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By N Guresin, M Rohde

A lead-zinc flotation tailings sample containing silver from BHP Billiton’s Cannington Mine has been characterised to understand occurrences of silver in the tailings by conventional elemental, X-ray diffraction (XRD) and size analyses followed by mineralogical analysis with a scanning electron microscope (SEM) equipped with mineral liberation analysis (MLA) software and the use of an adapted diagnostic leach process originally developed for gold containing materials.The tailings sample contained 67 g/t Ag, 1.8 per cent Pb and 0.52 per cent Zn. The XRD analysis showed that the sample consisted of 74 per cent silicates, nine per cent sulfides, 11 per cent magnetite and small amounts of other minerals such as fluorite, fluorapatite and rutile. The p80 and p50 of the sample were determined to be 106 µm and 38 µm, respectively. The silver distribution was high in the small size fraction with 52.1 per cent of the silver being in the -8 µm fraction. The silver minerals freibergite, acanthite, jamesonite, pyrargyrite and native silver were observed in the mineralogical analysis of the sample by SEM/MLA. The associations of the minerals were intricate and the occurrences of silver were complex. There were finely disseminated silver minerals and also coarser grains of silver minerals in composites with the host minerals. It was estimated that almost 50 per cent of the silver was contained in pyrargyrite, around 14 per cent as native silver and contained in acanthite, 12.5 per cent in galena and around ten per cent in freibergite and jamesonite.These composite particles and the type of the silver minerals present were expected to limit leaching efficiencies of the silver in hydrometallurgical processing. The diagnostic leach tests showed that around 50 per cent of the silver could be recovered by direct cyanidation and higher extractions could be achieved by more aggressive acidic systems.Cyanidation tests were conducted to confirm the findings of the diagnostic leach studies. The investigated cyanidation parameters were time (up to 48 hours), solid to liquid ratio (1:1 and 1:2), cyanide concentration (0.025 M, 0.5 M and 0.1 M) and particle size (p80 of 106 µm, 63 µm and 7.5 µm). The effects of oxygen and lead nitrate were also studied. The tests were conducted at atmospheric temperatures. The maximum silver recovery obtained was about 50 per cent for all the parameter ranges trialled except particle size. The decrease in particle size from 106 µm to 7.5 µm by fine grinding resulted in an increase in silver recoveries from 50 per cent up to approximately 82 per cent indicating that the liberation of the silver grains/minerals is one of the factors affecting the cyanidation recovery of silver in addition to the presence of refractory silver minerals not amenable to cyanidation.Low head grades of silver in the tailings and relatively low cyanidation recoveries of silver (without fine grinding) necessitate a thorough cost analysis for the cyanidation of the Cannington lead and zinc tailings to assess if cyanidation would be a suitable process option for the extraction of silver. It is clear that one of the most important factors in determining the cost feasibility will be the price of silver in the world metal market.CITATION:Rohde, M, Guresin, N and Johnson, N W, 2014. Characterisation of silver minerals in lead-zinc flotation tailings and their response to cyanidation, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 163–172 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Szymanski J

In the first part of this paper, the principal sources of dilution during underground evaluation and mining are discussed, then definitions of ore dilution currently in use are analysed. These definitions vary depending on the authors. Ten different analytical expressions of dilution percentage currently exist. It is demonstrated, with the help of a numerical example for a given mining condition, that dilution percentage results vary considerably and that they depend on the definition used. This situation makes it difficult to compare different results regarding the dilution problem, often because some of the terms used are contradictory. A new ore dilution evaluation methodology is proposed, replacing the ten different analytical expressions by only two: the planned dilution factor related to the stoping selectivity, done at the mine planning level, and the additional dilution factor related to the efficiency of the dilution control measures during stoping operations. The conclusion shows that the use of this methodology would be a definitive asset in planning, in stoping operations follow-up, and in future costs comparison studies between mining operations.

Jan 1, 1995

Sulphide Corporation Pty. Limited operates a Lead/Zinc Smelter at Cockle Creek, some 11 miles from Newcastle, N. S. W . Works effluents totalling some 8, 500, 000 gallons/day join Cockle Creek some 1. 8 miles from its mouth in the most northerly section of Lake Macquarie, The Creek is also the source of the Works cooling water intake of which approximates 8, 000, 000 g.p. d. In view of the wide use of the Lake for recreational activities by the people of Newcastle and the surrounding areas, particular care must be taken to ensure that the control of effluent quality is of a high order. This paper outlines the philosophy and measures taken for the treatment and control of plant effluents discharging into Cockle Creek.

