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By Gabriel G. Walton

Conventional numerical modelling tools for analyses of underground excavations are well suited for modelling elastic behaviour and yield response of geomaterials with very simple constitutive behaviour. Non-dilatant elastic and perfectly plastic behaviour is most commonly used for preliminary analyses in the absence of the data required to consider more complex behaviours such as strainweakening and dilation. For truly brittle models, this deficiency is more acute. Current state of practice allows only for reliable estimation of the volume of failure, but not for any prediction of displacement. In fact, there is no consensus in rock engineering regarding the most accurate approach or most suitable tool to model the magnitude of the plastic deformation that strain-weakening or brittle rocks experience at tunnel boundaries, particularly when support is incorporated into these models. This problem is largely a function of a poor understanding of how inelastic dilation occurs in different types of rockmasses, the rate controls on strength loss and volume change during yield, and the complexities of rock-support interaction in yielding conditions.

Jun 1, 2012

By David Newton, Christian O’Keefe, Robert Maron, Jerin Russell, Paul Rothman, Dylan Cirulis

"The presence of unwanted coarse material in flotation feed streams negatively impacts both recovery and throughput of concentrator plants. The detection of this coarse material is a long-standing problem in mineral processing that has been poorly addressed by existing instrumentation systems. This problem has been overcome by the development of two new systems that detect in real-time the presence of coarse material in the overflow stream of individual hydrocyclones. They both use sensors mounted to the overflow pipe of the hydrocyclone and provide a robust and maintenance-free system measurement that enables corrective actions through operator intervention or automatic control strategies. One system is non-invasive and detects very coarse material 6mm or greater in size. The other system uses a wetted sensor and detects coarse material down to a lower size limit of approximately 100 um. Both systems have been commercially deployed. The systems will be described in detail. Validation data and typical plant data will be shown"

Jan 1, 2014

By W. D. Robson

THE prevention of silicosis by metallic aluminium has been reported by Denny, Robson, and Irwin in two papers. The first (1) was published in 1937; the second (2), in 1939. The results definitely established that silicosis was prevented in animals by the inhalation of small quantities of aluminium. The present communication records subsequent progress in this field of research. HARMLESSNESS OF ALUMINIUM Animal experiments having served their purpose, it became necessary to consider means to test the discovery on humans. A question for immediate consideration was: Is aluminium harmful to man when inhaled as a fine powder? While the animal experiments were reassuring, since they conclusively showed the powder to be innocuous when breathed by animals, it was, nevertheless, desirable to have additional reassurance with regard to its effect upon human beings. Through the courtesy of the Aluminum Company of America and especially the valued interest in this problem displayed by that Company's Director of Research, Dr. Francis C. Frary, a study was made of the records pertaining to the health of a group of 125 employees who had for many years been engaged in the manufacture of finely powdered, metallic aluminium for the paint and ink industries. The conditions were such that these employees had inhaled varying and oft-times very dense concentrations of this powder daily over periods ranging from 6 to 23 years, the average for the group being 12 years. X-ray pictures of their chests showed no abnormalities attributable to aluminium. Their general health seemed better than that of the 3,000 workers in other sections of the plant. In fact, the early films of three employees in this group of 125 showed shadows suggestive of minimal tuberculosis, which shadows were not discernible in films taken after considerable periods of exposure to aluminium powder. The harmlessness of aluminium was, by this study, reasonably well established at the outset, a finding subsequently verified by Ontario research on humans.

