Application of Dynamic Vapor Sorption for evaluation of hydrophobicity in industrial-scale froth flotation

• Published in: Minerals engineering 2018-10, Vol.127, p.305-311
• Main Authors: Malm, Lisa, Danielsson, Ann-Sofi Kindstedt, Sand, Anders, Rosenkranz, Jan, Ymén, Ingvar
• Format: Article
• Language: English
• Subjects: Binary alloys; Capillary absorption; Capillary flow; Dichromate; Dynamic Vapor Sorption; Flotation reagents; Froth flotation; Hydrophilicity; Hydrophobicity; Industrial scale; Measurement methods; Mineral industry; Mineral Processing; Mineralteknik; Ore treatment; Pharmaceutical industry; Repeated measurements; Screening; Sorption; Surface properties
• ISSN: 0892-6875; 1872-9444; 1872-9444
• DOI: 10.1016/j.mineng.2017.11.004

•A new technic proposed for measuring the hydrophobicity of mineral samples.•The method based on Dynamic Vapor Sorption, DVS.•Measurements carried out on samples from industrial scale Cu-Pb flotation circuits.•Showed viable for measuring differences in water uptake with high reproducibility.•Also useful for evaluating the effects of different flotation chemicals. The particle surface properties are essential for understanding froth flotation, particularly for the evaluation of various chemical or reagent effects. Dynamic Vapor Sorption (DVS) is used in the pharmaceutical industry for the evaluation of surface properties and has to the knowledge of the authors not been used for applications in mineral processing. This paper describes an evaluation of industrial ore samples using DVS. Four samples (feed, CuPb concentrate, Cu concentrate and Pb concentrate) from each of the Cu – Pb flotation processes in the Boliden and Garpenberg concentrators, Sweden, were analyzed by DVS in order to investigate if this technique could be used to estimate differences in their hydrophilicity. The DVS measures the water uptake as a function of the relative humidity (%RH) at constant temperature. For both series of four samples, it was found that the DVS-data are in precise agreement with the flotation theory on hydrophobicity (indicated by differences in water uptake). The feed material, without any collectors, adsorbed more water compared to the CuPb bulk concentrate, which in turn adsorbed more water than the Cu concentrate. The lead concentrate on the other hand, which had been depressed by dichromate and should be more hydrophilic, showed a higher adsorbance of water than that of the CuPb concentrate. The repeated measurements of three sub samples from one of the ore samples gave a mean value and an estimated standard deviation of 0.13 ± 0.01%. This shows that the method gives highly reproducible results and that the differences between the samples had high significance. This also shows that the DVS method can serve as a useful complement to traditionally used contact angle or capillary absorption-based measurement methods, especially when screening for new flotation reagents on industrial ore samples.