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By B. Tiryaki

Longwall shearers usually suffer from excessive pick and pickholder consumptions and severe wear of the back plate of the clearance ring section of shearer drums. In practice, most of the drums were seen to be withdrawn from the face due to the abovementioned problems, while vane picks and their holders were intact due to the improper lacing design of the clearance ring picks. However, few underground investigations and their results on the effect of lacing arrangement of clearance picks on the service life of shearer drums have been published. Nevertheless, the pick consumption characteristics of shearer drums were not investigated in detail, since these are fewer pick consumptions with shearers when compared to roadheaders. This paper is concerned with the comprehensive in situ trials on the effect of lacing of clearance ring picks on the lifespan of shearer drums, and the pick consumption characteristics of longwall shearers at Cayirhan Coal Mine in Turkey. The lifespan of shearer drums employed with shearers in this mine increased 70 per cent, while the consumption rate of clearance ring picks decreased threefold through using an alternative lacing for clearance picks, indicating the significance of utilizing proper design techniques for clearance ring picks for the service life of shearer drums. Statistical analyses carried out, using the raw pick consumption data, implied that the clearance ring picks experienced much higher loads than vane picks, revealing that special attention must be paid to designing clearance ring picks. An average maximum consumption value of 41 was determined for clearance ring picks, with corner-cutting picks having the most replacements, while it was 35 for vane picks, on three-day based pick replacements.

Jan 1, 2004

By C. Gatschlhofer, A. Krammer, H. Raupenstrauch, T. Hochsteiner, A. Holzer, L. Wiszniewski

The rising demand for lithium-ion batteries, coupled with international climate targets, emphasises the need for circular economy and zero-waste recycling approaches. However, so far, no industrial-scaled solutions are available that fulfil global recovery targets. Therefore, a novel pyrometallurgical reactor was developed at the Chair of Thermal Processing Technology at Montanuniversitaet Leoben to avoid lithium slagging and recover volatile elements via the gas phase. Nevertheless, previous results show that several impact factors, including interfering elements or pre-treatment steps, strongly limit the recycling efficiency of black mass. To simulate the black mass and provide feedback on possible influences of pre-treatment steps, cathode material from production with additives of interfering elements was analysed regarding melting behaviour. The results show that formation of a further processable alloy was increased by almost 50% when pretreatment steps were excluded, indicating pre-treatment steps as a major influence to be considered within this specific recycling route.

Jan 1, 2023

By H. C. Voges

The concentration of cassiterite at Iscor's Uis Mine is described, and information is given on aspects of the concentration of iron ore at Thabazimbi and Sishen Mines. At Uis, a very Iow-grade tin ore is concentrated by three-stage jigging, spiral concentration, and tabling to give a high-grade concentrate with a recovery of 80 per cent of the tin. A Iow-grade tantalite-columbite concentrate is also produced. The possibility of recovering mica, the use of sluice boxes instead of spirals, and the recovery of cassiterite from minus 45 µm material are being investigated. At the two iron-ore mines, heavy-medium separation is applied to size fractions larger than 0,5 mm. The types of ferrosilicon and the circuits used for the recovery of ferrosilicon from the various dilute-medium circuits are described. The spiral-concentration plant being installed at Thabazimbi for the treatment of the minus 0,5 mm portion of the ore is described.

Jan 1, 1982

By M. Izadi Yazdan-Abadi, S. H. Amiri, M. Ramezanizadeh, M. Bazmandeh

Iron ore concentrate is used as the fresh feed of pelletising plants. The green pellet properties depend on iron concentrate characteristics such as particle size distribution (PSD), specific surface area (Blaine value), iron grade, moisture content and grinding methods. The grinding methods affects particle size distribution and Blaine value. To find out the effects of grinding methods on pelletising process, green pellets were produced with concentrates that were reground by means of HPGR (high pressure grinding rolls) and ball mill. The Blaine values of ground concentrates in both types of milling were approximately 1400, 1600 and 1800 cm2/gr. The results of green pelletising tests on a pilot plant scale showed that at the same Blaine values, drop numbers of green pellets produced by ground concentrate inside HPGR were higher than the green pellets produced by ground concentrate inside a ball mill. Also, reground concentrates by means of HPGR, in comparison with ball mill, caused the production of green pellets, at higher wet and dry compression strengths. As a result, it was found that preparing the pelletising feed by means of HPGR led to more positive effects on the properties of green pellets. Keywords: Ball mill, HPGR, green pellet, drop number, wet and dry compression strengths