Jan 1, 1944

By D. E. L. Zapata, O. J. R. Baena

"INTRODUCTION Mining is a fundamental part of the historical and economic development of a country. In Colombia, this is reflected from pre-Columbian jewelery, to being now one of the first exporters of coal worldwide, in 2017, the Colombian mining sector contributed approximately 6% of GDP (Ministerio de Minas y Energía, 2017). Coal, nickel, gold, platinum, emeralds, limestone, salt, phosphate rock, clays, siliceous sands and to a lesser extent copper, manganese, magnesite, barite, gypsum and various types of ornamental rocks, among others are produced (UPME, 2016). The contributions of mining activity in the economic dimension is more measurable, on the contrary in other dimensions, as the social and environmental, for this, every day there are new proposals and tools oriented to strengthen how to evaluate the contributions in terms of the sustainability and responsibility, with the aim of quantifying, concreting and non-utopian, to improve the life quality of a community and not only to comply with reporting and gaining prestige. Colombia has a generalized increase in the mining sector where the levels of informality and illegality are evident only 10% of mining activity is legal (UPME, 2014), also, the mining sector is accused of human rights violations, high levels of inequality, poverty and the affectation of ecosystems due to bad environmental management, among other situations (ACNUDH Colombia, 2015). This problem has generated rejection to the realization of the mining activity in many places of Colombia. At this point, it is important to clarify this problem is more complex, different actors are involved in this conflict, but it is an evidence that is needed a sustainability model for specific realities such as the Colombian mining. This situation in the current mining activity, is similar to the chemical industry situation three decades ago, because of an extensive problem in relation to repeated work accidents, natural disasters and indications as a highly polluting and unsustainable industry, with the aim of improving, not only this public perception, but also in the way of carrying out the business activity. Thus, in 1985, the Canadian Chemical Producers Association released the Responsible Care Program (RCP) (ICCA, 2015). Being aware that companies were responsible for the affected lives in some way by the operation and needed to improve workers safety, environmental protection and most importantly how legal persons should comply with the law, but go beyond this. RCP is most recognized sustainability initiative in the chemical sector, companies associated are recognized for having high quality standards, continuous improvement, visibility, corporate ethics, environmental and social management (ACC, 2015). In addition, to meeting the objectives is set out the creation of a model that increasing reputational sector levels. This initiative is considered to be a worldwide successful case of reporting corporate responsibility indicators and contributions to sustainability from the industry sector to local development (BASF Group, 2016)."

Jan 1, 2018

The Callie Underground Gold Mine (Callie) is owned by Newmont Asia Pacific and located 531 km north-west of Alice Springs in the Northern Territory. Historically, stopes have been mined utilising a primary and secondary stoping sequence with cemented aggregate fill and rock fill respectively. Current and near-future mining will employ long hole open stoping with rib pillars and rock fill with a paste fill system approved to allow a higher extraction ratio from mid-2011. The Callie rock mass is of good quality with little or no mining difficulties during development and stoping to a depth of 1140 m below surface. Development is currently occurring at depth of 1360 m below surface. Stress damage previously observed only in secondary stope accesses is now observed in development unaffected by stoping stresses. A change in rock mass properties is being experienced with depth, with more pronounced and frequent joint planes. Also, other structures are intersected more commonly, such as lithological boundaries and fault zones. The 'Callie rock factory' mentality that has persisted for years is challenged. This paper covers an appraisal of the stress and ground condition changes at Callie. The appraisal outlines the mine design criterion that was developed and examines the transition from a low stress environment to one where stress damage is observed. Discussion includes a judgement on the rock mass damage observed in development, the dominant geotechnical factors influencing the change in ground conditions, and if a correlation can be made between the observed rock mass damage with stress through the use of numerical modelling.

Nov 25, 2010

By B. Mishra

This paper presents a rock mechanics investigation of the time-dependent behavior of the rock immediately surrounding the excavation in a hypothetical one-entry coal mine based on the geology of the Illinois coalfields Research in the area of time-dependency is almost nonexistent and, therefore, this research was performed to make inroads into this neglected research area. Numerical analysis of a typical one-entry coal mine in an Illinois basin was performed using the commercial finite difference program FLAC3D. The immediate roof of the coal entry was assumed to be a shale formation. Shale in other formations has shown a tendency to creep with time. Therefore, in this study the authors modeled the shale in the roof using time-dependent characteristics. The input properties were taken from laboratory creep tests performed on shale. Model runs were performed at different stages, mimicking the progressive excavation of the entry. The model results showed that stresses in the roof attained the limit of yielding. Using Mohr-Coulomb failure criteria, potential zones of failure were also predicted. The results showed that the current computational capacities are sufficient to explore this previously uncharted territory of ground control.

