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How to improve coal flotation performance has been examined with a focus on the effect of particle size on flotation conditioning. A coking coal sample collected from the flotation feed of a coal preparation plant located in Lu’an, Shanxi province of China was investigated. The characters including mineral composition, size fraction, density fraction, and contact angle were analyzed. Classified and unclassified conditioning tests were carried out using different size fractions. The relationship between flotation indices (combustible recovery and flotation efficiency) and conditions (particle size, collector dosage, and conditioning stirring speed) was investigated. The results showed that the optimum conditions for different size fractions were different. The collector dosage and the conditioning stirring speed increased with the decrease of particle size. Meanwhile, the collision frequency between fine coal and diesel particles was much higher than the coarse particles, resulting most of the flotation agents adsorbed by fine particles, though the kinetic energy of coarse particles was higher. So a classified conditioning process was proposed. By conditioning optimizing, the flotation performance of classified conditioning was significantly improved compared with unclassified conditioning, especially for the +0.125 mm fractions. [ABSTRACT FROM AUTHOR]

In present work, BiFeO was synthesized at different temperatures (450, 500, 550 °C) by tartaric acid sol-gel method. XRD, SEM and TEM were used to characterize microstructure and morphology of as-prepared BiFeO. All results indicate that as-prepared BiFeO is the nanocrystal with single rhombohedrally distorted perovskite structure with the space group R3c and has irregular shapes and the average grain sizes between 50 and 120 nm. BiFeO nanomaterials have a low working temperature of 240 °C and high acetone gas response. Especially for BiFeO grown at 500 °C, the sensitivity to 50 ppm acetone is about as high as 30 at 240 °C. The response and recovery time of BiFeO sensors is respectively about 5 and 18 s. Moreover, BiFeO sensors have a low detection limit and the logarithmic curves of the sensitivity and concentration of BiFeO sensors satisfy the linear relationship in the low detection range. These results demonstrate that BiFeO can be used as an ideal candidate to fabricate high response acetone sensor. Gas sensing mechanism of BiFeO is also discussed on the basis of adsorption and desorption of reducing acetone gas and the reaction with oxygen species on the surface of BiFeO nanomaterials. This work can give rise to an interesting choice for researching excellent gas sensing properties of other nonstoichiometric oxides. [ABSTRACT FROM AUTHOR]

The present work has been carried out to investigate the effect of process variables on gas holdup and develop an empirical equation and a neural network model for online process control of the gas holdup based on the operating variables. In this study, the effect of process variables (nozzle diameter, circulation pressure, aeration rate, and frother dosage) on gas holdup in a cyclone-static micro-bubble flotation column of an air/oily wastewater system was investigated. Gas holdup was estimated using a pressure difference method and an empirical equation was proposed to predict gas holdup. A general regression neural network (GRNN) model was also introduced to predict gas holdup for the cyclone-static micro-bubble flotation column. The predictions from the empirical equation and the GRNN are in good agreement with the experiment data for gas holdup, while the GRNN provides higher accuracy and stability compared with that of the empirical equation. [ABSTRACT FROM PUBLISHER]

The effect of calcium borosilicate (CBS) glass ceramic on the phase formation, the microstructures and the microwave dielectric properties of 0.95(MgZn)TiO-0.05CaTiO (MZCT) ceramics prepared via the conventional solid-state reaction route were investigated. It has been found that (MgZn)TiO and CaTiO are the main phases and a second phase (MgZn)TiO appeared in MZCT ceramics doped with CBS glass. As the content of CBS glass increased, the second phase (MgZn)TiO further enhanced. Appropriate CBS glass addition could effectively facilitate sintering of the ceramics, and well-densified microwave ceramics with uniform grains could be obtained under 1240 °C. An extremely high Q × f of 59,200 GHz together with an ε of 21.42 and a τ value of −2.1 ppm/°C could be found for 0.95(MgZn)TiO-0.05CaTiO specimen with 4 wt% CBS glass addition sintered at 1240 °C for 2 h. This study shows that appropriate addition of CBS glass could effectively decrease the sintering temperature of MZCT ceramics without deteriorating the ceramic performance. [ABSTRACT FROM AUTHOR]

Bubble size is a key factor in froth flotation for oil-water separation. In this paper, the bubble size which impacts on oil removal efficiency for a novel oil-water separation column was researched systematically. The bubble size distribution was researched by using the photographic method and Matlab software. In addition, several operating parameters which impact on the bubble size were investigated, including circulating pressure, aeration rate, and the foaming agent. Based on the results of experimental data and image analysis, the frother consumption and aeration rate has important influence on the bubble size. The bubble size can be controlled by adjusting the operation conditions including the circulating pressure, aeration rate, and the frother consumption. The optimum operating conditions for the oil-water separation column were determined. Furthermore, the mathematical model of oil removal efficiency for the oil-water separation column was established. [ABSTRACT FROM AUTHOR]

