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By MáAndrusiewicz, M M. Hilden, M S. Powell, P D. Kay, B Foggiatto

Circuits with unconventional and potentially more complex designs are predicted to become more common in the future as plant designers and operators look to process ores more efficiently. Ideas have been presented on how circuit design may be changed to utilise todayÆs technology to address tomorrowÆs challenges (Powell and Bye, 2009; Powell, Benzer and Mainza, 2011a). High pressure grinding roll (HPGR) installations in various configurations; application of preconcentration plants eg sorting, magnetic or gravity separation; and preweakening devices eg microwave processing; are all examples of technologies having the potential to deliver a significant reduction in comminution energy for ores amenable to these processes. Not only will future novel circuits contain equipment for which models are not as well developed (if at all), many will likely require the ability to respond to variations in feed, and interact with geometallurgical models requiring process adjustments when the ore characteristics change.In order to confidently simulate more complex circuits and accommodate variations in feed type, a significant advancement in modelling and simulation capability is required. This includes dealing with multiple components in the feed, accommodating different competencies of ore, utilising physical separation opportunities and tracking the grade reporting along the different potential processing routes. Developing the means to simulate complex circuits has been a key priority of a collaborative group of comminution researchers working to solve these challenges.Simulations are presented utilising a new configurable simulation interface called the model developers kit (MDK). The MDK is designed to accommodate multi-components and incorporate new models under development. These will be used to demonstrate the potential of flexible circuit design, based on measured ore properties and equipment performance.CITATION:Foggiatto, B, Hilden, M M, Powell, M S, Kay, P D and Andrusiewicz, M, 2012. Simulation of flexible circuits, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 291-298 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By S Morgan, D J. Bradshaw, S Schwarz

The characterisation of the flotation kinetic response in future mining deposits is important because the flotation response is affected by changes in ore mineralogy. Current methods for characterising the flotation response of different ore types, such as the JK floatability index test (JKFIT) methodology, require at least 10 kg of feed material. In geometallurgical applications, this material is taken from core samples. Core samples are generally obtained using specialised drills and are limited in nature. Thus, it would be beneficial to develop a laboratory technique that required less sample material but still characterised the flotation response of different ore types. The JK mineral separation index (JKMSi) is a small-scale flotation test that requires significantly less feed material (10 g of sample/data point). This study aims to investigate the JKMSi system kinetics and to validate this technique using the JKFIT proven methodology. The JKMSi flotation kinetics were manipulated by varying selected system parameters. The relationship between these parameters and mineral recovery was used to obtain floatability characteristics of the ore. For an ore sample containing chalcopyrite and pyrite, it was found that the chalcopyrite floatability parameters determined from both the JKMSi and JKFIT tests were of the same order of magnitude and the mass fractions of the fast, slow and non-floating components were similar. For pyrite, the floatability parameters were not of the same order of magnitude, but modifications to the test procedure have been identified, which may correct this.CITATION:Morgan, S, Bradshaw, D J and Schwarz, S, 2012. Julius Kruttschnitt Mineral Separation Index - Small-scale test to characterise the flotation response of an ore type, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 159-162 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By P Holtham, R Dunne, D Stoll

Flash flotation is a process designed to remove coarse, liberated, fast floating minerals from hydrocyclone underflow. Irrespective of liberation, coarse particles would normally remain in a grinding circuit until they are reground fine enough to report to the hydrocyclone overflow. Additionally, minerals of high density also report to hydrocyclone underflow despite being fine in size and/or liberated because hydrocyclones separate on the characteristics of both particle size and density. Dense particles continually reporting to the hydrocyclone underflow can lead to over-grinding and the production of ultra fine particles. These particles exhibit slow flotation kinetics and thus are difficult to float in conventional flotation circuits. Therefore, removing coarse, liberated particles from the hydrocylcone underflow by flash flotation has the potential to improve recovery and can improve dewatering unit operations and reduce grinding costs.The impact on the overall performance of the flotation circuit by removing coarse, fast floating minerals prior to conventional flotation is not well understood. Ultimately, predicting the overall recovery improvement provides the justification for the installation of a flash flotation cell within the milling circuit. This paper will describe attempts to estimate flash flotation recovery improvements to the overall circuit using kinetic data from simplified batch cell flotation tests combined with limn-based modelling techniques.CITATION:Stoll, D, Dunne, R and Holtham, P, 2012. Modelling the impact of flash flotation from batch cell flotation tests using limn, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 179-184 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By N Weerasekara, M Bird, M Yahyaei, M M. Hilden, M S. Powell, J Franke, P Toor

