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The maximum current density at which conventional copper electrowinning plants will result in satisfactory, adherent, and dendrite·free cathodes is determined by the thickness of the diffusion boundary layer. A decrease in the value of that thickness will permit an increase in the current density. This fact is utilized to develop a high current density cell in which the reduction of the boundary layer thickness is accomplished by means of a specially designed electrolyte circulation system. The high current density cell is used to determine the effect of current density on such process parameters as current efficiency, cell voltage, power consumption, and cathode purity. A number of empirical equations are developed for the purpose of estimating the magnitude of these effects.

Jan 1, 1972

A study was made of zircon powders bonded with phosphoric acid or aluminium orthophosphate. The influence of strength of solution of the phosphatic binders on the modulus of rupture over a temperature range was investigated. Physical properties of three grades of zircon powder bonded with phosphatic binders were studied at various temperatures. Examination of x-ray diffraction data indicated that phosphates ofzirconia are preferentially formed to phosphates of silica. However, zircon in the presence of excess phosphoric acid also forms phosphates of silica upon heating.Resistance to attack by slags from blast and open hearth furnaces was determined on phosphate-bonded zircon mortars in a cup test with industrially made ladle bricks. Zircon powders bonded with phosphates proved to have high P.C.E. values. The first satisfactory results of a plant trial with phosphate-bonded zircon mortar, used in a steel ladle, are now being assessed in larger scale industrial tests prior to accepting the mortar as a steel plant refractory.

Jan 1, 1972

Geological hazards such as faulting, basement ridges, and zones of "thin" (< 6 m) coal have a major impact on mining economics of underground operations in Huntly Coalfield. Experience has shown that drillhole-based investigations do not yield sufficiently detailed models of the coal seam to allow management of the planning risks associated with these hazards. Consequently, operational performance is affected by unplanned costs associated with lower productivity, loss of coal reserves, and expensive strata control remedies in problem ground conditions. Huntly Coalfield is a challenging environment for acquisition of good quality seismic reflection data due to the very thick (10-85m) weathering layer. Since 1994, successful acquisition of 2D and 3D data has been achieved through a combination of careful testing of technical parameters and experimental trials prior to committing to production recording. High resolution seismic reflection (HRSR) is proving to be an investigations technique which generates accurate and reliable models of the coal seam and associated structures, such as normal faults and topography of the surface on which the coal seam rests. The HRSR technique has been applied and developed in the Okowhao Sector where Huntly East Mine is developing and extracting coal reserves. Results of a recent 3D survey demonstrate that this technique is capable of revolutionising risk management in mine planning for underground mines in structurally complicated coal deposits.

Jan 1, 1997

The need for the hydraulic transportation of coal in the New South Wales coal industry, both from the coal face to the surface and from the coal mine to the consumer or the port for export, is explained. Details of research projects currently in progress and involving the hydraulic transportation of New South Wales coals are given together with information on the hydraulic transportation of coal in the United States of America. The potential of hydraulic transportation as a viable alternative to the proposed expansion and upgrading of the New South Wales railway system to meet the projected New South Wales coal production to the year 2000 is described.

