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By I. D. Ustinov, V. A. Arsentyev, A. O. Mezenin, A. M. Gerasimov

"The solid mineral raw materials of the sediment deposits containing the argillaceous variations such as the coal and the potash ores are the most multi-tonnage solid minerals mined and processed in the territory of the Russian Federation. Both types of the deposits have relatively simple geology aspects with large and medium-sized solids and as a rule, the most often, with the regular bedding which are characterized by the fitchery thickness and the internal structure. Such deposits are very difficult for mining and processing. The thermal modification of this of ores allows changing the physico-chemical properties of its components in such a way that their further processing - grinding, separation, transportation and storage can be carried out without the use of process water or significantly reduces its consumption. The purpose of the present study is to increase the efficiency of the mineral processing containing the layered aluminum silicate by reducing their negative impact on the basic dressing processes, the separation of suspended matters and the storage of waste. INTRODUCTION Many deposits of minerals are associated with the presence of layered silicates such as the argil, mudstones, argillaceous slate - highly hydrophilic mineral varieties which have the ability to swell in the water. This ability to self-disperse creates the great difficulties both for the extraction and the processing of such ores. Since the dressing of most minerals is associated with the use of wet processes, where in contact with water the swelling layered silicates are dispersed to a particle size of less than 50 µm, but due to their high hydrophylic property they form bonds that promote the formation of so-called structured suspensions having increased viscosity. In this case the structured suspensions make it difficult to perform the separation operations as the classification, the gravity and magnetic separation, the flotation and thickening and filtration operations."

Jan 1, 2018

By S. S. Indi, D. Santhiya, S. Subramanian, K. A. Natarajan

"With the gradual depletion of the high-grade ores and finer dissemination of values in the leaner samples, it has become imperative to develop innovative approaches to process such complex ores. The beneficiation of complex sulphide ores containing copper, lead and zinc minerals, remains one of the most important challenges in base metals metallurgy. The advent of biotechnology in mineral processing has opened up immense possibilities to exploit such difficult-to-treat ores. Bioprocessing techniques thus hold promise as potential substitutes for the conventional technologies in vogue. Several types of autotrophic and heterotrophic bacteria, fungi, algae and yeasts are implicated in mineral beneficiation processes. Adopting a bioprocessing route to mineral beneficiation has attractive benefits, such as lower cost and energy requirements, environmental acceptability and operational flexibility.The interaction of sphalerite- and galena-adapted Bacillus polymyxa (B. polymyxa) cells with sphalerite and galena has been investigated through adsorption, electrokinetic and flotation studies. The amount of sphalerite-adapted cells adsorbed onto sphalerite and galena is found to decrease with increase in pH. On the other hand, the adsorption density of galena-adapted cells onto galena shows a feeble maximum around pH 8, and the amount adsorbed is marginally higher in the pH range of 8 – 11.5. In the case of sphalerite the amount adsorbed is higher in the pH range of 5 to 7. The adsorption density of both the adapted cells is higher for galena vis-à-vis sphalerite. Electrokinetic studies indicate significant surface chemical changes on the chosen sulphide minerals and the bacterial cells, consequent to microbemineral interactions. Selective flotation tests on a synthetic mixture of galena and sphalerite confirm that sphalerite could be preferentially floated from galena, using galena-adapted cells, but not with the sphalerite-adapted cells. The cells adapted to galena assay a higher polysaccharide content and are more hydrophilic, while the sphalerite-adapted cells have a higher protein content and possess greater hydrophobicity. Transmission electron microscopic studies have provided evidence in support of the differences between the cell surface characteristics of sphalerite- and galenaadapted cells (Figure 1). Possible mechanisms of interaction between the minerals and the bacterial cells are discussed."

Jan 1, 2003

By Santiago Garcia, Dariusz Lelinski, Devan Govender, Tyson Baker, Mads Jespersen

"In recent years, the scale-up of mechanical flotation machines has been attempted with greater frequency. In contrast, the development of rotor-stator designs has been subject to greater inertia. The rotor-stator components are integral to the operation of mechanical flotation machines, responsible for the key physical processes of solids suspension, gas dispersion and energy dissipation. Design modifications are predicated upon the dual purpose of meeting customer needs while achieving metallurgical performance objectives. Accomplishing the latter is a rigorous undertaking, typically involving the sequential application of fluid dynamics principles, prototyping, smaller-scale research screening studies and larger-scale development projects. This industrial evaluation details the final stages of the forced-air rotor-stator development process using a double-refractory Carlin-type gold ore. A bypass stream of the primary rougher feed was further classified into cyclone underflow and overflow products. Four rotor-stator treatments were evaluated using parallel flotation rows coupled with a randomized statistical design. Only two treatments are compared in this initial assessment. Metallurgical responses were measured as a function of the random variation of key machine factors. Machine characterization measurements complemented the analysis of flotation performance indicators."

