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By D. G. Almond

Low-grade, complex mineral deposits have resulted in the need for complicated large-throughput processing plants delivering increased productivity, reliability, and utilization, together with reducing operational costs. Complex mineralogy has resulted in complicated process flow sheets designed to recover minerals as efficiently as possible. In addition, the remote location of many minerals¬-processing plants, continuously rising energy costs, and fierce competition pose significant challenges to the modern mine, compounded by a global scarcity of qualified and experienced operational personnel. Over the last decade the Internet and automation technologies have undergone major advancements. Automation technologies, solutions, and concepts that existed, but were considered risky or unreliable prior to the year 2000, have now gained acceptance and matured. Furthermore, new technologies and different collaboration schemes have appeared, offering innovative solutions to the mining industry to address many of the challenges described. These advancements in reliable remote systems that access technology through the Internet provide significant opportunity to support mining operations, enhance process performance, provide engineering services, and proactively anticipate and execute maintenance services. This paper references a global survey of automation trends in the mining industry and the potential for an intelligent collaborative environment using automation technologies to exploit opportunities in operating the plant of the future, increasing effectiveness, and reducing operational costs. A variety of possibilities are described, including asset management solutions, remote access capabilities, performance monitoring solutions, advanced process control technologies, and the formation of an intelligent collaborative environment. A real example where this technology is used to support the operation and maintenance at a cement plant in Egypt is given to underpin the concepts described in this paper.

Jan 1, 2013

By J. G. M. Mukoya, B. Adebayo

"This work was carried out to determine the influence of rock properties and drilling machine parameters on the penetration rate at the SJ pit of Rössing Uranium Mine, Namibia. Rock properties (uniaxial compressive strength, tensile strength, and modulus of elasticity) of samples collected were determined in the laboratory. Drilling experiments were conducted in which feed pressure, air pressure, rotary speed, weight on the bit, and torque were varied to measure their effect on the penetration rate. The uniaxial compressive strength varied from 90–180 MPa for layered marble-quartzite and banded gneiss. Increases in feed pressure, weight on the bit, and rotary speed beyond the optimum level led to a decrease in penetration rate and caused the drill bit to ‘stall’. Results of the study revealed that penetration rate increases with an increase in the feed pressure and air pressure. After reaching a maximum value, the penetration rate begins to decrease despite increasing feed pressure. A very high torque causes the drill bit to stall, since the feed pressure is too high and the air pressure is not sufficient to remove the cuttings from blast-hole at maxium bailing velocities. The average penetration rate varied from 19 to 45 m/h for phase 2 of the pit, and from 17 to 68 m/h for phase 3. The optimum drilling machine parameters obtained in phase 2 and phase 3 were slightly lower than those currently being used at the mine. The trials of the optimum machine parameters will assist in reducing the cost of drilling, which varied from N$29.48 to N$36.31 per metre for the tricone bit. IntroductionDrilling and blasting contribute most to the operational cost in opencast mining and have the potential to influence the cost of downstream operations (Aipanda, 2011). The drillability of rocks depends not only on the rock properties, but also on the drilling tools and operational variables. In rotary drilling, rotational speed, thrust, and flushing are the operational variables, and are known as the controllable parameters. Rock properties and geological conditions are the uncontrollable parameters. Although, many attempts have been made to correlate drillability with rock properties, the rock characteristics affecting rotary drilling have not been entirely defined (Hartman, 1962; Kahraman, Bilgin, and Feridunoglu, 2003). The drill bit is forced into a rock surface from the rotary power head, hence creating stresses and cracks at the bit-rock interface. The performance of a particular bit in any formation i"

May 1, 2019

By R. T. Jones

Keywords: Pyrometallurgy, DC arc furnace, myths, history, hollow electrode, radiation, resistance, flicker, AC DC arc furnaces are widely used for steel scrap melting as well as for reductive smelting of ore fines. Industrial smelting applications include the smelting of chromite to produce ferrochromium, the smelting of ilmenite to produce titania slag and pig iron, and the recovery of cobalt from non-ferrous smelter slags. A number of myths and misconceptions are widely held, especially regarding: the age of the technology, the use of a hollow electrode, arc stability and shape, arc and bath radiation, interaction between the arc and molten slag, electrical behaviour of arcs and slags, a comparison between AC and DC furnaces, DC reactors, the lifespan of bottom electrodes, and the applicability of DC arc furnaces to various metallurgical systems.

