Study on the stripping of the extractant from the production of industrial-grade ammonium dihydrogen phosphate solution by solvent extraction

In this paper,the effective D2EHPA is empolyed as extractant.Based on the extractant of D2EHPA,The abilities to extract Mg2+ from ammonium dihydrogen phosphate solution with the separation methods of extraction,emulisification extraction,saponified D2EHPA,and predispersed solvent extraction have been studied.And superior grade NH4H2PO4(MAP) can be obtained by two levels of extraction under optimal condition.However one of difficulties to realize industrialization is the choice of strippant.The key for selection of strippant is to realize the complex D2EHPA-Fe3+ effective separation,because complex D2EHPA-Fe3+ is very stable,moreover concentration of Fe3+ can cause the extractant aging.Therefore the choice of the effective strippant to realize the extractant D2EHPA recycling use is necessary. In the stripping of Mg2+/Fe3+ in the organic phase,H2SO4+ additive A is used to strip Fe3+.to study the stripping extraction ratio and advantages of the strippant H2SO4 in the removal of Fe3+,various parameters: concentraction of H2SO4,reaction temperature,phase mass ratio,stirring speed,stirring time are studied and optimized.The optimized parameters affecting the process are as follows: The concentraction of H2SO4: 4mol·L-1;the reaction temperature: 45℃;the phase volume ratio: 1∶1;stirring speed: 550r·min-1,stirring time: 0.5h.