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By H J. J Boshoff, A J. Karrasch

Mine planners frequently face the challenge of mitigating the impact of climatic events on mining operations, such as floods and droughts. Specific water management infrastructure can be implemented to meet operational requirements in response to these events. However, the effect of flood protection, for instance, may reduce the resilience of the site to drought. The probability and duration of unfavourable climate sequences significantly influences the net present value (NPV) of implementing specific water management infrastructure.Good life-of-mine planning will consider the incremental development of the project, and provide staged development plans. Water management infrastructure and the timing of implementation are facets of this process.CITATION:Boshoff, H J J and Karrasch, A J, 2016. A decision-making framework for water supply and flood protection options in net present value terms, in Proceedings Life-of-Mine 2016 Conference , pp 196–199 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

Future depth and production limitations of an ore hoisting system are fixed by its initial design criteria. There is little scope to extend these limitations once installation is completed. Depth and production rate upgrades from the initial duty to the hoistÆs practical limitations require capital expenditure in stages, each of which can be defined when assessing the initial system design criteria. A means of presenting and assessing the design criteria, the limiting factors in each option and the relative present and future capital costs is necessary to arrive at a solution that delivers the best value to the mine. Application of this technique to recent friction winder installations and upgrades in the Australian mining industry is of particular interest; however, the analysis methods are also applicable to drum hoists. It is usual to specify a minimum hoisting capacity and depth, based on mine ore handling design and production needs. The final hoist depth and production rate are usually a result of the initial hoist design and hence it is useful from the outset to specify a required production versus depth envelope for the mine. Technical solutions can then be modelled within this envelope at their initial and final duties and a comparative analysis made against the cost of installing and progressively upgrading each solution. Understanding the factors that constrain each solution to a maximum production rate at a given depth is important, as the costs of overcoming limiting parameters such as rope tread pressure and motor power can be significant. The task of understanding and evaluating the options open to the hoisting system designer is simplified using this approach. Communicating the results of a multi-dimensional problem such as hoist specification is also made easier using the graphical methods inherent in the analysis.

Jan 1, 2005

My closest personal connection with the problems of rehabilitation comes from two years spent on a project at Weipa. At the beginning I am fairly certain that the engineers did not understand the mental processes of the ecologist they were dealing with. I am absolutely certain that the ecologist did not understand the minds of the engineers. This form of the two cultures problem is the root of some of the matters that lie behind this lecture. It is possible to establish a stabilising cover of vegetation on virtually any land surface, short of a cliff. While the biologist knows this he also knows that the physical and chemical nature of a given acre of land combines with climate to define quite sharply just what plants can be grown there. In the case of land after mining the range of plants may be quite limited. The engineer, and his masters in the accounting section, seem (in my experience) to expect that rehabilitation can be carried on with equal speed and facility in any location. This belief commonly leads to a situation where rehabilitation is not considered until mining is well under way. True, the mine must be proved as an assured profit- earner before money can be justified for the non-productive (to the miner) expense of rehabilitation. But when the miner finally starts rehabilitation he does not always get a convincing and speedy result. Furthermore, the failure may not be easy to overcome. This is even more likely to be the sequence of events if the miner wants, or is obliged, to specify the exact type of vegetation to be produced, e. g. commercial forest, pasture,' or the original native vegetation.

Jan 1, 1971

The complete life cycle of a production facility has many phases requiring many different skills and many different personalities. It is not unlike the life cycle of a person and many parallels can be drawn from it. I leave some of these analogous situations to your fertile minds. The author, having worked in operations, plant design, plant commissioning, marketing and many other interesting situations through the industry has drawn from this experience and examples given by many associates in the industry.The phases seen are as follows: Concept Studies û someone has a bright idea of how to make a dollar. Scope Studies û what possible processes/options that could make a dollar. Prefeasibility Study û the æviableÆ scope options are studied to develop feasible options. Feasibility study û defines the concepts that should be designed to make a viable project thus enabling financing and project commitment to be made. Detailed Design û an intermediate step that consolidates the inputs to give a robust plant that can be constructed.Construction û people can see what they thought was going to occur and start to understand the plant. Commissioning û the hand-over of æownershipÆ from the conceiverÆs to the operators. Operations û the ætoyÆ has become reality and money must be made. De-commissioning û the plant has seen out the useful life of the ore deposit, it now goes through a further process required by society.Across these phases of plant design run several countervailing management requirements that can influence the outcome of the plant design. Some of the management rigours that have to be applied to the various phases are as follows: costing basis of the various phases; operational and maintenance reviews; sustainable development; risk assessment; reliability reviews; equipment availability; commissioning time; and environmental review.This paper endeavours to awaken people to the phases that projects require for a successful outcome and the management rigour that has to be applied throughout the phases to ensure the correct intellectual horsepower is applied at the right time to ensure the best outcome.Many of you would be parents and realise this is not unlike the development of children, teenagers, adults, retirees and ongoing.

