Search Documents

By B. McFadzean, N. Patterson, M. Becker, S. Geldenhuys

The retreatment of secondary tailings for platinum group metals recovery presents a range of potential challenges, which vary depending on the nature of the original ore and the type of pretreatment it was subjected to. These challenges include the prevalence of ultrafine particles, which promote slimes coatings on valuable minerals, hinder bubble-particle attachment, increase pulp viscosity, and lead to higher gangue entrainment; surface oxidation of minerals, which alters their floatability; and the presence of deleterious gangue minerals and residual platinum group metal species that are inherently difficult to recover by flotation. This study compares the batch flotation performance across a range of tailings samples from the eastern and western limbs of the Bushveld Complex. A complementary mineralogical analysis was conducted to gain deeper insights into mineral behaviour. The paper evaluates these findings to identify the key factors contributing to poor platinum group metal performance.

Mar 6, 2026

By I. M. Morsi

The present study investigates the feasibility of using some materials as start-up slags for the extraction of magnesium metal from Egyptian dolomite ores by the Magnethermic technique. The reduction of roasted dolomite (dolime) takes place in a closed evacuated electric arc furnace (small Magnetherm reactor) using ferrosilicon as a reducing agent and liquid start-up slag as a reduction bath under an inert atmosphere. The operational parameters affecting the stabilization of the start-up slag composition and the extraction of magnesium such as reducing agent stoichiometry, reduction temperature, and time were investigated. The dolomitic charge was in the form of sintered briquettes. The charge was reduced under an argon atmosphere in the Magnetherm reactor for constant period and constant temperature. The results showed that the clinker can be used as a start-up slag for the magnethermic process. Also, the optimum conditions for the extraction process were found at 2XSi stoichiometry to give maximum reduction of 80% after 15 minutes reduction time at a temperature of 1550°C. XRD and XRF measurements were used to determine the phases present and the extent of reduction of magnesium, respectively. Keywords magnesium, dolomite ore, magnetherm, magnetherm reactor, silicothermic reduction.

Jun 1, 2013

By F. H. Deist, H. D. Small, J. D. Austin, L. F. Duvel

The development and application of a Computer System to aid in the planning of production in mines By F. H. Deist, L. F. Duvel, J. D. Austin, H. D. Small A computer system to aid in the planning of production in mines and its application to a complex colliery are descrIbed, The system consists of three phases, the data base maintenance program the 'production simulator' and the report generation facility, In the first part of the paper the categories of information kept on the data base and the functions of the simulator are described in general terms. The application of the system to a multi-product colliery operating a variety of mining methods in a number of superimposed seams is described m the second part. In conclusion some comments are made on further applications and intended future developments.

By A. V. Z. Brink

This paper describes the development of a monitoring architecture that allows for continuous monitoring of the process of mining, the underground environment, the state of the rockmass and its response to mining. The system is based on an open standard and is non-propriety. It allows for dense sensor arrays in the workplace, wire less communication to the closest power line, and TCP/IP communication to a central server. Continuous monitoring and quantification of the appropriate parameters allows a mine to optimise its mine process; to dynamically access the safety and health risk to people and equipment; and to quantify exposure to potential heath hazards such as dust, gas or noise. Current application examples of continuous monitoring include an application to optimise drilling and blasting thought fragmentation monitoring; an application of wireless sensor network-based monitoring in to provide early detection of potential rockfalls; and a trail to continuously assess the gold grade at the shaft through correlation with radioactivity. It is unlikely that a single monitored parameter will provide adequate knowledge of the assessed risk or even an optimisation approach. Multiple parameters are being combined using cognitive science tools such as Bayesian theory and other statistical methods to improve the accuracy and relevance of, for example, risk quantification. The decision maker is not confronted with massive amounts of raw data but rather with a single knowledge statement such a probability of failure, a human physiological strain index or an optimisation index.