Jan 1, 2011

By C. van der Merwe, R. Lumbule, J. Kgomo

"The mining industry in the Democratic Republic of Congo has seen a significant expansion in copper and cobalt production in recent years. The greater proportion of this expansion has arisen through processing of oxide ores. The design of metallurgical processes for these oxide ores is based on the conventional equipment and layout for processing of sulphide ores, and comprises milling followed by leaching, solvent extraction, and electrowinning. The physical characteristics of the oxide ores, however, provide the process design engineer with an opportunity to examine critically the principles on which equipment selection is based and to design processes better suited to these ores. In 2015, ERG Africa began a project to expand the leaching capacity of the Luita hydrometallurgical facility. A number of innovative changes to the conventional process design were included in the modified flow sheet, which were validated when the project reached design throughput in November 2017. Of these changes, the most novel presented an alternative approach to mitigate the impact of colloidal silica on the operation of the solvent extraction plant. Introduction ERG Africa operates the Luita hydrometallurgical facility located at Kakanda in the Democratic Republic of Congo (DRC), treating malachite and heterogenite minerals to recover copper as electrowon cathode and cobalt as a hydroxide precipitate. The process was originally conceived as a heap leach operation followed by direct electrowinning of copper, with solvent extraction (SX) and electrowinning (EW) of cobalt. In preparing the sized ore for the heap leach operations, the undersized ore fraction at a P80 of 625 µm was discharged to a fines storage facility for later processing. This fraction carried with it approximately 30% of the copper contained in the run-of-mine (ROM) ore feed, and an equivalent proportion of cobalt.In a subsequent development, the cobalt SX section was converted to a copper SX facility, the leached cobalt being recovered from a bleed stream from the copper heap leach circuit. The operating cost for the process as then installed placed this facility well in the fourth quartile of the industry cost curve. The initial Luita operation was established in 2010 at a time when metal prices were above long-term averages (copper above US$3.00 per pound; cobalt above US$20.00 per pound), and the drop in prices in 2015/2016 presented a major challenge. The London Metal Exchange (LME) copper price dropped below US$2.00 per pound, with cobalt dropping below US$10.00 per pound in Q1 2016. This set in motion a range of improvement initiatives for the Luita operation. Central to this was the installation of a tank leach circuit to process the discarded fines and a modified SX circuit to manage colloidal silica. The revised Luita circuit reached design capacity in November 2017 and has proven to be well suited to processing of the oxide ore feed. This process design challenges the boundaries of conventional thinking in the areas of leaching, solid/liquid separation, solution management, impurity management, and metal recovery, and is the subject of this paper."

Nov 1, 2018

By M. P. Brandt, T. P. Knoetze, I. I. M. Kessler

It has generally been accepted that the volatile mater in a coal is the factor that determines whether or not a specific coal dust is an explosion risk. This paper presents the results of an attempt to relate the explosibility index (Kex) of South African coals, as determined in a AD-litre explosion vessel, to the volatile mater content of the coal and the calorific value of the volatiles. A good relationship between the calorific value of the volatiles and the explosibility index was established, which makes it possible to calculate the violence of an explosion, as expressed by Kex, for South African coals. The Kex value is but one of a number of parameters that influence the explosion hazard in a specific colliery and cannot be used as the sole predictor of the propagation of an explosion underground. Other parameters include the ignitability of the coal, temperature, humidity, dispersibility of the dust, methane concentration, amount of incombustibles present, and ventilation.

Jan 1, 1993

By R. Scott

This article describes and evaluates the establishment of Kuyasa Mining including the search for a suitable deposit, the ongoing lack of finance, and market constraints. Despite the dramatic initial growth and success of their Ikhwezi Colliery near Delmas, Mpumalanga, Kuyasa?s experiences offer some sobering arguments for significant changes to mineral rights ownership, the attitude of financial institutions and government policy if South Africa is to have a dynamic and successful junior and small-scale mining sector.

