Search Documents

By A Thompson, E Villaescusa

The Western Australian School of Mines (WASM), Kalgoorlie, has been performing dynamic testing of reinforcement systems as part of the Minerals and Energy Research Institute of Western Australia (MERIWA) Projects M349 and M349A sponsored by WASM, the Western Australian State Government and the mining industry. These projects have resulted in the construction and commissioning of the WASM Dynamic Test Facility and a program of reinforcement system testing. The primary purpose of the WASM projects is to evaluate the performance of complete reinforcement systems when subjected to an axial dynamic load. The test procedure, monitoring and associated analysis enable assessments for each component (ie the element, the internal fixing mechanism and the surface hardware) of the reinforcement system. The performance of a reinforcement system is usually defined by a static force-displacement response to axial loading. However, this static response may not be applicable to dynamic loadings associated with violent failure of rock due to overstressing as mines progress to greater depths. It was therefore appropriate that the responses of reinforcement systems subjected to dynamic loading be defined and evaluated. The key findings from the tests on a number of reinforcement systems are presented and recommendations made regarding their application for dynamic loading.

Jan 1, 2008

Sampling is an integral part of gold bullion analysis. Gold mining industries sell millions of dollars worth of gold on the basis of analyses. Biased sampling can cause a serious loss in terms of monetary value to a mining company; hence accurate sampling is of great importance. The sampling procedures for gold bullion will be described. Emphasis is given to the most reliable method of obtaining a representative sample from a gold bar. The problems associated with sample preparation will also be discussed.The sampling procedure at the Kalgoorlie Metallurgical Laboratory will be evaluated in the light of comparative results from the Australian Gold Refineries (Perth, Kalgoorlie). The most common sampling practices adopted by different gold mining companies in the Goldfields and Australian Gold Refineries, Western Australia will also be presented.

Jan 1, 1976

Kensington is a joint venture between Echo Bay Mines and Coeur Alaska, a subsidiary of Coeur d'Alene Mines Corp. The venture is of equalparticipa- tion and is governed by a management committee with Echo Bay as the operator. The project site is 50 miles north of Juneau, Alaska on the eastern shore of the Lynn Canal. The mine and mill are being planned for a production rate of 4,000 stpd. Currently, probable reserves stand at just over 11.3 million tons grading 0.149 oz Au/ton. The project is now in final feasibility study with a production decision anticipated by the end of 1990. Commercial production would begin early in 1993. This presentation dis- cusses the anticipated mine, mill and support aspects of the project.

Jan 1, 1991

The word `environment' may have many different meanings but, for the purposes of this paper, I have assumed the definition included in the Environmental Protection Act 1986 (Western Australia). This Act defines `environment' as `... living things, their physical, biological and social surroundings, and interactions between all of these'. The Act further defines the `social surroundings of man' as `... his aesthetic, cultural, economic and social surroundings to the extent that those surroundings directly affect or are affected by his physical or biological surroundings'. This gives a very broad meaning to the idea of environment and environmental issues, and it is therefore understandable that the influence that environmental issues have on mining activity can vary so much from state to state, and even within states, and why the degree of influence can change so much with time.

Jan 1, 1990

By Hutchinson H

Froth flotation is applied to mineral sand concentrates in order to produce commercially viable xenotime concentrates. Experiments indicate that a xenotime product containing 38% Y203 at 47% recovery or 34% Y203 at 83% recovery can be obtained from a 27% Y203 feed. The process involves a primary stage of reverse flotation at which oxide and silicate gangue is floated, and secondary stage of direct flotation at which xenotime is floated. Of the various collectors screened an amphoteric compound was found to be effective at both stages. This was made possible by the addition of sodium silicate at the second stage, which acted as depressant for the remainder of the gangue. Similar studies on a low grade feed material were somewhat unsatisfactory as the grade achieved fell short of what was targeted.

