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By J Player, R de Vries, E Villaescusa, H Saw, R Hassell

The use of cemented rock fill (CRF) for support of open stope walls has increased in the Australian underground mines operations over the last five years due in part to its low capital cost. In open stoping the exposed CRF masses require adequate strength and stiffness, in order to resist the forces and to limit the displacement associated with movements in the rock mass surrounding the excavations. The CRF material preparation often involves the use of large particles, either from crushed rock or from development mining waste sometimes up to 1 m in diameter. However, the use of waste rock, which has a poorly graded particle size distribution may not achieve the required minimum target strength due to segregation and large air voids within the fill mass. This paper describes the optimisation of CRF strength by either crushing the waste rock or the addition of sand to the mix. Both methods increase the level of fines in the mix design. Cylindrical samples having 400 mm diameter and 800 mm heights were prepared for uniaxial compressive strength (UCS) testing. The UCS test was determined using the Western Australian School of Mines (WASM) large-scale static test frame. The laboratory results were compared with a database of large-scale CRF strength mixed without sand from a number of mine sites around Australia. The comparison shows a significant strength development in the CRF mixing with addition of sand for a given cement percentage. Due to the higher strengths achieved by the addition of sand and the crushing of the waste material these CRF types require less cement to achieve the same strength. This has the potential to improve the overall economics of open stope mining due to less dilution of the exposed fill mass.CITATION:Saw, H, de Vries, R, Player, J, Hassell, R and Villaescusa, E, 2017. Optimisation of cemented rock fill strength for open stope support, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 85–90 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By A R. Gerson

Pyrite, chalcopyrite and mixed sulfide samples, with and without quartz (5 wt per cent S), were subjected to column leaching to mimic natural weathering (cyclic wetting and drying). The pH and SO4 2- concentration of the column effluent was measured over a period of 78 weeks. The pH of the pyrite-only containing column rapidly decreased and remained under pH 4 after 12 weeks of leaching. The pH calculated assuming a 2:1 ratio of H + generation and SO4 2- release was slightly lower than that measured. However, a reduced H + to SO4 2- ratio of 1:1 is predicted if the release of aqueous Fe 2+ is assumed rather than the formation of Fe(OH)3. The pH of all columns containing only chalcopyrite or a 1:1 mole ratio of chalcopyrite and pyrite remained at or above pH 5 for the duration of the leach even though significant SO4 2- was released. One column containing the same initial surface area of pyrite and chalcopyrite but only approximately 0.10 the mole fraction of S as chalcopyrite maintained a pH of greater than five for the first 56 weeks of leaching and showed sporadic acid production thereafter. It is well established that oxidation of chalcopyrite results in a surface layer of polysulfide material. It is the formation of polysulfide that neutralises the acid produced on S oxidation through to SO4 2-. Hence where polysulfide formation occurs extensively on chalcopyrite the resulting solution pH decrease will be less than that based on SO4 2- production. The oxidation rate of sulfide minerals increases with decreasing pH and hence acid formation via sulfide oxidation to SO4 2- causes the subsequent oxidation rate to increase. The addition of calcite (CaCO3)to a pyrite column not only neutralises the acid formed but also decreases the rate of release of sulfate to solution by a factor of approximately 30. This is also the case where chalcopyrite is present mixed with pyrite. The rate of release of sulfate from the mixed sulfide mineral columns (after the initial release of the sulfate already present) was between one-fifth and one-tenth that in the absence of chalcopyrite.

