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By N. R. Shoko, J. Chirasha

Refractory design remains the most fundamental factor in furnace construction. Refractory design details and proven technology consideration is of paramount importance to come up with an optimum furnace life and to maintain productivity in the life span of the furnace lining. The failure to produce a technically or operationally durable refractory design lining could give rise to pre-mature deterioration of the refractory lining and furnace shell. The premature failure of the furnace lining will lead to extensive heat losses, furnace bath shift, change in taphole orientation and alteration of the Pitch Circle Diameter. A combination of these were experienced at Zimbabwe Alloys? new high carbon ferrochrome furnace. The Zimbabwe Alloys experience has shown an excellent furnace performance in the first two years of operation although signs of an anomaly showed within the first six months of the new furnace. Production slowed down due to induced problems from refractory failure causing furnace distortions impacting on the availability of the furnace and smelting capacity. This paper presents the lessons learnt, measures taken to deal with the premature failure and constraints within which the situation was managed.

Jan 1, 2007

By F. Lanaro, K. Röshoff, R. Christiansson, L. Jing

This paper presents the results of a project for developing a methodology for empirically determining some of the mechanical properties of the rock mass at the Äspö Hard Rock Laboratory, Southern Sweden. Using the equations available in the literature, the deformation modulus, friction angle, cohesion and unconfined compressive strength of the rock mass were estimated. A comparison of the results using different classification methods (Q, RMR, GSI, RMi, Ramamurthy’s) was made to estimate the range of variations in the mechanical properties with the considerations of: i) the quality/quantity of the geological data; ii) the technique for partitioning of the rock mass into homogeneous domains; iii) the sensitivity and subjectivity of the empirical methods; and iv) the need for validating the empirical methods against a test case. Cet article présente les résultats d’un projet visant à établir une méthodologie, pour déterminer, de façon empirique, les propriétés mécaniques de la masse rocheuse. En utilisant les corrélations disponibles dans la littérature, quelques-unes des propriétés de la masse rocheuse ont pu être déterminées (module de déformation, angle de friction, cohésion, force de compression illimitée). Une comparaison des résultats obtenus par différentes méthodes (Q, RMR, GSI, RMi, de Ramamurthy) a permis d’établir une échelle de variations des propriétés mécaniques et de formuler une série de recommandations concernant : i) la qualité/quantité des données géologiques ; ii) la technique de partition de la masse rocheuse dans des domaines homogènes ; iii) la sensibilité et la subjectivité des méthodes empiriques ; iv) la nécessité de valider les méthodes empiriques à l’aide de nouvelles études de cas. Dieses Paper präsentiert die Ergebnisse eines Projekts mit dem Ziel, eine Methodik für die empirische Festhellung von mechanischen Eigenschaften im Gesteinmassiv zu etablieren. Durch Verwendung der in der Literatur zugänglichen Korrelationen, wurden einige Eigenschaften des Gesteinmassivs festgestellt (Entstellungsmodul, Reibungswinkel, Kohäsion, unbeschränkte Kompressionsstärke). Ein Vergleich der Ergebnisse unterschiedlicher Methoden (Q, RMR, GSI, RMi, Ramamurthy’s) wurde durchgeführt und dies erlaubte die Feststellung der Variationsskala von den mechanischen Eigenschaften, sowie eine Reihe Empfehlungen für: i) Qualität/Quantität der geologischen Dateien; ii) die Technik für Teilung des Gesteinmassivs in homogene Domäne; iii)die Empfindlichkeit und Subjektivität der empirischen Methoden; iv) das Bedarf die empirische Methoden gegen neue Fallgeschichten zu validieren.

Jan 1, 2003

By C. E. Dohm

The paper serves to show the importance of both a geological model and geostatistical model that support one another in mineral resource evaluation. It highlights the advantage of reference models for the geometry, the geological, statistical and geostatistical models of various orebody types and introduces a method for quantifying the combined uncertainty in these models. The example presented reveals how the above levels of information can be applied to add value to a resource evaluation process. It is a generic example in that it is the technique of combining uncertainty in the geological model (boundaries) as well as the grade model to assess the overall risk in the estimation of the resource. Data from the coal industry is used to illustrate the techniques. The geological uncertainty is considered via categorical simulations and these are combined with simulations of the variables (grades, thickness,) being estimated in the resource. The simulation techniques used are based on the application of GSLIB software1and a general discussion of the two simulation processes is included. In conclusion the paper demonstrates how the results of two types of conditional sequential simulation can be combined to produce confidence limits that take both uncertainties into consideration. This technique does not replace the resource estimation; it serves as an additional tool to quantify confidence in the resource evaluation model. The topics considered in this contribution are in terms of continuous improvement of mineral resource evaluation.

