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By Bennet A. G

As part of the construction of the Melbourne Underground Rail Loop it was necessary to construct two 7 metre diameter tunnels, each 100 metres in length, by shield driven excavation through an alluvial valley at Elizabeth Street. The tunnels had a primary support of bolted precast reinforced concrete liner blocks and were excavated with the aid of compressed air. The work was undertaken by the Tunnelling Group of the Melbourne and Metropolitan Board of Works as nominated sub-contractor to John Holland (Constructions) Pty. Ltd. The paper describes some of the problems associated with the construction of the above tunnels and the methods used to overcome them. In particular

Jan 1, 1981

By Nowell SB, Cottrill DA

Host-rock - wallrock major and trace element geochemistry associated with epithermal gold mineralisation in the Hauraki Goldfield of New Zealand is poorly documented, even though rock geochemistry is a recognised tool in exploration. Such responses assist in recognition of the regional scale imprint of fossil hydrothermal activity, and indicate targets for detailed evaluation within these alteration zones.Recent investigation of gold deposits in the Waihi (Gladstone), Golden Cross (Empire), Thames (Waiotahi) and Coromandel (Tokatea) areas indicate enrichments of Au, As and Sb in the andesitic wallrocks hosting mineralisation. Of the other elements examined, Si, K and Rb are enriched, and Na, Ca, and Sr are depleted at all deposits. These trends are best developed in the vicinity of veining. In deposits with clay alteration dominating (Waiotahi and Tokatea) there is also depletion of Mg, Mn, Zn and Cu. Ba and Cr are variably enriched or depleted within different styles of alteration. Base-metal enrichment in the wallrocks is not a feature of Hauraki deposits.

Jan 1, 1990

By Smith T. N, Wild M. B, Elliot B. J

The process of flash smelting of nickel sulphide ores, as practised at the Kalgoorlie Nickel Smelter, is described. The critical variables in the operation of this process are identified. The design of a pilot-scale, turbulent-jet flash reactor which models the essential features of the industrial smelter is described. A report of its operation and application to an investigation of the ignition of particles of sulphide species is given.

Jan 1, 1991

Felspar occurs in association with quartz in the Broken Hill lode pegmatites and is brilliant green, greenish white, and white in colour. The pegmatites occur mainly in the walls in sporadic patches, parallel to the general dip of the ore deposit. The occurrences are of no economic value.Deposits of marketable felspar occur in pegmatite in a number of localities around Broken Hill, New South Wales.The majority of these are in the form of an irregular outcrop, usually of tapering length and depth. The maximum depth of any deposit yet worked in the district is about 40 ft. The felspar is occasionally contaminated by "blows" of quartz, mica and beryl, but the two latter are profitably marketable when separated.Felspars vary in colour from pink, through grey to snow white, and the colour is not indicative of the mineral content. The largest deposit at present being worked is the Egebeck quarry, about 14 miles south of Cockburn. It is a prominent outcrop, roughly circular and about 150 ft. in diameter, covered by one to three feet of overburden.The felspar is mainly massive, but contains some cleavage planes at approximately 90°. Intrusions of quartz and mica occur in patches, but the deposit appears likely to improve in size, regularity and quality below the present working floor.COMMERCIAL USES.Commercial felspars are mainly used in the ceramic industry, for which a high-grade potash felspar is required.The dental industry requires limited amounts of soda felspar with a very low Fe20s content. The poorer grades...

Jan 1, 1946

By Richmond GD

The Hellyer concentrator of Aberfoyle Limited commenced production in 1989 processing a fine grained, massive sulphide ore containing Zn, Pb, Ag, Cu and Au as values. Four concentrates are produced - copper/silver, lead, zinc and bulk (Pb/Zn) - with overall payable recoveries (1991) of 80 per cent Zn, 55 per cent Pb, 50 per cent Ag, 30 per cent Cu and ten per cent Au. Metallurgical development work commenced immediately after plant commissioning, and continues. The flotation response and liberation analysis on a size basis highlighted reagent balance problems associated with tower mill regrinding of sphalerite, poor conditioning of flotation pulps, poor selectivity for fine galena, and insufficient liberation. These were the main causes of values lost to tailings, values reporting to the 'wrong' concentrates and of impurities in the concentrates. Modifications to tower mill regrind circuit operation, and the use of improved conditioning techniques have greatly improved concentrator performance, particularly in the finer (-5 micron) size fractions. Studies of concentrator and laboratory flotation by size and liberation analysis are the basis of diagnostic metallurgy. The techniques used to evaluate the improved concentrator performance are discussed.

