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HIGHER PRODUCTIVITY THROUGH COOPERATIVE EFFORT: A METHOD OF REVEALING AND CORRECTING HIDDEN OPERATING

INEFFICIENCIES

By Adrian Dance1, Walter Valery2, Alex Jankovic3, David La Rosa4 and Sedat Esen5

1ManagerProcess Integration & Optimisation, Metso Minerals Process Technology AsiaPacific (MMPT-AP) Brisbane, Australia; 2General ManagerMMPT-AP, 3ManagerDevelopment and Process Engineering, MMPT-AP, 4ManagerProcess Control, MMPT-AP, 5Crushing Process Technology Engineer, MMPT-AP

ABSTRACT

Most operations continue to function with the mine and concentrator working in isolation. Both have separate objectives, separate cost centres and key performance indicators (KPIs) that do not reflect the customer/supplier relationships that inherently exist. Using these KPIs alone, the two entities appear to operate efficiently; however considering the whole operation, they often operate well below maximum efficiency.

Over the past ten years, the authors have developed a proven methodology for revealing these inefficiencies and have worked with operations around the world to significantly increase their production: generating typically 5 to 20% higher throughput. A number of recent optimisation and reenfield projects will be discussed in this paper to describe the structured approach taken and demonstrate the benefits that are achievable.

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CURRENT SITUATION

Despite considerable effort by Mine-to-Mill practioners over the past decade, many mining companies continue to operate in isolation, with the mine and concentrator focusing their attention on their own needs rather than the goals of the entire operation. This is usually driven by different sets of KPIs and separate cost centres. However, as frequently as there exists an uncaring supplier (i.e. mine) there exists an unsure customer (i.e. concentrator) about what their needs are.

When delivering material to the concentrator, the mine is well aware of the need of quantity but what of quality? Is it possible to improve the performance of the concentrator by changing operating practices and objectives upstream in the mine? Absolutely, and this has been demonstrated at numerous operations worldwide.

In light of current metal prices, operations are repeatedly asked (or told) to increase production normally, with little or no capital investment. This requires greater consideration of how they operate rather than the size or number of pieces of equipment they use. Most mining and processing professionals understand their business and do a good job of controlling their costs, focussing on their weaknesses and trying to improve their efficiency. However, what appears to be lacking is an awareness of how they impact the next phase of the process or their customer. This lack of awareness leads to inefficiency in the mine-concentrator interface. Ore has been defined as material that can be processed for a profit this may or may not have anything to do with grade. Unfortunately, grade is commonly the sole indicator of whether material is suitable to be sent to the concentrator.

In order to reveal the inefficiencies entrenched in our operating practices, we need to understand what rock properties are relevant. In other words, we need to characterise the material in terms of its downstream performance and be able to predict how well it will process. After discovering what properties are important to processing, they can then be termed quality parameters and used to determine if high grade material is truly ore or waste.

OPPORTUNITIES

Over the past ten years or so, Mine-to-Mill studies have focussed on the impact of run-of-mine (ROM) fragmentation or mill feed fragmentation on concentrator throughput. In these cases, the property of interest is material size: either the topsize, 80% passing size (P80) or distribution.

DEPARTMENT OF MINING ENGINEERING UNIVERSITY OF BRITISH COLUMBIA

Vancouver, B.C., Canada

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IV-377 So when considering the impact of feed size, what is the typical situation? Normally, the mine (or supplier) delivers material of sufficient quality to satisfy their own needs does it dig well? Will the truck loading be good? Will it fit in the crusher? Beyond that, there is typically little consideration of how to improve the quality of the ROM material further.

On the other hand, the customer (or concentrator) understands the impact of feed size on their process but normally only the negative effects and at the extreme levels: If the feed is too big, we have problems and if it is too small we also have problems. Quite often the effect of feed size on mill performance is not well understood and results in the customer not being clear in their requirements: Just dont give us the same stuff as last week.

Rather than focussing on the negative effects, the concentrator needs to understand how quality parameters can positively affect performance. In addition, understanding should be based on measurements that can be reproduced: We need more of the 25mm material in the feed than what we measured this morning.

Understanding which quality parameters are important to each concentrator is the first step. The next one is to measure them continuously if possible and then develop methods to control them so that the quality of mill feed is as high as possible.

By communicating with the mine how the quality of their product (or the concentrator feed) can affect downstream performance leads to ways to improve the value of mill feed. That is, ore can now be judged on its overall quality parameters and not just grade. Despite the grade, if certain material will not process well due to low production or higher costs that lowers its value. In addition, it eliminates the opportunity to process material of higher value by using up concentrator capacity.