Jan 1, 2020

By Pieter de Waal

The beneficiation equipment under the control of plant metallurgists exploits the differences in the physical properties between valuable and waste mineral components. In many cases, laboratory results are too late for process control and can only serve the purpose of "post" reports, the calculation of a mass balance and the issue of a quality certificate. As a result, experienced operators regularly adjust separation equipment based on the colour and texture of the various product streams in the beneficiation plant. Metallurgists quickly learn to recognise the different minerals in their ore body. The stereo microscope has been a valuable tool used by operators to quantify known mineral species. For many years it was the only practical method available for the purpose of process control and even for quality contro1. The modem spectroscope is far superior to the human eye and can rapidly detect a change in mineral composition. New generation optical scanners and digital signal processors can provide useful signals, related to mineral composition that can readily be applied for the purpose of process control. Successful case studies, covering dry in-line and slurry applications as well as in-plant fast spot analysers are presented.

Jan 1, 2014

The September General Meeting of the Institute was held in Kelvin House, Johannesburg, on 16th September, 1970, at 3.00 p.m. Mr V. C. Robinson (President) was in the Chair. There were also present one hundred and eighteen Fellows, including Dr J. M. Bereza, H. P. Carlisle, R. J. C. Goode, Dr J. P. Hugo, P. Lambooy, Prof R. P. Plewman, W. W. Malan, Dr J. T. McIntyre, Dr M. D. G. Salamon, L. W. P. Van den Bosch, P. A. von Wielligh (Council Members), A. Bain, G. P. Bennet, D. L. Carson, G. L. H. Diering, M. E. E. Douglas, F. A. B. Fouche, R. Fourie, A. R. C. Fowler, E. B. Gordon, J. S. Hay, G. H. Henderson, S. D. Hill, A. C. Hofmeyr, J. M. Jacobs, A. F. Lee, D. G. Malan, L. J. Prince, W. G. Pyne-Mercier, A. H. Mokken, Dr W. S. Rapson, R. R. Richardson, H. V. Solomon, C. G. Sowry, G. G. Stanley, G. R. Still, D. L. Starkey, D. L. Taylor, E. W. Thiel, I. E. Van Aswegan, M. van Ryneve1d Steyn, N. B. Vinson, H. Wheeler, Dr A. Whillier, R. A .Wilson, C. F. Ziervogel. Forty-two Members including R. C. Bertram, F. Collier, G. C. Currie, O. Davel, J. M. Gosnell, A. Hazell, Dr N. C. Joughin, F. Kleinschmidt, D. Love, R. B. Macgillivray, D. Mather, R. D. R. Munro, R. S. Pearson, J. J. Peisl, T. J. Pole, A. J. Rossouw, R. G. B. Skirving, G. S. Schwartz, K. Stee1e, H. A. G. Slater, A. Taylor, B. A. Thomas, P. L. Vaughan, D. T. Watt, W. Wilson. Nineteen Associates including R. K. Briggs, S. I. Du Preez, P. G. Gaylard, P. H. Hartslief, W. M. Mackay, A. D. Ross. Three Students: V. S. Care, R. J. Drummond, P. J. Pretorius. Thirty-one Visitors including C. P. S. Barnard, D. W. Bosch, M. Bain G. L. Brown, G. D. Behrens, C. Coetzer, D. M. Gilbart-Smith, R. L. Man, Dr G. J. Stander, M. W. L. Steinobel, R. H. E. Thorpe, T. D. van Wyk, P. H. van Zyl, E. Vereecken, J. J. H. Viljoen. Secretary, D. C. Visser. Total present: 215. OBITUARIES The President: "It is my sad duty to announce the death of the following: Bruce Donaldson Crawford, Fellow, who joined the Institute in 1951 and passed away on 29th April, 1970. Donald Joseph Powrie, Life Fellow, who joined the Institute in 1935 and passed away on 22nd July, 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." MEMBERSHIP The President: "I have much pleasure in announcing that the names of the under-mentioned 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: Associate: WiIliam Norman Carter. Students: Roman Michael Dabrowski, Sean George Dean Eaton, Alan Philip Stonham Howard, Anton du Preez Roos, Richard Harold Tourle. MEMBERS TRANSFERRED TO A HIGHER GRADE From Graduate to Member: Terrance Alexander Ward. From Associate to Member: Bernard Andre Thomas. "I welcome the newly elected members to the Institute and congratulate the members who had been transferred to a higher grade." CO-OPTION The President: "I wish to advise members that, in terms of clause 3.9 of the Constitution, Mc. H. P. Carlisle had been co-opted to serve on Council." PAPERS FOR PRESENTATION The President: "We have two papers today, and I am first going to call on Dr Stander the Head of the Water Division of the C.S.I.R., who IS well known to many of you for his work and talks on pollution, who has had more than a little to do with this industry, and who has been I would say, of the greatest possible assistance to the mining industry in overcoming the problems of pollution which are so prevalent in industry of this nature. He, Mr Henzen and Mr Funke have written this paper, 'The disposal of polluted effluents from mining, metallurgical and metal-finishing industries, their effects on receiving water and remedial measures.' This is the Water Year, as you know, and it is most appropriate that we should have such an authority to talk to us on this very important topic. I now have much pleasure in asking Dr Stander to introduce his paper." After the presentation of the paper the President said, "Gentlemen, I am sure that you would like me on your behalf, to thank Dr Stander very sincerely for a paper which I think has enabled us to get a completely new slant on the Water Year. There are many people who have put their finger on this campaign and said, it is all a gimmick. There are others-I suppose notably some of the bridge clubs which operate on week-day afternoons in Parkview-who seem to think that this is a quick way of getting early rain. Of course, it is not. This is a most important paper which we have had given to us this afternoon. You probably found it here when you arrived and have not read it-I was very lucky to be able to read it last night, and there is an awful lot of meat in it. For as long as I have been associated with mining in any way, there has been a problem of polluted effluent-of effluents carrying a mineral load from mining, and I think Dr Stander is absolutely right-and, of course, the Commission is right when they say that this is not merely the problem of mine management or mine owners-this is a problem which affects every single human being in this country.

