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By L. B. Hales

Expert control of grinding and flotation plants has been successfully used in the minerals industry since the 1970?s. The earliest of these systems were written in a hard-coded fashion in FORTRAN, BASIC or Pascal. Second generation systems were built using the first experimental expert system shells that were being developed in the artificial intelligence community. Later systems were deployed in expert system shells designed for real-time processing plants that also included the ability to model the process with neural network models and optimize setpoint selection through the use of genetic algorithms. Significant performance increases have been achieved using these systems, but in general, they suffer from the static nature of their rules and to a degree the process models also. Typical improvements quoted in the literature suggest throughput rate increases of 4 to 8 percent and recovery increases of 1 to 4 percentage points. In over 30 years of designing and installing expert systems we have never seen performance numbers less that these but have often seen numbers in excess of the high values. However, once the system has been installed and tuned up the performance usually does not improve much thereafter. Granted, the initial increases in throughput rate and recovery are significant but a question always lingers, that is, can the expert strategies be modified further to squeeze a little more improvement out of the system. The answer to this question is a resounding yes, however a complete understanding of what we do well as designers and operators of expert control systems is required as well as how we can improve upon our best practices is required to move us from the performance plateau we have been on for a number of years to a new higher level of performance.

Jan 1, 2009

By W. Wittke, J. Gattermann

ABSTRACT: One alternative to close a radioactive waste repository in rock salt is the construction of a “Cross Section Closure (CSC)“ sealing barrier. The proposed material for the CSC is highly compacted bentonite. To investigate the swelling behaviour of a highly compacted bentonite a large number of laboratory tests were performed. In addition, large scale model test were carried out to demonstrate the development of a nearly homogeneous and isotropic swelling pressure. The results of the large scale model tests were interpreted numerically based on the models for stress-strain behaviour and water uptake which are implemented in the finite element codes FEST03 and HYDOPO. The investigations show a good agreement of the results of the model tests and the corresponding analyses and show, that the theoretical models are capable of describing the behaviour of sealing structures based on highly compacted bentonite. ZUSAMMENFASSUNG: Eine Möglichkeit für den Verschluß eines Endlagers für radioaktive Abfälle im Steinsalz ist die Konstruktion einer Querschnittsabdichtung aus hochverdichtetem Bentonit. Zur Untersuchung des Quellverhaltens von hochverdichtetem Bentonit wurden eine große Anzahl von Laborversuchen durchgeführt. Um die Entwicklung eines nahezu homogenen und isotropen Quelldrucks nachzuweisen, wurden darüber hinaus auch Modellversuche in größerem Maßstab durchgeführt. Die Ergebnisse dieser Modellversuche wurden im Hinblick auf die Wasseraufnahme und das Spannungs-Verformungsverhalten mit Hilfe numerischer Berechnungen mit den finite Element Programmen FEST 03 und HYDOPO interpretiert. Die Untersuchungen zeigen gute Übereinstimmungen zwischen Versuchs- und Berechnungsergebnissen. Die numerischen Modelle sind somit geeignet, das Verhalten von Abdichtungsbauwerken aus hochverdichtetem Bentonit zutreffend zu beschreiben. RÉSUMÉ: Une possibilité pour fermer un dépôt final de déchets radioactifs dans sel gemme est la construction d'un étanchement de coupe transversale, fabriqué de bentonite fortement compacté. Pour étudier le comportement de gonflement de bentonite fortement compacté, de nombreux essais en laboratoire ont été exécutés. En outre, des essais sur modèle sur une plus grande échelle ont aussi été exécutes afin de prouver le développement d'une pression de gonflement à peu près homogène et isotrope. Les résultats de ces essais sur modèle étaient interprétés en vue de l'absorption d'eau et du comportement contraintes-déformations par le moyen de calculs numériques avec les programmes d'éléments finis FEST03 et HYDOPO. Les études montrent de bonnes conformités entre des résultats d'essai et de calcul. Les modèles numériques sont ainsi capables de décrire justement le comportement d'ouvrages d'étanchement fabriqués de bentonite fortement compacté.

