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To B. K. Martus I discussed several points raised by Mr Martus in my reply to Professor Krige*. Mr Martus discusses several possible interpretations of optimum South African sales, but in my paper these sales refer to the sales level that maximized the working profit of the whole South African gold-mining industry over the past eleven years. Mr Martus also seems to be under the impression that the paper deals with the future. While there may be references to the future, and some implications for the future may be obvious, the paper deals essentially with the past eleven years.

Jan 1, 1984

By J. P. Gouvea

Back-analysis of two mining-induced tremors in 2011 was used to determine a modelling criterion for the entire Klerksdorp Goldfield (i.e., Vaal Reefs region). At that time, most mining operations in the region were owned by AngloGold Ashanti (AGA) and shared many geotechnical similarities. By 2018 AGA had sold off all its Klerksdorp operations to different mining companies, which continued applying the 2011 modelling criterion. As mining activities became more remote, scattered, and isolated, the extraction of isolated blocks of ground and remnants became increasingly necessary. However, the inherited criterion allowed only minimal or no mining activities at these areas. Keeping in mind that safety is the overriding consideration, an innovative numerical modelling approach, which includes the application of peak particle velocity designs, was developed to provide practitioners in the Klerksdorp Goldfield with a suitable criterion to justifiably and safely mine isolated blocks of ground and remnants. This would not always be possible if a conformist approach was used.

Mar 14, 2024

By T. C. Huber

The southern African region has a high concentration of mineral resources and supplies much of the world?s platinum demand. As a result, the international community watches South Africa to understand the impact of supply on global markets. An analysis of supply certainty and risk plays a key role in the future of growing demand in various sectors. The southern African platinum industry experienced substantial growth in the early part of the 21st century, resulting in bullish forecasts for growth during the period of 2000?2006. However, southern African platinum producers saw a significant drop in production over the following three years as a result of many dynamic factors in operations and the global economy. Between 2006 and 2009 there was a million-ounce shortfall between forecast and actual production. This was raised as a concern at the Fourth International Platinum Conference in 2010 by Stephen Forrest during his keynote address, specifically regarding the lack of understanding in the market of the causes of this shortfall and any action that was being taken to address them. This paper reviews publicly available information in the media and corporate reports and communications for the period January 2006 to December 2009. In addition, several interviews were held with key stakeholders in the industry to provide further perspective. The paper then highlights the main reasons that are reported to have affected the loss in production over the period and discusses the possible implications of the information that the mining industry does and does not disclose regarding platinum supply.

Jan 1, 2012

By J. P. Gous, M. Tangstad, J. D. Steenkamp

In April of 2013 a 48 MVA submerged arc furnace producing silicomanganese was excavated in South Africa. One of the areas excavated systematically was the furnace taphole. The aim was to obtain a refractory wear profile of the tap-hole area, together with affected hearth and sidewall refractory. Subsequently, thermodynamic modelling was applied to quantify the potential for chemical reaction between refractory and slag and refractory and metal in the tap-hole area.

Jan 1, 2014

By S Sondashi, F. J. Chidley, W. A. Grobler

Some of the challenges facing the flotation of base metal sulphides are the opening of new and varying ore bodies as well as maintaining essential skills in plants. Flotation reagent research focuses not only on improving flotation grade and recovery, but also on producing reagents robust enough to cope with changes. A group of recently developed co-collectors, activators, depressants and frothers are described together with a summary of results measured on base metal sulphide ores.

Jan 1, 2005

By B. R. Broekman, D. W. Penman

Discussion by P.J Lloydt Broekman and Penman describe (J.S. Afr. Inst. Min. Metal., vol. 91, Aug. 1991, p. 261) the addition of sodium cyanide and zinc sulphate to the flotation feed at Prieska. They note that for 'safety sake, lime was added to the rod mil to raise the pH to 9,5', and that 'personnel working in the vicinity of the rod mil were required to wear gas masks'. Author reply to P.J. Lloyd We thank Dr Lloyd for his interesting contribution. As he correctly points out, the Prieska float had run with cyanide solutions at pH values of 6,4. In fact, it ran safely for extended period with the pH slightly below 6.

