Selective copper extraction from sulfate media with N,N-dihexyl-N′-hydroxypyridine-carboximidamides as extractants

Solvent extraction studies of copper(II) from sulfate media have been carried out using a selected non-commercial extractant N,N-dihexyl-N′-hydroxypyridine-2-carboximidamide (DH2PIA) diluted with toluene and heptane. The presented results indicated that the extraction of copper(II) was very sensitive to the pHeq, extractant concentration and the type of diluent. Also the pH0.5 values depended on the type of diluent and varied from 2 for heptane to 2.8 for toluene. The isotherms of the extraction and the McCabe-Thiele diagram revealed that using the single stage extraction at O/A = 2 Cu(II) can be removed almost completely from the leach solution. Stripping of the loaded copper(II) to the sulfuric acid solution (10%, A/O = 10) yielded rich electrolyte with 37.7 g/L Cu(II), while the stripping test with the spent electrolyte allowed for enrichment of the solution to 67.6 g/L Cu(II). Moreover, the extraction of Cu(II) with DH2PIA from a leach solution containing also Fe(II) is selective and allows to enrich the organic phase in Cu(II).