The combination of new tools with a more rigorous approach to understanding the interaction of mill liners with overall mill performance and economics, forms the basis of an integrated approach to liner management. Based on accurate liner wear measurements, some (limited) physical mill inspections and surveys, accurate calibration of the mill load and analysis of process data, a whole new approach to liner selection, relining intervals and mill control is proposed. Collection and analysis of this information in operating mills illustrates the mill performance improvement which can be attained through this careful measurement and modelling approach.A more holistic approach to liner management is proposed, including a broadening of the current work to cover the potential benefits of improved relining technologies and predictive liner wear modelling. CITATION:Powell, M S, Hilden, M M, Weerasekara, N, Yahyaei, M, Toor, P, Franke, J and Bird, M, 2012. A more holistic view of mill liner management, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 95-104 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By J Seppelt

The Kanmantoo Copper Project is owned and operated by Hillgrove Resources Limited and is situated in the Adelaide Hills region in South Australia. Mining in the area has taken place off and on over the last 140 years to recover metal from both copper and lead-zinc ores. This paper focuses on the commissioning, ramp up and future outlook for the copper concentrator at the Kanmantoo Copper Project with major focus on issues encountered and operating performance achieved to date.CITATION:Seppelt, J, 2012. Commissioning of the Kanmantoo Copper Concentrator, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 127-136 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By C J. Greet, J Kinal, C Hitchen

Following the successful completion of a marked ball test defining the potential wear benefits the high chrome alloys may offer against forged steel, as well as laboratory test work investigating changes in pulp chemistry and improvements to metallurgical performance, a plant trial was commissioned at NewcrestÆs Ridgeway concentrator. The paper briefly describes these results.Newcrest decided to convert their media charge by the top-up method. To monitor the trial a sampling protocol was put in place whereby the pulp chemistry was monitored before, during and after the purge. The metallurgical shift data was analysed using various statistical methods to determine if the metallurgical performance had improved with the change in grinding media. While the analysis indicated that the metallurgy had improved, not all of the benefits could be assigned to the change in grinding media alone. However, the combination of reduction in media wear and the increases in copper and gold recoveries suggested that it was economically viable to operate with high chrome grinding media.As with many trials of this nature the prevailing economic conditions are fluid and a decision was made to revert back to forged steel grinding media in an effort to reduce operating costs. It was further agreed that Magotteaux could monitor the pulp chemistry and metallurgical changes in this reverse trial to confirm the results observed in the earlier conversion to high chrome grinding media.CITATION:Greet, C J, Hitchen, C and Kinal, J, 2012. Conducting high chrome grinding media trials at NewcrestÆs Ridgeway Concentrator, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 56-64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By B Clements, G Lane

The operations and project environments are very different, but overlap in many areas. The development of mineral processing projects is goal oriented, is schedule focused and is a contractual environment. The operating environment for a mineral processing plant is oriented around longer-term commitments, focused on delivery against budget expectations, and an environment heavily influenced by long-term personal relationships, community relationships, and people issues.Further contrast is evident in the way expenditure is managed. Projects commit large amounts of money quickly to meet schedule-based objectives. Operations manage expenditure to minimise operating costs and are able to, or are forced to delay decisions on large expenditures. However, these two environments need to come together in many ways, ranging from greenfields plant handover to a new operations and maintenance crew, to day to day interaction and management of brownfields projects, often in close proximity.This paper considers the different perspectives people bring to projects and early operations, including the advantages and disadvantages of æoperationsÆ input to a project and models for managing value adding during project development, implementation and debottlenecking.CITATION:Lane, G and Clements, B, 2012. Operations versus projects - How do people think and what are the implications?, in Proceedings 11th AusIMM Mill OperatorsÆ Conference , pp 11-16 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By B Davis, A H. Benzer, A N. Mainza, C M. Evertsson, L M. Tavares, M M. Hilden, M S. Powell, C Rule, G Asbj÷rnsson

