Tungsten is found in the minerals Wolframite (iron-manganese tungstate, FeWO4/MnWO4), Scheelite (calcium tungstate, (CaWO4), ferberite and hübnerite. These are mined and used to produce about 37,400 tons of tungsten concentrates per year in 2000. China produced over 75% of this total, with most of the remaining production coming from Austria, Bolivia, Portugal, and Russia.

Tungsten is extracted from its ores in several stages. The ore is eventually converted to tungsten(VI) oxide (WO3), which is heated with hydrogen or carbon to produce powdered tungsten. It can be used in that state or pressed into solid bars.

Tungsten can also be extracted by hydrogen reduction of WF6 (WF6 + 3H2 → W + 6HF) or pyrolytic decomposition (WF6 + energy → W + 3F2).

Because it retains its hardness at high temperatures and has a high melting point, elemental tungsten is used in many high-temperature applications, such as light bulb, cathode-ray tube, and vacuum tube filaments, heating elements, and rocket engine nozzles. Its high melting point also makes tungsten suitable for aerospace and high-temperature uses such as electrical, heating, and welding applications, notably in the gas tungsten arc welding process (also called TIG (tungsten/inert gas) welding).

Due to its conductive properties, as well as its relative chemical inertia, tungsten is also used in electrodes, and in the emitter tips in electron-beam instruments that use field emission guns, such as electron microscopes. In electronics, tungsten is used as an interconnect material in integrated circuits, between the silicon dioxide dielectric material and the transistors. It is used in metallic films, which replace the wiring used in conventional electronics with a coat of tungsten (or molybdenum) on silicon.

The electronic structure of tungsten makes it one of the main sources for X-ray targets, and also for shielding from high-energy radiations (such as in the radiopharmaceutical industry for shielding radioactive samples of FDG). Tungsten powder is used as a filler material in plastic composites, which are used as a nontoxic substitute for lead in bullets, shot, and radiation shields. Since this element's thermal expansion is similar to borosilicate glass, it is used for making glass-to-metal seals.

The hardness and density of tungsten are applied in obtaining heavy metal alloys. A good example is high speed steel, which may contain as much as 18% tungsten. Superalloys containing tungsten, such as Hastelloy and Stellite, are used in turbine blades and wear-resistant parts and coatings. Applications requiring its high density include heat sinks, weights, counterweights, ballast keels for yachts, tail ballast for commercial aircraft, and as ballast in race cars for NASCAR and Formula 1. It is an ideal material to use as a bucking bar for riveting, where the mass necessary for good results can be achieved in a compact bar. In armaments, tungsten, usually alloyed with nickel and iron or cobalt to form heavy alloys, is used in kinetic energy penetrators as an alternative to depleted uranium but may also be used in cannon shells, grenades and missiles to create supersonic shrapnel. High-density alloys of tungsten may be used in darts (to allow for a smaller diameter and thus tighter groupings) or for fishing lures (tungsten beads allow the fly to sink rapidly). Some types of strings for musical instruments are wound with tungsten wires. Its density, similar to that of gold, allows tungsten to be used in jewelry as an alternative to gold or platinum. Its hardness makes it ideal for rings that will resist scratching, are hypoallergenic, and will not need polishing, which is especially useful in designs with a brushed finish.

Tungsten compounds are used in catalysts, inorganic pigments (e.g. tungsten oxides), and as high-temperature lubricants (tungsten disulfide). Tungsten carbide (WC) is used to make wear-resistant abrasives and cutters and knives for drills, circular saws, milling and turning tools used by the metalworking, woodworking, mining, petroleum and construction industries and accounts for about 60% of current tungsten consumption. Tungsten oxides are used in ceramic glazes and calcium/magnesium tungstates are used widely in fluorescent lighting. Crystal tungstates are used as scintillation detectors in nuclear physics and nuclear medicine. Other salts that contain tungsten are used in the chemical and tanning industries.

Lately, tungsten is used for jewelry because of its longevity and high durability.

