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In this work, a complete beneficiation technical route combining physical and chemical methods, namely a roasting-flotation-leaching scheme, is proposed to produce a qualified grade Ti-concentrate from altered Vanadium titanomagnetite (VTM) ore. Based on the character of the ore sample, it is recommended to recover the Ti-bearing minerals, ilmenite and anatase, as composite mineral. Pretreatment experiments indicate that the oxidation roasting (800 °C) and acid washing methods increase the flotation indexes significantly. Flotation condition tests show that the optimal conditions are a grinding fineness of −0.045 mm 83%, sulfuric acid dosage of 2000 g/t, water glass dosage of 1500 g/t, oxalic acid dosage of 200 g/t, and EM328 dosage of 1500 g/t. An open flotation circuit test obtains a flotation concentrate with a TiO2 grade and recovery of 38.30% and 25.99%, respectively. A leaching exploration test shows that the TiO2 grade of the flotation concentrate can be improved to 53.90%. XRD analyses reveal that the ilmenite in the VTM ore is converted into anatase and rutile during the roasting process at 600–800 °C, but pseudobrookite begins to form at 900 °C. Compared to the flotation concentrate, it is confirmed that the content of Ti-bearing minerals is increased significantly in the leaching residue. [ABSTRACT FROM AUTHOR]

[Display omitted] • OPLS-DA effectively distinguishes between gold-bearing and barren rocks using spectral bands of sericite. • LSTM models accurately predict high-grade gold samples using sericite spectral data. • Machine learning and SWIR spectral data as a novel approach to uncover lode gold mineralization. The Jiaodong Peninsula in the eastern North China Craton is renowned globally as a major gold province. Notably, the Jiaojia orefield is an important gold-producing district in this region, and its depths are inferred to offer substantial prospecting potential, underscoring the need for innovative exploration tools to uncover concealed orebodies. The Qianchen gold deposit in the southern part of the Jiaojia orefield is characterized by the disseminated-stockwork-style orebodies at depths of ca. –1000 to –1800 m, with three mineralization stages, namely (I) pre-ore K-feldspar-quartz stage, (II) quartz-sericite-gold-polymetallic sulfide stage (main Au mineralization stage), and (III) post-ore quartz-calcite stage. Systematic short-wavelength infrared (SWIR) spectral analysis reveals that sericite group minerals developing in Stage II are the predominant and wide-distributed alteration minerals at Qianchen. Their spectral characteristics demonstrate a shift in the Al-OH absorption feature wavelength positions (Pos2200) to longer wavelengths (>2205 nm) within the orebodies. This shift is likely due to strong water–rock interactions leading to Fe and Mg substituting for Al in octahedral sites. Orthogonal partial least squares discriminant analysis (OPLS-DA) indicates that the H 2 O, OH, and FeOH spectral bands (Variable Importance in the Projection (VIP) ≥ 1) of sericite are crucial for distinguishing between gold ores and barren wall rocks. Additionally, Long Short-Term Memory (LSTM) models demonstrate that spectral data of sericite can be used to predict ore samples with an accuracy of 82 %, validated by receiver operating characteristic analysis (84 %), and blind test results demonstrate that the predicted grade closely aligns with the actual grade. Therefore, it is concluded that SWIR spectral characteristics of sericite group minerals can serve as an effective indicator for prospecting the Qianchen concealed gold mineralization. This study highlights the potential of coupling between machine learning and SWIR spectral data of alteration minerals to uncover the concealed lode gold mineralization. [ABSTRACT FROM AUTHOR]

• Dissolved calcite inhibits bastnaesite flotation by NaOL at high pH. • Calcite supernatant has a stronger effect than calcium or carbonate alone. • Calcium forms hydroxy complex and precipitate to hinder adsorption of NaOL. • Some NaOL in the solution is also converted to calcium oleate precipitate. The flotation behavior of bastnaesite, a major mineral source of rare earth elements, is strongly affected by the dissolved species of gangue minerals that change the solution chemistry and mineral surface properties. In this work, the effect of dissolved calcite species on the flotation of bastnaesite was investigated by conducting micro-flotation experiments, zeta potential measurements, Fourier-transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) analysis. Micro-flotation experiments confirmed that calcium and carbonate ions in calcite supernatant significantly reduced the flotation of bastnaesite in strongly alkaline condition. Zeta potential measurements showed that the IEP of higher bastnaesite was obtained after the addition of calcite supernatant species. Species distribution diagram demonstrated that the adsorption of sodium oleate on the surface species of bastnaesite was inhibited by the generation of calcium-containing hydroxy complexes and precipitates. FT-IR analysis suggested that the decrease the sodium oleate concentration in solution and the generation of calcium oleate precipitate on the mineral surface are possible reasons for the reduced recovery. XPS analysis further revealed that the metal carbonates and hydroxy complexes of calcium adsorbed on the bastnaesite surface in the presence of calcite supernatant, which concealed the surface active sites, caused the decrease in bastnaesite flotation recovery. [ABSTRACT FROM AUTHOR]

Focusing on salt-type and oxide minerals, this paper reviews the research on anisotropic surface chemistry properties, including broken bonds, surface energy, wettability, and surface charge. Moreover, based on the analysis of anisotropic surface properties, the anisotropic adsorption behaviour of reagents on mineral surfaces is also reviewed. The research on anisotropic surface chemistry is instructive to understand some of the properties of the minerals themselves and the reactions in which minerals participate. In addition, the investigation on the anisotropic adsorption behaviour of reagent molecules on mineral surfaces will definitely strengthen the understanding of the efficiency of the interactions. In general, with the knowledge of mineral anisotropy, the relationship between the selective pre-treatment of a mineral and the efficient adsorption of reagent molecules on mineral surfaces will be established. [ABSTRACT FROM AUTHOR]

• Ultrasound treatment improves separation of ilmenite from titanaugite & olivine. • Treatment condition for maximum difference in floatability was identified. • Effect of ultrasound on different minerals is due to change in mineral dissolution. • Ultrasound converts Fe(II) to Fe(III) and promotes dissolution of Ca and Mg. • Fe(OH) 3 precipitate on ilmenite enhances collector adsorption in floatation. Selective separation of ilmenite from gangue minerals after ultrasonic preconditioning was studied in terms of surface dissolution. After preconditioning, ilmenite exhibited better single-mineral flotation capacity while titanaugite and olivine had lower recoveries. Significant separation could be obtained at pH 6.0 after ultrasonic treatment (500 W, 5 min). Zeta potentials of preconditioned titanaugite and olivine shifted positively compared to those of raw titanaugite and olivine treated with sodium oleate (NaOL), respectively. Meanwhile, the zeta potential of ilmenite was similar before and after NaOL adsorption. Mineral dissolution results indicate that ultrasonic preconditioning promotes the dissolution of Mg and Fe species but not the Ca species. The dissolution of Ca and Mg is much higher than that of Fe. According to solution chemistry calculation, Fe(OH) 3 precipitate is dominant at pH greater than 2.5, and Ca2+, Mg2+, Fe2+, and Fe(OH)+ are dominant under acidic conditions. Microcalorimetric measurements demonstrate that the preconditioned ilmenite releases more heat during NaOL adsorption than titanaugite and olivine do. XPS results reveal that ultrasonic treatment facilitates the conversion of Fe2+ to Fe3+. After preconditioning, Fe species interacted with NaOL to promote the latter's chemisorption on ilmenite and olivine, while Ca2+ was more likely to interact with NaOL on titanaugite. [ABSTRACT FROM AUTHOR]