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By Francesco Vegliò, Luigi Toro, Francesca Beolchini, Francesca Pagnanelli, Stefano Ubaldini

"Biosorption is an innovative technology used to remove heavy metals from aqueous solutions from mining waters and other industrial wastes. A wider application of this alternative process is strictly dependent on the understanding of the chemico-physical aspects involved, in order to optimize the operating conditions. Mechanistic models are the most useful tools used for understanding purposes, even if the empirical models are still widely applied for their simplicity.In this paper especially propagated biomasses of Sphaerotilus natans, calcium alginate and some waste materials were tested as adsorbents for single and binary solutions containing heavy metals at different pH. The equilibrium experimental results were fitted according to empirical and physical models with growing complexity outlining the inadequacy of the predictive models; in fact, the non-ideal interactions among metals require the insertion of additional correction parameters."

Jan 1, 2003

By Eduard Stefanescu, James M. Mwase, Egon Sehner, Stoyan Gaydardzhiev

"The study is focused on investigating the production of synthetic rutile of 95% purity or higher from a Norwegian ilmenite ore concentrate. This was to be achieved using a sequential process involving oxidative-reductive roasting at 975°C, followed by magnetic separation to further concentrate the sample and finally leaching with 20% HCl to remove mostly Fe-based impurities leaving behind synthetic rutile. The key process parameters considered were roasting time (1 and 2 hrs), leaching temperature (100, 125 and 145°C), pulp density (15 and 25wt%) and leaching time (3 and 6 hrs). The option of directly leaching the concentrate without pre-treatment was also evaluated. Test work was conducted using samples screened to a size fraction of 105-212 µm. Samples were leached in a 1 L glass autoclave. The reactor was hermetically sealed and thus the resulting pressure was not controlled but was dependent on the process temperature. The product from leaching was calcined and analysed via XRD and SEM to determine the purity of the product. The magnetic separation step was found to be ineffective and discontinued early in the study. Thus far a product with 97% synthetic rutile purity as analysed by SEM has been produced by directly leaching the concentrate at a temperature of 145°C, pulp density of 25wt% and leaching time of 6 hrs.INTRODUCTION The study investigates the use of a process route comprising oxidative-reductive roasting, followed by magnetic separation and then hydrochloric acid leaching and calcination to produce synthetic rutile from ilmenite concentrate. The grade of synthetic rutile produced should be suitable for chlorination to produce pigment grade TiO2. Hence the proposed process should produce a product consisting of no less than 95% synthetic rutile. Additionally, the product should have no more than 1.5wt% combined content of CaO and MgO (Zhang et al., 2011) as they tend to form high-boiling-point chloride leading to the malfunctioning of fluidized bed chlorinator (Cardarelli, 2008). Finally the product should have no more than 2.1wt% of Fe2O3."

Jan 1, 2018

By Saveliy F. Kaplan, Valeriy N. Tsyplakov, Vasily N. Kovalev, Igor A. Agapov, Nikolai V. Vorob’ev-Desyatovskii

"Based on the experiments, a possibility of successful processing of double-refractory gold sulphide concentrates with a high content of natural organic carbon, which has a high sorption capacity toward gold chloride complexes, has been demonstrated. The proposed approach involves deep burnout of sorption-active organic carbon in an autoclave at a higher temperature and a longer retention time. INTRODUCTION It is known that one of the reasons why gold-bearing ores and concentrates are refractory is the occurrence of fine gold in sulphides (usually in pyrite and arsenopyrite) in ores and concentrates. In addition, refractory gold-bearing ores and concentrates also contain an organic carbonaceous material, which has a sorption capacity towards gold chloride complex, making the ore or concentrate even more refractory. In pressure oxidation, metallic gold is oxidized by Fe (III) aqua-ions and complex Au(Cl)4- ions are formed at temperatures over 180°C, in the presence of chlorides contained in ores. Complex gold anion is adsorbed on the organic carbon surface and then reduced to Au0; the chloride ion is regenerated and gold, adsorbed on organic carbon microparticles, is ultimately transferred to tailings (preg-robbing). Currently, there are several suggestions how to suppress preg-robbing (Simmons, 1998, Pyke, 1999, Rees, van Deventer, 2000, Zhao Jun-wei, 2008). It can be done by reducing the organic carbon content by processing (flotation, etc.),reducing chloride ion concentration by preliminary washing of concentrates in thickeners, reducing the adsorption capacity of organic carbonaceous material by introducing some organic substances that are strongly adsorbed on its surface (blanking agents), and reducing the redox potential of the slurry liquids by introducing neutralizing agents (limestone)."

