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THE BRITISH COUNCIL AWARDS 1971-1972 The British Council invites applications from permanent residents of the Republic of South Africa and South West Africa, for the following awards: SCHOLARSHIPS Scholarships are available to such permanent residents who hold university degrees or comparable professional qualifications. The scholarships are tenable for postgraduate study at universities and other educational establishments in Britain for the academic year of approximately ten months beginning 1st October, 1971. BURSARIES Bursaries are available to such permanent residents who hold university degrees or who, being already established in their professions or trades, hold other qualifications. The bursaries are tenable at British educational institutions or other suitable establishments in Britain for a course of training, study or research lasting not less than two months or more than six. The British Council may, at its discretion, bear the cost of single or return fares to Britain. The closing date for applications is 31st July, 1970. TRAVEL GRANTS Travel grants each of £300 are available in respect of journeys to Britain undertaken between 1st April, 1971 and 31st March, 1972 and are provided to facilitate visits to British universities by persons holding staff appointments or graduate research posts at South African universities. Visits must normally be of at least six months duration. The closing date for applications is 31st October, 1970. For further particulars and the relevant application forms please write stating the type of award for which you wish to apply to: The Cultural Attache, British Embassy, Pretoria. THE SECOND INTERNATIONAL CONFERENCE ON THE PROPERTIES OF LIQUID METALS Tokyo, September 1972 The Second International Conference on the Properties of Liquid Metals will be held under the auspices of The Japan Institute of Metals and The Physical Society of Japan from 3rd to 8th September, 1972 in Tokyo. The purpose of this conference is to continue and extend the efforts towards the objective of the First International Conference on the Properties of Liquid Metals at Brookhaven, 1966. The tentative Conference subjects presently planned are: Structure of Liquid Metals and Alloys; Atomic Transport Properties (Diffusion, Viscosity, etc.); Electronic States and Transport Properties; Thermodynamical Properties; Melting and Phase Transitions. Correspondence regarding the Conference and the request for the First Notice should be addressed to: Professor S. Takeuchi, Chairman of the Organizing Committee, The Research Institute for Iron, Steel and Other Metals, Tohoku University, Sendai, 980, Japan. PROCEEDINGS OF THE NINTH COMMONWEALTH MINING AND METALLURGICAL CONGRESS 1969 Volume 4 of the Proceedings of the Ninth Commonwealth Mining and Metallurgical Congress 1969- Physical and fabrication metallurgy-contains the 24 papers presented under this general heading at the Congress. Also included are discussion, authors' replies, name and subject indexes, and plenary addresses by Sir Val Duncan, O.B.E. and Sir Ronald L. Prain, O.B.E.

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 T. Oberthür

The Great Dyke of Zimbabwe constitutes the world?s second largest reserve of platinum group elements (PGE) after the Bushveld Complex in neighbouring South Africa. Within the Great Dyke, economic concentrations of PGE are restricted to sulphide disseminations of the Main Sulphide Zone (MSZ), which are currently mined at the Ngezi, Unki, and Mimosa mines. Near-surface oxidized MSZ ores have a large potential. Their total resources are in the range of ca. 160 ? 250 Mt; however, all previous attempts to extract the PGE from this ore type proved uneconomic due to low PGE recoveries (<< 50 per cent) achieved by conventional metallurgical methods. Within the ores of pristine, sulphide-bearing MSZ, the PGE are bimodally distributed. Platinum occurs mainly in the form of discrete platinum group mineral (PGM) grains (mainly bismuthotellurides, sulphides, and arsenides), whereas approximately 80 per cent of the Pd (and some Rh) is hosted in pentlandite. Within the oxidized MSZ ores, the PGE are polymodally distributed. Whereas arsenide- and sulphide-PGMs, making up ca. 25 per cent of the original Pt content of the ore, largely remain stable (relict PGMs), the remaining PGMs are disintegrated. The base metal sulphides are destroyed, partly releasing their base metal and PGE contents, and are replaced by iron oxides or hydroxides. Unspecified amounts of the PGE are redistributed and either form secondary PGMs, are found in chemically and mineralogically ill-defined (Pt/Pd)-oxides or hydroxides, or in iron-hydroxides, Mn?Co-hydroxides, and in secondary silicates. The problematic processing of oxidized MSZ ores is attributable to their complex nature and polymodal distribution of the PGE, prohibiting a significant upgrading of the ores by conventional metallurgical methods. Therefore, only bulk leaching methods are viable for ore treatment, and novel metallurgical methods have to be developed for the processing of these ores. Our ongoing work aims at locating the PGE in their mineralogical form in order to understand the mineralogical balance of the PGE in the ores and thereby facilitate the evaluation of metallurgical options for their recovery. A short overview on options and recent advances regarding the recovery of the PGE from oxidized ores is given.

