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By E Werner, J J. Donovan, A J. Morris

Coal mining in the Pittsburgh coal seam, in the eastern United States, began in the late-1700s. Since that time numerous mining technologies have been used throughout the basin. Environmental concerns, particularly mine discharge quality, have only been considered since the early-1970s. During the last 20 years, many of the larger underground mines have closed and are now either flooding or already flooded. In order to understand the consequences and potential future effects of this flooding, mine mapping of the basin has been compiled utilising a geographic information system (GIS) with an emphasis on locating barrier pillars between mines. Mine flooding has been monitored at numerous sites utilising pressure transducers and data loggers. These data have been combined with historical data from mining companies and structure contour maps to yield chronological flooding maps of the basin from 1980 to present. Utilising these maps and the indicated flooding rates, future discharge locations have been identified along with estimates of when these discharges are likely to occur. Related work has identified barrier pillar hydraulic conductivities and vertical infiltration rates as a function of overburden thickness. All of this information has been integrated into a groundwater flow model that simulates mine flooding. This model is useful in defining mine to mine interactions as the various mines fill with water, and the testing of various flooding scenarios. The model will be used in evaluating mine discharge rates and evaluating the options for regional mine drainage treatment.

Jan 1, 2003

The world is getting flatter through internet, mobile phone technology, relatively low cost travel, massive outsourcing of manufacturing to China and the transfer of company backroom operations to India. In the iron and steel industry, however, things will remain relatively the same with slow gradual improvements in technology; only the geographic location of plants may change over time. Or will it? The blast furnace smelting process has remained largely unchanged since 1828 when James Neilson came up with the idea of preheated air being delivered to the tuyeres. Likewise, oxygen steelmaking that takes molten iron from such blast furnaces has remained conceptually unchanged since Sir Henry Bessemer invented an air-based system in 1856. These two processes are the core of integrated steel mills that we know today. Typically such mills consist of coke ovens, sinter plant, blast furnace, oxygen steelmaking, continuous caster, rolling mills and metal coating lines. In the intervening 150 years the only real disruptive technology to the integrated steel mill has been the minimill. Based on the use of the electric arc furnace (EAF), in conjunction with a continuous caster and rolling mill, the term minimill is used because steel products are produced at down to one-tenth the scale required for economic operation of an integrated mill, with the EAF producing molten steel using largely scrap steel as its feed, as against transforming coal to coke (coke ovens), iron ore, coke and limestone into molten iron (blast furnace) and molten iron to steel (oxygen steelmaking). There are, however, a number of technologies in development that may cause a paradigm shift in the way steel products are produced and perhaps push the evolution of the minimill as a disruptive technology. Two examples are direct iron smelting, where iron is produced in a matter of seconds by injection of ironmaking feed materials into a molten bath, and thin strip casting, where molten steel is cast into 2 mm strip or less, in similar time. Both have Australian connections. A leading iron smelting technology is the HIsmelt« process, which has its first commercial application at Kwinana, Western Australia, where a joint venture of international parties, consisting of Rio Tinto and the Nucor, Mitsubishi and Shougang corporations, are in the stage of ramping up commercial production. The leading strip casting technology is the Castrip« process that arose from development work done by then BHP Steel, with IHI of Japan, at Port Kembla, New South Wales in the 1990s. Nucor followed this work up, building the first commercial plant for the technology at its Crawfordsville site in Indiana in 2001 and has recently announced an intention to build a second plant in the USA. While both technologies are only into the early stages of commercialisation they are likely to change the face of iron and steelmaking as we know it over the next 20 years. This paper elaborates on the technology of the two processes, why they could change the face of the iron and steel industry forever, what might drive the rapid change and what the changes may look like.