Jan 1, 2014

The flotation of nickel sulphide minerals is normally difficult in the presence of serpentine minerals due to the coating of serpentine particles on the nickel mineral surface. To improve the flotation, dispersants such as polyphosphate and carboxy methyl cellulose are normally used to remove the slime coating. However, in the flotation using high ionic strength process water, these dispersants are invalid due to their ionic nature. In this study, a new type of non-ionic dispersants, Pluronic triblock copolymers were examined with an objective of improving the flotation of ultrafine pentlandite (a nickel sulphide mineral) in the presence of lizardite (a serpentine mineral) in saline water. Three Pluronic triblock copolymers varying in solubility and hydrophile-lipophile balance (HLB) values were studied by flotation tests, settling tests and froth measurement. It was found that two of the copolymers improved pentlandite flotation against lizardite, and one copolymer deteriorated the flotation. The effect of Pluronic triblock copolymers on the flotation was actually linked to their dispersibility and foamability, which were governed by their physical properties. The two copolymers with a higher solubility or HLB value produced more stable mineral suspensions and more stable froth in the flotation resulting in better nickel grade and recovery in both rougher and cleaner flotation. Keywords: ultrafine particle, flotation, slime coating, dispersion, saline water, triblock copolymers

Sep 1, 2012

By P. Yu, L. X. Liu

"A mechanistic model for tumbling mills was developed during PhD studies at the JKMRC. The concept was presented at the IMPC of 2014, followed by progress in a sub-process of the model presented at the IMPC of 2016. Additionally, a number of papers on the sub-models and breakage function have been published. This paper provides a consolidated summary of the outcomes and status of the model. The overall model structure is presented along with the sub-models such as appearance functions, breakage rate functions, energy distribution, transport, and multicomponent grinding interaction model. The strengths and capabilities of the model structure as achieved to date are presented. The gaps in knowledge and sub-processes are also presented, providing a guide to the areas that require further research and development. It is proposed that the approach developed in this paper provides a structure that can accommodate future mechanistic, dynamic mill model evolution that can incorporate the latest research outcomes and provide a platform to test modelling improvements. This can assist in substantially improving the predictive mill modelling capability in the industry, the importance of which should not be underestimated for this workhorse of mineral processing.INTRODUCTION Grinding is almost the largest single energy-consuming process in the mineral processing industry, which was estimated that about 0.2% of global, and 1.3% of Australia’s electricity is consumed by comminution of gold and copper ores (Ballantyne and Powell, 2014). Although there are some relatively new grinding mills, such as stirred mills, vibrating mills and HPGRs (High-Pressure Grinding Rolls), etc., tumbling mills, as the traditional grinding facilities, are more extensively used."

Jan 1, 2018

By E. V. Manlapig, M. C. Harris

"The complexity of the flotation process has made the identification of an appropriate model structure for the predictive simulation of flotation circuits far from obvious. Work performed under the auspices of the AMIRA P9 flotation program has indicated that the metallurgical performance achieved from a flotation cell arises from the interaction of two essentially independent property classes, namely the cell operating conditions and the properties of the cell feed stream. These observations have led to the development of a model structure that associates a constant set of flotation parameters to the streams of the circuit, which are transformed into a flotation response depending on the operating conditions within the flotation cell.A variety of alternative model structures exist within the literature which do not make this distinction between cell and stream flotation properties, and many of these models are in widespread use for flotation optimisation and design studies, both in industry and academia.In this paper, circuit survey and laboratory batch flotation data collected from an industrial flotation circuit are analysed. The data demonstrate that streams in an industrial flotation circuit exhibit varying particle floatability – concentrate streams typically float faster than tailing streams (Figure 1(a)). This floatability, however, is generally conserved around the various units within the flotation process (i.e. the effective floatability of the combined feed and product streams of a unit is equivalent (Figure 1(b)))."