Jan 1, 2003

By A R. Bye

The mining industry is facing some key challenges that provide a compelling case for geometallurgy initiatives. Over the last 30 years, the average grade of Australian orebodies being mined has halved while the waste removed to access the minerals has more than doubled. In the last eight years, the industry’s energy consumption has increased 70 per cent while multi-factored productivity has fallen 24 per cent. The paper documents a broad range of industry case studies which demonstrate strategies for gaining value from geometallurgy.The mining industry constantly faces the key questions of how significant ore variability is on mine valuation and how would knowledge of the variability change the mining schedule, mine to mill design and operation. Using case studies the paper describes the methods used for incorporating mineral extraction attributes into orebody models and their technical integration into daily operation as well as mine planning optimisation. While pit optimisation from a fully attributed geometallurgical model highlights areas of opportunity and risk it is shown that during the scheduling phase of mine planning that significant value can be added. The benefits from these projects included reducing geotechnical and environmental risk, improving mine to mill performance, option analysis and quantified cash flow risk. There is growing acceptance within the minerals industry that ‘realistically assumed modifying factors’ defined by a competent person/s are not sufficient to mitigate the risk of funding mining ventures. Geometallurgy is moving away from factored ore reserves to data-rich block models providing reliable information for mining, metallurgical and environmental considerations.

Sep 5, 2011

By T Kojovic, S J. Windle, J Sullivan

"The Geometallurgical Mapping and Mine Modelling (GeM) comminution index (CI) was developed as part of the AMIRA P843 GeMIII project. Drill core geochemistry samples were passed through a Boyd Crusher with standardised settings and the resulting particle size distribution (PSD) was measured using sieves.Disadvantages of the original measurement were the relatively coarse crush size, requiring a second pass of crushing for geochemical sample preparation, and the limitation of throughput caused by the sieving step. At Antamina, the measurement has been modified to use a 2.2 mm crusher size setting, which permits a single pass. The PSD is measured using a Camsizer, an automated optical sizing instrument. The Camsizer sample is a +180 µm fraction, used to avoid passing too many fines through the instrument and slowing down the measurement. In the sieving step, the weights of the two fractions are recorded and subsequently used to normalise the distribution measured by the Camsizer. In this way, the throughput of the Camsizer can match that of the Boyd Crusher. The PSD data are therefore measured without penalising the throughput of the sample laboratory.The normalised PSD distributions are used to derive modified CI parameters, based on the slope and intercept of the breakage product size distribution, which are indirect measures of the material breakage hardness.Fifty samples were selected as a training set, each sample a composite of five or six individual assay intervals and each with its own measured CI. The average PSDs were calculated for the composites and used to calculate a composite CI. The intact half of the core, approximately 40 kg, was tested to measure the BWi, A*b and crushability. The results were used to develop predictive algorithms for these hardness parameters.A further 50 composites were chosen for lab testing, to serve as a blind test of the algorithms. The paper reports on the test results and the incorporation of the modified CI data and predicted hardness parameters into the Antamina block model.CITATION:Windle, S J, Kojovic, T and Sullivan, J, 2016. Use of a Modified Comminution Index to Predict Bond Work Index and SMC A*b at the Antamina Mine, Peru, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 153–160 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By G Collecutt, T O’Beirne, D Humphreys, J Greenwood

Much of our knowledge of the behaviour of underground coal dust explosions has been derived from less than full-scale experimental explosions in facilities as small as 0.25 m diameter pipes. Although a substantial body of research has been undertaken in larger galleries approaching the size of full-scale modern mine roadways, there are still questions regarding the scaling of results to full-sized roadways in modern coalmines. Questions also surround the issue of comparing or scaling results between smooth and rough walled galleries, round and rectangular galleries and galleries with differing wall thermal properties due to different materials of construction.This paper will examine the influence of gallery size, cross-section area and wall roughness and thermal properties upon the characteristics of a coal dust explosion. Data from past explosion research will be examined and assessed for its application to the problem along with theoretical considerations for these factors.Recommendations on the design and minimum appropriate size of explosion galleries for assessing the performance of explosion inerting strategies, passive and active explosion barrier performance and determination of appropriate pressure ratings for ventilation structures will be made.CITATION:Humphreys, D, Collecutt, G, Greenwood, J and O’Beirne, T, 2015. The impact of facility construction and scale on the characteristics of experimental coal dust explosions, in Proceedings The Australian Mine Ventilation Conference, pp 301–308 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

