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By Wooltorton B

Highwall failures in surface coal mines in Queensland occur as circular slips through weak and weathered material, or as bilinear slides on sub-horizontal surfaces and steeply dipping joints. Weak horizontal planes occur in the Permian-Tertiary unconformity or on bedding surfaces within the Permian Coal Measures. Sub-vertical movements occur along rock joints and tension cracks induced by stress relaxation after excavation. Blasting also introduces new fractures and causes movement along existing rock discontinuities. Critical factors for stability include the dip direction of potential failure surfaces, shear strength of the rocks, damage due to blasting prior to highwall excavation, groundwater conditions, the type and performance of clays on shear surfaces, and pit geometry.

Jan 1, 1981

Rio Tinto Iron Ore (RTIO) manages eleven mines in the Pilbara region, Western Australia. Three of these mines have previously or are currently mining black shale that contains varying amounts of pyrite. Several new deposits currently being evaluated and existing mines that may progress below water table in the future, will also encounter this waste material. The black shale presents not just an acid rock drainage risk but also a spontaneous combustion risk. This paper presents the black shale management strategy and provides an overview of the relevant activities undertaken by RTIO. The strategy can be divided into two components which firstly involve defining the risk and secondly involve managing the risk. The mineral waste management plan is used to identify specific mineral waste hazards by:geochemical characterisation of waste material,undertaking mine site specific risk assessments,characterising the receiving environment,identifying sulfidic boundaries in geological and mining models,quantifying the amount of sulfidic material in medium and long-term mine plans, anddesigning and sequencing black shale waste dumps. Once a mine exposes black shale the Spontaneous Combustion and Acid Rock Drainage management plan is used and the major activities are: regular site meetings with a representative from every group that works with black shale;compliance with safe working procedures for site specific and detailed activities;regular training;the use of specific explosives to prevent premature detonation;ongoing geochemical characterisation;acid water management, monitoring and analysis;regular internal and external auditing of procedures and practices; andclosure planning assessments and preparations (ie cover trials, geochemical void modelling, geochemical waste dump modelling). The success of this holistic strategy is evident by the awareness of personnel within the business, thorough understanding of the geochemistry and by undertaking proactive management of black shale during mining. The strategy and management plans adopted by Rio Tinto Iron Ore have activities that other mine sites with potentially acid forming material may like to consider implementing.

Jan 1, 2009

By D C. Curry, M F. Young

Many flotation operations need to improve liberation to increase recovery, yet often plant operators are concerned that finer grinding will produce æslimesÆ with low flotation recovery. Yet simple circuits can be designed to give good liberation and excellent fines recovery. The economics of fine grinding has changed fundamentally with new stirred milling processes like the IsaMill. This has also transformed flotation design due to the clean surfaces produced in the inert grinding environment and the narrow size distribution produced by the IsaMill. Past poor experiences with æovergrindingÆ in flotation circuits was often due to the wide size distribution and the degradation of mineral surfaces produced by conventional devices using steel media, like ball mills and tower mills. The correct practice is to design both grinding and flotation together to suit the liberation characteristics of the ore. This may result in several stages of grinding and flotation, recovering mineral as soon as it is liberated, then applying further grinding energy only to those particles that still need liberation. Flotation then occurs in relatively narrow size bands and with minerals with similar liberation characteristics. Though the circuit may look more complex on paper, in reality it is far simpler to operate since each section performs predicably. Circuit design also needs to address materials handling. Finer particles affect froth handling and dewatering, but can still be easily handled by standard products with careful attention to design of launders, pumps and pumpboxes, and de-aeration before thickening and filtering. Excellent examples of designing circuits to include ultrafine grinding include Mt Isa and McArthur River (MRM). In the last decade these operations have produced over ten million tonnes of concentrate with an average grain size below 10 ¦m and above 80 per cent recovery. At Mt Isa, zinc recovery was increased by ten per cent by applying fine grinding to existing poorly liberated streams. In fact, grinding finer in the IsaMill actually improved the recovery of fine particles by ten per cent, and maximum particle flotation recovery occurs for 10 ¦m particles. A more recent example is the flotation of Platinum Group Metals (PGMs). The use of conventional ball or tower milling to improve liberation is severely limited by the impact of commonly associated chromite on classification, and degradation of flotation performance by the steel grinding environment. The ability of open circuit IsaMills to deliver a narrowly sized ultrafine product with clean mineral surfaces is transforming the design of platinum flotation circuits. The science and practice of fine-grained flotation is now thoroughly proven. The availability of the 2.6 MW IsaMill has made ultra fine grinding a practical tool for flotation plant design. It is expected to become a standard choice for future applications of both fine-grained ores and for minerals with difficult flotation characteristics.