Jan 1, 1991

Careful monitoring of the position of the cave front is essential for well-managed block cave mining. Seismic monitoring systems yield 3-D information about the location of fracturing ahead of the cave. However, because the a seismic gap between cave surface and seismogenic zone is of unknown extent, the cluster of micro-seismicity can only yield an upper bound for the cave height. The large velocity contrast between the fractured rock in the aseismic gap and the broken loose material within the cave can be used by an inversion procedure to find a few simple geometric parameters (such as height of the top of the cave) if a simple 3-D shape?for example a paraboloid?is assumed for the cave. Ray-tracing must be used as the large velocity contrasts cause seismic waves to bend around the cave, but the inversion takes the form of a minimization problem in only a few dimensions and so the computational time is feasible. This technique has been successfully tested on realistic synthetic data.

Jan 1, 2007

By FT Cawood

The latest Draft MPRRB was released for public comment in October 2006. The main purpose of the Bill is to collect royalties at mines developed in terms of new-order mineral rights granted through the MPRDA process. The transition phase stipulated in the MPRDA will be completed by 1 May 2009, on which date mineral royalties will become payable to the state. The royalty rates stated in the MPRRB differ from mineral to mineral and also depend on the degree of refinement. Gold is the subject of this paper, where the royalty rate ranges from 1.5% (for refined gold) to 3% (for unrefined gold) of sales revenue. This royalty is payable regardless of profit, with a maximum 75% relief for loss-making mines. The purpose of this paper is to establish whether or not it would be necessary for gold mines to adjust their mineral reserve statements as a result of this Bill. The methodology is to add the royalty costs stipulated in the MPRRB to the actual quarterly information for the past ten years as reported by the gold-mine members of the COM. The rationale is to investigate the impact this Bill (in its current form) would have had on gold reserves that must be left unmined in the ground because of a higher pay limit. The results of the study point to a significant impact on reserves available for mining with the subsequent shortening of mine lives and retrenchment of workers. Had the MPRRB been effective for the 10 years prior to 1996, it would have resulted in 46 tonnes of gold being sterilised. Stated alternatively, 30 700 workers at COM gold mines alone would have lost their livelihoods.

Jan 1, 2007

The November General Meeting of the Branch was held in the St. Helena Club at 8.00 p.m. on the 17th November, 1970. Mr J. N. Saunders (Chairman) was in the chair. There were also present six fellows, N. A. Honnet, C. J. Isaac, J. G. Kirchner, (Committee Members), J. M. Meyer, S. L. S. Swart and J. W. Wilson; seven members, D. V. Baum, M. de Lange, A. H. Edwards, G. J. G. Emere, E. R. Penny, G. P. Rundle, C. G. J. Vermeulen; six graduates, N. Mayer, H. Miller, E. J. Shillaber, P. J. H. Short, M. H. Smith, T. R. Stromsoe; five associates, M. Andriesse, A. E. Hooper, A. Paschalides, R. L. Solms, W. M. Todd; one student, J. C. Simms and 14 visitors. Apologies for absence were received from Messrs L. O. W. Leimer and G. Y. Nisbet. MINUTES OF THE ANNUAL GENERALMEETING The Minutes of the Annual General Meeting held on the 27th August, 1970, were taken as read. Their adoption, which was proposed by Mr N. A. Honnet and seconded by Mr J. G. Kirchner, was carried unanimously. MINUTES OF THE JULY GENERALMEETING The minutes of the General Meeting held on the 8th July, 1970, were taken as read. Their adoption, which was proposed by Mr C. J. Isaac and seconded by Mr J. G. Kirchner, was carried unanimously. GENERAL BUSINESS Members were advised that no more applications could be entertained for the visit to Western Holdings; they could, however, still apply to visit Welkom Mine and Harmony. TALK The Chairman invited Mr A. Paschalides to deliver his talk on 'Controlled blasting in stopes and new explosives developments'. The presentation proved to be of great interest to the meeting and lively discussion followed the talk. Mr N. A. Honnet proposed a vote of thanks to Mr Paschalides on behalf of all members of the O.F.S. Branch. CLOSURE The Chairman thanked Mr Paschalides for his talk and all present for their attendance, and as this was the last meeting for 1970 he wished all members a Merry Christmas and a Happy New Year. He declared the meeting closed at 9.30 p.m.