Jan 1, 2018

By Xingshi Yang, Ghislain Bournival, Seher Ata

"Particle-laden interfaces are a fundamental research topic in froth flotation since the process involves particle-coated bubbles in both the pulp and the froth phase. In most experimental studies the characteristics of the particle layer in multi-bubble systems are poorly defined. An experimental setup has been developed based on a Langmuir-Blodgett (L-B) trough. The modified trough allowed introducing an air bubble beneath the particle monolayer formed at the air-water interface which made the study of the interaction between the bubble and the monolayer under various pH values possible. The monolayer characteristics of the particles were also studied and compared in terms of surface pressure (?-A) isotherms and packing factor. On compression, the particles formed branched structure at high pH whereas a uniform monolayer was formed at lower pH. Observations related to the behavior of particles during compression and expansion cycles, and the coalescence of a bare bubble with the flat particle laden interface were provided and the implication of the results for flotation process was discussed.INTRODUCTIONFroth flotation is known for its versatility and ability to concentrate low-grade, complex ores. It is considered a physico-chemical process in which particles attach to air bubbles, depending on their hydrophobicity as well as other factors, and are carried to the surface to form a froth layer. Reagents are used to stabilize bubbles and the froth layer (Pugh, 1996). However, particles, which are carried by the bubbles or entrained, significantly contribute to the stability of the froth phase (Ata et al., 2003; Zanin et al., 2009; Bournival et al., 2015a). Their relevance in mineral processing has led to a number of fundamental studies on the effect of particles and their properties on the process of froth flotation.Flotation systems are particularly difficult to characterize due to the broad range of properties of particles (e.g. size, liberation, hydrophobicity, etc.) and inconsistent operational conditions (e.g. changes in water quality, reagent addition, etc.). Several studies have made the use of well characterized particles in laboratory conditions. Such studies allowed the finding of an optimal contact angle for the stabilization of the froth phase (Johansson and Pugh, 1992; Ata et al., 2002). Froths have a large number of bubbles so that individual interactions are not observed. The study of two bubbles allows to determine the stability of the bubbles, with particles, and to some extend the stability of the bubble-particle aggregate (Gourram-Badri et al., 1997; Bournival et al., 2015b). The removing of particles between two bubbles may also be studied from a Scheludko cell (Johansson and Pugh, 1992) or by observing a bubble with a flat interface (Sethumadhavan et al., 2002). However, these systems provide limited information on the arrangement of the particles."

Jan 1, 2018

By Heribert F. Broicher, Arne Volland

The application of remote sensing techniques combined with fluorescence spectroscopy is realised in analytical devices called LIF Analysers. The analysis of laser-induced fluorescence facilitates non-destructive, non-contact, on-line and real-time rock identification and quality control of bulk solids in transport. LKAB of Sweden was the first company to test LIF Analysers in the Kiruna Mine for bulk sorting of run-of-mine ores depending on the phosphorus content. Other applications tested in Germany so far are quality control of limestone (iron and/or dolomite content) and rock identification in lignite mining. Of special interest also is rock identification in diamond mines for dilution control. The paper summarises the present state of the application of LIF Analysers.

Jan 1, 2003

By A. T. Sutaone

"Battery grade Mn ore is not found in India except in Dongri-Buzurg Mine, Dist. Bhandara, Maharashtra. The mine located in central India is operated by a premier company viz. Manganese Ore India Ltd., under Central Government Public Sector Undertaking. The company is not selling the product as battery grade material but instead primarily catering to the needs of the iron and steel industry in the country. However, a part of the ore is being used in-house for the production of electrolytic manganese-dioxide in their EMD plant, which is located near the mine.The production of lumpy ore for steel industries generated through multi-stage crushing and screening has resulted in accumulation of about 50,000 tonnes of low grade fines over the year, which contain low of Mn values. Further, the generation of fines is still on going process due to the production of lumpy ores. These fines are stacked in the form of unconsolidated dumps, which create environmental problems like air and water pollution and siltation in the adjoining fields. Besides they are occupying large space, which is scarce in this mining area. The Indian Bureau of Mines under one of its statutory functions has suggested the company to explore the possibility of recovery of additional values under conservation and environmental aspects. Hence the company has sponsored a bulk sample for beneficiation studies in the Modern Mineral Processing Laboratory and Pilot Plant of Indian Bureau of Mines at Nagpur, India. The main manganese minerals present in these mine rejects have been identified as pyrolusite and psilomelane. The purpose of this study was to explore the possibility of evolving a suitable beneficiation flowsheet to obtain manganese concentrates assaying over 72% MnO2 to be used as raw material for the manufacturing of dry cell batteries."

