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By P Hayward a, P Evans, K Prince, F Radke

Operating efficiency is becoming paramount as the mining industry moves towards globalisation and conglomeration. Mining companies are continuously searching for new technologies that can improve plant efficiency, by reducing operating costs and maximising metal recovery. Identification of how gold losses occur within an operating plant is crucial for determining appropriate operating strategies for improved metallurgical performance. Classical mineralogical and metallurgical techniques enable the operator to identify where losses occur in terms of particle size and mineral associations, however how the gold is hosted within the mineral grains (for example, as solid solution or as fine micro-inclusions) is more difficult to determine. This paper provides details of the testwork methodology, and resultant laboratory study to improve gold recovery.

Jan 1, 2004

Particles finer than 10 um often cause problems in flotation. The current under- standing of the nature of the following effects is discussed: slime coatings on particles, carrier flotation, increased froth stability, entrainment of ultrafine gangue, excess reagent consumption, slower rate of flotation, more reactive surfaces. The review emphasizes the principles underlying these effects rather than details of progress in practical solutions to the problems they cause. The princi- ples of selective flocculation and floc flotation and the various approaches to achieving selectivity are discussed. Hydrodynamic effects on floc growth are reviewed. The evidence suggests that satisfactory performance in the ultrafines fraction will be achieved only by simul- taneously increasing the rate of flotation of the ultrafine valuable mineral and de- creasing the rate of entrainment of ultra- fine gangue.

Jan 1, 1984

The problem of spontaneous combustion has long exercised the minds of Mining Engineers. The idea of inertising an area with a non combustible gas has seemed to be an attractive way to overcome the problem. Various agents have been tried but nitrogen has particular attractions and advantages. Britain adopted the idea from the German industry and found that it was particularly suitable for the conditions in British Mines. Over 8 years much development work has been done and specialist equipment has been developed as the requirements came to be better identified with experience. There is a continuing programme of innovation and the technique can be further developed in the future as a means of protecting the very heavy investments which are being made in today's large capacity, heavily capitalised faces.

Jan 1, 1988

By Seshold P

The cost of capital is the rate at which a project's cash flow should be discounted to obtain the Net Present Value. The cost of capital is a weighted average of both debt and equity funds of a company, on an after tax basis. Two methods are described for calculating a company's cost of equity, the Dividend Valu- ation Model and, more importantly, the Capital Asset Pricing Model. A worked example is presented where the cost of capital was obtain- ed for two resource companies. The application of the cost of capital was illustrated by way of a mining equipment replacement problem. The paper outlines refinements and problems that may be encountered with the use of the cost of capital, and concludes that it is an integral part of any project evaluation.

Jan 1, 1983

By D R. Venkatesulu, N K. Nanda

Due to increased production of steel in India, the thrust is now on iron ore producers not only to enhance productivity from existing mines, but to look also into alternative resources, like lean grade iron ores such as banded haematite quartz (BHQ)/banded haematite jasper (BHJ), which are available in abundance but not yet utilised for want of suitable process technology. In this context, BHJ ore from the Bellary-Hospet sector was collected and subjected to detailed physical, chemical and mineralogical characterisation and beneficiation studies. The as-received sample was found to occur physically as alternating layers of haematite and jasper. The chemical analysis of the sample was 41.20 per cent Fe, 39.10 per cent SiO2 and 0.86 per cent Al2O3. Based on the mineralogical observation, haematite was found to be the lone ore mineral and jasper was the major gangue mineral. The microscopic observations revealed that the ore minerals liberate at a top size of 0.150 mm. Guided by the characterisation results, indicative tests were conducted using gravity and magnetic separation equipment, namely, Floatex«, gravity slime table and wet high intensity magnetic separator (WHIMS). The results indicate that it is possible to upgrade the sample by both gravity and magnetic separation techniques. However, the WHIMS results indicate that jasper grains report to the concentrate at higher gauss intensities. Therefore, based on the encouraging gravity separation results and the availability of new design spirals for treating fine particles, the applicability of gravity spirals for beneficiating BHJ in the liberation size range of -0.150 mm was studied. The sample was ground to a top size of 0.150 mm and was subjected to preconcentration using wash waterless spirals. Tests were conducted at different feed rates, pulp densities and splitter positions. The results indicate that it is possible to upgrade the sample from a feed grade of 41.20 per cent Fe to a preconcentrate ranging from 46 per cent to 62 per cent Fe with a yield ranging from 19 per cent to 55 per cent. The obtained preconcentrate was then subjected to a cleaning stage by using a combination of wash water and wash waterless spirals. The test results indicate that it is possible to obtain a final concentrate assaying 65.75 per cent Fe and 4.75 per cent SiO2 with a yield of 25.9 per cent and an iron recovery of 41.31 per cent. It was concluded that further test work is necessary to increase the recovery and improve the product specification.

