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By T G. Vizcarra, T J. Napier-Munn, A T. Karbowiak, M G. Hart

Squeezing extra performance from existing equipment (‘sweating the assets’) is key to continuous improvement initiatives, particularly during times of cost cutting where the option of spending additional capital to facilitate circuit upgrades can be severely constrained. A common challenge, however, is identifying the best combination of settings for different process variables, as their effects can be camouflaged by interactions with other process variables and, of course, noise in historical data.This paper describes a recent investigation at Boyne Smelters Limited to identify strategies to coarsen the product of its dry, fixed-speed, open-circuit AG mill, without the need for installing pre-screens prior to the mill. The product is used as insulation material for the reduction of alumina to aluminium, and an excessively fine product was inhibiting the ability of the cover material to dissipate heat from the underlying anodes. The approach was to undertake a series of experiments, designed according to statistical criteria, to elucidate the effect of key process variables (feed blend and power draw) upon the product sizing. The results provided clarity about what strategies would encourage the production of a more desirable mill product (with some surprises). The study is a good example of how properly designed experiments can identify hidden potential in processing circuits, thereby mitigating the need for capital-intensive upgrades.CITATION:Vizcarra, T G, Hart, M G, Karbowiak, A T and Napier-Munn, T J, 2018. Getting the most from existing processes: using cleverly designed experiments to optimise the line 3 AG mill at Boyne Smelters Limited, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 207–216 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By D Phillpotts, S M. Mantsho, P Strobos

A challenge on many industrial flotation circuits is controlling concentrate mineral grades using measurements that are provided infrequently. The mineral grades in concentrate streams are a critical performance indicator in any industrial flotation circuit. Failure to achieve concentrate mineral grade targets has significant financial consequences on a flotation operation. A violation of a gangue mineral grade limits by the concentrator may also result in significant penalties. Online grade analysers which can provide reliable real-time grade measurements are essential for effective grade optimisation. The Blue Cube MQi analyser (by Blue Cube Systems) has recently come to prominence for its ability to rapidly determine mineral concentrate grades online and in-stream. This has provided excellent insight into the actual process dynamics in the flotation circuit, and hence enabled real-time control and optimisation of concentrate mineral grades. MintekÆs Measurement and Control division, specialising in advanced control solutions for mineral and metallurgical industries, has had the opportunity to link the FloatStar Grade-Recovery Optimiser to the measurements provided by the Blue Cube system at a nickel concentrator plant. The project initially focused on stabilising the final concentrate grade without directly accounting for nickel recovery. The site later procured additional Blue Cube MQi analysers, resulting in the expansion of the FloatStar Grade-Recovery Optimiser to incorporate recovery component in the performance. This site already had the FloatStar Grade-Recovery Optimiser for several years, but the original grade measurement device was unreliable and ultimately failed. The system was reactivated once the Blue Cube system was installed, replacing the old analyser.CITATION:Mantsho, S M, Phillpotts, D and Strobos, P, 2012. The implementation of FloatStar grade-recovery optimisation control solutions using Blue Cube online grade analysers on industrial flotation circuits, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 363-368 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By D Wei

Large tonnages of low-grade haematite ores need to be treated every day in China. One of the mineralogical characteristics of these haematite ores is that the grain size of haematite is smaller than that of quartz and is not uniform in the ores. Therefore, a flow sheet consisting of gravity concentration, low-intensity magnetic separation, high-intensity magnetic separation and reverse flotation is mainly used to separate haematite ores in China, to obtain acceptable beneficiation performance and reduce the operating costs. Nowadays, whether based on mineral processing practice or theoretical analysis, the results show that the application of the above-mentioned flow sheet is able to take full advantage of these mineral processing methods and achieves satisfactory benefi ciation of haematite ores. For example, when the iron grade of the haematite ore is about 29 per cent Fe, a concentrate assaying 68 per cent Fe can be obtained and the recovery of iron is over 80 per cent. In the future, research work on the beneficiation of haematite ores should focus on investigating the most feasible particle size for gravity concentration circuit feed so that the operating costs can be reduced and ultimately the separation performance can be improved.

