Tungsten Products Research Articles

Showpiece APT plant rides the tungsten wave

China produces approximately 70 per cent of the world's tungsten raw materials and possesses nearly 45 per cent of the world's known tungsten ore reserves. Over the past five years the rapid growth in China's economy and increasing global demand for tungsten has driven up prices of high quality intermediate tungsten products such as ammonium paratungstate (APT) and tungsten oxides. In the second of two articles, Bernard Williams reports from a new 10 000 tonnes/year APT powder plant at Chenzhou in Hunan Province.

SD 170/175/180/185

Abstract The SD group is part of the Densalloy family of materials, which are high-density alloys used for a variety of applications, from counterbalance weights to radiation shielding. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on forming. Filing Code: W-28. Producer or source: Tungsten Products, An Allegheny Technologies Company.

DENSALLOY DENS21/DENS23/DENS25

Abstract Densalloy alloys are tungsten heavy alloys for applications ranging from use in radiation shielding to use in pins for ejection molding. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming and machining. Filing Code: W-27. Producer or source: Tungsten Products, An Allegheny Technologies Company.

Recovery of tungsten and vanadium from tungsten alloy scrap

This investigation resulted in the development of a flowsheet for the recovery of tungsten and vanadium from a leach solution of tungsten alloy scrap. The leach solution contained 95 kg/m 3 WO 3, 0.175 kg/m 3 V and some other impurities. In the purification step, MgCl 2 combined with Al 2(SO 4) 3 was employed to remove the majority of Si, Al, P and Fe from the solution. This step was followed by converting tungsten and vanadium into the calcium salt with the addition of Ca(OH) 2. When the mixed calcium salt was treated with formic acid solution, vanadium was selectively dissolved and separated from tungsten, while tungsten was rejected in the residue. The vanadium solution was then purified with H 2SO 4 and the ammonium meta-vanadate was precipitated with NH 4OH to give 86.87% vanadium recovery. The leach residue of formic acid solution was dissolved with hot HCl solution in the presence of oxygen, resulting in the conversion of CaWO 4 to H 2WO 4. This step was followed by NH 4OH addition to convert H 2WO 4 to (NH 4) 2WO 4 and removal of the remaining impurities. Finally, ammonium para-tungstate (APT) was crystallized from the solution of (NH 4) 2WO 4 by evaporation. The purity of both tungsten and vanadium products met the standard specifications.

A novel process for recovery of tungsten and vanadium from a leach solution of tungsten alloy scrap

A process is developed in this study to recover tungsten and vanadium from a sodium tungstate solution containing 95 g/l WO 3, 0.175 g/l V and some impurities. The solution is produced by roasting a tungsten alloy scrap and subsequently dissolving it in an alkali solution. The process to recover tungsten and vanadium involves three steps: purification and separation of vanadium from tungsten, recovery of vanadium, recovery of tungsten. For the recovery of vanadium, MgCl 2 and ammonia solution are used in the purification step to precipitate the impurities and the vanadate. A small amount of acetic acid solution is then used to selectively dissolve the vanadium from the mixed residue and leave the impurities in the residue. Finally, NH 4VO 3 is precipitated by adding NH 4OH to the solution, to achieve a vanadium recovery of 88.28%. For the recovery of tungsten, the sodium salt is converted to calcium salt after purification of the sodium tungstate solution. The CaWO 4 is then converted to H 2WO 4 using a HCl solution, followed by dissolving in NH 4OH solution and crystallization of APT. A tungsten recovery of over 85% is obtained. The purity of both the final tungsten and vanadium products has met the standard specifications.

Tungsten Particle-Induced Nicking of Supercoiled Plasmid DNA

Small particles of metallic tungsten, known also as tungsten microprojectiles, are routinely used for biotechnological purposes. In such applications, tungsten was observed to affect the integrity of plasmid DNA. Here we present evidence that interaction between tungsten particles and intact circular plasmids pU19, pUC119, and ColE1 may result in generation of a limited number of single-strand DNA breaks. As a consequence, supercoiled DNA is converted into its open circular form and no fragmentation products can be detected. The rate of the tungsten-mediated reaction depends on pH but is not influenced by ascorbate, Tris, or EDTA. No DNA nicking can be observed when the tungsten particles are replaced by substances that can be leached out from these particles with water or incubation buffers. Likewise, commercial sodium tungstate, tungsten (VI) oxide, and tungsten (VI) chloride and products of its decomposition remain DNA undamaged. Native plasmid DNA molecules, upon adsorption on the surface of tungsten microparticles, may undergo some nicking without a need for participation of external catalysts.

Direct determination of trace elements in tungsten products using an inductively coupled plasma optical emission charge coupled device detector spectrometer

An echelle inductively coupled plasma optical emission spectrometer equipped with a segmented array of charge coupled device detectors was used for the direct determination of trace impurities in tungsten products. No sample preparation was necessary. The multicomponent spectral fitting software provided by the instrument was used for the correction of spectral interference and background. The detection limits of the trace elements Al, As, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Ni, P, Pb, Sb, Sn, Ti and V in tungsten matrix were obtained under optimized operating conditions. The accuracy of the proposed method was assessed using three National Reference Materials. As a result of their ultra-trace concentrations in the reference materials, As, Pb and Sn could not be determined satisfactorily. The concentrations found for the other elements agreed quite well with those of the certified values of the reference materials.