Mar 1, 2014

By A Romanel, M S. Kato, M P. Piermatei, P Artioli

"Brazil is the sixth worldwide producer of aluminum and Votorantim (Metals) has been operating three bauxite open pit mines in a particular way of working. In those the deposits occur on the top of hills, under forest, coffee, eucalyptus plantation or pasture area.The deposits are not large and normally mining takes an average of two months to be completed before starting the rehabilitation process, which demands a good strategy in mining planning to achieve the production goals.The benefit function developed to select feasible areas uses, beyond production costs, fees from the owner by using their area and rehabilitation cost. Both are based on land use and occupation field survey data. In this process each area with different land use receives a specific rehabilitation cost as input into a block model.Once the selection is made the mining schedule begins, taking into consideration the following premise: the orebody needs to be mined in a short period of time because during this time, the surface owners receive from Votorantim a compensation based on the expected profits from their plantation or pasture, plus royalties related to the ore amount existing in their area.Not all operations have waste dumps. Waste is pushed down by bulldozers to the lower part of the ore border. After loading and transporting ore, the waste is handled back to the mined area to fit the topography. With this step concluded, the mined area is directed to the environmental team who, alongside university partners, develop land reclamation to return them to their owners, eg in 2011, 110 ha were rehabilitated of which 29 per cent is native forest.Votorantim closes many mined areas a year and currently the entire mine planning considers this particular way of operation, making profit with minimum interference with the community and the environment.CITATION:Artioli, P, Kato, M S, Romanel, A and Piermatei, M P, 2012. Environmental variables at bauxite mine, in Proceedings Life-of-Mine 2012 , pp 171-178 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 10, 2012

By Matthew Goff, Russell Lutch

The Great Lakes Water Authority (GLWA) operates the largest regional water authority in the State of Michigan. Two of the tunnels supplying raw water to the system from the Detroit River are the Springwells and Northeast Tunnels. The existing 70- to 90-year old concrete lined tunnels have experienced distress and cracking over their life requiring non-structural repairs to sections of the tunnels. For the repair, an interior stainless-steel segmental liner plate system has been designed to restore the watertight capacity of the tunnel liner and resist the exterior hydrostatic groundwater pressure in a dewatered condition. The team is utilizing a “wet repair” approach to perform the necessary repairs while the tunnel remains fully flooded and operational. To test and validate the tunnel repair approach, a full-scale mock-up of the proposed repair has been performed using underwater equipment and divers.

Dec 1, 2022

By Brad Grothen

What is the most economical way of tunneling in mixed ground that may experience high pressures? Non-continuously pressurized, mixed ground Tunnel Boring Machines (TBMs) are being utilized to deal with a wide range of geology. Continuous improvements in these mixed ground machines allow for ever-increasing efficiency and reduction of project risk due to unexpected conditions. We will explore the performance of recent mixed ground machines throughout the world and then look at how new improvements to mixed ground machines will enable excavation of an expanded range of ground conditions. These conditions include mixed ground with low fines, mixed face rock, and fracture/fault zones with high pressures where in the past a Slurry TBM may have been utilized.

Dec 1, 2022

By Dave Paul

Dam rehabilitation involves a range of design, construction, and operation risks, some of which are not encountered in new dam construction. These risks can have significant impact on project schedule and project budget. Owners, engineers, and contractors need to understand these risks. Existing dams typically were designed in an era of design and construction standards that have been upgraded and changed. Modern standards will impact the construction approach taken and involve understanding the earlier standards. Knowledge of historical standards/practices as well as current design standards and construction methods is valuable for developing and designing rehabilitation components. Construction records and as-built drawings are valuable when they are available. Rehabilitation projects often consist of older projects where as-built documents or construction records are not available. Where these records exist, many (most) times, they do not fully reflect the current conditions within the dam and appurtenant works. leading experienced practitioners to “expect surprises” both during investigation of the existing facility, as well as during construction. “Surprises” should be expected even when historical records of investigations, design and construction are available. Unknowns, be they known unknowns or unknown unknowns, can be planned for by developing an approach for the design and construction process to identify potential issues/problems, or at least alert the designer and contractor of potential issues. A Risk-Based approach applied for the entire life of the rehabilitation project can be used to alert the parties of potential “surprises” and provide direction for mitigating issues as they arise. This type of approach is particularly effective when the process includes senior practitioners with decades of design and construction experience in all aspects of dams. Minimizing impacts created by “surprises”, particularly during construction, can result in an improved project meeting budget and schedule goals and design standards. This paper identifies and categorizes risk types salient to dam construction, reviews the process of risk identification and analysis, discusses guidelines for risk allocation, reviews strategies to mitigate risks, presents several case studies where risk mitigation strategies were employed successfully (or unsuccessfully), and presents lessons learned. The paper concludes with a summary and recommendations for best practices for Project Risk Management and mitigation that can be used by: Owners; Design Engineers; and Construction Managers, in planning, design, pre-construction and construction phases of dam related projects.

