Search Documents

By S Arthur, J Mills, A R. Penney

A key aspect of seismic management for narrow vein stoping of the west zone at the Beaconsfield Gold Mine has been the development of a fully remote extraction method that does not require personnel access to sill drives within the orebody once stoping commences. Initially, sill driving within the reef is undertaken in a conventional fashion under geological control. Sill drives are developed at a vertical backs-to-floor height ranging from 7 - 12 m. This mining stage includes all activities prior to the commencement of stoping, after which no personnel enter the unstoped section of the sill drive at any time for any purpose. The key aspect of the remote mining cycle is the use of footwall drill drives paralleling the ore drive at a minimum separation of 6 m under survey control. These drives provide the platform for fan drilling of the orebody. Up to 20 m strike panels are blasted in a single shot using electronic blasting techniques. Ore is mucked from the extraction level sill drive using tele-remote loaders. Aerials for tele-remote operation are installed through boreholes from the footwall drive, negating the need for personnel access to the sill drive. Once mucking of a stoping panel is complete, a laser scanning survey instrument is used to survey the final void for subsequent design and production reconciliation purposes. The survey instrument is mounted in the bucket of the tele-remote loader, and is also operated remotely. Finally, tele-remote loaders are used to dump waste rock fill from the upper sill drive. A system of flags and cameras installed in boreholes from the footwall drive assists the operator in locating the live stope edge during the filling cycle, again negating the need for personnel access.

Jan 1, 2008

The price of oil and other minerals may not make the costly business of offshore exploration seem -attractive at present. There is little doubt that the future search for the strategic resources will tend towards deeper waters particularly on the continental slope margins. In addition with the realisation that active tectonic environments (eg the Makassar Straits) cannot be excluded as potential hydrocarbon sources there is an increasing demand by the explorationists for deep water survey capability. Such deep water research has until recently been restricted to a few specialised academic institutions ;however with the anticipated extra, demand from other institutions, companies, and government agencies, Marconi Underwater Systems Limited (MUSL)and the Institute of Oceanographic Sciences in the UK have come together to allow MUSL to provide the deep water mapping system GLORIA on a commercial basis -for the first time. The GLORIA package comprises a deep water(more than 400m) side scan sonar system which, by operating at a frequency around 6.4 kHz can insonify swathes on the seafloor up to 60 km wide. In addition, single channel seismic, 3.5 kHz high resolution profiles, precision echo sounding, magnetic and gravimetric data all combine to provide as complete a regional interpretation as possible. The GLORIA system combines surveying at a reconnaissance level, covering as it does up to 20,000 sq.km per day, with a very high reliability, so that even in- economically unfavourable times, it can-still be considered as an invaluable and cost effective primary exploration tool. Analysis of the GLORIA data enables the identification of areas of particular interest requiring more detailed study by the more costly multi-channel seismics at a later date.

Jan 1, 1987

This paper traces briefly the reasoning which led to the decision to extend the existing internal shaft at the Rosebery Mine and to instal underground a larger winder (No. 2 Hoist) with capacity to handle all hoisting requirements to a depth of approximately 2,500 ft. on an incline varying from 83" to 55" to the horizontal. It then covers the specifications and selection of the winder, the design of the winch chamber, rope raise and bins, the excavation, support and lining of the chambers and the transport to site and installation of the machinery. Finally a brief description is given of the mechanical and electrical parts of the winder.INTRODUCTIONThe existing shaft winder on the internal inclined shaft situated on No. 8 Level of the Rosebery Mine had reached the limit of its capacity. Hoisting 21-ton capacity skips in balance, with a 13/16-in. diameter rope, it required four layers of rope on the 3 ft. 6 in.drums to reach the loading station under No. 12 level at a depth of 864 ft. (Fig. 1). This entailed heavy wear on the multi-layered rope and heavy stresses on the cheeks of the drums. Continuous working on three shifts was necessary to handle ore, men and materials, and a hold-up from any cause whatever meant an interruption to production on the lower levels of the mine. The maximum output of the hoist whilst hoisting from the No. 12 level loading station was 50 tons per hour. It was obvious therefore, that a larger winder was required if output was to be maintained.Diamond drilling had proved the existence of sufficient ore at depths well below No. 12 to warrant exploitation and a decision had to be reached on the means of hoisting this ore.

