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By Bond W. F, Sharry P. V, Onley P. G

The use of Decision Analysis is becoming more widespread in industry as a whole, and there is considerable scope for its application in the mining industry. Wherever decisions have to be made, whenever risks have to be taken, whenever uncertainty exists or whenever judgements have to be made, then Decision Analysis can be used. In the mining industry we daily make many decisions involving risk, uncertainty and judgement. Expansion and diversity will only increase the need for balanced decision making techniques. This paper seeks to describe the history and principles of Decision Theory, and to illustrate the various modelling approaches using three fictitious yet realistic case studies. Decision Analysis logically integrates the quantifiable and seemingly non-quantifiable aspects of a decision problem into a coherent, explicit and rational solution. It also allows the decision-makers to see the full impact of each variable or uncertainty, and hence focus on the key aspects that influence the solution.

Jan 1, 1996

By Prohaska G, Jackson F, Jack B

To learn more about the fundamental roof behaviour in South African coal mines, accurate underground measurements of roof deflection were conducted in bord and pillar panels during development and pillar extraction. To conduct these measurements a survey levelling technique was adapted. The overall system reading accuracy was established as being within 0,4 mm on a 15 m sighting distance. The underground sites were modelled and, for a roadway development, similar symmetrical curvatures were calculated by a linear elastic model, as were measured underground. In a pillar extraction panel, a significant amount of bed separation was measured and the roof underwent an a-symmetric movement due to the close presence of the mined out area at one side of the roadway.

Jan 1, 1992

By Hoskings AD

Bolting forms a prestressed elastic layer of rock which is capable of supporting loads at right angles to the bolted surface. Investigations on rock bolting made with a number of different models give rise to empirical and theoretical prin- ciples for the formation and action of the layer. In the models, flat and arched layers of many materials were used simulating rock conditions ranging from closely interlocked blocks to fragments of various shapes. Results of observations made in the underground works of the Snowy Mountains Scheme are related to the mode of action of bolted surface layers of rock. There is abundant experimental, theoretical and practical explanation for the well-demonstrated capability of bolting as a means of rock support.

Jan 1, 1971

The mine manager is one of the oldest jobs in the world. Over many centuries the fundamentals of how this job was approached did not change much. However since the later part of the 1980s there has been a dramatic shift in the expectations and role of the mine manager as the pressures of globalisation and consolidation have increased the size of companies and the production levels of mining operations. The changes have been dramatic, with demanding requirements on mine managers to continually improve the skill levels of people, to apply and develop rapidly changing technologies and to consider far broader business issues that need to be managed in a truly globally connected world. This paper will attempt to outline some of the issues, the complexity surrounding them and some of the approaches that have been made to manage them. There is not a single correct answer or approach, but there are many key success factors that have led to some amazing levels of performance being achieved as we go deeper, broader and literally move mountains to meet the customerÆs needs for today and tomorrow. This contrasts with many mining operations in developing countries that still have a traditional approach to how they mine. Society is the river of life that continually flows and changes the environment that surrounds it. The pressures from the customers and world growth, shape and force alterations to be made in an industry that has to live with the far greater primal and uncompromising forces of the earth we mine. This has led to some paradigm shifts in how we accept what we manage. TodayÆs mine manager must manage a far broader range of issues, than just how do we get tonnage out of the mine and product out of the ore. These include but are not limited to technical, commercial, product quality and end use understanding, employee and community issues, environmental and the ever increasing complexities of sustainable development. Organisations will have to look at how they structure their management of the business to manage functions to meet the complexity of different stakeholders needs û the business, the employees, the customer and the broader community within an environment that is becoming more attuned to the harm impacts to the world in which we operate. The attraction and retention of skilled people that contribute to the value and worth of the corporation, will become critical to sustain a companyÆs growth. One of the fundamental elements of successfully doing this will always be the skills of the mine manager and his/her extended team with the continued development and support that they will need to meet these demands.

