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By R. Falcon, A. J. Ham

This paper summarizes the characteristics of Southern African coals, presents a fundamental approach to the combustion performance of coal, and reviews some of the recent developments in the fields of technological evaluation and boiler design for coals typical of this region. This includes a summary of the petrographic constituents of coa~ highlighting the differences between the Palaeozoic coals of the northern and southern hemispheres (Laurasia and Gondwana respectively), and the effects of these properties on the combustion performance of coal as seen in terms of laboratory, pilot-scale, and full-scale operating conditions. Recent developments in boiler design linked to advanced characterization studies and commercial experience have led to unprecedented use, with maximum effect, of the low-grade, high-ash, high-inertinite coals typical of some parts of this region. In the light of this success, more adequate understanding and better methods of assessment of the coals typical of the Gondwana region are called for, particularly in the light of the price premium for high-grade coal and the more cost-effective lower grade coals on the international steam markets.

Jan 1, 1988

By Anders Erlandsson

"The crude ores from the LKAB mines are sorted and refined into a number of products. As there are a number of different plants the flow of material is often complex.in connection with studies of a proposed extensive investment program it was necessary to get a good measure of the changes which would be caused in the total profit by the different possible investments. A linear programming model was set up to accomplish this, and to cover the consequential effects on the production system. The objective function of the model maximized the total profit, taking into account restrictions in materials balances, blending conditions, production capacities and market. The changes in total profit resulting from the different investment alternatives, together with investment and fixed costs, were used in a series of investment analyses. The application has proved to be very successful and the results come very near to what was expected."

Jan 1, 2014

By D. D. Marsden

This paper discusses the concentrations of sulphides and total sulphur in widely spread regions around mine residue deposits, from which rain-water run-of can enter the Vaal River system. Analyses of borehole samples from several deposits are used to establish typical sulphur head grades. It is shown that a high percentage of al the oxidizable, and hence leachable and pollution-causing, sulphur has already been removed. When the residues were fresh, water that came from the deposits was highly polluted, but the dissolved solids from these residues are today of very minor significance. The data are supported by analyses of the drainage streams.

Jan 1, 1986

The 95th Annual General Meeting of the South African Institute of Mining and Metallurgy was held in the Gold Room of the Transvaal Automobile Club in Johannesburg on Wednesday, 12th August, 1992.

Jan 1, 1992

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 R. Perlman

This paper describes the various new computer-aided techniques being used by economists in the construction of economic models. It discusses the relevance of these techniques to mining industries. In particular, it describes their role in making it possible to obtain better estimates of future price and demand developments on the markets on which metals are sold, and how these estimates can be used to improve forward planning by mining companies.

Jan 1, 2014

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 K. L. Morton

This technical note reviews the status quo of mud rushes and flooding, which have claimed them lives of many people in underground mines in South Africa and globally. Given that the causes are well known and can be managed, the note calls for the development of a national and global standard on flood and mud rush prevention in order to save lives.

Mar 30, 2026

By B. Jack, A. Vervoort

During pillar extraction, sidewall fracturing and spalling at some collieries constitute a severe stratacontrol problem. In order to obtain a better understanding of this phenomenon, a survey of pillar corner conditions before and during pillar extraction was conducted at one particular site. For the various successive mining steps, the vertical stresses on the pillar corners were calculated by use of a three-dimensional boundary element program. A significant correlation was found between the calculated vertical stress prior to the extraction of the panel and the sidewall conditions. During the extraction of the panel, a significant deterioration of the sidewall conditions at a pillar occurred only when the adjacent pillar was mined, causing an increase in vertical stress on the remaining pillar.

Jan 1, 1992

By A. Marek

The safe and optimal installation of roof support remains one of the biggest challenges in underground mining today. Traditional hand-held, roofbolt installation in conventional mining has been replaced, in a lot of mining operations, by mechanized equipment. This was a first step to moving the operators out of the unsafe working environment and a start on the trend toward a changed support regime in mechanized mining. However, the challenge of handling of the drill steel itself, as well as inserting resin cartridges and bolts, remains a major hazard and the cause of many lost-time injuries. The paper describes and discusses developments in this area, of mechanized bolting and on-board automation, presenting solutions to known problems, achievements to date, and future developments. The solutions presented will identify with addressing customer needs while touching on possibilities for further technology changes, keeping focus on the safety aspect for operators and the need to bring the operators even further away from the unsafe working environment. The-state-of-the-art technology in mechanized bolting equipment is presented and a brief outlook on the past, current, and future developments is given.

