Basic principle and main technical indexes of tungsten mineral NaF leaching method
First, the basic principle
The NaF leaching method reacts as follows:
At 225 ° C, the concentration equilibrium constant is 24.5.
The leaching rate of tungsten than white with CO 3 2 - -, PO 4 3 - other large (see FIG. 1) F.
Figure 1 Reaction rate of CaWO4 with different anions (PB Kui)
At less than 100 ° C, a CaF 2 film is formed on the surface of the ore particles, which hinders the reaction. Above 100 ° C, the film falls off. The apparent activation energies were 63.54 kJ∕mol and 89.03 kJ∕mol, respectively, at stirring speeds of 830 r∕min and 510 r∕min, respectively.
Second, the main technical indicators
When a Russian scholar treats a white tungsten ore containing 33.7% to 41.5% WO 3 , when the temperature is 225 ° C and the amount of NaF is 1.8 times the theoretical amount, the decomposition rate is 99.2% to 99.8%, and SiO 2 ∕ WO 3 = in the leachate. 0.2% to 0.5%. Yao Zhengang waited for the treatment of Shizhuyuan white tungsten concentrate under industrial conditions. When the amount of NaF was 1.2 times the theoretical amount and 1.5 hours at 190 °C, the decomposition rate was 98.87%, and the obtained Na 2 WO 4 solution contained P0.002g. L, As 0.017 g ∕ L, SiO 2 0.055 g ∕ L.
The disadvantage of the NaF leaching method is that the solubility of NaF is limited, that is, the F - concentration in the leaching agent is limited, and accordingly the unit production capacity is low.
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