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By W. C. Joughin

Problems with the stability and performance of rockpasses in deep-level mines are common. This paper presents the results of an investigation into the recorded performance of rockpasses in deep-level gold mines. Records relevant to the geological environment in which the passes are excavated, their excavation details, and their historical performance are not at all well documented on mines. In general, the quality of data available from mines is poor. The investigation showed that very large spans frequently developed in passes during use, and that rock mass quality, the orientation of the pass with respect to the dip of the strata, and the magnitude of the stress acting normal to the axis of the pass were the main factors of influence. From the historical information obtained, the risks of instability in rockpasses are identified.

Jan 1, 2005

By N. Duda, W. Koperska, S. Anufriiev, P. Stefaniak

In mineral processing plants ore extracted from mines is processed to obtain a concentrate with the highest possible concentration of this valuable product. It is a complicated multi-stage process. Usually, the first step is sieving the ore, which is typically done using vibrating mining screens. There is often only a limited number of these machines in the technological chain, which is why their continuous operation, and proper maintenance is crucial for the whole process. Predictive maintenance is the best strategy in this case because it allows for minimising the number and duration of unexpected stoppages. It consists of the prediction of future failures based on available real-time data, and predictive models built upon this data using, for example, machine learning techniques. In this paper we concentrate on feature generation for future predictive maintenance model development for a vibrating screen, based on an example of a KGHM ore processing facility in Polkowice-Sieroszowice. We focus on two types of measurements: bearings temperature and vibrational data. Based on the raw data, the process of more advanced feature engineering is described. By transforming the temperature data we calculate characteristics of bearing cooling and heating dynamics, while based on vibrational data, the aggregated characteristics of the vibrations are derived. Such features are calculated on a long-term basis, and then they are compared to the data related to vibrating screen maintenance to estimate their significance for the prediction of particular failures of the machine.

Sep 1, 2021

By L. Cheng, Y. Liu, Z. Shen, H. Shang, Y. Li

The pre-concentration process of magnetic coarse particles can discharge waste rock or liberated gangue before milling, which is an effective means to reduce cost and increase the efficiency of the concentrator, but the weakly magnetic ore doesn’t have the effective separation method of coarse particle such as hematite, limonite, ilmenite and so on, Because the composite iron minerals contain both strong and weak magnetic elements, the pre-concentration process cannot be applied, or the existing pre-concentration process has problems of complicated configuration and high operation cost. By researching a new type of external magnetic separation technology, the pre-concentration process of composite iron ore was realised by single equipment, which can have a good recovery rate with simple arrangement. In this paper, the separation principle and structure characteristics of the external magnetic separator were researched, and the magnetic circuit characteristics of the external magnet were analysed. The laboratory tests of vanadium titanium magnetite were conducted, and the test results proved that the external magnetic separator can be applied for the pre-concentration process. The industrial application shows that a product of TFe 24.76% with 90.08% recovery, TiO2 10.10% with 91.78% recovery can be achieved from the feed of TFe 20.67%, TiO2 8.33%. Keywords: Coarse particle pre-concentration, composite iron ore, external magnet, magnetic separator

Jan 1, 2020

By B. J. Buys

Rock bolt integrity is a critical issue for the mining industry because of its influence on the safety of mining operations. Guided ultrasonic wave testing of the defects associated with resin-anchored rock bolts was investigated. Axisymmetrical and three-dimensional finite element models were built, one of a partially encapsulated bolt and the other of a bolt with a simulated local corrosion crack. Experimental bolts were then installed in a testing block and typical responses were compared to finite element models of different defect scenarios. Encouraging results were obtained for the smaller axisymmetrical and three-dimensional finite element models, as well as during the experimental investigation. It is recommended that software with energy-absorbing elements should be utilized to consider higher frequencies and longer bolts. Once the integrity of models such as these has been established, the models could in principle be used to train neural networks for use in commercial equipment to determine the integrity of the installed bolt.

Jan 1, 2009

By E. T. Boshoff

Paper written on project work carried out in partial fulfilment of B. Eng. (Metallurgical Engineering) The weathering of kimberlite can be accelerated with cations in solution if swelling of the kimberlite occurs in contact with the weathering medium. The type and amount of swelling clays present, along with the surface charge and cation valence, determine the degree of swelling that can occur. Crystalline swelling occurs by the incorporation of cations in the interlayer spacing of the silica sheets. Kimberlite exposed to cupric cations showed very strong weathering, indicating that this type of weathering may be considered a viable process option. Kimberlite fines generated after weathering with monovalent cations showed poor settling behaviour compared to kimberlite weathered with di-, and trivalent cations.

