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It has become increasingly clear in recent years that human kind has developed the capacity to alter the environment of the Earth on a global scale. The changes are often subtle. This is particularly true in the case of stratospheric ozone. Ozone is produced primarily in the stratosphere, at altitudes in excess of 20 km, initially through the action of ultraviolet sunlight dissociating molecular oxygen. According to theory as it existed up to a few years ago, ozone is removed mainly by reaction with atomic oxygen. In the unperturbed environment, this reaction proceeds both directly, and by paths catalyzed by trace quantities of nitrogen radicals. Molina and Rowland [Nature, 249, 810, 1974] pointed out that decomposition of industrial chloroflurocarbons could in-troduce an additional source of radicals to the strato-sphere. Chlorine radicals are even more efficient than nitrogen in catalyzing recombination of oxygen atoms with ozone; models suggested that we might expect reductions in the vertical column density of ozone of as much as a few per cent over the next several decades. A reduction in ozone of x¦/a, by increasing the flux of ultraviolet sunlight reaching the surface, was predicted to result in an increase of about 2x% in the number of cases of skin cancer, with other less well defined impacts on the non-human environment for life.

Jan 1, 1990

By Adam R. A

Techniques for the optimisation of open pit design and development are now accepted as standard practice in the mining industry. These techniques are used to analyse the impacts on project profitability of factors such as product price, slope design criteria and equipment selection. A fundamental assumption used in this type of analysis is that dump and stockpile designs and sequencing are predetermined. The cost of haulage for a typical truck shovel mining operation is in the range of 25 - 50 per cent of mine operating costs. Substantial cost savings can be achieved by optimisation of dump design and location of associated road and ramp systems.Factors which affect both the operation and total cost of dumping include; Ramp gradients and location, road design, dump placement and shape, dumping height, slope design (interim and final), slope stability, environmental requirements and equipment selection. This paper discusses these factors and their effects on the total mining operation and project value. Reference is made to case studies in which some of these factors have had a significant impact.

Jan 1, 1992

The Kanowna Belle deposit was discovered in 1990 following encouraging assays from soil sampling and RAB drilling. At the end of September 1993, diamond drilling had been completed to a vertical depth of 1,000 metres and a resource of 22 million tonnes grading 5.73 grams of gold per tonne containing a million ounces of gold had been defined. The deposit remains open at depth. Pre-production mining for the open pit began in November 1992, construction of the oxide treatment plant began in January 1993 and the first gold was poured in September 1993. Sulphide ore roasting commenced in December 1994 and the underground mine development commenced in July 1995. The Kanowna Belle project is owned by the Golden Valley Joint Venture (GVJV), an unincorporated joint venture with equal shareholdings between North Gold (W.A.) Ltd and Delta Gold N.L. North Gold are the managers of the development and operations and Delta Gold are the managers of exploration throughout the GVJV tenements.

Jan 1, 1990

By R McCarthy, P Hawke

FerrAus Ltd's Robertson Range and Davidson Creek Projects are located in the Hamersley Province about 100 km east of Newman, Western Australia. Significant iron mineralisation defined by an aggressive exploration program within the Marra Mamba Iron Formation is shallowly north dipping at Davidson Creek, and mainly shallowly east dipping at Robertson Range, forming part of a regional scale anticline with the granitic and greenstone basement of the Sylvania Inlier as its core. With minor exceptions, the stratigraphy is comparable with that seen in the main Hamersley Basin. Granite and greenstone basement rocks of the Sylvania Inlier are unconformably overlain by shales and volcanic rocks of the Fortescue Group. The overlying Hamersley Group is locally represented by interbedded chert, banded iron-formation (BIF) and shales of the Marra Mamba Iron Formation (Nammuldi, MacLeod and Mount Newman Members), and dolomites, cherts, BIF and shales of the Wittenoom Formation. Iron enrichment occurs predominantly in the Mount Newman Member, and to a lesser extent in the West Angela Member of the Wittenoom Formation. Enrichment varies from 20 - 30 m in thickness in elongate bodies up to 3 km in strike length, and generally thins down dip. At Davidson Creek iron mineralisation is a haematite-goethite-ochreous goethite assemblage, while at Robertson Range this assemblage is consistently overprinted by a later, goethitic alteration related to 'hardcap' weathering. Near surface hardcap alteration in both project areas comprises more siliceous, aluminous and vitreous goethite. Initial exploration completed by Rio Tinto Exploration between 1999 and 2001 indicated the potential for about 20 Mt of iron mineralisation at Robertson Range. Since 2005 a detailed exploration program undertaken by Australian Manganese Pty Ltd (a wholly owned subsidiary of FerrAus Ltd) has defined a global indicated and inferred resource totaling 164.4 Mt at 58.6 per cent Fe (ASX: FRS 17 April 2009).

