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Now showing items 1 - 16 of 39

  • Process intensification of stirred pulp-mixing in flotation

    Li, Zhen   Zhao, Chengqian   Zhang, Huaiqing   Liu, Jiongtian   Yang, Chao   Xiong, Shanxin  

    With the increasing demands for the high efficiency of pulp-mixing, which is adapted to the fine particles entering into flotation section, an intensification pulp-mixing device with novel design has been developed. On the basis of numerical simulation, which indicated efficient circulation and shear effect of the "maleic-cutting" configuration equipped with static-guide-blade, the power dissipation amount P-v, mixing time theta(m), power number N-P, mixing time number N-theta, C-S which reflects shear property, suspension percentage phi/Phi(%), and concentration variance sigma(2) were measured, analyzed and compared with the ordinary agitated tank. Combining with actual mineral separation tests, performance of the efficient pulp-mixing device characterized by "multi-stage and compulsory" has been validated: the "multi-stage and compulsory" mixing device corresponds to a different circulation/shear energy; under the same operating conditions, the absolute advantages in the aspect of mixing time are the root cause for the increase of mixing efficiency; the "maleic-cutting" configuration is less influenced by pulp-mixing time and has the characteristics of achieving fast mixing; the strong shear effect mechanism is the root cause for the realization of pulp-mixing intensification on fine-particle and microfine-particle materials. Therefore, the "multi-stage and compulsory" mixing device designed by this research successfully accomplished intensification of pulp-mixing effect.
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  • pH-controlled dispersion of micro-fine siderite from hematite and quartz

    Hao, Haiqing   Li, Lixia   Yuan, Zhitao   Liu, Jiongtian  

    To reduce the heterocoagulation of siderite with hematite and quartz, the controlled dispersion of micro-fine siderite was investigated at different pH values. The dispersion ratio, particle size distribution (PSD) and supernatant turbidity of suspension, and the direct flotation index were used to characterize the pH-controlled dispersion. Based on the lower dispersion ratio (ca. 40%) of the micro-fine siderite and the smallest difference between the experimental and ideal turbidities of the mixed suspension, micro-fine siderite homocoagulation was sustained at an approximate pH of 7, under which heterocoagulation was suppressed. Therefore, the controlled dispersion of the micro-fine siderite could be realized under a neutral condition. DLVO calculations revealed that the total interaction energy between the micro-fine siderite and the other two minerals tended to zero at pH of 7. However, at other pH values involving either a repulsive or attractive DLVO energy, the heterocoagulation between micro-fine siderite and the other two minerals was accelerated. A preferable controlled dispersion of micro-fine siderite can be achieved by maintaining a neutral condition at DLVO energies close to zero. The direct flotation of siderite revealed that a concentrate with FeO content of 16.31% and FeO recovery of 61.57% was recovered at a pH of 6.8. The greatest difference between FeO recovery and TFe recovery was 24.04%, indicating the suppressed heterocoagulation. Therefore, a neutral condition is favorable for the controlled dispersion of siderite from hematite and quartz. (C) 2018 Elsevier B.V. All rights reserved.
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  • Process intensification of stirred pulp-mixing in flotation

    Li, Zhen   Zhao, Chengqian   Zhang, Huaiqing   Liu, Jiongtian   Yang, Chao   Xiong, Shanxin  

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  • The effect of calcium ions on coal flotation

    Zhang, Zhijun   Zhang, Hanyu   Nong, Haitao   Liu, Jiongtian  

    Laboratory and field experiments were carried out to study the effect of calcium ions on coal flotation. Tap water and recycled water were used as flotation water in the laboratory experiments. Gypsum and potassium sulfate were used as modifying agents to adjust the water chemistry of flotation water. Gypsum was also used as a modifying agent to adjust the Ca2+ concentration of flotation water in field experiments. Both tap water and recycled water were used as flotation water in laboratory flotation tests, of which the results indicated that cleans ash increased by 1-2% with the increase of Ca2+ concentration. No obvious effect was found on cleans yield. The cleans ash gradually increased with the increase of Ca2+ concentration which is less than 5 mmol/L. Further increasing the concentration of Ca2+ did not cause further increase in cleans ash, but there was a slight fluctuation because of experimental error. The field flotation results indicated that cleans ash increased by 1.1% with the increase of Ca2+ concentration, which was consistent with the results of laboratory flotation tests. Since calcium ions had a negative effect on coal flotation, the dosage of gypsum used to treat coal tailings water should be controlled optimally.
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  • Bubble size distribution in cyclonic zone of a novel flotation column