The Mogalakwena North Concentrator of Anglo Platinum Operations was built with the capability to allow for future projected expansion. Several research groups, currently working with Anglo American on collaborative research over a range of projects, were brought in to review the existing operation, with a view to releasing some specific bottlenecks and providing specialist design input to the potential plant expansion.Based on a thorough review of the high pressure grinding rolls (HPGR) and crushing circuit, a wide range of de-bottlenecking opportunities were identified. This was followed by a series of surveys to provide performance measurements and to model the circuit in detail. From this effort a full simulation of the plant has been developed, including updated models of the HPGR, crusher, bins and screens. These models have been implemented in the researchersÆ Model Development Kit (MDK) version of JKSimMet, and in a prototype dynamic simulator based on the Matlab Simulink software.The observations, measurements and simulations have provided guidance and quantified the benefits of some proposed circuit modifications. Based on these findings a number of upgrades are being planned, with the aim of ensuring full utilisation of the installed equipment. The circuit demonstrates a potential expansion of over 30 per cent through minor improvements, and a 70 per cent increase in capacity with the addition of some strategic equipment.The HPGR-crushing upgrade project demonstrates the potential benefits of nurturing disparate Research groups into a strong inter-disciplinary technical team capable of supporting operational needs while developing future technology.CITATION:Powell, M S, Hilden, M M, Evertsson, C M, Asbj÷rnsson, G, Benzer, A H, Mainza, A N, Tavares, L M Davis, B, Plint, N and Rule, C, 2012. Optimisation opportunities for high pressure grinding rolls circuits, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 81-94 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By R Crosbie, K C. Runge, E Tabosa, J K. McMaster

Flotation feed density is an operating parameter which is currently not well understood. Most models of flotation only incorporate its effect on particle residence time, but it is likely to have additional effects within both the pulp and froth phases of the machine. Test work was performed in MetsoÆs 3 m3 RCS test rig to investigate the effect of flotation feed density on metallurgical performance. The rig was operated at Rio TintoÆs Northparkes operation using flotation feed and scavenger tail. For each feed, tests were performed at different feed densities, and measurements were performed to estimate the pulp and froth recovery as well as other key flotation parameters (eg bubble size, turbulence and froth stability). Results of this test work have shown that the pulp density does affect key parameters of the flotation process in both the pulp and froth phases. Pulp phase kinetic rates decrease at high density and this is attributed to a reduction in the turbulence within the cell. Froth phase recovery, however, improves presumably because of a stabilising effect due to a greater loading of solids on bubble surfaces.There is a need for more research to be done to better understand these interactions so that metallurgists can determine the optimum flotation feed density to use at a particular operation, or within a section of a flotation circuit.CITATION:Runge, K C, Tabosa, E, Crosbie, R and McMaster, J K, 2012. Effect of flotation feed density on the operation of a flotation cell, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 171-178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By W Valery, A Jankovic

A growing demand within the minerals industry for sustainable development and the introduction of carbon taxes have resulted in a significant focus on improving the energy efficiency of comminution circuits. However, in this drive for improved energy efficiency the role of classification has been overlooked. Inefficient classification and large recirculating loads reduce circuit capacity, result in over-grinding and higher specific energy consumption.It is well understood that classification increases mill capacity; therefore, closed ball mill-cyclone circuits have become an industry standard. However, due to limitations in cyclone classification efficiency, the optimum recirculating load is limited to about 250 per cent. A simple relationship quantifying the effect of classification efficiency and recirculating load on grinding circuit capacity is presented in this paper. The possibility of improving the capacity of ball mill circuits by improving classification efficiency is discussed, considering the current practical limitations of classification equipment. Simulation tools were used to evaluate circuits with cyclones and with high frequency screens to identify opportunities to improve energy efficiency. The investigation also identified potential benefits to flotation recovery due to a reduction in over-grinding.CITATION:Jankovic, A and Valery, W, 2012. The impact of classification on the energy efficiency of grinding circuits - The hidden opportunity, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 65-70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By R. E. Mitchell

