Search Documents

By He F, Zhu D

How to monitor and control the support and surrounding strata system on a longwall face effectively is one of the major research problems in ground control. Based on observations on movements of the support and surrounding strata of face No. 2703 of Dongpang colliery, the relationship between the downtime related to support and surrounding strata and other influential factors is analysed systematically in this paper. Monitoring indices and control measures are then determined by taking corresponding downtime as an objective function. When the monitoring method, developed from the above findings, was used on face No. 2703, the downtime due to support and surrounding strata was remarkably reduced, and the face advanced Normally.

Jan 1, 1992

By Hikosaka A, Chiba A

In a fundamental study of the physical chemistry of steelmaking slag, equilibra bet- ween hydrogen-water vapour gas mixtures and liquid slags contained in solid iron crucibles have been measured for four binary slags, FetO-CaO, FetO-Si02, FetO-TiO2 and FetO-Al203 at 14000C. From the data, the activity of iron oxide and the ratio of ferrous and ferric ions (A = Fe3+/Fe2+) were calculated for the slag composition. The best ionic model is found to be that based on regular solution of cations. The oxygen distribution between slag and metal is quantitatively expressed by this model over a wide range of slag composition.

Jan 1, 1980

By Rayner J. G, Leckie J. F, Moorehead C. F

The Coronation Hill gold-platinum-palladium prospect is located in the valley of the South Alligator River (latitude 13'35'S, longitude 132'36'E), about 80 kilometres east of Pine Creek in the Northern Territory. Coronation Hill was one of thirteen sites in the South Alligator Valley at which uranium was mined between 1955 and 1964 after initial discovery by the Bureau of Mineral Resources in 1953. Most of the mines were operated by United Uranium No Liability. The Sleisbeck mine 25 kilometres south of Coronation Hill was operated by North Australian Uranium Corporation and the group of mines at Rockhole about 20 kilometres to the north-west of Coronation Hill was operated by South Alligator Uranium No Liability. The uranium mine at Coronation Hill produced about 26000 tonnes of ore averaging 2.6 kg/t U308 with an estimated average gold grade of 10.4 g/ gold. Gold was commonly associated with the uranium mineralisation and was recovered at the gravity treatment plant at El Sherana. Gold was also recovered in 1986 by Pacific Gold Mines Limited by treating the tailings from the Moline and Rockhole uranium leach plants at a CIP plant at Moline. With the completion of uranium contracts in 1964 mining in the South Alligator Valley ceased. Exploration for uranium continued in the area during the 1960s and 1970s with no success. The Coronation Hill Joint Venture (BHP Gold Mines Limited 45 per cent, Pioneer Minerals (Gold) Pry Ltd 45 per cent, Notgold Limited 10 per cent)carried out the first exploration specifically targetted at gold in 1984 with the drilling of five vertical drill holes which indicated high potential for a substantial gold resource at Coronation Hill with no associated uranium. The Joint Venture has sub- sequently drilled about 25000 metres of diamond drill holes at Coronation Hill alone. Analytical results from 1985 drilling established that platinum and palladium were associated with gold. An indicated resource of 3.49Mt at 5.12g/t Au, 0.21g/t Pt and 0.56g/t Pd has been calculated using a lg/t Au cut off.

Jan 1, 1991

By Gang L

Seventy-nine gold deposits and prospects have been discoveried in the Jiamusi region of northeast China, and constitute one of the most important gold metallogenic belts in China. All these endogenic gold occurrences can be subdivided into three main deposit types: (1) porphyry related; (2) metamorphic-intrusive hosted, and (3) sediment-hosted deposit. The first two types of gold deposit are spatially and temporally related to Mesozoic Yanshanian granitoid intrusions with hydrothermal activity channelled along crustal-scale fissures. The ultimate cause of the Yanshanian magmatism is considered to be the subduction of Pacific oceanic lithosphere beneath the Eurasian continent. In contrast, The chemical sediment-hosted deposit is typified by the Dongfengshan gold deposit, and genetically related to Proterozoic sedimentation and Mesozoic igneous activities.

