Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
  • C25C3/34—Electrolytic production, recovery or refining of metals by electrolysis of melts of metals not provided for in groups C25C3/02 - C25C3/32
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B34/00—Obtaining refractory metals
  • C22B34/30—Obtaining chromium, molybdenum or tungsten
  • C22B34/36—Obtaining tungsten
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B5/00—General methods of reducing to metals
  • C22B5/02—Dry methods smelting of sulfides or formation of mattes
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C5/00—Electrolytic production, recovery or refining of metal powders or porous metal masses
  • C25C5/04—Electrolytic production, recovery or refining of metal powders or porous metal masses from melts
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B34/00—Obtaining refractory metals
  • C22B34/10—Obtaining titanium, zirconium or hafnium
  • C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
  • C22B34/129—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining metallic titanium from titanium compounds by dissociation, e.g. thermic dissociation of titanium tetraiodide, or by electrolysis or with the use of an electric arc

Definitions

• This invention relates to a method for producing tungsten and/or tungsten alloys from tungsten bearing compounds by electroreduction in molten salt solutions.
• the process for carrying out the invention can be expanded to include other metals, which show similar behavior with tungsten.
• Metal production by molten salt electrolysis is used for more than a century. Metals can not be produced by gas-based pyro-reduction, metallothermic reduction, hydrometallurgical methods or aqueous electrochemical techniques if their compounds are very stable. In these cases, where production by other routes is not feasible due to thermodynamic, kinetic or economical reasons, the choice is limited to electrowon the metal by the electrolysis of various molten salts. However fused salt electrolysis is satisfactory only for low melting point metals which are deposited in the liquid state. High melting point metals can be electrowon in the solid state because the reduction temperature is less than the melting point; but this results in dendritic deposition which is prone to oxidation.
• the classical molten salt electrolysis involves dissolution of the starting material, containing the metal to be electrowon, in the electrolyte. A subsequent electrowinning of the metal from the solution takes place by direct current reduction.
• Many metals exist as oxides or oxygen bearing metal compounds in nature. Therefore, there had been some attempts to produce metals from their oxides by molten salt electrolysis method. In these work, metal oxides were dissolved in fluoride melts because fluorides are regarded to be better at dissolving oxides than chlorides. However, most of the time these studies failed to develop a commercial large scale production because fluorides usually melt at higher temperatures and they are far more corrosive.
• metals or metal alloys can be produced without dissolution of the starting material in the electrolyte and continuous electrolysis of the molten salts.
• the patent on the process (WO 99/64638) claims that Ti, Si, Ge, Zr, Hf, Sm, U, Al, Mg, Nd, Mo, Cr, Nb and any alloys thereof could be produced by FFC Cambridge process.
• WO 3 (S) + 3H 2 (g) W (s) + 3H 2 O (g)
• 70% of total tungsten world reserves is scheelite (CaWO 4 ) and 30% is Wolframite ((Fe, Mn)WO 4 ). Production of tungsten oxides from these minerals is a complicated and time consuming procedure. Furthermore, Gibbs free energy change of the above reaction is not a large negative value; which means there is considerably low driving force for the process at the temperatures of reduction. In addition, since the above reaction is endothermic, in order to attain and preserve the high temperatures required for reduction, continuous external heat supply is necessary.
• M 1 M 2 X cathode is a conductor.
• M 1 M 2 X may be an insulator in contact with a conductor.
• M 1 M 2 X is any compound having scheelite stochiometry (M 1 M 2 O 4 ).
• M 1 is any of W, Mo or any alloy thereof.
• M 2 is any of Ca, Fe, Ba, Mn, Pb, Cd, Sr or any alloy thereof.
• X is any of O, S, C, or N.
• the electrolyte is a molten chloride salt or chloride salt solutions.
• electrolysis preferably occurs with a potential below the decomposition potential of the electrolyte.
• This invention is an alternative tungsten production technique.
• the process for carrying out the invention is more direct and cheaper than the usual production technique.
• the invention can be expanded to include other metals which have similar characteristics with tungsten.
• the cathode of the cell is tungsten (or any metal which has similar characteristics with tungsten) compounds. In order to act as cathode, these compounds need to be either conductors, or used in contact with a conductor. As the anode material graphite, carbon or an inert metal could be used.
• This invention is based on the removal of non-metallic substances from metal compounds in molten salts, without continuous electrolysis of the electrolyte. In order to ease the diffusion of the non-metallic substances, it is advantageous to use the cathode materials porous.
• the starting materials should not have serious solubility in the electrolyte. This situation may impose a restriction on the temperature range over which electrolysis can be done.
• chloride salts are chosen. These salts can be used alone or as salt solutions in order to control the temperature and solubility of the cathode material. In order to have more freedom about voltage selection, it is an important advantage to use electrolytes with decomposition potentials as high as possible.
• Synthetically produced calcium tungstate (CaWO 4 ) powder was pressed in the form of a pellet of weight 2.5 grams, diameter 1.5 cm and height 0.3 cm. Then this porous CaWO 4 pellet, forming the cathode of the cell, was placed into a spoon (made up of stainless steel), which was attached to the end of a stainless steel wire current collector. A graphite rod was used as the anode material and the electrolyte was CaCI 2 -NaCI salt mixture at eutectic composition. At 600 ° C the electrodes were immersed into the electrolyte, and a potential difference of 2.5 volts was applied between the electrodes for 500 minutes. After the electrolysis experiment, electrodes were removed from the molten salt solution and left to cool.
• CaWO 4 calcium tungstate

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Electrolytic Production Of Metals (AREA)

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• 2007
  • 2007-10-22 TR TR2007/07197A patent/TR200707197A1/xx unknown
• 2008
  • 2008-08-15 CA CA2703400A patent/CA2703400C/en active Active
  • 2008-08-15 WO PCT/TR2008/000101 patent/WO2009054819A1/en active Application Filing
  • 2008-08-15 RU RU2010115668/02A patent/RU2463387C2/ru not_active IP Right Cessation

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