Search Documents

By J Krahn

In designing climate exposed soil structures such as caps and covers over mine waste it is necessary to include the wetting and drying influences of the local climate in order to accurately predict the net water, vapour and oxygen fluxes across the ground surface and through the base of the covers. The most advanced evaporative flux modelling tools currently available to practitioners have been limited to rigorous one-dimensional models (ie SoilCover) or semi-empirical two-dimensional models (ie Hydrus-2D). It is common practice to use the rigorous one-dimensional evaporative flux model results to develop a surface boundary function that can then be applied within a saturated/unsaturated two-dimensional model. However, this is not an ideal situation and results in a further approximation of the real system being modelled. This paper will highlight the use of a new modelling tool, VADOSE/W, which brings existing, rigorously formulated evaporative flux theory into the familiar setting of a two-dimensional model. The model is enhanced for simultaneous two-dimensional oxygen gas transport analysis, which has direct application in the mine waste industry. A key focus of the paper will be addressing the limitations of one-dimensional analysis for cover systems on sloping and hummocky terrain.

Jan 1, 2003

By A M. Wala, H W. Wu

A research project incorporating a number of mine site exercises to reduce the effects of fire incidents and possible consequent health and safety hazards has been undertaken focused on the application of mine fire simulation software packages for contaminate tracing and fire modelling in coal and metalliferous mines. This paper examines aspects of introduction of inert gases to underground workings to aid recovery of a mine following a fire. Broad conclusions from work undertaken at individual Australian coal mines are discussed as examples. The effort is built around the introduction of the fire simulation computer program æVentgraphÆ to the Australian mining industry and the consequent modelling of fire scenarios in selected different mine layouts. Case studies have been developed to examine usage of inertisation units and particularly application of the GAG jet engine unit. One example has focused on selection of the best surface portal location for placement of the GAG for most efficient suppression of a fire. A second has examined a situation with significant seam gas being emitted on the face. This has shown that under certain face dip angles stopping the mine surface fan to reduce dilution of GAG exhaust gases will cause reversal of face air and consequent mine explosion as gas laden air is drawn across a fire. A third examines inertisation and dilution issues in mains headings. mains headings present a complex ventilation network with often numerous parallel headings, hundreds of cut-throughs and a variety of ventilation control devices. In such a complex system (with additional interference from a fire), maintaining control of the movement of inert gas is more difficult than elsewhere in the mine. Some illustrations of this issue are given.

Jan 1, 2005

The title of my presentation is `Nursing One's Resources', words that fit a young organisation like Ross Mining and words we had to apply to reach our current level as a company. To get to where we are, we had to nurse, foster and treat carefully all our available resources in the widest sense of the word, namely: ò a stock or supply that can be drawn upon (funds, mineral resources, human resources); ò the means available to achieve an end; ò skills in devising expedients; and ò practical ingenuity. I do not claim that Ross Mining is now the perfect mining company. However, we have become a profitable, dividend- paying, gold mining and exploration company which is to our knowledge, currently the cheapest gold producer on the Australian continent. Nursing our resources got us where we are and will guide us in our future development. The words `nursing one's resources' are I feel particularly applicable to mining-as I like to argue that the extractive mining industry has a social responsibility to optimise the metal output and value from each orebody which is being exploited, and preferably leave no metal behind. Likewise, a modem company cannot survive into the future without maximising and optimising its human resource potential. In this presentation I would like to present a number of actual examples of nursing one's physical and human resources. Before I do that, I will give a brief background to Ross Mining. Ross Mining NL is a young Queensland-based company that gained its stock exchange listing in September 1987 and that poured its first gold in 1989 from its own developed Belyando Mine, located in Central Queensland. We have now reached the stage of a medium-size gold producer, producing approximately 70 000 ounces of gold per year, mainly from the Yandan Gold Mine, also in Central Queensland. Our production is set to increase to over 100 000 ounces in the near future. Recent increases in our resource base have secured us a future of ten to 15 years. As a young, newly listed company, we faced all the dangers that most new small floats do as a new entrant into an established industry. However, one advantage of being young and perhaps naive, is summed up by the following Zen Buddist saying: In the beginner's mind there are many possibilities, in the expert's mind there are few. A mining company's main assets are the sum of its resource base and the skills and talents of its people. Attempting to optimise both the physical and human resources within the company has been to-date the key to our success. The first example I would like to present is linked to the exploitation of the Belyando Gold Mine in Central Queensland.