    Deng, Xiaowei   Xing, Baolin   Liu, Jiongtian   Zhang, Chuanxiang   Shi, Changliang   Lu, Yang  

    In order to investigate bubble size distribution (BSD) in the cyclonic flotation column, a series of tests were conducted to study flow velocity distribution (FVD) and BSD by using the method of particle image velocimetry (PIV). Foaming performance of the n-octyl alcohol is more applicable than both of n-butyl alcohol and terpenic oil. At different circulation volume conditions, BSD range lies in 0-800 m, and a large number of tiny bubbles (<90 m) are generated. Besides, the curve presents a normal distribution in 90-180 m. With the increase in circulation volume, bubble size decreases. BSD determined by cyclonic flow effect plays a crucial role on bubble mineralization with fine particle in cyclonic zone of the flotation column.
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  • Drag Coefficient Prediction of a Single Bubble Rising in Liquids

    Yan, Xiaokang   Zheng, Kaixin   Jia, Yan   Miao, Zhenyong   Wang, Lijun   Cao, Yijun   Liu, Jiongtian  

    The motion of single bubbles rising in 2-octanol solutions was investigated experimentally. By using a high-speed video system to follow the rising bubble, the sequences of the recorded frames were digitized and analyzed using image analysis software. The periodical fluctuation of the bubble terminal velocity was observed, which is indicative of a nonconstant bubble drag coefficient. Then, the measured drag coefficient was compared with correlations available in the literature. The comparison shows that these correlations cannot give fully satisfactory results in predicting the fluctuated drag coefficient. Using the extensive experimental data, the authors proposed a new correlation to predict the drag coefficient calculated from the fluctuated motion with the added mass force and history force included. In virtue of nonlinear curve fitting, the drag coefficient of the single bubble is correlated as a function of the Re number, Eo number, We number, and Mo number based on the equivalent bubble diameter. This new model successfully predicts the periodical fluctuations of the drag coefficients. For the standard drag prediction (when averaged terminal velocity is used), this model agrees better with our experimental results and has a maximum relative error of 2.2% and an average relative error of 0.87%. This model is also verified by bubble rising in methyl isobutyl carbinol cas (MIBC) and OP-10 (C32H58O10) aqueous solutions, and the errors are similar to that of 2-octanol solutions. On the basis of a comparison with measurements in other liquids from the literature, this new correlation represents well the experimental data which covers 21 pure liquids and contaminated liquids in a very wide range of parameters as follows: 10(-3) <=3D Re <=3D 10(5), 10(-2) <=3D Eo <=3D 10(3), and 10(-14) <=3D Mo <=3D 10(7). This work is an extension of our previous one (Yan et al. Chem. Eng. J. 2017, 316, 553) in which the old correlation predicts the fluctuated drag coefficient for bubble rising in pure water.
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  • Effect of water hardness on the settling characteristics of coal tailings

