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By S Talu, E Savage, P Sturm, A van As

It is estimated that substandard ground support installations and elements cost the Rio Tinto Copper Group millions of dollars between 2000 and 2014. These issues have also created significant safety and financial risks in Rio Tinto mines. As a result, Rio Tinto Copper has developed CaveCAD, an integrated system to collect, store and analyse all ground support-related data. The CaveCAD system stores geotechnical data and has the ability to automatically import data, collect data through tablet applications, report processed/analysed data and present this data through 3D visualisation software.The CaveCAD Ground Support module closes the design–implementation–verification loop by providing a method of verifying the compliance of all installed ground support, recording manufacturer specifications, recording quality control test compliance and rectifying any non-conformant areas. The module uses innovative technology to create value through cost saving, safety improvements and data collection efficiency. Cost savings will be achieved by a decreased need for excavation rehabilitation, less ‘waste’ due to faulty installation and quality assurance checks reducing the likelihood of substandard support units being used. Data collection will be improved through the use of a mobile tablet application that can be used underground in ‘off-line’ environments.CITATION:Savage, E, Talu, S, Sturm, P and Van As, A, 2016. Development and implementation of the CaveCAD ground support module for cost and safety improvements in block cave mines, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 769–772 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By N Herault

PT Freeport Indonesia recently completed preproduction development and construction of the Big Gossan underground copper and gold mine, located in the Ertsberg mining district of Papua, Indonesia. Production has commenced with an expected ramp-up to full production of 7000 tonnes per day in 2012. The Big Gossan utilises an open stoping mine method with paste backfill.In order to deliver ore to the mill, which sits in a valley above the ore deposit, an underground production shaft and hoisting facility was designed and constructed as the key component of ore haulage. The design and construction of the Big Gossan shaft posed many challenges to the project team. Available shaft design and construction expertise were limited as this was the first shaft of its kind in Indonesia and the project was undertaken during a time of high industry demand for new shaft systems. Construction resources were also limited due to the remote location and competition with existing, producing mines for these resources and skills. The project also taxed the ability of Freeport to provide services and resources to this as well as their other projects.Completion of the Big Gossan shaft was a milestone in PT Freeport Indonesia’s plan to fully transition ore production to the underground environment in this decade.This paper deals with the various challenges faced by PT Freeport Indonesia and shaft contractor, PT Redpath Indonesia, during the construction of the Big Gossan shaft and offers suggestions to improve future shaft projects of a similar nature.

Mar 21, 2011

By H Allday

The mining industry’s attention has shifted over the last decade with the recovery from the downturn resulting in greater development of innovation and new work methods in a bid to remain competitive and deliver higher productivity. The emphasis on cost reduction to improve profit margins has primarily been the focus of the “work smarter” campaigns embraced within the industry. But is this strategy holistically the best-for-business, or does it place a ceiling on revenue opportunities and inhibit mining companies from truly maximising value? Businesses need to maintain a balance between active cost management and revenue generation often resulting in cost reduction strategies at site level. These strategies have merit, assessing areas of cost wastage across operations and creating space for opportunity. However, this potentially can create distractions from the goal of enabling growth and lead to the sacrifice of quality and delivery. Focusing too heavily on cost reductions without addressing revenue generation is an unprofitable lens to look through, and the relationships between cost, revenue, quality and profit margin can often be overlooked resulting in missed opportunity to maximise value. How these relationships are effectively employed by mining companies to reap the rewards from an overarching corporate perspective down to site level remains a fluid concept depending on the nature, operating market and strategy of the business. A common directive from businesses to their operations is to strive for greater profitability and productivity. The quantification of these requirements, and the nature of the cascading message delivered, impacts the methods employed by the operational team to meet the expectations of the business. Cascaded strategies, if not delivered with appropriate participation and buy-in can often be perceived to be knee-jerk and create frustration for operations who are squeezed to deliver on expectations by slashing site costs. This squeezing is not only felt by the mining operation but at the individual level and can result in increased team stresses. In some cases, this may also steer behaviours towards activities that result in corner cutting and an elevation of operational risk, potentially increasing associated incidents and injury. Driving down costs by any means can create an unhealthy tunnel vision where value is no-longer assessed for best-forbusiness results. By flipping the viewpoint to a value-based approach revenue opportunity may be realised and potentially exceeded, however this opportunity may be missed if value is over shadowed by a cost heavy focus. By analysing a selection of real operational cases (ranging from mining contractors through to in-house mining giants), it becomes apparent that practical revenue maximisation strategies are not only key to an increase in value and cash flow but to a stronger understanding of business drivers for sites and operators alike. In the cases evaluated additional revenue opportunities are foregone in favour of cost reduction strategies resulting in negative impacts on the associated operations and wider businesses. Alignment towards value generation is king. If strategies are not implemented focusing towards value and revenue maximisation, the opportunity loss experienced by mining operations could continue be great and the question should be posed; when the next up-turn hits will operations be ready to reap the rewards or still have a glass ceiling above their heads?