By H. C. Van Der Merwe

In the 21st century, dynamic, accurate digital 3-D geological models are essential to the pursuit of safe, efficient and profitable mining. This is particularly true for the deep-level underground mines in South Africa. The Sirovision® solution is a collaboration project between the Australian CSIRO (Commonwealth Scientific and Industrial Research Organisation), Datamine Software Ltd. and AngloGold Ashanti Ltd (AGA). The purpose of the project is to provide a fully integrated digital rock face imaging, geological mapping and modelling system for the AGA gold mining operations. The CSIRO-developed Sirovision® Stereo Camera Rig (SCR) consists of two digital cameras, alighting system, a laser guidance system and image processing software. The imaging system works on the principles of photogrammetry, i.e. overlaying of two 2-D images with a central focus point, with mathematical algorithms extracting 3-D information from the 2-D image pair. The output from matching several image pairs is a computer-generated, full 3-D, virtual copy of the mining excavation. The image resolution and relief ares of sufficient quality to distinguish different rock types and structural contacts. Functionality within Datamine Studio3 is used to add geological intelligence to the 3-D images provided by Sirovision®. The geologist identifies and ?draws? lines representing geological features directly onto the image. By utilizing the inherent ?topography? of the 3-D image, the software is able to convert the lines into 3-D surfaces, ready for use in the 3-D geological model. Subsequent to promising underground test results from AGA?s Sunrise Dam Gold Mine (SDGM) in Australia and other mining operations worldwide, it was decided to test the Sirovision® system in the South African deep-level gold mines. The first underground tests at Moab Khotsong Mine began in January 2009. The objectives of these tests entailed the capturing of 3-D images of selected development ends, mapping of geological features onto the 3-D images and integration of the mapping data with the 3-D geological model. Some downsides have cropped up during the feasibility testing, related to practicality of the SCR for acquisition of 3-Dimagery in the deep-level underground operating environment. These constraints will have to be addressed prior to operational implementation. Facing such difficulties is not unusual when attempting to implement new technology in such a challenging working environment and testwork is still in progress at the mine in order to prove the concept of using this technology in a Witwatersrand underground gold mine. The great advantage of the Sirovision® solution is that it offers the geologist the opportunity to work remotely on a 3-D virtual copy of a mining excavation, without the heat, humidity, hazards and time constraints associated with physical mapping in an underground workplace.

Jan 1, 2009

By N. Madani, S. Abulkhair

In multivariate geostatistics, it is common to have different types of complexities between variables of interest. In this context, an inequality constraint is an example of complex bivariate relationships. Unfortunately, traditional co-kriging and co-simulation algorithms cannot reproduce this type of bivariate complexity, leading to the overestimation of disturbing elements. This paper proposes a new algorithm based on a hierarchical sequential Gaussian co-simulation framework, integrated with inverse transform sampling, to model inequality constraints between variables. First, the proposed methodology's validity was evaluated by applying it to a real case study from an iron deposit, with an inequality constraint between iron and aluminum oxide. Then the simulated results were compared with a conventional hierarchical co-simulation algorithm to investigate the effect of inverse transform sampling on the quality of the co-simulation. The results showed that the proposed algorithm can reproduce an inequality constraint between variables.

