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It's long been suspected that there has been an increase in the incidence of premature failure of rock bolts in underground coal mines over the past ten years. As far back as 2002 a study found a possible contributor to such premature failure in some Australian coal mines might be linked to stress corrosion cracking (SCC) (Crosky et al, 2002). That study suggested the low impact toughness could be a major influence on the susceptibility to SCC of different steel compositions. A subsequent study involving laboratory corrosion tests however failed to confirm any link with metallurgical factors (Villalba and Atrens, 2007), a finding that is at odds with field experience. Some mine sites today are still reporting prematurely failed rock bolts to the rock bolt manufacturers; the failures are being identified at SCC induced. To this end a research project has recently been commissioned at University of New South Wales (UNSW), which aims to identify the environmental factors causing SCC, through field test sites and simulating the conditions within an accelerated corrosion laboratory. This paper outlines the methodology that will be used in this study.

Nov 25, 2010

By B B. Beamish

Long-hole directional drilling for in-seam exploration was introduced to New Zealand at Huntly West Mine in 1989. Following the success of this initial drilling program the Coal Corporation of New Zealand (CoaICorp) purchased its own drilling equipment and proceeded to adopt the technique with in-housetraining. From July 1991 to September 1992 a total of 15 455 metres was drilled at Huntly West Mine. During this period several modifications were made to the drilling technology to suit the ground conditions. The resulting interpretations of the drill information enabled reliable seam definition to be incorporated in mine planning. Since January 1993, the technique has been transferred to the Huntly East Mine to assist with seam definition for the planned development westwards under the Waikato River. The benefits of this drilling technique to coal mine planning are now well documented in Australia and New Zealand as well as other overseas countries. The possibilities of adapting the long-hole drilling technique to hard rock applications has been illustrated recently with successful cross-measure drilling at Huntly East Mine.

Jan 1, 1993

Present roof bolting practices in the collieries of Australian Iron and Steel Pty. Ltd. are outlined. Roof support has been improved since introducing roof bolts and it is hoped to increase the reliability of the bolts still further.Expansion-shell, and split and wedge roof bolts five to eight feet long are placed by "Atlas Falcon" and "Fletcher" roof bolters. Both anchorage and tightening have presented some problems.Good panel supervision is required if systematic roof bolting is to be properly co-ordinated with coal production without unnecessary delay to either. Successful roof bolting can only be the product of conscientious men and supervisors who are all convinced of its value. A rigid operational code should be established early and maintained.INTRODUCTIONRoof bolting is a method of support which is permanent and reduces or eliminates the need for other support; The method was pioneered in America and was first experimentally investigated in Australian collieries at Elrington in 1949 (McKensey, 1953). Pneumatic installation methods were employed. Subsequently, a method of using standard hand-held electric coal drills was developed at John Darling Colliery (Horseman, 1954). Pneumatic roof bolting equipment was first operated in the collieries of Australian Ironand Steel Pty. Ltd (A.I. &. S.) in 1951. Since then various hydraulically operated mobile machines have been installed in Australian collieries and these, together with improved pneumatic equipment, form the two present basic methods of placing ,roof bolts. Roof bolt anchorage is achieved by either split and wedge or expansion-shell bolts.The two broad types of roof bolting are 1. consolidation of strata, and 2. suspension support.

Jan 1, 1961

As it is probable that a large proportion of the members of the Institute attending this meeting are connected with the metalliferous side of mining, the writer thought that, as coal and coke are required for various purposes in considerable quantities by their companies, some particulars of the coal industry might be of interest, especially when visiting such an important coal-mining centre as Newcastle. It is proposed to deal with the matter from the mining and economic point of view, as the geology has been so well and exhaustively dealt with in various publications referred to in the bibliography at the end of this paper. In the immediate vicinity of the city of Newcastle the collieries are gradually being abandoned, and during the past few years the Wickham and Bullock Island, Stockton, Hetton, Newcastle Coal Mining Company's "B," and the Australian Agricultural Co's Sea pit, have disappeared from the coal-producing list of collieries. AIl of these collieries worked the Borehole seam, from which, up to date, the largest quantity of coal has been produced in the northern district.It is the bottom seam of any present commercial value in the Upper or Newcastle coal-measures, and although the coal-in this seam has not been entirely 'exhausted in the collieries referred to, they have been abandoned for various reasons. For example, although about 60% of the seam (18 to 20 ft. thick) was left in the workings in the form of rectangular pillars under the city of Newcastle, this was not sufficient to 1?revent'the subsidence which took place about twelve years ago.Again, large quantities of coal in the Borehole seam have been left to protect the shipping arrangements at the Dyke, and other...

