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Effects of particle size and concentration on bubble coalescence and froth formation in a slurry bubble column

Particuology 2018年第1期16卷 82-95页

作者： A.R. Sarhan J. Naser G. Brooks Department of Mechanical and Product Design Engineering Swinburne University of Technology Hawthorn Victoria 3122 Australia Department of Mechanical Engineering University ofAnbar Ramadi Anbar 31001 lraq

A new approach for simulating the formation of a froth layer in a slurry bubble column is proposed. froth is considered a separate phase, comprised of a mixture of gas, liquid, and solid. The simulation was carried out using commercial flow simulation software （FIRE v2014） for particle sizes of 60-150 μm at solid concentrations of 0-40vol%, and superficial gas velocities of 0.02-0.034m/s in a slurry bubble column with a hydraulic diameter of 0.2 m and height of 1.2 m. Modelling calculations were conducted using a Eulerian-Eulerian multiphase approach with k-ε turbulence. The population balance equations for bubble breakup, bubble coalescence rate, and the interfacial exchange of mass and momentum were included in the computational fluid dynamics code by writing subroutines in Fortran to track the number density of different bubble sizes. Flow structure, radial gas holdup, and Sauter mean bubble diameter distributions at different column heights were predicted in the pulp zone, while froth volume fraction and density were predicted in the froth zone. The model was validated using available experimental data, and the predicted and experimental results showed reasonable agreement. To demonstrate the effect of increasing solid concentration on the coalescence rate, a solid-effect multiplier in the coalescence effi- ciency equation was used. The solid-effect multiplier decreased with increasing slurry concentration, causing an increase in bubble coalescence efficiency. A slight decrease in the coalescence efficiency was also observed owing to increasing particle size, which led to a decrease in Sauter mean bubble diam- eter. The froth volume fraction increased with solid concentration. These results provide an improved understanding of the dynamics of slurry bubble reactors in the presence of hydrophilic particles.

关键词： Computational fluid dynamics Slurry concentration Gas holdup Particle size froth Coalescence efficiency

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2<sup>k</sup>Factorial Experiments on Factors that Influence the Recovery of Gold during the Upgrade of Ilesha-Itagunmodi Gold Ore through froth Flotation

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Journal of Minerals and Materials Characterization and Engineering 2014年第1期2卷 32-39页

作者： Kayode Emmanuel Oluwabunmi Abraham Adewale Adeleke Adelana Razak Adetunji Samson Olaitan Jeje Abiodun Ayodeji Abioye Olusola Adedayo Adesina Fatai Afolabi Ayeni Folahan Peter Ibitoye Department of Chemical Engineering Landmark University Omu-Aran Nigeria Materials Science and Engineering Obafemi Awolowo University (O.A.U.) Ile-Ife Nigeria Prototype Engineering Development Institute (PEDI) Ilesa Nigeria Prototype Engineering Development Institute (PEDI) Ilesa Nigeria Materials Science and Engineering Obafemi Awolowo University (O.A.U.) Ile-Ife Nigeria

A low-grade gold ore from Ilesha-Itagunmodi, south western Nigeria was panned, dried and ball-milled before sieving into fractions. The morphological, mineralogical and chemical composition was studied by optical micro-scopy (Reflected and Transmission), X-ray diffraction (XRD) and Energy Dispersive X-ray fluorescence (XRF), respectively. The sieved fractions were subjected to chemical analysis (AAS). The +106 μm sieve had the highest concentration of the mineral and was then selected for the upgrade through froth flotation using standard reagents. In this paper a report on a 2k factorial experiment that provides an understanding of the impact of operational variables on the quantity of gold mineral obtained from the ore during froth flotation is presented. Analysis results showed that Ilesha-Itagunmodi gold ore is non-refractory with fine grain particles, amenable to froth flotation and contained about 20 other associated minerals, gold had a concentration of about 0.0024%. A com-bination of P-Xanthate and amine glycol collectors at a pH of 9.2 only produced a considerable increase in gold yield. This translated to about 87.13% increase in recovery of gold from the ore. Analysis of variance (ANOVA) was carried out and the model equation obtained was subsequently optimised to obtain a model equation that could be used in predicting the recoverable quantity of gold, indicating that F11,1-values for Collector concentration, frother concentration, pH and Conditioning time were 156.86, 6.96, 43.81, and 56.77 respectively. A model with an F value of 88.41 was obtained which indicated that the model was significant. The model equation obtained was subsequently optimised to be able to predict the recoverable quantity of gold. A “Pred R-Squared” value of 0.9365 (93.65%) was also obtained and is in reasonable agreement with the “Adj R-Squared” value of 0.9534 (95.34%). It was established that Ilesha placer gold ore is amenable to froth flotation using standard reagents.