By V. Sheikhzadeh, M. Saghaeian, N. Esmaeili, R. Hejazi, A. D. Ahmadabadi

The main challenges in most low grade iron ore deposits are finding the optimum flowsheet for beneficiation to achieve a final concentrate from both technical and economic viewpoints. Dry preconcentration techniques are being used to assist in reducing the amount of ROM feed to the plant. In this paper the benefits of utilising a dry cobbing magnetic separation technique for upgrading the product of HPGR in a closed circuit with dry screen 4 and 1.4 mm by performing a pilot scale test work was investigated. The experimental test work was done on two sample types of Yogi BIF magnetite iron ore located in Western Australia. Prior to magnetic separation studies, detailed characterisation of the feed materials including physical, chemical, mineralogical and magnetic properties were carried out. Furthermore, the effects of process parameters: drum rotation speed (1.5, 2.5 and 3.5 m/s), magnetic field intensity (1100 and 3800 gauss) and feed size (minus 4 and 1.4 mm) were investigated. The results revealed that sample type1 with 33.90% Fe could be upgraded to 41.51% Fe by using a stage of 1100 gauss dry magnetic separator with 69.12% weight recovery and 84.36% Fe recovery at a size of 4 mm. Also for sample type2, it is possible to increase Fe grade from 29.84% to above 36.68% with 75.58% weight recovery and 90.32% Fe recovery by applying one stage of 1100 gauss dry magnetic separator to a 4 mm size sample. Keywords: Banded iron formation (BIF), pre-concentration, dry cobbing technique, magnetic separator

Jan 1, 2020

By I. O. Ondicho, E. K. Mutinda, B. O. Alunda, E. Agyekum

Driven by the necessity to improve blast performance regarding fragment size distribution in limestone mines, this paper introduces the prediction and measurement of blast fragmentation distribution through the modified Kuz-Ram (MKR) and Kuznetsov-Cunningham-Ouchterlony (KCO) models. Precise prediction and measurement of rock fragmentation resulting from blasting play a critical role in hard rock ore extraction. This is due to the substantial influence of post-blast ore size distribution on the efficiency of all subsequent downstream rock handling and processing operations. Additionally, employing secondary breakage of boulders, when necessary, leads to an unjustified rise in production costs. In this paper, the MKR and KCO models were utilised to identify the most appropriate model for application in Bisil and Simba quarries situated in Kajiado County, Kenya. Split-Desktop was used for blast fragment measurement by processing digital images obtained after blasting and computing the fragment size distribution of the blasted rock. As per the investigation, the recorded percentages of boulders generated at the sites ranged from 7% to 12.3% for the Simba quarry and from 11.2% to 23.9% for the Bisil quarry, respectively. Regression, correlation, and root mean square error (RMSE) were employed as the primary performance indicators. The study concluded that KCO outperformed MKR in accurately predicting blast fragment sizes in the examined quarries.