Jan 1, 2006

AND INTRODUCTION The Lochiel coal deposit, a large Tertiary soft brown coal deposit in the mid north of South Australia, is currently being investigated by the Electricity Trust of South Australia (ETSA) as a potential source of fuel for a base load power station. Feasibility studies indicated that the proposed dragline method of overburden removal was viable but economically sensitive to both highwail and dump batter angles. The unusual properties of the unconsolidated overburden sediments and the groundwater regime posed a number of intimately related hydrogeological and geotechnical questions which were addressed before and during the excavation of a trial pit. All strata at Lochiel are of soil strength, and artesian aquifers occur above and below the coal. From the initial evaluation of the deposit a number of hydrogeological questions were defined. These related to the rate at which the pore pressure in the silts is reduced by dewatering, the extent of the reduction in pore pressure due to prestripping, and the feasibility of dewatering and depressurising carbonaceous silty sand sequences. The site of the trial pit was selected to answer these and other questions from the basis of a detailed geological, hydrogeological and geotechnical understanding. The trial pit dewatering system simulated a full scale mine dewatering system and included ten pumped wells, twenty drainage wells, and nearly 400 monitoring instruments. It operated from September 1986 to June 1987. The excavation was carried out between February and May 1987.

Jan 1, 1988

Many operating hard-rock sulfide mines are predicted to require perpetual post-closure management to prevent environmental degradation. Causes include evaporative concentration of metals and other solutes in pit lakes, and acid rock drainage from sulfide waste-rock, tailings, and pit benches. Dilemmas posed by the prospect of perpetual management include: uncertainty in predictive models typically prevents reliable bounding on forecasts for the timing or magnitude of environmental impacts; comprehensive closure designs that can meet environmental standards may not be economically possible, particularly when applied retroactively to mines permitted under less stringent closure requirements; the publication of site-specific environmental analyses in peer-reviewed journals are discouraged in the current regulatory environment, hindering scientific advancement; and the durability of financial and government institutions cannot be assured for the long-time horizons over which mine impacts are predicted to occur. Re-evaluating mine closure in a framework of sustainable development (as proposed by the Mining Mineral Sustainable Development forum), can resolve, in part, these dilemmas. Key sustainability goals include: assurance of the social and economic well-being of the local community; assurance of the long-term environmental integrity of the region; and establishment of institutions capable of addressing (and learning from) long-term environmental management. Under a sustainability framework, impractical plans for immediate attainment of perpetually-stable closure may be replaced with a fund for long-term management of environmental impacts (eg through contaminant migration controls and exposure barriers), and a set-aside long-term growth reserve intended to eventually fund more complete closure. Fund expenditures would follow Adaptive Managementùa template for environmental-management institutions in which knowledge accumulated and uncertainty acknowledged explicitly. Under adaptive management, trusts would be flexible entities, supporting an evolving program of monitoring, predictive model refinement, and treatment. Periodic value of information analyses would target data collection efforts, refining the balance between predictable cost and uncertainty. This framework could overcome present-day financial shortcomings, enhance the field of environmental science, and meet the needs of future generations through the propagation of capita.

Jan 1, 2003

Peko Mines, a Division of Peko-Wallsend Operations Limited (PWOL) has operated several small underground mines in the Tennant Creek district of the Northern Territory supplying ore to a central treatment plant. The Argo Mine is the most recently developed by Peko Mines. A magnetic anomaly was identified from low level airborne magnetics in 1960 and drilling, which commenced on the site in 1969, was halted in 1974 and resumed in 1980 following the rise in the price of gold. By mid 1983 a resource of + 200 000 tonnes of 12 g/tonne Au had been outlined and a decision to develop the resource was taken following the drilling of three further diamond drill holes which did not significantly alter the value of the resource. The small size of the orebody could not support the full capital cost of two shafts and a single entry mine plan was developed to extract the ore at a rate of 15 000 tonnes per month and to provide all the safety features, ventilation systems and services of a two shaft mine. In December 1983 a contract was let to Allied Constructions Pty. Limited (Allied) to sink and equip a 4.8m shaft to a depth of 410m and to convert the headframe and winder, which are leased for the life of the mine by PWOL from Allied, from a sinking to a production configuration. Shaft equipment designed by Hardcastle & Richards Pty. Ltd. (H & R) in conjunction with PWOL includes a skip/cage, counter- weight, and an auxiliary cage on rope guides, a sealed ladderway and exhaust air ducts.

