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By D. H. White

The term "block caving" as used in this text includes panel caving and mass caving as described by Julin and Tobie (1973). This method reportedly was conceived in 1895 when a block of ore ranging up to 200 ft (61 m) in width was undercut at the Pewabic Mine on the Menominee Range in Michigan (Bucky, 1956). Over the years this method has evolved largely as a consequence of trial and error in which operators became acutely aware of what nature would allow and what it would not. Today block caving remains somewhat of an art rather than a science where experience often dictates what needs to be done. With the plunging prices of base and specialty metals in the early 1980s caving mines sought to reduce operating and development costs in order to return to profitability. For some this became an impossible task given the design, grade and operating costs of the day and closure became the only alternative. One lesson learned from the experiences of the 80s is that survivability depends on cost competitiveness and this implies the efficient use of resources and technology. To this end applied rock mechanics serves as a useful tool. The purpose of this paper is to show how Geomechanics can be used? in block caving to facilitate sound decision making and how this equates to dollars saved. Features of mining method selection, design and operation are discussed as related to this theme.

Jan 1, 1990

This paper pays tribute to the pioneers in geomechanics, and addresses some of the most pressing issues of our time related to deep mining, and how to mitigate these issues. Solutions developed by our predecessors seem to have reached their limits as mines continue to go deeper. The International Society for Rock Mechanics (ISRM) guidelines for rock mass characterization for excavation design also require re-thinking to reflect current knowledge and experience. Thus, a whole new approach is urgently required to increase mine safety and productivity. The paper will draw on the challenges and experiences in medicine and science that have been overcome through genuine collaboration, advances in technology, and impressive funding, which can be adopted to provide solutions to contemporary geomechanics challenges for increased safety and productivity as mines continue to go deeper.

Jan 1, 2014

By Kurzeme M, Willoughby D. R

Current research at the CSIRO, Division of Applied Geomechanics, into the mode of response of fill as a structural component has been based on model tests for prediction of behaviour and field observation of critical parameters. The procedure is summarised in four stages: (a) define the specific fill function (b) postulate the mode of failure (c) use models to quantify the conditions (d) monitor critical parameters to check or update the analysis in (c). The above procedure is used to postulate the failure modes of each of the possible func- tions performed by fill materials. Analytical techniques, or lines of investigation, are described for each of these modes and specific reference is made, where, possible, to an exis- ting mine environment.

Jan 1, 1973

By Francois E. Heuze

This paper summarizes the geomechanics programs conducted in two hard rock underground mining operations in the Western United States, between 1966 and 1981. The two projects were directed towards understanding the behavior of the rock masses, at the scale of the caverns. To this end, the emphasis was put on large scale field measurements, complemented by limited laboratory testing. The results of these observations were used to build realistic finite element models of the underground chambers. In the marble mine, at Crestmore, California, the models were applied to the structural optimization of the room-and-pillar pattern. In the granite mining, at Climax, Nevada Test Site, the models explained some unusual stress changes observed during excavation. Based on the large number of geomechanical techniques employed, specific conclusions and recommendations are offered regarding the quality, applicability, and usefulness of the various methods. The two case histories clearly indicate chat numerical models are extremely useful for a detailed understanding of the structural behavior of mine openings. To be realistic, these models must be based first and foremost on large scale field observations. The lessons Learned on these two projects also are directly applicable to the design and analysis of nuclear waste repositories in hard rocks such as basalt, granite, and welded tuff.