Understanding and measuring important parameters that affect mill feed quality can lead to the identification and elimination of poor performing ores that should not be sent to the concentrator without being blended.

The reason that most operations do not follow this path to enlightenment is a lack of resources and a definite plan with clear objectives. Metso Minerals Process Technology Asia-Pacific (MMPT-AP), have been working with customers to develop such plans and to reveal the inefficiencies hidden in the way they currently operate. The work is rewarding in that often the improvements in efficiency are very significant. In the case of throughput, MMPT-AP projects typically result in increases of 5 to 20%.

MMPT-AP provide an integrated approach or methodology that eliminates costly (both in time and resources) plant trials, from which the

IV-378 benefits can be difficult to quantify. Also, MMPT-AP can provide the guidance and support to make the significant step changes that are sometimes required.

In the case studies discussed below, the quality parameter of interest is material size and the objective is increased production. There is no reason the same approach cannot be used for cost reduction, recovery increases or final product grade by characterising the material using other quality parameters.

METHODOLOGY

The methodology that MMPT-AP uses is called Process Integration and Optimisation (PIO) and has been developed over the past ten years at a number of operations worldwide. It represents a wider application of optimisation than Mine-to-Mill, as it can focus on any quality parameter of interest and not just feed size. That being said, most of our customers are interested in understanding how their material properties affect mill production and how to increase mill throughput.

The methodology involves a number of steps: benchmarking, rock characterisation, measurements, modelling/simulation and where required, material tracking. A PIO project is normally comprised of a number of site visits spaced over a few months. The first site visit is to establish current operating practice, initiate rock characterisation and collect measurements of blast fragmentation and mill performance. This is followed by modelling and simulation studies to determine how to best exploit hidden inefficiencies. These recommendations are then followed by further site visits to implement the changes, monitor the results and ensure the improvements are maintained over time.

We have made long-term agreements with some customers so that they have access to our services without the delay of setting up individual projects.

Benchmarking

The first step of a PIO project is to benchmark the current practices by auditing the operation and control of the blasting, crushing, grinding and flotation processes.

The quality of blast pattern implementation is assessed and the resulting ROM fragmentation measured using image analysis. The crushing, grinding and flotation circuits are surveyed and process control strategies reviewed. All of these measurements allow mathematical models to be developed for the complete process chain. These models are later used to simulate the impact of operational changes in the mine or concentrator on the entire process.

IV-379 Rock Characterisation

Once the current operating performance has been measured under one set of conditions, the effect of changing rock properties can be quantified. This involves rock characterisation. The MMPT-AP methodology for rock characterisation utilises simple and inexpensive measurements that can be performed by trained site personnel. Quite often, the measurements are already being collected by the operation. The advantage of simple measurements is the amount of data that can be collected in a very short timeframe, as the samples do not require shipping to an outside laboratory. When attempting to characterise an entire orebody, the density of data is very important.

For rock characterisation, MMPT-AP use measurements of rock strength (Point Load Index, PLI and/or UCS) and rock structure (Rock Quality Designation, RQD and/or fracture frequency). Both PLI and RQD measurements can be taken on drillcore and Point Load tests can also be performed on irregular shaped samples of material.

The PLI value can be correlated to Unconfined Compressive Strength (UCS) as well as the JKMRC Drop Weight test parameters A and b. The Drop Weight parameters are necessary in order to model the crushing and grinding circuits. Therefore, the use of the Point Load Index allows sites to characterise their rock properties quickly and easily while still making use of the sophisticated grinding models that are available. The rock structure is represented by the RQD value that indicates the fracture frequency present in the drillcore. This measurement is routinely taken at operations for geotechnical purposes but has been shown to be very useful in blast fragmentation modelling in the absence of detailed rock mass structure mapping. Once the PLI and RQD data are available, the range of rock properties are mapped out and domains are defined (see Figure 1). Within each domain, the material will behave similarly in the blasting, crushing and grinding processes while all of the domains cover the complete range of rock properties that are present.

Figure 1: Rock Strength and Structure Domains

IV-380 (When flotation is involved, material domains are defined based on different characterisation measurements, but the method is the same.)

The domain structure shown in Figure 1 follows the existing ore type characterisation used by the site but expands further into areas of structure (coarse, medium and fine) and strength (soft, medium and hard). The ranges of strength and structure used are based on the variability of the orebody. The more variable the PLI and RQD values measured in the orebody, the greater definition required for domains.