Jan 1, 1998

By S. Soren, K. Deo Mehta, G. Jha

The paper aims to find a sustainable sintering process through cleaner means, in order to achieve the desired outputs with zero environmental impact. At present, sintering has no control over its environmental impacts. These impacts occur when fossil fuels such as coal and coke are used in metallurgical sintering. These fossil fuels are undoubtedly effective in their assigned reducing task, but simultaneously emit about 220 kg of GHGs (greenhouse gases) per tonne of sinter produced. The current attempt has focused on reducing these emission levels by switching from coke to a renewable fuel source such as biomass. Biomass is a cleaner fuel source with a significantly lower emission footprint compared to coke. In the experimental campaign, sawdust and wood-charcoal were used in substitution for coke. Experiments were designed in a progressing substitution to obtain the maximum substitution ability without compromising the sinter properties. Sawdust as raw biomass source optimally substituted 10% of coke. The substitution levels were remarkably higher (30%) for wood charcoal due to its low moisture and high calorific values. A fuel blend with 30% biomass and remaining coke succeeded in producing a sinter with acceptable quality indices. Sinters prepared with or without biomass contribution shared an identical phase transformation and microstructures. In order to to maintain consistency in the process, every effort was made to maintain all operational and process parameters identically, except for the fuelling framework. Keywords: Sintering, sustainable, biomass, GHGs, fuel substitution

Jan 1, 2020

By P. Pięta, A. Surowiak, T. Niedoba

In a flotation process of copper ore three factors were measured: copper grade in concentrate (β), copper grade in tailings (J) and recovery of copper in concentrate (e). The experiment was conducted by means of the Jameson cell. The factors influencing the quality of the process were particle size (d), time of separation (t), type of the collector (k) and dosage of the collector (s). The considered vector function was then [β(d, t, k, s), J(d, t, k, s), e(d, t, k, s)]. Optimisation achieved was based on determining the values of the adjustable factors (d, t, k, s). The goal was to obtain the highest possible values of functions β and e (maximum) and the lowest possible values of function J (minimum). To this purpose the taxonomic methods were applied. Keywords: Flotation, copper ore, lithology, flotation agents, particle size distribution, taxonomic methods

Jan 1, 2020

By J. Werfling, J. R. Kiehl

SUMMARY: The effects of blasting on structures are assessed on the basis of the maximum amplitudes of the occuring vibration velocities. If the standard values in the German Standard DIN 4150 are not exceeded, damages to structures are not to be expected. The estimation of the maximum vibration amplitudes is usually based on experience or on emperical formulae. However, a comparison of expected with measured values shows that these estimations are not conservative, particulary in case of small distances between blasting locations and structures. More reliable predictions are possible on the basis of numerical analyses, which simulate the three-dimensional propagation of waves with consideration of the geomechanical and geometrical conditions. In addition to the expected velocities, these analyses also allow the determination of stresses resulting from dynamic loading. If the dynamic stresses are known, the effects of blasting on structures can be predicted. ZUSAMMENFASSUNG: Die Auswirkungen sprengbedingter Erschütterungen auf bauliche Anlagen werden in der Praxis auf der Grundlage der Maximalamplituden der auftretenden Schwinggeschwindigkeiten beurteilt. In der DIN 4150 werden Anhaltswerte angegeben, bei deren Einhaltung Schäden von Gebäuden nicht zu erwarten sind. Die Abschätzung dieser Schwing-geschwindigkeiten erfolgt meist auf der Grundlage von Erfahrungswerten oder empirischer Formeln. Der Vergleich der prognostizierten Werte mit Meßergebnissen zeigt jedoch, daß diese Ansätze insbesondere dann, wenn die Abstände zwischen den Sprengorten und den Gebäuden gering sind, nicht konservativ sind. Zuverlässigere Prognosen sind auf der Grundlage von numerischen Berechnungen möglich, in denen die räumliche Ausbreitung von Erschütterungen unter Berücksichtigung der geomechanischen und geometrischen Verhältnisse simuliert wird. Mit derartigen Berechnungen können die zu erwartenden Schwinggeschwindigkeiten und die aus der dynamischen Beanspruchung resultierenden Spannungen ermittelt werden. Dies ermöglicht Aussagen über die Auswirkungen sprengbedingter Erschütterungen auf Bauwerke. RÉSUMÉ: Les conséquences de vibrations résultantes d'explosions pour des bâtiments sont estimés dans la pratique à partir des amplitudes maximales des vitesses d'oscillation. Dans la norme allemande DIN 4150 des valeurs d'orientation sont données, avec l'observation desquelles de dommage à des bâtiments n'est pas à présumer. Ces vitesses d'oscillation sont estimés généralement à partir de valeurs d'expérience ou de formules empiriques. La comparaison des valeurs prédits avec des résultats de mesures montre cependant que ces hypothèses ne sont pas conservateurs, en particulier si les distances entre les lieux de sautage et les bâtiments sont petites. Des prédictions plus fiables sont possibles à partir de calculs numériques, dans lesquelles la dissipation spatiale de vibrations est simulée en considération de la situation géoméchanique et géométrique. Avec tels calculs les vitesses de vibration à présumer et les contraintes résultantes de l'effort dynamique peuvent être établies. Cela permet de constater sur les conséquences de vibrations résultantes d'explosions pour des bâtiments.