Jan 1, 2009

The Vera Nancy orebodies, although simple in overall geometry, are in detail generally narrow, multi-veined and fluctuating in width, strike and dip. Tight geological control is required to optimise gold and silver production from this bench stoping operation. The processes used to model the resource and to control ore drive development have evolved since mining commenced in 1997. Grade control is a combination of orebody sampling, geological data collection, understanding orebody geometry and the optimisation of ore driving and stoping activities. Global resource modelling utilises mainly drill hole data which is largely superceded by drive development data as stope development progresses. The orebody has a relatively low nugget effect that assists in grade estimation. Rather than rely on sophisticated grade interpolation methods, resource estimation to-date has focussed on developing the geological understanding of the orebody to ensure the framework for estimation is correct. Drill data alone is not adequate to define deposit geometry for stoping . Drive data is used as the dominant data set for stope geology modelling once development for a stope is complete.

Jan 1, 2000

By A J. Ryan

The Ernest Henry copper-gold Mineral Resource is the major asset heldby Ernest Henry Mining Pty Ltd, comprising A$6.4 billion of containedmetal. The case history presented below describing the evolution andevaluation of this resource generally observes best industry practice and is a good example of effective due diligence in the resource delineation and estimation process. Early reconciliation data from mine production confirms the accuracy and validity of the resource estimate, providing valuable assurance to the mine owners.

Jan 1, 1998

By Bhaskara Sarma P V R

Solvent extraction of cobalt from an ammoniacal ammonium sulphate medium was carried out using Di(2-Ethyl Hexyl) phosphoric acid in kerosene as diluent. The effect of ammonium chloride and ammonium sulphate on the extraction efficiency was studied. The extracted species in the ammonium chloride and sulphate systems were CoAz2HA.NH4CI and CoA3.HA.2(NH4)2SO4, respectively. Ammonia scrubbing and cobalt stripping studies were carried out from loaded and ammonia free organic Respectively.

Jan 1, 1992

By S M. W Rajaratnam, P Varma, T L. Sletten

Mining employees undertaking shift work are at considerable risk of experiencing sleep disturbances and circadian rhythm disruptions. In the complex, high-risk environment of mining, these sleep and circadian disruptions lead to adverse impacts on employee health, alertness and safety. Evidence-based tools that effectively target improvements in sleep health amongst shift workers are needed. Variability in work hours and individual differences in the response to shift work mean that a ‘one-size-fits-all’ solution is often insufficient in complex work environments. Currently no interventions provide tailored support for shift workers based on their rosters, personal commitments and sleep habits. Existing technologies, such as smartphone applications and watches, allow sleep monitoring, but their strategies are targeted towards night sleepers, which does not translate to shift work contexts. To address this, our team has developed an innovative digital tool that implements biomathematical models to provide automated, personalised sleep and circadian intervention strategies to optimise sleep, alertness and performance during shift work. The tool uses mathematical models of sleep and alertness regulation that provide physiologically optimal times for an individual to sleep when experiencing circadian disruption. This program of work included co-designed development of a world-first app with shift workers and the examination of the preliminary efficacy of the intervention for improving sleep, alertness and performance.

Apr 16, 2024

By Wylie A. W, Jarrett R. G

Two versions of a radiometric-type caliper for measuring borehole diameter are described. One, based on the bow-spring principle, is suitable for percussion (exploration) drill holes. The other, which utilizes hemispherical wall contactors actuated by springs, is suitable for blast holes. Both utilize low-power radioactive sources and employ a scintillation detector to measure the "inverse-square law" response of the device to changes in borehole radius. The performance of the device is examined and examples of its use are illustrated.

