Search Documents

By Mitchell G, Clarke C

The high oas emissions which are associated with high production lonowall mining have provided a need to investigate the limitations and reouirements of the various gas control methods. The major relationships between oassiness and various other parameters are presented with computer analysis being adopted to assess the respective correlations. Some of the relationships are studied in detail with emphasis being placed on methods for overcomino the changes in conditions resulting from high production levels. The importance of the various drainage systems which can be adopted to combat high gassiness levels are analysed. Logical and necessary steps are also proposed for gassiness prediction and data monitoring as well as various combinations of gas drainage systems. The gassiness prediction methods which are discussed outline the need for a sound knowledge of the established worldwide methods together with a comprehensive study of the local mining and geological environment in order to develop a system which is adaptable to the changing conditions. This is particularly important in mines where high coal production levels are anticipated and the need for accurate gassiness relationships is essential.

Jan 1, 1988

By Childs G, Ritchie IC

This paper describes the principle and operation of small hydrocyclones for use in the coal, minerals and other process industries. The principles for selecting a hydrocyclone for an application are also discussed. Typic- al uses and installations in various industries are described.

Jan 1, 1984

The Hartley layered mafic igneous complex within the Great Dyke of Zimbabwe contains economically-recoverable quantities of platinum group metals and gold, nickel, copper and cobalt. The recoverable metals are concentrated in a thin gently-dipping stratigraphic unit - the Main Sulphide Zone. The Hartley Platinum mine, jointly owned by BHP and Delta Gold NL, is scheduled to come on stream at the end of 1996 at an initial mining rate of 2.16 million tonnes per annum and will produce approximately 150 000 oz of platinum and 3300 tonnes per annum of nickel, as well as saleable amounts of palladium (110 000 oz), rhodium (11 500 oz) and copper (2232 tonnes).

Jan 1, 1996

By Sheard SN, Tucker DH

Sampling procedures are an important aspect of geophysical exploration survey design. It is good practice that the selection of survey parameters ensures that the signal to noise ratio is optimised, while minimising survey cost.Sampling considerations for any geophysical method include the size of the target, scale of observation, aliasing associated with station and line spacing, nature and extent of overburden, and the presentation of data.As a guide to survey design, the specifics are discussed for three geophysical techniques in common use in mineral exploration; these include the magnetic method, transient electromagnetics and induced polarisation.

Jan 1, 1976

By Sloan GJ, Lysnar RD

Since the of Bergstrand's Geo-dimeter in 1946, and Wadley's Tellurometer in 1956, there have been numerous Electromagnetic Distance Measurement (EDM) instruments produced throughout the world by a variety of companies.This form of measurement has not merely replaced other methods of measurement, but has caused considerable change of emphasis in survey techniques. Major control surveys are now being accomplished using trilateration instead of triangulation. The surveying of open cuts or engineering work may be done in a fraction of the time and, in the majority of cases, to a greater degree of accuracy than with older methods.It is surprising that with this new tech-nology and development of EDM equipment which is compact, easy to use and no longer so expen-sive, no advance has been made in underground surveying. If we look at equipment being used by the majority of mining companies, we see that there have been very few changes since the Second World War. Very little research has been carried out to enable the surveyor to do his work more easily in conditions which, at the very least. are hazardous.

