Search Documents

The October General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 21st October, 1970, at 4.30 p.m. V. C. Robinson (President) was in the chair. There were also present 25 Fellows, including J. K. E. Douglas, Prof D. D. Howat, D. G. Maxwell, Dr R. E. Robinson, P. A. von Wielligh (Council Members). D. Ayres, G. Burrow, E. H. D. Carman, D. L. Carson, M. E. E. Douglas, S. A. Finney, W. R. Flook, A. J. Freemantle, W. A. Gilbert, E. B. Gordon, B. W. Gray, J. M. Jacobs, P. H. Kitto, C. H. Kruger, Dr P. J. D. Lloyd, D. G. Malan, W. Pilkington, W. G. Pyne-Mercier, K. S. Rae, W. T. Ruhmer, D. J. Tutt and D. T. Watt. Seven Members, including E. J. Dominy, S. I. du Preez, L. V. Grobler, D. R. Lings, G. D. Louw, J. S. A. Oelofse and O. B. Prentis. Fifteen Visitors, including J. R. Coppin, Dr A. Faure, P. E. Franzl, G. P. Hart, D. van Heerden, A. W. Hunt, A. R. F. MacDonald, B. G. Meyburgh, P. H. Radcliffe, J. M. Shirley, T. H. Tunley, A. D. Vellema and R. E. Wheeler. Secretary, D. C. Visser. Total present: 49. OBITUARIES The President: "It is my sad duty to announce the death of the following: Sir George Arthur Davenport, Honorary Life Fellow, who joined the Institute in 1930 and passed away on 17th September, 1970. The late Sir George was also, for many years, our corresponding member for Rhodesia. Andrew Malcolm Carmichael, Associate, who joined the Institute in 1944 and passed away on 22nd August, 1970. Cyril John Douglas Veal, Life Fellow, who joined the Institute in 1929 and passed away on 27th August, 1970. As a mark of respect to the memory of the deceased and in sympathy with the bereaved I would ask you all to rise and observe a few moments' silence." CONFIRMATION OF MINUTES The President: "May we confirm the minutes of the Annual General Meeting held on 26th August, 1970, and the minutes of the monthly general meetings which were held on the 20th of May and the 17th of June, 1970, as published in the August Journal." Agreed. MEMBERSHIP The President: "I have much pleasure in announcing that the names of the undermentioned candidates, having been published in accordance with By-Law 5.2.2., Council has elected them to membership of the Institute in the following grades: Members: Nikolaos Lalakakis, Gordon Phillips Rundle. Associates: Henry du Preez, James Robert Forbes, Johannes Stephanus Albertus Oelofse, Casper Vorster van Heerden. Graduates: Michael Harold Crosbie, Graham Robert Wallis Walker, Gary Walker Braithwaite. Students: Mohammad Ali Kazemzadeh, Gerhardus Petrus Benade. APPLICATIONS FOR TRANSFER From Graduate to Member: James Wormald. From Student to Graduate: Peter John Cook, Pieter Willem Greeff. "I welcome the newly elected members to the Institute and congratulate the members who have been transferred to a higher grade." PAPER FOR PRESENTATION The President: "This paper is entitled 'The Design, Erection and Operation of a Purlex Plant at Buffelsfontein Gold Mining Company Limited'. It is presented to the Institute by Mr B. G. Meyburgh, a visitor to our Institute. He is a graduate of the University of the Orange Free State and is the Uranium Plant Superintendent at Buffelsfontein and he, therefore, is in a very strong position to describe this very excellent job which is being done as he has been associated with this plant from the inception." After the presentation of the paper the President said: "Gentlemen, the paper you've heard from Mr Meyburgh is a very concise and interesting account of an important piece of work, and I think the title is so completely descriptive of the subject, which is admirably set out in the paper which you have heard. You probably haven't all had the opportunity of reading it, but you very soon will. I found it interesting to note that the results predicted were surpassed in the operation of the plant to date. The actual results obtained are significantly good, I think. Any process which, in this country, increases production and decreases costs, is to be welcomed, particularly when it is so necessary for South Africa almost to bend over backwards to utilise every avenue available in order to increase the scope of the production for overseas' markets, of her metallurgical and mineral potential. In lighter vein-and there is no reason why we should always be so serious-I am glad to see that, in a scientific journal like this, such words as the American word 'crud' which I have been picked out about so often, because my grandchildren use it, is now given an aura of respectability. Thank you very much, Mr Meyburgh, for an interesting paper. We have a long list of contributors, and I am not going to waste any more time. I am going to call on Mr Tunley of the N.I.M. for the first contribution." T. H. Tunley, P. de Bruyn (read by A. D. Vellema), E. J. Dominy, E. H. D. Carman, A. R. F. MacDonald D. C. Streicher (read by P. H. Radcliff), Dr A. Faure and Dr P. J. D. Lloyd then contributed to the discussion. (This discussion will appear in a later issue of the Journal.) The President: "I wish to thank members and visitors for their attendance, and now declare the meeting closed." The meeting closed at 6.05 p.m.

