Search Documents

By Littlewood E

We offer these notes as a practical contribution. All the arguments we advance have been tested by practical experience.In its preparation we realised that our subject was one of such importance and covered so wide a field that, dealt with by one of us alone, it might easily have been too much for him, so we have endeavoured, by mutual criticism and advice and a pooling of ideas, to bring forward a few points that may be of advantage to members. If any of the paper is of benefit to mining on the "Golden Mile," or elsewhere, we shall feel amply repaid for our efforts.It is obvious to all that the longer the machine is working productively per shift the greater the return, to all concerned; the machine-man himself and the company. Furthermore, if a man commences a shift with a definite objective in view; for instance, to bore and fire a specific cut, which he recognizes will give him a good financial return, then that man will exercise all his capabilities to attain that objective.In this paper we hope to demonstrate the value to the machine-man of the knowledge of the capabilities of each hole he bores, so that he will be enabled to utilize his drilling time to the greatest advantage. Also, we hope to show that such drilling time can be advantageously extended.After the war, with the influx of new men to the industry, some education on the finer points of machine work may be desirable, and any instruction in this branch must stress the realization of the value of each hole.We realise that most of those present have a sound workable knowledge of machine-mining, and we are not trying to teach anyone the fundamentals of machine work, but we would like to bring to their attentIon some of the finer points which we believe are very important.The machine-man has control of gear of a capital value of over £150, and the use or misuse of that material has a direct bearing on working costs. Therefore it is imperative that the capital outlay is gainfully employed.A "bogger" in charge of a 5/- shovel engaged unproductively is bad enough. How much worse for £150 worth of gear to be not fully productive.Figs. 1 and 2 demonstrate angles of break, and the full realization of the importance of this angle is essential to our paper. Although these Sketches are two-dimensional, we hope they will be sufficient to demonstrate our meaning. We will pass over them as briefly as possible.Fig. 1 shows three holes asked to perform an identical task.(a) 7-ft. hole bored 2 ft. into solid ground-will not come out.(b) 4-ft. hole bored 1 ft. from solid ground-will come out easily.(c) 5-ft. hole bored to solid ground-the best that can be expected under general conditions encountered.The angle of break is a right-angle, normal to direction of hole.

Jan 1, 1944

By R Robinson

Modem occupational health practice can be described as the fitting of work to the individual and each individual to his job; perhaps a non-traditional way to view occupational health. This two-component description is achieved through the development of programs to implement and monitor specific job procedures, from the monitoring of unwanted exposures to contaminants to the auditing of mine sites. This paper is about such programs. Some attempt must be made to evaluate the effectiveness of the program and several performance indicators which are intended to measure the effectiveness of such a program are offered.

Jan 1, 1994

By Taylor G. H

The proposed classification scheme is based on two primary parameters, one for petrographic composition and the other for rank, both being determined with microscopical techniques. The scheme has been applied to a wide range of Australian coals and found to provide a useful means of relat- ing their inherent properties to properties such as volatile- matter yield, crucible swelling number, and calorific value, which will determine how these coals might be used coimierciallyti,