Jan 1, 2002

By P Cheluszka, M Jaszczuk, P Sobota

This paper refers to a new idea of stereometry of cutting drums of longwall shearers designed to get medium and hard to mine coals. A new way to place picks on a drum enables to readjust a number of picks being in contact with the body of coal to shearer haulage speed. Owing to this a remarkable increase in depth of a cut within the low range of haulage speed has been obtained. On comparing operating characteristics a considerable reduction in the specific energy consumption has been shown when using the units machined as per the new idea, in comparison with the units produced in series.

Jan 1, 2003

By S H. Li, H Z. Gu, A Huang

High aluminium steel is a promising advanced steel known for its exception properties and holds significant economic and strategic importance. However, the CaO-Al2O3-SiO2 based slag with high alumina content reacts vigorously with alumina refractories during the smelting process at high temperature, seriously affecting the safe and efficient production of furnaces and resulting in the formation of Al2O3-MgO non-metallic inclusions within the molten steel. This is a bottleneck problem for high-quality steel refining, and the key reaction path during the corrosion remains unclear. The dissolution reaction mechanism of alumina refractories in high alumina CaO-Al2O3-SiO2 slags under a weak static magnetic field was investigated in this work, using high temperature laser confocal microscopy and in situ radiation spectroscopy techniques. The results indicate that the interaction between the high alumina slags and the alumina refractories is governed by free radical reactions. The dissolution of alumina forms AlO and AlO2 radicals. The reaction rate increases with the C/S ratio of the slag due to its low polymerisation. The reaction between non-bridging oxygen and AlO2 free radicals accelerates the generation of AlO and O2ꞏ- radicals. The reaction layer composed of calcium aluminate is formed through the recombination of AlO, Caꞏ+ and O2ꞏ- radicals. The weak static magnetic field induces the Zeeman splitting of free radical pairs and intersystem crossing occurs, promoting the formation of triplet free radical pairs through the hyper-fine coupling effect. The reaction can be significantly inhibited as the triplet free radical pair does not meet Pauli’s incompatibility principle. This discovery perfects the structure theory of molten slags with radicals and provides supplement to the design of the highly slag-resistant refractories, and provides the theoretical basis for the development of external field protection technologies for high-quality steel refining.

Jun 19, 2024

By A Densten, C Gimber

Surface water management and drainage is a key aspect of mine rehabilitation and closure planning. In the authors’ experience, drainage related problems are amongst the most common forms of failure in mined landscapes. The appropriate design of surface water infrastructure is therefore a key focus of practitioners. While there is currently a trend towards distributed drainage networks and avoiding hard engineered structures, in many situations (especially for existing landforms) engineered drainage structures cannot be avoided. CITATION:Gimber, C and Densten, A, 2018. A risk-based approach to drainage design standard selection for mine rehabilitation and relinquishment, in Proceedings Life-of-Mine 2018, pp 116–118 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

Railway cuttings require the highest care in design and construction, as the pro- bability of failure concept does not allow any risks to be taken with hundreds of lives being dependent on continued stability. The usual geological influences on stability such as bedding dip and faulting are often discus- sed, but other major problems may come from the presence of sheet joints, cross joints differential weathering and seasonal or daily changes of ground water level. The design of rail cuttings has taken little note of the problems imposed by cons- truction methods, and low cost quarrying methods may seriously weaken a designed shape. The presence of berms and drainage ditches is often difficult to achieve as blasting imposes cumulative stresses and jointing on rocks. Contractors face difficulties in bidding extensive rock cuttings as variations in rock properties are often concealed and overshoot- ing the toe of a batter can easily occur. Modern blasting methods offer some solutions, but the best guide to safe successful cuttings is extensive investigation and the continued involvement of engineering geology at the stages of feasibility, design, construction and maintenance. Two case histories show the influence of folding, faulting and construction methods in the case of slope failure and slope stability.

Jan 1, 1979

This paper carries on from an earlier paper 'Cemented fill practice and research at Mount Isa' and reports further on the laboratory programme at Mount Isa to develop a cheap cem- ented fill using Company waste products. The practical economic significance of availability of cheap cementing agents is re- viewed, with the various alternative approaches available The basic approach adopted within this paper is that use of reactive pozzolans such as ground slags to replace a proportion of the Portland cement in the fill can make mining methods employing cemented fill more economic- ally competitive with other mining methods.

Jan 1, 1973

In many mining operations, the truck and loader equipment represents the bulk of the invested capital and the majority of the mine operating cost. The profitability of these mines is therefore critically linked to the efficiency of the truck and loader operations. The various factors which affect the productivity of trucks and loaders are analysed by computer simulation, and the results presented in a form allowing assessment of the importance of each factor on overall productivity.

