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By T M. El Hajj, A C. Chieregati, M T. G C Marques, J M. Braga Jr, H Delboni Jr

"The estimate and control of sampling errors is essential for all mining operations, especially when dealing with strategic materials, such as niobium. This paper is based on a traditional quality assurance and quality control technique used to confirm mineralised intersection zones, and proposes the validation of sampling data using diamond drill twin holes, in order to evaluate and improve the quality of the current data set. The geological model of the niobium mine – located in Araxá, Minas Gerais, Brazil – was built including 77 diamond drill holes of a sampling campaign carried out during the 1970s. There are few records about the collection and preparation procedures of these past samples, making it difficult to estimate the errors associated with their analytical results. Therefore, 11 twin drill holes were drilled to compare their samples against the samples from the 1970s drilling campaign. The new hole locations were chosen as near as possible to the old holes location. The JORC Code, 2012 edition, relates the use of twin holes as a good sampling technique to assess sampling and assay data. Three parameters were considered to validate the 1970s drill hole campaign by the twin drill hole campaign: the difference of the coordinates between the paired holes the difference among the positions of the geological contacts to validate the geologic description the difference between the paired samples grades was calculated to validate the analytical results.The analysis of the grade range variation between sample pairs was based on three techniques: geostatistical interpretation of vertical semivariogram to obtain the nugget effect calculation of the relative difference between duplicates calculation of the error associated with the sampling protocol established according to Pierre Gy’s Theory of Sampling.The results were satisfactory for hole coordinates; however, the ore content showed a high deviation, although this divergence can be explained by the nugget effect. For the lithological intervals, the new results contributed to an effective identification of variations among lithologies, ie brown weathered ore and saprolite. The twin drill holes campaign successfully validated the geological model data, allowing effective mine planning and higher reliability of the reconciliation results.CITATION:Marques, M T G C, El Hajj, T M, Braga Jr, J M, Chieregati, A C and Delboni Jr, H, 2017. Theory of Sampling and geostatistics for twin drill holes analysis in a niobium mine in Araxá, Brazil, Australia, in Proceedings Eighth World Conference on Sampling and Blending, pp 97–106 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

May 9, 2017

Determination of Porosity and its Influence on Specific Surface

Sep 13, 2010

By G B. Arehart, S J. Mathews, J L. Mauk

The banded nature of the quartz veins which form the Empire lode at the Golden Cross mine, is perhaps their most striking feature. Petrographic studies show that significant differences occur between the bands in terms of textures, quartz grain size, calcite, adularia and kaolinite content, and the form, concentration and mineralogy of sulfide phases.   The d18Oquartz values of individual bands within the vein material range from 7.3-10.9ë. Calculations show that the d18Oquartz values can be adequately explained by temporal variations in the system temperature, boiling and/or variations in the systems fluid/rock ratios.

Jan 1, 1995

By P Stoker

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Mining and exploration properties have a unique set of technical risks. Privately-owned companies considering investing in the resources sector can optimise their investment decisions by adopting a systematic technical assessment of acquisition assets, similar to the approach commonly adopted by public financial institutions and publicly-listed companies.Technical due diligence provides a process to identify key geological, mining, geotechnical, metallurgical, environmental and social risks and opportunities and determine the most likely business case and valuation of assets. Technical due diligence is commonly carried out in parallel with legal, commercial and financial due diligence, often involving the acquirer, to maximise the understanding of the investment.There are significant advantages in investors conducting a comprehensive technical due diligence, which typically involves site visits and project assessment to international standards by an independent, multidisciplinary team of experts. The outcomes provide the opportunity for the investor to make early, informed decisions and to understand and manage risks.Technical due diligence may be carried out at several stages: when considering and weighing up a number of investment options, prior to and during a transaction or immediately post-transaction. In the first stage, the outcomes will inform the choice of investment and, more particularly, whether there are any fundamental flaws in the projects being considered. In the second stage, due diligence outcomes can inform the level of investment and approach to risk management and planning. In the third stage, risks and opportunities can be investigated in more detail, allowing the investor to consider the best options to reduce risk and maximise the benefit of the investment.This paper presents a summary of the technical due diligence assessment process, its benefits to investors, common risks in mining and exploration projects known to cause mining asset write-downs and principal technical due diligence approaches.CITATION:Keogh, A, Stoker, P and Thomas, M, 2015. Benefits of due diligence in private equity mining investments – maximising value and unearthing common risks , in Proceedings PACRIM 2015 Congress, pp 115–126 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By D Kepert

