In theory, high purity blue tungsten oxide (BTO) refers to the β-tungsten oxide with a very high purity of 99.99% and above. The quality of tungsten products is getting more and more attention with the constant rise of high and new technology. According to the tungsten products on the performance of genetic, high-purity blue tungsten oxide will directly contribute to the high purity requirements of downstream products.

Doped yellow tungsten oxide, also known as doped tungsten trioxide, is a good catalyst. Compared with the common yellow tungsten oxide, the photoelectric conversion efficiency and photoelectric catalytic activity of the doped tungsten trioxide have been improved. For example, Fe is doped to form Fe2O3 and Fe3+ can capture the photo electron, which inhibits the recombination of electron and hole. 

Electric separation utilizes different conductivity of mine and vein mineral grain, can process electric classification and separation in high voltage electric field. It is effective method to separate tungsten and tin in tungsten scheelite. But it is also used in tungsten concentrate gravity separation.

Intermediates of tungsten include ammonium paratungstate, tungsten metal powder, and tungsten carbide, cast carbide.

Ammonium Paratungstate

APT [(NH4)10[H2W12O42] • 4 H2O] is the main intermediate and also the main tungsten raw material traded in the market. APT is usually calcined to yellow (WO3) or blue oxide (WO3-X; a slightly substoichimetric trioxide with varying oxygen content). 

Concentrates are the primary tungsten sources and scrap is the secondary tungsten sources in the tungsten processing.

Concentrates (Primary Tungsten Sources)

Modern processing methods dissolve scheelite and wolframite concentrates by an alkaline pressure digestion, using either a soda or a concentrated NaOH solution. The sodium tungstate solution obtained is purified by precipitation and filtration, before it is converted into an ammonium tungstate solution. 

First, tungsten-containing steels were patented in 1858, leading to the first self-hardening steels in 1868.  High speed steels with tungsten additions up to 20% were first exhibited at the World Exhibition in Paris in 1900, and revolutionized engineering practice in the early 20th century. Such steels (Taylor- and White) are still used today in practically every machine shop of the world.

In 1781, the outstanding Swedish chemist Carl Wilhelm Scheele published the results of his experiments on the mineral tungsten in Kongl. Vetenskaps- Academiens Nya Handlingar, with the title: “The Constituents of Tungsten”.  In this work he demonstrated that the mineral contains lime and a still unknown acid, which he called tungstic acid. Torbern Bergman, professor in Uppsala, suggested preparing the corresponding metal by charcoal reduction of the obtained acid.

Tungsten, like all the elements having a higher atomic number than iron, cannot be formed by nuclear fusion processes in stars, as is the case for those elements with a lower atomic number, but originates only by neutron or proton absorption of already existing bigger nuclei. 

Tungsten and Wolfram are the names given to element 74 of Mendeleev's Periodic Table of the Chemical Elements. Its chemical symbol is W.

Tungsten has the highest melting point of all metals (3,422± 15°C). At this temperature most of the other engineering metals (Fe, Al, Cu, Ti) have already vaporized. Its boiling point of about 5,700°C corresponds to the surface of the sun. 

Tungsten scheelite is non-conducting but tin is conductive. Use power classification can separate them effectively. So tungsten scheelite electric separation is invented.