In the example shown in Figure 1, there are three levels of strength and three levels of structure for each ore type: or a possible total of nine domains per type. If a domain does not occur significantly in the orebody, it may be combined with a nearby domain so that the overall number of domains is less. In Figure 1, there are a total of ten domains defined for the two ore types shown.

Once the domains have been defined, different blasting practices, crushing and milling operational strategies are established. Through modelling and simulation studies, the impact of blending different domains can be reviewed. Most importantly, as the rock properties have now been well characterised and the processes modelled, the variable nature of the material can now be compensated for.

For example, consider Domain 6 in Figure 1. This material is of Ore Type 1 and both hard and coarse in structure. This indicates that it would require higher energy blasting to overcome the difficult rock properties. Otherwise, the resulting ROM fragmentation will be difficult to crush and mill. On the other hand, Domain 1 is soft and fine in structure (highly jointed). This material can be blasted will less energy and achieve an adequate fragmentation size. In most cases, operations use the same blast pattern (and hence powder factor or energy level) for all material in one ore type (or even all ore types). The rock characterisation method details how and where energy should be usefully applied and not wasted.

In the example discussed, the quality parameter of interest is mill feed size and the objective is to maximise mill production. By developing customised blasting practices for each domain, the resulting ROM fragmentation can be controlled much better. The result is more consistent mill throughput by compensating for the different rock properties.

Measurements

Another aspect of MMPT-APs methodology is the heavy reliance on measurement. If material size is the quality parameter of interest, the first site visit is used to collect measurements of size: ROM fragmentation, primary crusher product and mill feed.

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IV-381 In addition, attempts are made to measure the reduction in material size for different ore types or domains in order to calibrate the mathematical models over a wider range of conditions.

Image analysis is used to measure blast fragmentation by collecting numerous photographs of the muckpile as well as haul trucks dumping at the primary crusher. For measurements of crushing and grinding circuit performance, surveys are performed to collect data on all the process streams. When concentrator recovery and/or final product quality are the issues, surveys of the separation circuits are performed as well.

Modelling/Simulation

The measurements collected while at site are combined with the rock characterisation domains to model the complete process chain. MMPT-AP uses these data to develop site-specific models of blast fragmentation, crushing, grinding and flotation. This allows customised blast patterns to be developed that optimise both crushing and grinding performance. For each domain, blast designs are recommended to generate the optimal fragmentation size for downstream processes. This may involve an increase or decrease in energy level (or powder factor) depending on the rock characteristics of each domain.

The objective is to minimise the overall cost for the entire process by distributing the energy required sensibly and effectively where it is best applied. Near-field vibration measurements and models are used to confirm that pit wall stability issues are considered in the blast designs.

In addition, the crushing and grinding models allow the impact of operational and control strategies to be investigated. For example, what is the best closed-side-setting to operate my primary crusher at in terms of production and product size? What target load should I use in my SAG mill when processing this domain? What is the tendency for this material to be SAG mill, ball mill or recycle crusher limited?

All of these questions can be evaluated using the model of all the stages of comminution (blasting, crushing and grinding).

Material Tracking

Using the MMPT-AP methodology of optimisation, it is very important to understand what type of material is being processed at any point in time. That is, which domain or domains is the material part of?

This is necessary in order to observe the effect of different ore sources (and the blending of sources) on concentrator performance. By monitoring concentrator KPIs with different material, the actual and expected performance can be compared. This was discussed in detail in an earlier paper (Dance, 2005).

IV-382 There are currently two methods to track material movements from the mine to the concentrator: model-based and sacrificial instruments. These are illustrated in Figures 2 and 3.

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IV-383 The first method of tracking material involves the development of a software program to record the movements of material from the open pit or underground to the intermediate or long-term stockpiles, through the crusher and coarse ore piles and into the concentrator. Each stockpile can be represented by simple perfect mixing models or if necessary, more sophisticated three-dimensional models. The models allow the effect of material mixing and delays to be incorporated and provide a reasonably accurate estimate of mill feed. In the trend shown in Figure 2, the material transactions were updated every fifteen minutes combining the different ore sources into packets that were tracked through the inventories and into the concentrator. Such a system provides much greater definition or detail on changes in concentrator feed. In Figure 2, the twenty-four hour period shows episodes of stockpile versus muckpile feed, intermittent feed when the primary crusher was not operating as well as changes in the blend of different blocks of ore. A daily summary will not provide such a degree of detail.

Another method for tracking material movements being employed by MMPT-AP are Ore Block Markers or OBMs. MMPT-AP have developed passive radio frequency (RF) transponders for use in blasted material monitoring. These RF tags are small, robust and inexpensive and can be dropped into the blasthole stemming column or placed on the muckpile surface post-blast (see Figure 3).

