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By I Canbulat, G Si, Y Duan, X Luo

The presence of unfavourable geological structures such as faults and dykes often can contribute to coal burst risk. Seismic events associated with rock fractures tend to cluster around these structures and it is important to understand the characteristics of seismicity for coal burst risk management. In an Australian underground longwall coalmine, two clusters of seismic activities close to the longwall face and within a section of the maingate roadway which was intersected by a major dyke were respectively identified. The induced seismicity in the dyke-roadway area was closely related to the longwall mining. These seismic events were located and the distribution of seismic events shows that more fractures were distributed on the inbye side of the dyke. The spatial-temporal changes of the seismic event locations delineate the fracture propagation as the longwall mined through the dyke. The frequency-magnitude relationship of seismicity was analysed and it was found that it changed significantly when the longwall was mining towards, through and past the dyke. The monitoring results demonstrate that because of the stiff dyke, the seismicity was intensified in the roadway section. It proves that the dyke promoted stress re-distribution and seismicity in its vicinity. More fractures were induced in the hanging wall of the dyke, whereas less strain energy was accumulated and released in the footwall of the dyke.

Nov 29, 2022

This paper is based on studies made intermittently from 1937 to 1950. Its object is to describe the surface geology and the tin lodes, and to relate the lodes to the structure of the field.PREVIOUS REFERENCESR L. Jack made his first report on the field in 1880, but his principal report was made in 1883. W. E. Cameron described the Great Northern lodes in 1904. Numerous later reports on various mines were made by L. C. Ball, J. H. Reid and C. C. Morton, the most important of which were on the Black King, Good Friday, St. Patrick and the Great Northern Gully Shaft.GENERAL GEOLOGYJensen maps the Herberton area as part of a granite massif intruding rocks of two ages, the Younger Metamorphics of Silurian-Devonian age, and the Older Metamorphics of Older Palaeozoic age. The distinction is apparently based on lithological data. The Older Metamorphic rocks occur as inliers in the granite massif to the west and east of Herberton (Fig. 1).The area described consists of granite traversed by numerous dykes. West of the area, approaching the Older Metamorphic rocks, the granite becomes finer grained as if chilled towards its contact, and the dykes more numerous. To the east, passing from the Nova Scotia mine to Mount Lavery there are numerous dyke rocks, but the outcrops are poor and knowledge of the geology indefinite. The area is the main tin-producing area. To the west there are comparatively small tin lodes in the granite, and the "Copper Firing Line" occurs in the Older Metamorphic...

Jan 1, 1951

By A M. van Niekerk, W Mey

Coal mining has an impact on the water management of the water scarce Upper Olifants River Catchment. A prefeasibility study was carried out by Anglo Coal and Ingwe Collieries Limited to establish the water supply and demand in the catchment. A geohydrological model was used for the coalfields to determine the stored water and excess water available. Two distinct collective and treatment systems were proposed for the Witbank and Middelburg municipalities to treat excess water from the Anglo Coal and Ingwe Collieries Limited. The Emalahleni Water Reclamation Project for Witbank was initiated first. Water management and treatment experience gained at Anglo Coal was the cornerstone to develop the collection, treatment and distribution system. A full enquiry was issued to Keyplan, Veolia, Bateman Africa and IST Technik to construct, commission, operate and maintain a 20 ML/day desalination plant to treat acidic, saline mine waters to a South African National Standard (SANS) 0241 Class 0 potable water. After the technical and financial adjudication, Keyplan were awarded the contract. An integrated regulatory process was adopted through consultation with all the relevant regional and head office staff of the Department of Minerals and Energy, Department of Water Affairs and Forestry and the Mpumalanga Department of Land Affairs via an authorityÆs steering committee. A rock engineering evaluation was done to select both the plant and waste disposal sites as all possible sites are undermined. Various contracts are required with the individual mines for water supply, the Emalahleni Local Municipality for the delivery of potable water and for the disposal of wastes.

