Study on the Effect of Fe3+ on Zircon Flotation Separation from Cassiterite Using Sodium Oleate as Collector

Enhanced oxygen evolution performance by partial phase transformation of cobalt/nickel carbonate hydroxide nanosheet arrays in Fe-containing alkaline electrolyte

Herein, we employ a partial phase conversion strategy to transform cobalt/nickel carbonate hydroxide (CoxNiyCH) nanosheet arrays in Fe-containing KOH electrolyte. The optimized sample exhibits a remarkable electrocatalytic activity (η50 =...

The pH dependent surface charging and points of zero charge. IX. Update

of the points of zero charge (PZC) and isoelectric points (IEP) of various materials published in the recent literature and of older results overlooked in the previous compilations. The roles of experimental conditions, especially of the temperature, of the nature and concentration of supporting electrolyte, and of the type of apparatus are emphasized. The newest results are compared with the zero points reported in previous reviews. Most recent studies were carried out with materials whose pH dependent surface charging is already well-documented, and the newest results are consistent with the older literature. Isoelectric points of Gd(OH)₃, Sm(OH)₃, and TeO₂ have been reported for the first time in the recent literature.

Surface Mechanism of Fe3+ Ions on the Improvement of Fine Monazite Flotation With Octyl Hydroxamate as the Collector

Froth flotation of fine minerals has always been an important research direction in terms of theory and practice. In this paper, the effect and mechanism of Fe³⁺ on improving surface hydrophobicity and flotation of fine monazite using sodium octyl hydroxamate (SOH) as a collector were investigated through a series of laboratory tests and detection measurements including microflotation, fluorescence spectrum, zeta potential, and X-ray photoelectron spectroscopy (XPS). Flotation tests have shown that fine monazite particles (−26 + 15 μm) cannot be floated well with the SOH collector compared to the coarse fraction (−74 + 38 μm). However, adding a small amount of Fe³⁺ to the pulp before SOH can significantly improve the flotation of fine monazite. This is because the addition of Fe³⁺ promotes the adsorption of SOH and greatly improves the hydrophobicity of the monazite surface. This can result in the formation of a more uniform and dense hydrophobic adsorption layer, as shown by the fluorescence spectrum and zeta potential results. From the XPS results, Fe³⁺ reacts with surface O atoms on the surface of monazite to form a monazite–O_surf–Fe group that acts as a new additional active site for SOH adsorption. A schematic model was also proposed to explain the mechanism of Fe³⁺ for improving surface hydrophobicity and flotation of fine monazite using octyl hydroxamate as a collector. The innovative point of this study is using a simple reagent scheme to float fine mineral particles rather than traditional complex processes.

Effects of Hydration on the Adsorption of Benzohydroxamic Acid on the Lead-Ion-Activated Cassiterite Surface: A DFT Study

The strategy of enhancing the surface activity by preadsorption of metal ions (surface activation) is an effective way to promote the adsorption of surfactant on surfaces, which is very important in surface process engineering. However, the adsorption mechanism of surfactant (collector) on the surface preadsorbed by metal ions in the explicit solution phase is still poorly understood. Herein, the effects of hydration on the adsorption of benzohydroxamic acid (BHA) onto the oxide mineral surface before and after lead-ion activation are investigated by first-principles calculations, owing to its importance in the field of flotation. The results show that the direct adsorption of BHA on the hydrated surface is not thermodynamically allowed in the absence of metal ions. However, the adsorption of BHA onto the lead-ion-activated surface possesses a very low barrier and a very negative reaction energy difference, indicating that the adsorption of BHA on hydrated Pb²⁺ at cassiterite surface is very favorable in both thermodynamics and kinetics. In addition, the adsorption of BHA results in the dehydration of hydrated Pb²⁺. More interestingly, the surface hydroxyl groups could participate in and may promote the coordination adsorption through proton transfer. This work sheds some new lights on understanding the roles of interfacial water and the mechanisms of metal-ion surface activation.