Jan 1, 2003

By M. Nduna

Surface properties of metal sulphides have a great significance in various areas of engineering and science, such as acid mine drainage, contaminant sorption, and metal separation. In various attempts at producing metal sulphide particles from synthetic solutions, prodigious quantities of nuclei that grow only to colloidal dimensions have been frequently reported. This copious nucleation is promoted by the high levels of supersaturation that characterize most precipitation reactions. Colloidal particle formation in precipi¬tation-based separation processes results in sub-optimal solid-liquid separation, which is alleviated by the production of more highly crystalline particles or agglomerates. The current work approaches this challenge from an electrochemistry perspective, by measuring surface charge potential of precipitant particles during metal sulphide precipitation with respect to the concentration of metal sulphide lattice ions in solution. Electrophoresis was used to measure the metal sulphide particle zeta potential and the settling properties were obtained by performing settleability measurements using an Imhoff settling cone. A suspension of copper sulphide particles was precipitated from synthetic solutions of copper and sulphide ions at equimolar concentrations. Immediately after precipitation the copper sulphide particles had a zeta potential of -50 mV and a settleability of about 7 ml.l-1. With the addition of copper ions the settleability increased by a factor of nearly three times and the zeta potential also increased to a maximum of -40 mV. A decrease in zeta potential to a minimum of -60 mV was observed after the addition of sulphide ions and this was associated with a settleability of 0 ml.l-1.

Jan 1, 2013

By M. Steyn

The coordination compound tetrakis(1,3-diphenyl-1,3-propanediona to)zirconium(IV), [Zr(DBM)4], (DBM = dibenzoyl methane/1,3- diphenyl-1,3-propanedionol) was synthesized and characterized by single-crystal X-ray diffraction. [Zr(DBM)4] crystallizes in the monoclinic space group P21/c (a = 24.769(4) Å, b = 10.216(5) Å, c = 19.314(4) Å, and = 101.541(5)°). The coordination geometry around the zirconium atom, formed by the eight O-donating atoms of the four -diketonates, is found to be a near-perfect square antiprism. Crystal packing is stabilized by C?H... interactions throughout the crystal lattice. This structure is a noteworthy example of the application of ambient condition synthesis of zirconium compounds in N,N'-dimethylformamide (DMF) as reaction and crystallization solvent, highlighting the possibilities of aerobic condition metal purification through chelation.

Jan 1, 2014

By S. W. Robertson, M. T. Golela, S. Mxinwa

South Africa has one of the largest Cr-related industries in the world and generates large amounts of Cr-containing smelter dusts. It is normal practice to scrub Cr from the furnace off-gas in water, and to recover the Cr by adsorption, followed by recycling of the loaded adsorbent into the furnace. A study was conducted to find a low-cost adsorbent that is capable of removing sufficient Cr from the solutions generated by scrubbing. The test work focused on the evaluation of different clay minerals (attapulgite, bentonite, and kaolinite) as adsorbents for Cr. Cr(VI) could only be adsorbed after prereduction with e.g. ascorbic acid (ASA). An 80% removal of Cr(VI) could be achieved from a solution containing 20 mg/L Cr using bentonite clay after reduction with ASA. Attapulgite and kaolinite adsorbed less than 55% Cr after reduction with ASA. Both ASA and ferrous salts were found to be suitable reducing agents. The use of acid mine drainage (AMD) was also investigated as a low-cost alternative reducing agent, as AMD usually contains iron. The Cr(VI) reduction potential of the AMD was determined by redox titration against a solution containing 50 mg/L Cr(VI). Studies show that AMD can potentially be used as a reducing agent in a Cr removal process if it is available on site.

