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By H M. Parker, G Verly, T Postolski

Assessing the uncertainty and risk in mineral resource estimation is required for best practice and is implied by the public reporting codes in the categorisation of mineral resources and reserves. One industry best practice is quantifying the risk on future production for a given period, which can be done using two geostatistical approaches: conditional simulation and drill hole spacing studies based on estimation variances. Conditional simulation can provide a more complete and flexible answer to the problem, but it takes a fair amount of time to complete. Drill hole spacing studies are simpler, faster and can provide reasonable assessments of mineral resource uncertainty.This paper is a presentation of the principles, theory and practice of drill hole spacing studies. Various types of risk assessment are considered. Difficulties encountered in practice are discussed, and solutions are proposed. The important parameters impacting the results are reviewed. Examples of results and sensitivities are shown.CITATION:Verly, G, Postolski, T and Parker, H M, 2014. Assessing uncertainty with drill hole spacing studies – applications to mineral resources, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 109–118 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By J Pan, G Qiu

In this paper, an analysis is made of the present situation in the Chinese steel industry and its demand for iron ores. It is shown that the demand for iron ores has been growing substantially with the rapid development of the steel industry all over the world, especially in China. However, the iron ore market is currently in the situation where supply exceeds demand due to the economic crisis, with more investment in mines and less output of steel for several years ahead all over the world. Gigantic pressure is confronting the Chinese steel mills due to the too high and irrational price of iron ores. It is time to return the price of iron ores to a normal position much closer to their value. More attention has therefore been paid to developing low-grade and complex iron ore resources in China due to the irrational price of imported iron ores. More innovative mineral processing processes have been developed to tackle these complex resources. A systematic introduction to the development of beneficiation processes for low-grade iron ores is provided, including upgrading low-grade siderite, limonite, micron sized haematite and magnetite resources.

Jan 1, 2009

Solid EnergyÆs project evaluation process utilises a standard staged gate approach, with five levels leading ultimately to project execution (level 6). For a project to progress through each level, specific financial criteria need to be satisfied. Solid Energy primarily use value based (discounted cash flow) metrics to support investment decisions. Within this approach Solid Energy utilise a number risk-based techniques to quantify project uncertainty. This includes the use of risk-based probabilistic analysis using Monte Carlo simulation and probability-based scenario analysis. Figure 1 shows the net present value (NPV) cumulative probability. Project risks are identified through comprehensive risk workshops. The output of these workshops (list of key risks, ranges of uncertainty and probability of occurrence), is quantified within the financial models. Incorporating this risk information on a probabilistic basis allows an investment decision to be made with a robust knowledge of the range of possible project outcomes along with the likelihood (probability) of those outcomes occurring, for example 80 per cent confidence that the project value will be greater than NZ$10 M, 50 per cent confident it will be greater than NZ$50 M and ten per cent confident it will be greater than NZ$70 M. Incorporating risk implicitly into the financial analysis allows the business to easily evaluate/measure projects with different risk profiles. The detailed risk analysis does away with the complexity of arbitrary risk-based hurdle (discount) rates, as projects can be evaluated based on their specific risk characteristics. Whether a project will progress to the next level of investment and ultimately into implementation depends firstly on the value assessment in comparison with the associated risk/uncertainty, and secondly matching this with the businesses appetite for risk. At Solid Energy standard criteria are used for specific project evaluations, but in addition projects are considered on a portfolio or strategic basis also. Solid Energy attempts to maintain a mix of low risk (low value) projects with some high risk (high value) opportunities. The mix of projects must remain in line with the shareholdersÆ risk appetite. One of the keys to a successful investment decision is ensuring that the appropriate information is available to decision-makers so that they may proceed with a comprehensive understanding of the risks and impacts associated with the decision.

Jan 1, 2007

By JSrvinen A, Yll÷ E

At Cominco's Zinc Refinery at Trail, British Columbia impurities are removed from zinc sulphate electrolyte by a two-stage purification process using zinc dust. Copper, cadmium and thallium are removed in the first stage whereas cobalt is removed in the second stage. Cobalt removal kinetics are affected by soluble antimony and copper additions to the electrolyte. This study was focused on the kinetics of cobalt removal by zinc powder cementation. Experimental variables included copper and antimony concentrations, pH and temperature. Common organic additives employed in zinc plants were studied to determine potential interactions with the cobalt removal process. Cementation products obtained from laboratory experiments and plant practice were studied using SEM. A number of significant results were obtained: 1. Copper and antimony ions were sustantially removed from solution during the early stages of the cementation reaction (within the first 15 minutes). Cobalt cementation kinetics are slow and follow a first order kinetic regime. 2. A drop in the cobalt removal rates can be correlated with a rise in the Eh of the slurry. 3. Ligninsulphonate, Percol 351 and animal glue at levels of 2 mg/L significantly impede cobalt cementation.