Mar 15, 2021

For several years, the Geology Department of the University of Canterbury has hosted a series of postgraduate projects in the field of coal studies, supported principally by the Ministry of Energy and to a lesser extent by private companies. These projects have involved mainly West Coast Coalfields, and my own studies have focussed on inorganic geochemical aspects of West Coast coals. Because of the large number of potentially important analyte elements in coal, and the wide diversity of coals occurring in the West Coast region, this project has required a substantial amount of work to be spent on sample collection, sample preparation, development of analytical methods, and actual analysis. Considerable problems must be faced at the sampling stage: Can sufficient information be obtained from whole-seam composites, or should seams be sampled in plies. Ply analysis is preferable, but results of proximate analyses are usually available for composites only. Where multi-seam drillhole samples become available (eg Greymouth Coalfield, where some holes yielded more than six sampled seams), the ply option involves a dramatic increase in the number of samples. I have attempted to strike a workable compromise between geographical coverage of coalfields, and detailed sampling of individual seams at each locality. In many cases, sample material has been used jointly with Jane Newman who has carried out petrographic studies.

Jan 1, 1985

By M Allen

Energetics has been in the business of climate change for more than twenty years. This experience has only served to cement the understanding that decisions taken during design define the environmental and economic performance of any project. The 80-20 rule definitely applies, with 80% of a project’s performance being set through the first 20% of design decisions. This in depth knowledge is used for determining energy price forecasts, future carbon markets and carbon costs, current and future energy technologies, as well as giving a thorough understanding of the processes and technologies in place in the mining industry to work out what the most carbon and energy sensitive decisions during design are. Project selection and design is a gated process where decisions are taken in line with the information available at that point in the evolution of the project. Design decisions are, by their nature, dominated by uncertainty. In order to ensure that robust decisions are taken, it is necessary to ensure that the correct information is brought to bear at the correct decision point. This then defines and supplies the necessary carbon and energy information for design decisions to be correctly made. One of the most significant risks facing design engineers and decision makers in the mining industry is the future cost of energy. Part of this risk is associated with a future cost of carbon, however, a significant part of this risk is the cost, and variability in this cost, of the energy itself. This paper investigates the information required to support good decision taking during the design process.Project Managers and MetPlant Operators accept poor quality evaluations because they are generally unaware of what they should expect.The 2010 draft AusIMM ‘Guidelines for Techno-Economic Evaluations’ were collated by a subcommittee of practitioners and are regarded as best practice.They apply directly to projects and metallurgical plant evaluations, including those with a heavy technical basis. They can be applied to technical problem solving where there are no monetary computations.Project Managers and MetPlant Operators should demand that economic models and evaluations follow the six principles. They should become working tools which are easy to understand, fit for purpose, consistent, rigorous, record sources of input data, have key graphs and are rapid to audit.

