Abstract A method is provided for producing refractory metal powder from a refractory metal ferro-alloy containing a refractory metal selected from the group consisting of tungsten, molybdenum, niobium and tantalum and containing at least about 8 percent total of iron plus silicon, the silicon constituting at least one halidizable metal in addition to iron as an impurity. The alloy is crushed and then subjected to dissolution at a temperature of at least about 900* C with a gaseous hydrogen halide selected from the group HCl and HF for a time at least sufficient to effect substantial removal of said iron and said at least one other metal impurity as halide vapor, whereby to provide a finely divided refractory metal powder low in said impurities.
The method of claim 1, wherein the particle size of the ferro-alloy is less than about 2 mm, wherein the temperature of dissolution ranges from about 900* to 1,200* C, and wherein the time of dissolution over said temperature is at least about 1 hour.
Claim 2
Dependent Claim
27 words
The method of claim 2, wherein the dissolution temperature ranges from about 1,000* to 1,100* C and the time of treatment from about 2 to 4 hours.
Claim 3
Dependent Claim
150 words
In a method of producing tungsten metal powder from a tungsten-containing ferro-alloy containing at least about 8 percent total of iron plus silicon, said silicon constituting at least one other halidizable metal impurity in addition to iron, and the balance of said alloy essentially tungsten, the improvement for substantially removing said iron and said at least one metal impurity which comprises, providing said tungsten-containing ferro-alloy having a particle size of less than about 2 mm, and then subjecting said alloy to dissolution in the presence of a gaseous hydrogen halide selected from the group consisting of HC1 and HF at a temperature of at least about 900* C for a time at least sufficient to effect substantial removal of said iron and said at least one metal impurity as halide vapor, and whereby a finely divided tungsten metal powder of substantially reduced size is obtained low in said metal impurities.
Claim 4
Dependent Claim
29 words
The method of claim 4, wherein the temperature of dissolution ranges from about 900* to 1,200* C, and wherein the time of dissolution is at least about 1 hour.
Claim 5
Dependent Claim
28 words
The method of claim 5, wherein the dissolution temperature ranges from about 1,000* to 1,100* C and the time of treatment ranges from about 2 to 4 hours.