Mar 5, 2025

By S. Mohanta, B. C. Melkap

"SynopsisDry beneficiation of coal by air dense medium fluidized bed is an emerging trend. It is widely believed that the particle size of the medium has a significant effect on the separation efficiency. This investigation demonstrates that medium particle size has a major effect on separation efficiency. Experimental results show that different size fractions of the same feed respond differently to the same size fraction of medium solids. Furthermore, a particular size fraction of feed coal responds differently with different size fractions of medium solids. The Ep values and overall metallurgical performance parameters, obtained from experimental results, clearly indicate the superior performance of an air dense medium fluidized bed separator when using –150+106 µm magnetite powder as the fluidizing medium. These observations reinforce the importance of sizing the medium particle size for the air dense medium fluidized bed.IntroductionIn an air dense medium fluidized bed (ADMFB), a fluidizing bed of a particular density is created by suspending solid particles in an upward air flow. A feed containing coal particles of different densities is introduced into this fluidizing bed. The particles with relative density less than the bed density float on the top of the bed, while particles denser than the bed density sink through it. Since there is a general correlation between ash content and density of coal particles, it is possible to remove ash-forming impurities from a raw coal to the required level by regulating the density of the fluidizing bed. Recently, the ADMFB process has received significant attention world-wide for its specific advantages of low operating cost and less restrictive for small capacities (Luo and Chen, 2001; Houwelingen and de Jong, 2004; Dwari and Hanumantha Rao, 2007; Sahu et al., 2009; Mohanta et al., 2012). This process is not recognized as a well-established industrial practice because of the availability of efficient wet processing technology. However, with the revival of interest in dry beneficiation of coal in general, and ADMFB in particular, there is a concerted effort to improve the efficiency of the ADMFB process, and successive improvements have made the process a competitive and viable option for beneficiating coal."

Jan 1, 2015

By M. Holuzko, Y. R. Zhang, J. Alexander

The use of dual-energy X-ray transmission (DE-XRT) technology in the mining industry has been developing rapidly in the past decade. In many projects, DE-XRT images are analysed to classify ore and waste in sulphide deposits where the sulphides and non-sulphides have distinct characteristics in density. In the current practice of DE-XRT image processing, every pixel in the image gets classified into two categories, depending on the intensity of the pixel from both low and high energy X-ray response. If the pixel’s intensity is above the threshold curve generated in the high-energy and lowenergy scatter plot, it is classified as “higher density” material, and the remaining pixels are classified as “lower density” material. This paper elaborates on an alternative approach to DE-XRT image processing for in-depth characterisation of samples from a lead-zinc sulphide deposit. The detailed characterisation is achieved by providing density distribution of individual rock using DE-XRT laboratory sorting unit (COMEX) located at the University of British Columbia. Instead of classifying the X-ray images into two different classes from one threshold curve, multiple density classes are created between two threshold curves to generate the density distribution. By manipulating the two threshold curves, we can analyse images of samples obtained at different resolutions of density distribution. If the two threshold curves become infinitely close to each other, it will create a single-threshold scenario similar to the current methods being used in the industry. This method provides the ability to change the threshold curves, hence providing more flexibility on material characterisation based on the needs of the operation. Furthermore, the DE-XRT images from individual rock specimens are compared to the test results from hand-held X-ray fluorescence (XRF) analyser as well as assays of various elements for the same set of samples. The data analysis will provide information regarding ore characteristics and also the theoretical performance of the sensor-based sorting. Keywords: Dual-energy X-ray Transmission (DE-XRT), X-ray fluorescence (XRF), ore characterisation, density distribution