Jan 1, 1993

By Marshall GA

Structural fatigue damage of haul truck frames is a costly problem associated with the operation of large mine haul trucks. A monitoring programme is described which has been instigated to measure stresses in the frames of haul trucks under actual mine operating conditions. The instrumentation used and methodology employed in the computer analysis of the results is briefly described. The results of the monitoring programmes are reviewed, and the effects of various factors affecting structural fatigue damage of three common types of rear dump truck are considered. Factors discussed include the effects of haul route features (for example shovel, dump and crusher areas); the effect of operations such as turning, braking, loading and dumping; the influence of payload; the effects of malfunctions in suspensions; and the influence of haul route surface quality. It is shown that with respect to payload, while structural fatigue damage is increased with payload, the structural damage per unit of payload does not change significantly for moderate increases in payload above the nominal value. Finally, on the basis of these results, recommendations are made for haul route design and operational practices which will increase the structural fatigue life of haul truck frames.

Jan 1, 1986

Optimisation of capital in the development process is critical to the profitability of any new mining venture. The process of optimisation should apply to all aspects, that is the financing, management, revenue, reporting and, of course, the development of the project. Unfortunately, too much emphasis has been placed on the optimisation of the financing or reporting aspects and too little on the project itself. This paper addresses the latter.

Jan 1, 1991

The transportable moisture limit of a mineral concentrate (TML) is of great importance in the shipping of that material from Australian ports. Each year Australian mining companies incur substantial costs as a consequence of delaying shipments and/or multi-handling concentrates so as to comply with transportable moisture limits. Despite this there is a general lack of in-depth knowledge concerning factors that influence the parameter. Eight major Australian mining companies supplied sizing, specific gravity and TML data for their concentrates. Zinc, lead, copper and bulk concentrates were represented in their data. Estimated surface areas of the concentrates, as calculated from their normalised sizing data, correlated strongly with the reported transportable moisture limits. This high correlation prevailed in spite of the acknowledged limitations associated with the use of multi-sourced data and the adoption of simplistic approaches in the normalisation of sizing data and the estimation of surface area. Based on the broad range of concentrates studied, concentrate sizing data were concluded to offer potential as an alternative means of reliably estimating transportable moisture limits.

Jan 1, 1993

During the 20th century, the iron ore mining industries of Canada and the United States passed through several periods of transformation. The beginning of the 21st century has seen yet another period of transformation, with the economic failure of a number of steel companies, the acquisition of their facilities by more viable steelmakers, and the consolidation of control within the North American iron ore industry. Changes in Canadian and United States iron ore production and the market control structure involved are analysed. The consolidation of ownership, formation of foreign joint ventures within North America, planned divestitures of upstream activities by steelmakers, and industry changes made to ensure availability of feedstocks will be reviewed. The traditional isolation of the Canadian and United States iron ore operations and their strong linkage to downstream steel production will be discussed in the context of a changing global economy. Management-labour conflicts that have taken place and agreements made during 2000 through 2004 will be discussed in the context of the economic environment leading up to these agreements. Cooperative agreements between competing Canadian and United States companies to resolve client needs in processing and blending will be examined. A joint industry-government project designed to use new technology to produce direct reduced iron nuggets of 96 - 98 per cent iron content using non-coking coals will also be assessed. Changes in iron ore transportation methods, ownership and infrastructure will be reviewed for both rail and inland waterway transport between Canadian and United States companies. A brief analysis of social and environmental issues relating to sustainable development of the Canadian-United States iron ore industry will be included.

