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By C. Klutke

This paper outlines a simple methodology for mineral characterization, developed as part of the Australian Mineral Industry Research Association (AMIRA) managed research project P777 ?The Development of Heavy Suspension Techniques for High Density Separations (Replacement of Clerici?s Solution)?. The project was sponsored by De Beers, Rio Tinto and Iluka Resources. Heavy mineral characterization of samples arising from exploration, mining or metallurgical processes is frequently conducted using laboratory heavy liquid analysis. Unfortunately, there are only a limited number of high density (?heavy?) liquids and these tend to be more toxic as their density increases. Low-toxicity inorganic solutions, based on tungsten compounds, have been developed that can be utilized at relative densities (RD) up to 3.0. Beyond this value organic liquids can be used; however, this presents significant health and safety hazards. Diiodomethane (methylene iodide) having a relative density of 3.31 is commonly used. Mixtures of thallium formate and thallium malonate were found in the early 1900s by Clerici to provide liquids having specific gravities between 4.0 and 5.0. For the characterization of the heavy components of mineral sand deposits (e.g. anatase RD 3.9, rutile RD 4.2, ilmenite RD 4.4?4.7 and zircon RD4.6?4.8) there is currently no heavy liquid alternative to Clerici?s solution. Clerici?s solution is highly toxic and testing is now conducted by few laboratories worldwide, with costs reflecting the chemical costs, infrastructure costs and health and safety regimes (e.g. blood testing of exposed staff). A simple laboratory technique of density fractionation has been developed, employing suspensions of fine tungsten carbide particles in lithium heteropolytungstates solutions, that can replace Clerici?s solution in the evaluation of fine mineral sands samples (e.g. -250 +150microns). The developing methodology that can achieve low-cost, low-toxic separations at relative densities above 4.0 is outlined and the comparison of results with Clerici?s solution presented. In addition, preliminary work on density fractionation of zircon samples is presented. Zircon fractionation relates to their inclusion, radionuclide content and metamictization.

Jan 1, 2007

By R. C. W. Webber-Youngman

The mining industry in South Africa faces real challenges with regard to the reduction of safety-related incidents. The purpose of this paper is to highlight the need for alternative interventions in addition to other safety improvement strategies already employed on mines. It furthermore supports an existing paradigm: incident investigations. An investigation into fatalities in the South African mining industry shows that although great progress has been achieved through the reduction in fatalities in all sectors of the industry over the last few years, more can and should be done to achieve status of ?zero harm?. Fatalities and lost time injuries on mines result not only in large financial losses, but also in disruptions of mining operations in general through Section 54 stoppages to resolve the situation. The approach of the paper is therefore not to try and prove whether there is high fatality rate and/or lost time injuries, but in what way incident reconstruction simulations (IRS) can have an impact in the future prevention of such incidents. The challenge therefore lies in the utilization of pro-active systems that would show employees the possible outcomes of being exposed to certain hazards. In real life, these incidents cannot be re-enacted and in most cases we can only learn through the previous mistakes of others. A virtual reality (VR) education and training system will enable employees to be ?exposed? to different hazards in a safe environment, and simulation, in a ?forgiving? environment, of the possible consequences of unsafe acts. According to the Occupational Safety and Health Act (OSHA), unsafe acts and unsafe conditions are indirect causes of safety-related incidents, but there are also direct causes; for example, unplanned release of energy and/or hazardous material, and basic causes, for example, management safety policies, personal factors, and environmental factors. The administrative workload associated with any incident investigation places a large burden on the investigation team, and in most cases other employees are informed through vague administrative processes what the ?real cause? for the incident/accident was. New preventative strategies are often put in place without showing the employees what the real causes of the incident/accident were. This can be mitigated through the use of interactive VR simulations/animations of the hazards that they are exposed to and how to deal with them. If VR interventions are not used as proposed by this paper, the real causes and consequences of almost all fatalities and lost time injuries may never be fully understood. This paper also emphasizes what potential impact IRS could have on the prevention of future mine incidents as part and parcel of a pro-active risk prevention strategy. The intention is therefore not to replace any other risk prevention strategies, but to visually enhance the reality of the incident. Keywords virtual reality, risk management, incident reconstruction simulations, interactive safety training, usability context analysis, mine safety.

