•Sodium oleate has collecting ability for both scheelite and calcite.•Acidified sodium silicate is mixture of sodium silicate and oxalic acid with a ratio of 3:1.•Acidified sodium silicate exhibits ...selective depression for calcite.•The separation of scheelite from calcite is realized.
The flotation separation of scheelite from calcite using sodium oleate as collector and acidified sodium silicate as depressant has been studied. The results show that sodium oleate has collecting ability to both scheelite and calcite and the flotation separation of scheelite from calcite cannot be realized if collector is used only. The depressant acidified sodium silicate has selective depression effect on calcite and the optimum ratio of sodium silicate to oxalic is 3:1. The use of acidified sodium silicate as depressant can achieve the flotation separation of scheelite from calcite. Infrared studies and zeta potential measurements showed that the pre-adsorption of acidified sodium silicate interferes with the adsorption of sodium oleate on calcite surface while does not interfere with its adsorption on scheelite surface.
There is an urgent need for an eco-friendly and efficient route to treat the organic pollutants in wastewater. Therefore, we report a facile synthesis of carbon nanotube–magnesium oxide composite ...(CNTs/MgO) which can efficiently activate peroxymonosulfate (PMS) to degrade Rhodamine B (RhB). Fabricated CNTs/MgO was characterized by XRD, FTIR, SEM, TEM, BET, XPS, and Raman. The results showed that the carbon nanotubes uniformly entangled on the MgO whiskers and linked to the MgO by Mg–C and C–O bonds. The effects of temperature, pH value, CNTs/MgO dosage, PMS dosage and the ratio of MgO/CNTs on degradation of RhB were conducted to determine the activation performance of CNTs/MgO. The catalytic degradation process was carried out in a wide pH range of 3–9, and 100% of RhB was degraded in 20 min under optimized conditions. Moreover, the efficient degradation performance was attributed to singlet oxygen generated in the PMS&CNTs/MgO system. The excellent activation properties of CNTs/MgO was derived from the enhanced electron transport performance and chemical bonding between MgO and CNTs. In addition, this work provides an innovative design for the development of novel PMS catalysts without transition metal components.
Background
To observe changes in the cauda equina nerve on lumbar MRI in patients with central lumbar spinal stenosis (LSS).
Methods
878 patients diagnosed with LSS by clinical and MRI were divided ...into the redundant group (204 patients) and the nonredundant group (674 patients) according to the presence or absence of redundant nerve roots (RNRs). The anteroposterior diameter of the spinal canal (APDS) and the presence of multiple level stenosis, disc herniation, thickening of ligamentum flavum (LF) and increased epidural fat were assessed on MRI. Univariate and multivariate logistic regression analyses were performed to explore the predictors of LSS combined with RNRs.
Results
Patients with LSS combined with RNRs had thicker epidural fat, smaller APDS and more combined multifaceted stenosis. Female patients and older LSS patients were more likely to develop RNRs; there was no difference between two groups in terms of disc herniation (
p
> 0. 05). Age, APDS, multiple level stenosis, and increased epidural fat were significantly correlated with the formation of LSS combined with RNRs (
p
< 0.05).
Conclusion
A smaller APDS and the presence of multiple level stenosis, thickening of LF, and increased epidural fat may be manifestations of anatomical differences in patients with LSS combined with RNRs. Age, APDS, multiple level stenosis, and increased epidural fat play important roles. The lumbar spine was measured and its anatomy was observed using multiple methods, and cauda equina changes were assessed to identify the best anatomical predictors and provide new therapeutic strategies for the management of LSS combined with RNRs.
Ameliorating the problem of low leaching efficiency, long leaching period, and high agent consumption should be studied to efficiently exploit ion-absorbed rare earth ore resources. In this study, ...the surfactant sodium dodecyl sulfate (SDS) is used to enhance the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect for the first time. The effects of surfactant concentration, leaching agent dosage, solution flow velocity, and solution pH on the leaching rate were explored, and the mechanism of SDS was discussed. Under the optimum conditions, the addition of a small amount of SDS (mass fraction 0.04%) can increase the leaching rate by about 5%, shorten the leaching period, and reduce the consumption of the leaching agent. SDS significantly ameliorates the seepage effect of the ore body by reducing the surface tension of the leaching agent and ameliorating the wettability of the mineral surface. This effect is the main factor that improves the leaching efficiency. DFT (density functional theory) calculation results show that SDS can react with rare earth ions, which reduces the adsorption strength on clay mineral surfaces. Hence, rare earth ions are easily exchanged by ammonium ions, and mass transfer is enhanced.