By M. Hao, S. Hu, X. Lyu, M. Lian, C. Anning, G. Yao, Z. Wang

The results revealed that the pozzolanic activity of the gold mine tailings and their main mineral phases improved by mechanical activation. Under the same activation conditions, the activated mica powders possessed the highest pozzolanic activity index, followed by the activated feldspar, and the activated quartz exhibited the lowest pozzolanic activity index. The addition of calcium oxide promoted the formation of amorphous C–(A)–S–H gel for all paste samples, and stratlingite and hydrotalcite were observed in calcium oxide activated mica paste. The addition of natural anhydrite promoted the formation of ettringite for the pastes of calcium oxide activated aluminosilicates materials (gold mine tailings, mica, and feldspar). Furthermore, the pozzolanic activity indexes of the mechanically activated gold mine tailings and their main mineral phases were tested to be qualified for use as supplementary cementitious material in cement. This paper provided an innovative approach for recycling gold mine tailings as supplementary cementitious materials in cement, which would be environmentally friendly and cost-effective. Keywords: Mechanical activation, gold mine tailings, supplementary cementitious material, hydration properties, pozzolanic activity

Jan 1, 2020

By R. G. Diale, H. R. Chauke, T. M. Ledwaba, P. E. Ngoepe

FeCo alloys play an important role in soft magnetic materials with a wide range of technological applications due to their high saturation magnetization and Curie temperature. However, these alloys have low ductility at room temperature. The ductility can be improved by the ternary addition of elements such as V. A density functional theory supercell approach was used to generate B2 Fe50Co50-xVx (0 ≤ x ≤ 50) structures and the properties were evaluated at different atomic percentage compositions to determine the ductility at room temperature. The structures were fully optimized to obtain better equilibrium ground-state properties such as lattice parameters and thermodynamic properties for both binary and ternary systems. The stability of Fe50Co50- xVx was evaluated from the heats of formation, elastic properties, and phonon dispersion curves. Furthermore, magnetic strength was evaluated from magnetic moments. It was found that all structures are thermodynamically stable due to the negative heats of formation. The calculated Pugh’s ratio and Poisson’s ratio confirm that alloying with V effectively improved the ductility. It was also found that Fe50Co50-xVx showed a positive shear modulus for the entire concentration range investigated, in agreement with phonon dispersion curves. The ternary addition of V to the FeCo system resulted in reduced magnetic strength due to a decrease in magnetic moments. These findings reveal that B2 FeCo-V alloys can be used as components and actuators for the automotive industry.

Jun 10, 2024

By P. L. Moolman

An approach to the design of a tailings disposal system is presented using an example from a platinum project on the eastern limb of the Bushveld Complex as a base case. The design is driven by two inputs: namely, maximizing water recovery and minimizing power cost, expressed as cubic metres and kilowatts per ton of solids deposited on the tailings storage facility respectively. The approach considers low-, medium-, and high-density platinum tailings and uses material-specific aspects such as thickening and rheology to determine the most economical option. An analysis based on direct capital and operating cost (water and electricity) shows that the medium-density scenario results in the lowest total cost per ton of tailings deposited, even though this system results in the highest electricity consumption per ton of tailings deposited. As the cost of water and electricity is likely to increase in the future, the higher-density tailings disposal options become more economical, with the paste option the preferred option.

