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By Johnson N. W, Manlapig E. V, Alexander D. J, Franzidis J. P

The importance of the froth region on flotation performance is often emphasised in the literature. It is well-known that decreasing froth depth or increasing air flowrate results in increasing cell recovery at the cost of lower concentrate gra

Jan 1, 1997

By A T. Bernardes

Using the cellular automata computational technique it was possible to simulate the generation and discharge of an iron ore pellet pile inside a direct iron reduction oven, as well as to calculate the reduction degree of the pellets as they leave the oven. It allows simulation of the variation of operational parameters and verify the results of those variations in the pellet reduction degree. The simulated data was validated in two instances: for the dynamics of the pellet flow inside the oven it was used in an acrylic bi-dimensional silo; and data from direct reduction iron literature was used for validation of the pellet reduction. The simulated results were considered acceptable to describe the movement of the iron pellet inside the direct reduction iron oven and to describe the iron pellet reduction direct in the oven.

Sep 26, 2011

A novel approach to validate size distributions obtained from bubble sizing techniques is introduced. The experimental rationale consists in verifying whether the output features the anticipated bi-modality when two uni-modal populations (ca. 0.5 and 5 mm) are mixed in a bubble column. The degree of deviation is quantified by comparing the calculated and real proportions on a volumetric basis. A sampling-followed-by-imaging technique was used to proof the concept. The results showed the anticipated bi-modality in which the real and calculated proportions corresponded with a deviation of less than 15 per cent, considered good given the severity of the test. However, the deviation was correlated to the superficial gas velocity (Jg) in the column and was consistently against smaller bubbles. Possible sources of bias are suggested.

Jan 1, 2005

By S Bluhm, R Funnell

Creative mine-designs are constantly being applied in the deep platinum mining industry in South Africa. Recently, this has resulted in deep hot mine-designs including room and pillar, bord and pillar or stall and pillar layouts and the use of in-stope trackless mechanisation. In these mines, the ventilation systems use refrigerated air and high fan pressures and as a result ventilation leakage can have a huge impact. Leakage is a serious impediment to cost-effective operation and potential leakage in future projects is a major factor in judging project viability. This paper describes certain mine layouts and quantifies the extent of the leakage. Based on typical field data, a range of seals from ævery poorÆ to ævery goodÆ was defined and used to estimate overall leakage. Within these mine networks the ventilation pressure, temperature and density all vary significantly and with the multiplicity of leakage paths it was necessary to make use of the VUMA-network simulation package. For the examples examined, the leakage was found to be up to 85 per cent for æpoorÆ category seals and up to 50 per cent for ægoodÆ category seals. The total air flow (and refrigeration) requirements grow exponentially with strike distance due to the compounding effects of higher pressure and more leakage paths. It is shown that beyond certain depths and strike distances the leakage will become so great that it will be impossible to operate cost-effectively û even with ægoodÆ seals. Indeed, in these examples the projects were not considered viable in their original format because of the high ventilation-cooling costs and the mine-designs were modified to include footwall drive systems û the cost of which was justified by the reduced strategic risk to operating ineffectiveness due to leakage.

Jan 1, 2005

By A G. Shellsh, R J. Henham, J R. Foley

The Porgera Gold Mine, west of Mt Hagen in PNG is a large open pit and underground operation currently producing gold at the rate of almost one million ounces per year. This deposit has produced some 8.8 million ounces to-date and has current reserves of 103.4 million tonnes @3.2 g/t Au. The Porgera Joint Venture has invested over $A1 billion in infrastructure in this project. Technical management of this operation involves the interrogation of some 700 000 metres of diamond drilling, some 50 000 blastholes per year, and very large volumes of laboratory, geotechnical, environmental and production reporting data. Over the past seven years this data has been consolidated into a single centralised, relational database which now acts as the single reference point for all the technical application systems used for surveying, grade control, production reporting, deposit evaluation and modelling. Data transfer to application programs and management systems is controlled by the centralised database, this process at times involving a two-way, real-time, binary data transfer. The benefits of a specialised database application include security and integrity of the data asset, ease of access, and performance in a multi-user environment. This replaced fragmented, inconsistent data sets stored inefficiently as individual, unindexed, variably formatted files associated with the different application programs. Most importantly, the database has allowed mine management at all levels to make timely, confident investment, cash flow and optimisation decisions as it provides the primary link between the deposit and operational data sets on one hand, and the application programs and management and performance measurement systems on the other. This paper discusses the economic value and importance of technical data in terms of the resource asset and the means by which this data is being managed and used at Porgera.

