Methods of deoxygenating metals having oxygen dissolved therein in a solid solution
A method of deoxygenating metal can include forming a mixture of: a metal having oxygen dissolved therein in a solid solution, at least one of metallic magnesium and magnesium hydride, and a magnesium-containing salt. The mixture can be heated at a deoxygenation temperature for a period of time under a hydrogen-containing atmosphere to form a deoxygenated metal. The deoxygenated metal can then be cooled. The deoxygenated metal can optionally be subjected to leaching to remove by-products, followed by washing and drying to produce a final deoxygenated metal.
1. A method of deoxygenating metal, comprising:
forming a mixture comprising:
(a) a metal having oxygen dissolved therein in a solid solution, wherein the metal includes less than 50% by weight of metal oxides,
(b) at least one of metallic magnesium and MgH 2 , and
(c) a magnesium-containing salt;
heating the mixture at a deoxygenation temperature for a period of time under a hydrogen-containing atmosphere to form a deoxygenated metal; and
cooling the deoxygenated metal.
2. The method of claim 1 , wherein the metal comprises titanium and has a dissolved oxygen content from about 0.15 wt % to about 14.3 wt %.
3. The method of claim 1 , wherein the metal includes less than 10% by weight of metal oxides.
4. The method of claim 1 , wherein the metal is titanium having less than 10% by weight of metal oxides, and the method further comprises reducing a purified TiO 2 to form a hydrogenated titanium product and dehydrogenating the hydrogenated titanium product to form the metal.
5. The method of claim 1 , wherein the metal is particulate metal powder.
6. The method of claim 1 , wherein the metal is substantially spherical Ti or Ti alloy powder.
7. The method of claim 1 , wherein the mixture further comprises a particulate separator material.
8. The method of claim 7 , wherein the particulate separator is MgO powder.
9. The method of claim 7 , wherein the particulate separator is 0.1 to 1000 wt % by weight of the particulate metal.
10. The method of claim 1 , further comprising pre-oxidizing the metal to an oxygen level of 0.5 wt % to 10 wt % prior to heating the mixture at the deoxygenation temperature, wherein an initial oxygen content of the metal is from 0.2 wt % to 0.5 wt % such that excess MgO is formed as a separator during heating the mixture at the deoxygenation temperature.
11. The method of claim 1 , further comprising spheroidizing either the metal or the deoxygenated metal.
12. The method of claim 11 , wherein the spheroidizing is accomplished by passing an irregularly shaped Ti or Ti alloy powder through an induction plasma torch.
13. The method of claim 1 , wherein the hydrogen-containing atmosphere is substantially pure hydrogen or is a mixture of hydrogen and argon.
14. The method of claim 1 , wherein the magnesium-containing salt is substantially pure MgCl 2 .
15. The method of claim 1 , wherein the magnesium-containing salt comprises MgCl 2 , MgBr 2 , KCl, NaCl, LiCl, RbCl, CsCl, CaCl 2 , or combinations thereof.
16. The method of claim 1 , wherein the deoxygenation temperature is above a melting point of the magnesium-containing salt.
17. The method of claim 1 , wherein the deoxygenation temperature is below a melting point of the metallic magnesium.
18. The method of claim 1 , wherein the deoxygenation temperature is from 550° C. to 900° C.
19. The method of claim 1 , further comprising leaching the deoxygenated metal to remove unreacted magnesium, magnesium byproducts, and optionally salts.
20. The method of claim 1 , wherein the deoxygenated metal has a dissolved oxygen content of less than 0.2% by weight.
21. The method of claim 1 , wherein the deoxygenated metal is a metal powder.
22. The method of claim 21 , wherein the metal powder comprises substantially spherical particles.
23. The method of claim 1 , wherein the deoxygenated metal comprises titanium, aluminum, chromium, vanadium, niobium, tantalum, zirconium, tungsten, molybdenum, hafnium, or alloys thereof.
24. A method of deoxygenating metal, comprising:
forming a mixture comprising:
(a) a metal having oxygen dissolved therein in a solid solution,
(b) at least one of metallic magnesium and MgH 2 , and
(c) a magnesium-containing salt;
heating the mixture at a deoxygenation temperature for a period of time under a hydrogen-containing atmosphere to form a deoxygenated metal, wherein the deoxygenation temperature is below a melting point of the metallic magnesium; and
cooling the deoxygenated metal.
25. A method of deoxygenating metal, comprising:
forming a mixture comprising:
(a) a particulate metal having oxygen dissolved therein in a solid solution,
(b) at least one of metallic magnesium and MgH 2 , and
(c) a magnesium-containing salt;
pre-oxidizing the particulate metal to an oxygen level of 0.5 wt % to 10 wt %, wherein an initial oxygen content of the particulate metal is from 0.2 wt % to 0.5 wt % such that excess MgO is formed as a separator during heating the mixture at a deoxygenation temperature;
heating the mixture at the deoxygenation temperature for a period of time under a hydrogen-containing atmosphere to form a deoxygenated metal; and
cooling the deoxygenated metal.