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South Crofty's ventilation network is large and complex. Of the total exhaust air quantity 40% enters the mine by leakage routes through old workings, this air carries high concentrations of radon gas and results in the mine becoming a classified work place under the Ionising Radiation Regulations 1985. Improvements in the control of the ventilating air and dilution by increased air quantity have reduced the average contamination to aelow-0.2 WL. The major part of the radon originates from ground water inflows and from concentrations of radium within the mine with direct emanation from rock surfaces being negligible. Of 600 kBgs-1 total radon leaving the mine 93% cannot be accounted for from known and accessible sources.

Jan 1, 1988

By Lockhart D. A, Gleeson P, Lang S. C

The Glenrock Group forms the uppermost part of the Early Devonian to Early Carboniferous Burdekin Basin sequence in the Townsville hinterland, north Queensland. As redefined, three formations make up the Glenrock Group. The Percy Creek Volcanics (base), the dominantly epiclastic Mount Douglas Formation, and the Horse Pocket Volcanics (top). The Ellenvale beds unconformably overlie the Mount Douglas Formation and Percy Creek Volcanics and have been excluded from the Glenrock Group as defined by Wyatt and Jell (1980). Three facies associations are recognised in the Mount Douglas Formation: Alluvial Plain facies, Alluvial Fan facies and Lacustrine facies.Deposition of the Glenrock Group, began with the eruption of massive basalt and basaltic andesite lavas, probably in a volcanic arc setting. With time, the volcanism evolved to become more dacitic to rhyolitic in composition. Waning of the volcanic activity appeared to coincide with uplift of source areas (probably to the west). Deposition on an alluvial plain during this waning volcanic cycle, gave way to alluvial fans at the margins of the uplifted terrain. As the uplift ceased and the system became more mature, the alluvial fans gave way to widespread lakes. Rhyolitic ignimbrite and airfall tuff, interbedded with the alluvial plain, alluvial fan and lacustrine facies, indicate that some volcanism continued, probably vented in the uplifted terrain to the west.

Jan 1, 1990

By E Taylor, F Lebbing

The $2.5 billion EastLink project is a 39 km tollway and includes twin three-lane, 1.5 km long, undrained driven tunnels with cross passages every 120 m. The hard rock tunnels are being built to avoid passing the motorway through the Mullum Mullum Valley and help preserve the unique flora and fauna in the area. The design of the permanent concrete lining and waterproofing system for the EastLink tunnels was both innovative and practical, to meet the demanding environmental and production constraints of AustraliaÆs largest road project. This paper describes several key aspects of the tunnel design and construction, including: design of fully tanked, permanent concrete tunnel linings for the main tunnels and cross passages to withstand 37 m head of water pressure in combination with potential rock loading in the future;optimisation of the tunnel shape to minimise the amount of reinforcement required and the design of special welded mesh which was developed within manufacturing constraints;100 year design life and durability considerations in every aspect and detail of the design including concrete mix design and stray current mitigation;development of a precast invert solution for the main tunnel permanent concrete lining to enable faster lining construction and to minimise risks to the tunnel membrane associated with fixing reinforcement and construction traffic;development of prefabricated reinforcement details for the junctions between the main tunnels and the cross passages to enable faster construction and minimise risks to the membrane associated with fixing reinforcement; andincorporating the tunnel drainage sump at the lowest cross passage in the alignment, resulting in deep excavation to satisfy the required storage volumes for drainage.

Jan 1, 2008

This paper presents results of the experiments carried out in Beth Energy No. 33 Mine for the purpose of alleviating problems associated with cutter roof. Cutter roof problems have delayed the advance of the entry development considerably and maintenance cost of these entries was very high due to the requirement of very extensive and heavy artificial supports. The study includes assessment of the problem, investigation of the geology and lithology of the mines, study of in-situ stresses and corrective measures to combat the problem. Two approaches were selected as the corrective measures: 1) implementing yield pillar concept in order to reduce the effects of in-situ horizontal stresses, 2) designing an effective roof reinforcement system and application procedure. Results of this study revealed that roof strata is weak and in-situ stresses are very high at the problem area which results in development of cutter roof. Implementation of yield pillar concept was found to be ineffective because cutter roof often developed at the entry face concurrent to the development. However, proper design and implementation of roof reinforcement system stabilized the roof and eliminated roof caving during both entry development and retreat of longwall face, despite existence of the cutter roof, at a much lower cost.

