Reclamation process for tungsten carbide and tungsten-based materials
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United States of America Patent
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Mar 25, 1997
Grant Date -
N/A
app pub date -
May 23, 1995
filing date -
May 23, 1995
priority date (Note) -
Expired
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Abstract
Tungsten carbide and/or tungsten can be recycled by oxidizing the tungsten composition at a temperature greater than 700.degree. C. to form a water insoluble tungsten trioxide. This is then reduced to form tungsten dioxide. The tungsten dioxide is subjected to a low temperature oxidation which forms monoclinic tungsten trioxide. The monoclinic tungsten trioxide is then dissolved in ammonia to form ammonium tungstate. If present, the binder metal such as cobalt is converted into the soluble ammine complex. This can be spray dried and carburized to form tungsten carbide. If the form composition includes cobalt or other binder metal, the ratio of cobalt to tungsten can be adjusted by adding cobalt salts or ammonium metatungstate to the aqueous solution prior to spray drying to form a precursor composition. This is uniquely suitable for forming a cobalt tungsten carbide composition.
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