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The growth of the mining industry around Australia over the last ten years has seen many open cut mines developed on shallow oxide reserves. Most of these have been gold operations, although there are some copper mines in the list, too. Many of these have exhausted their oxide reserves and have made the transition to underground mining to access their deeper sulphide ores. Other operations have reached or are approaching the point where the decision has to be made to go underground or cease mining. This paper discusses the issues involved in making the transition from surface to underground mining. The aim is not to discuss each of the issues exhaustively. This would take a conference in its own right. Nor is it intended to provide a primer on underground mining. Instead the aim is, firstly, to flag the issues which must be addressed when planning to make the transition from surface to underground mining and, secondly, to identify critical aspects of mine development.

Jan 1, 1997

Alaska Native corporations, as representatives of the aboriginal inhabitants of Alaska, control the mineral rights to 18 million hectares of Alaska, approximately 12% of the state. These corporations were established through legislation passed by the United States Congress in 1971 designed to settle the land claims of the Native peoples of Alaska. Twelve corporations, each representative of a specific geographic and cultural region, were established and granted the mineral rights to most Native lands in their respective regions. Since that time the Native corporations have taken an active role in mineral development in the state. Generally through agreements with established mining companies, Native corporations encourage balanced exploration and development of their lands. Substantial mineral potential has been recognized on Native corporation land, which includes holdings in many historic mining districts of Alaska. Several world class deposits have been discovered on Native corporation land, including the Red Dog zinc-lead deposit, which began production in late 1989. The experience of Alaska Native corporations demonstrates that aboriginal peoples can be very positive forces in resource development.Alaska, although remotely located in the Northeast corner of the Pacific Basin, is playing an increasing role as a supplier of natural resources to the region and the world. Most of Alaska's privately held natural resources are owned by the aboriginal inhabitants of the state. These aboriginal inhabitants, now collectively referred to as Alaska Natives, have emerged in the last two decades as having a major international impact in mineral resource exploration, development, and production.

Jan 1, 1990

By Weller KR

Completely dry or completely wet materials are comparatively easy to screen, but materials with moisture contents between these two extremes can present varying degrees of difficulty. The presence of moisture can impair the performance of a dry screening plant in a number of ways: ò agglomeration of fine undersize particles onto larger oversize particles, resulting in the fine particles being misplaced to the oversize; ò increasing attractive forces between particles that hinder stratification and particle presentation to the screen; and ò blinding of the screen apertures caused by fine moist particles clinging to the screen which reduces the effective aperture size and the open area of the screen. Test work on full-scale screens has shown that the agglomeration of fine particles onto larger particles only occurs once the equilibrium moisture content of the ore is exceeded, and that the quantity of adhering fines present is proportional to the surface area of the larger particles. An -adhering fines screen model has been developed from this work, and by using relationships derived between the model parameters and feed moisture content, the effect of changes in feed moisture on both product quality and operation of iron ore dry screening plants is predicted.

Jan 1, 1993

Conditional simulation is a branch of geo- statistics which allows the simulation of a mineral deposit so that predictions can be made about the variability of some particular parameter of the deposit. A summary of the general principles, advantages and limitations of conditional simulation is presented together with an example based on coal seam thickness.

Jan 1, 1981

By Reeve JS

Heap leaching is a low capital cost alternative to conventional processing techniques for gold recovery from areas that contain small gold particles in a porous host rock.For successful heap leaching the ores to be leached must maintain good permeability after being stacked into heaps so that the leach solutions can percolate evenly through them.The presence of clays, slimes or excessive amounts of fines can hamper the flow of leach solutions causing channelling and producing dormant or unleached areas within the heaps. This results in unreasonably long leach periods and poor extractions. In extreme cases the clays or fines completely seal ore heaps, causing leach solutions to run off the sides of t'he heaps rather than penetrate the ore.The Northern Queensland Company uses the Agglomeration Heap Leach technique (AHL) to overcome the difficulties associated with clays or fines. This technique involves cementing the fines, by using readily available binders, into a rigid, porous network that greatly enhances uniform flow of cyanide leach solutions through the ore heaps.

