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By R Bertuzzi

This paper presents a three-dimensional analysis of a trapezoidal-shaped segmental tunnel lining for a recent tunnelling project in Sydney. Two- dimensional analyses, hand calculations and equipment selection defined the lining geometry and loads. The analysis, which was undertaken using 3DEC (Itasca), included a complete ring of six segments bolted together to assess the impact of imperfectly built rings. Asymmetry was induced in the analysis by unfavourable positioning of segments within construction tolerances. Model output includes displacement and stress within the entire ring and normal, shear and bending moments at the joints. For the case analysed, the results suggest a 10 mm construction tolerance increases normal and shear stresses along the radial joints by approximately 25 per cent and 15 per cent, respectively and up to a doubling of the induced moments.

Jan 1, 2008

Mathematical modelling of continuous rotary vacuum filtration has been limited by the wide range of variables and the absence of connecting equations linking the variables. The filter type and size, mechanical design and predicted performance are generally determined by laboratory leaf tests on representative samples of slurry, or plant samples from an operating filter. A model has been developed which includes the major process variables such as slurry feed rate and concentration, cake thickness, wash water and air flow rates, to predict the filter production throughput, cake moisture and residual solubles. Where possible the model incorporates well established equations relating form filtration, washing and drying rates of the filter cake. Where an equation has not been formulated, standard curve fitting programs have been used to establish an algorithm. The theoretical equations and the derived algorithms are defined in the text. A major feature of the model is that operators, metallurgists, process, mechanical and instrumentation engineers become more aware of the interaction of process variables, the principles of the equipment design and its limitations when operating at peak performance. The model has specific application in the alumina industry where a high moisture content of the filter cake can increase chemical losses and energy costs, and in the coal industry where overseas companies are insisting on lower export coal moistures.

Jan 1, 1989

By J Morton

The Resource Management Act 1991 represented an innovative and unique piece of planning and environmental legislation when it was introduced. Since the Act was passed into law in 1991 it has been subject to nine amendments, many of which were of the ætinkerÆ variety. These amendments recognise that the Act has not been as successful in providing the æone-stop shopÆ for resource users that the Act was hoped to be. The latest and most significant attempt at changing the Act was the Resource Management Amendment Act 2003. The amendments made by the Amendment Act have proved to be largely unsuccessful in achieving any significant changes to the way resources are managed in New Zealand, and have failed to address many of the concerns which drove the original Resource Management Amendment Bill in 1999. The recent decision to discontinue further investment in Project Aqua has once again placed the Act in the spotlight as a significant hand-brake on major projects. This particular event has led to yet another review to be undertaken this year. The review will focus on five key areas:   1.   achieving the right balance of national and local interests; 2.   improving the design and process for local policy formulation; 3.   improving the consent decision making process; 4.   allocation of natural resources (water, air and geothermal); and 5.   supporting measures for building capacity and promoting best practice and implementation at the local authority level.  It is important for the business community and the mining industry in particular to seize the opportunity that this review provides to make sure that any amendments undertaken as a result of the review achieve the aims listed above. The review needs to be considered in light of the current regime for the management of natural resources in New Zealand. In addition to the Resource Management Act 1991, the Crown Minerals Act 1991 and the Building Act 1991, which form the core resource statutes in New Zealand, there have been other developments affecting the regime. Special legislation over and above the Resource Management Act 1991 has been enacted to protect the Hauraki Gulf and special legislation is currently being considered to protect the Waitakere Ranges in Auckland. In the Hauraki District mining is prohibited in some areas and a plan change mechanism is specified as the appropriate tool to use in the event a mineral resource is to be developed in those areas. The current review is a further opportunity to remedy the inadequacies of the Act.

