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By R Dimitrakopoulos, R Goodfellow

One of the primary objectives when optimising a mining complex is to maximise its value for the primary stakeholders. In order to achieve this objective, it is necessary to holistically optimise all aspects of the mining complex, including decisions of when to extract materials from the available sources, how to blend or stockpile these materials and how to best use the available processing streams to satisfy customer demand. Existing methods for global, or holistic, optimisation ignore the compounded effects that risk has on the performance of a mining complex. Over the past decade, several stochastic optimisation approaches have been proposed to integrate various forms of uncertainty into the open pit mine design and production scheduling. These methods, however, are limited in their ability to simultaneously optimise the production schedules for the portfolio of mines, material destination policies, the use of the available processing streams and the various products that are produced at each location of the mining complex.This paper aims to discuss a new method for the global optimisation of open pit mining complexes with geological uncertainty. The proposed generalised methodology is capable of modelling and holistically optimising mining complexes, including aspects related to production scheduling, blending, stockpiling and non-linear interactions that often occur in practice, but are over-simplified in existing models. Two case studies are discussed to highlight the need for these complex, stochastic optimisers. First, a case study for a nickel laterite blending operation highlights the need to integrate geological uncertainty into the optimisation in order to ensure product quality constraints are respected. Second, a case study for a copper-gold mining complex highlights the added value when simultaneously optimising the production schedule and the stockpiling and treatment of extracted materials.CITATION:Goodfellow, R and Dimitrakopoulos, R, 2014. Stochastic optimisation of mineral value chains – developments and applications for the global optimisation of mining complexes with uncertainty, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 13–22 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By A Clarkson

Cannington Mine is an underground silver lead zinc operation located in north-west Queensland which has been in production since 1997. Ore is primarily moved through an underground material handling system comprised of a crusher, conveyor and hoisting shaft. The Fowler Shaft was constructed in 1997 using a strip and line method with the intent for it to provide a means to hoist ore from the loading station 600 m below surface. The shaft also serves as the route of key services including high voltage power, mine dewatering and fresh air. Despite the adherence to a mining exclusion zone, large-scale change in geotechnical conditions around the shaft were first observed in 2015. Ongoing ground movement around the shaft lead to cracking and delamination of the concrete liner. Shaft management required the on-site team to measure deformation rates and magnitudes, forecast change, manage rockfall risk and deforming pipework, and ultimately, hoisting skip clearance. Monitoring techniques to observe and measure deformation were required to evolve with the magnitude of movement. Some techniques leveraged off modern technology while some of the most useful techniques were based on logic and first principles. All shaft deformation management strategies relied on the co-operation and alignment between Cannington’s Infrastructure Maintenance, Survey and Geotechnical Departments.

Mar 29, 2023

This paper presents a rationale for selecting appropriate support elements which combine to form a support system to maintain stability in mines subjected to both strainburst and the shaking that occurs from fault slip. The overall approach was developed during the 'case for safety' study undertaken to allow the then Beaconsfield Gold mine (now Tasmania mine) to resume development and production after the 25 April 2006 ground-fall and fatality that received worldwide publicity. Issues of the sometimes competing requirements of support element performance during dynamic loading are discussed and the need for support flexibility is contrasted with the usual high support element stiffness required when these are used to reinforce rock masses. An example is presented to show the steps and technical details required to design each component of a support system to counter the de-stabilising effects of seismicity.

Nov 25, 2010

The Ernest Henry Mine is an open pit copper-gold mining operation located in north-west Queensland, Australia. It is owned and operated by Xstrata Copper with a current concentrator throughput of approximately ten million tonnes per annum. The pit will cease mining towards the end of 2010. Extensive surface diamond drilling has confirmed an extension of the orebody to depths of 1000 m below surface. A prefeasibility study was commissioned in late 2006 to investigate underground mining options with the preferred mining method being an inclined sublevel cave. In February 2008 mining of a decline commenced in conjunction with a feasibility study to further investigate the project. Work from the prefeasibility study indicates that an underground crusher, conveyor and hoisting shaft could be utilised to crush and transport broken ore from the sublevel cave workings to the concentrator. The study suggests that a production rate of five million tonnes per annum could be achieved and sustained for up to ten years. Ventilation designs and requirements will form a large section of the feasibility study. This paper will detail investigations of preliminary ventilation network designs of the proposed sublevel cave. Work has been completed using both Ventsim and VumA ventilation simulation packages. Ventsim was used to provide preliminary estimations and suggest alternatives for: surface fan duties;airflow characteristics (direction, velocity, pressure and quantity); andventilation network design in key mine areas. With mining activities reaching depths in excess of 1000 m below surface an analysis of heat conditions should be conducted. The VumA software package was used to model the thermal properties of the ventilation system. This model will provide a basis for the preliminary decisions on refrigeration requirements for the mine.