Los proyectos mineros son revisados por medio de dos estudios: el primero es el Estudio de Impacto Ambiental (EIA) que evalúa proyectos mineros e industriales propuestos para obtener una programación reglamentaria y así ayudar al plan de desarrollo responsable de las compañías. El segundo sistema de evaluación es el Estudio de Impacto Social, Ambiental y sobre la salud (ESHIA) , cuyo enfoque es más inclusivo y comprensivo para evaluar potenciales impactos. En este sentido, el presente texto describe las normas de EIA para la provincia Alberta (Canadá) al tiempo que realiza un análisis comparativo entre el EIA y ESHIA.

Oct 1, 2012

By T Laing, M A. Abdalla, P Hagan

Open pit operators are facing a number of challenges in the area of blasting and blasting processes, such as wall control, quality of fragmentation, explosives consumption and vibration. Remaining financially viable is one of the most significant objectives for mining professionals as they work through the blasting challenges within the mining chain of processes. This objective is such a significant challenge, primarily due to the high consumption of materials and the direct consequences on the downstream processes in the mining work flow, including loading, hauling, crushing, milling and mineral concentration. This paper reviews and discusses a technique to achieve this objective, namely air-decking. The performance in a number of mines around the world is reviewed focusing on the economic contributions of air-deck blasting. Various scenarios are investigated and simulated, covering both conventional and air-deck blasting, using JKSimblast software. The scenarios explore a range of issues and found that optimum results could be achieved with a minimum amount of explosives. The results obtained from the simulations were verified with blasts at Rixs Creek Coal Mine, Australia. Based on the verification results the simulations were then modified to more accurately model the actual conditions and parameters on site and to ensure that the models derived meet the production and control requirements at the mine site. Ultimately, overall analysis and comparisons were applied to the outcomes of the conventional and air-decking blasts revealing a reduction in material consumption of around 25 per cent with consequential savings and up to a 30 per cent reduction in ground vibration.CITATION:Abdalla, M A, Laing, T and Hagan, P, 2012. The contribution of air-deck blasting to open pit mining economics, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 7-12 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By R Small, S Combrinck, R Lindsay

Maintaining your competitive edge in the growing Australian mining sector today is an arduous task. With an ever increasing demand to extract more ore, safely, complete visibility throughout the blasting cycle has become vital to any operation. To achieve this requires full two way communication with every detonator during the testing and programming cycle, as well as, inside the firing window. Concerned with an increase in the number of incidents involving mining equipment, uncovering and digging into unknown misfires on-sites across Australia, Black Star Mine made the decision to embark on the use of electronic detonators to eliminate this hazard. With this safety goal achieved, the mine set about using the added benefits of electronic detonators to improve their drill and blast processes with impressive results.CITATION:Combrinck, S, Lindsay, R and Small, R, 2012. Eliminating unidentified misfires at Xstrata ZincÆs open pits through the application of electronic detonators, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 27-30 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By T Trott, M Lewis, G Lumley