Jan 1, 1990

Sampling systems are never perfect. They all have some bias and give variable sampling errors. The ways of thinking about bias and precision should be different before and after construction (or reconstruction) of a sampling system. Before a sampling system is constructed, the fundamental error variance can be estimated using GyÆs formula or by doing test work on the material to be sampled. The component of sampling variance which varies with the number of sample increments can be computed for the expected patterns of grade variation. The smallness of the bias can be checked using discrete element modelling, by checking that the proposed design complies with clauses in standards, or by copying an existing sampling system that performs well for similar material. After a system has been constructed, sampling precision can and should be monitored directly. Anyone claiming to take responsibility for a sampling system should know its precision. Bias could be checked by comparison to a more accurate sampling system, such as stopped-belt sampling, under conditions where bias seems most likely. However, it is more practical to conduct regular checks that the system is still operating as designed, that the design is still appropriate despite any changes to material flows, and that sample masses are consistent with the correct operation of the sampling system. If precision is not regularly assessed then it should be assumed to be very poor. If a sampling system is not regularly inspected then it should be assumed to be biased.

Jan 1, 2008

It may at first sight appear somewhat presumptuous for the writer to attempt to discuss a subject in which he cannot pretend to possess any special scientific training; but a sufficient apology can surely be found in the fact that a very large percentage of the accidents from explosives occurring in metalliferous mines is traceable to the ignorance of the characteristics of these compounds by the miners who have to handle them, and to their deliberate disobedience of the rules laid down for their guidance by the manufacturers, the government regulations, or the special rules of the mines.The only method which promises any possibility of improvement upon these conditions is to substitute reason and understanding for the rule-of-thumb principle which says "you should do this" or "you should not do that." In the one case his own knowledge and intelligence enables the miner to avoid any dangerous practice in the other his inclination prompts him to do anything which will save time, provided he is not found out or at best trusting to his memory to tell him what is dangerous, without the reasoning which makes that memory easy.Another evil of rule-of-thumb knowledge is that, from its very nature, it prevents adaptability, and so we find that old miners, who learnt blasting in the days of black powder, cannot understand why high explosives do not require heavy tamping, or because copper bars are permitted in tamping powder they should not be used with other explosives...

Jan 1, 1903

By M Rispin, R Karlson

Chemical admixtures are not commonly included in the variety of backfill mixes used in the mining industry. This may be attributed to several reasons including, but not limited to: the perceived high added cost, the lack of awareness about their proper use, and the lack of knowledge about their features and benefits. In the construction industry today, however, chemical admixtures are used in the majority of the concrete produced, enabling concrete to become a more cost-effective building material. They also enable construction crews to meet demands for year-round construction, quicker completion of construction projects, and improved concrete properties. The high demand for chemical admixtures in the construction industry has led to numerous innovations in admixture technology in recent years. Some of these chemical admixtures have been found to enhance the production, transport, placement, and in situ properties of backfill mixes. Others have been found to reduce the cost of such mixes while maintaining, and in some cases improving, their physical properties. In this paper, a few of such innovative admixture technologies are discussed. The benefits, imparted by these technologies to backfill mixes as well as performance data on their use in several backfill applications at various mines, are presented.

Jan 1, 1998

By S Freij, P W, R Gunawan, D Zhang, B Feng

The Mt Whaleback iron ore mine is located adjacent to Newman, approximately 1200 km north of Perth, in the Pilbara District of Western Australia. Approximately 15 per cent of the waste materials are in the zones with high concentrations of sulfide and carbonaceous minerals and are referred to as æreactive shaleÆ. The reactive shale has the potential to undergo self-heating and can react with the ammonium nitrate (AN) based explosives used in mining operations, resulting in spontaneous combustion and spontaneous explosion. The sulfide-rich shales also have the potential to produce acid rock drainage (ARD). In the present study, over 200 shale samples have been collected from different locations in the Mt Whaleback iron ore mine, including blasthole drill cuttings, fresh mine faces and waste dumps. These samples have been systematically characterised for their geochemical properties. Based on the characterisation results, a pH test was developed as a cost-effective, fast and efficient tool for the assessment of reactive ground in the mining industry. This paper summarises the results of the sample characterisations and discusses the key findings arising from the interpretation of results. These results have significant implications in the safe storage of the reactive shales and the prevention of spontaneous explosion, spontaneous combustion and ARD.