Jan 1, 2009

The introduction refers to observations made in the early days of the Nationalisation of the Coal Industry in the United Kingdom, indentifying the underground transportation problems. Statistical information is presented, highlighting the considerable developments which have been made in recent years with an evaluation of the manpower and cost involvement.

Jan 1, 1985

By Ichinose M, Tsuru T, Gotoh K

Since 1980, the Department of Mining Engineering at Kyushu University, in co-operation with the Ikeshima Colliery, Matsushima Coal Mining Co. Ltd., has been conducting a research project into longwall gateroad designs applicable to deep and poor strata conditions. During this period, the economic environment has drastically changed the situation of the domestic coal mining industry. Conventionally, the retreat longwall method, with re-use of gateroad, has been employed as it achieves higher recovery. However, from the view point of production efficiency, this method is not suitable because it requires intensive work in side packing and roadway maintenance. Therefore an interpanel-pillar system, or a two-entry gateroad system, was adopted to identify the factors responsible for excessive vertical closure in longwall gateroads. Field measurements and non-linear finite element analyses were undertaken to confirm the performance of this system. Study results indicate that the stability of the gateroad employing the rib pillar system is comparable to that of the conventional system of re-using Gateroads.

Jan 1, 1992

This opportunity to present a few thoughts on the question of professional education and training comes at a most appropriate time. In Britain, a great deal of energy is being expended in this, so-called, post-Finniston era, to create a new look for the status of engineers and engineering by the Engineering Council. Naturally, the tune and the tempo are being called by the big institutions which essentially serve the manufacturing industries. However, the Engineering Council in Great Britain also includes the mining and processing institutions such as the Institution of Mining and Metallurgy (IMM) and so there is a chance - if it is taken - for us to contribute to the debate and the determinations that emanate from it. The IMM, of course, caters for the professional status of those engaged in the mining and minerals industries and includes many who do not see themselves as engineers. Nevertheless, the debate is important to these other groups whose livelihood is inextricably bound up with those who are engineers and there are many facets of the engineering policies being shaped that will, I am sure, eventually be enshrined in the requirements for professional status across all the various disciplines in our industry.

Jan 1, 1986

By Turker L

The leaching of Tellness (Norway) ilmenite concentrate in hydrochloric acid and mixed aqueous HCl-alcohol solutions at boiling temperatures was investigated. It was found that the alcohols methanol, ethanol and ethylene glycol all substantially increased the leach rate and in the case of methanol and ethanol this was achieved at lower boiling temperatures compared with aqueous HC.

Jan 1, 1986

By J Masliyah, Z Xu

The largest oil sand deposit in the world is located in Alberta, Canada, with a total proven reserve of 2.5 trillion barrels of oil. The water based extraction process is currently being used in commercial operations to recover bitumen by flotation from oil sand ores. A recognised challenge in bitumen extraction is the reduced bitumen recovery when processing ores containing high fines content or æweatheredÆ oil sand ores, collectively known as poor processing ores. Inspired by demonstrated success of using kerosene as collectors in coal flotation, an innovative idea of using oily bubbles (air bubbles coated with a thin layer of oil or solvent) was tested to improve bitumen flotation recovery from poor processing ores. In this study, dynamic contact angle of air bubbles or oily bubbles on bitumen and induction time of bitumen-oily bubble attachment in water were measured to justify the use of oily bubbles in bitumen recovery from poor processing ores. The type of oil or solvents, including kerosene, toluene and naphtha, used in generating oily bubbles showed a marginal effect on the contact angle values, similar to the values measured with air bubbles. However, the spreading of an air bubble was found to be much slower than that of oily bubbles on a bitumen surface. The induction time for oily bubble-bitumen attachment was found to be much shorter than that for corresponding air bubble-bitumen attachment in the process water from poor processing ores. The reduced induction time for kerosene-coated air bubble-bitumen attachment correlates well with the improved bitumen recovery from poor processing ores using kerosene-coated oily bubble flotation technology.