Jan 1, 2004

Grey River Gold Mining Limited (GRGML) has constructed and largely completed the commissioning of an alluvial gold dredge designed to recover gold from a low grade gold deposit in the Grey River Valley, New Zealand. The most important resource that GRGML has are the people who are employed by the organisation. The low grade of the deposit necessitates the requirement to operate the dredge at optimum efficiency, which in turn requires the work force to be of high calibre and continually motivated. The primary prerequisite for employment at GRGML is for employees to be receptive to new ideas and have the adaptability to develop new skills and apply those skills to the changing demands of the workplace.   A continually changing organisational structure is utilised to meet the needs of a changing work environment. The adoption of an innovative site employment agreement allowing for flexible working hours has aided the achievement of good employee productivity and attendance.   Employees gain a higher quality of life by working a roster pattern involving twelve hour shifts and a four day on, four day off pattern.   Employees and management are communicating very well and working together to achieve organisational goals which will ultimately benefit the employees, the shareholders, the local community and the mining industry generally.

Jan 1, 1989

By P Meehan, R McAree, Z Guan

Equipment maintenance is 30 - 50 per cent of the operating costs for a typical mining company. While this is substantial, its importance is beyond its significance as a cost heading. Modern mining requires large amounts of investment in capital infrastructure and equipment to produce a product sold at a low unit cost. To stay competitive, such a business has to focus on full realisation of its capital investment, ie sustained production at high levels. Maintenance plays an essential role in achieving this goal. Mining companies typically use a mix of breakdown or corrective maintenance, planned maintenance, and some condition-based maintenance. The share of breakdown maintenance has been coming down through more effective planned maintenance and better condition monitoring tools. Planned or preventive maintenance (PM) is playing an increasingly important role in todayÆs mining maintenance. This is the suite of inspection and repair/replacement actions performed at scheduled time intervals as part of a preplanned activity. The activities are scheduled well in advance and, usually, the current wear-state of the machine is irrelevant. For example, the replacement of a major gear may have been planned 18 months in advance; replacement is carried out when the time comes regardless of the actual condition of the gear. The PM costs are significant and include direct cost of parts and labour as well as the opportunity cost of lost production while the machine is under maintenance. It is important to identify the optimum PM effort because over-maintenance should be avoided as much as under-maintenance. A new concept called severity-based maintenance is introduced in this paper. We have seen that measuring equipment ageing in mining merely by counting the engine hours is a very imprecise way of planning and scheduling maintenance because the damage accumulated in one hour varies enormously from operator to operator and with changing pit conditions. We recommend continuous monitoring of duty on all major equipment. This is feasible without having to fit out the machine with an army of sensors because most of the physical sensors required by dutymeters are already installed and maintained as part of the existing performance monitors. While the investment is modest, the potential benefits are huge and can be grouped under three headings:Immediate benefits will come from providing operators with direct feedback on the effect of their behaviour on machine health and training them to use this feedback to correct their operating style. The equipment can operate closer to the limits of capacity, producing more without unduly sacrificing the availability by monitoring and controlling the severity of the operation, ie the duty on the machine. Longer term benefits accrue from establishing correlations between actual time to failure data and measured equipment duty and using these correlations to optimise maintenance effort as well as planning new equipment purchases and warranty conditions.

Jan 1, 2002

Population growth, social inequality, pollution, global warming, poverty, overexploitation of natural resources and biodiversity loss, are a few examples of the many challenges facing the world today. Sustainable development is about meeting these challenges and improving the standard of living for the benefit of the maximum number of people. These issues concern governments, communities, environmental and social action groups and individuals all over the world. Business too, has a fundamental role to play in delivering sustainable development. In particular, sustainable development is becoming increasingly recognised as a critical issue for the oil and gas industry to address and act upon. BP is committed to positively respond to the challenges posed by the objective of sustainable development.

Jan 1, 2002

The interaction between ore-bearing fluids and the siliciclastic rocks typically hosting orogenic gold deposits in Phanerozoic metamorphic terrains result in the development of a distinctive alteration halo. Along with petrological changes such as the replacement of chlorite by carbonate and the growth of sericite, characteristic geochemical modifications take place within this alteration envelope. These include variations in elemental abundances and more or less pronounced shifts in the H, C, N, O, and S isotopic signature of the ore system. æFingerprintingÆ these isotopic trends can provide exploration with additional vectors towards the ore zone, and yields valuable information regarding the source of the hydrothermal fluids and the solutes contained therein. Data from radiogenic isotope systems such as Sr-Rb, Ar-Ar, Xe-Ra, Pb-Pb, Re-Os, Sm-Nd, and U-Pb can constrain the kinematic history of ore-hosting structures, provide important clues concerning the absolute timing of gold emplacement, and enable the detailed characterisation of associated intrusives with respect to their magma source(s) and crystallisation age. Although high analytical costs, long turn-around times and the potential for misinterpretation prevent isotope systems from offering a æquick & dirtyÆ analytical method that would provide a significant advantage in exploration for orogenic gold mineralisation, the development of integrated four-dimensional ore genesis models depends heavily on constraints obtained from isotope mass spectrometry.

