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By S. Özgen

In this study, the possibility of beneficiation of chromite tailings in the Uckopru/Fethiye-Turkey region by a combination of hydrocyclone and multigravity separator (MGS) was investigated. The two significant operational parameters of hydrocyclone, which were diameter of the apex and diameter of the vortex, and the three significant operational parameters of the MGS, which were drum speed, tilt angle, and wash water, were varied and the results were evaluated with the central composite rotatable design. In order to produce a chromite concentrate by hydrocyclone and MGS, mathematical model equations were derived by computer simulation programming, applying the least-squares method using Minitab 15. Second-order response functions were produced for the grade and recovery of chromite concentrates.

Jan 1, 2012

By F. Hees, A. H. Bracken, L. I. Boshoff

"Biological cementation of the Mandena heavy mineral sand deposit in Madagascar was causing difficulty in dredge mining and hence in planning and control of production rates. An investigation was initiated to better evaluate the geotechnical properties of the orebody by defining the distribution and geotechnical properties of the cemented strata, in order to generate a site-specific geotechnical model for the deposit. The geotechnical characterization was developed by an integrated approach using several ground investigation techniques such as piezocone (CPTu) testing, geotechnical drilling, standard penetration testing (SPT), as well as laboratory testing. The final outcomes of the investigation included a 3D geotechnical model showing the distribution and extent of the cemented areas, as well as the typical geotechnical parameter ranges associated with each of the defined geotechnical units. The interpretations developed were incorporated into the mine and production planning to ultimately optimize operational planning and control.IntroductionQIT Madagascar Minerals (QMM) is a heavy mineral sand mining operation at Mandena, near Fort Dauphin in Madagascar. During the final planning and commissioning stages of the project, the need to fully characterize the unusual geotechnical conditions was identified and a geotechnical investigation became necessary.Nature of the problemDuring the commissioning phase it was found that mining production was being hampered by biologically cemented/indurated layers encountered within the sands. Closer inspection of the indurated horizons in the dredging face revealed that these layers contain a high loading of bacteria and fungi. It appears that the bacteria produce an extracellular (outside the cell) polysaccharide (i.e. sugar and carbon salts), which form a gelling biofilm to trap nutrients. There are a number of different bacteria. The fungi, on the other hand, produce a network of fibrous strands that bind the sand grains together. Thus both bacteria and fungi probably contribute to the ‘apparent cohesive’ strength or binding of the indurated sand (Lynn, 2008)."

Jan 1, 2017

By O. Tshifungat, A. Luzanga, N. Goel, S. Sandoval

"Tenke Fungurume Mining Company (TFM), located in Katanga Province, Democratic Republic of Congo (DRC), began production of copper cathode and cobalt hydroxide in March 2009. Copper production capacity was 115 000 t/a utilizing a semi-autogenous grinding, agitated leach, countercurrent decantation process followed by solvent extraction and electrowinning (SX-EW). Cobalt production capacity (as cobalt hydroxide) was 8000 t/a utilizing a three-stage purification/precipitation process treating raffinate from the copper SX-EW process. Recently a phase II expansion was completed, in which copper electrowinning capacity was doubled and four stages were added to the SX plant. Corresponding enhancements were made to mining, milling, and processing to bring production to 195 kt/a copper and 15 kt/a cobalt. An additional sulphuric acid plant is currently being constructed, adding 1400 t/d sulphuric acid to bring total acid production to 2250 t/d for use in leaching at TFM.Initial copper electrowinning results were satisfactory, but cathode quality and current efficiency decreased as copper production increased. The Freeport-McMoRan (FCX) Technology Centre and TFM personnel began operation of two bench-scale copper electrowinning cells in the tankhouse to diagnose chemistry effects on the cathode and anode. The results indicated an excellent electrolyte chemistry, producing finely crystalline copper at 430 A/m2 current density with 98% current efficiency. Attention next turned to the physical factors of the electrowinning cells, including electrode insulator geometry and performance. A demonstration cell was selected in the tankhouse and was operated with varying cathode and anode insulator geometries. Operation of the demonstration cell with a three-side cathode edge strip, A-style anode insulators, and an improved cell furniture design increased current efficiency from 77% to 89% at 400 A/m2 current density. Cathode quality improved correspondingly. TFM is now operating at 92% current efficiency."

Jan 1, 2016

By L. Wade

The advent of relatively cheap computing power has precipitated a rapid growth of computer usage in the mining industry. In order to obtain most benefit from this development a need is recognised for the future mining graduate to be trained in computer literacy. This paper outlines the type of training required and describes progress to date with such a programme at the University of the Witwatersrand. Certain challenges concerning the teaching effort are discussed.