Jan 1, 1976

Fluid circulation occurs in oceanic crust of all ages, at the seafloor spreading axis, on mid-ocean ridge flanks, in the ocean basins, and in subduction zones. In the first three settings the fluid originates as seawater. At the axis and on the ridge flanks, the circulating seawater produces a major chemical exchange between the oceans and the crust. Based on heat budget constraints, between 10 and 40% of the river flux of Mg can be taken up during high-temperature alteration of the basaltic crust along the mid-ocean ridge axis. Most of the hydrothermal -heat loss, however, occurs on the mid-ocean ridge flanks, where the temperatures are lower and the seawater flux correspondingly larger. The estimated heat loss on the flanks is so large that upwelling must occur over a large fraction (5-30%) of the seafloor less than 65 Ma in age, at seepage velocities on the order of 10 to 100 cm/yr. The circulating seawater need lose less than 1 to 2% of its Mg content in order to solve the Mg mass balance for the oceans. Fluids in subduction zones are commonly less saline than seawater and are rich in methane and other light hydrocarbons. These fluids may originate by dewatering of the downgoing slab. If so, they may close the geochemical cycle of H2O that began with hydration of the basaltic crust at the ridge axis.

Jan 1, 1990

This paper explores options worthy of consideration in the management of S02 produced from the gold roasting operations at Kalgoorlie. Some of the options have relevance to other sources of SO2 in the region, eminating from nickel smelting operations. The paper considers the following options: 1. Capture of SO2 within the roaster where sulphur-containing reaction products are mixed with the calcine. 2. Processes in which the sulphur-containing products are bled separately from the stack for further treatment or for dumping as a waste. These include: Seawater-based scrubbing of SO2; Sulphuric acid manufacture as a feedstock for fertiliser production or for leaching of bauxite; its use as Caro's acid: and the production of value-added sulphur-containing reagents eg liquid S02 and sulphonic acid.

Jan 1, 1992

Silica and limestone fluxing levels in copper smelting slags were studied. Copper concentrates with flux additions were smelted to matte (55.5 per cent Cu) and slag in a pilot scale submerged combustion furnace.Results indicated that oxidic and sulphidic copper levels in slags were minimised with a slag Si02 level of 36 per cent and a SiO2/CaO ratio of 5.5. Total copper losses in slags were 0.6 per cent under these conditions.To produce the desired slag chemistry, additions of bulk silica and limestone to copper concentrates of fluctuating grades were predicted numerically. The method employed the solution of two simultaneous equations, each respectively for silica and limestone calculations.The predicted flux additions were applied in a further series of tests and the resultant stages were found to be satisfactory. The method is applicable to smelting 'operations which employ two flux bins, with weigh feeders, so that slag chemistry may be controlled with the flux/concentrate feed mix.

Jan 1, 1985

By H Han, d S. Hapugoda, L Lu

With the recent rapid development of Chinese steel industry, the world iron ore resources of good quality are depleting rapidly. As a result, iron ore deposits of lower quality have been or are being developed to meet the market demand and are becoming increasingly important to iron and steel companies. As concentrates have advantages of high Fe grade and less harmful impurities, they are ideal sweeteners to maintain sinter grade and quality when high proportions of low-grade ores are used in the sinter blends. However, due to their fine nature, addition of concentrates will inevitably increase the proportion of adhering fines and reduced the proportion of nucleus particles of the sinter blends, which can adversely affect the green bed permeability and sintering productivity. In the present study, lab scale sintering tests were carried out under the conditions similar to the sintering process to examine the effect of concentrates on the high temperature sintering characteristics of sinter blends and the structure and strength of the resultant sinter analogues.

Sep 18, 2023

The SAG milling circuit at Paddington was designed on limited bench testwork and since commissioning with the exception of some mechanical problems has performed well.

Jan 1, 1987

Bakelite is fairly widely known as a suitable material for the mounting of ore specimens, concentrates and tailings for microscopical study, but has not as yet had extensive application. It is the most suitable mount for specimens which are to be held in the mechanical holder of a polishing machine, based on that described by J. W. Vanderbilt*, which is installed in the Geological Department of the Melbourne University.Bakelite products are prepared by subjecting bakelite powder to a temperature of about 1600 C. under a pressure of approximately two tons per square inch for a period of four minutes. The shape and size of the products are governed by the use of suitably constructed dies. When the concentrate or tailing is mixed with the bakelite powder, a briquette is produced which can be polished so that the opaque minerals in the sample can be examined microscopically in the same way as in a piece of solid ore. A simple machine for the construction of these briquettes has been described by Head and Slavin. It consists of a small four-pillar press in which the pressure is supplied by...

