Tungsten ores

Ha2ards encountered with tungsten may be caused by substances associated with the production and use of tungsten, eg. As, Sb, Pb, and other impurities in tungsten ores, Co aerosols and dust in the carbide industry, and thoria used in welding electrodes. Lanthanum is being promoted as a substitute for thoria in this appHcation. 

Bismuth is referred to as a minor metal. It is not generally mined for its own intrinsic value, rather it is mined primarily as a by-product of lead or copper ores. In China, however, bismuth can be found ia tungsten ores. In BoHvia the metal has been mined for its own value, but this has not happened on a consistent basis over the years because fluctuations ia the bismuth price have at times made it uneconomical to recover. 

Traditionally, tungsten ore is chemically processed to ammonium paratungstate [1311-93-9] 5H20, and tungsten oxides, W O. These... 

Includes copper-lead ore, gold ore, gold—sHver ore, lead—zinc ore, molybdenum ore, tungsten ore, zinc ore, fluorspar, flux ores, cleanup, ore shipped direcdy to smelters, and tailings. 

Tungsten ores often contain traces of molybdenum that need to be determined before the ore is processed. When the tungsten content is known, as it usually is, that element can serve as a built-in standard for the determination of molybdenum. In the work to be described, the intensity ratio was measured for molybdenum Ka and tungsten Lyl. The general approach thus resembles that of Eddy and Laby to the analysis of brass (7.10), but conditions are less favorable in the present instance. The background corrections necessary were somewhat involved, and they will be discussed in Chapter 8. See Figure 8-1 c. 

As a specific illustration reference may be drawn to molybdenum reserve scenario in the United States. The reserves are mainly grouped under five categories (i) primary, (ii) byproduct of copper ores, (iii) co-product of copper-molybdenum ores, (iv) by-product of tungsten ores, and (v) by-product of uranium ores. These have been presented and briefly elaborated in Table 1.14. It may finally be recorded by way of summary that the present day molybdenum sources in the world today seem to be principally of two main kinds first, the large-tonnage, low-grade, disseminated type of deposit in which molybdenite is the principal economic mineral second, the deposits in which molybdenite occurs as a by-product in... 

By-product of tungsten ores The Pine Creek mine in California is the only operation that is having such reserves. 

Molybdenum is the 54th most abundant element on Earth. It is relatively rare and is found in just 126 ppm in the Earth s crust. Its major ore is molybdenite (MoS ), which is mined in Colorado in the United States and is found too in Canada, Chile, China, England, Norway, Sweden, Mexico, and Australia. Moldybdenum is also found in two less important ores wul-fenite (PbMoO ) and powellite ([Ca(MoW)0 ]. These ores are usually found in the same sites along with tin and tungsten ores. 

Tungsten ores (oxides) are found in Russia, China, South America, Thailand, and Canada. In the United States, the ores are found in Texas, New Mexico, Colorado, Cahfornia, Arizona, and Nebraska. Today, it is estimated that about 75% of all tungsten is found in China. 

The United States gets most of its bismuth as a by-product from smelting ores of lead, silver, copper, and gold. It is also recovered from the refining of tin and tungsten ores. 

Molybdenum is recovered primarily from its sulfide ore, molybdenite, M0S2. It also is produced, although to a much lesser extent, from the tungsten ore wulfenite, which yields lead molybdate, PbMo04. The first phase of the recovery process generally involves concentration of the ore, because ore coming from the mine is very lean and usually contains less than one percent molybdenum. Molybdenite at first is concentrated by flotation which concentrates the M0S2 over 90%. If wulfenite is used as a source material, concentration is usually done by hydrauhc methods. 

Tungsten is recovered mostly from mineral scheebte and wolframite. The recovery process depends on the mineral, the cost, and the end use i.e., the commercial products to be made. Typical industrial processes have been developed to convert tungsten ores to tungsten metal and alloy products, tungsten steel, non-ferrous alloys, cast and cemented tungsten carbides, and tungsten compounds. A few processes are mentioned briefly below. 

While the blendes contain indium as the sulfide, continued Winkler, Hoppe-Seyler found it in another form, which could not be definitely determined, in a tungsten ore from an unknown locality, and later in the wolframite from Zinnwald. The latter contains 0.0228 per cent of indium. In the meantime, I have placed many minerals (without previous concentration, to be sure) before the slit of the spectroscope, but have never found one which gave the desired reaction. It therefore seems as if the occurrence of indium in nature is exceedingly scarce or it must in most cases play the role of a difficultly discoverable satellite (81). 

Analytical data of samples of ore utilised on the commercial scale are set out on p. 119. By-products produced during the working-up of the rare earths for cerium and thorium compounds for use in the manufacture of incandescent mantles, as well as by-products from oertain tin and tungsten ores, are also available as sources of tantalum. 

Amine salts have been used for more than 25 years in the manufacture of pure ammonium paratungstate from sodium tungstate solutions obtained from the leaching of tungsten ores with alkali.211 Such solutions are produced by the leaching of scheelite with sodium carbonate solution at 190 to 225 °C... 

Tungsten ores are concentrated by mechanical and magnetic processes and the concentrates attacked by fusion with NaOH. The cooled melts are leached with water, giving solutions of sodium tungstate from which hydrous W03 is precipitated on acidification. The hydrous oxide is dried and reduced to metal by hydrogen. 

Articles concerned with tungsten history usually start by describing the discovery of tungsten ores, compounds, and the element. In reality, however, the history of tungsten began with the formation of the tungsten atoms, a very long time ago. 

Sn) CassHerite (W) Tungsten ores (Cu) Chalcopyrite (Zn) Sphalerite (Pb) Galena (Ag) Silver salt (Au) Gold (Sb) Stibnite (Hg) Cinnabar... 

Tungsten ore crystallization can be classified as near-source high-temperature deposits, because wolframite as well as scheelite range on the high-temperature end of the series of minerals crystallizing from hydrothermal liquid. Due to the properties of this liquid, a move to further distant places may also occur. 

Tungsten ore deposits have been classified according to their formation, which is closely related to the properties and composition- of the residual magma and the hydrothermal liquid as well as to the physical and chemical properties of the surroimding... 

From time to time, summaries about the tungsten ore reserves are published in the current literature. In principle, it must be taken into account that all those figures are based on estimates. Moreover, they are influenced by the demand of tungsten, the market situation, and consequently by the world market price for tungsten. 

Table 2.8 informs about the tungsten ore reserves of countries, continents, and the earth at different times. By far the largest reserves lie in the Peoples Republic of China... 

TABLE 2.8. Reserves of Tungsten Ore at Different Times ([lO t] tungsten content) [2.23]... 

Mining methods for tungsten ore are not at all exceptional and usually are adapted to the geology of the ore deposit. 

---