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By M E. Trim, J J. Johnson, W Cranston

The Brightwater conveyance system is located near Seattle, Washington in the north-western United States. The East Contract portion of the system consists of a 4.3 km long, 5.9 m diameter tunnel in soft ground and two large shafts constructed in challenging soil conditions. The two shafts are situated side-by-side in an urban valley. One will house an influent structure to direct incoming sewage and outgoing treated effluent, while the other will house a 645 megalitre per day (ML/d) influent pump station. The tunnel contains four pipelines: two force mains to convey untreated wastewater eastward from the new pump station to a new treatment plant, one gravity-pressure pipeline to convey treated effluent westward to a new outfall in Puget Sound, and one high-pressure pipeline to convey reclaimed water from the treatment plant to downstream distribution points. The shafts and the tunnel presented many design challenges. Groundwater is near the surface in the area surrounding the shafts, and compressible peat and clay soils preclude dewatering during construction. These and other challenges were encountered during design of the pump station shaft and multiple-pipe tunnel. The challenges were addressed by a design that includes a dual intersecting circular cell shaft (referred to as æthe peanutÆ) and a single tunnel into which stacked pipes will be æstuffedÆ. This paper discusses the design approach and design details for both elements.

Jan 1, 2008

By K Vallo, T Haimi, J Pihlasalo, J Hamuyuni, M Lindgren, F Tesfaye

Decarbonisation of the steel industry has recently attracted a lot of research and technological development. Most of the technological developments are centred around the replacement of blast furnace (BF), which has been the main primary smelting furnace in the ironmaking step of steel production. Replacement of the BF is not an easy task because of BF’s many established capabilities over the years, especially its ability to use low-grade iron feed. In this regard, Metso has developed its own technology, Metso’s Outotec direct reduced iron (DRI) smelting furnace, to tackle this problem. The recently developed six-in line electric furnace for DRI smelting can be used for primary smelting of DRI from blast furnace grade iron ore. Unlike the electric arc furnace (EAF), the DRI smelting furnace can handle larger slag volumes that emanate from the high gangue in BF grade DRI. Therefore, fluxing plays an important role in operating the DRI smelting furnace. This paper presents fluxing options and proposes slag quality and operating windows for the DRI smelting furnace. Also, the effect of slag on refractory durability will be discussed.

Jun 19, 2024

In 1980 Pancontinental Mining Limited decided that while the Jabiluka uranium project was still a major focus of the company's efforts some diversification was necessary. At this time it was decided to include precious metals in Pancon's exploration and acquisition objectives. As a result the now Paddington Gold tenements were acquired, explored and developed. Today, it rates as the 6th largest gold mine in Australia and at an expanded throughput of 1.2 million tonnes per year of ore it will produce about 110,000 ozs of gold per year. Following extensive exploration activities by Pancon's Exploration Division the Operations Division continued with development drilling finally proving up a reserve of about 8.4 million tonnes at an average grade of 3.2 g/t. An in- house preliminary feasibility study was followed by a two phase feasibility study by Davy McKee. This resulted in a recommendation to the Pancon Board of Directors to develop Paddington with an annual throughput capacity of 875,000 tonnes. This paper describes the acquisition, exploration and development of the Paddington project. It goes on to

Jan 1, 1986

By N Van Buc, E Coroiu

The rapid socio-economic growth of Hanoi City coincides with a corresponding growth of the transport demand. Today, the transport in Hanoi is completely dependent on private modes of transport. Because of the lack of an efficient public transport system and the expected rapid increase in traffic volumes, the movement of people and goods in the urban areas of Hanoi will cause congestion in the present city transport network. The solution of the construction of new roads, or the widening of the existing streets, is very expensive in urban areas and usually causes many social problems due to the resettlement of people. From the point of view of the number of inhabitants, Hanoi City is now over one million. Above this number the international experience shows that the public transportation must be a mass transport system with large capacity, commercial speed and also independent as much as possible from the street network. According to the Hanoi Master Plan for 2020, the Hanoi urban population will be over 3.5 million persons. Also, in the next 15 years, the distances between centre-destination points will be doubled by comparison to 1995.