Jan 1, 2003

By C. Bazin, D. Hodouin

"A flexible model involving perfect mixers, stagnant zones, plug flow, material bypassing and recycling zones has been developed for interpreting mixing phenomena in mineral processes. The mixing properties are described by the residence time distributions which can be subsequently interpreted by the flexible model. User-friendly computer programs (for 1MB-PC or compatible) have been developed for simulation and modelling of RTDs using the proposed model. Seven mineral processing case studies are discussed in terms of experimental procedure, model calibration results and application of the estimated mixing model to process modelling, diagnosis, and performance evaluation. IntroductionIn any mineral processing plant there are continuous-flow machines that transform or separate the ore components. Grinding mills, flotation cells, conditioning and leaching tanks are examples of such machines. The performances of these vessels or reactors are controlled by the rate at which the reaction proceeds and the time spent in the environment where the reaction occurs. This paper deals with the latter aspect of mineral processes operation.Since most of the reactions occurring in mineral processing units are time dependent, knowledge of the residence time of the material in process vessels is important for modelling and diagnosis purposes. Due to the random mixing phenomena involved in the process equipment, there is a distribution of the residence time of the ore particles and the fluid in the vessel. The probability density function E(t) that a micro-element of the material flowing through a processing unit stays a time t in the vessel, is the residence time distribution (RTD) of the corresponding component."

Jan 1, 1988

By J. P. Hansen

Reducibility tests were run by the Bureau of Mines on an open hearth lump ore and four groups of pellets whose smelting characteristics had been deter-mined previously in the Bureau's experimental blast furnace. When reduction data from various tests were plotted on specially prepared paper l-(l-percent reduction/100)1/3 against time, the plots were linear. The iron-wustite inter-face therefore advances at a constant rate. The rate of the interface advance in mm/min was used as a reducibility index. The reducibility index measured at 900° C, using 0.45 cu ft hydrogen per minute varied inversely with the surface area of the sample. Even with carefully controlled surface areas, how-ever, duplicate reducibility indices varied considerably. When enough tests were run to give a stable mean, the mean reducibility index did correlate with blast furnace production for the four pellet groups. Results indicated that if the interface speed itself were to be used for correlation with blast furnace production, a sample size of about 180 grams of minus 0.742-plus 0.525-inch particles should be used with a test temperature of 900° C and a flow of 0.45 cu ft hydrogen per minute.

Jan 1, 1966

By D. Conklin

Annual fish monitoring of the Red River, NM from the town of Red River to downstream of Questa, NM has been conducted since 1997. This long-term dataset, sponsored by the Chevron Mining Inc. Questa Mine provides an opportunity to evaluate the fish community response to natural phenomena, such as landslides and drought. Hydrothermal scars are present on drainages to the Red River, which can contribute large quantities of sediment to the Red River during localized storm events. Sediment inputs from the hydrothermal scars result in decreased habitat and water quality conditions within the Red River. Landslides from the hydrothermal scars contributed large amounts of sediment to the Red River in the summers of 2002 and 2007. Resident trout populations in the Red River after summer 2002 were depressed at sites adjacent to and downstream of the hydrothermal scars. Resident trout populations had begun to recover by 2005 and 2006; however, after the summer 2007 landslide, the resident trout population was again drastically reduced. In fall 2007, 13 resident trout were collected from 11 sites in the approximately 23 km reach of the river, compared to 691 from the same 11 sites in fall 2006. Resident trout density and biomass has gradually increased since fall 2007, and flows have removed sediment from the study reach. A combination of increased sedimentation and decreased water quality were likely responsible for the decreased resident trout populations in the Red River. Drought and the lack of flushing flows appeared to exacerbate the problem of high sedimentation levels from 2001 to 2004. Climate models predict prolonged periods of drought and increased intensity of storm events, potentially resulting in less favorable conditions for the resident trout population of the Red River in this area.

