Purification of wet process phosphoric acid by solvent extraction with methyl isobutyl ketone: Systematic study of impurity distribution

This paper reports a study on the purification behavior of methyl isobutyl ketone (MIBK) for the major impurities of the phosphoric acid wet process ( Ca2+, Mg2+, Al3+, Fe3+, SO42-, and F-). Distribution coefficients of phosph oric acid (PA) and impurities, as well as selectivity of MIBK for PA, have been studied as a function of the PA concentration (wt%) in the organic pha se. Our results are compared to those obtained with other solvents (isoamyl alcohol, dibutyl ether, and dipropyl ether) described in the literature. M IBK seems to have the best selectivity far PA against SO42-, and it shows a n intermediate behavior between those of isomyl alcohol and ethers with reg ard to metallic impurities.