Jan 1, 1958

By J Webb

Anoxic limestone drains (ALDs) have been widely used in the passive treatment of acid mine drainage (AMD), but their effectiveness has often been less than anticipated. Iron hydroxide often precipitates around limestone particles and inhibits neutralisation. To determine the conditions under which iron hydroxide precipitates, a small-scale laboratory ALD system was built to enable a detailed examination of the chemistry of iron within the drain. For one experiment, a mixture of limestone and quartz was introduced to the drain to assist in the determination of the key mechanism governing iron precipitation. Synthetic anaerobic acid mine drainage containing Fe2+ (~130 ppm), SO4 2- and H+ was pumped at a rate of 30 mL/min up a 90 cm tall, 15 cm diameter vertical column filled with limestone gravel of 98 per cent purity. Three sampling ports were fitted at equal intervals along the column; water was periodically extracted for analysis at the sampling ports over an 11-hour period. Experiments were run at influent pH levels of 2 and 4. Results show that acid neutralisation to pH greater than 6 occurred at the inflow end of the drain. The greatest amount of iron precipitation (19.5 per cent) also occurred in this area. The lack of iron precipitation on the quartz surfaces in the quartz/limestone mixture indicates that neutralisation is the key mechanism for the precipitation of iron hydroxide on limestone particles. A pe-pH stability diagram derived for the laboratory ALD system indicates that ALDs will not be effective for AMD with pH 2. Influent waters with pH 2 require a pe of -2 (Eh: -118.4 mV) to avoid Fe precipitation upon neutralisation. Influent waters of pH 4 require a pe between -2 and -4.

Jan 1, 2003

By T J. Howard

At BHP Billiton Iron Ore operations, run of mine ore from the several Newman Joint Venture (NJV) mines is railed in 12 kt rakes to Port Hedland. Rakes are processed sequentially, with the lump and fines components from each rake sampled after crushing and screening. The grade of ore from the individual mines varies around consistently different means. Although a discrete sample is attributed to each rake, the sample contains some material from the following and/or the preceding rakes due to dilution by ore from the neighbouring rakes during the dumping, screening and crushing processes. Individual rake grades at the port are therefore biased according to the mine sources of adjacently processed rakes. Dilution does not affect the grade of the overall NJV product or the accuracy of port stockpile grades; however, it does limit the ability to use port rake grades to review the quality performance of individual mines and provide meaningful lump-fines algorithms and port to mine biases for individual mines, information that is useful when scheduling ore for mining. A non-linear regression model has been used to estimate the average dilution from the preceding and following rakes. It has been shown that the lump and fines samples for 12 kt rakes are each diluted within the Port process with about 8.3 per cent of the sample coming from the preceding rake and about 3.6 per cent from the following rake. This can bias the reported rake grade by up to one per cent iron. The results of this analysis have been incorporated into the daily grade scheduling system to provide more accurate individual mine grade data and consequently better decision making.

Jan 1, 2007

By P Voigt, B Lumsden, P Lines, I Gurnett

Plant tests of magnetic conditioning have shown increased flotation recovery of paramagnetic sulfide minerals (chalcopyrite, sphalerite and pentlandite) in the -38 ¦m size fraction within rougher and cleaner flotation circuits. A statistical plant test was undertaken in the Mount Isa zinc flotation circuit where magnetic conditioning was tested simultaneously in both the rougher circuit and the cleaner retreat circuit (cleaner scavenger). This test resulted in a normalised increase of 1.60 per cent in the rougher circuit zinc recovery and simultaneously a normalised increase of 4.60 per cent in the cleaner retreat circuit zinc recovery - to a very high level of statistical confidence. Interestingly, in a novel approach, it was possible to verify the plant test results in two ways. Firstly, detailed MLA analysis of the tails confirmed the statistical plant test results and showed that the greatest effect of magnetic conditioning was on the sphalerite in the C3 - C6 size fraction, where there was a reduction of around 15 per cent in zinc in tails. Moreover, there was a reduction of around 15 per cent in liberated sphalerite across all -38 ¦m size fractions, but only a seven per cent reduction in non-liberated sphalerite in the tails. Secondly, plant modelling showed that increasing the rougher zinc recovery would cause an increase in zinc feed grade to the cleaner retreat circuit. The increase in the zinc feed grade to the cleaner retreat circuit with magnetic conditioning was demonstrated to a very high level of statistical confidence.CITATION:Gurnett, I, Voigt, P, Lumsden, B and Lines, P, 2012. Magnetic conditioning of sphalerite at XstrataÆs Mount Isa Zinc Operations, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 233-240 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

