Extraction of H3PO4 from low-grade phosphate rocks leachate of HCl-route by the mixture of TBP and IPE: Optimization, mass transfer and mechanism

•The mixed solvent of TBP and IPE was first used to extract H3PO4 from the leachate of HCl and low-grade phosphate rocks.•The relation of total extraction percent and cross-flow extraction stages for all tested components were summarized.•The mass transfer of H3PO4 extraction was studied in our work.•The mechanism of H3PO4 extraction was discussed.