At Cliffs Natural Resources Ltd (CNR) crushing and shipping sample stations, precisions are estimated for the sampling, preparation and measurement stages of iron ore sampling in accordance with ISO 3085 (2002). In this Standard, gross duplicate samples are prepared at each of the three stages, yielding eight measurement assays. Appropriate calculations of the differences between assay pairs are then made to estimate precision of each stage of sampling. The International Standard for checking precision in iron ore sampling, ISO 3085 (2002) prescribes a method for identifying outliers that is ambiguous and possibly inappropriate. The procedure also makes an unnecessary implicit assumption, that the differences between assay pairs are normally distributed. The Anderson-Darling statistic is used to demonstrate that in some cases the assay pair differences have distributions significantly different from normal. When applied at CNR as specified, the Standard leads to precision estimates well below the expected values, thus overestimating the sampling method's capability and limiting the opportunity for real process improvement. This paper suggests an improved method of estimating sampling, preparation and measurement precision. A bootstrap procedure is used to estimate confidence limits for the calculated precision estimates. The proposed method would be suitable for testing blasthole precision. The discussion is supported by extensive simulation modelling of realistic data.

Mar 1, 2010

By M Saghaeian, V Sheikhzadeh, R Hejazi

Mining dilution is one of the most important factors affecting the economy of mining projects. Instead of quantifying dilution in mining studies, it is common to assume a general dilution such as 5 per cent for massive deposits. Dilution increases the operating costs in the plant by increasing the tonnage of material to be milled. It prolongs the mine life by reducing plant’s effective capacity. It also reduces the feed grade. In most cases, lower feed grade means lower plant recovery. Dilution also increases the cut-off grade, which in turn reduces the overall ore utilisation of a mine. In this study has been investigated applying pre-concentration by dry magnetic separation for decreasing of dilution impact on reserve estimation and open pit design in low-grade iron ore mine. Based on the preliminary open pit design and assumption 3 per cent as dilution factor, the mineable ore in life-of-mine (measured + indicated) has been estimated with Fe = 25 per cent, SiO2 = 49.7 per cent. Based on the experimental test work on the ore, by dry low intensity magnetic separation of dry HPGR product grinding circuit, it is possible to remove diluted waste material and liberated gangue before concentrate plant, so that around 34 per cent rejected and Fe grade increase from 25 per cent to 33 per cent and by weight recovery 66 per cent. The results of the test work showed that this methodology could decrease largely the impact of dilution in the feed to the plant. It also slightly effect on the reducing of dilution factor impact for open pit design and optimisation and leads to increase the mineable tonnage in the low-grade magnetite iron ore mine.

Aug 24, 2022

By I Halikia, T Lilis

Lead smelter slags, produced during the last century in quantities ofmillions of tonnes at Lavrion, Greece, have recently been used in theconstruction of Lavrion harbour. In order to evaluate the geochemicalstability of slags and assess their environmental impact on the aquatic environment, a detailed study on lead leachability under conditions that simulate subsea environments was carried out. Leaching experiments using magnesium chloride solutions under mild temperature conditions were conducted and the effect of main parameters on lead solubility was examined. Furthermore, kinetic analysis on the experimental results was performed. Based on the results, lead dissolution increases by increasing the reaction time, magnesium chloride concentration in the bulk solution and temperature, whereas it decreases by increasing the slags particle size. The reaction order was found to be approximately 0.5 at the initial extraction stages and the activation energy value from the Arrhenius plot was estimated to 29.8 KJ/mole. Diagnostic equations applied to all the experimental data reveal that lead dissolution is mainly controlled by diffusion through the ferrosilicate matrix of the slag particles, which is in accordance with the low activation energy value. The JanderÆs diffusion equation [1-(1-a)1/3]2=kt was proposed as the equation representing the reaction of lead dissolution from slags using magnesium chloride solutions.