Jan 1, 1982

By W. G. Pariseau

This contribution focuses on the role of stress analysis for mine planning and the selection of suitable computer programs for the task with special emphasis on coal mine pillars. In this regard, barrier pillars that defend a set of five main entries at the Crandall Canyon coal mine in central Utah were formed during extensive longwall mining north and south of these main entries. Numerical analysis for ground control guided the mine planning and permitting. Retreat mining of pillars led to disastrous events August 6 and 16, 2007, with the loss of nine lives. A most difficult lesson taught by the Crandall Canyon tragedy is the need for education in the selection and use of computer programs for pillar design. Much of this contribution is taken from a report prepared for the Mine Safety and Health Administration (Gates, et al, 2008). Details appear in Appendix Q of the report (Pariseau, 2008). The Crandall Canyon mine is about 16 miles west of Huntington, Utah, in the Wasatch Plateau coal field. Geology of the Wasatch Plateau is described by Doelling (1972) as gently dipping Cretaceous sandstones, mudstones, coal seams, and shales. Joint systems are present in strata above and below coal seams where cleat systems are present as described by Hucka (1991). Several major fault systems transect the field and form grabens with 450- 760 m of drop. One such structure is Joes Valley fault that crosses the Crandall Canyon mine. Mines in the Wasatch Plateau are generally developed from outcrops in steep canyon walls. Overburden increases rapidly as mining progresses into the plateau; mining depth varies with topography between 450 and 600 m in the region of interest. A stratigraphic column derived from a borehole into the mine is shown in Figure 1. There are 11 layers in the column.

Jan 1, 2011

By R. Mark, R. Richards

The Washington National Cathedral is one of the largest masonry structures in the USA, and like many of its European Gothic counterparts, it required nearly a century to construct. The design was altered during this period, resulting in greater loadings than were originally anticipated on the soil beneath the foundation. When signs of continuing differential settlement were observed in the early 1990's, the Cathedral approached the US Bureau of Mines (now the National Institute for Occupational Safety and Health (NIOSH)) for assistance in monitoring the movements of the massive towers and walls. An array of dual-axis tiltmeters was installed about 40m above ground level to measure wall and tower inclination, with the data sent over a dedicated phone line to the NIOSH Pittsburgh Research Laboratory for processing. Mechanical gages and string-potentiometers are also being used to measure motion across cracks and joints, and differential pier settlement is being monitored with optical-level surveying. Data have now been collected for almost 7 years, and they show a long-term settlement trend masked by dramatic diurnal and seasonal thermal movements. The paper discusses the major findings of the study, implications for the future of the Cathedral, and conclusions regarding the use of geotechnical monitoring at major national monuments.

By F. Malek

At Creighton Mine, magnitude events are a regular occurrence due to depth and major seismically-active structures. Over the last ten years, major advances have been made in research and development to develop strategies for the management of these major events. Today, the number of rockbursts has been drastically reduced at the mine and damage due to seismic events, when they occur, is often minimal. This paper describes the evolution and implementation of appropriate geomechanics strategies, designs, and practical ground control measures undertaken for the management of seismicity at Vale Inco?s Creighton Mine. A description of the research and development approach, implementation, and ground control strategy is provided for placement of enhanced support systems to manage the consequences of magnitude events at Creighton

May 1, 2009

By Eder Salazar

Como parte del desarrollo de sus operaciones de mina de cobre subterránea, la Sociedad Minera El Brocal S.A., desarrolló el método de minado tajeo por subniveles con pilares recorridas con el fin de incrementar su producción actual. En ese sentido, el presente texto señala la implementación de un método de minado conforme a las características geomecánicas del macizo rocoso del yacimiento.

Sep 12, 2011

By A Rozendaal

Namakwa Sands, a heavy minerals beneficiation business situated along the west coast of South Africa, is a major producer of titanium slag, pig iron, ceramics quality zircon and rutile concentrate to the international export market. The bulk of the economic mineralisation, which includes zircon, rutile, ilmenite and leucoxene is hosted by a late Cainozoic aeolian succession overlying remnant palaeo-strandline sediments. Relatively younger duricrust layers that cement a significant part of the generally unconsolidated ore compounds the challenging processing character of the primary mineralogy. The complex nature and hardness of the duricrust ore influence their mineability negatively, and can potentially destabilise downstream ore preparation processes. Effectively, up to ten per cent of the entire mineral resource is sterilised as the present infrastructure is not geared to treat the hard-mineralised ore. The metallurgical performance of the primary processing stage, which entails wet density separation, is strongly a function of the quality of the heavy mineral assemblage, liberation state of the economic minerals and slimes content. Elevated concentrations of garnet, a gangue contaminant exhibiting similar physical characteristics as the economic minerals, subtract substantially from the recovery performance of the secondary concentration process, which comprises mainly wet magnetic separation. By contrast, the intrinsic mineral purity of the economic fraction governs its successful recovery to saleable products as stringent product quality specifications apply. Improved mine planning through geometallurgical enhancement of the existing mineral resource model is envisaged to benefit the entire Namakwa SandsÆ mineral beneficiation chain, ultimately aiming to optimise mineral resource utilisation.