Jan 1, 2012

By Wei Sun, Ruolin Wang, Wenjuan Sun, Junhao Fu, Haisheng Han, Zhao Wei

Pb–benzohydroxamic acid (BHA) (lead complexes of benzohydroxamic acid) exhibits high selectivity but low collecting efficiency in scheelite flotation. This paper reports the manner in which BHA and sodium dodecyl sulfate (SDS) were employed as ligands to coordinate with the lead ions to obtain a colloidal lead-group multiple ligand complex, i.e., the Pb–BHA–SDS, for improving the collecting efficiency of Pb–BHA. The flotation mechanism of Pb–BHA–SDS with respect to scheelite was investigated from the viewpoint of interface science based on the pure mineral flotation, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The results showed that the BHA and SDS coordinated with Pb2+ to form novel leadgroup multiple ligand complexes, which are different from the traditional understanding associated with the mixed collectors. Pb–BHA–SDS was a better collector with stronger collecting ability and excellent selectivity in regard to a scheelite flotation than Pb–BHA. The addition of SDS to Pb–BHA enhanced the latter’s adsorption ability on the scheelite surface and improved the hydrophobicity of the collector’s nonpolar groups, rendering Pb–BHA–SDS as a more efficient collector at a low dosage. Keywords: Scheelite; Pb-BHA complexes; sodium dodecyl sulfate; multiple ligands; Pb–BHA–SDS

Jan 1, 2020

By L. W. Palmer

Compositing or regularization of drillhole data is common practice in mineral resource estimation and is deemed a necessary step in producing unbiased estimates of mineral resources and reserves. Commonly, data are collected over irregular distances due to the varying relative thicknesses of lithologies drilled or sampling/assaying strategies. This necessitates data transformation to regular lengths of equal size to ensure that all data have the same sample support. However, there have been few detailed publications on the effect of this process on the composited data that are subsequently taken forward for the estimation process. In this paper, three currently available compositing methods are reviewed and the effects of inappropriate compositing methodologies presented. It is shown through a case study that compositing samples to different lengths leads to changes in the average and variance of the grades in the drillcores in the dataset, which will impact the final estimated value. These differences are exacerbated by breaks or gaps in data where, for a variety of reasons, there has been no data collection or data have been lost. The importance of appropriately treating blank and zero data is also presented. Globally, these differences might be minimal, but locally may be substantial, affecting the efficiency of the estimation and subsequent use of the results in, for example, mine planning and reconciliation. Further detailed investigation of compositing practices is required if the full implications of compositing are to be understood and any induced bias effectively defined.

Jul 10, 2024

By S. Ata, Y. Pan, S. Gautam, G. Bournival

Bubbles play a vital role in flotation, and their properties directly affect the flotation performance. Xanthates are one of the major collectors used in sulphide mineral flotation. It is often believed that their main function is to render the desired mineral surface hydrophobic, which is essential for the mineral particles to attach to air bubbles. This paper takes a systematic approach to assess the influence of potassium amyl xanthate (PAX) at the air–liquid phase and its interaction with the frother in the concentration of range 10–5×104 ppm. Bubble size was measured in a laboratory flotation cell using a photographic technique and the stability of bubbles was quantified in terms of coalescence time -, the time required for a bubble pair produced at adjacent capillaries to merge into a single bubble. Bubble size reduction of up to 26% was observed with increasing PAX concentration in the cell. The bubble coalescence experiments using PAX only showed that the bubbles coalesced quickly at lower concentrations (10–50 ppm), but they stayed extremely stable at higher concentrations (1×102–1×104 ppm). Further experiments were carried out where the concentration of PAX was fixed at 1 ppm and 4- Methyl-2-pentanol (MIBC) concentration was varied. The synergetic action of PAX and MIBC significantly improved the stability of bubbles in the mixed system, and is even compatible with a stronger frother. The results strongly suggest that the role of PAX at the air–liquid phase should be considered in the practice of sulphide flotation. Keywords: Bubble size, bubble coalescence, PAX, bubble stability

Jan 1, 2020

By J. N. Van der Merwe

Following the Coalbrook disaster in 1960, research into coal pillar strength resulted in the adoption of the concept of a safety factor for the design of stable pillars in South African coal mining. At the time when the original statistical analysis was performed by Salamon and Munro in the early 1960s, 27 cases of failed pillar workings were considered suitable for inclusion in the database of failed pillars. Pillar failure did not stop after the introduction of the safety factor formula by Salamon and Munro (1967). In the ensuing years, pillars that were created before the application of the formula deteriorated and later failed, as did ones that were created after the introduction of the formula. This means that over time, the database of failed pillar cases increased in size, allowing ever more reliable analyses to be performed. The number of failed cases in the database had grown from the original 27 in the 1960s to 86 by 2011. All the failed cases are contained in the updated database. The database of stable pillars, which is also used in the derivation of strength formulae, has now been extended from 125 to 337 cases. The new database of intact pillar cases is more complete as it bridges the time gap between the Salamon and Munro (1967) and the Van der Merwe (2006) databases. The original requirements for inclusion into the database were satisfied in the compilation of this latest collection. The characteristics of the original database of intact pillars did not change in a meaningful way. The mining depth and pillar dimensions of the new database are largely as they were in the original database. Time-related trends with regard to pillar dimensions and depth of mining could not be found, indicating that the geometrical parameters of coal mining in South Africa have not changed meaningfully in approximately a century of mining. The characteristics of cases in the updated database of failed pillars does not differ substantially from the one published by Van der Merwe (2006). The same difference between that database and the original Salamon and Munro database, namely that the average safety factor of the failed cases had increased dramatically, from 1.0 to 1.5, is still apparent. This may be due to the inclusion of more failures from specific areas that exhibit a disproportionate number of failures at higher safety factors. These areas are the Vaal Basin, Klip River, and Free State coalfields. The new database confirms yet again that there is no correlation between the safety factors of failed pillars and their time of failure. The safety factor on its own is thus not a reliable predictor of longterm stability of pillars. Keywords coal pillar, stable pillar cases, pillar collapse, pillar data base.