Jan 1, 1984

By L Lorenzen, H Muller

"Every year a large number of projects are evaluated by small listed and unlisted mining companies that are hoping to find the ideal project, which will catapult them from a mining junior status to that of a mid-tier mining company. Usually this includes finding the æidealÆ or ærightÆ orebody and then developing a process which will allow cost-effective recovery of the valuable metals and the production of a saleable product. These dreams are seldom realised and there are a number of good and obvious reasons for this. Issues that are generally high up on the agenda for the smaller companies are: cost of developing a project before the feasibility study stage finding a suitable, or optimum processing technology financing of the project dealing with risk.The most expensive part of the development process for the small miner is often the exploration side of the business and finding the æidealÆ orebody. However, finding the right orebody will not be discussed in this paper. The æidealÆ orebody does not necessarily solve the problems of the mining junior, as much of the uncertainty lies in the process required to recover and produce the final metal product. Once a mineralised deposit has been identified and the grade at least reasonably qualified, the development of a suitable process becomes the driver to convert the deposit into an orebody. This paper proposes that a small exploration company has a very limited opportunity to succeed if it does not do sufficient homework before it identifies the æidealÆ orebody. The risk profile for the small mining company, by its very nature, has to be different to that of a major company and as a result the opportunities often lie in managing different and often new process options, which may be the key to bring such projects on line successfully.CITATION:Muller, H and Lorenzen, L, 2012. Project selection and process development for mining juniors, in Proceedings Project Evaluation 2012, pp 149-158 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

May 24, 2012

By Bronson B

The geotechnical and environmental aspects of heap leaching are very closely tied during design, operations and closure. Potential environmental impacts from heap leaching are mostly due to land disturbance and water quality issues, including both groundwater and surface water. Water quality issues are mostly related to containment design, which is primarily a function of proper sizing of the facilities and site specific liner design. Geotechnical analyses is the dominant discipline in providing cost efficient, operationally effective and environmentally sound heap leach facility designs. Much has been published on geotechnical aspects of heap leach design, for example Van Zyl, Hutchison and Kiel (1988) and Van Zyl (1987). This paper will emphasize a few specific aspects related to the geotechnical and environmental consideration for heap leach projects. These aspects are: ò site investigation; ò containment design; ò slope stability; ò heap flow dynamics; and ò closure design. Design of a heap leach project must consider not only the operating life but also closure and post-closure considerations. As a matter of standard practice, designing for closure is an extremely important concept. Not only is it important for environmental aspects, but experience also shows that projects designed for closure will be overall more economical for the total life cycle of the project. Closure considerations are also important during project feasibility evaluations to ensure that total life cycle costs are evaluated.

Jan 1, 1994

The kinetics of desorption of nitrogen from molten iron were investigated using the electromagnetic levitation technique. The respective influences of gas flow rate and surface active element (S) were examined. A second order behaviour with respect to the nitrogen concentration in the melt prevailed at all experimental conditions. Sulphur had a marked inhibiting effect on the desorption rate. The experimental results on the rates of nitrogen desorption have been interpreted with the aid of a reaction mechanism consisting of a sequence of elementary steps.

Jan 1, 1991

By Blair J. R

A Train Performance Calculator (TPC) is an essential tool in railway operations, as a means of acquiring quickly a precise measure of the performance of the system. Traditionally the TPC was used in the form of program for a large computer. By employing an efficient integration algorithm and tailoring the program to suit the computer system it is shown that it is possible to devise a TPC for a mini computer. The resulting low running costs and flexibility of operation makes this a useful design tool. This TPC was developed to study problems associated with a single track railway operation. It was applied specifically to study the railway operated by the Mt. Newman Mining Co. Limited in the Pilbara region of W.A. to transport iron ore from the mine to the port. The TPC was used to calculate the effects of changes to locomotive power, to train size, to the track and to the amount of traffic. Its accuracy was checked by comparing its performance with that of the actual trains.

Jan 1, 1977

By Gleadow AJW, Foster DA, Kohn BP, Raza A

A large and increasing data base of apatite fission track results from sedimentary and granitic rocks exposed within the southeastern highlands and along the continental margin of Australia provides constraints for the tectonic development of the southeastern passive margin. The fission track results suggest that many regions of the southeastern margin of Australia experienced distinct episodes of relatively rapid cooling during the middle Cretaceous to early Tertiary that can be attributed to the effects of rifting. One cooling episode is middle Cretaceous in age and related to denudation of the southeastern highlands from Tasmania to northern New South Wales between -90-100 Ma. Rocks exposed along the present coast line record a later episode of rapid cooling, which is diachronous and decreases in age northward from -80 to 90 Ma in northern Tasmania to southern New South Wales, -60-80 Ma in central and northern New South Wales, and to -50-60 Ma in southern Queensland.

