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By A R. Cruden, M S. Egglseder

The formation of banded iron formation (BIF)-hosted high-grade iron ore deposits in the Hamersley Province, Australia has been debated for decades. Although a structural control on their formation is widely accepted, only the roles of large-scale structures (ie faults and folds) formed by brittle and ductile deformation have been considered to date. However, the deformation of multilayered sequences in the Hamersley Province (ie the Mount Bruce Supergroup), with their contrasting rheological behaviours, creates challenges for understanding the complex structural framework at regional to deposit scales, including the significance for mineralisation and orebody location.Our approach to understanding these complex relationships is based on an established principle of structural geology, which is to extrapolate microscale structures to deposit-scale structures and vice versa, supported by state-of-the-art 3D modelling techniques. Complexly deformed hand samples associated with the Mount Tom Price iron ore deposit (Hamersley Province, operated by Rio Tinto Ltd) have been analysed and visualised with 3D explicit (Move™, Midland Valley Ltd) and implicit modelling software packages (Leapfrog™, AranzGeo Ltd) and supported by microstructural investigations (optical and X-ray microscopy) and fieldwork.Our study shows that the deformation of BIFs in the central Hamersley Province is controlled by microscale chemical processes (ie dissolution precipitation creep) due to rheological differences between iron oxide and chert layers, contrasting fluid flow properties and layer thickness variations. These processes account for the removal of vast amounts of silica, its transportation by diffusion in the presence of a fluid and reprecipitation at low-pressure sites. Consequently, this structural framework was used by different upgrading fluids to form iron orebodies.CITATION:Egglseder, M S and Cruden, A R, 2015. Evolution of a structural framework for high-grade iron ore deposits, in Proceedings Iron Ore 2015, pp 255–262 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

The paper provides an overview of the development and content of APCOM symposia since their inception in 1961. This development is set within the context of the academic environment in which much of the research published at APCOM symposia is conducted. This environment includes rigorous external assessment of research quality at national levels and against international benchmarks, which carries significant consequences for funding and for the continued existence of the academic minerals industry disciplines. Adverse consequences that undermine the academic provision of mining and resource engineering will impact negatively on the minerals industry by reducing the level of research and education resources available to it.The traditional reductionist approach to research is contrasted with the inter-disciplinary approach that is required to address the complex systems problems that the minerals industry will have to address to ensure its technical, economical and environmental sustainability. Such an approach offers a means of raising research profiles, of establishing mutually beneficial academic-industry engagement and provides an opportunity for APCOM to take a lead role in identifying the research and development agenda for the future

Sep 26, 2011

By Yanske TR, Lane WL

The Doc Run Company and its predecessors have been mining for over 130 years utilising the room and pillar mining method. This method has left approximately 20 per cent of the orebody in the remaining pillars. The original design and planning for the mines did not include extensive pillar extraction. This paper summarises the introduction of the pillar extraction and backfill techniques which have been implemented since 1991. These techniques include the use of low cost fill walls up to 20 in in height and the use of stinger trucks for topping off the fill. In conjunction with these accomplishments, much experience and confidence has been gained in the use of numerical modelling as a method of predicting pillar stability as the mining of pillars progresses. These advances have led to pillar extraction hecoming a major portion of the overall production and have added to the mine life of Doe Run's six operating mines.

Jan 1, 1998

By D J Williams

Coal washery wastes comprise tailings, finer than 0.5 to 0.1 inn depending on the sophistication of the washery, and coarse reject, typically finer than 50 mm. Subaerial disposal of coal tailings slurry at about 30 per cent solids by mass results in the formation of a delta with an average slope of about 1 in 100, representing one extreme. The ravelling of coarse reject on loose-dumping, results in an angle of repose slope with an angle of about 37" (1 in 1.3), representing the other extreme. The pumped co-disposal of coal tailings and coarse reject results in the formation of an upper delta with an average slope of about to one in ten, between the two extremes. The depositional behaviour of these three waste streams is discussed and compared in this paper. The important depositional and material parameters, and a theoretical description of the processes involved, are also presented. Comparisons are made between the depositional behaviour of the various coal washery waste streams, and natural depositional systems, such as rivers, alluvial fans, and scree slopes.

