Search Documents

By S. L. Miller

The development of a pilot gold geostatistical ore reserve system proved that geostatistical methods worked well for the routine production of annual ore reserves on gold mines of the Gold Fields of South Africa (GFSA) group, and that the techniques could also be practically implemented, understood and accepted by Survey Department personnel. Many side benefits of the pilot system became apparent, and a variety of useful management information was provided by manipulating the data values that were already captured. It was decided that it was a priority computing project to develop a standard production system (GORS) for routine use by all the GFSA gold mines. Experience with the pilot system enabled detailed functional specifications for GORS to be laid down. These, together with group computing policy determined the terms of reference and constraints for the GORS development. System design could not be finalized until new and appropriate mainframe database software and graphics workstation equipment and software had been found. With these in place the basic system was structured to take best ad- vantage of the interactive features of the workstation, the number-crunching power of the mainframe and the flexibility offered by a relational database and associated 4GL tools. Application sub-systems were developed for data capture, statistical applications, geostatistical calculations, contour plotting and graphical queries. GORS is being introduced to the mines in a phased manner with suitable documentation, training and support structures to enable it to be routinely and effectively used on a day-to-day basis by all group gold mines.

Jan 1, 1987

Limestone formations in the United States can be subject to relatively high horizontal stresses due to the existence of tectonic loading of the limestone strata. Underground limestone mines use the room-and-pillar method, in which 12- to 18-m-wide rooms are typically excavated. The stability of these excavations can be compromised by the horizontal stress, resulting in a rockfall hazard. Rockfalls are the cause of 15% of all reportable injuries in underground limestone mines. Horizontal stress related damage can occur in the form of guttering along one or more sides of an excavation, roof beam buckling or oval shaped roof falls, with the long axis perpendicular to the major horizontal stress. Numerical analyses show that the pillar layout and orientation of the mine workings have an effect on the horizontal stress distribution within the roof. The effects of high horizontal stresses can be mitigated by orientating the heading development direction parallel to the maximum horizontal stress, reducing the number of cross-cuts and offsetting the cross-cuts to limit the potential lateral extent of horizontal stress related roof falls. The modeling approach described in this paper can be used as a tool to evaluate potential roof failure and optimize the stability of room and pillar layouts.

Jan 1, 2008

By A. C. Lawrence, K. F. Mauer

Human factors in stope productivity -a field experiment by K. F. MAUER, M.A. (Visitor), and A. C. LAWRENCE, B.Econ., D.Com. (Member) An experiment in which three human variables were manipulated in eight stopes was conducted in a gold mine over a period of roughly six months. The three variables, which each had two levels, concerned the degree of movement from gangs, the quality of the Bantu production supervisors, and the extent to which gangs were composed of a single ethnic group (Malawians). Time was included as a variable with three levels in the analysis of the findings. On the average, stable gangs produced 12 per cent more than gangs with a high percentage of transfers, gangs with better production supervisors were more successful by nearly 9 per cent than those with poorer production supervisors, and homogeneous gangs were more productive than heterogeneous ones by as much as 15 per cent. In addition, it was found that a number of the variables exercised a joint influence on stope productivity and that the effects of the variables were accentuated by the len gth of time they had been in operation. V

Jan 10, 1973

The Third International Conference on Coal Research was held in Sydney, Australia, in October 1976. The papers and proceedings of the Conference will be published in Australia on behalf of the International Committee for Coal Research in April 1977. The papers deal with the economics and practicability of coal conversion, coal winning, resources assessment, safety and dust, and coal and power generation, together with an appreciation of coal potential by the deputy chairman of the U.K. National Coal Board. Copies of the report are available to organizations within member countries of ICCR at a cost of 35 dollars (Australian), including postage, by application to the Executive Officer, Third ICCR, Box 3842 GPO Sydney, Australia 2001. Drafts should be in Australian currency payable to Third International Conference on Coal Research.