The tags are not powered but are detected by antennas placed over conveyor belts (see Figure 4). Each tag has a unique identifying number that the antenna transmits to a remote computer for recording along with the date/time. By noting the initial position of each tag (i.e. blasthole ID), an estimate of the origin of the material being processed can be made. By tracking the actual material itself, concerns about estimating stockpile volumes, mixing and retention times can be avoided.

Figure 4: Typical OBM Antenna Installations (Temporary)

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APPLICATIONS OF PROCESS INTEGRATION

In this section, a number of case studies will be summarised illustrating the MMPT-AP methodology in a variety of applications. All of these cases are actual projects conducted by MMPT-AP in the past few years.

Case Study 1: Conventional Crushing Circuit

This site was operating three crushing circuits ahead of SAG and ball mill circuits and was interested in ways to reduce operating costs and increase crusher and mill throughput. Two of the crushing plants were owned while a third plant was contracted out to provide additional capacity.

MMPT-AP conducted a Process Integration and Optimisation program in order to recommend changes in operating practices.

The initial phase of the PIO study was dedicated to benchmarking the blasting performance in the pit. A typical production blast was chosen for auditing and the implementation and performance of a blast was monitored. Hole depth variance, drilling accuracy, explosive usage and blast performance (with particular attention to fragmentation), were all measured during the site visit.

Blast fragmentation modelling was then undertaken to determine new blast designs that would decrease the ROM particle size and rehandle costs. These blast designs were adopted by site and represented a 3.5% increase in total blasting costs. The results of the finer fragmentation were quite dramatic with an increase in crushing plant productivity of 21 to 32% and the cessation of the contract crushing plant operation. In addition, excavator productivity increased and primary crusher rock breaker usage decreased significantly. Overall, the improvements in productivity more than accounted for the increase in drill and blasting costs.

Case Study 2: SAG/Ball Mill Circuit

This operation was experiencing lower SAG mill throughput due to a higher proportion of harder material. MMPT-AP deployed their PIO methodology to characterise the range of rock properties expected to be processed to the end of mine life and estimate their impact on mill production.

As always, the PIO project commenced with an audit of the sites current drill and blast, crushing and grinding practices. This included an audit of a typical production blast along with the use of Ore Block Markers to directly measure the concentrator performance on the audited material.

IV-385 Rock characterisation based on PLI and RQD values showed that the blast domains were relatively simple: all ore types showed strength variations but were not significantly different. At the time of the site visit, the operation was using the same blast pattern for all ore types.

Measurements taken while at site identified issues with blast design implementation that would result in variable ROM fragmentation. In addition, problems with the primary crusher operation and selection of SAG mill grate size were affecting mill production.

MMPT-AP recommended blast designs for the different domains that would compensate for the change in rock properties. In conditions where wall stability was a concern, alternate designs were provided. The lack of flexibility in the operations blast designs meant that harder and less fractured material was being under-blasted while the softer and more fractured material was being over-blasted. The recent drop in mill production was due to an abundance of under-blasted material.

The definition of blast domains based on rock strength and structure would allow the blast engineer to compensate for changing rock characteristics and stabilise the ROM fragmentation size and result in increased crusher and mill throughput.

Interestingly, the recommended blast designs were at energy levels or powder factors lower than what the operation had recently trialled. However, these trials were not considered a success due to their unstructured nature and a lack of measurements. Plant trials are costly and time-consuming and often produce unclear results. The blast audit approach taken by MMPT-AP in their PIO projects involving material tracking with OBMs and direct measurement of its performance has a greater chance of producing a clear outcome of an operational change.

Following on from the blast recommendations, simulations of the grinding circuit showed an expected increase in throughput of 15 to 20% with a combination of finer fragmentation and crushing/grinding circuit changes.

Case Study 3: Greenfield/Brownfield Project

This study involved an operation that was surface mining using a combination of ripping and low powder factors, but was aware that the rock characteristics would change as the pit went deeper. The question to be answered was: how would mill production be affected over time as the material strength and structure changed?

The PIO project involved an audit and calibration of the blast fragmentation model to the current operating practices. Based on PLI and RQD measurements of drillcore, MMPT-AP estimated how concentrator performance would change over time and whether additional grinding power would be required to maintain design mill throughput.

IV-386 The drillcore results indicated that with depth, both the PLI and RQD values would increase and then plateau (see Figure 5).

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Blast designs were recommended for the changing rock conditions that also considered the proximity of the nearby town. Models of airblast and vibration were used to determine the maximum energy levels possible without exceeding allowable limits.

