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By J. B. Boisvert, O. Leuangthong, T. Acorn

Optimizing final pit limits for stochastic models provides access to geologic and economic uncertainty in the pit-optimization stages of a mining project. This paper presents an approach for optimizing final pit limits concurrently over all realizations in a stochastic model and using a risk-management framework to manage the geologic and economic uncertainty. A heuristic pit optimizer is used to find multiple uncertainty-rated pit shells. These uncertainty-rated pit shells follow the mean-variance criterion to approximate the efficient frontier for final pit limits. Stochastic dominance rules are then used in a risk-management framework to further eliminate suboptimal solutions along the efficient frontier. This results in a smaller set of final pit shells that can be further analyzed for production scheduling. Additionally, the original solutions are analyzed for changes in the mining limits, and two regions are targeted as potential regions for further exploration.

By Laurel E. Blackman

The DFI Project Information Management Systems (PIMS) Committee cooperated with the US Army Corps of Engineers (USACE) to develop a specification for PIMS used on USACE projects. Once completed the Committee developed a more generic version of this specification for general use, which is contained in this document. This first edition has simply removed the USACE-related requirements from the document. The committee will continue to work on this specification to enhance the content and also incorporate recent technological development for these systems. It is the Committee's intention that a second edition will be issued in 2022.

Jan 1, 2021

By E Widzyk-Capehart

The mines of the future can be envisioned as complex, large-scale technological systems being operated remotely from few centrally located (major cities) operating centres and skeletal crew stationed at the site. These systems will require remotely located human operators to constantly adapt to new and unforeseen system and environmental demands. In addition, the remote operators will need to match system properties to the changing demands and operational conditions, ie must be able to handle the ‘non-design’ emergencies, because the system designers would not have been able to foresee all possible scenarios of failures and provide automatic safety devices for every contingency. Therefore, it is highly important that the operators’ job, which involves problem solving and decision making at the workstation level, is facilitated by the proper interface designs. This paper argues that decision support systems and thus human-system interfaces for the mines of the future should be developed based on the principles of human-system integration that take into account human information processing and cognitive abilities. The information presented to the operator must support the operator in taking appropriate action through a human-system interface designed according to scientific principles of User Centred Design. A case study is presented where an iterative design process was used by CSIRO researchers as an evaluation method involving users (control room operators) at several stages of the user interface design in order to correct any design inadequacies as they emerged. This process allowed the designers to identify any usability issues before the user interface was fully implemented, which subsequently enabled the control room operators to easily adapt to the new interface and carry out all designated tasks in a timely and effective manner.

Nov 22, 2011

By S Leichliter

La Colosa, Colombia is a large gold-porphyry deposit currently undergoing feasibility studies by AngloGold Ashanti. This period of development allows the opportunity to apply innovative and emerging testing and modelling methods to provide a predictive geometallurgical recovery model for the deposit. By partnering with the AMIRA P843A Geometallurgical Mapping and Mine Modelling (GeMIII) research project, the geological and mineralogical data are analysed with respect to liberation and recovery methods. This will allow the variability in the geology and mineralogy of the deposit and key relationships recognised in the data to be included in the development of a model to help predict recoveries of the gold. Many aspects of the gold mineralisation such as gold paragenesis, associations, grain size and texture are determined and analysed using optical microscopy, Mineral Liberation Analysis (MLA), and laser ablation (LA-ICP-MS). At La Colosa the gold has been located in sulfides (eg pyrite, pyrrhotite, and chalcopyrite), silicates, along silicate phase boundaries, and among the pyrite-rich intermediate argillic alteration. Further testing and analysis will also determine if ‘invisible’ gold is present in the pyrite, pyrrhotite, and chalcopyrite. Recovery methods can also be determined and tested after combining the results of mineralogy tests with other data (eg results of comminution tests). Indices for the mineralisation and recovery are developed using image analysis and analytical testing. These indices are correlated with recovery data from the company to develop a predictive block model for recovery. The goal is to develop cost-effective, efficient methods to analyse the mineralogy and geology of the deposit; understand the variability in the mineralogy, geology, and recovery; and construct a predictive geometallurgical recovery model.