Jan 1, 1983

By P H. Warton

It is proposed to construct a gold extraction plant at Matatoki, near Thanes. Ore to be processed at the mill will come from reopened and enlarged underground mines north of Thanes. The project has been described in some detail in environmental impact reports (Worley Consultants Ltd 1984, 1987), and is now at an advanced stage in terms of obtaining the required statutory approvals.

Jan 1, 1987

By Lunardi P, Pelizza S

The link between the Lecco bypass and major road SS36 (Italy) requires the construction of a double two-way tunnel (through the mount San Martino carbonatic massif). The tunnel excavating section is about 90 sqm through mount San Martino carbonatic rocks. The mountain sides are unstable and are often the scene of large collapsing landslides (tens of thousand cubic metres). The tunnels are very close to the mountain sides. The use of blasting induces vibrations which may reach the Lecco built-up area. With a view to avoiding such dangers the excavating operations were carried out in two successive stages: - opening a pilot tunnel, whose section is about 10 square metres, by a full face TBM to eliminate the more intense vibrations which are generated by the first opening charges; - successive enlargement by blasting.

Jan 1, 1987

The Bowen Basin coal field is an important energy resource. A relatively small proportion is avail- able by open cut operations. Responsible men throughout the world have warned of the need to increase coal research immediately. Because energy is still available in abundance these warnings have not been heeded in Australia. The characteristics of the Bowen Basin coal make it a fairly difficult underground mining proposition and a significant research effort is required to solve the problems likely to be encountered. Both industry and government have responsibilities in the economic recovery of the maximum proportion of the resource and jointly funded research administered by existing organisations should be inaugurated forthwith.

Jan 1, 1976

Asbestos is a commercial term applied to fibrous varieties of several minerals, the properties of which are not generally appreciated by the majority of geologists. A thorough knowledge of these properties and of the uses of asbestos is of fundamental importance in the assessment of the economic value of an occurrence of asbestos. The varieties of asbestos that are used predominantly by the manufact- urers of asbestos products are chrysotile, crocidolite and amosite but chrysotile constitutes 95% of the world's usage. It is the properties of high tensile strength, 'heat resistance and large surface area that make chrysotile asbestos the most acceptable of the mineral fibres. There are no known exploration aids, other than direct visual inspec- tion of outcrops in ultrabasic environments, that could be used in the exploration of chrysotile asbestos. The surface exploration of an occurrence of chrysotile asbestos is relatively routine, though it lends itself to a unique form of bulk sampling by the use of a twelve inch diameter diamond drill core. The laboratory assessment of the prop- erties of the actual fibre requires specialized techniques and tests to assess not only the amount of fibre present but also its length distri- bution, inherent strength, filterability, dust content and other prop- erties. The way a fibre reacts to milling will determine what milling process- es must be implemented to ensure a product that is acceptable to the asbestos product manufacturing industry.

Jan 1, 1971

The grades of alluvial ore deposits are low compared with grades of hard rock mining. This factor, combined with other parameters of irregular distribution of particles, bedrock irregularities, size of particles, nugget effect, ore characteristics, and wet horizons, combine to place alluvial deposits among the most difficult to evaluate, and on which to establish an ore reserve with a high degree of confidence. With increased geological input, correct selection and implementation of sampling method, due regard to sample representativity and process design, these confidence levels can be achieved.

Jan 1, 1987

By M B. McKevitt, W J. Shaw

The main task of grade control on a daily basis is to define the material that should be mined to a destination under various categories. This can be determined by grade, lithology, quality and blending criteria. In the case of multi-element deposits or deposits with various blending or other processing criteria the optimum selection of ore block boundaries can be quite complex. In every case the balance between ore loss and dilution must be considered when designing the ore block boundaries and this becomes a risk-based decision when using the conditional simulation model. The use of such systems allows grade control to meet specific targets, such as budget tonnages and grades and blended product specifications. Two case studies are presented: the Prominent Hill copper/gold mine and the Rapu Rapu zinc/copper mine. Mining is based on a rational grade control strategy involving a number of factors, including strong geological control, advanced geostatistical approaches, such as conditional simulation, and optimisation of the ore blocking to meet production requirements. This provides an objective, transparent and repeatable grade control strategy.