Jan 1, 2020

By R. Uwaoma, A. Goosen, R. Matjie, K. Mphahlele, J. Bunt

Coal properties that are associated with wear and damage of grinding equipment during pulverization prior to combustion were investigated. A South African Highveld feed coal and its beneficiated fractions were crushed to <1 >0.25 mm particles for the grindability tests. These particles were milled and screened into <75 μm and >75 μm fractions, which were analysed by different techniques to establish a correlation with the conventional Hardgrove Grindability Index (HGI). The <1.5 g.cm-3 float fraction, which contained 93 vol.% (mineral matter free) total -macerals,9% kaolinite, and had the lowest HGI (57) (hardest to grind) was pulverized for 15, 30, 60, and 120 minutes for particle size distribution analysis. This analysis indicated that the content of <75 μm particles increases with increased grinding time. The >1.9 g.cm-3 sink fraction, with the highest HGI (76), 44% kaolinite, and 20 vol.% total macerals, was ground easily to generate the highest proportion of <75 μm particles. Based on higher correlation coefficients (R2 = 0.77–0.91), the ash yield, mineral matter, petrographic composition, and fixed-carbon have significant effects on the HGI. Conversely, the inherent moisture and total sulphur (R2 = 0.48–0.62) have only minor effects on the HGI. Results from this investigation could be implemented in the preparation of a suitable pulverized fuel with little equipment wear, as well as utilizing mineralogical and petrographic compositions. Finally, the effect of microlithotypes and maceral types in South African feed coals on the HGI should be investigated in further pulverization and grindability studies.

Jul 5, 2023

By K. Barani, S. M. S. Ganji

Creatine was used as a lixiviant for gold dissolution from gold ore. The effects of creatine concentration, temperature, leach time, and pH were examined for their influence on extent of gold dissolution. The results show that at a temperature of 75°C and pH 11.5, gold dissolution increased from 51% to 88% on increasing creatine concentration from 25 to 50 g/t. Further increase in creatine concentration showed a negative effect on the gold dissolution. Gold dissolution increased from 47% to 87% by increasing the temperature from 25°C to 55°C, and from 61% to 89% by increasing pH from 10 to 11.5. Under the optimum conditions of solids’ content of 30%, pH 11.5, creatine concentration of 100 g/t, temperature of 75°C, and hydrogen peroxide addition of 2%, about 90% of the gold could be dissolved from the ore after 24 h. A comparison between creatine and cyanide leaching showed that 90% gold dissolution was achieved at a cyanide concentration of 300 g/t, which is three times higher than the creatine concentration under optimal conditions.

Apr 14, 2024

By M. R. Khalesi, Y. Kianinia, A. Seyedhakimi, F. Soltani

"The feed ore to Agh-Darreh gold processing plant (Takab City, Iran) contains 2 ppm Au, 7 ppm Ag, and 120 ppm Hg. After cyanide leaching of the feed at pH 10.4, 80% of the total mercury (in the form of cinnabar and metacinnabar) goes to the tailings dam. In this research, separation of mercury from the tailings by flotation was investigated. The effects of collector type and dosage, pH, and the number of cleaner stages were studied. The results showed that after two stages of cleaning a 40–62% recovery of Hg at a grade of 14.3% Hg is attainable. Recycle water from a test in which 50 g/t amyl xanthate and 30 g/t pine oil was used in the flotation stage showed no adverse effect on the leaching and adsorption of gold onto activated carbon.IntroductionMercury, most commonly found in the nature as the mineral cinnabar (HgS), is a hazardous substance because of its mobility and toxicity (Kyle et al., 2012). Roasting is the wellestablished treatment method for mercury ores, in which the sulphur is burned and volatilized and mercury recovered subsequently by cooling and condensation. However, for low-grade ores, flotation is mainly applied for primary concentration due to its comparatively low costs, low environmental hazards, and flexibility regarding feed variations (Bulatovic, 2007). Particularly, cinnabar can be easily recovered by flotation using pine oil and a collector such as xanthate (Bulatovic, 2007; Crozier, 1991). Floatability of cinnabar is reduced due to surface oxidation when it is exposed to the atmosphere after crushing. This problem can be eliminated by adding copper sulphate and lead nitrate or acetate. The best pH for cinnabar flotation is in the range of 6.5 to 8.5 according to Erspamer and Wells, (1954), who reported that cinnabar and stibnite can be floated with long-chain xanthate collectors and an alcohol frother, with cumulative recoveries of 97.8% and 94.7%, respectively. Lead acetate was used as an activator."

