Method for producing diammonium phosphate by using extract spent acid resulted from phosphoric acid purification

Abstract

The invention relates to a method for producing diammonium phosphate by using extract spent acid resulted from phosphoric acid purification. The method comprises the following steps: adding a modified frequency modulator on an extract spent acid conveying pump and ensuring the conveying amount of the extract spent acid to be constant; mixing the extract spent acid with common raw material phosphoric acid, and causing the content of sesquioxide in the complex acid to be lower than 3 percent; adding surfactant in the complex acid to increase the fluidity and the surface activity of a reaction slurry and reduce the viscosity of the reaction slurry; and according to a conventional method, using ammonia to neutralize the complex acid so as to obtain the diammonium phosphate. The method is a precedent in realizing the recovery of high-content impurity acid and the production of fine-quality diammonium phosphate products meeting national standards, when compared with a conventional process. The procedures in the method are unhindered, thereby being favorable for reasonably utilizing the phosphorus resource and conforming to the requirement of recycling economy. The method is suitable for enterprises producing the diammonium phosphate of purified phosphoric acid by using extracting agent.

Description

technical field [0001] The present invention relates to phosphoric acid, also relates to diammonium phosphate, specifically, relates to the method for producing diammonium phosphate with the raffinate acid of purifying phosphoric acid. Background technique [0002] A production method for purifying phosphoric acid is to extract phosphoric acid from wet-process phosphoric acid with an extractant to obtain purified phosphoric acid; in production, the acid remaining after extraction is called raffinate. Its main components are as follows: P 2 o 5 ≥42%, Ca≤0.04%, Fe 3+ ≤0.44%, Al≤0.17%, Mg≤1.49%, F≤0.23%, Cl≤0.016%, K≤0.1%, Na≤0.23%, SiO 2 ≤0.06%, Cu≤5.1×10 -6 , and other metal ions. For a long time, the recovery and utilization of raffinate has been a technical problem. Some manufacturers have successively tried to produce powdered monoammonium and granular monoammonium, but the production was unsuccessful. During the production process, the following problems were found...

AI Technical Summary

Problems solved by technology

During the production process, the following problems were found: the viscosity of the system material slurry increased, and the pipes were easy to block and scale; the crushing and screening system was easy to scar, and the nozzle was easy to block; High; the number of system shutdowns increased significantly, and the N content of the product was much lower than that produced without raffinic acid, and the test failed

[0003] After searching, no patent has been found on the use of raffinate to produce diammonium phosphate