Jan 1, 1999

By G J. Keyter, P J. Terbrugge, Yu Xianb

There has been disappointingly little development in the understanding of the behaviour of rock slopes in open pit mines over the past 30 years. The lack of development in general, and of robust, standardised approaches in particular, are surprising in view of the æultraÆ deep open pit mines that are being developed to depths in excess of 1000 m. Research has recently been carried out into the occurrence of zones of extension strain in open pit slopes. This showed that very large zones of extension strain can occur, and this finding represents a significant new aspect in slope stability that has not been considered before. The greatest magnitudes of extension strain occur near the toe of the slope, either in the slope itself, or in the floor of the pit. Results of the research will be presented for different slope heights, slope angles and horizontal to vertical in situ stress ratios. The magnitudes of the strains are considered to be large enough to result in fracturing of intact rock, and the fracture orientations predicted are adverse for slope stability. Fracturing that is extension in nature is common in competent, brittle rocks and often develops with some violence and little or no warning, producing easily measurable seismicity. In the slope situation, the expected physical manifestation of this behaviour would be popping off of rock slabs and plates of rock from slope surfaces and popping up of the pit floor, as well as the formation of new fractures within the rock mass. Such behaviour may cause overall slope failure, or may initiate failure, which may then be driven to overall slope failure by other influencing factors or combinations of factors. In addition to instability resulting from the fracture surfaces themselves, all induced fracture surfaces could interact with natural geological structures to facilitate formation of a significant failure surface. Case studies of slope failure in two open pits will be described. In both cases failure occurred æsuddenlyÆ after very limited amounts of deformation. In the first, the slope crest moved suddenly upwards and backwards over a length of more than 200 m, with associated instability. In the second, the horizontal displacement of the slope face was almost an order of magnitude greater than the vertical displacement and occurred æsuddenlyÆ. A recently installed seismic system is detecting events in a significant zone behind the slope face. Both pits were in the 200 m to 300 m depth range at the time of the occurrences.

Jan 1, 2003

By J Zhou, D M. Hunter, S M. Iveson, K P. Galvin

The recovery and concentration of ultra-fine iron ore can provide significant economic benefits. Presently, there are limited options available given the low settling rates achieved by conventional gravity separation and the relatively poor performance of reverse flotation. The Reflux Classifier is a new water-based gravity separation technology that consists of a set of parallel inclined channels positioned above a vertical fluidised section. This arrangement promotes a powerful throughput advantage compared to conventional fluidisation and a highly selective hydrodynamic basis for achieving sharp separations. A high shear rate develops within the inclined channels, which generates sufficient hydrodynamic lift to convey the lower-density particles (even if they are relatively coarse) to overflow while retaining the high-density particles (even those that are ultra-fine) for discharge to the underflow. The technology has previously been used around the world on particle sizes in excess of 0.1 mm. The present work, however, is concerned with density-based separations down to much finer particle sizes approaching 0.01 mm.A major advantage of the Reflux Classifier technology is the achievement of simultaneous gravity separation and desliming via a single-stage separation. A series of continuous experiments was conducted using an iron ore feed with head grade of 35 wt per cent FeT and nominal top size of 0.106 mm, with 59 wt per cent being below 0.038 mm in size. At a low throughput of 1.5 t/(m2 h), the Reflux Classifier produced high-grade products at a high recovery. For the entire feed, grades of 66.1 wt per cent FeT with Fe recoveries of 80 per cent were achieved in a single-stage separation. Within the 0.020–0.038 mm size fraction, grades of 68.8 per cent were achieved with iron recoveries of 94.7 per cent. Excellent recoveries of up to 57.0 per cent were achieved for the -0.020 mm size fraction. The ability of the inclined channels to retain the fine dense material further enhances the effectiveness of the Reflux Classifier by creating an autogenous dense medium effect within the vertical section. This helps to elevate large gangue particles up into the overflow.CITATION:Hunter, D M, Zhou, J, Iveson, S M and Galvin, K P, 2015. Gravity separation of ultra-fine iron ore in the reflux classifier, in Proceedings Iron Ore 2015, pp 143–148 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

The economic significance of a fundamental understanding of the mineral pyrrhotite is dis- cussed. Particular emphasis is placed on the relationship of other sulphide minerals to the pyrrhotite when it is the major sulphide mineral present in an ore body. Studies of the Kambalda nickel deposit are used to give a better under- standing of (a) the genesis and other character- istics of a particular ore body (b) the textural relationships between pyrrhotite and other sul- phide minerals (c) magnetic properties of natural pyrrhotite, and (e) the oxidation and supergene processes that take place in a sulphide ore body.