Jan 1, 1986

By D Connelly

Magnetite orebodies generally means mining lower grade iron ores, crushing and grinding with significant energy costs in processing and the capital costs being significantly higher than for direct shipping ores (DSO). Overseas, the mining and processing of magnetite ores has a long history of production due to the lack of DSO deposits. This raises the question as to why the new magnetite projects have been so problematic and also whether there is a future for the long list of potential magnetite projects in Australia.The quality of the magnetite concentrate product is superior to most DSO products and the magnetite contains energy benefits when converted to hematite in sintering or pelletising. The industry’s hopes for new projects have been dashed and questions are being raised as to the financial viability of such projects.A comparison of Grange Resources Savage River, Arrium’s Project Magnet, the Sino Iron Project and Gindalbie’s Karara Iron Project is used to understand the differences between the projects and why some are more successful than others.CITATION:Connelly, D, 2015. What is the future for magnetite projects in Australia and why have some of the new projects been so problematic?, in Proceedings Iron Ore 2015, pp 107–114 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By A Hacket, M Haest, I Vitins

Infrared spectroscopy has the ability to accurately measure mineralogy of drill cores, allowing for better spatial characterisation of iron ore deposits and potentially improving the prediction of key mining and processing parameters at the deposit scale. BHP Billiton Iron Ore is using infrared spectroscopic drill core logging to provide fast and accurate mineralogy for diamond cores and reverse circulation (RC) samples.Mineralogy can be predicted from infrared spectroscopic drill core data with errors on estimates ranging from six to 12 weight per cent. The error on the clay estimates is significantly lower than for hematite and goethite content estimates. This manuscript presents the results from a study on a bedded iron ore deposit, hosted in the Brockman iron formation, for which infrared spectroscopic data were collected on all of the diamond and RC drilling. Results show that these mineralogy estimates improve drill core logs, the geology model and the metallurgical block model.CITATION:Haest, M, Vitins, I and Hacket, A, 2013. Infrared spectroscopic drill core logging - making inroads to deposit scale 3D mineralogy, in Proceedings Iron Ore 2013 , pp 251-258 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By Johnson RW, Rogerson R

New perceptions of the nature of volcanic hazards on Bougainville Island have resulted from a recent remapping of the geology of the island. Ignimbrites and calderas have been identified at six Quaternary centres (Emperor Range, Tore, Kunua, Billy Mitchell, Loloru, and Laluai), and large-scale explosive activity now must be identified as a significant volcanic hazard on the island. Billy Mitchell and Loloru volcanoes are identified as the most likely sites of future, major, explosive activity. Billy Mitchell was recognised formerly as an extinct volcano, but is now known to have produced major eruptions 370 and 918 years BP. Five ignimbrite units recognised at Loloru range in age from about 12 700 to 3200 years BP. Bagana is an active volcano in central Bougainville, but its explosive activity is relatively minor and does not significantly affect areas beyond the uninhabited area of the volcano itself. Balbi is the largest volcano on Bougainville and has an extensive geothermal area at its summit. It was thought to have been in eruption last in the early nineteenth century. However, 370 and 940 year BP plinian ashfalls from Billy Mitchell cover the central area of Balbi, so the latest significant activity from Balbi may have been at least 1000 years ago.

Jan 1, 1990

The issue of flyrock is critical to the operation of all mineral extraction sites that use blasting. This paper takes a risk-based approach to identifying, analysing and managing the flyrock hazard. The basic cause of flyrock generation is a mismatch between the energy available and the work to be done. It should be noted that the energy available depends on the charge confinement. This mismatch can be caused by an abrupt decrease in rock resistance (geological weaknesses), overcharging, inadequate delays between holes and rows, inappropriate blast design and inaccurate drilling. The mismatch can come about from two sides; either too much energy (charge) for a fixed burden (work to be done), or insufficient burden (work to be done) for a fixed charge. The main mechanisms of flyrock generation are rifling, cratering, face bursting and secondary blasting. Each source mechanism has different characteristics in terms of vulnerable locations and each requires different control measures. However, all controls require a high level of quality control and assurance. A range of different approaches for managing flyrock risk and determining blast clearance zone dimensions are presented. A prescriptive consequence-based approach is discussed. A conventional risk matrix based approach is outlined with some innovation regarding controls rating and uncertainty ratings. A published semi-empirical approach is discussed. Two examples of quantitative flyrock risk analysis are presented; one involves bench blasting based on a published paper and the second is a cratering example developed by the author based on consulting projects. Finally, a stochastic approach based on published work is presented which simulates cratering superimposed on face bursting mechanisms. Also, a stochastic analysis undertaken by the author of the cratering example is presented. Effective blast emission management is required for two reasons; firstly to reduce and/or eliminate safety risks and secondly to manage public perception of blasting risks such as flyrock. The conclusion of the current research is that the wild flyrock risk can be estimated using existing techniques. Furthermore, both qualitative and quantitative risk management methods as discussed in this paper can be used for flyrock management for a given blasting situation. A combination of both is considered to be best practice.