Jan 1, 1980

By G F. Brent, R D. Hart, C Carr, F Felipe

In underground operations, where copper, gold and other metals are mined, the open stopes can be backfilled to stabilise surrounding workings. This fill may consist of tailings from the processing plant, usually mixed in slurry with a binder such as ordinary Portland cement (OPC). Extensive use is made of tailings in OPC-based paste fill, cemented hydraulic fill or cemented aggregate fill applications. A large underground operation such as the Mount Isa Copper Operations utilises over three million tonnes of backfill per annum. Geopolymers offer an alternative binder system with significant environmental advantages over OPC. Geopolymers are formed by polymerisation of aluminosilicate precursors in an alkali medium. They generally form products with superior strength characteristics as well as increased resistance to degradation, particularly under acidic conditions. Geopolymers have lower carbon dioxide emissions associated with their manufacture than OPC and offer further potential advantages, such as the use of less water and more waste materials. The application of geopolymers to weak material systems such as mine backfill has not been widely studied. The aims of this investigation were to assess a range of Australian mine process wastes for suitability as feedstocks in fill applications and to construct a range of these cemented minefills using a geopolymer binder. The physicochemical characteristics of each of the wastes are discussed as well as how they ultimately contribute to the geopolymer cement through direct replacement of OPC. Results from various tests on the candidate geopolymer fill formulations are presented and the potential of such fill formulations to replace OPC in mine backfilling operations is highlighted. The significant potential contribution to reducing greenhouse gas emissions from the use of geopolymer-based mine backfill across the industry is noted. Conversion of a single mine, such as the Mount Isa Copper Operations, is shown to match the reductions in greenhouse gas emissions due to the current total installed photovoltaic electricity generation capacity of Australia. A similar examination of wastes available to a gold mine could potentially yield new binders for use in established or new fill systems.

Jan 1, 2007

The sulphide ores of the principal lodes of the Boulder Mines are mainly composed of a schistose guess with a varying proportion of silica and lime, containing tellurides of gold, silver and mercury, associated with iron pyrites. It is a great difficultyto obtain pure and homogeneous samples of the tellurides for analysis, and from a number of tests made with excellent specimens it was found hardly possible to procure two to agree in analysis, the precious metals being found to be combinedwith tellurium in most varying proportions indeed, a close inspection of a partially crushed specimen will reveal, even to the naked eye, the various shades of colour characteristic...

Jan 1, 1901

By C Bailey, T Kojovic, M M. Hilden, M S. Powell

The Julius Kruttschnitt semi-autogenous grinding (SAG) mill model was developed by Leung in the 1980s and extensively updated to the variable rates model by Morrell and Morrison in 1996. Since then only minor upgrades have been incorporated in the version distributed in the JKSimMet simulator. A number of improvements, developed over the course of the AMIRA P9 project and in recent independent work, have now been incorporated. These improvements are based on a power-based model that directly relates the degree of breakage with energy consumption. The new size-dependent breakage function has been incorporated. The upgrades include more accurate predictions for a wide range of mill fillings (ten - 40 per cent), slurry hold-up in the mill, pebble discharge rate and the influence of changes in feed size and ball load.The paper presents the status of progress in the model development. The upgraded model will greatly enhance its application to challenging design and optimisation studies required to optimise the performance of SAG milling circuits.CITATION:Kojovic, T, Hilden, M M, Powell, M S and Bailey, C, 2012. Updated Julius Kruttschnitt semi-autogenous grinding mill model, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 71-80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

The large increase in secondary industries in this country, during the war and post war periods, has caused a shortage of capacity for the production of merchant bar.To overcome this shortage, an expansion of rolling mill facilities has been undertaken by the Broken Hill Pty. Co. Ltd. A small, but modern, merchant mill has been erected at Kwinana in Western Australia and a strip and skelp mill is under construction at Newcastle. The latter mill will roll strip and skelp at present being rolled by the Newcastle 10 in. Merchant Mill, enahling this mill to concentrate on merchant bar production.The Kwinana mill was installed to supply the Western Australian market. This state has a small population (approximately 658,000) and is not at present highly industrialised. It was necessary, therefore, to design a mill which would be capable of producing a wide diversity of sections and could be expanded as the demand increased. To begin with capital expenditure had to be kept within reasonable bounds. The design work for this mill, with the exception of a few specialised items of equipment, was carried out at Newcastle.All design work for the Newcastle mill was carried out by the lVIorgan Construction Co. of America. Although initially intended for rolling flat. products, the designers were asked to make the mill as flexible as possible, so that should the market for flat products decrease, this mill with additional equipment could undertake the rolling of medium sized sections.