Jan 1, 1971

By R Cooksey

The Globe-Progress Mine is an open pit gold mine that is part of the larger Reefton Goldfields deposit located on the West Coast of New Zealand. The regional geology comprises a series of north to south oriented fold structures that have undergone post-deformation mineralisation. The structural geology within the mine itself is more complex, with major shears hosting numerous high-grade mineralised quartz shoots and splays that have been historically mined.The selective mining of ore within the pit is challenging due to the orientations of the hanging wall and footwall areas of the main Globe shear zone, the lithologies of these areas which range from highly brecciated and sheared material to competent mineralised host rock, and in the hazards presented by the numerous old historic underground workings. The coordination of drilling, modelling and excavation of the ore requires careful planning to maximise recovery whilst operating with the pit design boundaries.Grade control packages are custom designed to reflect the orientation of the footwall and hanging wall mineralisation. The shear material in the footwall zone dips between 60° and 70° and requires angled drilling whereas the footwall mineralisation is contained in shallow dipping quartz veins sub parallel to bedding and can be vertically drilled to best intercept the mineralisation. Ore excavation is directed so that the contact between the footwall and hanging wall is mined in the correct direction so that any non-visual ore contacts can be safely mined and that the ore-waste dilution is reduced.The ongoing grade control and selective mining of the Globe Progress deposit continues to deliver high grade ore for processing by ensuring that waste and dilution of ore is reduced and that recovery is maximised.

Aug 22, 2011

By D R Quick

The Goodall gold mine is located 30 km east of Adelaide River, within the Pine Creek 1:250 000 map sheet, at 8 525 000 mN: 750 000 mE, on the AMG grid. The first gold was poured in April 1988 and the mine closed in September 1993, having produced 228 400 ounces of gold from 4.095 million tons of ore, at a head grade of 1.99 g/t. Oxide and primary ore was mined from one large open cut and low grade oxide ore from three smaller pits. The gold mineralisation was discovered in 1981 by means of a helicopter borne rock chip sampling survey, which delineated 13 discrete anomalies. Systematic grid sampling of rock chips outlined an area of 1300 m by 300 m within the 2.0 g/t contour. Over 7500 m of costeaning was used to delineate the A and B-Pod mineralised areas. Geochemical soil sampling played only a minor role in the discovery and geophysics none at all. By the end of 1984, 40 diamond drill holes had been completed and a resource of 3.63 million tonnes at 3.0 g/t calculated. In January 1985, Western Mining Corporation Ltd became a joint venture partner and funded exploration to cam a 60 per cent interest. Additional drilling led to a feasibility study in 1987, based on a Measured and Indicated resource of 4.25 million tonnes at a grade of 2.35 g/t. The host rocks are quartzo-feldspathic wacke and interbedded phyllitic siltstone, of the Proterozoic Burrell Creek formation. The main zone of gold mineralisation, A-Pod, occurs in a sub-vertical vein array, up to 50 m wide and 800 m in length, of quartz and sulphide veins (5-20 mm wide), It is parallel to and on the east limb of an upright, north plunging anticline. Five types of veining have been recognised, with the bulk of the gold mineralisation associated with quartz-pyrite-arsenopyrite and chlorite-quartz-pyrite veins. The gold occurs as particles, from 1-20 micron, as inclusions and along fractures in pyrite and arsenopyrite and to a limited extent in chlorite. The mineralisation is epigenetic and structurally controlled by fractures developed during an earlier folding event. The gold is assumed to have been derived from the underlying sediments of the Koolpin Formation by hydrothermal fluids emanating from the deep seated northern margin of the Cullen Batholith. Precipitation of gold may have been controlled by variations in temperature and pressure.