Jan 1, 1995

By Gillies A. D S, Just G. D

The advancement of computer applications in the coal industry is focusing interest on the presentation of washability data by mathematical functions.The normal method of presenting washability data is in the form of five curves, usually filled by eye or by cubic spline functions. It has been shown that coal washability can be characterised by two basic relations: the instantaneous ash vs relative density relationship and the instantaneous yield vs relative density relationship. In a new approach to the mathematical modelling of the instantaneous ash vs relative density relationship, theapplication of the algorithm to a data set from a mine in central Queensland was successful.

Jan 1, 1991

Today the application of computer programs for planning of mine-ventilation and for safety- analysis of ventilation systems is widespread practice in German mining. The computer program for network calculat- ion, developed at the "Mine Ventilation Testing Centre of the Westfalische Berggewerkschaft- skasse" allows the distribution of airflow and pressure in mines to be calculated. In a physically well founded manner it takes into account the natural ventilation as well as changes of volume-flow in the mine, which both are dependent on pressure and temperature. Compared to an incompressible treatment of the mine air these circumstances are of increasing importance with the increase of depth, air temperatures and fan-pressures'. This especial- ly holds for the calculation of airflows during failures of fans or for assessing the influence of open mine-fires on ventilation. The application of the program is very easy and its structure is made to fit the requirements of practice. For instance it takes into account the fan characteristics of all fans. For each planning calculated air- flows in all mine workings are compared to those of an eligible basic calculation or to measured airflows. In addition for the

Jan 1, 1983

By Wilson CJN

The central Taupo Volcanic Zone is a region of intense Quaternary silicic volcanism accompanying rapid crustal extension. Modem central TVZ is the most frequently active and productive silicic volcanic system on Earth, erupting rhyolite at c. 0.28 m' s'. The rhyolites show no major compositional changes with time, but the total extent of magma chamber zonation has changed with the advent of rifting and crustal extension at c.0.7 Ma. At least 34 caldera-forming ignimbrite eruptions have formed a complex sequence of relatively short-lived, nested and/or overlapping volcanic centres in central TVZ. Taupo contrasts with other large silicic magmatic systems in the exceptionally high frequency, but small size, of caldera- forming eruptions. This contrast reflects the thin, rifted nature of the TVZ crust, that precludes the development of long- term magmatic cycles at Taupo.Within central TVZ, non-rhyolitic compositions have been erupted apparently irregularly in time and space; in particular there is no evidence for a geographic separation of basalts from andesites. TVZ is a rifted arc, but its segmented nature, high thermal flux and voluminous rhyolitic volcanism make it unique on Earth.

Jan 1, 1995

Cut and fillstoping using hydraulically placed mill tailings has become an essential feature of stoping operations in Kalgoorlie. ' Approximately 30 per cent of the total production is currently mined by this method. Fill is prepared by thickening or cycloning and is gravitated or pumped underground. The average pulp density is 70 per cent solids by weight, Recent cost reducing innovations are the use of steel passes, corrugated iron manways, polythene film sealing, and the replacing of vertical cement lined pipes with boreholes. TTTTTI rvr T Trim r l1TT

Jan 1, 1964

At the Nikkel og Olivin nickel mine near Narvik, Norway, Outokumpu has been the operator since 1993. The mine was opened in 1989 and in 1992 Outokumpu commenced operations to secure concentrate deliveries to Harjavalta's nickel smelter in Finland. Annual production is about 740 000 tonnes of nickel ore grading 0.5 per cent Ni, about 25 000 tonnes of nickel concentrate and about 2800 tonnes of nickel metal. All production comes from underground operations which makes Nikkel og Olivin AS perhaps the lowest grade underground nickel mine in the world today. Production is currently from one of two orebodies, which is known as the Western orebody. The Eastern orebody was worked out by 1995. During Outokumpu's operational period the Western orebody has been delineated and taken to production. The underground exploration and definition drilling involved about 15 000 in of diamond drilling, which was carried out during a nine-month period. Following this a feasibility study was undertaken and production commenced. Improvements were made to the mining methods. Previously the mine utilised open pit equipment underground and this resulted in an enormous amount of additional tunnelling. Grade control and ore delineation were previously based on sparse diamond drilling and all geological information was processed manually. The improvements included the use of underground sludge drilling to increase the amount of geological information, the of a new computer system for grade control and mine planning, new automated underground longhole drilling equipment and the of underground mining equipment which reduced the size of the drives. These changes produced a marked increase in the efficiency of the underground Mine.

