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By L. Gunnewiek

An advanced real-time monitoring system called the tapblock diagnostic system (TDS) has been developed. The purpose of the TDS is to help furnace operators manage the safe operation and economical maintenance of furnace tapblocks. This system is an evolution of the current practice of using historical records and operator interpretation to assess the ?health? of a tapblock. The main parameters affecting tapblock health are heat removal capacity and refractory wear, and these are currently difficult to assess in situ except in a global way. By using monitored and operating data together with predictive numerical modelling and multivariate statistical methods, real-time tapblock performance is assessed relative to expected performance. A state indicator in the form of a green, yellow, and red light is used by furnace operators to monitor the tapblock performance and health status during operation. Access to historical operating data and the provision of diagnostic functions allow for probable health degradation events to be deeply investigated. A recent opportunity to evaluate the actual performance of a first generation TDS installed in the KIVCET furnace at Teck Cominco?s Trail Operations showed that a reasonable estimate of tapblock health was made. However, the evaluation also found that some areas of refractory wear were missed, and a new mechanism affecting refractory wear was discovered that was not previously known. This has reinforced the belief that there is a need to develop improved methods of monitoring so that data used to define the health of the tapblock is more comprehensive and accurate.

Jan 1, 2008

By T. Wallmach

Heavy mineral deposits are a source of the economic important element titanium, which is contained in minerals such as ilmenite, pseudorutile and rutile. In the Ranobe heavy minerals deposit these minerals occur not only as primary unaltered minerals but also display various degrees of alteration resulting in an increased titanium content of the deposit. The presence of the various FeTi-oxide minerals? textural relations is a reflection of geological processes and may ultimately be used to unravel the geological history of the deposit. These minerals have different chemical and physical properties that influence metallurgical tests and the quality of products produced from various mineral beneficiation streams. It is therefore of metallurgical importance that the minerals are well characterized, defined and monitored during preliminary beneficiation tests.

Jan 1, 2007

By W. P. C. Duyvesteyn, J. R. Cutland, J. R. L. Russell

In 1970 it was decided to build a large new plant at the Chingola Division of N.C.C.M., Ltd., to treat concentrator tailings and leach residues with a low copper content by a leach-solvent extraction-electrowinning process. In order to assist in the establishment of the design parameters for the new plant, and to study the interaction of this plant with the existing leach-electrowinning plant, mathematical models, formulated as linear programs, have been developed and used extensively. The paper outlines the metallurgy of the plants and describes briefly the way in which the models have been formulated and used. The formulation involved the use of separable programming to form the products of some variables.

Jan 1, 2014

By C. A. Preece

Finsch Diamond Mine, part of De Beers Consolidated Mines (DBCM), is situated between Kimberley and Postmasburg in the Northern Cape, South Africa. The kimberlite pipe was discovered in 1960 and De Beers assumed full mining rights three years later. Production commenced in 1966 from an opencast mine, and the operation moved underground in 1990 by developing and implementing a new mining method of blast hole open stoping. A mechanized block cave was brought into production in 2005. While block caving was not new to DBCM, with productive caves having operated in Kimberley and Cullinan, from the outset, the Finsch caving operation was designed as the most advanced with a semi-automated ground handling system. The extraction level was laid out as a single sided herringbone system due to the very poor ground conditions on the south side of the pipe. These factors combined to create a unique environment, which necessitated a completely new approach to draw control. The required system was developed by a team consisting of DBCM personnel from head office and Finsch, GEMCOM and Sandvik-Tamrock, the equipment manufacturers. It was essential that the system could be run quickly, provide daily updates and issue calls directly to the LHDs. It was also important that the base data were obtained from the resource model, which was to be depleted on a monthly basis, thus forming a close link between mine planning and draw control. A further requirement of the system was that it would form a central database for the extraction operation where all data pertaining to delays and changes in conditions, be they production or ground condition related, could be recorded and analysed. The design brought together empirical rules and tables developed at Cullinan plus concepts from programming developed for the front cave at Koffiefontein so that the new system was based on sound practical experience. These facets were incorporated into PCBC (GEMCOM) and CMS and PCS (Sandvik-Tamrock programmes). The system has now been operational for just under a year and while modifications have had to be made, it has proved itself as a practical and reliable tool with which to manage the draw control at Finsch. The system is unforgiving and has forced the production team to focus on the specified drawpoints. Problems have been encountered but most of these have been related to re-educating a workforce, familiar with a flexible mining method, to the strict discipline required for a modern block cave.