Jan 1, 2005

By Schmidt CG

Parameters affecting gold elution using the AARL process are reviewed and critically analyzed in an attempt to optimise metallurgical efficiency and minimise costs in both current and future carbon adsorption operations. Such factors as acid washing, column geometry, elution temperatures and pretreatment reagents are discussed together with eluant water quality and eluate flowrates. Hot acid washing of carbon prior to gold elution has many benefits. Besides improving elution efficiency when eluting with regional water, a hot acid treatment preheats the carbon without causing any gold leakage. Laboratory data indicated that hot acid washing reduces the mass loss of carbon during thermal regeneration. The eluate going to either zinc precipitation or electrowinning is also relatively free of troublesome impurities (organic contaminants and ferrocyanides in particular). Because of the chromatographic character of the AARL elution where an ionic strength gradient is used to inhibit the readsorption of gold, column geometry plays a significant role. While practical considerations and capital costs may restrain the length of the elution column, high length/diameter ratios are advocated in order to promote the plug flow of column eluate. From both a metallurgical and costing viewpoint, the two significant factors affect- ing the AARL gold elution are temperature and cyanide addition. High temperature and high reagent additions within prescribed limits will improve metallurgical efficiencies, but a balance between energy and reagent costs is required in order to minimise overall elution costs. As pretreatment reagents constitute a considerable portion of the total elution costs, both the addition and consumption of sodium cyanide must be carefully considered. Lower cyanide additions may be effective in certain instances, but the more practical use of 0,6 bed volume of a 2-3 per cent NaCN reagent containing 2 per cent NaOH is advocated. This is equivalent to an addition of 20-30 kg NaCN and 20 kg NaOH per ton carbon Treated.

Jan 1, 1986

Investment decisions in the Australian mining industry are often made without awareness of the impact of risk on project outcomes. A fundamental change in thinking is required to move away from the traditional attitude of æcushioning the blowÆ towards a measured approach to project risk. Such an approach involves quantifying and understanding project uncertainty so that investments may be shielded from downside risk while at the same time exposed to upside potential. Communication and collaboration between study teams and corporate financial managers must be improved before the industry can improve its project investment record. Monte-Carlo simulation provides a way to quantify and understand investment risk, but its accuracy depends on how well the variability of input parameters is estimated. Research in this area is currently centred on quantifying uncertainty in mineral resource estimation using new conditional simulation techniques, but a less-rigorous method can be applied in practice to begin the education process and develop the required awareness at board level.

Jan 1, 2003

By H Rose, T J. Sheer, M Dumka

Whenever rock is tipped from above, severe eruptions of airborne dust occur into the airways connected to tipping stations of rock passes (ore and waste) on the lower levels of a gold mine in the North West Province of South Africa. An investigation was undertaken to understand the nature of the physical phenomenon, in order to propose possible solutions. Accordingly, measurements were taken underground, involving the simultaneous logging at two levels of the transient pressures produced in the orepass by tipping from various levels. Two portable data loggers with associated transducers were custom-built for this purpose. Measurements were taken during a tipping program in which rock quantities and levels were controlled. Pressure pulses that are generated by the falling rock drive the airborne-dust eruptions. When tipping from a specified level, recorded pressure pulse waveforms were found to be repeatable on any given level, irrespective of the amount of rock falling, but measurements were conspicuously different on different levels. It was recognised that a pressure pulse is generated as the falling rock passes through the constricted region û a relatively narrow neck û at each tipping station. In passing through the constricted areas the mass of falling rock acts as a æleaky piston in a cylinderÆ and compresses the length of the air column in the orepass below that level. Once the rock has passed through the constriction, the pressure is released and this behaviour causes a regular train of pressure pulses that are separated by the time taken for the rock to move from one level to the next. Based on this physical understanding of the dust eruptions, a computational model has been developed that can reproduce all the main features of the measured phenomena. The model has been verified adequately against the measurements and can now form the basis for simulating a range of possible engineering solutions.

Jan 1, 2005

By J Lim, M Powell, P J. Scales

The current philosophy employed in the design of mineral processing plants effectively involves bolting together segmented unit operations both chosen and optimised from a product-centric perspective. In this context, integration of water saving technologies at an overall plant level becomes difficult and often only local water efficiency improvements are feasible. In general only limited benefit can be obtained from such add-on solutions. It is therefore proposed that to obtain significant savings in water consumption and reductions in the volume of discharged contaminated water in the mining process, the entire process along the mining and mineral processing chain should be addressed This paper explores aspects of the processes that may be modified to provide an integrated and combined step change saving in water consumption. It is also apparent from this study that taking a more holistic view of the process can provide significant benefits in energy savings and total cost of production, providing the potential of a substantial win-win outcome.