The general principles of technical due diligence best practice that are involved in assessing a mineral property in the early stages of its development are described and a bibliography of relevant papers is attached. The issues specific to the evaluation of gold deposits are highlighted. The Australasian Institute of Mining and Metallurgy's (The AusIMM) initiatives in this area, dealing with the proper public reporting of Reserve/Resource information (JORC Code) and property assessment/valuation (VALMIN Code), will be used as a framework against which the illegal tampering with drilling samples to artificially boost their gold content (salting) from the Busang gold deposit (Kalimantan, Indonesia), owned by Bre-X Minerals Limited (Calgary, Canada), will be reviewed. While the Busang saga was based upon fraud, through salting the samples, the general lessons to learn from such a scam are worth documenting. In Australia, most of those working in the mineral industry belong to long established professional institutes and consultant associations (eg The AusIMM or Mineral Industry Consultants Association [MICA]) that require their members to work within their technical limits and to comply with best practice guidelines, or risk being judged and found wanting by their peers in the context of strong Ethics Codes. There is also a strong interface between such representative professional bodies and the corporate and financial market regulators (ASC/ASX), which closes the monitoring loop. Canada has only now seen the wisdom of having this type of early warning system in place. Fraud and deliberate deception will be always possible, but deception on the enormous scale that occurred at Busang is most unlikely with proper surveillance systems in place and the use of accredited technical professionals. There should have been more hard data available about so big and rich a deposit owned by a C$6Bn company.

Jan 1, 1997

By N McKenzie, F Brodbeck

The North-South Bypass Tunnel is the first project to get underway as part of BrisbaneÆs transport plan, which aims to improve the urban road network. The total length to be excavated is 6.8 km, which includes 4.8 km of driven tunnel and associated road connections. Construction commenced in August 2006 with project completion targeted well before the contractual completion date of October 2010. Due to the local geology, in particular the hard Brisbane tuff and neranleigh-fernvale formation, a combination of tunnel excavation methods are used. The majority of the tunnel is excavated by two tunnel boring machines which have a rate of progress of 16 - 20 m per day in rock having a compressive strength of between 80 and 150 MPa. Ten roadheaders operate at a rate of up to 2 m per day excavating the remaining tunnels, such as ramps, access tunnels, cross passages and merges. The tunnel team are managing the challenges and complexities associated with tunnelling through the hard Brisbane rock. A major challenge arose during the planning of the initial mainline excavation underneath the Royal National Association Showground in Bowen Hills. This section contains low rock cover and historical maps indicate that the showground is located within a former topographic depression (alluvial valley), which a creek once flowed through.Due to traffic merge design requirements, both tunnel boring machine (TBM) and roadheader excavation methods were required to be used in this challenging geological profile. The answer was to stabilise the alluvium above both TBM section tunnels from the surface prior to excavation and to operate the TBM in single shield mode with immediate grouting of annular void from the tail shield. In addition, the roadheader section of tunnel required additional support by spiles and canopy tubes installed from the tunnel face.