Jan 1, 1999

By C E. Woolley, A Hosseini, J Foster

Northern Star’s Thunderbox Open Pit C-Zone cutback was designed to maximise extraction in a short life excavation; In fresh rock on the western wall this included 20 m to 30 m bench heights with 6.5 m to 10 m berm widths and a 90° pre-split angle. Rock mass quality in this area is generally fair to good, however, there are sections where the dominant foliation runs parallel with the designed pit wall, and more closely spaced, altered, foliation is present: these areas are difficult to predict and prone to failure. Stringent controls and monitoring were required in order to safely access below these areas, in particular the use of slope stability monitoring radar, Trigger Action Response Plans (TARPs), re-entry procedures, visual inspections, drone inspections and day-to-day personnel awareness of the hazard. Robust and comprehensively planned remediation was also required after two significant slope failure events where long reach equipment and rope access techniques were utilised to remediate the areas in question safely, but also in a timely manner, such that expected production targets were impacted as little as reasonably practicable. This combination of rigorous risk management and well planned remediation resulted in a successful and complete extraction of the C-Zone cutback with no impact to operational safety.

Jun 22, 2022

By D Gerrard, J Begelhole, J Gerber

The Iron Magnet deposit has been mined since 2007 when Arrium (then OneSteel) commissioned the magnetite concentrator to supply feed to the pelletising plant in Whyalla. The concentrate quality requirement for the customer required consistent product with minimal variability. In the early stages of operation, it was identified that the feed variability introduced significant changes in the concentrate quality, which was outside the acceptable customer limits.In 2011, a geometallurgical regression model was developed that allowed for the estimation of concentrate quality produced from the feed material. This was based on a laboratory-scale Davis Tube Recovery (DTR) test performed on the feed material. The objective of the project was to characterise the raw ore in the pit to allow for blending prior to crushing. By blending the feed to the concentrator, minimal concentrate quality variation within the plant was achieved. The orebody was divided into geometallurgical classes, called ore types, based on the mineral texture and magnetic mass recovery. Each geometallurgical class consisted of material with similar metallurgical performances. For each individual blast pattern, the ore was grouped into the geometallurgical classes and a composite sample was created. The composite sample was put through the laboratory-scale DTR test and the results were used to estimate the metallurgical performance of the material.The characterisation process and feed pile build methodology was applied in early 2013 and went through an optimisation and streamlining phase. Since the implementation of the geometallurgical characterisation process, the plant has seen a significant reduction in concentrate variability and measurable throughput gains. The characterisation process has also increased the amount of material that is now classified as ore.CITATION:Gerber, J, Gerrard, D and Begelhole, J, 2015. Geometallurgy of the South Middleback Ranges magnetite deposit – predicting plant performance from the pit, in Proceedings Iron Ore 2015, pp 555–560 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By Kato T, Eguchi M, Seino T, Itagaki K, Kimura T, Muto T, Shimizu T, Kobayashi T

Behaviour of minor elements in the dust collecting system connected with fluidized bed roaster for zinc concentrate was investigated by use of the bench scale experimental appara- tus. The dust collecting system was consisting of two dust chambers, hot electrostatic precip- itator, washing tower, mist electrostatic pre- cipitator, drying tower, absorption towers and potassium permanganate solution towers. Some volatile elements such as lead, cadmium and arsenic tend to concentrate in the fine calcine obtained in hot electrostatic precipitator especially in the case of the roasting with insufficient air supply. Special attention was paid to behaviour of mercury. In the roasting tests for plain zinc concentrate, it was considered that most mercury volatilizes at first as elemental vapour in the roaster, but with decrease in temperature of gas around a half of mercury forms compound, and both elemen- tal and compound forms of mercury were found in the gas stream. Elemental mercury is of course difficult to be trapped in the dust collecting system. To promote the compound formations, some additives for concentrate, such as selenium and halogens were effective, especially selenium of a few times equivalent to form HgSe repre- sented complete conversion of mercury from elemental to compound. To clarify the behaviour and removal mech- anism of mercury, various small scale laboratory tests were also carried out. It was confirmed that mercury sulfate formation is possible if temperature and flow rate are adjusted adequate- ly for gas stream consisting of 02-SO2-N2. To trap elemental mercury, various substances were tested, and excellent results were obtained with selenium. Satisfactory results were obtained with a selenium disc heated at 100 to 200¦C in a mercury containing gas stream. Also, applica- bility of scrubbing method with SeO2 solution was investigated, and the solution containing a few hundred ppm SeO2, 0.01 per cent additive and 6 per cent H2SO4 proved to be satisfactory.