Jan 1, 1992

By Richardson G. W, Yap L. C

Friction rock stabilisers (FRS) are the most common steel-based ground reinforcement used in underground mines in Western Australia. As with any other steel-based product used in underground mines they are susceptible to corrosion, particularly under aggressive minewater and mineral conditions. Because of their thin-wall tubular construction and large surface area, the potential damage resulting from corrosion is considered to be more severe for this type of reinforcement than for other forms of reinforcement made of solid steel bars. Because of the obvious safety problems which may result from corrosion, both mine operators and regulators have raised concerns regarding the long-term effectiveness of FRS installed in underground mines in Western Australia. Although corrosion has been recognised as an important safety issue, the controls of corrosion in varied underground mining environments has not been well understood. To improve the understanding of the corrosion behaviour of FRS, the Department of Minerals and Energy has initiated a research project focused on the mechanisms and extent of corrosion attacks, and their influence on the effectiveness of the reinforcement. This paper describes the research project and presents the interim results achieved To-date.

Jan 1, 1995

By R R. Lovel

In this paper, life cycle assessment methodology has been used to assess the variations in water use associated with different metal production and processing routes and provide insights into the value derived from water usage in the minerals sector. Using water consumption data derived from the literature it has been shown that the æcradle-to-gateÆ water consumption (or embodied water) for production of the various metals considered in the study ranged from 2.9 m3/t for steel up to 252 087 m3/t for gold. The results largely reflect the grade of the initial ore used to produce each metal, and can be approximated by the following equation:W = 167.7 G - 0.9039 where: W = embodied water (m3/t refined metal) G = grade of ore used to produce metal (per cent metal) The study showed that indirect water consumption in the metal production life cycle, in particular that due to electricity generation, can make a significant contribution to the embodied water value, eg aluminium production. When expressed in terms of m3/t ore, the results for all metals considered indicated that the embodied water is roughly, on average, three times the water consumption of the mining and concentration stage. It was also shown that the economic value per m3 of water consumed for the minerals industry exceeds that for the agricultural and industrial sectors, supporting the view that allocating water resources to the minerals industry has a strong underlying economic basis. Water reforms currently taking place in Australia aim to address issues such as competition for water access, reduced security of supply and increase in cost. Consequently the minerals industry, along with others, can be expected to come under increasing pressure to reduce fresh or raw water use and to integrate water use across sectors. While water recycling is an obvious candidate to help reduce water consumption in the minerals industry, issues such as water quality, among others, will influence the extent to which this can be achieved. In addition, wastewater volumes can be minimised using techniques such as pinch analysis to establish and use the minimum water requirement for the process. The use of dry or near-dry processing technologies, for which the demand for water is small or zero, may be a more radical solution to the water consumption problem; however, it is possible that the introduction of dry processing would bring with it a new set of problems, including dust.

Jan 1, 2006

By Anderson J. M, Gillies A. D S, Jones N

There are a number of current theories in relation to methane migration and emission into workings following underground coal mining activity and some controversies do exist. Mining causes changes in the stress regimes in surrounding strata and results in fracturing. Permeability increases and methane flows into workings under a pressure gradient. The effects of stress on permeability depend on the physical properties of the coal and surrounding strata. Methane emission also depends on the original methane content and the proportion which will be liberated. There are several methods for determining in situ methane content and desorption characteristics of coal samples and several methane prediction methods but clearly more research is necessary to achieve an adequate predictive model.

Jan 1, 1992

By Singh JK, Singh R

With a view to producing increased target output every year, Indian coal mining industry is fast moving towards mechanisation but the present approach of mechanisation suffers from lack of standardisation, mainly due to nonavailability of the cutting data for various machine/rock combinations. The coal seams of the country are relatively hard in nature and the coaling machines are reported to be affecting production and productivity of the coal mine and the very trend of niechanisation. This paper presents the result of extensive study performed to visualise the cutting characteristics of coal seams of compressive strength ranging from 20 MPa to 65 NIPa. In a specially designed drag bit type coal plough rig, continuous recording of cutting forces was done with the help of a microprocessor based data logger and the specific energy of cuttability was evaluated at different depth of cut and speed of cutting. The geomechanical properties such as compressive strength, orientation and frequency of cleats etc. and different indices of coal seams were measured in the laboratory and field and relationship was developed for easy determination of specific energy.

