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By D S. Stewart, K W. Keskimaki

The Henderson Mine has been utilising a continuous panel caving method to extract molybdenum ore since starting operation in 1976. In the past three decades since the mine was designed, many changes have taken place in underground technology as well as the general nature of the mining business. The impacts of larger scale underground equipment and automation are significant at Henderson and continue to reshape the nature of the enterprise. During the first years of operation in the 1970s, Henderson required almost 2000 employees to achieve full production, today only about 400 people are required to fully utilise the plantÆs capacity. The most recent change to the facility is the conversion from a rail haulage system to an underground crushing and conveying system that transports ore 25 km to the Henderson mill site. This change has required the introduction of large, rubber tired haulage trucks underground and the mining methods necessary to develop the large openings demanded by the trucks and underground crusher. The development of the underground crusher is also the first step to mining the final bottom horizon of the orebody. Along with this move comes an opportunity to almost triple the effectiveness of the mining effort, through higher draw columns and wider draw bell spacing. This final advancement to a totally trackless mine has positioned Henderson well for safe and efficient operation as it enters the 21st century.

Jan 1, 2000

By Beech-Jones J. M

At Port Latta in Tasmania, Savage River Mines operates vertical shaft furnaces for the firing of pelletised magnetite concentrates. At times the temperature profile of the furnace has changed markedly, necessitating the- burning of greater quantities of fuel to maintain good pellet quality. A study of the oxidati=of magnetite concentrates was under- taken because this exothermic process supplies much of the heat required to indurate the pellets. Using the thermal analyses methods, different magnetite concentrates from Australian and overseas were heated in air under identical conditions, to compare rates of oxygen uptake and of heat release. In addition, a compari- son was made of the oxidation behaviour of different particle size fractions of a selected concentrate. Particle size analyses, x-ray diffraction and dilatometer tests were used to aid inter pretation of the thermal analysis traces. The investigation emphasized the importance of particle size and ferrous iron content in determining' oxidation rates from the commencement of heating.

Jan 1, 1974

By Smith DM Jr

Silver deposits, in which silver forms at least fifty percent of the value of the ore, are abundant and large on the east side of the Pacific and are absent in the western Pacific. To determine if this uneven distribution is related to features of consuming plate tectonic boundaries which dominate the metallogeny of the Pacific Rim, the variation of Ag/Au in porphyry copper deposits was used to estimate the relative silver content of magma generated in subduction zones. Porphyry copper provinces with high Ag/Au occur in regions of the eastern Pacific where silver deposits are abundant, suggesting that the distribution of silver deposits is controlled by the relative abun- dance of silver in subducted ocean crust. Ocean crust being subducted in the eastern Pacific is mostly less than 50 million years old in contrast to most ocean crust in the western Pacific which is much older. Enrich- ment of silver in young ocean crust at spread- ing centers may reflect metallogenetic evolution over geologic time. Silver may be transported to the surface in volcanic rocks, and deposits are common where felsic varieties are abundant. The high ,solubility of silver in natural waters provides a natural storage mechanism for silver weath- ered from these rocks and ultimately circulated in near-surface hydrothermal systems where many silver deposits form. The regional distribution of silver deposits is not influenced by discoverability, vertical metal zoning, or regional tectonic style. The effect of igneous differentiation is unclear.

Jan 1, 1987

By Bowdler RJ, Lowson RT, Sarbutt JV

There have been few long-term studies of sulphide oxidation under controlled conditions. The object of this study was to investigate the oxidation and leaching characteristics of pyritic mine material under conditions that were commensurate with field conditions but which could be controlled and monitored on a long term basis. The test material - overburden from Woodlawn Mines Pty Ltd - was packed into a 300 cm high column and leached with water at an infiltration rate of 256 mm y-1 for 5 years. Chemical conditions within the column were continuously monitored by sensors embedded in the overburden and leachate from the base of the column was analysed weekly. The study examined the relationships between heavy metal release and gas, moisture, and chemical conditions in the column.

Jan 1, 1988

By Fulton E, Ring RJ, Waters DJ

Laboratory leach tests of Nabarlek uranium ore carried out by the Australian Atomic Energy Commission to compare the effectiveness of Caro's Acid1 (permonosulphuric acid) as an alternative oxident to pyrolusite indicated reduced acid consumption in leaching and lime savings in neutralisation of tailings liquors when using Caro's Acid. Interox Chemicals Pty. Ltd. arranged a plant trial for Caro's Acid at Queensland Mines Nabarlek Plant. The trial confirmed that significant savings in acid and lime can be achieved under plant conditions. Plant operations also demonstrated improved redox potential control was possible using Caro's Acid.

