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By P. van der Steen

This paper examines the historical developments in diamond beneficiation technology and the impacts on the industry. The art of diamond beneficiation has given way to the application of scientific process, but at considerable capital expenditure. The shift in beneficiation methodologies has been disruptive to the traditional skills set of the industry, but evolutionary change continues and has been beneficial to the quality of the final product.

Jan 1, 2010

By L. C. Woollacott

A computer-aid is described that is designed to calculate steady-state material balances for ore-dressing circuits. The program determines the material balance from a specification of the process condition. No mathematical models or data adjustment techniques are employed. As such the program complements existing simulation and material balance 'smoothing' packages. The process condition is specified using performance indicators. These are significant parameters in the industry with which all practising mineral processors are very familiar. The program employs an equation-oriented technique for material balancing and so has had to deal with the difficulties peculiar to that approach.

Jan 1, 1987

By S. Kahraman

P-wave velocity measurements were carried out on 22 large limestone blocks in a stone processing plant. In the laboratory, P-wave velocity of core samples was measured to obtain intact rock velocity. The square root of the ratio of the velocity of the large stone block to the velocity of the core specimen was called the velocity ratio index (VRI) and a quality classification for large building stones was suggested. In addition, the applicability of the established classification to stone cutting with gang saws was checked. It was concluded that the quality classification and estimation of slab production efficiency of the building stones can easily be made by ultrasonic measurements. However, the study was carried out only in limestone. Further study must be conducted to check the validity of the obtained results for the other rock types.

Jan 1, 2007

By S. R. Xie, S. Gong, E. P. Li, S. S. He, Y. J. Sun, S. J. Li

"Based on the complicated geological production conditions and abnormal strata behavior of the fully mechanized caving face No. 102 in the Xinyang Coal Mine, we analyze the breaking and forming process of distinguishing key block structures in close spaced coal seams. This analysis establishes an integrated mechanical model of these distinguishing structures. Furthermore, the horizontal force TAB generated by downward key blocks A and B is quantified, as is the Pressure PG exerted by key block B on caved gangue. Finally, the interaction mechanism is revealed. Analysis of the results using Mathematica reveal the following: 1. Both TAB and PG exhibit approximately inverse relationships to coal pillar width b; 2. TAB exhibits an approximately exponential relationship with mining height M of which the base is greater than 1; 3. PG exhibits an approximately arctangent relationship with mining height M. Combining these results with field observations, we conclude that the area in the vicinity of supports 100#–120# in the upper area of working face No. 102 is the likely zone of abnormal strata behavior. Thus, this area was classified as a key control area. Based on these results, the graded support control technique is proposed. Application of this technique in the field resulted in a reduction in the rate of hydraulic support system malfunction from 47% to 7% in the key control area. In addition, during times of periodic mining pressure, the roof caving height value never exceeded 0.3 m and the maximum spalling depth never exceeded 0.2 m. Overall, the results indicate that this new technique has markedly increased the stability of surrounding support rock material. IntroductionClose-spaced coal seams are widely distributed in China, and mining proceeds from the uppermost to the lowermost seam (Zhang et al., 2008). In the case of coal seams in close proximity, a particular set of risk factors becomes pertinent. These include disturbance of lower seams during the mining of overlying ones and the decrease in mechanical stability of lower coal seams following repeated movement of key blocks in main coal seam roofs. This inevitably results in behaviour such as heavy wall spalling and support damage to fully mechanized caving faces in lower-lying coal seams, which necessitates a significantly increase in the measures to support surrounding rock material (Zhang et al., 2010; Huang et al., 2013; Xie et al., 2013)."

Jan 1, 2016

By B. Mulcahy, M. Valenta

"The purpose of executing a project in a stagewise fashion is to evaluate all potential options in a cost-effective manner and develop an understanding of the project drivers, thereby minimizing overall project risk to the client. Among the more valuable tools for this exercise are production and financial models that can be used to quantify the sensitivity of the project to the critical parameters.The mine and concentrator used in this case study are located on the Kalahari Copper Belt, which extends from Zambia through northern Botswana into Namibia. This area of Africa has seen very little industrial development and the project will create much-needed employment and development in the region.The success of this project thus far can be attributed to the close cooperation between the geological, mining, and metallurgical disciplines. Regular updates of projected capital and operating cost estimates coupled with project outputs guided the teams in optimizing their various discipline models, ultimately delivering a compelling argument for the execution of the project. Key to the success was the development of a geometallurgical model for the prediction of concentrate tonnage, grade, and recovery for the life of the mine from the mining plan.This paper summarizes the metallurgical findings and the outcome of the various project stages. The development of the model is discussed, as are the challenges faced in developing a suitable metallurgical process route. IntroductionThe Kalahari Copper BeltThe Kalahari Copperbelt, which extends from Zambia across northwest Botswana into Namibia, is considered to be a broad time equivalent of the Central African Copperbelt, with a similar style of mineralization. However, at shallower depths (<25 m), chrysocolla and malachite exist in significant proportions in certain geological areas. As illustrated in Figure 1, the project is located in the Ghanzi-Chobe Fold Belt which forms part of the Kalahari Copper Belt. The Ghanzi Group, which overlies the lowest stratigraphic unit (the Kwebe Formation), consists of three formations, namely the Ngwako Pan, the D’Kar, and the Mamuno Formation (Hall, 2012)."