Jan 1, 1992

This paper describes the application of the Total Productive Management (TPM) technique as a performance improvement initiative for a coal mining operation. It discusses the objectives of TPM, with the driver for improved production performance being the Overall Equipment Effectiveness (OEE) of the equipment or process, and with the development of "ownership" as the behavioral approach to equipment management and continuous improvement through cross-functional and area-based teams. It illustrates the concept of equipment management as defects management.The scope for application of TPM to the coal mining industry is immense. The harshness of the operating environment can be a major generator of equipment defects, and a current paradigm in the industry accepts these defects as an unavoidable outcome defining maintenance costs in this environment. However recent benchmarking studies have highlighted that maintenance costs per operating hour in some mining operations are more than double the vendor's estimate of "best practice". The paper refers to these studies which also compare maintenance costs of fixed and mobile plant and equipment to "best practice" outcomes in comparable process industries.

Jan 1, 1998

The process of hydraulic transport through pipelines, world-wide well known for the trans- port of fine-grain solids is also being used to a greater extent in mining for the handling of 1rimarily coarse-grain solid - water mixtures r the removal of, for instance Coal and waste mixtures after coal winning rising hydraulic monitors, lings for backfilling underground and :her tailings and flotation waste to A large-scale test unit was taken into service at the Bergbauforschung GmbH (Mining P',search Company) in Essen-Kray, GFR, to ¦urther improve this technology. The unit was :fanned and built by Krupp Industrie- and +hibau of Duisburg in cooperation with i r

Jan 1, 1980

Syferfontein Colliery, part of the Sasol group of companies which specialises in the field of petro-chemical production, was established in 1990. The mine is situated about 150 km east of Johannesburg, South Africa. Two coal seams are mined, utilising two 75 m3 draglines, shovels and a fleet of 177 ton rear dump trucks. The mine will reach its full production capacity of seven million tonnes per annum in 1992. During the planning period, prior to the establishment of the mine, management were confronted with the unstable socio-political environment in South Africa which could jeopardise the eventual success of the mine. They consequently conducted a strategic planning exercise to determine guidelines for mine planning to improve the chances of success in this unstable third world environment.The strategic guidelines formed the basis for specific actions taken during the planning and commissioning of the mine. Specific actions were taken in the field of operating cost, labour relations, working environment, logistics and the general environment. First results indicate that these actions have played a major role in the success of the mine to-date. This process can be utilised by others facing similar or even totally different uncertainties.

Jan 1, 1992

The paper examines the possibility of applying the monolithic packing technique developed in the UK to the division of wide development drivages in Australia, so enabling double entries for longwall retreat panels to be created from shortwall units. The monolithic pack of the UK therefore becomes a monolithic partition in this proposed Australian application. A method developed for the analysis of the load development in packs installed behind longwall advancing faces is adapted and used to predict the support performance of the monolithic partition. Conclusions are made regarding partition construction and possible rates of advance.

Jan 1, 1986

The Telfer Gold Mine, owned and operated by Newcrest Mining and located in Western Australia, is currently being expanded. A new underground sublevel cave development is proposed along with an appreciable expansion of the open pit. The Telfer area is generally subject to low rainfall, however, during the wet season cyclonic events can result in sizable rain events, which have the potential to cause substantial inflow. In addition to this, during the first five years (nominal) of the mineÆs life, there is the potential for drainage paths between the pit and the underground mine via decommissioned underground workings which lie directly under the pit. After this initial five year period the pit floor will be mined out below the old workings and will therefore no longer connect to the underground, however cave breakthrough to the surface may start to occur thus providing another water path into the underground mine. To arrive at an optimum, safe solution for dewatering the mine that successfully addressed the above items, a rigorous risk analysis was included as an integral part of the design process. This involved the determination of the probability of events occurring and the consequences of these occurrences. This was compared against the cost of mitigation for the various events. This paper outlines the process by which a safe concept addressing all the issues relating to dewatering the proposed mine has been arrived at. This process included: Establishing the pit catchment areas. These were based on historical run-off data and took into account practical mitigation works. Establishing an Average Recurrence Interval (ARI) based on reference material and historical rainfall data. Utilising a standard approach based on Australian Rainfall and Run-off (ARR) to calculate pumping and storage requirements for the various catchments. Analysing the 20 years of recorded rainfall in the Telfer area to establish the duration, magnitude and sequence of events. This analysis assisted in determining the surface run-off coefficient. Establishing potential water storage areas and determining the risks associated with using particular storage options. Establishing the percolation rate through the cave zone. A degree of uncertainty regarding the percolation rate in the cave zone required that the consequences of using various percolation rates were considered to aid in establishing the rate which was adopted. Establishing preliminary concepts and determining the most economically viable concept. Conducting a risk assessment based on the principles outlined by Australian Rainfall and Run-off (ARR) to confirm that the appropriate Average Recurrence Interval (ARI) had been selected. A risk assessment was also conducted in accordance with client requirements. Establishing the optimum pump station sizes and storage capacities. Establishing the appropriate numbers of duty and standby equipment. By using the foregoing process, which included a number of stages of risk analyses, an optimum dewatering system concept was produced.

