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By N. J. Wagner, D. G. Modiba

There is currently limited knowledge concerning South African coal deposits as hosts for rare earth elements (REE). This project aims to determine the concentration of REE, including yttrium and scandium (REY+Sc) in various coal seams and adjacent sediments in borehole cores from the Ermelo, Witbank, and Waterberg coalfields in South Africa. Coal petrography (maceral count and vitrinite reflectance), XRD, XRF, sequential chemical extraction procedure (SCEP) before ICPMS, and mineral liberation analysis (MLA) were conducted on the coal and associated sediment samples. The coals were inertinite-rich, medium-rank bituminous coal, with moderate to high ash content. The two dominant minerals in all the coalfields are kaolinite and quartz, except for sample ZBS2M, where dolomite was dominant. The dominant major oxides are Al2O3, SiO2, Fe2O3, and CaO, which concur with the XRD results. The ICP-MS results following SCEP indicated that both coal and the associated sediments were light REY+Sc dominant. There was also an elevation of medium REY+Sc in the Witbank coal’s associated sediment samples. Notably, the samples with the highest REY+Sc results were the sediment samples. The Waterberg samples had the lowest REY+Sc from both the coal (less than 2 μg/g to 7 μg/g) and associated sediments (2 μg/g to 15 μg/g). While the highest REY+Sc was yielded from the Witbank-associated sediments (500 μg/g to 2,500 μg/g). The carbonate fraction step proved to be the most successful leaching step, as most REY+Sc was recovered in that step for all coalfields. In addition to the carbonate fraction, the silicates and sulfide fraction in the Witbank samples, and the ion-exchangeable fraction for the Waterbergassociated sediments samples proved successful in leaching out the REY+Sc. MLA determined that monazite and xenotime in all the coal samples were the REY+Sc-bearing minerals.

Nov 6, 2024

By Whittaker B. N, Reddish D. J

The rockbolting method of support is employed widely in several countries in different of mines. Hard rock mines use this method extensively. Soft rock mines, such as coal mines, have employed standing supports (steel sets) as the main method, although some countries such as the U.S.A. and Australia have preferred rockbolting. There is increasing interest in extending the rockbolting method in coal mines. The application of rockbolting techniques in an industry which traditionally has not applied such techniques, has required the development of a systematic design approach. This design approach uses extensive monitoring, to asses the viability of the support system in differing conditions. Currently at a number of new and existing mine developments in the U.K., rockbolting is being successfully applied. Although, inevitably some localised geotechnical problems have been encountered and have needed to be taken into account. The effect of faulting on roadway conditions is discussed in this paper and a design approach has been applied using a numerical analysis method, namely the Finite Element Method. The results presented in the paper serve as a useful guide to roadway support designers, and in particular the role played by different bolts in a range of conditions.

Jan 1, 1992

By Erdal Akyol

The rockbolting method of support is employed widely in several countries in different of mines. Hard rock mines use this method extensively. Soft rock mines, such as coal mines, have employed standing supports (steel sets) as the main method, although some countries such as the U.S.A. and Australia have preferred rockbolting. There is increasing interest in extending the rockbolting method in coal mines. The application of rockbolting techniques in an industry which traditionally has not applied such techniques, has required the development of a systematic design approach. This design approach uses extensive monitoring, to asses the viability of the support system in differing conditions. Currently at a number of new and existing mine developments in the U.K., rockbolting is being successfully applied. Although, inevitably some localised geotechnical problems have been encountered and have needed to be taken into account. The effect of faulting on roadway conditions is discussed in this paper and a design approach has been applied using a numerical analysis method, namely the Finite Element Method. The results presented in the paper serve as a useful guide to roadway support designers, and in particular the role played by different bolts in a range of conditions.

Jan 1, 1992

By F O. Otuonye

Full-face blasts were fired in a 12 x 8 ft drift of an underground hardrock mine in a basalt formation with porphyry copper to study the effects of drill pattern and explosive type on the size distribution of the resulting muckpile. Each muckpile produced by five full-face blasts was sampled four times with a scooptram equipped with a 5-cu yd bucket and the size distribution of the broken rock in each bucket was determined by screen analysis. Results show a strong dependence of the fragment size distribution of muckpile on the blast pattern and explosive type for a given rock type. The mean fragment size of the broken rock was compared with the predictive equations of other investigators. Random sampling of the muckpile from full-scale blasts and screen analyses of the samples are recommended in assessing the size distribution of the broken rock because of scaling errors that are inherent in full-scale blasts when designed from results of small-scale tests.