Jan 1, 1995

By Lovitt M

Ora Banda Gold Mine is located in the Eastern Goldfields of Western Australia. Mining is carried out underground by sublevel open sloping resulting in large open stopes. A Mass Blast of approximately 250 000 tonnes was carried out in July 1994 to recover a rib pillar between two stopes, and the crown pillar between the underground mine and the abandoned open pit above. Strategic development within 50 m of the blast consisted of two ventilation shafts and the main decline. This development required careful design and prediction of the blast results. This paper describes the design of the blast, the prediction of the likely effects, the measures taken to reduce the risk to important development, and the results of the blast.

Jan 1, 1995

The last decade has seen a dramatic change in the. size and complexity of mining and mineral processing projects in Austral- asia. Major projects of today are vastly different from major projects of the 19.50's. This change has in turn resulted in a change in the role-of consultants whose contributions have been increasingly in the provision of specialist services and less in the form of overall project design and construction supervision. It is anticipated that, the specialist function will continue to represent the principle mode for consultant participation in major, projects. However, by means' of international affiliation, the development of comprehensive engineering and project management capabilities and possibly as a result of Government intervention, it is expected ,that local consultants will assume an increasing degree of participation in.the overall project design and supervision Function.

Jan 1, 1975

THE auriferous sulphide ores of the eastern end of Gippsland, and notably of the Cassilis and lVIitta districts, are amongst the most complex and refractory in Victoria-perhaps in Australia. The minerals occurring in these ores are pyrite, arseno-pyrite, zincblende, galena, and (in smaller amounts) some of the copper, sulphides, as chalcopyrite and covellite; and some of the antimonial minerals, notably stibnite and jamiesonite. In the oxidized portions of the lodes, the oxidized lead and iron minerals, and small amounts of the hydrated arseriiate of iron, are found.In the Cassilis mine, near Omeo, copper is present usually in quantities of under 1 %. The magnetic sulphide of iron is of fairly common occurrence. In, the upper levels of the Cassilis mine tin was usually present, the amount going up to 3% in some samples of concentrates. These minerals occur sometimes banded, but usually as an intimate mixture-pyrite and arseno-pyrite predominating. The gangue is usually quartz (blackened by enclosed particles of sulphides). Calcite, magnesium silicate and felspar are also present in varying amounts.

Jan 1, 1911

By Swift D. G

For some time the Electricity Trust of South Australia (ETSA) has been investigating the application of new mining methods and equipment to minimise the cost impact of the steadily increasing depth of mining brought about by the 20¦ dip of the coal seams at the Leigh Creek Coalfield. Exhaustive examination of all suitable mining systems showed that highly mechanised systems involving belt conveyors displayed no eco- nomic or operational advantages over shovel and truck methods. However, the configuration of the Leigh Creek coalfield allows for two quite different approaches to mining by shovel and truck. The current strip mining method involves removing overburden from the highwall in 60 m to 200 m wide strips to progressively expose the coal down dip, and requires all waste to be hauled to the surface. The alternative ter- race haulback method involves opening a boxcut to full depth at one end of the coalfield, then mining the full section along strike and placing the spoil in the mined out area. On a strictly economic basis, the latter is clearly advantageous, but the former has significant less tangible advantages. In deciding between the two methods ETSA is faced with the need to examine the applicability of each method under a wide range of possible future demands on the coalfield, and to assess the importance of many intangible factors.

Jan 1, 1989

By Chitombo GP

The proposed guidelines on vibration limits that have been circulated by the Australian Environmental Council, demonstrate the need for an extensive data collection and evaluation program to avoid the enacting of abritrary and costly legislation. The operational or practical influence of blast design and overall economic implications of legislation which further reduces permissible levels of ground vibration are discussed. In a typical blasting operation, blast sizes could become smaller and blasting correspondingly more frequent to meet pro- duction demands. Blasthole diameters and charge lengths could be reduced, increasing drilling costs and associated labour costs. Blast size however, is frequently controlled by factors associated with machinery, grade control, pit control, stope size, production contract levels and other factors which cannot be readily changed for operating mines. Blasthole diameters are frequently deter- mined by existing drilling equipment, length of holes (depth of ore or stope size), geological structure and other factors which are not easily changeable. Typical large scale open stoping and strip mining opera- tions are analysed as case studies. The effects of extreme leg- islative limits and the corresponding operational changes with respect to variations in production costs are discussed.