Jan 1, 2003

By David I. Verrelli, Peter T. L. Koh

"Recent experimental measurements of induction time made by direct observation with the ‘Milli-Timer’ indicated that angular particles were able to attach much more rapidly than spherical particles. There was around a tenfold difference in the respective induction periods for particle-bubble attachment. For industrial application, a more holistic comparison is needed, with the induction period for attachment being just one input. Over the years, CSIRO has developed a CFD-flotation model that incorporates both rigorous hydrodynamics, to simulate real industrial cell geometries, and a detailed model of the embedded flotation process, in which the induction period is an important parameter. We conducted transient modelling of batch flotation. First, spherical particles were modelled, as a ‘baseline’, for different particle sizes and levels of hydrophobicity. In the second set of results, the induction period was decreased by a factor of up to ten, simulating flotation of angular particles. Flotation recovery was found to depend upon induction period in a complex manner. For highly hydrophobic or fine particles, the induction period for spheres was already so low that recovery was limited by other factors (e.g. bubble-particle collision frequency). Further decreases in induction period, as for angular particles, did not have a significant effect on recovery in these cases. By contrast, when weakly hydrophobic or coarse particles were modelled, the recovery was predicted to be greatly enhanced for angular particles, in comparison to spheres. For these particles the induction period was limiting recovery, so that the flotation rate constant could be improved directly by reducing the induction period. This is consistent with batch flotation experiments using Ballotini reported earlier. Therefore, when dealing with weakly hydrophobic particles or relatively large particles that are to be floated, an enhancement can be expected for more angular particle shapes. In such cases, judicious specification of the grinding circuit may improve the overall efficiency."

Jan 1, 2014

By M. Rudolph, D. H. Hoang, N. Kupka

"Froth flotation has been subjected to modelling since the 1930s and there is a large variety of approaches that intend to portray the entire process. Among these, three fundamental models could be considered exhaustive: the Pyke model [1], the Yoon model [2] and the Schwarz and Koh model [3]. The first model makes use of the generalized Sutherland equation collision model, the Dobby-Finch attachment model and its own stability model, the second model considers an extended DLVO approach for the attachment and stability whereas the third model makes use of computational fluid dynamics. Using a scheelite ore as a test case, a specific batch flotation test was repeated ten times and analyzed for chemical assays, mineralogical studies and froth properties. The detailed data are used to feed the three flotation models aforementioned in order to compare the outcomes of the three approaches, their capacity to reflect reality and to predict it. This article intends to pave the path towards reliable process models incorporating in depth mineralogy information, e.g. surface liberation, particle size and particle shape. KEYWORDS Froth flotation fundamental models, scheelite, automated mineralogy, critical assessment. INTRODUCTION In mineral processing, only three approaches aiming at describing froth flotation fundamentally could be considered exhaustive: Pyke’s collision and sliding approach [1], Yoon’s kinetic approach [2] and Schwarz and Koh’s approach [3]. The models will hereafter be referred to as Pyke model, Yoon model and Schwarz and Koh model. The first model makes use of the generalized Sutherland equation collision model, the Dobby-Finch attachment model and its own stability model, the second model considers an extended DLVO approach for the attachment and stability whereas the third model makes use of computational fluid dynamics. All three approaches rely on the widely accepted idea that flotation is a kinetic reaction dependent on a flotation rate constant kp, as expressed in Eq. [4]:"

Jan 1, 2018

By C. B. Wu

This paper presents an analysis of comminution behavior of using cast iron segment (CIS) as fine grinding media with comparison to conventional steel ball. Grinding experiments utilize just one-size medium and mixed size media in laboratory were carried out and its efficiency is expected to be improved. The results show that no matter whether one-size medium or mixed size media employed, grinding efficiency of CIS media can be considerably equal to that of steel ball, on the other hand, grinding product by two kinds of media can conform to Robin-Rammler?s size characteristic curve and distribute in function of . )exp(100nbxy-= Comparing with steel ball, the milling capacity with CIS media could be increased up to about 8.6 percent, overcomminution decreased 3.96 in percentage and qualified size increased 3.98 in percentage in case of grinding fineness retained. At the same time, due to the improvement of grinding product size characteristic and its metal distribution characteristic, the grade and recovery of easy to separation size increased 0.24 in percentage and 6.47 in percentage respectively. Based on these results, the CIS media can be employed as novel fine medium for grinding process substituting for steel ball.