Jan 1, 2011

By Christopher Mark

Knowledge of in situ stresses is fundamental to many studies in earth sciences, and coal mine ground control is no exception. During the past 20 years, it has become clear that horizontal stress is a critical factor affecting roof stability in underground coal mines. The theory of plate tectonics and the World Stress Map (WSM) project has been extremely helpful in explaining the sources and the orientations of the horizontal stresses observed underground. Recently, WSM geophysicists studying deep-seated stresses have developed a model of how stress magnitudes vary with depth in the crust. They have devoted relatively little attention to near-surface stresses, however. This paper explores the relationships between deep-seated and shallow in situ stresses in several of the world?s coalfields, using a data base of more than 350 stress measurements from underground coal mines. The analysis indicates that distinct regional trends exist, corresponding roughly to the regional stress fields identified by the WSM. The paper presents equations for estimating stress magnitudes that were developed by treating depth and elastic modulus as independent variables in regression analysis. The magnitude of the horizontal stress increases with depth, at rates that range from 0.8 to 2.0 times the vertical stress, just as the WSM ?critically stressed crust? model predicts. Overall, it seems that the stress regimes encountered in underground coal mines are closely linked to those that exist deep in the earth?s crust.

Jan 1, 2008

By Henry P. Chandler

[Diamond, because of its extreme hardness and abrasion resistance, has an important function in precision engineering and automation. With the increasing; requirements of modern production for fine tolerances, interchange-ability, and speed, it has become even more important. In spite of the supply of other abrasive and hard materials and of ultrasonic, electrospark rued other substitute grinding, methods, world industry seams likely to absorb large quantities of diamond for industrial purposes. An increasing part of the world's needs will be supplied by manufactured diamond, which was introduced commercially by General Electric Co. in 1957. Use of diamond for glass cutting roes bark several centuries, mid diamond drilling of rock became important to the mining industry M the 1870's. Today, diamond drilling is the most extensively used method of exploring the world's ore reserves; diamond drills two also used to determined the nature of bedrock below the foundations of buildings, dams, and bridges. Diamond drill bits are now used extensively in the petroleum industry, and replacement or steel rock bits with diamond drill bits in hard rock formations has affected substantial savings.]

Jan 1, 1964

By Henry P. Chandler

[Diamond, because of its extreme hardness and abrasion resistance, has an important function in precision engineering and automation. With the increasing; requirements of modern production for fine tolerances, interchangeability, and speed, it has become even hors, important in spite of the supply of other abrasive and hard materials and of ultrasonic, electrospspark rued other substitute grinding methods world industry seems likely to absorb large quantities of diamond for industrial purposes. An increasing part of the world's needs will be supplied by manufactured diamond, which was introduced commercially by General Electric Co. in 1957. Use of diamond for glass cutting goes bark several centuries, mid diamond drilling of rock became important to the mining industry M the 1870's. Today, diamond drilling is the most extensively used method of exploring the world's ore reserves; diamond drills two also used to determine the nature of bedrock below the foundations of buildings, dams, and bridges. Diamond drill bits are now used extensively in the petroleum industry, and replacement or steel rock bits with diamond drill bits in hard rock formations has effected substantial savings.]

Jan 1, 1964

Effects of DA as a Grinding Aid on Selective Grinding of Low-Grade Bauxite Effects of DA (a copolymer of acrylic acid and acrylamide) as a grinding aid on selective grinding of low-grade bauxite were investigated in this study. The addition of DA into the grinding system enhanced the selectivity of grinding and increased the A/S ratio in the coarse fraction of ground product, leading to improved throughput of grinding mills and alumina recovery. The results showed that DA decreased the viscosity of slurry significantly and hence improved grinding efficiency due to low viscosity at a high slurry concentration. Both the hydrogen bond formation and chemical adsorption existed between DA and the surface of bauxite particles. The adsorption of DA on the surface of bauxite could decrease stress needed for crack initiation and extending during grinding, prevent new-born crack surfaces from rejoining, and promote the expansion of the cracks.

Sep 13, 2010

Considerable improvements in diamond drilling equipment have been made since the early 1950s. A recent drilling programme, however, at Williamtown, near Newcastle, carried out by the Joint Coal Board on behalf of the Electricity Commission of New South Wales, emphasized deficiencies in existing equipment when particularly diflkult coring conditions were encountered.Spurred by unacceptably low recoveries in coal seams in this area, the Joint Coal Board devised and developed, with the assistance of the Electricitv Commission, a new typc core lifter and a special 26 ft triple tube core barrel, designed to operate in conjunction with it in bad coring conditions.The core lifter, whieh is propped open clear of incoming core during drilling, is activated by fluid impulses generated inside the core barrel. It can be used with double tube barrels when drilling firm rocks whichdo not change diameter by compaction inside the barrel.Softer rocks. such as clayey types, require the use of a rriple tube barrel.Results from testing carried out to date in difficult areas in New South Wales coalfields have shown that greatly improved results can be obtained with the new equipment. Although developed essentially for coaldrilling, the new core lifter and barrel could be adapted to other fields of diamond drilling. Even in areas where no great coring difficulty is encountered the cost advantage deriving from the greatly inereased life of the core lifter and the adaptor in which it is housed could justify its use.