Jan 1, 1993

When the writer first saw the square-set timbering, he was at once impressed with the fact that the frames made by the sets, along the lode amI across it, were composed of panels with rectangular openings, and it was puzzling to understand howsuch a collapsible construction could resist pressure that came unevenly on it. Later he learnt that the sets did not satisfactorily resist such pressure, but mullock filling had, to a great extent, to undertake this duty for them. So it appeared that the setswere practically an expensive scaffolding, enabling the miners to work in the face and carry the stope forward, till the filling was put in behind them to take the pressure of the roof and sides of the excavation. Of course some of the pressure is takenby the sets, but this is because the set timbers prevent the filling being done perfectly; if it were practicable to remove the sets before filling, the filling by itself would more effectively support the back and wall, than do the combined sets andmullock. On the whole, therefore, the sets can hardly be said to be of much benefit where pressure has to be resisted. Despite this, the system has been of immense service in mining wide lodes, but for all that, it can only be pronounced a makeshift.This is no reflection on Deidesheimer, the famous originator of the square set, for, as will be shown later on, this way of...

Jan 1, 1911

-in 1961,.West Australian Petroleum's Eneabba. No. 1 bore encountered twenty-two' seams of coal totalling forty feet in thickn' ss between the..'depths of 6373 feet and 64,/,1 feet. 0n'ana:lysis; this coal had a. similar calorific value (8000 - 9000 B.

Jan 1, 1964

By C OÆKeefe, A Thomas

Boom time in the mining industry has presented mill operators with several unique challenges including the need for increased throughput while being constrained by a shortage of skilled labour and aging capital equipment. New instrumentation technology that provides reduced installation costs; no process down time for installation; and reduced maintenance costs and labour requirements; has been introduced to address the labour situation while maintaining production. This new tech- nology also enabled more accurate and reliable process measurements thus providing the capability for operators to maximise throughput with their existing capital equipment. This passive SONAR based technology can accurately measure the volumetric flow rate of single phase and multiphase fluids as well as the amount of air entrained within slurries. This is accomplished in a non-invasive manner. This paper will describe the principle of operation as well as the application of the technology to critical minerals processing applications. Included will be operational examples comparing the SONAR measurement performance to traditional measurement techniques. These examples will include hydrocylone feed flow, flotation concentrate flow, and slurry streams containing magnetic ores. Actual plant data will be presented as well as a discussion on the operational advantages such a measurement capability.Also described will be the power of the technology platform to provide novel process monitoring and control capabilities such as pipeline sand-out prevention and pipeline acoustic monitoring.

Jan 1, 2009

By P K. Seccombe

Sulfur isotope data are available for 18 low-sulfide orogenic gold systems hosted by the Lachlan Orogen in eastern New South Wales including those in the northern Hill End Trough (Hargraves, Hill End, Napoleon Reefs, Sofala-Wattle Flat, Stuart Town, Windeyer) and adjacent areas (Bodangora, Lucknow, Springfield), the Gilmore Fault Zone (Adelong, Sebastopol) and those in the Parkes district (Calarie, London-Victoria, Wyoming One-Myall United). Other systems for which data are available include Mongarlowe, Murrumbateman, McMahons Reef and Yalgogrin. The d34S data for many of the larger deposits including Adelong, Bodangora, Calarie, Hargraves, Hill End London-Victoria, Lucknow, Sebastopol, Sofala-Wattle Flat, Stuart Town and Windeyer (Group 1) are all very similar and have average d34S values close to zero per mil. Near 0ë d34S signatures imply that sulfur was sourced from a magmatic reservoir. Furthermore, the large Wyoming One deposit has d34S values significantly below 0ë with the data implying that sulfur was sourced from a fractionated magmatic reservoir. Group 2 deposits include those at Mongarlowe, Murrumbateman, Napoleon Reefs, McMahons Reef and Springfield . These deposits have average d34S values significantly above 0ë. With the exception of Springfield where sulfur was probably sourced from the Hill End Trough, Group 2 deposits are an order of magnitude smaller than Group 1 deposits. The results suggest that many of the larger orogenic-related gold deposits hosted by the Lachlan Orogen in eastern New South Wales derived sulfur and gold as a result of leaching and recycling from a magmatic reservoir. Alternatively, there may have been direct mantle-derived input; however, this is considered unlikely on geological grounds. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By A Coulson, J Hussey