Jan 6, 1977

By N. V. Nemchinova, A. A. Kozlov, A. V. Epiforov

The gold dissolution in sulfuric acid media during industrial oxidative leaching test of sulfide gold-copper flotation concentrates has been achieved. The reason for this was using technological water containing thiocyanates and cyanides, which can dissolve gold under these conditions. The carbon in column (CIC) process for gold recovery from these solutions was proposed. However, significant amounts of copper and iron were adsorbed onto the carbon during CIC technology industrial tests. This resulted in a decrease of the gold content in the loaded carbon up to 0.5 kg/t. Further development of the technology was conducted by optimisation of gold and impurities stripping and implementation of carbon reactivation. It was shown, that the copper extraction from the loaded carbon during cyanide treatment was about 95%. The copper content in the stripped carbon after cyanide treatment was 1.76 kg/t. The gold recovery during high-pressure elution by caustic solution was 98%. The hydrochloric acidic treatment with thermal pre-treatment (reactivation) for removing iron and calcium from gold-free carbon was proposed. In this case, the iron and calcium extractions from carbon were 40-45 and 50-55% respectively. These tests showed that for carbon recycling the sequence operations of ‘cyanide treatment, gold elution, thermal pre-treatment, hydrochloric acidic treatment’ can be used. Keywords: Thiocyanate leaching, recovery of gold, carbon adsorption, gold elution, copper stripping, thermal reactivation of carbon, activated carbon, carbon-in-column

Jan 1, 2020

By M. Holuzko, Y. R. Zhang, J. Alexander

The use of dual-energy X-ray transmission (DE-XRT) technology in the mining industry has been developing rapidly in the past decade. In many projects, DE-XRT images are analysed to classify ore and waste in sulphide deposits where the sulphides and non-sulphides have distinct characteristics in density. In the current practice of DE-XRT image processing, every pixel in the image gets classified into two categories, depending on the intensity of the pixel from both low and high energy X-ray response. If the pixel’s intensity is above the threshold curve generated in the high-energy and lowenergy scatter plot, it is classified as “higher density” material, and the remaining pixels are classified as “lower density” material. This paper elaborates on an alternative approach to DE-XRT image processing for in-depth characterisation of samples from a lead-zinc sulphide deposit. The detailed characterisation is achieved by providing density distribution of individual rock using DE-XRT laboratory sorting unit (COMEX) located at the University of British Columbia. Instead of classifying the X-ray images into two different classes from one threshold curve, multiple density classes are created between two threshold curves to generate the density distribution. By manipulating the two threshold curves, we can analyse images of samples obtained at different resolutions of density distribution. If the two threshold curves become infinitely close to each other, it will create a single-threshold scenario similar to the current methods being used in the industry. This method provides the ability to change the threshold curves, hence providing more flexibility on material characterisation based on the needs of the operation. Furthermore, the DE-XRT images from individual rock specimens are compared to the test results from hand-held X-ray fluorescence (XRF) analyser as well as assays of various elements for the same set of samples. The data analysis will provide information regarding ore characteristics and also the theoretical performance of the sensor-based sorting. Keywords: Dual-energy X-ray Transmission (DE-XRT), X-ray fluorescence (XRF), ore characterisation, density distribution

Jan 1, 2020

By H. B. Prinsloo

Change management and training initiatives in remote rural settings in Africa are generally difficult to implement successfully due to factors such as varying levels of education, multiple nationalities and languages as well as cultures in one workplace. The challenge has always been the ability to implement change management and training initiatives that will have an impact despite these differences. Essentially this requires that the change and training interventions employed are applicable and should work well with a wide range of individuals sitting in one room ? in practice this can vary from semi-literate workers to engineers with PhDs. In this paper we will share the theory behind behaviour-based change management and training and present a case study that reviews an actual supply chain improvement and sustainability implementation at a Zambian copper mine. The case study explains the results achieved as well as the interventions employed to achieve these results in a multidimensional organizational environment. This paper is relevant to delegates who are faced with implementing changes or training in a similar mining environment. Keywords change management, behaviour-based training, learning style, P2P process.