Jan 1, 2007

By E. J. Y., G. J. McLachlan, E. Amini, Koha

Inferring individual component flotation rates from recovery-time data of ore complexes is important in optimising and designing minerals processing plants. However, existing two-component first-order flotation models are computationally intensive to solve using conventional non-linear least squares regression. In this paper, a Convolutional Neural Network (CNN) is used to approximate the inverse function which predicts the two-component first-order model parameters using recovery-time data. This paper compares the accuracy and computation speed of the proposed CNN against traditional non-linear least squares regression on 1 million generated data based on a known two-component firstorder kinetic model. It is shown that using a CNN is possible to approximate the inverse function for the non-invertible two-component model with recovery-time as an input matrix for convolution operations. The CNN method is 450 times faster to compute than the Trust-Region (TR) non-linear least squares regression algorithm. However, the CNN model is less accurate compared to the TR algorithm overall. Keywords: Flotation kinetics, convolutional neural network, inverse problem, modelling and simulations

Jan 1, 2020

By L. M. Tavares, T. M. Campos, P. M. Faria, R. M. Carvalho

Recent advances in mechanistic ball mill modelling are expected to allow for more accurate predictions that overcome the well-known limitations of phenomenological approaches, including their inability to predict the effect of liner geometry and their wear, in grinding. Although able to describe continuous operation, the UFRJ model of ball mills has only been validated in the past in mills that operate in batch mode, either in laboratory or pilot scale. The present work demonstrates the application of the mechanistic UFRJ ball mill model to predict fine grinding of iron ore in a pelletising plant in Brazil, the first application of such a mechanistic modelling in continuous mode. It shows that the model provides accurate descriptions of flows after iterations in a closed-circuit with hydrocyclones. Keywords: Ball mill, iron ore, grinding, modelling, particle breakage

Jan 1, 2020

By J. Danoczi

South Africa is running out of fresh water and is looking at ways to improve water usage. This report addresses how a diamond mine in Gauteng has improved the utilization of its water resources. In the past, water from the local river was deemed the most suitable to use in the grease recovery plant but subsequent tests on the water from the slimes dam have shows that this water source is in fact more suitable for diamond recovery. Utilizing the slimes dam water provides a more stable water source than the local river while also reducing the impact of the mine on the water resources in the area.

Jan 1, 2008

By D. F. Malan, J. A. L. Napier

A number of shallow coal or hard rock mines employ pillar mining systems as a strategy for roof failure control. In certain platinum mine layouts, pillars are designed to ‘crush’ in a stable manner as they become loaded in the panel back area. The correct sizing of pillars demands some knowledge of the pillar strength and the overall layout stress distribution. It is particularly important to understand the impact of the layout geometry on the effective regional ‘stiffness’ of the rock mass around each pillar. An important design strategy is to model relatively detailed layout configurations which include a precise representation of the local pillar layout geometry and to analyse multiple mining scenarios and extraction sequences to select optimal pillar sizes and barrier pillar spacing. Although computational solution techniques are now impressive in terms of run time efficiency, a major difficulty is often encountered in assigning suitable material properties to the pillars and in devising an effective material description of the layered rock strata overlying the mine excavations. This paper outlines an efficient numerical strategy that can be used to assess large-scale pillar layout performance while retaining the ability to modify individual pillar constitutive behaviour. The proposed method is applied to selected layouts to compare estimated average pillar stress values against values determined by detailed modelling and against observed behaviour.

May 3, 2023

By J. Bullón, A. Pérez

Some years ago, Ferroatlantica developed a new type of electrode known as the ELSA electrode. In this electrode there is a central graphite core that provides support, surrounded by an annulus of Søderberg paste that gets baked during operation. This technology has been implemented on several silicon furnaces around the world, and was reported on during the previous Infacon conference. In all electrodes, but particularly in the ELSA electrode, the quality and consistency of the paste are important for correct operation. As the type of paste varies between customers and between countries, Ferroatlantica has developed a quality control procedure for their customers of this technology. This procedure is geared to the point of view of the customer rather than the paste producer. The analysis is based on the desired flow pattern of the raw paste and on the desired mechanical and electrical properties of the baked paste, as experience has shown that these are the most important parameters to monitor in order to avoid having problems with the resulting electrodes. This paper discusses these methods of paste analysis in the light of complementary studies that have been done when there has been an electrode breakage in the different plants.

Jan 1, 2007

By G. M. Dunn

Pressure leach autoclave circuits are employed in the leaching of ores, concentrates, mattes, alloys and intermediates for the recovery of metals into solution. Once the metals are extracted into solution, the value metals can be recovered by hydrometallurgical means such as by purification followed by electrowinning, hydrogen reduction, pyrohydrolysis, crystallization and other unit operations. In many of these integrated flowsheets the pressure leach step is pivotal to the recovery of the value metals from the host material. Furthermore, the autoclave circuit invariably is a high capital cost component of the plant and an area that is carefully scrutinized when debottlenecking and capacity increases are being considered. This paper identifies a unique proven way of increasing the capacity of existing or new exothermic pressure oxidative leach autoclave circuits by as much as two or three times.