The material was characterised into blast domains and simulations of blast and grinding conditions were performed to identify circuit restrictions as the material changed with depth. The availability of Work Index (Wi) test results allowed a relationship between Point Load Index (Is50) and Wi to be developed.

Based on the current mine plan, a plot of expected material strength (UCS) and Work Index over the next twenty years was produced (see Figure 6).

In addition, the minimum powder factor required to maintain design concentrator throughput was estimated. It was concluded that the current SAG mill circuit would not be able to operate at design tonnage for the life of mine. Additional grinding capacity would be needed in around seven years time to maintain or exceed design throughput.

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Case Study 4: Throughput Forecasting

In this project, rock characterisation and blast domain definition was used to improve on existing throughput forecasting models already available to site personnel. The rock characterisation was based on measurements of drillcore and the fragmentation and grinding models calibrated to site conditions using measurements collected while at site.

This operation had collected a considerable amount of information on their daily concentrator feed and this data was used to confirm the accuracy of the throughput model.

Based on the drillcore data of PLI and RQD, the four lithological groups (Volcanic, Diorite, Intermediate Tonalite and Young Tonalite) were divided in sub-domains of similar properties (see Figure 7). Some of the domains were combined with adjacent ones and the resulting rock characterisation map produced 16 distinct domains.

For each of the 16 domains, a standard blast pattern was recommended that the operation should implement. For flexibility, both high and low powder factor designs were provided for each domain. The exclusive use of these designs not only compensated for the different rock properties and stabilised the ROM fragmentation, it resulted in crusher and mill performance that was more predictable by the model. In other words, by minimising changes in the ROM size, the throughput model could more

IV-388 accurately predict concentrator throughput. Deviations from the recommended blast designs would result in the model over or underestimating mill production.

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Figure 7: Blast Domain Mapping (16 Domains)

In addition to the blast fragmentation model, crushing and grinding circuit models were produced with the output of one becoming the feed to the next. The structure of the MMPT-AP throughput forecasting model is shown in Figure 8.

Following the flow of data in Figure 8, ore characterisation and blast domain information are combined with the blast design conditions into the fragmentation model. The resulting ROM size distribution is then fed to the primary crusher model along with the rock properties. The primary crusher product size distribution is then input into the grinding circuit model that can estimate throughput, specific energy requirements and final product size. In the future, it is expected to include a site-developed grind/recovery model of flotation.

The throughput forecasting model estimates the mill performance for each of the domains in the daily blend of material. The overall mill performance is then calculated based on the amount of each domain sent to the concentrator.

A comparison of the model predicted daily production and the actual recorded production for an eighteen month period is shown in Figure 9. The model has been shown to be quite accurate and very useful in both mine planning (until end of mine life) and interpreting daily concentrator performance. The model estimates assume ideal blasting, crushing and grinding performance based on the conditions entered.

IV-389 The predicted mill throughput then represents what is achievable by the operation with good blast implementation as well as consistent crusher and grinding circuit operation.

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CONCLUSIONS

Metso Minerals Process Technology Asia-Pacific has over the past ten years developed a proven methodology for optimising the mine-concentrator interface. This method involves characterisation of the rock strength and structure using simple and effective measurements. These measurements can be done by site personnel at little or no expense and are calibrated to more comprehensive measurements like the JKMRC Drop Weight test. The end result is a mapping of rock characteristics into domains of similar properties.

The methodology involves a number of steps: benchmarking, rock characterisation, measurements, modelling/simulation and where required, material tracking. A project is normally comprised of a number of site visits spaced over a few months.

Based on the rock domain definitions, blasting, crushing and grinding models are used to determine specific operating and control strategies that optimise the efficiency of processing each domain. This methodology has been used in a wide range of applications from conventional circuit optimisation, throughput forecasting and greenfield operations. For existing operations, significant increases in performance have been realised through the application of the MMPT-AP methodology.

Where operations continue to work with the mine and concentrator in isolation, hidden inefficiencies can be revealed through the development a complete process model and considering the impact of operational practices on the downstream process.

REFERENCES

Dance A.D., 2005, Closing the Loop Using Actual Concentrator Performance to Determine the True Value of Ore Sources, CIM Bulletin Vol 98, No. 1086, March/April 2005.

Renner D., et. al., 2006, AngloGold Ashanti Iduapriem Mining and Milling Process Integration and Optimisation, proceedings SAG 2006, Sept 23 Sept 27, Vancouver, Canada.

Tondo L.A., et. al., 2006, Kinross Rio Paracatu Minerao (RPM) Mining and Milling Optimisation of the Existing and New SAG Mill Circuit, proceedings SAG 2006, Sept 23 Sept 27, Vancouver, Canada.

