Scheelite Phosphate Extraction

The common decomposition methods of scheelite concentrate include acid method and alkali method. At present, with alkali method is relatively common, but recently, in view of the high phosphorus content of scheelite, many scholars have put forward the theory and method of phosphoric acid decomposition, and in general, the benefits of scheelite phosphate extraction method improve a lot.

A company using closed-loop method to decompose scheelite concentrate, the scheme of the process is as follows:

The ball mill scheelite has a particle size of 300 mesh to 150 mesh, the concentration of hydrochloric acid added is 1 mol / L to 2 mol / L, the amount of phosphoric acid (mass ratio of tungsten to phosphate) mw / mpo43- is 1.5∶1～5∶1, after heating to 40 ℃ to 100 ℃, the scheelite is added into a mixture of hydrochloric acid and phosphoric acid for reaction, the stirring speed is 500r / min ~ 950r / min, the liquid to solid ratio is 5: 1 to 10: 1, the reaction time is 1h to 3h, And the filtrate was extracted with an organic phase containing N235 to obtain phosphotungstic acid.

Hydrochloric acid and phosphoric acid complex leaching scheelite, the N235 containing organic phase volume ratio of 10% to 20% N235, 20% n-octanol, 60% to 70% kerosene, compared to 1: 1: 2, after 5min ~ 15min mixing time, the filtrate extraction.

Sulfuric acid is added to the raffinate to deposit calcium, the hydrochloric acid and phosphoric acid obtained after filtration are returned to decompose scheelite, so that the acid can be reused, the cost is reduced, and the gypsum is formed at the same time.

Compared with 1: 1 ~ 1: 3, 1mol / L ~ 2.5mol / L NaOH solution for stripping, after 5min ~ 20min mixed to obtain heteropolyphosphoric acid sodium. After the phase separation, the organic phase is returned to continue extraction.

In the process, sodium tungstate heteropolyacid is obtained by evaporation crystallization. Sodium tungstate heteropolyacid can be used as catalyst, antivirus, anticancer, inorganic ion exchanger, analytical reagent and so on. It is a widely used tungsten chemical product. In addition, extraction can also get gypsum and HCl at the same time, and then filter and separate gypsum. The gypsum has high purity and can be used as mould gypsum. The remaining HCl can be used as a decomposition reagent. The regeneration rate of hydrochloric acid can reach 93.5%. In the whole process, the total loss rate of tungsten is 2.49%, that is, it can generate income and save money.

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