Jan 1, 2003

By J C. Diaz, C R. Scherpenisse

Blasting represents one of the most relevant unit operations in the process of mineral extraction. The final objective of this operation is that of obtaining an adequate final fragment size distribution such that the combined costs of drilling, blasting, excavation and transport, and crushing/grinding, are minimised, while at the same time producing the minimum possible level of damage to the surrounding rock mass. The strong influence that drilling and blasting has over the subsequent processes involved in the operational cycle makes it imminently desirable to have access to experience and technology which make possible the evaluation and optimisation of this unit operation. The correct use of vibration monitoring techniques offers a number of benefits in terms of their ability to examine any blasting process in detail. In effect, the measurement of particle velocity levels that result from the detonation of each explosive charge offers a means by which it is possible to measure relative efficiency of each charge, interactions (productive and counterproductive) between adjacent charges, and a definitive indication of general performance of any given blast design and its implementation. In this way the monitoring of blast vibrations in rock due to the blast event, can be used as a diagnostic tool, given that the correct interpretation of the vibration traces allows the determination of the level of interaction between the design and operational variables of the blast event. This makes it possible to evaluate, for example, the presence of out of sequence detonations, statistical scatter in the detonation times of pyrotechnic delay detonators, deficient detonation of charges, instantaneous detonation of charges and sympathetic detonation of charges, as well as the general of vibration levels in terms of peak particle velocity, acceleration, and displacement. Another important use of such data is in the construction of a database relating vibration levels to charge weight, hole diameter, and distance, for any given rock type, enables the calibration of predictive vibration models which in turn make it possible to predict the damaging effects of blasting. Knowledge of both the vibration levels induced, combined with quantitative measures of the geomechanical competence of a rock mass make it possible to estimate the probability of producing blast induced damage. The high levels of vibration generated by some blast events may damage the rock mass, producing new fractures or extending and dilating existing fractures. The vibration in this context may be considered as a dynamic stress provoking strain in the rock mass. This paper describes the application of the vibration monitoring technique, particularly in the underground mining environment, and its importance in diagnosis, modelling, control, and optimisation of the development blasting process. The potential of the technique is assessed in the context of achieving substantial techno-economic improvements development blasting results, increasing output whilst minimising the operational costs of the mining process.

Jan 1, 1999

Sasol Roche Blasting Services (SRBS) has undertaken a process of trialing and evaluating the use of the SMI electronic initiating system with the specific purpose of being able to fully quantify the benefits of the system over a pyrotechnic system. After an initial trial of three shots in mid-2001, it was decided that to fully quantify the system, a complete strip would need to be fired using the system so that any losses due to ramps or end walls would be the same for both scenarios. The results have shown a significant improvement over the use of pyrotechnic initiators in several key areas including percentage cast. Through the use of survey results, the increase in cast and subsequent net improvement in blasting has been quantified. These trials have set out to compare each system in comparable situations to determine the real benefits, if any, of the electronic system over the pyrotechnic one. As the percentage cast is relatively easy to quantify using modern survey techniques, it was decided that this would be the principle method of comparison. However, while the assessment only included survey results, any improvement in fragmentation size and consistency would have flow on effects on reduced running and maintenance costs.