Jan 1, 1967

ON mineral lease 38 of the Sulphide Corporation Limited, Broken Hill, a shaft was sunk in the early days Ior prospecting purposes and at the present time it is accessible as far as the 1000-ft. level where a connexion exists with the main workings of the Corporation's Central Mine, mineral lease 9. About the year 1895· a crosscut was driven east from this shaft at the 1330-ft. level cutting the Central Ore-body in mineral lease 9 and the shaft is supposed to extend a further depth of 25 ft; but no records of any of this work are in existence, the whole of the evidence being based on hearsay and memory:Fig. 1 shows the position of the Extended shaft in relation to the main workings. The shaft filled with water to the 1000-ft. level where it overflowed through the crosscut to the main shaft and was pumped to the surface, but when the South drive on the 1300-ft. level was pushed to the southern boundary, it was deemed advisable for safety, to tap the water at this level and so relieve the...

Jan 1, 1919

By S Rupprech, T Lund, H Fourie, PH van Rooyen, NM Vegter

Rosh Pinah Zinc Corporation (Pty) Ltd (RPZC) operates an underground mine at Rosh Pinah in southern Namibia producing zinc and lead sulphide concentrates. It currently mines around 0.7 Mtpa run-of-mine ore containing around 6-10% zinc and 1.5-3.5% lead. As part of past exploration and current intensified exploration, a massive continuous low grade ore body was identified which grades at around 3% zinc equivalent. This ore body is near current mining infrastructure and could be amenable to bulk mining methods. In the present paper a concept is presented on how it could be exploited. As a precursor to exploitation of the low grade a number of enhancements are proposed for the current mining operations including: ? shortening load-and-haul distances by extending the conveyor raise further down the mine in a phased manner and back-filling of waste into mined-out stopes; ? use of mobile crushing plant at the crusher tip, and; ? installation of a system to allow scoops to load directly from stopes into ore passes close by combined with truck loops to haul from these ore passes to the crusher tip. To exploit the low grade ore body the following concepts are proposed: ? open stope mining from two areas at a total rate of up to 2 Mtpa; ? underground pre-beneficiation of mined low-grade ore near the stopes using either dense medium separation or X-ray sorting; ? pre-beneficiated tails back-filled to mined-out stopes and; ? pre-beneficiated product transported to surface by linking into proposed run-of-mine conveying system.