Sep 5, 2011

By S Bhandari

A model for predicting dust plume dispersion from blasting operations using the Eulerian mathematical algorithm has been developed. This model considers atmospheric stability, and wind velocity and direction for computing dust concentrations at different distances from the blast. Software has been developed which simulates the movement of a dust plume at a given horizontal distance from the blast location and time elapsed after the blast. The concentration of dust is also given in vertical planes. It takes into account ground profile and atmospheric conditions such as temperature, pressure, humidity, wind velocity, wind direction and shear. Experiments were carried out in two limestone mines to calibrate the accuracy of the predictions made by such model. High volume dust samplers were used to collect dust samples. Difficulties encountered in satisfactory dust sampling and quantification of results have been described.

Nov 8, 2011

By J Lombardi

OZ Minerals' Prominent Hill copper-gold concentrator is located 130 kilometres south east of the town of Coober Pedy in the Gawler Craton of South Australia. The concentrator was built in 2008 and commenced commercial production in early 2009. The Prominent Hill concentrator is comprised of a conventional grinding and flotation processing plant with a 9.6Mtpa ore throughput capacity. The flotation circuit includes six rougher cells, an IsaMill for regrinding the rougher concentrate and a Jameson cell heading up the three stage conventional cell cleaner circuit. In total there are four level controllers in the rougher train and ten level controllers in the cleaning circuit for eighteen cells.Generic proportional – integral and derivative (PID) control used on the level controllers alone propagated any disturbances downstream in the circuit that were generated from the grinding circuit, hoppers, between cells and interconnected banks of cells, having a negative impact on plant performance. To better control such disturbances, FloatStar level stabiliser was selected for installation on the flotation circuit to account for the interaction between the cells. Multivariable control was also installed on the five concentrate hoppers to maintain consistent feed to the cells and to the IsaMill. An additional area identified for optimisation in the flotation circuit was the mass pull rate from the rougher cells. FloatStar flow optimiser was selected to be installed subsequent to the FloatStar level stabiliser. This allowed for a unified, consistent and optimal approach to running the rougher circuit. This paper describes the improvement in the stabilisation of the circuit achieved by the FloatStar level stabiliser by using the interaction matrix between cell level controllers and the results and benefits of implementing the FloatStar flow optimiser on the rougher train.

Aug 8, 2011

By J Elder

Magnetic separation equipment has long been used to upgrade and beneficiate a wide variety of minerals and materials. Over the years, significant advances in both wet and dry magnetic separators have improved their operability and separation performances, broadening their use.But no one answer exists to the question: what is the right type of magnetic separator? For many minerals, including ilmenite, both process routes may be viable. There are technical, production, as well as economic reasons for choosing wet versus dry. However, recent developments illustrate that a new generation of wet magnetic separators is approaching performance once seen only in dry magnetic separation. With quality and production performance becoming similar, the choice between wet and dry magnetic separation is not as cut and dry as it once was.

Oct 5, 2011

By S Bailey

In-field sampling programs generally take time, equating to money, and unless you have an onsite laboratory, you have the issue of having to wait long periods for your data. Until recently, field portable X-ray fl uorescence (FPXRF) analysers, which can help provide instant indicative results, were not able to detect penalty elements, such as Al and Si, or do so reliably enough to act upon.The purpose then of this field test then was to show that the latest FPXRF devices are capable of producing reliable readings on field samples of variable grain size, in particular for Al and Si, such that the readings still correlate well with the assay for those samples and thus be reliable for an iron ore grade control application.We tested RC chip samples on-site in the Pilbara, Western Australia, with the Niton, analysing for a range of elements including Fe, Mn, Al and Si and then compared the results for those elements against assay data for the same. A strong correlation would tell us that the FPXRF results were reliable. Furthermore, to show the effect of simple sample preparation, we also analysed pulps of the same samples in the same way.The correlations were good for the all of the four elements of interest for the RC chip samples (R2 values between 0.82 and 0.9), and excellent for the pulps (R2 values between 0.89 and 0.998).The results also showed a direct correlation between sample preparation and improved quality of results with the FPXRF.The data showed allowed for two conclusions:1. the FPXRF can produce data from unprepared RC chips for Al and Si that, when compared with assay, is reliable for a fi eld application in drilling and grade control; and2. the greatest limitation to data quality is sample preparation.

Jul 11, 2011

By C. J. Edmonds

Of the gold mined in Canada over 90 percent is extracted from the ore by the process of "cyanidation". In this process crushed ore is treated with lime to provide "protective alkalinity" and cyanide, usually in the form of sodium cyanide. The gold is dissolved in the cyanide solution, which after further treatments for clarification, is precipitated by the addition of zinc dust. Wastes from the process consist of tailings which will contain cyanides. Water consumption, mill size, effluent quantity and quality are depicted in transparency (1). It should be noted that as far as the wastes are concerned it has been impossible to postulate a typical situation. Variation from the above data will occur. A summary of data from tailings pond effluents is presented in transparency (2). The figures in parentheses indicate the usual range of values for the parameter.