Jan 1, 1994

By H Q. Zhang, M C Chai, W Fu, H Y Chen, L M. Wei, Q J. Yang

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Fozichong deposit – located in the south-western segment of the giant Qinhang metallogenic belt, South China – is a large-sized lead-zinc polymetallic deposit. This deposit contains two main ore districts, termed as the Guyi ore district in the north and the Hesan ore district in the south respectively. We present an integrated data set on sulfide minerals, fluid inclusions and stable isotope (H-O-S-Pb) geochemistry to better understand the features and genesis of the Fozichong deposit.Field and paragenetic relationships indicate three mineralisation stages forming the early (Po+Sp+Gn+Ccp+Py+Di+Ep+Qtz), middle (Sp+Gn+Ccp+Py+Ep+Chl+Qtz) and late (Gn+Sp+Py+Qtz+Cal) sulfide assemblages respectively. Mineral chemistry – particularly S/Fe and Co/Ni ratios in pyrite, Zn/Fe, Zn/Mn and Zn/Cd ratios in sphalerite and Pb/Ag ratios in galena – indicates a magmatic association for the sulfide minerals.Quartz and calcite coexisting with the sulfide minerals of various stages host abundant fluid inclusions. Quartz in the early stage contains two- or three-phase CO2-H2O and liquid-rich aqueous inclusions, which have homogenisation temperatures of 162~365°C and salinities of 2.9~17.8 wt per cent NaClequiv, whereas quartz and calcite from the middle and late stages are dominated by two-phase, liquid-rich aqueous inclusions that have slightly lower homogenisation temperatures (153°C~320°C) and much lower salinities (1.0~6.0 wt per cent NaClequiv). Hydrogen isotopes (dD = -59‰~-41‰), analysed using fluid inclusion waters from quartz and calculated oxygen isotopes (d18OH2O = -5.47‰~4.00‰) for the equilibrated ore fluids, indicate that the ore-forming fluids may have been sourced from magma and mixed with groundwater in the late stages. Sulfide minerals have d34S values of 2.3‰~4.3‰, consistent with a magmatic-derived source for sulfur. Lead isotopes (206Pb/204Pb = 18.592~18.794, 207Pb/204Pb = 15.648~15.864, 208Pb/204Pb = 38.909~39.580) confirm that lead and, by inference, zinc were mainly derived from magmatic rocks, with subordinate contributions from sedimentary rocks.Various lines of evidence support that the formation of the Fozichong deposit has close genetic association with the granite porphyry intruded in the late Yanshanian period (106 Ma), and it can be classified as a magmatic hydrothermal type lead-zinc deposit. We propose that the Hesan and Guyi ore districts may represent the proximal and distal products of a magmatic – hydrothermal system respectively.CITATION:Fu, W, Zhang, H Q, Chai, M C, Yang, Q J, Chen, H Y and Wei, L M, 2015. Genesis of the large-sized Fozichong lead-zinc polymetallic deposit, Guangxi, south China – constraints from the sulfide mineralogy, fluid inclusions and isotope geochemistry , in Proceedings PACRIM 2015 Congress, pp 609–614 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Mowat B. A

I lamata is within the Morobe Goldfield (7¦ 25' S, 146¦ 39' E) on the Wau (SB 55-14),1:250,000 scale map sheet (Fig 1). The deposit is 13 km SW of Wau, within the headwaters of the Upper Watut River, at an average elevation of 2000 m. The steep mountainous terrain is covered by dense tropical rainforest and access is by helicopter or by foot track. The deposit has been described previously by Wells and Young (1991) and 1)enwer. Leach and Mowat (1995). Data collected to late 1996 have been used to estimate an Inferred Resource of 9.2 Mt at 3.1 g/t gold using a cutoff of 0.5 g/t. This contains a high grade portion for which an Inferred Resource of 1.2 Mt at 9.7 grt gold has been estimated using a 5.0 g/t cutoff.

Jan 1, 1997

By Thompson M

The humble gabion basket is to mine development what the light bulb and safety pin are to eir-ryday life. Gabions provide a flexible, easy to assemble and cost efficient solution for "101" mine and civil engineering development applications.In some instances gabion baskets are still efficiently in use after many years of faithful, maintenance-free service. In other situations, the baskets have been demolished or made redundant within days, either having served their temporary usefulness or negligently destroyed by the operator of heavy equipment. Either way, the gabion basket must surely rate among the top 10 cost efficient engineering construction materials.