Jan 1, 1980

By E Corpuz, J Weissman, S Winter, R Evans

The surface-to-inseam (SIS) directional drilling technique has been utilised at Oaky Creek Coal for more than a decade to predrain both the Oaky No 1 and Oaky North mining areas. The cumulative drilling program constitutes a total of 140 lateral and 200 vertical holes, and 405 km of lateral drilling.The use of SIS gas drainage has been successful with the following site-specific benefits being recognised:ability to drain German Creek seam gas contents to residual gas levels of new mining areas within an 18-month period from commencement of well productionstructural geological verification of the mine design well in advance of development mining occurring in an areaability to conduct successful predrainage of the overlying Aquila seam to reduce subsequent goaf emissions.Appropriate and up-to-date geological knowledge during the design and drilling process is a significant influence to achieving success. Vertical production wells need to be located in a position that is most effective to remove water from hole. The lateral hole should not include intersections with significant geological structure.SIS drilling provides continuous seam roof/floor data to help define seam geometry and locate geological hazards with high accuracy. In faulted ground and with variable seam gradients, SIS data can resolve geological ambiguities from seismic sections and enhance seam correlation that would otherwise be available only from discrete and closely-spaced infill vertical exploration drilling.Here, we review some examples of SIS configurations and practice to highlight key learnings in drilling long inseam holes (up to 1900 m per arm) ahead of development and mining. Aspects on prerequisites, evolution of network design, tolerances and drainage outcomes in a variety of geological situations are discussed as technical basis towards a viable and effective SIS drilling program.CITATION:Corpuz, E, Evans, R, Weissman, J and Winter, S, 2015. Surface-to-inseam (SIS) drilling at Oaky Creek coal mine – SIS design aspects and drilling environment, in Proceedings The Australian Mine Ventilation Conference, pp 93–104 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By G Nicholas, S Coward, J Vann, R Wolff, S Jackson, S Moayer, A Bye

"A new approach to mineral project evaluation is described called Scenario-Based Project Evaluation (SBPE). SBPE incorporates well established æscenario planningÆ and æscenario thinkingÆ approaches, which are used extensively in other industries,?most notably the?petroleum industry. While most scenario planning is qualitative and non-probabilistic, the approach described here includes both quantitative and qualitative aspects. SBPE is complementary to optimisation approaches and allows mining firms to build and operate projects that are more robust in the face of adverse changes as well as proactively respond and exploit the upside offered by a realistic assessment of variability. The approach has potential to improve project performance and decrease operational risk. It also has important applications for currently operating mines.Conventional evaluation of metalliferous mineral deposits uses estimates of metal grades and deleterious attributes in singular æorebody modelsÆ, usually 3D block models, which fail to capture two critical aspects that underpin the realised value of mining projects: the inherent uncertainty of the estimated attributes the spatial variability of attributes, at the scale of mining selection, which impact on downstream processing steps and fundamentally drive realised value. While singular models are appropriate for estimating block averages, conditional simulation (CS) models of the relevant attributes are needed to represent uncertainty and capture spatial variability. Any attributes that can be either built into CS models and/or modelled in the envisaged mining/processing steps, can be evaluated fully through to highly ægranularÆ (ie detailed and un-smoothed) cash flows. A complete view of SBPE relies on selected strategies being tested against plausible æscenariosÆ of factors external to the project and thus outside management control. æExternalitiesÆ captured in such scenarios include market prices, costs and taxes. Via SBPE, project managers may demonstrate that there is material value in preserving or purchasing options that provide future flexibility to respond to the changing externalities or changes in orebody performance. Such flexibility generally comes at a cost but is very difficult to value. It is argued that full value chain evaluation using SBPE can help to value these options for a mining company. A case study for a gold mine is presented.CITATION:Vann, J, Jackson, S, Bye, A, Coward, S, Moayer, S, Nicholas, G and Wolff, R, 2012. Scenario thinking - A powerful tool for strategic planning and evaluation of mining projects and operations, in Proceedings Project Evaluation 2012, pp 5-14 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

