Method for increasing extraction rate of purification of wet process phosphoric acid

Abstract

The present invention disclose a method for increasing an extraction rate of purification of wet process phosphoric acid. The method comprises steps of: step 1, removing solid substances in the wet process phosphoric acid to obtain a clear liquid, and inputting the clear liquid into four extraction tanks arranged in series to perform extraction, to form an organic phase and a raffinate phase; step 2, performing desulphurization and defluorination treatment on the organic phase, and then performing precipitation and washing, to obtain a purified organic phase; and step 3, inputting the purified organic phase into a stripping column for primary stripping and then into an extraction column for secondary stripping, performing separation to obtain stripping acid and a recycled extractant, and then returning the recycled extractant to step 1 for extraction. According to the above scheme, the purification of wet process phosphoric acid is adjusted by replacing the traditional process of four-tank and one-column five-stage extraction plus one-stage stripping with a process of four-tank four-stage extraction plus two-stage stripping. Therefore, the extraction rate is increased by 10% or more without structurally changing the extraction column or adding a new device, thereby dramatically reducing production costs; and the process is very simple and the effect is very significant.

Description

technical field [0001] The invention relates to a method for purifying wet-process phosphoric acid, in particular to a method for improving the purification and extraction rate of wet-process phosphoric acid. Background technique [0002] Chinese patent 200710092904.1 discloses a method for preparing purified phosphoric acid from wet-process phosphoric acid. Its scheme is extracted with high-concentration wet-process phosphoric acid through four tanks, one tower and five stages by solvent method, after desulfurization, defluorination, washing, and stripping, 46-48% of phosphorus pentoxide is extracted and used to manufacture industrial phosphoric acid, and the remaining 52-54% of phosphorus pentoxide is sent to the ammonium phosphate plant in the form of raffinate to produce low-concentration slurry method monoammonium phosphate; since the available phosphorus utilization rate of the obtained industrial phosphoric acid is only 46-48%, the extraction efficiency Lower and hig...

AI Technical Summary

Problems solved by technology

Its scheme is extracted with high-concentration wet-process phosphoric acid through four tanks, one tower and five stages by solvent method, after desulfurization, defluorination, washing, and stripping, 46-48% of phosphorus pentoxide is extracted and used to manufacture industrial phosphoric acid, and the remaining 52-54% of phosphorus pentoxide is sent to the ammonium phosphate plant in the form of raffinate to produce low-concentration slurry method monoammonium phosphate; since the available phosphorus utilization rate of the obtained industrial phosphoric acid is only 46-48%, the extraction efficiency lower production cost

In addition, the extraction tower in the scheme is a low-concentration extraction, and the trays are prone to scaling due to impurities precipitated in wet-process phosphoric acid, which will block the tray holes and increase the load on the tower vibration equipment, resulting in equipment failure and increased energy consumption.

Therefore need to improve the extraction rate (being P 2 o 5 Yield); in order to improve the extraction rate, those skilled in the art can easily think of directly increasing the number of extraction stages and setting more extraction tanks or extraction towers, but this will significantly increase the cost, and it is necessary to modify and adjust the existing equipment