Jun 1, 2013

By A. P. L. Kotzé

Modelling and scheduling for Grootegeluk coal mine, situated in the north- western Transvaal, is by means of a series of modular systems. Modelling of the multilayered body, which is part of the Waterberg coalfield, was based on a detailed study of the behaviour of coal and waste qualities and the sub- sequent use of standard geostatistical techniques. A notable improvement on previous methods was attained. Scheduling procedures and systems were developed to model a multibench pit producing coal for several metallurgical plants as well as a power-station. Scheduling was done by producing a series of longitudinal cuts, the cuts being subdivided into increments. By allocating cuts to certain periods, the resulting calculated product tonnages were com- pared with production targets, and by iteration a final scheduling sequence was determined.

Jan 1, 1987

By L. S. Bicalho, W. J. Rodrigues, P. M. A. Rollo, P. R. G. Brandão, W. C. da Silva

Quadrilátero Ferrífero is an important mineral province located in Minas Gerais state, responsible for a substantial amount of iron production in Brazil. Among the concentration methods for iron ore practised by the mining companies in this region, the most important is the reverse cationic flotation. Dolomite iron formations, with the presence of hematite, quartz and dolomite, occur in several areas of mining and, with the deepening of the deposits, this type of ore, with low iron content and more complex mineralogy occurs frequently. Carbonaceous minerals, mainly dolomite, present a technological challenge for the concentration of iron ore by flotation. In the present study, the concentration of iron ore with 6% of dolomite content was evaluated. Bench flotation trials indicated that conventional iron ore flotation is not selective to float dolomite, thus compromising the iron content in the final concentrate. Alternative flotation routes were evaluated, and a selective condition was reached to float both quartz and dolomite using the combination of the cationic collector Flotigam 16424 with an anionic collector Flotinor 16551. It was demonstrated that the flotation of dolomite was improved with the combined use of both collectors in the cleaner stage, and by a previous quartz flotation in the rougher stage. Zeta potential analysis indicated specific adsorption as the adsorption mechanism between Flotinor 16551 and dolomite, confirming the high selectivity observed in the bench flotation tests. Keywords: Flotation, iron ore, dolomite

Jan 1, 2020

By A. Atta-Quayson

Since 2012, Ghana has been implementing local procurement regulations in the mining sector to broaden and deepen linkages between mining and other sectors of the economy. The regulations have been implemented in collaboration with the mining industry. This paper offers an in-depth analysis of how the local procurement regulations and related initiatives have been implemented so far. Primary data gathered with semi-structured interviews and secondary sources of data indicate a steady improvement in both in-country procurement and local manufacturing of inputs for the mining industry. There are, however, some challenges relating to tariff structure and support (financial and technical) for local suppliers and manufacturers to meet high standards and demands of the mining industry. This calls for a well-thought-out strategy and programme of activities to sustain and improve on progress made.

Feb 2, 2022

The vast majority of the roughly 100 million rock anchors installed in mines in the USA each year use resin cartridges1. About 4.5 million of these bolts are installed using a mechanical shell in addition to the resin to create an active (pre-tensioned) bolt. Over 1 million of the bolts are passive cable bolts and typically have an effective grout length of 1.2 m, regardless of the cable length, which could be as long as 6 m. The successful performance of the resin grouted bolts depends on several parameters, including the annular gap between the bolt and hole wall, which should be relatively small, ideally from 3 mm to 5 mm. This requirement, combined with the high viscosity of the resin, produces a high back-pressure that can cause the bolt being installed to buckle or not be installed to standard. It is this back-pressure that limits the effective grout length with passive cable bolts and causes the mechanically anchored bolt failures (typically called ?spinners? where the mechanical shell does not anchor). This creates potentially unsafe conditions and wastes time and money. A purpose, built rig was used to mimic underground installations and record the back-pressures during full scale applications in the laboratory. This information was used, and is still being used, to reduce the failures and sub-standard installations by producing improved designs. In addition, a flow model was calibrated that can act qualitatively to estimate the back-pressures and can be used as a crude screening process before full scale prototypes are built and tested. To date, the results obtained have been used to stop the use of a mechanical shell due to the proven higher rate of failures. A new, improved mechanical shell is being field tested and another system is underdevelopment. The use of the rig is therefore ongoing to develop improved mechanical anchor systems. It is too early for real data; however, anecdotal evidence seems to indicate that significant improvements can and will be made.