The analysis of equipment trends in The AusIMMÆs revision of Monograph 19 - Australasian Mining and Metallurgical Operating Practices (AMMOP) (in prep) in the paper by Graham Lumley raised some interesting, and in parts disturbing, trends in the Australian open cut mining industry. According to the Australian Bureau of Statistics (2011) the productivity of the whole mining industry is down by 34 per cent since 2001. In terms of open cut equipment, median output for draglines is down by 15 per cent since 2003, electric rope shovels are down by 41 per cent since 2003, hydraulic excavators are down by 39 per cent since 2008, front-end loaders are down by 39 per cent since 2007 and trucks are down by 41 per cent since 2006. Clearly e boom has not been good for the efficiency of the mines. During this same time, best practice (defined as the average of the top ten per cent by annual output per unit of input) has declined, but not by as much as the median (eg shovels down by eight per cent, excavators down by 19 per cent and FELs down by five per cent). This paper will build on the analysis of AMMOP to understand the differences occurring between median and best practice and identify the factors contributing to the decline in performance. As the industry enters a period of potentially lower prices for commodities and reduced margins, pressure will be brought to bear on mine sites to start moving more with the equipment they have. An understanding of where efficiency has been lost will be a key component in that. The information contained in AMMOP, and the subsequent analysis of that information in papers such as this one, will be crucial to reversing the decline in open cut equipment performance.CITATION:Lumley, G, Trott, T and Lewis, M, 2012. Reversing the trend in open pit mining equipment output, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 75-82 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By P Hagan, S Campbell

A study was undertaken using various methodologies to determine the optimum loading and hauling configuration for different haul routes at Callide Mine, a coal mine located in central Queensland. The study involved development of an effective flat haul model that was used to estimate production rates in truck and shovel circuits that employ two excavators of differing capacities then Queuing Theory to construct a capacity constraint model for scheduling purposes to assist in truck allocation and finally a cost model to determine the most cost effective fleet configuration.The model was calibrated using haul road design and performance data of trucks and excavators currently in use at the mine. The study examined the effects of cycle time for different truck and excavator fleet configurations on production rate and costs.The study found haulage cost was directly related to cycle time while production rate reduced with cycle time. The study indicates the approach taken in combining a cost model with a capacity constraint model offers a simple and effective method of scheduling an optimum number of trucks in a haulage circuit.CITATION:Campbell, S and Hagan, P, 2012. Selection of an optimum truck and shovel fleet based on effective flat haul and capacity constraint modelling, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 19-26 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By T. Kumaresan

The Bayer process used for refining bauxite to smelting grade Alumina serves as the linchpin of the Aluminum production industry worldwide. Even though the process is well established, the presence of impurities in the liquor affects the quality of product and imposes a major economic cost on the industry. This review article focuses on the issues pertaining to Gibbsitic (Al2O3.3H2O) precipitation circuit. The comprehensive review provides a basic understanding of the aluminum trihydrate precipitation and agglomeration phenomena. Crystal growth rate and agglomeration play a significant role in determining the output PSD of agglomerates. Hence, the effect of certain thermodynamic and hydrodynamic parameters along with the impact of impurities (oxalates, aldols, acids etc.) and additives on hydrate growth has been reviewed.

Sep 1, 2012

By B. Orberger

The fine fraction (< 2 mm) of the high grade Mn-ore from the world class Moanda deposit, Francevillan basin, in Gabon, contains up to 30 wt. % of manganese and about 0.4 wt. % phosphorous. A pilot study at laboratory scale integrating mineralogy and geochemistry before and after ultrasonic treatment was conducted on the fine fraction (< 2 mm) of oxidized Mn ore in order to reduce the phosphorous content and enrich this fraction in manganese. The fine fraction was dried, crushed at 2 cm and sieved at 2 mm. The two fractions (< 2 mm and 2 mm ? 2 cm) were investigated by X-ray diffraction and scanning electron microprobe ? electron dispersive spectroscopy analyses. Both fractions contain lithiophorite, cryptomelane and pyrolusite as Mn carrier, and goethite, muscovite, illite and quartz as contaminants. The Mn hydroxide nsutite was only found in the fraction 2mm ? 2 cm.The < 2 mm fraction is significantly richer in goethite, muscovite/illite, and quartz. Phosphorous carriers are mainly goethite (up to 2.8 wt. % P2O5), while the Mn minerals contain up to 0.8 wt. % P2O5. The Mn minerals are partly included in an agglomerate of goethite, muscovite/illite, and quartz. The < 2 mm fraction was treated by ultrasound for 30 s in normal water. Mineralogical and chemical analyses after ultrasound treatment showed that the Mn-minerals were largely liberated from the goethite-muscovite-illite agglomerate. Mass balance calculations show that after ultrasonic treatment the < 2 mm fraction was ? 50 % enriched in Mn and ?50 % impoverished in P.