Jan 1, 1985

By F. G. Boehm, T. S. Golosinski, P. M. Tucker

"In an earlier paper(1) the visits to several European mines using the bucket-wheel excavator (BWE) technology were described. It was during this trip that information was gathered on some interesting developments related to this type of mining, taking place elsewhere. It was learned that an across-the-pit system (XPS) comprised of a BWE and stacker has been operating successfully in a Hungarian mine for some time. Also the use of stackers with 225 m long booms and draglines with 125 m booms and 125m3 buckets in Soviet mines was indicated. Such equipment could be of great value to some Canadian strip mines, in particular the equipment proven useful in severe climatic conditions of U.S.S.R., similar to those of the Canadian prairies.To follow up on this information a field trip to Hungary and the U.S.S.R. was organized by the Department of Mineral Engineering, University of Alberta, to study the applications and performance of the systems in question. Visited were the Thorez mine near Visonta, Hungary, U.S.S.R. Ministry of Coal Mining and Skotchinski Institute in Moscow, Karagandashakhstoi Institute (designers of Ekibastuz mines in the Kazakh Republic) and Kostenko mine in Karaganda, Vostsibgiproshakht Institute (designers of Irsha Borodinski, Kharanovski, Moguntski and Tugnuski mines in Siberia) and the eastern Siberian Unit of the U.S.S.R. Coal Mining Ministry in Irkutsk as well as Azeiski mine located some 250 km northwest of Irkutsk. The findings of this field trip are presented."

Jan 1, 1985

An assessment has been made of six reported methods for the determination of the swelling of iron ore pellets on reduction. The methods are discussed on the basis of apparatus requirements, reduction conditions, sample requirements, measurement of swelling and reproducibility. It is concluded that the CNRM, LKAB, and Lurgi methods are the most satisfactory which presently exist for determination of the swelling of industrially produced, iron ore pellets.

Jan 1, 1974

By J J. Moreno, J Willis, P Garvey

Many of the tailings storage facilities (TSFs) in Australia are upstream raised facilities for which the consolidation of the hydraulically deposited tailings is essential to the stability of the TSF. While much operational consideration is given to limiting the rate of rise of TSFs through careful management of deposition rates to achieve desired consolidation, the rate of embankment raise construction (RoC) is often not given the same level of consideration. Loading the tailings at too high a rate during construction could lead to upstream and potentially downstream failure of the embankment. The Tailings Retention System (TRS) at the BHP Olympic Dam Mine comprises upstream raised TSFs that are continually raised with a zoned embankment. Improving on 20 years of successful embankment raising, there was a desire to understand the acceptable RoC under varying operating conditions and assess upper construction limits to improve operational risk management. To understand the RoC, trial embankment raise construction pads were constructed at different rates and the pore pressure response of the underlying tailings material was monitored. The pore pressure data were used to calibrate the permeability and consolidation characteristics of the tailings in a finite element model (FEM) that replicated a typical embankment raise. The rate of material placement, location of the phreatic surface and construction load were varied in the FEM until failure was initiated. The results were presented as a period (in days) over which the various zones for the embankment raise could be safely constructed. The results indicate direct sensitivity to the depth to the phreatic surface prior to commencement of an embankment raise, as well as the point of application of the construction traffic load. This paper presents the study approach, challenges experienced in modelling the construction methodology, the study results and their relevance in the improvement of understanding of RoC at the BHP Olympic Dam TRS.

Jul 1, 2021

By Palmer W. T

The successful re-opening of the Cobar min- eral field was dependent upon the success- ful introduction of highly productive, low cost mining. Mechanised cut and fill stop- ing with incline access was selected for the C.S.A. mine because it permitted flexi- bility, complete primary extraction with no secondary pillar recovery, minimised dilu- tion and oxidation, a minimum of pre-pro- duction development and because diesel powered load-haul-dump (L.H.D.) units were proving reliable and highly productive in the U.S.A. Although L.H.D. vehicles are the key to the success of the mining method, four other main groups of vehicles are utilised in the mine - trucks, scaling vehicles, ser- vicing vehicles and specialist vehicles. The operating requirements at the C.S.A. mine are more stringent than those encount- ered in many other underground mining oper- ations. The first L.H.D. vehicle used at Cobar - the Transloader - had considerable difficulty in loading and discharging coarse production ore. The Wagner ST5 Scoop Tram performed this duty much better. However, the first generation Scoop Trams were not robust enough to withstand the heavy duty and many modifications were necessary before acceptable availabilities were obtained. Similar modifications were necessary for the Eimco 916 vehicle but the Eimco 915 unit came much closer to meeting the duty requirements. Eventually Cobar technical personnel design- ed a L.H.D. vehicle to meet specific C.S.A. mine conditions. These units have proven most satisfactory. Over 8 years of operation the underground vehicle fleet has become a proliferation of vehicle types. A standardisation pro- gram has been initiated based upon common prime movers being mated with "trailer" units to serve specific functions. Standardisation will reduce inventory levels and facilitate training of operating and maintenance personnel.

