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By M Rankin, F Medina, R Verburg

We conducted a preliminary assessment of an extensive deposit of historic tailings discharged over a period of 40 years to the shoreline along a Southern Peruvian coastline. The tailings formed an extensive beach approximately 2.4 km long and 300 m wide. The tailings consist principally of pyrite (37 to 59 per cent), hematite (nine to 20 per cent), magnetite (three to 13 per cent) and quartz (11 to 36 per cent). The present operating company was required to evaluate the feasibility of capping the ocean side tailings deposit, however, given the size of the undertaking and the potential to reclaim residual minerals from the tailings, it was prudent to first evaluate whether capping would in fact reduce the impacts to the marine environment. Therefore this preliminary assessment examined: 1. metals contamination in tailings, shoreline porewater and marine sediments; 2. reactivity of tailings and acid generation potential; and 3. the potential for biological effects from metal contamination in the uplands tailings (solid phase) and beach porewater. Based on mineralogy, column leach studies and chemical results, the upland tailings have a high geochemical potential to acidify and release metals, especially copper, nickel and zinc, should they be subject to oxygenated and aqueous conditions. But, the extreme arid climate results in very low potential for precipitation and virtually precludes the transport of acid drainage reaction products from the upland tailings towards ocean. Wind erosion caused by offshore winds is likely a small source of tailing transport to the ocean. Since some potential exists to reprocess the tailings in the future, capping does not seem justified at present.

Jan 1, 2003

By W D. Ortlepp

Seismicity associated with deep block cave mining operations in hard rock can give rise to dynamic loading of the mining openings. A description is given of the source and damage mechanisms associated with such seismic events, and the possible demands placed on the rock support by the resulting dynamic loading. In addition, production level drifts are often subjected to large static deformations during mining. Appropriate support, able to sustain large static deformations, and capable of absorbing the energy released during dynamic loading, is described. The performance of these support types has been determined by means of large-scale dynamic loading tests, and large deformation static laboratory tests. Finally, a support system which is considered to be appropriate for extraction drifts in block cave layouts subjected to dynamic loading is described.

Jan 1, 2000

By R Brake

The Enterprise Mine Project (EMP) is being developed by Mount IsaMines Limited as the future source of copper ore at the Mt Isa miningand processing complex. Environmental engineering is one of the majortechnical challenges facing the project because of the depth of theorebodies, high virgin rock temperatures and hot ambient surfacetemperatures in summer. This paper discusses the engineering principles adopted by EMP to manage the risks associated with working in these adverse thermal conditions.

Jan 1, 1998

By Olden WH

A scheme is presented whereby the complexities of design and operation of a hydraulically powered coalmine support are modelled using the finite element method. This enables predictions to be made of the interaction of the support with its environment in a variety of operating conditions. The model is a two dimensional representation. The modelling scheme was applied in two case studies. In the first, the performance of a four leg support was uprated by increasing the front leg force. The finite element model enabled changes in overall support performance to be verified. In the second case study, the change in lateral force developed by a two leg support was assessed with changes in support operating height and floor foundation stiffness. The modelling scheme is capable of further development with the possibility of extending the model into three dimensions and the addition of control elements that would enable an actual mining sequence to be Represented.

Jan 1, 1992

This paper reviews an analytical model that defines the relationship of weight-weighted or volume-weighted average haulage distance with bench height and other related parameters; presents the optimum bench heights under various conditions in terms of minimising the weighted average haulage distance of ore/waste during the full lifetime of an open pit mine, and discusses the truck-haulage economics of mining open pits by high bench, specifically by 15 m, 18 m and 20 m bench through marginal analysis. The observations from these analyses disprove the previous conflicting assertions that the overall weighted average haulage distance either increases or decreases monotonically with bench height. It is concluded that: (i) an increase of bench height to 15 m from 12 m is likely to be viable under the general conditions of large-scale deep open-pit mines; (ii) the reduction of haulage cost is limited with the case of increasing bench height to 18 m from 15 m; and (iii) the feasibility of mining open pits by 20 m benches is generally questionable. These conclusions may serve as a useful guide for those who advocate open pit mining by high benches.