Jan 1, 2006

By J S. Petersen

The occurrence of coarse gold particles leading to grade complexity and sampling challenges is a common feature of many gold deposits. Poorly designed sampling protocols applied to these deposit types can lead to an excessively high fundamental sampling error. Together with other errors, the fundamental sampling error contributes to the nugget effect. Proper sample collection, preparation and assay protocols are required to minimise this error, and hence reduce the total nugget effect. Reduction of the nugget effect is a key requirement for subsequent geostatistical resource estimates to be effective. A case study from the Nalunaq gold mine in Greenland is presented, which is characterised by notable quantities of coarse gold (>30 per cent +100 ¦m gold) hosted in quartz veins. Diamond drilling provides a good measure of gross geological continuity at practical grid spacings, but is not considered to represent the mineralisation effectively. On-reef development with face and bulk sampling, together with detailed geological studies were undertaken during the resource delineation phase. This contribution describes the nature of the Nalunaq deposit, its gold particle size characteristics, how sampling and assay protocols were developed (including QA/QC issues), application of GyÆs sampling theory and its calibration, and how the data was subsequently applied to grade estimation.

Jan 1, 2005

By L Faulkner

The Tarnagulla Gold Project in Central Victoria, Australia, was developed and operated by Reef Mining NL between 1994 and early 2000, producing 53 000 ounces of gold from the Nick OÆTime Shoot, a single narrow vein shoot structure within part of the larger Poverty Reef, with a strike length ranging from 30 m to 60 m. The ore shoot was developed over a vertical interval of 190 m, using a small cross-section decline and small, mechanised equipment. Various stoping methods were employed including mechanised cut-and-fill with a single boom jumbo, hand-held mining using airleg drills and rope scrapers, and small uphole retreat stopes using a line of sight remote operated LHD to recover a crown pillar. Experience during stoping showed that airleg drilling and rope scrapers gave much better dilution control than diesel equipment. Innovations included a low-cost hydraulic fill system. Due to the small scale of the deposit, the feasibility studies, planning and permitting for the mine were based on very limited drilling information; however, the mine was brought into production within two years of the discovery. While the mine made an operating profit, it failed to fully repay capital at the low gold price then prevailing. Applying the lessons learned from the operation to optimise the access and stoping method, the project is re-examined at todayÆs gold price and operating costs. Central Victoria has the potential to host many similar small deposits. The authors were respectively Non-Executive Director and Resident Manager for Reef Mining NL when the mine was operating.

Jan 1, 2008

By L E. Krause

This paper discusses the considerations for optimum maintenance of critical ore handling infrastructure in order to minimise the cost to the business of maintenance periods. As maintenance periods are a direct interruption to production, time is of the essence and careful management of shutdown periods is essential. The ore pass systems currently in use at Xstrata Copper û Mount Isa Copper Operations are up to 30 years old and have had significant wear over the years. The maintenance of these passes and their brows and chutes in a production situation is a challenge as it can potentially expose personnel to high risk situations in addition to the production interruptions. Some alternatives for mitigating the risk of working in ore passes including plugging and ballooning are described. Criteria are included for selecting a method for the safe entry into a given ore pass. Experience in adapting the method of ore pass plugs and some lessons learnt in the process are also discussed.

Jan 1, 2005

By Lawrence L. J

The Australian Broken Hill Consols Mine, situated some 600 yd east of the main Broken Hill line of lode, is noted for its rich ores of silver. In contrast to the vast conformable orebodies of the Broken Hill field, the Consols lode occupies a narrow fissure dipping to the south west at angles increasing from 240 through to vertical and transgressing the strike of the metamorphosed country rock at an oblique angle. This feature, together with the abundance of calcite and siderite and the virtual absence of silicate minerals in the gangue, has led to its classification as an orebody of the Thackeringa type (King, 1953). Recorded production during the period 1890 to 1903 is given as 845,000 oz of silver and 20 tons of lead.The unusually rich silver values of the Consols lode were concentrated at the intersection of the fissure with beds of amphibolite, whereas in the adjacent schists and gneisses the lode became markedly impoverished. From the surface to a depth of some 120 ft extensive surface oxidation had occurred, resulting in the breakdown of siderite and its replacement by limonite and associated manganese oxides.Silver halides, dyscrasite, acanthite and partly oxidised tetrahedrite were the main silver minerals in this zone. With increasing depth the lode material gradually reverted to minerals representative of the hypogene zone.The only previous work specifically on the mineralogy of the Consols lode is that by Smith (1922), one time manager of the mine. His zeal as a mineral collector resulted in much valuable information being available on the distribution of the minerals. More recently, Garretty (1943) noted the...