Jan 1, 2009

By Associates

The headwaters of Skippers Creek and the Shotover River are reputed to be among the richest alluvial gold catchments in the world. This alluvial gold has no doubt been derived from reef systems similar to, and associated with, the Bullendale lodes. Physiographically the prospect covers steep ridges and deeply incised gullies between the Richardson Mountains in the west and the Harris Mountains in the east. Vegetation is mainly tussock with bush either side of Murdochs Creek. Access to the area is by metalled road to Skippers and then by 4WD track to Bullendale. Alternatively the prospect area can be reached by helicopter from Queenstown in around ten minutes.

Jan 1, 1992

Epicentres of recent shallow earthquakes in the region (3-12¦S, 126-150`E) were plotted to identify the various plate boundaries in the region, in particular the southernmost one marking the northern edge of the Australian plate. New and published fault plane solutions were examined to determine the style of faulting and state of stress along the Australian plate boundary. From east to west the boundary is first a subduction zone along the Solomon Islands, then a spreading centre across the Solomon Sea, a zone of compression and left lateral strike slip along the Papua Peninsula, almost pure thrusting across the centre of New Guinea and lastly left lateral strike silo through Irian Taya to the outer Banda Arc. The principal stress is very consistent, trending NW to NNW in a near horizontal plane, from the triple junction of the Pacific, Solomon Sea and Australian plates in the east to the Banda Sea in the west. Only along southern Solomon Sea plate margin which is a divergent boundary, is the stress different in type and direction.

Jan 1, 1987

The prevention of silicosis by metallic aluminium has been reported by Denny, Robson, and Irwin in two papers. The first was published in 1937; the second, in 1939. The results definitely established that silicosis was prevented in animals by the inhalation of small quantities of aluminium. The present communication records subsequent progress in this field of research.

Jan 1, 1944

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

Management of Mining Wastes in European Union and Developments in Turkey

Sep 13, 2010

Degussa's PAL-system (peroxide assisted leach) has been proven to be more economical than the conventional cyanidation technique. Significant in- creases in the gold recovery have been reported, accompanied by savings in cyanide. Accelerated extraction kinetics and modified reagent demands necessitate a redesign of the conventional cyanidation plant. The South African Osprey Mine is presented as an example of a successful PAL-application. Based on the plant and laboratory data it is shown that the redesign of the flowsheet can be an important factor for the effectiveness of a metallurgical plant. In the case of the Osprey Mine, the PAL-technology all ows a modification of the current preoxidation-ClPcircuit to two separate CIL-plants to treat run-of-mine ore and old tailings dumps. A doubling of the throughput is possible without enlargement of the plant. This innovation in the field of gold extraction, the combination of the PAL-process with a redesign of the metallurgical plant, can be considered as a basis for a more profitable gold mine.

Jan 1, 1991

By Kasai H, Hibi T, Matsuishi S

Coal oil mixture (COM), a liquid fuel pro- duced by mixing together coal and heavy oil on the 50-50 basis, has been brought to a level of practical use in Japan, being actually employed by a oil fired system at Yokosuka Thermal Power Station of The Tokyo Electric Power Co., Inc. A COM Production Plant, built in Onahama which is located about 160 miles from Yokosuka, required COM to be transported by sea. Mitsubishi Heavy Industries, Ltd. therefore performed a series of studies to develop a spe- cialized COM carrier, the world's first of its kind. Long lasting high stability is of pri- mary importance to successful use of COM. Much have been done in the way of research on stability of COM in the static storage, and the mechanism of COM static: stability is almost completety known. On the other hand, the knowledge about the COM dynamic stability, such as the stability while being transported aboard the COM carrier at sea, is still limited at the moment. The motion of COM aboard the COM carrier and how COM would settle were studied by tests. A visualization test on the COM behavior under dynamic motion was also performed and the mechanism of COM dynamic stability was analysed. The tests showed that the ship rolling motion had @n effect of promoting the settling of coal content of COM in the cargo hold. And studies were also made to device a method for esti- mating the settling quantity of coal during sea Transportation.

Jan 1, 1987