Jan 1, 2002

As the theme of the conference is ære-discover Otago' from the minerals point of view, it is also timely. Of the eight million ounces of gold recorded produced from Otago, perhaps a quarter of this came from the goldfields of St Bathans, Vinegar Hill and Cambrians. The most notable among them was the Kildare Hill Mine, which is the so-called Blue Lake at St Bathans today. The bottom wash encountered in this mine contained the famous Kildare lead, which averaged 7 1/2 dwt to the dish, and is still one of the richest leads of alluvial gold known in the world. The richness of this lead, the best encountered in these gold fields, is otherwise stated to have yielded more than 42 ounces of gold to the cubic yard. It should be borne in mind that this equates to about $22 000 per cubic metre, in todayÆs values. I have been told by older residents of this district that in fact about 1 million ounces came out of the Kildare mine and associated workings. In todayÆs values, this would be about 530 million dollars worth of gold. The largest mines in the district were at Surface Hill, Kildare Hill, Nicholsons, Vinegar Hill, the Never Fail claim at Shepherds Flat nearby, and at Cambrians. It would appear that in almost every case, work stopped when the bottom wash progressed too deep down dip of the anticline hills on which it was initially found. The mining methods were sluicing and hydraulic elevating, and although the gold bearing ground did not stop, eventually it exceeded the ability of the mining methods then available years ago, to work it further. When it is realised that the previous mining has removed what is likely to be only a low percentage of the gold resources in these fields, a tantalising situation presents itself today in that mining technology now available will enable another cut to be taken off these fields. As in the past, I believe this will be million ounce plus and multi-million dollar scenarios, where the economic and social benefits will become widespread prizes.

Jan 1, 1992

By R Ulusay

Rock mechanics involves characterizing the mechanical properties and behaviour of rock material and the natural discontinuities of the rock mass, while rock engineering is concerned with specific engineering circumstances, for example, how much load will the rock support and whether reinforcement is necessary. Rock engineering models developed depend considerably on the input data such as boundary conditions, the properties of rock material and rock mass. Correct evaluation of these properties frequently requires laboratory and in-situ tests, supplemented with a high degree of experience and judgment. Accordingly, since 1974, the ISRM Commission on Testing Methods has spent considerable effort in developing a succession of the ISRM Suggested Methods (SMs) for different aspects of rock mechanics and rock engineering with the contribution of a number of working groups and cooperation of some other ISRM Commissions. This paper emphasizes the need and importance of standardization of rock testing methods within the context of the ISRM SMs, gives a guideline for developing ISRM SMs and finally discusses on some implementation and contractual issues associated with rock testing and experienced in practice, and briefly introduces main future trends in rock characterization, testing and monitoring. This is an extended abstract only. CITATION:Ulusay, R, 2018. Standardisation on rock characterisation, testing and monitoring with emphasis on ISRM suggested methods, practical issues and difficulties, and future trends, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 17–18 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By Johnson CR, Wilkie G

The aim of the study was to use quantitative mineralogical measurements to predict the processing characteristics of an ore. Samples were taken from a wide range of concentrators processing ores of lead, zinc, copper and nickel. QEM'SEM was used to measure the characteristics of the ore feeding the plant. Concentrate product samples, together with plant operating data were used to give concentrate grade, recovery and grind size information. It was found that the mineralogical measurements correlated well with the metallurgical parameters indicating that these techniques will be very useful for making predictions in feasibility studies and simple plant optimization.