Pore network structure of ore body is a diffusion channel of leaching agent solution that exerts a significant influence on seepage. The ore body structure, pore distribution, pore and throat size, ...and pore network characteristics of topsoil, weathered, and semiweathered layers of ionic rare earth ore in southern Jiangxi Province were explored in this study. The effect of leaching operation on the pore structure was investigated, and main factors affecting the seepage were analyzed. Results showed that the semiweathered layer presents a dense structure and a small number of unconnected pores. Pores of topsoil and weathered layers are mainly long and narrow column openings with some planar fractures. Even pore distribution and large size span were observed. Compared with the weathered layer, the topsoil layer demonstrates larger voids, smaller average pore volume and equivalent radius, and fewer coordination throats; however, the average equivalent radius of the throat in the topsoil layer is larger and large-scale channels exist through ore body vertically. Hence, permeability of the topsoil layer is significantly higher than that of the weathered layer. Colloidal clay minerals migrate easily and the occurrence of silting in the small porosity blocks the throat and significantly decreases the permeability of the ore body in the leaching process. The equivalent radius of the throat is the key to the seepage. Reducing the migration of fine particles is an effective measure to protect the throat and shorten the leaching period.
•The interaction of H2O and spodumene surface reduces the collector adsorption strength.•The weak adsorption of Ca2+ makes spodumene difficult to be activated at neutral pH.•The bonding of OH with Al ...sites improves the adsorption of Ca(OH)+ and Ca(OH)2.•Ca(OH)+ effectively improved the adsorption strength of collector.•Ca(OH)2 has great hindrance to the adsorption of collector on Al sites.
Calcium chloride is an important activator for spodumene flotation; however, its mechanism has been controversial. In this study, density functional theory (DFT) calculation was taken to investigate the adsorption of reagents from the atomic and electronic microscopic perspective, and the activation mechanism of calcium was discovered. Results show that the reaction of the O in the H2O with the Al on the mineral surface reduces the bonding strength between the collector and the Al sites, making spodumene recovery by flotation impossible in the absence of active ions. The Ca2+ can bond with two adjacent O atoms of the spodumene surface. However, the weak adsorption strength makes spodumene difficult to be activated effectively at neutral pH. The hydroxyl group in Ca(OH)+ and Ca(OH)2 strongly bonds with Al sites on the surface, significantly improving the adsorption strength of these components, and the adsorption strength of Ca(OH)2 is the highest. However, the Ca(OH)2 have a greater steric hindrance effect on the adsorption of the collector on the Al sites, resulting in the collector adsorbing on the Ca site of the spodumene surface in the bidentate adsorption form. Hence, Ca(OH)2 cannot effectively improve the flotation recovery effect of spodumene. After the Ca(OH)+ treatment, the O atoms of the collector bond with Ca and Al atoms on the surface, resulting in the great increase of collector adsorption strength. Thus, the species of Ca(OH)+ is the sole effective active component in spodumene flotation.
Different TiO2/g-C3N4 (TCN) composites were synthesized by a simple pyrolysis method with TiO2 xerogel and urea. The structure and physicochemical properties of TCN were characterized by X-ray ...diffraction, scanning electron microscope, transmission electron microscope, ultraviolet-visible diffuse reflectance spectrum, X-ray photoelectron spectroscopy, N2-adsorption isotherms and electrochemical impedance spectroscopy. Aniline Aerofloat was chosen as a typical degradation-resistant contaminant to investigate the photodegradation activity of TCN under UV irradiation. The results indicated that TCN had higher light absorption intensity, larger specific surface area and smaller particle size compared to pure TiO2. Furthermore, TCN had great recycling photocatalytic stability for the photodegradation of Aniline Aerofloat. The photocatalytic activity depends on the synergistic reaction between holes (h+) and hydroxyl radicals (·OH). Meanwhile, the direct Z-scheme heterojunction structure of TiO2 and g-C3N4 postpones the recombination of h+ and electrons to enhance UV-light photocatalytic activity.
