Metalothermic reduction of refractory metal oxides
View Patent ↗High purity refractory metals, valve metals, refractory metal oxides, valve metal oxides, or alloys thereof suitable for a variety of electrical, optical and mill product/fabricated parts usages are produced from their respective oxides by metalothermic reduction of a solid or liquid form of such oxide using a reducing agent that establishes (after ignition) a highly exothermic reaction, the reaction preferably taking place in a continuously or step-wise moving oxide such as gravity fall with metal retrievable at the bottom and an oxide of the reducing agent being removable as a gas or in other convenient form and unreacted reducing agent derivatives being removable by leaching or like process.
1. A high purity powder, wherein the powder is selected from the group consisting of tantalum metal powders and tantalum alloy powders, wherein the powder has the following particle size distribution as determined using a Malvern Mastersizer 2000 particle size analyzer without ultrasonic treatment:
i) 90% of the particles have a particle size of 252 microns or less,
ii) 50% of the particles have a particle size of 50 microns or less, and
iii) 10% of the particles have a particle size of 8 microns or less
and wherein said powder contains less than 5 ppm of chromium, less than 5 ppm of iron, less than 5 ppm of nickel, less than 10 ppm of potassium and less than 1 ppm of sodium.
2. A capacitor made from the powder of claim 1 .