Aspects of effective doping and the incorporation of dopant

This paper describes results of many decades of research work on non-sag (NS) tungsten. Some of the results did not solve a given technical problem but they can be used to solve other technical or theoretical questions. Besides the role of intentional additives, the effect of nitrogen (as NH 3), of phosphorus (as H 3PO 4) and of other additives is also discussed as is their role in building tungsten bronzes and beta-tungsten. In connection with the important role of gaseous hydroxides on the incorporation of additives into the metal particles, the effect of As, Mo, etc., on this volatilization process (CVT), is also treated. Numerous SEM pictures show that the role of the melting effects is emphasized in the incorporation of potassium (as silicates). SEM pictures give information also about the influence of many experimental additives on the morphology of intermediate products of metal powder production. Some suggestions are given concerning the testing of NS metal powder without precursor tests and, further, about special chemical effects influencing the performance and use of tungsten products.

Formation of η-benzene or η-cyclohexa-1,3-diene compounds of chromium, tungsten, and rhenium from cyclohexane and the metal atoms

Co-condensation of atoms of tungsten rhenium, and chromium with a mixture of cyclohexane and trimethylphosphine causes activation of the cyclohexane giving the compounds W(η-C6H8)(PMe3)2H4, W(η-C6H8)(PMe3)3H2, W(η-C6H6)(PMe3)2H2, W(PMe3)4H4, Re(η-C6H6)(PMe3)2H, and Cr(η-C6H6)(PMe3)3 respectively; when tungsten atoms react with a 3 : 1 mixture of cyclohexane and perdeuteriocyclohexane, together with PMe3, then the absence of mixed H–D tungsten Products indicates that the C–H activation processes are intramolecular.

Selective Extraction of Tungsten from Searles Lake Brines

Abstract Tungsten was successfully extracted from the brines of Searles Lake, Calif., in a demonstration unit based on 9 years of laboratory research conducted by the U.S. Department of the Interior, Bureau of Mines. Pilot-scale operation was initiated in July 1979 at the Westend facility of the Kerr-McGee Chemical Corp. at Trona, Calif. The extractive method, based on a novel ion exchange resin, resulted from research supporting one of the Bureau's goals: helping to insure an adequate supply of minerals to meet national economic and strategic needs. The objectives met during pilot testing included proving operational viability during seasonal changes in brine properties, concentrating the tungsten to enable concluding tungsten recovery research, supplying escalation data necessary for commercialization, and confirming earlier small-scale laboratory work. The demonstration unit typically removed 92 percent of the tungsten from alkaline brine using QRF (8-hydroxyquino-line-resorcinol-formaldehyde) resin beads produced by the Bureau. A “merry-go-round” system was employed whereby two 12-inch-diameter resin beds were loaded in series while a third bed was eluted. Testing was concluded after treating over 500,000 gallons of brine. Tungsten, isolated in the primary ion exchange system, was recon-centrated in a secondary ion exchange system. Several tungsten products were produced from tungsten-rich solutions.

Petroleum for U. S. Agriculture

commodity crises. The quixotics, of course, also tilt among themselves whenever windmills are scarce. Many feel that public and private investments in technology have not kept pace with the need while others feel that seeking the bonanza in advanced technology may result in just another dry hole. During the past year critical shortages and/or substantial fluctuations in prices have occurred in tin, pig iron, lead, zinc, mercury, antimony, tungsten, silver, magnesium, bismuth, palladium, gold, phosphate, coal, petroleum, and petroleum products. Each of these commodities has experienced a price change of more than 50 percent during the past 12 months [22]. Serious shortages of natural gas are expected to occur again this year, and a scheduled national coal strike could have a more substantial impact on energy supplies this fall and winter than the Arab oil embargo of the previous year. During the last eighteen months fossil fuels have experienced at least a doubling in price. The average prices of petroleum products have more. than doubled. During the past winter, spot prices ozf oil reached levels of more than four times their magnitudes of 18 to 24 months ago. Imports of these critical commodities constitute a significant component of U. S. consumption, and most may be subject to actions of international cartels seeking political or monetary gains. The recent Arab oil embargo is sometimes recognized to be an international cartel action to achieve both political and monetary concessions.

Charge-transfer interactions involving high oxidation state transitionmetal fluorides

Charge-transfer interactions have been observed between NbF5, MoF6, and WF6 and the Group IV compounds MX4(M = Si, Ge, Sn, X = alkyl; M = C, Si, Sn, X = Cl) and between WF6 and C6H6, C6H5CH3, and C6F5. WF5OMe behaves similarly to WF6 but the spectra of phenoxotungsten (VI) fluorides are solvent independent. Photolysis of solutions of WF6 in C6H6, C6H5CH3, and Me4Sn, leads to reduction of tungsten but pure products are not obtained.

Some Tungsten and Molybdenum Products

Some Tungsten and Molybdenum Products