Jan 1, 2003

By A. V. Bauman

"Important for thickening processes is the ability of slurries to form under certain conditions aggregation and sedimentation stable systems. Substantial part of difficult to sediment solid particles in such systems may be in colloidal state. The technique to study the sedimentation and aggregative stability of the slurry developed by the author with co-authors makes possible to define kinetics of changes in the aggregative stability of the system with solid phase varying concentration in it and produce data on sedimentation stability of the system in preliminary investigation of the thickening process. Research of aggregative and sedimentation stability of the slurry complement standard methods of laboratory studies to prevent errors in development of water-slime thickening balance and water circulation to design new and upgrade existing processing plants. Statistical analysis of process audits of more than one hundred upgraded and newly commissioned processing plants carried out in recent fifteen years showed that more than two-thirds of problems arising in commissioning the processing plants are associated with misdesign and errors in thickening and water circulation system. Among the main reasons of process design failures are: non-conformity of actual characteristics of the raw material to design characteristics, low quality of preliminary studies at the stage of sedimentation process simulation, design failures, wrongly selected equipment for the thickening and water circulations systems. As of today a number of problems associated with laboratory studies of sedimentation process, first of all, with interpretation of precipitation curves produced at the stage of laboratory refinement of the thickening process have been pinpointed. (Bauman A.V. Outstanding issues in design of thickening and water circulation diagrams in processing plants // Ore processing. 2016. ?3 P. 58-62) ?????? ?.?. ?????????? ??????? ?????????????? ???? ???????? ? ??????????? ?????????????? ??????. // ?????????? ???. 2016. ?3. ?. 58-62))"

Jan 1, 2018

By A. F. Usov

A potential of electric pulse disintegration in benification used for primary deposits ores containing precious metals is shown. Of special significance is that PGM and gold grains, being highly plastic, are easily liberated and are not smeared on the disintegrated rock fragments surface. It al-lows gravity separation, which is less expensive and more efficient, to be used instead of chemical processing, which is expensive and environmentally faulty.

Jan 1, 2014

By L. J. Li, Q. Zhang, Z. H. Liu, Q. L. Chen

Phosphogypsum (PG) is an industrial waste from the production of phosphate fertilizer. The utilization of PG is restricted by its containing impurities, and the pretreatment is crucial to eliminating these impurities. The purpose of the research is to recycle pretreatment PG as raw material for preparation of a-calcium sulfate hemihydrate (a-HH) by salt solution method. The effect of pretreatment technologies of lime neutralization and washing on dehydration rate, phase composition and morphology evolution of a-HH were investigated by crystal water content analysis, XRD and SEM. Furthermore, the change of pH in the reaction process was also discussed in detail. The results show that the dehydration rate of conversion PG to a-HH increases and the corresponding induction period, crystal growth period and total time decrease with an increase in CaO dosage from 0.2% to 0.6%. In the presence of 0.4% CaO or 0.6% CaO, the a-HH presents a long hexagon-prism-shaped crystal with a purity of 94%, and the end face of a-HH presents polyhedron. The system pH sharply decreases with the reaction time under different CaO dosage, and the pH variation from the initial alkalinity to acidity. The main reason is that as the co-crystallized phosphorus dissolved and released HPO42-, and with the pH decreasing to 4-5, HPO42- transformed into H2PO4-. The dehydration rate of washing PG is lower than that of original PG. Compared with the original PG, a-HH with the larger width and smaller aspect ratio can be achieved from the pretreatment PG subjected to lime neutralization and washing, meanwhile the crystal surface is more smooth.

Jan 1, 2018

By R. Els Ellis

Enhanced granulation of UASB granules was tested on pilot scale with two different test reactors (about 5 litres capacity each). Sludge from a local sewage works was used, with peach cannery effluent as carbon source. Cyclic motion of the reactor contents, and a daily replenishment of feed material create the necessary stress conditions for enhanced growth. Sizable granules, bigger than 0.5 mm, were produced within 20 days. Of the two reactors tested, the reactor equipped with a horizontal agitation shaft proved more effective.