Jan 1, 2008

By X Li, W McKeague, M S. Powell

This paper explores the importance of operators in the overall efficiency of mineral processing plants. With the potential of future control configurations becoming more remote, it is time to review the implementation of control and utilisation of operators. This paper is based on a preliminary review of operators and control room operations and clearly shows that, in the minerals industry, operations are typically run in a reactive mode (with a focus on ensuring equipment operation), rather than in a proactive mode (with a focus on optimising the process performance). The primary reason for this misguided approach is the short sighted thinking applied to the challenges of designing technology and organisational tools capable of addressing the essential operational needs: an approach which inevitably results in a disconnect between people and technology. Contrary to the popular approach of replacing operators with expert systems, the thesis of this paper is that the shift to more complex circuits, with higher demands on processing capability and control, will require the actual upskilling of operators. Experience in mineral processing and other industries indicates that expert systems cope well with small changes but are typically unable to respond to major changes in feed material and this is where the expert operator becomes crucial. Providing operators with ongoing high level training in process understanding, and restructuring how they interact with the plant and interface with the control system is the approach being proposed here - an approach surprisingly underutilised and often absent in the minerals industry today.CITATION:Li, X, Powell, M S and McKeague, W, 2012. Unlocking processing potential by empowering our operators, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 333-340 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By S Dorrington, J Olsen, N Kinkaid

Several studies have been conducted on the economic analysis of mining near-Earth asteroids for resources for use in Earth orbit. While these studies use detailed economic figures of merit, they often use many invalid assumptions in the trajectory design. Factors such as the energy and propellant requirements are estimated with analytic methods, however, the stay-time at the asteroid and the spacing of repeated launch opportunities are not taken into account. The work outlined in this paper attempts to combine detailed trajectory design methods with newly defined economic figures of merit to improve the economic assessment of asteroid mining missions. The study focuses on asteroid 2014 EK24, a near-Earth asteroid with very Earth-similar orbital properties.CITATION:Dorrington, S, Kinkaid, N and Olsen, J, 2015. Trajectory design and economic analysis of asteroid mining missions to asteroid 2014 EK24, in Proceedings Third International Future Mining Conference, pp 281–288 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By J Naude

The TauTona (Sotho for Great Lion) Mine near Carletonville, which is one of AngloGold AshantiÆs most profitable operations in South Africa, has started a multi-million dollar expansion project that is expected to extend the operational life of the mine by at least three years. The project will also secure some 1900 jobs for existing workers and contract workers. The $US140 million project entails the development of the orebody to a record depth of almost 4 km underground. It means that TauTona, which already mines gold at the deepest levels in the world, will deepen its mining activities from 3600 m to a new record depth of 3910 m. There is great anticipation about the expansion program, especially because of new technology that will contribute to a safer working environment. It includes a simplified hoisting system that will minimise safety risks in conveyance activities. Due to the unique nature of this project, depth below surface and working through a three-tier shaft system, various innovative measures were incorporated into the planning of the endeavour. Special support equipment was designed to reduce cycle times and enable the crews to install the extensive support, prescribed by the mineÆs rock engineering department, right up to the face before every blast. Both declines dip at 23¦. The personnel/material (P/M) shaft is 4.4 m wide x 3.9 m high. This shaft is unique in that the conveyance will have an onboard driver. The rock shaft is 4.5 m wide x 3.6 m high. Rock will be hoisted with two, ten-tonne overturning skips. In both cases, P/M and rock, the winders were designed for the highest duty cycle, which is encountered during sinking.

Jan 1, 2005

The Osborne copper-gold deposit (within the Trough Tank project area) is located in the Cloncurry Shire about 195 kilometres south-east of Mount Isa. It is hosted by Proterozoic metasediments of the Eastern succession of the Mount Isa Inlier. The deposit is overlain by 25-40 metres of Mesozoic cover, so it represents a true "blind target". Placer Exploration has 100% outright ownership of the property, having purchased the remaining 10% interest in the property from Shell in early 1993.Intensive exploration, both surface and via drilling at Osborne, has taken place since 1985, when CSR Limited Mineral Exploration and Development Group (acquired by Placer in 1988) entered into a joint venture with Billiton Minerals. Exploration effort from 1985 to June 1988 outlined a 20 kilometre strike length of magnetic horizons, in what was termed the North-East, Central and Southern anomalies, which were drilled with weak indications of copper-gold mineralization in the North-East anomaly. During the later half of 1989, four core holes were drilled into the shallower northern partofthe North-East anomalywhere previous drilling had outlined economic intersections of mineralization. These holes encountered high-grade copper-gold mineralization confirming the potential for an economic deposit to be hosted within the ironstone sequence. Further drilling involving over 400 holes (100 kilometres of drilling) has brought the deposit up to its present resource status.The current resource inventory is 36 million tonnes grading 2.0% copper and 1.0 grams pertonne gold and includes a high-grade zone of 13 million tonnes grading 3.6% copper and 1.5 grams per tonne gold. The discovery of this potential economic mineralization resulted from a persistent exploration effort based on indications that a large mineralizing system existed within a sequence of ironstones.