Jan 1, 1972

By H Kundapen, B R. Bolton, H Davies

The Ok Tedi porphyry copper-gold mine is located in the Star Mountains of Western Province, Papua New Guinea. Open-cut mine commenced in 1984 and is due to cease around 2010. The mine produces a total of 88 Mt of waste annually including 58 Mt overburden and 30 Mt tailings, which are discharged directly in to the Ok Tedi River. Mine derived wastes are transported downstream and deposited within the river channel in a variety of bar forms. The prevailing hydrogeological conditions including, velocity, competency, capacity, gradient, grain size and specific gravity, control the deposition and segregation of these sediments. Periodic exposure of the reactive sulfides to oxygen during fluctuations in the river discharge may result in oxidation, localised acid generation and liberation of metals into solution. To evaluate the significance of this issue, Ok Tedi Mining Limited initiated an investigation of the sediments deposited in the upper Ok Tedi River as part of its overall ARD Management Program. The specific objectives were to: evaluate the acid-forming characteristics of identified high sulfide river deposited sediments; characterise geochemically the waters in contact with sulfide-bearing river deposited sediments; map and monitor exposure areas and oxidation depth of deposited potentially acid forming (PAF) sediments; determine the depositional processes controlling sulfide distribution; and assess lag period, oxidation and metal release rates for the sediments. This work included the analysis of sediment and water samples collected on a 50 + 50 metre grid at six gravel/sand bars. The sediment samples were analysed for total sulfur, ANC, NAG, total sulfur and total copper. Water samples were tested for general water quality parameters, sulfate and a suite of dissolved metals including; Al, Ca, Cd, Cu, Fe-sol, K, Mg, Mn, Na, S and Zn. This paper presents the results of these investigations with particular emphasis on the geochemistry of the river sediments and associated contact waters.

Jan 1, 2003

By Johns AS

Comissioning of a new residue disposal tcluding upgraded classification for none backfill preparation, new variable speed pumps and a new residue dam took place in 1¦76. The system is described.

Jan 1, 1978

This paper presents the findings from an experimental study of the effects of shock and gas penetration breakage mechanisms in rick blasting. A blasthole liner method, which realistically seperated these two basic sources of energy in blasting, was developed and utilized. The use of four different explosives with contrasting detonation behaviour produced a wide variation in the nature of explosive energy transfer to the rock. Through extensive field experiments it was found that, relative to low VOD dynamite, the high VOD emulsion imparted greater shock to the rock and therefore produced finer fragmentation and greater back damage. The comparatively lower heave energy of the emulsion caused less immediate blast results were obtained with watergel and ANFO explosives, which have detonation behaviour and energy partitioning charecteristics lying between emulsions and dynamite.

Jan 1, 1990

By R W. Henley, L Knuefing, M Turner, Y Zhang, M Saadatfar, A Limaye, R Cruikshank, M A. Knackstedt, A Kingston, L Beeching, N Francois

A better understanding of ore fragmentation and the textural features of ore is a key to the energy efficient extraction of targeted minerals from low-grade ore deposits. In this study, X-ray microcomputed tomography (micro-CT) is employed to study mineral liberation during the tensile failure and onset of fragmentation of a copper ore. Our results show that X-ray micro-CT could inform new studies of ore micromechanics and fragmentation at the laboratory scale and may offer new avenues to address current challenges in the design of efficient comminution processes. We present the results of experiments based on a high-pressure apparatus enabling micromechanical studies to be carried out in situ (inside a micro-CT scanner). This platform produces high-quality 3D images of the evolution of a sample of porphyry copper ore during an in situ fragmentation test. A sequence of tomographic images enables mapping in 3D of both the deformation of mineral phases and the fragmentation process. The fragmentation occurs quasistatically through multiple stages starting with an initial tensile fracture splitting the ore diametrically, followed by tensile-activated nucleation and growth of multiple fractures producing a complex fracture network. Coupling breakage with microstructural information enables quantitative determination of the impact of ore texture heterogeneity on fracture patterns and mineral liberation. This microstructural information can be compared to key measurements of the ore mechanical behaviour such as the global deformation energy, strain deformation field and the stress relaxation response. The latter allows one to identify interesting precursor signals of the tensile failure. The copper liberation, fragment size distribution and breakage patterns are statistically characterised and related to comminution mechanisms which are clearly identified in the sequence of tomographic images. The two dominant mechanisms are rock-rock friction/compression induced by fracture closing and compression-driven fragmentation at rock-crusher contact points.