Jan 1, 1995

By B Godel, E R. Ramanaidou, M Verrall

Fortescue Metals Group Ltd Iron Bridge (IB) operation is a magnetite deposit located in the Pilbara region of Western Australia situated around 145 km south of Port Hedland. This Mesoarchean deposit belongs to the 3230 Ma Pincunah banded-iron formations (BIF), a member of the Kangaroo Caves Formation, Sulfur Springs Group (van Kranendonk, 2000).

Sep 18, 2023

By C Zhang, G Si, J Oh, X Zhu

The presence of rock joints has a huge impact on the strength, deformability, and permeability of fractured rock masses by providing surfaces of weakness on which further deformation are more prone to occur, and by serving as the major channels of water flow due to low matrix permeability. In earlier studies, water flow-through rock joints is often assumed as laminar flow between two ideal smooth parallel plates, and the well-known cubic law was derived and widely used to characterise the hydraulic behaviour of rock joints. However, natural rock fractures are irregular and of spatially varied aperture. Thus, the concept of equivalent hydraulic aperture was introduced to modify the cubic law. Numerous works have been conducted on the relation between hydraulic aperture and mechanical aperture incorporating various geometrical parameters. The surface roughness is one of the most sensitive factors for water flow-through rock joints. The aperture distributions are irregular in natural roughed fractures relative to the parallel plates. Barton et al (1985) and Olsson and Barton (2001) incorporated the joint roughness coefficient JRC in evaluating hydraulic aperture and proposed an empirical equation based on fluid flow tests. However, their equations do not conform to the dimensional consistency. Many other researchers (Zimmerman and Bodvarsson, 1996; Xiong et al, 2011; Li et al, 2019) considered aperture distributions in their equations. But the aperture distributions change during shear was always neglected. The contact of rock joints also has a significant impact on the hydro-mechanical behaviour of rock joint, since fluid tends to flow-through a rough joint along connected channels while bypassing the contact obstacles with tortuosity. Nonetheless, previous research mostly considered joint roughness or aperture changes based on 2D joint profiles, while the contact and tortuosity based on 3D surfaces were often overlooked. Only a few works have been made on quantifying the effect of contact area on flow behaviour (Walsh, 1981; Zimmerman et al, 1992; Zimmerman and Bodvarsson, 1996; Yeo, 2001), and mostly ignored contact area change induced by shearing and the associated impact on flow behaviour. Summarily, the quantification of fracture geometry effects on water flow in single rock joints still needs further investigation, especially when considering coupled shear-flow processes. This paper, therefore, aims to study the impacts of contact area and aperture distributions of the single rock joint on the flow behaviour. The evolutions of contact area and aperture distributions induced by shear are considered. Then, an improved model for estimating the hydraulic aperture with the mechanical aperture incorporating the above factors is developed. Finally, a series of shear and shear-flow tests are conducted on artificial joint samples and the model performance is verified by comparing against the results of experimental tests.

Nov 29, 2022

By D Guibal, J Vann, M Harley

Many sample value distributions are highly skewed and present variograms with high relative nugget effects and/or short-range structures. In consequence, significant deskewing of the histogram and variance reduction occurs when transforming between sample and block support, where blocks are of significantly larger volume than samples. When making estimates in the mining industry we usually wish to estimate on the basis of block support rather than sample support. The selective mining unit (SMU) refers to the minimum support upon which ore/waste allocation decisions can realistically and practically be made. The SMU is usually significantly smaller than the sampling grid dimensions, in particular at exploration/feasibility stages. In a non-linear estimate, for each large block (by convention called a æpanelÆ) we estimate the proportion of SMU-sized parcels above a cut-off grade threshold. A series of proportions above cut-off defines the SMU distribution. Use of such non-linear estimates reduces distortion of grade-tonnage curves and provides a better basis for mine planning and economic decision-making. At present, Multiple Indicator Kriging (MIK) is the most widely used technique for performing estimation of recoverable resources. MIK is not the only approach available and it has some potentially serious limitations. The MIK technique is described and a number of theoretical and practical implementation issues are examined. In particular: MIKÆs assumptions about spatial distribution of grade; the behaviour of indicator variograms; application of change of support models; order relationship problems; and modelling the tail of the distribution. Some simple tests are described which allow us to determine the suitability of different estimators for a given deposit and criteria to identify a preferred estimator are also examined. Uniform Conditioning (UC), an alternative estimator which may be used instead of MIK, is described.