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Tungsten News & Tungsten Prices, WML Version: http://m.chinatungsten.com

At first, the comparison between fluorescent and tungsten may seem simple, but such a decision can impact the work environment, home environment, product quality, even financial situation. When comparing fluorescent and tungsten lighting, important factors to consider include location, spacing, safety and cost.

Instructions

1
Consider the location and purpose of the light in question. Is it a smaller room or a large, open area? Will people be reading and studying under the light or moving actively? If a work-based environment, is the location a photo studio or a place that works with details and colors? Does the light require a dimmer?

2
Consider the output and safety of the light. Fluorescent light bulbs emit 90 to 95 percent of their energy as light, while tungsten light bulbs emit 90 to 95 percent of their energy as heat. Will the lights be used in wide, open spaces? Will the lights be near flammable materials or papers? Are the lights recessed and potentially prone to overheating?

3
Consider cost and energy efficiency. Fluorescent lights will always be more energy efficient than tungsten, however, there may be a cost involved to make a fixture fluorescent-friendly. Additionally, take note of how long the light and location will be in use; the long-term operating cost of fluorescent lights is less than that of tungsten, but in the short term tungsten may be less expensive.

Tips & Warnings
If cost is a major factor, crunch some numbers to figure out which light is more financially feasible. For instance, if you are renting a small office for five years, using fluorescent lighting may be more cost effective. If you rent the same small office for one year, on the other hand, tungsten may work better. Remember to include the cost of any fixtures as well as modifications necessary to accommodate those fixtures.

If the decision comes down to the issue of safety, choose fluorescent. With a significantly lower operating temperature, fluorescent lights are far less likely to cause burns or fires if the fixture is knocked over as well as less likely to overheat when used in smaller, contained spaces.

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Tungsten News & Tungsten Prices, WML Version: http://m.chinatungsten.com

Tungsten ore low, must be integrated mineral-rich concentrate to a smelting raw material. According to the type of tungsten ore dressing into wolframite and scheelite mineral beneficiation two types. Present mining to wolframite quartz vein type, accounting for the amount of ore taken out more than 90%. Tungsten ore dressing methods mainly hand-selected, HM election, re-election, flotation, magnetic separation and electrostatic separation methods such as. Wolframite in order to re-election dominated by flotation mainly scheelite. Most of our wolframite is easy to choose the type of ore, while the composition of scheelite ore complex, and mostly of refractory ore, coupled with low grade, so not a lot of development.

In addition, tungsten oxide minerals such as tungsten China currently not recycled. China's tungsten ore dressing and processing plant started in 1952 a large-scale factory in Dajishan Tungsten establish 125t / d of gravity concentration plant, the late 50s, former Soviet Union Mechanobr Research and Design Institute for the down hill , West Mountain and hilly Miyama tungsten designed three large-scale tungsten ore processing plant put into operation one after another. 40 years in the production practice constantly sum up experience, and absorb foreign advanced technology dressing, through continuous improvement, so that beneficiation process is improving daily, processing technical and economic indicators have reached the world advanced level.

Nanchang representative non-ferrous metals such as tungsten ore beneficiation company targets, despite nearly 10 years in the annual decline in ore grade, the tungsten recovery remained at 84% or more of the high concentrate grade (WO3) 66.7 % ~ 68.9% (up to 12 tungsten national standards: WO3 content is not less than 65%), ore grade (WO3) 0.25% ~ 0.27%, tailing grade (WO3) 0.036% ~ 0.046%. Tungsten smelting and fire refining method and two kinds of water law. The use of wolframite concentrate or smelting scheelite concentrate, but different smelting process, so both wolframite deposit, there scheelite, we must each ore body, each calculated reserves. When the ore wolframite, scheelite coexist together, to elect a black tungsten concentrate and scheelite concentrate for smelting, respectively. The smelting of mineral raw materials as tungsten tungsten ore concentrates, containing WO3 should meet or greater than 65%.

