Search Documents

Following the Coalbrook Colliery disaster in 1960, Salamon and Munro (1967) established the well known empirical coal pillar strength formula in South Africa. This formula has prevented further violent multiple pillar failures. In 1996, a back analysis of the collapsed and uncollapsed cases in Australia led to the development of the Australian empirical coal pillar strength formulae. The original collapsed and uncollapsed coal pillar database of Salamon and Munro (1967) was updated in 2006. This study introduced various strength formulae for different coalfields and seams in South Africa through back analyses of collapsed and uncollapsed cases. Today, the resultant pillar strength formulae from these previous studies and the behaviour of coal pillars are mostly well understood and applied with confidence. However, it was assumed in the previous studies that the behaviour of pillars is not time dependent; therefore, the formulae established do not provide an associated time to failure of coal pillars. This paper attempts to evaluate the so called 'Geometrical Limits' concept to provide the Australian coal mining industry with a tool to assess the long-term behaviour of bord and pillar workings where the pillars are prone to failure due to spalling of ribs. In order to achieve this outcome, the principles of the safety factor concept and the probability of failure calculated using the coal pillar strength formulae have also been evaluated and practical design examples are presented in this paper.

Nov 25, 2010

By P G Simpson

The Sundance gold mine, located 2.5 km east of the town of Batchelor in the Northern Territiory, has produced over 5300 oz of gold since it was discovered in 1978. Sundance is unique in the Pine Creek Inlier in that the ore is hosted in palaeo-karst detritus and crystalline magnesite of the Early Proterozoic Coomalie Dolomite. This paper presents a summary of the geology of the mine, and describes the methods used during the two periods of mining.

Jan 1, 1994

The Hyde Macraes Shear Zone (HMSZ) is an extensive low angle semibrittle mineralised structure in the Otago Schist Belt, New Zealand. The shear zone is located on the lower limb of a late metamorphic recumbent fold. Structural observations suggests that the shear zone initiated as a high strain mylonite zone and transgressed the ductile/brittle boundary (D4) later in its development. A surge zone at Round Hill is bounded to the south by a NE-SW striking lateral ramp which displaces the hanging wall shear (HWS) by 50 m. Oblique strike slip displacement during surge zone propagation created space for deposition of the sheeted vein complex or stockwork. Quartz recrystallisation in stockwork veins suggests that the veins were deformed in a ductile manner and implies that surge zone propagation may have occurred during late D3 deformation. A macroantiform was produced during D3/D4 shortening below the HWS. Over tightening of the antiform hinge created SW and NE-dipping ramp thrusts. Continued strike slip displacement along the lateral ramp rotated the antiform and associated ramps into a south plunging drag fold. Post-mineralisation (D5) structures include NE-dipping nonna! faults below the HWS and SW-dipping low angle imbricate thrusts above the HWS. The development of these structures was kinematically compatible with normal movement on the HMSZ and is related to mid Cretaceous break up of Gondwanaland in the SW Pacific.

Jan 1, 1992

By J V. Lawless

Mineralisation processes in epithermal deposits in the North Island of New Zealand are best illustrated by considering the two most productive deposits: Waihi and the Thames Bonanza Zone (TBZ), which have different mineralogies and ore shoots geometries. These two deposits can be taken as typical of certain styles of epithermal deposits worldwide, and recognition of their differences can be used to develop mineralisation models of predictive value. Waihi, the major economic producer in the Coromandel Volcanic Zone (CVZ), has laterally near-continuous ore shoots over a vertical interval of 600 m which consist of quartz, chalcedony, pyrite, base metal sulphides and electrum. They are found in the foot wall of earlier quartz veins which contain quartz pseudomorphs after platy calcite and adularia. The Thames Bonanza Zone which was the second biggest producer in the CVZ has discrete near-vertical ore shoots over 300 m vertically, which consist of quartz, pyrite, base metal sulphides, electrum and in their upper parts barite, that are enclosed in veins of quartz.   The gold mineralisation in both deposits is considered to be a co-precipitate with pyrite, with that at Waihi produced by prolonged boiling in an upflow of a hydrothermal system. That at the TBZ was produced by mixing a deep water primed for gold deposition by prior limited boiling, with an oxidised condensate of the steam released by the boiling, in an outflow proximal to the system's upflow.