Jan 1, 2012

By J. Mulenshi, J. Rosenkranz, P. Khavari, S. C. Chelgani

The geometallurgical concept has mainly been applied to primary ore deposits, starting from ore characterisation to the economic optimisation of the mining operation. However, as primary ore resources are becoming depleted and lower in grade, alternative sources need to be explored and a question of adaptability of the geometallurgical approach to the secondary resource repositories arises. The particle size distribution, chemical and mineralogical compositions of the Smaltjärnen historical tungsten tailings from physical separation in Yxsjöberg, Sweden were studied using drill core samples collected from different locations within the tailings repository in order to assess the amenability of the tailings to reprocessing. The tailings are dominated by the –600 to +149 μm particle size fraction. This fraction contains most of the elements of interest (W, Cu, S, Sn, Zn, Be, Bi and F) hosted by scheelite, chalcopyrite, pyrrhotite, cassiterite, danalite (both Zn and Be), bismuthinite and fluorite, respectively. The particle size distribution and mineralogical composition vary across the repository, suggesting a possible existence of geometallurgical domains, which require further assessment to evaluate metallurgical performance. Keywords: Historical tailings, tungsten, scheelite, geometallurgy, characterisation, mineralogy, reprocessing

Jan 1, 2020

By N. P. Mabasa, N. Naudé, A. M. Garbers-Craig

An improved methodology is presented for assessing the economic feasibility and effectiveness of recycling MgO-C and Al2O3-MgO-C refractory bricks, which are widely used in the steelmaking industry. Since approximately 28 Mt of refractory bricks are discarded each year, it is logical to recycle them. When furnaces and ladles are relined, the spent refractory bricks become mixed up, and need to be sorted before recycling. This study examined the use of a hand-held X-ray fluorescence analyser (HH-XRF) to distinguish between spent oxide-based and oxide-carbon-based refractory materials, with special emphasis on spent MgO-C (MC) and Al2O3-MgO-C (AMC) bricks. HH-XRF analysis was conducted on 18 oxide-carbon refractory bricks as well as on MgO-chromite and bauxite-based refractories. X-ray diffraction, reflected light optical microscopy, and scanning electron microscopy with energy dispersive spectroscopy were used to characterize the MgO-C and Al2O3-MgO-C bricks to confirm the accuracy of the HH-XRF analyses. This study also underlined the importance of calibrating the HH-XRF analyser for the refractory bricks to be sorted. The HH-XRF was successful in distinguishing between the different oxide-carbon-based refractory bricks both before and after cleaning. This result is important as it proves that HH-XRF provides a method whereby spent MC and AMC bricks can be sorted quickly and reliably.

Jan 26, 2023

By M J. Daniel

The diamond industry is no newcomer to High Pressure Grinding Rolls (HPGR) as it has used the technology for more than 20 years, predominantly in secondary crushing and recrushing roles. In fact it could be argued that the diamond industry has led the way for the wider minerals industry to consider its application. In existing conventional secondary cone crushing applications, large valuable diamonds are" won" through meticulously managing the recovery process within defined particle size ranges. Conventional crushers operate with relatively large closed side settings, but have the potential to damage diamonds by making direct contact with the sides of the crusher. Cone crushers also result in steep product size distributions that run a high risk of losing many of the smaller, unliberated but more abundant diamonds from the rock. This current comminution paradigm of particle size reduction management results in recrushing processing applications or plants where HPGRs are often used.

Jan 1, 2010

The Barrick North Mara Mine and the Advanced Systems Group at SGS Minerals collaborated on the implementation of a grinding expert system for the control and optimisation of a single semi autogenous (SAG) mill. Over the last 5 years, grinding expert control has gained wide acceptance by mineral processors. In this paper, two key factors for success are highlighted: the adaptability of the software tools and the interaction with site personnel. Created with SGS?s MET expert console (MEC) toolkit, and running on Gensym?s G2 real time inference software, the North Mara expert logic has been set up to keep a steady and on spec leaching feed slurry while striving to maximize throughput. Leach feed stability was achieved by standardizing operating practices across shifts; a result of successful collaboration with site personnel in developing a consistent control strategy. The strategy maintains the SAG load and power draw in an optimised range by manipulating SAG feed rates and inlet water flow. The project life-cycle was slightly longer than average due to site specific constraints. One of these was the high turnover rate of site?s workforce during the project, coupled with the availability of key staff on site due to the fly in fly out work roster. These constraints called for different, and innovative ways of project commissioning and hand-over. This paper describes details of the control solution, its implementation as well as results and conclusions.