Jan 1, 2000

By G M. Tranell, M Tangstad

The CO2 footprints in the production of Mn-ferroalloys and silicon/ferrosilicon are correlated with the fossil carbon consumption. The CO2 emissions may be reduced in the Mn-ferroalloy process by increasing the degree of prereduction and reduction of carbonate materials, while the silicon/ferrosilicon process is optimised based on silicon yield. By changing the fossil reductant into biogenic reductants, the global warming potential will be decreased even more. Even if the reductants are biogenic reductants, there will still be a global warming potential (GWP) in eg the electrode consumption and the CH4 emissions in the charcoal production. To reduce the use of fossil reductants there are also more disruptive technologies like the use of H2 that at least for the silicon production is on a very low technology readiness level (TRL). Using metallothermic processes will reduce the use of carbon but requires carbon neutral metal reductants. Electrowinning can have low CO2 emissions, and the electrowinning of pure Mn is a technology of high TRL. Salt and oxide electrolysis is under investigation for both Mn and Si production however the research is still on a low TRL. The use of CCS/CCU (carbon capture storage/utilisation) is a part of obtaining carbon neutral processes. Last, the energy mix used for these energy demanding processes is discussed.

Aug 21, 2024

By N Swiegelaar

Loubert Witbank is a defunct coal mine situated near Ermelo in South Africa. Mining ceased in 1992, and within a short period acidic decant occurred, with a significant impact on the regional catchment. The problem was studied during 1996/1997, and the site remediated in 2001/2002 by the Department of Water Affairs and Forestry. Remediation involved primarily submerging of carbonaceous material, backfilling of voids, and capping of the site. Acidic water with high iron levels was also neutralised and discharged. The project was used to assess the cost benefit of different options to the downstream users, from which target expenditure was derived for the various improvements. The cost benefit analysis for neutralisation provided a basis for the investigation of low-cost neutralisation options that are robust enough to be applied in a remote environment.

Jan 1, 2003

By J G Reid

In the period since 1989 the Yabulu Nickel Refinery of Queensland Nickel has undergone a transformation both in terms of the nickel laterite ore feed and the refined nickel product. These two changes were mutually supporting, as will be shown in the following paper. It had been realised since the early-1980s that the Greenvale orebody would be exhausted by 1992. Consequently planning had been in progress throughout the 1980s for the importation of overseas ore as a replacement for the Greenvale ore. The existence of extensive lateritic ore deposits in New Caledonia and Indonesia made these locations the natural focus of attention. With the three Japanese ferronickel smelters sourcing their nickel garnierite ore feed from these locations it was relatively easy for the miners to supply the overlying limonite ore to Yabulu. This limonite ore was previously discarded as waste. The Yabulu refinery now receives about 85 per cent of its ore from these two overseas sources. The transition from Greenvale ore to imported ore occurred gradually between 1989 and 1993. It was during the ore importation planning stage of the mid 1980s that Queensland Nickel commenced the technical investigation which led to the ammoniacal solvent extraction (ASX) plant installation and the product change from nickel oxide to nickel metal.

Jan 1, 1994

The Mount Kasi gold deposit in Vanua Levu represents an epithermal, high sulphur, gold-enargite system occurring within a volcanic caldera of Middle to Upper Miocene age. High level breccia pipes flare upward and form flat lying, near surface, mushroom shaped sheets parallel and near to the present land surface. The upper portions of the pipes contain explosion breccias which are capped by sandy siliceous sinter-like beds and are cut by alunite veins. Outlying intercalated scoriasceous lavas and breccia sheets show evidence of subsidence within a shallow basin. Detailed mapping of breccia types, intensity of silicification and the presence of multiple quartz veining and enargite abundance outlined blocks of more consistent gold mineralization within the breccias. This work has provided a model for mineralization which will aid future exploration and ore reserve estimations. A significant eluvial concentration of gold occurs in soils overlying the breccia sheet.