Jan 1, 1997

By Koch D. F A

An electrochemical study of the dissolution of gold in aerated cyanide solution shows that the dissolution rate is determined by the nature of the surface. A passive film (probably a basic cyanide) formed at -0·6 V vs a saturated calomel electrode inhibits both the anodic dissolution of gold and the cathodic reduction of oxygen. Thallium has an "activating" effect on these reaction mechanisms.INTRODUCTIONIn general the dissolution rate of a solid in a liquid is studied by weight loss measurements or analysis of the solution at known time intervals. However, if the solid is a metallic conductor, on which a redox reaction can occur at the metal-solution interface, it can be studied by electrochemical techniques. Electrochemical measurements have the advantage that the overall reaction can be separated into its components, in some cases by electrical measurements alone, and in others by a combination of these with analytical determinations.The overall equation for the dissolution of gold in aerated cyanide solution may be written4Au + 02+ 8CN- + 2H20 = 4Au (CN)2- + 40H- ..... (1)which can be separated into the two electrochemical componentsrepresenting the oxidation of gold and the reductionof ogygen respectively.4Au + 8CN-,= 4Au(CN)2- + 4eand O2+ 2H20 + 4e = 40H- These two reactions occur at the gold-electrolyte interface and it is the purpose of this paper to discuss the mechanism...

Jan 1, 1964

By Carlos G. C

Geological mapping in various parts of Australia is revealing a number of regional associations of mineralizations with particular persistent stratigraphic horizons. Such associations have been found in the Broken Hill district of New South Wales, in the Nairne district of South Australia, in the Mount Isa district of Queensland, and in the Cloncurry district of Queensland. The question has arisen as to whether such mineralizations are of sedimentary origin, syngenetic with the enclosing formation, or whether they are of epigenetic origin, and reflect the selective hydrothermal mineralization of favourable beds on a regional scale.The purpose of this investigation is to test the use of sulphur-selenium ratios as an objective method of distinguishing between suphide deposits or sedimentary or supergene origin, and sulphide deposits of hydrothermal origin, with particular application to the districts mentioned. At the same time much data has been accumulated as to the selenium content of Australian sulphide ores. The possible use of sulphur-selenium ratios for this purpose was first demonstrated by Goldschmidt and his coworkers (1933; 1935), and later by Carstens (1941). Goldschmidt and Strock (1935) found that pyrite of sedimentary origin had a sulphur : selenium ratio of the order of 200,000 or more, whereas pyrite of hydrothermal origin had a sulphur: selenium ratio of 10,000 to 20,000. Carstensfound that sedimentary pyrite deposits in Norway contained less than 1 g. Se per ton, whereas hydrothermal pyrite deposits contained 20 to 30 g. per ton.

Jan 1, 1954

Mining education has received almost continuous discussion since its inception and most people engaged in the mining industry and in mining education feel at some time the urge and necessity to express their views. This paper is not a comprehensive survey of past and present practices and accepted principles, but a personal opinion of the form mining education should take at university level. It is expressed because of a dissatisfaction with the existing courses offered to students. It is hoped to provoke discussionand bring forth guidance to those engaged in mining education. After all, students spend four or five years at a university and it is desirable that the graduate should be something more than just those many years older at the end of his course.POST GRADUATE EMPLOYMENTThe first problem confronting the university should, be to discover what the mining industry wants and expects or graduates. This must influence the university course and yet universities have done little to seek this information, and if suggestions have been offered by industry; universities appear to have made little use of them. University mining curricula are basically what they were 50, 100 and even 200 years ago. (See Appendix.) Whether this reflects the unchanging problems of mining the wisdom of early professors, the conservatism of subsequent professors or inability to apprectate necessity for changes, is debatable.Unfortunately there is no uniformity in the type of employment offered to new graduates: Some mining...

Jan 1, 1959

By V A. Diemar

The Chatree Gold Project represents a greenfields discovery of metallurgically clean shallow gold mineralisation in a logistically simple terrain. Total Measured, Indicated and Inferred Resources are currently 31 tonnes of gold and 160 tonnes of silver. Gold occurs in an adularia-sericite epithermal system within quartz-calcite-adularia veins, breccias and stockworks. Host rocks are volcanic arc porphyritic latite-trachyte flows, their pyroclastic equivalents and volcaniclastics of upper Permian to upper Triassic age. The mineralisation was deposited in dilated zones during repeated reactivation of pre-existing structures. To-date five mineralised prospects have been defined by drilling with three reaching JORC Code Mineral Resources status. The project is in its definitive feasibility stage and is anticipated to be in construction during 2000.

Jan 1, 1999

Gold deposits in Eastern China have characteristic of belted distribution. The concentrating belts of gold mineralization are about parallel to the island are belt in Western Pacific Ocean. Gold deposits are mainly concentrated in the aged metamorphic rock series on the upwarping zones and upwarping fault zones, and obviously controlled by the deep fractures and their deriva-tive secondary faults. Gold mineralization had genetic relation to the Mesozoic (especially Yanshan period) magmatic activity. The distribution and genesis of gold deposits can be explained by the assumption of wavy structure. The formation of wavy structure is related to the process of Pacific plate and India plate.