Jan 1, 1918

By P Atkinson, M P. Simpson, J R. Kyle

BM37 is a bonanza-grade (>30 ppm Au) ore shoot of the Maria Lode of the Karangahake adularia-sericite epithermal deposit in the southern Hauraki Goldfield. Samples from BM37 contain up to weight percent gold. The ore shoot is a vein that pinches and swells, but is typically tens of cm thick, and locally exceeds 0.5 m in true width. Gold occurs as irregular anhedral electrum grains that range up to 300 microns across and contain 38 to 59 wt per cent Au (ave. 52 wt per cent Au). Electrum occurs in sulphide-rich bands in association with pyrite, chalcopyrite, acanthite, galena, sphalerite, and local covellite. Lower grade samples contain local to rare mckinstryite [(Ag, Cu) 2S] and polybasite [(Ag, Cu) 16 (As, Sb) 2S11]. Pyrite from BM37 is nearly stoichiometric; it lacks the As that commonly occurs at up to percent levels in pyrite from other veins in the goldfield. Acanthite also contains low quantities of trace metals, and typically has less than 2.5 per cent Se. The vein shows complex textures. Bonanza grade sulphide-rich ginguro bands form discrete layers adjacent to the vein margins, and occur as breccia fragments encased by later massive to comb quartz with local quartz after platy calcite. Both the breccia fragments and ginguro bands are cross-cut by later quartz veins. Textures thus indicate that formation of the high-grade portions of BM37 resulted from one or more discrete events that differed markedly from the events that formed the bulk of the vein.

Jan 1, 2006

A calibration of the Frantz isodynamic magnetic separator relates the current in the electromagnet and the transverse slope of the chute to the specific susceptibility at which separation is being effected. In addition to providing a rapid measure of the specific susceptibility of minerals and composite grains, the calibration provides a guide to operation of the Frantz isodynamic separator for mineral separation, and to the nature of composite grains. The most sensitive magnetic separation is obtained by using the highest practicable current and transverse slope, and the lowest practicable longitudinal slope.INTRODUCTIONProbably all minerals have a magnetic susceptibility measurable by sensitive techniques. However, magnetic separation between minerals which have low but different specific susceptibilities, and which for many purposes are considered essentially non-magnetic, has only become practicable with the development of the Frantz isodynamic separator.The construction and principle of this highly sensitive separator has been described by S. G. Frantz as an appendix to a description by 'Gaudin and Spedden (1943) of its application to the separation of sulphides constituting mill products.Various publications (e.g. Hess, 1949, Hutton, 1952) refer to its use in separating the mineral constituents of rocks, ores, and unconsolidated sands.As used in this study the Frantz isodynamic separator consists of a vibrating chute mounted centrally between the pole pieces of an electromagnet (Fig. 1). This unit may be inclined in any direction by the universal mounting, and the electromagnet current is continuously adjustable from 0 to 1·5 amperes.

Jan 1, 1957

Laboratory scale equipment was developed to recover zinc as oxide fume from granulated lead blast furnace slag. The cyclone furnace process is characterised by high treatment rates combined with continuous and independent operation.Results were sufficiently encouraging to warrant pilot plant scale trials being undertaken.INTRODUCTIONSince granulation of lead blast furnace slag started at Port Pirie in 1921 the stockpile of this material has increased to nearly 5 million tons which averages 17·5 per cent zinc by weight. Although a number of processes for recovering the zinc have been examined, economic considerations indicate that a slag fuming process is likely to be most suitable.In the conventional slag fuming process zinc is extracted by injecting pulverized coal and air into a molten slag bath. By maintaining a suitable air to coal ratio the oxidised zinc contained in the slag is reduced to metal. Volatilization of the zinc is followed by reoxidation in the gaseous phase with the addition of further air above the bath. The zinc oxide fume so produced is collected by normal gas cleaning methods.By examination of the thermodynamics of this process Bell, Turner, and Peters (1955) determined the zinc oxide activity of the slag over the duration of the fuming cycle.A combination of high temperature and high carbon monoxide/carbon dioxide ratio was found necessary for rapid zinc elimination.Since melting of the slag is an essential step in the slag fuming process, only two treatment methods appeared possible at Port Pirie until recently...