Jan 1, 2008

By J. P. Beukes

South Africa holds approximately three-quarters of the world?s viable chromite ore resources and dominates the global production of ferrochrome. Albeit completely unintended, small amounts of Cr(VI) are formed during ferrochrome production. Certain Cr(VI)species are regarded as carcinogenic, hence making the treatment of some ferrochrome waste materials necessary. In this paper, the Cr(VI) treatment strategies currently employed by the South African ferrochrome producers are investigated by means of a literature review and a questionnaire survey. From the discussion, it is evident that various treatment strategies are available to deal with Cr(VI)-containing waste in the ferrochrome industry. However, by far the most commonly applied treatment strategy remains the aqueous reduction of Cr(VI) with ferrous iron. The advantages and the correct application of this strategy, together with the disadvantages and pitfalls, are argued. Innovative improvements on historic practices are also discussed

Jan 1, 2012

By B. Moritz, W. Schubert, E. A. Button

ABSTRACT: Geological conditions associated with alpine environments in combination with high overburden in many tunnelling projects lead to squeezing behaviour. The main problems associated with such conditions include large deformations, overstressing of supports, and lack of face stability. In the past during Alpine tunnelling the problem of large displacements incompatible with rockbolt – shotcrete support systems have been solved by leaving gaps in the lining to accommodate excessive deformations. In the late nineties, yielding elements have been developed, which are integrated into the lining. The paper deals with the basic concept, the design and the application of that system, which has been successfully used in several Alpine tunnels. ZUSAMMENFASSUNG: Die geologischen Verhältnisse in den Alpen führen bei großer Überlagerung häufig zu starken Deformationen während des Baues von Tunneln. Die großen Verformungen führen in vielen Fällen zu einer Überbeanspruchung des Ausbaues und Problemen mit der Ortsbruststabilität. Früher ist man dem Problem der Unverträglichkeit des Ausbaues mit den hohen Dehnungen durch Freilassen von Deformationschlitzen im Spritzbeton begegnet. Vor etwa 10 Jahren wurden duktile Stahlelemente entwickelt, welche in die Spritzbetonschale integriert werden. Der Beitrag beschäftigt sich mit dem Konzept, der Planung und der Ausführung. RÉSUMÉ: Les conditions géologiques dans les Alpes conduisent fréquemment lors d'un grand recouvrement à des déformations fortes pendant la construction des tunnels. Les grandes déformations conduisent dans beaucoup de cas à une surtension du revêtement et à des problèmes avec la stabilité de front de taille. On a fait face plus tôt au problème de l'incompatibilité du revêtement avec les extensions élevées par libérer des rainures dans le béton projeté. Il y a environ 10 ans, des éléments sidérurgiques ductiles qui sont intégrés dans le béton projeté ont été développés. La contribution s'occupe de concept, de planification et de mise en oeuvre.

Jan 1, 2003

"Chairman: Professor C. O. Frush Rapporteur: Mr A. C. SchmidtPapers:Planning of underground copper mining by J. K. Williams, L. Smith and M. P. WellsLinear programming models of copper leach and solvent extraction plants by W. P. C. Duyvesteyn, J. R. Cutland and J. R. L. RusselPlanning and forecasting stope production by D. W. Kappes and P. F. X. Moussett-JonesA proposed method of dynamic ore reserve assessment for a caving system of mining by A. F. Spinks and S. P. NicholsThe initial point made by Mr L. Smith in presenting his paper was that the planning aid outlined in the preprint was neither sophisticated nor complicated. However, it was a system which worked and was a very real way in which the computer was being used to assist miners, in particular, who at the present moment have very little experience in the use of computers.Mr Smith apologised for the fact that the editors of the paper had eliminated all reference to 'time'. This was very unfortunate because the essence of the system was that it saved time, which was one of the main points made in the paper.The operations being planned by this means cover the Rokana orebody which is a stratiform body mined by open stoping.The planner has to decide how much ore to mine from each base in each time period of his plan, that is, from three to four months hence to a year ahead. Normal procedure is for the planner to have discussions with the underground manager on some of the information he requires. The sort of information needed is (i) tramming limits for each face, (ii) extraction and grade factors, (iii) the present status of mining operations so that the planner knows where to start the new plan, and, (iv) details of any other mining consider¬ations that need to be incorporated in the plan.The objective at this point is to produce an initial plan for discussion purposes. All the information required comes from one sheet per stops and shows, inter alia, the stope identifier, the length along strike, the ore tonnage, the copper and cobalt grades and, finally, the extraction and grade factors.The program itself, among many other things, checks the data for validity, compatibility, completeness and credibility and prints error messages accordingly. Output from this system is in the form of a summary of production from each face, as well as giving the figures of ore reserve depletion. This summary indicates which slopes are to be mined in this time period, the original survey grades (copper and cobalt), the estimated production grades, how much is to be mined from each stope and the copper and cobalt production accordingly."