Jan 1, 2005

The Olympic Dam mining operation is some 520 kilometres NNW of Adelaide on the Roxby Downs Pastoral lease. The deposit containing copper, uranium, gold and silver was discovered in 1975 by Western Mining Corporation (WMC). A joint venture was formed in mid-1979 between WMC (51 per cent) and British Petroleum (BP, 49 per cent) for the development and exploitation of the deposit. WMC assumed 100 per cent ownership after acquiring BP's share in early-1993. Ore is won from a highly mechanised underground mining operation and processed to refined products. Current annual output from the mining of 3.0 Mt of ore is approximately 83 500 t of refined copper, 1400 t of uranium oxide, 750 kg of gold and 12 000 kg of silver. Conventional long hole, open stoping techniques are used to extract the production ore. Since stope production began in April 1988, full surveys and appraisals of stopes have been carried out to evaluate the integrity of the design and blasting techniques. This evaluation included the determination of the degree of dilution or non break that had occurred. Performance information also made it possible to re-design any adjacent stopes to retrieve remaining ore and conversely, avoid the chances of targeting backfilled material in the future. Performing stope surveys proved not only to be a time-consuming process but one fraught with access and line-of-sight problems. Occasionally it was not possible to obtain any stope survey data, and as was often the case with the mine pass system, rarely. In 1992 the sudden failure of the pillar between the fine ore and mullock passes and the subsequent delays to production, emphasised the need to effectively monitor pass wear. Initial information regarding the development of the Cavity Measurement System (CMS) prototype (Figure 1) indicated that it had the potential to solve these problems by the introduction of a remote scanning device into a cavity. Following a great deal of investigation, Olympic Dam Operations purchased the first CMS in Australia. This paper discusses its application for all underground void surveys and the procedures developed to manage both field and office requirements.

Jan 1, 1995

XstrataÆs Mount Isa Copper Operations (MICO) is a world-class mining operation producing in excess of six million tonnes of copper ore per annum from its underground mining operations. The Mount Isa Copper Mines have been producing from the underground operations since 1952. Current copper reserves are 87 million tonnes at 2.8 per cent Cu, extending the mineÆs life beyond 2018. The underground orebodies in the copper mines are divided into nine distinct areas and are mined by sublevel open stoping techniques. One of the nine areas is the hanging wall lens, which consists of two sections; a northern lens (NHWL) and a southern lens (SHWL). The SHWL has a proven reserve of 2.2 million tonnes with an average grade of 2.9 per cent copper. Stopes in the SHWL have an average size of approximately 245 000 tonnes and will be extracted in a primary-secondary mining sequence, producing ore until 2009. This paper discusses various aspects of stope design applied in the southern hanging wall lens, including sequencing options and the rationale for the selected sequence. Design features are also discussed and how they have evolved as more is learnt about the SHWL orebody. These include mass firing techniques, focusing on minimising ground vibrations, using seed wave form analysis and prediction. Rock mechanics issues will also be discussed, in particular the reinforcement of stope hanging walls and the use of instrumentation to monitor behaviour within the hanging wall.

Jan 1, 2006

Iron ore in the Pilbara Region of Western Australia varies in composition giving iron ore a range of densities. An accurate density figure of the material leads to accurate calculations of production throughput. Density studies of two separate iron ore mines were conducted in the Pilbara. Procedures and results are reported here.The Pilbara Region of Western Australia has a number of iron ore operations. Two mines have conducted density studies of their materials. The purpose for the studies was to determine an accurate in situ bulk density that could be applied to volume and tonnage calculations of the operation. It was identified that density was one culprit causing calculation variations. Density is an important figure used to estimate ore reserves, equipment requirements, production rates and indirectly costs and sales revenue. One study was conducted at Rio TintoÆs Robe River Mine based near the town of Pannawonica. Its Mesa J orebody is currently being mined and is a low-grade deposit of goethite and hematite (Burnham, 2003). A separate study was conducted at BHP BillitonÆs Yarrie Mine situated north of Newman and east of Pardoo. Its orebody consists of high grade formed by a supergene enrichment of cherty material and a burial metamorphism to produce hematite (Richardson, 2002). The method used to determine density was by large-scale samples using the pre-mining in situ volume of the material and the weight in tonnes after mining.