Jan 1, 1973

By G Lane

This paper discusses the factors that contribute to the cost effective design of a concentrator. Concentrator design and layout outcomes are functions of the team (engineer’s and owner’s) participating in each particular project. The benchmark for relatively modest projects was set in the 1980s and 1990s during the ‘gold boom’ when numerous cost effective plants were designed and constructed on a lump sum basis in a very competitive market. A number of factors contribute to lack of transference of the lessons learnt in gold plant design to concentrator design including established paradigms in the design and layout of concentrators, lack of experience in cost effective design, operator’s preferences for flowsheet and layout and simple lack of appreciation of the impact of plant footprint on materials quantities and resultant capital costs.Experiences with recent copper concentrator projects (both small and large) are used as case studies.

Aug 8, 2011

By A Dix

Fire suppression systems are but one of the many technologies currently available to manage operational tunnel risks. However, the actual reasons for their use are often shrouded in mischievous discussions of the marketing variety.The international tunnelling community still stands divided on the merits (or otherwise) of fire suppression systems. For some the debate focuses on their cost compared to the theoretical benefits they bring to human safety.Long standing concerns about their potential adverse effects in an emergency are often at odds with the experience from tunnels which use them. High installation and operational costs are cited as reasons not to use them, yet toll road operators and insurers increasingly use them as a risk mitigation strategy for toll revenue protection.Fact or fiction, myth or reality, should such systems be seriously entertained or are they just another expensive gadget in the escalating array of expensive toys for modern tunnels? Ultimately this presentation argues that they have their place as a risk mitigation measure to achieve a range of objectives. The exact circumstances for their use ultimately fashioning their design and operational characteristics. This is an abstract only. No paper was prepared for this abstract.

Mar 8, 2011

By P V. A van der Westhuyzen

Namakwa Sands is a heavy minerals mining and beneficiation business in the Exxaro Sands Division, and operates along the West Coast of South Africa (see Figure 1). The business encompasses mining, mineral concentration, separation, and smelting operations. Inflated commodity prices and increasing operating costs demands greater attention to the management of process performance and the company wide coordination of resources. Consequently, the task of deploying operational/technical skills and budgets into the most appropriate parts of the business assumes great importance in order to increase productivity from its capital assets. The mineral sands industry is under the same sort of economic scrutiny that all other industries find themselves, and as such, Exxaro – Namakwa Sands has taken the strategic initiative to improve overall resource utilisation within the processing steps and to measure the costs associated with obtaining this value.This paper provides details of the successful implementation of a Kelsey Centrifugal Jig (KCJ) at Namakwa Sands to recover primary and secondary zircon products from the wet gravity (quartz) rejects generated and stockpiled at the Mineral Separation plant (MSP).

Oct 5, 2011

By P Card

“Let’s get discipline and quality into easy to understand evaluations!” Project Managers and MetPlant Operators accept poor quality evaluations because they are generally unaware of what they should expect.The 2010 draft AusIMM ‘Guidelines for Techno-Economic Evaluations’ were collated by a subcommittee of practitioners and are regarded as best practice.They apply directly to projects and metallurgical plant evaluations, including those with a heavy technical basis. They can be applied to technical problem solving where there are no monetary computations. Project Managers and MetPlant Operators should demand that economic models and evaluations follow the six principles. They should become working tools which are easy to understand, fit for purpose, consistent, rigorous, record sources of input data, have key graphs and are rapid to audit.