Jan 1, 2016

By J. N. Van der Merwe

"Platinum is a highly valuable resource, its safe and economic extraction is paramount. The success of platinum mining by the bord and pillar method depends heavily on a comprehensive and dependable pillar design method. Pillars need to be large enough to safely support the load and small enough to avoid loss of resources. A critical evaluation of current pillar design systems used in narrow-reef platinum mining was undertaken using practical experience from a large feasibility-stage platinum exploration project, supplemented by observations from several platinum mines in Zimbabwe. An extensive literature survey was undertaken in order to determine the current status of design systems. Through this approach, the shortcomings of current pillar design systems are highlighted. Areas are proposed for further research to obtain a better understanding on how additional factors influence pillar system stability. The exploration work highlighted how rock mass classification methods can be utilized in determining the overall strength of pillars. Current pillar design systems for narrow-reef platinum mining consider width-to-heightratio (usually with different exponents for width and height) and the strength of the pillar material. However, there are many more important factors that are not considered and which have a bearing on pillar system stability. An in-depth study of these parameters with a view to establish effective narrow- reef platinum mining pillar design systems needs to be undertaken. IntroductionPillars have been used as a means of support since the early days of mining. Pillarsupported mining methods such as bord and pillar require a reliable design system for them to be successful. This paper presents an evaluation of the current hard-rock mining pillar design systems as applied to a practical large-scale narrow-reef platinum mining feasibility study. It is vital to have a dependable pillar design system for economic and sustainable mining. Using an extensive database collected from the project, the pillar strength formulae were tested and several discrepancies noted. This necessitates the establishment of more reliable pillar design systems. In narrow-reef platinum mining, large compressive stresses accompanied by geological and geotechnical factors contribute to pillar instability. A well-formulated pillar design system is required that accounts for such factors so as to minimize pillar failures."

Jan 1, 2017

By S. C. Greeff

At ISCOR the quantitative determination of the structural properties of coke is done with a Leitz-TAS Image Analysis System. A reflected light microscopic image of a coke sample is converted into a binary image and stored in computer memory or on hard disc. By means of mathematical and stereological techniques the system can transform the images electronically. A lightpen can be used to determine the sequence of these operations. TASIC, which is based on BASIC language, is used as the program language on the computer. The majority of the programs are written by the user to ensure satisfactory results for specific studies. The computer controls the whole system, including the movement of the microscope stage, focusing, transformation and measurement of the image and data processing. The computer is also applied for establishing statistical correlations between the structural and other coke and coal parameters as well as for graphics and predictions of the coke structure. Factors affecting the structural properties of coke are discussed and conclusions are drawn.

Jan 1, 1987

By S. M. Spottiswoode

A simple method for the application of excess shear stress (ESS) analysis to the mining of planar reefs is examined. The potential for seismicity associated with mining is expressed as the calculated increase in ESS on a regular grid of points 50 m above the reef, and is compared with observed seismicity around a deep-level, relatively geologicaly-undisturbed gold mine. Thirty regions were studied, involving over 2000 seismic events with magnitudes greater than 1,5 on the Richter scale and associated with almost 2 million square metres of stoping. The total seismicity, measured either as the number of seismic events or as the total radiated energy, corelated more closely with changes in ESS than with ERR. The incidence of rockbursts also favoured the ESS model. Corelation coeficients of around 0,8 for seismicity and ESS indicated that the assumptions inherent in the method used are collectively reasonable. The total seismicity in each region was found not to be strongly controlled by the presence of dykes and faults, although numerous individual seismic events were located close to such features.

Jan 1, 1988

By R Linares

For centuries, diamond&apos;s superlative properties have earned it a reputation as the &apos;dream&apos; material for mankind in its search to create advanced applications. Until recently, this dream has been realized only in the use of diamond for gemstones and abrasive applications where several tons of diamonds are now used on an annual basis. The vision of having large, high quality diamond as part of a broad engineering tool-kit for many diverse high tech industries is now becoming a reality however, with the advent of early stage commercial availability of single crystal and poly crystalline CVD diamond.