Jan 1, 1969

The total cost of horizontal development can be minimised by optimising the cost of each of the component operations (eg drilling, blasting, etc). Component costs should not be minimised. To optimise blasting results (ie the mean advance per round, muckpile characteristics and overbreak), operators need to optimise the blast design and drilling and blasting procedures. The costs of pulling extremely long (say >6 m) rounds, producing unnecessarily fine fragmentation, and minimising overbreak are excessively high. Operators should continually consider how they can shorten the cycle period by saving time at the face. To enable it to be matched to the pertinent rock properties, the blast design needs to be based on as much relevant experience as possible. To develop the most valid correlation between blasting results and blast design, the latter must be implemented carefully and accurately, but without sacrificing speed excessively. The total cost can often be reduced by using: 1. computer-controlled jumbos (to reduce the period and cost of drilling and to increase drilling accuracy); 2. larger diameter (51 mm to 64 mm) and longer (4.5 m to 6 m) blastholes; 3. at least three large diameter ( ¦89 mm) relief holes that are 0.2 m to 0.3 m longer than the blastholes; 4. explosive products that are selected on the basis of proven reliability and overall cost efficiency rather than price; and5. stemming (to increase the amount of effective work done by each kilogram of explosive and, hence, to reduce the powder factor and possibly the number of blastholes and the costs of drilling and initiation). Non-perimeter blastholes should be charged with ANFO or a bulk emulsion of established performance. Upper perimeter blastholes should be charged with a bulk explosive with a much lower effective density. But where geology varies considerably, greatest control over overbreak could possibly be achieved with the versatile pre-assembled charge shown in Figure 1. This paper presents numerous potential ways in which the total cost of development can be minimised. It concentrates on recommending blast design features and the safe, rapid, cost-effective implementation of designs.

Jan 1, 1998

By Rosengren KJ

Geotechnical conditions often have a critical influence on the design of new open pit and underground mines, but they are often considered of secondary importance in relation to other factors, such as detailed geology, orebody geometry and grade distribution. As a result, geotechnical studies may not be carried out during early project investigations or, at best, may be given only superficial attention, often to the overall detriment of the project. Technically and economically, it is logical that geotechnical studies should be integrated with geological investigations as soon as it becomes evident that the particular deposit may prove to be economic. The paper discusses the use of geotechnical information in the selection of mining methods and mine design for underground mines and for wall design and assessment of excavation characteristics in open pit mines. It then considers methods of obtaining the relevant data, with particular reference to exploration boreholes. Selected case studies on the application of geotechnical data to mine design are Included.

Jan 1, 1986

By Seymour C. A

Peak Downs Mine, a five million tonnes a year coking coal operation, strip mines a, series of Permian coal seams. Seam thickness ranges from 0.5m to 5.0m, and seams consist of multiple coal plies with intermediate shale and mudstone partings. Four 47m3 draglines strip overburden to a cover depth of up to 60m. Coal loading is by 12m3 shovels and 14m3 to 18m3 front-end loaders. Parting removal takes place where the layer of shale and mudstone between seams exceeds 0.3m in thickness. Parting has been removed by a wide variety of earthmoving equipment in order to evaluate the problem and to select the optimum method from an operational and economic standpoint. Multi-seam stripping of the thicker seams is accomplished by working draglines from spoil- pile benches. Coal seams thinner than lm are recovered by dragline and stacked in the pit for later loading.

Jan 1, 1974

By K Saito, M Hasegawa

Removing sulfur and phosphorus from molten iron can be expressed by the following reactions, respectively. [S]Fe + (O2-)slag = (S2-)slag + [O]Fe [P]Fe + (3/2) (O2-)slag + (5/2) (FeO)slag = (PO43-)slag + (5/2) Fe(liquid) These equations indicate that desulfurisation and dephosphorisation have opposite oxygen potential conditions. If a small amount of desulfurisation slag not removed is carried over to dephosphorisation process, the reaction of sulfur mentioned above proceeds toward left hand resulting in increasing sulfur content in molten iron. For better understanding of such re-sulfurisation reaction in hot metal pre-treatments, the present study aimed at evaluating the effect of iron oxide on the sulfur distribution ratio between slag and hot metal. To measure sulfide capacities and FeO activities simultaneously at temperatures below the melting point of pure iron, CaO-SiO2-FeO and CaO-Al2O3-FeO ternary molten slags were brought into equilibria with copper-iron-sulfur liquid alloys, and the equilibrium oxygen partial pressures were determined with an electrochemical technique involving the stabilised zirconia solid electrolyte. The experimental results showed that the sulfide capacity increased with an increase in FeO content, and this trend was consistent with the fact that FeO was basic. Although the addition of FeO raised the FeO activity and oxygen potential, the calculated value for sulfur distribution ratio between slag and hot metal increased with increasing FeO content.