Aug 24, 2022

By G York

South African gold reserves extend to great depths. However, strategies for the mining of such deposits have changed only slightly over the past number of years. Regional support at depth is currently provided by rock pillars and backfill. Many problems have been experienced with these regional support practices at deeper levels. In this paper several alternative forms of regional support are described which include the use of concrete, the use of back area caving and confinement to strengthen pillars. These new concepts are supported by numerical and laboratory modelling and in situ results.

Jan 1, 1998

By H Kusumi, A Nishio, K D. Halim, Y Yun

In Japan, evaluation of rock mass is crucial in mountain tunnels that are constructed using the NATM (New Austrian Tunneling Method) to determine the support pattern that in turns determine the final support structure of the tunnel. The current evaluation method is highly dependent on the observations of on-site expert engineers that grades the rock mass in four levels across nine criteria: A. Condition of tunnel face. B. Condition of excavated surface. C. Compressive rock strength. D. Weathering. E. Spacing of discontinuity. F. Condition of discontinuity. G. Orientation of discontinuity. H. Spring water. I. Water degradation. However, in recent years, the number of said experts are decreasing rapidly due to labour shortage caused mainly by an aging population and declining birth rates. This is one of the biggest challenges that the construction sector currently faces, and this may affect the efficiency of tunnel construction projects in the future. Thus, this study proposes the implementation of a deep learning tool called the convolutional neural network (CNN) to quantitatively evaluate rock fractures on tunnel face. In addition, Gradient-weighted Class Activation Mapping (Grad-CAM) is applied to visualise CNN, as well as verify the applicability of CNN to the evaluation of rock fractures. In other words, by creating heat maps of tunnel face images, CNN is utilised to evaluate rock mass in categories that are associated with discontinuities. The CNN model is most accurate when six convolution layers, four pooling layers, and three dense layers are used. This yields an accuracy of 75.0~88.0 per cent. Thus, the CNN model is verified to be feasible method to evaluate rock fractures.

Nov 29, 2022

By D Elmo, M Scoble, Y Liu, B Klein, J Scholar, S Nadolski

A cave-to-mill study being conducted at the New Afton block caving operation demonstrated the potential for sensor-based ore sorting equipment to reject waste and improve the grade of feed to the mill. The lack of selectivity and potential for dilution entry associated with the block cave mining method results in many caving operations having to mine and process material that is below cut-off grade at certain stages of production. Online monitoring and bulk sorting systems have the potential to alleviate this problem and improve the productivity of caving operations while reducing energy and water requirements for each tonne of concentrate produced.As part of the cave-to-mill study, the suitability of a range of sensors, such as X-ray fluorescence and induction-type sensors, to sort mine production at the New Afton mine was investigated. Results showed that the discrimination of ore and waste can potentially be carried out by implementing surficial sensors into the material handling system. The study also showed that a combination of sensor outputs could be used to identify a certain ore type so that pre-emptive changes can be made in the mill to improve beneficiation performance. Overall, the outcomes of the study on implementing sensor systems at block cave mines are considered to be of significant relevance to a number of existing and future caving operations.CITATION:Nadolski, S, Klein, B, Elmo, D, Scoble, M, Liu, Y and Scholar, J, 2016. Investigation into the implementation of sensor-based ore sorting systems at a block caving operation, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 393–400 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Fowke NC, Williams RJ, Hungerford F

In-seam, directional drilling has been implemented at Huntly West Mine, New Zealand as the most cost effective means of obtaining geological information at a level of detail and accuracy required for planning of longwall ("flexiwall") panels. No geological or geophysical technique tried at the mine prior to 1989 has been able to reduce geological risk to an acceptable level. Surface and in-seam seismic methods have not had adequate resolution. Obtaining the required knowledge via surface drilling would be prohibitively costly, and still not precisely locate or orient faults or the axes of seam "ridges and valleys".A total of 3543 m was drilled at an average of 67m/shift including setting up time. Unplanned delays totalled only 9.6 percent. Major re-interpretation of seam structure resulted from the drilling. Lateral and longitudinal panel grades have been defined. which should be negotiable with the Coalcorp longwall equipment.