Jul 11, 2011

By K J. Riihioja, E Nozawa

SmartTag is a radio frequency identification (RFID) based technology designed to allow tracking of ore from its source through blasting, run-of-mine (ROM) pads, crushers, intermediate stockpiles and finally into the concentrator. This paper presents current developments and the future direction of the SmartTagÖ ore tracking system, as well as presenting some case studies. Successful applications of the SmartTag system have encouraged development to allow the system to be used in a wider variety of plants, in particular plants with finer crushing and screening stages. This presented Metso with a number of technological challenges, including RFID tag and antenna design. By reducing the traditional RFID tag diameter from 60 mm to 20 mm the RFID tags can now successfully pass through a secondary crusher. The new smaller RFID tags (referred to as mini RFID tags) have been used in some Process Integration and Optimisation projects with very promising results. The results indicate that the miniature RFID tags have a higher survivability to blasting and through secondary crushing stages. Extending ore tracking further through the process allows more reliable linking of spatial data with time based process performance. Metso is looking at developing even smaller micro RFID tags, and is also investigating other applications for the SmartTag system, including ore tracking from the original source to the final destination (ie from the mine, through the plant and ports to the customer).

Sep 26, 2011

By A Roudnev, P Loderer

Mineral froth pumping utilising centrifugal slurry pumps is a major engineering challenge for both the end users and pump manufacturers. The traditional approach has been to oversize the pump for pumping mineral froth. New horizontal slurry froth pump designs offer opportunities to improve froth pumping capability of mineral froth with challenging (high) Froth Volume Factor while maintaining high efficiency, long wear life and stable pumping performance.CITATION:Loderer, P and Roudnev, A, 2018. A reliable solution for pumping mineral froth with challenging froth volume, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 291–296 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Toro HCH, Von Borries GH

A brief description of the semi-autogenous grinding (SAG;) facilities of Compania Minera Disputada de Las Condes is given. A data-logging and computer system was connected to the plant inter facing the existing analog control system in a supervisory s, control philosophy. The development of a control straiov,v t,) maintain maximum power of the SAG mill atsubjected to process restrictions is shownThe present control scheme is discussed inalgorithm was designed based on correlations onLween vartaoles. Associated with this, a direct level of control was developed be, on classical control algorithms, process inter-active tuning has been included. Also, an algorithm to prevent overloading of the is discussed. Control scheme tests are presented in comparison t manual operator control under the same conditions. It is shown t the control strategy gives a more stable operation and a higher plant throughput.

Jan 1, 1985

Mine Dewatering for reoccupation of a flooded mine requires rehabilitation and recommissioning of shaft and sane level functions to provide safe efficient access, services and logistics, as well as securing connections with all exposed workings. The objective is the earliest secure reoccupation of the target depth horizon for minimum water pumping, consistent with an appropriate investment and optimum schedule of operating inputs to the dewatering, redevelopment, services and consolidation processes. Strategy must focus on recommissioning of relevant functions in the shaft and at stage pumping horizons, advance of logistics close to pumping and rehabilitation, management of the secured exposed workings. The progress must be systematic, sustained and integrated, and must be secured against risk and uncertainty. There must be a strategic capability to respond effectively, and manage interruptions to processes, conditions requiring higher or different resources, and contingencies which affect schedule, budget or risk profile for the continuing programme. Planning must aim to reduce or contain risk or uncertainty elements and contingencies, limit interruption frequency and severity, identify and provide the capability for efficient responses. It is appropriate to model and simulate the reoccupation analogous to a mine initial development production programme. Only minor changes to relationships and relativities of models for Capital works, Operations (Production and Development) and Services/Logistics are needed but the model for management of workings is more relevant than that for depleted workings in an operating mine because of the water and other transfers. An important difference is the unsteady state of operations which requires probabilistic modelling of availability and utilization of equipment and processes.