Jan 1, 1987

By D Cliff

Despite advances in technology, the Australian underground coal mining industry continues to have incidents involving spontaneous combustion. Managing these incidents relies heavily on understanding the state of the event as it develops and controls are applied. Gas analysis plays a major role in aiding this interpretation. This interpretation is based upon laboratory testing of coal samples under conditions very different to those found in an underground coal mine. This paper will explore the links between laboratory data and actual events. It will highlight the difficulties of using laboratory data. It will outline the relevance of laboratory data and how it can be usefully applied to manage spontaneous combustion events as well as in establishing relevant trigger action response plans to facilitate early detection and control of such events. The paper will identify some of the factors that need to be applied when adapting laboratory data to apply to the underground coal mine. It will outline the need for comprehensive knowledge of the local conditions and gas concentrations to be expected at all locations in an underground coal mine. Further, it will demonstrate the need for mine environment monitoring to go beyond simply measuring gas concentrations but also to include reliable atmospheric pressure, temperature and air velocity monitoring.CITATION:Cliff, D, 2013. Gas analysis - Linking the laboratory with reality, in Proceedings The Australian Mine Ventilation Conference , pp 277-282 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By P A. Grossman, J H. Rubinstein, M Brazil, D Whittle

Many ore reserves are harvested by a combination of open pit and underground mining methods. In these cases, there is often material that could be mined by either method, and a choice has to be made. The area containing this material is referred to as the transition zone. Deciding where to finish the open pit and start the underground mine is referred to as the transition problem and it has received some attention in the literature since the 1980s.In this paper, we provide a review of existing approaches to the transition problem encompassing: graph theory-based optimisation employing an opportunity cost approach, heuristics and integer programming. We also present a novel opportunity cost approach, that takes into account a crown pillar, and show how the new approach can be best applied through the unconventional application of an existing mine optimisation tool.CITATION:Whittle, D, Brazil, M, Grossman, P A, Rubinstein, J H and Thomas, D A, 2016. Determining the open pit to underground transition – a new method, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 731–742 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By K Knorr

Desktop X-ray powder diffraction using a D2 PHASER equipped with fast linear detector was performed on several iron ore and mill scale samples. Data were analysed using cluster analysis and Rietveld quantitative phase analysis. The quantitative mineralogy of both materials could be established. Thus the input is provided for understanding the energy consumption and the CO2 emission during iron production. Furthermore, tabletop XRD allows to distinguish iron ore from mill scales and to quantify their mixtures.

Jul 11, 2011

By J Bohm, B Csoke, I Tarjan

In process technology, especially in coal preparation, it is often necessary to have a continuous knowledge of the average density of granular material in order to achieve both quality control and process control. The paper presents a new method and means supported by laboratory measurements for the rapid, practically continuous, determination of the average density of continuously supplied granular material through frequent sampling.

Jan 1, 1993

By M Rankin, F Medina, R Verburg

We conducted a preliminary assessment of an extensive deposit of historic tailings discharged over a period of 40 years to the shoreline along a Southern Peruvian coastline. The tailings formed an extensive beach approximately 2.4 km long and 300 m wide. The tailings consist principally of pyrite (37 to 59 per cent), hematite (nine to 20 per cent), magnetite (three to 13 per cent) and quartz (11 to 36 per cent). The present operating company was required to evaluate the feasibility of capping the ocean side tailings deposit, however, given the size of the undertaking and the potential to reclaim residual minerals from the tailings, it was prudent to first evaluate whether capping would in fact reduce the impacts to the marine environment. Therefore this preliminary assessment examined: 1. metals contamination in tailings, shoreline porewater and marine sediments; 2. reactivity of tailings and acid generation potential; and 3. the potential for biological effects from metal contamination in the uplands tailings (solid phase) and beach porewater. Based on mineralogy, column leach studies and chemical results, the upland tailings have a high geochemical potential to acidify and release metals, especially copper, nickel and zinc, should they be subject to oxygenated and aqueous conditions. But, the extreme arid climate results in very low potential for precipitation and virtually precludes the transport of acid drainage reaction products from the upland tailings towards ocean. Wind erosion caused by offshore winds is likely a small source of tailing transport to the ocean. Since some potential exists to reprocess the tailings in the future, capping does not seem justified at present.

