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By M Bellamy

The DeGrussa copper deposit was discovered by Sandfire Resources in April 2009. Construction of the 1.6 Mt/a concentrator, open pit and underground mining operations commenced in March 2011 with first concentrate production achieved in October 2012. Over the next ten years, DeGrussa grew to include both the DeGrussa and Monty underground mines, establishing itself as one of the world’s premier copper producers with total production of 663 000 t of contained copper by the time the mine closed. Final ore was trucked from Degrussa on 5 October 2022. This paper examines the mine closure experience from both a planning and operational perspective. The paper provides an overview of the site’s mine planning process including the factors involved in determining the end of the mine life and how this was tracked and communicated in the lead up to the end of mining operations. It will also look at some of the specific operational aspects involved in maintaining steady state production all the way through to the last day while facing increasingly challenging conditions. These factors, along with the external factors faced by most of the industry such as labour shortages and COVID related disruptions, contributed to making it an interesting journey to the end of operations at DeGrussa.

Mar 29, 2023

By R Shaw, T T. Neidel, C Adams

Sampling equipment manufacturers endeavour to ensure that the mechanical equipment installed in sampling systems are designed and manufactured to adhere to the requirements of the International Organization for Standardization (ISO) or other standards relevant to the application. The mechanical parameters necessary to achieve these standards can be well controlled and requirements such as constant speed can be met through good mechanical design and engineering. However, when the equipment is installed and put into operation, the ISO compliance of the system is out of the hands of the equipment manufacturer and handed to the operator, who may be a generalist control system integrator.Making a sampling system perform according to standards, and being able to monitor and report on compliance require that the sampling system knowledge and the control integration is combined and applied in an integrated approach. Using a dedicated library of control routines developed for sampling can change a system from having compliant equipment to being a compliant system. The library has to include monitoring of relevant parameters and control and reporting on sampling parameters.CITATION:Neidel, T T, Adams, C and Shaw, R, 2014. Control and monitoring of International Organization for Standardization compliance for industrial sampling systems, in Proceedings Sampling 2014 , pp 121–126 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

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 G Hancock, A Kemp, I Taylor

The mine site is situated south east of Port Hedland in the Pilbara region of Western Australia. A detailed engineering design was undertaken for six irregularly shaped waste rock dumps at the site. The design was undertaken to ensure long-term stability of the dumps and optimise material movements for closure construction. The Watershed Erosion Prediction Program (WEPP) and SIBERIA landscape evolution modelling was undertaken for the landforms using regional and site-specific material characteristics to provide an indication of the maximum allowable slopes and corresponding slope lengths for long-term stability.The majority of the waste materials present in the waste rock dumps are considered likely to be subgrade banded iron formation (BIF) and chert, which is generally competent material. The presence of a large number of dolerite dyke swarms indicates appreciable volumes of dolerite were produced as waste from the pits. Geological records also indicate that the dolerite is logged as being heavily kaolinised in the geological logging, hence kaolinite is very likely to be present within the waste dumps on-site. This material has an elevated risk of being highly erodible/dispersive. Clays and shales are also likely to be present in the dumps and are considered to be less competent material (relative to the BIF/chert).The final design configuration of the largest existing ‘unplanned’ waste rock stockpile is compared to a hypothetical continuous ten degree outer embankment alternative. This paper will present a brief description of the alternatives for closure of three waste dumps in close proximity to each other and how the detailed design based on site-specific materials and conditions compare to an alternative approach blankly assuming that most materials will be erosionally stable at less than ten degrees.CITATION:Kemp, A, Taylor, I?and Hancock,?G,?2014. Landform design for Pilbara mine site – why plan and design waste rock dumps for closure based on site-specific conditions?, in Proceedings Life-of-Mine 2014 , pp 47–54 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By R G. Barker, N Mortimer