Jan 1, 1994

By J Loeb, J Dampney, P Cameron

Optimisation of Blast Design and Execution must be done right the first time. It is too late after the ore is broken. Consequences of poor design and execution negatively affect productivity from load and haul through the primary crusher to processing and hence reduce mine site profits. Harnessing and utilising ‘big data’ from geology, geometallurgy, drill hole location, powder loading, blast timing, blast movement and fragmentation to close the loop in blast design and optimise the blast increases productivity across the entire value chain from Mine to Mill. As the internet of things and artificial intelligence increases the quantity of data available, being able to capture and utilise this data to advantage is a challenge. Recent advances in software and hardware together with the increased power of cloud computing allows engineers to close the blasting loop to increase mine site productivity. Numerous case studies over the years detail significant gains from implementing the innovative technologies available to Mine to Mill projects. The opportunity is available for all members of the multi-discipline teams at each mine site to actively ensure productivity improvements are realised and maintained not only in their area, or silo of responsibility but across the entire mine site. This paper refers to recent case studies which outline how significant improvements in productivity are available to all mining operations to increase mine site profitability and dividends to shareholders.

Jun 22, 2022

By Littlewood E

We offer these notes as a practical contribution. All the arguments we advance have been tested by practical experience.In its preparation we realised that our subject was one of such importance and covered so wide a field that, dealt with by one of us alone, it might easily have been too much for him, so we have endeavoured, by mutual criticism and advice and a pooling of ideas, to bring forward a few points that may be of advantage to members. If any of the paper is of benefit to mining on the "Golden Mile," or elsewhere, we shall feel amply repaid for our efforts.It is obvious to all that the longer the machine is working productively per shift the greater the return, to all concerned; the machine-man himself and the company. Furthermore, if a man commences a shift with a definite objective in view; for instance, to bore and fire a specific cut, which he recognizes will give him a good financial return, then that man will exercise all his capabilities to attain that objective.In this paper we hope to demonstrate the value to the machine-man of the knowledge of the capabilities of each hole he bores, so that he will be enabled to utilize his drilling time to the greatest advantage. Also, we hope to show that such drilling time can be advantageously extended.After the war, with the influx of new men to the industry, some education on the finer points of machine work may be desirable, and any instruction in this branch must stress the realization of the value of each hole.We realise that most of those present have a sound workable knowledge of machine-mining, and we are not trying to teach anyone the fundamentals of machine work, but we would like to bring to their attentIon some of the finer points which we believe are very important.The machine-man has control of gear of a capital value of over £150, and the use or misuse of that material has a direct bearing on working costs. Therefore it is imperative that the capital outlay is gainfully employed.A "bogger" in charge of a 5/- shovel engaged unproductively is bad enough. How much worse for £150 worth of gear to be not fully productive.Figs. 1 and 2 demonstrate angles of break, and the full realization of the importance of this angle is essential to our paper. Although these Sketches are two-dimensional, we hope they will be sufficient to demonstrate our meaning. We will pass over them as briefly as possible.Fig. 1 shows three holes asked to perform an identical task.(a) 7-ft. hole bored 2 ft. into solid ground-will not come out.(b) 4-ft. hole bored 1 ft. from solid ground-will come out easily.(c) 5-ft. hole bored to solid ground-the best that can be expected under general conditions encountered.The angle of break is a right-angle, normal to direction of hole.