Jan 1, 2005

By Ho D, Yang J

The ready availability of powerful desktop workstations, which combine 3D real-time graphics and processing speed better than that of supercomputers of a few years ago, now allows the cost-effective solution of real world geomechanics and underground mining strength simulations. The inclusion of geotechnical factors such as rock joints and porous flow on strength and stability are discussed together with the range of available deformation and failure models for soil, rock and concrete. This paper describes the capabilities provided by finite element graphics and analysis software for modelling and sequential investigation of both excavation and lining, or rock bolting, construction sequences. Examples of the use of finite element models in mining are also included in the paper, together with a discussion of the required people, software and computer hardware resources required to achieve timely and productive results.

Jan 1, 1995

By C Fountain

Australian mining and engineering companies have increasingly been investing in the mining industry in Brazil. It is a country of enormous mineral and agricultural wealth, with a well-established mining sector. Some Brazilian mining companies and personnel have been journeying in the opposite direction. There are significant differences in the approaches to engineering between the Australian and Brazilian industries that can cause confusion for companies operating in the other country. These range from differing expectations during the various stages of feasibility studies to style of plant and contracting strategies during the construction phase of projects. Some of the differences are driven by tax regimes, labour costs, or different settlement patterns. Others are the result of different histories and pressures on the industries in the two nations.This paper describes some of the differences in approach found in the two countries and some of the reasons for them.

Aug 8, 2011

By Theophili CN, Kapenis AP

Seismic tomographic imaging has been applied to determine the blast induced damage zones in bauxite pillars in underground mining. At the retreating stage, when pillar dimensions are reduced from 8 x 8 m to approximately 5 x 5 m, the' seismic tomographies reveal, through measurements of the P-wave velocities which is a measure of the degree of fracturation of the pillar rock mass, the presence of three zones within each pillar. In the external zone, where velocities recorded are below 750 m/s. extensive pillar damage occurs which is attributed to both the growth and coalescence of pre-existing cracks and even the creation of new cracks in the rock mass. This effect is in agreement with literature, when considering the peak particle velocity as a criterion for rock failure in tunnels. In the intermediate zone, where velocities range between 7S0-1000 m/s, damage to a much lesser extent occurs which is due mostly to growth of pre-existing cracks and widening of their apertures. The inner zone, where velocities exceed 1000 m/s, is considered to be unaffected by blasting. Simple remedial measures of low cost, which are based on blasting mechanics are proposed to minimise the blast induced damage zone and consequently the transition zone.

Jan 1, 1995

By N Patzelt, T C. Logan, I B. Klymowsky

In 2003, NEWMONT MINING CORPORATION, the worldÆs largest gold producer, set out to prove that High Pressure Grinding Roll (HPGR) technology is sufficiently robust and reliable to be considered for the treatment of hard rock gold ores. In collaboration with POLYSIUS, a significant trial was conducted and 127 600 tonnes processed, successfully proving the HPGR capabilities on the Lone Tree Mine, Nevada ore û one of the most competent and abrasive ores in the industry. The success has led a number of mining companies to consider HPGRs for the comminution of gold and copper ores.

Jan 1, 2004

A new test coke oven of seven cubic foot capacity is described. The oven was designed to simulate conditions in a central section of a battery oven and a special feature is the achievement of unidirectional heating from the flues on either side of the charge. The method of charging permits close control of charge conditions'such as bulk density and moisture content. These conditions, as well as coking conditions (e.g. flue temper- atures., coking time) must be varied to simulate conditions in different batteries, The effects of several variables on coke quality are discussed. Using test oven conditions corresponding to those of Newcastle steelworks batteries, good agreement was obtained between strength indices of test oven and battery cokes; for 17 tests, the average A.S.T.M. stability and hardness indices for the test oven coke were 38,5% and 69.7%, while those for the battery coke were 37.1.% and 67.6%.

Jan 1, 1969

By Jagger ND

Pressure filters were found to be necessary to produce Elura silver/lead and zinc concentrates at sufficiently low moisture contents for bulk cargo shipment by sea to smelters.The difficulty in obtaining low moistures was due to the fine primary grind, 80% passing 45 microns, and resultant fine concentrates, 97% passing 45 microns.The filtration system was designed to filter up to 90,000 tonnes/year silver/lead concentrates and up to 130,000 tonnes/year zinc concentrates.This paper details the preliminary test work to select Larox automatic pressure filters, and the commissioning and operation of these filters to achieve design criteria for both concentrates. The design criteria for both concentrates have been bettered due to the concentrates being coarser than the design sizing.

