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By G B. French

Post a serious heating event underground, and at the direction of the State Mining Safety Authority, a mining company needed to demonstrate the use of cutting-edge technology to mitigate future events. Yokogawa were contracted to provide a turnkey solution to help the mine achieve this objective. The solution was to use a fibre optic-based Heat Detector that will allow entry into and around the mine considering the potential volatility of the environment, also the need to redeploy as mining activities moved underground and more boreholes are added. Industrial strength fibre optic cable and a robust connector system was chosen to achieve this goal and give the customer the ability to send cable down boreholes of up to +1 km and continuously monitor the temperature ofunderground roadways. Being able to re-deploy the cables into different boreholes and link borehole temperature measurements gave insight into all areas on the mine. The machines deployed on-site were the Yokogawa DTSX1 heat detector incorporating the Ramen Backscatter principle. Being of a robust construction and a low power consumption device, it was easily included into the portable monitoring trailers designed by the customer and built locally.

Oct 12, 2022

The celebrations which took place in 1986 to mark South Australia's Jubilee 150 served to focus attention on all aspects of the State's heritage. Until that time the sites and relics of South Aus- tralia's early mines had been generally neglected. Marked by the ruins of enginehouses and littered with the remains of the massive technology of the Industrial Revolution, these sites have now been recognised as containing the threads of a fascinat- ing story. In the early days of settlement the economy of the Colony was based on land and farming. Droughts caused periods of economic depression which were alleviated by chance discoveries of gold, lead, silver, and copper ore. Some of the mines which were opened on the copper deposits were the largest in the world at that time and their names well-known throughout mining circles. Working by hand with primitive equipment, the early miners excavated vast networks of shafts and stopes often extending to great depths: at Moonta- Wallaroo Mines for example workings extended to 860 m below ground. Because of the presence of underground water, mining to these depths would not have been possible without the Cornish pumping engine. Operated by steam power these massive engines and their associated equipment were transported from Cornwall by clipper and delivered to the mines by bullock cart. At this time the engines were at the peak of their devel- opment and, although expensive to import and install, they were highly reliable: the engine oper- ating Hughes pump at Moonta worked continu- ously for sixty years without a major breakdown.

Jan 1, 1987

By B W. Atkinson, J Docherty

An Australian Working Group has been compiling a guide for operators to use in order to improve the efficacy of their routine and non-routine sampling tasks within their coal preparation process. The guide focuses on unit operations within the process, and not conveyor belts or transfer stations that are adequately covered by the existing Standard ISO 13909.Representative sampling of unit operations is generally an after-thought following plant construction, whether that be a result of oversight, or more commonly, capital cost minimisation during initial construction. Minimising capital cost by avoiding adequate sampling systems is generally a poor decision, since the result is a process that cannot be adequately measured, meaning that it cannot be adequately managed and optimised.The use of the term ‘guide’ rather than ‘standard’ is intentional. Practical means of sampling unit operations within existing plants generally relies on a compromise between sample representativity (minimisation of bias) and sampling feasibility. The guide does not endorse poor sampling practice, but instead offers practical guidance to overcome, to the extent reasonably possible, real-life limitations.When it comes to sampling any particular process, it is almost always necessary to make a professional judgement as to whether or not the proposed samples are likely to be sufficiently representative such that the sampling will be worthwhile. Such judgement needs to be exercised by personnel who understand the principles of sampling, as they apply to the stream being sampled. There are many circumstances where available methods for sampling of a particular stream will be meaningless, and in such circumstances analytical data from that sampling will only serve to propagate poor decision-making.This paper outlines the approach for the guide, the areas it covers and the approaches adopted for different types of unit operations and associated equipment configurations.CITATION:Atkinson, B W and Docherty, J, 2017. A practical guide to sampling in coal preparation plants, in Proceedings Eighth World Conference on Sampling and Blending , pp 241–246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By I M. Platten, Y Xie, B W. Cuffley, S C. Dominy