Jan 1, 1986

The Honourable Tony McGrady, Queensland Minister for Minerals & Energy and our local member; the Deputy Mayor of Mount Isa, Alderman Bob Moore; members and guests of the Australian Institute of Mining and Metallurgy; Ladies and Gentlemen; welcome to the Carpentaria and Mount Isa Region Development Forum.Withoutdoubtwearein an exceptional placeatan extraordinary time. In this region we have a numberofexistinganddeveloping mines, plus several major deposits in pre-feasibility oradvanced definition stage, and we continue to see further vigorous exploration. All this mining industryactivity is occurring against a backdrop of wider political, social and economic change, affectingmostofAustralia. The North West Queensland Branch of the Institute decided that the time was ripe for an open forum where issues involved with developing the region's assets be presented and discussed between members of the industry and also the general public.That then is the aim of this meeting: it is to be a place of learning and discussion about issues relevantto the developmentofthese deposits. To this end feel free to use the microphones in the aisles at question time to direct your questions to the speakers.

Jan 1, 1993

The paper discusses the use of animated dynamic numerical simulations to support design and operational decisions in the mining industry. The basis of the simulations discussed is a queuing theory engine with added features that enable continuous processes to be included in simulations. This approach is well suited to the needs of the mining industry which has a mixture of discrete events interfaced to a variety of continuous processes via various forms of surge capacity. Examples are given of the benefits of animation in communicating concepts to those with limited domain knowledge and simulation as a tool that facilitates the sharing of understanding between the stake holders of a system. The analytical content of the paper addresses conflict for resources within systems, the constraints imposed by human and other types of resources, and the impact of external events. Examples are presented showing the use loop diagrams and Gantt charts in the recognition conflict, and its causes. and the use of utilisation logs to identify opportunities for cost reduction.

Jan 1, 2009

By Lindbeck K

The mining industry in Western Australia is a large sector of the WA economy providing $12 billion (1993) of the export income for the State. Historically, mining in WA developed from traditional prospecting in the late-1880s leading to major underground operations by the turn of the century. Large open pits were developed in WA following World War II and became increasingly common since the gold boom of the 1980s. With the development of the open pits has been concomitant evolution of mining legislation, principally the Mining Acts of 1904 and 1978, which has been also accompanied by a practical evolution of the administrative system within the Department of Minerals and Energy. The mining industry has recognised the need for sound environmental management at mine sites, taking up the challenge and becoming a world leader in rehabilitation techniques. Any environmental management program in the industry has three stages: approval by government; management by the industry; and return to the State in an environmentally acceptable condition. The WA environmental requirements, procedures and industry performance in these three stages are discussed.

Jan 1, 1994

By Twemlow GL

The accounting profession in Australia and overseas has taken up the responsibility of setting standards specifically relating to the minerals and energy industries. Australia led the way with AAS7 Accounting for the Extractive Industries. This statement was issued in 1976 and amended 1977..It largely deals with accounting for preproduction expenditure and uses the term "economically recoverable reserves". It does not require disclosure of reserve quantities or values in balance sheets or as supplementary information in financial statements. The United States accounting profession in 1982 finally resolved an accounting standard in the same area as AAS7-SFAS69 Disclosures About Oil and Gas Producing Activities. It applies only to oil and gas producers, but has extensive disclosure requirements, including proved oil and gas reserve quantities. Current developments indicate that Great Britain is about to follow the US example. At this time in Australia, AAS7 or some other statement relating to the extractive industries has not been issued as an approved accounting standard by the ASRB. Standards issued by the ASRB are binding in law.

Jan 1, 1987

By Doxford CI, Perry AJ

Mining Lease 908, situated on Gorge Creek near its confluence with the present Cape River system, has been subjected to intensive recent exploration for alluvial gold.The gold is hosted by a buried palaeochannel, the Gorge Creek Lead and by an overlying remnant meander of the Cape River. The principal, if not sole, sources of gold within the Gorge Creek Lead are the northwest trending Great Australian Reef and Green's Specimen Reef systems which are situated on adjacent high ground. Lower grade gold bearing eluvial ground separates the reefs from the Gorge Creek Lead. The sources for gold within the old Cape River system channel (Canton Lead) are thought to be situated some distance upstream, one source perhaps being the Lolworth Diggings located 30 kilometres to the northwest.Exploration of previously "heavily dug" ground on both leads consisted of detailed geological mapping followed by the collection and treatment of bulk samples from eight costeans. The wash samples varied in size from 120 to 396 cubic metres. Treatment was undertaken through a commercial sized conventional wet screen and jig plant.

