The flotation of low-grade manganese ore using a novel linoleate hydroxamic acid

•LHA was investigated as a new collector for rhodochrosite flotation.•The selectivity of LHA is better than that of the traditional collector oleate acid.•We investigated key factors in flotation and the optimum values were obtained.•Chemisorption is the major adsorption mechanism in the flotation.

We designed and synthesized a novel linoleate hydroxamic acid (LHA) which demonstrated high selectivity and strong collecting capacity for the beneficiation of manganese ore by selective flotation. The performance of this LHA and oleic acid (OA) used for anionic froth flotation was compared, and the critical factors of rhodochrosite flotation were investigated. It demonstrated that the use of sodium carbonate instead of sodium hydroxide as the pH regulator, dosages of depressant and collector, and the addition of synergist are essential to the effective recovery of Mn in the flotation. And the concentrate grade of 18.3% Mn had been produced from a feed mixture with 10.7% Mn, and the Mn recovery could be achieved as highly as 97% when the LHA was used for the flotation separation of rhodochrosite under the optimum operating conditions. It was found that compared to OA, the novel LHA achieved superior results. Moreover, the analyses of Zeta-potential, Fourier Transform Infrared Spectroscopy (FT-IR), and X-ray diffraction (XRD) indicated that chemisorption accounted for the flotation mechanism. Besides, results of the Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) revealed that the concentrate obtained had significantly higher proportion of manganese-bearing grains (e.g., rhodochrosite and pyrolusite) relative to the tail and implied that Mn-LHA compounds or chelates might be produced through the interaction between the rhodochrosite and LHA.

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