At present, the purification technologies of WPA include extraction, crystallization, electrodialysis, ion exchange and adsorption. Among them, the purification process of wet process phosphoric acid by solvent extraction can be continuously produced.
The solvent extractant has good separation effect on phosphoric acid and impurity ions, good purification effect and high product purity, which is the most widely purification technology for wet process phosphoric acid.
The purification of WPA by solvent extraction is based on the fact that phosphoric acid is soluble in organic solvent, while impurities have low solubility in organic solvent. Most impurities are left in the water phase by the extraction process, while phosphoric acid is enriched in the organic phase. After extraction, the organic phase is separated, and the purified phosphoric acid with a mass fraction of>75% is finally obtained through water washing, stripping, distillation and concentration.
Although the solvent extraction method has significant purification effect on WPA, it is the main means to remove metal ions. However, there are still some problems for improvement: for example, there is a certain solvent loss in the extraction process, the process is complex, the cost is high, the extraction rate and the utilization rate of extracted acid need to be improved, phosphoric acid is highly corrosive to equipment, and the direct discharge of phosphorus containing extractants such as tributyl phosphate will cause certain pollution to the environment
① Select new composite extractants, reduce the amount of extractants, improve the extraction rate, and improve the product quality;
② Develop new extraction equipment, increase the interface area between water phase and oil phase, improve the mass transfer rate, and improve the extraction rate; Simplify and improve the process route, reduce investment and operation costs; Wrap or lining PVDF and other protective layers on key equipment or key parts of equipment to prevent equipment from corrosion
③ Develop a new way to utilize the raffinate acid and improve the utilization rate of phosphoric acid
CWL-M Centrifugal Extractor Advantage
01 Simple and stable structure
Adopted upper suspension single structure , no leakage risk with no bottom bearing and mechanical seal.
02 Energy saving
03 Corrosion resistance
04 Good mixing and separation effect
05The heavy phase weir plate is easy to replace
06The equipment has a small liquid storage
07High degree of automation