"Geometallurgical programs require the collection of representative samples for geochemical, mineralogical and metallurgical test work. Such protocols must be designed to suit the style of orebody in question. The distribution, proportion and size of gold particles have a direct impact on the effectiveness of sampling and test work protocols, and the gold recovery processes employed. Characterisation studies focusing on ore mineralogy, and gold particle deportment, size and distribution are required. High resolution X-ray computed tomography provides a non-destructive method for analysing the 3D nature of gold in rock samples. It can be used to calculate the modal abundance, particle size and distribution of gold in the sample volume. This paper presents a case study of the imaging of in situ gold particles in a high-grade gold ore. The Nick O’Time reef system comprises laminated quartz veins, which locally bear extreme grades of up to 100 oz/t gold. The mineralisation has previously been characterised from both a mineralogical and metallurgical perspective. Eight visible gold-bearing vein samples were scanned using X-ray microtomography. Microtomographic data were integrated with previous mineralogical and metallurgical test work outputs.CITATION:Dominy, S C, Platten, I M, Xie, Y, Cuffley, B W and O’Connor, L, 2016. Characterisation of Gold Ore from the Nick O’Time Shoot (Tarnagulla, Australia) Using High Resolution X-ray Computed Tomography, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 241–254 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By B Chapman, B Gaida, L Drowley

The 372 MW Ulu Jelai Hydroelectric Project is a peaking power scheme located in the Cameron Highlands, Malaysia. The main features of the project include an 84 m high roller compacted concrete dam; two weirs which divert flows from adjacent catchments via transfer tunnels into the main reservoir; an underground power waterway; and an underground power station complex comprising three large caverns with connecting tunnels approximately 240 m below surface level. The project includes approximately 25 km of tunnels excavated in fresh granite rock mass with some distinct shear zones of weaker material. The majority of the tunnels are being excavated using drill and blast, with the two transfer tunnels being excavated with a tunnel boring machine (TBM).This paper focuses on the design and construction of the Telanok underground power station complex and also some aspects of the design for the headrace tunnel. Topics covered include geological site investigations including in situ measurements of rock stresses; development of a geological model and parameters for rock support design; three-dimensional modelling to assess interactions between the caverns to optimise rock support; design of a rock anchored crane beam; construction of the caverns and design of the unlined headrace tunnel taking into account hydraulic jacking and operational pressure fluctuations.CITATION:Drowley, L, Gaida, B and Chapman, B, 2014. Design and construction of large caverns in granite – Ulu Jelai Hydroelectric Project, Malaysia, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 361–368 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

In spite of the efforts done in the past to implement in Codelco best practice guidelines and standards on several important sampling, assaying and variability issues, many people, particularly top managers and operators, are still not aware of the relevance of the use of the principles and practice of geostatistics, sampling theory, analytical chemistry and the understanding of processes variability from rock to cathodes. As a result, an important challenge for the sampling community is to find out the causes of this lack of awareness and to develop communication skills to influence the organisation, particularly the top management level. This situation is not affecting only Codelco; it is a common characteristic of the copper mining industry. The main cause is cultural. Judeo-Christian and occidental sciences are deterministic. This implies a disregard of process variation and the assumption that homogeneity is omnipresent. Another important aspect of the cultural challenge is education. Education is the most efficient way to transfer a system of ideas, traditions and practices. To implement proper courses of sampling theory and geostatistics and support to multidisciplinary education at universities, mining companies will improve teamwork between geologists, mining engineers, metallurgists and chemists. The improvements will imply a more sustainable and efficient mining business.