Jan 1, 2005

By G Ride

The provision of a water supply is a major consideration in planning mining developments particularly in remote areas. The evaluation and development of adequate water supplies in arid areas of Australia is often as important as the discovery of the orebody. The copper orebody at Warrego near Tennant Creek could not be mined economically if cheap treatment water was not available near the mine. This paper describes the difficulties in obtaining water in the Tennant Creek area and the water supply investigations carried out near the Warrego Mine which resulted in the successful discovery and evaluation of a reliable large scale water supply. It is contended that the establishment of a water supply must be approached on a systematic and scientific basis similar to the approach with the exploration and establishment of actual ore reserves. Mining companies with similar water supply problems may benefit by approaching their problem on this basis. The approach adopted by Peko Mines is outlined in this report.

Jan 1, 1971

By G Newling

Zinifex Rosebery Mine is a lead-zinc underground mining operation located at the base of Mount Black, on the West Coast of Tasmania. Mining activities at the Rosebery Mine have been undertaken for over 100 years, and it has been operating in its current form for over 60 years. A large surface and underground exploration drilling program over the last 18 months has increased the mineÆs expected mine life from five to 12 years, with expectations that over the next 18 months as the program continues this will swell to 20 plus years. Zinifex Ltd secured Rosebery Mine in April 2004 and commissioned a detailed life-of-mine (LOM) study on all aspects of the operation. One of the most detailed sections of this report was on the state of the current ventilation system. It was identified in this report that for mining at the current depth of approximately 1100 m to continue a minimum 30 per cent increase in ventilation quantity was essential, as well as a likely requirement for a refrigerant cooling plant for each of the two deepest panels, the K and P lenses. It was identified that Zinifex did not have personnel with the expertise in underground refrigeration to manage and implement a project of this nature. A second report was commissioned with Bluhm Burton Engineering (BBE), a South African firm specialising in both surface and underground large-scale refrigeration plants. BBE concluded that two refrigeration plants were required to provide the necessary cooling power in the lower sections of the mine. In 2005, with BBE as technical consultants, Zinifex Rosebery Mine embarked on a project to commission two underground refrigeration units capable of lowering the wet bulb temperature at the decline face by four degrees centigrade. This paper is intended to give the reader an overview of: Rosebery Mine operations,Rosebery underground refrigeration project,technical difficulties associated with implementing an underground refrigeration system, andkey learnings to date.

Jan 1, 2008

Material hardness and environmental factors can limit or restrict conventional blasting techniques and this has led to advancements in the performance and efficiency of ripping. Not all materials can be ripped, however today's technology and experience can help make a reasonable prediction. A ripping versus blasting decision will depend on the total volume of material to be moved, the production capabilities and costs of the ripping tractor(s) and on the size and relative efficiency of drilling and Blasting.

Jan 1, 1995

By J van Niekerk

The BIOX« process for the treatment of refractory gold ores and concentrates has been commercially in operation for 18 years. A total of six BIOX« operations have been successfully commissioned since the commercialisation of the process. Four of these BIOX« plants are still in operation today. There has been a renewed interest in the process the past few years with two BIOX« plants, the Suzdal plant in Kazakhstan and the Fosterville plant in Australia, scheduled for commissioning during 2004. Four new projects are also in various stages of development and are currently scheduled to be commissioned during 2005 and 2006. Research into the process are currently focussed on the two highest operating cost items for the commercial operations, namely power for agitation and air dispersion and cyanide consumption during leaching. Laboratory aeration and agitation testwork using the A340 up-pumping agitation system has shown that similar mass transfer rates can be achieved at slightly higher agitator power. The up-pumping system, however, eliminates the need for a separate blower and sparger system as air is introduced into the slurry from the slurry surface. The use of the thermophile bacteria as the final oxidation step during biooxidation has shown great promise. Reductions in cyanide consumption of up to 50 per cent were achieved when using the combination mesophile and thermophile process compared to standard BIOX« product solids. The combined process takes advantage of the milder oxidising conditions of the well known BIOX« process for the bulk of the oxidation and then uses the high temperature thermophile bacteria to complete the oxidation. The ASTERÖ process for the biological degradation of cyanide and thiocyanate containing effluent solutions has been proven to be efficient and stable. The process uses an activated sludge system with a residence time of approximately six hours in the sludge reactor. Heavy metals and metal cyanide species have also been shown to be removed successfully from solution.