Jan 1, 1987

By C. Van Rhee

In dredging practice sand is eroded at very high flow velocities using water jets. The existing pick-up functions overestimate erosion. By taking the permeability into account conventional pick-up functions can be made suitable for high velocity erosion. This can be achieved by modifying the critical Shields parameter. The procedure is demonstrated using the pick-up function of Van Rijn. The theory is compared with experiments and agreement is good.

Jan 1, 2007

By C. M. Suhr

n order to validate the borehole analysis valuation procedure commonly used in the South African gold mining industry, a simulated orebody was used to create borehole values which would serve as data for the procedure. After confirming the distribution, calculating the variance size of area relationship, estimating the block variance, and calculating a profit measurement for each set, comparisons were made to the known population parameters. Results show only one overall bias (in the estimation of the lognormal third parameter), which is carried throughout the analysis. The remainder of the analysis is unbiased, validating the procedure.

Jan 1, 1987

By K. Tobór-Osadnik, M. Wyganowska, A. Manowska

"The behaviour of employees is an essential issue in the field of occupational health and safety. Safe behaviour is to a large extent determined by, apart from motivation and preventive actions, an employee’s attitude towards hazard. Thus, attention should be given to defining employees’ attitudes, and following that, to the possibility of correcting and shaping these attitudes in relation to hazard and obeying occupational health and safety regulations. The authors have focused on the analysis of employee attitudes to health and safety regulations in Polish coal mining companies, taking into consideration earlier research on the behaviour of selected employees. The paper presents the methods used to identify Z-type (passive) behaviour. Next, this behaviour is analysed to identify differences between a Z-type employee (enslaved) and other employees. To conclude, the paper presents a list of possible motivational tools that may be used to encourage occupational health and safety in Z-type employees. IntroductionThe technical state of equipment and conditions in the workplace greatly influence occupational safety. However, the deciding factor influencing the rate of accidents in the workplace is the frequency with which employees practise risky behaviour. Factors such as the social conditioning of conduct and motivation for organizing safe work conditions have been included in the notion of creating a positive culture of work safety. This notion has been approved as one of the main goals in management (Studenski, 1996).Safe behaviour is to a large extent, apart from motivation and preventive actions, determined by an employee’s attitude towards hazard. All actions undertaken in the field of occupational health and safety, including training, motivational systems, or imitation of behaviour resulting from a high culture of occupational safety in a given work environment, will not bring about the desire effects if workers have an inappropriate attitude towards occupational health and safety regulations."

Jan 1, 2017

The relationship between the aspect ratio and physical fields in aluminium reduction cells wase studied numerically. The aspect ratio was firstly defined and 7 kinds of 320 kA cells with different aspect ratios were put forward. By using numerical simulation, the relationship between the aspect ratio and the electric-magnetic flow fields, magnetohydrodynamic stabilities, and thermal stability was discussed. It is concluded that the electric-magnetic flow field distributions are greatly affected by the aspect ratio. From the perspective of magnetohydrodynamics stability, the larger the aspect ratio is, the more stable the cell will be. A larger aspect ratio is more beneficial for the thermal stability under the same current density.

Jan 1, 2011

This paper presents a quantitative approach to the problem of determining design capacity and field dimensions of underground coal mines using room- and-pillar mining systems. In evaluating these design variables, relationships among mining costs, number of production sections in mines, location of central shafts, mine field dimensions, section production, mine output, and cost of production losses due to underground man-traveling are analyzed. Thereby the unit cost of coal is expressed as a function of the design variables as well as input parameters such as seam angle, seam thickness, seam depth, underground traveling speed of men, mine recovery and plant recovery. The problem is then formulated as a nonlinear optimization model in terms of minimizing the unit cost of coal subject to a set of constraints and solved analytically for flat seams and numerically for inclined seams. Sensitivity analysis of the variables is also included in the paper.

Jan 1, 1987

By D. R. Hardman

Coal mining has been practised in South Africa for over one hundred years. The total production increased gradually in the early pat of the twentieth century, but over the past twenty years the rate of growth has been considerable. Although opencast mining has contributed largely to this increase in production in recent years, underground bordand- pillar operations still contribute slightly less than 50 per cent of the total production. The paper highlights problems arising from old bord-and-pillar workings, and an indication is given of how some of the problems have been addressed.

Jan 1, 1990

By I. H. Clark

In some mining situations, backfills are not only required to be free-standing but are also expected to provide hangingwall support. It may therefore be specified that the backfill withstand a certain calculated stress within a given time. Given the materials available, the choice of backfill composition is not always straightforward, and an approach to the evaluation of cemented tailings backfill is therefore proposed. The general use of such a method will greatly assist in both the scientific analysis of the material properties for industry-wide purposes of comparison and decision-making as regards the choice of fill.