Sep 1, 2021

By T. G. Pedro, Q. Gonzalo, R. E. Roberto

Anionic surfactants, such as oleic acid and sodium oleate (OLE), and cationic surfactants, such as dodecyl amine-hydrochloride (DDA), are used as flotation collectors of spodumene. However, recovery is poor even if activating ions are used because gangue minerals are also activated. Some reports demonstrate that OLE/DDA mixtures act as a selective collector to enhance spodumene recovery. From mostly macroscopic tests, it has been argued that anionic OLE and cationic DDA form electroneutral complexes, which are adsorbed on the mineral surface through chemisorption; however, no molecular evidence has been presented. Therefore, the adsorption mechanisms of the collector mixtures remain mostly unknown. It seems necessary to first study the behaviour of these surfactants confined in salt solutions, to determine auto-associations when they are pure and cross-associations when mixed, the transition from monomers to micelles, and the structure of the micelles and the effects of pH, temperature and concentration. In this paper, ab initio calculations are first used to determine the surface charge distribution of OLE and DDA separately. Then molecular dynamics simulations are used to determine the conformation, aggregation, and diffusion of these pure and mixed surfactants in freshwater and saltwater with the ionic strength of seawater in a pH range. In particular, it is interesting to determine the various associations that result in mixtures of both surfactants and the impact of alkali and alkaline earth metal cations on the structures formedp. Cations influence the order of the structure and orientation of water dipoles, reducing the mobility of water, ions, and surfactant molecules. This knowledge is critical to improve the molecular understanding of the adsorption mechanisms on minerals. Keywords: Computer simulation, molecular dynamics, flotation, collectors, saltwater

Jan 1, 2020

By E. Isokangas

A mine is essentially a series of operations, including drilling and blasting, crushing, milling, flotation, and leaching, that are interconnected and therefore interrelated, with the performance of one operation affecting the performance of another. Optimizing each stage separately without considering the whole system often causes potential economic benefits and energy savings to be missed. However, the PIO methodology is a thorough approach which considers these individual process activities within the context of the whole process. The basic principle is to optimize the process as a whole, rather than each process step in isolation from the others. Metso?s Process Technology and Innovation (PTI) group offers a global consulting service for the mining and construction industries. A significant amount of this consulting work involves process integration and optimization (PIO) studies. When conducting a PIO study, every aspect of the process is considered. In addition to drilling and blasting, transportation, handling and storage, crushing, screening, grinding, flotation, separation, and recovery, other aspects including equipment utilization and energy consumption and even greenhouse gas emissions are also included if necessary. In a PIO project, it is very important to understand what type of material is being processed at any point in time. That is, which domain or domains is the material part of? This is necessary in order to observe the effect of different ore sources (and the blending of sources) on concentrator performance. Linking the ore from the pit to the concentrator required the development of an ore tracking system. As a result, PTI developed a radio-frequency based material tracking system called SmartTag?. This system allows tracking of ore from its source through blasting, run-of-mine (ROM) pads, crushers, intermediate stockpiles, and finally into the concentrator. Using the SmartTag? system, definitive correlations can be made between the performance of the plant and the plant feed characteristics, including the domain from which the feed ore originated. Since its commercialization in 2007, SmartTag? has been used in the majority of PTI?s consulting projects and several permanent systems have been installed worldwide1. Successful applications of the SmartTag? system have encouraged development to allow the system to be used in a wider variety of plants, in particular plants with finer crushing and screening stages. This paper describes how the SmartTag? system is being utilized by PTI and the benefits being gained by its use in PIO projects, as well as presenting some case studies.

Jan 1, 2012

By N. V. Moraka

Calls for transformation in the mining sector are legislated. Whilst the composition of boards in terms of gender diversity and equal representation has improved, little is known on how women directors experience boardrooms. This research investigated the experiences of South African women in male-dominated mining boards. It questions why women remain marginalised in boardrooms, even when they are qualified as the men in their respective fields. The experiences of South African women on male-dominated mining boards were investigated by means of a multiple case study using a qualitative research methodology. Interviews were conducted with 16 women and 12 men serving across six JSE-listed South African mining companies. The findings show that irrespective of their qualification and experience, women,s, contributions are often ignored, and they are assigned to more social roles. Regardless of race, all women experienced gender stereotyping. Strategies are required to ensure that board cultures embrace female talent, where women can effectively contribute to decision-making and maximize their talent. It is argued that gender and identity should be studied in relation to post-colonial history in African countries. Women have multiple, varying identities, and their experiences require a unique investigation that would enable strategies to overcome barriers, through the implementation of an appropriate diversity management programme.

