A NEW PROCESS FOR PRODUCTION OF TUNGSTEN, TUNGSTEN CARBIDE AND TUNGSTEN-OXIDE POWDERS

A new factory commenced operation in Israel to produce tungsten products of top quality: tungsten metal powder (W), tungsten carbide powder (WC), tungsten yellow oxide (WO3) and tungstic acid (H2WO4) for applications such as: hard metals (cemented carbides), heavy metals, electrical components, electrodes, chemicals, etc. A new technology was developed in Israel in order to recover these products from W-containing scrap by a chemical/metallurgical process to obtain high purity and excellent control over the grain size distribution of the products. The new technology offers the following advantages: a. Versatility of scrap materials: various scrap compositions (hard metal, heavy metal, W-Cu alloys and others) of various sizes - up to 250 mm diameter and 35 kg weight a piece, coated or uncoated with or without brazing material residues. b. Natural sub-micron powders: the WO3 powder, obtained as an intermediate product in the new process, is of fine grain size (may be controlled between 0.8 to 3.0 microns). Therefore, the sub-micron W grades obtained are not a result of crushing or milling of the products and thus gram growth during sintering is prevented. c. Better control of the grain size is also obtained due to the fine uniform oxide grain size. The W metal powders as well as WC powders are, therefore, more uniform and so is the resulting structure of the hard metal obtained.