Jan 1, 2012

By A. Kapito

The ferrite-pearlite microstructure is the most popular microstructure for alloys used in structural applications, including railway wagon wheels. These alloys have been designed through alloying and thermo-mechanical processing to have a refined microstructure. Ferrite-pearlite alloys are low cost, weldable, have good fabricability, and are reliable under extreme conditions. Given these performance attributes, it seems unlikely then that their dominant position as structural steels would ever be challenged by alternative microstructures. One major achievement in the development of ferrite-pearlite steels has been in the refinement of their interlamellar spacing to very fine distances of the order of < 0.3 µm. A refined microstructure increases the hardness of the alloy, thus increasing its life under wear conditions. The interlamellar spacing in pearlitic steels has, however, been refined almost to its theoretical limit. The increasing demand for speed and increased axle loading on railway wagons requires the use of stronger, tougher, and more durable materials. This has opened the window for the development of novel bainitic steels. Bainitic alloys have a higher level of microstructural refinement than pearlitic ones. They have shown to have good wear resistance and rolling-contact fatigue resistance, and high toughness. This paper will discuss the progress to date on the development of bainitic railway wheel alloys. Four alloy chemistries have been chosen for possible further development.

Jan 1, 2012

By V. E. Cogho

Optimum Coal Mine comprises numerous defunct, active, and future mining sections. The mine is primarily a large opencast coal mine; however, underground mining activities will be increasing steadily over the next five years. Opencast and underground mining activities have a significant impact on surface and groundwater resources. To ensure that the mine will be able to continue with its mining operations in the catchment, the extent of this impact requires that substantial intervention and mitigation measures need to be implemented to ensure the environmental integrity and economic use of the catchment&apos;s water resources. In developing a sustainable long-term mine water management strategy, numerous scenarios had to be analysed. The various scenarios are a combination of water and land management activities. The main components of the mine&apos;s integrated water management strategy include: ? Management of water recharge by continual and appropriate rehabilitation of disturbed land ? Beneficial re-use of impacted mine water for coal plant process water and mining operations ? Reclamation and desalination of remaining excess impacted mine water to potable standard. From the mine&apos;s long-term water balance, it is evident that the continued implementation of numerous water management actions is required to mitigate the water resources impact in a sustainable manner. In addition, the installation of a water reclamation plant at Optimum Coal Mine (15Ml/day) is a key step for the mine to achieve a zero impact target.

Jan 1, 2012

By R. Kosmicki

Wet end components of centrifugal slurry pumps used in the hydraulic transport of solids are subject to substantial erosive wear. Accurate prediction of the casing wear rate and location for a particular duty is beneficial for correct pump selection and design, maintenance planning, and elimination of emergency shutdowns. CFD multiphase simulation using the Eulerian-Eulerian approach is being applied successfully to determine the velocity fields and solids concentration in the centrifugal pump, allowing for accurate predictions of casing wear patterns resulting from sliding abrasive wear. Simulation results for various single domain and multi-domain (multistage) multiphase simulations are discussed. Emphasis is placed on results from a 3-dimensional, multi-stage transient, multiphase simulation and comparison to field data.

Jan 1, 2007

By J. J. van Vuuren

Pipe-stick support in deep-level gold mines is first described and illustrated, a pipe-stick being a mine pole trimmed to the required size and sleeved by a pipe. An account is then given of an investigation into this form of support that involved load-compression tests in a 1000-ton press, tests in a rapid loading machine simulating rock-burst conditions, a study of the load-compression behaviour of pipesticks installed underground, and a cost evaluation. Pipe-stick support was found to be very effective on the face and to cost less than conventional matpacks.

Jan 1, 1979

By V. Matou?vek

The paper addresses pipe flows of aqueous medium-sand slurries at velocities lower than the deposition-limit velocity. Laboratory test results including measurements of particle concentration distributions are used in order to describe a flow with a (pseudo-) linear concentration gradient above a stationary bed. Particle dispersion within the flow is evaluated and a stratification-ratio equation is formulated, estimating a portion of contact load in the flow. The formula is incorporated in the proposed predictive model for the hydraulic gradient for a medium-sand flow above a stationary bed.