Jan 1, 1988

SASOL Synthetic Fuels has recently completed the design of sampling systems for raw and blended coal feeding the gasifiers at Secunda, South Africa. The new systems will replace manual, stopped belt sampling and have been designed to achieve specific accuracy targets on a daily basis. The sampling system is unusual in the coal industry in that the fines content (-5.5 mm nominal) of the coal is very critical and is to be determined with high accuracy.The sampling system was designed to meet carefully considered target accuracies using methods of modern sampling theory. The heterogeneity of the coal streams involved with respect to the critical analytes was determined by appropriate sampling and sample analysis. The statistical characterisation of the time variation of analytes in the process streams was based on variograms derived from on-line ash gauges. From this point, the design was completed using fundamental statistical sampling theory and some simulation studies. The paper discusses the development of the sampling system design in detail as well as the plans to use the data stream to provide timely alarms when the coal quality deviates from the target specification.

Jan 1, 2002

By G J. Jameson, A Agarwal

This paper is concerned with the observation and analysis of bubble clusters in a laboratory flotation cell. A device was used in which bubbles were allowed to rise in clean water containing the same frother and collector concentration as in the cell. Bubble clusters were recorded using a high speed camera and analysed using an image analyser. Dodecyl amine was employed as a collector to float silica. The effect of impeller speed on the cluster behaviour was investigated. The results were interpreted in terms of cluster diameter and shape factor. The sizes of the bubbles forming the clusters were also measured and compared to the sizes of the independent bubbles in the cell. It was found that there was an optimum impeller speed in which the cluster diameter was a maximum. Higher agitation and the consequent higher power inputs resulted in cluster break-up while lower shear rates promoted cluster formation.

Jan 1, 2005

By D Cliff

"Recent underground coal mine incidents have again raised the issue of: under what circumstanceis it safe for personnel to re-enter the mine? Mine rescue guidelines make recommendations aboutthe limits in terms of the circumstances, lives at risk, no lives at risk and training exercises. Theseare based upon percentages of the upper and lower explosive limits. Many factors infl uencesett ing limits for safe re-entry. These include: the representativeness of the sampling location(s),the rapidity of gett ing an underground sample analysed and the rate of change of the atmospherebeing monitored. Value judgements based upon these parameters will then infl uence the sett ing ofa trigger point based upon per cent explosibility. This raises the question of how the percentage ofthe lower or upper explosive limit is established. It is easy to defi ne this when the sampling pointdata sit on the fresh air limit line. However - what value is used when the sample sits somewherein the body of an explosibility diagram? This paper explores the various options and illustratesvarious pitfalls and problems that are faced in making such a determination. These include howthe data are represented and the assumed knowledge of those doing the interpretation."

Jun 1, 2012

By B Broad

"Establishing ventilation in the early stages of a new mine is an essential step to achieve scheduled outcomes that ultimately drive the financial success of an operation. If the primary ventilation is not in place in time to support a contractorÆs work output, then the ore delivery is likely to be severely impacted. Options to increase ventilation in order to address shortfalls are limited. This in turn can lead to reduced revenue generation at a time when a mine is at its highest capital outlay. This can have implications for any company, but even more for an explorer moving to producer. The ventilation put in place to cover the start-up period is also unlikely to cover any extended or increased load required to meet schedule delays.The following paper examines two issues in relation to ventilation with a focus on small to medium projects where the company is establishing a mine using a mining contractor. The issues being: potential impacts on the contract and tender process when using a mining contractor key mine design considerations, such as æcrunch timeÆ, as they interact with ventilation achieving a successful ramp up.A recommendation is made for higher levels of detail around secondary ventilation leading up to the primary fan installation. The information should be included as part of the tendering process and preliminary project execution planning. Understanding the æcrunch timeÆ concept can lead to strategies, as well as back up plans, to minimise any negative impact.By understanding key risks around primary ventilation establishment for a new mine, detailed design work can be completed where it is needed most. Value is added by reducing uncertainty and a payback with better contract terms and a more robust ramp up plan. This will improve the economic return for the company and reduce the risk.CITATION:Broad, B, 2013. Contract considerations and other critical ventilation aspects in achieving a new mine ramp up, in Proceedings The Australian Mine Ventilation Conference, pp 207-214 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 1, 2013