    Zhang, Zhijun   Nong, Haitao   Zhuang, Li   Liu, Jiongtian  

    Water hardness has an important effect on the settling characteristics of coal tailings. This article is mainly on a research of the relationship between water hardness and the settling performance of coal tailings. Samples from five coal preparation plants were used for mineralogical and water chemistry analyses by the X-ray diffraction (XRD) technique and the ion chromatograph technique, which showed that the water hardness of the recycled water was determined by the mineral composition of coal slimes. The settling tests indicated that water hardness of the sample water was closely related to mineral composition and could be used to evaluate the settling characteristics. It was shown that the increase of water hardness resulted in the increase of settling rate and the transmittance of supernatants. A gradual decrease of the slope was obtained in the curves of settling rate and transmittance. Verification tests on settling rate and transmittance of five coal samples were in agreement with the claim. The Zaozhuang and Datun samples, whose water hardness was at a high level (over 90 degrees DH), achieved the settling rate over 19 cm/min and transmittance of supernatant over 89%. Settling rate and transmittance of the supernatant are below 12 cm/min and 41%, respectively, for the Xingtai, Shitai, and Linhuan samples, whose water hardness is below 10 degrees DH.
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  • Flow field simulation of agitating tank and fine coal conditioning

    Huang, Gen   Liu, Jiongtian   Wang, Lijun   Song, Zhihao  

    Numerical simulation was performed to predict the flow field parameters in an agitating tank. The relationship between characteristic parameters, impeller size, and agitating speed was studied. The conditioning and flotation tests were conducted by using fine coal from Henan province in China. Based on the simulation results, the effects of velocity, shear rate, and power consumption on conditioning and flotation processes were discussed. Maximum shear rate had more notable influence on fine coal flotation indices than fluid velocity and average shear rate. The agitating mode of smaller diameter with higher speed had better performance and lower power consumption than larger diameter with lower speed for fine coal conditioning. Particle size analysis indicated that the combustible recovery and flotation efficiency of the -0.074 mm fraction significantly increased with the increase of maximum shear rate. (C) 2016 Elsevier B.V. All rights reserved.
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  • Effects of Energy Input on the Laboratory Column Flotation of Fine Coal

    Xing, Yaowen   Gui, Xiahui   Liu, Jiongtian   Cao, Yijun   Lu, Yu  

    This study explored the effects of energy input and different energy increase patterns on the separation performance of a laboratory cyclonic-static microbubble flotation column in fine coal flotation. The energy input was changed by adjusting the circulating pump power and pulp residence time. Continuous flotation tests were designed by using five feed rates (i.e., different pulp residence time), which were 53.33, 80.00, 106.40, 133.60, and 160.00 g/min, and various useful power of the circulating pump (22.44, 30.14, 38.50, 46.86, 56.10, and 64.46 W). Results show that concentrate combustible recovery initially increased before reaching saturation distribution with increasing energy input absolute value. An ash content of 10.90% and combustible matter recovery of 92.84% were obtained at the energy input of 10098.00 J which is called the flotation saturation energy Es. Es is the essential condition and guarantee for a complete flotation process. A low ash content of clean coal was obtained with low energy input. With the increase of energy consumption, the additional coals recovered were coarse particles with low ash content and fine particles with high ash content. However, the ash content did not exhibit a significant change with the increase of energy input in this investigation. During the flotation process, a minimum critical flotation time T and critical circulation pump useful power P are required. If the P and T of a variable are less than the critical value, high combustible matter recovery could not be obtained by adding another variable to increase energy input. A reasonable mode of energy input was proposed that the absolute value of the energy input reaches Es; meanwhile, it ensures that each value of the P and T is greater than the critical values.
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  • Cyclonic state micro-bubble flotation column in oil-in-water emulsion separation

    Li, Xiaobing   Xu, Hongxiang   Liu, Jiongtian   Zhang, Jian   Li, Jing   Gui, Zhaolong  

