Minerals Engineering最新文献

Xanthates are the main trapping agents used in the processing of metallic sulfide ores and residual xanthates in beneficiation wastewater can potentially contaminate the environment at the mine site. Finding efficient methods to degrade butyl xanthates has received much attention. Micro–nano bubble (MNB) and advanced oxidation technologies (AOPs) have recently become increasingly important as effective treatment methods. In this study, the degradation of butyl xanthate was investigated through a micro–nano bubble-enhanced Fenton process (hydrogen peroxide (H₂O₂)/ peroxymonosulfate (PMS) /Fe²⁺). The effects of the process parameters (pH, coexisting ions, oxidant dosage (PMS, H₂O₂), and Fe²⁺ dosage) on the degradation of butyl xanthate were investigated. Results showed that the H₂O₂/PMS/Fe²⁺ process resulted in a 100 % degradation rate for butyl xanthate and 66 % total organic carbon (TOC) removal rate. With the enhancement of the degradation process using MNBs, the TOC removal rate increased to 80 %. The hydroxyl and superoxide radicals were identified as the main active substances in the degradation of butyl xanthate through electron spin resonance. Introducing H₂O₂ into the PMS/Fe²⁺ process increased the strength of hydroxyl and superoxide radicals in the reaction system. In addition, following the introduction of the MNBs, the amount of dissolved oxygen in the reaction system increased. As a result, the production of active substances in the reaction system increased. The synergistic effect of MNBs and the Fenton process caused an increase in the TOC removal rate. This implies that the multiprocess coupling technology of the MNB-enhanced Fenton process has great potential in the field of wastewater treatment.

In the last decades, there has been a growing demand for critical metals such as nickel (Ni) and cobalt (Co). Olivine, an orthosilicate mineral containing Ni and Co, presents a viable primary source for these metals. This study investigates the leaching behavior of selected elements, namely magnesium (Mg), silicon (Si), iron (Fe), Ni, and Co, from olivine using hydrochloric acid (HCl) and the impact of different factors. Characterization experiments indicated that Ni and Co were distributed throughout the olivine particles, being substitutes for Mg or Fe in the olivine crystal lattice. Based on the results, the favorable leaching conditions were t = 6 h, T=75 °C, solid-to-liquid ratio = 5 %, and [HCl] = 1 M, leading to 89.9 % and 90.8 % leaching efficiency for Ni and Co, respectively. Additionally, based on the shrinking particle model, the leaching kinetics of Ni and Co consisted of two distinct stages. During the initial 10 min, both film diffusion and chemical reaction controlled the process, whereas beyond this point, only the chemical reaction governed the leaching. Apparent activation energy values and morphological analysis of the solid residues confirmed the findings relevant to the leaching kinetics. This research provides valuable insights into the leaching kinetics of Ni and Co and the characteristics of solid residues, enhancing our understanding of the leaching process of olivine.

Understanding the mechanical properties of ores is critical for optimizing the crushing and grinding processes. To investigate the breakage characteristics of tungsten ores with different particle sizes in different crushing sections during the comminution process, the breakage index (t₁₀) and fractal dimension (D) of different particle sizes in different crushing sections were calculated using particle size distribution (PSD), and the correlation between JK size-dependent breakage model and fractal theory to characterize the mechanical properties of ores were discussed. The study results reveal that the JK size-dependent breakage model and fractal theory accurately characterize the mechanical properties of ores. With the same size, the mechanical properties of the particles increases as the comminution operation proceeds. But the HPGR, a unique roller pressing method, serves to keep the mechanical properties of particles lower than the cone crushers. The D of tungsten ore particles of different sizes under impact increased with E_cs and eventually reached a limiting value D_m. D to E_cs correlation was studied. Based on this, a mathematical model between t₁₀ and D was established and successfully fitted to the variation of ore mechanical properties under various impact crushing conditions. Compared with the traditional JK breakage model, the new model can better describe the mechanical properties from the perspective of ore properties.

This study systematically investigated the potential of organic acids as Ca²⁺ ions chelating agents in bastnaesite flotation. Naturally, bastnaesite is associated with calcium-bearing gangue minerals, such as calcite (CaCO₃) and fluorite (CaF₂). The flotation beneficiation of bastnaesite in the presence of calcium-bearing minerals (e.g., calcite) is exceptionally complex due to the release of Ca²⁺ ions into the flotation pulp which changes the solution chemistry and bastnaesite surface properties. This study seeks to address the challenge of dissolved Ca²⁺ ions on bastnaesite flotation using organic acids, namely lactic, succinic, and citric acids. Systematic micro-flotation experiments were followed by electro-kinetic tests, solution chemistry studies, and XPS characterization. The results of this study showed that the elevated concentration of Ca²⁺ ions dramatically decreased bastnaesite flotation recovery values. However, organic acids formed soluble chelates with Ca²⁺ ions, effectively eliminating the detrimental impact of dissolved Ca²⁺ ions on bastnaesite flotation.