Jan 1, 1993

By P D. Munro

"This is a reprise of the paper ‘Back to the Future – Why Change Doesn’t Necessarily Mean Progress’ presented to the Tenth Mill Operators’ Conference in 2009. It was observed that the ‘boom and bust’ cycles of the industry, together with trends in tertiary education and the effects of fly-in fly-out (FIFO) operations raised serious questions about the sustainability of human capital in the mineral processing sector.In 2016 we find ourselves in a ‘bust’ after enjoying a decade of the longest commodity price ‘boom’ in a century. In the ‘boom’ did we:make any technological breakthroughs?put measures in place to improve our human capital, especially in the area of ‘professional formation’?The paper makes observations on the current performance of mineral processing engineers and the organisational milieu in which they operate. It questions whether mineral processing engineers are actually ‘adding value’ at some sites given their organisational and operational practices.Some technical trends are examined and what it might mean for mineral processing engineers.Given the above and demographic trends for mineral industry professionals, changes to the seemingly current laissez-faire model of professional development are proposed.Citation:Munro, P D, 2016. Back to the Future - Still on the Dark Side, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 341–348 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By G I. Lumley

‘Every mine is a pilot’ is an attitude which encourages the mining paradox of optimistic mine plans and equipment under performance; propped up by an environment lacking accountability. The premise that ‘every mine is a pilot’, appears to underlie the development and operating approach to most mines. It is the hypothesis of this paper that many mining companies, development teams and their managers largely ignore what is done elsewhere. Anecdotally, most planners don’t know whether the selected rates are high or low (rates based on theoretical models tend to be high – certainly higher than what most companies can achieve). Mines then consistently operate the equipment at rates well below targets; often more than 20 per cent below. Further to this paradox, mine performance data demonstrates the average mine is currently operating their equipment at levels of output not much more than half the output of those in the top ten per cent. On the whole mines don’t know the potential of their equipment and therefore don’t put appropriate plans in place to do better. After all, when ‘every mine is a pilot’ there is little reason to look to one’s peers for an indication of potential. This paper will outline why every mine is not a pilot and how mines do value some knowledge, but not as much as they should. This paper proposes a two-pronged approach to address this issue in the area of equipment performance. This approach is to:1. engage in better forecasting of equipment rates and better subsequent performance through benchmarking against industry standards2. provide conditions for more accountability.These parameters are linked and proper implementation of them will address the losses which many shareholders and financiers have incurred when investing in companies with unrealistic mining plans.CITATION:Lumley, G I, 2016. Is every mine a pilot? In Proceedings International Mine Management Conference, pp 75-88 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

Coal losses and dilution are among a coal mine operators everyday problems. These losses and unwelcome additions are generated primar- ily by the stripping operation and secondly by the coal mining opera- tion. Losses in yield due to preparation plant efficiency are a separate issue although they may be related to the coal mining operation. The losses and dilution can be traced to the following operations: (A) Overburden or Interburden Removal (1) Removal of coal edge by blasting operations. (2) Removal of top of seam by drilling/blasting. (3) Removal of top of seam by stripping equipment. (4) Removal of coal edges by stripping equipment. (5) Dilution due to stripping equipment. (B) Coal Mining (for the case where seams are ripped rather than shot) (1) Coal rib losses. (2) Coal rib dilution. (3) Coal left in floor. (4) Coal left in fault areas. (5) Floor material picked up whilst loading. (6) Spoil material picked up. (7) Spoil material from poor surface clean up. (8) Top of coal losses from final clean up. (9) Dilution from ripping too deep, i.e. into floor below seam. (10) Dilution from interseam parting. The losses apply to both the single seam and multi seam oper- ations although they are more pronounced in the multi seam mines than in a single seam mine due to the position of the coal which is lost. For example in the multi seam case the top seam coal edge loss is final. There is little chance of recovery with the subsequent pass even if the extra rehandle is done. However conversely the lower seam is relatively easy to locate as it has nowhere to go being contained by the lowwall bench.