Jan 1, 2014

By M. Ghiani, R. Peretti, S. di Giovanni, G. Zonnedda, A. Serci, A. Zucca

"Beneficiation of the epithermal gold mineralizations associated with an extensive alteration zone in the Serrenti-Furtei region on the island of Sardinia, is proving a complex issue. Experimental investigations have in fact demonstrated that while the ores contained in the upper parts of the deposit are amenable to conventional cyanidation, the gold contained in the refractory ores in the lower portions needs to be recovered by means of flotation, combined with leaching where necessary.The results of commercial heap leaching, carbon-in-leach (CIL) processing and flotation, designed on the basis of the experimental findings and applied to the oxidized portions and transition zones of the deep sulphide mineralizations, confirmed the expectations emerging from the laboratory tests."

Jan 1, 2003

By Igor Kuzymin, Isaak Maximov, Iuriy Akkerman, Galina Aksenova, Valentina Sentemova, Nataliya Trubechkova

"The Russian Federation possesses large reserves of oxidized ferruginous quartzites. These ores are currently mined together with magnetite ores and are stockpiled on account of unavailability of an efficient processing technology. This paper presents the results of investigations performed on the ores from the largest oxidized ferruginous quartzite deposit located in the Kursk Region iron-ore basin of Russia. The objective is to produce concentrate with iron content at least 66% and silica content within 5%. A processing technology was, developed under laboratory conditions, which included ore preparation, wet magnetic separation in weak and strong fields and reverse cationic flotation with addition of caustic soda, dextrin and Lilaflot 811M (alkoxy propylamine) collector from Akzo Nobel. The developed technology produced iron recovery concentrate with iron content of nearly 67%, and that of silica - 4.1%, iron recovery into concentrate being 72.6%."

Jan 1, 2014

By P. Somasundaran, G. Anastassakis, Z. Pan, D. R. Nagaraj

Gums are often used as depressants for talceous gangue minerals in the flotation of nickel and platinum bearing ores. However, the mechanisms of gum adsorption on talc are not clearly established. In this work, adsorption of guar gum at the talc-solution interface is investigated using spectroscopic and allied techniques. Guar gum adsorption on talc is not affected significantly by changes in solution conditions such as pH and ionic strength. Electrokinetic studies showed that guar gum decreased the negative zeta potential of talc but did not reverse the charge. Fluorescence spectroscopy studies conducted to investigate the role of hydrophobic bonding using pyrene and dansyl probes showed no evidence of the formation of hydrophobic domains at talc-aqueous interface. Urea, a hydrogen bond breaker, reduced the adsorption of guar on talc to the same extent as that for guar/alumina system, in which hydrogen bond plays an important role. All of the above results suggest that one of the main driving forces for guar adsorption on talc is hydrogen bonding rather than electrostatic or hydrophobic force.

Jan 1, 2003

By S. P. Nagaeva, O. U. Poperechnikova, A. V. Kuptcova

"In case of free gold presence in ore, there is always problem of a choice between the gravity-flotation and gravity separation flowsheets. Study of morphology of gold being extracted by different methods allows to find the most efficient solution. One of the latest methods of gold concentration for wide range of grain size (-0.8+0 mm) is a flash flotation. The paper presents comparative testing results of flash and centrifugal separation.The goal of the studies was to determine process and flotation parameters of flash flotation. In case valued minerals are soft if compared to host rock, such minerals tend to concentrate into circulating load of grinding circuit. Thus, valued minerals can be overground, and in turn, will result in low extraction in flotation circuit. Integration of flash flotation operation into process flowsheet has been evaluated. Flash flotation operation can be successfully used not only for gold but also copper, lead, nickel and silver minerals.With low-sulphide ores being a case study under laboratory conditions, various flotation (impeller rotational speed, air flowrate) and process (pulp density, collector consumption, frother consumption, time of flotation) parameters were studied in view of its impact on gold flash flotation. Experiments were carried out under laboratory conditions using special pneumatic mechanical flotation machines.INTRODUCTIONGravity separation is used for extraction of coarse gold before cyanidation and before flotation of polymetallic ores to increase gold total recovery into gravity copper and lead concentrates.Benefit of the flash flotation is efficient recovery of coarse gold carrier particles (sulphides) thus preventing its regrinding and, as a result, low recovery. Furthermore, combination of flash and conventional flotation results in final tailings that do not require further cyanidation.Combined gravity-flotation flowsheets are designed for concentration of ores containing gold within thewide range of grain sizes (see Table 1)."