Jan 1, 1991

The moisture content of clean coal contributes significantly to the product's transportation costs, handleability characteristics and/or energy value. A major contributor to the total moisture is the ever increasing proportion of fine coal in

Jan 1, 1994

By C M. Stewart, P Bowen

McArthur River Mine, in the Gulf Country of the Northern Territory, exploits one of worldÆs largest deposits of zinc, lead and silver. It was officially opened in September 1995, 40 years after its discovery in 1955. This paper describes the geological, engineering and metallurgical assessments which made up the feasibility study. It then relates how these study components compare with the first two years of operation. The challenges that had to be overcome before the McArthur River Mine became economically viable included the metallurgical problems associated with extremely fine grained ore and the development of an effective mining process.

Jan 1, 1998

By Segnit ER, Boow J

The start up operations of Western Mining Corporation's Kalgoorlie nickel smelter encountered troubles due to the high magnesia content of the concentrates. The flash smelter slags, with higher than normal magnesia content, had a much higher melting point than the normal low-magnesia, predominantly fayalite slags usually produced in nickel smelting. Investigations were made of the structures, melting points and viscosities of the Kalgoorlie smelter slags, as produced, and with additions of silica or lime.

Jan 1, 1980

A review of the factors controlling stope wall behaviour such as excavation geometry, rockmass strength, induced stress, ground support, blast damage and drill drive layout is undertaken. In addition, the advantages and disadvantages of single lift stope geometries linked to vertical crater retreat are also analysed. Finally, key components of multiple lift stoping such as cut-off slots, production rings, stope undercuts and drawpoints are studied in detail.

Jan 1, 2000

By Butler I. K, Nicholson P. M

There are four main types of base metal and gold mineralisation recognised in the central Pine Creek Geosyncline. These are stratiform, polymetallic veins, stockwork/concordant gold-quartz veins and unconformity related uranium-gold-platinoid mineralisation. The stratigraphy of the central Palaeoproterozoic Pine Creek Geosyncline has been simplified into three groups comprising the Batchelor, Frances Creek and Finniss River Groups in ascending order. Stratiform mineralisation occurs within the Frances Creek Group. The earliest mineralisation is found adjacent to circular faults ringing basement highs. Higher in the stratigraphy, stratiform mineralisation is often associated with zones of high compression in the vicinity of basement highs. A synsedimentary-diagenetic origin for stratiform mineralisation is proposed. Polymetallic vein mineralisation occurs within the Frances Creek and Finniss River Groups. Its composition changes systematically through the stratigraphy similar to the stratiform mineralisation. The mineralisation is structurally controlled and usually occurs in the vicinity of basement highs. Stockwork-concordant gold-quartz vein mineralisation is hosted by the upper Frances Creek and Finniss River Groups. It occurs within compressional zones and along the Pine Creek Structure corridor around, above and particularly between basement highs. Mineable reserves occur in thick continuous semi concordant quartz-sulphide veins and/or stockworks. Unconformity related uranium-gold-platinoid mineralisation shows a close spatial relationship with the Palaeoproterozoic/Mesoproterozoic unconformity. The mineralisation is localised by structures formed during Mesoproterozoic deposition and is commonly adjacent to Archaean basement or its remobilised equivalents. The type of mineralisation (stratifom/polymetallic vein) is a reflection of local stress regimes, structure and physio-chemical conditions. An initial phase of stratiform mineralisation is postulated to have occurred with the first significant marine transgression in a tensional regime. A second phase occurred later during a compressive regime. "Ihermochemical sulphate reduction of mineralising fluids by hydrocarbons is invoked as the precipitation mechanism for the polymetallic vein type of mineralisation. Hydrocarbon generation is postulated to have occurred within the Frances Creek Group, in many places contemporaneously with the movement of mineralising fluids and basin compression. Polymetallic veins formed from the interaction of mineralising fluids and hydrocarbons which were trapped in suitable structures. An abundant, continuing supply of hydrocarbons was necessary to form significant deposits. Where these conditions were not net, the mineralising fluids largely continued their ascent to the near surface environment to form stratiform deposits. The stockwork/concordant gold-quartz vein mineralisation is a later event and occurred during the relaxation of compressional defonnation after deposition of the 1-inniss River Group.

Jan 1, 1994