Jan 1, 2007

By Stewart R, Manson RA, Haig DW, Perembo RCB, Kruman B

Since the advent of plate tectonic modelling, the Ramu-Markham valley has been thought the site of a classical island-arc/conti- nent collision zone. In this interpretation the units south of the Markham Valley are held to be island are / micrcontinental mate- rial accreted to Australia and those north of the valley are thought to represent a separate Finisterre island-arc terrane. Recent remapping by the Geological Survey of Papua New Guinea shows: (1) there is no terrane boundary along the Ramu-Markham valley (2) the Finisterre Volcanics are probably part of either a fore-arc sequence or oceanic plateau obducted onto a microcontinent/ volcanic-arc composite terrane, accreted to the continental Australian plate. A new tectonic model is proposed for northern PNG and involves: (I) Eocene to Late Oligocene subduction below a microcontinent remote from Australia to produce the Sepik are and related intrusives, the Finisterre Volcanics (fore-arc or possible oce- anic plateau), together with the Alife blueschist. (2) obduction of the Sepik arc in Late Oligocene-Early Miocene times over the advancing Australian plate. This resulted in crustal melting, some of the products of which are the Mid- dle to Late Miocene Akuna and Bismarck intrusive complexes of the Maramuni arc. (3) obduction of the Finisterre Volcanics began in Early Pliocene times and continues today. (4) post-Middle Miocene mineralisation is the result of melting after obduction of the Sepik microcontinent.

Jan 1, 1997

Computer software has been developed to link real-time information generated by underground mine ventilation airflow monitoring sensors into a network simulation program to undertake network simulations and allow interpretation of key system data and operational changes. Results were used in the development of a computerised monitoring and simulation system to provide immediate or real-time data on air behaviour within each branch of an underground mine ventilation network through linking of sensors to the ventilation network simulation software. The outcome of the project is an online system that can report changes in the mine ventilation system, allow causes of changes to be isolated and rectified, improve balancing of available air throughout the mine, allow improved approaches to regulator setting and dispense with much of the labour used for underground ventilation measurement. The work activities in both coal and metalliferous Australian mines have involved examination and modelling of regulators, software modification and considerable mine site testing and optimising activities. There is some discussion on approaches to control of flow through ventilation systems with increased information. New systems will be part of a total mine information management system. They will have to be cost effective and justified by gains in productivity. New systems will need to provide simulation of contaminant production such as diesels, vehicle heat, strata heat, radiation, blast fumes and other gases. More robust real-time ventilation simulation systems will be required. Personnel and vehicle identification and production tracking will be collected to provide integrated ventilation system monitoring and control. This paper examines a study to gain greater understanding of computerised real-time airflow monitoring and control within the mine production system to provide immediate simulated information in each branch of an underground ventilation network and to allow interpretation of key system data and operational changes. A case study implementing a real-time airflow monitoring and control is discussed. Approaches to control of flow through ventilation systems with increased information are discussed. The concept of a system that can be linked to or be part of a total mine information management system is developed. Such a system can form the base for mine automation that allows mines to incrementally and cost effectively implement monitoring and control to further seek gains in productivity.

Jan 1, 2005

After a short presentation of the Division of Mining at the Royal Insti- tute of Technology, Stockholm, Sweden, the author presents some of-the fill research carried out at the Division. Literature surveys and testing methods and equipment are described. The use of flocculants' in hydraulic filling has been tested both in laboratory and in mines and the results are very promi- sing. Finally compressibility investi- gations and some finite element calcu- lations are presented.