Jan 1, 2009

By Daniel W. Kappes, Pierre F. X. Mousset-Jones

"In this paper a discussion is presented of a program designed to produce a 40-day production forecast for an underground stoping system.The program is intended to be a tool for the operations department in an underground mine, and is designed to utilize data readily available from production reports. Brevity of data input, ability to revise slope conditions easily and the accuracy of starting stope status are stressed. Applicability of the program to a wide variety of sloping methods makes the program potentially useful in a large number of mines.The general functions of the program subroutines, and input and output lists are discussed. An example is also given of a stope in operation for a three-day period, which shows how the program can handle production irregularities as they arise."

Jan 1, 2014

By E. M. W. Skinner

Various models of near-surface kimberlite pipe emplacement have been proposed over the years. These include a top-down, phreatomagmatic model, a bottom-up, embryonic pipe model and three top-down explosive dyke models. AU of these models consider kimberlites as essentially the same rock type. However, different kimberlites have different pipe shapes and contain different rock types with very specific mineral assemblages and textures and therefore are likely to have been emplaced by different processes. Some authors have considered local geological differences as the principal reason for the contrasting geology but others argue that, while geological differences might contribute locally the petrographic peculiarities of particular kimberlites may be due mainly to inherent compositional differences specifically in the ratios of juvenile CO2 and H2O.

Jan 1, 2010

The 114th Annual General Meeting of The Southern African Institute of Mining and Metallurgy was held at The Country Club, Johannesburg, Napier Road, Auckland Park on Thursday, 11 August 2011. Welcome The President extended a special welcome to the guests and representatives of our sister institutes and other associations, and also to recipients of awards, senior members of industry, Honorary Life Fellows, past-presidents, our members and other guests, among them the following: F. Cawood, President, Institute of Mine Surveyors of South Africa C. Roode, President, Mine Metallurgical Managers' Association of South Africa M. Cresswell, Chairman, South African Coal Processing Society A. Hay, Immediate Past President, South African Institute of Electrical Engineers L. Gardner, President, South African National Institute of Rock Engineers J. Krynauw, President, The Geological Society of South Africa (GSSA)

Jan 1, 2011

By L. Cortez, Á. Magalhães, F. Durão

Methods based on regionalized variables theory, commonly known as geostatistics, have been widely used since more than three decades to predict/estimate spatial distributed data, namely mineral resources, with quite good results. However, some restrictive theoretical assumptions, such as the need of some kind of stationarity of data and the linearity of the predictor/estimator, are often wrong options in many applications. An alternative approach based on a finite mixture modelling, or cluster weighted modelling (CWM) technique, is presented and compared, in its theoretical and practical aspects, with the geostatistical methodology. CWM is a general non-linear framework based on the estimation of joint density functions allowing the calculation of the conditional probability function of the target values given their locations. Validation tests are performed in a 2D case study, where testing data proceeds from a soil contaminated by a heavy metal. The results of ordinary kriging and CWM estimations show a very good agreement with actual data. Keywords: Non-linear regression, Geostatistics, Ordinary kriging, Finite mixture modelling, Cluster weighted modelling.

Jan 1, 2003

It is well understood that to develop wagon wheels with higher abrasion resistance, fracture toughness, and fatigue resistance, steels with lower amounts of inclusions need to be used. Clean steels are produced with technologies that minimize the amount of inclusions in the microstructure. The demand for cleaner steels is high, and lowering of non-metallic oxide inclusions and controlling their morphology, composition, and size distribution is vital. Reduction of residual impurity elements such as sulphur, phosphorus, hydrogen, nitrogen, and trace elements is essential in the production of cleaner steel. Material cleanliness is vital for fatigue endurance, since oxide inclusions may act as stress concentrators and initiation points for fatigue cracks. To better understand the relationship between the cleanliness and toughness of the 34-inch cast wagon wheels, two samples of different levels of cleanliness were supplied for investigation. This paper presents the results of metallurgical analysis using scanning electron microscopy(SEM), energy-dispersive spectrometry (EDS), and mechanical tests for the pearlitic high-performance cast rail wagon wheel (identified as Class B) that are currently being used. The Charpy V-notch impact test results for the three samples from wagon wheels were compared. With the aid of SEM/EDS analysis system, non-metallic inclusions in these steels were detected, and it was possible to determine the position, size, shape, and composition of each particle. Alumina and manganese sulphide inclusions could be identified as the dominant inclusion types in the investigated samples. Fracture surface analysis of the Charpy specimen with high inclusions indicated that transgranular cleavage was the predominant fracture mode. Fractography of fracture surfaces of Charpy impact test samples also showed improvement of toughness properties on the clean sample.

