Search Documents

By B Johansson

The mining industry needs to recruit young talented people. An important task therefore, is to create future attractive mining workplaces that engage and motivate young people to work within the industry. Our intention with this article is to illustrate a possible way forward for the mining industry to form such workplaces. We discuss different aspects of an attractive workplace and summarise our findings in a specification of basic demands dealing with safety, physical and psycho-social work environments and social responsibilities.

Nov 22, 2011

By Roberts C

The satisfactory testing and characterisation of mineralisation amenable to heap leaching, is of prime importance to successful operation of a project. This paper outlines a methodology for assessing material suitability. A general model is used for classing material types for suitability for treatment and for economic analysis. The four levels of these are overburden, oxide, transitional and unoxidised materials. During exploration, reverse circulation (RC) drilling can be used effectively to define these zones by a combination of logging, analysis and provision of cuttings for column leach and bottle roll trials. RC cuttings can he used effectively for column leach trials, when calibrated against conventional processing-sized samples, obtained from surface. Tbis allows metallurgical testing to depth and definition of transitional ore types and the base of oxidation, accurately and economically with an acceptable density of samples. The accurate prediction of base of oxidation and variations in recovery with depth and ore types can be used to develop 'economic' pit designs with zones of variable recovery. Petrological studies of leaching results and examination of mineralisation types carried out on concentrates, provide information on gold distribution and physical and chemical constraints. The examination of concentrates can be particularly useful for types of mineralisation when overall gold content is frequently at or below one pan per million. Explanation of anomalous recovery of gold grains in dense goethite and solution-robbing by carbonaceous material can be identified by use of petrological and scanning electron microscope. An understanding of the role of the host rock in leaching characteristics can also he provided by petrology where siliceous or clayey materials can require significantly different treatment.

Jan 1, 1994

By Kaleta S, McTavish LP, Turner RD

Primary production blasting at Hamers- ley Iron began with seven inch holes at Tom Price in 1966 and has developed since then to large multiple row shots of 381 mm holes at Tom Price and 311 mm at Paraburdoo. Up to 1.3 million tonnes are initiated in a single blast with the average around 300,000 tonnes. Development can be traced through Anfo, AlAnfo, slurries, various boosters, initiation and delay techniques, hole loading and daily operating practices. A standard practice could be developed for the two mines for normal pro- duction blasts; this would not apply to such common variations as low "paddy" shots, pre- splitting, tight corners necessitating single row drilling etc. Because of ground variation three or even four sizes of drill holes may well be economic- al for blasting, even though this would be off set by complications in operation, supervision, store stocking and maintenance, particularly in Drilling.

Jan 1, 1978

By Rongqing Q, Tiancong Z, Yiyuan L

The influence of pulp density, ferric ion concentration and particle size on the tank bioleaching of two kinds of refractory gold concentrates are discussed. The chemistry and mechanism of the bioleaching process are also presented. The relationship between oxidation of sulphides, liberation of enclosed gold and gold cyanidation are discussed. The consumption of NaCN could be reduced by alkaline treatment of bioleached residues prior to Cyanidation.

Jan 1, 1992

This paper discusses a number of examples of how environmental factors have been incorporated into the water management aspects of mining projects. One example is the Kingston Lignite Project in the South-East of South Australia where the most significant environmental issue was considered to be the effect of drawdown from mine dewatering and depressurization upon the use of groundwater. By proposing an alternative mining method - the use of floating dredges rather than a two-pass dragline method - drawdown effects would no longer be a concern. A second example is the Pine Creek Gold Mine in the Northern Territory. In this case the principal area of interest from an environmental viewpoint was water management - in particular effluent disposal, contaminated seepage from overburden and tailings, and project water supply. Through an integrated approach to the management of wastes and water the potential for water quality impairment was significantly reduced and external water supply requirements were also significantly reduced.

Jan 1, 1987

By Muge F, Pereira H

In the early stages of the planning of a new exploitation, the error in ore reserve estimation is an important factor that must not be disregarded. As this error can be computed by geostatistical methods, the risk of the venture can be calculated for different recognition patterns in a certain assumption of economical conditions. A case story is described for an open pit phosphate deposit in which grade/tonnage curves and their confidence intervals are related to an economic function for three drilling patterns and decisions are taken on the basis of cost and value of supplementary information.