Jan 1, 2003

The AJ Parker Cooperative Research Centre for Hydrometallurgy is the focus of a world-class effort in providing technical solutions to the minerals industry. The 85 FTE staff are drawn from the CentreÆs five joint venture research partners comprising universities (Curtin, Murdoch and Qld) and government research agencies (CSIRO and WA Dept of Industry and Resources). There are also 12 industry partners, representing most of the leading mining companies in the world. Around 45 postgraduate students, mainly PhDs, make a significant contribution to the research effort. Total annual expenditure on R&D is around $17 million.Hydrometallurgy activities encompass both fundamental and applied research across the alumina, gold and base metal sectors. The Centre is now growing its client base into overseas markets, particularly North America, South Africa and Europe. Quality, strategic R&D by the Parker Centre is seen by the industry as an attractive investment. A recent survey of the industry revealed an estimated ten-fold return based on direct costs of research to the client. In addition, the Parker Centre has a strong commitment to education of postgraduate students wishing to enter the mining industry as well as providing specialist courses for those technical professionals already employed in the industry. The wide range of employment opportunities in the mining industry is reflected in the diversity of the disciplines amongst the CentreÆs research team, eg extractive metallurgy, chemistry, biotechnology, physics, engineering, molecular modelling, microscopy, geology and computational fluid dynamics. How does an atomic force microscope and molecular modelling improve our ability to control gypsum scaling or understand crystallisation of alumina in a Bayer plant? Can a biologist contribute to the problem of the slow leaching of copper from chalcopyrite? Why are computational fluid dynamics and lasers the basis of understanding how to make thickeners work more efficiently. Can you combine a PhD or Honours degree with industry experience? What is crud and why is nickel stressed? These are typical examples of the CentreÆs research activities and demonstrate the contributions of its multi-disciplinary teams which keep the Australian mining industry at the cutting edge of advanced global technology.

Jan 1, 2003

By Davies B, Rogers A, Grainger A, Todd J, Brenman R, Jones L, Horton B, Eager L

Research into the control of diesel particulates (DP) has been. conducted by BHP Coal for more than 7 years. Personal monitoring of employee exposures (n = 480 full shift samples) conducted at nine underground coal mines has indicated that the exposure of the workforce ranges from less than 0.1 to 2.2 mg/m3 of DP dependent on job type and mining operation. Approximately 50% of the mass of DP captured is elemental carbon (EC) which is the species currently being considered by some international regulatory authorities as the exposure standard. Five technologies for controlling DP were investigated in a combination of studies conducted in an above ground simulated tunnel, in a special controlled section of underground mine roadway and validated by application in standard coal mining operations at Tower Colliery. Tests conducted under controlled conditions indicate that dependent on the type of fuel in use, the introduction of low sulphur fuels can reduce DP levels in return airways by up to 50% and in actual mining situations a reduction of 20% can be achieved in exposure of the workforce. In addition, subjective responses from the workforce indicate that exhaust emissions from low sulphur fuels provide lower irritation and a more pleasant aroma. The use of water filled scrubber tanks reduces the level of DP emissions by 25%. Chemical decoking of engines resulted in a reduction of 20% in DP in return airways. A commercially available non-flammable disposable dry exhaust filter constructed from synthetic organic fibres with an operational lifetime in excess of 20 hours was found to reduce DP exhaust emissions by 80%. Investigations have indicated that the use of increased ventilation to control DP levels particularly in multiple vehicle situations does not follow a simple dilution factor and in some instances compliance with current regulatory requirements may not produce the required reduced exposure levels. The results from single component control strategies provide considerable reduction in exposure to DP, however the most efficient and cost effective control methodology is the use of a combination of individual systems modelled to operations conducted at each mine.

Jan 1, 1998

The coastline is. an incomparable stretch of sea coast known as Ninety Mile Beach. Two gas pipelines and two oil pipelines carrying hydrocarbons from thb'Bass Strait fields to the markets of Australia cross this beach. They cannot be seen as they are laid in trenching stretch- ing many miles out to sea and the beach was restored to its natural state. Even where the dunes were disturbed, suitable grass was sown thus consolidating the sand and preventing erosion. Ninety Mile Beach is but one of the many key.wildlife and recreational areas that our operations must be concerned with. Others include Westernport and Corner Inlet, but the one discussed in this paper in particular is the platform area of the Bass Strait itself. Never was the old adage "an ounce of prevention is worth a pound of cure" more meaningful than in offshore oil production. All are well aware of some of the events of the past several years that resulted in large and costly oil spills. Far less is known, seen or publicised about the measures and developments that are undertaken to ensure that such events do not occur. We also have well developed plans for response in the event of an emergency situation, which can be initiated with great rapidity. Our responsibility is to ensure that with the best of engineering technology and operating procedures, spills do not occur.