Mar 1, 2010

By C Buchanan

For a long time there has been a known relationship between the northern Heavy Mineral (HM) deposits of the Murray Basin to the extensive north east trending ridges in the area. These ridges have been a targeting tool for exploration and have uncovered some significant discoveries, some of which have turned into mining projects. Bemax’s Ginkgo and Snapper deposits are good examples of how the faulting helped create an economic deposit but also result in significant planning issues in the exploitation of these deposits. Material balance, induration and pyrite issues have been made easier to manage through good geological understanding of the deposits.

Aug 22, 2011

By S Coward, C Xu, P A. Dowd

"This paper provides an assessment of the current challenges in strategic mine planning and design and suggested approaches for addressing them. The specific challenges covered are: realistic quantification of downstream processes applied to orebody models to provide an integrated approach to mine design and optimisation modelling, estimation and simulation of geometallurgical variables and their integration into resource and reserve estimation and mine planning modelling, estimation and simulation of new variables for new forms of mining – deep mining, particularly block caving, and solution mining flexibility in planning and design to manage risk and minimise its impact information technology (IT) infrastructure and platforms for rapid online data collection, storage, access and processing.Most of these challenges require new types of data, variables, modelling and estimation methods. Foremost among the new types of variables and data are geometallurgical and dynamic rock mass characterisation variables. New types of data and data collection include rapid generation of very large amounts of online sensor data and the consequent need for rapid processing and modelling of these data.This paper outlines the challenges and strategies in each of these areas and uses examples of models and outputs to illustrate approaches and potential solutions.CITATION:Dowd, P A, Xu, C and Coward, S, 2014. Strategies for mine planning and design, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 41–50 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 24, 2014

By M J. Nugus

The structural models developed by exploration and mining geologists are most commonly concerned with the ‘main structures’ or key constituents that pertain to the associated mineralisation. To this end, it is recognised that the geological and exploration models, which are developed, are essentially ‘fit for task’ and the scale-related variances are not always realised at an early stage. In fact, in many cases anomalous intercepts along different trends and of variable apparent continuity have often been neglected as ‘back scatter’ and not important. Recognition of the importance of subordinate structures as mineralising hosts suggests that additional opportunities exist outside the primary and main structures. History shows that opportunities are often not realised where gold is hosted in orientations not parallel to the predominant trend of the schistosity, main fault or shear zone.Another reason for the importance of subordinate structures can be understood from their roles in a percolation network. Subordinate structures can access the large fluid fluxes provided by backbone elements, but, as dangling elements, they provide greater opportunities for gold precipitation mechanisms and hence may constitute essential parts of the resource. Therefore, the role, understanding and consideration of the smaller-scale and orthogonal structures should be considered during all facets of exploration, resource development, delineation and mining.

Aug 22, 2011

The incidence of colliery disasters has highlighted the need for more centralised and directed coal mining safety research in Queensland, with particular impetus from explosions at Box Flat in 1972, Kianga in 1975 and Moura No 4 in 1986. Inquiries which identified the likely causes recommended measures and, research and two outcomes have been the present Mines Safety Research Advisory Committee and The Safety in Mines Testing and Research Station at Redbank, near Brisbane, dealing with all mining problems, coal and metalliferous. Already, important research into ignition and explosion and other health and safety matters has been accomplished; the Station has become an accredited testing laboratory; and international recognition has been achieved. Now the advisory, testing and research arms are soundly in place to pursue preventive investigations and be ready to provide assistance in any emergencies.