    In order to improve the separation efficiency of oil-in-water emulsion, a novel cyclonic state micro-bubble flotation column was developed to enhance the separation efficiency. The flotation column comprises a column separator and a cyclonic separator provided on the bottom plate of the flotation apparatus. The process parameters, namely the feed volume flow rate, initial oil concentration, aeration rate, and oil droplet size on removal efficiency were investigated. The process efficiencies between the cyclonic state micro-bubble flotation column (FCSMC) and dissolved air flotation column (DAF) were compared. Results show that this FCSMC has higher oil removal efficiency and treated water with lower oil levels than the DAF, especially for the process of fine oil droplets (<10 mu m). An oil removal efficiency of 92.19% was obtained with the treated wastewater effluent containing a final oil concentration of 37.10 mg/L using FCSMC (an oil removal efficiency of 76.65% with a final oil concentration of 110.92 mg/L using DAF) under conditions as following: a 18.75 min of residence time, a 475.05 mg/L of initial oil concentration, a 1.8 L/min of aeration rate and a 25.01 mu m of mean oil droplet size in feed. The mean oil droplet size is 1.84 mu m with 4.81% of the oil droplets above 5 gm in diameter in the treated effluent. It shows that the FCSMC is especially advantageous for the separation of fine oil droplets. (C) 2016 Published by Elsevier B.V.
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  • PROCESS AND SYSTEM FOR UPGRADING LIGNITE BY VIBRATION HOT-PRESSING DEHYDRATION

    A process and system for upgrading lignite by vibration hot-pressing dehydration, belonging to processes and systems for coal processing and cleaning. The system: a discharge port of a raw coal bin is connected with a feed port of a fan-milled powder pre-drying device, a discharge port of the fan-milled powder pre-drying device is connected with a feed port of an upgrading device by vibration hot-pressing dehydration through a powdered coal bin and a distributing device, a steam generating device is connected with a steam inlet of the upgrading device by vibration hot-pressing dehydration through a steam switching valve, a water outlet of the vibration hot-pressing dehydration upgrading device is connected with the inlet of the upgrading device by vibration hot-pressing dehydration at one end and is discharged through a waste water purification system at another end, via a three-way valve; the process: the fan-milled coal powders are conveyed into the upgrading device by vibration hot-pressing dehydration, is preheated and then sealed, steam is introduced into the device to heat the coal until the coal is heated to the process temperature, then the introduction of steam is stopped and the coal is dewatered and formed. The lignite can be efficiently dehydrated and formed in a relatively short time under comparatively mild process conditions, preventing reabsorption and spontaneous combustion, so that the lignite can be conveniently stored and transported.
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  • Cyclonic flotation column of siliceous phosphate ore

    Li, Guosheng   Cao, Yijun   Liu, Jiongtian   Wang, Dapeng  

    The introduction of cyclonic circulation method is one of the most important developments in column flotation technology in the last years. In this study, effect of a cyclonic flotation column on the flotation performance of a siliceous phosphate ore was evaluated by the experiments on circulation pressures and circulation methods. The feed and flotation products were characterized by size fraction, X-ray diffraction and X-ray fluorescence. The results showed that both of the P2O5 grade and recovery of the concentrate increased with circulation pressure under the condition of cyclonic circulation. Under the optimal circulation pressure 0.24 Mpa, Flotation comparison results at different circulation methods showed that the P2O5 recovery for cyclonic circulation reached 86.03%, which was increased by 4.9 percentage points comparing with that of direct flow circulation. The size analysis of the products demonstrated that cyclonic circulation method promoted the recovery of fine particles. Theoretical analysis results show that centrifugal force field can reinforce the mineralization of fine particles as well as decrease the lower limit for efficient flotation. (C) 2012 Elsevier B.V. All rights reserved.
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  • A rule-based intelligent method for fault diagnosis of rotating machinery