Jan 1, 2011

By L. M. Tavares, H. A. Petit, P. P. Cavalcanti

Iron ore pellets experience degradation during handling due low energy impacts and stresses. These impacts lead to volume or surface breakage of the pellets, creating fine particles that accumulate along the process. Some of the particles are in contact with the air and are dragged as dust into the workplace or into the atmosphere. The aerodynamic size of the particles allows them to be potentially inhaled by the workers or to be carried to nearby communities. Dust emission becomes critical at specific locations, such as transfer chutes and stockpiles. This work models the dust generation that occurs in an iron ore pellet stockyard using a methodology that combines experiments to quantify the degradation of the pellets to mathematical modelling of the dust emission mechanisms in the stockyard. First, laboratory tests were used to characterise the amount of mass and the particle size distribution of the dust generated by degradation under controlled conditions. Second, the flow over a stockpile of an iron ore pellet company was simulated with the aid of computational fluid dynamics (CFD) simulations. Third, semiempirical equations linked the data generated by simulations and laboratory tests to estimate the dust emission in the stockyard. Finally, results were validated with measured field data, obtained with a novel online measurement tool. Results suggest that the approach is able to predict dust emission with sufficient accuracy and can be used for further implementation in the management of operations and decision making in order to reduce the environmental impact of the process. Keywords: Iron ore pellets, abrasion, dust emission, mathematical modelling

Jan 1, 2020

By Y. Ren, B. Yang

The magnetic field characteristics due to electromagnetic stirring in the secondary cooling zone of an extra-thick slab during continuous casting are numerically determined using Maxwell's equations, with particular emphasis on the distribution of magnetic induction intensity and electromagnetic force, as well as the influence of process parameters on the magnetic field. The orientation of the electromagnetic force is the same when the electromagnetic stirrers at the 30° and 60° posistions of the arc-shaped slab are powered in the same direction; otherwise, the orientation is opposite. The magnetic induction at the centre of the section of the stirrer's central axis at the 30° positio, as well as the current, frequency, and fitting formulae, are as follows: B = {0.075I.(1/A)-0.3} mT and B = {-1.75f.(1/Hz)+22} mT. The electromagnetic force and current fitting formula at the central point of the B-B section is F = {0.03168I2.(1/A2)-03.762I.(1/A)+326.7} N/m3, and the fitting formula of electromagnetic force and frequency at the centre point is divided into two segments. The first takes the form of a parabola: = {-21((f-4.3).(1/Hz)2)+970} N/m3, and the second segment is negative linear: F = {-1.65f.(1/Hz)+51.5} N/m3.

Apr 16, 2024

By K. C. Mills

The objective of this work was to provide process engineers with values of the physical properties of various slag systems involved in high-temperature processes. Software that calculates the thermo-physical properties of slags from chemical composition is available on the www.pyrometallurgy.co.za website. This paper outlines the principles underlying the various models available in the program. The software calculates the following properties of crystalline, glassy, and liquid slags (where appropriate) as a function of temperature: heat capacity, enthalpy, density, viscosity, thermal conductivity, electrical conductivity, and surface tension. We hope, in the future, to update the program to (i) add new models as they become available, (ii) remove any ?bugs? discovered in existing programs, and (iii) provide guidance on the limitations of individual programs.