Oct 1, 2013

By L. Thomas, A. Argyn, B. Mbao, G. Longo Banza

Since the first application of solvent extraction as part of the hydrometallurgical processing of copper, several studies have been carried out to optimize extractant formulations. In 2006, Solvay developed the ACORGA® OPT series of solvent-extraction reagents to optimize copper transfer by use of a blended formulation containing both aldoxime and ketoxime as well as selected modifiers. The incorporation of selected modifiers in these blended reagents resulted in increased copper transfer, due to the interaction between the modifier and oximes within the blend. By changing the ketoxime concentration and ratio of modifier to aldoxime, the strength of the formulation was optimized to enhance copper transfer and improve Cu:Fe selectivity. This formulation is well known in the African region under the ACORGA® OPT5540 name and provides the best performance at the conditions of agitated leach plants with pregnant leach solutions that fluctuate in Cu grade and pH. This paper discusses advantages of using ACORGA® OPT5540 in the Copperbelt

Jan 1, 2023

By N. Naude, R. Foisy, F. Bornman

Spiral separators have been widely accepted as one of the most flexible gravity separation devices for several decades. The International Journal of Mineral Processing, 84, pp. 118 – 132 mentioned that spirals are for treating material too coarse for flotation and too fine for dense-media separation. Powder Technology V 102, pp 244 – 252, 1999 stated that there exists a genuine need for extending the performance envelope of spirals – whether to treat finer or coarser material than the traditional size ranges. In recent times there has been an upsurge in interest, particularly in the development of newer fine gravity separators. Spiral separators for the recovery of ultra-fine particles have a unique profile, pitch and features to ensure efficient performance. The flow on the spiral trough must be controlled to minimise turbulence that will entrain fine particles in the outer section of the trough. The experimental test work showed a movement of mass from the outer region towards the centre column of the spiral, i.e., from the fine tailings band towards the concentrate. As recovery on the spiral trough is a function of mass yield and grade, the ultra-fine 7 spiral had a better recovery than the HX5. This makes the UF7 an ideal rougher spiral. Keywords: Ultra-fine particles, spiral, design, recovery

Jan 1, 2020

By N. A. Smith, R. J. Fowell, J. L. Hislam

Abstract: Data are presented from two sites in southeast England, where problems were encountered in tunnelling through ground containing flint. In response to the difficulties, substantial laboratory testing programmes were initiated to determine the strength of the flints.It is shown that the strength varies very considerably, even within a single flint particle and that the practice of estimating unconfined compressive strength by a single multiplier applied to the point load strength index (Is(50)) may give misleading results. The preparation of UCS specimens for testing was found to be very difficult and it is recommended that tunnel machine capacity is assessed relative to Is(50). Résumé: Des données sont presentées sur deux sites dans le sud-ouest de l’Angleterre,où le perçage d’un tunnel dans un sol contenant du silex a posé des problémes. En consequences de ces difficultés, des programmes substatiels de recherché en laboratoire ont été initiés afin de déterminer la resistance des silex. Il est demontré que la resistance varie considérablement, même au sein d’une particule de silex, et que la pratique de estimation de la résistance en compression non confinée, (UCS) par le biais d’un simple coefficient appliqué au ‘point load strength index (Is50)’ pourrait donner des resultants trompeurs. La préparation de specimens UCS destinés aux tests s’est avérée trés difficile et il est recommandé que la capacité de la machine de perçage de tunnels soit calculée relativement au Is50. Zusammenfassung: Daten von zwei Standorten in Südosten von England, wo Probleme beim Tunnelbau durch feuersteinhaltigen Grund antraffen, sind angegeben. Wegen diesen Schwierigkeiten wurden Laboratoriumsforschungsprogramme eingeleitet, um die Festigkeit von Feuersteinen zu bestimmen. Es wurde gefunden, dass die Festigkeit sehr unterschiedlich war, selbst bei einzelnen Feuersteinstücken, und dass die Praxis, die unbegrenzte Kompressionsfestigkeit (uKf) auf Grund eines einzigen Multiplikationsfaktors vom Punktladefestigkeitsindex (Is50) abzuschätzen, zu irreführenden Resultaten führt. Die Vorbereitung der uKf Prüfstücke war sehr schwierig und es wird vorgeschlagen, dass die Kapazität der Tunnelbaumaschine in Abhang der Is50 bestimmt wird.