In order to improve the separation efficiency of fine oil droplets from oily wastewater, a new process utilizing coal adsorption and column flotation has been developed. In this work, anthracite from Jincheng, China was used as an adsorbent for oil removal from wastewater. The effects of adsorption time, coal particle size distribution, the value of pH, and the oil concentration in wastewater on the adsorption capacity of anthracite were investigated by static experiments. A novel device named a cyclone-static microbubble flotation column was developed for the separation of oily wastewater, which combines the conventional hydrocyclone with a conventional flotation column. Coal adsorption-column flotation tests were carried out and scaled-up from a lab-scale (1 m3/day), to a pilot scale (30 m3/day), and to a full-scale (2000 m3/day) unit. Different operating parameters, such as coal dosage, feed rate, circulation pressure, and gas flow rate were studied. In full-scale tests of 2000 m3/day, oil removal of 97.70% with the treated effluent containing an oil concentration of 23.39 mg/L was obtained. [ABSTRACT FROM AUTHOR]

Abstract: Ce3+ activated LaCl3 is a promising scintillation crystal for radiation detection. The starting raw materials used to grow LaCl3 crystals are rather hygroscopic and XRD proves that LaCl3·7H2O and LaCl3·3H2O are two main compounds in the raw materials. Five endothermal peaks, 100.4°C, 156.0°C, 181.0°C, 210.6°C and 840°C, are observed in the DTA curves, they are corresponding to the thermal dehydration effect of crystallized water and melting. The process of dehydration is described to be 7→6→3→1→0. In the dehydration process, little amount of LaOCl phase can be identified, its formation is related to the oxidation of LaCl3 at high temperature: LaCl3·nH2O→LaOCl+HCl↑. In addition, LaOCl phases also appear in the grown crystals, they are suggested to be responsible for the transmission loss of the crystals. The oxidation temperature of LaCl3 with oxygen is much lower than that with water. [Copyright &y& Elsevier]

Natural products are attractive components to tailor environmentally friendly advanced new materials. We present surface-confined metallosupramolecular engineering of coordination polymers using natural dyes as molecular building blocks: indigo and the related Tyrian purple. Both building blocks yield identical, well-defined coordination polymers composed of (1 dehydroindigo : 1 Fe) repeat units on two different silver single crystal surfaces. These polymers are characterized atomically by submolecular resolution scanning tunnelling microscopy, bond-resolving atomic force microscopy and X-ray photoelectron spectroscopy. On Ag(100) and on Ag(111), the trans configuration of dehydroindigo results in N,O-chelation in the polymer chains. On the more inert Ag(111) surface, the molecules additionally undergo thermally induced isomerization from the trans to the cis configuration and afford N,N- plus O,O-chelation. Density functional theory calculations confirm that the coordination polymers of the cis-isomers on Ag(111) and of the trans-isomers on Ag(100) are energetically favoured. Our results demonstrate post-synthetic linker isomerization in interfacial metal-organic nanosystems., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

BiFeO 3 nanocrystals were applied as the sensing material to isopropanol. The isopropanol sensor based on BiFeO 3 nanocrystals shows excellent gas-sensing properties at the optimum working temperature of 240 °C. The sensitivity of as-prepared sensor to 100 ppm isopropanol is 31 and its response and recovery time is as fast as 6 and 17 s. The logarithmic curves of the sensitivity and concentration of BiFeO 3 sensors are a very good linear in the low detection range of 2-100 ppm. In addition, the gas sensing mechanism is also discussed. The results suggest that the BiFeO 3 nanomaterial can be potentially applied in isopropanol gas detection.

This paper presents the facile synthesis of two different morphologies of WS 2 nanomaterials-WS 2 hexagonal nanoplates and nanoflowers-by a sulfurization reaction. The phases and morphology of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The tribological performance of the two kinds of WS 2 nanomaterials as additives in paraffin oil were measured using a UMT (Universal Mechanical Tester)-2 tribotester. The results demonstrated that the friction and wear performance of paraffin oil can be greatly improved with the addition of WS 2 nanomaterials, and that the morphology and content of WS 2 nanomaterials have a significant effect on the tribological properties of paraffin oil. The tribological performance of lubricating oil was best when the concentration of the WS 2 nanomaterial additive was 0.5 wt %. Moreover, the paraffin oil with added WS 2 nanoflowers exhibited better tribological properties than paraffin oil with added WS 2 hexagonal nanoplates. The superior tribological properties of WS 2 nanoflowers can be attributed to their special morphology, which contributes to the formation of a uniform tribo-film during the sliding process.