Jan 1, 2006

By Z W. Orndorff

Excavation through sulfidic geologic materials during construction activities has resulted in acid rock drainage (ARD) related problems at numerous (>40) locations across all five geologic regions of Virginia, USA. Potential acidities ranging from >100 to develop a statewide sulfidic materials risk map; document ARD impacts to soil and water quality and engineered structures; and develop methods to assess site-specific risk potentials within a given highway corridor. A statewide sulfidic materials GIS risk map was developed based upon the state digital geology map which assigned four levels of relative risk to all mapped strata based upon predicted lime requirements and probabilities of encountering highly reactive materials. Non-highway construction activities have also routinely disturbed sulfidic materials, and a recent airport project in northern Virginia resulted in over 150 ha of extremely acidic (pH 45 mg/L) run-off from this site heavily damaged a receiving stream, partially due to the fact that it dissolved the galvanised steel water control structures in stormwater detention basins, leading to direct discharge of run-off and sulfidic sediments. The airport area was treated and revegetated in 2002 with a combination of lime-stabilised biosolids, straw mulch, and acid-tolerant grasses. Water quality in a receiving second-order stream quickly responded to the treatment, but some release of N was also noted as a secondary effect. Collectively, these results point out the importance of accurately assessing the potential for excavation of sulfidic materials in construction environments, and the necessity of developing toxic materials handling strategies similar to those employed in mining environments.

Jan 1, 2003

Grade control aims to deliver quality tonnes to the mill via accurate definition of ore and waste. It comprises data collection and interpretation; local reserve estimation; supervision of development and mining; and stockpile management. The foundation of all grade control programs should be that of high quality sampling supported by geology. The requirement for quality grade control samples has long been recognised, where they should be representative, unbiased, safe and operationally timely. Underground sampling methods include chip and channel samples; grab samples; and drill-based samples. To achieve quality samples, collection techniques employed should minimise delimitation, extraction and preparation errors. Grade control staff should be well-trained and motivated, and mining staff should understand the need for grade control. This paper reviews grade control sampling methods and presents recommendations for best practice and minimisation of sampling errors.

Mar 1, 2010

By B Washington, A Campbell, R Taylor

A sampling and measurement program was undertaken on the reaction shaft of the Olympic Dam copper flash smelting furnace. The object of the work was to provide information to validate a mathematical model of the burner and reaction shaft. Samples and measurements were undertaken through the burner inspection ports and the South East (SE) shaft sampling port about half way down the reaction shaft. Samples were collected to enable the calculation of particle loading of shaft gases, or sizing and chemical analysis of the partly-combusted feed, and the preparation of polished sections. Measurements were made of the temperature and sulfur dioxide content of the atmosphere, as well as plume velocity.To implement the program it was necessary to design and construct the following specialised items of equipment. For use at the burner inspection ports: a cup sampler for obtaining samples below the burners (temperature, solids loading and samples for characterisation).For use at the SE shaft sampling port and also at the settler level: trough sampler (plume definition and samples), isokinetic sampler (used as a velocity probe in this work), temperature probe (temperature traverses across the shaft), and sulfur dioxide probe (SO2 measurements across the shaft).The design of the sampling and measuring equipment is described, and examples are cited of the types of information obtained. The problems arising from working in a hot environment with molten or sticky particles are discussed.