Jan 1, 1989

Silver and gold bearing ore from the Palmarejo mine, located within the Mexican state of Chihuahua, contains a complex mix of electrum, native silver, silver sulfides and silver chlorides. This paper presents a case study that describes the selection, development and engineering of a tailored process plant for the recovery of silver and gold from this ore. Process circuit feasibility study modelling, metallurgical test work and engineering studies are outlined. Options considered to optimise the recovery of the contained silver and gold are compared, based upon cost, operability, recovery and engineering aspects. Concentration by flotation was found to be the preferred primary recovery route. Intensive leaching of the flotation concentrate resulted in solution grades sufficient to allow direct electrowinning to be evaluated against the more traditional Merrill Crowe process. The flotation tailings stream is processed through a separate leaching stage as there is sufficient economic metal extractable from this stream. The processing flow sheet, which is designed to maximise the recovery from both the flotation concentrate and tailings, and to utilise a common metal production facility, is presented.

Jan 1, 2009

By M Ujihira, M Komazaki, K Higuchi, D F

A diesel engine with a misfiring cylinder is likely to break down in a short time when the engine is used without maintenance. The authors have developed a method of detecting the occurrence of cylinder misfiring and specifying the misfiring cylinder by using wavelet analysis and statistical analysis on the root mean square (r.m.s.) values of two kinds of acceleration waveforms. This detection method is considered superior to traditional methods, which require several accelerometers, especially in terms of simplicity. Since the development of the method, research has been conducted on semi-automatic processing of measured signals and signal transmission from the worksite to a remote office. Field tests confirmed that 1 + 105 points of dynamic data could be transmitted through the mobile multimedia network within 15 minutes, and the time for signal processing was within 15 minutes. Final determination on the condition of a diesel engine in heavy machinery could be achieved within 30 minutes. Shortened processing time is expected by improvement of the processing software.

Jan 1, 2003

By M D. Kuruppu

Fleet operational effectiveness is fundamental to any operation, becoming highly topical in mines experiencing less than optimal output from their fleets. It is an all encompassing aim to identify those factors that could be improved within production and suggesting solutions in order to optimise the existing fleet and obtain the highest return on capital expenditure. The fleet operational effectiveness of a large open pit truck and shovel operation in Western Australia was examined and a study was undertaken allowing identification of areas falling below target. The annualised hours and production downtimes were investigated to quantify the potential gains of improvements in these areas. The project aimed to maximise direct working hours through determination of the main issues hindering performance. External and internal factors were considered and a continuous improvement program (CIP) was developed. The CIP aimed at internal site-based improvement teams to identify and implement solutions for improvement on a day-to-day basis. Strategies were then identified for the implementation of the proposed changes.

Jan 1, 2003

By Canterford J. H, Bologiannis F, Smith A. N

The Mutooroo copper mine is one of a number of deposits that have been evaluated by Adelaide and Wallaroo Fertilizers Ltd as a source of feed for the production of high- purity copper oxide at their Burra plant. For this deposit, the technique of solution mining or in-situ leaching appeared ideal. The Mutooroo production circuit and the results of the process optimization and environmental monitoring programmes are outlined. At the end of the experimental period described here, the production liquor typically contained I g/litre copper, yield- ing in excess of 5 t/month of cement product containing about 80 per cent copper. The environmental monitoring programme provided clear evidence that there had been no un- acceptable alteration to the properties of the groundwater in the country rock surround- ing the mineralized zone. It is anticipated that the experience gained at Mutooroo will be of considerable help in the development of other solution mining operations.

Jan 1, 1983

By Peverett N. F

The purpose of filtration in a gold reco- very plant is to separate the gold bearing liquid from the solids in the slurry. Some of the gold is inevitably lost due to incomplete separation. An investigation recently completed by the authors has brought to light a method of reducing such losses. In this investigation, the filtration pro- cess was represented by a steady-state mathema- tical model which took account of 14 indepen- dent variables and three parameters. One of the filters in the plant at West Driefontein Gold Mine in South Africa was isolated from the rest and fully instrumented. A computerized data acquisition system was installed close to the filter, and the data obtained from it served to test the model. Using the model together with an optimizing program, the optimum operating point for the filter as a function of throughput was found, and a control strategy developed to minimize the total gold losses in the filter plant.