Jan 1, 1964

By W Taylor, S Chen, R Haywood, M White, R West, J Ranasinghe

In March 2012 a combined BHP Billiton and Hatch team embarked on a program to improve the concentrate burner efficiency of BHP Billiton’s Olympic Dam copper flash smelting furnace. A multi-faceted approach including an analysis of the furnace using operational knowledge and first principles engineering led to the design and supply of a new central-lance (disperser). A new, patented, swirl method of introducing the copper concentrate into the furnace was developed to integrate with the existing concentrate burner. Plant trials in 2014 demonstrated an increase of nearly 10 percent in the oxygen efficiency of the furnace. The improved efficiency is expected to provide savings in operating costs and asset life extension of downstream gas and dust handling equipment.CITATION:White, M, Haywood, R, Taylor, W, Chen, S, Ranasinghe, J and West, R, 2015. Improved copper flash smelting at Olympic Dam, in Proceedings MetPlant 2015, pp 382–395 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By K Nilsson, D Connelly

Troy Resources acquired the Karouni Gold Project in Guyana, South America in 2014 and immediately proceeded to a Pre-Feasibility Study and project implementation. The study considered two open pit mines feeding a conventional carbon in leach (CIL) gold plant with a capacity of 1Mtpa. The study assumed a total of 2.61 million tonnes of ore with an average grade of 3.84 g/t gold with a recovered gold production of 303,526 ounces over a three year mine life.The project development involved drilling metallurgical test holes, securing second-hand major pieces of equipment where suitable, and arranging shipping to Guyana. The remote location meant logistical considerations were paramount. The plant consists of conventional two-stage crushing with single stage ball milling and a gravity circuit. The tailings circuit includes DETOX.The extremely high rainfall presented challenges with water management and the necessity to dispose of clean water to the environment. The DETOX was also mandatory due to the highly sensitive environment and past history in the area. The criticality of this meant that in the design, any cyanide in the tailings would precipitate in a plant shutdown.Lessons were learned and the project has been both profitable and successful for Troy Resources in a new operating location. In addition, the project has created jobs, delivered royalties and brought new skills into an area where previously there was little current mining activity.CITATION:Nilsson, K and Connelly, D, 2015. Karouni Gold Project from drill core to commissioning, in Proceedings MetPlant 2015, pp 197–206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By P Rowe

New Zealand Steel's Taharoa titano-magnetite mine, south of Auckland, set two national load records when it transported around 2000 t of mining equipment three kilometres overland on time, under budget and without safety incident. It was the first time in New Zealand that four platform trailers were assembled end-to-end to transport a load. It was also the first time that a single load of 1000 t was transported on platform trailers. The need for the relocation of all equipment was realized five years ago. It took two years of planning and specialist advice to relocate the mine's 250 t dredge, 500 t surge bin, 1000 t concentrator plant and ancillary equipment from the Southern Mining Region across a specially designed haul road to the Central Mining Region. The project was carried out during a six-week shutdown in early 2001. Two dry docks were constructed, one at each end of the relocation route. The equipment was floated into a dismantling pond that was interconnected with the dry dock in the Southern Region. Through pumping, the water levels were controlled to allow transfer of the separated units from the dismantling pond into the dry dock. Once drained, sets of self-elevating platform trailers were used to transport the main units, one at a time, between the dry docks. Five prime movers were used to pull the loads. At the receiving end, the units were off-loaded in a dry dock interlinked with ,the first mining pond. The equipment was relocated because the reserves in the Southern Mining Region were mined out. A natural watercourse û the Wainui Stream û defines the northern boundary of the Southern Region and the objective became to relocate the mining plant to the other side of the stream and re-establish in the Central Region. The project team selected the trailers as the most effective means of transporting the equipment, particularly given the non-invasive means of crossing the Wainui Stream. Negotiations with prime contractor Tranzcarr Heavy Haulage Ltd commenced in mid-2000. The remainder of 2000 was spent in developing concepts with the contractor, detailed designing, preparing the dry docks, haul road and initial mine plan for the Central Region. These activities occurred with no conflict to the normal site production.