Under the background of increasingly scarce ore worldwide and increasingly fierce market competition, developing the mining industry could be strongly restricted. Intelligent ore sorting equipment ...not only improves ore use and enhances the economic benefits of enterprises but also increases the ore grade and lessens the grinding cost and tailings production. However, long-term research on intelligent ore sorting equipment found that the factors affecting sorting efficiency mainly include ore information identification technology, equipment sorting actuator, and information processing algorithm. The high precision, strong anti-interference capability, and high speed of these factors guarantee the separation efficiency of intelligent ore sorting equipment. Color ore sorter, X-ray ore transmission sorter, dual-energy X-ray transmission ore sorter, X-ray fluorescence ore sorter, and near-infrared ore sorter have been successfully developed in accordance with the different characteristics of minerals while ensuring the accuracy of equipment sorting and improving the equipment sorting efficiency. With the continuous improvement of mine automation level, the application of online element rapid analysis technology with high speed, high precision, and strong anti-interference capability in intelligent ore sorting equipment will become an inevitable trend of equipment development in the future. Laser-induced breakdown spectroscopy, transient γ neutron activation analysis, online Fourier transform infrared spectroscopy, and nuclear magnetic resonance techniques will promote the development of ore sorting equipment. In addition, the improvement and joint application of additional high-speed and high-precision operation algorithms (such as peak area, principal component analysis, artificial neural network, partial least squares, and Monte Carlo library least squares methods) are an essential part of the development of intelligent ore sorting equipment in the future.
Wastewater containing low concentrations of rare earth ions not only constitutes a waste of rare earth resources but also threatens the surrounding environment. It is therefore necessary to develop ...environmentally friendly methods of recovering rare earth ions. The spores produced by Bacillus are resistant to extreme environments and are effective in the bioadsorption of rare earth ions, but their adsorption behaviors and mechanisms are not well understood. In this study, the cells and spores of Bacillus subtilis PS533 and PS4150 were used as biosorbents, and their adsorption of terbium ions was compared under different conditions. The adsorption characteristics of the spores were investigated, as were the possible mechanisms of interaction between the spores and rare earth ions. The results showed that the PS4150 spores had the best adsorption effect on Tb(III), with the removal percentage reaching 95.2%. Based on a computational simulation, SEM observation, XRD, XPS, and FTIR analyses, it was suggested that the adsorption of Tb(III) by the spores conforms to the pseudo−second−order kinetics and the Langmuir adsorption isotherm model. This indicates that the adsorption process mainly consists of chemical adsorption, and that groups such as amino, hydroxyl, methyl, and phosphate, which are found on the surface of the spores, are involved in the bioadsorption process. All of these findings suggest that Bacillus subtilis spores can be used as a potential biosorbent for the recovery of rare earth ions from wastewater.
Spodumene is a silicate mineral rich in lithium. However, the gangue mineral, albite has similar crystal chemical structure and composition to spodumene. In this work, the density functional theory ...(DFT) calculation was taken to research the floatability from the perspective of crystal chemistry. And contact angle test and reagent adsorption test were used to support the simulation results. In addition, the weighted total density of broken bonds is proposed for the first time to judge the generation probability of cleavage surface. The DFT calculation results display that the Na and Al sites on the albite surface are the adsorption sites of water molecules. While the water molecules only bond with Al atom on the surface of spodumene and each Al site can adsorb only one water molecule. Thus, the wetting effect of water molecules on the albite surface is stronger than that of spodumene. This is consistent with the result of contact angle. In sodium oleate system, the oleic acid anion is adsorbed on the spodumene surface in form of a multicomponent ring while the albite is a single ring. Theoretically, oleic acid anion can be strongly adsorbed on the surface of spodumene and albite under vacuum. The adsorption strength of spodumene is higher than that of albite. However, on hydrated surface, the adsorption strength of oleic acid anion on mineral surface is greatly reduced due to the interaction between water molecules and metal site on mineral surface. Thus, spodumene and albite are hard to float without external activated ions in sodium oleate system.
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