Jan 1, 1991

By N Power, R Hassell, E Jones

Wiluna Mining Corporation are progressively re-entering the old Wiluna underground mining complex. The existing underground was abandoned in 2013 by previous owners and left to flood with water levels reaching above the East Pit portal and Happy Jack Pit portal and up to 300 m below surface in the Bulletin underground. Re-entering the mine commenced in 2017 with dewatering of the Bulletin decline. The underground development had been previously supported with friction bolts, with weld mesh in places. Until mid-2021 rehabilitation requirements were based on an external visual inspection of the installed ground support scheme. However, several incidents involving falls of ground due to corroded bolts have occurred during this time, showing that this approach was inadequate. The challenge the operation faced was should the entire decline be rehabilitated, the implication being not only a large rehabilitation cost but also the impact of severe delays to the mining schedule. The question was asked can the operation better understand the level of corrosion damage and potentially optimise rehabilitation requirements. A proposal to use a systematic approach to assess corrosion by environmental condition mapping, visual external corrosion assessment, and internal corrosion assessment via borehole camera inspections was provided and accepted by Wiluna Mining Corporation. The objective of this work was to produce a three-dimensional map showing the degree of corrosion on the reinforcement systems in the capital infrastructure, this would then be used to risk assess and prioritise rehabilitation requirements. This paper summarises the approach, methodology and results that provided the Wiluna mine planning team with information to enable planning of resources and budget to justify priorities of rehabilitation.

Nov 29, 2022

By S N SHEARD

The use of geophysics in mineral exploration in Australia, and overseas, has increased dramatically over this century. This paper shows that using simple equipment with clever interpretation that the foundations of modem geophysics were laid, using all the same principles. The plethora and diversity of mineral exploration geophysical techniques does not allow a full description of their evolution to be given in such a paper. To convey this evolution, however, the progress of two different geophysical methods, magnetics - a potential field (passive) method, and electromagnetics - an electrical (active) method, are described. Examples of magnetic survey data from the 1920s and more recent vehicle home and airborne surveys are given to show the increase in data quality through technological improvement. A set of four airborne electromagnetic data sets spanning three decades is used to indicate the improvement in electromagnetic techniques. It is argued, that considerable progress is still required in the electromagnetic field to increase its interpretability.

Jan 1, 1992

By P Odins

Traditionally, stratigraphic deposits have been represented by a large number of gridded surface and product analytical models, related to each other by naming convention. This approach, though suitable for structurally simple stratigraphic deposits, does not lend itself well to addressing the complex style of stratigraphic deposits which are becoming more prevalent. In addition, the sheer number of individual gridded models involved makes it very difficult to keep a consistent audit trail of the overall deposit model. Recently, a new enhanced block model structure known as Horizon Adaptive Rectangular Prism (HARP) models was introduced to address these issues. An HARP model is specifically designed to allow stratigraphic units to be represented with virtually no loss of structural integrity, by allowing the tops and bases of the individual HARP blocks to ‘bend’ in concert with the input surfaces. By bringing together the best of grid modelling, triangulation modelling, block modelling and grade estimation, the HARP model opens up many exciting new opportunities for the stratigraphic geologist or engineer to take their model further than was previously possible. Examples of improvements in modelling methodology using a HARP model include: the ability to represent complex normal, reverse and thrust faulting; the ability to store thousands of additional analytical, geotechnical or calculated variables in each individual block; advanced visualisation, manipulation and plotting capabilities; and the ability to calculate volumes and resources against complex, three-dimensional (3D) solid pit designs. Finally, several ‘real world’ scenarios, illustrating how this advancement in modelling technology can benefit a wide range of mining professionals are detailed. These examples demonstrate how productivity gains can be made in both long-term resource modelling and short-term ‘week by week’ geological modelling as an adjunct to mine planning.