Jan 1, 1987

By H R. C Pratt, G W. Stevens

Hydrodynamic and mass transfer performance are presented for a 72.5 mm diameter pulsed disc and doughnut column of the type used by Western Mining Corporation, Olympic Dam Operation, for the extraction of uranium from sulphate media using Alamine 336 as extractant. For the present purpose, 4.0 g/L sulphuric acid was used as solute. The mass transfer data were interpreted in terms of the diffusion model, thus accounting for continuous phase axial dispersion. The results indicated that an efficiency corresponding to approximately one transfer unit over the 1.0 m height of the column was obtained. This efficiency is comparable to that observed by Gottliebsen (1997) for a pulsed perforated plate column using 173 gm/L sulphuric acid.

Jan 1, 2000

Although the effects of sea level changes on ore concentration processes are to some extent obvious with certain deposits, e.g. beach placer deposits, they have been largely overlooked with others such as Mississippi Valley type lead-zinc deposits. It is contended that sea level variations may have more profound effects on a wide range of deposits than has previously been appreciated. These deposits include not only placer'and residual deposits but also stratiform copper deposits, Mississippi Valley type deposits, stratiform manganese deposits and Minette type iron deposits. Sea levels in paralic basins profoundly affect the influx of 'detrital sediment, and this has to be suppressed to allow for the accumulation of thick rich deposits of coal evaporites, phosphate or metalliferous sediment. Emergence can be associated with oxidized waters, erosion, and,solution of soluble rocks. Submergence can reverse the Eh trend and can lead to preservation of ores. Both realms of surficial sedimentary environments and subsurface diagenetic environments can be affected by changes in water pressure, gas pressure (pC02), Eh, pH, and temperature as sea levels fluctuate. Even relatively small sea level changes may have profound effects. For example, there is some evidence to suggest that when the level dropped below 100 metres about 10,000 years ago, the Red Sea became isolated by the sill at Bab el Mandeb in the south, and evaporated away to leave a series of shallow lakes. The Red Sea is 1 to 2 km deep. It was at times such as this that the well-known copper-zinc mineralization developed in the Red Sea trough. Changes in sea level also affect the stability field of gas hydrates which can yield large volumes of gas leading to mass movements on the sea floor (Warnke, 1986).

Jan 1, 1987

By G Byrne, A Bowden

There is often a difference in opinion about the allocation of risk in the establishment of mine closure bonds or financial assurances. From the State’s perspective, protection is needed to ensure that the broader community is not left with the liability of properly closing a mine in the event of a default by the mine operator. Such a default might occur where an operator decides to abandon a site, perform incomplete rehabilitation, becomes insolvent or claims limited liability. On the other hand, mine operators who can demonstrate a strong financial position plus a record of social and environmental commitment and performance, argue that there should be some recognition of this in setting a bond that is less than the full cost of early closure. They argue that a mine rehabilitation bond based on the full cost of early closure is overly conservative and ignores the actual risk of the operator being in default. This paper examines an approach that incorporates the risk of default into the establishment of mine closure and rehabilitation bonds. CITATION:Bowden, A and Byrne, G, 2018. Mine closure bonds (financial assurances) – the ‘how much?’ conundrum, in Proceedings Life-of-Mine 2018, pp 32–34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

The problem of instantaneous outbursts remains unsolved after over a century of events and the investigation of the mechanism of the phenomenon and means of treating it. Outbursts have occurred of up to 5,000 tonnes with perhaps up to 500,000 m3 of accompanying gas, either methane (CH4) or carbon dioxide (C02) or mixtures. The low density of CH4 and the high density of CO2 give particular problems. Australia with both gases has experienced outbursts for 85 years with fatalities as recent as 1978. The Bulli Seam of the Illawarra area of the Sydney Basin is affected and outbursts with both CH4 and CO2 occur. The Northern and Central Bowen Basin also experiences outbursts with both gases. Proneness of affected mines is related to the high rank of the'coal and the proneness of the seams-is localised according to depth, gassiness, structure and development geometry. Proneness may be reduced by appropriate choice of mining methods. In addition to outbursting mines other mines have symptomatic phenomena. Traditional preventive methods have been used and control by induce- ment has been practised. A method of local prediction for widespread use has not been achieved although locally successful prediction 1Superintendent Rock Mechanics and Strata Control, The Broken Hill Proprietary Company Limited, Steel Division Collieries, Wollongong, N_RW

Jan 1, 1980

Sizing is fundamental technology for each step of ironmaking process. The progress of sizing technology has greatly contributed to the development of ironmaking technology. As the purposes of ironmaking operations diversified particularly since the oil crisis of 1973, the sizing technology made new advance- ment, as represented by pulverization of ser- pentine, dezincification and classification of secondary blast furnace dust, pulverized coal injection, size-segregated sinter charging and a coal preparation control process. These techniques are mostly characterized by the fine grinding of a given type of mineral or coal to heighten the degree of reaction con- trol. This trend is expected to continue Further.