INTERNATIONAL AUTOGENOUS AND SEMIAUTOGENOUS GRINDING TECHNOLOGY 2006VOLUME I OF IV VOLUMESIntroduction and Table of ContentsANTAMINA DESIGN THROUGH TO OPERATIONLAGUNA SECA, THROUGHPUT INCREASE SINCE START-UPOPTIMISATION OF THE SOSSEGO SAG MILLCOMMISSIONING AND OPTIMISATION OF A SINGLE STAGE SAG MILL GRINDING CIRCUIT AT LEFROY GOLD PLANT ST. IVESGOLD MINE KAMBALDA / AUSTRALIACOMPARISON OF SAG MILL POWER DRAW ESTIMATES OVER THE LAST 20 YEARSTHE DESIGN, START-UP AND OPERATION OF THE PHOENIX PROJECT SAG MILLSINGLE STAGE SAG MILLING AT THE TARKWA GOLD MINENORTHPARKES MINES SAG MILL OPERATIONSBATU HIJAU SEVEN YEARS OF OPERATION AND CONTINUOUS IMPROVEMENTSLURRY POOLING AND TRANSPORT ISSUES IN SAG MILLSKCGMS ORPHAN SEMI-AUTOGENOUS GRINDING MILL(An Untold Success Story)GRINDING POWER: TOO MUCH OF A GOOD THING?IMPROVING THE EFFICIENCY OF BALL MILLING CIRCUITS FOLLOWING AUTOGENOUS/SEMIAUTOGENOUS GRINDINGCOMPARATIVE EVALUATION OF GRINDING MEDIA CONSUMPTION RATES AT FULL PLANT SCALESAG GRINDING INTEGRAL OPTIMIZATION PROJECT AT CODELCO NORTEMILLING CURVES AS A TOOL FOR CHARACTERISING SAG MILL PERFORMANCETHE VALUE OF RIGOROUS SURVEYS THE LOS BRONCES EXPERIENCEANGLOGOLD ASHANTI IDUAPRIEM MINING AND MILLING PROCESS INTEGRATION AND OPTIMISATIONINSTRUMENTED BALL DEVELOPMENT AND USEAPPLIED MAGNETIC SEPARATION TECHNIQUES TO IMPROVE MILLING CIRCUIT PERFORMANCESERVICE AND MAINTENANCE FOR GEARLESS MILL DRIVESPROBLEM DEFINITION AND REPAIR OF THE ROTOR POLE STRUCTURE ON ONE OF THE WORLDS LARGEST GEARLESS DRIVE SAG MILLSFORGED FABRICATED MILL GEARINGEVALUATING THE RELIABILITY PROFILE OF SOUTH AFRICAN PLATINUM CONCENTRATOR PLANTS BASED ON PRIMARY MILL PERFORMANCECHALLENGES OF LUBRICATING HIGH-HORSEPOWER OPEN GEARING IN MODERN MINING SCENARIOS.ATTEMPTING TO QUANTIFY IMPROVEMENTS IN SAG LINER PERFORMANCE IN A CONSTANTLY CHANGING ORE ENVIRONMENTSECONDARY CRUSHED FEED BEFORE SAG MILLING AN OPERATORS PERSPECTIVE OF OPERATING PRACTICES AT PORGERA AND GRANNY SMITH GOLD MINESNEWMONTS MILL 5 MULTIPLE PURPOSE PLANTAUTOGENOUS AND SEMIAUTOGENOUS MILLS 2005 UPDATE