Jan 1, 2005

By X Yang, T Zhang, Z Li, Z Yan, M A. Williams, S Qin, P Wilson

Continuous development of complex new steel grades to meet the ever-increasing demand of high performance causes recurrent issues in steel continuous casting such as surface quality defects (eg cracks, depressions, deep oscillation marks) and productivity challenges (eg faster casting, near-net shape casting). Continuous casting of steel is a highly successful metallurgical process. Much of this success can be attributed to the performance of the casting powder that is added to the top of the mould, creates a liquid slag pool as it is heated, and forms a slag film between the watercooled copper mould and steel shell during its passage down the mould. Mould powder selection is a compromise between the conflicting requirements of heat transfer and lubrication. In an EU RFCS (Research Fund for Coal and Steel)-funded project, various techniques are developed to offer the opportunity to adapt the slag film to meet the conflicting needs in different parts of the mould such that mild cooling can be generated in the meniscus, mid-broad face or corner areas whilst maintaining lubrication and offering higher cooling rates in other areas of mould. This has significant potential to address the industrial issues in product quality and productivity of continuous casting. This paper reports, as part of the EU RFCS project, the determination of crystallinity and porosity in slag films for casting challenging and innovative steel grades using new methods. In comparison with the methods such as X-ray powder diffraction (XRD) analysis and optical microscopy / scanning electron microscopy (OM/SEM) analysis that are currently adopted by the industries, EBSD (electron backscatter diffraction) has been employed to determine the crystallinity of the slag films taken from industry casters. X-ray computed tomography (XCT) plus 3D image reconstruction has been used to determine the slag film % porosity with pore volume, pore size distribution, and pore location, which can be linked with the performance of the slag films during casting different steel grades.

Jun 19, 2024

By T R. Stacey

South Africa has a long history of rockbursts, some 100 years. During this time much research and many developments have taken place in the country to limit the occurrence of rockbursts, and to mitigate their effects. In this paper I shall present a personal view of what I consider to be important achievements, and contributions made. Some of these are: planning of stope layouts, and the use of strike barrier pillars; recognition of energy as a key factor, the use of the energy release rate ERR as a layout planning criterion, and development of MINSIM for calculation of ERR and stope planning; sequential grid stope layouts; use of backfill for stope support; and, development yielding support elements, and dynamic testing of stope and tunnel supports. The record shows the establishment of a rock engineering research powerhouse over a 40 to 50 year period and, unfortunately, the complete breakdown of this capability in the subsequent 10 years. CITATION:Stacey, T R, 2018. A personal review of South African rockburst research, experience and lessons learnt, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 5–16 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By Coin CDA

From a study of coke samples obtained from the tuyere level of four Australian Blast Furnaces, the nature of in-furnace coke degradation has been investigated. At the periphery of the raceway is a concentration of fines and the lump coke appears dull and rounded. However coke from the deadman is angular and relatively undegraded. Cokes made from higher rank coal appear to suffer preferential attack of the reactive maceral derived component (binder). The coke from lower rank coal appears to be attacked non-preferentially by the solution-loss reaction. Initial attempts to simulate these phenomena have given results consistent with these findings. From chemical analysis of the tuyere probe samples there appears to be a relative increase in carbon and decrease in-.sulphur and phosphorous between stockline and tuyere level. An overall decrease in coke mineral matter derived material was noted and associated with this was a significant gasification of silicon. Consequent formation of silicon carbide was noted.

Jan 1, 1981

An understanding of the importance of the different components that comprise a rock bolt unit is necessary to ensure the proper use of rock bolts as a means of roof support. The various anchors, bolts and plates in use in Australia have been designed and adapted for Australian con- ditions. As mining conditions change, so will the types of bolts in use. This is apparent in the development of chemical anchors and other recent innovations.

Jan 1, 1971

By Payne AR

The high cost of gateroad repairs and maintenance in U.K. longwall coalmining is a clear indication of the failure of permanent support systems to fulfill their prime function, i.e. control of strata movement. The main component of gateroad support is the pack, the design and materials of which have experienced an important development process during the last 10-15 years. More recently, research investigators have attempted to give a design basis to pack quality and dimension, and reference is made to two theoretical approaches. In the course of a current research programme based upon in situ monitoring, interim design recommendations have been proposed as a means of effecting improvement in support efficiency. Identification of characteristic deformation behaviour forms the basis of the recommendations made and the subsequent improvement in gateroad performance reported.