In New Zealand, platinum group metals (PGM) occur in three main geological environments of economic interest: layered mafic igneous complexes, the Dun Mountain Ophiolite Belt, and in association with placer gold deposits. Most of the layered mafic complexes with PGM potential occur in the Median Batholith. These include the Longwood (Permian), Bluff (Permian), Riwaka (Devonian) and Rotoroa (Jurassic) igneous complexes. Exploration of the Longwood Complex discovered PGM associated with gabbroic rocks. Best assays to date include a 1 m drill intersection of 1 g/t Pt + Pd and float rock with 3.0 ppm Pt and 3.3 ppm Pd. The Greenhills complex at Bluff consists of basal dunite overlain by wehrlite and gabbro. PGM occur with chrome spinel in the basal dunite and Pt geochemical anomalies have been identified associated with the wehrlite-gabbro contact zone. The Greenhills complex has some similarities to Alaskan-Ural type complexes.Reconnaissance exploration in the Dun Mountain Ophiolite Belt has identified PGM geochemical anomalies, but no follow-up work has been carried out. During the late 1800s and early 1900s, PGM were recovered as a byproduct of placer gold mining in Southland. Placer gold prospects with PGM potential include the Waiau River, deposits flanking the Longwood Complex and some Southland beaches.

Jan 1, 2002

In current mining practices it is desirable to bring about a substantial increase in both rate of face advance and productivity, thus compelling the mine engineer to consider better and more productive ways of mining. Transportation plays a vital role in achieving improved productivity. This paper focuses on horizontal transportation systems. Horizontal transportation is defined from the shaft station area to the end of the stope cross-cut. Traditionally, horizontal transportation is inefficient in comparison to vertical transportation efficiencies and accounts for a high proportion of South African mine accidents. Thus, the role of horizontal transportation has been investigated in detail, as it offers the greatest chance for improvement. The purpose of the paper is to provide a best practice guideline for the design of horizontal underground transport systems. It is intended that the document be used by mine designers and planners as an aide memoir during the design process and benefit may well be gained from retrofit and reorganisation activity. The paper looks at transport systems suitable for deep level gold mining in South Africa and evaluates such items as management, scheduling, and haulage systems. Current transportation systems for personnel, material and rock transportation are evaluated, gaps in technology highlighted, and recommendations made.

Jan 1, 2003

To obtain the best economic results in treating the comparatively high-grade ore of the Kalgurli Mine a good roast is essential, and the effort of this paper will be to briefly describe the plant and the conditions prevailing in roasting, which, on an output of about 360 tons daily, subsequently enable an average extraction of slightly over 94% of the gold to be maintained.The percentage of sulphur in the ore varies between 2'5 and 3'5, the lower figure existing when treating oxidized ore. The average gold value is 13 dwt; this occurs chiefly as sylvanite, containing .a lower percentage of silver than is usually present in that mineral. One ore body in the mine contains hessite (Ag2Te) in considerable quantity, associated with gold telluride, and when ore from this stope is being treated the silver contents rise to as high as 20 dwt, but the usual amount is about 9 dwt. per ton, of which only a small proportion is extracted. Other metallic minerals, in addition to pyrite, occurring more or less commonly, are arsenopyrite, magnetite, chalcopyrite, and the tellurides calaverite (AuTez)and coloradoite HgzTe3). A small proportion only of the value occurs as free gold.

Jan 1, 1911

By W Zirima

A detailed, mine scale non-linear numerical model of Rosebery mine has been built for the purpose of simulating life-of-mine global deformations. The model was calibrated using observations of displacement and damage, and was then used to investigate the correlation between dissipated plastic energy (DPE) and seismic event occurrence. The study is unique because the seismic data was collected over a relatively short period using a temporary portable seismic system. It is the intent to undertake significantly more work, but the analysis of limited data shows that a very good, non-linear relation between DPE and event probability is present. The observed correlation is consistent with measurements from other mines where more data was available. With more data, the strength of the correlation will allow the DPE analysis to be used during the design and sequencing phase of planning to better design the mine to minimise seismic hazards.