Jan 1, 1957

By S van der Sluijs, M van Ende, Y Tang, A Emami

This paper presents a phenomena-based model for investigating the possibility of scrap melting in an Open Slag Bath Furnace (OSBF) for green ironmaking. The goal of this study is to enhance the circularity of the steelmaking process by utilising scrap as a green source of iron in OSBFs. The model takes into account the fundamental differences between OSBFs and traditional processes such as Electric Arc Furnaces (EAFs) and Basic Oxygen Furnaces (BOFs). The model considers three primary regions where scrap heating and melting occur: the solid feed pile, slag and hot metal. It accounts for factors such as the furnace geometry, scrap charging mechanism and specific heat and mass transfer properties of the reactor. The model was validated using literature data and was used to investigate the heating and melting behaviour of individual scrap particles under various process parameters. The study finds that the scrap melting process in OSBFs involves three stages: shell formation, shell remelting and subsequent melting of the parent scrap. The carbon content of the scrap and the liquid hot metal plays a critical role in determining the melting behaviour. Depending on the carbon concentration and temperature, the melting process can be heat transfer controlled or mass transfer controlled. The paper also examines the scrap feeding methods in OSBFs, including direct charging into the slag or charging through a feed pile. The model provides insights into the melting rate of scrap compared to Direct Reduced Iron (DRI) in OSBFs and highlights the role of carbon in this process. Overall, this phenomena-based model contributes to the understanding of scrap melting behaviour in OSBFs and provides valuable insights for optimising the circularity and efficiency of green ironmaking processes. The findings of this study can inform the design and operation of OSBFs, paving the way for increased utilisation of scrap as a sustainable feedstock in the steel industry.

Jun 19, 2024

By J T. Woodcock, G J. Sparrow

A sample of pyrrhotite flotation concentrate pulp assaying 15.3 g/t Au, which had been prepared from an old tailing dump, was treated to extract the gold. Examination of the concentrate with an SEM showed that exposed or free native gold, 5- 40 ¦m in diameter, was present but no locked gold was observed. Direct cyanidation of the concentrate to extract the gold showed that the flotation reagents present inhibited gold extraction. A range of pre-treatments was used to overcome these effects. Direct cyanidation for 48 h extracted only 26 per cent of the gold, indicating possible contamination of the gold in the concentrate with flotation reagents. Pre-treatment of the concentrate pulp by aeration for 24 h, or by 72 h aeration with an addition of 3.65 kg/t of sodium sulphite, gave little improvement in gold extraction by subsequent cyanidation. Pre-treatment by filtration, or by aeration with 12.5 L/t 100 volume hydrogen peroxide, followed by cyanidation for 48 h gave gold extractions in the range 67-77 per cent. Combining filtration and an aeration period with hydrogen peroxide addition raised the subsequent cyanidation extraction of gold to 88 per cent, giving a tailing assaying 1.5 g/t Au. Re-cyanidation of some of the dried tailings from the initial tests extracted most of the remaining gold giving a tailing assaying 0.5 g/t Au. This indicated that most of the gold was available for dissolution by cyanide. The poor dissolution of gold by cyanidation of the untreated concentrate was attributed to the presence of flotation reagents. It was shown by UV spectrometry that xanthate-containing compounds were present in the solids fraction of the original pulp and that they were partly removed by pre-treatment. MIBC was also present, and dithiophosphate, which was used in the flotation step, was also probably present. The results indicated that the improvement in gold extraction after filtration and oxidation of the original pulp was due to partial removal of the flotation reagents, and illustrates the detrimental effects that residual flotation reagents can have on the extraction of gold by cyanidation of a flotation concentration.