Feb 12, 2024

By M. Splaine, W. Davison, D. C. Atkinson

"Since 1964, Nchanga Consolidated Copper Mines, Ltd., has been developing and using production scheduling methods for optimizing its metallurgical operations in the short term (up to one year). Medium-range metallurgical planning has been possible only by successive evaluations of a single-year L.P. A modified version of Rosenbrock's direct search technique has now been developed to allow multi-year optimization of both mining and metallurgy for medium-range planning. The modifications to the search technique have produced a marked increase in computational efffciency for this heavily constrained problem in many variables and the system is a usable planning tool, given a reasonably powerful computer. The plans are 'optimum' in the sense that they yield the maximum present value of the operations.Each of the resulting five-yearly mine plans forms the basis for further detailed metallurgical evaluation by the established production scheduling system."

Jan 1, 2014

By W. E. Stumpf

"SynopsisSouth Africa recently announced a resurgence in its commercial nuclear power programme. The implications for the development of the necessary high-level manpower within South Africa’s tertiary educational system and its national research and development (R&D) capacity in materials science and engineering, as well as in other engineering disciplines, are placed into perspective. An organized national process of developing this manpower by moving away from the previously high-risk and costly ’large programmes’ to rather a selection of ‘small and better’ research projects and a redefinition of what constitutes ‘nuclear materials’ are proposed as parts of this strategy.IntroductionSince 2008, and more particularly in 2014/2015, South Africa has woken up to the fact that significant steps need to be taken to ensure sufficient electricity generating capacity for the future, even beyond the coal-fired stations at Medupi and Kusile currently under construction. It is, therefore, encouraging to see some active large-scale wind farms in the Eastern Cape near Jeffrey’s Bay, in the Couga area, and others in the Western Cape already in operation. In addition, many solar energy projects are also progressing from the small localized scale to larger programmes in the Northern Cape, which may contribute some capacity on a national basis. South Africa needs to tap into its renewable resources of wind and solar much more, but will these projects solve the country’s long-term industrial needs? Unfortunately not. One cannot run mines and trains on solar cells. Industry needs reliable baseload capacity, and with very limited easily accessible hydrocapacity this leaves really only coal, possibly natural gas, and nuclear power as options. South Africa’s current over-reliance of about 90% on coal–fired power, however, places it in an internationally vulnerable position, and diversification into a more equitable energy mix should be a national priority for the medium to long term. South Africa cannot significant climate change confronting the human race, as the IPCC cautioned in 2013, and will have to adjust its future energy reliance to a more balanced combination of sources."

Jan 1, 2015

By I. Ashmole

The dimension stone industry is not widely known or appreciated within the mainstream mining industry. This is in spite of the fact that the industry has grown at an average of over 7% per annum since 1980, and is estimated to now have a global turnover in excess of US$ 60 Billion per annum. Production technologies, particularly in the developed world where labour costs are high, have developed rapidly over the past two decades. Aligned with this, there has been a significant trend in adoption of a more professional mining approach in the exploration for and operation of dimension stone quarries. In fact, in the experience of the authors, mining a dimension stone deposit successfully if often more challenging from a mining engineering point of view than many conventional surface mines. This paper gives an overview of the industry and then proceeds to discuss best practice in exploration for dimension stone and to outline the latest technologies applied in mining of dimension stone. These technologies are varied and the specific combination of technologies applied in any given quarry is determined by both the physical properties of the material as well as the influence of geology which significantly impacts on the recovery of saleable material and hence the economics of the quarry.