Jan 1, 2003

By I. Kaabachi, F. Meunier, N. Morales

In open pit mining, ore and waste are hauled outside of the excavation area by trucks that move along a system of ramps. The design of these ramps must be carefully addressed because they have to comply with geomechanical constraints to ensure the stability of the pit walls, provide access to the different levels and phases, but also maximise the value of the extracted ore and reduce the extraction of waste. Because an optimisation approach able to deal with the design of the full ramp system seems to be out of reach at the moment, this paper addresses the problem of designing one ramp providing access to a single pushback, which has been determined beforehand. The optimisation objective is therefore to find a ramp that gives access to one given potential volume, while minimising its impact on the economic value of the volume. Two versions of the problem are formalised. One version allows the extraction of ore and waste only if this extraction is necessary for the ramp system. This version somehow minimises the intrinsic value of the ramp system. In the second version, it is possible to extract more than is needed by the ramp system. For instance, this takes into account the possibility of attaining ore on the wall opposite to the ramp as soon as the ramp reaches its level. In the setting mentioned above, the contribution of this work is three-fold. First, the computational complexity of the two different versions of the problem is presented and discussed; in particular, they are shown to be NP-hard. Second, compact integer programs modelling these two versions are proposed. Third, an efficient GRASP algorithm able to cope with the large instances of the problem is proposed. To assess the proposed approaches, the models and algorithms are applied to real instances with an off-the-shelf solver, illustrating and discussing their potential and relevance for the two versions of the problem. They are also compared with other approaches from the literature in terms of value and resulting designs.

Sep 1, 2021

By N. Sacks, N. B. S. Magagula, I. Botef

"Low-pressure cold gas dynamic spraying was used to deposit WC-4wt%Ni and WC-4wt%Ni-1wt%Mo coatings onto mild steel. Dense coatings with very low porosities were produced. No decarburization occurred during deposition and no deleterious phases were formed. The coatings were subjected to standardized material characterization tests, as well as slurry abrasion testing to assess their wear behaviour. The wear tests were conducted in synthetic minewater-silica slurries, while distilled watersilica slurries were used as a control. The hardness of the coatings, 512HV0.3 and 458HV0.3 for WC-4wt%Ni and WC-4wt%Ni-1wt%Mo respectively, are comparable to those achieved using high-temperature coating processes. The abrasion wear rates for both coatings were less than 5 mg/min and 10 mg/min in the distilled water-silica and synthetic mine water-silica slurries respectively. The approximately 50% increase in wear rate in the synthetic minewater slurry is attributed to a synergistic corrosive wear mechanism. The predominant wear mechanisms were identified as binder smearing and delamination, with carbide grain fracture and pull-out. IntroductionSlurry abrasion is a common phenomenon in mining operations, particularly in pipelines transporting, for example, sand-water slurries. This type of wear can cause pipeline fracture, shortened operational lifetimes, and impede pipeline efficiency. To reduce or limit abrasion, thermally sprayed tungsten-carbide-based coatings are often used as pipe linings (Kanchan et al., 2010). This is due to their attractive mechanical properties, which include high wear resistance, stiffness, hardness, compressive strength, and tensile strength. These properties are provided by the coating microstructure and composition, which is a blend of hard, wear-resistant tungsten carbide (WC) particles embedded in a fracture-tough metallic binder phase (Brookes, 1997). Cobalt (Co) is the most commonly used binder due to its excellent wetting of the WC phase and moderate mechanical properties; however, its application is limited to non-corrosive environments as it has a low corrosion and oxidation resistance (Andren, 2001). Nickel (Ni) may also be used as a binder, and has been shown to have superior oxidation and corrosion resistance, but in some applications may not have the required mechanical properties (Kim et al., 2006)."

Jan 1, 2016

By P. H. S. W. Kulatilake

The paper introduces a computer simulation technique to estimate the target detection probabilities associated with search surveys. The technique takes into account the inherent randomness associated with the distributional properties of geologic targets. Use of the technique is illustrated through examples. The paper provides information as to how this technique can be used in obtaining the optimum sampling pattern and optimum spacing associated with target detection surveys.