Jan 1, 2003

By Cuff C, Taylor RG, Georgees C

Mineralisation adjacent to Herberton occurs within three main subcentres. The Her- berton Hill subcentre is characterised by the association of Sn,W the Herberton Dividing Range South subcentre by Sn, and the Herberton Dividing Range North by Cu, As. The relation- ships between the subcentres are discussed in terms of metal distribution, production, deposit types, wall rock alteration and re- lationships with granitoid intrusives. The temporal and three dimensional spatial re- lationships between the centres are uncertain.

Jan 1, 1978

By Slechta JJ

The performance of a hydrocyclone treating fine coal has been examined over a wide range of feed and operating conditions.The results were expressed in terms of partition curves from which the water split to the oversize flowstream,the corrected separation size and reduced partition curves were determined-.The following conclusions were obtained. (a) The water split to the oversize flowstream was found to be dependent upon the vortex finder and spigot diameters of the cyclone and the flowrate and solids content of the feed slurry. (b) The corrected separation size was dependent on the solids content of the feed,and the vortex finder and spigot diameters.The hydraulic pressure (or flowrate) of the feed slurry did not have a significant effect.This phenomenon could be explained in terms of crowding of the particles at the Spigot.

Jan 1, 1984

By Abraham B. K, Jensen B, Gillies A. D S

The aim of the research was to investigate the feasibility of using an impedance cell and ratio-transformer bridge to measure solids content in coal slurry pipelines. It appeared that this technique could be developed to measure variations in conductance which correlate with solids content. Successful implementation of the measurement technique would have a variety of applications in existing coal wash plants and the potential for automatic process control. A small pilot plant was designed for a feasibility study. This was a closed loop system in which the coal was uniformly dispersed in a tank with a variable speed agitator and then circulated through an external pipe returning to the top of the tank. The impedance cell was located near the end of the external pipe. Slurry concentrations were varied from clean tap water to 50 per cent solids by weight with the addition of weighed quantities of dry coal dust. Ratio-transformer bridge measurements showed that variations in individual observations were equivalent to measurement errors of about two per cent. These probably reflect variations in concentration of the mixture in the pipe. Data for increments in concentration of one per cent indicate that this is about the limit of resolution of the current system. The paper discusses the principles of operation of the impedance cell and measurement system. Results from the pilot study and proposed improvements in the impedance cell design are examined.

Jan 1, 1995

By J Kok

"In some underground mines it has been observed that the primary focus during feasibility studies is to determine the best way to mine the defined orebody. Some studies have been conducted without sufficient consideration of the ventilation and cooling requirements or the risk from exposure to associated airborne pollutants caused by the mining operations.Following the hierarchy of control to manage risk, numerous problems of the ventilation systems in some underground mines could have been avoided if sufficient consideration was given to the ventilation requirements to manage heat, airborne pollutants and leakage during the feasibility study phase. If the constraints and hazards were well defined and understood at the time of the study, efforts could have been made to eliminate or substitute the hazards to decrease the risk. Some of these problems include but are not limited to: primary fan locations heat loads diesel exhaust ventilation design based on the production requirement fire/emergency response strategies.This paper highlights areas in the ventilation discipline that are sometimes overlooked during feasibility studies. It will also highlight the importance of the Ventilation Specialist during these studies. Experience and knowledge of best ventilation practices must be applied in feasibility studies.As a result of adequate consideration to all ventilation aspects in the feasibility study phase, risks will become lower in terms of health, safety, production loss and equipment downtime caused by heat.CITATION:Kok, J, 2014. Feasibility studies – what should be considered in terms of ventilation, in Proceedings 12th AusIMM Underground Operators’ Conference 2014, pp 197–204 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 24, 2014

Largely inherited from the past and from strictly internal laboratory use, the certification of reference material using round-robin assaying is often insufficient for the use made today for external assay laboratory control by client parties. Certification often needs to be revisited on the basis of existing round-robin data, especially to derive reproducibility parameters to the end of establishing probabilistic performance gates for operational error detection on a batch per batch basis (ie batch-ærejectionÆ). The most common difficulty arises when only a few certification samples have been analysed in one single batch by each laboratory, so that the round-robin data do not contain the full variability that needs to be quantified. Existing certification data sets from properly submitted round-robin samples were studied using analysis of variance to derive a remedial method, leading to the proposal of default correction factors to restore full variability estimates when no other avenue is available.

Jan 1, 2008