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By N. Lock

"Despite the pre-eminence of the Jwaneng Diamond Mine as the world’s richest diamond mine, the discovery story has long been clouded in mystery. This is the 45-year old untold story of the Jwaneng discovery and contemporaneous Bechuanaland/Botswana political and socioeconomic history. Diamond exploration by De Beers in Bechuanaland began in 1955, with the first true kimberlite discovery near Letlhakane in 1967, before Clifford’s Rule was applied and before the use of indicator mineral chemistry. Surface deflation soil sampling and bioturbation by termites was the foundation for exploration into the Kalahari. The 1962 reconnaissance programme south of Jwaneng had failed to make any discoveries. Improved sampling methods were applied to the Kalaharicovered areas in 1969 and positive results were received by year-end. The Whateley’s Wish percussion drill-hole in December 1972 was confirmed as Jwaneng 2424D/K2 with drill core in early 1973. Jumper drills were required to penetrate the Kalahari sand cover. Diamond resources were demonstrated despite multiple technical problems. IntroductionThe Jwaneng Diamond Mine is, by value, the world’s richest diamond mine. Harry Oppenheimer is quoted as saying that Jwaneng is ‘the most important primary deposit found anywhere in the world since the discovery at Kimberley more than a century ago.’ (Taylor III, 1982) The mine opened in 1982 after some nine years of evaluation and construction since discovery in February 1973. Debswana (2017) states that 2015 production was 7.87 Mt of ore from which 10.408 million carats were recovered at a grade of 132 carats per 100 t (cpht). Although the value is not reported, it was noted that Jwaneng contributes 60–70% of Debswana’s total revenue from all mines, including Orapa, Damtshaa, and Letlhakane (Debswana, 2017)."

Feb 1, 2019

By R. Degel

Keywords: Pyrometallurgy, DC furnaces, electric smelter, FeCr, FeNi, FeMn, Si metal, ferro-alloys, platinum production, circular furnace, energy recovery system In 1906, the first submerged-arc furnace was supplied by SMS Siemag. Since then, the division has become established in various industries such as ferro-alloys and non-ferrous metals, and in numerous other special applications. During the evolution of this technology, more efficient units with longer lifetimes were developed. Today, especially the potential of DC-based smelters, raises worldwide attention, with some projects having already started to implement this kind of technology. This paper evaluates SMS Siemag?s general viewpoint regarding the potential application of DC smelter technology and possible options for the ferro-alloy and non-ferrous industry. SMS Siemag is currently executing a FeCr project in Kazakhstan, where four of the world?s largest closed-type DC smelting furnaces, with a power input of 72 MW, will be installed. These furnaces include the latest technological features of modern DC smelters, which are described in this paper. SMS Siemag has started a long-term research and development project allowing a direct comparison of AC versus DC technology on a large scale, using a recently installed 1 MVA test furnace at the IME at the University of Aachen, in Germany. For open-type ferro-alloy and Si-metal furnaces, SMS Siemag has developed an energy recovery system, which is presented in this paper.

Jan 1, 2011

By B. D. H. Knights

In November 2009 Mintek installed the FloatStar? advanced flotation stabilization system on Vale's Cauê iron ore beneficiation plant in Brazil. In September 2010 the system was upgraded to include flotation optimization. The circuit consisted of two parallel cleaner circuits producing final concentrate. The tailings from the cleaner section passed through a scavenger circuit. Large, well-instrumented feed sumps played an important role in circuit stability, presenting a good opportunity for advanced control. Previously the plant was controlled using distributed control system (DCS) level control only. The flotation circuit processes roughly 30kt/day. The FloatStar system provided advanced control of the flotation circuit as well as of the sumps feeding the circuit. The system underwent a lengthy trial to assess the benefit that it provided. Two data sets were analysed, showing performance under advanced stabilization and optimization respectively. Several validation and consistency criteria were employed to ensure the quality of the analysis. Iron recovery and iron tailings grade were used to measure system performance. The analysis showed that the system increased recovery by up to 2.7%. In addition, the system decreased the iron tailings grade by between 1.2% (from 23.5% to 22.3%) and 4.3% (from 31.3% to 27.0%) during different test campaigns. The analysis also showed that the entire FloatStar stabilization system was active for 72.7% of the time from first activation to the end of the first data set (approximately 200 days). From the analysis it was concluded that under similar conditions for 'ON' and 'OFF' tests, the system provides a clear benefit. It was also found that over the longer term, the system continues to provide a benefit. This finding suggests that the results were not simply due to a short-term advantage. The size of the data set, as well as the magnitude of the recovery improvements, lends considerable confidence to these results. Therefore, it can be concluded that the FloatStar control system provides substantial benefit to operations at this site.