Jan 1, 1944

By M Fritz, B Ziegelaar

"For moisture samples, the International Standard for iron ore sampling states the following: Moisture samples shall be processed as soon as possible and test portions weighed immediately. If this is not possible, samples shall be stored in non-absorbent airtight containers with a minimum of free air space to minimise any change in moisture content, but should be prepared without delay. ISO 3082 (2009)Prescribing what to do is of course easy. Putting it in practice is, however, a little more problematic.The iron ore industry has seen quite some changes in the last ten to 15 years, such as: a large increase in the volume of seaborne trade new ore types and blends coming onto the market new mines, processing plants and port facilities producing more and loading faster an increase in wet processed ore products a dramatic rise and then equally dramatic fall in the iron ore price followed by a recent recovery.All of the above have had an effect on sampling facilities. The large increase in volume coupled with ambitions such as labour efficiency, safer operations and higher precision has driven the installation and retrofitting of automated sampling and robotic sampling preparation plants in order to keep up with increased quality control.Designers of sampling facilities are invariably instructed to build plants that comply with ISO 3082. In general this means that the plants are compliant in respect of the number of primary increments, gross sample masses and sample division rules. The clause at the beginning of this abstract is mostly overlooked as it only appears in a section (4.1) describing the basic requirements of a sampling system.An error of 0.1 per cent in moisture changes the value of 1 Mt of iron ore at US$50/t by US$50 000. At 700 Mt/a of Australian iron ore exports, this is US$35 M. Frequently, errors from 0.5 to 1 per cent in moisture measurements are encountered.In comparison an error of 0.1 per cent Fe is US$0.081 (US$50/t and 62 per cent Fe base) per tonne, that is US$81 000 per Mt or about US$51 M for the same Australian annual iron ore exports.It is somewhat mystifying that we in the ISO Technical committees spend extraordinary energy (= money and time) on improving measurement techniques, whilst the big costs are in sampling errors. This is particularly true for moisture measurement. Our paper quantifies some of the sources of moisture measurements errors and suggests mitigating actions.CITATION:Ziegelaar, B and Fritz, M, 2017. Sampling for the percentage moisture in the iron ore industry, in Proceedings Eighth World Conference on Sampling and Blending, pp 271–274 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

May 9, 2017

Subsurface information from the "Upper Coal Measures" of the Sydney Basin is interpreted by means of structure contour maps, isopach maps and geological cross- sections. Particular reference is made to recent coal drilling operations by the New South Wales Department of Mines. The study is restricted to the onshore portion of the Sydney Basin.

Jan 1, 1972

Deposits of chromite are in associated with ophiolite complexes in Papua New Guinea. No deposits which are currently exploitable have been recognised, but large resources that may be economic in the future are present at Ramu area and on the Morobe coast. These are contained either in laterites or in sediments derived from ultramafic members of the ophiolites. There are possibilities of establishing further resources either in similar settings or associated with ultramafic members of alkali intrusive Complexes.

Jan 1, 1987

By A Innis, A Bye, B McCarthy, S Glover

Technology adoption in the mining industry has been steadily increasing over the past decade, driven by the need to improve operational efficiency, safety, sustainability, and profitability. As mining companies wish to implement solutions to improve mining safety and productivity, various technologies are being integrated into mining operations to enhance processes, reduce risks, and optimise resource utilisation. Adoption of new technologies such as autonomous trucks requires a strong focus on foundational operational technology (OT) and a systems-thinking approach. OT support is critical however, OT is traditionally not considered or integrated into standard maintenance activities. Consequently, sourcing and applying service support to OT systems in real-time has posed significant challenges to date. Neglecting the monitoring and upkeep of these operational technologies and equipment can lead to a host of adverse consequences. Operating instability becomes more prevalent, necessitating reactive measures, and the vulnerability to cybersecurity threats increases significantly. To address OT monitoring and maintenance challenges, a systems wide mindset and remote support discipline must be utilised. Remote operations support refers to real-time, 24/7 monitoring, control and support of site OT: network, production systems, maintenance systems, enterprise systems and mobile and fixed plant through a single interface remote from site. The presence of a disciplined team, grounded in a systems-oriented approach, is of the utmost importance to remote monitoring, given the intricate interdependencies of OT systems. The ability to understand the relationships among multiple systems, coupled with the capacity to distinguish between symptoms and root causes, assumes a pivotal role in operations. Through diligent monitoring and the astute understanding of system thresholds, remote operations support can actively identify and alleviate constraints, in turn, serving as the enabler for transformative advancements in technology output.