Jan 1, 2008

By J. Sliwinski, J. Oliveira

"The application of geometallurgy and corresponding sample selection can take on several formats within industry. Current practice can range from a strictly geostatistical approach to one in which geological and metallurgical parameters are used in combination to create a representative sample selection strategy. The stage of a project and the level of information available at the time of sampling influences the methodology used to create a representative sample.A geometallurgical study of Carpathian Gold’s Rovina Valley Project in Romania is used to demonstrate a sample selection strategy that integrates geological, mineralogical and metallurgical data to maximize the relevance of the geometallurgical unit definitions. This approach, practiced by Xstrata Process Support for its’ clients, ensures that the results of the metallurgical program can be interpreted in the context of these units.INTRODUCTIONGeometallurgy is a cross disciplinary approach in which metallurgical performance of an ore is linked to intrinsic geological and mineralogical characteristics. The objective of a geometallurgical study is to characterize the range of metallurgical performance of an orebody. This allows the geoscientist or metallurgist to create a robust flowsheet able to treat the full range in variability and to develop production strategies to maximize financial performance. The standard approach is to individually sample and test a series of ore types or geometallurgical units. Several different approaches are used in industry to define what constitutes geometallurgical units and how to sample them.One current methodology is the use of multivariate statistics. Geochemical data along with available geological data are used to define multiple variability domains (Williams, 2004; Walters, 2009). There are risks associated with this methodology since the extent of the data set itself may not support a purely statistical approach at the time that metallurgical units need to be defined. The assay suite collected by exploration programs is often limited to pay metals while metallurgical performance is often affected by ore gangue components. Furthermore, in many cases metallurgical scoping and pre-feasibility studies take place prior to the availability of extensive geochemical data sets. Purely statistical methods can produce multiple populations which require extensive sampling, testing and validation prior to consolidation into a reasonable number of composites for metallurgical testing. Methodologies are therefore required that allow representative sampling and testing of consolidated geometallurgical composites to occur at various phases throughout the development of a mining project."

Jan 1, 2013

By D. Michaud, C. Bazin, S. Lévesque, L. Pérez-Barnuevo, H. Longuepée

In recent years, with the emergence of Geometallurgy, a great effort has been made to characterize ore resources as early and accurately as possible, to allow better design and a more efficient operation of mineral processing circuits. In this context, core logging plays an important role, since drill cores provide the first insight into the ore characteristics. However, to satisfy geometallurgical requirements, traditional core logging does not suffice. New tools and methodologies need to be developed for the automation of core logging and the acquisition of mineralogical data better related to mineral processing performances. In this paper, a methodology for the geometallurgical characterization of drill cores is proposed, based on the drill core textural patterns. Textural pattern is defined here as the macroscopic spatial arrangement of minerals. The Mont-Wright iron ore deposit (Quebec, Canada) is used as a case study. The first part of this work aimed at analyzing the potential link between the iron ores textural patterns observed in drill cores and their response to ore processing, namely comminution and concentration. Preliminary results show similar performances in terms of energy consumption and heavy liquid separation for samples showing the same textural pattern. In the second part, this work seeks to develop a methodology for the automated identification of drill core textural patterns by the application of digital image analysis and discriminant function analysis. The results obtained show that this methodology is able to discriminate between the textural patterns identified at Mont-Wright with a good rate of success. Therefore, this work lays the foundation for the development of a new drill core characterization tool, which would allow for the early prediction of the iron ore behaviour during mineral processing through the identification of drill core textural patterns.