Aug 22, 2011

By S Matos Camacho, K G. van den Boogaart, R Tolosana Delgado, U Mueller

"The precise formulation of a geometallurgical optimisation problem is by necessity a simplification of reality. It includes implicit choices such as data availability or mining block geometry. Additional data can be orebody data, production data or market data. Often these choices are predetermined by the software, the workflow or the corporate culture, and as such are not even queried. There are several aspects that might play a role in the optimisation. They include not only the spatial model on which the selection of mining blocks and the potential mining sequence are based, but also the complexity of the processing model, the way in which uncertainty is treated, the scope of responsibility and the complexity of the model. In addition the timing of the optimisation and the availability (or lack thereof) of information will influence the outcome of any optimisation.We show that different modelling choices and different model formulations for the same mine can lead to very different processing choices, substantially different net present values (NPV), opposite investment decisions and so to overall different values for the entire operation. The selection of adequate simplifications and corresponding formulations for the optimisation problem is thus an important task in itself.For this purpose we introduce a method for quantifying the impact of certain simplifications prior to the optimisation. For example, the effect of mining block choices depends mainly on the spatial structure and the structure of the processing gain function. Both can be quantified beforehand. Based on the outcome, appropriate simplifications can be selected for the geometallurgical optimisation.CITATION:van den Boogaart, K G, Tolosana Delgado, R, Mueller, U and Matos Camacho, S, 2016. How Details of the Geometallurgical Optimisation Influence Overall Value, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 303–312 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By D Woolmer

Since January 2019, BHP Olympic Dam have been trialling the use of a drone based LiDAR mapping system for the purpose for surveying stope voids. This new technology utilises Simultaneous Location and Mapping (SLAM) algorithm providing positioning, stability and collision avoidance in GPS denied environments. Implementation of this system utilised underground personnel trained in the equipment’s use. The study’s intention was to evaluate the effectiveness of this equipment versus traditional surveying methods in regards to quality, safety and productivity. The trial results showed a marked improvement in the quality, productivity and personnel safety when conducting surveys. The use of the drone and LiDAR system reduced personnel and equipment requirements for surveys, thus allowing these resources to be deployed elsewhere. The technology’s simple and rapid deployment allowed multiple surveys to be conducted during a 12 hour shift, including ad-hoc work with minimal disruption to underground operations. After the drone’s initial trial, further work was conducted to utilise the Hovermap LiDAR scanner on other platforms to increase utilisation. A mounting system was created allowing the LiDAR to be mounted on a remotely operated loader or vehicle. This enabled drawpoint scans to be taken directly after production completion, resulting in faster stope close outs and drive scans for convergence monitoring. Implementation of the LiDAR system has resulted in improvements in the stope production cycle by reducing delays previously associated with data capture. The increase in the volume and quality of data has also allowed in-depth back-analysis of stopes in new mining areas to be conducted, which have driven improvements in the design process.

Mar 15, 2021

By A F. Cropp, D J. Bradshaw, W R. Goodall

Mineralogy and critically the texture of both the ore and gangue phases are of paramount importance in the flotation recovery of copper from porphyry ores. Mineralogy and texture will define the theoretical grade recovery curve for a feed ore. Actual grade-recovery falling below this may be due to texture and gangue influences, whilst desired grade-recovery above this line will not be possible unless the characteristics of the feed are altered.This review discusses examples of porphyry copper deposits where process mineralogy has been used to characterise these textural and gangue influences on recovery by flotation. More specifically, the influence exerted by grain size, liberation, association and elemental distribution is explored. The implications of these on overall plant philosophy and operation are highlighted, along with the subsequent potential impact on recovery.CITATION:Cropp, A F, Goodall, W R and Bradshaw, D J, 2013. The influence of textural variation and gangue mineralogy on recovery of copper by flotation from porphyry ore - a review, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 279-292 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By M Rauer