Jan 1, 1988

By A. Mainza

It is common practice in the mineral processing industry to use hydrocyclones for particle classification. However, classification in the UG2 platinum circuits using the hydrocyclone poses major challenges due to the differences in density between silica and chromite, the two major components of this ore. Silica,-the PGM carrying component, has an average density of 2.7 and the barren chromite component has an average density of 4.5. When conventional and flat bottom cyclone are used there is a misplacement of particles due to differences in density leading to inefficiencies in the classification by size. As a result of the density effect, coarse silica reports to the overflow, resulting in loss of recovery, and fine chromite reports to the underflow, resulting in loss of milling capacity and unnecessary production of fine chromite. A classifier based on a different concept was required in the classification of UG2platinum ore. The three-product cyclone, which is a hydrocyclone with two concentric vortex finders to produce three distinct products, has been tested in the UG2 ore application and indications are that misplacement of particles due to differences in the component densities can be minimized through the use of this unit. Industrial and pilot plant trials were conducted and indications are that the three-product cyclone can be installed to selectively produce a middlings stream that can be screened using Pansep screens to provide a screen oversize, which is predominantly coarse silica that can be preferentially reground to recover the PGM values contained in the coarse silica.

Jan 1, 2004

By A. A. Bradley, K. H. Stanton, P. J. D. Lloyd

A theory for the dynamic balancing of centrifugal mills is presented that takes account of the mass and shape of the charge in a gyrated grinding tube and the way in which the charge lags behind the centrifugal force vector. predicts that a corresponding lag in the angular position of the counterweight centres of mass is necessary, and that the fractional filling should be increased if the ratio of gyration diameter to tube diameter is decreased. A worked example is given for a I MW centrifugal mill that was balanced adequately by the methods described.

Jan 1, 1983

By W. K. Brinsden

The Australian Institute of Geoscientists (AIG) held their fifth successive annual seminar at Observation City, Scarborough, in Perth on 15th November, 1990. The title of the seminar was 'Strategies for Grade Control'. The Seminar attracted 158 delegates, including 10 speakers. In addition to geoscientists, the attendees included mining engineers, metallurgists, and mining analysts. The welcoming address was given by Rob Duncan, Chairman of the Westem Australian Branch of AIG, who said there is a strong demand for this type of seminar in Western Australia (WA). It helps geoscientists to keep up with former colleagues and to keep abreast of technical developments.

Jan 1, 1991

By J. Baklík, V. Rak, W. Kolarcík, Z. Franc

The paper deals with hydraulic transport of thin and dense slurries. Based on mathematical modelling of three-phase flow, dynamic properties of the systems for pumping of thin slurry are solved. Theoretical calculations were experimentally verified both at the testing hall and in real operation. For thin slurry (e.g. bauxite slurry), a three-chamber hydrohoist with float is used. Dense slurry (e.g. ash and water) is transported from the power plant to a deposit site by means of a three-chamber hydrohoist with sealed separator (piston).

Jan 1, 2007

By M. Pötsch, M. Blümel, E. A. Button

ABSTRACT: Stiffness controlled test procedures performed with servo-controlled shear systems are the most versatile for simulating the wide range of boundary conditions expected in nature. Examples of a function controlled procedure in addition to dilatation controlled procedures are discussed for different characteristic behaviours. ZUSAMMENFASSUNG: Steifigkeitskontrollierte Scherversuche mit servohydraulischer Steuerung eignen sich gut unterschiedliche Bettungen, wie auch in der Natur vorkommen, zu simulieren. Beispiele für spezielle Steuerungsfunktionen und dilatationsgesteuerte Prozeduren mit verschiedenen charakteristischen Eigenschaften werden diskutiert. RESUMÉ: La rigidité a commandé des méthodes d'essai exécutées avec les systèmes asservis de cisaillement sont la plus souple pour simuler l'éventail d'états de frontière prévus en nature. Des exemples d'un procédé commandé par fonction en plus des procédures commandées par dilatation sont discutés pour différents comportements caractéristiques.