Jan 1, 2008

By D Drinkwater

In 2009, Peter Munro and Peter Tilyard examined the “human capital” in the mineral processing sector in a paper entitled Back to the Future (Munro and Tilyard, 2009). One of their major concerns was a general decline in technical skills and process knowledge, exacerbated by lack of appreciation of the impact this can have on process plant performance and, ultimately, profitability or sustainability of the industry. There are many reasons for this decline, not least of which are the work schedules of today’s metallurgists which have a very different balance between technical and non-technical responsibility than those in the past. However, a shift towards a more technical focus has potential to deliver a range of benefits for industry at large and for the individuals in it This paper discusses some options for development of core metallurgical and process engineering skills that can be used by graduates, employers and training providers.Key skills are identified and mapped against available opportunities for development, such as existing graduate programs, on-the job training and external courses. The authors also review a number of past and present high-quality graduate development programs, including the graduate development program in place at Mount Isa Mines in the 1980s and the Anglo Platinum Graduate Development Program (AGDP) currently operating in South Africa.

Aug 8, 2011

By A F. D C Varajpo, R C. Weba, C Volkmer-Ribeiro, C A. C Varajpo, N S. Gomes

This study relates to the spongillite deposits from the region of Jopo Pinheiro, in the north-west of the State of Minas Gerais, south-eastern Brazil. The deposits occur in shallow ponds (with a maximum depth of 3.5 m) on a karstic planation surface developed on rocks of the Spo Francisco Neoproterozoic Supergroup. Cenozoic detritic covers are associated with this surface. The field study of spongillite deposits from the Preguita and Avipo deposits revealed sedimentological and pedological similarities between the different deposits. They have a lenticular shape and contain different layers of sedimentary spicules intercalated with layers of quartz sand and clay minerals. Representative samples from the different layers investigated by X-ray diffraction, differential and gravimetric thermal analysis and infrared spectroscopy showed a range from three to 80 per cent of amorphous silica (opal) corresponding mostly to the sponge spicules in the sediments. Optical microscopic investigation determined that the spicules predominantly belong to the sponge Metania spinata. This species is represented by smooth megascleres (alpha type), prickly megascleres (beta type) measuring 240 to 450 mm in length, as well as the spiny microscleres; whereby the smooth megascleres are larger and thinner. The morphological variation of the spicules as well as the presence of more fragmented spicules towards the base of the deposits, portray a variation in texture and in the state of their preservation along the profile, suggesting environmental variations at the time of their formation and deposition.

Jan 1, 2008

By H Kurth

Oyu Tolgoi copper and gold mine in the southern Mongolia holds mineral resources that make it one of the largest known copper and gold deposits in the world. The project is operating an open pit mine on the near surface of Southern Oyu deposit and developing underground block-caving mine at the Hugo Dummet North where 80 per cent of total resources exists. Oyu Tolgoi (OT) commenced open pit mining in 2011 and implemented an industry standard blasthole sampling, and ordinary kriging grade control estimation with block-out process. Since 2017, grade control improvement projects have successfully completed that have led to the implementation of current, improved grade control system. Geological model is updated by blasthole logging on Leapfrog® and used for daily grade estimations. GC estimation is proceeded solely on Vulcan® by running Lava script and integrating with a relational database. Combination of block-out procedure produces GC model which is updated in Vulcan® and as well as in the database simultaneously. Switching to the integrated database eliminated many manual processes such as importing and exporting data and enabled access to the database anytime, anywhere and from any device. Thereby, these improvements allowed to increase an efficiency, create a comprehensive reconciliation system and reduce operational risks. We are looking forward to expanding applications of integrated grade control data stored in the database. This paper outlines how the grade control system was developed at OT’s open pit mine, and how it is integrated into the short range mine planning, mine reconciliation workflow and ultimately enabled development of various automated reporting systems.