Jan 1, 1990

By Lynch A. J

Comminution within rod mills has been investigated by use of a matrix analysis of breakage processes. A parameter, the number of breakage stages, has been introduced and comminution within all rod mills has been expressed in terms of the number of grinding stages and a function which describes the feed rate, mill diameter, and mill speed. The effect of variation in feed rate, feed sizing analysis and mill speed on the number of breakage stages is discussed, but no general relation is proposed because more study is needed.INTRODUCTIONRod mills are normally used as the first unit of multi-unit systems for the grinding of metalliferous ores and the cost of operating rod mills may be considerable. For both economic and metallurgical reasons, it is therefore necessary that the mills should be operated efficiently and that a knowledge of the mechanism of the size reduction process within rod mills should be as complete as possible. While a qualitative assessment of the process may be of some value, a quantitative assessment gained by describing the process in mathematical terms can be of much greater use because it may also be used for design and control purposes.In this paper, an empirical mathematical model is postulated to describe the size reduction process within rod mills and it is used to analyse the effects of variations in both rates and size distributions of the feed to the mills.GRINDING CHARACTERISTICS OF ROD MILLSMyers (1953) discussed the grinding characteristics of rod mills and suggested that a pronounced screening effect, resulting in the preferential grinding of the coarser particles, occurs within the mills. This is illustrated in...

Jan 1, 1964

By Colwell J. B, Constantine A. E

A unique, regional grid of deep (12 - 14 second record length), seismic reflection and refraction data has been recorded by the Australian Bureau of Mineral Resources (BMR) across the offshore Gippsland Basin and parts of the adjacent Bass Basin, in southeastern Australia. These data have been combined with onshore mapping to produce a new model for the development of the Gippsland and adjacent Bass Strait basins. Overall, the Gippsland Basin contains up to 12 - 14 km of sediment in an ESE-trending depocentre bounded on its north and northwestern margins by a detachment ramp, and on its southern side by a relatively linear, listric fault system. The basin, together with the adjacent Bass and Otway Basins, appears to have formed as part of a linked, largely- strike-slip to 'transtensional' system, which started to extend through Bass Strait, probably during the latest Jurassic. Each of the basins developed by movement on a common detachment or detachment complex, which produced headwall extension at their western ends, in the areas now occupied by the Strzelecki Ranges, Otway Ranges - Torquay Sub-basin, and Robe Trough. Adjustments and reactivation from the mid Cretaceous of several postulated microplates in the region, largely in response to Tasman Basin rifting, gave rise to the wrench-related and compressional structures which form the major petroleum targets in the Gippsland Basin. However, the same process formed largely extensional stuctures in the Bass Basin. Our interpretation of the tectonic history of the Gippsland Basin leads us to the conclusion that there may have been several phases of petroleum generation and migration, and that potential petroleum traps appear to exist in the deeper section, in structures sometimes not reflected at the top or near-top Latrobe Group levels.

Jan 1, 1992

By Bain J. H

Since zinc was first deposited at Risdon in February, 1917, provision of the most economical cathode assembly has been a subject of extensive research, the major problems being corrosion and efficient use of power.From the corrosion viewpoint, a perfect cathode is one in which the life of the headbar and the deposition sheet are the same. However, corrosion usually concentrates in a narrow zone across the face- of the sheet, resulting in breakages which, before the advent of argon arc welding, meant a loss of a 'complete assembly.Attempts to extend sheet life included use of thicker sheets, multitudinous protective coatings applied with varying degrees of success, re-rolling, and for a time, aluminium consumption was reduced when broken sheets found re-use as protecting strips. This latter economy became impracticable when electrode spacing was reduced for greater efficiency in power utilization.As an integral part of the electrode, the headbar was modified accordingly. Copper headbars, although more corrosion resistant, were replaced by aluminium due to a possibility of dissolved, copper promoting deterioration.Thicker electrodes and regulated spacing reduced internal shorting, whilst provision of knife-edge type supports on both contact and insulator ends of headbars aided in electrode centralising and continuous electrical conduction.After much experimeIitation, an assembly has been evolved which, with the aid of argon arc welding and tbe use of minimum additional aluminium, permits comparable headbar and sheet lives, combined with good electrical conduction throughout the life of the cathode.INTRODUCTION Over 300 tons of zinc are produced daily at Risdon from a purified zinc sulphate solution by electrolysis, the zinc being deposited upon all-aluminium (except for copper contact) cathodes. It is stripped in 72-hour cycles from the cathodes, melted and cast into the customary rectangular slabs.