Jan 1, 2003

By P. F. Sorensen

A simple mathematical model is presented that relates the 'head' developed at the surface of pulp in a tank to the power dissipated by the air in producing it. The value for the head is then used in the calculation of the superficial circulating velocity of the pulp and the area of the overflow, and the product of these two values gives the pumping rate of the pulp. Thus, the superficial circulating velocity, and hence pumping rate of the pulp, are related directly to the flow-rate of the air. This hypothesis was tested with good results in an air-agitated pachuca tank (of 1 m in diameter) fitted with a draught tube. The method can also be used for the prediction of the pumping rates in production-scale vessels.

Jan 1, 1985

By Y. Suzuki, H. Yoshida, K. Sakaguchi, K. Matsuki, M. Minami

To estimate three dimensional in-situ stress at great depth, Downward Compact Conical-ended Borehole Overcoring (DCCBO) technique, which is one of stress relief methods, was developed. DCCBO technique can be applied to a water-filled vertical/sub-vertical borehole. In in-situ tests, the bonding device and the cleaning system were verified to work well in a water-filled borehole with cuttings on the bottom. Um dreidimensionale in-situ Beanspruchungen in großen Tiefen abzuschätzen, wurde das Downward Compact Conical-ended Borhole Overcoring (DCCBO) Verfahren entwickelt, wobei es sich um ein diese Beanspruchungen entlastendes Verfahren handelt. Die DCCBO Technik kann auf wassergefüllte vertikale und subvertikale Bohrlöcher angewandt werden. Bei den in-situ Tests wurde die Einsatzfähigkeit der Verbindungsvorrichtung und des Reinigungssystems für wassergefüllte Bohrlöcher mit Einschnitten am Boden bestätigt. La technique de Downward Compact Conical-ended Borehole Overcoring (DCCBO) ou ‘Surcarottage par sondage à extrémité conique compact dirigé vers le bas’, qui est une méthode de détente des tensions, a été développée pour calculer les tensions in-situ à trois dimensions à grande profondeur. Cette technique peut s’appliquer à des sondages verticaux/sub-verticaux remplis d’eau. Au cours des essais in-situ il a pu être vérifié que le dispositif de liaison et le système de nettoyage fonctionnaient bien dans un trou de forage rempli d’eau avec saignées au fond.

Jan 1, 2003

By Pieter de Waal

The beneficiation equipment under the control of plant metallurgists exploits the differences in the physical properties between valuable and waste mineral components. In many cases, laboratory results are too late for process control and can only serve the purpose of "post" reports, the calculation of a mass balance and the issue of a quality certificate. As a result, experienced operators regularly adjust separation equipment based on the colour and texture of the various product streams in the beneficiation plant. Metallurgists quickly learn to recognise the different minerals in their ore body. The stereo microscope has been a valuable tool used by operators to quantify known mineral species. For many years it was the only practical method available for the purpose of process control and even for quality contro1. The modem spectroscope is far superior to the human eye and can rapidly detect a change in mineral composition. New generation optical scanners and digital signal processors can provide useful signals, related to mineral composition that can readily be applied for the purpose of process control. Successful case studies, covering dry in-line and slurry applications as well as in-plant fast spot analysers are presented.

Jan 1, 2014

By E. C. Stoltz

Note: An electric tin smelter for the processing of Iow-grade tin concentrates in South Africa by E. C. STOLTZ, Pr. Eng., B.Sc. Eng. (Rand) Gold Fields of South Africa Limited is the largest producer of tin in the form of concentrates in South Africa, more than 55 per cent of the South African tin production being produced by the tin mines of the Group. Most of these concentrates are exported to be custom-smelted in overseas smelters, but the modern tendency is for tin-mining countries to establish their own smelters.

Jan 11, 1976

By J. M. Stewart

The purpose of my few comments is to try to create a healthy perspective to constructively link considerations of the sessions to follow to those of the earlier sessions. I propose to do this by considering some of the issues and priorities related to the development of backfill systems and technology for South African gold mines.