Jan 1, 2010

By D. P. Power

The development of an accounting code for the metallurgical industry has been debated for many years. Following the series of tumultuous economic events in the nineties and earlier this century that have affected business, there was much need for legislation to be passed to minimize potential risk. One of the consequences to affect the mining industry was the enhancement of existing geological codes for reporting. In parallel the sponsors of AMIRA have taken the brave step to develop a generic code for metal accounting that embraces the full gamut of industry. In this paper the code will be reviewed in the context of metallurgical accounting as it applies to coal preparation. This paper provides the background for this development and an insight into the mechanism for the debate for the generation of this code. The key elements of the code as it applies to the coal industry are explained but most importantly the key opportunities are highlighted.

Jan 1, 2010

Rock fall accidents continue to be the main causes of fatalities in the mining industry. The occurrence of rock falls in supported stopes implies a failure of the support system. The failure of the support system in turn implies a failure in design. In this paper, ethical issues associated with engineering design are discussed, with particular relevance to stope support design. A risk approach is introduced that will allow designs to be carried out that are compatible with the acceptable risk defined by the mining company management. The implementation of this approach would overcome the ethical shortcomings of current support design practices.

Jan 1, 2007

By R. Layton

Expert Systems Technology (EST) is becoming more and more widespread in both its range of applications and the public interest. It appears to be capable of performing tasks unmatched by other techniques. Within the mining industry a large body of unsolved problems now appear to have a solution. This paper examines the current state of EST both in the context of the history of Artificial Intelligence and current efforts at building mining expert systems. It provides recommendations for those wishing to get involved, and outlines the problems for those who believe that expert systems are capable of anything and everything. The paper also provides a detailed analysis of limitations of current EST that must direct research into more fundamental, commonsense areas than have been extensively covered before.

Jan 1, 1987

By H. M. Friede

Notes on the composition of pre- European copper and copper-alloy artefacts from the Transvaal by H. M. Friede. Ph.D. (Visitor) Seven copper artefacts (five ingots and two ornaments) found at prehistoric sites in the Transvaal were submitted to analysis. All the artefacts showed a high copper content and a relatively Iow level of impurities. A little-known ingot type from the Limpopo Valley (&apos;nail&apos; ingot) is described, and its analysis is given. The analysis of two copper ornaments that come from sites dated to the 5th Century AD. and the 11th Century AD. showed the constancy of the composition of copper articles over long periods. The well-known &apos;Blaauwberg Ingot&apos; was re-analysed, and the results showed that this ingot cannot be regarded as a true bronze. Analytical values for the composition of three brass artefacts from Bambandyanalo (Mapungubwe), Northern Transvaal, are given. Some aspects of pre-European bronze manufacture and brass smelting, and of early metal trade from the East Coast into the interior of South Africa, are discussed.

Jan 2, 1975

By David J. Haddock

On Wednesday, 6th July, 1988, 28 members of the Johannesburg Branch of The South African Institute of Mining and Metallurgy and their guests assembled at the Rand Refinery Sports Club, which is situated within the Refinery complex, to hear Dr Daniel Polnow, General Manager of the Refinery, give a very interesting lecture on the Rand Refinery Complex and its activities. Accounting for gold The South African Institute of Mining and Metallurgy will be holding a 3- or 4-day school in the third week of May 1989 on the topic &apos;Accounting for Gold&apos;.

Jan 1, 1988

By Ri McCrindle

"Analytical Chemistry is moving rapidly towards a concept where technicians have to do no more than press a button and print the result from an instrument that is a featureless ""black box"". In this environment we must ask how much traditional &apos;&apos;wet chemistry"" is still required for undergraduate students.Methods that can be fully automated will become increasingly important. An example of such a method is that of the slurry nebulisation and ICP-OES analysis of precious metal concentrate. Grinding the sample and adding Triton X100 as dispersant, complete analysis time is in the order of 90 min as apposed to the traditional Carius tube method which could take as long as 24 h. For most of the elements studied, the results using ""in-house"" reference material for calibration and as samples as well were within the 95% confidence level. Elements of low concentration in the sample (As, Bi and Se) were not within that level."