Jan 1, 1995

By A Garg

Squeezing can occur both in hard rock and in jointed rock mass as a result of over stressing. It is related to time dependent shearing, ie shear creep and is associated with the volumetric expansion (dilation) and radial inward displacement of the tunnel surface. While planning a tunnel in hard rock under a high cover of the order of 2 km it is desirable to identify the potential squeezing ground conditions and to select appropriate excavation technique and the support measures. There are several solutions to counter balance the squeezing ground viz over excavation of tunnel profile, assessing appropriate excavation technique, provision of a ductile primary support and time for providing tunnel lining. Low drivage rates and high cost due to support failures requiring rectification arising out of poor anticipation of tunnel closures and support pressures are major problems associated with tunnelling under squeezing ground conditions. Under squeezing ground conditions, the deformation will be gradual, therefore, in order to absorb deformations yielding supports are quite useful as primary support which provide a reliable low initial support pressure and permit uniform stress relief of the surrounding rock along with preventing rock from ravelling. The paper discusses the various factors which influence the selection of appropriate excavation technique and support measures in hard rock under squeezing ground conditions.

Jan 1, 1999

By Moxon NT, Torrace AC

The detonation pressure of an explosive is a function of its density and its velocity of detonation (VOD) and relates directly to the degree and manner in which the explosive loads the surrounding rock. The suitabil- ity of an explosive to any particular situation is determined not so much by the total energy released but more by the rate at which it is released. As the science of rock blasting advances it is becoming economically more important to quantify explosive performance, particularly with respect to quality control and fragmentation. As part of a major explosive user, BHP Central Research Laboratories have developed a number of tech- niques to determine the detonation characteristics of explosives. These include a method of continuous velocity of detonation measurement based on the SLIFER principle. This not only enables the VOD of the explo- sive to be determined, but also has the versatility to allow factors such as under priming, slow run up, the effect of water, variable energy load- ing and the velocity of the shock wave in the stemming to be assessed. Multi point VOD systems have also been developed for more routine appli- cations. With a minor modification they can be used to determine the absolute delay of detonators accurately and economically. Direct deto- nation pressure measurement methods have also been developed based on piezoresistive techniques. Future developments include the incorpo- ration of all the above techniques into a single, portable package, allow- ing easy use on the mine site.

Jan 1, 1988

There was a time, in the memory of some here tonight, when the annual meeting of The Institute was a nostalgic occasion. Often, in the 1920s, there was comment on the decline of Australian mining and on the lack of new mineral discoveries. When some of our Presidents prayed then for a new Bendigo, and instead were given a Mount Isa, they were justifiably disappointed because of the vastly different capital requirements.In 1967 the mining picture is very different. The recent mining developments in Australia are certainly as important as several Bendigos and several Kalgoorlies. The mining industry in Australia has never been more dynamic than today (Table 1). And if we ask why it is so dynamic, the answer lies in the role which overseas capital is playing in the industry. The contribution of overseas capital should concern us not only because we are members of the mining and metallurgical profession, but also because we have a duty to make our profession contribute as much as possible to the well-being of Australians. It is not sufficient to argue that overseas capital is good for the mining industry; we must also examine whether it is good for the economy and the nation. In this context the current criticism of the inflow of overseas capital into Australian mining is useful, for it gives us an opportunity to see what has resulted from the inflow.In discussing this question I do not suggest that we emulate Captain Hancock, that legendary Moonta mine manager who, according to Oswald Pryor's cartoon, used to say to his miners: "When I say a thing is, it is, even if it isn't". The question can only be discussed on a factual basis; and I would submit that many of the important facts relating to overseas capital in our mining industry are often overlooked or ignored. I would further submit, on the basis of these facts, that Australia's present day mining industry has been largely built on overseas capital and that the overall benefits of that capital to Australia have been enormous.

Jan 1, 1967

By D Reid, A Fourie, J Ayala

This paper discusses cone penetration test correlations for loose gold tailings that were developed within a critical state soil mechanics framework. The development of a new calibration chamber for cone penetration testing that consists of a modified triaxial cell is described. Some of the early development and commissioning issues that were encountered, as well as the solutions adopted are outlined, including the system to prepare the samples and to acquire high-quality data from the testing. Also, the triaxial laboratory testing required to achieve the critical state line is described, including some of the basic precautions considered necessary as good practice. Additionally, the system adopted for volume tracking of the calibration chamber sample is described, which is essential for ensuring a reliable state parameter comparison against the acquired cone penetration test data. Finally, some laboratory test data from the calibration chamber is plotted against the soil behaviour type charts currently available from various authors.