Jan 1, 2007

By P. C. -H. Rhee, H. -G. Lee, J. -H. Choi, D. S. Kim, S. -B. Lee

In order to predict the composition of inclusions and to ascertain a method to prevent inclusions from forming in liquid Fe-16 mass Cr alloy, a thermodynamic database was developed through a quantitative determination of thermodynamic relationships of Cr-Al-Si-Mn systems in the liquid Fe alloys. Applications of the databases to the prediction of Mn/Si complex deoxidation with Alin Fe-16 mass Cr alloy were demonstrated in succession. The electromagnetic levitation technique using a cold crucible was employed to separate inclusions from liquid metallic alloys completely and to prevent any contamination from surroundings. Various interaction parameters in the liquid Fe-16 mass per cent Cr alloy system were determined; these are: [eAl(Fe)Cr= 0.19/T, rAl(Fe)O,Cr= -0.01, rAl(Fe)O,Cr= -0.00013, eS1Cr(Fe)= -0.38/T,rSi(Fe)O,Cr= 0.007, rO(Fe)Si,Cr= 0.0044, rA1(Fe)Si,Cr= -0.0075, rSi(Fe)A1,Cr= -0.0078, rSi(Fe)Mn,Cr= 0.005, and rMn(Fe)Si,Cr=0.01.] An improved database, utilizing interaction parameters for molten metal determined in this study, and the Fact Sage slag database of the MnO-SiO2-Al2O3-CrOx-MgO system were used for thermodynamic calculations. These were carried out under various thermodynamic conditions, and results were compared with experimental data of Si/Al, Mn/Si, and Mn/Si/Al deoxidation equilibria. With the abovementioned results, together with experimentally obtained data, thermodynamic conditions were determined, in particular Mn and Si contents, under which liquid inclusions form in liquid Fe-16 mass per cent Cr alloy. The critical Al content in liquid Fe-16 per cent Cr alloy, above which solid inclusion of corundum phase ((Al,Cr)2O3) formed, was as low as 10 ppm. This indicates that extreme care must be taken in controlling the Al content in the metal to avoid formation of solid corundum phase ((Al,Cr)2O3) inclusion. The compositional change prediction of inclusions, which originate from slag entrapment and by Ca addition, was demonstrated by use of the alloy database optimized through this study, and the Fact Sage oxide database. For Si-deoxidized Fe-16 per cent Cr alloy, high Si and low basicity of slag are effective to obtain liquid inclusions. For Al-deoxidized Fe-16 per cent Cr alloy, it is important to keep the Si content lower than 0.1 per cent and it is required to add Ca. Keywords: inclusion, thermodynamic simulation, deoxidation, Fe-16 per cent Cr alloy,stainless steel, interaction parameter, cold crucible

Jan 1, 2004

By S Hu, P Ni, H Xu, P Chen

Indosinian (T) orogeny amalgamated the Mongolia-Xingan fold zone, the North China continent, the Yangtzi platform and the SE China fold zone into a unified continent. The early to middle Yanshanian (J-K1) orogeny created a Cordilleran type active continental margin in East Asia, reactivated the consolidated East China continent, and generated a large amount of granitoids, calc-alkaline volcanics and W, Sn, Mo, Cu, Au, and U ore deposits. The late Yanshanian (K2) orogeny began a transition to the western Pacific type continental margin. A tensional environment led to the development of peralkaline magmatism and tne formation of continental basins with red beds. The Himalayan (Tr-Q) orogeny was characterised by a backarc spreading and rifting regime. The dominant magmatism was continental basaltic.

Jan 1, 1995

By Jun Lu

There are many factors affecting the strength of pillar, including width-to-height (W/H) ratio, mechanical properties of coal and surrounding rocks, property of partings in the coal, and the interface property between coal seam and the roof/floor. In this paper, the effect of varying pillar?s width-to-height ratio (W/H=3, 5, 7, and 10) and coal/rock interface cohesion (Cj =50 psi, 150 psi, and 300 psi) on pillar strength has been studied. The confinement effect of W/H ratio and interface shear strength is investigated by studying their effects on the average minimum principal stress developed in the pillar. The deformation behavior of the coal pillar is investigated. It is found that the pillar?s transition from strain softening to strain hardening behavior depends on its W/H ratio and the interface shear strength.

Jan 1, 2008

EARLY in 1911 the Public Service Board of New South Wales suggested the advisability of inaugurating a School of Mines at Broken Hill, arid made inquiries to determine how such an institution should be conducted. He, the author, believed the Board, as a result of the inquiries, was in favour of the project being worked in conjunction with the Technical College, and hoped to be ready to receive students at the commencement of 1912. That the inauguration has not yet taken place is probably due to the vast amount of consideration and preparation that a new departure of the sort would require. At the present time New South Wales or, to speak more broadly under the same denunciation, Australia is not at all suitably catering for the technical training of young men to provide the increasing demand for officers to work the valuable mines within its territory...