Jan 1, 1977

By Pollard D, Meadows N

The presence of impurities which are electropositive to zinc in acid zinc electro- lyte causes changes to deposit morphology and reduced current efficiency. Glue may be added to control some impurity effects, but assaying for animal glue concentration is difficult and seldom done. Measurement of the activation overpotential for zinc deposition by cyclic voltammetry is used in some plants to monitor electrolyte quality and control glue additions. The deposit morphology and current efficiency of zinc deposition from commercial electrolyte were investigated for various glue additions in the presence of increased levels of antimony. Cyclic voltammetry was invest- i,ated as a method of optimizing glue additions in the presence of antimony. Scanning electron microscopy showed deposits characteristic of the impurity element present and the glue addition rate. Cyclic voltammetry measurements showed some correlation between current efficiency and activation polarization potential. The importance of using tankhouse electrolytes where results are to be related to tankhouse operation was noted.

Jan 1, 1984

By E Heath, F McDermott, S Turner, P van Calsteren

U-Th isotope studies of recent volcanic rocks may be used to evaluate the depths and rates of melt generation beneath midocean ridges and ocean islands. Island arc rocks exhibit a similar range in Th isotopes to that seen in both MORB and om, but while those with high (230Th/232Th) tend to have excess 238U, many of those with low (230Th/232Th) are in isotope equilibrium. The excess 238U is attributed to the preferential mobilisation of U in hydrous fluids from the subducted slab within the last 100 000 years, whereas the low Th isotope ratios in the higher-K arcs are primarily due to the introduction of subducted sediment. Preliminary results from mineral separates from lavas on Soufriere on the island of St. Vincent indicate that some of the minerals crystallised up to 50 000 years prior to eruption.

Jan 1, 1995

By Scott IR

In stratigraphic orebodies, estimation of footwall and hangingwall location is often of more importance than grade estimation. Contoured grade estimates often produce smeared boundaries and the use of accumulations and thicknesses as variables re-introduces the original problem: location of the point at which the estimate is to be made. The paper introduces statistical and geostatistical techniques for the solution of the problem and illustrates the techniques with a case study from Mount Isa, one of the world's largest producing silver-lead-zinc deposits. Solutions for calculating variograms in orebodies of variable dip, strike and plunge are presented together with relative variograms for individual metals, metal accumulation and orebody thickness. Optimal methods for hangingwall and footwall location are introduced and illustrated with an example. Orebody boundaries are then kriged after which individual metal grades are kriged within the estimated boundaries. The boundary estimates are compared with manually interpreted boundaries and known boundaries in mined-out areas. Grade and tonnage estimates are compared in mined-out areas.

Jan 1, 1986

Sasol Roche Blasting Services (SRBS) and its former owners have been in the process of developing and utilising low-density explosives over the last ten years. Many blasts have been fired in varying strata types in a number of mining operations. This has led to a good understanding of the product and the best methods to exploit its characteristics when designing blasts. Unlike some other low-density products, SoftLOAD« is a homogeneous mix that is easily handled and able to be loaded at high load rates. This paper discusses the physics of SoftLOAD« low-density explosives and how through correct utilisation, blasting outcomes can be significantly improved. It also touches on the various side benefits that can provide the blast designer with a more controlled blast.

Jan 1, 2004

Were it simply a matter of extracting tin from the simple tin sulphide, the proposition would undoubtedly be simple enough. When, however, other valuable metallic sulphides are combined with the tin, and it is required to separate these intomarketable products, then the proposition becomes somewhat complex, and such is the case with the class of material of which I am about to write. The locality where it occurs is Howell, New South Wales, and chiefly at the Conrad Silver-Lead Mine. The tin sulphide occurs chemically alloyed with copper, iron and other metals associated with galena, pyrites, mispickel, blende and silver sulphide in varying proportions, and generally in a gangue of highly crystallised quartz.Several varieties of tin sulphides occur, and from the following analyses of three minerals, these being specimens specially selected free from foreign matters, it will be seen that the chemical composition is somewhat complex.

Jan 1, 1902