Jan 1, 1971

Interpreted geologic domains provide the geologic architecture of many current models used to estimate the potential economic resources in mineral deposits. The spatial extent of each domain is usually defined by a three-dimensional wireframe or triangulated surface.The set of geologic wireframes forming part of a resource model might generally be called a spatial interpretation of some set of geologic features coincident with the mineralisation, based primarily on logged and mapped properties of the samples and other exposures of the mineralisation. The interpreted spatial distribution of rock type, alteration and grade of drill hole samples above a particular grade threshold are commonly used criteria in constructing the geologic domain wireframes. Frequently, the grade threshold is closely related to the anticipated economic cut-off grade. The boundaries or spatial limits of different domains are most commonly defined as æhardÆ or æsoftÆ. A æhardÆ boundary usually means no dependent relationship of any kind is defined between the properties of samples inside a particular domain wireframe and those samples outside the wireframe. A æsoftÆ boundary commonly implies that some kind of dependent relationship does prevail between the properties of samples inside and outside the particular wireframe. Many ways are used to describe those relationships, few of which are based on spatial analysis of the continuity of sample attributes across the domain boundaries. In local estimation procedures such as ordinary block kriging, æhardÆ boundaries act as a total barrier to the influence of samples on either side of the boundary depending on the location of the block being estimated. In some instances, æsemi-permeableÆ boundaries are used in which the samples inside a domain wireframe are allowed to influence the estimates outside but not the reverse. This can lead to many undesirable effects in estimates of block grades.This paper discusses the value of this approach to geologic domaining from a viewpoint of model complexity, as well as in relation to the implications for both linear and non-linear estimation methods and contrasts it with alternatives. It also explores some important consequences of using æhardÆ and æsoftÆ geological boundaries with the commonly used modelling methods: excessive smoothing of estimates near domain boundaries and conditionally biased estimates of grade at the global and local scale.

Sep 26, 2011

By Hood M

Rock cutting excavation technologies and particularly continuous excavation technologies, can offer benefits in the areas of reduced costs, higher revenue and increased safety in a variety of mining situations. Non-explosive rock excavation technologies for example, can deliver significant benefits in the areas of dilution and improved ground support (no overbreak). This paper is an attempt to focus on the development and future of alternative rock breaking technologies and to provide some insights as to why and how we should proceed in this direction. The market size for underground hard rock excavation technologies is examined. A short review of the evolution of various rock excavation technologies in terms of cost and production rate is given and a summary of the state-of-the-art technology is presented. Mechanical excavation technologies (TBM) have very high production rates compared to D&B and the gap is widening, however, they have not been successfully applied to mining applications. Operating costs for mechanical and D&B systems have been dropping over time, however, D&B costs are the lowest. Given the current state of knowledge it appears that with regard to hard rock underground metalliferous mining that R&D efforts should be focussed in the following areas - disc cutter tool development (materials and design; operation; presentation to the rock surface), hybrid cutting systems (consisting of water jets and disc cutters) and development of pressurised hole breakage technologies. It is also possible that two techniques known as the pulsed laser and pulsed water jets may have some potential. The generally agreed specifications for a widely applicable underground hard rock excavating machine are - disc cutter based, a minimum production rate of 100 t/h, be flexible, manoeuvrable and deployable, weight of less than 100 tonnes and be economically competitive with D&B in rocks over 150 MPa UCS. Such a machine would seriously challenge the position of conventional D&B in a wide range applications and provide some of the benefits of mechanisation and automation that the mining industry is pushing so hard for. However, technology developments in the D&B area are not static and hence the target is moving and is increasingly difficult to overtake.