Jan 1, 1998

By M Stephens, T A. Sutra

Currently, there are several open pit mines with production rates of about 200 000 tpd of ore that are reaching the end of their economic lives. In most cases, the remaining orebody extends to depths greater than 300 m below the pit limit, leaving hundreds of millions of tons of reserves that can only be recovered by means of an underground mining method. One such method used for mass production is block caving. This paper presents a ventilation system for a four-zone block cave mine operation developed on a footprint 1000 m wide and 1200 m long. The system is designed for a mine with a nominal production rate of 120 000 tpd of ore using diesel powered units on the production and reduction levels. It discusses the air quantity requirements for the worst case scenario, which is anticipated to occur five years after the mine has reached its full production capacity. Finally, it summarises the results of computer modelling exercises that were carried out to determine an economic ventilation infrastructure that includes shafts, drifts, main fans, and ventilation control devices.

Jan 1, 2005

By Holmes RJ, Sowerby BD, Watt JS

Major improvements have taken place in mineral and coal processing in the last decade. The development of nuclear on-line sensors that continuously analyse the material being processed has led to better control of metalliferous mineral processing and increased recovery of valuable minerals. The recent development of on-line techniques for analysis of coal is expected to be of similar Importance. Australian developments in on-line nuclear gauges are reviewed. These include systems for in-stream analysis of mineral slurries with comments on plant operating experience; on-line determination of ash in coal using low energy Y-ray transmission and pair production techniques; in-stream determination of solids weight fraction and ash content of coal in slurries with variable voidage; and on-line determination of moisture in coal, iron in high grade iron ores and sulphur in lead sinter.

Jan 1, 1986

By I Canbulat, G Si, Y Duan, X Luo

The presence of unfavourable geological structures such as faults and dykes often can contribute to coal burst risk. Seismic events associated with rock fractures tend to cluster around these structures and it is important to understand the characteristics of seismicity for coal burst risk management. In an Australian underground longwall coalmine, two clusters of seismic activities close to the longwall face and within a section of the maingate roadway which was intersected by a major dyke were respectively identified. The induced seismicity in the dyke-roadway area was closely related to the longwall mining. These seismic events were located and the distribution of seismic events shows that more fractures were distributed on the inbye side of the dyke. The spatial-temporal changes of the seismic event locations delineate the fracture propagation as the longwall mined through the dyke. The frequency-magnitude relationship of seismicity was analysed and it was found that it changed significantly when the longwall was mining towards, through and past the dyke. The monitoring results demonstrate that because of the stiff dyke, the seismicity was intensified in the roadway section. It proves that the dyke promoted stress re-distribution and seismicity in its vicinity. More fractures were induced in the hanging wall of the dyke, whereas less strain energy was accumulated and released in the footwall of the dyke.

Nov 29, 2022

By R Chinamatira

Several technical and economic factors have to be taken into consideration in developing an optimal mining method. This paper describes some of the important factors learnt during the evolution of the sublevel cave mining method at Trojan Nickel Mine, part of the Bindura Nickel Corporation (BNC) in Zimbabwe. Sublevel caving (SLC) has been successfully implemented at Trojan mine since its introduction in 1994. The method has evolved over the past six years into a system that has brought about improvements in efficiencies and productivity. Although the original design parameters used were sound and provided a solid foundation for the system, they needed to be optimised to get the best out of the mining method. Improvements and changes have been made in areas such as the drilling process, charging and blasting techniques, ring pattern design, development size and shape, and the draw control system. This has enabled the mine to develop an SLC operation that is efficient and innovative. Experience gained, together with the theory available has given us a much better understanding of the system. This knowledge will be used in the future to enhance the system further. Given the low grades of the BNC Mines, management recognises that only through technical excellence and efficient mining can the mines reduce mining costs and maintain profitability and competitiveness on the world market. In the Zimbabwe mining industry reaction to technological change, mechanisation and advancement have been relatively slow, due to isolation and economic constraints, compared to the rest of the world. Economic difficulties prevail, with high inflation levels, a poor exchange rate, lack of foreign currency and other associated problems. Despite these constraints, the bold steps taken have transformed Trojan mine into a more efficient and competitive operation, presenting itself as the leading mine in the BNC group. Appendices give data to illustrate the benefits obtained.