Jan 1, 1986

By D Giles

We present plate tectonic reconstructions, showing that porphyry-type ore deposits are spatially and temporally linked to ridge subduction. A reconstruction of the Peruvian subduction system reveals an immediate metallogenic response to the arrival of the Nazca Ridge at the subduction trench, followed by southward migration of the zone of metallogenic activity due to the lateral migration of the zone of ridge subduction. A similar pattern is recognised in central Chile , where the spatio-temporal distribution of giant ore deposits coincides with the arrival of the Juan Fernandez hotspot chain at the subduction zone. We conclude that there is a spatial and temporal link between ridge subduction and ore deposit formation, with high metal fluxes concentrated in zones of ridge subduction. Thus, the recognition of tectonic patterns associated with ridge subduction can provide insights into predictive mineral discovery by enhancing our ability to predict the position of large mineral deposits in other modern and ancient orogens. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Gilligan P

The Selwyn gold-copper operation is wholly owned and operated by the Arimco mining group. The mine is located 150 kilometres south-east of Mount Isa. The primary extraction method for the gold-copper 251 orebody is by sub level open stoping. Secondary extraction is from the mass blasting of the remaining crown and rib pillars. The final mass blast of the 251 orebody occurred in December 1993. This paper details the design and execution of that firing.

Jan 1, 1994

By Jancar T, de Guzman M M, Matthews B, Tu J. Y

The use of computational simulation to predict the performance of existing equipment or for the design of improved mineral processing equipment will be referred to as Computational Mineral Processing (CMP) in this paper. The emphasis will be on solving the governing equations for liquid solid flows in complex geometric domains to obtain, typically, the three-dimensional distributions of velocity and pressure for the liquid phase and the velocity and concentration for the solid phase. The underlying technology, computational fluid dynamics (CFD), is very well-developed in other industries (aircraft, car and chemical) and forms a vital part of product design and analysis. The subsequent design of improved mineral processing equipment may also involve finite element structural analysis (FESA). Computational fluid dynamics (CFD) and finite element structural analysis (FESA) are part of the generic discipline of Computational Engineering and Science (CES). Ciment and Scherlis (1993) define CES as `The systematic application of computing systems and computational solution techniques to mathematical models formulated to describe and simulate phenomena of scientific and engineering interest'. Increasing computer power (Kaufmann and Smarr, 1993), is a dominant factor determining the rapid growth of industrial utilisation of CES. This increase is happening at both the supercomputer and the workstation level. Indeed, today's typical workstation, a Hewlett-Packard 735, is as powerful as a CDC 7600, the leading supercomputer in 1970. Future computer architectures are expected to become increasingly parallel (Gartner Group, 1990) allowing a sustained performance of a teraflop (a million megaflops) to be achieved well before the Sydney Olympics in the year 2000. It is recognised that the modem development of most disciplines in the physical sciences rests on the three complementary strategies of experimentation, analysis and computational simulation. As the 21st century is approached the volume of computational simulation, both fundamental and applied, is growing dramatically and the role of experimentation is diminishing. In the area of equipment design, CES provides the following advantages over experimental testing and measurement: 1. lead time in design and development is significantly reduced; 2. CES can simulate conditions not reproducible in experimental tests; 3. CES provides detailed and comprehensive information; and 4. CES is more cost-effective and time-efficient. The ultimate benefit for industry is greater productivity and hence greater profitability. The broader issues in relation to CFD are discussed by Fletcher (1993b). In the five- to ten-year time frame, growth in computer power will make it practical to combine CFD and FESA with optimisation procedures to produce a design process that is almost fully computerised. It is expected that fully automatic