Jan 1, 1990

The area around Big Bell was actively explored and sporadically mined for gold from 1904 onwards. The lease was named Big Bell in 1913. The property became established as a major mining centre with the development of the Big Bell underground mine in 1936. Mining operations commenced in late 1937 and ceased in January 1955, after milling 5.56 million tonnes of ore and producing nearly 21 tonnes of gold. In 1969 Australian Consolidated Minerals Ltd (A.C.M.) acquired the deposit then explored it alone and in joint venture until the current joint venture agreement with a subsidiary of Placer Pacific Limited (PPL) was negotiated in 1984. Following exploration and evaluation of near surface mineralisation, and a reassessment of the remnant pillars underground, the concept of a large open pit in conjunction with an underground mine evolved. The feasibility study was completed in October 1987, and the decision to go ahead was formally announced on 2nd December 1987. Placer Dome Technical Services Ltd were contracted to be the Project Managers, commencing construction on site early in January 1988 and handing the plant over to the operators 13 months later. The capital cost of the project at handover was estimated to be $133 million. The operating team commenced pre-production stripping of the open pit on 1st May 1988. By 31st January 1989 almost 16.0 million tonnes had been stripped and 350,000 tonnes of ore stockpiled.

Jan 1, 1989

By Rayner B

Five wells have been drilled in the Basker/Manta Block of VIC/P19, Gippsland Basin, resulting in sub-economic Intra-Latrobe Group oil and gas discoveries at Basker-1 and Manta-1. A total of 21 individual hydrocarbon bearing sandstones were intersected by the two wells. These reservoir sand bodies were deposited by fluvial processes in a lower coastal plain environment. The modelling of sand body orientation and geometry is a critical component in the evaluation of the two accumulations. Seismic resolution of the thin (average 2 m to 5 m) sand bodies is inadequate for mapping their orientation and distribution. Dipmeter data has been successfully applied to the problem of orienting the sand bodies using FMS images acquired during the drilling of Gummy-1 and reprocessed HDT data from Basker-1 and Manta-1. Prediction of lateral extensiveness (geometry) of individual sand bodies has also been attempted. Interpreted palaeocurrent direction from all three wells is dominantly from the NW to the SE. Reservoirs in the Manta-1/Gummy-1 area are interpreted to be predominantly channel sands, deposited by relatively low sinuosity streams. As such they would tend to have a laterally extensive, elongate geometry. Sand bodies deposited in the Basker-1 area show a predominance of laterally accreted cycles deposited by meandering streams. Channel geometry may then be limited in the downstream/upstream direction by internal permeability barriers such as clay plugs.

Jan 1, 1992

By Lewis PJ, Halfpenny R, Craighead GA

Exploration drilling by Joint Venture partners CRA Exploration Pty Ltd and Elders Mining PNG Pty Ltd has discovered a signif- icant copper and gold deposit at the Wafi River prospect, 60km WSW of Lae in Papua New Guinea. An indicated resource of 18Mt at 2.5g/t Au using a lg/t cutoff has been delineated in Zone A. No estimate has been determined for the separate copper occurr- ence at Rafferty's Zone but the copper will be significant to the project. Metallurgical studies on the gold indicate that the primary ore is refractory to direct cyanidation giving a highly variable and inadequate response. All conventional refractory ore oxidation techniques perform well on both ore and pyrite concentrate and oxidation occurs rapidly. No metallurgical studies on the copper mineralisation have been undertaken. Hypogene covellite and chalcocite copper mineralisation is associated with an intensely quartz-stockworked, and quartz and alunite-altered intrusive. Economically significant gold mineralisation occurs in distal subhorizontal lenses, within a sedimentary host, that plunge toward the intrusive. These lenses are sandwiched between overlying quartz and alunite-altered zones and underlying quartz and smectite zones in a mixed zone of quartz, dickite, kaolinite and illite alteration. The alteration and mineralisation is classified as a high sulphidation, epithermal style resulting from the influx of hot, acid magmatic fluids. Preliminary land ownership, road access, power supply and mine infrastructure studies are in progress. The project is currently at an advanced exploration stage.