By Armando Moyonero, José Villegas, Peggy Peñaloza

La CIA Minera Antamina alineada con su propósito de la búsqueda permanente de la excelencia operativa, la cual permitirá mejores índices de seguridad y resultados operativos más estables y predecibles, decide implementar la metodología LEAN a través del programa denominado ES+. La gerencia de mantenimiento, con el objetivo de mejorar los indicadores y procesos de mantención, haciéndolos más seguros y eficientes con el fin de alcanzar las aspiraciones internas propuestas tanto en seguridad IFAR1, ISAR2, así como disponibilidad en las flotas de palas y camiones de acarreo; inicia la implementación del programa ES+ LEAN en las áreas de palas y camiones de mantenimiento mina.

Sep 29, 2023

By Wilson Quispe, Luis Silva, Rubén Alvarado

El presente trabajo nos permitirá compartir los desafíos que en el pasado reciente se enfrentaron, cuando se pusieron en marcha las primeras operaciones de gran minería que contemplaban los molinos SAG el cual fue resuelto acudiendo a empresas extranjeras para poder cubrir la necesidad de realizar el cambio de los revestimientos. Esto porque los molinos SAG eran nuevos en el país y las empresas prestadoras de servicios mineros carecían de experiencia para poder ejecutarlo.

Sep 29, 2023

By D Xu

BHP Billiton Iron Ore is one of the world’s premier suppliers of iron ore. It currently has operations in Western Australia and Brazil and also has some iron ore interests in West Africa.BHP Billiton’s Optimisation R&D team has developed a proprietary mine planning optimisation tool that uses a mixed integer linear programming (MILP). This tool is called Blasor and it is used to rapidly evaluate the resource development potential (RDP) scenarios for the company’s business development strategy. In addition it generates life of asset (LOA) mine plans for the company’s operations and growth projects. The Blasor optimiser maximises the discounted operating cash fl ow (DCF) as the objective function, subject to mining, processing and transportation capacity constraints and blended product quality constraints. The paper will outline how Blasor has been applied to the resource development potential (RDP) strategy scenario studies, growth project evaluations and LOA mine planning within BHP Billiton Iron Ore.The practical application of Blasor to resource planning optimisation within BHP Billiton Iron Ore has demonstrated the value of such a tool for optimising strategic directions through the evaluation of a number of carefully proposed scenarios and maximisation of operational decisions, such as cut-off grade, open pit development sequence, etc. Particularly for the company’s business development direction studies, Blasor plays the role of a fair valuation tool in that it discovers the most valuable resource development scenario, thus establishing a sound basis for comparing the economic merits of each scenario.

Jul 11, 2011

By Martin Dirks

Nowadays the sinter cooler often becomes the bottleneck of the sinter production, with outdated equipment leading to low productivity and high operation and maintenance costs. Furthermore valuable energy is simply destroyed in the cooler, which is not compatible anymore with a cost efficient and environmentally friendly sinter production. Paul Wurth has developed and improved two types of coolers, the annular cooler and the shaft cooler which offer flexible solutions to the specific situation of each client. The classic design of the annular cooler was completely revised and is now composed of a rigid ringframe construction as opposed to the traditional design with individual sintering cars, avoiding the typical problems of centering. Additional features of the PW annular cooler are the low air leakage rate and the increased effective cooling surface due to the removal of dead areas. This leads, in addition to the lower weight, to lower operating costs and a smaller space requirement. The shaft cooler stands out with an even smaller space requirement and a lower sinter outlet temperature because of a very long residence time of the sinter inside the shaft. Its development into a pure counter flow cooler aims at maximizing its energy efficiency, as it is designed as a system with a very low demand for cooling air, high air discharge temperatures and highly reduced dust emissions. For both cooler types flexible heat recovery solutions can be offered. These solutions include the supply of hot combustion air to the ignition hood burners and the sinter strand, the production of steam for the clients steam grid or the production of electric energy.