Jan 1, 1987

By F. Nakhaei, A. Noury, S. Ghodrati

To achieve maximum efficiency in any purification stage, the flotation should be continued until the concentrate grade reaches the feed grade. During sampling from rougher cells of the Iranian Sarcheshmeh copper concentrator plant 1, it was revealed that the concentrate grade of the last five cells of rougher circuit was close to feed grade. Therefore, it was suggested that the concentrate of the aforementioned cells be mixed with rougher feed. In this study, one of eight rougher circuit rows was selected and evaluated. The floatability tests were performed to compare the flotation behaviour of rougher feed and mixture of concentrate of the last five cells with rougher feed in the laboratory scale by a tree analysis process. The results showed that mixing of rougher last five cell concentrate with feed has a detrimental effect on flotation efficiency that leads to a 3% decrease in recovery. It was also observed that with grinding of this concentrate, recovery can be improved. Keywords: Efficiency, flotation, rougher, tree analysis, floatability, concentrate, mixing

Jan 1, 2020

By Y. Cao, C. Li, A. Song

Bubble size plays a key role in determining flotation efficiency. Bubbles can be formed by passing air through pores. Bubble detachment from a pore is driven by lifting forces including buoyancy force and momentum force. Enhancing the momentum force is the key to accelerate bubble detachment and to minimise bubble size. Recent studies show that replacing steady air with oscillatory air supply could significantly decrease bubble size by enhancing the momentum force. To date, the underlying mechanism for the improved momentum force with oscillatory air supply is not yet clear. This work, for the first time, developed a qualitative model for the momentum force as a function of frequency, on/off time ratio and gas flow rate. It was found that the momentum force was positively correlated with the frequency as well as the air flow rate, and was negatively related to the on/off time ratio. The relation between bubble size and these operating parameters was also investigated. Keywords: Flotation, bubble size, momentum force, modelling, oscillatory air supply

Jan 1, 2020

By X. Zhang, E. Li, Y. Xiao, Z. Yu, H. Han, J. Xie, J. Tian, W. Sun, K. Hong

In a pulp environment, the surface properties of magnesite and dolomite tend to be similar, due to the re-adsorption of dissolved calcium species, which makes the flotation separation difficult. In this paper, the chelating reagent EDTA is introduced to eliminate the adverse influence of the calcium species and to restore the selectivity of magnesite-dolomite separation using sodium hexametaphosphate (SHMP) as a depressant. Flotation experiments confirm that the recovery of magnesite improves significantly in the presence of EDTA. Zeta potential experiments confirm that the negatively charged EDTA4+ and HEDTA3+ species can form soluble and stable chelates with positively charged Ca2+ and Ca(OH)+ species preventing their adsorption on the magnesite surface. Adsorption measurements prove the addition of EDTA can decrease the adsorption of depressant SHMP on the magnesite surface. X-ray photoelectron spectroscopy (XPS) measurements further confirm the transformation from the surface of magnesite to dolomite in the presence of calcium ions, and the possible adsorption mechanism of EDTA and SHMP on the magnesite and dolomite surface. Key words: Magnesite; Dolomite; Surface dissolution; Flotation separation

Jan 1, 2020

By S. Liaghat, J. Rosenkranz, P. Semsari Parapari, S. Chehreh Chelgani, A. Tohry

It is commonly accepted that the energy consumption for comminution within mineral processing is responsible for around 3% of the global electrical energy usage. However, it was clearly noted that inside mills, less than 1% of this energy efficiency is actually consumed for particle size reduction. Therefore, monitoring of grinding parameters and modelling of product particle size distribution (e.g. characterised by the 80% passing size P80) play an essential role in operating costs of a mineral processing plant. Several empirical models have been introduced for the prediction of the P80. Since in the industrial scale usually a few numbers of grinding variables are monitored, these models cannot identically be used in plants. In addition, these empirical models do not always indicate the magnitude of correlations between milling variables. This study proposes to introduce the Hilbert-Schmidt independence criterion (HSIC) as an intelligent model for exploring linear and nonlinear relationships between grinding variables and P80 for an industrial scale data assessment. HSIC can rank variables based on their importance and help to select the most effective one for the generation of predictive models. HSIC modelling through various monitored grinding variables (ball charge, feed input rate, F80, power draw and work index) of an industrial plant indicated that F80 as a feed property has the highest effect on P80 of the ball mill products. Modelling results highlighted that the P80 can be accurately predicted, based on effective variables by using a HSIC model. These outcomes showed that HSIC as a powerful modelling tool can assess the relationships between monitored grinding parameters, select the most effective grinding parameters and satisfactorily predict the P80. Keywords: Product particle size, variable importance measurement, Hilbert-Schmidt independence criterion, mill charge

