a b s t r a c tVibrational spectroscopy and XPS have been used to investigate the interaction of n-octanohydroxamate with the surfaces of chrysocolla and other oxide copper minerals, as well as with the native oxide on copper metal. XPS investigations of low collector coverage at pH 9.5 confirmed that copper hydroxamate was formed at the mineral/collector interface. Multilayers were formed at all surfaces investigated, probably with minor ($15%) co-adsorption of hydroxamic acid. The coverage at conditioned chrysocolla surfaces tended to be less uniform than coverage at the 'well-defined' oxide minerals. There was also some evidence for the formation of an Al hydroxamate species at the chrysocolla surface.

No abstract

Microplastics (MPs), defined as plastics with diameters between 1 and 5000 µm, are problematic pollutants in the environment, but their removal is challenging because of their minute size. One promising approach for their removal is flotation because MPs are inherently hydrophobic. However, the very small particle size of MPs lowers the probability of MPs-bubble collision and attachment that in turn affects the efficiency of the process. To address this challenge, we propose the use of agglomeration-flotation, a technique using kerosene as a bridging liquid to enlarge the particle sizes of MPs and make them amenable to flotation. In this study, the effects of kerosene dosage on particle size enlargement and floatability of six types of MPs with 100–1000 µm size fractions were investigated. The results showed that MPs with lower density compared with water could easily float in water without bubble attachment and particle agglomeration required. So, the effects of agglomeration on removal were negligible. In contrast, agglomeration using kerosene enhanced the floatability of MPs with high-density plastics. Moreover, image analysis was used to determine the agglomerated MPs’ particle size. The results indicate that kerosene could agglomerate the MPs and enhanced the removal of MPs by agglomeration-flotation.

Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Atomic absorption spectroscopy (AAS) and X-ray Photoelectron spectroscopy (XPS) have been employed to characterise the surface layer and compound formation during the interaction of n-octanohydroxamate with chrysocolla and malachite surfaces. The flotation response of a single mineral chrysocolla -quartz sand sample and mixed chrysocolla -malachite -quartz sand sample using n-octanohydroxamate collector have been investigated. Recoveries of 95% were achieved in bench-scale flotation testing, with the best Cu grades achieved at pH > 9. Long conditioning times adversely affected flotation performance. Moderate recovery of impurity minerals in the mineral and sand was also observed.

White silica sand samples were collected from Steuong Hav district area. The samples were mixed and quartered to obtain a representative sample for physical and chemical characterization. Silica (SiO2) and iron oxide (Fe2O3) content were measured by X-ray fluorescence (XRF) analysis. The results showed silica and iron oxide content at 94.83 wt.% and 0.189 wt.% representatively. In this study, a shaking table, Wet High-Intensity Magnetic Separators (WHIMS), and reverse flotation technique was undertaken to remove mainly iron oxide. The collectors amine (named AOA) and petroleum supinate (named NANZA), pine oil as frother, and H2SO4 as depressant were used to optimize the froth performance. The iron oxide content was removed from 0.189wt.% to 0.062 wt.% and the silica content was upgraded from 94.83 wt.% to 98.6 wt.% after the process.