Aug 8, 2011

By F Ramos

Conventional techniques for resource estimation generally involve the laborious analysis of variograms and the specification of parameters for covariance functions. In large deposits, construction of resource models and their update require significant amount of manual work, expert knowledge and time. In this paper we take a machine learning view to the problem of resource estimation. This is a non-parametric Bayesian method, leading to automatic parameter estimation (learning). Through Bayesian learning, the parameters of the model can be obtained by optimising a quantity known as the marginal likelihood. The main advantage of this approach over conventional maximum likelihood estimators is that the objective function incorporates the OccamÆs razor principle. This allows the comparison of different statistical models û for example, models designed with different covariance functions û and naturally penalises complexity, thus avoiding overfitting. Our technique presents significant flexibility for the definition of mean and covariance functions and permits the usage of more sophisticated models.The second contribution of this work is the formulation of a data fusion mechanism that continuously updates the resource model. As mining progresses, more information becomes available. For example, the hardness of the rocks can be measured while drilling blast holes, grades of ore and contaminants are obtained from cone logging. This information is in general available at a finer spatial resolution but can be more uncertain. The data fusion mechanism can seamlessly estimate the uncertainties of the different types of information and fuse them as new measurements are acquired. This procedure can significantly improve the quality of the resource model, defining new grounds for stochastic mine planning. We demonstrate the effectiveness of our approach in estimating iron ore deposits by integrating information about different grades.

Sep 26, 2011

By G Jones

The Singapore Land Transport Authority (LTA) has been procuring the expansion of their underground mass rapid transit rail network at a prodigious rate since the first line opened in 1987. Four lines (149 km) are currently operating and several more lines are at various stages of planning/construction; one of these is the Downtown line stage 2 (DTL 2).DTL 2 contract C917 was awarded in September 2009 for S$320 M. On 18 June 2013 the original contractor became insolvent, leaving the works incomplete. Following a fast-tracked tender process, McConnell Dowell was awarded the S$254 M contract on 29 August 2013 to complete the works. This contract includes two underground stations constructed by cut-and-cover methods and twin bored tunnels between the stations. Each tunnel is 1400 m long, excavated by earth pressure balanced (EPB) tunnel boring machines (TBM) at an average depth of 20 m and segment lined to 5.8 m inner diameter. The tunnel alignment is located under a busy five-lane road lined with prime residential real estate and congested with utilities.To compound the difficulty the tunnels are located within the notorious Bukit Timah Granite formation. This has a very wide range of strength, from below 1 MPa to over 300 MPa. This strength range is a consequence of six weathering grades, from soil to fresh rock, with the fresh granite causing severe abrasion problems. The various grades can occur within a very short distance of each other. Consequently, the problem of supporting a mixed face exists, particularly in the intermediate weathering grades where intact rock is encountered in the invert and corestones within a loose soil matrix in the crown, which can increase the instability by allowing the ground to flow into the TBM.The focus of this paper will be the excavation of the bored tunnels by EPB TBM used by McConnell Dowell to complete these challenging works.CITATION:Jones, G and Shepherd, J, 2014. Earth pressure balanced tunnelling in a dense urban environment, C917A, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 41–50 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By N Anderson

With traditional grade control processes, geological models are created by geologists at the completion of the data collection stage and wireframe construction is closed off at a set date to allow for time to complete the estimation process. Any issues identified at earlier stages or the addition of new data requires the estimation process to be started again. Alternative interpretations are explored only if time allows and often in a limited fashion. An alternative workflow has been developed at the Waihi Underground Gold Mine utilising Leapfrog Edge and Seequent Central. Geological and grade control models are created, dynamically linked, and saved as separate branches. A project geologist is able to work on the grade control model and a mine geologist on the geological model simultaneously. This allows for a non-linear modelling workflow with continual review and feedback. The introduction of new data can occur right up to the model due date, with data collection, validation, alternate interpretation, and review happening incrementally. Models are categorised and stored in Seequent Central according to project status. An approved version of the geological model and grade control estimate are uploaded at the time of release and transparently capture all data used at a point in time, as well as the review process. Dynamically updating models for grade control has reduced turnaround time while increasing accuracy and quality. Estimates of individual domains are vastly improved from being able to rapidly evaluate the effects of model parameter changes in real time and 3D. Development and stope design directly benefit from these streamlined processes, with higher quality, timely production occurring as a result.

