Solvent extraction is the most widely used method for separation and purification of rare earth elements, and organic extractants such as di(2-ethylhexyl) phosphoric acid (P204) and di(1-methyl-heptyl) methyl phosphonate (P350) are most commonly used for industrial applications. However, the presence of impurity ions in the feed liquid during extraction can easily emulsify the extractant and affect the quality of rare earth products. Aluminum ion is the most common impurity ion in the feed liquid, and it is an important cause of emulsification of the extractant. In this study, the influence of aluminum ion was investigated on the extraction of light rare earth elements by the P204-P350 system in hydrochloric acid medium. The results show that Al³⁺ competes with light rare earths in the extraction process, reducing the overall extraction rate. In addition, the Al³⁺ stripping rate is low and there is continuous accumulation of Al³⁺ in the organic phase during the stripping process, affecting the extraction efficiency and even causing emulsification. The slope method and infrared detection were utilized to explore the formation of an extraction compound of Al³⁺ and the extractant P204-P350 that entered the organic phase as AlCl[(HA)₂]₂P350_(o).

Flotation reagents can change the surface properties of minerals, leading to differences in the interaction between mineral particles and affecting the mutual aggregation or dispersion of particles. In this work, we studied the role of activator copper sulfate, collector butyl xanthate and frother terpineol in adjusting the potential energy of pyrite particles from the perspective of the interfacial interaction. We evaluated the surface characteristics using contact angle analysis and zeta potential measurements under different reagents. A microscope was used to observe aggregation state of particles. The hydrophobic agglomeration kinetics of pyrite was studied through the turbidity meter measurement, and the interaction energy between pyrite particles was calculated using the extended-Derjaguin-Landau-Verwey-Overbeek (extended-DLVO) theory. The results showed that the repulsive potential energy is dominant among pyrite particles in aqueous suspensions and that the particles are easy to disperse. Flotation reagents can effectively reduce the repulsive energy between pyrite particles and increase the attraction energy between particles, which is conducive to the hydrophobic agglomeration of fine pyrite. Reagent molecules can greatly reduce the electrostatic repulsion potential energy of the pyrite particles’ interface, increase the hydrophobic attraction potential energy between the particle interfaces, and its size is 2 orders of magnitude larger than the van der Waals attraction potential energy, which is the main reason for induced the agglomeration of fine pyrite and is conducive to the flotation recovery of fine pyrite. Generally, the order in which the reduction of pyrite agglomeration was affected by the additions of flotation reagents was butyl xanthate > terpineol > copper sulfate.

In this paper, the adsorption of cyanide and its combination with zinc sulfate on the surface of sphalerite (110) was studied by density functional theory (DFT), and its configurational relationship was analyzed by coordination chemistry. The calculation results show that the adsorption configuration stability of CN⁻ is stronger than that of Zn(CN)₂; the chemical bond of Zn(OH)₂ is less covalent. The three adsorption modes all make the surface of sphalerite lose more electrons, thereby weakening the reactivity of S and Zn atoms on the sphalerite surface. During the CN⁻ adsorption process, both the 3d and 4p orbital peak energy levels of Zn decrease, indicating the strong inhibitory effect of CN⁻. Coordination chemistry also shows that CN⁻ matches the Zn ion orbital in sphalerite and the π electron pair on the Zn ion can easily interact with the empty π orbital on CN⁻ to form π-backbonding.

Chalcopyrite and molybdenite are vital strategic metal resources. Due to their close association in ores, flotation methods are commonly used for separation. The flotation separation method primarily employs the “copper depression and molybdenum flotation” process, enhancing the wettability difference between chalcopyrite and molybdenite through a chalcopyrite depressant. Traditional depressants often face challenges, including low selectivity, high dosage requirements, poor stability, and significant environmental pollution, highlighting the need for new, highly selective green reagents. This study introduces the novel chalcopyrite depressant 2-mercapto-6-methylpyrimidin-4-ol (MMO) for flotation separation. The influence of MMO on chalcopyrite and molybdenite flotation recovery was examined through microflotation experiments. Additionally, the effects of MMO and ethyl xanthate on surface wettability were assessed via contact angle measurements. The adsorption microstructure and interaction mechanism of MMO on chalcopyrite were elucidated using FT-IR, TOF-SIMS, and XPS analyses and DFT simulations. Results indicate that MMO enhances chalcopyrite hydrophilicity and exhibits a strong depressing effect on its flotation, while minimally impacting molybdenite recovery. Thus, it serves as an effective depressant. During adsorption, N and S atoms in MMO donate electrons to Fe and Cu ions, leading to triple bond adsorption and a stable chelate structure. These findings are crucial for achieving a greener and more efficient flotation separation of copper and molybdenum.

Extracting iron while minimizing the health and environmental risks associated with arsenic contamination necessitates the removal of arsenic from arsenic-bearing iron ores to ensure a safe and sustainable supply of this metal for industries. The beneficiation of iron minerals and arsenic-bearing minerals from arsenic-bearing iron ores with a calcification-magnetizing roasting and low-intensity magnetic separation (CMR-LMS) process is investigated in this work. The results show that the process is successful in extracting iron minerals and eliminating arsenic-containing minerals. The roasting involves two key steps: calcification and magnetizing, which change hematite and goethite into magnetite and arsenic-bearing minerals into calcium arsenates. The process’s separation efficiency of the CMR-LMS is closely linked to the parameters such as roasting temperature, roasting time, coke, alkalinity, and the liberation of gangue minerals from iron minerals. Through grinding and secondary magnetic separation, the iron minerals and gangue components, as well as arsenic, in roasted sand can be further separated. The optimum procedure results in a high-grade iron concentrate with an iron assay of 65.65%, an Fe recovery rate of 80.07%, and an arsenic content of 0.085%, while achieving a 93.29% As removal rate from the original ore that has 45.32% Fe and 0.70% As.

Thiophosphate compounds have attracted much attention in coordination chemistry, but their deep adsorption mechanism remains underexplored as flotation collectors. The flotation performance and adsorption mechanism of a novel (dibutoxy-thiophosphorylsulfanyl)-acetic acid (CDDP) chelating collector on azurite surfaces were studied by micro-flotation tests, zeta potential measurements, and Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FE-SEM) analysis. The micro-flotation results indicated that CDDP exhibited superior collecting performances to direct flotation recovery of azurite and floated over 91.44% of azurite at pH 7. For sodium isopentyl xanthate (NaIX) and Benzohydroxamic acid (BHA) collectors, the addition of Na₂S still did not show good collection performance. The results of zeta potential, FTIR, XPS and FE-SEM measurements, all confirmed that CDDP showed a better affinity to azurite surfaces than NaIX and BHA. Furthermore, XPS and FE-SEM provided obvious evidence that CDDP could easily react with Cu²⁺ sites on azurite surfaces. Using the density functional theory (DFT) method, the collection capacity of azurite was CDDP > BHA > NaIX, which exactly matched the micro-flotation results. In addition, this study provided an atomic-scale understanding of the structure–property relationship of CDDP as chelating agents for copper mineral flotation.