Jan 1, 1962

Facies associations in the Okiduse Volcanics, woodlark island, suggest that two major volcanic centres erupted synchronously during the Middle Miocene. These centres are referred to as the Watou Mountain Eruptive Centre and the Uvarakoi Caldera. The Watou Mountain Eruptive Centre, centred on Boganuse Mountain in the Okiduse Range, was a typical, moderate-sized composite volcano (or stratovolcano). The seq-uence is readily divisible into lava (Boganuse lava unit), breccia (Nikuben breccia unit) and epiclastic (Talpas sandstone unit) dominant facies, typical of composite volcanoes. These facies girdle Boganuse Mountain and they are interpreted to represent vent, cone forming and ring plain associat-ions, respectively. These facies indicate a reconstructed volcano of approximately 1,700m height with a basal diameter of 7km. The presence of limited exposures of intrusive associated with the vent facies (Kuike'beimmicrodiorite) suggests that the volcano is only partially dissected. The Uvarakoi Caldera is a felsic volcanic system contrasting with the mafic Watou Mountain centre.

Jan 1, 1994

SINCE 1900, five underground fires of consequence have beenrecorded in the Broken Hill mines. These occurred at the Junction(1906), Proprietary (1906 and 1916), Block 14 (1906), and Centralmines (1923). All have been extinguished, but at an enormouscost; e.g., in the eleven months following on the 1923 Central mine fire the sum of £187,123 was expended in fire-fighting operations.To this series may be added others, as the South (1925) and British mine (1918) fires, which were extinguished before serious damage had resulted. All, however, have occurred within a period of 28 years, and in a district where spontaneous combustion, a prolific source of fire in the U.S.A., has been practically nonexistent. Therefore, definite fire risks exist in the underground workings of the Broken Hill mines, and, as a consequence, an active fire prevention policy is a necessity...

Jan 1, 1929

By H Bartosiewi, M Kuruppu, F Mashiri

Wire ropes are one of the most heavily used components in a dragline. They are subjected to harsh conditions during the regular usage of a dragline in a mining operation. Hoist ropes are subjected to fatigue due to the cyclic nature of load handling as well as due to rope bending over the sheaves and the drum under load. This leads to wire breaks due to fatigue. Accumulation of a number of wire breaks close to each other can have a detrimental effect on the rope. Furthermore, to allow for the increasing demand for higher load capacity coupled with the inconvenience of having very large ropes, the factor of safety is often compromised, which increases the wear rate. Drag ropes are also subjected to heavy loads. More importantly, they are allowed to drag along the rough mine surface subjecting them to external physical abrasion. This makes the life of drag ropes one of the lowest among those used in a dragline. Suspension and IBS ropes are relatively uniformly loaded during their regular usage although they need to withstand dynamic load cycles as well as bending. Hence they tend to last for a number of years on average. The paper analyses the wear types and their severity of each of these rope applications, and suggests methods to determine rope wear rates and the resulting rope life. The paper further gives suggestions for good operating and maintenance practice that can extend the rope life and help reduce the large expenditure associated with every major rope change in a dragline.