Jan 1, 2007

By S. Vorberg, B. Fischer, U. Glatzel, R. Völkl, D. Lupton, M. Wenderoth

Owing to their excellent oxidation and corrosion resistance, Pt and its alloys are being used preferentially at elevated temperatures and in aggressive environments. For example, an important application field is the glass industry. Alongside the discovery of new potential application fields, the knowledge of material properties is essential for computer simulations, design configuration, process optimization, research and development or quality assurance purposes. Due to the importance for technical applications high-temperature properties have been investigated for currently available Pt-base alloys with ongoing improvements. For the determination of tensile creep test data up to 3000°C, including precise strain measurement, special experimental equipment has been developed at the University of Applied Sciences Jena, Germany. An overview of the existing and newly obtained mechanical property data on pure Pt, solid-solution strengthened Pt-Rh alloy, oxide dispersion-hardened materials Pt DPH and Pt 10%RhDPH as well as cutting-edge results on Pt-base superalloys hardened by intermetallic precipitates will be presented and discussed. Furthermore, some important application examples for the abovementioned Pt-materials will be given.

Jan 1, 2006

By Q. Li, B. Ricks

Over the last several decades mineral concentrate long distance slurry pipelines have been installed and successfully operated. Nearly all were installed via the buried construction method. Their record of depend ability and economy has been well proven. However, these systems operate in regions where seasonal soil frost penetration is shallow or non-existent. In recent years interest in long distance mineral concentrate pipelines in northern cold regions has been increasing. For cold regions one must consider seasonal temperatures and soil frost penetration in order to ensure reliable operations through the year. Herein a case study is developed where heat balance and temperatures for small and large diameter long distance slurry pipelines are compared. The study development is as follows: ?Rheological properties are analysed over range of temperatures from near freezing (4ºC; 39ºF) to relatively very warm (40ºC; 104ºF). ?Then assuming similar climatic conditions, soil properties, and pipeline length, a study is carried out for two pipeline diameters, namely: a small diameter (nominal8 inch; 219.1 mm) and a large diameter (22 inch; 558.8 mm). ?The study focus is on maintaining slurry temperature above freezing throughout the pipeline length by illustrating a decision based on burial depth versus coating the pipeline with insulation.

Jan 1, 2007

By H. Scott-Russell

Much of the technology and methodology extensively employed in current mining operations is in the mature phase of its lifecycle and, consequently, subject to the principle of diminishing returns. It is probable that future gains in productivity and safety of the magnitude essential for the sustained economic viability of the industry will be derived only from a determined technological development programme. The history of trackless mechanized mining, which represented a radical change in methodology in deep-level gold mines, is reviewed. The benefits and obstacles to the realization of the full potential are highlighted. Similarly, an overview is given of alternative mechanization developments in South Africa. In addition to the development and application of advanced technology, an envelope of operating parameters relevant to each methodology must be engineered to facilitate the site-specific selection of the most appropriate. Furthermore, a mechanism for the evaluation of cost effectiveness is essential to the decision-making process. The narrow, tabular orebodies of relatively low dip that are encountered in the South African hard-rock mining industry make the design and manufacture of a comprehensive range of stoping equipment extremely difficult. The machinery that has been available to date has demonstrated only limited site-specific success. The development of suitable machinery must necessarily be initiated and driven by the South African mining industry in collaboration with the major equipment manufacturers in the world.

Jan 1, 1993

By Maggi Loubser

"In a technologically advanced era, where process control is accurately maintained within the smallest error margins, and accuracy and precision are continuously improved, sampling is still left to the lowest paid employee in the company without training him or her properly to understand the relevance and importance of the task. In this paper the objectives of sampling in a process control environment is discussed and an attempt is made to link it to the theory of sampling. Some of the practical problems associated with implementing theoretical sampling principles in an industrial environment will be elucidated and some examples given on how compromises are made. Different methods of sampling will be discussed with real life examples from different manufacturing industries."

Jan 1, 2014

By G. J. Wright, M. J. Neale

As machines become more complex and vital to our way of life, any disturbance or failure of their proper functioning tends to have serious consequences. To prevent such failures, increasing attention is being paid to techniques for the monitoring of machinery condition or &apos;health&apos;. Of the many methods available, examination of the lubricant and any particles it contains forms a basis for interpretation of the conditions of operation, and the rate and severity of degradation of the moving parts, in a machine. Many techniques of wear-debris analysis, such as spectrographic oil analysis and ferography, are available indicate the composition, shape, size, and concentration of contaminants in a lubricant. This paper reviews the important aspects of wear-debris analysis as an integral component of machinery condition monitoring, and gives an insight into the selection of appropriate techniques and the information that can be obtained from each.

Jan 1, 1987