Jan 1, 1988

By M. Kumral, S. Hmoud

Optimising the configuration of infill drill holes is an important step during mineral exploration campaigns. However, this optimisation process encompassing all possible drilling configurations within a mineral deposit is highly combinatorial and hard to solve in a reasonable time. This paper proposes using spatial clustering algorithms to divide the orebody into contiguous zones and target the best zones with infill drilling in order to reduce the size of this optimisation problem. Several clustering algorithms are assessed in a spatial context on hypothetical datasets. This evaluation shows that the hierarchical density-based spatial clustering application with noise (HDBSCAN) algorithm can be used in combination with the uniform manifold approximation and projection (UMAP) dimensionality reduction algorithm to identify contiguous zones in the orebody.

Sep 1, 2021

By R. I. Klintworth

The multi-reef area of Cooke 3 Shaft provides a unique mining challenge on account of the very thin middlings between the pay bands and the marginal values of the reef. It is uneconomic or impractical, because of the excessive heights, to mine the middlings using conventional stoping methods. The development of suitable mining methods is discussed with particular emphasis on the control of water inflow and the policy of not jeopardizing or sterilizing other reef horizons by the mining method implemented. No definite solution is currently available, but with the aid of instrumentation, computer analyses and mechanized mining equipment, the mine continues to attempt to maximize extraction and profits.

Jan 1, 1988

By B. J. Pieters

The paper describes the difficulties experienced with inferior coking coals as Iscor began using larger blast furnaces for the production of liquid iron. Research conducted at Iscor from 1977 to 1979 showed that benefits could be gained from the use of partially briqueted charges, and it was decided to install briqueting plants at the Vanderbijlpark and Newcastle Works. Details are given of the later plant, which was supplied by a consortium consisting of Voest Alpine, Didier Engineering, and Sumitomo Metal Industries. Sumitomo also supplied information on the optimization of coke quality along the lines of their Sumicoal System. The results have been a marked improvement in coke quality, much better blast-furnace operation, and increased productivity.

Jan 1, 1991

By J. M. Stewart

Although the incidence of heat stroke in South African gold mines is small, work continues on its reduction. This paper proposes limits of heat stress that are applicable to South African underground conditions, with the warning that they should not be extrapolated to other situations without careful consideration having first been given to their limitations. These limits of heat stress take physical and physiological considerations into account, and they correspond to there being a 10-6 risk of an essentially nude man developing a rectal temperature in excess of 40°C. It is recommended that further work should be undertaken on the development of equations for the calculation of the heat transfer from clothed men, the derivation of equations that quantify the physiological conductance and sweat rate response of humans, and on establishing the frequency distributions that describe variations in rectal temperature response between individuals in different types of environment.

Jan 1, 1981

By M. E. E. Douglas, A. K. Haines, D. I. Nicol, C. M. Olëm, W. M. Craig, G. D. Louw

A description is given of the design of the continuous ion-exchange demonstration plant at Blyvooruitzicht Gold Mine, including details of the process design, the column construction, and the control system. The operating and process results gathered over a period of seventeen months are summarized, and development work and modifications to the process are discussed. It is concluded that the system comprising continuous loading and continuous elution is technically feasible and can be scaled up with confidence.

Jan 1, 1978

By J. E. Furze

World-wide hikes in the oil price and the prospect of future scar cities of liquid and gaseous fuels have given enhanced status to the South African coal industry. It is thus understandable that the colloquium held at Wit bank on 3rd and 4th October, 1979, and organized jointly by the South African Institute of Mining and Metallurgy and the South African Coal Processing Society should have attracted more than 400 delegates.

Jan 1, 1979

By M. J. Nicol

This paper ,examines the kinetics of the extraction of uranium from acid sulphate solutions by strongbase anionexchange resins. Parameters such as the concentration of uranium in solution. the agitation of the resin beads in solution. the size of the resin beads. and the degree of cross-linking within the resin matrix were varied. and the effec ts on the kinetics are reported. The applicability, of various empirical kinetic models to the description of the data is assessed, and an attempt is made at the modelling of the rate data in terms of established theories about the diffusion of ions through films of stagnant liquid and through spherical beads of resin.