Noranda Inc is a Canadian mining and metallurgical company with its activities managed through businesses in copper and recycling, zinc, aluminum, magnesium and various metals through its interest in Falconbridge Ltd. Noranda operates three base metal mines, three copper smelters, one copper refinery, one zinc refinery, one lead smelter and refinery, three copper recycling and sampling facilities seven aluminum producing facilities and one magnesium production facility in the construction stage. The mining side of Noranda has a strong history of open stope, cut and fill and shrinkage mining. The 1999 Noranda Annual Report lists a 206 million tonne resource located at Porphyry Mountain in GaspT, QuTbec. Mont Porphyre is a large tonnage, low-grade porphyry style Cu-Mo deposit that was discovered in 1994. It is located at a depth between 1.0 and 1.7 km below surface and characterised by a very competent rock mass. The Mont Porphyre resource is located adjacent to the town of Murdochville, close to NorandaÆs Mines GaspT operations. Mines GaspT closed its open pit and underground operations in 1999 after approximately 45 years of mining, but still operates a copper smelter near Murdochville. The low-grade and great depth of the Mont Porphyre resource suggested that mine design could not be based on the conventional Noranda open stoping mining practice. This paper will review NorandaÆs approach to evaluating the Mont Porphyre deposit. The approach included two definition diamond drilling campaigns, a review of current caving practice, an in-house scope study, a geotechnical logging program for diamond drill core and participation in an international study on cave mining. One interesting component of NorandaÆs approach was the scope study that involved a team of multi-disciplinary personnel drawn together for a short period of time. The objective of the scope study was to determine what conditions would be necessary to mine the deposit and to assess the merits of continuing with further exploration work. A review of current worldwide underground bulk mining practices, and in particular an evaluation of the applicability of caving mining methods, were key components of the scope study. The scope study team concluded that derivatives of caving could be applied to the mining of Mont Porphyre, but additional diamond drilling was recommended to further define the deposit and improve the level of geotechnical information. Following the recommendations of the scope study team, a diamond drilling campaign was completed during the summer and fall of 1997. The 1997 drilling campaign had two secondary objectives, in addition to the primary objective of defining the limits of the orebody. The first objective was to improve the level of geotechnical information available for the characterisation of primary block cave fragmentation. The second objective was to improve the delineation of a lower grade intrusive core. A geomechanical investigation was conducted and included particular emphasis on geotechnical data collection and analysis. A review of the actual data collection process, including several trials of different core orientation techniques, will be included in the discussion.

Jan 1, 2000

The overall mineral assemblage of the Broken Hill orebody is similar to that of a skarn. However unlike the classical skarns it does not represent contact metamorphism of pre-existing limestone beds. It is a stratiform accumulation of exhalative-sedimentary silica, sulphides, (Ca, Fe, Mn) silicates and carbonates, fluoride and phosphate that has later undergone regional metamorphism. The resulting development of coarse-grained quartz, sphalerite, galena, rhodonite, bustamite, mixed carbonates, fluorite, apatite and many minor phases has produced a sulphide-rich skarn- like mass that like many others of its kind, might best be referred to as a stratiform skarn. Recent investigations of occurrences of this type are showing that the incidence of concentrations of particular metamorphic minerals in and adjacent to such orebodies are closely related to bedding and to former sedimentary facies patterns. From this it appears that the mineral assemblages may be used to deduce not only the nature of the materials laid down in the beds, but also the physico-chemical conditions under which sedimentation took place. Several stratiform deposits, including Broken Hill, are used as examples to show that variations in these conditions may have a profound influence on the subsequent response of the rock to regional metamorphism and hence on the mineral assemblages that finally develop.

Jan 1, 1983

By Opitz E. A

The integration of environmental and permitting strategies into development has become a routine part of doing business for the international minerals industry. Paralleling the development schedule with the environmental and permitting schedule is critical to ensuring that design recognises environmental constraints and that the environmental and permitting program has the right focus and achieves the objective of obtaining workable permits that reflect the project design. Regulatory issues including the law of and controls established by the country the project is situated in, the requirements of international financing institutions, international politics and the role of environmental groups and the particular precedents and processes established are all important issues that must be recognised and incorporated into the permitting program by the developer. Technical issues including collecting early environmental data during exploration, establishing hydro-meteorology equipment, baseline data gathering, and getting good environmental engineering information as a part of feasibility and design are also critical issues to the success of a project which are under the direct control of the developer. Finally tying all of these issues into a single integrated strategy under the direction and control of a nominated team is necessary to maintain focus and achieve results.