It is the role of the exploration geologist to create wealth through the discovery, delineation and characterisation of economic mineralisation. This requires a critical depth of geological understanding.Unfortunately, the resource industry is well known for its cyclic nature. Many of the current generation of workers have only ever experienced the boom of the ‘super-cycle’ and are only just discovering the negative side to the business. For the case of the geologist and especially the exploration geologist, the magnitude of peaks and troughs are usually amplified and may become destructive to all parties. During the uptime a healthy stream of exploration good news becomes the staple diet of company releases, in particular those of junior companies attempting to bolster the share price. The geological knowledge and experience gained thus forms a significant and integral part of the value and therefore, future of a company. On the downturn it is often viewed that geologists are a luxury, an optional extra and a burden on the bottom line with companies entering a period of memory loss and myopia.Retention of geological knowledge however remains critical as projects, companies and cycles mature. Beyond exploration per se, this knowledge becomes both fundamental in de-risking and commercialising an asset (through development or divestment) and in positioning the company for cyclic or counter-cyclic opportunities.The growth and retention of this knowledge base is difficult to quantify in terms of direct value but becomes one of a successful resource companies greatest assets. At worst, its loss can lead to millions of investors’ funds wasted on missed opportunities, drilling, or poorly designed plant and mine.But the rocks are around for the longer haul and pay little notice to the vagaries of the scurrying of Man.This paper reflects on some of the authors own observations through 25 years of iron ore exploration, in why it is critical to always rigorously question the prevailing geological (mis)understanding and the technical and commercial benefits which that may bring, and looks forward to the future.CITATION:Kepert, D, 2015. Geology – the affirmative case, in Proceedings Iron Ore 2015, pp 285–298 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By E Villaescusa, A Kusui

The depth of underground mines has been increasing due to several factors, such as material demand growth and improving technology. It is a challenge to understand severe failure mechanisms such as spalling, which is caused by induced high stress. To investigate this failure mechanism under high stress conditions, intact rock blocks with small size tunnel were tested at the Western Australian School of Mines (WASM). The range of rocks, such as sandstone and granite, were drilled (200 mm hole) and tested using a servo-controlled 450 t capacity INSTRON machine. The acoustic emission sensors were attached to the block mass during the experiment to investigate the seismic response prior to spalling failure. The effect of the ground support system towards the failure was also examined by comparing the seismic response of the various ground support schemes.CITATION:Kusui, A and Villaescusa, E, 2016. Seismic response prior to spalling failure in highly stressed underground tunnels, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 689–694 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By D Craw

Uplift of the antiformal ranges in Central Otago, New Zealand , has resulted in the progressive evolution of eluvial placer deposits in tectonic sediments on the range flanks and along their margins. The placers are derived from the reworking of fine-grained gold from the auriferous Manuherikia Group fluvial sediments which covered the basement prior to uplift of the ranges. Gold in the tectonic sediments at Matakanui shows a progressive increase in grainsize in successively younger sediments and nuggets in the youngest gravel sequence are up to two orders of magnitude larger than gold grains in the parent alluvial source. Most of the gold in the tectonic sediments is highly irregular in shape, commonly with delicate surface textures which could not have survived fluvial transport and are indicative of authigenic precipitation. Some coarse grains have been rounded by recycling, and further addition of authigenic gold has occurred. Placer gold values result from both physical and chemical enrichment during sedimentary recycling. Continued range uplift and back-thrusting of sediments on to the ranges results in recycling of earlier formed placer sediments. They also result in further enrichment of gold values through the incorporation of additional supplies of the parent alluvial source sediment The host sediments are widespread along the ranges and are not confined to sites of historic mining activity.

Jan 1, 1992

Aurum Reef Resources is a provincially owned unlisted public company which holds a number of prospecting licences over Otago hard rock historically active minesites. The Bullendale Licence 31 1845 was applied for in 1985, granted 1991, including a DoC special condition allowing re-opening of the historic workings. The underground workings were commenced in 1862 and up to the mine's closure in 1906 some 40 000 ounces were produced at an average grade of 15.5 g Au/t. The purpose of the summer 1991 work programme was to enter the workings in an attempt to observe and sample the mullock between the lodes operated by the early miners. This objective was achieved on the third attempt. Samples were taken and subsequently a contract geologist resampled the workings and prepared a report indicating the Bullendale lode zone to be generally mineralised. Mullock interlode and schist foot-wall consistently returned assays over 0.5 g/t.