Jan 1, 2008

By F Hungerford, T Ren

"Gas management has always been a major concern for the ventilation officer of any gassy mine. With an increase of mining depth and gas content, there is a great demand for the development of in-seam drilling sites where boreholes can be drilled for the pre-drainage of gas prior to longwall operation. The ventilation and gas management in the drilling site therefore becomes a critical component of mine safety. In this study, advanced computational fluid dynamics technology was adopted to investigate the aerodynamics of gas emitting from the drilling site and boreholes during normal drilling and, in the case of a sudden gas inrush, from the borehole. In addition, the impact of different ventilation controls on gas removal in the drilling site was investigated. Modelling results indicate that gas accumulation zones could be formed if the ventilation system fails to deliver sufficient airflow to the drill site, especially when a sudden gas inrush from a borehole occurs. The configurations of brattice, layout of ventilation tubes and the gas emission rate all have a significant effect on the gas distribution. Due to variations in site-specific conditions, it would be desirable to conduct modelling studies to assess the effects and efficiencies of a ventilation design for the varying environment on-site before carrying out drilling practice. CITATION: Ren, T, Hungerford, F and Wang, Z, 2015. Computational modelling studies of ventilation management for underground in-seam drilling sites, in Proceedings The Australian Mine Ventilation Conference, pp 239–250 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 31, 2015

By M G. Wansbone, R Bhargava

The inferred ground conditions for the proposed mined cross passages at the northern end of the Waterview Connection tunnels consist of an overburden of alluvial and residual soils, with mixed face geology of highly weathered to unweathered extremely weak rock. This paper describes three-dimensional (3D) finite difference analyses undertaken to evaluate the stability of the cross passage headings and to validate the proposed sequence of excavation. The analyses undertaken incorporated the influence of the construction of the mainline tunnels and the breakout opening in the segmental lining for construction of cross passages.The stability analyses were carried out using FLAC3D™, version 4.0 (by Itasca Consulting Group) by progressive reduction of shear strength parameters to obtain a failure condition and estimate a factor of safety. For each step of strength reduction, corresponding increments of displacements of several points on heading faces were monitored. The stability obtained from numerical analyses was compared with analytical solutions. Interpretation of results of drained analyses indicated instability of the upper 2 m of heading face within the highly weathered rock mass. Additional analyses were undertaken by including grouted fibreglass dowels to reinforce the heading face. The results of the additional analyses showed significant reduction in displacements and yielding of ground around the face. The proposed temporary support comprised face reinforcement using grouted fibreglass dowels in conjunction with canopy tubes and perimeter support of steel fibre reinforced shotcrete. The stability of the construction sequence, which was related to the specific requirement of the proposed excavation equipment, was validated.CITATION:Wansbone, M G and Bhargava, R, 2014. Analysis of stability and design of face support for cross passages – Waterview Connection tunnels, Auckland, New?Zealand, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 339–344 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By I Gray

This paper examines the effects of the changes in stress that a coal may undergo as part of the drainage process. As a consequence of this, some coal seams will come to the situation that they have zero horizontal stress existing within them at the time of mining. The hypothesis of this paper is that this lack of horizontal confining stress means that on mining, the vertical stresses may be easily raised to a level where failure occurs. This failure may be accompanied by significant energy release from energy stored within the coal as well as that coming from the roof and floor. To determine the state of stress within the coal seam, the concept of the effective stress path that the coal passes through is examined and is found to be very dependent on the shrinkage of the coal with degassing, the Young’s modulus of the coal and its Poisson’s ratio. The Young’s modulus of the coal is important and has been found to be highly dependent on the state of stress within the coal. It may change by more than an order of magnitude.CITATION:Gray, I, 2014. The consequences for pillar stability of zero confining stress brought about by forced or natural drainage, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 331–336 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

With the burgeoning opportunities for new gold mines to be developed the opportunity now exists for a reassessment of the optimal processing path for these gold ores. Projects have traditionally followed the path of whole ore cyanidation with either Carbon In Pulp (CIP), Carbon In Leach (CIL) or Merrill Crowe. The challenge ahead is whether these traditional processing methods are the best option for stakeholders, or to go beyond CIP and use a combination of currently available technologies that can be used to provide gold recovery at a significantly reduced capital cost and minimal deleterious impact on the environment. Either stand alone or combinations of gravity concentration and flotation, can produce a gold bearing concentrate that can then be fed directly to a batch or continuous intensive cyanidation unit. Treatment of a gravity/flotation concentrate by intensive cyanidation may be processed by the InLine Leach Reactor (ILR) developed by Gekko Systems of Australia. The advantages of the technology combining gravity/flotation followed by intensive cyanidation are significantly reduced capital costs; improved safety due to reduced cyanide inventories; the majority of tailings un-contaminated by cyanide; less energy required due to an opportunity for an increase in grind size û reducing green house gas emissions; detoxification of concentrate tailings can minimise tailings disposal and containment requirements.