With a worldwide growing population the demand for higher living standards, food and the development of new technology is rapidly rising. To allow for a continuous growth, larger quantities of minerals and raw materials are needed at a faster pace. Different methods have been developed to access or tap ore more quickly, such as improved drill and blast operations, mechanical mining methods using equipment such as roadheaders (RH), longwall miners and other technical equipment. Another possibility to access and develop mines faster is the use of a tunnel boring machine (TBM).The historical usage of TBMs is surprisingly long, but the opportunity for technology adoption by the majority of worldwide mining companies remains largely untapped. Dozens of full face TBMs have been used by mines around the world, including two that will begin operation soon in Australia. TBMs have been used to safely and rapidly gain access to the orebody, or to expand access to the orebody to increase output by running a TBM along the edge of the orebody for several kilometres. These machines have also been used for ventilation and for conveyor tunnels for ore removal. They have been used to quickly excavate long and winding declines giving access to an orebody at several levels in a short period of time.Tunnel boring technology can be used for mine declines, mine access tunnels and all sorts of different mine designs and set-ups. TBM technology simply needs to be adapted to the mine conditions and, if manufacturers are involved early on in the planning process for mine development, the operation can be very successful. In some cases, historically typical mine designs may need to be re-thought.One mine, the Stillwater Platinum mine in Nye, Montana, is currently employing its fourth TBM in 25 years. Two were used to create tunnels running alongside the orebody, rapidly expanding access to the orebody in many locations for increased output. Two were used to create parallel access tunnels to a mine expansion at the East Boulder orebody; one tunnel is for conveyor haulage and the other for vehicular access. TBMs have been employed successfully many times to rapidly drive vehicular decline tunnels to multiple mine levels, such as at the San Manuel – Magma Copper mine in the USA. While TBM technology may not seem to be optimal for every mine, these success stories show that the method can provide vast benefits for the right projects.Early use of TBMs in extremely hard rock metal mines, in the 1960s and 1970s, had limited success since performance was low. However there have been great improvements made over the years in the strength of rock which can be excavated by TBMs with high performance. Other important improvements involve the provision of a safe work environment, safely and rapidly supporting the rock and predicting geology ahead of the TBM.This paper will briefly note the more than 20 TBM mining projects and highlight some notable successes. It will then go on to give a status report on the two active TBM mining projects in Australia and the difference between a TBM operation versus other excavation methods such as drill and blast (D&B) or RH excavation.CITATION:Rauer, M, 2014. Tunnel boring machines in mines – a?brief review of past use with a status report on use today in Australia, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 663–670 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

Over the last ten years geological and mining software products have evolved greatly. Software companies developing such products have focussed almost exclusively on the development of technical aspects of the applications, addressing geological, ore reserve estimation and mine planning problems. These specialist applications, and the many other new technologies that are being developed by a myriad of niche developers, are an essential part of todayÆs hi-tech mining operations. Technology is also being used in many other areas to improve the mining process and there is no doubt that tremendous advances are being made in all these fields. Yet there is something missing. The manner in which the technologies are used and implemented has led to the creation of many independent and inefficient æislands of technologyÆ where a variety of products from different vendors are used to address different, but related problems. Problems occur with unreliable information, data duplication, data redundancy and transferring data between applications that may be incompatible or even run on different computer platforms. These problems impede the flow and availability of information and hamper day-to-day decision-making by mine management. A solution to this problem is to take a holistic view of all the various technical applications and incorporate them into a single information technology solution. This solution must encompass all of the information requirements of a mining operation and must provide facilities that address much of the modern thinking about mine management, including strategic mine planning, value management, key performance indicators, and maintenance of a mineral balance sheet. Gemcom is developing an Integrated Resource Asset Management System (IRAMS), which is an enterprise-wide integrated computer system that encompasses various applications typically found at a mining operation. The core component of the system is a common, open, industry standard database that can be shared by many users from each of the different departments at a mine. Around that central repository are the primary applications that provide the mine with information it needs to operate. Ensuring that the information is reliable, accurate, shareable, timely and consistent will eliminate many inefficiencies, and provide significant benefits to mining companies. In turn these benefits will lead to significant improvements in decision-making, productivity and profitability for the operation. The initial version of the IRAMS system is currently being implemented at the De Beers Venetia Mine in South Africa. The system is being built around a core repository using the Microsoft æBack OfficeÆ architecture, and incorporates key technical applications from Gemcom, Whittle, De Beers Technical Team, Wenco and JKTech. The benefits of enterprise-wide systems have long been recognised in the commercial arena and enterprise resource planning (ERP) systems such as SAP, JD Edwards and MIMS are becoming commonplace in the mining industry. The more forward looking software developers and mining companies realise the need for efficient management of the information gathered during the mining process and can see that the concepts used in ERP systems apply equally to the technical applications as they did to commercial applications. The use of IT in the mining industry has expanded tremendously over the last five years as enabling technology and management acceptance has become more prevalent, and there is considerable room for dramatic growth over the next five years. The evolution of geological and mining software has now reached the stage where mines will yield the greatest returns by integrating the applications used in each area of their operations.