Jan 1, 1977

By Crawford M

During the initial development of Mount Isa Mines power was supplied from a temporary power plant situated near the Man & Supply Shaft. The main power plant was placed in service early in 1931 and then comprised two Babcock and Willcox boilers, fired by pulverised fuel, and two British General Electric Company's turbo-alternators of 5,000 kW. each. Both plants have been described by A. F. McAskill in the Journal of the Institution of Engineers, Australia.From 1931 power demand progressively increased due to greater production, further mine development in the harder sulphides increased pumping for mine drainage and additions to mill and smelter until, by 1935, the plant was inadequate for further output commensurate with a reasonable safety margin.Coincident with the added power demand, operating conditions involved a fuel problem which could not have been anticipated. The ash content of the fuel supplied gradually increased from 13% to 16-5%, while the melting point of the ash decreased with higher pyrite content.Temperature conditions in the furnace required careful control to cope with ash formation and slag accretions.Consequently brickwork, excessively stressed on water walls, was constantly under repair, and required suspension periods of 50% of operating time for cleaning and overhaul.Load conditions varied continually, therefore the high heat liberations in the furnace, necessary to accommodate peaks in fluctuating output, resulted in ash fusion.

Jan 1, 1939

By Green GR

Description of two methods developed at Sulphide's Cockle Creek Plant as part of a site energy reduction program. The two case studies are:

Jan 1, 1985

The impulsive loading tests under confining pressure were performed to investigate the dynamic fracture properties of rocks in a triaxial stress state. The apparatus in this study consists of the Split Hopkinson pressure bar, a pressure vessel and hydraulic actuator. Magnetite-quartzite and limestone were selected for the test. The stress-strain curves and fracture strength under confining pressure obtaind in the tests were compared with those of the conventional triaxial tests. Finally it is concluded that on the effect of dynamic that on the effect of dynamic compressive strength of rock, dynamic elastic coefficient of rock and confining pressure etc. on the blasting result

Jan 1, 1990

By C J. Corbett

Many underground mining methods rely on blasted rock moving under gravity to report to extraction points. Mining of orebodies dipping between 20 - 45 degrees poses a unique challenge for mining engineers in that a dip angle in this range will not allow the movement of broken ore down the footwall to the mucking horizon utilising gravity. This is more so in cases where the natural angle of repose of the rock is less than the dip of the orebody. Hence, innovative mining systems are necessary to mine this type of orebodies. In Australia, the method of uphole retreat panel stoping is commonly used to extract orebodies in the dip range of 20 - 45 degrees and thickness range of 5 - 15 m. In the Zambian Copperbelt a method called continuous retreat updip stoping is used for orebodies with similar dips and thicknesses. The mechanised form of this mining method has potential for application in the metalliferous mining industry in Australia. In this study a comparison is made between mechanised updip (MUDS) and transverse retreat stoping (TRS) methods. A hypothetical nickel sulphide orebody located in Western Australia is used as case study. The net present value for mechanised updip stoping is seven per cent higher than that of transverse retreat stoping based on the assumptions applied. Initial results of this study indicate that mechanised updip stoping can be adopted for Australian mining conditions. However, lack of significant local experience with the method is often cited as a reason for not adopting it even in situations where it is clearly the best option.

Jan 1, 2003

By Quast K. B

The effects of metal ion addition rates and contact time on the activation of synthetic sphalerite using copper, cadmium and silver ions were determined in order to investigate the exchange characteristics at the mineral surface. The stoichiometry of the adsorption indicated that the activation of sphalerite involved both a simple ion exchange and redox process in which the activating ion and oxygen were reduced, and the mixed-sulphide surface was oxidised to produce elemental sulphur and a metal-deficient sulphide surface. Unactivated sphalerite was shown to be relatively hydrophilic, with recoveries usually less than 20 per cent for a five-minute float. Activated sphalerite could be readily floated without the use of a conventional collector. This inherent flotability of the activated sphalerite had previously been associated with the formation of a metal-deficient sulphide layer; however, this study emphasizses the significance of the surface oxidation processes occurring.