Jan 1, 2004

By S Wainio, P J. Beckett, T Miller

Lichens are a symbiosis of fungi and algae. Air borne elements and gases are absorbed very efficiently over the entire surface of the lichen, because they have no protective structures such as a waxy cuticle or stomata. A survey in 1977 (one year before the Sudbury Regreening program began), indicated that several Cladonia spp had invaded the soil in Sudbury’s open birch woodlands. Pollution sensitive species such as Cladonia rangiferina and C. mitis occurred 20–25 km from the smelters. It was anticipated that the improvements in air quality and reclamation efforts would allow a natural invasion of pollution sensitive species into what once was a lichen desert that surrounded the smelters. The purpose of this project was to study the invasion of terricolous (soil-inhabiting) communities of lichens and mosses on reclaimed land in the Sudbury region 45 years after commencement of the Sudbury Regreening Program.

Aug 2, 2023

Response of a mineral to anionic and cationic flotation reagentsvaries with the nature of the mineral and the particle size. A ruleis deduced for the selection of the correct type of reagent, which leads to a simple method of testing ores to determine the possibility of separating the constituents by flotation.

Jan 1, 1963

By T Laing, M A. Abdalla, P Hagan

Open pit operators are facing a number of challenges in the area of blasting and blasting processes, such as wall control, quality of fragmentation, explosives consumption and vibration. Remaining financially viable is one of the most significant objectives for mining professionals as they work through the blasting challenges within the mining chain of processes. This objective is such a significant challenge, primarily due to the high consumption of materials and the direct consequences on the downstream processes in the mining work flow, including loading, hauling, crushing, milling and mineral concentration. This paper reviews and discusses a technique to achieve this objective, namely air-decking. The performance in a number of mines around the world is reviewed focusing on the economic contributions of air-deck blasting. Various scenarios are investigated and simulated, covering both conventional and air-deck blasting, using JKSimblast software. The scenarios explore a range of issues and found that optimum results could be achieved with a minimum amount of explosives. The results obtained from the simulations were verified with blasts at Rixs Creek Coal Mine, Australia. Based on the verification results the simulations were then modified to more accurately model the actual conditions and parameters on site and to ensure that the models derived meet the production and control requirements at the mine site. Ultimately, overall analysis and comparisons were applied to the outcomes of the conventional and air-decking blasts revealing a reduction in material consumption of around 25 per cent with consequential savings and up to a 30 per cent reduction in ground vibration.CITATION:Abdalla, M A, Laing, T and Hagan, P, 2012. The contribution of air-deck blasting to open pit mining economics, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 7-12 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By M Hassall

There is a plethora of activities that have been, and continue to be, performed to improve the health, safety and well-being of workers involved in resource industry activities. These activities include implementation of risk management systems, performing risk assessments, constructing bow-ties, implementing critical control management systems, undertaking personal, process and functional safety initiatives, implementing psychological and physical health as well as industrial hygiene programs. Despite the significant work that has occurred over the last several decades, unacceptable levels of fatalities, injuries and illnesses continue to persist as evidenced by Safe Work Australia statistics.