May 24, 2012

By M Orunesu Preiata

The Odysseus Project is part of the high-grade Cosmos Nickel Complex that lies 30 km north of Leinster. The Odysseus definitive feasibility study (DFS) was approved by the Western Areas’ board in October 2018. Early works commenced in January 2019 with rehabilitation of the existing underground infrastructure. In June 2022 Western Areas was acquired by IGO Ltd. The project is now well advanced to meet its target of first concentrate. The project included the construction of a haulage shaft. The design of the hoisting equipment and the shaft barrel evolved from the initial DFS design stage to the final execution, as the data were made available from the initial investigation to the data gathered during execution (although this did not change from its initial concept). The design philosophy for the haulage shaft incorporated, from the beginning a multidisciplinary approach with inputs from three main areas involved in such projects, namely excavation techniques, geotechnical assessments, and infrastructure construction. This interaction is a fundamental component for the success of such a critical project. In fact, each of these three areas influences each other in a cyclical manner, triggering a continuous review of the project inputs and outputs, while maintaining the original project goals: the design of an infrastructure able to deliver the desired throughput. The throughput dictates the infrastructure that needs to be built, which in turn controls the size of the shaft. The key assumption applied to this is that the rock mass can accommodate the excavation void, and the excavation technique with its tolerances and limits that ultimately need to be verified back with the initial assumptions used for the infrastructure design. The aim of the paper is to present a case study of the experience gained with the Odysseus hoisting shaft and to propose a possible logic path for similar projects elsewhere.

Mar 29, 2023

By A J. Moore

Blasting operations in open cut mines results in airblast, ground vibration and rock movement with the potential for wild flyrock. In some mines there is a trend towards blasting closer to established infrastructure as extraction boundaries alter with increased resource prices and changed economic circumstances. Mine infrastructure in close proximity to blasting has the potential to be damaged by ground vibration and wild flyrock especially. To provide guidance for the determination of appropriate buffer distances and blast specifications, this paper describes methodologies that may be used to determine the potential for damage to infrastructure by predicting:dynamic blast;near field ground vibration levels;dynamic blast strains induced in infrastructure by consideration of ground vibration,ground strain and response amplification;potential for damage by comparing induced strains with allowable working strainsfrom structure design codes and serviceability requirements; andflyrock throw distances based on models developed from flyrock investigations.This report demonstrates the use of strain prediction methodologies developed during Australian Coal Association Research Programme (ACARP) Project C14057 for infrastructure such as conveyor belts, transmission poles and towers, buildings and bridges.

Nov 8, 2011

By T Atchison

In-pit crushing and conveying (IPCC) systems have come under growing scrutiny as a perceived mitigation to fuel and equipment price fluctuations, labour shortages and the need to move everincreasing volumes of material. Individual vendors and delivery organisations are now offering a sometimes confusing array of systems, particularly for the dig and dump side operations.One system does not suit all operations. This paper seeks to document the factors that should be considered in assessing the suitability of different IPCC systems, with a focus on dig side equipment layouts in particular. These factors include the productivity of the systems, interactions with the drill/blast and bench operation sequence, the ease of relocation, flexibility to changes in the reserve, scalability and compatibility with other elements of the system.