Jan 1, 2005

By S Long, A J Koen, D MacKay

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

Mar 24, 2014

By Rankin W. J

Increasing concern with the emission of sulphur dioxide from smelters and roasters has caused renewed interest in processes which can use waste sulphur dioxide, such as the sulphation of nickel laterite ores. The process described here proposes to by-pass the production of sulphuric acid and react laterite directly with a sulphur dioxide containing atmosphere. A thermodynamic analysis identified operating windows in which nickel sulphate forms while iron oxide (the major impurity in most laterite ores) remains stable. The initial assumptions included unit activity of all species except nickel oxide. The lowest possible nickel oxide activity (while maintaining selectivity) increased with increasing temperature, indicating that selective sulphation is favoured by low temperatures. The temperature of interest was found to be between 500 and 800¦C. Calculations show that a feed gas containing ten per cent SO2, five per cent 02, balance N2 requires a temperature greater than 650¦C for selective sulphation of nickel. Laboratory experiments showed that the assumption of unit activity of ferric sulphate was unrealistic above about 680¦C due most likely to the formation of solid solutions which decreased the ferric sulphate activity. Results are presented which illustrate the limiting equilibrium sulphur trioxide partial pressures at 700 and 730¦C below which selective sulphation occurs. Cobalt extraction was usually between 80 and 95 per cent under conditions yielding selective sulphation, whilst nickel extraction was about 50 to 75 per cent depending on temperature and choice of upper limit of iron extraction. An operating diagram is presented for a limonite ore and shows that the optimum reaction conditions are 680¦C and an input gas containing 20 per cent SO2. Under these conditions nickel, cobalt and iron extractions are 73, 95 and two per cent respectively.

Jan 1, 1996

By O Tiili, A Dixon

Many minerals processing plants need to have greater efficiency in current times and optimise their process performance in order to maintain high profitability. This is even more so in the current economic climate. In the case of large flotation cells, such as TankCell«-300 with over 300 m3 active capacity, ensuring consistent operation and optimal flotation conditions is particularly critical, given the high impact on overall process and throughput of such cells. As there are fewer cells to control and monitor, there is also a lower initial capital cost for instrumentation - the requirements, however, are higher. Despite such compelling reasons, instrumentation and basic control in flotation cells has not changed much in recent years. The standard is still to use traditional feedback (PI algorithm) controls for slurry level and flotation air. A new advanced instrumentation and control package for large flotation cells has recently been developed by Outotec and has been installed at Macraes.In addition to the standard basic instrumentation and control, the new system at Macraes consists of a froth image analysis system, a froth velocity control, and a level control system which utilises adaptive feedforward compensation. There are three TankCell«-300 cells in operation at Macraes since November 2007 and the new control system was commissioned in December 2007.The paper will include comparative data from pre- and postsystem installation and discusses benefits including optimised recovery, improved performance, as well as ease of operation.

Jan 1, 2009

By T Perera, B Fan, S Thang, T Hsia

The mining industry is currently focusing to develop and adopt sustainable collector chemistry that can efficiently recover valuable minerals from their natural state. However, a limited number of research can be seen on the design and synthesis of polymeric flotation collectors. The focal objective of this research is to synthesise a more effective polymeric collector with advanced architecture to utilise in the mineral processing industry. Reversible Addition-Fragmentation Chain Transfer (RAFT) co-polymers with cardanol derivatives have the potential to selectively trap valuable metals in the flotation process in a more efficient way. Cardanol exhibits amenability to chemical modification for making tailor-made monomers that can further produce polymers with high value. The synthesis of a series of fit for purpose copolymers in this study was accomplished by RAFT polymerisation. The ability to design complex architecture is a significant advantage in engineering polymeric collectors by RAFT polymerisation. Initially, commercially available cardanol was converted to a cardanol based monomer and copolymerised with commercially available monomers to synthesise a series of novel cardanol based copolymers with predetermined molecular weights. The side groups of the copolymer were chemically modified to incorporate functionality that can be selectively adsorbed on the chalcopyrite surface.

Aug 24, 2022

By Chugh Y. P

A simplified, three-dimensional, time-dependent, mechanistic model of the overburden-coal seam-floor interaction has been developed and validated at two Illinois coal mines. The model based on the thin plate theory can involve any complex layout of mine workings, time-dependent sequence of extraction and, rheological properties of immediate floor strata. The model output data consist of spatially distributed surface subsidence and its slope and curvature, as well as load acting on pillars in one or more panels. A comparison of calculated and monitored surface subsidence or in- mine convergence measurements has proven the model's effectiveness for surface subsidence and load transfer Prediction.