Jan 1, 1980

By D. G. Krige

Recent publications have demonstrated the important role that can be played by a priori information of the grade levels, variability, and spatial patterns in adjacent or nearby areas in improving the quality of grade estimates for virgin or sparsely drilled areas. A research project was therefore conducted involving the collection and analysis of extensive sampling and borehole data from 7 reefs on some 30 Witwatersrand mines. This paper shows that the 'equivalent' log variance for the two-parameter lognormal model provides a good basis for the study and comparison of the levels and behaviour of relative variances. The trends of these against the corresponding log areas were found to form distinctive patterns, which are useful for these purposes. The patterns for the Basal, Vaal, Carbon Leader, and Main Reef Series form a reasonably close group, whereas those for the V.C.R.(particularly where the facies are mixed), B Reef, and Kimberley-Elsburg Reefs (particularly for narrow channel widths) do not always conform. The patterns shown by underground chip samples are also compared with those obtained from borehole cores. It is shown how this information can be used to improve the borehole valuation of new mines and of virgin areas in existing mines.

Jan 1, 1993

By S. A. Lorentz, Y. Xu, C. Theron

The failure of tailings storage facilities (TSFs) results in the discharge of significant quantities of hazardous waste material into the natural environment. Research studies relating to slope instability have identified physical mechanisms such as rainfall-induced erosion, liquefaction, and shear failure as the main triggers. The generation of transient pressure waves and the mobilization of pre-event water in the unsaturated zone have been found to trigger shallow landslides in natural hillslopes. In this paper we review these physical mechanisms, known as groundwater ridging (GWR) and the Lisse effect (LE), from other studies. Previous researchers have explained both these phenomena through field and laboratory observations, numerical modelling, as well as conceptual discussions. These case studies demonstrate the impact of rainfall characteristics on the generation of transient pressure waves that rapidly increase the phreatic surface and change pore water suction. Reference is also made to the influence and behaviour of physical porous medium characteristics on the establishment of a continuous water phase that facilitates the transmission of an induced pressure head. However, previous studies fail to recognize the possibility that the pressure increase in pre-event water through pore air propagation could cause slope instability in tailings dams. The authors suggest that the physical properties and hydraulic behaviour of unsaturated porous tailings media make it susceptible to GWR and the LE, resulting in the creation of a potential failure plane.

Feb 2, 2022

By H. Jiang, W. Wang, Y. Zhao, Q. Jinpeng, C. Duan

Dry deep screening is an important method of classifying moist fine mineral. The rigid-flexible coupled elastic screening technology can simultaneously solve the problem of traditional screen surface plugging and the low service life of a screen surface in the process of deep screening. In this paper, two kinds of rigid-flexible coupled elastic screen surfaces were introduced. The structural characteristics of a screen surface were studied. The mechanism of a rigid flexible coupled elastic screen surface to overcome hole blockage was revealed. Finally, 3 mm and 6 mm screening experiments were carried out. When the external moisture content was below 12.79% for the 6 mm dry screening experiment of elastic rod screen surface, the screening efficiency was above 81%. When the external moisture content was below 11.31% for the 3 mm dry screening experiment of elastic screen surface based on ball hitting, the screening efficiency was above 83%. Keywords: Moist fine mineral, rigid-fexible coupled, elastic screening

Jan 1, 2020

By G. R. Marchant, B. K. Loveday

"A mathematical model has been developed for flotation circuit simulation. This model was designed to investigate the effect of varying the circulating loads and to determine whether an improvement in overall efficiency could be gained by a size separation prior to flotation.Model parameters were obtained by regression to plant data. Highly correlated parameters in the model were combined to reduce the number of parameters so that the need for excessive data gathering was eliminated. Mass balance smoothing was used to obtain a consistent data set for regression.The results of the simulation indicate that for the same grade of concentrate, an increase in copper recovery of 0.6 per cent may be Possible by increasing the circulating loads. The results of the simulation also indicated that recleaning of the plus 200-mesh material may be beneficiaL."

Jan 1, 2014

The optimal design of production phases and ultimate pit limit for an open pit mining operation may be generated using conventional or stochastic approaches. Unlike the conventional approach, the stochastic framework accounts for expected variability and uncertainty in metal content by considering a set of equally probable realizations (models) of the orebody. This paper evaluates the performance of a new stochastic network flow approach for the development of optimal phase design and ultimate pit limit using a gold deposit as the case study. The stochastic and conventional frameworks as considered here utilize the maximum flow and Lerchs-Grossman (LG) algorithms, respectively. The LG algorithm is restricted to considering an estimated (average-type) orebody model, while the stochastic maximum flow algorithm is developed to simultaneously use a set of simulated orebody realizations as an input. The case study demonstrates that, when compared to the conventional LG algorithm as used in the industry, the stochastic approach generates a 30 per cent increase in discounted cash flow, a21 per cent larger ultimate pit limit, and about 7 per cent more metal, while it maintains a consistency in phase size.

Jan 1, 2012