Jan 1, 2013

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

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

Mar 14, 2024

By A. Madowe

This paper discusses the mine planning process for Letseng diamond mine in the Kingdom of Lesotho, in conjunction with the various software packages used during the process. The major pillars of the long-term mine planning process at Letseng are pit optimization followed by pit design and scheduling. Letseng uses Gemcom Whittle and GEMS for pit optimization and design and Runge XPAC for scheduling. The output of the mine planning process results in the generation of published mineral reserves and provides input into the Letseng overall business plan. The process of defining the key inputs for the entire mine planning process is discussed, which covers: ? Pit optimization ? Slope design as an input ? Diamond price inputs ? Operating and capital cost inputs ? Haul road design ? Generation of pit shells ? Selection of an optimum pit shell and interim cutbacks using operational scenarios ? Sensitivity analysis on the selected optimum pit shell. ? Pit design ? Slope design criteria in the detailed design ? Split shell vs concentric pit design ? Practical mining widths to determine cutback design ? Ramp design ? Pit design process in the GEMS software package. ? Detailed scheduling ? Development of scheduling scenarios in the XPAC software package ? Planning through mining production bottlenecks. ? Company-level NPV model ? Comparing scenarios and input of the different schedule scenarios into the company NPV model. Keywords pit optimisation, mine planning, pit shell, recovery, dilution, revenue factor, pit design, split shell, sensitivity analysis, scheduling, production bottleneck, NPV, discounted cashflow.

Jul 1, 2013

By Q. G. Reynolds

The problem of direct-current plasma arc behaviour, interaction, and dynamics is considered in the context of metallurgical DC arc furnace applications. Particular attention is paid to the transient flow behaviour of arc systems. A mathematical formulation of the physics used to describe the arc system is presented, and includes the spatial and temporal evolution of fluid flow, heat transfer, and electromagnetism. Based on this formulation, a numerical model is developed using a finite difference approach on a regular cartesian grid in both two and three dimensions, with a special focus on robust stability, high resolution modelling, and high performance. A collection of results produced using the numerical model to study pilot plant-scale furnaces is then presented. These address a range of process and design variables and their effect on the numerical model?s results. Where possible, the qualitative behaviour of the model is compared to available experimental data. A number of novel effects and phenomena are seen in the dynamic behaviour of the DC plasma arc model for both single and multiple arc systems, which may lead to improved understanding, control, and manipulation of such systems where they occur in industrial applications. Keywords Pyrometallurgy, direct-current furnace, plasma arc, modelling.

Jan 1, 2010

As part of a broad program to optimise the performance of their grinding circuit, BHP Billiton Cannington have installed an OCS© Expert system together with three VisioRockTM online particle size analysis cameras. The main purpose of the system is to stabilise grind size and feed to the flotation circuit. This particular application of OCS© is the first installation to incorporate Metso Minerals Process Technology-Asia Pacific's (MMPT AP) Dynamic SAG/AG Mill Model, which is able to predict numerous mill parameters that were previously unable to be measured with the existing plant instrumentation. Integrated into the logic of the control algorithm are online vision based, particle size measurements of the AG mill feed and recycle crusher product. This paper will describe the history of the project from initiation to date, the model and OCS© logic configuration, and demonstrate the significant benefits realised at Cannington mine.

Jan 1, 2007

By J. A. Maree

After the South Deep complex was purchased by Goldfields in 2006a re-feasibility study was done and the life of mine (LOM) was extended to 52 years. This also implied that the mine?s infrastructure would have to be enhanced. One of the changes was the proposal of five new main orepass systems to be excavated before the mine reaches full production in 2013. Excavations started to show signs of scaling, and in some cases, whole new excavations were lost. This particular area was exposed to very high stresses and the geology was prone to body delimination rendering the relevant areas unstable. This paper investigates the conditions at the location of one of the proposed orepass systems, and the best possible orientation was suggested to ensure that the orepass system would be stable and have a practical life. It was, however, found that the fourth leg of the orepass system would require further support to be classified as stable by the chief rock engineer and the section geologist of South Deep. Several support methods and orepass system linings would then be analysed and evaluated to give calculated recommendations on how to productively and practically support an orepass system. Keywords Main orepass system, stresses, body delamination, impact and abrasion, rock support, concrete lining.

Jan 1, 2011