Jan 1, 2000

The Kunwarara magnesite deposit is the largest known magnesite (MgCO3) deposit in Australia. It is located under black soil plains to the north of Rockhampton in Queensland. The deposit consists of magnesite nodules set in a fine-grained sandstone, siltstone and mudstone matrix. The magnesite is derived from weathering of serpentinite in adjacent hills and transport of magnesium in solution to a Tertiary/Quaternary river system. The magnesium has come out of solution in the active river system, and combined with atmospheric and biogenic CO2 to form magnesite nodules. The magnesite can be very pure with certain varieties up to 98 per cent MgO (LOI free). The deposit has been mined since 1991 and processed into magnesia (MgO) which is sold into refractory, agricultural and other markets. The geologist is an integral part of the small mine technical team. The role of the geologist includes characterisation of the ore through drilling and bulk sampling, supervision of geological aspects of mining and assistance in the optimisation of ore processing.

Jan 1, 2000

The Cannington silver lead zinc deposit is located near Mt Isa in North West Queensland. This world class orebody is owned by BHP World Minerals (BHP) and is estimated to contain 45 million tonnes of ore at an average grade of 11 per cent lead, four per cent zinc and 500 grams/tonne silver. At BHPÆs planned 1.5 Mtpa extraction rate, the mine life will exceed 20 years. Construction of the underground mine, which commenced in August 1993, was carried out by Peabody Resources Ltd (Mining Services Division) (PRL) for BHP Minerals Pty Limited (BHP) under contract packages totalling approximately $100 M using several innovative techniques to deliver safety, quality and time related project goals. Client/Contractor Partnering, resulting in harmonious working relationships, a combined commitment to the achievement of an excellent safety record, and a seamless transition from the construction phase to operation of the mine, has been a feature of the project.

Jan 1, 1998

By D J. A Van Zyl, J C. Cunning

Technological advances associated with the expanded application of paste technology in underground mine backfilling are now stimulating an interest in the disposal of process tailings as paste in the surface environment. Concurrent with the development of alternative surface tailings disposal practices is the requirement to fully understand the consolidation behaviour of tailings in paste form, and to relate this understanding to the significant body of data and operating experience from decades of study of the performance of hydraulically placed tailings. One effective method for demonstrating the benefits derived from handling and placement of tailings as paste is to review tailings slurry consolidation theory from the perspective of the changes which take place in the material as it makes its transition from a loose slurry to a dense, stable deposit resulting from managed thin-layer deposition. For a typical process tailings, an example is provided which illustrates the effect which mechanical dewatering has in accelerating the consolidation process and thereby providing a range of benefits from the perspective of surface disposal. Increased rates of filling (rise), expanded use of upstream embankment construction methods and elimination of impounded surface solutions are some quantifiable benefits which can be assembled on a site-specific basis to allow for valid comparisons with more traditional approaches to tailings disposal.