Sep 1, 2024

By D R. Seaman, R P. Tooher, B A. Seaman

"Several mine scheduling tools exist for use in optimising and scheduling the reserve according to in situ value. These tools generally value the ore on a per block basis according to regressed recovery models based on ore grade and type. It is then the task of the plant metallurgist to ensure that these ore blocks are fed to the plant in a manner that satisfies the prevailing plant constraints. This task is often completed in complex Excel® spreadsheets that are modified over time with factors applied to account for plant modifications or limitations.It is the authors’ experience that this approach is difficult to audit and replicate in a consistent manner. Furthermore, operational decisions, such as primary grind size or autoclave oxidation are made on the metallurgist or managements’ perceived optimum value and does not necessarily represent a cash flow based optimum.Many processing plants contain multiple internal constraints. As ore feed grades and properties change over the life-of-mine (LOM), processing-bottlenecks shift from one unit process to another and different operating strategies need to be adopted to maximise cash generation from the process.This paper presents a unified optimisation approach to scheduling ore based on a circuit mass balance to describe the process plant with individual models for each significant unit operation. The approach allows for optimisation over multiple input variables and the inclusion of linear and non-linear constraints.This optimisation process has been applied to different complex gold operations. The end result is an automated scheduler that selects the optimum blend of ores as well as plant operating conditions that satisfy all internal plant and shutdown constraints while maximising the objective of choice (metal production or cash flow). The models are also valuable for evaluating expansion or debottlenecking opportunities of individual processing units. These models are coded in Matlab® R2016a provided by MathWorks®, and can be deployed to end users in a compiled version with significant savings in time to run different scenarios over the Excel®-based systems.Citation:Seaman, D R, Tooher, R P and Seaman, B A, 2016. Optimisation of Complex Gold Processing Plants with Multiple Unit Operation Constraints - the Newcrest Planning Scheduler, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 191–198 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By S C. Dominy

Gravity amenable gold ores are those that after comminution produce liberated particles, composites and/or carriers that can be recovered by gravity separation means. Recovery depends upon mineralisation type and the comminution and concentration method used. Any in situ ore with more than 20 per cent of gold greater than 100 µm in size is likely to have a strong gravity recoverable component. A less traditional approach is where the gold is sulfide-locked and the gold carrier plus any liberated gold is recovered via continuous gravity recovery following fine crushing. Specific tests are undertaken to determine the level of gravity amenable gold within a deposit. The principal methodology is the gravity recoverable gold (GRG) test, which consists of three sequential liberation and recovery stages. For continuous gravity recovery (CGR), the sample is fed over a laboratory Wilfley table to simulate continuous recovery of the gold. Tails from the feed can be progressively re-ground and re-tabled to develop a grade-recovery curve. Primary geology and gold particle size-distribution have a strong effect on the mass of sample required to provide representative results for both tests. Where low-grade ore contains very coarse gold, substantially larger sample masses are required. Experience has shown that GRG and CGR values can vary throughout an orebody, particularly within different geological-grade domains. A testing regime must consider sample frequency and support.

Sep 5, 2011

By J E. Everett

Maximising ore tonnage at a selected target grade requires that appropriate ore identification criteria be established. Iron ore mining block models may consist of many millions of estimated blocks, each block corresponding to the selective mining unit (SMU), with grade interpolated from drill hole data. Each block can be considered as a potential ore candidate. Analysis of such a huge database can require large computational resources, especially for sensitivity analysis requiring multiple computations. However, an alternative streamlined approach is possible, where the data are compressed to an appropriately smaller and representative subset. The consequent data reduction not only makes it feasible to consider the simultaneous analysis of multiple pits but also considerably speeds up computation, enabling sensitivity analysis of the potential ore tonnage as a function of the required grade. Ore identification criteria can be successfully established using appropriately chosen reduced data comprising less than one per cent of the blocks. The ore identified is virtually indistinguishable in tonnage and grade from the ore that would be selected using the entire block model.Two methods of data reduction are tested: sampling (using a proportion of unaltered blocks) and binning (consolidating groups of blocks to a single average grade). The source blocks are first sorted (such as by location, analyte grade, principal component score, random order or value) before sampling or binning. In this study, the sorting options considered were by location and Fe grade. The effectiveness of each method was evaluated using the block model subsets to select the maximum tonnage of ore at a specified target grade. Block model data from an anonymous Pilbara iron ore project with about one million blocks averaging 1.132 kt were used. The blocks are from multiple resource models, to be blended to a single product. Sampling is shown to be superior to binning because sampling preserves the full variability while binning, although matching the mean block grades reduces their variability.It was found that the appropriately sampled data sets (sorted by location) gave results virtually identical to the results for the full data set, even when the samples comprised less than one per cent of the original blocks. The reduction in computer time to identify maximum tonnage at a specified grade was approximately proportional to the sample percentage. The increase in computation speed greatly facilitated sensitivity analysis. A sampled data set of one-eighth the total block model was used to investigate the effects of changing each of the component grades around the original grade specification. The results of this sensitivity analysis are discussed, and illustrate the potential benefit of carrying out sensitivity analysis in determining feasible and marketable product grades.CITATION:Everett, J E, 2015. Block model data reduction and sensitivity analysis, in Proceedings Iron Ore 2015, pp 263–270 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By R Grobler, D Burger, L Alberts