Jan 1, 2016

By Antony Amberg, Gonzalo Saldías, Romke Kuyvenhoven, Catherine Souza, Heriban Soto, Francisco Soto

"Vizcachitas is an advanced stage copper–molybdenum porphyry deposit, fully owned by Los Andes Copper and located in Central Chile. The property contains an indicated resource of 1,038 million tonnes grading 0.37% Cu and 0.012% Mo, and an inferred resource of 318 million tonnes grading 0.345% Cu and 0.013% Mo (Coffey & Alquimia, 2014). The deposit occurs in the same geological belt as several other giant copper-molybdenum porphyry deposits including Río Blanco-Los Bronces, Los Pelambres-Pachon and El Teniente. In 2018, the original Preliminary Economic Assessment (PEA) study from 2014 was updated; this paper presents the geometallurgical testwork that was performed to support that update. The testwork focused on the metallurgical characterization of 40 DDH samples and the development of a more profound orebody knowledge by relating geological features with metallurgical performance. The scope of work included complete chemical and mineralogical QemSCAN characterization; SAG, ball mill and abrasion testing; complete rougher and cleaner kinetics including locked-cycle-test; environmental ABA and settling tests on rougher tailings. The results show that the ore can be classified as medium-hard, with a hardness that is slightly below the average for large Cu/Mo deposits in the region. A good correlation was found between lithology and breakage characteristics, implying that the specific energy consumption (kWh/t) is well correlated to rock type. The results of the flotation tests were very encouraging and did not show significant variability. An overall Cu recovery of 91% can be expected for the flotation circuit. The use of a relatively coarse primary grind size gave good final recovery and grade for both Cu and Mo, and deserves further attention in future work, as this impacts positively both energy consumption and water recovery.INTRODUCTION Los Andes Copper Ltd. is a Canadian exploration and development company focused on the acquisition, exploration and development of advanced stage copper deposits in Latin America. The company owns 100% of the Vizcachitas project in Chile, the largest copper deposit in the Americas not controlled by the majors. Vizcachitas is a copper-molybdenum porphyry deposit, located 120 km north of Santiago, in an area of very good infrastructure."

Jan 1, 2018

By L Jackson, A Parbhakar-Fox, N Fox

"Characterisation of sulfide minerals (eg pyrite, sphalerite) in historic tailings can assist in determining whether there are economic benefits of reprocessing such materials using modern metallurgical practices. In addition, there are associated environmental advantages if the historic tailings are actively generating acid and metalliferous drainage (AMD). At the Old Tailings Dam (OTD), Savage River, Western Tasmania, 38 Mt of pyritic tailings were deposited from 1967 to 1982; consequently it has been recognised as an AMD source. Long-term management options considered for this site have included the establishment of either a water, hard-engineered or vegetation cover. However, due to geotechnical challenges posed and the lack of success demonstrated by previous pilot studies, these strategies have not been implemented. Instead, resolving the pyrite chemistry can allow for a first-pass assessment of whether reprocessing these tailings is a feasible option as part of a long-term management strategy for this legacy site.Tailings samples (n = 144) were collected across the OTD from up to 2 m depth from five facies (A–E), and four zones (1 to 4; defined by hydrological regime and grain size). These materials were subjected to acid-base accounting (ABA) and mineralogical evaluations to determine their geoenvironmental characteristics. Following this, 26 samples were selected for in-depth laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) investigations to evaluate pyrite chemistry across different tailings facies. The results revealed enrichment of Co and Ni in these materials. Specifically, Co content was up to 3.0 wt per cent, particularly within facies C to E, and Zones 3 and 4. Cobalt is recognised as a critical metal, therefore, reprocessing should be considered as a future rehabilitation option for the OTD, pending resource definition using established codes and practices.CITATION:Parbhakar-Fox, A, Fox, N and Jackson, L, 2016. Geometallurgical Evaluations of Mine Waste – an Example from the Old Tailings Dam, Savage River, Tasmania, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 193–204 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By H. Wotruba, L. Gronen, A. Hellmann, S. Sindern, J. Katzmarzyk