With the use of 86 rock drills of the jackhammer type at the West Lyell Open Cuts of the Mt. Lyell Mining & Hailway Co., it is of importance to determine the economic as well as the physical life of these machines. With this purpose in mind records have been kept of the footage bored and the cost of new parts placed in each machine, and the following procedure adopted.A graph is plotted for each machine showing the footage bored as a horizontal line and at each 5,000 feet of boring the total cost of new parts noted on this line. (See l"ig. 1.) Thus at a glance it is possible to see... the amount of work done by each machine and the money spent on it in new parts. However, it is difficult to visualise from this graph the increase in the cost of new parts for each machine as its life advances. To obviate this difficulty a curve is plotted with the cost of new parts as the vertical component and the distance bored as the horizontal component. As before the cost of new parts are taken at each 5,000 feet bored. (See Fig. 2.) The curves so obtained are particularly interesting for two reasons:1. Each machine has its characteristic curve.2. The curve always steepens.Some machines are found to have relatively flat curves, others flat curves for approximately 15,000 feet of boring, and others steep gradients from the begining.This demonstrates that it is not always economic to discard a drill after it has been in service for a certain length of time or after it has bored a specified number of feet. Each drill has its own characteristics and so must not be regarded as one of a class, but considered on its own performance.The following use of these curve diagrams has been made to determine whether a machine has reached the end of its economic life. Figure 3 shows...

Jan 1, 1942

By M Haest, S Sandler, R Botha, H Lang, K Hume

Benchmark practices in the mining industry include the establishment of Quality Programs — Quality Assurance and Quality Control (QAQC) — to monitor the correct execution of sampling protocols and control each stage of the ‘Sample Cycle’: Sample Collection, Preparation (comminution) and Analysis. QAQC reports commonly include statistical-numerical results that quantify performance of QAQC controls (field duplicates, preparation duplicates, blanks, standards etc). Graphics such as scatter plots, QQ plots, histograms and cumulative frequencies are used to represent the results. Statistical values including relative difference, absolute difference, relative variance, averages, T-test, and Zscores are used to quantitatively express the relationship between duplicate pairs ... but is an effective quality program just a statistical exercise? This paper aims to highlight the concept of ‘Quality Management’ (QM) as the precursor of continuous monitoring (ideally in real time) of QAQC results on Exploration, Production, Processing and Port samples, determined by trend analysis performed on a time and/or grades basis. Currently, there is a paradigm in the process of quality assurance that if individual data points fall within a predetermined acceptance limit then they are ‘acceptable’ and therefore suitable for informing operational and investment decisions. However, what is stated with respect to QM is that sometimes results found within the acceptance limits can indeed be internally biased, or show material deviations over a period of time, thereby impacting reconciliation results and/or potentially creating discrepancies with the final buyers. QM refers to the proactive detection of these ‘anomalous tendencies’, the approach and communication with the source of the information, the understanding of the reasons that cause the deficiencies, and the generation of agreed action plans to remediate the situation and ensure the consistency of results, in other words: continuous improvement on proactive manners.

Mar 22, 2022

By D McCoy

Titanium feedstocks are the building blocks of the titanium value chain. They can be mined directly, as is the case for ilmenite, leucoxene and rutile, or manufactured from ilmenite by extracting various quantities of non-TiO2 components from the ore by chemical and/or thermal processes.While feedstocks can be grouped into categories of materials with similar characteristics, they are essentially unique products from very different mining locations around the world. In fact, no two feedstocks are exactly the same. As such, the variations between the available feedstocks, in combination with the permutations in processing technologies to turn the feedstocks into titanium pigment or metal, mean that choices between feedstocks are specific to the location in which they are utilised.In this paper, the authors examine the key requirements of titanium feedstocks to the TiO2 pigment and metal sectors. Apart from the well known differences between feedstock choices for the sulfate and chloride process, the more opaque considerations in feedstock sourcing are examined.

