Abstract:

To address the high demands of global energy transition on lithium-ion battery materials and resolve the issues of high energy consumption and pollution in traditional thermal-process phosphoric acid routes，as well as the high impurity levels in wet-process phosphoric acid routes，a novel process for producing battery-grade ammonium dihydrogen phosphate（MAP） based on wet-process phosphoric acid purification was developed.Through innovative multi-stage purification technologies，including chemical precipitation-extraction-membrane separation coupling，low-temperature premixing for arsenic removal，graded utilization of thermal energy，and the combined use of DTB crystallizers and crystal destroyers，deep purification and efficient utilization of wet-process phosphoric acid were achieved.The results demonstrated that the prepared product surpassed the specifications of the（HG/T 5742—2020）“Ammonium dihydrogen phosphate for battery materials” standard，with a purity of up to 99.8%，moisture content as low as 0.02%，and sulfur compounds，fluorides，arsenic，and iron content was reduced to 36.14，3.15，1.15，and 5.23 mg/kg，respectively.Compared to thermal-process routes，the raw material cost，energy consumption cost and investment intensity were reduced by 61.3%，75.3%，40.7%，respectively and environmental treatment costs were significantly decreased.The developed process was successfully validated in a 100 000 t/a industrial-scale facility，demonstrating notable technical and economic advantages.It provided crucial technical support for the green upgrading of the wet-process phosphoric acid industry chain with broad prospects for industry-wide adoption.

Key words: wet-process phosphoric acid, ammonium dihydrogen phosphate, battery-grade, multi-stage purification