Jan 1, 2014

The development of short- and medium-term mine production schedules in isolation from each other has meant that only a local optimum can be achieved when each scheduling phase is carried out. The globally optimal solution, however, can be achieved when integrating scheduling phases and accounting for the interaction between short-term and medium-term activities simultaneously. This paper addresses the task of integrating short- and medium-term production plans by combining the short-term objective of minimizing deviation from targeted mill feed grade with the medium-term objective of maximizing net present value (NPV) into a single mathematical optimization model. A conceptual sublevel stoping operation comprising 30 stopes is used for trialling segregated and integrated scheduling approaches. Segregated medium- and short-term scheduling using separate models achieved an NPV of $42 654 456. The final scheduling approach involved integrating the two scheduling horizons using the newly-developed globally optimal integrated production scheduling model to achieve an NPV of $42 823 657 with smoother mill feed grade. The larger the stope data set, the larger the difference between the two scheduling approaches is likely to be. At the very least, an integrated approach ensures feasibility across the two scheduling horizons, which cannot always be assumed when using a segregated approach.

Jan 1, 2012

By D. F. Malan, R. P. Els

The limit equilibrium model, used in displacement discontinuity codes, is a popular method to simulate pillar failure. This paper investigates the use of physical modelling to calibrate this model. For the experiments, an artificial pillar material was prepared and cubes were poured using the standard 100 mm × 100 mm civil engineering concrete moulds. The friction angle between the cubes and the platens of the testing machine was varied by using soap and sandpaper. Different modes of failure were observed depending on the friction angle. Of interest is that significant loadshedding was recorded for some specimens which visually remained mostly intact. This highlights the difficulty of classifying pillars as failed or intact in underground stopes where spalling is observed. The laboratory models enabled a more precise calibration of the limit equilibrium model compared to previous attempts. Guidelines to assist with calibration of the model are given in the paper. The limit equilibrium model appears to be a useful approximation of the pillar failure as it could simulate the stress-strain behaviour of the laboratory models.

May 3, 2023

By J. van der Merwe, C. Phetolo, V. Matjeke

The mechanical properties and microstructure of AlSi10Mg alloy samples that were printed by selective laser melting (SLM) were studied to determine the effect of processing parameters and building orientation. After printing, the alloy was stress relieved at 250°C for 2 hours. The microstructures were analysed by optical microscopy and scanning electron microscopy (SEM) to determine the alloy phases and distribution. Phase transformation characteristics of the material were evaluated using differential scanning calorimetry (DSC). Mechanical properties were determined by subjecting the XY- and Z-built samples to tensile and nano-indentation testing. The samples from the tensile tests were then used to perform fractographic analysis by SEM. The microstructural properties in each orientation revealed a non-homogeneous microstructure which was characterized by a semi-elliptical tract and fine silicon precipitates, which were found to be softer along the fusion zone. The DSC thermograms revealed that the material underwent two phase transformations during the first heating cycle. The mechanical properties revealed a higher UTS, higher yield strength, and a lower percentage elongation in the Z orientation than in the XY orientation. Fractographic analysis showed that crack initiation in both orientations started from the surface in a brittle manner due to surface flows, and then propagated via microvoid coalescence.

Jul 1, 2021

The imbalance between the coal resources contained in thin seams (1,5 m or less) and the production from them is outlined. It is suggested that an Increase In the exploitation of thin coal seams is necessary, and that drum-type continuous miners can produce a substantial amount of any increase. Continuous miners are employed in a number of mining methods including bord-and-pillar, pillar extraction (stooping), rib-pillar extraction, and shortwalling. These techniques of mining are evaluated with respect to production rates and the cost of extraction for South African conditions included in these evaluations are the types of equipment used to transport coal from the mining machine to the section conveyor belt. Computer simulation techniques are used to generate the required production levels, and interpretations are made of other results from the computer modelling. For thin, coal seams, bord-and-pillar mining utilizing continuous haulage is apparently the most productive and cost-effective of all the methods using the continuous miner. The relative efficiencies of the other techniques of mining and of coal-transportation vehicles are also outlined.

Jan 1, 1984

By C. Botha

The South African democratically-elected government instituted policies and legislation that are intended to bring about change and transformation in the country and have drastically affected different industries, among others, the mining industry. The Mineral and Petroleum Resources Development Act 28 of 2002 (MPRDA) and the Broad-based Socio-economic Empowerment Charter (Mining Charter) were introduced in order to redress previous inequalities and to promote women?s employment in the mining industry. This research evaluates the practical implementation of the MPRDA and the Mining Charter with specific reference to women in underground mining. A quantitative research paradigm was used. Data were collected through a process of a face-to-face interview surveys utilizing a structured questionnaire. The research setting was limited to the platinum-mining industry in the area of Rustenburg in the North West Province. The study population consisted of 195 available women working undergound at the mine. It is clear from the findings that mining companies are facing major challenges in their attempt to incorporate women in underground mining activities. Company policies regarding these issues must be firmly in place; however, the challenge lies in the translation of these policies into practice. In this regard, managers will have to play a leading role in the successful phasing in of women into the underground mining arena.

Jan 1, 2012