Aug 16, 2017

By Renan de Matos Silva

Em função da necessidade constante da redução de custos e aumento da vida útil de equipamentos do setor industrial (como siderurgia, Mineração, entre outros), Aumenta-se a procura por soluções técnicas para tais necessidades. Uma excelente alternativa é fornecer aos equipamentos proteções superficiais que garantem resistência aos mecanismos de desgastes. As perdas econômicas geradas por desgastes prematuros são críticas e generalizados. Estes custos não são somente correlacionados a reposição de novas peças, mas também, paradas de máquinas, perdas de produção, de competitividade e de oportunidade de negócios. Visando melhor atender às necessidades dos clientes e potencializar a performance dos equipamentos, a SMS Group vem desenvolvendo e empregando novas tecnologias de revestimentos por aspersão térmica, com estudos criteriosos apresentando soluções práticas e viáveis.

Oct 30, 2017

By M Dean, M Nehring, P Knights, M S. Kizil

Integrated continuous mining techniques such as fully mobile in-pit crusher and conveyor (FMIPCC) systems offer inherent labour, energy and environmental benefits to deep pit metalliferous mines. However, before such systems become commonplace, a number of barriers must be overcome.This paper outlines a number of commonly perceived barriers to FMIPCC application, together with a number of suggested solutions. The paper advances a design approach for specifying FMIPCC systems for deep pit metalliferous applications. A novel FMIPCC configuration is advanced using a hydraulic excavator in backhoe configuration. Because of the requirement to minimise belt extensions, a mine planning approach is presented based on a series of parallel and radial belt conveyor moves.The FMIPCC system does not fully replace truck-shovel systems. In the proposed mine plan, sinking is undertaken with truck-shovel systems using a series of box cuts, whereas pit ‘widening’ activities are accomplished via the FMIPCC system. Because of inherent differences in mine sequencing, the net present value derived from the FMIPCC mine will differ markedly from that derived from traditional, nested-pit, truck-shovel mining approaches. Therefore, any comparison of the FMIPCC and truck-shovel approaches must take into account radically different mine planning approaches.CITATION:Dean, M, Knights, P, Kizil, M S and Nehring, M, 2015. Selection and planning of fully mobile in-pit crusher and conveyor systems for deep open pit metalliferous applications, in Proceedings Third International Future Mining Conference, pp 219–226 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By David Leidel, Beth Shimer, James Stuart

Periodically, the Institute of Makers of Explosives Safety Library Publications are reviewed, edited and updated to reflect recent technical developments, new commercial explosive products and new regulatory requirements. The rapid proliferation of electronic devices, particularly portable communication systems, inventory management devices, navigational aids, etc., required the revision of the IME Safety Library Publication 20, “Safety Guide for the Prevention of Radio Frequency Radiation Hazards in the Use of Commercial Electric Detonators”. The new edition of SLP-20 has been updated to correct alterations to U.S. frequency allocations and maximum transmitted power permitted and a discussion of communications and tracking systems required in underground mining by the Miner Act. Also, an entire section was added dedicated to safe distances from RF sources to the special type of resistorized electric detonators used in the upstream oil and gas industry on wellsites and an enlarged section describing the particular types of RF sources that the blaster may encounter, perhaps in construction blasting operations.

Jan 1, 2012

By B L. Sommerville

"The theme of this International Mining Geology Conference is ‘Setting New Standards’. Rio Tinto’s iron ore operations include a complex integrated supply system to deliver ore from 15 mine operations through four independent terminals over 1700 km of rail line. Significant growth in the past 20 years has seen production grow from 88 Mt in 1997 to 329 Mt for the 2016 calendar year.With more than 50 years of mining in the Pilbara, Rio Tinto has extensive experience in developing standardised approaches to mine geology and the geometallurgical prediction of product quality to meet the increasing growth profile and business planning complexity.Rio Tinto’s standardised approach to mine geology can be developed and utilised on a daily basis to enable the optimisation of the supply chain in terms of tonnages and product quality. This experience demonstrates a fully standardised system can balance the needs of a systematic process across all mine sites and the flexibility for mine geologist to determine and use local properties at each mine; this is done by ensuring two key principals are in place: a single, centrally maintained, system is established and maintained, providing a common set of processes and software across all mine sites the system allows senior mine geologists to review and customise key attributes and product regressions, ensuring site specific data is used in product predictions.The benefits of formal work process and standardisation include health, safety and environment, people and skill development, cost and improved communication. Also product predictions from mine geologists are one of the key inputs into an integrated and dynamic mine to ship scheduling system, optimising the supply chain whilst still managing the product quality. The experience of Rio Tinto is that a standardised approach to mine geology is an enabler of value for the iron ore operations.CITATION:Sommerville, B L, 2017. Mine geology standardisation – providing the foundation to consistent short-term geometallurgical product predictions in a complex multimine and supply chain environment, in Proceedings Tenth International Mining Geology Conference 2017, pp 13–20 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 20, 2017