Apr 16, 2024

By A L. Bennett

It is well understood that designers and constructors must protect the existing surroundings of tunnel construction, particularly in the selection of excavation methods, ground support and waterproofing systems. However, while this can readily address the existing conditions, the tunnel owner and the designers need to consider the changes that are likely to occur during the life of the tunnel. It is typical for transport infrastructure to have a design life of at least a century. While the effects of constructing the tunnel on its surroundings are a short-term effect, the converse case, the protection of the tunnel, and the need to maintain its integrity, will affect developments over and adjacent to the tunnels beyond the foreseeable future. Decisions made during the design phase have the potential either to facilitate development or to hinder it for the long term.Examples principally from Australia, New Zealand, Singapore and Hong Kong show that the provision for future development is addressed in different ways. These have ranged from making no specific provision, putting the onus onto developers to ensure that the tunnels are not affected adversely, to including a loading allowance for future development in the performance specification or contract documents for a tunnel project.These two contrasting approaches have strong points and risks. A highly prescriptive definition of permissible loadings around the tunnel can provide unambiguous guidance for the approving authority and the developer, but runs the risk of being overly conservative to allow for all the envisaged works, while still missing a detrimental combination of effects that theoretically complies with the specified requirements. In contrast, a general requirement to not cause detriment is open to interpretation and potentially difficult negotiations to reach agreement between the tunnel owner/operator and developer and finally the appointed contractor (probably with no contractual relationship with the tunnel owner).In practice, a combination of prescriptive and performance requirements is likely to provide the optimum combination of clarity and flexibility. The author provides examples and recommendations on how such provisions could be structured.CITATION:Bennett, A L, 2014. Protection of ?tunnels in their future environment, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 495–500 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By A Nigam, K Biswas, R Sarkar

Because of the problems with 1st and 2nd generations of Advanced High-Strength Steels (AHSS), a 3rd generation of AHSS steels has become prominent and these steels have properties in between the 1st and 2nd generations of AHSS. However, although the 3rd generation of AHSS is a promising candidate as a replacement for its predecessors, there remain some challenges in processing these steels which are essentially medium Mn (Mn content ~ 5–7 wt per cent) and high Al (Al content ~ 1– 3 wt per cent) steels. The use of conventional casting powders based on the CaO-SiO2 system is unsuitable for high and medium Mn/Al steels. This work investigates the development of CaO-Al2O3- based mold fluxes for casting third-generation AHSS steel. Mold fluxes, with otherwise similar compositions but different C/A ratios, are tested and their crystallisation behaviour is examined using differential scanning calorimetry (DSC). A calcium aluminate phase having a composition Ca12Al14O33 was found to be the main crystalline phase in the mold fluxes. A decrease in crystallisation temperature was observed as the CaO/Al2O3 ratio increased from 1.00 to 1.33. The effective crystallisation rate constant exhibited an increase with decreasing crystallisation temperature, indicating a potential influence of nucleation rate on the overall crystallisation rate and suggesting an anti-Arrhenius behaviour in the crystallisation process of these mold fluxes.

Aug 21, 2024

By S J. Neethling and, S J. R Simons

In this paper the effect of humic substances (natural surfactants), electrolytes and solid particles on bubble coalescence, and as a consequence on froth stability, have been investigated. In this study two bubbles of equal size were formed and forced to collide using a novel experimental apparatus. The interactions were recorded by a high-speed camera, the images of which helped to determine the coalescence frequency and the coalescence time, as well as the mechanisms of the interactions. Two types of humic substances were used, along with three different electrolytes. Humic substances appeared to have a considerable effect on bubble coalescence, while the effect of electrolytes was minimal. Moderate and high hydrophobic glass spheres were used between two bubbles. Very hydrophobic spheres promoted fast bubble coalescence, while moderate hydrophobic spheres had no effect. Data of coalescence frequency and time is presented, as well as images of the coalescence events. The coalescence frequency was used to validate a parameter, Pf, known as the film failure frequency, used in a simulation model to predict foam height in a gas-sparged vessel. Predictions determined using Pf were then validated by experimentation.

Jan 1, 2005

By Drury SA, Williams RD, Nind DC

The Airborne Thematic Mapper is an eleven channel digital scanner which acquires image data in the visible, near infra-red, short wave infra-red and thermal infra-red wave- lengths. A description of the system is presented which includes details of the operating wavelengths and performance parameters of the scanner. Consideration is also given to the aircraft installation requirements. During January 1984 the scanner surveyed the mineral rich areas of Leonora, Laverton and Kalgoorlie in Western Australia. This is a region of intense exploration activity for gold and base metals. Some 30,000 square kilometres were systematically surveyed in a period of ten days. This scanner was flown at 7,000 metres altitude giving a ground pixel size of 17.5 by 17.5 metres. The flight line spacing was 8 kilometres. The overall project took some thirty days from conception to completion. The planning and execution of this operation are described in detail. The resulting magnetic tapes provided 11 channels of digital image data over a 30,000 square kilometre area and a variety of image processing techniques were employed in order to capitalise fully on the results. The imagery provides a powerful tool for the geological mapping of the terrain. The data can also be used to monitor the environmental effects of mining operations.