Jan 1, 2003

By Andrey V. Tarasov

"An environmentally clean and virtually waste-less technology for treatment of domestic and industrial solid waste (HGIW) including other toxic chloride-containing materials has been developed and proven on a full scale by the Gintsvetmet Institute in cooperation with some other Russian organizations.The essence of the process is that the HGIW are decomposing in the liquid base in air-bed slag melted layer under the temperature of 1350-1400°C.HGIW is considered as fuel heat-producing energy of 1500-1800 kCal/kg with 51,7%.Processing of municipal and industrial solid waste in molten slag is carried out autogenously without additional fuel, the blowing is enriched by oxygen up to 50-70%.The complex makes it possible to treat the furnace charge without preliminary drying and sorting with big differences in chemical and morphological composition due to the versatile firing chamber.The proposed process resolves the acute and globally significant problem of dioxin formation.The purpose of the proposed technology is to ensure such destruction of the structural lattice that would guarantee irreversible transformation of the resultant substances to prevent formation of dioxins. It was established the required preconditions to achieve this purpose."

Jan 1, 2003

By C. L. Lin

Previous research on particle damage during high pressure grinding roll (HPGR) crushing was limited by the resolution of point-projection micro CT systems and the extent of damage was described by the percent of particles cracked for different crushing methods as determined at a voxel resolution of 40 microns. With recent advances in X-ray optics, the resolution afforded with point-projection micro CT systems has been improved by at least an order of magnitude using a lens-based X-ray micro CT system. With the use of X-ray lens imaging the resolution is determined by the lens rather than by the spot size of the micro-focus X-ray source. The high resolution X-ray micro CT (HRXMT) system made by Xradia with a voxel resolution of less than 1 micron is now being used for the characterization of particle damage during HPGR crushing. In this way, the direct 3-D determination of the internal damage of crushed ore particles which vary from 40 mm down to 100 microns in size is being studied at a voxel resolution of a few microns. The number, size, and shape of cracks can now be measured at this improved resolution and for the first time the specific crack surface area distributions of the crushed product can be calculated from HRXMT images using specially designed software tools for 3D analysis. Results from selected crushing operations are presented. Copper ore particles from HPGR crushing at high pressure (6 N/mm2) are severely damaged having crack specific surface areas as great as 10 mm2/mm3. Keywords: HPGR, particle damage, X-ray micro tomography, crack surface area

Sep 1, 2012

By M. Amani, A. Akbarinasab, M. Bazmandeh

The fourth iron ore production plant at Golgohar mining and industrial company consists a ball mill and wet medium intensity magnetic separators (3500 Guss). The ball mill product applies directly into MIMS and the MIMS concentrate directly transfers to the low intensity magnet separators (LIMS). The thickener is used for dewatering of MIMS and LIMS tailings. By sampling from streams of ball mill and separators, it was defined that the grade and iron recovery were 60% and 80% respectively while they would be 66% and 90% respectively based on the designing documentation. The average of P80 in the ball mill was 342 micron in a month that is coarser than optimized value. This problem was related to unsuitable operation of grinding. For optimization of grinding efficiency, the amount of charge volume was investigated as a variable. The measurements illustrated 32% charge volume. For increasing grinding efficiency, the charge volume was increased 1% and 1.6% in two stages. The results showed ball mill power draw average reached from 3650 kw to 4120 kw and the average P80 reached to 329 micron. All of parameters calculated about 35 day before and after change. Average of Ball mill feed iron ore grade before and after change was 49.24% and 50.32% respectively. This change caused an increase in efficiency of MIMS, where the enrichment ratio and concentrate grade increased 2% and 1.9% respectively. For increasing the iron grade of the MIMS concentrate; the orifice of the tail flow exit pipe changed from 4 inch to 6 inch and the concentrate grade increased 2%.