Jan 1, 1985

Sizing is fundamental technology for each step of ironmaking process. The progress of sizing technology has greatly contributed to the development of ironmaking technology. As the purposes of ironmaking operations diversified particularly since the oil crisis of 1973, the sizing technology made new advance- ment, as represented by pulverization of ser- pentine, dezincification and classification of secondary blast furnace dust, pulverized coal injection, size-segregated sinter charging and a coal preparation control process. These techniques are mostly characterized by the fine grinding of a given type of mineral or coal to heighten the degree of reaction con- trol. This trend is expected to continue Further.

Jan 1, 1984

By Larsen D. F

Minor iron formation related base metal sulphide mineralization occurs in granulite facies metamorphic rocks of the early Proterozoic Willyama Complex. Rock sequences hosting three iron formation related Cu, Zn, Pb prospects from the Thackaringa Group (Suite 3) are described. A caparison of host rock sequences, style of mineralization and facies of iron formations suggests major differences in terms of the overall depositional environment. However, significant similarities are present with respect to the nature and distribution of iron formation facies and the occurrence of chlorite 'alteration' zones in close proximity to mineralization in all cases. The chlorite within these zones occurs in a number of diverse forms in a range of rock types. A comparison of the prospects shows that there is no evidence to indicate that the chlorite in the zones is a retrograde alteration product of former higher grade prograde mineralogies - the chlorite appears to have survived granulite facies metamorphism. The mode of occurence of the chlorite in the 'alteration' zones together with the fact that the association quartz + chlorite + magnetite + pyrite + base metals is cx rmn to all areas suggests that the chlorite is specifically related to the processes which deposited the stratiform iron formations and related sulphides. It is considered that the chlorite precursor was a prenetanorphic alteration product or chemical sediment closely related to submarine hot spring activity which was also the source for chemical sediment precursors of the iron formations, associated lode rocks and Sulphides.

Jan 1, 1983

Probabilistic seismic hazard analyses (PSHA) have now gained wide acceptance in the development of design criteria for major projects. When used with regional criteria the procedures have also allowed the preparation of more rational seismic zoning maps. Seismic zoning maps using various levels of results from PSHA studies around the Pacific Rim now include Canada, Indonesia, New Zealand and the United States. Some Pacific Rim countries such as Chile where the seismic exposure is dominated by subduction events have no subdivision into separate zones.Approaches to risk based zoning are being considered in several Pacific Rim countries including Australia. Australian studies must face problems similar to parts of the Eastern United States where seismic activity is low with irregular and infrequent occurrences of moderately large earthquakes. The perception of the seismic exposure by both regulatory agencies and the public at large is different when considering areas of low seismicity. There is therefore a need to make different interpretations of the results of PSHA studies in these areas of low seismicity. The aim of this paper is to explore some of these differences by comparing the results from two site specific studies from areas with widely differing seismic activity rates.

Jan 1, 1990

The phenomenon of Instantaneous Outbursts, although not new to Australia, was sharply drawn to the attention of the local coal-mining industry by two isolated fatal occurrences on widely separated fields, both late in 1954. An outburst is the eruption of apparently solid coal from the face, aided by vast quantities of gas released from the coal, as the coal fails under mining stresses additional to its natural stressing.The gases involved are principally methane and carbon dioxide. The various factors which combine to produce outburst conditions range from external factors such as stresses arising from depth of cover and other causes, to inherent factors such as strength of coal,and its capacity to retain gases (sorption). Of the localities where instantaneous outbursts occur the Gard Basin in Southern France has had the greatest number and the most serious occurrences. By contrast, local outbursts have been minor.Experimental work into some influencing factors has been carried out by various overseas authorities and some research has been accomplished in Australia. Practices used in some overseas areas to improve safety of working are largely empirical, as are the local rules and recommendations for work in affected areas.The appearance of further outburst areas is anticipated as mining becomes more extensive and deeper.INTRODUCTION"Instantaneous Outbursts" can be described as violent eruptions of coal from the solid accompanied by considerable gas evolution. The projected coal is usually of small size, and a high proportion is pulverized, and may be carried and deposited over great distances by the gases, liberated from the outburst. This outburst coal is of bituminous to anthracitic rank, and the gas involved is essentially methane or carbon dioxide, or a mixture of both. Outbursts involving carbon dioxide are usually more violent and dangerous. The phenomenon is relatively unusual, being confined to probably sixteen known areas in the entire world, these areas comprising only portion of the coalfields in which they occur. Usually only one or two mines on each field are affected.