Jan 1, 1986

By Mez W

the German ruining industry uses different residues for hackfilling and stowing. A hydraulic pipe conveying technology for these materials has shown advantages for the transportation into the mine. Pipeline conveying systems are able to bridge long distances, they save room within the underground workings and they save staff and costs. Absolutely necessary for successful use of the hydraulic conveying technology is the knowledge about the unusual non-Newtonian flow properties of solid/liquid mixtures like pastes and slurries. The flow resistance of these materials cannot be described easily by one viscosity. Owing to a yield point and a pseudo-plastic behaviour the viscosity changes with the shear rate and with the streaming velocity inside the pipe. Also these flow behaviours depend very sensitively on the liquid/solid-ratio, often so dramatically that gravimetric or volumetric dosing equipment is not in a position to control the production of backfill pastes. Quality changes of the solid raw materials (particle size distribution, density, mineralogical composition) lead to additional difficulties. The first experiences with hydraulic backfilling plants were troubled by plugged pipes. a bad backfill quality caused by unnecessarily high water content and high costs for chemical binders to solidify the backfill. The installation of viscosity controlled paste production leads to success with the hydraulic backfill technology. A development of the l)MT, a bypass pipe-viscometer, has been the key technology. The system is able to analyse on-line, difficult, sticky and abrasive substances and determine their non-Newtonian flow properties. Because the system measures real physical values it is in a position to pre-calculate process relevant parameters like the pressure drop of the backfilling paste in the conveying pipeline. Newer types of the viscometer system also measure the slurry density and calculate its composition. These systems have proven a success controlling backfill paste production plants. They offer it secure prevention of pipeline plugging and a production of high quality backfill pastes with a water content as low as possible.

Jan 1, 1998

By A Stasi, B Brice

Water is a limited and precious resource in Australia. Because of the increasing demand for water from all sectors of the economy and the variability in supply, efficient management of water resources is of vital importance. The national water reform agenda has provided a strong impetus to all states and territories to progressively move towards more efficient and sustainable water management. The Queensland Water Act 2000 is the legislative framework for providing water for the environment and for planning for the security of supply to water users. The comprehensive water planning process prescribed in the Act results in new tradeable water allocations that are separate from land. These water allocations are well specified and can be traded on a permanent or temporary basis. Trading of water allows it to move to its highest value use, thereby encouraging the most efficient distribution of this limited resource. In addition to transferring ownership of water allocations, it is also possible to change the attributes of the allocation, such as the location from which water may be taken. Changes to water allocations are subject to approval from the resource manager. Pre-testing allows for certain changes to be approved very quickly, making the trading process more streamlined and cost effective. Temporary trades, or seasonal water assignments, currently account for the majority of water trades in Queensland. However, permanent trading activity is expanding steadily as old water entitlements are converted to tradeable water allocations and as the market matures. The permanent trading market provides significant opportunities to the mining sector. It allows mining companies to buy water allocations at market prices without compromising environmental outcomes or causing third party impacts.

Jan 1, 2006

By A Whaanga

The use of photogrammetry has greatly increased the accuracy of 3D mapping underground. However, this has not reduced the need or desire for geologists to produce plans and sections showing an interpretation of the mapped geology. At the Waihi Underground Gold Mine, a hybrid solution has been developed that utilises the accuracy of photogrammetry and mapping onto face photos with the CAD-based Deswik.MappingTM functions to create plan and section maps. These have the benefit of looking like traditional paper maps but are more spatially accurate and richly attributed with metadata that can be filtered and exported to downstream processes. Deswik.MappingTM is a tablet-based solution that allows the geologist to map digitally with a stylus. Automation is utilised for the updating of survey as-builts, approved designs, drill holes, geological mapping, vein interpretations and mine work areas, reducing the requirement to print out maps at various locations and scales. Having 3D mine software on a tablet device provides a wealth of features not available when using paper: scaling is a problem of the past; information can be turned on and off; features can be viewed in 3D; and measurements between points of interest can be calculated in 3D space, for example, between vein wireframes and drill hole sample information. A suite of custom scripts has been developed that take the spatially accurate, registered and attributed polyline data from photogrammetry scans and converts them to a geological mapping legend with vein textures, structural information, and lithological boundaries. These 3D maps can be plotted in plan or section view and satisfy the requirements of the most ardent paper map supporter.

Mar 22, 2022

By Bawden WF, Paynter JT

This investigation involves laboratory testing and stability analysis of paste fill at the Golden Giant Mine. Site-cast samples are tested in unconfined, confined, and consolidated-undrained triaxial compression. Pore pressures during shear and consolidation characteristics are measured to determine both drained and undrained shear strength parameters and assess the potential for undrained loading. Liquefaction potential is also considered. A limit equilibrium solution is used to obtain factors of safety against failure of the fill during mining of adjacent stopcs

Jan 1, 1998