Jan 1, 2000

By J Knecht, R Klymowsky, E Burchardt

The wide spread introduction of SAG mills into grinding circuits 20 years ago was the last development which had a major impact on the design and economics of comminution circuits. Single SAG mills were able to replace batteries of high maintenance and cost intensive crushers in order to achieve high throughput operations. Today, where the head grades of gold and copper ores are falling, there is again a strong need for a significant breakthrough to reduce investment and operating costs as well as improve metal recoveries. High-pressure grinding rolls is the new technology available to meet this challenge. HPGRÆs are state-of-the-art in several mining and minerals applications such as the grinding of iron ores and concentrates, and diamond bearing ores. Reasons for their success in these industries are overall cost reductions and improved product properties achieved by the application of high compressive forces. But these ores are relatively soft, with unconfined compressive strengths up to 150 Mpa.

Jan 1, 2000

By M J. Schultz, R L. Rude, D M. Tomko

The US Mine Safety and Health Administration (MSHA) conducted compliance assistance diesel particulate matter (DPM) sampling throughout the underground metal and non-metal mining industry. Based on that sampling, MSHA identified mines that were having difficulty meeting the DPM limit. To provide further assistance, MSHA then visited approximately 60 of the mines that were experiencing difficulty complying with the DPM standard. As part of these visits, DPM exposures were measured and control technologies for DPM were observed and assessed. Controls consisted of ventilation, clean engines, environmental cabs, alternative fuels, diesel particulate filters (DPF) and work practices. The focus of the follow-up compliance assistance visits was to assess control effectiveness and to make recommendations to mines experiencing difficulty in meeting the DPM standard. At each mine visited, the ventilation controls were evaluated, engine emissions were determined for equipment in use, environmental cabs were examined, and operational practices were noted. Additionally, control technologies, including alternative fuels and DPF were evaluated in several mines. A comparison was made of mine and section airflow to equipment particulate indices. Based on engine emissions, horsepower and operating time, the contribution of individual engine emissions to total emissions was made. Environmental cab integrity, positive pressure and air filtration systems were checked and operational practices relating to DPM exposure were assessed. This paper summarises the preference and magnitudes of controls that were typically used or needed for successful control of DPM. Additionally, results of the assessments of alternative fuels (including bio-diesel and water emulsion fuels) and DPF are presented.

Jan 1, 2005

By H G. Poulos

Prediction of ground deformation caused by soft ground tunnelling is an important problem facing design engineers. The ground deformations are caused by the closure of the gap formed around the tunnel due to the tunnelling procedure and soil intrusion via the tunnel face into the tunnel. There are three different approaches that are commonly used in practice to estimate the ground deformations due to tunnelling, namely, empirical methods, analytical methods and finite element methods. One of the important issues of tunnelling in urban areas is the assessment of the likely impact on adjacent pile foundations of ground movements arising from tunnel construction. The main objectives of this paper are two-fold: first, to assess the available methods to estimate the tunnelling-induced ground deformations, and second, to examine the effect of such ground deformations on adjacent piles. Analytical solutions to predict the tunnelling-induced ground deformation developed by the authors are used in this study. These estimated ground deformations are imposed on the pile in simplified boundary element analyses to compute pile responses. The influence of various factors such as tunnel geometry, ground loss ratio, pile diameter and ratio of pile length to tunnel depth are examined in this study.

Jan 1, 1999

By S Chaudari, T Ren, T Harvey

Management of respirable dust on longwall face remains a challenging issue for mine operators, particularly for the new generation of thick seam longwalls. A fundamental understanding of the airflow behaviour around the shearer is critical for dealing with the dust control issue on longwall faces. Computational fluid dynamics (CFD) modelling techniques have been used in this study to conduct a detailed investigation of the air and respirable dust flow patterns around the longwall shearer. Three CFD models have been developed to represent different longwall cutting heights. The results of these modelling studies tallied well with field measured airflow data from different mines. The validated thick seam longwall face model was then used for detailed parametric studies to simulate the effect of various parameters and dust control concepts. The dust control options investigated include various spray configurations, shearer clearer, modified cutting sequences and shearer scrubbers of various capacities to minimise the respirable dust migration towards the walkway area of the longwall face. This paper presents a summary of the results of these CFD modelling investigations.