Jan 1, 2011

By H. Rosen

The pump is the heart of most industrial and mining plants, providing the energy to separate valuable minerals from process feed. The actual effect of the pump, both in terms of production costs and overall process efficiency, is often assumed or misunderstood by engineers due to insufficient pump performance data. Pump performance can be understood and corrected, where required, through continuous performance monitoring, leading to dramatic improvements in both pump life cycle costs and system efficiencies. The performance of every pumping application is subject to variation and the main contributing factors are as follows: ?Unavoidable deviations from pump supplier curves ?Pump wear ?Pump curve derating factors for slurry pumping ?System curve variation ?Deviation from basic principles of centrifugal pump operation. These are discussed in detail through case studies and the author?s personal experiences. This paper shows ways to minimize the effect of these variations, thereby reducing performance loss and preventing damage to the pump. The paper discusses the benefits of efficient pump operation, the requirements of pump performance monitoring, and its practical application to pump operation in the slurry and water environments. The cost of remedial actions is explored and compared against the savings in both power and plant reliability, resulting in a reduced life cycle cost of the pump.

Jan 1, 2010

By F. Petersen, W. van Dyk, J. Bonsu, A. Isafiade

"This paper aims to demonstrate how a systemic approach can be applied to the analysis of the causes of accidents in South African mines. The accident analysis framework used was developed previously by the authors from the combination of the Mark III version of the Swiss Cheese model, Incident Cause Analysis Method (ICAM), the Nertney Wheel model, and safety management principles. Data on 91 accidents occurring from 2010 to 2012 at the site of a platinum mine in South Africa were used to populate the newly developed framework. The results obtained show that while routine violations (45% of all accidents analysed) were the most common form of human error, problems in the physical environment of workers were the most common workplace factor (39.6% of all accidents analysed). Furthermore, inadequate leadership was found to be the most common systemic factor responsible for accidents (51.6% of all accidents analysed). Some workplace factors were more commonly associated with particular unsafe acts than others, and some systemic factors were more associated with particular workplace factors than others. The outcome of this study demonstrates that systemic factors, rather than human errors and violations, are the chief causes of accidents in the mining sector. IntroductionThe mining industry is a very important sector of the South African national economy. A major factor threatening the sustainability of this industry is mining accidents, which frequently result in injuries or deaths, destruction of property, and pollution of the environment. In the past, mining accidents have led to the shutdown and threat of shutdown of mines (Ryan, 2008; Mail and Guardian, 2011). The country stands the risk of incurring significant losses if the mining industry continues to experience shutdowns. In 2012, the mining sector accounted for R262.7 billion (equivalent to US$32.83 billion) representing 8.3% of GDP directly, on a nominal basis (Chamber of Mines of South Africa, 2013).Mining safety is a global concern and has attracted significant international attention. This has precipitated various studies into different aspects of mining. Unfortunately, human error has been blamed for the majority of these accidents. A study by the US Bureau of Mines found that human error is the cause of almost 85% of all accidents (Patterson and Shappell, 2008). In Australia, it is the cause of two out of every three occupational accidents (Patterson and Shappell, 2008). Various mining companies maintain that they run efficient systems, and hence the behavioural problems of workers are to blame for most accidents. An understanding of accident causality could be a major step in the quest to reduce accidents. Only with a good understanding of the accident process can effective remedies can be designed."

Jan 1, 2017

By P. A. Laxen, P. J. van Staden

In situ leaching tests with thiourea as the lixiviant were caried out in two worked-out stopes at the No. 6 shaft at Rand Leases Gold Mining Company. Dissolution rates of 0,9 and 0,7 9 of gold per week per 100 m2 of footwal area were achieved. A major disadvantage of the method seems to be the slow rate of dissolution of the gold, which is probably caused by poor contact and slow mass transfer between the lixiviant and the gold surfaces. Under full-scale application, the loss of lixiviant by leakage could also be a very important factor. Furthermore, the oxidation products of thiourea may 'poison' the activated carbon that is used for the recovery of the gold. The method may therefore be economically viable only in stopes that contain high values of residual gold.