Pyrrhotite, a ubiquitous gangue sulfide mineral in base metal sulfide ore deposits, has little to no economic value but can dilute base metal sulfide concentrates, reducing their quality and emitting SO₂ during downstream smelting. Therefore, effective rejection of pyrrhotite is crucial in the flotation of base metal sulfide ores. Pyrrhotite is characterized by various crystallographic superstructures, such as 4C, 5C, 6C and 11C, which exhibit markedly different flotation behaviors, complicating its separation from value base metal minerals. This paper reviews the distinct characteristics of pyrrhotite superstructures such as crystal structure, chemical composition, iron vacancy ordering, optical properties, magnetic susceptibility and bond vibrational modes that can serve as unique identifiers for the identification and quantification of pyrrhotite superstructures in base metal sulfide ores. In this paper, the advantages and limitations of various characterization techniques, including X-ray diffraction (XRD), optical microscopy, thermomagnetic analysis, scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), and various spectroscopic methods such as Mössbauer spectroscopy, Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy for distinguishing pyrrhotite superstructures in ore samples are reviewed. Although these techniques provide a robust framework for analyzing pyrrhotite’s intricate properties, the identification process is complicated by the fact that all pyrrhotite superstructures share a common NiAs-type hexagonal lattice, exhibit only subtle compositional differences and possess similar optical and vibrational properties. Consequently, relying solely on the results from a single technique can be inadequate to distinguish between different pyrrhotite superstructures accurately. In this regard, the review discusses the potential of combining various techniques to enhance the capability of accurately identifying and quantifying pyrrhotite superstructures. By improving the identification and quantification of pyrrhotite superstructures in ore samples, the minerals industry may optimize the strategies to selectively reject pyrrhotite, reducing environmental impacts and achieving better recoveries of base metal minerals.

Abandoned iron mine soil (MS) contains elevated concentrations of heavy metals (HMs) with poor bio-physicochemical characteristics, causing significant risk to the environment including associated living organisms if not handled properly. Studies related to iron ore MS remediation and reclamation with commercially important bioenergy plants and economically viable amendments are still scarce and elusive. This study investigates the influence of farmyard manure (FYM), NPK fertilizer and the blending of different ratios of garden soil (0–100 %) on the MS bio-physicochemical parameters and the response of Ricinus communis L. The pot experiment was carried out for 90 days in a naturally illuminated net house to record the growth parameters, tolerance index (TI), metal accumulation, bioaccumulation factor (BAF), total metal extract by plant (Metal_Ex) and improvement of soil bio-physicochemical properties after harvesting. Study shows MS has low pH, low organic carbon (OC), and matter (OM), water holding capacity (WHC) and lack of key nutrients along with low soil microbial biomass carbon (Cmic) and nitrogen (Nmic) with high levels of Fe, Cu, Pb, and Ni with 2032.33, 34.52, 64.94 and 70.67 mg kg⁻¹ respectively. The amendments of NPK and FYM enhanced the growth of R. communis by 179.86 and 441.32 % respectively. The TI, chlorophyll and carotenoid levels show an upward trend along the growing period. The accumulation of HMs in NPK unit was found in order of Fe > Ni > Pb > Cu and for FYM unit as Fe > Pb > Cu > Ni. The BAF and Metal_Ex values were significantly high for FYM treatment sets. The soil properties like OC, OM, Cmic and Nmic improved after harvesting by 13, 17, 8.84 and 6.38-fold, respectively. Overall, the study concludes that the application of FYM showed better results than NPK. R. communis has found to bear a substantial potential to accumulate high concentrations of HMs and grow well in multi-metal contaminated MS.

The SAG mill’s discharge end cover, which comprises the slurry lifters, the grate liners, and other structures, significantly impacts the machine’s discharge capacity. The working performance of the current SAG mill when the radial structure and arc structure were adopted in the lifting bars of the grate liners and slurry lifters, respectively, was compared to investigate the influence of the discharge end cover structure on the discharging capacity and optimize the design of the end cover structure. Additionally, a new arc structure for the lifting bar was designed. The discharge process of the ore particles passing through the discharge end cover in the SAG mill was simulated using the discrete element method (DEM). The analysis included the discharging rate, discharging efficiency, and flow characteristics of the ores under the three lifting bar structures, as well as the impact of the lifting bar structure and the arrangement of the discharge holes of grate liners on the discharging capacity. The results demonstrate a positive correlation between the effective discharge hole area of grate liners and discharge rate. When adopting the arc lifting bars, the grate liners have a larger effective discharge hole area and a stronger discharge capacity than the radial lifting bars. The new design arc structure for lifting bars largens the effective discharge hole area and enhances the discharge capacity of the grate liners when compared to the original arc structure of lifting bars. The ore particle backflow phenomenon will be evident in the discharge process of the slurry lifters when the lifting bars of the slurry lifters adopt a radial structure; on the other hand, the arc structure can effectively mitigate the backflow issue and increase the discharge rate. Based on the observation that the arrangement of discharge holes on the grate liners greatly affects the discharging rate of the grate liners, a strategy for arranging the discharge holes is suggested to maximize the discharging capacity of the SAG mill. In addition, a comparison between the findings of the discrete element simulation and the experimental data confirms the viability of the simulation approach.