Jan 1, 2005

The history and milestones in the evolution of support systems utilised in the mass-mined chrysotile mines of Shabanie and King are discussed in detail. The use of block caving, false footwall or sublevel caving mining methods brings with it some major support problems, which are exacerbated, in our low rock strength mining environments. The paper discusses the various support elements and systems that have been used successfully or otherwise in these operations. Some predictions for the future of rock reinforcing in our ground conditions are highlighted, in relation to geomechanics, levels of mechanisation and production risk analysis.

Jan 1, 2000

This paper has been developed for æThe Race for SpaceÆ conference. It ranges over various aspects, all of which are within the umbrella of marketing. The question is posed because many engineers, tunnelling and other specialisations, frequently demonstrate an unwillingness to embrace marketing. The accurate reply is probably à ænot an engineer!Æ The paper identifies some of the possible explanations for this reply. The vast majority of the themes, ideas and principles are based on more than 25 years actual experience for the author with Engineers, Tunnelling and other disciplines. This experience has been gained with leading consulting engineering practices; some of the worldÆs largest construction contractors together with other organisations employing engineers in the public, private and tertiary sectors in the UK; US; Europe; the Middle East and throughout Australia and New Zealand. Experience has been gained in design offices; head offices and construction job sites in four contrasting continents. The most significant themes developed throughout this paper are as follows:æLetÆs go and do some ærealÆ work and leave the marketing to others!ÆæMarketing is just a æsoftÆ option and neither technically based nor true management!ÆNIMBY-ism (Not In My Back Yard) so leave well alone!Engineers regularly confuse services marketing -v- product marketing à a useful cop out, or a genuine cry for help?Marketing databasesæLetÆs get rid of the term æsellingÆ and replace it with the more acceptable à and less distracting for tunnelling engineers à 'marketingÆDistinction between benefits and features à in The Race for SpaceSales Comprehension Test, Benchmarking TestJack WelshÆs æmost difficult decision for a CEOÆHarvard Business ReviewÆs (HBRÆs) formula for performanceMany engineers are losing the balance in their lives Sustainable development and engineering æQuality work doesnÆt mean quality serviceÆMajor recommendationsRecommended references

Jan 1, 1999

By MattelmSki M

Outokumpu Harjavalta Metals Oy has been producing nickel since 1962, based on conventional flash smelting technology followed by electrowinning of nickel. In the 1980s, a research project was initiated to develop a converterless direct smelting process to produce matte for further refining in the then existing refinery. The process was tested on a pilot plant scale at Outokumpu's research centre in Pori and was found to be viable. The process was named the Direct Outokumpu Nickel Smelting Process or the DON Process. At the turn of the 1990s, Outokumpu studied various options to develop its nickel business and the Harjavalta operations. As a result of this work, the DON Process was further developed to produce two mattes: low iron matte in the flash furnace to be leached in the existing leaching circuit and high iron matte in the electric furnace to be leached in the new leaching circuit. In Harjavalta's case, it was essential and important that the process could use the existing flash furnace and electric furnace without converters.

Jan 1, 1996

By Thirnbeck M, Sione T, Petrie P, Leach TM, Mori W, Digan K, Harry K

Gold and lesser copper mineralisation are associated with porphyry-related vein systems periph-eral to two separate inferred intrusive centres north of Kainantu, Papua New Guinea (PNG). The intersection of NW trending structures, formed parallel to the Markham Fault, with NE trending transfer structures localise porphyry intrusions, and control vein distrib-ution.The Arakompa veins intrude pre-existing fractures in Akuna granodiorite, located proximal to an inferred porphyry. These veins are characterised by early quartz and later pyrite-chalcopyrite. Gold mineralis-ation is associated with Bi-Te phases in the sulphide veining. At Maniape, en echelon gash veins occur within the imbricate portion of a regional structure. Maniape is a high level carbonate-base metal gold system formed distal to the same porphyry source as Z ?-;4 kmmna