Jan 1, 2014

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 P. J. Bartlett, H. A. D. Kirsten

A two-dimensional numerical scheme for the simulation of the plastic stress-strain properties of rock, and the various components of rock reinforcement and shotcrete, was used to rigorously determine the characteristics of tunnel support under squeezing conditions. D-shaped tunnels varying in size from 2,8 to 6,5 m in height and width were considered. The four main mining stages in the BAS block cave on Premier Mine were simulated as alternative sets of field stresses. The rock reinforcement comprised 1,8 m long fully grouted rockbolts and 6,0 m long fully grouted cable anchors at various spacings, and of various tensile and bond strengths. Various thicknesses of shotcrete and footwall support configurations were also considered. It was found that shotcrete and rock reinforcement, owing to inherent differences in stiffness, do not function in unison. As monolithic application, shotcrete has an overriding avidity for the imposed loading and destructs itself unless of extraordinary thickness. Under squeezing conditions, it accordingly supports the excavation surface while the rock reinforcement contains on-going convergence. The loads in the various support components can be determined only by simulation of the shotcrete as a stress-relieved medium to represent its broken condition in the field. The loads in the rock reinforcement vary around a tunnel and are the largest in the sidewalls. The loads increase with an increase in tunnel dimensions, the increase in load in the sidewall due to an increase in height being larger than that in the hanging- and footwalls due to an increase in width. Depending on the strength of the rock, the loads in the rock reinforcement become prohibitively large beyond a certain size of tunnel. The reinforcement of footwall rock can be omitted without adversely affecting that in other walls, provided the tensile and bond strengths of the reinforcement are not limited. The resulting footwall heave may, however, result in undermining of the reinforcement in the adjoining walls. A relative depth of anchor of 1,37 provides adequate bond strength in the larger sizes of tunnel, whereas, in smaller tunnels, anchor length is determined by the allowable convergence. The lack of fun column grouting adversely affects the efficiency of rock reinforcement to a major extent. The loads in rock reinforcement are very sensitive to the strength of the rock. Owing to a lack in refinement and calculational rigour, empirical classification systems are an inappropriate means for the design of tunnel support in squeezing conditions and, as a result, grossly unclear-estimate the support requirements.

Jan 1, 1992

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 D. Marcotte, R. V. Dutaut

In most exploration or mining grade data-sets, the presence of outliers or extreme values represents a significant challenge to mineral resource estimators. The most common practice is to cap the extreme values at a predefined level. A new capping approach is presented that uses QA/QC coarse duplicate data correlation to predict the real data coefficient of variation (i.e., error-free CV). The cap grade is determined such that the capped data has a CV equal to the predicted CV. The robustness of the approach with regard to original core assay length decisions, departure from lognormality, and capping before or after compositing is assessed using simulated data-sets. Real case studies of gold and nickel deposits are used to compare the proposed approach to the methods most widely used in industry. The new approach is simple and objective. It provides a cap grade that is determined automatically, based on predicted CV, and takes into account the quality of the assay procedure as determined by coarse duplicates correlation.