Jan 1, 2012

By P. Share

As part of JAGUARS (JApanese-German Underground Acoustic emission Research in South Africa), high-resolution tiltmeters were installed during 2007 at Mponeng gold mine, South Africa, in an attempt to study and understand the risks posed by in-mine seismic events and to subsequently use the knowledge gained to mitigate these risks. In December 2007, an M2.2 event occurred at Mponeng and was detected by the tiltmeters installed. The tilt expected for the M2.2 event is modelled through the use of numerical and analytical tools and utilizing, as input parameters, characteristics of the event such as the rupture area, the amount of slip, elastic properties of the rock, the state of stress before the event occurred, and frictional parameters of the rupture. The calculated tilt values are correlated and compared with the recorded data, and are found to be of the same order. Certain input parameters, such as the initial rupture point, are further constrained by varying them, during modelling, until the calculated and observed tilt values are approximately equal. From modelling, it can be concluded that the rupture point had to be closer to the location of the tiltmeters. In addition, possible locations acting as source areas for the observed aftertilt are determined. Further modelling still needs to be done to quantify the effects of the tunnel close to the tiltmeters and plastic deformation of the rock mass. Keywords high-resolution tilt data, Mponeng gold mine, M 2.2 seismic event, analytical modeling, numerical modeling, rupture plane.

Oct 1, 2013

By R. Weber

Methane explosions in underground coal mines are a major concern across the mining industry. After the Pike River disaster, Arnot Coal became even more aware of the explosion risk. To determine whether Arnot has adequate precautions against a methane explosion, such as the one that led to the Pike River disaster, a literature survey covering the causes of the incident and what preventative measures should have been in place was conducted. Many different methane explosion prevention methods were evaluated, as well as codes of practice. Based on the findings, Arnot?s measures to prevent conditions favourable for a methane explosion were evaluated.

Jan 1, 2014

By K. R. Koch

Although some of the platinum(II/IV) and rhodium(III) chemistry is considered ?old? and well-known, the application of modern multinuclear NMR spectroscopic methods to this chemistry in solution reveals new details about their rich and relevant solution chemistry. In this paper we will briefly illustrate that the highly-sensitive 195Pt NMR shielding is an excellent probe to explore aspects such as solvation, ion-pairing, and the hydrolysis chemistry of inter alia [PtCl6-n(H2O)n]n-2 (n=0-5). Moreover the novel use of 35Cl/37Cl and 18O isotopes effects as unique NMR ?fingerprints? leading to a new and unambiguous method of chemical speciation of the numerous possible PtII/IV and RhIII complexes present in halide-rich aqueous solutions. In the case of Rh(III) chemistry a new, direct speciation distribution diagram has been established for [RhCln(H2O)6-n]3-n complexes (n = 3-6) in HCl solution at 292 K with these methods.

Jan 1, 2012

By J. H. Zietsman, S. Maharajh, J. Muller

In the chlorination process for TiO2 pigment production, blends of titania feedstocks such as ilmenite, synthetic rutile (SR), natural rutile, upgraded slag, and chloride-grade slag are reacted with coke and chlorine at a temperature of around 1000°C to form TiCl4 (the main product) and other waste metal chlorides. The TiCl4 is the main feed material for the TiO2 pigment-making process. Feeding different titania materials to the chlorinator affects the amount of coke and chlorine required for the process, the amount of waste generated, waste disposal costs, the amount of TiCl4 produced, and bed build-up rates. These factors influence the value of the feedstock. Generally, a higher TiO2 feedstock is more valued since less waste is generated and less reagents are consumed. To quantify the impact of different feedstocks on the chlorinator, a techno-economic model was developed to describe the chlorination process and estimate process variables at steady state. This paper describes the development of the model and studies in which the model has been used to quantify effects of using different feedstocks.

Jan 1, 2015

By Merete Tangstad, Kai Tang

The primary aim of the present investigation is to develop a model which permits to calculate/predict the viscosities of ferromanganese slags, typically focus on the MnO-SiO2-Al2O3-CaO-MgO-FeO multicomponent system. The present viscosity model emphasizes the ability of prediction, i.e. using the binary parameters to extrapolate the viscosities in ternary and higher order systems. To this end, a physical sound model is essential. Temperature dependence of viscosity is described by the Eyring?s formalism. The well-known cell model is used to define the SiO44- tetrahedra in the silicate melts. Composition dependence is expressed in term of viscous activation energy, which is characterized by the binary structural units. The viscosities in ternary and higher order systems are hence predicted using the binary activation parameters. The model has been used to calculate the viscosities in the whole liquid composition range of ferromanganese slag.