Jan 1, 1992

By C Rizzardi, M Callahan, J Mahon

Henderson Operation’s underground molybdenum mine has been in production since 1976. Since that historic date, more than one billion pounds of moly has been produced, and over 120 Mt of ore extracted from three different levels and many different panels. The safe and successful operation of Henderson has been, and will continue to be, dependent on utilising an increasingly sophisticated fleet of equipment, advanced designs, innovative mining techniques, best practices in maintenance processes, improvements in crushing and conveying systems, and most importantly, the training and mentoring of the underground staff. These ‘professional mining technicians’ have been essential in the safe and efficient operation and maintenance of the underground mine and convey systems, and will drive the continuous improvements needed to keep Henderson competitive in the growing global market.CITATION:Callahan, M, Mahon, J and Rizzardi, C, 2016. Development of the professional mining technician – Henderson’s underground mine continuous improvement program, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 161–166 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By H Mali, B Kain-Bückner

Different types of lump iron ore-bearing particles were investigated in terms of their raw material properties depending on their behaviour during reduction. To predict the reduction behaviour different types of lump iron ore and pellet brands were characterised by their mineral abundance, texture and pore size. The image processing software VisuMet was developed to semi-automate the evaluation of photomicrographs from polished sections of lumpy iron particles. The results were compared to the standard reducibility test after ISO 4695. The evaluation of lump iron ores is based on the simulation of the transformation of the different iron minerals due to their sequence of reducibility. The progress of the reduction front is simulated and the result is a degradation curve. Pellets were also investigated due to their different pore size distribution. The results indicate that the pore size influences the reducibility in addition to mineral abundance. The evaluation with VisuMet of the lump iron ore and pellet samples correlates with the reducibility provided by the ISO 4695 test. The determination of the mineral abundance by VisuMet is comparable to common point counting with a correlation coefficient of 99.67 per cent.CITATION:Kain-Bückner, B and Mali, H, 2017. VisuMet – analyses of lumpy iron carriers with image processing, in Proceedings Iron Ore 2017, pp 557–560 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

The New Zealand Steel Ironsand Slurry Pipeline was successfully commissioned in February 1986. The project includes 18 km of high pressure, polyurethane lined buried pipe. McConnell Dowell Constructors Limited has developed a coupling which has allowed this pipeline to be fully welded. The design and development of the coupling and its application on this project is discussed.

Jan 1, 1986

By W E. Short

Ausmelt top submerged lance technology is at the cutting edge of technological developments in non-ferrous metal smelting with commercial operations throughout the world. The Technology is being used for lead smelting, copper smelting and matte converting, fuming zinc from slags, recycling iron residue from zinc plants, processing the aluminium industry hazardous waste SPL , precious metal processing, nickel-copper residue smelting and converting, and tin smelting. The Technology is also being developed for projects involving iron-making and waste industry opportunities. There are 19 furnaces operable or under design at the time of writing. The benefits to operators using Ausmelt Technology vary depending on application, but typically result from environmental improvements, enhanced recovery of valuable products, lower capital and operating costs, more flexible operations capable of handling a wide range of feed materials, better removal of impurities, or improved product quality. Growing industry acceptance of the Technology is evidenced by the fact that more than 20 per cent of the worldÆs tin production will be extracted in systems using Ausmelt Technology when the Yunnan Tin Corporation plant starts up in 2001. Metallurgists, industrialists and investors have accepted the Technology for improved operations in both greenfield main smelters and add-on plants in Korea, China, Japan, Germany, Peru, Zimbabwe, India, Namibia and Australia. Ausmelt intends that this paper will update the industry by outlining recent achievements of the Technology in global metallurgical operations.