Jan 1, 1958

By M Passmore, N Poznik

Olympic Dam is a world-class deposit and is unquestionably one of the most geologically, structurally and texturally complex orebodies in the world. As development advances into the Southern Mine Area (SMA) the geological understanding is rapidly evolving as underground drill rigs are prioritised to provide the additional data necessary to convert Indicated and Inferred Resources into Measured Resources. The SMA represents approximately 70 per cent of Olympic Dam’s total resource and is significantly more complex when compared to the Northern Mine Area with respect to the diverse nature and origin of lithotypes, rock mass characteristics and the extent of major structures controlling primary mineralisation trends.Recent mine development into the central SMA has been impacted by a major structural gouge zone. Sound geological interpretation allowed mine geologists to successfully integrate their local understanding of the distribution of lithotypes with critical geotechnical data, chiefly rock quality designation (RQD), to delineate and better predict this major structural gouge zone. As a direct result, development rates improved whilst also increasing awareness for the importance of sound geological interpretation utilising all available data. In order to maximise predictability across all systems in place through the mining geology value chain, the integration of geological and geotechnical data in a geotechnical RQD block model provides an additional tool to assist in preventative solutions for complex problems to achieve a proactive mining environment.This paper details the methods used to build the RQD block model, the geostatistical estimation parameters, 3D geotechnical domain wireframes, challenges regarding legacy approaches, and collection of geotechnical information and incorporating/linking geotechnical data with geological features, including the use of grade and lithotype domains. Although the geotechnical block model proved difficult and complex to construct, the resultant product has seen successful integration of geological and geotechnical data into mine planning providing higher resolution of critical parameters for local mining areas.CITATION:Clark, J M, Passmore, M and Poznik, N, 2017. Olympic Dam rock quality designation model – an integrated approach, in Proceedings Tenth International Mining Geology Conference 2017, pp 27–36 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

IN the construction of a set of ordinary mine plans, two axes or coordinates are used; also, two different projections are essential viz., a plan (horizontal projection) and longitudinal section (vertical projection). In isometric projection three axes are employed-one axis vertical and the remaining two inclined to it at angles of 120°, also making an angle of 120° with one another, as shown in Fig. 1. The two inclined axes are used to plot the horizontal projection, while altitudes are plotted on the vertical axis. As an illustration, consider the ease of a simple object, such as a box. To show all the dimensions in the usual manner requires two drawings-a plan and elevation, as in Fig 2.

Jan 1, 1919

By Everson P. T, Moyle F. J

Magnesite-rich and dolomite-rich ores from the Savage River region of Tasmania are being considered as potential feed material for a commercial process for production of magnesia.Two selected samples have been characterized by chemical analysis, X-ray diffraction, and differential thermal and thermogravimetric analysis. The materials differ in calcination behaviour, with magnesite decomposing at a significantly lower temperature than dolomite. Calcination conditions have a marked effect on the rate and percentage of magnesium dissolved as the bicarbonate when slurries of the calcine are leached with carbon dioxide. From a process point of view, the feed should have the highest possible magnesite/dolomite ratio, while the optimum calcination conditions are determined by the behaviour of the magnesite component of the feed.From batch calcination tests, it is apparent that the optimum calcination conditions for magnesite-rich ore are a temperature in the vicinity of 700°C and a calcination time of one hour.

Jan 1, 1981

By D Vickers, N C. Fowke

The reduction of geological risk for planning of high production longwall faces is essential. Geological and geophysical techniques applied at Huntly West Mine before 1989 were unable to reduce the geological risk to an acceptable level. The success of a trial long-hole directional drilling programme at Huntly West Mine (Fowke et al, 1989) has encouraged the Coal Corporation of New Zealand to use the technology long-term, for seam definition. Initial drilling in 1989 completed a total of 3543 metres, with the longest borehole length being 369 metres (limited by number of rods available). A major re-interpretation of seam structure resulted from the drilling, which was able to fill in seam details between surface exploration boreholes. The undulating thick seam conditions at the mine require a refinement of drilling strategies used overseas. Long-hole directional drilling also displays potential for inseam gas drainage. Gas flows of the order of 1000 L/min were initially indicated in individual boreholes. Other gas parameters of the seam have been studied by Beamish et al (1991), and highlight the significance of the natural gas resource in the Huntly Coalfield.   The continued development of drilling technology will be of major benefit sustainable development, particularly in policy.