A review of reagents applied to rare-earth mineral flotation

The rare-earth elements (REE), which encompass the fifteen metallic elements of the lanthanoid series of the periodic table, yttrium and occasionally scandium, have gained enormous public, economic and scientific attention in recent years. These elements, which have been found in over 250 minerals, are of high economic and strategic importance to many high-technology industries. As such they have been designated as critical materials by several countries and many new deposits are being developed. Rare-earth mineral (REM) deposits can be broadly classified into four geological environments: carbonates, alkaline/peralkaline igneous rocks, placers and ion adsorption clays. Apart from ion adsorption clay deposits, which require no mineral processing steps, froth flotation is the most applied beneficiation technique. This paper reviews the flotation of REM, covering their surface chemical properties as well as the various flotation reagents which have been employed.

A Study on the Flocculation and Sedimentation of Iron Tailings Slurry Based on the Regulating Behavior of Fe3+

Based on the regulating behavior of Fe3+, flocculation and sedimentation tests of iron tailings slurry flocculated using 2 mg/L anionic polyacrylamide (APAM) were studied, including the tests of Fe3+ dosage, regulating time, and pH. Flocculation–sedimentation tests showed that: a recommended addition of 56 mg/L Fe3+ produced a surprisingly bad flocculation effect; sedimentation ability decreased with the increase of regulating time, however, the regulating ability during the first 1 min was low; Fe3+ displayed a high regulating effect at pH 6–7, and then decreased with the increase of slurry pH. Size analysis demonstrated that the regulating ability of Fe3+ was related to the change of floc size, which increased with the decrease of size. Zeta potential analysis and calculation showed that small concentrations of Fe3+ and certain hydroxyl complex ions (such as Fe(OH)2+ and Fe(OH)2+) adsorbed onto the APAM molecular chains, resulting in a decreased charge density of the APAM molecules, and this electrostatic adsorption was able to make the polymer curl more easily. Fourier Transform Infrared Spectroscopic (FTIR) indicated the APAM on the hematite was slightly degraded into a monomer-like short-chain polymer while adding certain concentration of Fe3+. Scanning Electron Microscope (SEM) imaging showed that the network structure of APAM molecules treated by Fe3+ collapsed, and the APAM adsorption amount on hematite was significantly reduced. Therefore, the effect of Fe3+ on the APAM could be recommended as a new method for desorption and degradation of the APAM contained in the tailings slurry or flocs.

Inhibition mechanism of Ca2+, Mg2+ and Fe3+ in fine cassiterite flotation using octanohydroxamic acid

The existence of metal ions should not be ignored in both hydrometallurgy and flotation. In this study, the effects of Ca²⁺, Mg²⁺ and Fe³⁺ on the flotation performance of cassiterite using octanohydroxamic acid (OHA) as the collector were investigated by micro-flotation tests, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, contact angle, zeta (ζ) potential measurements and atomic force microscopy (AFM) imaging. The results of the flotation and contact angle experiments showed that the addition of Ca²⁺, Mg²⁺ and Fe³⁺ significantly decreased both the recovery and contact angle of cassiterite with pH ranged from 6.0 to 12.0 in the presence of OHA collector. ζ-Potential measurements, solution chemistry analysis and FTIR measurements indicated that the flotation recovery of the cassiterite declined due to the CaOH⁺, MgOH⁺ and Fe(OH)₃ sites on the cassiterite surface. XPS results indicated that the chemisorption of OHA and calcium ions on the cassiterite surface finally changed its chemical properties. The AFM images also revealed that new species Fe(OH)₃ of Fe³⁺ formed and adsorbed on the cassiterite surface at pH 9.0. The adsorption of Fe(OH)₃ reduced the adsorption of OHA on the cassiterite surface, thus the hydrophobicity of cassiterite was deteriorated.