Jan 1, 2009

By T Baumgartl, B Noller, B Forsyth, J Park, M Edraki, P Pham

Understanding and quantifying residual risk is the key to the successful closure and rehabilitation of mines. An important aspect of residual risk is predicting the long-term chemistry of mine water and the long-term geochemical stability of mining wastes. This requires updating the characterisation data for mine wastes and monitoring mine drainage throughout the life-of-mine. The intrinsic properties of waste materials (ie the geology, mineralogy and the weathering processes, which in turn depend on the local climate and water balance in a waste storage facility) are the fundamental controlling factors of residual risk. In this paper, case studies of coal and metalliferous mines are used to discuss the definition of residual risk for a range of waste storage facilities and to highlight the benefits and limitations of current geochemical methods in predicting and quantifying residual risk. Consistent with the classification of mine drainage by the Global Acid Rock Drainage Guide, three case studies of acid, saline and neutral drainage are presented.CITATION:Edraki, M, Pham, P, Park, J, Baumgartl, T, Noller, B and Forsyth, B, 2016. Defining residual risk for successful mine closure – a geochemical perspective, in Proceedings Life-of-Mine 2016 Conference , pp 9–11 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

Information from bores in the LatTobe Valley has been accumulating for over fifty years, and the manual extraction of details has become a limiting factor in their use.Punched card equipment, installed by the State Electricity Commission for accounting purposes, was known to be available for reasonable periods, and it was suggested that this could help in the extraction of data from the voluminous records.Investigation showed that they could be substantially duplicated on cards, with consequent gains on many operations; the cards being regarded as an auxiliary to the existing records.BRIEF DESCRIPTION OF RECORDSAs a bore is drilled a continuous record of the strata is kept, together with notes on the presence of water or any unusual features which the driller may observe.When coal is struck, samples of each ten feet are usually sent for analysis.The location and surface level of each bore is fixed by surveyors, and details of dates and methods of drilling are also kept.Bores are allocated numbers, prefixed by the name of the parish within which they are drilled. Numbers are allocated in conjunction with the Department of Mines, to avoid duplication.Records of strata and analyses are kept in folders, with 100 bore numbers per folder.Standard plans are drawn, showing the locations, bore numbers and surface levels. For each bore they also show the depth and thickness of coal struck, and the total depth drilled.Cross sections are then drawn, connecting the various coal seams, which have been identified by the geologist.

Jan 1, 1960

By H Kim, M J. Sun

Global steel companies are actively combating climate change by reducing carbon emissions. Traditional steel production, using the blast furnace (BF) – basic oxygen furnace (BOF) process, heavily depends on coal and emits substantial CO2. To mitigate this, companies are transitioning to the more eco-friendly DRP (direct reduction plant) – EAF (electric arc furnace) process, which lowers CO2 emissions. This study quantitatively evaluates the impact of increased hydrogen consumption on the carbon footprint of product (CFP) through an analysis of direct reduction process heat and mass balances. The study prioritises a comprehensive material balance based on mass conservation principles. The heat balance is calculated using differences in enthalpy through state energy properties, avoiding heat consumption. Validation using operational data from Hyundai Steel Dangjin works’ blast furnaces shows close alignment between calculated results and actual data, with less than 1 per cent error. This methodology facilitates a detailed analysis of the direct reduction process, offering insights into its feasibility and efficiency. Analysis of the operational impact by increasing the hydrogen ratio demonstrates reduced CO2 emissions and increased heat requirements due to the endothermic nature of hydrogen reduction, in contrast to the exothermic CO reduction. Possible solutions include raising reducing gas temperature or enhancing flow rate. The study effectively utilises designed heat and mass balances to assess material quantities and thermal balance under different operational conditions. It lays the foundation for the initial direct reduction process design, aiding in deriving and optimising operational parameters. Additionally, it provides valuable insights into the challenges of increased hydrogen, contributing to the production of greener steel by addressing these issues.

Aug 21, 2024

By T R. Anderson, A R. Butler

Haymont (2012) notes that in parts of Australia significant areas of mining disturbance cannot be relinquished. In Queensland it has been estimated that by 2010, just 0.3 per cent 507 ha of mining disturbance had been rehabilitated to the regulator’s satisfaction (Short, 2015).One reason for this poor record is the presence of inappropriate, unachievable or unmeasurable rehabilitation targets (Glenn et al, 2014; Butler, Anderson and Sexton, 2015). In the authors’ experience in Queensland many mature operations have licence conditions that hinder the achievement of sustainable outcomes or prevent successful validation of rehabilitation success. This creates a lack of certainty for industry and a lack of confidence in the community that the sector can deliver good rehabilitation outcomes (Short, 2015).This extended abstract presents a framework approach that has been applied at two contrasting operations. Without the changes presented, the goal of progressive rehabilitation certification, reduction in financial assurance (FA) and a path to surrender at these sites would have been impossible. The framework can be adapted for use across different bioregions and commodities.CITATION:Butler, A R and Anderson, T R, 2016. Reassessing rehabilitation objectives and targets for mature mining operations in Queensland, in Proceedings Life-of-Mine 2016 Conference, pp 139–141 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016