Feb 12, 2024

By R. Meyjes, P. Davies

Keywords: Pyrometallurgy, furnace, smelter, engineering company Metix is a private smelter engineering company wholly owned by its management. Its main lines of business in the ferro-alloy industry being: - turnkey smelter projects (LSTK) - engineering, project, and construction management projects (EPCM) - specialised furnace equipment comprising: ? complete electrode columns, including forged copper pressure rings and contact shoes, as well as fail-safe slipping devices ? water-cooled roofs ? bus-tube systems ? feed systems ? cooling systems ? linings ? off-gas systems ? tap-hole drills & clay guns - furnace power supply systems - ore agglomeration & sinter plants - feasibility studies & due diligence reports - technical consulting for investment banks - project procurement & cost control Metix management experience includes around 130 combined years of contacts and experience in the South African smelter industries. Over 30 furnaces have been built, for processes including FeCr (high, medium, and low carbon), FeSi, FeMn (high and medium carbon), SiMn (ultra low carbon), Si metal, and FeV.

Jan 1, 2006

By X. H. Li, Q. Zhang, X. Fei

Bauxite residue known as red mud (RM) is a by-product produced in massive quantities during alumina production by the Bayer process with a utilisation rate of less than 5%. A large amount of RM accumulated and produced continuously has had a seriously adverse impact on the surrounding ecological environment. The application of RM in building materials is considered to be the most effective and thorough way to make RM harmless and recycle resources for the reason that adding RM to concrete as a mineral admixture could not only consume a lot of RM, but also save cement and other energy-consuming industrial products. In this paper, the adaptability to cement and aggregate of RM was studied. The results showed that the compressive strength and flexural strength of concrete using ordinary Portland cement, slag Portland cement or fly ash Portland cement as cementing material showed different trends with the increase of the amount of RM. The influence rules of RM on the compressive strength of Portland cement, slag Portland cement and fly ash Portland cement concrete were similar, whether for silicate aggregate or carbonate aggregate. RM has a negative correlation to the flexural strength of silicate aggregate-ordinary Portland cement concrete, but a positive correlation to silicate aggregate-slag Portland cement, silicate aggregate-fly ash Portland Cement. RM promoted the formation of calcium carbonate crystals and inhibited the formation of ettringite and calcium hydroxide crystals in the matrix while ordinary Portland cement, Portland cement and fly ash Portland cement were used as cementing materials. This study provided support for the use of RM in concrete, the reduction of solid waste storage, and the saving of high energy consumption cement as well. Keywords: Red mud, cement, aggregate, adaptability, mechanical properties, mineral composition

Jan 1, 2020

By H. Askari-Nasab, S. Upadhyay, A. Moradi-Afrapoli

Material handling in surface mines accounts for around 50% of the operational cost. Optimum truck dispatching plays a critical role in the reduction of this operational cost in truck and shovel surface mines. Researchers in this field have presented several mathematical models to solve the truck dispatching problem optimally. However, a critical survey of the literature has shown that three significant drawbacks exist in the available truck dispatching models. The published models underestimate the importance of the interaction between truck fleet, shovel fleet, and the processing plants. They also disregard goals set by strategic-level plans. Moreover, none of the available models account for the uncertainty associated with the input parameters. In this paper we present a new truck dispatching model that covers all of these drawbacks, using a fuzzy linear programming method. The performance of the developed model was evaluated through implementatin in an active surface mining operation. The results show a significant improvement in production and fleet utilization.