Mar 22, 2022

By S Ravn

Under platform exhaust (UPE) systems are often designed into metro stations as a means of removing heat generated by trains as they come to a halt in the platform. These systems are designed to extract heat from the brakes and brake resistors directly at the source in order to capture as much heat as possible before it can enter the public areas of the station, or contribute to the temperature build-up in the tunnels. Due to space requirements for the associated duct and air handling units, the UPE plays a significant role in the geometric design of the platform and station as a whole.In recent years questions have arisen as to the effectiveness of UPE systems. However, very little data is available for designers to use when making important decisions on the station designs for new metro systems. This is important as significant savings could be achieved by omitting or re-designing these systems for new build stations; not only due to the capital costs of space provision for the duct itself but also due to the associated operation and maintenance cost of the UPE system.This paper will present recent measurements of the UPE system of the Copenhagen metro together with one-dimensional (1D) simulations, looking at typical dispersion of heat into the station plenum box and air exchange through draught relief shafts as the train enters the station in order to evaluate the effectiveness of the UPE system. The aim of this paper is to disseminate the results of measurements and analysis to increase awareness of the issue and to provide discussion relevant to designers in their evaluation of heat removal systems in new build station designs.

Mar 8, 2011

Throughout the industrial world, Ilmenite, Rutile, Monazite and Zircon mineral sands play a KEY role in numerous industrial processes. Australia's ilmenites, rutiles, and synthetic rutiles are of vast importance in the world of titaniferous ores, and Australia has been the world leader in the field, and continues to adapt to new demands with alacrity. These materials enter a world titanium dioxide market that will exceed three million tonnes in 1990 at an expected growth rate of 2.3%. Many experts place current use in excess of 2.5 million tonnes of contained Ti02. Here we have a slide that illustrates projected growth rates in consumption, in SCM's view.

Jan 1, 1986

By I M. Platten, Y Xie, R-M F. Bell, S C. Dominy, L E. Howard, R C. A Minnitt

For any resource evaluation program, the collection and processing of representative samples for assaying is critical. Sampling, sample preparation and assay protocols must be designed to suit the style of orebody in question. The a priori need is for the characterisation of mineralisation type(s) and domain definition. The proportion and size of gold particles has a direct impact on the effectiveness of sampling protocols employed. Mineralogical studies focusing on gold particle deportment, size and distribution are required. Key issues are the presence of gold particle clustering and proportion of coarse versus fine gold. High-resolution X-ray computed tomography (HRXCT) is a radiographic technique that produces high-resolution 3D computerised models of in situ objects based on density distribution. The ævirtualÆ specimens are made up of voxels, the 3D equivalent of pixels each assigned a grey value based on X-ray absorption. This paper presents the results of recent research on the imaging of in situ particles in coarse gold-bearing ore samples from the Nalunaq mine, southern Greenland. The samples used were previously well-characterised through mineralogical and metallurgical testing, and serve to test the HRXCT methodology. Gold particle size and distribution in the context of the sampling liberation diameter was investigated.CITATION:Dominy, S C, Platten, I M, Howard, L E, Xie, Y, Bell, R-M F and Minnitt, R C A, 2012. Determination of the sampling liberation diameter in a high-grade coarse gold ore by high-resolution x-ray computed tomography, in Proceedings Sampling 2012 , pp 161-170 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By D J. Logan, J Jackson

"As of 1 December 2014, the 2012 edition of the JORC Code requires Ore Reserves to be defined by studies at the pre-feasibility or feasibility level. This paper examines how the pathway for most mining developments is determined in the Pre-Feasibility Study and how a trade-off must be made between the need to make the best decision, the constraints of limited time and resources, and the level of the project’s accuracy and uncertainty in terms of value. Issues considered include framing the scope of the study, planning for robust decision-making and ensuring effective communication between the diverse disciplines within the team.An inherent conflict exists between the immediate value added to a mining business from an increase in ore reserves resulting from a ‘quick’ Pre-Feasibility Study and the long-term value of pursuing a development strategy based on proper investigation and evaluation of the options. Recognition and resolution of this conflict is necessary if a project is to progress into future development stages, both in a timely manner and with the optimal development alternative and strategy.The challenge for project developers and those conducting the Pre-Feasibility Study is to understand what the key deliverables are (ie an Ore Reserve statement, option selection, business evaluation, forward work plan or risks) and how to follow good practice to ensure that these deliver value.CITATION:Logan, D J and Jackson, J, 2016. The pre-feasibility study – big choices, little time, in Proceedings Project Evaluation 2016, pp 122–132 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

Although a small quantity of lc,;v viscosity index ' (L.V.I.) oils are presently manufactured in. Australia, lubricating oil refining methods are assuming gxeater significance since in 1964 Australia will be locally refining the bulk of its requirements and some companies may be exporting a surplus. New plants are ' planned to refine mainly high and medium viscosity index oils from imported crudes and the paper describes typical techniques used òto: produce. thes& oils. .