Jan 1, 1989

By J. Uys, P. J. Mokganya, J. Olwagen, R. C. W. Webber-Youngman

This article discusses the critical role of leadership in the technology adoption process within organizations, particularly in industries like mining, where innovation is essential for maintaining competitiveness and operational efficiency. It highlights the limitations of traditional technology adoption models, such as the Technology Acceptance Model (TAM), Diffusion of Innovations (DOI), and Unified Theory of Acceptance and Use of Technology (UTAUT), which focus on individual factors and overlook the strategic and organizational roles of leadership. The study proposes the Ambidextrous Leadership-Technology Adoption (ALTA) model, which integrates leadership styles such as transformational, transactional, adaptive, and ambidextrous leadership into the technology adoption process. The model emphasizes the balance between exploration (fostering innovation) and exploitation (ensuring operational efficiency). The findings suggest that transformational leadership fosters innovation by encouraging risk-taking and creativity, while transactional leadership ensures efficient technology integration. The article also identifies key barriers to technology adoption, such as organizational resistance to change, which can be mitigated through adaptive leadership that addresses employee concerns. The research emphasizes the importance of a supportive organizational culture and cross-functional collaboration, which are essential for successful technology adoption. The study concludes by offering practical recommendations for leaders to foster a culture of innovation, manage resistance, and balance short-term efficiency with long-term technological advancement.

Nov 27, 2024

By D. Sethuram, P. G. Koppad, S. Iyengar, R. Shobha

TiB2 and CeO2 particle-reinforced Al6061 hybrid composites were manufactured using stir casting and hot rolling techniques. The base alloy and composites were hot-rolled at 500ºC and a 50% reduction was achieved through 12 passes. The effect of varying TiB2 and CeO2 particle additions on the microstructure and mechanical properties of the Al6061 matrix was studied. Scanning electron microscopy showed uniform dispersion of both the reinforcements, with good interfacial bonding. Microhardness and tensile properties like yield and tensile strength were found to be higher for hybrid composite with 2.5% TiB2 and 2.5% CeO2 compared to Al6061 alloy and other hybrid composites. The increased tensile strength is attributed to good dispersion and interfacial bonding between the particles and Al6061 matrix. Fracture analysis using a scanning electron microscope revealed ductile fracture for the Al6061 alloy and mixed characteristics of ductile-brittle fracture for hybrid composites

Oct 1, 2021

By N. T. Beukes

An engineering house?s perspective of required inputs in designing a copper electrowinning tank house and ancillary equipment calls for both understanding of the key fundamental controlling mechanisms and the practical requirements to optimize cost, schedule and product quality. For direct or post solvent extraction copper electrowinning design, key theoretical considerations include current density and efficiency, electrolyte ion concentrations, cell voltages and electrode over potentials, physical cell dimensions, cell flow rates and electrode face velocities, and electrolyte temperature. Practical considerations for optimal project goals are location of plant, layout of tank house and ancillary equipment, elevations, type of cell furniture, required cathode quality, number and type of cells, material of construction of cells, structure and interconnecting equipment, production cycles, anode and cathode material of construction and dimensions, cathode stripping philosophy, plating aids, acid mist management, piping layouts, standard electrical equipment sizes, electrolyte filtration, impurity concentrations, bus bar and rectifier/transformer design, electrical isolation protection, crane management, sampling and quality control management, staffing skills and client expectations. All of the above are required to produce an engineered product that can be designed easily, constructed quickly and operated with flexibility.

Jan 1, 2009

By H. Mulder, M. C. Bekker

The objective of this paper is to describe the research followed in creating a generalized, readiness assessment tool for mining projects. We start by highlighting the need for the assessment tool and then progress towards explaining the methodology followed during the study. The selection and finalization of the list of elements, sections, and categories that make up the unweighted values are described, followed by a summary of the weighting process applied. The outcome of this process is a weighted readiness assessment tool for mining project studies. The main benefits of the tool are that it will guide decision-makers and project managers through the definition phases of the project and improve the likelihood of project success.