Jan 1, 1973

The Kelian gold mine which was developed in East Kalimantan Indonesia in 1990 - 1992 is scheduled to complete mining and processing operations in 2004. This will have a major impact on the neighbouring communities who have benefited from the jobs, economic activity and infrastructure development which has been generated by the mine. Currently, there are no formal regulations or standards specifying the procedures for relinquishment of mining leases in Indonesia. Furthermore, a move towards regional autonomy, providing greater authority and responsibility to local (regional) areas, has recently been implemented in Indonesia and limited capacity exists in the new regional governments. Consequently, in October 2000, Kelian Equatorial Mining (KEM) initiated a partnership with the local community and government to explore sustainable post-closure options for the mine site and community development programs. The Kelian mine closure strategy seeks full involvement of all stakeholders through the Kelian Mine Closure Steering Committee (MCSC) in the development of sustainable solutions which will enable communities to secure long-term benefits and minimise post-closure risks from the KEM operations. This organisation, jointly chaired by the Head (Bupati) of the regional West Kutai government and the KEM President Director, with representatives from the local communities, governments and NGOs, has developed a Charter, a website and evaluation criteria to ensure accountability and transparency. There are four technical working groups, consisting of representatives from the mine, local community leaders, NGOs, Universities, Local, Provincial and Central Government Departments, which report to the Steering Committee. These working groups have researched, developed and recommended sustainable options to the Steering Committee. The MCSC has met quarterly to examine options in accordance with the criteria set out in the Charter and has endorsed sustainable solutions which have support from Government, Community and the mine. This paper describes the closure risks, sustainable outcomes derived through the Kelian mine closure steering committee process and outlines the methodologies used to develop and endorse sustainable solutions in a society with limited capacity undergoing enormous change and uncertainty.

Jan 1, 2003

The New England Fold Belt forms the easternmost and youngest section of the Tasman Fold Belt System of eastern Australia. From middle Palaeozoic to Early Cretaceous time it was the site of extensive episodic calc-alkaline magmatism related to W-dipping subduction. The oldest rocks may have formed at least partly in a volcanic island arc, but from the Late Devonian, the fold belt developed as a convergent Pacific-type continental margin. For Late Devonian-Carboniferous time, parallel belts representing continental margin volcanic arc, forearc basin and subduction complex assemblages can be recognised. Major dextral transform faulting may have offset parts of the fold belt in the Late Carboniferous. In addition, some structural blocks which appear to be out of place in the overall palaeogeographic setting are possible exotic or suspect terranes. A great variety of lode deposits ranging in age from middle Palaeozoic to Early Cretaceous is present in the New England Fold Belt. The vast majority of these are related to emplacement of extensive granite plutons and eruption of continental silicic volcanics in Late Permian-Late Triassic time. However, volcanogenic massive sulphides and volcanic hosted epithermal gold-silver deposits in older rock sequences include one major orebody (Mount Morgan) and several important ones (Mount Chalmers, Cracow, Silver Spur, Cangai and Halls Peak). Some problematical deposits are best classified as metamorphic-hydrothermal. These include gold-bearing quartz reefs and stockworks in sedimentary host rocks, the most important of which are at Gympie, and antimony-gold- tungsten mineralisation in the New England area, mainly at Hillgrove.

Jan 1, 1987

By R S. Suglo, G-K Er

Mineral processing is an essential component of a mine production chain and it accounts for significant proportion of the production cost. Over the past decade, significant research progress has been made in processing plant efficiency using theoretical, experimental and simulation modelling techniques. However, these studies are limited to process plant system as stand-alone units with no interactions with the mining units. In order to maximise the total mining system efficiency and more accurately simulate the system, the processing plant must be modelled as part of an integrated mining system. This becomes increasingly important in continuous surface mining systems, with limited ore processing capacity. In addition, plant efficiency is roughly estimated with known parameters or with simplistic statistical data, without regards to the stochastic processes governing these parameters, such as processing plant feed introduction. In this paper, a comprehensive model of the ore processing plant system is given and the object-oriented design (OOD) of the system is briefly introduced. The joint operation of ore processing plant system and haulage system is analysed. Numerical modelling is used to analyse the ore processing plant system under different conditions. Analysis of the results show that the optimum plant capacity is 0.7 tons/sec (2520 tons/hour). The results also show that the plant system resources cannot be fully utilised because the production rate is always less than the plant capacity. When plant capacity reaches an optimum value 0.7 tons/sec, the production rate is about 0.64 tons/sec. The underlying stochastic processes associated with plant and mine capacities cause this variability. In order to reduce this variability, there is the need to tightly set tolerances for the function variables.

