Process for producing metal powders by reduction of oxides with magnesium vapors and metal powder obtained in such a manner

摘要

The present invention relates to a process for producing metal powders selected from the group consisting of Ta and Nb, and all up thereof, alone or with one or more metals selected from the group consisting of Ti, Mo, W, Hf, V and Zr added thereto or co-produced therewith, comprising the steps of : (a) providing an oxide or mixed oxides of the metal (s), the oxide itself being in a form that is traversable by gas, (b) generating a gaseous reducing agent at a site outside the oxide mass and passing the gas through the mass at an elevated temperature, c) the reactants selection, porosity of the oxide, temperature and time of the reduction reaction being selected for substantially complete reduction of the oxide (s) to free the metal portion thereof, the residual oxide of reducing agent formed in the reaction being easily removable, whereby a high surface area powder is formed in a process that essentially avoids the use of molten state reducing agent in the production of metal or alloy powder. Further, there is a process comprising the steps of : (a) providing an oxide or mixed oxides of the metal (s), the oxide being in a form that is traversible by gas, (b) passing a hydrogen containing gas through the mass at an elevated temperature, (c) the porosity of the oxide, temperature and time of reduction reaction being selected to remove at least 20 percent of the oxygen contained in the oxide to produce a suboxide, (d) further reducing the suboxide in a second stage with reducing agents being selected from the group consisting of reducing metals and hydrides of reducing metals, thereby substantially completely reducing the oxide to free the metal portion thereof.