    Dou, Dongyang   Yang, Jianguo   Liu, Jiongtian   Zhao, Yingkai  

    To better equip with a non-expert to carry out the diagnosis operations, a new method for intelligent fault identification of rotating machinery based on the empirical mode decomposition (EMD), dimensionless parameters, fault decision table (FDT), MLEM2 rule induction algorithm and improved rule matching strategy (IRMS) is proposed in this paper. EMD is used to preprocess the vibration signals for mining the fault characteristic information more accurately. Then, dimensionless parameters are extracted from both the decomposed signals in time domain and envelop spectrum in frequency domain respectively to form the conditional attributes of a FDT. Moreover, MLEM2 algorithm is run directly on the FDT to generate decision rules imbedded in the data. To make the following classification process more robust, the IRMS is adopted to resolve the conflicting and non-matching problems. Finally, data of rolling element bearings with four typical working conditions is used to evaluate the performance of the proposed method. The testing result demonstrates that the method has high accuracy and systematically good performance. It is proved to be a convenient, concise, interpretable and reliable way to diagnose bearings' faults. The advantages are also confirmed by the comparisons with the other two approaches, i.e. the principal component analysis (PCA) and probabilistic neural network (PNN) based method as well as the wavelet transform (WT) and genetic algorithm (GA) based one. Furthermore, thank to the FDT working as a data interface, the method is more transplantable, therefore it may be applied to diagnose other types of rotating machines effectively. (C) 2012 Elsevier B.V. All rights reserved.
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  • Preconcentration of ultrafine ilmenite ore using a superconducting magnetic separator

    Shen, Shuaiping   Yuan, Zhitao   Liu, Jiongtian   Meng, Qingyou   Hao, Haiqing  

    The ilmenite lain in ultrafine ilmenite ore cannot be treated easily. In this study, a superconducting magnetic separator (SMS) was proposed to preconcentrate the ultrafine ilmenite. During this process, the essential condition for capturing the ilmenite from the ultrafine ore, key technology for obtaining an efficient preconcentration, and analysis of the ilmenite concentrates were investigated with theoretical descriptions, statistically designed experiments, and scanning electronic microscopy (SEM) detection, respectively. The descriptions and experiments indicated that the grade and recovery of ilmenite concentrate can be increased by the high-velocity slurry and high-intensity magnetic field, respectively; the synergy of the slurry velocity and magnetic intensity was demonstrated to be the key technology to improve the preconcentration efficiency. The SEM analysis demonstrated that the minimal agglomeration between ultrafine minerals in SMS further benefited the efficient preconcentration. Hence, the SMS provides an efficient way to preconcentrate ultrafine ilmenite ore. (C) 2019 Elsevier B.V. All rights reserved.
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  • The Investigation of Humics as a Binder for LiFePO4 Cathode in Lithium Ion Battery

    Han, Guihong   Yang, Shuzhen   Liu, Jiongtian   Huang, Yanfang  

    Binder, as a necessary functional material of electrode in lithium ion battery, has a vital influence on the electrochemical performance. The humics, coupled with polyacrylamide (PAM) and sodium carboxymethyl cellulose (CMC), were used as a water-soluble binder for LiFePO4 (LFP) cathode using in lithium ion battery. The techniques of cyclic voltammetry (CV) and galvanostatic charge-discharge were conducted to evaluate the performance of humics binder in LFP electrode. The reversible specific capacity of LFP (HA + PAM + CMC) electrode can reach to 142 mAh g(-1) after 50th cycling (100 mAh g(-1)) on conditions of raw materials with 1 wt% PAM addition, humics and CMC with a mass ratio of 3:1 in binder, and the raw materials mixed in an interval order. Humics has the potential to be used as a novel, eco-friendly and high-efficient binder for lithium-ion battery.
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  • Cyclonic separation process intensification oil removal based on microbubble flotation

    Liu, Jiongtian   Xu, Hongxiang   Li, Xiaobing  

    The cyclonic-static microbubble flotation column has dual effects including the cyclonic separation and floatation separation with the characteristics of the small lower limit of the effective separation size, short separation time, large handling capacity, and low operation cost. It shows significant advantages in the oily wastewater treatment field, especially the polymer flooding oily wastewater treatment aspect. In this paper, the cyclonic separation function mechanism of the cyclonic-static microbubble flotation column was studied, the impact of the parameters including the feeding rate, aeration rate, circulating pressure, and underflow split ratio on the cyclonic separation efficiency was investigated, and the cyclonic separation efficiency model was established as well. In addition, by applying the Doppler Laser Velocimeter (LDV) and Fluent simulation software, the test and simulation to the single-phase flow velocity field of the cyclonic separation section of the cyclonic-static microbubble flotation column were carried out, and the velocity distribution rule of the cyclonic separation section was analyzed under the single-phase flow conditions.
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