Aug 8, 2011

By M Darvall

Magnetite ore blending has yielded signifi cant performance improvements in OneSteel’s magnetite concentrator. The magnetite concentrator beneficiates magnetite ore from the Iron Magnet Deposit and produces concentrate, which is pelletised, then fed to the OneSteel Whyalla blast furnace. Concentrator feed variability severely detracts from the concentrator’s performance, affecting both concentrate yield and grade, which impacts on all downstream processing costs.A coordinated approach has integrated mine planning, geological modelling and grade control, to minimise concentrator feed variability, through effective ore blending throughout the mining and stockpiling process.Mine planning personnel design shots that extend the full width of the orebody and hence across the stratigraphic profi le. Based on geological information contained in block-outs and in consultation with Geology, the Grade Control team allocates material to each primary stockpile, potentially from every stratigraphic domane in the orebody. This ensures primary stockpiles are designed with maximum practical homogeneity and consistency.Using only primary movement, the allocated ore is stockpiled in a layer-cake fashion. The ore is pimple dumped across the width of the stockpile footprint and on completion of a layer, it is dozed flat with an access ramp that allows dumping to commence on the next lift. The primary stockpiles are reclaimed normal to build direction and the magnetite is crushed, all in, to a concentrator feed stockpile.The ore is sampled at the crusher from a falling stream cut. These assay data, are used for benchmarking and control charting the grade and variability of concentrator feed stockpiles. The concentrator feed stockpiles have demonstrated a statistically signifi cant reduction of within pile variation, between pile variation and pile to pile variation, primarily attributable to the development of ore blending. The concentrator has seen sustained, improved performance as a direct result, which translates into lower concentrate cost per tonne and improved yield and quality.

Jul 11, 2011

By G Barla

In Europe, a major interest in the infrastructure and tunnelling fields is in the new crossings of Alps in the form of base tunnels, which are important components of the high-speed (for passengers)/high-capacity (for freight) Trans European railway corridors. These tunnels cross the mountain belt at the elevation of the main cities and basins located all around the Alps and are longer (up to 57 km) and deeper (up to 2500 m) than all tunnels constructed in the centuries before. The excavation of the first Alpine railway and road traffi c tunnels could in general be carried out successfully by conventional excavation methods. With the great lengths of the new base tunnels, mechanised excavation by using tunnel boring machines (TBMs) is imperative as it contributes significantly to savings in construction time and costs. Questions are however posed on the adoption of such a systematic tunnel construction method given the severe ground conditions which are some time anticipated along the tunnel alignment, with possible major geological hazards such as water inflow in heterogeneous fractured or karstifi ed rock masses, stress-induced tensile failure of hard rocks, and plastic shear failure and squeezing of weak rocks, etc. This lecture is to briefly review the current state-of-the-art in the understanding and modelling of two such critical hazards as spalling/bursting and squeezing ground behaviour. With the present interest in the design of mechanised tunnelling with TBMs in such conditions, the complex interaction between the rock mass, the tunnel machine and its system components, and the tunnel support is studied in detail by numerical modelling. The research and development efforts presently underway with the intention to provide the designer with a novel three-dimensional (3D) simulator of mechanised tunnel excavation are presented. Case examples are discussed with reference to the Lyon-Turin Base Tunnel design.

Mar 8, 2011

By C Fischer

The introduction of digital communications technologies into the underground mining industry, in both coal and hard rock mining, has enabled high bandwidth applications to be applied in the mining industry. Digital networks based on 802.11 b/g/n open Wi-Fi standards have allowed numerous applications to be run over a single communication backbone. One of the many important applications is the tracking of personnel and equipment via RFID Tags. This tracking application has formed the basis of a Proximity Detection System or Collision Avoidance System (Schiffbauer and Mowrey, 2001; Kent, Fischer and Schiffbauer, 2011) thereby improving safety and increasing control in the mining environment. This paper discusses the growth of digital technology as the backbone for communications in underground mining applications. This growth has allowed the ‘convergence of technologies’ (occurring in the general business world) to be available to mine operators in general and underground mine operators in particular. Mine Site Technologies’ involvement with major mining companies and mining equipment manufacturers (OEMs) in developing and supplying their communication systems is also discussed.The latest technical requirements and specifications for communication systems for underground and open cut mines will be reviewed.