Jan 1, 1991

By N Elith

Coal is a valuable energy source in New Zealand and has been mined from the West Coast for over 100 years. Stockton Mine is New Zealand's largest opencast coal producer supplying around 1.5 Mt of hard coking and thermal coal to international markets annually. The Stockton Plateau forms an extensive, gently inclined dip slope on erosion resistant Lower Eocene Brunner Coal Measures unconformably overlying basement rocks. The dip slope rises 600 - 1000 masl, locally dissected by fault scarps and present-day fluvial systems, some of which are deeply incised. Within the Mt Augustus Mining Block overburden comprises of a 30 - 40 m thick sequence of fluviatile, coarse to granular coal measure sandstones. High quality coking coal is preserved as a gently dipping, 10 - 12 m thick seam. High and sometimes very steep cliffs of jointed overburden shape the skyline escarpment, above steep forested slopes and gullies. As mining has progressed at Mt Augustus individual coal blocks are progressively becoming more technically challenging. This paper outlines the scientific approach taken by Solid Energy International and mining contractors to carefully unlock many thousands of tons of coal whilst protecting nearby flora and fauna from the impacts of dislodged rock and other blasting side-effects. The strategy involved: an expert-driven onsite risk assessment,formulation of a management plan to manage impacts,conducting an in situ vibration research program, andanalysis of results and operational designs to eliminate potential environmental problems.

Jan 1, 2003

In the course of the last twenty eight years the copper lodes of New Caledonia have been periodically worked or abandoned, until quite recently, probably attracted by the higher price of the metal, British capital has again been induced to embark upon the further development of several copper properties, which at present give reasonable promise of becoming regular producers. Owing to its proximity to Australia (only a three day's journey by mail steamer from Sydney) New Caledonia becomes of additional interest to Australian commerce in general, and it is to be hoped that the French Government may see their way before long to make the best of this natural position, to the mutual benefit of both countries concerned.Op till now all copper ores and concentrates which have been shipped from New Caledonia, were treated in Australian smelting works furthermore, Australian mine managers and miners have from time to time been connected with New Caledonian mining ventures, but, unfortunately, it must be said that nearly everyone of them returned to Australia thoroughly disgusted with his experience over there. Even to the casual observer, it is not so very difficult to find a proper explanation for these shortcomings in the peculiar economic conditions of the 'French colony, as many of the objections which have hitherto existed in connection with mining operations, were the direct consequences of a system of colonisation which could not possibly have been productive of better results.

Jan 1, 1901

The timber township of Powelltown, Victoria lies N.E. of Yarra Junction, 60 miles east of Melbourne and in the site of the mill of the Victorian Hardwood Company Proprietary Ltd.A lift gauge railway owned by the company connects Yarra Junction on the Warburton line, with the township through two or three smaller mill centres on the way.The company has been operating for some 12 years. In the divide, about four miles from Powelltown, between the Little Yarra and Latrobe rivers, cutting was continued with material being handled by winch and double incline haulage over the divide. A small bush locomotive dealt with the traffic between the divide and the cutting site.In order to reduce costs, which were heavy at the haulage, the company decided to make a continuous railway from Powelltown to the bush by means of a tunnel through the divide.Hand bore holes were put down on the proposed line of tunnel and showed that the divide at this point consisted of decomposed depth of about 100 ft. towards the eastern or Latrobe side - and that the undecomposed granite summit lay to the west of the surface summit.The bores also served to locate the underground water line, this was afterwards found to rise and fall with wet and weather.To avoid tunnelling in hard and heavy water, the grading of the was laid out with the summit of the hard granite the point in the line.

Jan 1, 1925

THE plant is one of the usual type of Mond plants, and contains no new features worthy of comment. A brief description of the process, however, with a few remarks on the working of the plant, may prove of interest.Producer gas is made by passing a mixture of air and steam through incandescent carbon contained in a furnace called a producer, which, in the Mond type, is a cylindrical casing of steel plate, lined with firebrick, and fitted at the lower end with sloping fire-bars'. Coal crushed to an even size (about 2-in. gauge) is elevated to bunkers over the producers, from which it is fed into a measuring hopper on each producer.The hopper is a cast-iron cylinder fitted with a swing cover at the top and a bell valve at the bottom, worked by a lever and balance weight. When a charge of coal is run from the bunker into the hopper, the cover is closed, and the bell valve is lowered, allowing the coal contents to drop into the producer. Thus no gas can escape from, or air be admitted to, the producer during the process of charging. The hopper discharges its coal through a steel pipe-shaped container called the bell, which projects about 9 in. through the roof of the producer. The function of the bell is to spread the coal evenly over the fire, and supply coal to any portion of the fire as it settles.

