Surface modification of ilmenite by introducing copper-ammonia ion and its response to flotation in H2SO4-H2O2 system

Abstract The efficient recovery of micro-fine particle ilmenite using froth flotation remains a challenge. In this study, a novel method for the activation flotation of micro-fine particle ilmenite was performed. Micro-flotation experiments, solution chemistry, X-ray photoelectron spectroscopy, reaction thermodynamic and Time-of-flight secondary ion mass spectrometry analysis were conducted to investigate the activation mechanism. The results indicated that the flotation recovery was increased by ~ 18% with the addition of H2SO4-H2O2 and [Cu(NH3)4]2+ ions at pH value 5.5 using sodium oleate. The dominant RCOOH (l) species and RCOO− ions could interact with Fe and Cu active sites on ilmenite surfaces via chemical adsorption. The treatment of H2SO4-H2O2 promoted the valence transition of iron from Fe (II) to Fe (III). Eventually, the proportion of Fe (III) increased from 44% to 66%. This activity reinforced the formation of Fe(OL)3 complex under a low-acidic condition and it was well consist with the corresponding results of reaction thermodynamic. [Cu(NH3)4]2+ ions adsorbed onto ilmenite surfaces and further improved the surface activity of ilmenite. Accordingly, the normalized peak intensities of C18H33O2− increased from 1.42 × 10−2 to 1.80 × 10−2. Insights into copper-ammonia ions activation for the micro-fine particle ilmenite was mainly attributed to the dual oxidization of H2SO4 and H2O2, as well as the enhanced adsorptions of molecule/colloid oleate and oleate compounds of Fe and Cu. Results enriched basic theories of ilmenite flotation.