Method for Improving Purification and Extraction Rate of Phosphoric Acid in Wet Process

Abstract

The invention discloses a method for improving the purification and extraction rate of wet-process phosphoric acid, which comprises the steps of removing solids in wet-process phosphoric acid to obtain a clear liquid, and connecting the clear liquid to four sequentially connected extraction tanks for extraction to form an organic phase and the raffinate phase; step 2, take the organic phase for desulfurization and defluorination treatment, and then settle and wash to obtain a purified organic phase; step 3, first connect the purified organic phase to a stripping tower for primary reaction Extraction, and then connected to the extraction tower for secondary stripping, separated to obtain stripping acid and reused extractant, and the reused extractant is returned to the first step for extraction. Using the above scheme, the purification process of wet-process phosphoric acid is adjusted, and the traditional four-tank, one-tower, five-stage extraction and one-stage stripping are adjusted to four-tank, four-stage extraction and two-stage stripping; no need to change the structure of the extraction tower, and the In the case of adding new equipment, the extraction rate is increased by more than 10%, thereby greatly reducing the production cost, the process is very simple, and the effect is very remarkable.

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