Jan 1, 1997

By D Lees, D Gilchrist

Sydney has hundreds of kilometres of sewer tunnels. Many of these are over 50 years old and some have been in service for more than 100 years. The tunnels are predominantly constructed in Hawkesbury Sandstone and many are unlined.Principles have been developed over many years for the safety factor required in designing and constructing new tunnels but these do not necessarily relate to the operation and maintenance of existing tunnels, and in particular those that do not necessarily require personnel access for anything other than regular inspections.Assessment of the stability of these established tunnels needs to take account of their size, their age, their function, and their method of construction, as well as the geology in which they are situated and any support measures which have been installed. More importantly a stability review needs to take account of the consequences of a collapse, with regard to the inspection process, carrying out of any required repairs and the long-term performance of the tunnel.This paper is based upon the authors’ experiences inspecting and reviewing more than 200 km of tunnel in the last ten years. It will show some of the procedures and methods adopted by Sydney Water, how these can be presented as an acceptable procedure in line with other safety standards, and how they might be adopted for other similar historic rock tunnels.CITATION:Gilchrist, D and Lees, D, 2014. The development of a procedure for the inspection of unlined rock service tunnels, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 543–552 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

For several years, the Geology Department of the University of Canterbury has hosted a series of postgraduate projects in the field of coal studies, supported principally by the Ministry of Energy and to a lesser extent by private companies. These projects have involved mainly West Coast Coalfields, and my own studies have focussed on inorganic geochemical aspects of West Coast coals. Because of the large number of potentially important analyte elements in coal, and the wide diversity of coals occurring in the West Coast region, this project has required a substantial amount of work to be spent on sample collection, sample preparation, development of analytical methods, and actual analysis. Considerable problems must be faced at the sampling stage: Can sufficient information be obtained from whole-seam composites, or should seams be sampled in plies. Ply analysis is preferable, but results of proximate analyses are usually available for composites only. Where multi-seam drillhole samples become available (eg Greymouth Coalfield, where some holes yielded more than six sampled seams), the ply option involves a dramatic increase in the number of samples. I have attempted to strike a workable compromise between geographical coverage of coalfields, and detailed sampling of individual seams at each locality. In many cases, sample material has been used jointly with Jane Newman who has carried out petrographic studies.

Jan 1, 1985

By R Dunne, W McCallum

Continuous improvement might be defined as seeking incremental improvement over time through improved equipment, processes, technology and the efforts of people. Most people working in ore processing facilities embrace the general principles of continuous improvement. However, given the industry-wide issues with skilled personnel and the constantly changing environment in ore processing facilities, it is often difficult to identify improvements in a facility over a given time period. The driver for these outcomes is the use of basic principles and technology to achieve best practice targets. The process involves four stages: develop standards of practice to define best practice in specific areas; write procedures to guide the organisation towards these best practices; implement the procedures and develop a review process to provide a method of measuring performance against best practice.By reviewing performance against best practice on a regular basis, the organisation measures progress towards the best practice targets and the incremental improvement between these regular reviews is a measure of continuous improvement.This paper provides the background for developing standards of practice for metal accounting, metallurgy and metallurgical management. The paper also describes how standards of practice can be used to develop continuous improvement and the skills set of the departmentÆs leadership team.CITATION:McCallum, W and Dunne, R, 2012. Metallurgical management tools for continuous improvement, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 225-230 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By K Zic, P Pickering, P Fraser

Water is a defining feature of the Pilbara. Its management was and remains vital for the pastoral industry which European settlers established when they first came to the Pilbara, and for the mining industry which now dominates economic activity in the Pilbara. Water availability in the Pilbara is, however, problematic. Severe droughts and major floods can occur at close intervals. In response to this uncertainty, the Department of Water undertook a Prefeasibility Study to determine, at a high level, the water requirements and opportunities in the Pilbara region. This paper reports on the outcomes of this study and the water integration opportunities in the region, identifying the sources of water supply and offers possible options for managing this water sustainably for the present and future demand. A range of supply opportunities is reviewed including: dewatering from mining operations, surface water, and desalination. All opportunities were subject to order of magnitude costing, including capital, whole of life and retail unit pricing with preferred options receiving further interrogation through triple bottom line (TBL) analysis to prioritise solutions. Options were also subject to intangible quantification (IQ) including benefits from the reduction of carbon emissions to ensure that the preferred option is based on factors other than just the least cost. Demand analysis was undertaken to identify current and future requirements and were assessed through review and integration of regional and sub regional master plans and consultation with mining, agriculture, industry and the community. The paper concludes that the viability of a Pilbara integrated water supply scheme depends on the development of a financial mechanism involving both government and industry participation models. The agreed scheme formed the basis of a submission to Infrastructure Australia for funding assistance.