Jan 1, 2005

CSIRO Mineral has recently developed a new electron microprobe based system for characterizing zircon grains from heavy minerals sand deposits. The system acquires cathodoluminescence (CL) spectra, X-ray and backscattered electron (BSE) signals in parallel. By scanning over a specified target area, CL wavelength and X-ray element distribution maps of polished zircon grains can be acquired. Post-inspection of the combined dataset using in-house developed software enables correlations between chemistry and structure to be investigated. The new method offers significant benefits over traditional CL and BSE techniques in that direct comparison with the elemental concentrations over the same region is now achievable. By combining the electron microprobe results with data for the same mapped region obtained via a nuclear microprobe, significantly better detection limits (~ 1ppb) for elements with atomic numbers greater than iron are possible. The ability to measure spatially related analytical data and then investigate the correlation of the CL spectra with chemical data is an important advancement in the characterization of zircons. Key words: zircon, characterization, cathodoluminescence, backscattered electron, electron microprobe, nuclear microprobe, chimage, proton induced x-ray emission.

Jan 1, 2003

By J. Rivoirard

Historically, linear and lognormal krigings were first created to estimate the in situ mineral resources of blocks. Nonlinear geostatistics and indicator kriging were subsequently developed to evaluate also the portion recovered when applying a cut-off on selective mining units (SMUs) within blocks. In practice these methods are generally based either on the Gaussian model with a transformation generalizing the lognormal case or on the indicators above cut-offs. Very often the indicator approach is simplified by kriging separately each indicator, and when starting from a continuous variable, a practical advantage of the discretization into classes lies in the easy treatment of a zero effect and of the high values. However, a number of so-called isofactorial models have also been developed for a discrete or continuous variable, where the full cokriging of indicators (i.e. disjunctive kriging) simplifies to the separate kriging of factors. Moreover, these models are equipped with a change of support, allowing a consistent estimation of recoverable resources on SMUs. Min-Max Autocorrelation Factors (MAF) analysis of the indicators offers a new approach for indicator modelling. In particular the first factor, the one with the highest spatial continuity, can help in choosing the type of model. For example a monotonic experimental first factor can be used directly as the basis of a discrete diffusion model, unless a continuous diffusion model such as the Gaussian model can be used on the original variable. This approach is illustrated on a uranium deposit mined selectively: estimates of recoverable resources by discrete disjunctive kriging and uniform conditioning in a Gaussian model are compared locally to short-term estimates based on two areas densely drilled.

Jan 1, 2014

By A. More, J. M. Míguez, J. Bullón

In 2000 Ferroatlantica started a project with the aim to develop a new casting machine for silicon and other ferroalloys. Until now, it has been cast more than 25.000 tons of silicon for the chemical and metallurgical market. This system has improved the process yield, productivity and product quality which place?s Ferroatlantica at the top of technology development in this field. After the first presentation of the Ferroatlantica?s casting machine at Infacon X, we would like to show the improvements in the control which have permitted us to increase the lifetime of the copper and to obtain, at the end of the machine, the right product size for the customer avoiding the current necessity of crushing and sizing the lumpy metal. Furthermore, we have improved the system in relation to the obtaining of smaller granulometries at the end of casting machine. Not only is this kind of machine cost competitive for special silicon applications but also for other normal ferroalloys with different specifications of size and thickness.

Jan 1, 2007

By G. Kleyn

"Sub-standard practices and their adverse impact on safety performance remain a challenge in the South African gold mining industry. The purpose of this study was to investigate the root causes of sub-standard practices and the effect on safety performance in South African gold mines. The focus of the study was on the underground production operations at a gold mine in the Free State. The study consisted of three parts: a personal investigation into the causes of sub-standard practices at the mine, a comparison with the results of a cultural study performed at the West Wits mines, and a behavioural survey.The studies described in this article yielded similar results in terms of the key drivers behind sub-standard practices. It was found that substandard practices had a number of causes, and the origin lies within the habits, attitude, and behaviour of employees. Current methods of addressing sub-standard practices and improving safety performance were found to discourage employees from performing work safely and according to procedure. It was concluded that the lack of critical behavioural habits for the given work environment and job title could possibly be the primary reason for the occurrence of sub-standard practices. IntroductionSince the implementation of the Mine Health and Safety Act, 1996 (Act 29 of 1996) and the Mine Health and Safety Regulations, the South African mining industry has been striving to improve health and safety performance and has placed great emphasis on adherence to mine standards.The Act requires employers in the mining industry to report accidents, incidents, and dangerous situations to the Regional Principal Inspector of Mines in their area. The data provided by employers is captured and analysed by the South African Mines Reportable Accident Statistical System (SAMRASS) and made available for public viewing (Department of Mineral Resources, 2011).A review of the national mine-related accident statistics shows clearly that the South African gold mining industry has improved its safety performance markedly over the past decade, but is still facing major challenges (Figure 1). These include meeting the Mine Health and Safety Milestones (Department of Mineral Resources, 2011)."