Jan 1, 2014

By David Newton, Christian O’Keefe, Robert Maron, Jerin Russell, Paul Rothman, Dylan Cirulis

"The presence of unwanted coarse material in flotation feed streams negatively impacts both recovery and throughput of concentrator plants. The detection of this coarse material is a long-standing problem in mineral processing that has been poorly addressed by existing instrumentation systems. This problem has been overcome by the development of two new systems that detect in real-time the presence of coarse material in the overflow stream of individual hydrocyclones. They both use sensors mounted to the overflow pipe of the hydrocyclone and provide a robust and maintenance-free system measurement that enables corrective actions through operator intervention or automatic control strategies. One system is non-invasive and detects very coarse material 6mm or greater in size. The other system uses a wetted sensor and detects coarse material down to a lower size limit of approximately 100 um. Both systems have been commercially deployed. The systems will be described in detail. Validation data and typical plant data will be shown"

Jan 1, 2014

By Fatemeh Saeidi, Malcolm S. Powell, Mohsen Yahyaei

In order to deal with the problems of existing comminution models a new approach towards the development of mechanistic models has been made so as to better understand the physics of milling processes and environments. Despite enormous improvement in this field a comprehensive study of rock breakage characterisation, appropriate for use in these types of models, is still scarce. This paper reviews the existing models of comminution according to ore characterisation techniques and parameters. The authors have looked into the existing testing methods and their applied mechanisms of breakage, using standard test results available at the JKMRC. The study includes classifying testing devices such as the drop weight tester, rotary breakage tester, slow compression, and piston and die based on the few major fundamental mechanisms of breakage that are experienced by rocks in the breakage process. The paper compares the range of particle size and energy utilisation, applied strain rates and loading mechanisms for the equipment. The product size distributions from the various equipment is compared for equivalent input energies, various loading rates but the same level of energy intensity, a broad range of energy including low energy utilisation and fines generation rate for equivalent specific energy input. The results clearly show that the outcomes and conclusions on competence and energy for breakage are a function of the test method that is applied. In ongoing work, it is proposed to investigate common tests that can be applied to characterising ores in a manner suited to modelling a range of comminution devices.

Jan 1, 2014

By Francesco Vegliò, Luigi Toro, Francesca Pagnanelli

Different hydro-metallurgical processes have been studied in order to recover manganese(II) from oxidised minerals such as MnO2. An innovative acid reductive leaching carried out in mild experimental conditions was here considered using agricultural and industrial wastes containing carbohydrates as reducing agents. The leaching process was investigated from a kinetic and equilibrium point of view in order to optimise the experimental conditions, develop a kinetic model and obtain high purity concentrated MnSO4 solutions. To study the leaching kinetic a Shrinking Core Model (SCM) was modified by a variable activation energy term to take into account both the variable reagent concentrations and the reaction rate change with respect to the manganese dioxide conversion. The influence of the particle size in the kinetic model is discussed with the support of SEM analysis before and after leaching. Manganese extraction yield was maximised (170-190 g/L) using appropriate carbohydrates and acid excesses, while impurity concentrations were kept low (Fe<10ppm and Ca<300ppm) pre-treating the ores, using hydro-alcoholic leaching medium and different combinations of down-stream processes. In particular precipitation, solvent extraction and adsorption onto active carbon were tested to eliminate Fe and Ca from MnSO4 solutions.

Jan 1, 2003

By Markus A. Reuter, Albert Scholte, Ewoud V. Verhoef, Gerard P. J. Dijkema

A dynamic, interactive map has been developed of the life cycle of a number of metals, from mining through to minerals processing, metal production, product manufacturing, recovery and waste management. Whilst the existing metal process network and waste management infrastructure provide substantial scope for (product) design, these also limit change due to the complex interdependence of metals, both in production and recovery, and the strong path dependency of industry and infrastructure development. Therefore, models for dynamic simulation were constructed that allow the specification and evaluation of the metal process network and waste management infrastructure ‘products’ over a longer time span. The model has been constructed using a bottom-up approach, to enable assessment of the environmental aspects of metallurgy and to simulate changes in the system structure and technology, i.e. from reactor or individual process step up to integrated material cycles. The model comprises hierarchical mass balances and linear models of individual processes and sub-processes. Thus, at lower system aggregate levels an increasing level of technical detail is represented. Data reconciliation has been used literature data on process feed, products and residue composition to calculate representative and reliable split factors around each (sub-)process. World production figures on process capacity and recovery rates are be used to calculate the relative contribution of processes. The dynamic map is illustrated with a case on the introduction of lead-free solder.