Jan 1, 2003

The Circum-Pacific is defined to include back arcs and continental areas of volcanism. Volcanoes must be regarded as dormant, if the time since their last eruption is less than about ten times the average interval between eruptions, even if they have not erupted for tens of thousands of years or longer. It is important to establish a complete history, over as long a period as possible, for varying volumes of eruptions. In order to assess risk, the average interval between eruptions should be calculated for each range of erupted vo4ume~, in orders of magnitude from about 10 m up to the maximum volume possible at each volcano. Eruptions are considered to consist of individual explosions, and are grouped into eruptive sequences, with the sequences grouped into overall cycles of activity. Frequency of eruption versus volume erupted is a linear relationship for most andesitic and basaltic volcanoes, but is often bimodal at rhyolitic volcanoes, 3 with a slower eruption rate above about 10 km. Worldwide, during the last 7000 years, there have been three known e~uptions with volumes of ejecta of > 100 km , a9d, since 1638 A.D., 7 with volumes > 10 km , and 48 with volumes > 1 km . Average recurrence intervals are about 71 years for eruptions of > 20 km , 39 years for those of > 10 km , and 7 years for those of > 1 km . Rough esti- mates can be made for larger volumes erupted. Mean intervals in the Circum-Pacific are about twice the length of those for the world as a whole. During the last 400 years, about 61% of the world's eruptions of > 1 km3 have taken place in this region.

Jan 1, 1987

By Mercer J. K

Shaft guide reaetions in No. 2 Ore Shaft, Mount Isa Mines Limited, have been reduced to a low order of magnitude by the use of self aligning slippers and spring loaded guide rollers. Before commissioning the new 4500 h.p. winder at No. 2 Ore Shaft in January, 1958, it was realised that the increase in hoisting speed from 1800 to 2650 ft/min. would cause high shaft guide reactions which would be increased further when the elongated 12 ton skips replaced the existing 7 ton skips.The Cambridge accelerometer was used to measure the shaft guide reactions and to confirm that progressive skip modifications were resulting in reduced reactions. The skip modifications were completed in 4 weeks.INTRODUCTIONIn 1956 an expansion programme was initiated to increase production from 5000 to 11000 tons per mining day. At No. 2 Ore Shaft the 1500 h.p. winder operated at 1800 ft./min. and hoisted a 7 ton capacity skip. The new 4500 h.p. winder operates at 2650 ft./min. and hoists a 12 ton capacity skip. No. 2 Ore shaft is equipped with two 5 ft. by 5 ft. hoisting compartments (Fig. 1) and any increase in skip capacity meant an abnormally long skip. This feature, coupled with the increase in hoisting speed, could have caused very high shaft guide reactions. Before commissioning the 4500 h.p. winder, a Cambridge accelerometer was borrowed from the University of Adelaide and was used to measure the shaft guide reactions. Rather than carry out an extensive shaft timbering programme, the skips were modified by fitting cushioned guide shoes and spring loaded guide rollers (Fig. 1). Testing commenced in February, 1958, and was completed in March, 1958.

