Structural Modification of Natural Depressant Sesbania Gum for Enhanced Selective Separation of Ilmenite from Forsterite

Authors:
  • YYYang Yang
    Yang Yang
  • MCMengyao Chen
    Mengyao Chen
  • SLShijie Li
    Shijie Li
  • YLYan Long
    Yan Long
  • YCYijun Cao
    Yijun Cao
  • FZFanfan Zhang
    Fanfan Zhang
  • LSLiang Si
    Liang Si
  • SRShi Ruxing
    Shi Ruxing
  • GFGuixia Fan
    Guixia Fan
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Abstract
The similar surface physicochemical properties of ilmenite and forsterite make their selective flotation separation challenging. In this study, carboxymethyl sesbania gum (CMSG), a carboxymethylated derivative of sesbania gum (SG), was developed as a selective depressant for forsterite. At a CMSG dosage of 10 mg/L, single-mineral flotation tests achieved an 81.52% recovery difference between ilmenite and forsterite, 32.56% higher than that with SG. In artificial mixture flotation, CMSG maintained a comparable TiO2 recovery while increasing the TiO2 grade of the concentrate by 9.17% compared with SG. Multiscale characterization revealed that CMSG preferentially adsorbed onto the forsterite surface through chemisorption involving active Mg sites, forming a stable hydrophilic layer that reduced surface hydrophobicity and inhibited subsequent collector adsorption. In contrast, CMSG interacted with ilmenite primarily through weak physisorption, resulting in a limited effect on collector adsorption. Molecular dynamics simulations further revealed that the interaction energy of CMSG with ilmenite and forsterite reached -1568.31 and -4388.75 kJ/mol, respectively, confirming the substantially stronger interfacial interaction and more stable adsorption of CMSG on forsterite. This differential adsorption behavior enables selective depression of forsterite and efficient flotation separation of ilmenite, demonstrating the potential of structurally modified sesbania gum as a bio-based selective depressant.

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