Jan 1, 2017

By R. Simon, P. Pagé, L. Li, P. Yang

The Mathews-Potvin stability method is widely used in the Canadian mining industry as a starting point to determine the maximum dimensions of mine stopes. However, it cannot be applied to inclined (more frequently encountered) mine stopes without conducting numerical modelling to obtain the stress factor A, defined as a function of the ratio of unconfined compressive strength of intact rock to the induced principal stress on the exposed stope walls. The need to conduct numerical modelling significantly limits the application of the Mathews-Potvin method. In addition, given its empirical nature and main application for preliminary design, it is deemed undesirable to conduct numerical modelling, especially elaborate modelling. Alternatively, theoretical methods can provide a much simpler and quicker way to estimate stresses around stopes and the corresponding stress factors. Over the years, a large number of studies have been conducted to estimate stresses around openings excavated with various crosssections. However, theoretical or graphical solutions remain unavailable for mine stopes that typically consist of horizontal floor and roof, and two parallel inclined walls (hangingwall and footwall). To remedy this situation, a series of numerical simulations is first performed for openings with vertical and inclined walls, including typical stopes commonly encountered in underground mines. A group of empirical solutions is then formulated to estimate the induced principal stresses at the roof centre and mid-height of the stope walls. The validity and predictability of the proposed solution have been verified using additional numerical simulations. The proposed solution can thus be used to calculate stresses and the resultant stress factors A around typical mine stopes with any inclination angle and height to width ratio, under any in-situ stress state, without conducting numerical modelling.

Aug 1, 2021

By S. M. Rupprecht

A deposit to be mined by underground methods can be accessed by a number of methods: ? Adit ? Decline or ramp ? Inclined shaft ? Vertical shaft. Adits are an economical approach when the orebody is above the general floor elevation i.e. suitable in hilly or mountainous terrain. Incline shafts are limited to relatively shallow deposits, and because they are developed on an incline, development lengths for a given depth are the three to five times longer than for a vertical shaft. Vertical shafts are the preferred method for deposits deeper than 300 m but the development rate is slow and construction costs are very high. Declines or ramps offer early access to shallow deposits, which develops the ore body expediently, but are generally developed at a gradient of approximately 12 per cent. Decline haulages have become an attractive alternative to shaft hoisting, and over recent years the role of decline access has become more widespread throughout South Africa. Traditionally, South Africa has enjoyed the use of shaft systems, largely due to the large knowledge base of mining the Witwatersrand Basin, where vertical and inclined shafts were the norm. South Africa has also had the advantage of cheap electricity, giving shafts a definite economic advantage. However, in recent years the national power utility ESKOM has undergone an expansion programme that has led to tariff increases of nearly 100% over a three-year period. Based on the changes in electricity tariffs and technological improvements to underground haulage trucks, the economic inputs to access development have changed. This paper reviews mine access for shallow deposits as currently applied in South Africa. Based on current economic inputs, the paper investigates at what point a vertical shaft would be more economical than a decline system utilizing typical South African mining equipment.

Jan 1, 2012

By M. G. Maruma, L. A. Mampuru

"Mill liner wear is a major cost item in the mining industry and there is continuous research to prolong the life of the liners. Over the years it has become apparent that even though high-chromium white cast irons are highly efficient as abrasion-resistant materials, a combination of wear resistance and fracture strength remains difficult to achieve. Increasing the hardness of the high-chrome white cast iron (HCWCI), which improves the resistance to abrasion wear, is often accompanied by a deterioration in fracture strength. Operational conditions inside the mill require that the liner should be made of highly wear-resistant material with some fracture strength. Vanadium additions ranging from 0.2 to 3 wt% were made to HCWCI in an attempt to refine the microstructure. It was found that an increase in vanadium content promotes grain refinement. A content of 1.5-3 wt% gave the best results as measured by the maximum breaking strength.IntroductionOver the years it has become apparent that even though high-chromium white cast irons are highly efficient abrasion-resistant material, a combination of excellent wear resistance and fracture strength remains difficult to achieve. The exceptional wear resistance of highchromium white cast iron (HCWCI) is attributed to hard chromium carbides embedded in an austenitic/martensitic/pearlitic matrix. When the chromium contents exceed 12 wt%, interconnected MC3-type carbides of conventional cast irons are replaced by rodshaped and isolated M7C3 carbides (Powell, 1980), leading to an improvement in the impact toughness, ductility and fatigue resistance. However, the main M7C3 carbides in HCWCI are hard and brittle and can provide an easy path for crack propagation. This limits the applications of HCWCI, particularly in severe impact conditions. Most operations involving HCWCI are in crushing and grinding and the life of a part/liner is limited by its wear resistance. However, improving the wear resistance of HWCI comes at the cost of a significant reduction in fracture strength. Concerns about premature failure of HCWCI mill liners in the mining industries prompted a study to improve the wear resistance and mechanical properties of HCWCI."