The current climate in the mining industry is allowing mining companies to further broaden their views and investigate technologies to improve the safety, efficiency and cost-effectiveness of their operations. Furthermore, underground mine environments will become more demanding for mining equipment and personnel as orebodies become deeper in weaker ground conditions with more extreme environmental conditions. Loading and hauling can represent significant components of the production cycle of an underground mine and automation of these activities can offer considerable benefits. Sandvik has accumulated a long history and experience in loading and hauling automation in underground mining. Since the late 1980s Sandvik has actively participated in several major research and development automation programs leading to the commencement of the development of an integrated system for semiautomated loading in 1999. Development work was later conducted to expand the capabilities of the system for automated hauling during 2001 and the AutoMine« system became commercially available. The first delivery of the AutoMine« system was completed in August 2004 in South America, where the system continues to operate in a full-scale production environment and is being expanded as the production area enlarges. Further systems have been delivered and are operational in North America, Africa and Europe. This paper focuses on the AutoMine« system deployed in Block 4 at De Beers Finsch Mine in South Africa. An overview of the mine and the process used to acquire the system and the key drivers which led to the selection of an automated solution are described. An overview of the initial system installation, subsequent expansions and future plans are presented. This is followed by a summary of the implementation and operational experiences associated with automated underground operations. The paper concludes by summarising the benefits that have been realised.

Jan 1, 2008

By D Caffrey

To demonstrate the advantages of using electronic delay detonators over pyrotechnic detonators, a trial using the DNES Dynatronic System was conducted at the KCGM Mount Charlotte operation in 1998. The trial clearly demonstrated that accurate control over the firing delay time between blastholes can lead to fragmentation improvement and ground vibration energy control which are two important issues for the Mt Charlotte underground operation. Excellent fragmentation was achieved by employing a 12 ms delay sequence. Detailed fragmentation analysis has shown a 10 to 20 per cent passing increase for the rock fragment size from 0.1 to 0.4 m compared with the pyrotechnic detonator firing. There was no increase in ground vibration level on the surface with the electronic detonator firing even though the electronic detonator firing had a much shorter blast duration than the pyrotechnic detonator firing. In fact, our energy calculation has clearly shown that much less energy had been propagated to the surface from the blast using electronic detonator firing.

Jan 1, 1999

By O Arafat, K M. Bartholomew

A voracious consumer of energy and grinding media, the modern ball milling circuit has a huge direct cost impact on a mineral processing operation. Through optimisation, grinding also has the potential to unlock great improvements in recovery and throughput, but how can the complex interactions between mills, classifiers, tonnage, ore-type and downstream recovery be measured, understood and managed in a systematic manner?Functional performance analysis provides the tools and insights needed to measure, understand and improve the two key process efficiencies in ball milling circuits: classification system efficiency (CSE) and mill grinding efficiency.CSE measures the composite performance of the classification system as a whole. In short, the purpose of the classification system is to ensure that grinding mill energy is used to grind coarse particles while minimising overgrinding. CSE is simple to measure in the plant and it provides immediate feedback to the plant metallurgist, mill superintendent and management about the performance of the classification system and the amount of wasted energy in the grinding plant.Mill grinding efficiency measures the capacity of the grinding mill to convert feed-sized material into product-sized material on a tonnes per kilowatt hour basis. It is normalised based upon the ore resistance to breakage, so it provides feedback about the ‘health’ of the milling process under varying operating conditions and ore types. Mill grinding efficiency is measured at the same time as CSE through circuit sampling.Functional performance analysis combines CSE and mill grinding efficiency to provide a measureable, manageable optimisation objective. It also provides a link to tonnage, ore type and recovery. As a result, systematic optimisation of a grinding circuit is a measureable and manageable process to meet business objectives.CITATION:Bartholomew, K M, McIvor, R E and Arafat, O, 2014. Functional performance of ball milling circuits – a plant metallurgist’s tool for process characterisation and optimisation, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 227–232 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014