Jan 1, 1994

By J Zhou, X Bi, Y Yan, W Peng, H Yang, D Weng, P Li

Fortescue Metals Group (FMG) fines from Western Australia is a hematite and limonite mix characterised by high crystal water content. Due to its higher supply capacity and lower prices, the Wuhan Iron and Steel Corporation (Group) intended to use more FMG fines in the sinter mix. It is understood that sinter quality is closely related to its microstructure featured by the hardness and brittleness of different mineral phases, the content of micro pores, and trans-cracks. In order to maintain sinter qualities such as tumble index, reducibility and so on at higher FMG fines blend ratios, a research project was initiated to study the effects of the FMG fines blending ratio on sinter microstructure. Research results showed that at higher FMG fines ratios, the hardness of hematite and magnetite were both decreased while the hardness of calcium ferrite showed a tendency to decrease. The number of cracks that were generated during Vickers hardness measurement in various mineral phases decreased, but their length was shortened, and the variation of crack lengths increased. The contents of hematite and magnetite were also reduced and the reduction of magnetite was clearer. Also the content of calcium ferrite and pores rose and the magnitude of the increase of pores was greater. Among all the mineral phases in sinter cakes, the Vickers hardness of hematite was highest within the range of 879 N/mm2 ~ 942 N/mm2, and therefore the decrease of its content in sinter and the enhancement of its brittleness, ie the number of cracks increased, were harmful to sinter strength. In addition, the excessive increase in pores content is also not favourable to sinter strength.CITATION:Bi, X, Yan, Y, Zhou, J, Peng, W, Li, P, Yang, H and Weng, D, 2013. Study of sinter microstructure with various blend ratios of Fortescue Metals Group fines, in Proceedings Iron Ore 2013 , pp 331-336 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By T C. Souza Pinto, M Safari, F S. Hoseinian, D Deglon, L Leal Filhoc

In this study, the effect of hydrodynamic parameters on the iron ore reverse was investigated in a mechanical flotation cell. The work carries out using the case study of Iron ore from Vale in Brazil. The influence of hydrodynamic factors such as froth height, impeller speed, superficial gas velocity and solids percentage were evaluated on the quartz flotation. The results showed that the hydrodynamic conditions have a great effect on the flotation performance, especially on the fine and coarse quartz. The size-by-size analysis of the froth products showed that froth height, impeller speed, superficial gas velocity and solids percentage have a significant effect on true flotation quartz particles. The increase in the froth height decreased the recovery of quartz particles. The increase in the impeller speed increases the recovery of quartz particles to an optimum. The increase in the superficial gas velocity improved the flotation of coarse quartz particles. The increase in the solids percentage increases the recovery of quartz particles.

Sep 18, 2023

By Resta S. A

Energy Resources of Australia Ltd - Ranger Mine is located about 255 kilometres east of Darwin in the Alligator Rivers Region of the Northern Territory. The Ranger project is surrounded by Kakadu National Park which is on the UNESCO World Heritage list. . Ranger Mine operates the largest uranium mine and processing plant in Australia. It is designed to produce 3000 tonnes of uranium oxide per year, but presently is producing a little less than one half that figure due to the depressed uranium market. The safety performance of the employees and Ranger as a whole continues to improve. The lost time injuries (LTI) have significantly reduced from 74 in 1985 to five in 1994. The total days lost due to LTIs have gone from 1543 to 14. These significant improvements have reflected directly on workers' compensation premiums in which a four-fold reduction has occurred. It is estimated that the actual monetary saving to the company is about $1.3 million per year and directly reports to the profit of the company. There is also an obvious and significant reduction in the less quantifiable costs such as the suffering of the injured employees and cost to society. The paper will review the various initiatives introduced and assess their effectiveness. Performance improvement is primarily dependent on the commitment, introduction of various initiatives and the subsequent change in workplace culture.

Jan 1, 1994

By D W. Airey

Frictional rock bolts are widely used because of their low cost. However, they have a thin wall section that makes them prone to corrosion, and they cannot be relied on to provide long-term ground support. It is difficult to assess the capacity after the bolts have been installed as they can only be pulled out if this has been allowed for during insertion. The questions of how long can the rock bolts function effectively and the effectiveness of various surface coatings, which can have significant cost implications are, investigated in this study.A series of accelerated corrosion tests have been performed on frictional rock bolts. The rock bolts, typically 900 mm long, have been inserted into concrete cylinders produced using a styrofoam insert to create the hole for the bolt insertion. Strata rock bolts with four surface coatings have been tested: uncoated black steel, galvanised, enduro (plastic coated) and coated with a proprietary aluminium/zinc alloy. Tests have been performed on two diameters of bolts. Following insertion of the bolts, the concrete cylinders were placed in a large drum filled with saltwater and current was applied to accelerate the corrosion process. The rock bolts were then extracted at various times after the commencement of corrosion. Comparison of the insertion and extraction resistances shows that corrosion initially increases the bolt resistance and that substantial section loss is required for the bolt resistance to drop significantly.CITATION:Airey, D W, 2014. Laboratory corrosion tests of frictional rock bolts, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 257–262 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By W Stange