"This paper focuses on the beneficiation of the REE-Y-Nb-Zr complex ore from the ‘Khalzan Buregtei’ deposit, Mongolia. Pre-concentration based on mineralogical studies was investigated at the Unit of Mineral Processing (AMR) and the Institute of Applied Mineralogy and Economic Geology of RWTH Aachen University. In order to minimize the energy consumption in the most energy intensive grinding process a pre-concentration process using dry magnetic separation of particle sizes coarser than required for the liberation of the valuable ore minerals was designed. Dry magnetic separation in the particle size range of 63-250 µm is suitable as the pre-concentration method, due to the intergrowth of REE-Y-Nb-Zr bearing minerals with magnetic minerals determined by QEMSCAN© analysis. The results showed that a mass reduction of 45.3 wt.-% at high recoveries of REE, Y, Nb and Zr (90 wt.-% and higher) in the pre-concentration product was achieved at the beginning of the process chain. The improvement of process efficiency as shown in this study depends on the abundance and association of minerals affecting the magnetic properties (e.g. hematite) of the ores. Therefore, these mineralogical parameters are as important as grain size and ore grade for the geometallurgical evaluation of potential mining operations at ‘Khalzan Buregtei’.INTRODUCTION Polymetallic deposits containing other critical elements besides REE have the advantage of being robust to economic development and fluctuations of individual metal prices. (Gronen et al., 2016). These deposits can host economic grades of heavy and light REE, Y, Nb, Ta, Zr in complex mineralogical compositions. About 120 deposits of this type are known worldwide, including ‘Norra Kärr’ in Sweden, ‘Strange Lake’ in Canada and ‘Khalzan Buregtei’ in Mongolia which are not valued economically yet. (Salvi. & Williams-Jones, 2004.)"

Jan 1, 2018

By Jean M. Richardson, Steven R. Williams

"Geometallurgical mapping is a new team-based approach that documents variability within an orebody and quantifies the impact of geology (host rocks, alteration and structure) and mineralogy on grinding, metallurgical response and metal recovery processes. The quantitative, spatially constrained database that results can be readily integrated into 3-D block models and mine planning activities. Thus it is an important tool to reduce the technical risk associated with new mine developments or expansions.Normally undertaken during pre-feasibility or feasibility planning stages, the first step of geometallurgical mapping is to review the geology, mineralogy and other critical parameters and construct a geometallurgical matrix. This matrix provides an objective base to then guide sampling and/or compositing activity for physical property and metallurgical testing. Depending on the project, an array of testing techniques can be used to characterize the ore and feed data into the geometallurgical model.While the range and number of tests needed is project-dependant, the geometallurgical mapping approach allows the development of empirical models or interdependent relationships, grounded by spatially-constrained real data. Extensive data sets collected using less expensive testing methods can be meaningfully correlated with results from complex specialty tests to yield realistic metallurgical recovery data.With geometallurgical mapping completed, the resulting database can be integrated into an overall 3-D block mine model. This means that metallurgical response can be used to realistically forecast the recoveries of specific blocks, perhaps sampled only by drilling. Mine planning can then incorporate the forecasted metallurgical response and generate future project cash-flows; opening the door to economic optimization of the mine exploitation."

Jan 1, 2004

By E. Pizarro, A. Videla, G. Compan

One of the main problems related to mining investment decisions is the use of accurate prediction models. Metallurgical recovery is a major source of variability, and in this regard, the Chuquicamata processing plant recovery was modelled as a function of geomining-metallurgical data and ore characteristics obtained from a historical database. In particular, the dataset gathered contains information related to feed grades, ore hardness, particle size, mineralogy, pH, and flotation reagents. A systemic approach was applied to fit a multivariate regression model representing the copper recovery in the plant. The systemic approach consists of an initial projection of the characteristic grinding product size (P80), based upon energy consumption at the particle size reduction step, followed by a flotation recovery model. The model allows for an improvement in the investment decision process by predicting performance and risk. The final geometallurgical model uses eight operational variables and is a significant improvement over conventional prediction models. A validation was performed using a recent data-set, and this showed a high correlation coefficient with a low mean absolute error, which reveals that the geometallurgical model is able to predict, with acceptable accuracy, the actual copper recovery in the plant.