Jan 1, 2007

By J. P. Gouvea

Back-analysis of two mining-induced tremors in 2011 was used to determine a modelling criterion for the entire Klerksdorp Goldfield (i.e., Vaal Reefs region). At that time, most mining operations in the region were owned by AngloGold Ashanti (AGA) and shared many geotechnical similarities. By 2018 AGA had sold off all its Klerksdorp operations to different mining companies, which continued applying the 2011 modelling criterion. As mining activities became more remote, scattered, and isolated, the extraction of isolated blocks of ground and remnants became increasingly necessary. However, the inherited criterion allowed only minimal or no mining activities at these areas. Keeping in mind that safety is the overriding consideration, an innovative numerical modelling approach, which includes the application of peak particle velocity designs, was developed to provide practitioners in the Klerksdorp Goldfield with a suitable criterion to justifiably and safely mine isolated blocks of ground and remnants. This would not always be possible if a conformist approach was used.

Mar 14, 2024

By C. Machio

This paper reports the results of a study to determine the effect of process control agent (PCA) on the characteristics of Ti-Mg powders during milling. It has been shown that a 2% increase in PCA content leads to up to a 40% increase in yield of the milled powder but reduces the kinetics of the mechanical alloying process. The introduction of 4% PCA decreases the mean powder particle size by up to 30%, whereas 6% PCA increases the mean particle size by up to 230%. The characteristics of the milled powders will be discussed in relation to the role of PCA in the milling process. Keywords Titanium?magnesium, mechanical alloying, PCA.

Jan 1, 2011

By P. R. Segopolo

"The purpose of the project is to convert current shuttle car utilization on an underground coal mine to best practice by focusing on change-out points and tramming routes, which have a major influence on shuttle car away times. Time studies were an integral part of the project as these enabled the determination of shuttle car away times. An indirect proportional relationship between shuttle car away times and productivity is established. Through the time studies, it is deduced that a third shuttle car will make an insignificant contribution to production when there is only one split open. During this time, maintenance on the third car can be optimized. In order to satisfy the mine’s key performance indicator of keeping shuttle car away times less than 75 seconds, a belt extension must be scheduled after the third split is open. It is established that at any given time, a minimum of two shuttle cars should be used. When cutting on the left-hand-side of the belt road with only two shuttle cars available, the centre and left (left of the feeder breaker) shuttle cars should be used for coal hauling. When cutting on the right-hand-side, the centre and the right-hand-side cars should be used. If only one shuttle car is available, the centre car is the most efficient to use. Alternative anchoring configurations can be employed so as to enable cars (left or right, especially) to reach the opposite extremities of the panel and hence minimize cable length restrictions. Paper written on project work carried out in partial fulfilment of BSc. Eng. (MiningEngineering)"

Jan 1, 2015

By F. Agterberg

In his 1978 monograph ‘Lognormal-de Wijsian Geostatistics for Ore Evaluation’, Professor Danie Krige emphasized the scale-independence of gold and uranium determinations in the Witwatersrand goldfields. It was later established in nonlinear process theory that the original model of de Wijs used by Krige was the earliest example of a multifractal generated by a multiplicative cascade process. Its end product is an assemblage of chemical element concentration values for blocks that are both lognormally distributed and spatially correlated. Variants of de Wijsian geostatistics had already been used by Professor Georges Matheron to explain Krige’s original formula for the relationship between the block variances as well as permanence of frequency distributions for element concentration in blocks of different sizes. Further extensions of this basic approach are concerned with modelling the three-parameter lognormal distribution, the ‘sampling error’, as well as the ‘nugget effect’ and ‘range’ in variogram modelling. This paper is mainly a review of recent multifractal theory, which throws new light on the original findings by Professor Krige on self-similarity of gold and uranium patterns at different scales for blocks of ore by (a) generalizing the original model of de Wijs to account for random cuts; (b) using an accelerated dispersion model to explain the appearance of a third parameter in the lognormal distribution of Witwatersrand gold determinations; and (c) considering that Krige’s sampling error is caused by shape differences between single ore sections and reef areas.