Jan 1, 2016

By A. Whillier

The decisive action taken by mine managements in recent years has been the main factor in bringing about the present downward trend in mine fires. A better understanding of the fundamental factors that govern the ignition and spread of fires. obtained as a result of investigations into mine fires, has provided useful guidance to production personnel. Similar investigations into fire-fighting techniques have assisted the Rescue Training Service and mines to institute more effective fire-fighting techniques. Some of the more important findings of recent investigations in these areas are outlined.

Jan 1, 1981

By T. Tamura

It is known that the CaO-FetO-P2O5slag system has a wide liquid miscibility gap at steelmaking temperatures and this two-liquid slag phase has many advantages such as high activities of both FetO and CaO and high amount of P2O5. The phosphorus distribution ratio between the two-liquid slag and molten steel was confirmed to be higher than that between CaOsat.-FetO-P2O5slag and molten steel. The two-liquid slag may be useful for dephosphorization of molten steel and reduction of slag volume. Furthermore, the phase equilibrium of two-liquid CaO-FetO-P2O5slagsaturated with MgO was measured to determine the applicability of the two-liquid slag to dephosphorization in steelmaking process. Keywords: slag, refractories, solid solution, two-liquid phase, dephosphorization, steelmaking, phase equilibrium.

Jan 1, 2004

By R. E. Robinson

I shall present a concept for the development of the resources of this country and its neighbours that repre¬sents a fantastic challenge to our scientists and entre¬preneurs. This concept offers prospects of development that must make our previous achievements seem equivalent only to the first act in a drama enacted on the stage of Southern Africa. I hope to illustrate how, in Act Two, chemistry will play a dominant role, and chemists and chemical engineers will be among the principal actors.

Jan 1, 1980

By S. Hlajoane, L. S. Mokhahlane

The demand for rare earth elements has increased around the world due to their application in a variety of technological advancements. Previous studies have evaluated the potential of the rare earth elements and yttrium (REY) hosted within the Permian coal deposits of the main Karoo Basin (MKB) in Southern Africa. However, not a lot of scientific research has gone into the Triassic coal deposits. The Triassic coals in South Africa were the first coals to be exploited for their thermal use in the 1880s, but the discovery of the higher rank and more abundant Ecca coal deposits led to the Triassic coals remaining largely unexplored. The demand for rare earth elements has sparked interest in these coal deposits as potential sources for valuable minerals. Late Triassic coal deposits in Lesotho have previously not been well documented and these low-rank coals can be a potential source of rare earth elements. This study aims to characterize and evaluate the potential of REY in the Taung coal deposit, southwest of Lesotho. Coal and associated argillaceous samples from the Taung coal deposit were analyzed using microscopic petrography for coal characterization and an inductively coupled plasma mass spectrometry (ICP-MS) to determine the amount of rare earth elements. Taung coal is classified as middle medium rank D bituminous coal. The total REY content in Taung coal and its associated rocks range from 162.9 ppm to 855.1 ppm, which is significantly higher than the upper continental crustal (UCC) average. The average critical REY concentration of samples from the Taung coal deposit is 189.4 ppm, which is three times higher than that of the Chinese Bayan Obo deposit. Samples classified as very promising and promising because of their outlook coefficients, are found to contain up to 77% of critical REY. It is envisioned that the area could be a prime deposit for these REY.

Nov 6, 2024

By M. Görnerup, A. Kapilashrami, Seetharaman. S., A. K. Lahiri

Simultaneous reduction and foaming of chromium-rich slag have been studied in a laboratory furnace equipped with X-ray image analysis. Reduction of the metal oxides by graphite generated CO, which caused the melt to foam. The slag composition continuously changed due to reactions and dissolution of lining. Gas generation rate, foam height, and gas bubble size were studied and correlated to slag composition. Viscosity increased significantly during the experiments due to a change in slag composition. Bubble sizes varied little during the progress of reactions but differed considerably for different slags. Bubble sizes were largest for V2O5 containing slag, which is contrary to the general understanding that the presence of strong surface active agents reduces the bubble size. The foaming index did not follow expected trends for bubble size and viscosity, suggesting that foaming index is not a suitable parameter for discussion of foams under dynamic conditions. Keywords: slag, foaming, dynamic conditions