Jan 1, 1978

This paper is for mine managers. It is about maintenance of mining equipment. This is an extremely broad subject so this paper is given with the caveat that it necessarily contains generalisations, not true in all cases, but broadly correct. The job of mine managers is to be good at making money from the excavation and preliminary treatment of mineral. To do this well, they need to understand the cost and value drivers in the business. This includes understanding the drivers associated with maintenance. Maintenance is often identified as a problem at mine sites. It is frequently listed as the cause of production shortfalls when reporting. The state of maintenance within mining as an industry is generally among the lower end of the range, when compared to manufacturing, petrochemicals, etc. Why is this? Experience and review of many audits and evaluations of maintenance has shown that some patterns are consistent with good performance and some consistent with poor performance. These often centre around the time horizon of the management team and are associated with knowing the sensitivity of the business to certain maintenance drivers and the mechanisms of maintenance and their results. To summarise, some common misunderstandings can be listed as statements that are obvious and extrapolations from those, which are not necessarily correct. For example: High availability of equipment is necessary for production. Incorrect extrapolation:focus on availability will produce high production. Design is often the greatest factor in determining the reliability of a mining machine. Incorrect extrapolation: the newest and biggest machines generally have the lowest cost operations. Operation has an enormous impact on machine productivity and reliability. Incorrect extrapolation: the fastest operators are generally the best from a productive point of view. Some maintenance improves the performance and reliability of machines. Incorrect extrapolation: more maintenance will give you more reliability. Some maintenance depends on disassembly and reassembly of components. Incorrect extrapolation: assembly is basically the reverse process of disassembly. Maintenance improvement in the mining industry in the last 15 years has focused largely on planning and systems improvement. Incorrect extrapolation: most of the problems in maintenance can be traced to a lack of planning. Actions based on flawed extrapolations will steer a business suboptimally. It is therefore important that the mine manager understands these issues so that the improvement effort can be directed to the greatest benefit.

Jan 1, 2006

Consideration is given to the factors affecting raceway activity and the hearth design of a zinc-lead blast furnace. Results of measurements made on operating furnaces are given and comparisons are made with published data both from operating iron blast furnaces and from dynamic models of the zinc-lead blast furnace. Indication is given of the methods used for assembly of the relevant information into the specification of a commercial furnace design. A discussion on the comparative merits of furnaces of circular and essentially rectangular plan is given based on the concepts explained in the paper.

Jan 1, 1981

By Thompson D, Burgess G. C

Subsequent to large scale trials in 1987, the installation of a submerged lance Sirosmelt furnace system was approved in late-1988 for the cupellation of retort bullion to dore silver. Commissioning work commenced in June 1990. During the process air is lanced into a molten slag bath contained in a cylindrical vessel to rapidly oxidise the granulated feed bullion from 15 - 25 per cent silver to rough dore grade. The process is now an integral part of the Precious Metals operation replacing the first stage reverberatory cupellation furnaces to achieve productivity improvements, lower silver inventory and increased silver Recovery.

Jan 1, 1992

By T Goswami, M Edmondson

Henry Walker Eltin (HWE) are the mining contractors for Gloucester Coal at Stratford mine, which is in an environmentally sensitive area in the Avon Valley, NSW, Australia. Normal blasting at Stratford is done in a æstand upÆ or æbox cutÆ mode to suit the truck and shovel operations. Recently an opportunity of doing a throw blast became available when part of a ramp had to be blasted to accommodate changes to the pit design while not damaging the remainder of the ramp. The objective was to maximise throw into the void in order to minimise excavation costs by reducing the amount of overburden to be moved by the excavation fleet. It was necessary that the best result be achieved while staying within the vibration and airblast limits at a neighbouring property and nearby township. Both objectives were achieved through the application of OricaÆs knowledge of blast design, modelling and i-konTM electronic detonators. The i-kon system was used because of its known benefits in cast blasting and environmental control. The i-kon system provides the blaster with much greater accuracy, control and the flexibility to tailor blast designs. It has been found previously to enhance blast throw and provide cleaner high walls (Brent, 2002). The blast was a success, producing a muckpile with a high degree of looseness and consistent fragmentation, with an average throw to final spoil position of 37.5 per cent. This was achieved without any environmental exceedance. In addition, high speed filming showed that the coal edge had remained largely in place, indicating minimal coal loss. The results exceeded the expectations of HWE Stratford and the overall cost savings to HWE Stratford from this blast were recognised to be substantial. Further throw blasting opportunities at Stratford have been followed using the i-kon system to maximise benefits.

