Tungsten / Wolfram
Description: Tungsten / Wolfram is a high melting point rare metal or refractory rare metal in the field of metallurgy and metal materials. Tungsten and its alloys are one of the most important functional materials in modern industry, national defense and high-tech applications. They are widely used in aerospace, atomic energy, shipbuilding, automobile industry, electrical industry, electronic industry, chemical industry and many other fields. Tungsten containing super alloy are mainly used in gas turbine, rocket, missile and nuclear reactor components, and high specific gravity tungsten based alloys are used in armor piercing warhead of anti-tank and anti-submarine.
Solid Density: 19.25 G / CM3
Liquid Density: 17.6 G / CM3
Specific Heat: 130J / KG. K (300K)
Thermal Conductivity: 160W / M.K (300K)
Melting Point: 3410 ± 20℃
Boiling Point: 5555 ℃ ± 20℃
Tungsten Atomic Weight: 183.85
Sources: Tungsten occurs in wolframite, (Fe, Mn)WO4, scheelite, CaWO4, ferberite, FeWO4, and huebnerite, MnWO4.
Distribution: China, Canada, Russia, Bolivia, United States, North Korea, Mongolia and other countries.
History: Discovered by Juan José and Fausto Elhuyar(Spanish chemists and brothers) in 1783.
Tungsten / Wolfram Plant
Wolframite group and scheelite group are the most valuable tungsten minerals. Between them, scheelite raw ore grade is low, ore mining dilution rate is high, mineral composition is complex and the separation is difficult.
In production practice, the plant process of tungsten ore mainly includes five stages: roughing, grinding, gravity separation, concentration and fine mud treatment.
1.Roughing
Manual separation is a simple preconcentration method to separate tungsten / wolfram according to the density, and it is also a necessary operation in the process. The sand sample is placed in the gold pan filled with water, repeatedly vibrated, stirred and washed. The heavy minerals are left at the bottom of the pan, and the light minerals are floated out with water, so as to separate the light and heavy minerals.
At this stage, rod mills are mostly used in tungsten / wolfram grinding equipment, which can avoid over grinding and ensure the uniform particle size of grinding products to meet the particle size requirements of gravity separation.
2.Grinding
Due to the brittleness and heavy ratio of tungsten, it is easy to over grind and over crush in the grinding process, that resulting in too much secondary mud. So the grinding is particularly important in tungsten plant. One stage grinding, one stage rod grinding + middling grinding and two stage grinding are commonly used in the grinding of wolframite.
3.Gravity Separation
The process of the gravity separation of tungsten: The raw ore is grinding, and goes into the jigging, then concentrating, final mud treatment to get the coarse concentrate and discard a large number of tailings. The coarse and medium size of jigging tailings are grinded by rod mill, and the grinding products are returned to the vibrating screen to form a closed cycle. Most of the Shakers adopt twice separation, coarse and medium size shakers return middlings to circulation circuit, and slimes are treated separately.
4.Concentration
After gravity separation of tungsten ore, its coarse concentrate often contains high value non-ferrous metals such as tin, molybdenum, bismuth, copper and zinc, or rare metals such as tantalum and niobium. Therefore, it is necessary to clean the coarse concentrate.
Magnetic Separation: It is a method of using magnetic force to remove magnetic metal impurities in oil. The application of magnetic separation is to use the magnetic difference of various ores or materials to carry out separation process under the action of magnetic force and other forces.
Flotation: It is one of the most widely used mineral processing methods. It is a method to separate useful minerals from ore according to the different physical and chemical properties of mineral particle surface. Flotation is suitable for fine and fine materials, and for fine ore particles less than 10um which are difficult to be recovered by other mineral processing methods. The United carbide company has developed the “lime method” for Scheelite Flotation, and the shear flocculation flotation has also been used in Scheelite Flotation in some factories.
5.Fine Slime Treatment
In the process of fine slime treatment of tungsten ore, the desulfurization operation is carried out firstly, and then according the properties of fine slime materials to select the method(gravity separation, flotation, magnetic separation, electric separation and other combined separation methods) and comprehensive utilize of associated metal minerals.
Tungsten / Wolfram Plant Flow
Main Equipments of Tungsten / Wolfram Plant
Jig Separator: Important Gravity Separation Machine in Tungsten Plant
Jig separation is one of the important gravity separation equipments of tungsten plant. The jigging process of wolfram ore is mainly carried out by three-stage jigging, that is, all qualified ore sieves are divided into three levels: coarse, medium and fine to enter the jigging operation. The coarse-grained jigging particle size is generally 8-10 mm, and the particle size range of medium-sized jig is 1.5-5.mm. The recovery of coarse and medium sized jigging tailings can reach 65% – 75%. The fine-grained jigging tailings are separated by hydraulic classification and then put into the shaker for separation, and the tailings are lost during the operation of the shaking table.
Shaker Table: Widely Used in Wolfram Plant
The shaking table is widely used in the separation of medium and fine-grained tungsten ores. It can be used as concentrate equipment in large-scale tungsten concentrators and as coarse and concentrate equipment in small-scale concentrators. The suitable particle size is 0.037-2mm. In order to ensure the effect of gravity separation of tungsten ore, the narrower the range of particle size, the better.The high frequency vibrating screen or hydraulic classification box can be used for pre classification before the shaking table feeding.
Two times’ operations are usually carried out for tungsten ore shaker separation. The middlings in coarse and medium size Shakers return to the circulating circuit, and the slimes are treated separately.
Magnetic Separator: Best Choice for Tungsten Plant
The rough concentrate operation of tungsten is generally intermittent, and it needs to be dried before concentration. Single disc or multi disc dry magnetic separators are used for magnetic separation of coarse-grained tungsten ore. This kind of magnetic separators are lower feeding machines with strong selectivity, and the treatment particle size is 0.074-3mm. After magnetic separation, relatively pure tungsten concentrate can be obtained, but the tailings contain high tungsten content, which requires multiple scavenging. In addition, the feeding material of disc magnetic separator needs to be graded and selected. The narrower the particle size is, the better the magnetic separation effect is.