Jan 1, 1995

By R Forster

Direct ship iron ore (DSO) operations at Extension Hill in Western Australia’s Midwest region have commenced, with fi rst product railed to the port of Geraldton in July 2011. Reserves are 14.8 million tonnes (Mt) of haematite-goethite ore overlying an Archaean BIF-hosted larger magnetite deposit which Mount Gibson Iron Limited (MGI) sold to other parties in 2006.Some unique geological aspects of the deposit shape DSO mining and processing operations. Owner-operator selective mining, blending, crushing and screening on site will produce three million tonnes per year (Mt/a) of Lump and Fines product to be trucked 86 km to Perenjori, railed 232 km to Geraldton, and loaded aboard Panamax-sized ships through the dedicated iron ore shiploader at the Geraldton Port Authority’s Berth 5 facility.The statutory approvals process for this project formally began in 2004, dominating delays in a predevelopment phase which extended over a longer period than the likely life of DSO operations. The lack of transparency, uncertainties and costs inherent in state government processes have influenced decisions made by MGI while assessing other development opportunities in Western Australia. Potential for additional Reserves exists at Extension Hill, however MGI’s ability to extend the mine life will hinge on statutory approval to explore for and evaluate other DSO resources on surrounding granted mining leases.The nature of the resource and use of existing infrastructure for product transport have enabled MGI to keep operating costs and capital intensity of this project relatively low. A tenacious development approach by MGI and robust project economics have fi nally enabled this site to take its place as a revenue earner beside the company’s other DSO operations at Tallering Peak and Koolan Island.

Jul 11, 2011

By Buizen M

An investigation into the mechanics of sub-surface deformation caused by caving of the extracted area behind retreating longwall faces has been completed by the Subsidence Engineering Section of the New South Wales (NSW) Department of Minerals and Energy. Changes in strata bulk permeability were also measured by standard packer tests undertaken before and after mining. The strata movement was measured by a multi-wire borehole instrumentation system consisting of mechanical anchors installed at different horizons in a borehole extending from the surface to the coal seam. The mechanical anchors were collected to suspended weights on the surface by stainless steel multi-strand wires. The movement of these weights was monitored as the longwall face approached and retreated past the borehole. The anchors did not move significantly until the face went past the borehole. For subcritical extraction geometry with the extraction width to mining depth ratio of 124, the caving zone extended to roughly 9 times the extracted seam thickness above the seam roof. Tensile strains within the overburden tended to be much more closely related to stratigraphy than to the proximity to the extracted seam roof. Larger tensile strains were associated with layers of sandstone, siltstone and conglomerate, whereas layers of mudstones, claystones and coal underwent much smaller strains indicating subsidence in blocks. A beller correlation was observed between pre-mining Rock Quality Designation and permeability than between rock type and permeability. This correlation was less evident in the post-mining core logs. There was an overall increase in bulk permeability after mining.

Jan 1, 1990

Powercoal Pty Ltd operates eight underground coal mines in New South Wales and produces coal for both domestic power stations and the export market. Approximately 40% of total production is from continuous miners. Over the past five years, place change mining methods have been introduced to improve productivity from continuous miners. This has involved utilising the existing coal clearance system from the continuous miner to the ratio feeder using trailing cable shuttle cars.By late 1996 average productivity at Cooranbong Colliery using this system had plateaued at 800 tonnes per eight hour shift. A number of factors were identified to increase average productivity to 1500 tonnes per eight hour shift. An improved coal clearance system was one of the factors identified.

Jan 1, 1998

The advancements achieved in rapid tunnelling in the 60's and 70's have been notable. It is unfortunate that shaft sinking has not enjoyed equivalent advances and there are many good reasons why this is so. Technical and commercial considerations have held back development and continue to do so despite the increasing urgency in the search for minerals and energy. By the careful selection of an appropri- ate project and the application of specialist engineering the Bdard took advantage of a unique opportunity to apply a mechanised shaft borer in field conditions.

Jan 1, 1981

The resource sector is conservative industry and people are resistant to change. The methods and procedures used to implement changes in process plants ultimately determine the success of such changes. The financial managers have a large say in where money is spent and the technical personnel must justify the cost and benefits for any expenditure. There are also others who believe it canÆt be done û æwe tried thatÆ. Implementing change needs a æChampionÆ who can assess the risks, plan, define the objectives and scope, set the goals, determine the key performance indicators (KPIs) and stay focused. This also requires preparing a budget and schedule and measuring against this. Contract management, reports and reviews are part of the implementation. Several case studies are given as examples of the implementation of process design changes to highlight the critical aspects involved.

Jan 1, 2009