关键词： Factorial froth Flotation Collector frother Concentration Surface Graph Conditioning Time

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The Method of Flotation froth Image Segmentation Based on Threshold Level Set

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Advances in Molecular Imaging 2015年第2期5卷 38-48页

作者： Ji Zhao Huibin Wang Lina Zhang Conghui Wang Department of Software Engineering University of Science and Technology Liaoning Anshan China

A novel flotation froth image segmentation based on threshold level set method is put forward in view of the problem of over-segmentation and under-segmentation which occurs when the existing method segmented the flotation froth images. Firstly, the proposed method adopts histogram equalization to improve the contrast of the image, and then chooses the upper threshold and lower threshold from grey value of histogram of the image equalization, and complete image segmentation using the level set method. In this paper, the model which integrates edge with region level set model is utilized, and the speed energy term is introduced to segment the target. Experimental results show that the proposed method has better segmentation results and higher segmentation efficiency on the images with under-segmentation and incorrect segmentation, and it is meaningful for ore dressing industrial.

关键词： Flotation froth Image Segmentation Active Contour Model Histogram Equalization Speed Function Threshold Level Set

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Flotation Control System Based on Recognition of froth Image

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International Journal of Mining Science and Technology 2000年第2期21卷 42-44页

作者：王振翀路迈西陈浚赵建庆

In industrial flotation, froth layer plays an important role and reflects directly whether coal, air, water and reagents match each other properly or not and whether the quality of flotation is good or not. So the supervision and recognition of the state of froth layer is very important in the flotation process. The ash content of clean coal froth was predicted through extracting the features of images of flotation froth. The froth images were classified according to their structure. A control system of adding flotation reagents was established based on the LVQ neural net.

关键词： froth image recognition control system

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Effect of pyrite content of feed and configuration of locked particles on rougher flotation of copper in low and high pyritic ore types

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International Journal of Mining Science and Technology 2018年第2期28卷 167-176页

作者： Sahar Agheli Ahmad Hassanzadeh Behzad Vaziri Hassas Mohammad Hasanzadeh Mining Engineering Department Shahid Bahonar University of Kerman Faculty of Mines Mineral Processing Engineering Department Istanbul Technical University Department of Mineral Resources Engineering Montan University of Leoben College of Mines and Earth Science University of Utah Drug Applied Research Center Tabriz University of Medical Sciences

Misreported pyrite into copper concentrates dramatically declines copper grade and recovery. Copper flotation can be also more complicated if flotation feed comes from an elevated-pyritic copper ore. In this investigation, the effect of two different ore types(high pyritic and low pyritic feeds) was studied on rougher stage of industrial copper flotation circuit. Samples were taken from different streams and the structure of chalcopyrite within the pyrite and non-sulfide gangue minerals was examined in various size fractions for mentioned ore types. Results indicated that 72% and 56% of the total floated pyrite was transferred to concentrate in first four cells in the low and high pyritic feeds, respectively. Whereas, this proportion for floated SiO_2 in last ten cells was detected as 72% and 71%, respectively. A detailed interpretation of the effect of locked particles in different size fractions on rougher flotation cells is studied from industrial point of view.

关键词： Liberation degree High pyritic feed Pyrite froth flotation Chalcopyrite

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CFD model simulation of bubble surface area flux in flotation column reactor in presence of minerals

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International Journal of Mining Science and Technology 2018年第6期28卷 999-1007页

作者： A.R.Sarhan J.Naser G.Brooks Department of Mechanical and Product Design Engineering Swinburne University of TechnologyHawthornVictoria 3122Australia Department of Mechanical Engineering University of Anbar RamadiAnbar 31001Iraq

Bubble surface area flux(S_b) is one of the main design parameter in flotation column that typically employed to describe the gas dispersion properties, and it has a strong correlation with the flotation rate constant. There is a limited information available in the literature regarding the effect of particle type,density, wettability and concentration on Sb. In this paper, computational fluid dynamics(CFD) simulations are performed to study the gas–liquid–solid three-phase flow dynamics in flotation column by employing the Eulerian–Eulerian formulation with k-e turbulence model. The model is developed by writing Fortran subroutine and incorporating then into the commercial CFD code AVL FIRE, v.2014.This paper studies the effects of superficial gas velocities and particle type, density, wettability and concentration on Sband bubble concentration in the flotation column. The model has been validated against published experimental data. It was found that the CFD model was able to predict, where the response variable as indicated by R-Square value of 0.98. These results suggest that the developed CFD model is reasonable to describe the flotation column reactor. From the CFD results, it is also found that Sb decreased with increasing solid concentration and hydrophobicity, but increased with increasing superficial gas velocity. For example, approximately 28% reduction in the surface area flux is observed when coal concentration is increased from 0 to 10%, by volume. While for the same solid concentration and gas flow rate, the bubble surface area flux is approximately increased by 7% in the presences of sphalerite.A possible explanation for this might be that increasing solid concentration and hydrophobicity promotes the bubble coalescence rate leading to the increase in bubble size. Also, it was found that the bubble concentration would decrease with addition of hydrophobic particle(i.e., coal). For instance, under the same operating conditions, approximately 23% reduction in the bubble concentration is predicted wh

