The Application and Preparation of Vanadium Metal

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Preparation of Vanadium Metal

The process to restore the vanadium oxide into metal vanadium by using metal or carbon is an important element of the whole vanadium metallurgy processes. There are essentially four methods: calcium thermal reduction, vacuum carbon thermal reduction, magnesium chloride thermal reduction and aluminothermic reduction.

Calcium Thermal Reduction

It is an industrial-scale production of hot metal vanadium: with V2O5 or V2O3 as raw material, calcium metal shavings as a reducing agent, 60% of the theoretical amount of calcium, add V2O5(V203) calcarenaceous mixture into magnesia crucible placed in a steel reaction vessel purged by inert gas, then add iodine (sulfur is also available) as the heating agent , the amount of iodine measured by adding 0.2mol iodine per mol vanadium, reaction begins after sealed in argon, when the temperature reaches 973K by heating in high-frequency induction:

V2O5+5Ca≈2V+5CaO+1620.07kJ

V2O3+3Ca≈2V+3CaO+683.24kJ

Due to the exothermic reaction system, stop the heating after the reaction start as the temperature will automatically rise to 2173K, and then wash the generated attachments on vanadium or vanadium metal pieces of plastic granules. The vanadium yield is about 74%, and it can be increased to 82%~97.5% if we add aluminum in the furnace charge; however the vanadium will be brittle owing to the high aluminum-vanadium.

Vacuum Carbothermal Reduction

Mix the purity V2O5 powder with carbon powder, with 10% ether solution of camphor or alcohol, put the mixture into a vacuum induction furnace or a carbon resistance furnace after briquetting. Heating to 1573K when the vacuum furnace pressure reaches 6.66×10-1Pa, insulation for 2h, after cooling, break the reaction product. Matching certain amount of vanadium carbide or vanadium oxide for the secondary reduction based on the component of the first reduction product, which to keep the second reduction furnace vacuum pressure 2.66×10-2Pa, temperature between 1973~2023K, and thermal insulation for a period of time. The component of the resulting vacuum carbon reduction of metal vanadium (mass fractions m/%) are as follows: 99.5 vanadium, 0.05 oxygen, nitrogen 0.01, and carbon 0.1, with vanadium yield up to 98% to 99%.

Magnesiothermic Reduction

Magnesium metal is of extreme purity, cheaper than calcium, and the reaction of magnesium chloride volatile more easily than calcium chloride, so using calcium magnesium reduction is more reasonable than with calcium reduction. The reduction process is as follows: a. using vanadium containing 80% of vanadium iron chloride to make coarse tetrachloride vanadium; b.  removing the coarse four vanadium oxide iron trichloride by distillating; c. transforming tetrachloride vanadium into VCl3 in the cylindrical magnesium reflux device; d. using distillation to remove the VCl3 oxychloride vanadium VOC13; e. after cooling, place the broken vanadium trichloride in the reduction reaction tank, adding magnesium under argon protection reducing VCl3 into metal vanadium; f. removing the vanadium metal magnesium and magnesium chloride by vacuum distillation; g. water-washing the metal vanadium residue of magnesium chloride, the left is vanadium metal powder after drying. The reduction is addressed in mild steel crucible, with the mild steel crucible in the mild steel tank, with gas heating, first add magnesium ingot into the pickling crucible, then add 3 times the amount of magnesium ingot vanadium trichloride. Keep the reduction temperature at 1023~1073k. According to the temperature indicator showing how fast the reaction is going, add magnesium if slow, insulate for about 7h before cooling to room temperature. Each batch production is 18~20kg metal vanadium. Then remove the crucible, slowly heated to 573k in distillation in the furnace, and preserve the heat at 573k. When the indicated pressure goes up to 0.1333~0.6666Pa again, heat to 1173~1223k and insulate for 8h, then rapidly cool it down to room temperature; finally, the vanadium is 99.5%~99.6% and the purity of sponge vanadium yield is 96%.

Aluminothermic Reduction

In Germany, people use aluminothermic reduction method to produce thick metal vanadium. This method is the reaction of vanadium pentoxide and pure aluminum to generate vanadium alloys. Vanadium alloy will be dealuminizing in vacuum aluminum in a high temperature of 2063 K, and the obtained coarse metal vanadium containing 94%~97% vanadium.

The Use of Metal vanadium

The use of metal vanadium is mainly for the manufacture of alloy steel and non-ferrous alloys, also in the electronics industry for the manufacture of a cathode tube, a gate, and a getter-ray target, the electrode tube phosphor, etc., or as additive elements for titanium-based alloy and high strength heat-resistant special alloys. It can also be made into fast breeder reactors and nuclear fuel sheath.