Jan 1, 1961

By R Wynn, R A. Pax, S Mann, B Cornish

The semi-autogenous grinding (SAG) mill at the MMG Century operation has failing load cells that are essential to the control strategy used to stabilise the mill. Currently, mill-bearing pressure is used as a proxy for the load cells, but it has been found to be a noisy signal and lacking in useful sensitivity. It is also prone to variations and drift due to temperature. After consideration of a number of options, a non-contact acoustic array has been installed around the SAG mill to provide a more stable proxy load signal as well as other information about the internal operation of the?mill.The installation consists of 12 microphones to provide some detail into the operational differences that occur during normal operations at the MMG Century SAG mill. This acoustic approach acknowledges that operational grinding mills emit significant acoustic emissions that are a consequence of the dynamic environment prevailing inside them.Previous studies have attributed the acoustic noise to a range of events that occur inside these mills (Pax, 2011; 2012). Consequently, non-contact acoustic determinations of in-mill behaviour can provide powerful insights into the operation of the primary comminution tumbling mills. By measuring key microphone signal attributes at different positions around a mill, a holistic picture of mill internal operation can be developed.This paper will describe the installation of the 12 microphones and discuss the use of the acoustic load signals as a proxy for failing load cells. It will also present data from new observations of internal mill dynamics and the results of implementation of control using these acoustic signals. Key to the control approach has been the development of a logically coherent picture of the processes inside the mill.CITATION:Pax, R A, Wynn, R, Mann, S and Cornish, B, 2014. Implementation of acoustic arrays for semi-autogenous grinding mill?operation, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 273–282 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

The Mungana group of mines, in the Chillagoe district, yielded 334,000 tons of ore giving 31,831 tons of lead, 7,907 tons of copper and 3,228,600 ounces of silver. The Girofla mine produced approximately 220,000 tons of ore, and with the Lady J ane mine supplied most of the ore from this centre. The deposit was discovered in 1888, but active development did not commence from the main shaft until 1898. A subsidiary of the New Chillagoe Railway and Mining Co. Ltd., the Mungana (Chillagoe) Mining Co. Ltd., worked the mine from 1902 until 1914, selling copper, copper-lead, lead ores and fluxes to the smelters at Chillagoe. The smelters stopped operations in 1914 when the richer ores of the Girofla had been worked out and production from the Lady Jane had ceased due to heavyground and fire. The Girofla shaft was 823ft. deep with a cross-cut at 810ft. At the 710ft. level contour drives had delineated the orebody, which had been stoped about 10ft. above the level. Except for flux ores which had been stoped only for favourable smelter tariffs, the orebody was practically exhausted above the 610ft. leveL Under company ownership the mine yielded 139,265 tons of an average grade of 4.QlYr copper, 16.2% lead and 12.5 oz. per ton silver.In 1921 the Queensland Government re-opened the mine and worked it until 1927. The North Lode (Fig. 2) was discovered almost immediately at the 100ft. level and was worked down to the 410ft. leveL The ore from this branch and the completion of the stope at the 710ft. level yielded about 80,000 tons of ore averaging 0.4 copper, 9.8 lead and 7.8 oz. per ton silver during this period.

Jan 1, 1953

By Garg R. K

Himalayan ranges on the northern border of India are source of many perennial rivers and suitable sites for large dams have been located therein. However, Himalayas are young mountains and comprise of comparatively weaker rocks having adverse geological features like shear seams, thrust zones, minor and major faults and intense jointing. Tehri dam project under construction, is located in lower Himalayas. It envisages construction of a 260.5 m high earth and rock fill dam and an underground power station of 2000 MW (Eight machines of 250 MW each, four of which will be reversible) installed capacity. This dam will be the highest and the underground complex will be the largest to be constructed in India in the Himalayas. The under- ground complex comprises of 25 km of tunnels varying in diameter from 6 m to 11 m and seven large cavities of various sizes, the biggest being 22 m in width, 194 m in length and 65 m in height. Rock formation in the power house complex belong to phyllites having various joint sets spaced from 0.5 m to 3 m. Due to the poor geological conditions and closely spaced net work of large cavities, the planning, analysis and design of the cavities is a challenging job. Many aspects have to be considered in determining the sizes, locations and orientations of the various cavities taking into account the properties and jointing pattern of rock mass, functional requirements and economics. Correct evaluation of loads and forces is necessary for economical design of supporting system for the various cavities. Rock loads on the roof of cavities and their supporting system will be assessed with the help of the latest methods. The stability of the rock mass around the cavity will be evaluated by elasto- plastic method using finite or boundary element techniques. A scheme of field investigations, laboratory tests and instrumentation for deter- mining rock properties in preconstruction stage and for monitoring behaviour of the underground cavities during and after construction is envisaged.

Jan 1, 1987