关键词： CFD froth flotation Bubble surface area flux Solid properties Bubble concentration

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Flow field in air-sparged hydrocyclone

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中国有色金属学会会刊：英文版 1994年第3期4卷 30-35页

作者： Chu, Liangyin Luc, Qian Northwestern Univ Shenyung China

ＦＬＯＷＦＩＥＬＤＩＮＡＩＲ－ＳＰＡＲＧＥＤＨＹＤＲＯＣＹＣＬＯＮＥＣｈｕ，Ｌｉａｎｇｙｉｎ；Ｌｕｏ，Ｑｉａｎ（ＭｉｎｅｒａｌＥｎｇｉｎｅｅｒｉｎｇＤｅｐａｒｔｍｅｎｔ，Ｐ．Ｏ．Ｂｏｘ１３９ＮｏｒｔｈｅａｓｔｅｒｎＵ... 详细信息

ＦＬＯＷＦＩＥＬＤＩＮＡＩＲ－ＳＰＡＲＧＥＤＨＹＤＲＯＣＹＣＬＯＮＥＣｈｕ，Ｌｉａｎｇｙｉｎ；Ｌｕｏ，Ｑｉａｎ（ＭｉｎｅｒａｌＥｎｇｉｎｅｅｒｉｎｇＤｅｐａｒｔｍｅｎｔ，Ｐ．Ｏ．Ｂｏｘ１３９ＮｏｒｔｈｅａｓｔｅｒｎＵｎｉｖｅｒｓｉｔｙ，Ｓｈｅｎｙａｎ...

关键词： air-sparged hydrocyclone flow field froth flotation centrifuge process

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PRESSURE　DISTRIBUTION　IN　THE　AIR-SPARGED　HYDROCYCLONE

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中国有色金属学会会刊：英文版 1994年第4期4卷 20-24,28页

作者： Chu, Liangyin Luo Qian(Mineral Engineering Department,Northeastern University, Shenyang 110006)

ＰＲＥＳＳＵＲＥＤＩＳＴＲＩＢＵＴＩＯＮＩＮＴＨＥＡＩＲ－ＳＰＡＲＧＥＤＨＹＤＲＯＣＹＣＬＯＮＥ￥Ｃｈｕ，Ｌｉａｎｇｙｉｎ；ＬｕｏＱｉａｎ（ＭｉｎｅｒａｌＥｎｇｉｎｅｅｒｉｎｇＤｅｐａｒｔｍｅｎｔ，Ｎｏｒｔｈｅａｓｔ... 详细信息

ＰＲＥＳＳＵＲＥＤＩＳＴＲＩＢＵＴＩＯＮＩＮＴＨＥＡＩＲ－ＳＰＡＲＧＥＤＨＹＤＲＯＣＹＣＬＯＮＥ￥Ｃｈｕ，Ｌｉａｎｇｙｉｎ；ＬｕｏＱｉａｎ（ＭｉｎｅｒａｌＥｎｇｉｎｅｅｒｉｎｇＤｅｐａｒｔｍｅｎｔ，ＮｏｒｔｈｅａｓｔｅｒｎＵｎｉｖｅｒｓｉｔｙ，Ｓｈｅ...

关键词： air-sparged hydrocyclone pressure distribution froth flotation centrifuge process

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Surface Characterization of Metallic Particles in Printed Circuit Board Comminution Fines and the Processing Implication

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Journal of Minerals and Materials Characterization and Engineering 2012年第6期11卷 619-629页

作者： Iyiola Olatunji Ogunniyi M. K. G. Vermaak Dick Groot Materials Science and Metallurgical Engineering University of Pretoria South Africa Metallurgical and Materials Engineering Federal University of Technology Akure Nigeria

From the background of poor responses of metallic particles in printed circuit board comminution fines to chemical conditioning froth flotation schemes, contrary to expectations based on native metal flotation, surface studies were carried out on samples of these metallic particles in quest for the probable causatives. Auger electron spectroscopy combined with argon beam depth profiling was employed in studying the surface make-up of the metal particles. The composition profiles down to 340 nm surface depth obtained showed that the supposed metallic particles consist of organics, oxides, and various trace alloys different from the bulk material of the particles. The profiles reveal the peculiar surfaces of the particles and the matrix from which the particles were liberated. The study provides insight for better appraisal of the flotation system the sample presents. Implementing chemical conditioning flotation scheme on this sample must carefully consider the peculiar surface make up in contrast to native metal occurrences.

关键词： surface characterization metallic particles auger electron spectroscopy printed circuit board froth flotation.

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