Jan 1, 1973

By A. K. Gangopadhyay

This paper discusses the effect of grinding media composition, mineral type and slurry environment on the wear rate of various grinding media (balls). Sufficient wear data have been obtained and correlated with the modes of wear determined from examination of the ball surfaces using scanning electron microscopy. Five modes of wear have been identified to be operative under certain slurry conditions for the various ball compositions studied.

Jan 1, 1984

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 M. Kawakami

In order to make titanium ingot directly from molten slag, the metal pool was tried to form and used as the cathode. The electro-slag remelting (ESR) unit was used for the purpose. The unit is composed of water-cooled copper mold and the DC power source of 2000 A and 100V. The graphite electrode was used for anode and the base plate was used for cathode. The commercial and re-melted slag of CaO-CaF2 was melted in the mold with the addition of TiO2. The following reactions are expected to occur. Ti4+ + 4e = Ti at cathode 2O2- + 2C = 2CO + 4e at anode During the process, large amount of molten slag splashed out from the mold, showing the CO evolution at anode. The metal deposit was obtained but in the form of block and piled up on the base plate. The metal pool was not obtained perfectly because of shortage of heat supply. The cathodic current efficiency was 60 % at maximum. The metal deposit contained much impurity. In order to reduce the impurity and increase the current efficiency, the effect of electrode distance was examined. The electro-slag re-melting of titanium was tried in order to examine the condition to make metal pool.

Jan 1, 2006

By P Jonsén, S Larsson, M Parian, B I. Pålsson

The question of effective energy utilisation in grinding mills is not new. There are several conflicting arguments about tumbling mills, whether the efficiency is around 1 per cent or maybe 10 per cent, or even much lower. The energy not used is assumed to be lost as heating of the pulp, the grinding mill body, the charge, generation of shock waves and vibrations, etc. Stirred media mills on the other hand are generally considered to have better energy utilisation, but their energy efficiency is still not that clear. To shed some light on this a pilot-scale, wet stirred media mill was investigated over a range of operating conditions. The wet stirred media mill is a Drais PMH 5 TEX pearl mill fitted with an electric motor at 11 kW. It has been investigated over a range of operating conditions to try to balance the dissemination of the input energy in forms of the net grinding energy, mechanical energy losses, and the heating transferred to the pulp, the mill, the charge, and the cooling water. It is found that approximately 20–40 per cent of the input energy accounts for the grinding process. Also, that the difference between gross and net input electrical energy is mainly disseminated as heating of the pulp and cooling water. Mechanical energy losses appear to be much smaller than the heating effects. The use of a dispersant seems to mainly influence the heating effect.

Aug 24, 2022

The calibrated thermal IR data of part of Cambay Basin is used to determine surface temperatures and to detect the heat flow. Applying the conductive heat flow continuation technique, the three dimensional configuration of the hydrocarbon bearing reservoir was defined. The zone delineated by the present study coincides with the oil-bearing structures inferred by seismic survey. The results indicate the possibility of the technique as an effective tool in hydrocarbon exploration.