Jan 1, 1962

By G S. Beros, K M. Edwards

Over the past 20 years drum scrubbers have become a widely adopted technology within iron ore beneficiation plants. Generally, the drum scrubbers in use are considered high-capacity machines capable of accepting larger-sized feed material. Together with a water addition to a desired pulp density and a mild energy input, these large rotating machines effect an attritioning action that removes water soluble clays and other deleterious materials. Within the Western Australian iron ore industry, drum scrubbers have been successfully applied to Channel Iron, Marra Mamba, Bedded and Detrital orebodies. The introduction of drum scrubbers has enabled Western Australian producers to satisfy the substantial increase in demand for iron ore from Chinese steelmakers by making the lower-grade sections of the above orebodies economic. However, despite being a relatively simple unit process, the requirements for successful design and operation of these machines are not fully understood. This paper draws on the collective experience of both authors to provide some points to consider for incorporating drum scrubbers into iron ore beneficiation plant flow sheets.

Sep 18, 2023

By Y K. Leong

Occasionally additives are used in the wet processing of iron ore tailings and slurries, for examples, in the thickening of tailings with flocculant to recover process water, and in the smooth pumping of concentrated slurries. They can mitigate slurry behavioural issues that could significantly affect the plant operation and production. The nature of iron ore business requiring the plant to have a high throughput to be economical, large amounts of slurries are therefore processed every day. The quantity of additives needed will correspondingly be large and so are the associated costs. This could have a significant impact on the plant profitability. If additives are used they must be very costeffective. NaOH is among the lowest cost chemicals available, at ~US$400 per ton. In this paper we will look at use of composite additives involving phosphate compounds with NaOH added to reduce the cost, for the control of iron ore slurries rheology. The NaOH worked synergistically with the phosphate compounds. The effectiveness of these composite additives in viscosity reduction can be neutralised by another cheap additive such as lime or a Ca(II)-based salt turning the slurries back to being a paste. Tailings paste is an ideal material for safe storage in the dam. These composite additives can also be used to facilitate the recovery of iron ore at commercial grade from tailings (Leong, 2020a, 2021a).

Sep 18, 2023

By A K. B Chigwada

Mining organisations grapple with the same problems year after year, wasting incredible amounts of time and money. According to estimates from the International Labour Organization (ILO), over one million work-related deaths occur annually, and hundreds of millions of workers suffer from workplace accidents and occupational exposure to hazardous substances worldwide. Many accident reports cite human failure as a primary cause (Busse and Johnson, 1998). The workers at the Bhopal chemical plant pumped methyl isocyanate into a leaking tank (Morehouse and Subramaniam, 1986). On 3 December 1984, more than 40 tons of methyl isocyanate gas leaked from a pesticide plant in Bhopal, India, immediately killing at least 3800 people and causing significant morbidity and premature death for many thousands more. The company involved in what became the worst industrial accident in history immediately tried to dissociate itself from legal responsibility (Broughton, 2005). Australia is not spared from safety problems either (Lucas, 2022). The ILO Convention 176 (1995) as a response provides that national law should inter alia provide for the supervision of safety and health in mines; the inspection of mines by designated inspectors of the competent authority; the procedures for reporting and investigating of fatal and serious accidents; the compilation and publication of statistics on accidents, occupational diseases and dangerous occurrences; the competent authority to suspend or restrict mining activities on safety and health grounds until conditions giving rise to the suspension are addressed; and worker consultation on matters related to safety and health in mines. This has assisted in getting enough data to define the magnitude of the problem to the mining sector.