Jan 1, 1991

By P J. White, J V. Lawless

Low-sulphidation epithermal gold deposits, which form in quasi-hydrostatic convective hydrothermal systems, frequently contain chalcedony within high-grade ore, which has been interpreted to be a crystallisation product of amorphous silica. To deposit amorphous silica rather than another silica polymorph at elevated temperatures requires very high silica concentrations, because of its relatively high solubility. Only extreme boiling caused by decompression followed by wall rock heating upon structural dilation, can achieve this. As gold deposits with amorphous silica it must be produced by the same mechanism, particularly since extreme boiling is also a very effective mechanism for gold deposition. Recent developments support this view; the first is the detailed isotopic analysis of chalcedony-bearing high-grade veins reported from Hishikari, Japan, in which oxygen isotope results are indicative of extreme boiling and hydrogen isotopes indicate initial deposition of amorphous silica. The second is the finding of chalcedony within geothermal pipe work in the Rotokawa geothermal field in New Zealand. Rotokawa is a comparatively hot field (335¦C at depth); hence separation of the steam-water mixture produced by the wells is undertaken at a comparatively high temperature (220¦C) to minimise down-stream silica scaling. Even so, silica scale, some of which is chalcedony, does occur, under similar conditions to that in low-sulphidation epithermal deposits. Evidence of chalcedony forming under these conditions, reinforces the interpretation that decompressive boiling is the main deposition mechanism for gold in low-sulphidation epithermal deposits. It is possible that there is sufficient drop in temperature due to decompression that, at least initially, the silica deposits directly as chalcedony. Low-sulphidation epithermal gold deposits that do not contain chalcedony, such as those in the Philippines, may form at temperatures too high for chalcedony to directly form. The recognition of decompressive boiling as the main deposition mechanism in low-sulphidation epithermal deposits means that exploration can focus on zones where this has taken place by combining paleohydrological reconstruction and structural geology.

Jan 1, 2002

By Sneddon N

In November, 1975, Aberdare North colliery was sealed at the surface to extinguish an open fire underground.The fire had developed from a spontaneous heating in one of the open goaf areas of the mine.The mine was re-entered with normal ventilation methods following the isolation of the working district containing the fire. The isolation was accomplished by remotely sealing the open roadways with lly ash emplaced through boreholes from the surface. A subsequent re-entry operation similarly closed the roadways close to the fire and enabled the re-opening of the sealed district.Most of the mine and the underground equipment was recovered after clearing of numerous falls and production recommenced on 25th October, 1976.

Jan 1, 1978

This paper reviews the development and operation of a small underground tin mine in NE Tasmania. Tin mineralisation was discovered in the Lottah area in the 1880s with early alluvial and eluvial workings leading to the development of large low grade open pit operations. Apart from short lived activities operations ceased in 1915. Intensive exploration in 1978 - 1981 outlined substantial tonnages of low grade tin mineralisation (0.2% Sn) of open pit material. An underground ore body was also located (800 000 tonnes 0.6 per cent Sn). Spectrum Resources Australia Pty Limited acquired a 98 per cent interest in the property in 1988. Mine and mill development began in early 1989 based on an underground mine utilising trackless mining using room and pillar with fill stoping. The milling circuit involves primary jaw crushing, Barmac secondary crushing to 1 mm, Mogensen and DSM screens with jigs and tables to make a wet concentrate. Final tin concentrates are produced by high tension and magnetic separation. Planned production rates are 500 t/day with a mine life of six to seven years.

Jan 1, 1990