Scheelite Concentrate Alkali Pressing Method Improvement

Nearly 70% of the world's tungsten resources by scheelite structure. At present, with the continuous depletion of wolframite Scheelite Resources, has become the main industrial raw materials.

At present, nearly more than 95% of the tungsten smelting enterprises adopt alkali heat milling process decomposition of scheelite. But this method adopts the equipment for the autoclave, still belongs to high voltage equipment, need to bring pressure to ensure 8-15 kilograms of scheelite decomposition, there are some security risks, at the same time, the production process is intermittent single kettle operation, and the scale and efficiency of production are restricted. Therefore, it is urgent to develop a new and safe, continuous and efficient tungsten ore decomposition process.

In order to improve the implementation of alkali autoclave process, some scholars proposed an alkali pressing method for processing tungsten scheelite, which comprises the following steps:

Step one, the scheelite size ground to less than 200 mesh, to WO₃ dollars, the scheelite containing tungsten 30 ~ 70wt.%.

Step two, the milled scheelite with solid NaOH and SiO₂ mixed evenly, the amount of NaOH was 1 ~ 3 times of the theoretical amount, the amount of SiO₂ is 1.0-1.5 times of the theoretical amount.

In step three, the obtained mixture is roasted in a high temperature furnace; the roasting temperature is controlled at 600~800 ℃, and the calcination time is controlled at 1.0~3.0 hours.

Step four, the calcined material obtained in step three is flooded to obtain a sodium tungstate solution, wherein the leaching liquid to solid ratio is 2: 1 ~ 5: 1; the leaching temperature is controlled at room temperature to 95 ℃, the leaching time is controlled at 3.0 ~ 5.0 hours, filtered, washed with water and dried to obtain a residue containing insoluble WO₃ 0.21%, the decomposition rate of 99.85%.

Research shows that, compared with the prior art, the scheelite with solid sodium hydroxide and silica mixed roasting to achieve reaction, which overcomes the defects of the autoclave using production batch operation, have certain security problems, at the same time, compared with sodium carbonate sintering early decomposition of tungsten ore, low reaction temperature near 200 ℃, increase the extraction rate of tungsten about 5%, greatly reduces the energy consumption and improve the utilization rate of tungsten resources.

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