Jan 1, 1993

By C Kocsis, G Baiden, Y Bissiri

CANMET-MMSL and Penguin Automation Systems Inc have been exploring how process simulation and ventilation modelling software, when combined, can be used to optimise hard-rock/metal mine ventilation systems. In combination, it is anticipated that this methodology will facilitate the exploration of mine design options that affect ventilation requirements and ultimately cost. Such integrated mine design could limit, and possibly reverse, the drivers that under current practices would generally dictate increased ventilation, power consumption, cost and greenhouse gas emissions. It is believed that the mining industry needs such process models to develop better business cases. For example, the implementation of optimised ventilation systems will undoubtedly require significant investment and mines are often reluctant to try such conservational measures unless they can be proven cost-effective. In general, Canadian hard-rock mines know their ventilation systems are providing too much air and consuming power unnecessarily. This is because their systems are designed to provide maximum production flexibility, based upon peak demand, which may be at some future time, and operated continuously at that level regardless of actual need. Simplistic analyses have shown electrical energy savings can range from 30 per cent through to 90 per cent (Hardcastle, Gangal and Leung, 1998). These savings depend upon such factors as the intensity and continuity of the production schedule as opposed to non-productive time. Where these savings occur is also important, if limited to either the primary or auxiliary ventilation systems, they could be negligible in a mineÆs total energy consumption. The problem these mines face is determining what level of ventilation is required in real-time and then the relative benefits. Such parameters as varying electricity costs, heating fuel options, different design criteria and their complex inter-relationship can effect the selection of an optimal system, depending on whether energy, environment or cost is the prime driver. The use of process simulators in underground mining is in its infancy; to date they have been used to show the benefits over the life of a mine under different mining methods, such as a comparison of tele-remote mining from surface against conventional manned operation (Baiden, 2000). This ongoing development advances the use of such simulators into a new and potentially important area, namely modelling the life-cycle ventilation requirements of a mine. This paper shows how such a life-cycle analysis as opposed to peak demand can provide the basis for optimising the design of ventilation systems and their control.

Jan 1, 2005

In 1953, Dr N Fisher of the Bureau of Mineral Resources, acting on behalf of the Society of Economic Geologists, which is considering the sponsoring of a uniform system of nomenclature for ore reserves, enquired from The Australasian Institute of Mining and Metallurgy whether it had ever considered this subject and particularly whether it had ever set up any standard definitions or specifications with regard to ore reserves.As this had not been done, but was thought to be desirable, the Council of The Institute appointed a Committee consisting of H H Dunkin, Associate Professor of Mining Engineering, University of Melbourne (Convenor); E A Rudd, Professor of Economic Geology, University of Adelaide; J D Campbell, Chief Geologist of Western Mining Corporation; and the writer, to consider the report on this subject.In December 1953, the Committee submitted its frrst report to the Council and this report (reproduced here as an Appendix) was widely circulated among member companies and engineers, with an invitation to comment on the proposals. A large number of replies was received and studied.After studying the replies the Committee issued a second report, in part as follows:From these replies we have learned that the suggestions made in the frrst report of the Committee are unacceptable to most of those interested, on one or all of the following grounds:a. number of categoriesb. defmition of categoriesc. nomenclature.It is also apparent that all alternatives suggested in the various replies would likewise be unacceptable to the majority of those replying.As a result, we have come to the conclusion that neither this Committee nor any other could at present and in the present state of opinion on the subject make recommendations regarding classification and nomenclature of ore reserves which would be acceptable to a sufficiently large proportion of members.It seems to us now that the objective of a widely applicable and acceptable system of classification and nomenclature, one that could be endorsed by The Institute and ultimately become standard practice in the industry, requires more than compromise between present conflicting views... it requires first a foundation of substantial agreement on the essential facts, implications and range of ore reserve estimation. This does not yet exist and it is evident that much additional analysis of present practice and opinion must be undertaken before any further systhesis is attempted.

Jan 1, 1994

Blasting is known to be both an important and an easily quantified cost factor in rock breaking operations. However, the indirect costs and benefits of the blasting operation are not easily determined due to the irreversibility of the mechanisms involved and the multiplicity of influencing factors. A general conceptual model showing the relationship between blasting and mining costs is well known, but serious attempts to address the critical real relationships have all floundered on the fact that not enough is yet known about either detonation physics or blasting effects. This can only be remedied to the extent that blasting instrumentation enables researchers to pin down not only the relationship between the detonation process and its impact on a particular environment, but also the downhill costs of handling the rock, repairing any damage and building in "Safety Factors" to provide for imponderables. It is vital to standaraize on specifications for instrumentation and measurement techniques and there is a need to review what has been achieved in blasting expertise so as to focus on the most fruitful paths for future work.