Jan 1, 2009

By J Rostami, D Tadic

While hard rock tunnel boring machines (TBMs) have an established track record in the tunnelling industry, accurate estimation of TBM performance for each specific project remains critical. Machine performance prediction is required to assist planning activities, including costing and schedule preparation, machine specification and effective planning of maintenance and repairs. In addition, monitoring machine performance during the construction period is required to assess and manage excavation progress, and to achieve optimal advance rates based on specific geotechnical conditions exposed during excavation. TBM performance analysis can also contribute to the development of more accurate performance prediction models for future applications. Rock mass characteristics play a dominant role in machine performance. This paper offers a review of the impact of rock mass characteristics on TBM penetration rates for two specific tunnelling projects. A discussion is provided on the results of statistical analysis of available field data, including geological back mapping, rock properties and measured rates of penetration (ROP). The analysis offers a comparison of the achieved and predicted ROPs to provide a better understanding of the influence of rock mass properties on the performance of hard rock TBMs. A new rock mass adjustment factor is introduced to enhance the accuracy of an existing prognosis model for use in jointed rock masses.

Jan 1, 2008

Optimisation of mining projects is directly related to effective and efficient management of risks through the life cycle of mining projects. Effective and efficient management of risks must include explicitly all aspects of Occupational Health and Safety (OHS) through the life cycle of mining projects. This paper presents a different scale of OHS in the context of the optimisation of mining projects. Meaning of risk through the project life cycle is explained. Complex relationships between numerous risk, safety, knowledge, culture and change variables, and project life cycles are shown. The key element developed in this paper is a multi-disciplinary knowledge base that is necessary for constructive development of risk management and OHS models through the life cycle of mining projects.

Jan 1, 2003

By Mckenzie CK

Delay scatter, although widely recognised, has rarely been studied with the aim of critically reviewing blast designs. With current trends towards increased deck charging, and the effect on the number of separate delays in blast designs, delay scatter is shown to have a rather profound influence on the control of initiation sequence and the ability to successfully con- duct pre-splitting and smooth blasting. Determination of realistic delay scatter distributions is the first step towards application to blast design. Delay scatter must be evaluated in terms of deviation from the nominal time, not in terms of deviation from the batch mean, since the latter is not usually known without specific testing, requiring accurate timing instrumentation. Computer programs using Monte Carlo simulation can then be developed to investigate the probabilities of out-of-sequence initi- ation or near-simultaneous initiation within any specified interval. The procedures have been applied to both production and development blast designs in Australia and Chile to improve initiation sequence control and to rationalise and simplify blast designs.

Jan 1, 1988

Three main divisions of the. Proterozoic are recognised in the North- West of Western Australia. These are referred to, in order of decreasing age as the Mt. Bruce Supergroup, the Bresnahan Group and the Bangemall Group. The stratigraphy and distribution of each is described, their relative ages discussed and a brief geological history of the whole area is Presented.

Jan 1, 1964

By L Galisson, E Audigé, D Sowers

Establishing a robust geotechnical instrumentation and construction monitoring plan is one of the keys to the successful delivery of the world’s largest soft-ground bored tunnel in Seattle, Washington. The paper describes and provides a return of experience on current and best practice for monitoring tunnelling projects in urban areas. The owner’s contractual approach is discussed to highlight the flexibility of the design-built contract in achieving equal or better solutions by allowing for the use of innovative technics. Special attention is given to the management and involvement of third parties (building owners, utility owners), including the public, to overcome all challenges faced during the installation of the monitoring system in downtown Seattle for over 1000 instruments. Finally, the authors present the strategies implemented for managing the monitoring data and communicating with the owner, contractor and stakeholders.CITATION:Sowers, D, Galisson, L and Audigé, E, 2014. Current and best practice for monitoring tunnelling projects in urban areas – Alaskan Way bored tunnel, Seattle, Washington, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 441–450 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014