Nov 22, 2011

By B. C. Jago, H. Derbuch

"The Freightrain kimberlite is located on the Brodeur Peninsula, Baffin Island, Nunavut. Twin Mining is exploring the pipe and adjacent land (79 claims/655 km2) using a combination of airborne geophysics, soil sampling, diamond drilling, trenching and bulk sample processing. The pipe originally was discovered by Cominco Limited in 1975, re-evaluated in 1993 by Lumina Investment Corporation, when it was staked as the Zulu pipe, and subsequently covered by three claims in 1998 by Helix Resources who called it Freightrain.The Freightrain pipe coincides with a strong, ovoid-shaped aeromagnetic anomaly. It is the only surface exposure of kimberlite within a 30 km long linear trend of fourteen aeromagnetic anomalies that are up to 600 m in diameter.The pipe is exposed in the crater facies, near the transition into diatreme facies as indicated by the occurrence of pyroclastic kimberlite characterized by abundant olivine macrocrysts, juvenile lapilli and kimberlite autoliths set in a serpentine-calcite matrix. Olivine, Cr-pyrope garnet and chromite are the most abundant macrocrysts; clinopyroxene, ilmenite and phlogopite mica occur in minor to trace amounts. Garnet and chromite harzburgite, garnet lherzolite, garnet-spinel lherzolite and rare eclogite dominate the xenolith population.Garnet and chromite mineral chemistry indicate encouraging diamond prospectivity and that potentially diamondiferous garnet and chromite harzburgite were the principal sources of diamond in the mantle at the time of kimberlite eruption.Single clinopyroxene grains define an ~42 mW/m2 sub-continental geotherm that is rooted in the diamond stability field. This compares to a slightly hotter geotherm (~48 mW/m2) for adjacent Somerset Island kimberlites with an origin in the graphite stability field. This data accords with the general lack of sub-calcic Cr-pyrope garnet, diamond inclusion chromite and diamond in Somerset Island kimberlites."

Jan 1, 2002

By T N. Little

This review paper presents an integrated and practical insight to blasting geology and its importance. This approach involves developing blasting objective up front and implementing geology specific blast designs. The author refers to this approach as ‘starting at both ends’. There are many human-imposed controls on blasting operations, such as: safety, security, legislative, company standards, heritage, and environmental constraints. Thus it is possible for some operators to lose sight of the controls imposed by nature. This paper demonstrates how site geology controls or influences many aspects of the rock breaking processes and how a focus on this aspect has potential to add considerable value to mining operations. It is obvious that mining companies concentrate their efforts on economic/ore geology (good rock geology). However it is the author’s experience that they also concentrate on engineering geology (bad rock geology) only when forced to do so by the ground conditions, but seem to run out of puff before they apply blasting geology (big rock geology). This paper contains five main sections. In the first section, the impact of geological controls on blasthole drilling is briefly discussed in terms of drill selection, penetration rates, bit wear, blasthole stability, blasthole deviation, and health precautions. In the second section the geological controls on aspects of geometric design are reviewed. These include: hazardous minerals, valuable minerals, selection of the blasting techniques, geological structures, blasting direction, and blasting geometry. Section three overlaps with the geometric design section and deals with aspects related to explosives. Topics addressed include selecting the explosive type based on geology, distribution of explosive charge in space and time, explosive performance, and the rock response to explosive loading. In the fourth section, examples are given of the operational complexity needed to implement a blast to cater for difficult bench geologies, environment constraints, past mining (voids) and need for a high degree of quality control. Section five demonstrates geological controls on blast results. Blasting results include the muck pile characteristics, downstream handling and processing, damage to the remaining rock, and blasting emissions.

Nov 8, 2011

By D L. Kennedy

Many aspects of the physical layout of manufacturing plants and storage facilities for explosives are governed by so-called quantity-distances tables. Both the British and the American tables were originally derived from an analysis of the injuries and the building damage documented by an early 20th century compilation of significant accidental explosions. However, progressive changes in explosive process technology and in building techniques have reduced the relevance of much of this historic data set. Extensive scientific research has been conducted over recent decades to characterise the potential injuries and damage from accidental explosions under more modern conditions. This presentation will showcase some of this research.**This is an abstract only. No paper was provided for this abstract**

Nov 8, 2011

By R J. Thompson

In truck-based hauling systems, the mine haul road network is a critical and vital component of the production process. As such, underperformance of a haul road will impact immediately on mine productivity and costs. Operations safety, productivity and equipment longevity are all dependent on well-designed, constructed and maintained haul roads. With the advent of autonomous haul trucks, the haul road itself becomes all the more critical to the success of these type of operations; not only in relation to mine operators requirements for safer and more efficient and predictable haulage systems, but also in response to autonomous truck manufacturers’ requirements for a more predictable and controlled operating environment. This paper presents a brief summary of the state-of-the-art in surface mine road design and then proceeds to examine the design and technological challenges associated providing a safe, predictable and affordable road for autonomous mine haul trucks. The paper serves as a basis for evaluating the contributions that enhancements in road design and management can deliver to autonomous mining operations, an initiative that also has scope for adoption within the operating life of many mines, haul roads and haul trucks.

Nov 22, 2011