Jul 11, 2011

By D Will

RedrossThe Redross orebody averages 1 m wide, has a strike of 50 - 350 m, dips at 55° and has a basalt footwall and an ultramafic hanging wall. The most successful and innovative aspects of mining Redross were:•ore development innovations, 90 per cent of development was split fired with a shanty back profile to enable larger and more productive equipment to be used and resulted in higher development grades, improved project payback time and improved ore recovery;•hand held stoping using a multiple level, bottom up ‘V’ shaped hand held stoping method that allowed mining on multiple levels with hand held productivities between 50 and 90 tonnes per shift;•the use of 1 m cement pillars and 7 m high crown pillars were used to create multiple mining areas that enabled high overall production rates from hand held mining this orebody; and•the use of vertical cement pillars to enable hand held mining of adjacent stopes without leaving ore pillars.MarinersThe Mariners orebody averages 3 m wide, has a strike length of 50 - 250 m and dips at 50° with a basalt footwall and poor ultramafic hanging wall. The most successful innovative ideas of re-opening Mariners were:•Dewatering the existing mine workings utilising ‘oilfield’ technology by installing a long submersible pump in on existing pump rising main. This enabled the mine to be dewatered at rates up to 100l/ sec and helped overcome the 45 to 55 L/s inflows.•Overcoming the technical problems associated with Mining N07 ore blocks which had severely deteriorated from being underwater for five years by using reverse firing techniques to improve extraction rates and reduce dilution.•Mass firing a large mining block in the N08 with minimal void space because of deteriorating ground conditions.•Use of a longhole version of the Redross hand held mining method to achieve 100 per cent extraction of the N09 higher grade lenses.

Mar 21, 2011

By J Hartnett, B Tarrant, A Rayner, D O’Toole, P Davies

Since 2009, the Northern Territory and Australian governments have been working under a national partnership arrangement to inform a rehabilitation plan for the former Rum Jungle uranium mine. Part of the rehabilitation strategy is to backfill a flooded former pit (Pit), which extends down to 100m below the current pit lake surface and was historically partially backfilled with uranium tailings. It is proposed to utilise the remaining pit volume below water level to sub-aqueously store Potentially Acid Forming (PAF-I) waste rock which currently occupies large stockpiles across the site. The rehabilitation design and planning process undertaken to develop a strategy commensurate to project objectives and construction constraints involved the establishment of key constraints derived from the analysis of historic data sources and preliminary design efforts. Tabled strategies were balanced against dependent project tasks and project objectives, especially surrounding minimising disturbance of highly contaminated materials within the Pit. Ideas were developed in conjunction with industry input and review of case histories to develop a remediation solution that is constructible within the project timeframe and constraints.

Jul 1, 2021

By A J. Daniels

Macraes Mine is a large-scale open-cut and underground gold mine located in Central Otago, on the South Island of New Zealand. This paper presents the role of geological mapping in the grade control process at Macraes Open Pit as a case study, and demonstrates how systematic geological mapping can add significant value to the mining cycle. Geological mapping has proved to be a valuable foundation for orebody interpretation and analysis.Practical applications and lessons learnt are summarised, including predictive control of the orebody, improvement of geotechnical modelling, and identification of further exploration targets.

Aug 22, 2011

In the latter half of 1973 a contract was given to Roberts-Holland Joint Venture for the stripping of the southern exhaust airway.The contract was carried out efficiently and relatively cheaply. It was completed 2 months ahead of schedule.The sinking stage and in particular the drilling jumbo proved to be a success and helped produce an above schedule stripping rate.No major problems were encountered with ground conditions or ventilation. A survey of the shaft showed the diameter to be within the set limits of 5·49 m ± 0·15 m.

Jan 1, 1974