Jan 1, 2001

By A J. Eggers

With gold first discovered at Carrick in 1864, exploration and mining on the Carrick Goldfield in Central Otago, New Zealand, has now been ongoing for more than 130 years. Recorded historical hard rock production from up to 52 different mining claims from 1864 to about 1921 is 24,047 ounces (oz) of gold.   Since 1980 Amoco Minerals New Zealand Limited, CRA Exploration Pty. Limited, Amax Gold Mines New Zealand Limited and Summit Gold (New Zealand) Limited have conducted modem systematic exploration campaigns targeted at locating shear controlled gold bearing quartz lodes and stockwork deposits. More than NZ $1million has been spent by these companies on aerial photography, geological mapping, stream sediment surveys, soil and rock chip geochemistry as well as reverse circulation (RC) percussion and diamond drilling.   RC drilling by Summit Resources in 1997 has identified a 1,500 m long zone of low-grade gold mineralisation at Lower Carrick, with an average grade of 1.00 g/t Au over a 14 m average thickness. This gold mineralisation, hosted within a low angle shear zone, has analogies with the Hyde-Macraes Shear Zone in eastern Otago. Recent exploration and drilling at Carrick has revealed the potential to discover large (>0.5 million ounce (Moz)) low-grade bulk shear controlled quartz vein and stockwork gold deposits similar to those now being mined at Macraes.

Jan 1, 1997

Since the end of World War n, many important developments have taken place in the investigation of the phenomenon of brittle fracture in mild steel. Fractures in certain classes of welded ships, in welded bridges, penstocks, etc., focussed a great deal of attention on the interrelationships of design factors, service conditions, and steel quality on the generation of catastrophic failures.Much publicity has been given these major failures, and there is perhaps a tendency to forget that mild steel, under certain conditions, as well known to behave in a brittle fashion in a wide range of everyday engineering applications.For instance, many who are connected with the haulage and lifting of heavy loads will be familiar with the bright "crystalline" fractures of crane hooks and chains which sometimes follow sudden jarring; those concerned with the heavy pressing and shaping of steel plate will not be unaware that at times sudden brittle splits or tears will develop for no obvious reason in, say, rolled pipes or in dishings.In fact it will be evident upon reflection that in many cases the conditions which mild steel has to withstand during processing into an engineering part or structure are more severe than those it wili be called upon to endure during service. In this sense brittle fractu;res in mild steel are much more frequent than are commonly supposed.Two modes of fracture are now generally recognised to occur in metals, namely, shear and cleavage. The latter manifests itself by the so-called "crystalline" fracture (here...

Jan 1, 1954

The ore treatment expansion programme at Mount Isa Mines required the erection of a new lead-zinc concentrator to be known as No. 2 Concentrator. This concentrator was designed by Western-Knapp Engineering Company in conjunction with staff of Mount Isa Mines Limited. Metallurgical design followed conventional wet milling practice, but the size of many plant units is larger than previously used at Mount Isa. The. total capacity of the new plant is 150,000 tons per four weekly period, and the plant is designed to operate in two equal parallel sections.Erection was contracted on a turnkey basis, and the plant was commissioned as a production unit on 23rd June 1966.The existing concentrator, No. I, was converted to treat all copper ore, and the total capacity of the two plants is now 390,000 tons per four weekly period.

Jan 1, 1968

The mineralogy, textures, and genetic significance of a silver-rich siderite vein and an apparently co-genetic galena vein from the South mine, Broken Hill are discussed.Both veins cut sharply across the Main Lode Horizon and appear to be coeval with thc A.B.H. Consols lode.The minerals of thc siderite vein apparently result from the preferential leaching of silver from Main Lode Horizon ore with a demonstrable "breakdown series" commencing with tetrahedrite, passing through silver sulpho-salts, and ending with simple binary compounds or with elemental silver.The siderite vein has been deposited by metahydrothermal fluids along the lines of Schneiderhohn's "secondary hydrothermal" mineralization.

Jan 1, 1968

The C.S.A. copper-lead-zinc mine, located 7 miles north of Cobar in central-western New South Wales, is the largest known mineral ocurrence in the Cobar mining field. The generally discordant orebodies occur within a strike width of 600 ft and an overall strike length of 1200 ft. They are enclosed by the steeply westdipping, west-facing sediments of the Cobar Group, and comprise lenticular steeply north-pitching and eastdipping zones of sulphide mineralization which range in composition from massive pyrite-sphalerite-pyrrhotitegalena to less massive pyrite-pyrrhotite-chalcopyrite varieties.The thinly bedded siltstones, shales, and greywackes enclosing the mineralization appear to have derived some of their constituents from volcanic sources. They have been metamorphosed to the greenschist facies of regional metamorphism. At least two stages of deformation and folding have occurred. The first stage folded the rocks on a south pitching fold axis into their present configuration, and superimposed a strong axial plane cleavage which subsequently guided the emplacement of the mineralization. The second stage of deformation is considered to have controlled the zonal distribution of the orebodies.

