Melt Extraction Processing Carbonization Tungsten Carbide Production

The process is made ​​directly by the tungsten carbide, the former Soviet Union in this regard fruitful research. According to the Canadian Pacific International Industrial Co., Kirby said: used to produce tungsten carbide powder purity has reached 99.3% to 99.4%, while the cost of production of tungsten carbide with the traditional way of comparison can be reduced by half, so much attention.

Process and Principle

The process comprises three main technical steps: melt extraction, carbonation and the grinding gas into leaching purified.

(1) Melt Extraction

The tungsten and Na2SiO3, NaCl mixed and melted 1050 ~ 1100 ℃, the following reaction occurs:

2 (Fe, Mn) WO4 +3 Na2SiO3 +16 NaCl = 2 (Na2WO4 · 8NaCl) + Na2 (Fe, Mn) 2Si3O9

The resulting tungsten Na2WO4 · 8NaCl immiscible silicate phase, according to the density stratification, the upper silicate phases, the lower chloride - tungstate phase. The two phases were separated by decantation, the 98% to 99% of WO3 and a small amount of impurity in the titanium manganese tungstate phase.

In scheelite as raw material, Al2O3 and NaF should be added as a flux. But if the scheelite and wolframite 1:3 mix to join, you can add the free flux.

(2) Gas into Carbonized

The chloride - NaCl added tungstate scaling, and then in 1050 ~ 1070 ℃ when the pass into the natural gas, tungsten carbide reaction occurs as follows:

Na2WO4 +4 CH4 = Na2O + WC +3 CO +8 H2

(3) Purification Polishing Leaching

Tungsten periodically removed from the grinding and dispersion of salt furnace, first with 10% HCl and washed with 3% NaOH solution, extract, and then through the filter to remove impurities to get a more pure tungsten carbide powder.

Process Conditions and Indicators

Add the material ratio of: wolframite: NaCl: Na2SiO3 = 33:47:20; at 1050 ~ 1100 ℃ melted and incubated 2h, obtained chloride - tungstate phase substantially composed of: WO325% ~ 30% ; FeO about 0.24%; MnO about 0.3%; silicates containing approximately 0.5% WO3; WO3 recovery of this step to 98% to 99%.

The resulting molten chloride layered - tungstate phase and then in the 1050 ~ 1070 ℃ was passed through the gas, the main component of natural gas methane (CH4) in the utilization rate of approximately 2.2% carbon, 90% of WO3 are recovered into the WC, WC to ground and then acid leaching filtered to further remove impurities, the resulting WC WC carbide to achieve the general requirements.


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