APT Crystallization Liquor Treatment -- Artificial Scheelite Method
The crystalization method of evaporation and extraction method in the preparation of APT will produce crystallization liquor, leaving about 5% -10% of the WO3 and part of the S, P, As, Mo, K, Na and other impurities.
It resulting in it can not directly return to the process, in order to improve the recycle of metal, it is necessary to set up auxiliary processes to recycle WO3 in the liquor.
Artificial scheelite was the method of ammonium paratungstate crystallization liquor treatment, the main precipitant is CaCl2, the main purpose of the artificial scheelite method is to convert the WO3 in the crystallization liquor into a very insoluble calcium tungstate (artificial scheelite), then return to the acid process or hot ball milling process.
Artificial scheelite made in three directions: 1. CaCl2 precipitated artificial scheelite → acid decomposition and partial molybdenum → crude tungstic acid → return to the main process; 2. Remove the molybdenum → precipitated artificial scheelite → return to hot ball grinding alkali decomposition; Recrystallized and remediation of artificial scheelite.
Artificial scheelite method is the traditional method of recycling APT crystallization liquor, its advantages are simple, and more selective. But also has a lot of shortcomings, mainly reflect in: 1. Scheelite precipitation rate is low, the gradual addition of CaCl2 resulted in an increase in the acidity of the crystallization liquor. For the synthesis of pH degree, it generally add calcium chloride before adding some of the alkali to the liquor, to ensure a certain degree of alkalinity, which in turn increase the consumption of alkali. 2. The waste liquid has high impurity elements, especially ammonia nitrogen, which is far beyond the national emission standard, it’s not conducive to clean production, it has to re-manage before the emission. 3. Consumption is on the high side, artificial scheelite from the synthesis to return to the alkali decomposition process to do raw materials, need to re-consumption of raw and auxiliary materials, the more synthesis, the higher the consumption.
To sum up, artificial scheelite method played a certain historical role, but has failed to keep pace with the production requirement of modern industry, so it belong to the brink of elimination of backward technology.
If you have any inquiry of tungsten oxide, please feel free to contact us:
Tel.: +86 592 5129696 +86 592 5129595
Fax: +86 592 5129797
评论
发表评论