Jan 1, 2003

By Ljubisa Obradovic, Baisui Han, Batnasan Altansukh, Zoran Stevanovic, Atsushi Shibayama, Jonovic Radojka, Daizo Ishiyama, Kazutoshi Hag, Radmila Markovic, Ljiljana Avramovic

This paper discussed a combined froth flotation and high pressure leaching (HPL) process to recover copper from mine tailings. At first, froth flotation were carried out using the mine tailings sample under various conditions in the presence of different pH (3.5-10) and sulfurizing reagent value (0-1000 g/t), respectively. As a result, optimum condition (sulfurizing reagent of 1000 g/t, pH of 10, PAX (collector) of 100 g/t and MIBC (frother) of 200 g/t) was found for froth flotation of copper. The effects of sulphuric acid concentration, leaching temperature, total pressure (steam pressure plus oxygen pressure) on high pressure leaching (HPL) of mine tailing were investigated using sulphuric acid solution in the presence of oxygen. The best conditions for HPL were obtained to be sulphuric acid concentration: 0 mol/L (water), leaching temperature: 170 ?, total pressure: 2 MPa, leaching time: 1 hr and pulp density: 100 g/L. The leaching rate of copper reached nearly 99 % and the concentration of copper in pregnant leach solution (PLS) was 0.24 g/L. Finally, copper in the mine tailing was recovered using froth flotation followed by HPL. As a result of a combined froth flotation and HPL, the vast majority of copper (99 %) from the mine tailings was extracted.

Jan 1, 2014

By Lutz Rolf, Halit Z. Kuyumcu, Salas Cazón. Milton A.

Aim of experimental investigations was the mathematical description of the abrasion process running with a single particle stress. This is on the one hand the basis for the physical interpretation of the process, on the other hand the base for the simulation of abrasion processes carried out in technical scale. With this investigation for the first time the influence of the particle shape changing with increasing abrasion progress was quantitatively described. This influence affects itself particularly strongly on break-fresh particles up to an abrasion degree of approximately 10 to 20%. This is for the description of technical processes the most interesting area.

Jan 1, 2003

By S. Mitra1

"This study aims to investigate coarse particle detachment mechanisms (particle diameter > 150 ?m) utilising both experimental and numerical technique. Two mechanisms were studied – (i) interactions of bubbleparticle (BP) aggregate with vortices and (ii) coalescence of bubble-particle aggregates. On the first mechanism, interaction behaviour of coherent vortex structures with a BP aggregate (bubble diameter db = 3 mm, particle diameter dp = 0.3 mm) was studied using a CFD model in the Reynolds number range of 100 to 1000. Effect of surface hydrophobicity on the BP stability was examined using a range of contact angle boundary conditions. To address the second mechanism, interactions of bubble-particle aggregate (db ~ 4 mm, dp ~ 0.4 mm) with both free gas-liquid interface and individual bubbles were investigated using high speed imaging. Both rebound and coalescence outcomes were observed to be responsible for BP instability leading to particle detachment.INTRODUCTIONIt is widely known that flotation process performs excellent mineral recovery for base metal ore particles that are typically in the range of ~ 20 to 150 µm in diameter (Jameson, 2010). More specifically, higher recoveries are usually reported for particles in the size range of ~20 to 70 µm while outside this spectrum, generally the recovery diminishes significantly. It would be highly desirable to improve the recovery of particles at the coarse end of the flotation size range spectrum which has significant economic benefit (Jameson, 2010). However, it is essential that insights to particle detachment phenomenon, the primary impediment in coarse particle flotation caused by the underlying hydrodynamic factors are first obtained at a greater depth.In an ideal quiescent liquid medium, due to inertia, coarse particles deviate substantially from the fluid streamlines and collision efficiency with bubbles decreases which can only be augmented by increasing turbulence level in the medium sufficiently to make random physical contacts with bubbles. Nonetheless, even if successful contacts are made, it is difficult for these large particles to remain attached to bubbles in a turbulent shear flow environment. There are two major mechanisms postulated for particle detachment – interaction of turbulent flow structures (eddies) with BP aggregate and coalescence among surrounding aggregates. Earlier work of Schulze (1982) theorised a vortex acceleration component to characterise turbulence effect on BP aggregate instability in flotation machines. Wang et al. (2015) investigated bubble detachment behaviour from a stationary particle in a nearly homogeneous and isotropic flow field. Using PIV (particle image velocimetry), it was shown that the local maximum energy dissipation rate for the case of bubble detachment was significantly higher than the no detachment case, and was also higher than the critical value for bubble detachment calculated using Schulze’ theory (Schulze, 1982). Later, Wang et al. (2017) also visualised the BP aggregate instability in a cavity flow leading to particle detachment which was attributed to bubble coalescence, bubble surface oscillation and particle deceleration phenomena."

Jan 1, 2018