Jan 1, 2003

By F. M. Russell

Scheduling the extraction and rates of production for an underground mining operation is a common task carried out during the life of a mine, from the initial feasibility study through to the final production phase. The scheduling process can be complex when several requirements have to be satisfied, for example, match mill capacity and maximize net present value while constrained by mining sequence and availability of resources. Many mines have computer programs relevant to their operation but because they are site-specific they need considerable reprogramming to be adapted to other operations. Other methods currently in use also suffer drawbacks: manual spreadsheets are laborious, computerized spreadsheets cannot handle sufficient constraints, and operations research techniques require a complex mathematical model to be set up. The use of network analysis techniques has been proposed previously but the unavailability, until recently, of easily used computer programs has not allowed this approach to be developed. There are now many programs which can be used; however, the particular program which has been adapted to mine scheduling is Metier's 'Artemis-PC' running on IBM-XT or compatible machine. The use of network analysis offers many advantages, including the use of a logical mining sequence; activities can be as detailed as required; related activities can be readily incorporated, and costs can be easily extracted. A heuristic approach is necessary to optimize the schedule, but the ease and speed of program execution enables this to be readily achieved, while leaving the mining engineer in full control. The paper discusses the problems encountered in mine scheduling and current solutions. It then details the use of network analysis techniques and the application of the Artemis-PC program to solve mine scheduling problems.

Jan 1, 1987

By K. Grossauer, W. Schubert

For tunnelling in poor and heterogeneous ground a reliable on-site short-term prediction is required to allow a safe and economical construction. With the use of absolute displacement monitoring data and advanced software for evaluation of the data in combination with a routine update of the geological model a considerable increase in the reliability of the short-term prediction could be achieved. The paper deals with theoretical considerations, numerical studies and case histories from alpine tunnels in heterogeneous rock. Tunnelbau in schlechtem und heterogenem Gebirge erfordert auf der Baustelle eine verlaessliche Kurzzeitprognose, um ein sicheres und wirtschaftliches Bauwerk gewaehrleisten zu können. Die Verwendung von absoluten Verschiebungsmessdaten und deren Auswertung mit Hilfe von hoch entwickelten Softwareprogrammen in Kombination mit einer laufenden Aktualisierung des Gebirgsmodells ermöglicht eine erhebliche Erhöhung der Verlässlichkeit von Kurzzeitprognosen. Dieser Beitrag beschäftigt sich mit theoretischen Ansätzen, numerischen Modellen und Fallstudien von Tunnelvortrieben in heterogenem Gebirge. La construction de tunnels dans la montagne hétérogène de faible résistance exige un pronostic fiable à court terme sur le chantier, afin de pouvoir garantir un ouvrage sûr et économique. L'utilisation des données de mesure de décalage absolues et de leur évaluation à l'aide de logiciels sophistiqués en combinaison avec une mise à jour courante du modèle de la montagne permet une augmentation considérable de la fiabilité des pronostics à court terme. Cette contribution présente des approches théoriques, des modèles numériques et de cas pratiques de progressions de tunnels dans des montagnes hétérogènes.

Jan 1, 2003

By B. Zongwane, A. T. Visser

In surface mining operations, ultra-heavy trucks operate on haul road networks which are typically from 10–40 km in length. Road networks for these vehicles have historically been designed and maintained empirically, relying heavily on local experience. Whilst it is possible to construct amine haul road that requires no maintenance over its service life, this would be prohibitively expensive, as would the converse but rather in terms of vehicle operating and maintenance costs. An optimal functional design will include a certain amount and frequency of road maintenance which can be planned, scheduled and optimized within the limits of required road performance and minimum vehicle operating and road maintenance costs. For existing mine haul road networks, which may not be optimally designed and maintained, the problem of identifying existing deficiencies, quantifying their impact and assigning priorities within the constraints imposed by limited capital equipment and manpower is problematic. This is reflected in the fact that most surface mine operators agree good roads are desirable, but find it difficult to translate this into an effective road maintenance system. The aim of this paper is to present a road maintenance management system which utilizes on-board truck diagnostic data in conjunction with computer-based truck dispatch systems. Through a comparative analysis of the various haul road maintenance systems available to a mine, a condition-triggered road maintenance system is introduced. System architecture, evaluation of real-time data, event trigger level determination, specific condition signatures and real-time rolling resistance calculation are discussed. Finally the event, activity, transaction and notification system is portrayed in conjunction with the determination of key productivity indicators and benchmarked road and truck performance. Keywords: Haul road, maintenance, surface mining, rolling resistance, truck haulage.

Sep 1, 2001

By L. H. W. Walker

As part of an overall design of a computer based mining managerial system, the geological and mineral estates management disciplines find themselves centrally placed in terms of producing fundamental data both before and during the mining operation. Computerisation of all aspects of these fields of endeavour has come to be seen as essential for complete integration with other mining orientated disciplines. Release 1 .l. of the Anglo American system of mineral estates management has been tested and is in the process of being implemented at several Anglo American Gold Division mines.

Jan 1, 1987