Jan 1, 2018

By I. L. Grigorova

As a result of the main processes of the limestone treatment ? sawing, buffing and polishing, a technological waste is usually obtained. These final tailings consist of a water suspension with highly variable solid phase content and granulometric composition. Since the waste is conducted to a tailing pool or another place, this leads to environment pollution. In this work the slurry waste generated during the limestone processing in a Bulgarian limestone manufacturing company was characterized. The chemical composition, particle size distribution, solid phase content, whiteness, yellowness, abrasion, specific surface and density were determined. The possibility of obtaining building/construction materials from limestone processing waste was studied in a laboratory scale. The technological tests included thickening, filtration and drying of waste products. Continuous operation laboratory thickener was used. Coagulant Accepta® 8302 (aluminum sulphate solution) and anionic flocculant Magnafloc® 155 were found to be the most effective in the sedimentation of the products. Filtration tests were performed using a laboratory pressure filter. Drying tests were carried out in laboratory facilities using the direct heating method. On the basis of the laboratory results a technology for limestone treatment waste was developed. A production line for building materials from limestone slurry was set up. As a result the manufacturing company has a possibility to use circulating water.

Jan 1, 2014

By F. Burat

The present research covers the results of experiments carried out with high frequency vibration screen on dewatering of coal fines. In the tests, the addition of surface active reagents was studied employing a high frequency vibrating screen. To increase the efficiency of mechanical dewatering processes, ultrasonic treatment was applied along with surfactants and optimum dewatering conditions were obtained. The moisture content of the feed material was from 82.5% to 41% by the optimization of operation parameters including the angle of the screen, vibration frequency, feed rate and screen opening size. Optimum parameters obtained in dewatering processes carried out with the vibrating screen were kept constant and the effects of surface active reagents and ultrasonic treatment on dewatering were investigated. Finally, the moisture level of the material was further reduced from 41.0% to 37.66%.

Sep 1, 2012

By Andrey V. Yevdokimov

The results of the test work on gold leaching using high strength of cyanide solution in the presence of activators are presented. The major physical and chemical relationships of gold leaching were determined. Intensive cyanidation results of gravity concentrates with various material compositions using an activator are given. Process design criteria for intensive cyanidation unit were developed on the base of pilot plant test results. Keywords: gold, activators, intensive cyanidation, gravity concentrates

Sep 1, 2012

By A. A. Novoselov, U. Kelm

"Large volumes of mine tailings accumulated in surroundings of porphyry copper deposits represent a growing threat to environment. They contain significant concentrations of toxic metal and metalloids which can contaminate river runoff, ground waters or can be transported by wind. Both extreme pH of fluids in tailings impoundments and high surface areas of processed mineral grains provide their increased reactivity. As a result, during only a few decades, As, Cu, and Mo can be mobilized, redistributed through the tailing column and accumulated through post-deposition leaching, evaporation and contamination with natural fluids. Those processes are reflected in the forming of secondary minerals. Gypsum, Fe oxides/hydroxides, efflorescent salts and clay minerals are typical alteration products in tailings. Here we present the results of reactive transport simulations implemented on the base of PHREEQC and SUTRA codes. The one-dimension model emulates the mass balance between rainfall, evaporation and subsurface runoff, the kinetically- and thermodynamically-driven dissolution of tailing minerals, advective and diffusive transport of tailing fluids, and precipitation of secondary phases. A typical tailing column is composed of four unequal layers with predominance of (i) evaporation, (ii) secondary mineralization above, (iii) below water table, and (iv) near the bottom of dump. Those horizons are characterized by contrasting pH, chemical composition and bulk mineralization of pore fluids, distinct accessibility of atmospheric oxygen and, as a consequence, distinct intensity of sulfide oxidation. The modeling and its verification on Chilean tailings impoundments reveal the complexity and high rates of secondary mineralization. The accumulation of toxic alteration products is controlled by fluid transport through the tailing column induced by both rainfall/evaporation and exchange with subsurface runoff. The geochemical modeling is a powerful approach which allows comparing the processes in tailing deposits produced by distinct flotation regimes and providing the long-term predictions of their environmental impact as well as identifying sectors of tailings for possible re-processing."