Jan 1, 2000

By S McKnight, L Koroznikova, S Hall

Mineral sands represent an important new resource being developed in the Murray Basin, including parts of western Victoria. This paper will outline a simple methodology for mineral sands characterisation, developed as part of the AMIRA-managed project P777 æThe Development of Heavy Suspension Techniques for High Density Separations (Replacement of ClericiÆs Solution)Æ. This project is currently sponsored by three multinational mining companies (De Beers Consolidated Mines, Iluka Resources Limited and Rio Tinto Limited) and is developing an innovative laboratory mineral characterisation procedure that will allow the replacement of the currently employed highly-toxic chemicals.Mineral sand resources almost always contain more than one valuable (and relatively heavy) mineral. Titanium minerals are found with a large range of titanium contents, giving rise to density variation and often subjective mineralogical descriptions. Companies tend to rely on laboratory heavy liquid separation in the evaluation of samples arising from exploration, mining or metallurgical processes. Unfortunately, there are only a limited number of high density (æheavyÆ) liquids and these tend to be more toxic as their density increases. Low-toxicity inorganic solutions, based on tungsten compounds, have been developed that can be utilised at relative densities (RD) up to 3.0. However, beyond this value currently only organic liquids can be used. Diiodomethane (methylene iodide) having a relative density of 3.31 is commonly used; however, this presents significant health and safety hazards. Mixtures of thallium formate and thallium malonate were found in the early 1900s by Clerici to provide liquids having specific gravities between 4.0 and 5.0, hence æClericiÆs solutionÆ. For the characterisation of the heavy components of mineral sand deposits (eg anatase sg 3.9, rutile sg 4.2, ilmenite sg 4.4 û 4.7 and zircon sg 4.6 û 4.8) there is currently no heavy liquid alternative to ClericiÆs solution. ClericiÆs solution is highly toxic and testing is now conducted by very few laboratories worldwide with costs reflecting the chemical costs (though extensive efforts are made to recover and reuse the liquid, plus the requirement of its removal from the mineral samples), the infrastructure costs and health and safety regimes (eg blood testing of exposed staff, inventory management). A simple laboratory technique of density fractionation is being developed, employing suspensions of fine tungsten carbide particles in lithium heteropolytungstate (LST) solutions, that can replace ClericiÆs solution in the evaluation of fine mineral sands samples (eg -250+150 microns). The developing methodology that can achieve low-cost, low-toxic separations at relative densities above 5.0 will be outlined and the comparison of results with ClericiÆs solution presented.

Jan 1, 2006

By M P. Sandy, V Louchnikov, V Eremenko, M Orunesu, O Watson

"Surface support is a key component of most ground support systems which are applied as a means of reducing the risk of rockfall occurrence and maintaining serviceability of mine development. Surface support has two primary functions: distributing the applied load throughout the system by providing connection between rock bolts retaining smaller rocks that unravel between rock bolts.Confinement is also provided to the rock mass, which may increase its capacity to resist further degradation or loosening.Surface support has been routinely installed in most underground mines around the world for many years, yet the operators are still not always certain which type is best suited for deformable ground conditions. A number of factors need to be taken into consideration prior to selecting the type of surface support liner, such as its capacity, availability, practicality of installation, manual handling and loading conditions (static or dynamic) to ensure the system’s optimal performance in terms of safety and costs.This paper presents an overview of the surface support types currently used in underground mines in Australia. Shotcrete, weld mesh, high-tensile chainlink mesh, reinforced weld mesh and high energy absorption (HEA) mesh are discussed. A detailed description of each system is provided in terms of capacity, energy absorption, installation cycle and costs. The cost of each system has been normalised to the units of energy absorbed. The information presented in this paper can be used by underground operators as a reference guide when deciding on suitable surface support type for deformable ground conditions.CITATION:Louchnikov, V, Sandy, M P, Watson, O, Orunesu, M and Eremenko, V, 2014. An overview of surface rock support for deformable ground conditions, in Proceedings 12th AusIMM Underground Operators’ Conference 2014, pp 57–66 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 24, 2014