Jul 2, 2022

By M. Bryson, G. Marap, M. Ntlhane, M. D. Hlahane

This study investigated flotation of phosphate from a low-medium grade 8-12% P2O5, 65-73% SiO2 sedimentary phosphate ore from Kropz Elandsfontein (herein referred to as Elandsfontein) in South Africa. Quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) was used to determine apatite grain size distribution, liberation and mineral association in the F2 horizon sample. The mineralogy indicated that apatite was liberated and for the Elandsfontein plant to operate at the design throughput, the flotation feed has to be milled to a coarse grind ranging between 300 μm and 425 μm. Reverse flotation process routes using varying reagent dosages, and flotation feed top sizes that could possibly yield a final product of 31% P2O5,10% SiO2 at a reasonable +70% P2O5 recovery were investigated. Based on the results, a split circuit of coarse (-300+212μm) flotation and fine (-212+20μm) flotation, was mostly preferred as compared to treating the whole ore. A final combined concentrate of 31% P2O5 and 10% SiO2 with P2O5 recovery of 84% could be produced from the reverse split circuit. The robustness of reverse flotation for both coarse and fine fractions was further investigated. Reverse flotation of the fines fraction was found to be robust and produced a final product of 31% P2O5. It was however more challenging to achieve the required product grade and recoveries on the coarser fraction (-425+212μm), suggesting that reverse circuit was not adequately robust at fractions coarser than 300μm. Keywords: Phosphate, sedimentary, reverse flotation, particle size

Jan 1, 2020

By G. P. O’Malley, A. N. Nikoloski

One of the most promising options for extraction of copper from low-grade chalcopyrite ores by heap leaching, however, chalcopyrite is refractory and suffers slow leaching kinetics and poor overall extraction due to formation of a passivation layer on the particles. The solution composition is believed to strongly affect the formation of this layer. This paper examines the effects of the major cationic species of Fe3+/2+, Mg2+, Cu2+, and Al3+ and the anionic SO42− species in acidic ferric sulfate media with a composition simulating recycle heap leach conditions. It was found that altering the sulfate, iron or aluminium concentration had significant effect on the copper extraction, the concentration of copper slightly influenced the extraction, and the amount of magnesium had no appreciable effect. Also, iron and aluminium caused a change in the sulfate concentration, and the sulfate ions had the greatest influence on the extraction of copper under recycle leach conditions

Jan 1, 2023

By T. Moodleya, I. Govender

Despite the widespread use of DEM to simulate particle processes, comparatively little work has been done to evaluate its accuracy. One of the reasons is a lack of available measurement techniques that can capture dynamic information at the momentum transfer timescale which is lower than 10-6 s - typical of the kinetics occurring within the drum. This work makes use of Positron Emission Particle Tracking (PEPT), an in-situ method capable of measuring 3D kinematic data at 1000 frames per second. PEPT measurements are performed using 3 mm and 5 mm mono-size glass beads in a 300 mm diameter rotating drum at critical speeds that are relevant to industry. We undertake systematic ‘tuning’ of DEM with a view to optimising the agreement between experiment and simulation. To ensure an equitable comparison scale, both the DEM and PEPT data are coarse grained within representative volume elements. This work seeks to validate DEM predictions against experimentally derived PEPT kinematic measurements. Keywords: PEPT, nuclear imaging, DEM, Tumbling Mills

Jan 1, 2020

By I. Ince, S. Kahraman, M. Rostami, B. Dibavar

The density, porosity, and strength of rocks are fundamental in the design of geo-engineering projects. Determining these properties requires the preparation of smooth core samples, which is usually impossible for soft rocks. Besides, only fragmented samples may be available in some projects. A method for predicting rock properties from rock particles such as drilling debris would therefore be useful. This study was undertaken to develop prediction equations for compressive strength (UCS), tensile strength (BTS), density, and porosity values from the crushability index (CI) obtained from rock fragments. The results showed that UCS, BTS, density, and porosity were strongly correlated with the CI. The physical characteristics and strength of rocks may be predicted with the help of the derived equations. The CI test is a valuable tool for estimating rock properties in drilling projects and in situations where core specimens are not available.

Mar 14, 2024