Jan 1, 2015

By K. Woodward

"SynopsisSeismically active mines generally experience an increase in seismic hazard due to rock mass instability following blasting. Re-entry protocols commonly include measures to limit the spatial and temporal exposure of personnel to increased seismic hazard induced by blasting. The management of periods of increased seismic hazard requires the development of re-entry protocols for a unique mining environment. Identifying mining conditions that may result in significant seismicity following blasting relies on retrospective analysis, which is often focused on seismicity occurring within a certain period after blasting and within a certain radius of the blast in the broader context of site-specific experience.The analysis of seismicity without considering blasting times and locations allows for the relationship between seismicity and blasting to be investigated without prior assumptions concerning dependency. To achieve independent analysis, seismicity that is clustered in space and time (referred to as a seismic sequence) must be identified by assessment utilizing only seismic parameters. An automated algorithm is implemented that assesses the timing, location, and quantity of seismicity to identify seismic sequences, represented by the time of the first event and mean location of all events in the sequence.The relationship between sequences and blasts is assessed by calculating the distance and time from each sequence to the closest blast in space and time. Establishing an independent classification between sequences and blasting provides insight into the unique cases where seismic sequences are remote and/or delayed with respect to blasts and identifies cases when sequences exhibit a weak relation to blasting. The nature of seismic responses to blasting has direct implications for the management of the increased seismic hazard associated with seismic sequences.The approach presented in this study contributes to the management of seismic hazard by providing empirical support for the relationship between seismic sequences and blasting. These relationships indicate the portions of sequences that can and cannot be practically managed using tactical approaches. Furthermore, the analysis of sequences reveals the nature and evolution of rock mass responses to blasting. These results have implications for the extent of spatial or temporal re-entry restrictions required for the optimal management of time-dependent rock mass response to mining."

Jan 1, 2015

By N. Andersen

During the preliminary design phases and feasibility study of a proposed vertical shaft, a vertical diamond drill-hole is normally drilled on the site. This paper outlines how rock mass characteristics, in-situ rock stress, rock strength, hydrological characteristics, and structural parameters can be determined using wireline logging of this borehole. In addition, a rock mass classification scheme is developed, based on published work, and in particular the Q-factor is adapted to assess the stability of raise-bored shafts. The ‘stick plot’ is introduced, which combines all geotechnical parameters applicable to the stability of a vertical shaft into a colourcoded format where cross-correlations can readily be made on a day-today basis during the shaft-sinking process.

Jan 1, 2015

By W. Newcomen, G. Dick

"Effective management and mitigation of pit slope instability in open pit mines begins with a comprehensive slope monitoring programme. The ability to differentiate between non-critical pit wall movements due to rebound or relaxation of the excavated slopes and movements that may be indicative of slope failure is important for maintaining a safe working environment and maximizing production. Slope failure prediction methods using velocity, acceleration, and strain criteria have been introduced and put into practice over the past few decades. Forty-eight slope failures with surface monitoring data are presented and assessed using the strain-based failure prediction approach, with consideration of the quality of the rock mass and the potential failure mechanism. The results indicate that the strain-based approach can be used to provide general guidance regarding strain thresholds for pit walls for a variety of failure modes in diverse geological environments. The advantages and potential drawbacks of the strain-based and other slope failure prediction methods are discussed. The importance of implementing a pit slope monitoring and performance evaluation system early in mine development is also emphasized. IntroductionThe successful prediction of the Manefay Slide pit slope failure at Bingham Canyon at 9:30 am on 10 April 2013 (Engineering and Mining Journal, 2014) highlighted the importance of having a comprehensive slope monitoring system that provides an accurate prediction of the time of failure of an open pit slope. Using most of the geotechnical monitoring tools available, the time of the failure was predicted within hours and equipment and personnel were evacuated from the pit well in advance of the failure. From a time to slope failure perspective, the monitoring system in place was a success.There are two general groups interested in monitoring pit walls, with slightly different objectives in mind when the monitoring system is being set up. There are those at the mine site that have to implement the pit slope design, monitoring protocols, and the action response plans, and there are those designing the slopes (often consultants) who regularly visit the mine but may not be responsible for the day-to-day activities. was a success.There are two general groups interested in monitoring pit walls, with slightly different objectives in mind when the monitoring system is being set up. There are those at the mine site that have to implement the pit slope design, monitoring protocols, and the action response plans, and there are those designing the slopes (often consultants) who regularly visit the mine but may not be responsible for the day-to-day activities."