Jun 19, 2024

Dartbrook mine is a new greenfields thermal coal longwall mine located n the Upper Hunter Valley ten kilometres north of Muswellbrook Figure 1). Construction began in April 1993 with coal extraction starting n October 1994. Longwall production is scheduled to commence in the first quarter of 1996 with production expected to exceed 3.5 million onnes per annum. The permanent workforce will number 150 full-time ,mployees and productivity rates will be 22 000 per employee per annum m a ROM basis. Being a greenfield site Dartbrook has had the opportunity to develop and operate the mine using the best practices and latest technology available to meet high standards of safety, quality and production.

Jan 1, 1995

The Beaconsfield Gold Mine within the township of Beaconsfield in northern Tasmania has been established in recent years to exploit a known resource in the Tasmania Reef which was mined to a depth of 450 m below surface between 1877 and 1914 yielding 850 000 ounces of gold. Activity at Beaconsfield over the past 30 years has involved drilling to assess the resource and rehabilitation of the top 100 m of the Hart Shaft that had collapsed since the original closure. More recently the mine has been dewatered to the 375 m Level and work is well advanced establishing infrastructure aimed at recommencing production during 1998 - 99. This paper reviews geotechnical studies undertaken to-date and provides a brief overview of some practical methods of analysing ground conditions. It pursues simple observation and analysis as a tool for assessing mine design and ground support options without recourse to extensive monitoring and measurement and avoids the use of elaborate models before the basics are understood.

Jan 1, 1997

By Gibson G, Jaques L

The Broken Hill Exploration Initiative (BHEI) is a collaborative venture between the Australian Geological Survey Organisation (AGSO), Mines and Energy South Australia (MESA) and the New South Wales Department of Mineral Resources (NSWDMR) to provide a new generation of geoscientific information to promote and enhance the exploration for, and discovery of, new deposits in the Broken Hill region. The area under investigation (Figure 1) exceeds 150 000 square kilometres on either side of the NSW-SA border and is centred on the city of Broken Hill. N.T. I I OL n. WA 8A I Maw. AC,7 !ii oFCU vlc~ ~T. Fia I - Nlap showing the 150 000 square kilometre regwa,. i.i lcr investigation by the Broken HiII Exploration Initiauvr highlighted on the map of Australia. A major impediment to the exploration for, and to the understanding of, the genesis of the world-class Broken Hill Pb-Ag-Zn deposit is the structural and metamorphic complexit\ of the region. Important objectives of the BHEI are therefore: I. the definition of the three-dimensional structure of the province, 2. the deformation history, and 3. the stratigraphic and age relationships of the rock units. Early discussions between the BHEI partners and industry scientists revealed that new geophysical surveys would be a key requirement to help advance the understanding of the province, especially a contiguous high resolution airborne geophysical dataset covering both outcrop and areas of shallow surficial cover. The purpose of this paper is to draw attention to the new high resolution airborne geophysical data and to discuss their interpretation and potential for enhancing the knowledge of the Willyama Supergroup geology.

Jan 1, 1997

The mining of mineral sands in coastal aquifers is often constrained by other land use conflicts and inappropriate controls imposed through a lack of understanding of environmental interactions and processes. The recent experience with the Tea Gardens mining operation illustrates how increasing our knowledge and understanding leads to more effective management of environmental problems. As well as a source of heavy minerals, the Tea Gardens sand bed serves as a town water supply source. From past experience it was believed that mining could cause undesirable increases in dissolved iron concentrations in the aquifer, but the reasons and mechanisms for this phenomenon were not clear. A water monitoring program was therefore designed for the mining operation which was aimed at protecting the water supply borefield from any detremental effects. After one year the results of the monitoring program were assessed in the light of new knowledge and understanding of iron hydrochemistry. It was found that the existing program was not achieving some of its major aims, and was therefore modified to a more effective and cost efficient program.