Jan 1, 1988

A viable flow sheet of the sorption-flotation technology for gold recovery from low-grade ores and concentrates using powdered activated carbon modified by organic compounds as the sorbent-bearer has been developed. The powdered activated carbon, with high kinetic ability and sufficient specific area, was selected as the all-purpose gold cyanide complex-bearing sorbent which is active during flotation. To improve carbon adsorption capacity and to provide the required floatability its porous structure was filled with a quaternary ammonium compound which can extract gold cyanide complexes and render additional flotation properties to the carbon. To optimise the process and to simplify the layout, adsorption and flotation processes were carried out simultaneously in a mechanical flotation cell. The proposed technology was used for extended and pilot-plant tests of sorption-flotation gold recovery from 0.6 g/t Au final tailings and 2.0 g/t Au gravity tailings. The extended tests were carried out on Taseevskaya (Chita Region) flotation tailings, whereas pilot-plant tests were conducted on Kommunarovskaya (Krasnoyarsk Region) gravity tailings passing to cyanidation, followed by processing with filtration technology. Additional gold recovery from Taseevskaya final flotation tailings was 50.8 per cent. Gold recovery from Kommunarovskaya final gravity tailings was 92.5 per cent. Compared to the complete sludge process conventionally used at the plant, gold recovery was increased by 7.5 per cent due to lower gold losses in the liquid phase and conversion of the refractory non-cyanided metal into a carbon concentrate. This paper presents the experimental results of gold adsorption onto powdered activated carbon modified with quaternary ammonium compounds (sorbent-bearer) as well as sorbent-bearer flotation with various collectors from cyanide solutions and pulps.

Jan 1, 2005

By J-P Franzidis

The Floatability Characterisation Test Rig (FCTR) is a self-contained, highly instrumented, mobile pilot plant. It was developed as part of the AMIRA P9 project, primarily to determine ore floatability characteristics and to develop and validate flotation plant modelling, scale-up and simulation methodologies. This paper describes the use of the FCTR in validating the AMIRA P9 flotation model and modelling methodology. In 2001 the FCTR was installed and operated in parallel with WMCÆs (now BHP BillitonÆs) Kambalda Nickel Operation. The FCTR was operated using four different circuit configurations of increasing complexity. Metallurgical surveys, cell characterisation measurements and batch flotation tests were performed around each circuit. This allowed the calibration of a number of flotation models using a combination of data from one, two, three or four circuit configurations. The calibrated flotation models were then validated using predictive validation. To do this, data around a further five FCTR circuit configurations were collected (three of which are presented in this paper). The performance of each of the five circuit configurations was predicted using JKSimFloat V6.1 and the parameters from the various calibrated flotation models. The predicted performance was compared to the experimentally determined performance of each circuit. The validation of the AMIRA P9 model was shown to be largely successful except in the case where the reagent addition (depressant) to the validation circuit was different to that in the calibration circuits. The results also provided information regarding the required complexity of the calibration circuit and how many calibration circuits are required to obtain an accurate prediction of circuit performance. These results have increased the confidence in the AMIRA P9 flotation modelling methodology and have provided important information on what data must be collected to allow the accurate prediction of plant performance using the floatability component modelling approach.