Jan 1, 1995

By Y K. Leong

Iron ore tailings typically containing 40 to 50 per cent Fe can be beneficiated to iron ore products containing 54 to 60 per cent Fe. The impurities are comprised of clay, quartz, cristabolite and TiO2. Goethite and hematite are also present. At high concentrations of 55–60 wt% solids, the tailings displayed high yield stress and viscosity and cannot be pumped over long distances. Composite additives comprising of NaOH, phosphate-based additives and sodium metasilicate are found to reduce the viscosity and yield stress very significantly by a few orders of magnitude. The yield stress of 100 Pa can be reduced to almost zero. At this state, dilution of the tailings with its process water to 40 per cent solids causes the coarse and high-density iron ore particles to separate from the colloidal fractions located in the supernatant after a few minutes of sedimentation. Separation by decantation produces a sediment with an Fe content of 54 per cent from tailings with 47 per cent Fe. Another tailings sample with 48 per cent Fe was beneficiated to greater than 57 per cent Fe using NaOH-metasilicate-polyphosphate additives and employing an additional washing step. The use of other composite additives, NaOH and polyphosphates, increased beneficiated product Fe content to greater than 60 per cent from the same tailings. With the current iron ore spot price of more than US$180 per tonne, the cost of this treatment process even including a desalination step, if necessary, is relatively insignificant. This study has given tailings an economic value that should be exploited as soon as possible.

Nov 8, 2021

By A M. Robertson, R Lefebvre

Air movement and associated oxygen transport through waste rock dumps has the potential to significantly enhance the rate of oxidation of pyrite-bearing material. While this is a desired outcome for most heap leach operations, airflow in waste rock storage facilities can result in significant increases in generation and acceleration of acid rock drainage. Hence, a good understanding of internal airflow through waste rock dumps is required to control ARD and minimise any associated liability. The principal mechanisms contributing to airflow and oxygen transport in a waste rock pile include: diffusion; advection due to a thermal gradient (chimney effect) and/or wind pressure gradients; and advection due to barometric pumping. While diffusion is typically limited to a near-surface zone of a few meters depth, advection and barometric pumping have the potential to move air (and oxygen) to much greater depths into the pile. In general, the more permeable the waste rock material, and the greater the height-to-width ratio of the waste rock pile, the greater is the potential for advective air movement. The reactivity of the waste rock material as well as the coarseness (hence air permeability), and the spatial variability of these properties within a pile, have a strong influence on the magnitude of thermally induced advection. In contrast, air movement due to barometric pumping is controlled by the waste rock porosity, changes in ambient air pressure and the heterogeneity of air permeability of the waste rock dump. Results of field monitoring and numerical modelling using TOUGH AMD are presented to illustrate the concepts on air movement in waste rock piles discussed in this paper. During the design and construction phase, airflow can be controlled by judicious placement of reactive waste rock and use of selective placement techniques to control the internal structure of the waste rock facility (eg introduction of horizontal layering, prevention of inclined, high-permeability, channels (æchimneysÆ)). Several closure measures are available to minimise airflow including: placement of a low-permeability cover to reduce air entry; and placement of a non-reactive cover material to isolate reactive material from the zone of active airflow and/or regrading of the waste rock pile to obtain a geometry and internal structure less susceptible to advective airflow.

Jan 1, 2003

Geotechnical practice combines the site engineering geological model with engineering design and operations to control risk. The responsibility of the geotechnical professional is to present relevant engineering geological information to an engineer to effectively impact an outcome. Return is enhanced by understanding expected operating and capital cost due to ground conditions.   Risk is effectively communicated by a successful geotechnical practitioner. In a mining environment the need is to assess ground conditions accurately and quickly, and to effectively communicate expected ground response due to mining. A good engineering geological model includes a description of geotechnical engineering parameters to design assuming reasonable expected soil, rock and water conditions. Pit slopes are steepened, stope spans widened and waste foundations and land forms are constructed all under geotechnical control.   The responsibility of the geotechnical professional is to collect, assess and disseminate relative engineering geological information. The geotechnical professional is a person advising on ground related engineering, and generally operates within geology and engineering end members.   Return is better assessed on an understanding of ground cost. In operations the goal is to meet production at lower cost. In evaluation, regional and exploration geology, mine design and expected operational factors influence expected cost and project return. Return allows companies to meet shareholder expectations, attract equity to develop and add value to the community.   This paper presents a discussion with some examples to present an approach and design philosophy for geotechnical practice in the mining industry.

Jan 1, 2004