VOLUME II OF IV VOLUMESIntroduction and Table of ContentsHOW BIG IS BIG? REVISITEDLARGE GEARLESS DRIVEN MILL SYSTEMS RESPONSIBILITIES AND CAPABILITIESHISTORY OF WELD DESIGN FOR GRINDING MILLS (a participant's view)INVESTIGATING MILL HARMONICSA NEW PULP DISCHARGER FOR EFFICIENT OPERATION OF AG/SAG MILLS WITH PEBBLE CIRCUITAPPLICATION OF THE HYPER SER DRIVE TO SAG MILLSA MECHANICAL ALTERNATIVE TO THE GEARLESS DRIVE ? THE CAM DRIVEMILL CASTING DESIGN: EXPERIENCE VERSUS THEORYINTRODUCTION OF A NEW MILL BRAKING TECHNOLOGYTHE GEARLESS MILL DRIVE, THE WORK HORSE FOR SAG AND BALL MILLSPROTECTION AND SUPERVISION SYSTEMS FOR GEARLESS MILL DRIVESVIBRATION, INSTABILITY AND RESONANT SPEED ISSUES IN GEARLESS MILL DRIVESLESSONS LEARNED FROM RECENT FAILURES OF GEAR DRIVES ON MILLS IN SOUTH AFRICATHE OPERATION MODES OF A GRINDING MILL WITH GEARLESS DRIVEAUTOGENOUS AND INERT MILLING USING THE ISAMILLTHE ROLE OF CRITICAL-SIZED MATERIAL IN AG AND SAG GRINDINGANGLOGOLD ASHANTI GEITA GOLD MINE: UPGRADING OF THE 22 FOOT DIAMETER BALL MILLSAG AND BALL MILL CIRCUIT DESIGN FOR KINROSS RIO PARACATU MINERACAO (RPM) EXPANSIONDESIGN AND IMPLEMENTATION OF AN AVC GRINDING CIRCUIT AT BHP BILLITON CANNINGTONKINROSS RIO PARACATU MINERAO (RPM) MINING AND MILLING OPTIMISATION OF THE EXISTING AND NEW SAG MILL CIRCUITRoM BALL MILLS - A COMPARISON WITH AG/SAG MILLINGA REVIEW OF SAG CIRCUITS CLOSED WITH HYDROCYCLONESCOMMINUTION CIRCUIT SELECTION -KEY DRIVERS AND CIRCUIT LIMITATIONSCRUSHING PRACTICE IMPACT ON SAG MILLING: ADDITIONOF SECONDARY CRUSHING CIRCUIT AT GEITA GOLD MINEBATU HIJAU CONTROLLED MINE BLASTING AND BLENDING TO OPTIMISE PROCESS PRODUCTION AT BATU HIJAUINNOVATION IN PRIMARY GYRATORY CRUSHER MANTLE DESIGNUSED IN SAG & CONVENTIONAL MILLING OPERATIONSAG MILL PEBBLE CRUSHING: A CASE STUDY OF PT FREEPORTINDONESIAS CONCENTRATOR #4PRECRUSHING SAG MILL FEED

VOLUME III OF IV VOLUMESIntroduction and Table of ContentsADVANCED GRINDING MILL RELINING FOR PROCESS METALLURGISTS AND MANAGEMENTCURRENT DEVELOPMENTS IN SAG MILL LINER DESIGNOPTIMIZING SAG MILL LINER CHANGES THROUGH PROCEDURES AND LINER DESIGNAPPLICATION OF A 6T LINER HANDLER FOR CADIA VALLEY OPERATIONS 40 SAG MILLMILLMAPPER: A NEW TOOL FOR GRINDING MILL THICKNESS GAUGINGSAG MILL LINER WEAR AND BREAKAGE AT THE NEW CONCENTRATION PLANT OF THE SARCHESHMEH COPPER COMPLEXGRINDING MILL RELINING TECHNOLOGIES FOR ALL LINERS, GREAT AND SMALLA STRUCTURED APPROACH TO MODELLING SAG MILL LINER WEAR NUMERICAL MODELLING OF LINER EVOLUTIONA STRUCTURED APPROACH TO MODELLING SAG MILL LINER WEAR MONITORING WEARINVESTIGATING THE FEASIBILITY OF LINER WEAR SENSOR DEVELOPMENTIMPACT RESISTANT POLY-MET SHELL LINERS FOR SAG MILLSOPTIMIZATION OF THE LINER DESIGN AT KENNECOTT UTAH COPPERS COPPERTON CONCENTRATORSAG MILL CONTROL INSTABILITY: CAUSES AND SOLUTIONSCURRENT TRENDS IN SAG AND AG MILL OPERABILITY AND CONTROLCOMPARATIVE STUDY OF GRINDING EXPERT CONTROL ON TWO SABC CIRCUITS AT BARRICK GOLD COPORATIONHOLISTIC APPROACH TO SAG MILL CONTROLOPTIMIZING THE OPERATION OF A SAG MILL THROUGH OPTIMUM LOAD ESTIMATION AND CONTROLGRINDING EXPERT SYSTEM OPERATION AT RED DOG MINEEXPERIENCES IN CHARGE VOLUME MEASUREMENT AND THE POTENTIAL OF MODELINGEXPERT MILL CONTROL AT ANGLOGOLD ASHANTISAG-Tools(TM) AN ON-LINE SYSTEM FOR MONITORING CHARGE CHARACTERISTICS IN GRINDING MILLSINVESTIGATING ON-THE-SHELL ACOUSTICSEVOLUTION OF AG MILL CONTROL SYSTEM AT BOLIDEN MINERAL ABTHE DEVELOPMENT OF AN ON-LINE SURFACE VIBRATION MONITORING SYSTEM FOR AG/SAG MILLSTHE USE OF PERFORMANCE MONITORING TECHNIQUES IN DETECTING PROCESS SHIFTS & POTENTIAL ROOT CAUSES IN A VARIABLE SPEED GRINDING APPLICATIONLOAD IMPACT MANAGEMENT IN AN OPERATIONAL SAG MILL USING ADVANCED PERFORMANCE ENHANCEMENT INSTRUMENTATIONLESSONS LEARNED IN THE APPLICATION OF DEM FOR SAG MILL LINER DESIGN: KEMESS A CASE STUDYAN INVESTIGATION OF ROCK ABRASION AND BREAKAGE IN A PILOT-SCALE AG/SAG MILLDEVELOPMENT OF A SAG MILL SHELL LINER DESIGN AT CADIA USING DEM MODELLINGAPPLYING DISCRETE ELEMENT MODELLING TO DIFFERENT MODES OF BREAKAGE IN AG AND SAG MILLSA PROPOSED MECHANISTIC SLURRY DISCHARGE MODEL FOR AG/SAG MILLSINVESTIGATING SAG MODEL ASSUMPTIONS USING LABORATORY 3D TRAJECTORY DATA