Jan 1, 2004

By E. Matinde

Human beings have been dependent on metals and alloys for livelihoods since time immemorial. In fact, there is irrefutable evidence that successful ancient civilizations achieved supremacy over their environments through the mastery of metals and alloys (Miller, 1995; Mtetwa, 2022). Over time, metals and alloys have evolved to become ubiquitous engineering materials indispensable to mankind, with applications in industrial and residential infrastructure, agriculture, energy generation and storage, transportation and communication systems, and manufacturing, among others (Elshkaki et al., 2018; Watari et al., 2021). Population growth, technological developments, and increase in urbanization and industrialization are all intricately linked to the intensity of use of metals and alloys. With up to 5 billion people estimated to live in urban areas by 2030 (Armstrong, 2009), the demand for metals and alloys will inevitably increase in order to satisfy the increased demand for infrastructure, machinery, and other human needs (Elshkaki et al., 2018; Watari et al., 2021). According to LePan (2022), urbanization and growth of mega-cities will increase the demand for metals and alloys, such as nickel, steel, aluminium, and copper by 116%, 50%, 57%, and 26%, respectively, between 2019 and 2035. Naturally, the production of metals and alloys from natural ores, secondary resources, and/or a combination of both, to meet this increased demand will invariably lead to the increase in generation of deleterious emissions in the form of wastes. In fact, mining and metallurgical wastes currently constitute the world’s largest anthropogenic streams by mass, often containing a high concentration of elements and compounds that can cause potential damage to natural ecosystems and humans (Hudson-Edwards et al., 2011; Lottermoser, 2011; Matinde et al., 2018; Seetharaman et al., 2022). Obviously, society’s heavy reliance on new mineral resources to drive the emerging energy transition entails that the legacy of these waste streams will continue unabated for the near-foreseeable future. The scarcity of high-grade mineral reserves, coupled with deliberate efforts to solve the anthropogenic circularity conundrum, therefore introduces a high level of urgency in the metal extraction industry to develop nascent and more eco-friendly processes and technologies. Integrating circular economy principles based on intentional configurations of circular industrial ecosystems in order to maintain the value of materials and resources in the economy for as long as possible is widely accepted as a practical approach to mitigating the negative externalities imposed by

Sep 1, 2024

By V. S. S. Yadavalli, J. Hager, R. Webber-Youngman

"This article investigates the complex problem of a budgeting process for a large mining operation. Strict adherence to budget infers that financial results align with goals. In reality, the budget is not a predetermined entity but emerges as the sum of the enterprise’s operational plans. These are highly interdependent, being influenced by unforeseeable events and operational decision-making.Limitations of stochastic simulations, normally applied in the project environment but not in budgeting, are examined and a model enabling their application is proposed. A better understanding of budget failure in large mines emerges, showing that the budget should be viewed as a probability distribution rather than a single deterministic value.The strength of the model application lies with the combining of stochastic simulation, probability theory, financial budgeting, and practical scheduling to predict budget achievement, reflected as a probability distribution. The principal finding is the interpretation of the risk associated with, and constraints pertaining to, the budget.The model utilizes a four-dimensional (space and time) schedule, linking key drivers through activity-based costing to the budget. It offers a highly expressive account of deduction regarding fund application for budget achievement, emphasizing that ’it is better to be approximately right than precisely wrong’."

Jan 1, 2015

By Siyabonga Malevu

Chemical Initiatives? Umbogintwini plant is the production facility of Chemical Initiatives? business. Umbogintwini?s J Plant manufactures sulphuric acid. The plant was designed and built by Simon Carves, and was commissioned in 1974. The plant was designed to produce 500 tons/day of Sulphuric acid (H2SO4) at maximum rates. The Sulphuric acid manufacturing is through the famous contact process whereby liquid Sulphur is injected through dried air in a burner operating at 1000 °C to form sulphur dioxide (10.5% SO2). The SO2 gas is then cooled in waste heat boiler no.1 before being fed to a four pass converter which provides 99.5% SO2 conversion to sulphur trioxide (SO3). The SO3 gas is the absorbed by 98.5% H2SO4 through the inter-pass & final tower to make more concentrated acid and dilute it with water back to 98.5% H2SO4 in acid pump tanks and dispatched to storage tanks. The manufactured Sulphuric acid is supplied to a variety of industrial manufacturing customers includes Pulp & Paper industry, Mining industry, Chemical manufacturing industry etc. During the 1st quarter of the year 2007, Chemical Initiatives undertook a study to up rate the sulphuric acid plant output by 10% (i.e. from 500 tpd to 550 tpd).