By P Mikula, R Geranmayeh, R Carlton, M Ferguson, R Whiting

The concept of using specially designed slot blasts to mine through stress abutments that intersect faults, while controlling fault-slip seismicity, has come of age at Mt Charlotte Mine. Due to the high and adverse stress field and the presence of major faults, the mine is vulnerable to significant fault-slip seismicity. As mining proceeded, advancing stress abutments around various mined areas encroached on several major subvertical faults. If the sequence formed a diminishing pillar between stope and fault, the removal or failure of that pillar daylighted the fault, and often resulted in significant fault-slip seismicity. A new strategy called ‘Tight Slot Blasting’ (TSB) was developed to restrain or dampen this style of fault-slip movement. The TSB has geometric similarities to a conventional cut-off slot used to create stress shadows, but its function is different. Its objective is to trigger and control a sudden shift of the stress state on a fault from an initial stable state, through an unstable transition, to a second stable state. A TSB firing advances a long tall narrow slot through a stressed abutment between a stope void and a nearby fault, using a rapid blast with a low swell ratio, so that the slot substantially and rapidly fills with blasted rock fragments. During the blast process, the stressed rock is rapidly removed and transformed into the fragmented rock fill in the slot. The strategy deliberately allows a fault-slip episode to manifest at a chosen time and place. The tight-packed broken rock in the slot performs an essential shock-absorbing function by controlling the slip amount and rate on the fault, while at the same time the fill becomes compacted by the movement. This controls the dissipation of fault-slip energy, and greatly reduces the seismic response in time and space. A small closure across the slot occurs, with consequent relaxation and destressing of the adjacent rock mass. Stress monitoring data shows that slot creation lowers the abutment stress in the nearby rock mass, while the newly placed fragmented rock fill acts as a shock absorber, providing considerable resistance to substantial fault-slip movement that otherwise could deliver a significant seismic event. First used in 2007, the strategy has been refined to become a routine specialised practice for management of seismically hazardous situations at Mt Charlotte, with 12 successful TSBs conducted to date. Despite mining through multiple high stress abutments, seismic reactions have not exceeded ML 2.1 with any TSB firing, all remaining below the site tolerable maximum of ML 2.3. This paper presents an overview of the strategy, and five case examples of the strategy in critical stressed areas in July 2016, Sept 2017, Dec 2017 and two in Oct 2020. The strategy has successfully managed the seismicity and is expected to remain an essential part of the seismic management plan at Mt Charlotte Mine.

Nov 29, 2022

By J T. Carswell, N A. Schofield

Fluctuations in periodic reconciliations between the mine and the mill are an expected and common experience in mining and processing operations. These fluctuations are caused in part by errors in the estimates of tonnage and grade of the mined material as well as errors in the millÆs assessment of the material processed. Keeping these errors small and unbiased is an important aspect of an efficient operation whose primary goal is to derive maximum benefit from the exploitation of the mineral resource.These fluctuations in periodic reconciliations can also mask subtle but economically important problems which may take years to identify and resolve. Such problems can result from a poorly-conceived model of the mineralisation which affects both the spatial distribution of the ore as well as the tonnage - grade distribution over the range of cut-off grades. Poorly conceived models of the mineral resources and ore distribution can arise as a result of insufficient and inadequate?drilling and sampling of the mineralisation, inappropriate?application of geological?constraints in the estimation process and the use of inappropriate methods to estimate the block grade distribution. This paper presents three case studies from gold and copper mining operations, two of which experienced significant problems with their mine to mill reconciliations over extended periods of time. For the gold mine in case study 1, sampling problems were ultimately considered to be the main cause of the poor reconciliations between grade control predictions and the mill which persisted over a period of 18 months. In addition, incorrect application of resource modelling methods contributed significantly to a mismatching of the mill capacity with the mine at the beginning of operations. For the underground copper mine in case study 2, a change in the approach taken to resource modelling brought marked improvements in ore definition and more accurate predictions of ore grade and better production forecasts.The third case study describes the background to the expansion of production to exploit a large tonnage of lower-grade stockwork mineralisation in an open pit gold mine. Several years of favourable Mine to Mill reconciliation data from the mining and processing of higher grade and lower grade stockwork styles of gold mineralisation provided the confidence in the approach to grade control to support the expansion plans during a period of low gold prices.The paper is intended to complement the discussion of mineral resource estimation methods and risks in Section 6.1.3 of the Mine ManagersÆ Handbook to be published by the Australasian Institute of Mining and Metallurgy (Schofield, 2012).CITATION:Schofield, N A, Moore, J and Carswell, J T, 2012. Mine to mill reconciliation - Three case studies, in Proceedings International Mine Management 2012, pp 161-172 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

By R Adofo

Underpinning the mining process is a continuum of prediction, specifically of tonnes, grade and recovery from exploration to grade control, through short-term mine design, to mining and processing. The interdependence of one activity on the other is so strong that it can be difficult to partition the activities and determine where there are issues, if any. Reconciliation is the process that compares the predictions of the various estimates to the actual product produced at the end of the production chain. Quite often, an attempt to understand the variances from one measuring point to the other creates a ‘wicked problem’.This study outlines the benefits of incorporating the principles of ‘systems thinking’ into the mining reconciliation process, by constructing a framework within which reconciliation is effectively managed. The philosophical base for any variances between successive links in the reconciliation chain cannot be attributed purely to the statistical variance between the predicted and the actual grades achieved, but should include the interrelationships between the technical and managerial professionals involved. Systems thinking, as an interdisciplinary approach, draws its ideas and concepts from a variety of disciplines, and in so doing can exploit their different strengths.The study described in this paper offers methodologies to analyse the task, in advance of developing a technical solution. Two systems thinking methodologies, Grounded Theory (GT) and Soft Systems Methodology (SSM) were employed. These methodologies, are geared towards dealing with relationships and interactions between individual parts and the whole. The GT coding in the study specified that the key activity that would drive the reconciliation process is through an effective reconciliation meeting, and the competencies of a ‘reconciliation team member’ This team member should be a good communicator and enjoy challenges, be open-minded and transparent, and have a broad perspective of the mining process and relationships across the different activities.CITATION:Adofo, R, 2017. A systemic approach to managing the Mine to Mill reconciliation process, in Proceedings Tenth International Mining Geology Conference 2017, pp 95–102 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By R Redden