By Loic Galisson

"Urban tunneling projects are usually extensively monitored. Most of the instruments used rely on benchmarks providing a sustainable datum throughout the life of the project. The monitoring program also is based on a predicted model of deformation induced by specific construction methods. Events can interfere with those assumptions and eventually alter the stability of these datum. In addition, the anticipated ground conditions and hence the theoretical deformation model often differ from reality. Satellite Radar Interferometry provides useful information to overcome the weakness of the hypothesis made before construction. It is also a powerful tool to ensure the continuity of the monitoring program throughout the life of the project, accurately describing the true effect of the project on the surrounding environment. This paper emphasizes the benefits and limitations of this technique for urban tunneling applications, illustrated by examples of major tunneling projects around the world. MONITORING URBAN TUNNEL PROJECTS Why Monitoring? Retrofitting existing tunnels or constructing new tunnels – including access and retrieval shafts, portals and cross passages – implies an alteration of the neighboring soil structure. Excavating, dewatering, grouting, loading tie backs, etc. artificially modifies the natural equilibrium of the pore-water pressure, of the water table level and of soil stability. In many cases, the effects are immediate: ground loss, deformation of utilities, settlements of buildings, and distortion of infrastructure are a few examples resulting from construction activity.Instrumentation and Monitoring Scope To control and mitigate the risks of damage associated with the above effects, tunnel projects usually include an instrumentation and monitoring program. Depending on the level of geotechnical, structural and environmental risk, the magnitude of this program varies. Projects with a low exposure to risk may restrain the program to conventional methods such as limited topographical surveys and intermittent manual readings of geotechnical instruments. On the other hand, iconic projects with high risk or with controversial history may implement complex and extensive instrumentation plans, involving highly technical solutions such as Automated Motorized Total Stations (AMTS – see opposite Picture 1), Multi-Point Borehole Extensometers (MPBX), In-Place Inclinometers (IPI) and a wide series of fully automated geotechnical, structural and environmental sensors. In this case, all the devices are usually connected to field data loggers collecting raw data around the clock at frequencies ranging from days to seconds, depending on the sensors."

Jan 1, 2016

By A J. Cornah

"The mine geologist’s role in classifying ore from waste during grade control represents a critical link in the mining value chain. Any improvement in the ore/waste selection success rate (thus reduction in misclassification) which can be delivered by the mine geologist represents a value proposition. Improvement achieved without additional operating cost (for example extra drilling and sampling) will directly and immediately add value to the mining operation and therefore clearly must be pursued. Such improvement may be leveraged from existing resource drilling data which are typically less numerous but better quality than the grade control data. They are usually excluded from grade control estimates (termed the ‘base case’ approach here) because of the differences in quality.Various specialised geostatistical tools are available to account for differences in precision and accuracy between data sources during spatial estimation. This paper uses a conditional simulation (CS) case study to assess the benefit of integrating resource data into grade control estimates through ordinary kriging (OK) of pooled data sets, cokriging (CK), and ordinary kriging with variance of measurement error (OKVME) when the grade control data are:unbiased but increasingly imprecisebiased and increasingly imprecise. The premise assumed is that the resource data are unbiased and precise.The paper demonstrates that, if appropriately handled, resource data may be used to improve grade control estimates and thus improve ore/waste selection success without additional operating cost. Where grade control data are imprecise but unbiased it is recommended to integrate resource data using OKVME. This re-appropriates kriging weights from less precise to more precise data locations and improves the grade control estimation precision compared to the base case; it consequently provides an improvement in the grade control selection success rate. If grade control data are associated with significant bias, integration through CK is recommended as the biased data are zero sum weighted. CK consequently provides an unbiased estimate with some improvement in estimation precision compared to the base case and consequently improvement in the ore/waste selection success rate.CITATION:Cornah, A J, 2014. Incremental improvement of grade control models using resource data, in Proceedings Ninth International Mining Geology Conference 2014 , pp 387–396 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 18, 2014