Jan 1, 1912

By Patrick Pelletier, Pierre-Alexandre Bossé, Julie Fournier, Gianni Bartolacci, Jayson Tessier, Ahmed Bouajila, Carl Duchesne

"This paper summarizes research into the study of the control of flotation processes based on froth images. The use of numerical image analysis techniques for the extraction of significant patterns (froth structure and colour) from industrial flotation froths is discussed.First, the froth was analysed by the use of the Multivariate Image Analysis (MIA) method to extract the spectral variation contained in a RBG image. The Partial Least Squares (PLS) was applied to develop the empirical model for the prediction of froth grade. The results of this application are illustrated using one industrial case study.Second, the froth was also analysed by Gray Level Co-occurrence Matrix (GLCM) and Wavelet Transform Analysis (WTA) to extract features related more to morphological aspects. Since there is useful information hidden in froth texture, these methods are used as texture descriptor to classify different types of froths.Third, a control strategy based on a froth structure indicator was developed and implemented on an industrial zinc flotation circuit. The feedback controller uses a reagent flow-rate in order to maintain the froth structure at its set point. Process improvements obtained with the implemented control strategy are highlighted.Finally, the feasibility to implement a hybrid control strategy consisting in a froth structure supervision controller based on the froth concentrate grade estimated by MIA and recovery inferred by image analysis is discussed.INTRODUCTIONThe development of control strategies to achieve satisfactory control performance has always been a great challenge for engineers and the need for improved process diagnosis, control and optimization has become more and more evident for the mineral processing industry in the last decades. That is why new process variables need to be measured particularly in highly multivariable processes such as flotation. This industrial process is subject to a wide variety of disturbances mainly generated by frequent and sometimes abrupt changes in physical and/or chemical ore characteristics and also, due to some irregularities in manual process operating procedures. A flotation circuit scheme is always a complex network of more than two dozens slurry streams. Information about those streams (% solid, metal content analysis and flow rates) is important for process diagnosis performance evaluation and control. Also, because of the grade decrease and increasing complexity of the new processed ores, more instrumentation outputs and more powerful and significant pr"

Jan 1, 2005

By P G. Gaylard

The minerals Industry carries out over US$ 2 billion of R&D annually. The R&D is performed at three levels ? in house research facilities; on a one-on-one basis with a research provider; as syndicated (collaborative) research. The key to a successful R&D programme is project selection. It is suggested that at this time of ?bounty? for the minerals industry the research portfolio should contain some ?blue sky? but potentially long term significantly beneficial projects. This said, the projects should align the technical concepts with the business imperatives. AMIRA has found the ?Road Map? concept has assisted in defining areas for R&D. Examples of this methodology using a Copper Road Map developed by AMIRA for the copper producers operating in South America is presented. The benefits derived from syndicated research are also discussed.

Jan 1, 2007

By H. Ikeda

INTRODUCTION [Slide 1] The Role of the MMAJ Ladies & Gentlemen, it is a pleasure for me to be able to make a speech at this SME annual meeting, representing the Metal Mining Agency of Japan. [Slide 2] Today’s Topics In my presentation today, I would like to divide my topics into four parts. First of all, I would like to describe the current situation of Japanese non-ferrous metal mining and mineral processing industries in Japan. Secondly, the supply and demand of non-ferrous metals in Japan. Thirdly, I would like to spare some minutes on the overview of overseas development by Japanese mining companies. Finally, since some people may not be sure what the Metal Mining Agency is or what this Agency, I would like to briefly introduce the Metal Mining Agency of Japan.

Jan 1, 2001

By W. Greg Maybee

Separations, which form along stratigraphic boundaries in the roofs of potash mines, pose a serious safety concern. If these separations go undetected they can lead to falls of ground. The current method of identifying the location and extent of these separations is through manual scaling (sounding) using an aluminium rod. The potash mining companies would like to have a tool, which could quickly and reliably detect these separations and distinguish between them and clay seams. This paper presents the results of field trials undertaken at various potash mines in Saskatchewan belonging to the member companies of the Saskatchewan Potash Producers Association. A ground penetrating radar instrument from RST called SUSI (stepped frequency, ultra-wideband, synthetic aperture radar instrument) was used. SUSI has the ability of working over various frequency bandwidths. Four mines were chosen for these field trials, covering the different geological characteristics encountered in the Saskatchewan potash mines: Potash Corporation of Saskatchewan?s (PCS) Allan and Lanigan Divisions, Agrium?s Vanscoy Potash Operations and IMC Potash?s K2 Mine. These field trials indicated that stepped frequency ground penetrating radar technology could be ?tuned? to identify both separations and clay stratigraphy in the softrock, potash mine environment, based on the different spectral responses of the features.

May 1, 2004