Jan 1, 1996

By Kasaneva S

The San Cristobal gold district is located 110 km east of the port of Antofagasta, Chile. It contains the San Cristobal gold mine, where Niugini Mining Ltd. commenced a heap leach operation, with initial reserves of 10.1 million tonnes grading 1.34 g/t An, in December, 1990. The San Cristobal district occurs within an upper Cretaceous-lower Tertiary magmatic arc. The main mineralisation occurs within a northwest trending subvertical zone, 1km long and 70-100 m wide, which contains rhyolite porphyry and minor breccia, and is locally termed the "subvolcanic complex". At the San Cristobal mine, most gold mineralisation occurs in subvertical quartz-pyrite veins which were emplaced in dilational sections of an imbricate fault system. The bulk gold resource comprises four ore shoots which formed where the vein system intersects the subvolcanic complex. Gold-bearing quartz-pyrite veins also occur at separate prospects, the Three Sisters and Sol prospects, west and south of the San Cristobal mine. Hydrothermal alteration consists of potassic and propylitic assemblages related to intrusion of the subvolcanic complex. This alteration is overprinted by a phyllic stage which is associated with the emplacement of the quartz-pyrite veins. The oxide zone is 180 m thick, and contains native gold, electrum, limonite, and manganocarbonates. The underlying hypogene zone contains pyrite with minor chalcopyrite, sphalerite, galena, covellite, bornite, chalcocite, and arsenopyrite. Fluid inclusion studies indicate that the deposit formed at approximately 270¦ C, and the mean salinity of the fluid was 4% NaCl equivalent. These observations enable the San Cristobal deposit to be classed as a porphyry-related, mesothermal quartz-vein system of the low sulphidation type.

Jan 1, 1995

By White A, Price G

The main assets of a mining company are its orebodies; the second are the people who find and use them.The graphs in Figure 1 were derived from a paper by Rob Macdonald of Rothschild Australia presented to The AusIMM Centenary Conference in Adelaide earlier this year. They show that the value of the industry on the Australian Stock Exchange halved over the past decade, despite the re-investment of capital equivalent to its full market capitalisation. Why is this so? The average dividend yields for the ASX Mining Index was never above five per cent during that period and barely averaged 2.5 per cent. Why then is $Ai million capital re-investment per employee since 1960 not enough to generate a rate of return to investors better than lousy bank interest? Do the investing public no longer regard our industry's assets to be world class?

Jan 1, 1993

By S Fidler

Underground coal gasification (UCG) is a process by which coal is converted in situ to a combustible gas that can be used as a fuel or chemical feedstock. The process has been used in commercial-size projects in the former Soviet Union for more than 40 years, while significant national research programs have been undertaken in the United States and Western Europe. The Chinchilla UCG project is located at a site southeast of Chinchilla in Queensland. The UCG operation commenced in December 1999. A controlled shutdown of the process was initiated in January 2002 and successfully completed in April 2003. The process is currently under conservation and ready for restoration of gas production for commercial use in the near future. Groundwater plays an important role in the gas formation process during UCG. Most of the process water required for chemical reactions is usually derived from the coal seam itself and from surrounding aquifers. If insufficient water is available for chemical reactions the UCG gas will contain reduced concentrations of combustible components, and conversely, excessive water influx into the process area would cool down the reactor and thus limit the energy available for gas production reactions. Because of the importance of groundwater in the gasification reactions, and the potential to contaminate groundwater if the process is not correctly controlled, it is essential to predict and to control the groundwater influx into underground gasifiers during and after underground gasification. Control of groundwater requires a thorough understanding of hydrogeological conditions in the vicinity of the gasifier in order to be able to predict inflow rates, and constant monitoring throughout the process of water production rates and groundwater pressure in the coal seam and adjacent aquifers. Hydrogeological testing and groundwater monitoring in the vicinity of the UCG operation commenced six months in advance of its initiation. Monitoring of groundwater pressures in the vicinity of the gasifier have also been undertaken using vibrating wire piezometers installed in the coal seam at varying distances from the gasifier. This paper presents the results of the hydrogeological testing and groundwater quality monitoring carried out at the site, which show that it is possible to operate a UCG process without uncontrolled impacts on groundwater.