Jan 1, 1986

By Rynn J. M W, Paynter A

Recent studies by the authors have concerned themselves with assessing the earthquake risk to north-eastern Australia, based on available historical earthquake data for the area. There have been several significant earthquakes (Richter local magnitudes of the order of 6) concentrated in the Wide Bay - Burnett region in central eastern Queensland, although none of these has occurred close to a significant centre of population or development. Using derived average acceleration attenuation relations and world-wide data on earthquake-induced damage as a basis, conditions under which earthquake-induced liquefaction may occur have been investigated and presented in graphical form. Historical earthquake data for north-eastern Australia have been overlain on this graphical presentation and it has been demonstrated that the Wide Bay - Burnett region, in particular, may in the past have been on the verge of earthquake-induced liquefaction, where ground conditions are susceptible. When this is viewed in the context of the rapid growth in population and development in this area over recent years, the risk can no longer be ignored with impunity.

Jan 1, 1990

Erratic, though spatially localised occurrences of gold particles are a common feature of high-nugget gold systems. In many cases, gold is present as isolated or clustered, often coarse particles. The nugget effect is a part consequence of small-scale geologically controlled enrichment, and the inclusion or exclusion of gold particles from samples. Economic zones are generally contained within discrete structurally-controlled ore shoots which are surrounded by, and may include barren to low-grade background material. Problems are often encountered where small sample types (eg drill core and channel samples) of a few kilograms mass understate in situ grade by up to a few orders of magnitude, due to their general inability to represent the true gold particle distribution. This leads to uncertainty in mineral resource estimates. This contribution presents case studies where geologically-based parameters have been collected from drill core and underground faces to support grade determination. These parameters - or proxies - are based on mineralogical and/or geochemical (eg specific elemental ratios, fluid inclusion compositions and elemental correlations) criteria. Such criteria can be correlated with different grade domains to provide an indication of true grade within a geologically-controlled context. Proxies have recently been used to support resource estimates reported in accordance with the JORC Code.

Mar 1, 2010

At some time in the mining life of an open cut coal deposit, consideration is usually given to determine the point at which underground mining becomes an economic proposition or even necessary. This can occur anywhere from the pre-feasibility project stage to decades after commencement of mining. Options which can be considered include the extension of the life of the open cut by use of larger equipment, the utilisation of highwall mining techniques and the introduction of low capital start-up or full underground development. The primary focus is always the minimisation of the total unit cost (including capital )of clean product. The transition point at which an undergound mining operation becomes more economic than an open cut operation is not a simple evaluation and depends on many factors, particularly on the nature of the deposit itself. The main general determining factors of the transition point are related to the three factors of mining resource, the mining method that can be used and mining cost issues. Mining resource issues include geography, geotechnics, strip ratio, geology and the size of the deposit. Mining method issues include highwall mining, extending the life of an open cut, the environment, available roof support technology, product yields and the availability of appropriate workforces. The mining cost factors discussed include capital and operating costs and the impact of productivity and management. All these factors impact to a varying extent on the transition point.

Jan 1, 1997

By Osborne V. J, Urbank W

An explosion occurred at Moura No. 4 underground coal mine in Queensland on 16 July 1986 and resulted in the loss of 12 lives. The official report of the accident concluded that the most likely source of ignition was the flame safety lamp. This paper describes an investigation of the behaviour of a flame safety lamp, similar to the one involved in the Moura explosion in atmospheres of methane, coal dust and air, carried out at the Queensland Department of Mines . Testing and Research Station. The behaviour of the lamp is described in conditions of varying methane and coal dust concentrations in air, and varying air velocity. Particular emphasis is given to the 'phenomenon of burning which occurs inside the gauze and which is capable of causing the ignition of an external explosive atmosphere.

Jan 1, 1988

THE MORWELL BROWN COAL DEPOSITSTHIS deposits of brown coal in the neighbourhood of Morwell, are of tertiary age, and are represented on several horizons, but, owing to lack of evidence, the exact age cannot be fixed definitely. It is chiefly by reference to the basalt flows of the Older Volcanic series that the brown coal beds have been classified as of Pre-Volcanic and of Post-Volcanic age. The Pre-Volcanic brown coals are less widely distributed, and the seams generally are thin, though near Thorpdale a thickness of 40 tt. has been recorded, and from 10 ft. to 12 ft. in the vicinity of Narracan. Both of these localities lie to the south-west of Yallourn, and it has not been proven as yet whether these older coals and accompanying basaltic flows pass under the Morwell beds.The brown coal deposits have accumulated in an area where extensive faulting in early tertiary times has taken place with oscillations of elevation and depression of the land surface. In the vicinity of Yallourn, Paheozoic strata (probably Silurian) are exposed on either bank of the Latrobe River about a mile above the powerhouse weir, where the river flows through steep banks rising a couple of hundred feet on either side. The Silurian strata are highly inclined, and consist mostly of slates and Illudstones. Resting unconformably on the upturned edges of the Silurian is a conglomerate bed of Mesozoic age, above which occur beds clipping to the south-east of felspathic sandstones, with alternating mudstones at times carbonaceous, and containing thin seams of black coal.The brown coal seams and associated lignitic Clays, sands, gravels, etc, rest on the Mesozoic strata (as proved in the vicinity of the power-house and by boring north of the Latrobe River, near the old open cut), but do not appear on the surface of the Mesozoic, where these beds attain an altitude of more than 50 ft. above the present level of the Latrobe River.Half a mile upstream from the power-house a layer of basalt of the Older Volcanic series, almost resting upon the Silurian strata, is...