Oct 5, 2011

By A Boucher, M Baudin, P Androszczuk, I Minniakhmetov, A Rigby, P Machado, M Wright, B Van Dijken

IGO Ltd’s (IGO’s) Nova Operation (Nova), which is 160 km east-north-east of the town of Norseman in Western Australia (WA), mines and processes nickel-copper-cobalt (Ni-Cu-Co) sulfide ore from the magmatic Nova-Bollinger Deposit (Nova-Bollinger), which is hosted by the Mesoproterozoic age high-grade metamorphic rocks of the Albany Fraser Orogen. Over its 56-month life-of-mine (LOM) operations to 31 December 2020, Nova has processed 5.63 Mt of ore grading 2.04 per cent Ni, 0.86 per cent Cu and 0.07 per cent Co from its underground mine. At the end of 2020, both the Nova-Bollinger JORC Code reportable Mineral Resource estimate (MRE) and Ore Reserve estimate (ORE) were >90 per cent classified in the highest JORC Code confidence categories of Measured Mineral Resource and Proved Ore Reserve respectively. The high JORC Code classification confidences assigned to the Nova-Bollinger MRE and ORE results from the 386 km of surface and underground diamond drill testing of the deposit to a nominal 12.5 by 12.5 m pierce point spacing in mineralisation. The close spaced high-quality drilling and bulk mining method employed at Nova has effectively removed the need for any grade control modelling outside of the MRE process. Importantly, having only the one fully drilled out deposit being mined and only the one process plant, Nova’s reconciliation process is in the fortunate situation of not being confounded by issues such as external ore sources and constant updates as new grade control information becomes available. IGO’s Nova reconciliation processes are focused on reconciliation ratios that quantify operational period differences between the MRE and ORE head grade and tonnage forecasts and the process plant head actuals. These metrics have been used to identify key reconciliation issues and have initiated several studies into the causes for specific reconciliation results, which are discussed in the paper. In late 2020, a period of sustained poor reconciliation results led to the recognition that increasing the understanding of risk between the MRE and ORE should be investigated. To assist with modelling stope level risk within the mine plan and subsequent reconciliation, an attempt was made to develop a formula to quantify ‘stope risk’ from MRE metrics such as sample spacing, kriging efficiency and so on

Mar 22, 2022

By A Bagis

Road tunnels are an accepted and effective transportation solution in urban areas to mitigate increasing traffic congestion and facilitate improved urban connectivity in a cost effective manner while meeting societal goals to reduce the impact of construction. In designing a tunnel system, there is a requirement to achieve an acceptable level of in-tunnel air quality, as well as meeting ambient air quality goals. In Australia, there is also a requirement for zero portal emissions which means that all pollutants must be emitted to the atmosphere via a ventilation stack.Traditionally, effective pollutant dispersion has been achieved by constructing tall ventilation stacks which disperse pollutants into the atmosphere at a high level. The dominant variable parameters in the effectiveness of the dispersion under the ventilation engineers control are the efflux velocity, the height of the ventilation outlet and the concentration of pollutants at the point of discharge. During off-peak operations the required ventilation exhaust rate can be reduced due to the decrease in traffic. This can lead to a drop in the efflux velocity from the stack and therefore the effectiveness of the dispersion. This potentially drives the need for a higher outlet, or an increased exhaust rate to achieve a higher efflux velocity with consequent effects on energy consumption.The paper proposes a method of varying the cross-sectional area of the ventilation stack with the use of motorised control dampers, thereby maintaining a sufficiently high efflux velocity throughout the 24 hour period independent of traffic conditions. This allows the use of a potentially shorter ventilation stack.

Mar 8, 2011

By R deMoraes, A Bobet

The last decade has seen a resurgence of interest in lunar exploration and the emergence of countries like China and India as space fairing nations. In 2004, the US announced a new Vision for Space Exploration, whose objectives focused on human missions to the Moon and then Mars. The near future is likely to see the emergence of a worldwide drive to revisit the Moon as the first step in investigating the Solar System. To date, the Apollo missions provide our only experience of human operations on the Moon or anywhere else beyond Low Earth Orbit. Much was learned from these missions. However, their short duration means that many of the environmental effects that will be important for longer-duration missions could not be quantified. In addition, long-duration missions and infrastructure on the Moon require new technologies and capabilities, which must operate successfully and reliably in this lunar environment. Developing these technologies poses significant challenges for the exploration program. The paper discusses the risks associated with the construction of lunar surface and underground structures and the challenges to adopting the standards and rock mass classification systems developed on Earth and their applicability to the Moon. Moreover, an exchange of views to explore near-surface geologic and geotechnical profiles of the Moon is emphasized and implications of the lack of knowledge on rock mass characterisation of the Moonrock mass, the lack of theoretical/empirical experience on the use of rock mass systems outside Earth, and uncertainties.