The pyrometallurgical into tungsten alloy (with W>70 or>65%) by Water Act, a positive tungsten smelting sodium, calcium APT or tungsten, etc.. Finally, further processed into tungsten trioxide (containing WO3>=99.9%), then reducing agent (usually hydrogen) is reduced to tungsten powder (with W>=99.9%) and so on.

Tungsten is recovered from scheelite ore concentrates, or other tungsten concentrates which may, or may not contain scheelite in the form of sodium tungstate and in yields up to 99.5 percent or more by a process in which ground ore substantially below 200 mesh in particle size is first added to a 50 percent sodium hydroxide solution while being agitated to such an extent that the resulting mixture becomes a semi-solid as the temperature is raised above 80°C. The semi-solid is then baked at 135 to 145°C for about 1 to 2 hours, followed by adding sufficient water to the semi-solid to form a slurry having a sodium hydroxide concentration below 6 molar, separating the causticinsoluble sludge from the slurry and washing the sludge with a dilute sodium hydroxide solution to remove residual sodium tungstate.

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Tungsten News & Tungsten Prices, WML Version: http://m.chinatungsten.com

Tungsten is a steel-gray, heavy metal -- chemical symbol "W", atomic number 74, and atomic weight of 183.85. It was isolated in 1783 and originally named wolfram. It's hard and dense, with the highest melting point of any metal (6,192 degrees Fahrenheit) and greatest tensile strength of all metals at temperatures above 3,000 degrees Fahrenheit. These properties are the reasons for most commercial uses of tungsten.

Pure Tungsten
The glowing filament of incandescent light bulbs is made of pure tungsten. Tungsten also is in the starter filament of fluorescent bulbs and filaments of cathode ray tubes. These applications require great tensile strength at very high temperatures. Filament wire represents the single biggest use of tungsten. Pure tungsten also is made into heating elements for electric furnaces used in smelting plants and foundries. Pure tungsten also forms the electron beam target in the vacuum tubes producing X-rays for medical and industrial imaging. The pure metal also is used for lead-free fishing weights, lead-free shotgun pellets, welding rods and in high-tech weighted darts used for sporting competitions.

Tungsten Carbide
Most things made of tungsten are actually made with tungsten alloys. For instance, tungsten alloyed with carbon forms incredibly hard tungsten carbide. This material is used in golf clubs, drill bits, grinding burrs, lathe cutting bits, saw blades, cutting wheels, milling bits, wire pulling dies, water-jet cutter nozzles and armor-piercing artillery shells. It's also used for jewelry, mainly rings. Tungsten carbide can take textured finishes or a high-gloss silvery polish. Because tungsten carbide is so hard, the finish resists dings, scratches and abrasion. It's almost as heavy as gold, so tungsten carbide rings have a satisfactory "heft" when worn.

Other Tungsten Alloys
Tungsten is alloyed with various combinations of iron, copper, nickel, cobalt and/or molybdenum. The most common metallic tungsten alloys combine 90-95 percent tungsten with nickel and iron. Adding cobalt to the alloy enhances strength and ductility. Replacing the iron with cobalt greatly enhances wear resistance. Replacing the nickel-iron with copper produces a strong, wear-resistant alloy with good electrical conductivity. Adding molybdenum to the nickel-iron mix improves strength but reduces ductility. All metallic tungsten alloys are very dense.

Tungsten Alloy Products
Metallic tungsten alloys are about as effective as lead for blocking radiation, with the advantage of being non-toxic. Tungsten alloys are used to make radiation shields and containers for the radioactive materials used in certain medical imaging devices. Tungsten alloys also are used for balancing weights in computer disk drives and racing cars, inertial dampers for aircraft control surfaces, fragmentation artillery shells, bunker-busting bombs, concrete-piercing bullets and wear-resistant electrical switch contacts in high-voltage equipment.

Tungsten Alloy Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-alloy.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Tungsten News & Tungsten Prices, WML Version: http://m.chinatungsten.com