Jan 1, 1924

HAPPENING to be in Cue recently the writer was unexpectedly called upon to make surveys of some diamond drill bores on the Big Bell mine on the Murchison goldfield. The owner of the mine Mr Herman Mandelstam. had brought such apparatus with himas he could lay his hands on. and no other was available without prohibitive delay.The usual method of making these surveys as is well known is by putting a glass tube half filled with gelatine or glue in a melted state down the hole with a small magnet freely suspended in the glue and having it there till the glue sets solid. When this tubeis withdrawn (its depth down the bore being noted) the bearing and inclination of the borehole at this particular point can be read - the bearing by the compass and the inclination by the angle between the tube and the surface of the glue which of course ishorizontal. By taking a number of these observations according to the degree of accuracy required the course of the bore can be fairly accurately plotted.In dealing with dry holes there is little trouble but when the holes are full of water great difficulty is experienced. In the case in point the first observation was made in water 300 ft. deep, corresponding to a pressure of 130 lb. per sq. in. The tube containing the gelatine and glue (a mixture was used) was found, when hauled to the surface, to be completely filled with a weak mixture of water, gelatine, and glue and there was no horizontal surface from which to measure the angle of inclination of the bore. The water had been forced through the corks and sealing wax with which the tube had been closed. After several attempts it became obvious that no method available would keep the water from getting into the air-space in the tube, and to a pressure-proof metal container was impossible, nothing remained but to do away with the air-space and this was accomplished by using two liquids of different specific gravity - mercury and melted glue. The tube...

Jan 1, 1930

Teller Underground Mine was established to extract ore from the Middle Vale Reef located on the eastern flank of Telfer Main Dome.The mine is located below a 150 m deep open pit operation. The ore body is shallow dipping highly structured, and is a main aquifer in quite difficult ground conditions.In respect of these conditions it was determined to access the orebody using an adaptation of coal mining and hard rock mining methods, with support being achieved using a combination of island pillars, rock bolts and timber stalls.The paper will describe these methods in more detail, then discuss the successes and failures of these methods when put into practice. As well, it will detail several factors whose influences were found to be greater than previously expected and stress the importance of good geotechnical advice.

Jan 1, 1993

Qualitative measurement of respirable dust in metal mines is limited and an example of this is demonstrated at Northparkes Mine, where operational experience was sought for measuring dust standards and identifying exposure limits. However, relying on operational experience has limited value due to variation in observations from person to person and is based on visible dust (which is larger in size than respirable dust). However, with sophisticated dust measuring equipment, like the real-time aerosol monitor, dust concentrations can be accurately measured and recorded concisely. Research conducted as part of a collaborative agreement on behalf of Northparkes to launch an occupational dust monitoring program was implemented on the mine site. To form the basis of this research, it was hypothesised that no proper dust measuring testing at the mine site had been adequately identified. In addition, existing occupational hygiene monitoring programs did not adequately quantify employee exposures to these hazards. This project will outline the results of an occupational dust monitoring program, hence greatly improving the capacity to quantify the health risks posed to employees.

Jan 1, 2008

By Harris HR

This paper documents the selection, installation and performance of six, seventeen cubic metre, Dorr-Oliver flotation cells for primary zinc flotation at the North Mine in Broken Hill. The cells were installed to replace fifty, small cells, and despite initial design problems, have per- formed satisfactorily.

Jan 1, 1988

By Graham M

Longwall mining has been the dominant global coal mining method for decades. However, not until 1994 did longwall mining surpass continuous miner room and pillar extraction tonnage in the United States. This significant event, occurring in the most cost driven market in the world, confirms the efficiency and effectiveness of longwall mining.

Jan 1, 1998