Assessing the risks in a mining project is a key aspect of project evaluation. This is an exacting and demanding task because of the complexity due to the need to deal with uncertainty over long time periods. The way risks are assessed and managed is critical to the long-term success of the projects and the business. Discounted cash flow (DCF) analysis is commonly used for project and risk evaluation. A discount rate is selected that accounts for uncertainties in the cash flows. However, it is difficult to determine an appropriate discount rate due to the large number of factors that need to be considered and the complex relationships between risk sources. Using a proven framework, ævalue at riskÆ (VaR), this paper proposes to rigorously model and quantify ærisk at sourceÆ. The approach was first employed to assess financial market risks and is now widely used in the banking sector for risk assessment. In project evaluation, all risk sources are identified and estimated separately to ensure the overall project risk is quantified accurately. A bottom-up approach has been proposed. Estimates are first carried out for risk factors at the bottom of the project structure. The assessment is then applied at increasingly higher levels until the overall project risk is estimated. Value at risk is a versatile methodology and can be used in a local or integrated manner. The final value is objective and the calculation steps can be easily justified and followed. Four case studies have been included to illustrate how the proposed approach can assist management in decision-making.

Jan 1, 2009

By Weyer J

Many existing computer planning programs for the mining industry focus either on big mining enterprises with a high production rate or on smaller operations for high value minerals. Big mining enterprises, like the hardcoal company `Ruhrkohle AG' in Germany have their own R&D departments which develop powerful computer programs for planning purposes, partly in co-operation with mining universities. However, there is a remarkable number of small- scale mining operations which are either not able to buy expensive hard- and software or don't have the skills for the operation of extensive software programs. Partly there is also a trend in using rule of thumb calculations rather than computer programs which need a lot of - partly unavailable - data. For this reason a computer program was developed which does not need expensive hardware and software and which can help the planning engineer in the selection of a limited number of possibilities. Until this time the planning engineer established two or three different cases and calculated the results with a pocket calculator. This could last some hours or even some days. Now he or she can use the computer program with a normal PC to compare the cases. All activities are menu-driven. The basis for all, calculations are fixed and variable costs as well as average performance for special activities. The paper gives an example for a possible planning situation in fluorspar mining (originally this program was developed for the fluorspar enterprise Lengenfeld in Germany). It shows the initial situation, the main structure of the program, the input logic and the results. Benefits, limits and possible extensions of the program are discussed.

Jan 1, 1995

By D Macklin, R Hammond, T G. Blenkinsop

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Base metal sulfides at the Currawong volcanic-hosted massive sulfide deposit in the Lachlan fold belt of Victoria, south-east Australia, were formed in the late Silurian, but D2 deformation of the deposit in the Devonian Bindian orogeny was responsible for structural repetition that created the resource. The primary sulfide lenses were stacked by reverse-sense shear zones within a volcano-sedimentary sequence dominated by dacitic intrusions and turbidites. Shear zones were localised along lithological contacts, including the margins of the sulfide lenses. The competent dacitic intrusions did not fold during D2; folding was restricted to the packages of metasedimentary rocks. Overturning occurs within, but not between, the metasedimentary packages. The overall geometry of the deposit is that of a duplex, but the detailed shape does not conform to idealised duplex types, probably because of post-D2 deformation. A significant complicating factor for understanding the deposit, and for resource evaluation, is the dramatic variation in deposit geometry along strike, which may also be due to post-D2 deformation. The present day configuration of the deposit results from constructive thrust repetition of what may have been a single ore lens and destructive along-strike disruption controlled by rheology.CITATION:Blenkinsop, T G, Macklin, D and Hammond, R, 2015. Rheological controls on the geometry of the Currawong volcanic-hosted massive sulfide deposit, Lachlan fold belt, Victoria, south-east Australia, in Proceedings PACRIM 2015 Congress, pp 469–474 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015