Nov 29, 2022

By Koeng R, Richardson M, Hoare R

A discrete event computer simulation model was developed for two of the stoping methods currently used at the Z.C. Mines Broken Hill oper- ations. The objective in undertaking this project was to provide an effective tool for mine planning and design to allow comparisons of alternative extraction strategies and attempt to optimise the allocation of capital equipment and human resources. The Slam II simulation program was used in conjunction with ,a com- monly used data editor, text editor and graphics package to allow the simulation to be done on a personal computer with minimum training requirements. The computer hardware used was a portable computer cur- rently available using 80386/20MHz electronics. Specific logic techniques were developed to allow the Slam II language to simulate mining opera- tions because it was originally developed for manufacturing and com- mercial simulations. The design of the model was based on observations and a data collec- tion campaign. The model was designed with flexibility which allows simple editing of the input data which includes: - Insitu volumes - Development statistics -Loadout efficiencies -Loader speeds, availabilities and capacities -Chute numbers, volumes, distances and blockage statistics -Trucking statistics -Work schedules -Utility statistics

Jan 1, 1988

By G D. Matthews, M E. Haylett, S Khosrowshahi, A Weeks

In narrow orebodies the use of ordinary kriging (OK) may pose certain limitations when used for grade control modelling. The smoothing effect of kriging, by its very nature, cannot retain or accurately characterise the dispersion (variability) that is inherent in gold deposits. This dispersion is a critical component of determining the desired level of ore loss and dilution.Fixed block model positions used in OK, and all estimation approaches, within a grade control process may never align with the ‘true’ ore boundary. This may lead to excessive ore loss and dilution, especially within narrow lodes.Using a risk-based approach to ore block design based on the geostatistical method of conditional simulation (CS) can highlight the differences achieved when an alternative method to OK is used for grade control modelling. By using a mesh of nodes and the application of a ‘transfer function’ to the simulation models, the position for ore contacts can be better assessed than when using fixed blocks in OK. Therefore, the value of various ore block boundaries can be better analysed by objective assessment of ore loss and dilution for a given minimum mining selectivity (selective mining unit or SMU), even in narrow lodes.A case study of a narrow vein gold deposit, comparing the results from an OK model and a CS model shows that whilst both models show similar trends – waste, low-grade, and high-grade regions are the same in both cases – the simulation model can provide greater insight for optimal definition of the mineralisation boundary.CITATION:Haylett, M E, Weeks, A, Matthews, G D and Khosrowshahi, S, 2014. Ore block design in narrow vein gold deposits – estimate or simulate?, in Proceedings Ninth International Mining Geology Conference 2014 , pp 421–424 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By E Hernandez, I Agustian, W Kusumohastuti

PT Freeport Indonesia is completing the first underground gyratory crusher excavation at their Deep Mill Level Zone (DMLZ) mine located in the mountains of Jayawijaya, District of West Papua, Indonesia. DMLZ is an underground block cave mine with an expected output of 80 000?t/d and a scheduled production start in 2015.In order to deliver crushed ore to the mill through the existing conveyor belt, the DMLZ block cave mine will construct two 1000?kW 1.6?×?2.3?m gyratory crushers with their own respective ore flow conveying systems underground. Each crusher is composed of top, middle, and bottom chambers with an ore bin. This system includes a series of high capacity conveyors approximately 5 km in length including transfer stations and support facilities.The development methodology required a combination of lateral development by jumbo drilling machines and vertical development by mechanised raise climbers (MRC) due to the complexity of the chamber design.This paper will discuss the project scope, design and development methodology, ground conditions, innovative survey controls, and the challenges faced due to the remote location.CITATION:Hernandez, E, Kusumohastuti, W and Agustian, I, 2014. Excavating the first underground Gyratory Crusher at the Deep Mill Level Zone mine, PT Freeport Indonesia, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 43–50 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014