Jan 1, 1990

By Thornton D, Firth B, Kojovic T, Brien G, O&apos

Coal fragmentation is a function of coal type and mining process. Each unit step in the mining, handling and crushing chain of coal imparts energy to the material and impacts on size degradation and consequent mineral matter liberation and pla

Jan 1, 1998

By G W. Wilson, C Panidis

Potentially acid forming (PAF) waste rock contained in dumps formed as a result of open cut mining of metalliferous orebodies are conventionally sealed or covered using a near-saturated, low permeability compacted clay layer, protected with a mulch layer and/or vegetated growth medium. The purpose of the compacted clay layer is to limit oxygen diffusion and the infiltration of rainfall into the dump. Where the aerial extent of the PAF waste rock dump is large, or where suitable clayey material is in short supply, it may be difficult to source sufficient suitable clayey material to form the cover. The paper describes a laboratory-based investigation of combining inert waste rock and tailings to form an alternative seal or cover material. The inert waste rock was sourced from the trafficked surface of a non-acid forming (NAF) waste rock dump, with a maximum particle size of about 100 mm. This was combined with NAF thickener underflow tailings slurry in various mass ratios, and the resulting mixtures tested for their particle size distribution, compaction characteristics, soil water characteristics (relationship between suction and volumetric moisture content), and saturated hydraulic conductivity. The mixtures tested ranged in consistency from those dry enough to be compactable, to those with the consistency of wet concrete that lend themselves to placement without the need for compaction. The laboratory test results showed that the suitability of the mixtures as seal or cover materials is very dependent on the particle size distribution of the mixture, with well-graded mixtures having substantial fines performing best.

Jan 1, 2003

By Mirabediny H, Whitchurch K

A computerised simulation model has been developed to select the most suitable digging method of a dragline operation for a given geological condition. The developed procedure uses a geological ore body model as the basis for the geologic database. The simulation selects the most cost effective dragline digging method from a database of various dragline digging methods The database consists of common and innovative dragline methods currently used in Australian open cut mines. A generalised computer package, DSLX, was extensively used to simulate various dragline digging methods. The DSLX software uses predefined functions to build strip geometry, working benches, blast profiles and spoil piles. The outputs from DSLX in form of volumetric, swing angles and hoist distances data are then aggregated with dragline specifications and site time study data to compare productivity of selected digging methods. The result of a case study showed that this procedure lends itself to the 'optimum' selection a dragline digging method for a given coal deposit.

Jan 1, 1995

The mining and resources industry in general has relied on macro separation technologies (greater than 1 micron) through processes which include: ò sedimentation ò flocculation and coagulation screening and filtration ò absorption ò magnetic separation ò chemical leaching and precipitation Essentially, these processes and technologies provide the industry with an effective arsenal to handle most separation requirements to date. Dewatering of solutions is one of the most significant requirements of the resources industry, as practically all mining endeavours use water in their process for leaching, extraction, cooling, dilution or for potable drinking water.

Jan 1, 1989

Economic and technical reasons forced the mining industry all over the world to increase the unit size of mineral processing equipment. in large flotation cells, this development leads to problems in areas of air dispersion and keeping solids in suspension. Outokumpu, an operating mining company, designed and developed a mixing mechanism for large flotation cells at its own concentrators and also studied problems related to tank design. Ideal conditions for flotation can only be achieved if the flow pattern created by the mixing mechanism fits well into the tank configuration and the risk of short circuiting is minimized. In large deep flotation cells, four different zones can be found which improve the behaviour of large cells when compared to small cells. Selectivity is increased and in some cases final concentrate grades can be produced from the rougher cell. The largest units have also been used as final cleaners in some installations. When modernizing old plants by installing fewer larger flotation cells, immediate and substantial savings in power consumption are achieved. Additional power savings are made in pumping costs because of simpler circuit design and decreased circulating loads

Jan 1, 1978

By Milawarma E, Cusack C

The Sapan Dalam coal deposit of Indonesia consists of ten steeply dipping seams with thicknesses varying between 0.1 and 3.5 m and split by shale, clay, silt and sandstone. The area contains four faults dipping about 75¦ with four to 85 m vertical displacements. The complex nature of the deposit coupled with limited 27 exploration drillholes at an average spacing of 200 m made it difficult to create a realistic geological model. A three-dimensional gridded seam model gave a fair representation of the deposit. Attempt to create an optimum pit using the WHITTLE 3D pit optimiser proved unsuccessful since the pit optimiser is restricted to standard regular or fixed blocks. The gridded seam model was converted to a fixed block model prior to the optimum pit design. Smoothing and pit base controlling were also introduced to obtain a smoother pit. A mining scenario produced 3.6 million tonnes of coal, 28.4 million bcm of waste and US$18.1 million revenue.

Jan 1, 1995