Jan 1, 1992

By Blair JR

The tunnel alignments investigated for the Gosford Regional Sewerage Scheme are located in the Terrigal Formation and are covered for most of their length by a thick blanket of soil and weathered rock. The following techniques were found to be most effective in geotechnical investigations for tunnelling in this area: air-photo interpretation, seismic surveys to pinpoint drilling targets, in-situ measurements of strength,deformation modulus and permeability in cored holes, and the construction of rock- mass models. Cross-hole seismic modulus measurements, surface resistivity soundings and electric well-logging techniques were found to have limited applicability due to adverse local conditions.

Jan 1, 1976

The ore deposits investigated are composed primarily of hcmatite and can be grouped into three categories depending on the amount of leaching of silica and carbonate which has occurred from the original iron formation, and on the amount of recrystallization of the hematite. Minor constituents are magnetite. goethite, and quartz.Texturally. there are five different types of hematite, formed at different stages during the genesis of the ores.These are1. anhedral hematite grains formed by recrystallization of hematite already present in the original iron formation.2. hematite formed by martitization of euhedral magnetite, 3. massive aggregates of fine- to medium-grain hematite formed by recrystallization of (l) and (2).4. tabular or prismatic hematite grains occurring around the boundaries of the massive aggregates or martite euhedra. and in fractures and5. specular hematite. which is present in fractures in ore types (l) to (4).Minor and trace-element analyses, determined using an electron-probe microanalyser. indicated that only silica (less than 0·01 per cent) and cobalt (less than 0·002 per cent) were present in the magnetite and hematite from unaltered iron formation and in the hematite from the ores. Low concentrations of trace elements are typical of magnetite in ores formed as marine precipitates. On the basis of the analyses alone. it proved impossible to distinguish between the five hematite types. A determination of the variation in rare-earth trace element contents between iron oxides in the iron formation and iron oxides in the ores indicates that the rare earths were depleted during ore formation. A possible explanation is that they were removed in solution with silica as it was leached from the iron formation.

Jan 1, 1971

By Fitzgerald DE, Taverner MG

The principles, fields of application and equipment design concepts of several new approaches to continuous vacuum treatments of molten metals and alloys are discussed. Partic- ular attention is paid to the results of pilot plant tests evaluating a launder-in-tube method of 1. continuous production of refined zinc from a zinc-bearing lead produced in the lead splash condenser of the Imperial Smelting Furnace (ISF), and 2. continuous refining of crude cadmium. The former trials were not sufficiently encouraging to justify consideration of the process for commercial development. The applic- ation to cadmium upgrading gave very promising results; metal of 99.99 per cent purity was produced continuously at pilot scale (120 lb per hour) from crude metal containing 5.0 per cent Pb.

Jan 1, 1972

By G W. Scott, R C. Johnson

Hypogene alteration zones have been described as a precursor to high-grade haematite deposits in Australia, Brazil and elsewhere. This alteration is described as being below or distal and is typically magnetite-carbonate-silicates reflecting Mg - Fe metasomatism. This paper describes, without genetic implication, the mineral zonation and possible structural control on mineralogic variation within the Tilden Mine, a concentrating grade haematite deposit in Michigan, USA. In contrast to the high-grade deposits, these variations are not peripheral to the orebodies but are the ore. The deposit occurs within the Negaunee Iron Formation, along the southern margin of the Paleoproterozoic Marquette Range Supergroup basin. The regional structure is a fault-bounded west plunging syncline within the crustal scale Great Lakes Tectonic Zone, which forms the boundary between Archean granite-greenstone and gneissic terranes. Local structure consists of second-order anticlines and synclines with variable northwest and southwest plunges. The interaction of sedimentation and diagenesis within growth fault controlled basins, along with a possible metamorphic and/or hydrothermal overprint has resulted in a complex series of ore types. For modelling purposes, the deposit is divided into geologic domains based on both lithology and metallurgical response in the laboratory and in the plant. Mineralogic variation is recognised within individual mineral grains; at blast pattern (10 - 15 m) and development drill hole (100 m) scales.

Jan 1, 2007

When the new No. 3 Shaft is in full operation, the main hoisting duties will be in connection with the raising of: (a) ore from the various mining operations, and (b) mullock, or broken country rock, from development work in extending access to existing levels, opening up new levels, exploratory work, or sinking the shaft to greater depths.

Jan 1, 1957