Jan 1, 2016

By N Morales, G Nelis

Short-term plans must meet the long-term goals while accounting for shovel selectivity, operational space, and scheduling restrictions. There are several approaches that deal with these issues to deliver a feasible short-term schedule. This paper compares two approaches based on mathematical programming to address the short-term mining cut definition and scheduling in an integrated way. They work by scheduling extraction to comply with long-term production goals, but they differ in how mining cuts are modelled. The first approach schedules Selective Mining Units (SMUs) but aggregates them around predefined locations. The second approach does not work on SMUs; it decides directly what mining cuts are to be used from a pre-defined set of shapes. It assigns a destination and schedules the extraction for the selected mining cuts. We applied both approaches in a real case study to compare their results in terms of profit, mining cut design, expertise needed, profit, and optimisation performance.

Sep 1, 2021

By C. A. Border

This paper is a brief record of the State&apos;s involvement in the problems that have faced Iow-grade mines in the South African gold-mining industry for a period of more than sixty years. Not all the recommendations made by the various commissions are recorded here, but those which are included highlight the fact that many of the problems that plagued the industry during those years, whether economic or labour matters, are still troubling the industry today.

Jan 1, 1981

By P. Sebola, S. Rasmeni, K. Seripe, D. Chetty

"South Africa’s Northern Cape Province hosts semi-precious and gemstone occurrences that are sporadically mined on a small scale by local communities. Tiger’s eye, a gemstone known for its chatoyancy properties, is found in important deposits located near the town of Prieska, where is it intermittently mined. Challenges faced by small-scale and informal mining include mining without proper permits, risky mining practice in dangerous terrain, and illegal export of raw material without concerted effort at domestic beneficiation. As part of a study aimed at job creation and social upliftment in the region, tiger’s eye deposits in the Prieska area were assessed to assist small-scale miners to understand tiger’s eye grades and their distribution. This will allow not only more efficient and safer mining of these deposits, but also beneficiation of the raw product into tumbled stones, cabochons, jewellery, and other small artefacts for sale. A hub established in Prieska by Mintek trains locals in the beneficiation of tiger’s eye. Supply to the hub must make use of a consistent grading system, which is discussed in this paper. Together with proper mine licensing, such an approach will develop mining and beneficiation skills, and create and sustain employment for the local community. IntroductionTiger’s eye is a semi-precious stone known for its chatoyancy property, which is caused by parallel, silicified asbestos fibres that impart a silky lustre to specimens. Deposits of tiger’s eye in the surrounds of the town of Prieska, Northern Cape Province, formed the focus of a study aimed at small-scale mining and beneficiation of this commodity. The Prieska tiger’s eye deposits are located along the N10 route to Upington (Figure 1). Tiger’s eye is unevenly distributed and occurs as lenses of various sizes, interbedded in gently folded metasedimentary rocks of mostly banded iron formation (BIF). The tiger’s eye occurrence in the Northern Cape Province, especially in the Prieska area, has not been extensively researched. There is thus limited information available in the public domain. The lack of knowledge on tiger’s eye distribution has resulted in local small-scale miners adopting a trial-and-error method of mining. Basic geological mapping and field evaluation of the deposit, coupled with professional judgement, are important aspects of any small-scale mining operation and can contribute significantly to the formulation of various acceptable and equally viable mining methods and practices."

Jan 1, 2016

By R. Pretorius, N. Mautsa

In a cobalt precipitation plant, phosphoric acid is used to eliminate excess uranium from the pregnant leach solution, resulting in a cobalt hydroxide product that has little uranium contamination. However, the amount of phosphoric acid added must be monitored and controlled to avoid financial and sustainability impacts and to prevent negative impacts on the final product quality. One possible solution to this problem is the use of online residual phosphorus measurement techniques to regulate the addition. By continuously monitoring the residual phosphorus levels in the solution, the plant can adjust dosing in real time to maintain the target residual phosphorus level. As a result, the cobalt precipitation plant can improve phosphorus level control, lowering the risk of overdosing, and ensuring consistent product quality. This approach can also improve process efficiency, reduce operational costs, and have a positive environmental impact

Jan 1, 2023