Jan 1, 2004

By Baohm C, Barker T

There have been significant changes in the Australian mineral sands industry in recent years due to changing supply and demand conditions, new product opportunities and opportunities for rationalisation of operations. Earnings within the industry have typically been volatile and this has been reflected in the share prices of listed mineral sands companies. Apart from the effects of variations in the state of the economy on the industry, share prices have also reflected the extent to which a company's earnings volatility is due to capital structure, the relative proportion of fixed costs to total costs and the nature of th'- sales mechanism. At the time of writing, the high prevailing share prices for industry participants and the current outlook for the industry would suggest that the time is opportune for raising equity capital. The immediate outlook for the industry and its various product segments appears favourable but beyond this the usual uncertainties remain. The new tax environment will cause most companies in the industry to have to rethink their dividend and capital structure policies. Most shareholders will now be concerned to maximize dividend receipts and minimise exposure to capital gains tax. Companies in the industry that have relied fairly strongly on earnings retention to help finance growth in the past will- need to look to increased equity raisings in the Future.

Jan 1, 1986

By Staunton W. P

The presence of cyanide soluble copper in gold ores can give rise to serious operational and economical difficulties in CIP and CIL operations. Cyanide consumption can result in the ore being uneconomic to treat by conventional means. Loading of copper onto carbon can also have deleterious effects on gold recovery and subsequent stripping and bullion recovery. The recovery of gold from high copper ores has been previously reviewed by Muir, LaBrooy and Cao (1989). Work undertaken for Mt Gibson Gold Project by Australian Mining Advisors with the assistance of the Chemistry Centre (WA) resulted in the patenting of a process and subsequent construction of a plant at Mt Gibson to overcome some of the difficulties encountered with copper. This paper discusses some of the work which was undertaken during laboratory investigations prior to commissioning of the plant and some further considerations for the treatment of high copper gold ores.

Jan 1, 1991

By Kellerwessel H, Oberheuser

Since its invention by Professor Klaus Schonert of the University of Clausthal, Germany, high pressure rolls comminution has attained near total acceptance as the preferred method of size reduction in the cement industry. Over 300 units have been manufactured worldwide. At locations where the system has been installed, considerable energy savings have been realised. These energy savings are generally in the range of 20 to 30 per cent compared to conventional ball mill circuits. However up to 50 per cent power saving has been achieved at some installations. This technology, with the exception of the diamond industry, has up to now had only limited success in ore processing. This has mainly been attributable to the abrasiveness of ores encountered in this industry leading to high wear rates. These high wear rates have given rise to an unacceptably short life time of the wear surface of the rolls, requiring regular replacement. A new wear surface has been developed which has shown to give a ten-fold increase in service life over conventional surfaces. This, together with developments made in machine design now give the units the ability to attain the high availabilities demanded by the mining industry, and therefore to allow this industry to achieve the considerable operating cost savings offered by the high pressure rolls.

Jan 1, 1992

By Yu AB, Azahari HL

Indonesia has the largest coal reserves in the south-east Asian region. According to estimates from the World Energy Confer- ence, it has reserves of 18 billion mt lignite, 4.4 billion mt sub-bituminous coal and 774 million mt bituminous coal (Wyllie,1988). In recent years, substitution of coal for oil in power plants has been the goal of the Indonesian government since proven deposits of coal are about five times as large as national hydrocarbon reserves and most of Indonesia's power stations are still oil fired. Recently a coal fired power plant has been built in Java Barat, which will have a full capacity of about 3000 MW. It is intended to supply coal for this power plant from Bukit Asam mining area (South Sumatra). Coals from Bukit Asam - which are of the lignite or brown coal type - usually contain considerable moisture . It should be noted that reference to moisture in coal pertains to the total moisture content. This is comprised of what is commonly termed as equilibrium moisture and surface moisture. Surface moisture typically affects combustion process as well as pulveriser performance since it possibly influences the relative ease with which coal may be ground. In practice, the surface moisture produces agglomeration of the fines in the pulverising zone and reduces pulveriser drying capacity because of the inability to remove the fines as quickly as they are produced. This agglomeration has also the same effect as coarse coal during the combustion process because the surface area available for the chemical reaction is reduced, hence the combustion efficiency is also reduced. The influence of the moisture of some coals on their grindability (Hardgrove Grindability Index) has been previously correlated by several authors; some of them will be mentioned later. Those correlations, however, could not be immediately applied to any coal since it is still believed that there are other factors which influence the grindability of the coal, such as type and rank of the coal. The relationship between coal moisture content and its grindability has been investigated by Ellmann and Belter (1955). It was found that, for North Dakota lignites, the grindability varied as the moisture content changed. In Britain, Fitton, Hughes and Hurley (1957) stated that, for Bilsthorpe coal, over a wide range of free moisture content (from air-dried to about 30 per cent moisture), the Hardgrove Grindability Index (HGI) remains virtually unchanged. In addition to that, it was suggested that it would be slightly advantageous to dry the coal below its air-dried moisture content (at temperature ¦ 100¦C) to increase the ease with which coal could be ground, especially for low-volatile coal and high-volatile non-caking coal. Furthermore, it was also concluded that a broad relationship appeared between coal rank and Grindability.

