Clean and short flowsheet of recovering ultrafine ilmenite by high gradient magnetic separation coupling with magnetic fluid

•Efficient separation of ultrafine ilmenite was obtained by optimizing HGMSCMF.•Analyses of ratio of captured ilmenite numbers corresponded well with experiments.•HGMSCMF presented good adaptability to mineral particle size.•A cleaner and short flowsheet of recovering ultrafine ilmenite was proposed. Ultrafine ilmenite minerals (−0.019 mm) in vanadic titanomagnetite ore deposit in Panxi area of China were generally separated by hydraulic classification and discharged into tailings as these fine minerals will severely deteriorate subsequent flotation process, resulting in a great waste of titanium resources. Methods combining high gradient magnetic separation (HGMS) followed by flotation were usually developed for recovering ultrafine ilmenite, which commonly had defects of long flowsheet, high reagent consumption and environmental pollution. In this study, high gradient magnetic separation coupling with magnetic fluid (HGMSCMF) was adopted to recover ultrafine ilmenite in Panxi area. Effect of MnCl2 concentration (magnetic susceptibility of fluid), applied induction and pulsating frequency on TiO2 grade and recovery of magnetic products in HGMSCMF were systematically investigated. Under optimal conditions of MnCl2 concentration 40 %, applied induction 0.8 T and pulsating frequency 300 r/min, magnetic concentrate assaying 46.09 % TiO2 could be obtained under TiO2 recovery of 43.58 % through three stages of HGMSCMF. Numerical simulation of capture of ilmenite and titanaugite particles by matrices were conducted, based on which variation of ratio of captured ilmenite particles with MnCl2 concentration and applied induction were studied. Theoretical results corresponded well with experimental results and indicated good adaptability of HGMSCMF to mineral particle size. A clean and short flowsheet incorporating recycling of magnetic fluids for continuous recovery of ultrafine ilmenite was developed. HGMSCMF presented great superiority and application prospect in cleaner and efficient utilization of ultrafine ilmenite, as well as other refractory weakly magnetic minerals.