Jan 1, 1999

By N TassT, J Cyr

At the East Sullivan site, wood wastes covering the abandoned mine tailings impoundment prevent sulfide oxidation by creating an anoxic environment. The addition of coarse ligneous wastes and their high permeability favour infiltration, resulting in a water table rise that maintains most tailings under water saturation and thus provides an additional protection against sulfide oxidation. Moreover, high infiltration allows a more rapid flushing of acid prone groundwater generated prior to the cover placement, which could cause acid mine drainage over a long period of time. Finally, the pore-waters under the cover are characterised by a strong reducing potential, high alkalinity, and near neutral pHs. These conditions favour sulfate reduction and base metal precipitation as sulfides and as carbonates. Pore-water composition monitored from 1992 to 1998 showed a significant Fe2+ decrease, following cover placement. Thereafter, the restoration strategy capitalised on the alkaline and reductive properties of the waters underlying the wood-waste cover. An original treatment of acid effluents, based on the recirculation of water discharging around the impoundment through the organic cover, was implemented. In 2002, the recirculated water from May to October had a mean pumping rate of 240 m3/h, for a total volume of 800 000 m3. Data gathered near the dispersal zone from 2000 to 2002 show that despite the recirculation of acid water (pH ÿ3), the pH decreases by only one unit from 7 to 6, during the recirculation period, ie from May to November. However, alkalinity decreases from 800 to 100 mg/L-CaCO3. Despite this decrease, the alkalinity is back up to 800 mg/L-CaCO3 the following May, thanks to sulfate reduction. From 2000 to 2002, Fe2+ concentration in the pore waters near the dispersal zone is maintained below 2 mg/L. Evolution of surface water quality suggests that the contaminated groundwater flush is completed in the north and north-west area of the impoundment; the east sector is under recovery, while the south sector remains the most problematic. A wood-waste cover, besides limiting sulfide oxidation, can fill the role of alkaline reducing barrier for the treatment of these acidogenic waters, until a balance between acidity and alkalinity in the effluent is reached.

Jan 1, 2003

By E Philippa, B Miller

Material characterisation, ore sequencing and process capability are commonly regarded as the key parameters to consider in designing and operating an effective pit to plant supply chain. Therefore, an understanding of rock mass properties is the starting point for controlling the presentation of problematic material to the ore handling plant and optimising process utilisation. There are different methodologies for characterising problematic material and ore handleability which exist across a spectrum of sophistication. At one end of this spectrum are simple indices built using first principles geology and at the other are complex algorithms developed using advanced analytical methods, machine learning and ore traceability. Regardless of the method, without an integrated process for careful management of problematic ore, material handling delays (ie blocked, bridged, blinded and buried events) will interrupt the stable flow of production. The ability of the ore control geologist to mitigate these delays is central to the ore handleability challenge. This paper describes a quick and easy solution that links the presentation of ore to the operating window at the crusher. This operating window is based on material characterisation, using the physical, textural and mechanical properties of the rock mass, and crusher performance. It also describes how a basic problematic ore index (POI) can be developed using ore tracking to the production face, petrographic studies of ore texture and mineralogy, and existing variables in the geological model. Finally, this paper will demonstrate that by coding the POI into the geological model for mine planning, together with performance monitoring through compliance to plan routines, material handling delays at the crusher can be reduced, unlocking significant resource value.

Mar 22, 2022