Jan 1, 2009

By I. Soto, E. Córdova, A. Anani

The new caving megaprojects that are planned to go into production in the next decade have scheduled horizontal developments at very high rates, which are difficult to achieve. Research has been conducted that seeks to model the construction times for underground developments to determine the feasibility of achieving the planned rates. However, these previous attempts do not consider all the operational aspects that make up the mine development cycle. Here, we present a discrete event simulation (DES) model that individualizes each unit operation of the development cycle to determine the construction rates that new projects will be able to attain. The developed model was applied to the New Mine Level (NML) of the El Teniente Division (DET). The results indicate that it would be impractical to achieve the advance rates scheduled in the original plans if the unit operations of the mine continue to be executed using the status quo. The metres developed after six years in the sections analysed can be significantly improved by changing the maintenance strategy for the equipment (457 metres increase), orepass availability (194 metres increase), and the initial planning sequence (1 598 metres increase). It is recommended that the mine implements a flexible maintenance strategy, defines a strategy to ensure and increase orepass availability to contractors, and makes use of current simulation tools for a more robust development sequence planning.

Oct 1, 2022

By Richard F. Link, Jr. Koch

"A mathematical simulation model has been devised to guide the layout of surface or underground mine workings, drill stations, and drill holes that are established in order to search for tabular ore bodies. The ore bodies may be contained within veins, sedimentary beds (including reefs), or other tabular structures.Programmed for a time-shared digital computer, the model contains both stochastic and deterministic variables. Stochastic or natural variables include the number of ore shoots and their sizes, orientations, locations and values. Deterministic or controllable variables include (i) locations and costs of workings (for underground exploration); (ii) drill station locations and costs; and (iii) drill hole azimuths, inclinations, lengths and deflections (if any).For various assumptions about the natural variables, the model is run while the controllable variables arc changed deliberately. Thus, layouts are devised to determine the percentages of the total number of assumed ore shoots found at different costs. In order to choose among the various layouts, cost-effectiveness measures are calculated."

Jan 1, 2014

By P. Pięta, A. Surowiak, T. Niedoba

In a flotation process of copper ore three factors were measured: copper grade in concentrate (β), copper grade in tailings (J) and recovery of copper in concentrate (e). The experiment was conducted by means of the Jameson cell. The factors influencing the quality of the process were particle size (d), time of separation (t), type of the collector (k) and dosage of the collector (s). The considered vector function was then [β(d, t, k, s), J(d, t, k, s), e(d, t, k, s)]. Optimisation achieved was based on determining the values of the adjustable factors (d, t, k, s). The goal was to obtain the highest possible values of functions β and e (maximum) and the lowest possible values of function J (minimum). To this purpose the taxonomic methods were applied. Keywords: Flotation, copper ore, lithology, flotation agents, particle size distribution, taxonomic methods

Jan 1, 2020

By M. S. Shishvan, S. Klerkx, J. Sattarvand

The inaccurately drilled blastholes from the planned locations cause changes in the spatial distribution of explosive energy; some areas of the blast may receive a surplus of explosive energy, while others see a reduction. This results in less uniform fragmentation, reduces the efficiency of mining operations and increases costs. Additionally, it can lead to slope stability issues, flyrock, and uneven benches. To mitigate these problems, this study attempts to reduce differences in the explosive energy distribution (EED) through an optimization approach that adjusts the height of explosive columns in blastholes. Two optimization algorithms, the Genetic Algorithm (GA) and Tabu Search (TS), are tested. The latter is preferred for its local search neighbourhood strategy that gives superior computation times. Applications on different blast patterns result in improvements of 0.53–1.54%, or 2.14–3.94% when only the affected blocks are considered.