Jan 1, 1988

The twin iron ore islands of Cockatoo and Koolan are located in the spectacular setting of Buccaneer Archipelago off the Kimberley coastline of WA.Cessation of ore shipments from Koolan in 1993 ended 42 years of continuous mining activity which began with the first shipment of ore from Cockatoo in 1951.

Jan 1, 1993

Drill and blast operations account for 12 - 15 per cent of total mining costs. This paper looks at a comparison between electronic detonators and non-electric detonators, focusing on the cost benefits associated with the high precision of the timing sequences of electronic detonators. An analysis of the total mining costs was made on two main case studies; one on a quarry in South Australia (Martin, 2007) and the other on a project undertaken at Sunrise Dam (Vaughan et al, 2007). The criteria used in the analysis included; the resulting fragmentation, a vibration analysis, crusher throughput and productivity analysis such as excavator cycle times, dig rates of the excavator and bucket fill factor. The results indicate that there were consistent production improvements and hence reductions in total mining costs attributed to the use of electric detonators. An increase in the degree of fragmentation gives lower crushing costs as more material passes through as undersize. This reduces truck delay time at the crusher, which in turn gives higher truck and shovels productivity as well as higher dig rates for the excavators.

Jan 1, 2008

By Restarick C, Jowett A

A cylinder-cyclone system, fitted with a flow control valve between the cylinder and cyclone plus in some tests a variable cyclone spigot, has been used to achieve classifier separations at unusually coarse sizes relative to the diameter of the units used. The method has proved to be useful for low tonnage flows at low pulp density and variable feed rate. The system relies on use of a cylinder unit to reject excess water and fine particles, the amount rejected being adjusted by the flow control valve. The valve also adjusts flow rate and pulp density of feed to the cyclone unit, and can be adjusted to give a separation at a coarse particle size. The system has been used in connection with experiments on the pilot plant at Mount Isa, where a 76 mm system was used to classify feed to the lead secondary rougher circuit at sizes as coarse as 52 micrametres galena equivalent for split conditioning tests. Further tests have been carried out with quartz to assess the range of size separations Possible.

Jan 1, 1978

Since 1958 there have been 16 major coal mine explosions in the U.S. claiming 323 lives. Whilst the exact cause of a number of these incidents has not been determined, the majority has involved gas ignitions in one way or another. In addition there have been fatal gas explosions in salt mines and vapor explosions in oil mines. Furthermore, many of the oil shale mines in the U.S. have proven to be gassy giving cause for concern. Compounding these problems is the fact that frictional ignition of methane in coal mines has dramatically increased over the past several years; over 100 such ignitions were reported in 1979. While, no fatalities have been attributed to frictional ignition in the U.S. since early 1978, a recent mine explosion in Nova Scotia which resulted in 11 fatalities was attributed to a frictional face ignition. Research being conducted at the Bureau of Mines is aimed at the prevention and suppression of gas explosions. Emphasis is placed on new coal cutter bits for reducing ignition frequency, machine-mounted water sprays for preventing frictional face ignitions and automatic devices for quenching incipient ignitions and fully developed gas explosions.

Jan 1, 1981

By Gooday PE, Brech GE

Ore reserve categories used by Pancontinental Mining fall into one of three fundamental groupings: Geological In Situ Reserves Mining Reserves Production Estimates The first of these describes the total reserve within stated parameters without implication as to its mineability. The second is that part of the Geological In Situ Reserve which is considered mineable under a specific mining plan. The third is the Mining Reserve adjusted with appropriate dilution and recovery factors and thus represents the best estimate of the tonnage and grade of production. This practical three category system mirrors the standard steps traditionally taken in ore reserve estimation and readily conveys the basis of the estimates. An important, but secondary classification can be added to qualify the level of confidence in these estimates using the terms: Proved (or Measured) Probable (or Indicated) Possible (or Inferred) These terms can be applied to any of the fundamental groupings, but it is generally implicit that the level of detail required to produce meaningful Mining Reserves or Production Estimates would require the basic Geological Reserve to be at a Proved or at least Probable level of confidence. The application of these classification systems by Pancontinental is illustrated by reference to the Paddington Gold Project. The methods of calculation are described including the use of geostatistics. Reconciliations of actual production with predictions from reserves are carried out monthly and annually. To date there has been an excellent correlation with Production Estimates, based on both manual and geostatistical calculations.