Jan 1, 1958

The Rosebery Mine on the west coast of Tasmania is a world class polymetallic base metal deposit, containing six major minerals: galena, sphalerite, chalcopyrite, gold, silver and pyrite. This resource has been exploited for nearly a century, yet a reliable estimate of the reserve continues to present a challenge.Over the past twenty years, the operation has changed from relatively low productivity cut and fill timber-support scraper mining, to higher productivity bulk mechanised open stoping. At the same time, economic constraints have changed and grades have fallen, which have increased the pressure to refine the resource/reserve estimating processes. This paper compares the restrictions of the polygonal section method of the past with the advantages of a kriged block model. The limitations of Mine Call Factors, the problems involved in converting decades of diamond drilling data on paper into a computer data base, and the effect of this new methodology at Rosebery, are described.

Jan 1, 1990

Introduction.History of Stope Filling at Mount Isa.The Need for a Systematic Fill Programme.Reasons for Filling.Fill Materials and Tonnages.Rough Mullock Fill.Quantities Readily Available.Fill Pass Development.Stope Preparation.Drainage.Hydraulic Sand Fill.Initial Experiments with Mill Tailings.Surface Layout.Operation Procedure.Underground Pipe Lines.Life of Sand Pipes and Cones.Drainage.Old Tailings Dam Sands.Quantity of Fill Placed.Pillar Tonnages.Conclusion and Acknowledgment.INTRODUCTIONFilling practice outlined in this paper refers exclusively to the Black Star section of the mine. The stope filling necessary early in the life of the Black Rock and portions of the Rio Grande sections is not to be confused with the current filling programme.

Jan 1, 1953

By R Minnitt

Two methods of calibrating the parameters K and Alpha for use in Gy’s formula for the fundamental sampling error were investigated. Approximately 480 kg of broken ore from Harmony’s Target gold mine in South Africa was used to compile the replicate samples for two experiments. The duplicate series analysis (DSA) and segregation free analysis (SFA) methods differ in terms of their approach to recovering the sized materials required for the calibration procedure. In this experiment the DSA method split off six more-or-less equal masses of material from a 75 kg lot that was successively crushed to finer and finer fragment sizes. The sublots so formed were split into 32 samples and fire assayed for gold. The SFA method used approximately 250 kg of broken ore crushed to 95 per cent passing 2.50 cm, which was then passed through successively finer screens until a sublot of less than 0.0075 cm was obtained. Each of the 15 sublots obtained in this way were split using a riffle splitter into 32 samples that were fire assayed. A total of 672 fire assays were used in these experiments. The sampling parameters K and Alpha were used for the compilation of a nomogram and to calculate the gold liberation size of the ores. While there are no definitive results in terms of the actual gold grain sizes against which the calculated sizes can be compared, it appears that the DSA method produces more acceptable results.CITATION:Minnitt, R, 2014. A comparison of two methods for calculating the constants K and alpha in a broken ore, in Proceedings Sampling 2014 , pp 165–178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By T Horberry

This paper describes work conducted as part of an overall research project that aims to identify current and emerging trends in the development of automation and remote mining technologies, and to provide an operator-centred perspective to the design and deployment of such systems. More specifically, this paper outlines a research and development process being constructed to examine the issues of the human skills and capabilities required to operate or maintain automated/remote controlled mobile mining equipment. A human factors approach presented here, where the focus is upon designing equipment interfaces to fit operators, rather than purely designing and deploying the equipment based on a technology-centred approach. However, the importance of training to help develop the required skills and capabilities is also emphasised.The work built on a full review of the literature about the effects of automation in mining and elsewhere, extensive interviews with different stakeholders in mining automation and recognised best practice regarding designing for the human element in automated systems. The human element research and development process proposed is in four stages, ranging from understanding the tasks involved in both manual and automated equipment operation through to user trials to ensure that the automated systems are acceptable to operators and are fit for purpose.It is outside the scope of the current paper to present the full data collection described by this four stage process, but an overview of what will be collected is presented. As such, this paper focuses on the broad methods being developed, rather than the specific results to be obtained. The ultimate objective is to apply a broad ‘technology assessment’ approach to the design, deployment and evaluation of automated mining technologies, in particular by considering the user-centred design implications of these technologies.