"The Didipio Gold-Copper project in the Philippines has been a well-defined reasonably high gold grade porphyry for almost two decades. OceanaGold are now bringing the project into production in late 2012 and have recently reoptimised the project with the goal of combining the inherent high grades with higher through-put than previously proposed that will see strong initial metal production. The project was discovered and well defined by 1995, but has seen some obstacles to development, namely sovereign risk, capital cost and project funding. The project strengths over this time that have kept the flames alive are: strong grades large orebody with low stripping ratios a simple beneficiation process and a clean high-grade concentrate strong support from the Philippines government.The initial study in 1998 used Gold and Copper price assumptions of $325/oz and $0.95 lb respectively. Today reserves are based on $950 and $2.85. So, being a porphyry with a large reducing grade halo, the deposit now lends itself to extraction on a much larger scale than before, without any significant capital expenditure as a larger open pit now dominates the project.Didipio is a game changer for OceanaGold, so it has been important to learn from history and to capitalise on a strong initial metal production profile. The project sits in a reasonably remote mountainous area of Luzon which sees annual typhoons and numerous short duration high intensity rainfall events and two rivers flowing through the project area, so it has not been without some innovative technical solutions.CITATION:Redden, R, 2012. Didipio - Learning the lessons, adapting and getting ready for production, in Proceedings Project Evaluation 2012, pp 67-76 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

May 24, 2012

By A Teen

An open cast mine on the West Coast of the South Island of New Zealand proposes to remove up to 30 m of overburden to access an ore body neighbouring National Reserve land. Part of the conditions of the mining permit is that no material above natural discharge levels may be released over the Mining Lease boundary onto the adjacent land. In order to meet this requirement, the client has contracted the design and installation of over 2.6 km of high energy dynamic rockfall control barriers. This paper describes how the rockfall hazards were assessed and the rockfall barriers dimensioned. The design involved 2D modelling of over 3000 simulations.   Modelling parameters were calibrated during field trials at a purpose built section of barrier. The resultant energies ranged from 500 to 3000 kJ. The construction phase of the project involved the drilling, anchoring, and installation of certified barriers up to 7 m high in a remote and inhospitable climate with limited machinery access. By exploring best practice in this specialized field of engineering, a novel rockfall hazard mitigation solution was identified.

Jan 1, 2007

By J Lapwood, S Pal, M Pascoe

The devastating failure of Dam I at the Corrego do Feijao iron ore mine near Brumadinho in Brazil on 25th January 2019 left at least 270 people dead or missing. In the immediate aftermath of this event, many mining companies commenced reviews of their tailings and water storage facilities (T&WSFs), and Rio Tinto was no exception. Rio Tinto has an interest in over 250 T&WSFs across 47 sites in 13 countries as owner-operator, as managing JV partner, and through non-managed partnerships and other ownership arrangements; T&WSF experts from Rio Tinto’s Surface Mining Centre of Excellence visited the sites in order to complete Technical Risk Reviews of each facility. These reviews looked beyond the day-to-day operational aspects of T&WSF management, and the site’s compliance with local regulations and Rio Tinto’s internal D5 Standard – Management of tailings and water storage facilities, in order to provide a strategic, second line of assurance perspective. The reviews focused on design and construction; operational controls; risk control framework; and competencies and capabilities of personnel involved in the design, operation and closure of the facilities. Additional activities were carried out in parallel with these reviews, including the development of a consistent approach to dam break studies; the public disclosure of information on Rio Tinto’s tailings storage facilities and their management; and contribution to external programs such as the initiatives being co-ordinated by the International Committee on Mining and Metals. This paper provides an overview of the tailings and water storage assurance work undertaken by Rio Tinto’s Surface Mining Centre of Excellence Tailings Validation Taskforce to date; work that will continue to improve governance and assurance for all of Rio Tinto’s T&WSF.

Jul 1, 2021