Jan 1, 1998

By R Justa Cámara, J María Bertrán Llop

"The need for suitable geotechnical characterisation of the rock mass for underground construction is evident. The enlargement project of Railways of the Generalitat of Catalunya (FGC) in Sabadell is a patent example.In general, it is uncommon to encounter problems in the identification and characterisation of certain relevant weak rock formations, which affect project designs. However, all materials should be properly studied, as mischaracterisation can lead to a suboptimal design, resulting in construction problems during the course of the work.Good quality rock is generally not difficult to characterise, but this is not the case for Quaternary or Tertiary cemented soils. Geotechnical investigations based on boreholes do not provide enough information because samples are often badly damaged during the drilling process, if appropriate techniques are not taken. The samples can be altered and may not be representative of the in situ?material.The design and construction of the extension to the FGC line in Sabadell highlighted the importance of the characterisation of Quaternary and Tertiary cemented soils, in particular their rigidity and its underestimation. The twin tunnel project had a total length of 5.1 km, including five stations with 3.5 km excavated by tunnel boring machine (TBM). The remaining 1.6 km was constructed using cut and cover methods. The TBM portion of the tunnel had a bored diameter of 6.83 m with an internal radius of 3 m and 0.25 m thick precast concrete segments. Much of the tunnel alignment passed through and was affected by the presence of certain stiff layers of Quaternary cohesive materials.In this paper the TBM challenges faced will be discussed in detail. In particular:  TBM excavation rate reductions and overheating problems due to the required excessive thrust and torque floating problems in the lining due to nil earth pressure over the rings and the development of an improved, controlled setting time mortar to address this issue block-in and block-out methodology for each station, in some cases with internal blocks to prevent earth pressure drops and soil scouring the relevance of performing simpler solutions, for example, hyperbaric interventions to examine the cutter wheel tools when it has been shown that interventions under atmospheric conditions were equally feasible the implementation of conventional bivalve machines as standard procedure for excavation of diaphragm walls in stations, where in fact, hydrocutter machines or pile boring machines may have been required, given the mechanical characteristics of the materials to be dug out.CITATION:Justa Cámara, R and María Bertrán Llop, J, 2014. Underground extension of the FGC line in Sabadell through cemented soils, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 161–170 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 17, 2014

This paper deals with the evolution of Canadian shaft sinking technology over the last 15 years. Most, if not all, shaft excavation projects in Canada prior to 1990 were sunk using traditional benching methods with labour intensive equipment. In the late-1980s, J S Redpath Limited of North Bay, Ontario, Canada, were contracted to deepen the shaft at Atomic Energy of Canada LimitedÆs Underground Research Laboratory (URL) located in southern Manitoba. The laboratoryÆs role was underground hydrological and geomechanical research, so the project offered both time and opportunity to conduct additional experiments while sinking. The offshoot of the research program was the true birth of the Canadian version of full-face, long round shaft sinking technology. Throughout the 1990s, this sinking method has been further refined over a number of shafts. The results have been faster sinking rates, a safer work environment and an overall improvement in project economics.

Jan 1, 2002

By S S Solomons

In 1991 the uranium spot market price dropped to approximately US$7/Ib U308, a historical low in real terms and the short-term outlook for the industry in the next five years was grim. At this time the Ranger operation was producing uranium concentrate at its design capacity of approximately 3 000 tonnes/year. The loss of two major long-term contracts owing to price and reduced power utility demand due to excess inventories meant that the company could not match production to sales. Continuance at this production level would have resulted in a rapid buildup of product inventory and the tie-up of significant cash reserves. After analysing various options, an innovative operating strategy was devised such that production and sales were approximately balanced without a significant impact on the unit production cost or a long term effect on the plant or operation. A campaign mining/milling operation commenced and approximately 40 per cent of the workforce were retrenched. Multi-skilling of all employees was a critical aspect of ensuring a successful outcome. This paper examines the strategy and reports on the success of the operation two years after the restructuring exercise was effected in November 1991.

Jan 1, 1994

By Grady B. V, Ault A. R, Newman O. M G, Fraser R. J, Malcolm J. McPhersqn

In all electrolytic zinc plants cadmium is removed as an impurity prior to the zinc electrowinning stage of the process. Cadmium metal is the favoured form of this by-product and most plants use an electrolytic route for its production. The formation of dendrites in cadmium electrowinning processes is the major limitation to deposition rates. There is an economic incentive, therefore, to better understand the factors affecting their growth. A technique that has been used by others to examine fundamental aspects of dendrite growth has been applied to industrial strength electrolytes. It involves potentiostatic deposition in a cell containing the electrolyte of interest. The variation in the current with time at a given overpotential allows the determination of the dendritic growth induction time. A method was developed (the Locus method) from the investigation of a set of such potentiostatic curves, obtained over a range of applied overpotentials, that appears to give a measure of electrolyte quality with respect to dendritic growth in galvanostatic deposition. The Locus technique predicts that zinc at industrial concentrations in cadmium electrolytes should have a significant effect on morphology and that deterioration of morphology will occur as the zinc concentration in the electrolyte is increased. This effect is consistent with literature prediction and was shown to relate to a reduction of the diffusion limiting current density. Magnafloc R333 is used as an additive at Pasminco Metals-EZ to control the morphology of cadmium deposits and the Locus method was successful in predicting its dendrite inhibiting properties. A possible mechanism is discussed. This work has opened avenues for future research with respect to a technique that may have an industrial application in electrolyte characterisation and has pointed to a direction in which better understanding of galvanostatic dendritic growth may be found.