Sep 1, 2021

By K. Karaman

This study investigated the effect of surface roughness on Schmidt rebound hardness (RL). Four different test surfaces of rock samples were studied: natural, ground, cut surfaces, and core samples. There was significant variability of standard deviation based on the RL on the natural surface, which indicated high roughness of the rock surface, whereas surface polishing caused a significant decrease in standard deviation. ISRM and ASTM methods were compared to estimate unconfined compressive strength (UCS) for different testing surfaces. RL obtained from the cut surface was found to be more reliable than those obtained from other testing surfaces for the prediction of UCS; however, regression and ANOVA analyses revealed that the ISRM method gave a more accurate UCS estimation of rocks with highly rough surfaces. It was also shown that RL values obtained from a cut surface were significantly higher than those obtained from core samples. Therefore, a comparison between RL values obtained from core samples and cut surfaces was made based on previous studies. This study statistically showed that estimated UCS values are not statistically significant if Schmidt rebound tests are not performed on similar surfaces. In addition, the mineral grain sizes of the studied rocks, different testing surfaces compared with those in literature, and standard deviation from RL are evaluated and discussed. The Schmidt hammer technique is a rapid, inexpensive, and straightforward method for estimating UCS for preliminary assessment; however, roughness of the surface should be eliminated if variations are shown in the surface rebound hardness.

Apr 14, 2024

By Mark Dangerfield

[Power-Point Presentation]

Jan 1, 2005

By M. Borowski, N. Szlazak, D. Obracaj

Methods of research and control of the intensity of gas inflow to undersoil layers, after the mines were abandoned are presented in the paper. Gas migration causes them to penetrate to lower storeys of buildings and earthen structures being a menace to people's health and life. The results of measurements of gas concentration in undersoil layers, gas emission to atmosphere and their accumulation in buildings on the territory of closed down mines are presented.

Jan 1, 2003

By P. C. Pistorius, M. P. Maphutha, J. D. Steenkamp

Advanced high-strength steels (AHSS) are sophisticated materials being developed by the steel industry to mitigate challenges related to the performance of motor vehicles. To meet the requirements of AHSS, the ferromanganese alloys (FeMn) utilized in the production of the steel are required to contain acceptable levels of unwanted impurities, i.e. P, S, N, H, and C. The focus of the current study was to investigate dephosphorization of ferromanganese to produce a low-P alloy that could be effectively utilized in the production of AHSS. The study involved conducting laboratory-scale testwork to study the efficiency of CaO-based slag systems to dephosphorize FeMn alloys. The addition of Na2O, CaF2, and BaO to MnO-CaO-SiO2 slag was considered. The test work was carried out in a 25 kW induction furnace at temperatures of 1350°C, 1400°C, and 1450°C. The P partition coefficient (Lp) remained small at <1, which is an indication that dephosphorization had not been achieved. The baseline slag, comprising 40%CaO-40%SiO2-20%MnO, reported higher Lp values. Addition of Na2O and CaF2 did not show any further benefit. Substituting half of the CaO by BaO, resulted in similar Lp values to those of the baseline slag under conditions of 1350°C and 1450°C at 30 minutes. In summary, based on the Lp values obtained, the conditions investigated with the CaO-based slags appeared to have been unfavourable for dephosphorization of FeMn alloys, as most of this impurity element remained in the alloy.

Sep 1, 2021

By Y. Qin, X. Fu, T. Qi, H. Tang

"The FASTMELT ® process was developed as an alternative to blast furnace ironmaking; in this process, high-quality molten iron is produced using direct reduction followed by high-temperature slag/metal separation. In this study, iron recovery and phosphorus removal from oolitic highphosphorus haematite using the FASTMELT® process was investigated. The performance of two reducing agents, coal and wood char, was compared. Direct reduction experiments indicated that with optimized reductant addition, the ore-char and ore-coal briquettes attained metallization values of 82% and 78%, respectively, and residual carbon contents of 0.24 and 2.35%, respectively. The slag/metal separation experiments revealed that molten iron containing 0.41% phosphorus and 0.021% silicon (by mass) was produced from optimally reduced ore-char briquettes, and molten iron containing 0.78% phosphorus and 0.91% silicon from optimally reduced ore–coal briquettes. The study indicates that carbonaceous materials with high CO2 reactivity are suitable for use in the FASTMELT ® process for phosphorus removal and iron recovery from oolitic high-phosphorus haematite. IntroductionIn China, the general depletion of iron-rich mineral reserves has led to many efforts to exploit low-grade and refractory ironcontaining resources for ironmaking (Liu et al., 2014). The efficient utilization of the highphosphorus oolitic haematite resources in central China has received considerable attention. The available resources of this material total approximately 3.0 billion tons. The oolitic units in the ore exhibit an onionlike structure with phosphorus-containing gangue layers of 2–10 µm thickness. The best concentrate produced from these resources contains approximately 50% iron (Fe) and 0.8–1.2% phosphorus (P) (by mass) (Ai, Yu, and Wei, 2009; Song et al., 2013; Wu, Wen, and Cen, 2011). Further removal of phosphorus from these ores using conventional beneficiation methods is not possible."