Jan 1, 1987

By A C. Robertson

Over the past decade there has been continual change in the way that mines have been managed and the component roles of those people who make up the total mine management system. Major issues have included the change in the business structure of mining companies, the change in on-site infrastructure, increased personal liability of managers for the safety and health of employees and increasing social and environmental pressures on managers and their staff. This paper looks at the changing roles of two of the many groups of professionals associated with the mining industry - the equipment supplier and the mining consultant. The profiles of the ACME Group Pty Ltd, suppliers of ventilation equipment and ancillary canvas and plastic products to the mining and construction industry, and Tennent, Isokangas Pty Ltd, Consulting Mining Engineers, are presented.

Jan 1, 1998

By Iwu GO, Almond DP, Joasoo _

The gravimetric integral Knudsen effusion method was used to measure cadmium activity values in binary liquid In-Cd alloys in the range 523 to 573 K. The activity measurements together with other studies from the literature indicate that special bonding conditions exist in the melts near a composition corresponding to InCd3. Sound velocities in In-Cd melts were also measured using a precision pulse-echo over- lap method in the range 404 to 953 K. The frac- tional deviation of experimental and ideal isentropic compressibilities at 623K shows a functional dependence on composition with a pronounced maximum near the composition 75 at.%.

Jan 1, 1980

By D R. Wines

The design of near-surface civil infrastructure requires detailed consideration of the geological/ geotechnical conditions, excavation geometry and sequence and ground support measures to ensure stability of the underground openings and minimal impact on overlying or adjacent infrastructure. Twin parallel road tunnels have been designed and built with connecting cross passages and a piggyback busway tunnel as part of a large infrastructure project in Australia. The tunnels were excavated in poor to fair quality rocks using road headers. Temporary ground support includes shotcrete, rock bolts and canopy tubes. Extensive numerical analyses have been performed to analyse the expected behaviour of the tunnels during excavation, including two-dimensional analyses using UDEC and three-dimensional analyses using FLAC3D. Structural defects in the rock are explicitly included in the 2D analyses to examine the potential for localised ground instability. The stress redistribution is captured by the 3D modelling with an accurate representation of the complex excavation geometry and the detailed excavation and support sequence. This paper presents the modelling methodology, numerical results and discussions on integrating both 2D and 3D analyses to achieve reasonable design.

Mar 8, 2011

By Eggleton R. A, Taylor G

As the search for major orebodies continues, the regolith dominated areas of the Broken Hill region remain one of the major exploration frontiers. The past exploration philosophies emphasising bedrock related characteristics have been limited in their ability to effectively explore in the regolith dominated areas, that are a feature of most of the Broken Hill region (Figure 1). If mineral exploration is to be more effective across all of the Broken Hill region, particularly in the regolith dominated areas, an appreciation and increased understanding of the regolith and landscape features are a necessity. Ironically, there have been very few studies of the regional regolith and landscape features of this region. Owing to the previous lack of an established regolith-landform framework, this study initially concentrated on the general characterisation and variation in regolith types corresponding to the area of the Broken Hill Block, within NSW (Willis, 1989; Stevens, 1986). The approach has been to produce a regional regolith-landform map at 1:100 000 scale and conduct a complimentary program of regolith sampling and site descriptions. This was a basis to identify areas for more detailed regolith-landform mapping (1:25 000 scale) and for producing a regional stratigraphic framework and models for landscape and regolith evolution. This information can then be used to provide a basis for regional mineral exploration models and strategies. This paper highlights some of the regionally significant regolith-landform features and their general significance to mineral exploration. More detailed information on specific regolith-landform features and study sites may be found in Hill et al (1994; 1996; in press) and Hill (in prep).

Jan 1, 1997