This study investigates the role of alkyl ether monoamine-coated nanobubbles (NBs) in assisting the flotation process of quartz across various particle sizes, on a bench scale. Experiments were conducted in a mini lab column utilizing a consortium of bubble sizes: D32 = 1200 μm for macrobubbles and D32 = 180–220 nm for amine-coated NBs. The study revealed that an increase in amine-coated NBs correlates well with a decrease in the air/solution’s interfacial tension caused by the ether amine at less than 68 mN m⁻¹. True flotation recoveries with varying amine/g quartz, where the collector-frother amine may be amine-coated NBs alone or assisted by NBs generated in pure water, were compared with blank tests, in the absence of NBs. The flotation study evaluated size-to-size fractions from fine (−20 µm) to coarse (up to 150 µm) particles and their mixtures. In addition, the work extended to explore the behavior of the “super” coarse quartz from 150 µm up to 1000 µm. The results highlighted a clear dependence on the particle size, with NBs improving recoveries in all fractions, especially the difficult-to-treat ultrafine/fine and coarse quartz. Recovery results exceeded 90 % in all fractions (isolated or in mixtures) at a high rate with the amine-coated NBs. The mechanisms proposed improved flotation performance attributed to the high numerical concentrations of NBs (at least 2–3 × 10¹⁰ NBs per gram of quartz) rapidly attaching to quartz surfaces, serving as “seeds” for the adhesion of larger bubbles generated in conventional flotation cells. This interaction facilitates the formation of lightweight, cluster-like aggregates that swiftly rise to the column’s surface. Notably, larger quartz particles (+355 µm) form the bigger hydrophobic and buoyant clusters, leading to their rapid levitation and effective phase separation, with over 95 % separation efficiency. This innovative technique’s significance, outcomes, and potential scalability are thoroughly discussed, highlighting its promising applicability in diverse mineral and ore flotation systems, particularly those containing quartz and silicates.

Germanium is considered by many world economies, including the USA and EU, as a critical raw material. One of the methods, which may be used in its recovery is solvent extraction. Using it application of more environmentally harmful processes like tannin concentrate precipitation or chlorination may be reduced. Solvent extraction of germanium from solution after oxidative leaching of copper cake by two extractants, chelating Mextral 63H (LIX 63 equivalent) and basic trioctylamine (TOA), were compared. For TOA influence of complexant addition, tartaric acid, malic acid, malonic acid, and succinic acid, on germanium recovery yield was also tested. It was found that under investigated conditions, i.e. pH∼1.0 TOA was a better and more selective germanium extractant. The highest Ge extraction yields (>96 %) were achieved when tartaric acid was used as a germanium complexant in an aqueous phase. It was determined that germanium may be stripped from the organic phase using > 5 wt% NaOH solution with > 93 % yield.

Cobalt is mainly produced globally from Cu-Co sediment-hosted deposits in the Democratic Republic of Congo. As mining operations progress, oxidic supergene mineralisation gradually depletes, and many have been or are shifting towards extracting sulphide ore at depth. Overall, copper recovery is consistently higher than cobalt, but no in-depth investigation has been conducted to determine if this difference is due to ore mineral characteristics. The role of ore mineralogy on the flotation performance of copper-cobalt sulphides was studied by tracking the changes in mineral properties with time throughout the flotation process. A series of laboratory rougher-scavenger flotation experiments were carried out using a dithiophosphate collector to define the optimum collector dosage, which was determined to be 30 g/t. With that dosage, an experiment was carried out during which concentrates were collected at distinct times and then analysed by QEMSCAN®. The feed ore was relatively rich containing around 32 wt% bornite, 8 wt% carrollite and under 1 wt% of chalcocite and chalcopyrite. The particle size distributions of carrollite and bornite were suitable for flotation while chalcopyrite and chalcocite were relatively fine-grained. Carrollite also showed to be well-liberated while only half of the bornite showed to be fully liberated with around 25 % of bornite in the feed associated with magnesiochlorite, quartz or other gangue minerals. Even though carrollite had favourable properties for flotation, higher recoveries were obtained for bornite, chalcocite and chalcopyrite throughout the whole experiment. Carrollite grain size seems to have played a significant role in the recoverability of cobalt as the optimum size range was relatively narrow compared to bornite at around 20–45 µm with limited recovery above 100 µm. This upper size limit may be increased to some extent with higher collector dosage but, at ambient pH, the differential reactivity of the copper and cobalt sites at the mineral surface favours collector adsorption on copper sites.