Jul 1, 2021

By Brook W. H

The history of the reduction of iron from its ores is lost in antiquity. Archreologists state that man has practised it for over four thousand years. Until comparatively recent times charcoal was the principal reducing agent for making metallic iron from its various oxidised ores. Coke was first used by iron founders in England in 1619, and its use spread gradually throughout the civilised world from then onwards. Indeed, the destruction of forests to obtain the requisite charcoal made the iron founders, both in England and America, extremely unpopular, and this hampered the iron industry to a considerable extent, until coal provided the metallurgist with a new and better fuel--coke which is used by most pyro-metallurgists today. The transition from wood to coal products for iron smelting had a profound effect on the location of iron works. Particularly was this the case in America where, in the infancy of the industry, practically each of the early States had its own iron producers, but as coal and coke replaced charcoal, there came about a concentration of the iron and steel industry around the coking coal deposits, and so today there are huge steel plants clustered around the soft coal basins in Pennsylvania and Illinois.The development of the iron and steel industry in Australia, which is comparatively recent by world standards, has been cradled in the coal basins of New South Wales. The first steel works of any consequence in this country were built near Lithgow, close by the mines which produced the coal for coking.Incidentally, these works were rather unique in that the three essential materials for iron and steel manufacture-ore, coal, and limestone-were found virtually at the works' back door.When, in 1912, the location of the proposed steel works for The Broken Hill Pty. Co. Ltd. for smelting ore from Iron Knob in South Australia was considered, the site ultimately chosen was at Newcastle, almost on top of seams of satisfactory coking coal. One of the major factors which had determined the site of the steel works was the fact that, about 1912, three tons of coal were required to produce one ton of finished steel product, and the relative economics of ore and coal haulage were much in favour of bringing ore to the coal.

Jan 1, 1947

By B Shen

The Wambo Rail Spur located near Singleton, New South Wales, Australia, runs for approximately 14 km linking the Mt Thorley rail loop and the Wambo Coal Mine. The project involves a 260 m long tunnel in weathered sedimentary and intrusive materials. The tunnel has a low cover and runs under a main highway. This second paper on the project looks into one aspect of the tunnel in detail: the use of shotcrete arch as the primary support for part of the tunnel excavation. The use of shotcrete instead of steel arch, formulation of the material specification, construction sequencing, installation at the excavated face and material testing for verification related to this facet of the project will be discussed in this paper. The tunnel opened in April 2006, and two years on, we briefly reflect on the impact of this design decision on the overall project.

Jan 1, 2008

A new least-squares method for inversion of d.c. resistivity soundings from horizontally layered earth is proposed. Powers are used as measured data. Apparent resistivity is generalized and apparent parameters curves are defined. Estimates for parameter errors are often possible even when data errors are unknown or large. Acceptance or rejection of a model is made an easier decision. Total computational effort is often reduced when compared to global least-squares methods, because although several optimizations are needed, few data points are involved in each, and initial guesses are requested only once and not all at the same time. Correlations between parameters may be used to improve solutions. Precise indications for extra needed data points can be conveyed. A test example is worked out and a field sounding, taken by Rijo (1973, personal communication) in an alluvium-filled river valley in north-eastern Brazil, is studied.

Jan 1, 1987

During the 1998/99 Asian crisis Solid Energy's export revenues collapsed from over US$70M to under US$40M. Simultaneously, domestic market uncertainty led to decreases in volumes and prices. A major new underground mine was not technically viable, and was closed, and several other mines were marginal. Less than two years later, Solid Energy and its JV partner closed a second new underground mine. The company was in financial crisis, and reported an $86M loss for 1998/99. After refinancing with stringent workout conditions it still had minimal returns due to low prices, unaffordable transportation costs and huge unrealised FX losses as the NZ dollar fell 40 per cent in value. The obvious scenario was to æcash upÆ û complete extraction at remaining mines, sell off any viable parts of the business, pay off debt and wind the company down.In 2002 Solid Energy has completed its recovery. Although margins remain slim and volatile in both export and domestic markets, it is achieving record volumes and revenues. It has paid off its shareholder loan, has minimal remaining FX losses, and cashflow is allowing further mine and infrastructure development. The key to the turnaround has been implementation of rigorous planning, analysis and decision-making in all aspects of the business. The company has a comprehensive, rolling 20-year plan used annually to update rolling five year and annual business plans. Solid Energy augments strong line management operations with rigorous standards and processes for mine planning and development, operational decision-making, and functional support. Detailed, quantitative risk analysis is used in all aspects of the business and allows comprehensive integration of opportunity and risk management across all activities in the company.Coal mining is widely perceived as an æold-economyÆ industry. But, like other successful æold economyÆ companies, the information systems and management processes used by Solid Energy are as leading edge as any in the high-tech sector. They are the key to managing to add and sustain maximum value for a company that has access to coal resources sufficient for hundreds of years.