Sep 1, 2012

By A. Pankewitz

The well-established on-line particle size analyzer OPUS manufactured by Sympatec GmbH, has been successfully implemented in several mining and industrial minerals project. OPUS monitors the particle size distribution in 31 fractions as well as the solid concentration in opaque and highly concentrated ore and mineral slurries on-line in real time e.g. behind mills or cyclones applying 31 ultrasonic frequencies for highest resolution. Ultrasonic extinction overcomes all limitations known from optical and mechanical systems like contamination, blockage and wear. OPUS measures slurries in their original state without any dilution, hence no extensive sampling procedure or sample conditioning is required thus no dilution errors occur. Due to the OPUS design and suitable algorithms entrained air bubbles do not affect the quality of analysis at all. The sensor covers particle size distributions from 0,01 to 3.000,00 µm and solid concentrations up to 70 % by volume and can be easily adapted to a number of production lines simultaneously. Jiangxi Copper?s Dexing Mine is one of the biggest copper mines in Asia and among the first users for OPUS on-line particle size and concentration analysis in mining industry. OPUS is connected to 2 process lines. Jiangxi Copper has implemented OPUS for into their central control system for the grinding & classifying circuit of one SAG mill and one ball mill. Analysis data and process control as well as optimization based on OPUS particle size and concentration measurements will be discussed Keywords: particle size analysis, ultrasonic extinction, concentration analysis, grinding control

Sep 1, 2012

By J. E. Gebhardt

Progress is reported on capturing the effects of gangue chemistry in the context of a comprehensive stockpile heap leach model for leaching copper sulfide ores, employing leading edge computational fluid dynamics (CFD) technology. The stockpile is a complex multi-phase process, comprising of a solid porous media, with complex fluid flow, gas and liquid phases, competing solid-liquid reactions, dissolution of minerals and transport through the heap. The model accounts for many of the challenging physical and chemical features of the heap, including transport and reactions kinetics for the important copper and iron sulfide minerals, ferrous oxidation, bacterial effects, thermal energy, acid and sulfate balances. In this contribution, the model has been extended to incorporate dissolution of various species from gangue reactions and precipitation of hydronium and potassium jarosite, ferric hydroxide, alunite, and gypsum. The effect of aeration on the simulation of a copper sulfide heap leach is provided as an example.

Sep 1, 2012

By R. Roufail

In this paper, the effect of different operating parameters of high speed stirred mill on the particle breakage mode is addressed. Morphological features of broken particles is investigated and related to the types of forces generated in the mill using Discrete Element Method (DEM). The stress intensities generated in the mill are varied by changing the agitator speed. The investigated agitator speeds were 1000, 1500, and 2000 revolution per minute (rpm). The minerals considered in this study are hard minerals (quartz) and soft, sulphide minerals (galena). The morphological features examined are roughness, roundness and elongation, which shed light on the mode of breakage during the grinding process. Particles that are rough, less round and elongated would imply that they broke via fracture, along their grain boundaries. On the other hand, the smooth, less elongated particles would mean breakage occurred across the grain, which is abrasion mod. DEM study complemented the understanding of particle breakage mechanism via tracking the types of forces applied on the particles. Normal forces imply compressive loading, which is presumed to impose fracture breakage along the grain boundaries, whereas tangential forces imply abrasion loading. Stirred mill grinding has been regarded as an attrition/abrasion process, whereas, this study showed that about 60% of total particles that are morphologically analyzed for both minerals were rough particles. Such an observation indicates that the fine product, which contain a significant amount of progeny from the coarse fractions are consistently broken via fracture. The morphology results agreed with the DEM findings, which indicated that the agitator speed, mineral type, and residence time would dictate the type and mode of particle breakage. Keywords: DEM, high speed stirred mill

Sep 1, 2012