are the United States, the Soviet Union, Western Europe, Eastern Europe and Japan.
According to the report of the 18th session of the Tungsten Committee of the Commodity Committee of the United Nations Conference on Trade and Development in November 1986, the production and consumption of tungsten concentrates in the world in recent years are shown in Tables 3 and 4, respectively.
Year, year | 1981 | 1982 | 1983 | 1984 | 1985 | 1986 |
world | 48701 | 45932 | 39810 | 44035 | 43528 | 39095 |
Developed market economy countries Australia Austria Canada France Japan Portugal Spain Sweden United States other | 13961 3333 1450 2052 591 668 1396 441 365 3605 60 | 12062 2588 1406 2938 726 635 1343 556 349 1521 7 | 8092 2061 (1400) 328 793 475 1164 521 365 980 5 | 11715 1733 1400 3715 742 477 1486 569 365 1203 5 | 11403 1970 1565 3005 735 526 1737 462 402 996 5 | (8817) (1750) (1400) (1417) (700) (600) (1200) (450) (400) (900) (—) |
Developing country Bolivia Brazil Myanmar Mexico Peru South Korea Rwanda Thailand other | 10110 2778 1248 825 158 521 2742 281 1210 347 | 7583 2543 1365 844 78 654 2539 322 856 391 | 8538 2490 1026 930 147 703 2101 231 563 347 | 9170 1893 1101 1096 145 786 2702 291 742 414 | 8975 1643 1297 (1100) 282 798 2572 (300) 585 398 | 7328 (1100) (800) (1100) (300) (784) (2200) (300) (464) (380) |
Asian socialist countries | (15700) | (15200) | (14000) | (14000) | (14000) | (13800) |
Eastern European socialist countries Soviet Union other | (8930) (8850) (80) | (9080) (9000) (80) | (9180) (9100) (80) | (9150) (9100) (50) | (9150) (9100) (50) | (9150) (9100) (50) |
Year, year | 1981 | 1982 | 1983 | 1984 | 1985 | 1986 |
world | 47095 | 40022 | 39770 | 46967 | 44457 | 42075 |
Developed market economy countries Austria France Federal Republic of Germany Japan Sweden United Kingdom United States other | 19371 1850 663 1348 2238 1432 879 9839 1122 | 12572 1304 653 1541 1826 994 660 4506 1088 | 13679 (1629) 520 2030 1977 774 560 5181 1008 | 20208 (2096) 815 2934 2302 765 610 8577 1109 | 17179 (2000) 806 2073 2616 820 (600) 6838 1424 | (15345) (2000) (850) (1600) (2200) (1220) (600) (5625) (1250) |
Developing country Brazil India South Korea other | 2897 480 459 1898 60 | 2698 454 454 1742 48 | 2468 450 (400) 1555 63 | 3115 538 (400) 2070 107 | 3605 1048 (400) 2048 109 | (3260) (860) (350) 1950 100 |
Eastern European socialist countries Poland Soviet Union other | (18467) 427 (15870) (2170) | (19152) 1312 (15870) (1970) | (18623) 1073 (15600) (1950) | (18664) 594 (16000) (2070) | (18673) 603 (16000) (2070) | (18670) (600) (16000) (2070) |
Asian socialist countries | (6360) | (5600) | (5000) | (5000) | (5000) | (4800) |
Tungsten smelting has different requirements for the quality of tungsten concentrate due to different smelting methods and different purpose products. For example, tungsten concentrates for smelting tungsten iron and alloy steel by fire method have strict requirements on the content of sulfur, phosphorus and heavy metal elements, because these harmful elements cannot be removed during the smelting process, so that the produced tungsten steel is hot and brittle. Or cold and brittle to reduce mechanical properties; and the content of molybdenum is not limited, because molybdenum is a beneficial element of steel; the white tungsten contained in the black tungsten concentrate is also not strictly separated. However, when black tungsten concentrate is used as a raw material for hydrometallurgy, it is first processed into intermediate products such as ammonium paratungstate and tungsten oxygen, and then made into cemented carbide and tungsten products. In order to improve the decomposition rate of tungsten concentrate, it is required to separate black tungsten and white tungsten,
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