Jan 1, 1986

By Anoush Ebrahimi

Mining dilution is one of the most important factors affecting the economy of mining projects. Ore losses and dilution are present at all stages of mining and while several models can investigate the influence of dilution it is its quantification that poses the most serious challenge (Pakalnis et al., 1995). This paper introduces a methodology to quantify dilution factor in open pit mines. The proposed approach makes use of general mining software available in most mining companies. Therefore it is amenable to most mining operations and provides a readily available tool for understanding mining dilution for operators and consultants. To illustrate the methodology the author uses an example from a hypothetical mine. Dilution increases the operating costs in the mill by increasing the tonnage of material to be milled. In addition to its direct impact on short term income of a mine, dilution causes significant changes in other factors that on the long term reduce the overall value of the project. For example, it prolongs the mine life by reducing mill?s effective capacity. It also reduces the feed grade. In most cases, lower feed grade means lower mill recovery. Dilution also increases the cut-off grade which in turn reduces the overall ore utilization of a mine. In some cases, to take advantage of economies of scale, mining operations tend to plan for higher mining rates. Moving to a larger scale of operation means less selectivity, hence more dilution. This is true for all kind of deposits. High level and uncontrolled dilution may ultimately defeat the purpose of increasing production rates. If not impossible in theory it is nevertheless extremely difficult and expensive to eliminate dilution in practice. Some amount of dilution is practically unavoidable in most mining operations (Scoble and Moss, 1994). Although completely avoiding dilution may be impossible, we can measure and control it. By better understanding the root causes of the dilution and planning accordingly, it can be controlled and reduced. While we do our best to identify and calculate all the other cost items of a project, no matter how small, it is common to make general assumptions about dilution instead of quantifying it. It is common to assume a general dilution such as 5% for massive deposits and 10% for tabular shape deposits. While these figures may be a good starting point in early stages of mining studies, it does not take in to consideration the complexity of the problem. Dilution factor varies within a single mine for different benches and zones. This is due to changes we see in grade distribution and shape of ore body. It also varies based on commodity price. It is necessary to make sure that these variations are taken into account when designing or evaluating a mine. Dilution varies in different mines based on the deposit characteristics, operational aspects and economic cut-off grade. For instance, shape of the deposit, bench height, equipment size, and market conditions will have an impact on the level of dilution in a mine. It is paramount for mining projects to have a better understanding of dilution right from the beginning. In times like today, where mining operations must operate at peak efficiency, it is even more crucial to be able to calculate and have a better grasp of all the parameters influencing the economics of a project including dilution. In order to produce better project evaluations, dilution studies should be an integral part of any project.

Aug 1, 2013

By L Klemettinen, J Biswas, W Malan, D Sukhomlinov, D Lindberg

In order to mitigate the effects of climate change, our society must be able to drastically reduce its CO2 emissions. As the metallurgical industry is a considerable contributor to these emissions, new greener technologies must be invented and developed. One option could be the direct production of metals from oxides using renewable electricity. The aim of this study was to investigate the possibility of using high-temperature molten oxide electrolysis (MOE) for iron and ferrochrome production. FactSage™, ver 8.2 (by Thermfact Ltd and GTT-Technologies) was utilised for estimating a feasible equilibrium electrolyte composition, and the experiments were conducted at 1550–1580°C in conical alumina crucibles with iridium wire as the cathode and platinum wire as the anode. The sources of iron and chromium were either pure FeO powder or industrial chromite pellets. Voltage was applied to the electrolysis cell for 6 hrs and the resulting current was measured, along with oxygen concentration in the off-gas line. The electrolyte comprised of SiO2, Al2O3, MgO and CaO. First, the effect of FeO concentration on iron reduction efficiency was investigated using only pure oxide powders as starting materials. The results indicated that 10 wt per cent FeO mixed with the electrolyte resulted in more efficient iron reduction compared to 20 wt per cent. In further experiments, industrial chromite pellets were ground and mixed with the CaO-free electrolyte. Iron and chromium reduction efficiencies were higher when approximately 19 wt per cent of the total sample mass consisted of pellets compared to increasing the pellet amount to 37 wt per cent. Generally, the chromium solubility in the liquid electrolyte was relatively low, and most of the chromium was confined to the spinel solid solution, from where its dissolution to the liquid electrolyte was very slow, resulting in slow reduction kinetics. For larger scale applications, economically more viable electrode materials should be investigated.

Jun 19, 2024

By F. Mwaura

"The aim of the audit was to determine whether the mining project environmental impact assessments (EIAs) in Kenya are undertaken according to international best practice. A sample of 50 EIA reports for the 2007–2016 period was evaluated using 18 criteria in the Environmental Law Alliance Worldwide (ELAW) guidelines. The findings showed that only two criteria were considered ‘excellent’ according to the ELAW guidelines, namely baseline environmental assessment and prediction of physical impacts. Six criteria were found to be ‘satisfactory’, including prediction of social impacts, analysis of alternative options, and impact mitigation. The reports were quite weak in terms of: consideration of all phases in the mining cycle, environmental regulatory framework, prediction of biological impacts, stakeholder consultation and engagement, integration of human right issues, and integration of climate change and cost-benefit analysis. It is therefore recommended that the Kenyan National Environment Management Authority (NEMA) should consider tightening the EIA terms and conditions in the approval of statutory terms of reference (ToR) for full-scale mining EIAs to ensure improved performance of EIA as a tool for environmental protection. IntroductionThe nexus between society and the environment has continued to generate interest because the environment is the source of goods and services that sustain the various needs of human beings as outlined in the UN sustainable development goals (SDGs) (Armstrong and Peart, 2000; Sutton 2004; Chakrabarti 2007; Strange and Bayley 2008). All the five generic categories of societal needs, namely physiological needs (food, water, clothing, medicines, etc.), residential and occupational needs (shelter, transport, energy, etc.), economic needs (tradeable goods and services), leisure and recreational needs (tourism), and cultural and spiritual needs (e.g. sacred resources and ecosystems) (Mwaura et al. 2016) are addressed by the environment. Consequently, a wide range of development sectors have been established around the world in order to address the above needs (Lederer, Galtung, and Antal, 1980; Rammelsberg et al., 2006; Noonan, 2014). All these development sectors rely entirely on the environment for their proper functioning, as shown in Table I."