May 1, 2021

By C. J. Pretorius

More than 30 percent of the global demand for zircon (ZrSi04) is supplied by South Africa. A significant amount of the zircon is exported, and beneficiated products are then imported for industrial applications locally. Beneficiating the zircon locally could have a positive impact on the local market, since zircon is only one of many such cases. Ammonium acid fluoride serves as an alternative anhydrous fluorinating agent for zircon in the synthesis of several metal fluoridesl.2. It provides an effective dry fluorinating method and is easier to handle than hydrogen fluoride or fluorine gas. Zircon exposed to extreme plasma temperatures dissociates and becomes more reactive. The reaction of the plasma-dissociated zircon (Zr02?SiO2) with the ammonium acid fluoride (NH4F?XHF, where x= 1 to 5) forms two main intermediate compounds (NH4)3ZrFr(s) and (NH4) 2SiF6(s), the latter decomposing to form volatile products at relatively low temperatures, providing easy separation of the silicon and zirconium compounds. The ammonium zirconate compound decomposes to form zirconium tetrafluoride (ZrF4), which can be further manufactured into zirconium metal, to name but one product. Data on the kinetics of the reaction of ammonium acid fluoride with zircon and plasma-dissociated zircon, combined with the thermo-dynamic parameters of the reaction, is essential for the development of an industrial process for the production of a precursor for the manufacturing of zirconium metal, namely anhydrous ZrF4. Both the reaction kinetics and reaction parameters will be included in this study, as well as some proof that the reaction proceeds to ZrF4 on a small batch scale. If the exact reaction parameters can be pinned down, a wide spectrum of anhydrous metal fluorides can be synthesized through this fluorination route.

Jan 1, 2012

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 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

By N. Mangadoddy, M. Padhi

The simulation of multi-component classification with modified viscosity model is the key focus in the current study. The classification of the ores using hydrocyclone is a renowned process and has a convoluted flow separation phenomenon. The highly turbulent flow inside hydrocyclone depends on the operating and design parameters apart from the feed mixture. Slurry viscosity also plays a dominant role in the classification of solid particles under the centrifugal settling action. A heterogeneous mixture with different components would result in different settling and rheological behaviour of particles’ suspension in the water medium. The newly proposed multi-component viscosity model (Mandakini et al. 2020) is implemented as a user-defined function to define the material property during the CFD study of the mixture rheology inside hydrocyclone classifier. The multiphase and turbulence model is solved using the modified Algebraic Slip Model and Large Eddy Simulation model. A comparison of the predicted component performance curves is evaluated with and without the corrected viscosity model. The density and size effect on the particle phase distribution inside the classifier are compared, where the misplacements of the finer particles are carefully assessed. Validation of the component classification in hydrocyclone with the laboratory experiments found a close agreement with the rheology based CFD data. Keywords: Dual-component, multi-component viscosity model, double-gap rheometer, computational fluid dynamics, high solids concentration

Jan 1, 2020

By B. Friedrich, A. Birich

Gold has been a metal of special importance for mankind for several thousand years. Its outstanding chemical resistance is an important property of this noble metal, but becomes a disadvantage when it comes to gold recovery. The established processes are based on highly aggressive and toxic reagents. Different alternative leaching reagents with a significantly lower toxicity proved to be promising alternatives in the last decades. Major research activities in this field focused on gold ores, so that leaching of secondary resources were not described sufficiently. Based on literature research and extensive experimental investigations, a reagent assessment was conducted for hydrometallurgical gold recovery from electronic waste. It was found that besides thiourea and halides, thiosulfate in particular represents an alternative of major relevance. A variety of different electronic waste (e-waste) specimens were investigated to identify suitable leaching conditions. As a result, an almost complete and selective gold recovery in less than 48 hours from different electronic waste types and components was achieved by thiosulfate leaching. Within the experiments conducted, it was found that the leaching behaviour of cyanide alternative lixiviants differ strongly from leaching of primary ores. Keywords: Gold leaching, cyanide alternative, thiosulfate, electronic waste