Jan 1, 1993

Copper refining electrolytes are maintained in the range 60-65¦C to ensure an efficient operation. The heat energy required to meet these temperatures has been traditionally derived from the electrical energy required for the electrolytic process and supplementary steam energy. In 1983, experiments were conducted at Copper Refineries Pty. Ltd. (CRL) to determine the effects of insulating the Tank House cells, and fully covering the cells. The results of these experiments showed conclusively that greatly reduced steam consumption would be required to maintain electrolyte temperatures. These positive results led to an Energy Conservation Programme for the Tank House, and this was implemented in 1984. A computerised cell cover monitoring system was developed, and is used to control cell coverage and fluid balance. The experimental work and the benefits obtained since implementation of the programme are discussed.

Jan 1, 1985

By Williams ID

Ore and coke of various size fractions (1 to 11 mm) were packed in a column (146 ó) and resistance to air flow measured under a range of conditions. Results have shown that layered charging results in an interface having essentially a directional structure the thickness of which is directly proportional to the coke and ore size ratio and whose flow resistance exceeds that of the coke layer many times its thickness. Friction factor - Reynolds number plots showed large positive departure from the Ergun equation for all components investigated whilst functional analysis and that in terms of bed constants, showed a strong dependency of the pressure gradient on bed properties and the actual particle size as well as the size ratio. It is also shown that pressure gradient in mixed beds follows previously reported behaviour and that a directional interface offers higher resistance to flow than a mixed interface having the same volumetric ore/coke ratio. Significance of results to practice is discussed.

Jan 1, 1975

By Vanderberg B

A 3D, PC based computer program is currently under development by Blasting Analysis International, Inc., to analyze the kinetics of full scale blasts with two or more high-speed motion picture cameras. Todays common approach of utilizing only a single camera system can, in some cases, lead to great errors and erroneous conclusions when motion is assumed to be in a predefined plane of motion. CMe phrase, "What you see is what you get, it no longer true in 3D."). This is especially true in blasting environments which exhibit complex and/or predominant structural geology. The 3D system eliminates this problem, and includes automatic corrections for vertical and horizontal camera optic axis orientation, dimensional controls, lens distortion, field set-ups, projection imaging and digitized inputs. The only information required is the surveyed or known coordinates of at least six non coplanar points in the field of view. Motitn from each camera view is then digitized, transformed through a direct linear transformation, and processed with the 3D software, which also automatically time matches the data, even when the high-speed cameras are operated at different speeds. Eleven calibration constants are generated using an overdetermined system of linear equations to output the true 3D coordinates of motion in the time domain. Applications for this 3D approach are not restricted to just analyzing the kinetics of a blast. The system is sufficiently flexible to allow an accurate, quick and economical method of bench face profile analysis, generate muck pile profiles and estimate volumetric calculations. The recording systems for these applications can be common 35mm still photography and/or video equipment. It is envisioned that this system will soon replace expensive laser surveying systems at a fraction of the cost in the near future. It is also an excellent system to accurately quantify drill pattern layouts and the spatial locations of each blasthole. This information is required for generating single hole based synthetic seismograms to accurately predict the vibrational outputs of full scale blasts. In terms of litigation concerning claims resulting from blast induced ground vibrations to structures, the system is proving to be an excellent and economical method of performing pre-blast surveys where differential settlement is suspect.

Jan 1, 1990