Nov 22, 2011

By A A. Roberts, R F. Dewhirst

"Extensive literature surveys, research in the project environment and personal experiences both within and consulting to project teams have revealed some consistent ‘people factors’ that contribute most to ultimate project success. Outside of purely technical and business case issues, there are a small number of leadership characteristics – probably only ten – that if correctly applied can positively leverage a team’s impact on project success.Of the top seven project success characteristics that were consistently highly rated in a recent study, five of them were around leadership. The authors have focused on this topic, noting that good leaders need to display the following traits:passionate commitment to deliveryconsistent modelling and reinforcement of correct values and behaviourfocus on managing relationships well and energising teams and individualscarefully clarifying project vision from front-end loading stages onwardseffective decision making.Not every project manager can and does practise these behaviours all of the time, but being aware of them and receiving training or facilitation in improving their application of these skills can equip project managers with the essential tools to markedly improve their own performance and that of their teams.This paper draws upon experiences in the field and provides lessons – both good and bad – to illustrate. As well as examining leadership traits, the way in which a leader can establish, organise, motivate his or her team and ultimately lead them to success is examined. The paper shares methodologies that have been successfully used to track status within a team and generate appropriate recovery plans where required.In particular, the paper will examine a case study based on an amalgamation of real project issues in some challenging situations using virtual teams (ie physically distant teams located in different centres) to illustrate the importance of strong and positive leadership in achieving success across geographies, time zones and languages.CITATION:Roberts, A A and Dewhirst, R F, 2016. Leadership in projects – a recipe for success, in Proceedings Project Evaluation 2016, pp 49–58 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By J Pearce, R Ramanathan

hortly after the World Health Organization declared COVID-19 a pandemic, the words ‘social distancing’ entered the global lexicon. The effects on the public of social distancing, lockdowns and travel bans are well documented. They also present unique challenges to the mining industry. For Hexagon’s Mining division, this posed a significant challenge. We have built our business – our reputation – on regional, customer-focused service and support. True to Hexagon’s values of being professional, engaged and customer-focused, we innovated to overcome the distance dilemma. Making automation a reality for our customers by implementing and supporting technology projects from a distance has helped deepen partnerships by making it easier to tap into our global experts’ knowledge. For example: • Body cameras were at the heart of a successful safety installation at a mine in Ghana. Despite the pandemic lockdown preventing travel by our South Africa staff into Ghana, the project was completed with minimal delays. • Traditionally, implementation and training for our Blast Movement Technology solution is done physically at the mine site. With COVID-19 travel restrictions in place, we have developed and successfully employed a remote deployment methodology. • Using RealWearTM headsets in the field and utilising the knowledge management platform from HINDSITE, Hexagon workshop technicians have been able to support hardware repairs in local offices, which once would have been undertaken in our overseas offices. • The same headset is being utilised to provide clients with remote mentoring sessions by our skilled team members who are based in our regional locations and unable to travel to their site without extensive quarantine commitments. • In instances where our team members have had to travel to site, we have provided consumer technology such as VR headsets to help them cope with long periods of quarantine to and from site. Post-pandemic, Hexagon will continue to refine and improve this method of working. INTRODUCTION Shortly after the World Health Organization (WHO) declared COVID-19 (COVID) a pandemic, the words ‘social distancing’ entered the global lexicon. As governments, healthcare organisations and the public scrambled to respond to the crisis, one thing became abundantly clear: isolation was and, for most of us, still is the key to maintaining our health. Hexagon, a leader in sensor, software and autonomous solutions, was well positioned to pivot and assist in the global response to the crisis. From simulations of the effects of social distancing to mapping the spread of COVID in real time, to drone technology delivering COVID tests, to providing communities with transparent geospatial information, Hexagon solutions continue to help ensure that innovation is readily available to those who need it most during uncertain times. The effects on the public of social distancing, lockdowns and travel bans are well documented. They also present unique challenges to the mining industry.

Jun 22, 2022

By Forrester P. I, Richardson W

Methane in coal mines is an ever present hazard resulting in loss of lives and serious economic consequences. For effective control of methane, ventilation alone may not be totally adequate in some situations. In order to deal with such cases, new methods for the control of methane are being researched. One such method based on biotechnology has been investigated in Canada in the past several years. This method involves bringing methane oxidizing micro- organisms into contact with coal to oxidize the methane released to non-flammable products.

Jan 1, 1988