Jan 1, 2009

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 M. Z. Emad, N. Abbas, Y. Majeed

Room-and-pillar mining is commonly employed for the extraction of rock salt in undergroundmines. Pillar stress is a major concern in these mines as it is directly related to stability and mineralrecovery. In this study a flat jack method was used to measure pillar stresses in three undergroundrock salt mines in Pakistan. The field work included determination of in-situ stress, in-situ elastic modulus, recording of field variables (pillar length and width, height and width of opening, opening width to height ratio, extraction ratio, and overburden height) and collection of salt block samples. The geomechanical properties of rock salt (uniaxial compressive strength, Young’s modulus, Brazilian tensile strength, and density) were also determined to estimate overburden stress, pillar strength, and factor of safety (both estimated and actual). It was found that the measured pillar stresses are proportional to the overburden stress values, with their magnitude ranging from 6.05 MPa to 11.97 Mpa, and the pillars were found to be stable. Regression analysis was performed to develop statistical models for in-situ stress and in-situ elastic modulus. Finally a quick guideline chart was developed to determine the suitable length of pillar for a given span and required level of safety.

Jun 5, 2023

By L. Malmgren, A. Ansell

This paper deals with the influence from blast induced stress waves on the performance of shotcrete support in the Kiirunavaara mine. Time histories of stress waves from blasting were obtained from measurements during production blasts in the mine, followed by failure mapping. A finite element model, consisting of beam and spring elements, was used to calculate the shotcrete response to vibrations from blasting. The modelling approach was similar to that of a building during an earthquake, with accelerations measured in-situ used as loads. The analysis showed that the calculated adhesive stresses exceeded the strength in the interface between rock and shotcrete near to the blasted ring. It also indicated that tensile rock failure did occur. These types of failure will presumably result in ejection of joint defined rock blocks or rock slabs and will require a ductile support, such as fibre reinforced shotcrete. The predicted failure was confirmed by the mapping, which also showed that the zone of failed shotcrete was much larger in areas with plain shotcrete compared to areas with reinforced shotcrete. L’influence de l’onde de pression générée par les sautages à la mine de fer de Kiruna sur la performance du béton projeté est étudiée dans le présent article. Les ondes créées par les sautages ont été enregistrées et les domages résultants ont été cartographiés. La réponse du béton projeté aux vibrations de sautage est étudiée à l’aide d’un modèle d’éléments finis, constitué de poutres et de ressorts. L’approche est similaire à celle d’un immeuble subissant un tremblement de terre, avec les accélérations internes utilisées comme charges. L’analyse montre qu’à proximité des sautages, la contrainte adhésive dépasse la résistance de l’interface roche-béton. L’analyse confirme aussi l’existence de ruptures en tension. Ces types de rupture induisent probablement l’éjection des blocks définis par les structures du massif rocheux et requierent un support ductil, comme du béton projeté renforcé par exemple. Le type de rupture est confirmé par les observations de terrain, qui montrent aussi une extension plus importante des domages lorsque le béton projeté n’est pas renforcé. In diesem Konferenzbeitrag geht es um den Einfluss, der aus einer Sprengung hervorgerufenen Schwingungswellen auf die Ausführung der Spritzbetonverstärkung in dem Kiirunavaara Bergwerk. Die Aufzeichnungen der Schwingungswellen von Sprengungen gemäß einer Fehlerkartierung beziehen sich auf Messungen, die während der Sprengungen durchgeführt wurden. Ein Finite Elemente Modell, bestehend aus Stab- und Federelementen, wurde für die Berechnung der Spritzbetondeformation in Bezug auf die Schwingungen aus Sprengungen angewendet. Die Modellierungsmethode war ähnlich der eines Gebäudes während eines Erdbebens anhand der gemessenen Beschleunigungen vor Ort, die als Lasten benutzt wurden. Die Untersuchung hat gezeigt, dass die berechnete Haftspannung größer war als die Festigkeit in der Verbindung zwischen Gestein und Spritzbeton in der Nähe des Sprengungscentrums. Die Analyse hat gezeigt, dass die Zugfestigkeit des Gesteins versagte. Diese Arten von Versagen werden als Folge der Herausnahme von Gesteinsbrocken oder Gesteinsplatten erklärt und benötigen eine faserverstärkte Spritzbeton. Das vorausgesagte Versagen bestätigte sich beim Kartieren, welches auch zeigte, dass die Zone des versagenden Spritzbetons in Bereichen mit unverstärktem Spritzbeton viel größer war als in Bereichen mit armierten Spritzbeton.

Jan 1, 2003