Jan 1, 2020

By L. D. Robbins, M. L. Murphy, A. C. Campbell, L. Murphy

This paper reports on what appears to be the first discovery of prehistoric mica-schist mining in southern 4frica. The mine concerned was found in a location very rich in rock art that is one of the most important archaeological sites in the Kalahari. The authors conclude that the oval pieces of mica schist that were found at the mine site were used by Khoisan peoples to scrape fatty tissue from hides that were to be cured. Radiocarbon datings seem to indicate that such ovals were used for at least 20 000 years.

Jan 1, 1994

By J. Petersen, H. Naderi, M. H. Nikzad, M. Karimi

In this research, the thermodynamic study of sodium persulfate (Na2S2O8) solution in the presence and absence of H2SO4 and Fe3(SO4)3 was done. Eh-pH and equilibrium distribution diagrams were constructed using Outotec HSC Chemistry Software and the main stable ionic species were determined. Also, the mean activity coefficient and Pitzer model coefficients were evaluated. Effects of system composition, sodium persulfate concentration and temperature were investigated. According to the results, HS2O7 -, HS2O8 -, S5O3 2-, S4O3 2-, S3O3 2-, HS- and NaSO4 - are the main stable species in these three systems. Increasing of sodium persulfate concentration resulted in disappearing of SO4 2- and the appearance of NaSO4 -. The main effect of increasing the temperature from 25 to 75oC, is changing the stability regions of HS2O7 -, NaSO4 -, SO4 2- and S2-. From equilibrium studies, it was concluded that at 25 and 50oC, increasing the persulfate concentration results in a 55-60% decrease for HS2O7 - and an 20- 30% increase for HS2O8 -. At 75oC, HS2O8 - becomes the main species and its percentage decreases with increasing the persulfate concentration. Keywords: Thermodynamic, sodium persulfate, activity coefficient

Jan 1, 2020

The 96th Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room of the Transvaal Automobile Club in Johannesburg on Wednesday, 11th August, 1993. OBITUARIES The President announced the deaths of the following members of the Institute during the past year. Life Fellow E.F. Laschinger. Other Members R.K. Boright, J.S. Jacobi, R.D. Power, J.H. Cannon, C.J. du Plooy, L.B. Mcrae, C.P. Rossouw, A.L. Sillars, A.W. Heugh, R.K. Briggs, P.J. Stark, and C.S. Stott. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, all rose and observed a moment of silence.

Jan 1, 1993

10th COMMONWEALTH MINING AND METALLURGICAL CONGRESS-CANADA, 1974 The Commonwealth Council of Mining and Metallurgical Institutions has received and accepted an invitation from The Canadian Institute of Mining and Metallurgy for the 10th Commonwealth Mining and Metallurgical Congress to be convened in Canada in April, 1974, immediately following the Annual General Meeting of The Canadian Institute of Mining and Metallurgy. It is proposed that the Congress centre will be Montreal and that, after technical sessions, tours of operations will be arranged. Further information will be issued in due course by The Canadian Institute of Mining and Metallurgy and enquiries should be addressed to the Executive Director of the Institute, 906-1117 Ste. Catherine Street West, Montreal 110, P. Quebec. NOTICE TO ALL STUDENT MEMBERS OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY The Institute offers each year for competition among Student Members of the Institute a prize, or prizes, should entries so warrant it, of up to the value of R100 to be awarded to the Student Member or Members who submit the best paper or dissertation on a topic appropriate to the interests of the Institute. In the case of Student Members who are in full time study at a university the dissertation or thesis which they may have to write in part fulfilment of their university curriculum may be accepted provided it is presented in a manner and on a topic suitable for publication in the Journal. The closing date for the receipt of papers shall be 31st December each year.