Jan 1, 2017

By P. M. Solozhenkin, O. I. Solozhenkin

Currently lead nitrate is used as the recommended activator in Au-Sb flotation. However, due to high levels of hazard, the application of lead nitrate constitutes a potential risk for human health and ecosystems. To mitigate the harmful impact of activators on the environment, further research on activation by alternative reagents has been launched to promote the efficiency of antimony ores. In the present study, adsorption of lead, copper and zinc cations has been investigated by nuclear quadrupole resonance (NQR), which has revealed copper and zinc cations penetration into the mineral lattice, although lead cations remain adsorbed on the mineral surface. However, the combination of zinc and copper cations leads to preferential volumetric adsorption of zinc in the mineral lattice and further surface adsorption of copper which positively affects the activation process. It has been established that activation of stibnite can be achieved effectively with the mixture of Cu2+:Zn2+=1:1 as much as with lead cations in antimony ore flotation. As a part of this work, the computational modelling has been used in prognosis of reagent activity evaluation (PRAE) for stibnite and aurostibite flotation by sulfhydryl collectors. The lower PRAE value the stronger the ability of a collector to form a stable complex with a mineral. PRAE has shown a strong negative trend to complex formation on the mineral surface of aurostibite and stibnite. Based on these studies, several collectors have been proposed for effective flotation. To verify the feasibility of proposed collectors tetramethyl (ethyl) thiuram disulfides (TMTD and TETD) have been used for flotation of stibnite, sphalerite, pyrite and arsenopyrite. Flotation performance has been improved significantly with TMTD that allows the avoidance of lead nitrate application and increases the recovery of antimony by 8,16%. Keywords: Stibnite, aurostibite, activation, lead, copper, flotation reagents

Jan 1, 2020

By O. O. Ogunmodimu, D. K. Weatherley, M. S. Powell

Discrete element methods (DEM) have provided the ability to resolve the complex phenomena experienced by ore within comminution devices such as tumbling mills. The new developments in DEM techniques and the corresponding increase in computational power have made it more feasible to study the movement of individual ore particles as they traverse a tumbling mill. A range of information can be extracted on individual particle impact histories, such as kinetic energy at the time of collision, velocities of individual particles, per-particle stress tensors, impulse, and collision energy. DEM codes have been modified to provide required information that can be analysed in associated software to investigate the impact of varied operational parameters on the resultant granular dynamics. This paper explores the reaction of individual ore particles to the breakage environment within a tumbling mill using DEM techniques and studies the stressing conditions that would lead to either impact or abrasive breakage. Keywords: DEM, comminution, tumbling mill, breakage

Jan 1, 2020

By D. F. Malan, J. C. Esterhuyse

In this study we explore the use of a novel numerical modelling approach to study the effect of pillar reinforcement on pillar stability. Case studies in the literature indicate that tendons, strapping of the pillars, and shotcrete or thin spray-on liners are commonly used to reinforce pillars. No clear methodology exists to select the type of support or to design the capacity of the support required, however. This has led to ongoing collapses in some mines in spite of heavy support being used to reinforce unstable pillars. A limit equilibrium model with confinement on the edge of the pillar was used to simulate the interaction of the support with the failing pillar. The model correctly predicts that an increase in confinement will lead to a decrease in the extent of pillar failure. As the displacement discontinuity boundary element method allows for the efficient solution of largescale bord-and-pillar layouts, the effect of pillar confinement can now be studied on a mine-wide scale. Accurate calibration of the limit equilibrium model is, however, required before this method can be used for the design of effective pillar support.

May 3, 2023