May 1, 2019

By William Bent

THE dynamometer herein described is a modification of the one invented by Mr. Samuel Batchelder, of Boston, nearly forty years ago, a description of which may be found in the Journal of the Franklin Institute, 1843, vol. xxxii, p. 277, and in the Scientific American of August 31st, 1878. The modification consists in providing a method of making an automatic record, and of indicating more minute variations of the power transmitted. The improved dynamometer was designed by the writer in 1877, and was built a few months since by the Class of 1879 of the Stevens Institute of Technology. The accompanying cut, taken from the Annual Announcement of the Stevens Institute, represents the dynamometer without the recording attachment. It consists, as shown, of two stout cast-iron frames, held together by bolts in bearings, in the top of which frames run two shafts, each carrying a pulley at its outer end and a bevel gear-wheel of 45° at its inner end. One of these shafts is the driving-shaft, connected by belt to the engine or other prime mover; the other is the driven shaft, connected by belt to the machine driven. The power is transmitted from one shaft to the other through two other bevel-wheels of 45° gearing with the first, the shaft common to them and on which they run freely being at right angles to the axis of the two shafts first mentioned, and carrying at one extremity a heavy pendulum. The bevel-wheels being connected, as shown, and the power being applied to the driving-wheel, the two intermediate wheels with their common shaft have a tendency to revolve around the driving-axis, which tendency is a measure of the force transmitted, and is resisted by the moment of the weight of the pendulum. In the Batchelder dynamometer the four bevel-wheels and their shafts are used, but

Jan 1, 1880

By Ryan A, Dennis R, Dekker D, Ellis W, Sowerby B

An automated facility for non-destructive elemental analysis of mine samples has been developed and tested at Mount Isa in association with the CSIRO. The analysis is based on the prompt and delayed measurement of gamma radiation emitted by the sample during and after separate fast and thermal neutron irradiation. No sub-sampling or sample preparation is required and the analyser is operated by one person that would otherwise be splitting drill core in preparation for conventional analysis. The analyser has been calibrated to measure the following (precision in parenthesis): Ag (14 ppm), Pb (0.5 wt%), Zn (0.5 wt%), Cu (0.04 wt%), Fe (0.7 wt%), S (1.1 wt%), SiO2 (0.8 wt%), A1203 (0.07 wt%), Mn (0.05 wt%), specific gravity (0.02 g cmt). Crushed or whole drill core samples that range in size between 0.5 m and 1.8 m of equivalent BQ size drill core can be analysed at a rate of six samples per hour. If required, drill core samples can be re-packed in their original configuration for storage following analysis. Standard samples are measured every day to ensure operational stability. The analyser is controlled by a personal computer which prints the results and stores them along with the raw data on the computer hard disk. This paper reports the performance of the analyser during 1992 for routine analysis of drill core from the lead ore bodies of both Mount Isa and Hilton mines.

Jan 1, 1993

By M Scoble

This paper will report on the application of data collected through the performance monitoring of large diameter surface rotary blasthole drii and electric mining shovels, in an integrated approach to blast optimizatiion.

Jan 1, 1992

By S. Hill

For a mining operation, the determination of the best place to build haul roads is typically done by hand, or with the assistance of rudimentary shortest path optimisation algorithms. Straight line, point to point, modelling of costs is often used with distances multiplied by constants that are based on rise of the road between the points. Failings of this approach are that straight line approximations are notoriously poor as they do not take into account areas where a truck cannot travel. In addition, the rise and fall of the road may vary considerably over the truck journey meaning acceleration/deceleration and varying truck speeds are not taken into account. Lastly, the use of rudimentary optimisation algorithms means properties a truck must obey such as minimum turning circles, line of sight restrictions or even that the truck must travel forward at all times are not taken into account. Thus solutions generated may not be feasible, let alone optimal. In this paper we discuss a state of the art parallel Artificial Intelligence tree search technique for solving haul road location problems. As well as the above properties, factors such as road utilisation, cut and fill, and construction costs are taken into account. The combination of advanced modelling and fast computing and optimisation techniques produces significant benefits both in terms of time to generate roads and cost savings. Preliminary results where this method has been used are discussed.

Aug 1, 2013