Jan 1, 2020

By F. Pinto, J. V. Lemos, A. Sousa, L. Ribeiro e Sousa

The Rossio railway tunnel was built in 1890 crossing several formations involving limestones, basalts and also sandy and clayey formations. Due to the fact that it is an old underground structure rehabilitation and repair works were performed, namely at Km 0,900 and in a zone crossed by a new tunnel from the Lisbon Metro. Reinforcement support systems were designed in the Rossio tunnel in order to prevent its stability. In this paper, repair works and anchor tests performed at km 0,900 are presented, as well as the monitoring system implemented in order to observe the structural effects induced by the construction of the works. For the interpretation of the obtained information complex 3D models was built, permitting the simulation of the sequential excavation scheme used, non-linear behaviour of the different formations, and the support systems used. Der 1890 erbaute Rossio Eisenbahntunnel durchoertert mehrere Formationen, einschliesslich einer Kalkstein-, Basalt- sowie einer sandigen und tonigen Formation. Auf Grund des Alters des unterirdischen Bauwerks wurden Instandsetzungs- und Reparaturarbeiten im Bereich km 0,900 sowie im Kreuzungsbereich mit einem neuen Tunnel der Lissabonner U-Bahn durchgeführt. Aussteifungssysteme wurden entworfen, um die Stabilität des Rossio Tunnels zu gewährleisten. Im Folgenden werden die Instandsetzungsarbeiten und Anker Tests im Bereich km 0,900 sowie das Messystem zur Ueberwachung der strukturellen Auswirkungen der Bauarbeiten dargestellt. Zur Interpretation der gewonnenen Informationen wurden komplexe 3D Modelle entwickelt, die eine Simulation des Bauablaufs und die Anwendung nichtlinearer Stoffgesetze fuer die verschiedenen Formationen und Aussteifungssysteme ermöglichten. Le Tunnel ferroviaire du Rossio a été construit en 1890, traversant des différents terrains comme des calcaires, des basaltes et aussi des formations limoneuses et sableuses. Dû à l’ancienneté de l’ouvrage, des travaux de réhabilitation et réparation ont été faits, nomment au km 0,900 et dans la zone traversée par le nouveau tunnel du Metro de Lisbonne. Des systèmes de support renforcé ont été conçus pour le Tunnel du Rossio de façon à rassurer sa stabilité. Dans ce papier, on présente les travaux de réparation et les essais d’ancrage réalisés au km 0,900, et aussi, le système d’auscultation mise au point pour l’observation des effets structuraux induits par les travaux. De façon à interpréter l’information résultant de l’observation, des modèles 3D complexes ont été utilisés, permettant la simulation de la méthode séquentielle de l’excavation, du comportement non - linéaire du terrain et, aussi les systèmes de support utilisés.

Jan 1, 2003

By D. Yu Pleev, V. G. Krivolapov

Mines of Southern Kuzbass working out, basically, coal formations of flat seams. Seams, as a rule, are inclined to self-ignition. Detection at early stages of the centers of endogenous underground fires has great value for safe conducting mountain works. One of methods of detection of an early stage of underground fires in the worked out space is the method of superficial radon survey. In the report the method is de-scribed and examples of superficial radon survey on concrete layers are given.

Jan 1, 2003

By P. L. Moolman

An approach to the design of a tailings disposal system is presented using an example from a platinum project on the eastern limb of the Bushveld Complex as a base case. The design is driven by two inputs: namely, maximizing water recovery and minimizing power cost, expressed as cubic metres and kilowatts per ton of solids deposited on the tailings storage facility respectively. The approach considers low-, medium-, and high-density platinum tailings and uses material-specific aspects such as thickening and rheology to determine the most economical option. An analysis based on direct capital and operating cost (water and electricity) shows that the medium-density scenario results in the lowest total cost per ton of tailings deposited, even though this system results in the highest electricity consumption per ton of tailings deposited. As the cost of water and electricity is likely to increase in the future, the higher-density tailings disposal options become more economical, with the paste option the preferred option.

Jan 1, 2012