Jan 1, 1933

By Colston M. B, Johnson I. D

The importance which matters of social welfare and environmental quality have assumed recently is the underlying theme of this paper. Demands for infrastructure reflect the change in emphasis from economic and technological development to those issues which affect the total well-being of the community. To put the importance of social change in perspective, examples are cited and a theme is developed which underlines the relevance of changes in public attitude and in government policies on mineral exploitation and related development and on the regimen of associated infrastructure sought. Planning on a long term or strategic basis and on a broad scale is put forward as an effective means of identifying changing social attitudes for the purpose of framing government and corporate policies. As a prelude to a section in which a description is given of a novel 'services baseline' concept and its use in the assessment of the current backlog of services

Jan 1, 1977

By M Scoble, R A. Hall

The mining industry has aggressively sought competitiveness through increased productivity and return on investment. A primary strategy has been the pursuit of economies of scale. This has also been dependent upon the implementation of new technology and systems integration. System integration has been accomplished through the implementation of mine dispatch, global positioning and mine wide communication technologies. These technologies have tended to advance at different rates of development and implementation. The result has been that across the industry, and even within companies, mines are at various stages of operational system re-engineering in these areas, driven by improvements in productivity and operational efficiency. Although this strategy has been successful, little effort has been made to analyse change in operational performance in order to understand and model the effects of scale in a quantitative manner. This paper considers the particular impact of equipment scale, together with potential future trends. It then presents and demonstrates a preliminary method to quantify through simulation the anticipated benefits of economies of scale.

Jan 1, 2003

By Sharwood M

Welcome to the morning of the second day of Minval '89. There are some three hundred and fifty of us here today. That represents certainly the most influential gathering of the mining and investment community in Sydney for a very long time, and on behalf of the Institute I bid you all a very great welcome. Due to the pilots' strike some of you have arrived by very unusual methods and others have travelled long distances. So for those of you that have made a special effort, thank you very much. Inevitably some people have not been able to get to Sydney and this has led to some minor programme changes. I'd like to thank our sponsors. Our underwriting sponsors are Energy Resources of Australia, Neil Cole & Associates, Resource Finance Corporation and Robertson Australia Limited, and to those firms thank you very much. To our major sponsors, County NatWest, I would like to say a particular thank you. County is the lead sponsor for Minval '89. They've :made an important contribution to the programme, and we're indebted to them for this support. We look forward to County's continuing involvement in the programme today. County NatWest is a major participant in the Australian equities markets and a growing merchant banking organisation in this country. It's parent organisation, National Westminster Bank, isa leading UK domiciled bank which is also active in Australia. This session is the Pancontinental Mining Ltd sponsored session, and I'd like to record the gratitude of the Australasian Institute of Mining and Metallurgy to Pancontinental for its generosity in sponsoring the session. This morning's session focuses on valuation and follows on from yesterday's proceedings which looked particularly at the impact of NCSC draft Policy Release Number 149. Robert de Crespigny, who was to have been the Chairman of this morning's session, has had some special problems with the pilots' strike.So we have the privilage to have in his stead Michael Sharwood.

Jan 1, 1989

Continuous improvement in environmental management assists in the achievement of sustainability goals for the mining and processing of minerals. The use of regular internal environmental audits (scored or unscored) which form an integral component of an Environmental Management System (EMS), provide demonstrable evidence of this improvement. The audits described in this paper involve working with site personnel to develop and implement major improvement projects, providing advice on how to improve environmental practices and facilities, and disseminating innovative ideas and practices across the site and to other operations within the same group. Essentially the lead auditor assumes the role of a æskills coachÆ as opposed to a æpolicemanÆ, which is quite often the case for many audits. The audit process has been developed from involvement with a number of major coal mines in the Hunter Valley, where regular internal environmental audits have been undertaken every two to three months, over periods varying from 18 months to five years and more recently, with a metalliferous mine in the Northern Territory. Examples of the benefits of improved environmental performance (driven by the audit process) to sustainable development are provided. The auditing process as described is applicable to metalliferous mines, the processing of mineral ores, coal mines, coal handling and preparation plants, quarries, and oil and gas projects.

Jan 1, 2004