Jan 1, 1993

By R W. Henley, L Knuefing, M Turner, Y Zhang, M Saadatfar, A Limaye, R Cruikshank, M A. Knackstedt, A Kingston, L Beeching, N Francois

A better understanding of ore fragmentation and the textural features of ore is a key to the energy efficient extraction of targeted minerals from low-grade ore deposits. In this study, X-ray microcomputed tomography (micro-CT) is employed to study mineral liberation during the tensile failure and onset of fragmentation of a copper ore. Our results show that X-ray micro-CT could inform new studies of ore micromechanics and fragmentation at the laboratory scale and may offer new avenues to address current challenges in the design of efficient comminution processes. We present the results of experiments based on a high-pressure apparatus enabling micromechanical studies to be carried out in situ (inside a micro-CT scanner). This platform produces high-quality 3D images of the evolution of a sample of porphyry copper ore during an in situ fragmentation test. A sequence of tomographic images enables mapping in 3D of both the deformation of mineral phases and the fragmentation process. The fragmentation occurs quasistatically through multiple stages starting with an initial tensile fracture splitting the ore diametrically, followed by tensile-activated nucleation and growth of multiple fractures producing a complex fracture network. Coupling breakage with microstructural information enables quantitative determination of the impact of ore texture heterogeneity on fracture patterns and mineral liberation. This microstructural information can be compared to key measurements of the ore mechanical behaviour such as the global deformation energy, strain deformation field and the stress relaxation response. The latter allows one to identify interesting precursor signals of the tensile failure. The copper liberation, fragment size distribution and breakage patterns are statistically characterised and related to comminution mechanisms which are clearly identified in the sequence of tomographic images. The two dominant mechanisms are rock-rock friction/compression induced by fracture closing and compression-driven fragmentation at rock-crusher contact points.

Aug 24, 2022

By C Samuelsson, Q Shu, A Lennartsson, F Gyakwaa, A Andersson, J Isaksson

The physico-chemical property, viscosity, is essential for pyrometallurgical processes and influences the settling rate of valuable metal droplets in slag, affecting the metal recovery. The copper slag from smelting furnaces typically contains between 1 and 2 wt per cent Cu, which equals to or is higher than in most sulfidic copper ores mined today, meaning the slag is a valuable resource for copper extraction. A low viscosity is desirable for slag-cleaning through a settling furnace where entrained droplets settle under gravity. One approach to control the viscosity is through the slag composition. The literature has limited data on the correlation between viscosity, slag structure, and optical basicity of iron silicate slag with FeO/SiO2, CaO, and Al2O3 as factors. Therefore, the present study evaluated the influence of these factors on viscosity and correlations with slag structure and optical basicity. The FeO/SiO2 ratio (at%/at%) and the CaO and Al2O3 content were altered in two levels, resulting in a two-level full factorial design with three factors. The study was done by synthesising FeO–SiO2–Al2O3–CaO–MgO–Cr2O3 melts, followed by water granulation. The melt structure of the samples was analysed with the help of Raman Spectroscopy. The viscosity was then estimated with a high-temperature rheometer using a Mo spindle and crucible. The results showed a correlation between the optical basicity, FeO/SiO2 ratio, and viscosity, where a high optical basicity and FeO/SiO2 ratio were beneficial for achieving a low melt viscosity.