Jan 1, 2015

By Dave Bulled, Chris Bennett, Glenn Kosick, Glenn Dobby

"Mining companies around the world are embracing geometallurgical modeling at a rapid rate, as senior executives realize that inputs must be properly measured if the output is to be managed effectively. Geometallurgical modeling is used to scientifically manage risk in project evaluation, for plant design and production forecasting, and optimization of production planning and mineral processing/metallurgical unit operations. The technology also provides a solid foundation for implementing broad corporate strategies with respect to intelligent asset utilization and metal sales. Over the past five years, MinnovEX Technologies Inc. has been actively engaged in developing, promoting and applying geometallurgical modeling technology for major mining companies around the world. This paper describes the methodology for successfully applying the technology for the unit operations of comminution and flotation in the mining industry.INTRODUCTIONGeometallurgical modeling (referred hereon as geomet modeling), in theory, can be applied to its full potential on all unit operations in mineral processing; however, this paper will concentrate on two of the largest unit operations, namely comminution and flotation, where the technology is actually being practiced by many large mining companies. For concept studies and prefeasibility studies, aspects of geometallurgical technology are regularly applied but in a less rigorous manner than for final feasibility studies where justification for funds is sought. This paper will focus on the final feasibility stage of a project and on existing operations or planned expansions, where the full power of geometallurgical technology is brought to bear in a cost effective manner.One of the unique aspects of geomet modeling, when used to its potential, is the ability to design plants, and forecast and plan production with a quantifiable degree of precision, something that was unattainable in the past. This means that when new comminution and flotation plants are designed, the mining companies and financial institutions involved in the project can measure the precision of the design and therefore better understand and manage project risk. It means that for existing and new operations, metal sales personnel can carry out their sales strategies with a much better understanding of the degree of error associated with production forecasts of concentrate/metal and quality of concentrates. For mine and mill managers, geomet modeling allows the effect of the mine plan on the downstream processes to be quantified; thereby allowing the mine plan to be recast in a more optimized manner. Finally, existing concentrator personnel can optimize their unit operations based on a more definitive understanding"

Jan 1, 2004

"The Dumont deposit is a large (1066 Mt probable reserve) low grade (0.27% nickel), nickel sulphide project located in the Abitibi region 25km west of Amos, Quebec. Royal Nickel Corporation acquired the project in 2007 and has since taken the deposit through pre-feasibility. And updated, revised pre-feasibility was released in July 2012.The disseminated nickel sulphide and alloy mineralization is hosted within the serpentinized dunite subzone of the Dumont Sill; a differentiated, pervasively serpentinized, ultramafic sill of komatitic affinity. Pentlandite, heazlewoodite and awaruite are the dominant nickel-bearing, metallic phases and can be recovered by conventional methods (flotation, mag separation). Non-recoverable nickel is also present within the silicate matrix of the serpentinized dunite and is locked in serpentine (Fe and Mg-rich variants) and minor olivine.A detailed mineralogical program including 1097 QEMSCAN® samples and 4300 electron microprobe points were undertaken to increase the understanding of the nickel deportment in the various recoverable and non-recoverable phases in a spatial context across the deposit. Eighty-three (83) metallurgical tests performed under a standard procedure have linked the mineralogy to metallurgical performance. This has allowed the creation and modelling of geometallurgical domains on a block by block basis to understand the recovery variation and metallurgical performance throughout the deposit. Understanding the spatial variability of Ni deportment in recoverable and non-recoverable phases through mineralogy is the key to understanding metallurgical performance thus, unlocking the value of the Dumont deposit and other large tonnage low grade ultramafic nickel deposits."