VOLUME IV OF IV VOLUMESIntroduction and Table of ContentsAN OVERVIEW OF HPGR TECHNOLOGYHPGR CHALLENGES AND GROWTH OPPORTUNITIESHPGR IMPLEMENTATION AT CERRO VERDEA PRE-PRODUCTION REVIEW OF PT FREEPORT INDONESIAS HIGH PRESSURE GRINDING ROLL PROJECTAPPLICATION OF HPGR TECHNOLOGY IN PROCESSING GOLD ORE IN AUSTRALIATHE DEVELOPMENT OF A PROCESS FLOWSHEET FOR THE NEW ANGLO PLATINUM, PPRUST NORTH CONCENTRATOR, INCORPORATING HPGR TECHNOLOGYHPGR VERSUS SAG MILL SELECTION FOR THE LOS BRONCES GRINDING CIRCUIT EXPANSIONENERGY EFFICIENT COMMINUTION HPGR EXPERIENCE AT ANGLO RESEARCHCASE STUDY - INVESTIGATION OF HPGR SUITABILITY FOR TWO GOLD/COPPER PROSPECTSA STUDY OF THE EFFECTS OF HPGR TREATING PLATINUM ORESFLOWSHEETS FOR HPGRHPGR THE JOURNEY FROM SOFT TO COMPETENT AND ABRASIVEKHD HUMBOLDT WEDAG 150 YEARS OF INNOVATION NEW DEVELOPMENTS FOR THE KHD ROLLER PRESSDEVELOPMENT OF IMPROVED LABORATORY AND PILOTING TEST PROCEDURES AT MINTEK FOR THE DESIGN OF AG/SAG MILLING CIRCUITSSAG DESIGN TESTING WHAT IT IS AND WHY IT WORKSINVESTIGATING THE EFFECT OF IMPACT SPEED ON BREAKAGEROCK CHARACTERISATION FOR HIGH PRESSURE GRINDING ROLLS CIRCUIT DESIGNDESIGN OF AG/SAG MILL CIRCUITS USING THE SMC TESTSMALL-SCALE CONTINUOUS SAG TESTING USING THE MACPHERSON AUTOGENOUS GRINDABILITY TESTAN OVERVIEW OF THE SMALL-SCALE TESTS AVAILABLE TO CHARACTERISE ORE GRINDABILITYDIGGING INTO A LARGE TESTING DATABASEDETERMINATION OF AUTOGENOUS GRINDING CHARACTERISTICS IN THE GTK PILOT PLANTRISING TO THE CHALLENGE: MINIMISING RISK AND FORECASTING FOR A NEW ORE BODYHIGHER PRODUCTIVITY THROUGH COOPERATIVE EFFORT: A METHOD OF REVEALING AND CORRECTING HIDDEN OPERATING INEFFICIENCIESUSE OF POINT SAMPLES TO ESTIMATE THE SPATIAL DISTRIBUTION OF HARDNESS IN THE ESCONDIDA PORPHYRY COPPER DEPOSIT, CHILEGEOMETALLURGICAL MAPPING AND MINE MODELLING (GEMIII) THE WAY OF THE FUTUREDOMAINING FOR GEOMET MODELLING: A STATISTICAL/GEOSTATISTICAL APPROACH