Jan 1, 2003

By S Long, A J Koen, D MacKay

The Mt Wright Underground Mine is located near the town of Ravenswood in North Queensland and is operated by Carpentaria Gold – a wholly owned subsidiary of Resolute Mining Limited. Following the evolution of the mine plan through a number of stages, the ‘sublevel shrinkage (SLS) with continuous fill’ mining method was implemented in 2010 to extract the Mt Wright orebody. The production front in this mining method is similar to a sublevel cave (SLC) operation; however, backfill is placed into the top of the production zone as opposed to requiring the overlying strata to cave.Continuous fill to replace the void created by extracting the ore was required to manage the potential risks associated with the proximity of infrastructure to the footwall, associated long-term stability and air blast potential due to the limited ‘cavability’ of the material within the cave zone. The available fill material was sourced from a disused waste dump from a previous open pit operation, which introduced further technical and economic risks associated with dilution from ‘no grade’ broken material. Procedures and processes to manage these risks have been incorporated into the operation of the mine.Despite encountering a number of challenges, the SLS method has been in use for approximately three years at Mt Wright and has proven to be viable economically, technically and operationally. This paper will discuss the challenges encountered and what was done to overcome them, the operational and financial performance to date, along with the outcomes of some successful continuous improvement projects that have improved the efficiency of the operation.CITATION:Mackay, D, Long, S and Koen, A J, 2014. Sublevel shrinkage – the Mt Wright story, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 205–216 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By Johnson RD

The variation in coal properties and the coal seam reduced level can be analysed using partial trend-surface analysis techniques. For the area studied seam reduced level and seam thickness data from the Bulli Coal yield trend-surfaces with a high coefficient of determination, since they have relatively small systematic local and random components in their overall variation. Sulphur content appears to have no significant re.gi_onal trend, and phosphorus content has a very weak regional trend. Other analytical variables have regional trends which are of intermediate strength. The strike-directions of.the statistically significant first degree! trend-surface are similar, sug-gesting.: that the variation of the several coal properties was controlled by a set of- related causes. The relations apparent from the dip and strike of the first degree trend-surfaces are similar to- those which are apparent from the trend- surface residuals and'from the results' of canonical trend-surface analysis.'.. It is probable that differential subsidence controlled the areal

Jan 1, 1975

The Beaconsfield Gold Mine within the township of Beaconsfield in northern Tasmania has been established in recent years to exploit a known resource in the Tasmania Reef which was mined to a depth of 450 m below surface between 1877 and 1914 yielding 850 000 ounces of gold. Activity at Beaconsfield over the past 30 years has involved drilling to assess the resource and rehabilitation of the top 100 m of the Hart Shaft that had collapsed since the original closure. More recently the mine has been dewatered to the 375 m Level and work is well advanced establishing infrastructure aimed at recommencing production during 1998 - 99. This paper reviews geotechnical studies undertaken to-date and provides a brief overview of some practical methods of analysing ground conditions. It pursues simple observation and analysis as a tool for assessing mine design and ground support options without recourse to extensive monitoring and measurement and avoids the use of elaborate models before the basics are understood.

Jan 1, 1997

By Oliver R

The Hamersley Iron ore resources are geologically complex with fluctuations in mineral chemistry. From this resource Hamersley Iron must produce consistently high quality direct shipping products and have the ability to evaluate the effects of changes in demand. In order to achieve these objectives an incremental long term planning technique has been developed. This method reduces the total geological resource statement into a simple, logical sequence of events. A logical sequence of mining increments is defined within individual areas based on a final pit and access system. Increment characteristics are derived manually and from a computer based orebody model. The end product of the technique, an optimum mining schedule, is readily developed from the incremental information. Among its many benefits, this simple technique rapidly provides management with information for policy formulation.

Jan 1, 1979

Strip mining offers the advantages of high productivity from both human and capital resources as well as high rates of production. Experience suggests that it will be advantageous to extend strip mining to the maximum pos- sible depth in order to minimize costs and maximize the recovery of the in situ coal reserves. Highwall and spoilheap stability pose significant problems. Deep working in strip mines is likely to produce a change from methods which are based upon the elevation of material followed by dumping, to methods involving elevation and horizontal transport. There is considerable scope for optimizing the types of machines and minimizing the amount of double handling.