Jan 1, 2013

By K. Nasrallah

"The Dumont deposit is a large (1,179 Mt proven and probable reserve) low grade (0.27% nickel), nickel sulphide project located in the Abitibi region 25km west of Amos, Quebec. Royal Nickel Corporation acquired the project in 2007 and has since taken the project from a scoping study in 2010 through to completing the feasibility study in July 2013.The Dumont deposit in a nickel deposit with the recoverable nickel contained in three minerals; pentlandite, haezlewoodite and awaruite. The minerals are recovered by a combination of flotation and magnetic separation. Over the course of the studies many flowsheet design decisions and changes were made. This paper outlines an overview of the project, flowsheet design including the comminution circuit, desliming and awaruite recovery. The overall resulting flowsheet that was used for the feasibility study is then presented along with the confirmatory locked cycle testing that showed the feasibility design basis was able to produce the predicted concentrate grade and recovery.IntroductionRoyal Nickel Corporation (RNC) is a mineral resource company headquartered in Toronto, Canada, primarily focused on the exploration, evaluation, development and acquisition of base metal and platinum group metal properties. RNC's principal asset is the Dumont Nickel project (Dumont project) located in the established Abitibi mining camp, 25 km northwest of Amos, Quebec. RNC acquired a 100% interest in the Dumont property in 2007. The mineral claims covering the Dumont deposit are currently held 98% by RNC and 2% by Ressources Québec.The Dumont project is located in the province of Quebec in the municipalities of Launay and Trécesson approximately 25 km by road northwest of the city of Amos, 60 km northeast of the industrial and mining city of Rouyn-Noranda and 70 km northwest of the city of Val d’Or."

Jan 1, 2016

By Andres Salazar, Carlos Delgado Robles, Richard K. Preece

Minera Escondida, located in the Antofagasta Region of northern Chile, is the world’s largest producer of copper as concentrate and SX-EW cathode. Projects to increase mill and flotation capacity began soon after start-up in 1990 to off-set decreasing copper grade. Subsequent projects had the objective to increase copper production through heap leach and SX-EW production and a second concentrator. The mine footprint concurrently expanded peripherally from the central high-grade enriched core of Escondida and then into the separate Escondida Norte deposit. Early in the mine life, metallurgical forecasting that was based on metallurgical composites of presumed ore types and historical plant production was adequate for operational planning, plant design, and project valuation. This approach became unreliable, however, as the increase in mine footprint was accompanied by an increased variability in key ore body characteristics such as hardness, copper-iron sulfide mineralogy, and sulfide liberation textures that were not reflected in the geological criteria used for ore type designation. The project study teams turned to small-scale physical and chemical tests to better characterize the spatial distribution of these key ore characteristics. Programs associated with capital growth projects were carried out through the mid-2000s to sample and construct a three-dimensional spatial model of hardness, copper sulfide mineralogy, and rougher flotation recovery from tests on 15-m drill core composites. Mathematical models were developed from the respective ore characteristic data to calculate throughput, flotation recovery, and concentrate copper grade. The spatial models were integrated with the concurrent mineral resource block model using standard geostatistical methods and the metallurgical process calculations were applied to the block estimates. The geometallurgical model, originally constructed on a project basis, is now managed by a dedicated team reporting to the manager of Geosciences & Resources Definition in the Escondida organization. The model has evolved with increasing complexity of the mine and processing plants and currently includes seven forecasting areas for three concentrators and four areas for two leach plants. Metallurgical forecasts of mill throughput, final flotation recovery, and concentrate copper grade still have the highest relevance to mine planning and optimization. Sample preparation, test procedures, and quality control methods are summarized for the ore characteristic tests important to these forecasts. Analytical results from recent annual sampling programs are presented for the hardness indices, rougher flotation recovery, and partial extraction copper analyses. Geostatistical analysis of the SAG mill hardness index is summarized as an example for the spatial estimation process. Mathematic models are presented for throughput (based on hardness indices), final flotation recovery (based on rougher recovery and plant calibration studies), and concentrate copper grade (based on sulfide mineralogy and empirical pyrite rejection studies).

Aug 31, 2023