Mar 22, 2022

By Y Xu, J Hacker, D J. Williams

Shear strength parameters of compacted clay liners are needed to analyse the stability of mine waste dumps containing compacted clay liners as sealing layers for potentially acid forming waste rock. A representative clay sample was supplied by McArthur River Mine from the mine site in the Northern Territory, Australia, with an average as-supplied gravimetric moisture content of about 13.6%. The clay was compacted in a 100 mm by 100 mm direct shear box at the as-supplied moisture content to a dry density of 1.85 t/m3, representing the field compaction specification adopted by the mine. To determine the peak and ultimate shear strengths of the compacted clay, single-stage direct shear testing was carried out at nominal initial normal stresses of 50 kPa, 100 kPa and 200 kPa, representing shallow depths of burial in the North Overburden Emplacement Facility of about 2.8 m, 5.6 m and 11.1 m, respectively (assuming a waste rock wet unit weight of 18 kN/m3). Three shearing rates of 1 mm/min (rapid), 0.1 mm/min (intermediate) and 0.01 mm/min (slow) were applied to study the influence of shearing rate on shear strength. In addition, the development of a residual shear plane was tested by reversal and re-shearing in the direct shear box. In the first shearing, the peak and ultimate shear strengths are determined. The normal load was then removed and the box rewound to its starting position. The normal load was then re-applied and the specimen re-sheared. Two reversals were applied to each specimen, and it was found that there was no significant reduction in shear strength. Finally, based on a range of shear strengths obtained in the laboratory for McArthur River Mine clay and other materials by various laboratories over time, shear strength parameters for the compacted clay were recommended for use by the mine.CITATION:Xu, Y, Williams, D J and Hacker, J, 2018. Shear strength of compacted clay liner at McArthur River Mine, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 208–219 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By M Bloss, B Roberts

BHP Billiton Olympic Dam required a well-tested software product suitable for strategic optimisation and scheduling of options for a potential underground mining project. The company has a standard software package called Blasor® that is used for open pit optimisation of complex deposits such as iron ore, copper-gold-uranium and silver-lead-zinc. It applies a mixed integer programming formulation (MIP) to produce conceptual pushback designs and an optimised pushback sequence. Schedules can then be run on the resulting mine designs. Existing pushback designs can also be imported into the model and an optimum schedule generated. One of the key advantages of Blasor is that multiple strategic mine schedules can be quickly generated according to the various scenarios, options and constraints that are being investigated.It was realised that Blasor, if carefully configured, could be adapted for use in underground planning. The concept of using Blasor as an optimiser for underground strategic scenarios is to represent the underground stope and development data in the form and structure of an open pit mine. In simple terms, underground stoping areas are modelled in the form of pushbacks (phases) with vertical walls. The phase dependency tools in Blasor are used to link mine blocks and their access development drives. These underground phases are imported into the optimiser. Artificial block models are constructed using stope design tonnage and grade data at various fixed cut-offs. A variable cut-off grade model has also been developed using a method of parcels to represent each cut-off grade increment.So far, this approach has been successfully used to investigate the optimum stope design cut-off for various strategic options, the economic potential of a series of mining and processing configurations and to provide guidance on the optimum sequence for developing and mining the various stoping blocks in the resource. Examination of the results has highlighted the most suitable development paths for more detailed study.CITATION:Roberts, B and Bloss, M, 2014. Adaptation of an open pit optimiser for underground strategic planning, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 249–256 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By D Willis, A Shanahan, C Jacobs, T Luxner