Jan 1, 2008

By H. Cevizci

"Numerical simulation of the plaster stemming method (PSM) was performed and compared with the conventional drill cuttings stemming method (DCSM). Many earlier in situ tests have proved that PSM can use the blast energy more efficiently than DCSM. Despite PSM generating more blast vibrations, it has advantages over DCSM such as better fragmentation and lower cost per unit volume of rock blasted. In this study, numerical simulation with Autodyn software using a 2D tool was employed to prove the efficiency of plaster stemming by comparing parameters such as pressure, Y-velocity, Y-force, internal energy, acceleration-Y, and compression. For example, the maximum pressure attained at the top of explosive column was 7 395 MPa for DCSM whereas it was as high as 11 945 MPa for PSM. Most of the computed parameters were significantly higher in PSM than those obtained for DCSM. This paper is the first study elucidating the efficiency of PSM by numerical simulation. It is concluded that PSM can save substantial amounts of money and effort. IntroductionThe stemming of blast-hole collars in surface mines with an inert material redirects blasting energy to the rock more efficiently, thus the blast-induced energy is utilized more effectively in breaking rock. With proper stemming, the gases should not escape due to loose stemming material. More efficient stemming with better confinement therefore increases the blast fragmentation. In addition, the distance of scatter is increased, giving rise to a looser rock pile that can be more easily loaded and transported. In order to improve the performance of a blast, stemming is used to help maintain the gas pressure over time (Konya and Konya, 2018). Proper stemming has been shown to increase the explosive efficiency by over 41% (Snelling and Hall, 1912).The most common stemming material in open pits and quarries is drill cuttings because of their ready availability at blast sites and the drill cuttings stemming method (DCSM) is a low-cost method. However, it has a major disadvantage in that dry drill cuttings eject very easily from blast-holes during an explosion, thus a great percentage of the blast energy is wasted and lost to the atmosphere. Cevizci (2012, 2014, 2013, 2017) studied blasting parameters in open pits and obtained better results with the plaster stemming method (PSM) in many limestone, basalt, and clay quarries. Moulding plaster is preferred for stemming because of the fast hardening time of 25–30 minutes."

May 1, 2019

By A. Tello

Variography was introduced by Dr. Pierre Gy to monitor a process, in the sixties. Later on, Francis Pitard extended this concept, building a complete system of variographic controls for different applications. Nevertheless, the existence of information about its use as a way to effectively control plants has been limited. There are infinite areas where variography and chronostatistics can be used. In this paper, two different cases related to gold and silver recovery, through well known but complex metallurgical routes are studied. The use of effective management of process variability software (EMPV) has shown to be a suitable solution to clarify problems at the plant and, consequently, a solution to the encountered problems has been proposed. Chronostatistics is like opening a new world to the metallurgist, making the process variability speak in a more comprehensive and in depth way. Once the ore has been extracted from the mine, sampling is necessary at each sequence of the metallurgical process involved. As a first example, leaching of the ore with cyanide in agitated tanks is another case of a complex metallurgy. The aim of the process is to know about residual values in the tailings in order to optimize process. As a second example, leaching of gold and silver in ore heaps, has to be optimized in terms of time, reagents consumption and, of course, in predicting a reasonable recovery. This last issue appears to be crucial. After cyanide leaching at the heaps, a carbon in columns process is involved, where there are a series of carbon loaded columns that are submitted to a dynamic process of load and unload, to finally deliver an enriched solution to the precious metal electrowinning plant. In both cases, variography has been a good approach to show metallurgists ways to improve the operation.

Jan 1, 2009

By N. F. Mashinini

Optimization of current control systems, proper maintenance and efficient training of personnel are recommendations made to control the amount of dust that underground employees are exposed to on a daily basis in the coal mining industry. This dissertation forms as part of Sasol Mining?s commitment to protect the health and safety of their employees by suppressing and controlling dust at their mines. This study aims to understand the relationship among mining processes, exposure to dust and dust suppression control measures. The research phase of the project was done at the Sasol Mining Secunda complex where underground visits were undertaken to investigate current control systems and also new systems that are being implemented by Sasol Mining. This work was important because it helped determine the sources of dust underground and also to identify the shortcomings of current control systems and to test the efficiencies of the new systems implemented at Sasol Mining. The most important result of the research work was the identification of which underground operators were exposed the most to dust as this assisted in designing a dust suppression system for the areas where these operators worked. The main conclusions of this study are that the current control systems are sufficient for controlling dust and ensuring dust compliance if they are used efficiently and maintained properly.

Jan 1, 2008