Sep 1, 2021

Elongates are commonly used as stope support in South African gold and platinum mines. To evaluate the effect of the inherent strength, stiffness and yield variability associated with elongates, a statistical method is presented which addresses and quantifies the support performance at various levels of certainty. The analysis, which is based on a normal distribution, makes use of force-deformation curves determined from multiple laboratory compression tests on the same support type. The applicability of the method is illustrated making use of actual performance capabilities of various types of elongates. In order to ensure a high probability that support units installed underground exceed the standard support performance curve established by means of laboratory tests, the statistical mean of a suite of tests based on the same support type is downgraded. The ?correction factor? is a function of the mean and standard deviation of the test data, as well as the sample size of units deemed to control the local rock mass stability. It is shown that downgraded performance curves based on a high probability (90 to 95percent) of support units exceeding this performance level are suitable to ensure that the design of support systems will in variably meet the design criteria. In the highly discontinuous hangingwall rock mass typically associated with intermediate- and deep-level mining operations, the interaction between adjacent support units is comparatively limited (at the support spacings commonly used). Therefore, the appropriate sample size (n) of the support units controlling the local rock mass stability should be n= 1. In shallow mining conditions, sample sizes of up to n=5 may be warranted, depending on the spacing of joints and other discontinuities in the hangingwall.

Jan 1, 2001

By E. V. Lilford

Valuators of mineral properties are faced with a range of valuation methodologies, the most important of which are grouped under the headings of the market approach, the cost approach and the income approach. The way in which value is defined and the detail of the different valuation methodologies is examined here. This paper aims at documenting the variety of valuation procedures and applying each method to a variety of gold projects and comparing the outcomes. Any decision to apply a valuation technique will depend principally on the stage to which the project has been developed. The valuation approach to a greenfield project will be substantially different from that applied to a well-drilled, extensively explored mineral property. Furthermore, a valuation exercise may produce different outcomes for the same gold project depending on which method is applied. In order to investigate the variability in valuation methods and to explore the outcomes of different approaches, a series of five gold projects was analysed. The projects differ in regard to levels of capital application, infrastructural setting, depth below surface, in situ grade, and the stage of development, and were valued using the different methods. The most critical aspect of any valuation is the capacity of the valuer to identify the salient issues and ensure that they are incorporated into the valuation. The danger of simply applying ?black box? solutions to valuation problems without a full understanding of the parameters and the areas of uncertainty is emphasized. The importance of the valuator?s experience, insights into best practice and the ability to recognize and submit to the requirements of compliance within the minerals industry is among the most important characteristics of a valuer.

Jan 1, 2005

By G. Broadbent

It is an honour to be invited as a speaker to this ICCR conference and a pleasure to be with you here in South Africa. I have been asked to talk about the competitiveness of coal versus other energy alternatives. Coal supplies nearly one-quarter of the global primary energy. Its most direct competitors are gas, nuclear and renewables. Oil is predominantly for transport fuels. Fuel oil is competitive with coal when crude is below its long-run average price and has some niche opportunities. But I will confine my comments to nuclear, renewables and particularly natural gas as the most potent current competitive threat to coal. Competitiveness is more than just cost and price; there is environmental acceptability, security or reliability and increasingly image. These factors are more of a spectrum than discrete issues. Dollars and cents remain the key issue for competitiveness but one must recognize the impact of politics in sustainable development and energy security.

Jan 1, 2001

By S. Sarac

In this study, graphical and mathematical methods used to determine operating points in single or multiple fan ventilation systems are summarized. The problem is mathematically formulized for parallel connected fans in which analytical solutions are not possible. For n number of parallel connected fans, a non-linear equation system that consists of n number of non-linear equation sis derived. The Newton-Raphson method, which is a numerical analysis method, is adapted to solve this non-linear equation system and the solution steps are given as an algorithm. A computer program based on this algorithm is written and its applicability is proved.

Jan 1, 2000

This paper describes the extraction of gold, as the anionic aurocyanide complex, from solution by strong- and weakbase anion-exchange resins. The effects, on the rate of extraction and the loading capacity for gold, of parameters such as pH, temperature, ionic strength, agitation, and the presence of competing anions are reported. The elution and regeneration of strong- and weak-base resins will be examined in a second paper. A third paper in this series will present the results of several smallscale pilot-plant investigations carried out with strong- and weakbase resins In cyanide pulps from various South African gold mines, and will compare the metallurgical performance of resin-In-pulp with that of the carbon-in-pulp process.

Jan 1, 1984