Jan 1, 1918

By Y S. M Tabatabaei, R Hosseini Tabata

Application of Acidithiobacillus ferrooxidans bacteria to flotation of Sarcheshmeh low-grade copper sulfide ore was studied. Sarcheshmeh low-grade ore contains pyrite, which causes some problems in the flotation of copper minerals. In this study, A ferrooxidans was used to change the surface chemistry of pyrite and copper sulfide ores and consequently, their flotation behaviour. In the presence of A ferrooxidans and xanthate as a collector, pyrite was depressed whereas chalcopyrite and other sulfide minerals were unaffected. In addition, the pulp pH remained unchanged. It was shown that the surface chemical properties of the bacteria could be manipulated successfully to achieve the desired effects in a flotation process. The results showed that the recovery of pyrite in the presence of the bio-depressant is 50 per cent lower than when no bacteria were present. At the same time the recovery of chalcopyrite remained unchanged.

Jan 1, 2004

By G J. Corbett, T M. Leach

A continued exploration programme has further defined the geology of the Tolukuma vein system, verified the resource indicated by Newmont, and identified potential for additional mineralisation. The resource at Tolukuma Hill, designated as zone C, is a mine recoverable 432,000 t at 18.1 g/t Au & 46 g/t Ag. Mining will be by a combination of open pit and underground at a rate of 100,000 t per annum. Processing will be by SAG mill, gravity circuit and CIL plant. A diatreme breccia, localised at an intersection of structures and a relationship of gold to base metal sulphides, are indicative of a strong porphyry association. Typical epithermal features such as crustiform banded quartz and quartz pseudomorphing platy calcite are also present and locally contain lesser gold mineralisation. Pre-existing dilatant structures have acted as a host to the ore fluids, resulting in the formation of the semi-continuous Tolukuma-Gulbadi veins over a 1100 m strike. A fluid flow model suggests that mineralizing fluids were sourced from a diatreme margin and migrated laterally along dilatant structures. Bonanza gold grades are interpreted to be derived through fluid quenching in the flexure between a hanging wall split, which hosts much of the Tolukuma Hill resource, and the feeder graben structure. Thus, the relationship between the pre-mineral structural geometry and fluid upflow at the margins of a diatreme breccia, controls the ore setting.

Jan 1, 1995

The mineralised members of the Brockman Iron Formation mined at Mt Whaleback are overlain and underlain by shale horizons. To maximise resource recovery, waste movement within the life of mine plan includes mining of the:unmineralised banded iron formation (BIF), Mt Whaleback Shale, Mt McRae Shale, Mt Sylvia Formation, and parts of the Wittenoom and Jeerinah Formation. With the exception of BIFs, all other units contain zones with varying amounts of sulphides and carbon û æreactive shaleÆ. Reactive shale has a propensity to self-heat and can react with some explosives, resulting in spontaneous explosion. Sulphide rich zones also have the potential to generate acid rock drainage (ARD). Mining reactive shale at the Mt Whaleback mine must be undertaken in a safe, efficient and environmentally responsible manner. Key tasks in the mining process include:100 per cent identification of blastholes that may contain reactive shale; 100 per cent correct loading of blastholes with specified blasting products; 100 per cent of reactive shale mined, hauled and dumped in designated overburden storage areas; 100 per cent containment and treatment of ARD water onsite; and ongoing research into ARD, self-heating and spontaneous combustion. Successful mining of reactive shale requires constant co-ordination between the geology, mine planning, mining and environment departments.

Jan 1, 2002

By Ware AR, Doyle BJ, Hoogvliet H

The Ladolam deposit lies within the altered volcanic rocks of the caldera floor, part of which now forms Luise Harbour. It was discovered in 1982 in the course of a reconnaissance drainage sediment sampling programme. This was designed to follow up indications of surface hydrothermal activity noted by Government geologists during an earlier survey of the Tabar-Feni island chain. Diamond drilling began in September 1983 and by the end of 1989 a payable and proved mineable reserve containing 19 million ounces of gold had been established. Rock types and structures are masked at the surface by intense alteration and weathering. An extensive drilling programme has enabled the identification of these features and the relationships between them necessary for an understanding of the factors controlling gold mineralisation. It has also led to the recognition of two distinct phases of alteration. The first phase of porphyry-style potassic alteration was followed by violent caldera formation, producing extensive brecciation and veining. The second alteration phase partly over- printed the first phase and was an epithermal one, evidenced by argillic, advanced argillic and phyllic assemblages. During this event, a large volume of fluids circulated under the favourable structural conditions; these fluids included a sulphur- rich, neutral chloride brine believed to have transported the gold. Boiling and mixing of circulating fluids in the open breccias is thought to have resulted in deposition of the gold. There is evidence that this process is continuing at the present day.

Jan 1, 1991