Jan 1, 1975

Gold mineralisation at the Macraes Gold Project is hosted in the Hyde-Macraes shear zone and can be traced for ~30km along strike, although economic resources are confined to a 7 km section in the vicinity of the Macraes township. The shear zone, which typically dips at a low angle (~20 o ) to the NE, is bounded by an upper hanging wall shear and a lower footwall fault. Mineralisation occurs along the hangingwall of the shear zone as well as in low angle concordant shears and stockworks. Ore types include graphitic cataclasites with variable amounts of quartz veining, ælode schistsÆ and quartz-vein stockworks. Rehabilitation at the mine has focused on creating an environmentally benign site dominated by pasture to allow continuation of the traditional pre-mine farming economy. Changing regional economics, continued urbanisation and a reduction in traditional employment opportunities has seen a rethink in the long-term rehabilitation outcomes. The community has recognised that the rehabilitated site will provide the basis of a viable tourism venture and the creation of a Heritage and Art Park (working title æGolden Point ParkÆ) is the culmination of that process.

Jan 1, 2002

By Godresse M, Turczynski G. P J, Driver I. J, Low G, Ozawa N

Geological evaluations of coal deposits have been traditionally undertaken in a somewhat manual manner. Information is collected downhole by chip sampling, coring and using downhole geophysical logging. This information is then interpreted by an experienced geologist to define the coal and noncoal lithological units. Coal units were subsequently correlated to provide data for structural modelling. In recent years a number of advancements in interpretation techniques have been made based on Artificial Intelligence. This paper describes an integrated geological interpretation system based on maximised use of Al techniques. The first part describes the lithological interpretation which uses a number of boreholes with both logged lithology and downhole geophysical logs. This information provides a learning set of data to the neural network. The second part concentrates on the correlation of both coal and noncoal units from borehole to borehole. Problems in this area, in a manual sense, are interpretation of correlation across weathering zones and other geological anomolies. The technique is based on pattern recognition and dynamic programming techniques where a correlation matrix is developed relating all holes with their maximum correlations.

Jan 1, 1995

A simulation program has been developed tc predict the airflow distribution and thermal environment in multi-level narrow lode Cornish =n mines. Because of the approximate equality between fan power and natural ventilation _rergy a true thermodynamic mesh balance using mass flow rather than volume flow rate was required. Compressibility is allowed for by calculating mesh corrections on a mass flow of dry air basis. In this context, and within the confines of any steady state model, both the steady flow energy and pressure equations are satisfied with equal validity. The mesh balance includes natural ventilation energy, frictional losses, moisture lift work, water droplet energy and fan energy.

Jan 1, 1988

By Muchi I

To clarify the characteristics of non-uniform flow of gas through layered burdens of ore and coke, flow equations of continuity and motion were solved numerically taking account of the geometrical effect of a bed. The results are compared with that predicted by an approximate solution. A mathematical-kinetic model for determining the distributions of process variables over the region from the top to the melting level of blast furnace with the horizontal or the inclined layers of burdens is developed in consideration of the uneven gas flow. By the use of this model, the longitudinal and the radial distributions of process variables in an existing blast furnace in Japan were calculated with the aid of a digital computer. Computed results show that the process variables and the melting level change remarkably over the cross-section of the furnace and that the patterns of these distributions are similar to the results observed by other investigators.

Jan 1, 1975

By Harmse C

Gold mining in Vatukoula had been a low tonnage/high grade operation for much of its 55-year life. During 1991 it became clear that a change in direction was needed if the mine was going to continue to prosper. The challenges of ore reserves of only three years, the prevailing gold price and high infrastructure and fixed costs combined to force changes in mining strategy.A more productive mining method was required to lower the unit mining cost, lower the pay limit and make more effective use of the resource.The flat dipping mineralised faults or flatmakes had been mined by updip, handheld room and pillar methods with a more recent trackless development adaptation. Furthermore, up to 40 per cent of the resource was left in pillars and broken rock.

Jan 1, 1993

By Rogers R, Kinnane T

In a typical open cast mining operation, investigation of how existing truck performance compares with the highest achievable truck performance is largely neglected. This paper addresses this issue by proposing a computerised system that will provide a systematic method for comparing existing truck operational performance to the highest performance considered achievable. Through analyses of existing versus achievable performances, various inefficiencies associated with truck operations can be identified. These inefficiencies could occur due to machine configurations, haul route design and conditions or operator skill level. Remedial action should then be taken in a timely fashion to better manage these factors and to ensure the fleet is always operating at its peak efficiency.

Jan 1, 1994