Jan 1, 2002

The Mining Act (1992) and the Petroleum Act (1980) provide for the Government of Papua New Guinea (PNG) to take up equity holdings in mining and petroleum projects. The price the Government pays for its share is based on the historical cost of exploration and development on the project to the date of government equity acquisition. The equity level to be acquired is not fixed and ranges up to 30o for mining and up to 22.5s for petroleum at the discretion of the Government of the time.The objective of this paper is to examine the pros and cons of State equity holdings in PNG from the point of view of both the State and the developer. Using an economic model of the PNG mining taxation system an assessment is made of the effective return on investment received by the State from such equity holdings. The results are compared with government revenues from other taxation measures.

Jan 1, 1994

By Bojcevski D

The deportment and textural relationships of silver bearing phases are key characteristics in understanding the behaviour of silver ores in flotation tests or processing plants. These characteristics are however difficult to define and quantif

Jan 1, 1997

By J A. Didovich

Near the completion of undergraduate studies, students in mining-related courses are increasingly being presented the opportunity to undertake postgraduate studies. The current boom in the mining industry, the shortage of young professionals entering the industry and the lucrative starting salaries and packages on offer makes this a difficult and perplexing decision. This paper will outline what a PhD entails, discuss the benefits that a PhD can provide and discuss the timing and mode of a PhD.

Jan 1, 2006

The Australian mining industry has suffered from a decline in its public image during the past decade. This has occurred partly as a result of increased questioning of accepted social and economic values since the mid-1960s and the greater restrictions placed on industry since then, and partly ò from the industry's inability to effectively answer its critics. Public opinion surveys have shown the depth of the decline in the industry's community acceptability and highlighted those issues which people regard as disadvantages of mining. The industry's poor public image has contributed to the difficulties of attracting young people to take up professional careers in mining. All those involved in the industry have a responsibility to assist in activities designed to improve the industry community Acceptability.

Jan 1, 1981

The source and origins of the hydrothermal fluid of orogenic, or quartz-vein lode-gold deposits remain uncertain and disputed: Resolution would likely have a significant affect on exploration strategy. The gold-carrying fluid is interpreted to be a low-salinity mixed aqueous-carbonic fluid of near ambient pH and redox state, that may be derived either magmatically through crystallisation of granites at depth in the crust or through metamorphic reactions in a range of rock types. Classic isotope and geochemical tracers of fluid source have not differentiated these possibilities and have produced conflicting conclusions. Mass balance calculations show that fluid composition will be modified by wallrock reaction between source and deposit, and tracers should not be expected to give clear indications of fluid source. Fluid oxidation state can also be modified along flow paths. Tracers should be interpreted with care and with view to possible modification. Modelling of full flow paths and examination of the hydrothermal histories of proposed source rocks may be alternative approaches to determining fluid source.

Jan 1, 2002

By Skinner J, Brackenbury K

The AuPlus" Systems have been applied in the gold mining industry to achieve improved gold recoveries, faster leach kinetics and reduced cyanide consumptions. Calcium or hydrogen peroxide, collectively known as peroxygens, can be used. The choice depending on plant design and the nature of the ore. Laboratory test work and plant trials are included in this paper to illustrate the benefits of peroxygen usage in extractive gold metal- lurgy.

Jan 1, 1991

By Bailey DJ

Loader cut and fill stoping was first used at New Broken Hill Consolidated Limited mine in 1966. The equipment used included single boom pneumatic jumbos for drilling up- holes, diesel loaders for ore removal and diesel utility vehicles for rockbolting and servicing. Since 1966, there have been many modifi- cations and changes both in the equipment and stoping method. Twin boom pneumatic or hy- draulic drilling jumbos have replaced single boom pneumatic jumbos, electric loaders have replaced diesel loaders, diesel forklifts have replaced utility vehicles and "'flatbacking" has superseded uphole stoping. Concurrent with this has been the introduction of cable dowels in stope backs which has enabled loader cut and fill stoping to be used more extensiv- ely than in the past. There are now six loader cut and fill stopes at both mines and this paper traces the evolution of this method outlining the reasons for changes in technique and equipment.

Jan 1, 1982