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Inorganic membranes are used to effectively capture particulate matter in dust without causing secondary pollution. However, fine dust particles accumulate on the surface and penetrate the structure of inorganic membranes, thereby degrading their performance. This study investigated the influence of the precoating of inorganic membranes with needle‐shaped wollastonite particles on their regeneration efficiency. The filter‐cake‐curing technique was employed, and the results were obtained by characterization methods, including scanning electron microscopy and energy‐dispersive spectroscopy. The mechanism for controlling membrane fouling was examined based on the quantity and depth of particle penetration to the filtration medium and pore structure of the filter cake. The results demonstrated that precoating can prevent fine particles from penetrating the membrane pores, thereby alleviating pore blocking in inorganic membranes. Furthermore, this increased the porosity and decreased the fractal dimension of the pore in the cake, thereby reducing the structural complexity and resistance during cake removal. The regeneration efficiency of the inorganic membrane increased from 59.4% without a precoating to 94.1% when wollastonite particles with an aspect ratio of 10 were used for precoating. [ABSTRACT FROM AUTHOR]

Foam stability was one of the important factors affecting the flotation process. In order to investigate the influence of quartz on the stability of flotation foam, the foam stability and froth drainage test were carried out to study the foam stability of quartz under different concentration of collector, particle size and mass concentration. The influence mechanism of quartz on the stability of flotation foam was further analyzed by contact angle measurement, Zeta potential test, foam optical image observation, surface tension and slurry viscosity measurements. The results showed that with the increase of dodecylamine concentration, the foaming ability of the solution increased, and the foam stability increased first and then decreased. This was mainly because dodecylamine significantly reduced the surface tension of the solution system and slowed down the average flow rate of liquid foam film draining in Plateau channel. The hydrophobicity of quartz surface gradually increased and the foam stability was enhanced. However, when the concentration of dodecylamine was greater than 60 mg/L and the three-phase contact angle of quartz exceeded 90°, the strongly hydrophobic particles no longer had the effect of stabilizing bubbles, but followed the mechanism of bridging and anti-wetting, and the foam stability decreased. The finer the quartz particle size was, the greater the mass concentration was, which increased the slurry viscosity, hindered the liquid film drainage and enhanced the foam stability. The froth drainage test results showed that the larger the quartz particle size was, the faster the bubble burst rate was, which was in line with the foam stability test results. The electrostatic action of dodecylamine adsorbed on quartz surface changed the electronegativity of quartz surface. Under the condition of flotation test, it was beneficial to form stable foam system. The foam image showed that quartz adhered to the surface of the bubble film, increasing the thickness of the liquid film and forming a tightly arranged shell structure in the boundary region of the two bubbles and Plateau Border, enhancing the stability of the foam. [ABSTRACT FROM AUTHOR]

The pyrolysis separation of calcium and magnesium from phosphate tailings is an important process due to its high-value resource utilization. In this paper, aiming to address the problems of high energy consumption, a slow decomposition rate and the low activity of decomposition products in the high-temperature pyrolysis of phosphate tailings, the medium-temperature pyrolysis of phosphate tailings under a H2O atmosphere was carried out, and the phase reconstruction and activation of pyrolysis process were discussed. The results showed that compared with N2, air and CO2 atmospheres, the pyrolysis process of phosphate tailings in a H2O atmosphere was changed from two stages to one stage, the starting decomposition temperature was reduced to 500 °C and the decomposition time was shortened to 30 min. The order of the influence of each factor on the pyrolysis of phosphate tailings was temperature > H2O pressure > holding time. Under the optimized pyrolysis conditions, the yield of CaMg(CO3)2 decomposition of phosphate tailings into MgO and CaO was 97.3% and 98.1%, respectively, and the reactivity of MgO was 31.6%. The distribution of Ca and Mg elements in the phosphate tailings after pyrolysis showed a negative correlation, and both of them no longer formed associated compounds; Ca mainly existed in the form of Ca(OH)2, Ca5(PO4)3F, CaSiO3 and CaF2, and Mg mainly existed in the form of MgO, MgF2 and Mg(OH)2. [ABSTRACT FROM AUTHOR]

The crystal habit of pentaerythritol (PE) crystals is usually rod-shaped, which may lead to low bulk density and bad flowability compared with low aspect ratio crystals. In this study, dipentaerythritol (DPE), methylcellulose (MC), and hydroxypropyl methylcellulose (HPMC) were selected as additives to modify the morphology of PE crystals. In the presence of DPE, the bulk density of PE crystals was improved, and the aspect ratio was decreased. The modified attachment energy (AE) model was conducted to analyze changes in PE crystal habits in the presence of DPE, which characterizes the intensity of the interaction between DPE molecules and PE crystal faces. Spherical pentaerythritol crystals can be successfully prepared by adding MC and HPMC solution, and the formation mechanism can be divided into five steps. [ABSTRACT FROM AUTHOR]