Jan 1, 2007

The subject of steel wire ropes covers such a wide range of points that it would be impossible to deal with it fully in one paper, and in view of the apparent scarcity of published information on the subject it is proposed in this paper to deal with those items which should give the mining engineer a better understanding of the basic factors which affect the design.selection, and use of ropes. The matter will be considered under the following headings:-1. Brief history of steel wire rope-making.2. Rope-making terms.3. Wire rope materials.4. Characteristics affecting economy, operating life, and serviceability of a rope.5. Properties of construction of rope, and stresses met with in wire ropes.6. Drum and sheave sizes and sheave bearing pressures.7. Storage, handling, and maintenance of ropes in service.8. Common factors affecting rope life, particularly winding and haulage ropes.9. Inspection of ropes.GENERALWire rope, which was invented for, and first applied to mine winding, has become an indispensable aUXiliary throughout the whole field of mining, be it for underground, open cut, or dredge work, as well as the requirements of transport and treatment of ores.Though wire ropes appear simple collections of wire and fibre, the demands made upon them are many, and the stresses and abuses to which they are exposed in service are varying, and often of serious dimensions.The exposition of these stresses and abuses, particularly dynamic stressing, corrosion, etc., all of which seriously affect the safety and economical life of the ropes, is often enough to frighten most practising mine staffs, who are aware that before the requirements of economic operation stands the still more important question of safety in mining.

Jan 1, 1947

Mt Muro was a gold and silver mine in Central Kalimantan on the Island of Borneo, Indonesia. Aurora Gold through its Indonesian subsidiary Indo Muro Kencana owned the project. Processing commenced in November 1994, and ceased in June 2002. Mining, including prestripping, commenced in March 1994, and ceased in May 2002. Nominal throughput was 1.5 Mtpa, at average grades of 3.80 g/t Au and 99 g/t Ag. From the start of prestripping until the end of 1996, Drill Blast sampling was the main grade control method. After several studies into the viability of Reverse Circulation, including an assessment of costs and benefits, the switch from Drill Blast to Reverse Circulation was made in late-1996. From 1997 until the end of the project Reverse Circulation was the main grade control method. The mine-to-mill call factors û the reconciliation between predicted and actual tonnes and grades delivered to the mill û for the period from commencement of processing to December 1996 were 1.069 for tonnes, 0.949 for gold, and 0.969 for silver. The mine-to-mill call factors between January 1997 and June 2002 (excluding a period of significant illegal mining) are 1.086 for tonnes, 0.977 for gold and 1.025 for silver. At face value this indicates a 2.8 per cent absolute improvement for gold, and 5.6 per cent for silver. Using average grades for the project, an additional 5112 oz of gold, and 267 173 oz of silver were delivered annually to the mill using Reverse Circulation sampling instead of Drill Blast sampling. The additional recovered metal value is estimated at $US 2.87 M annually, significantly exceeding the cost of Reverse Circulation drilling. This paper discusses a number of issues that may affect the estimated benefits.

Jan 1, 2003

By A F. von Wielligh, M Scott, L Keeney

Operational Grade Engineering (GE) is the early (pre-processing) discard of low-grade mineralised and/or barren rock to improve the ore grade and/or reduce deleterious elements within the run of mine ore to be processed. GE activities generally have an impact on primary and ancillary mining activities, equipment utilization and overall equipment productivity. By discarding material which would have reported as ore (in a non-GE mine plan) means that GE must increases the total ore and total rock mining rate requirements to sustain mill feed targets. One challenge of GE and the planning of GE activities is that there are several indirect parameters which impact operational productivity. Modelling these potential impacts and determining if they can be overcome with alternate mine sequences, equipment application or possibly a different equipment fleet altogether is a key question requiring investigation. Overcoming these potential productivity obstacles associated with a more complex operation by introducing new operational parameters and destinations for ore and possibly sub-grade blocks, requires a GE mine plan that is coupled with detailed equipment productivity metrics and a sound operational plan incorporating all GE infrastructure requirements. Several GE mine plans and equipment productivity models indicate that mining rates generally need to increase by approximately 5% to 15% to sustain mill targets and often negatively impact equipment unit productivity metrices through increased cycle times, additional queuing and destination changes. These changes to productivity metrics are however offset by step change increases in asset value. This paper details a methodology to develop GE mine plans that incorporate equipment modelling, flexible mine sequencing and equipment-based production scheduling. In addition, the paper will outline impacts of GE planning on equipment unit productivities through worked examples and models.

Nov 10, 2020