Jun 19, 2024

By S J Riley

The cover (cap) over the tailings pit at Nabarlek uranium mine must be structurally stable as it will act as a barrier to radon gas emission and have to contain other long-lived radionuclides. Structural stability is primarily an issue of erosional stability in the context of a design life of thousands of years. The primary agent of erosion is fluvial, dominated by rainwash, overland flow, filling and gullying in the local area. Other agents of erosion are of less concern although biogenic agents of erosion (eg termites and windthrow) may enhance fluvial activity. Several methods may be used to assess erosional stability. They fall into two main categories, namely erosion modelling and geomorphic modelling. The former is illustrated by the Universal Soil Loss Equation in which parameters describing aspects of the geotechnical and hydrological properties of the rehabilitated surface are used as input for the modelling of erosion rates. The latter is illustrated by estimates of gully and valley erosion using empirical models. Estimates of the erosion rates and stability of the Nabarlek cover are presented. The two main techniques are complementary and it is argued that rehabilitation design must make use of both approaches when estimating erosion and geomorphic stability. More recent developments in geomorphic modelling using numerical techniques incorporate both approaches.

Jan 1, 1994

By A Scott, S Kanchibotla, J Segui

The æMine to MillÆ concept is not new. In fact, it is the underlying objective of every mine. Unfortunately, in many operations the management structure and reporting systems have created independent æbusinessesÆ within the overall mining enterprise. This has created incentives to optimise the performance of each component of the operation rather than the enterprise as a whole. The Mine to Mill Conference organised by The AusIMM in October 1998 documented a number of case studies where run of mine ore was not presented to the mill in the best possible form for subsequent stages of comminution and processing. A number of examples were quoted where modest expenditure in the mine had a very significant impact on downstream process efficiency and hence costs. Examples included:the minimisation of fines in the mining and handling of iron ore; the management of fines in blasting and crushing for a copper heap leach operation; the control of blast damage, mining recovery and dilution in open cut coal operations; and the optimisation of mine fragmentation to increase mill throughput in gold and copper operations. The latter topic has been trialed at a number of mines and is referred to as æMine to MillÆ fragmentation. A number of æMine to MillÆ type investigations have been reported in the literature including Pease et al, Simkus and Dance, Nielsen, Scott et al, Kojovic et al, Kanchibotla et al, Bulow et al and Hawkes from the 1998 Mine to Mill Conference. In addition, a number of studies are in progress or the results have yet to be published. These studies have demonstrated the feasibility of obtaining the data required to characterise the breakage behaviour of ores and to model the impact of changes to blasting practices on process efficiency. Characterising the breakage behaviour of ores is a vital step in the management of fragmentation and comminution in mines. The characteristics of importance to fragmentation fall outside the parameters conventionally required to describe the economic geology of a deposit. æMine to MillÆ optimisation of fragmentation means that the mining engineer needs information from the geologist in order to be able to help the metallurgist. Providing this information requires close interaction between these groups.

Jan 1, 2000

By T Y. Ko, Y S. Kang, S J. Park, J H. Hwang

The lunar subsurface, particularly the lava tubes formed by ancient volcanic activity, presents a promising environment for establishing safe and sustainable human habitats on the Moon. Tunnel Boring Machines (TBMs), widely used for excavating tunnels on Earth, offer a potential solution for developing these subsurface spaces. However, the unique lunar conditions, including extreme temperatures, high vacuum, radiation, and the extraordinary strength and abrasiveness of lunar rocks, necessitate significant adaptations to existing TBM technology. This study investigates the feasibility of utilising TBMs for lunar subsurface exploration and base construction, addressing the challenges posed by the harsh lunar environment. We review previous conceptual designs for lunar TBMs, highlighting their strengths and limitations in addressing these challenges. Additionally, we explore innovative excavation methods, such as microwave-assisted rock weakening and undercutting techniques, to enhance the efficiency and effectiveness of lunar TBM operations. By evaluating the geological characteristics of the lunar crust and analysing the potential of lava tubes as launching points for TBM operations, this study provides a comprehensive assessment of the technical requirements and operational considerations for lunar TBM implementation. The findings of this research contribute to the growing body of knowledge on lunar base development and pave the way for future human exploration and utilisation of the Moon’s subsurface resources.

Sep 1, 2024