The application of tunnel boring machines (TBM) for reef mining is a unique practice with benefits over current mining methods given the right geology and geometry of the orebody. The Stillwater Mining Company (SMC) of Nye, Montana, USA operates two mines for obtaining platinum metals. The operation is currently using a 5.5 m diameter open-type machine for further mine development, as well as another TBM that they own.The latest 7.1 km bored tunnel, known as the Blitz Tunnel, will be routed parallel to the ore deposit in igneous mafic intrusive rock, and will be used for the life of the mine operation. It will be used to map the ore deposit, and provide a rail haulage route.Detecting the reef in relation to the TBM requires careful analysis. Diamond core drilling occurs ahead, above, and alongside the machine at every 150 m. The core is drilled, logged, and interpreted on the spot, concurrent with boring. Based on the data, the TBM is readjusted so that it stays on the correct bore path.This paper will highlight the application and benefits of TBM usage for reef mining, with detailed descriptions from the mine site.CITATION:Willis, D, Jacobs, C, Luxner, T and Shanahan, A, 2014. Tunnel boring machine usage speeds up development at Stillwater Mine, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 683–690 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By K L. Silversides

Shales form distinctive peaks in natural gamma downhole logs, which are used to manually identify the location of ore boundaries. These shales form important lithology markers that can potentially be automatically identified using Gaussian processes. This approach is trialled using data from a typical iron ore mine in Western Australia which contains the Marra Mamba sequence of the Hamersley province.The method uses Gaussian processes (GPs) with a single length scale squared exponential covariance function. A library of 8 m sections, where natural gamma measurements were taken at 10 cm intervals down the hole, was used to train the GP model. This library was iteratively improved and was tested using natural gamma logs that were not included in the library. Areas that were misclassified or were not clearly classifi ed were added to the library. The new library was then used to train the model and improve the results. The trials used a double gamma peak from the NS3 and NS4 shales at the boundary between the Newman 1 and Newman 2 ore zonesin the Newman member and the AS1 and AS2 shales at the base of the West Angelas member. The results show that both boundaries can be identifi ed with an accuracy of over 99 per cent. The classification has the highest accuracy on undeformed shales. This method provides a fast, accurate and objective identifi cation of shale and ore boundaries and can potentially replace the current manual detection.

Jul 11, 2011

By D Elmo, M Scoble, Y Liu, B Klein, J Scholar, S Nadolski

A cave-to-mill study being conducted at the New Afton block caving operation demonstrated the potential for sensor-based ore sorting equipment to reject waste and improve the grade of feed to the mill. The lack of selectivity and potential for dilution entry associated with the block cave mining method results in many caving operations having to mine and process material that is below cut-off grade at certain stages of production. Online monitoring and bulk sorting systems have the potential to alleviate this problem and improve the productivity of caving operations while reducing energy and water requirements for each tonne of concentrate produced.As part of the cave-to-mill study, the suitability of a range of sensors, such as X-ray fluorescence and induction-type sensors, to sort mine production at the New Afton mine was investigated. Results showed that the discrimination of ore and waste can potentially be carried out by implementing surficial sensors into the material handling system. The study also showed that a combination of sensor outputs could be used to identify a certain ore type so that pre-emptive changes can be made in the mill to improve beneficiation performance. Overall, the outcomes of the study on implementing sensor systems at block cave mines are considered to be of significant relevance to a number of existing and future caving operations.CITATION:Nadolski, S, Klein, B, Elmo, D, Scoble, M, Liu, Y and Scholar, J, 2016. Investigation into the implementation of sensor-based ore sorting systems at a block caving operation, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 393–400 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By R Dunne

"Continuous improvement on metallurgical treatment plants is possible only when good data and analysis of the data are available. Good data implies appropriate and accurate mass measurement coupled with good sampling practices and accurate chemical analysis especially when carrying out monthly metallurgical metal reconciliations. Adequate characterisation of key samples (eg tailings, feed, concentrates and others) at timely intervals is an important part of a good continuous improvement program. The data from this will help identify opportunities to improve operation performance and thus profitability. Examples are provided of projects that have led to improved plant performance based on good metallurgical data collection and analysis.Citation:Dunne, R, 2016. Using Metallurgical Data to Drive Continuous Improvement, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 201–206 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

Large deposits present computational challenges to todayÆs commercial orebody modelling systems that are based on conventional block models. We describe a system that is specifically engineered to model and visualise large deposits. Central to the system is linear octree encoding of conventional block models and real-time conversion of three-dimensional (3D) meshes to linear octrees. We provide both methodological treatment and practical experience in implementing such a system. A commercial implementation is also presented to demonstrate the validity of the approach.