Jan 1, 2016

By W. Valderrama, D. G. Almond

Operation of large SAG mills requires a change in the conceptual approach to grinding processes. The traditional energy consumption criteria are now enhanced with new criteria derived from the mechanical dynamics of the mill load. This new approach demands instrumentation capable of providing accurate information about the load movement and the ratio of balls and ore inside the mill. This paper discusses two new performance enhancing tools available to meet these needs.

Jan 1, 2004

By E. Pardo-Igúzquiza, R. A. Olea

The bootstrap is a computer-intensive resampling method for estimating the uncertainty of complex statistical models. We expand on an application of the bootstrap for inferring semivariogram parameters and their uncertainty. The model fitted to the median of the bootstrap distribution of the experimental semivariogram is proposed as an estimator of the semivariogram. The proposed application is not restricted to normal data and the estimator is resistant to outliers. Improvements are more significant for data-sets with less than 100 observations, which are those for which semivariogram model inference is the most difficult. The application is illustrated by using it to characterize a synthetic random field for which the true semivariogram type and parameters are known.

Jan 1, 2015

By V. I. Zhuchkov, L. A. Smirnov, E. I. Arzamastsev, A. A. Babenko

A brief analysis is given for state-of-the-art of manganese and chromium ferroalloy production in Russia and their consumption by metallurgy plants. The main causes of low output of manganese and chromium ferroalloys, and ways to resolve the issue of ferroalloy production development are considered.

Jan 1, 2004

By T. Ertekin, X. Dong

This paper identifies the need for the development of specialized inverse solution techniques for the analysis of pressure transient data for the characterization of the transport and sorption properties of coal seams. Central to the proposed inverse solution technique is a specially structured artificial neural network (ANN). The most important transport and sorption characteristics of coal seams are butt and face cleat permeabilities, macropore porosity, Langmuir volume constant, Langmuir pressure constant, and sorption time constant. Conventional methods, such as type curve matching techniques and laboratory-derived measurements are handicapped in terms of being representative over the entire domain of interest. In this paper, we utilize analytical forward solution techniques for various combinations of characteristics of coal seams to generate training and testing patterns. These training patterns are shown to an ANN structured to learn the ubiquitous non-linear relationships that exist between coal seam properties, input conditions and the pressure transients measured. The trained networks are then extensively tested to ensure that they have effectively learned the training patterns. In the final stage of the development, the networks are run in the prediction mode. The responses of the networks are found to be in agreement with the input data. The developed networks are able to generate results generally within 5% error margin for permeability and porosity and 20% error margin for the sorption characteristics of coal seams. A number of examples highlighting the capabilities and degree of effectiveness of the network in characterizing the coal seams areincluded. Keywords: artificial neural networks (ANNs); coal seam characteristics; pressure transient analysis

Jan 1, 2003

By R. Kuyvenhoven, A. Parbhakar-Fox, X. Prieto, J. Quevedo, L. V. Danyushevsky

This paper presents the results of a study focussed on determining the distribution of cobalt in different types of pyrite of the La Estrella IOCG deposit in Chile. In the IOCG mineral deposits, where copper is the main product, the quantification and distribution of cobalt is required to correctly define the technical and economic viability of recovering cobalt as a by-product. In the La Estrella mineral deposit, seven alteration and mineralisation events were recognised through both optical and automated electronic mineralogical analysis. Of these seven events, five different types of pyrites were identified, each with unique characteristics of the pyrite crystals. Through advanced elemental analysis of these five types of pyrites, it was determined that the concentration and distribution of cobalt within the pyrite crystal is dependent on the mineralisation event. The results indicate high cobalt concentrations in the early pyrite mineralisation events, associated with relatively fine pyrite grains, and cobalt generally occurring in a solid form in the pyrite core. The late pyrite mineralisation event exhibits the lowest concentrations of cobalt, with cobalt predominantly present along the outer periphery of the pyrite. These results are relevant from a metallurgical point of view because the preferential location of cobalt within the pyrite crystal will influence the maximum metallurgical recovery of cobalt. For this, a cobaltiferous pyrite concentrate must be formed which, according to the characteristics of pyrite, must be processed with the optimal solubilisation method. The overall objective is to ensure both good cobalt recovery and a high concentration of cobalt in the leach solution resulting from pyrite leaching. Keywords: Cobalt, pyrite, IOCG, copper, metallurgical recovery, solubilisation, Chile

Jan 1, 2020