Jan 1, 1970

By D Wyatt, J Domenico, W Kow

Over the past few years developments in heavy minerals processing have concentrated on the mineral separation portion of the business. The best example of this would include new developments in rare-earth magnetic separators and associated flowsheet modifications. Except for some minor modifications in spirals, the æwetÆ side of the separation business has lagged behind the ædryÆ side. Basic concentrator design has not changed in 20 years. Recent pilot trials by Outokumpu Technology have shown the benefits of a new gravity flowsheet that combines density separation and spiral concentration on a variety of heavy mineral deposits. This concept is already well utilised within the iron ore industry. The synergistic combination of these two technologies allows smaller, simpler, and controllable gravity concentrators to be built while providing equivalent or better grade and recoveries of valuable heavy mineral. This is contrasted to the all spiral flowsheet characterised by the diminishing returns of multiple stages of spirals and associated recirculating loads. Examples of the flowsheets and associated benefits will be presented from a variety of cases.

Jan 1, 2001

By M J. Andrews, P J. White, I Bogie

Active geothermal systems occur widely in Sumatra and in the Taupo Volcanic Zone (TVZ) ofNew Zealand. There are also many occurrences of epithermal gold mineralisation in Sumatra, some of which are economic. Minor sub-economic occurrences of gold have been reported in the TVZ but none have yet been mined. There are both similarities and differences in the nature of the active geothermal systems and mineral deposits in Sumatra and New Zealand, which can be systematically related to the tectonic setting. The thicker crust and consequent predominance of silicic volcanism in New Zealand leads to hydrothermal systems which are little eroded and with limited lateral outflows. The systems in Sumatra are of mixed character, with some of the characteristics of those in andesitic island arcs such as Java or the Philippines, e.g. a higher proportion of systems with identifiable acid magmatic volatiles, a greater potential for deep erosion and lateral outflows than in New Zealand; but modified by the more oblique component of subduction and thickened crust so that some are localised in volcano-tectonic depressions and consequently have high piezometric levels of primary hydrothermal fluid. The unusual occurrence of calcic zeolites in veins associated with gold mineralisation in Sumatra is thought to be indicative of æsatelliteÆ boiling zones along de-gassed hydrothermal outflows.

Jan 1, 1995

Effects of DA as a Grinding Aid on Selective Grinding of Low-Grade Bauxite Effects of DA (a copolymer of acrylic acid and acrylamide) as a grinding aid on selective grinding of low-grade bauxite were investigated in this study. The addition of DA into the grinding system enhanced the selectivity of grinding and increased the A/S ratio in the coarse fraction of ground product, leading to improved throughput of grinding mills and alumina recovery. The results showed that DA decreased the viscosity of slurry significantly and hence improved grinding efficiency due to low viscosity at a high slurry concentration. Both the hydrogen bond formation and chemical adsorption existed between DA and the surface of bauxite particles. The adsorption of DA on the surface of bauxite could decrease stress needed for crack initiation and extending during grinding, prevent new-born crack surfaces from rejoining, and promote the expansion of the cracks.

Sep 13, 2010

THE flotation plant at Mount Lyell was erected, primarily, for the treatment of ore from the Lyell Comstock mine. These workings are situated over a mile in a direct line north of the North Mount Lyell mine, and are connected with the Reduction Work at Queenstown by a 2-ft. gauge steel tramway via the Queen River valley a distance of 7 miles. The property was purchased from the Mount Lyell Comstock Copper Co. After the disastrous fire in the North Mount Lyell mine in October, 1912, steps were immediately taken to make Lyell Comstock ore available for treatment, in order to relieve distress caused by any prolonged stoppage of work, and subsequently 13,032 tons of ore, averaging 3.38 %copper, 0.28 oz. silver, and 0.034 oz. gold; were smelted. When operations were resumed at the North Mount Lyell mine, it was evident that there was no economic advantage in smelting Lyell Comstock ore as compared with the higher value North Mount Lyell ore, which was also a better flux for the Mount Lyell pyrites, and that the future of the Lyell Comstock ore depended upon cheap mining and successful concentration of the ore. Therefore, extensive trenching and diamond-drilling was carried out, and a sufficiently large quantity of ore proved available for cheap extraction by open-cut methods. At the same time bulk tests by flotation were carried out at the Minerals Separation testing plant in Melbourne on different classes of ore from the Mount Lyell Comstock mine proper, followed by laboratory tests at Queenstown on all classes of ore available. All these tests demonstrated that the ore was amenable to the process, provided that it was ground finely enough. Plant erection was delayed by the general dislocation of business at the outbreak of war, but finally it became...

Jan 1, 1920

Inhibition of Bubble Coalescence by Salts and Sugars

Sep 13, 2010