Jan 1, 1984

Future hard rock mining will gradually move towards complete mechanisation which lends itself to remote control and ultimately to robotic mining. This will require different technical inputs into mining engineering and one of these is in the area of rock'mechanics. Traditional hard rock mining has had little rock mechanics input. Problems arising from high stresses and poor ground conditions have in most cases be remedied after they occurred, in the worst case by abandoning a particular stope or area and starting elsewhere. In a fully mechanised remote or robotic mining situation the financial penalty for such an approach could be severe, as a major part of the production costs will be in the development and the equipment. It is therefore imperative that a complete rock mechanics feasibility study is undertaken before an area is set up for robot mining and that a continuous stability monitoring system is installed that will predict rock behaviour well in advance of mining, such that the necessary ground control measures can be implemented without impeding the continuity of mining. This system will utilise already existing instrumentation such as extensometers and stress cells, and possibly additional improved instrumentation which has to be developed for this particular Application.

Jan 1, 1986

LITHOPROBE is a national, collaborative research grogram with the general objective of understanding the teotectonic evolution of the North American continent through multidisciplinary lithospheric studies in carefully selected areas of Canada. Six transect areas are investigating Precambrian evolution, although only in two of these is the research well evolved. The Archean Kapuskasing Structural Zone in Ontario is confirmed as an upthrust slice of upper to mid crust exposed at the surface. The Late Proterozoic Keweenawan mid-continent rift is shown to be the deepest known rift on Earth and the Grenville collisional zone of Ontario and Quebec involves crustal scale imbrication and ramping of deeply buried rocks to the surface. Two transect areas are investigating Phanerozoic evolution. In the Newfoundland Appalachians the geologically defined tectonostratigraphic domains do not coincide with lower crustal blocks defined by seismic reflection data. The Southern Cordillera Transect in western Canada is examining the nature, timing and dynamics of the assembly of the Cordillera, and particularly the role of accreted terranes. Work in the eastern and central segments has extended the known western limit of the North American craton at least IOO km westward and crustal-scale ramps associated with metamorphic core complexes have been identified.

Jan 1, 1990

By Abdalla MH

The deformation resulting from the presence of a tunnel may signifcantly affected, nearby structures and need to be considered during design of both tunnel and structure. The aim of this paper is to study the effect of different factors which may affect the interaction between the tunnel and the str- ucture. These include; the depth of both tunnel and foundation level of the structure ( z and t ), distance between C.L. of tunnel and loads, breadth of the loaded area, Diameter of tunnel and lining of the tunnel. The problem is studied as a two dimensional plane strain model by the boundary element technique. The results of this study indicated that the presence of a cavity/tunnel increases, in general, the vertical displacement on the ground surface and at the foundation level as well as the horizontal and vertical stresses in the cavity/tunnel level. The effect of eccentricity is increasing as e/D decreasing. For pile foundation there is a quite different- influence of the presence of cavity/tunnel in both cases of friction pile and end bearing pile type of foundation.

Jan 1, 1987

The expense of mine environmental and planning process approvals is a fundamental and proper part of mine planning and feasibility costs. It is not a cost that should be the subject of challenge nor is it a cost that should be avoided. However the additional process approval costs incurred by bureaucratic delay, process duplication and administrative incompetence is a scandal and a deterrent to investment.

Jan 1, 1992

By Hall K

The Osborne copper gold mine, 100 per cent owned by Placer Pacific Limited, is situated 195 kilometres south east of Mount Isa. The orebody is broadly categorised into three main ore zones; oxide, transitional and sulphide copper. Copper oxide

Jan 1, 1997

By Briggs D

Comparing the results of a plant trial by averaging performance measures collected during the trial with measures collected before and after the trial is often quite subjective because of the impact of natural variation on the process. This is

Jan 1, 1997