Jan 1, 2018

By S. Saha

Minerals in coals cause operational problems in various coal utilization technology as well as act as diluents towards its heat value. Indian coals contain higher percentage of mineral matter compared to foreign coals due to its formation through drift origin. Efficient utilization of high ash coal in environment friendly manner is the driving force for the development of clean coal technology. Coal gasification offers practical means meeting stringent environment controlled parameters for producing power, chemicals, liquid fuels and clean energy on a single platform. It is well accepted that gasification technology has sufficient potential for sustainable development of clean coal technology. Gasification reactivity depends on the coal properties and operational parameters as well as minerals present in coal. Minerals not only create operational problems but on the other side also catalyze the gasification and combustion reaction. Therefore to understand the effect of minerals on the gasification reactivity, present paper proposes to study the variation of gasification reactivity with various gravity cuts such as, 1.4-1.5; 1.6-1.7; and 1.8-1.9 of a selected coal. Gasification reactivity has been studied by thermo gravimetric analyzer (TGA) using CO2 as gasifying agent. Surface properties such as, true density, apparent density, porosity, surface area of different gravity cut samples have also been measured to find out the effect of gravity separation on gasification reactivity. Keywords: gasification, reactivity, mineral matter, gravity separation

Sep 1, 2012

By T. Wang

A new kind of mixed chelate collector was prepared in order to separate gangue (mainly quartz) and iron minerals efficiently during room temperature. The collector was was composed of two chelate collectors DES and DA. Floatation tests were carried out under 28?C with mixed magnetic concentrates of Donganshan sintering plant, and optimal test conditions were obtained, in which a direct floatation was undertaken and then a close circuit reverse floatation tests ( one roughing, one cleaning, and two scavenging), and a result of Fe grade of siderite concentrate 36.49%, Fe recovery of siderite concentrate 10.65%, Fe grade of final concentrate 66.27%, Fe recovery of final concentrate 78.25%, and Fe grade of tailing 16.22% was gained. Fourier Transform Infrared (FTIR) Spectra and Zeta potential of siderite and quartz adsorbed the DES and DA collectors before and after were measured in order to analyze the reaction between the collector and minerals. Furthermore, Molecule electronegativity of DES and DA was calculated by Electronegativity Proportionality Principle (EPP). Results showed that DES molecules have five active adsorbing sites and their molecule electronegativity was stronger while DA molecules have three active adsorbing sites, which all make the mixed collector has efficiently collecting performance. Zeta potential results of Quartz and siderite showed that at pH 11.5 both kinds of particles charged negative and at this pH value the mixed collector were mainly anionic collectors which indicate that electrostatic adsorption does not exist at this situation. FTIR results showed that characteristic peaks of the mixed collector changed before and after adsorption with the minerals, which means that there exists chemical adsorption or hydrogen bonding.

Jan 1, 2014

By Andrew T. McBride, Malcolm S. Powell, Indresan Govender

"Current empirical Semi Autogneous Grinding (SAG) mill models contain assumptions concerning the amount of energy available for particle breakage, how this energy is distributed in the mill media and the rate at which the energy is transferred. Despite these assumptions the JK SAG model is highly functional with a proven track record. DEM provides a numerical framework to greatly improve on these assumptions that were necessary due to a lack of available input data.This paper identifies key outputs of the Discrete Element Method (DEM), such as energy spectra and impact probability distribution. It describes how they can be incorporated into current mill models utilising practical rock breakage data. The rate at which energy is transferred is shown to be dependent on particle position and mill rotational speed and not once per cycle as previously assumed. Based upon this an improved energy transfer methodology is presented. The fundamental outputs of the DEM are validated against experimental three-dimensional particle tracking data, so as to establish whether the DEM produces correct energy transfer predictions on the inter-particle level, which is crucial to this work. • Effective Experimental ValidationAn automated 3D tracking technique is employed to study the motion of plastic particles deep within the charge of a 142mm diameter experimental mill. A Biplanar Angioscope is used to film the mill with X-rays in two planes simultaneously at 50 frames/s, with a shutter speed of 1/3000s. A marked ball within the charge is tracked for over 2 minutes and the resulting digital images processed by a fully automated imaging technique, which locates the 3D coordinates of the particles to within 0.2mm. With over 250 circulations, this provides statistically rigorous and accurate data for verification in the numerical modelling of mills.A series of validation techniques have been developed to compare the experimental trajectory data with the outputs of both 2D and 3D DEM simulations. The techniques describe the shape of the charge and the particle motion within mill, allowing objective comparisons to be made of key features of the charge, such as the equilibrium surface and the centre-of-circulation."

Jan 1, 2003