Apr 16, 2024

By D Luppnow, C Hore

In-pit tailings storage can provide many advantages when compared to typical above-ground tailings storage facilities (TSFs). As regulations become more restrictive and existing mines expand into new pits, the motivation and opportunities for in-pit tailings disposal is increasing.The Langer Heinrich uranium orebody follows a palaeo-river channel and is mined as an open pit operation. The mine pits intersect two main aquifer systems, one at the surface and one at the base of the orebody/pits. The tailings storage methodology is full in-pit disposal in multiple TSFs for the life-of-mine. Continuity of the initial hydrogeological conditions is incorporated in the design by the use of the pervious surround concept and the reinstatement of the lower aquifer (palaeochannel aquifer) at the base of the pit. Containment embankments are required to facilitate the staging of the TSFs development and are constructed using waste rock liberated during the mining of the pits. All of the TSFs are equipped with decant structures and an underdrainage system is included to improve water recovery, enhance consolidation and increase tailings density.This paper presents the design of a unique in-pit tailings storage solution for the Langer Heinrich mine in Namibia owned by Paladin Energy Ltd.CITATION:Hore, C and Luppnow, D, 2015. In-pit tailings disposal at Langer Heinrich – tailings storage facilities in a unique hydrogeological setting, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 373–380 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By A Castillo, K Wiese, L Panduro Robles

For decades, organisations worldwide have been working to overcome challenges associated with new technology adoption while keeping up with rapid growth, development, and globalisation. In minerals processing, the challenges in developing and implementing solutions that contribute to the mining value chain are unique from other markets, as mining operations expect that world-class suppliers provide them solutions to gain a competitive advantage in their operation, production, performance as a financial asset, and as a long-term partner as we move into the future of mining. A simple shift in mindset is proven key to successful technology implementation. Change leaders must no longer think of their expertise in the area of application as their only responsibility; they must make a mental shift and see themselves in dual roles that strive to integrate the perspectives and needs of both developers and users. Successful change leaders must: (1) collaborate, seeking user involvement to ensure fit between product and operational needs, (2) demonstrate commitment to receive new technology, and (3) communicate to achieve an eventual shift of ownership from supplier to users that is seamless. Additionally, this strategy contributes to the mining value chain, as it allows developers and implementers to evaluate how change contributes to the asset’s position both within the company and in the commodities market. This paper will explain the shift in perspective for new technology implementation in detail and provide recommendations that operations can emulate, using examples of real challenges and lessons learned during a commissioning of the CYCLONEtrac™ Particle Size Tracking (PST) system at Cerro Verde’s C2 Concentrator. This concentrator has led technological change for plant optimisation, witnessed improved Net Metal Production (NMP), among other benefits with PST, the only technology in the market capable of providing real-time, online, and direct particle size measurement at the individual hydrocyclone level

Aug 24, 2022

Historically the insurance industryÆs involvement in any project has been relatively late in the process. Often it was a case of the last item to be ticked off the checklist has been to ensure that the insurance is in place. However, in more recent times insurers have imposed more restrictions on the cover they are prepared to provide, which has in some cases necessitated a change in the contracting structure to accommodate the insurance policy(ies). In addition, changing contractual practices have changed the allocation of risk between the various parties involved. This calls for a more proactive approach to the design and implementation of an insurance program for both the construction and operational phases of any resource project. This paper explores how a risk managed approach to the design and implementation of an insurance program for a resource project can align itself with current management approaches to project development. From the authorsÆ experience, this approach is best adopted early on in the project (often in conjunction with the bankable feasibility study) and follows AZ/NZS4360 to objectively examine and compare a wide range of risk exposures of the project in a time-effective manner across the following areas: personnel; environment; general management; compliance û legislation, systems, protocols; asset management; change management; financial impacts to the organisation; products/services; service delivery; and technology. Having identified and then analysed the risk exposures according to common consequence and likelihood ratings the next step is to develop a risk map of all considered exposures. The true value of this approach lies in the development and implementation of a risk treatment plan for identified exposures where the exposure is unacceptable. The plans will lead to the optimal solution to the appropriate risk prevention, risk mitigation and risk transfer options available. This paper also examines other benefits to the project that may arise from adopting a risk managed approach in addition to the ability to design an insurance program which recognises the exposures and the ability of the organisation (and other project parties) to retain risk.

Jan 1, 2007

The Bellambi Coal Company Limited com menced longwall mining at South Bulli Colliery in 1965. At present it operates three long- wall units in two seams. Although results to date have been less successful than planned, it is apparent that this type of mining has tremendous potential in the particular conditions at South Bulli. Massive sandstone strata above the Bulli seam is the controlling influence on face conditions. The earliest equipment proved to be inadequate and the Company has progress- ively replaced and upgraded the roof supports and ancillary equipment so that the present units are capable of producing high and consistent outputs.

Jan 1, 1976