Jan 1, 2003

By R Grobler, D Burger, L Alberts

The current climate in the mining industry is allowing mining companies to further broaden their views and investigate technologies to improve the safety, efficiency and cost-effectiveness of their operations. Furthermore, underground mine environments will become more demanding for mining equipment and personnel as orebodies become deeper in weaker ground conditions with more extreme environmental conditions. Loading and hauling can represent significant components of the production cycle of an underground mine and automation of these activities can offer considerable benefits. Sandvik has accumulated a long history and experience in loading and hauling automation in underground mining. Since the late 1980s Sandvik has actively participated in several major research and development automation programs leading to the commencement of the development of an integrated system for semiautomated loading in 1999. Development work was later conducted to expand the capabilities of the system for automated hauling during 2001 and the AutoMine« system became commercially available. The first delivery of the AutoMine« system was completed in August 2004 in South America, where the system continues to operate in a full-scale production environment and is being expanded as the production area enlarges. Further systems have been delivered and are operational in North America, Africa and Europe. This paper focuses on the AutoMine« system deployed in Block 4 at De Beers Finsch Mine in South Africa. An overview of the mine and the process used to acquire the system and the key drivers which led to the selection of an automated solution are described. An overview of the initial system installation, subsequent expansions and future plans are presented. This is followed by a summary of the implementation and operational experiences associated with automated underground operations. The paper concludes by summarising the benefits that have been realised.

Jan 1, 2008

By D R. Seaman, B Adamson, P Sharman, M McMahon

"The Telfer processing plant commissioned its pyrite regrind and flotation circuit in August 2012. The circuit was designed to regrind pyrite concentrate to a p80 of <30µm then float a gold and copper rich concentrate before tails from the flotation circuit fed the carbon-in-leach (CIL) circuit downstream. Expected benefits were: improved CIL performance that would result from the finer grind and a reduction in cyanide soluble copper to the CIL circuit, as well as a small increase in overall flotation circuit recovery. While the benefits of a finer grind were soon realised, recovery in the post-regrind flotation circuit (named the ‘pyrite recleaner circuit’) was consistently and significantly lower than that expected based on laboratory test work. Selectivity in the pyrite recleaner circuit was virtually nil and copper reporting to the CIL circuit did not change as a result of the pyrite recleaner circuit operation.A pulp chemistry survey of the plant and comparison with the lab showed that the dissolved oxygen (DO) demand in the plant was much higher than that in the lab. Lab flotation tests conducted using nitrogen gas instead of air resulted in recoveries similar to those from the plant. It was identified that the freshly ground pyrite surfaces exiting the regrind mill were consuming oxygen in the slurry and there was insufficient oxygen available for collector adsorption and pyrite depression to occur. Test work, using a pilot regrind mill, showed that a reduction in grind size resulted in an increase in DO demand.A range of oxidising agents were tested in the laboratory and using a pilot flotation rig set-up in the plant. Oxygen was found to be the most reliable and effective agent and options for increasing oxygen delivery to the plant were explored. Scale-up from the lab oxygen requirement to the plant is difficult and efforts to implement a permanent solution for meeting the DO demand in the plant are ongoing.Citation:McMahon, M, Seaman, D R, Sharman, P, Adamson, B and Seaman, B A, 2016. Optimising the Telfer Pyrite Regrind Circuit - Effect of Dissolved Oxygen Demand, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 51–58 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016