Sep 26, 2011

Mother Nature controls, technical professionals model and miners decide. Decisions to explore, mine and mill. Mine decisions, mine design, planning and scheduling are subject to the quality of models û geological models, geotechnical models, resource models, density models. The closer these models are to reality, the more accurate the predicted outcome. So why is it we delegate the modelling tasks to the most junior and least experienced people? If we insist on this, we need to support them û to provide them with æexperience acceleratorsÆ. Technical mentoring is the most effective way to provide the right information at the right time. When this information (read skills) is supplied at the right time we can inject experience into the quality of our modelling and into our decision- making processes. The objective of this paper is to share those behaviours and manners that foster relationships and create frameworks for skills and experience transfer. Central to this is an understanding of how adults learn, an understanding of the basic rules of mentoring etiquette, and the three keys to building meaningful mentoring relationships. An understanding of adult learning processes and styles provides a structure within which a mentor can understand the learnerÆs perspective. Understanding the world from the learnerÆs point is critical to selecting the right language to engage, teach and transfer skills. Basic rules of mentoring etiquette like timeliness, respect and trust need to be brought into the consciousness so they can be agreed on and monitored to prevent conflicts in cultural and generational norms between the mentor and the learner.Meaningful relationships hinge on the three behaviours: truly listening, rather than just hearing; understanding the technical issues within the WIIFM (whatÆs in it for me?) question; and facilitative behaviour. Stronger and more meaningful technical mentoring relationships within our industry will bridge the generational gap and ensure we can capture and capitalise on the wealth of grey hair experience and develop an informed group of young decision-makers.

Jan 1, 2006

By R M. Arellano, D M. W Harney, M Makhuvha

Mineral resource and ore reserve estimates are founded on two sources of data: tonnage and grade. The tonnage is a product of volume and density; both of which are estimates. Density impacts numerous operational factors, which include, but are not limited to, mine design, mine planning, equipment selection and operational performance. Hence, density is a significant parameter and its determination requires similar care as the measurement of grade. Selecting an appropriate method to determine density, and ensuring its rigorous application, thus reduces risk and can improve operational performance, which in turn increases profit margin.Different Anglo American sites use a variety of practices and protocols to determine density, which is highly dependent on the physical characteristics of the orebody, local conditions and historical practices. Also, individual sites sometimes execute the same method in a slightly different way, which may also affect the outcome of the measurements. In order to gain a better understanding of how density is determined at Anglo American projects and operations, a review of these techniques was undertaken. The objective of the study was to identify and share good practices across the company, as well as to look for improvement opportunities, where applicable. Ten different methods of measuring density, applied to nine different commodities, were identified and described. An additional technique was recently developed by Anglo American Technical Solutions. The core pycnometer is a large gas displacement pycnometer capable of measuring density at high accuracy on full pieces of intact core.This paper provides an overview of methods used to determine density within the Anglo American Group, including quality control and quality assurance aspects. It is not the purpose of this paper to identify a preferred method, but to highlight the importance of choosing the best suited practice for a project or mine site. In addition, a case study comparing two different density determination methods applied to the same rock samples from the Los Bronces Copper mine was undertaken and the results of that study are presented here.Selecting the most appropriate method to determine density and comparing results from two or more techniques against each other, together with other suitable quality control procedures, is considered to be of utmost importance for all mining operations and exploration projects.CITATION:Makhuvha, M, Arellano, R M and Harney, D M W, 2014. Determination of bulk density in Anglo American plc, methods and impacts, with a case study from Los Bronces Mine, in Proceedings Ninth International Mining Geology Conference 2014 , pp 85–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014