Jan 1, 2003

By A Hilli, K Kosmara, J Steyn

PT Nusa Halmahera Minerals (PT NHM) is an Indonesian joint venture company owned by Newcrest Mining Limited (75 per cent) and PT Aneka Tambang (Persero) (25 per cent). PT NHM operates two underground gold mines, Kencana and Toguraci at the Gosowong mine site in North Halmahera District, North Maluku Province, Indonesia.On 8 February 2016, a major ground movement occurred in the K-Link orebody of the Kencana underground mine, effectively blocking the only two access ways to the stoping area. Following mine clearance, it was found that a Solo production drill rig operator, who had been drilling in the Level 10 Extraction Drive was still underground, cut off from the rest of the mine by the ground movement.Communication, nutritional and logistic supply to the trapped operator was established with the breakthrough of two diamond drill holes. A range of technical expertise and opinions from both on and off-site were sought and two options were chosen for implementation of the rescue operation. The rescue was completed successfully on 16 February 2016 with the operator being rescued in good physical and mental health.CITATION:Kosmara, K, Hilli, A and Steyn, J, 2017. Eight days entrapped – PT Nusa Halmahera Mineral’s rescue of a trapped miner, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 155–160 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

Low-grade, porphyry copper type mineralization at the Moonmera prospect is related to the intrusion of a granodiorite porphyry mass into the Upper Permian "Gracemere granodiorite". Significant copper mineraliza- tion appears to be associated with the alteration assemblage quartz-sericite- kaolinite. The ore shell is surrounded by a zone where montmorillonite and kaolinite are in greater abundance and this assemblage is over- lapped, mainly at depth, by potassium feldspar alteration. Secondary biotite is abundant throughout the mineralized zone. Preliminary sulphur isotope results on the sulphide mineralization are compatible with a magmatic origin for the sulphur.

Jan 1, 1974

By C Berglin

Is the Northern Territory different? Certainly it is more remote, has less people and relies more heavily on two or three industries for its survival. On the other hand, its mining industry is governed by Acts not dissimilar to those of the major States - a Mining Act provides the basis for acquisition of tenure, a Mine Management Act provides regulatory control, a Mineral Royally Act collects revenue in return for the right to utilise the land's bounties, an Environmental Assessment Act provides the public face to rehabilitation and environmental safety, and the Aboriginal Land Rights (NT) Act purports to give development criteria for inalienable land use. With the exception of the latter, at least until the advent of Mabo, all these are simply variations on a theme, and are common to most States. This paper will show how the Department of Mines and Energy works in relation to the Northern Territory mining industry.

Jan 1, 1994

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 E Mofya, R Kaunda, P Lever

One of the fundamental requirements for being able to optimise blasting is the ability to predict fragmentation. An accurate blast fragmentation model allows a mine to adjust the fragmentation size for different downstream processes (mill processing versus leach, for instance), and to make real time adjustments in blasting parameters to account for changes in rock mass characteristics (hardness, fracture density, fracture orientation, etc). A number of blast fragmentation models have been developed in the past 40 years such as the Kuz-Ram model (Cunningham, 1983). Fragmentation models have a limited usefulness at the present time because:The input parameters are not the most useful for the engineer to determine and data for these parameters are not available throughout the rock mass. Even if the input parameters are known, the models still do not consistently predict the correct fragmentation. This is because the models capture some but not all of the important rock and blast phenomena. The models do not allow for ætuningÆ at a specific mine site. This paper describes studies that are being conducted to improve blast fragmentation models. The Split image processing software is used for these studies (Kemeny, 1994; Kemeny et al, 1999).

Jan 1, 2001