Nov 1, 2013

By N. V. Moraka

In dealing with transformational aspects, the South African Constitution aspires for a balance between attempts to broadly represent the country’s demographics in the way in which organizations are structured and the need to maintain the necessary skills to ensure continual retention of skills for optimum and efficient organizational performance. Through the Mining Charter, government aimed to redress gender and racial imbalances in the mining industry as part of transforming the demographic representation of mining companies to include black people, women, and people living with disabilities in all job levels up to top management. While the Constitution calls for an appropriate balance between demographic representation and competency, this aspiration for mining poses challenges for companies due to the proficient and competent skills needed in this industry. To this end, the South African mining industry has been subjected to substantial criticism from government regarding the slow progress of transformation. The mining industry justifies its slow pace of transformation by pointing at inconsistent, varying legislation and definitions governing transformation, limited skills available from historically disadvantaged groups, and cautioning not to compromise the sustainability of mining companies by marginalizing white males and white youth with the objective of addressing racial imbalances. This lack of understanding between industry and the government has led to considerable confusion regarding the accountability of stakeholders in transforming the industry. This article presents the perspectives of ten mining executives on transformation in the South African mining industry. The theoretical description of transformation, as well as other mining stakeholders’ interpretations of transformation. is presented. Qualitative data from interviews with mining executives demonstrates their understanding of transformation through rich descriptions, interpretations, and implications in their contexts. The findings demonstrate that transformation in the mining industry is not simply about race and gender, but about cultural change, a change in mind-sets, embracing diversity, equalizing rights and opportunities, and attaining social justice. Moreover, transformation is clearly a gradual process. The article concludes with a recommendation for the definition of transformation to be corroborated with the views of mining executives and that of the Constitution of South Africa. This will create an overarching, simplified definition of transformation that can be accepted and interpreted by all stakeholders.

Jan 1, 2016

By L. Naude, J. Cloete, S. Engelbrecht

The results of an investigation evaluating whether an industrial plant, currently operating using sodium isobutyl xanthate (SIBX) as primary collector for sulphide minerals (mainly chalocopyrite), could adapt to operate using an alternate primary thiol collector without compromising plant and metallurgical performance. Initial laboratory scale flotation tests identified commercial dithiophosphate (DTP)-based and thionocarbamate (TC)-based collectors, that when blended, showed potential to replace the incumbent SIBX primary PGM collector. Industrial plant trail results show that there was no deterioration in recovery of 4E PGMs, even at a lower concentrate grade when operating the plant on the identified (DTP + TC)-based collector blend compared to SIBX. The effect on Cr2O3 content in the final concentrate was also found to be negligible. The (DTP + DTC)-based collector blend also showed promise in terms of plant adaptability in accommodating a new primary specialty collector blend. These observations highlighted the potential of replacing xanthate primary collectors with alternate thiol collector blends for PGM flotation. Keywords: PGM, xanthate replacement, specialty collector, sodium iso-butyl xanthate (SIBX), dithiophosphates (DTP), dithiocarbamates (DTC)

Jan 1, 2020

This International Mine-Surveying Conference will take place in Budapest (Hungary) from 5 to 14 June, 1972. Detailed information can be obtained from the Mine-Surveying Working Committee of the Hungarian Mining and Metallurgical Society. Write: OMBKE Bányaméröi Munkabizottsag Budapest, V., Szabadsag ter 17, Hungary. SYMPOSIUM ON NICKEL The &apos;Gesellschaft Deutscher Metallhiitten-und Berglaute&apos; is holding a Symposium on nickel on 24-25 September, 1970 at Wiesbaden, on the occasion of the G.D.M.B. Annual Meeting. Some 24 papers will be presented by metallurgists from many important companies around the world. Information may be obtained from The Secretary, G.D.M.B., Postfach 210, 03392 Clausthal-Zellerfeld, German Federal Republic. VISIT TO THE COUNCIL FOR SCIENTIFIC AND INDUSTRIAL RESEARCH On 23rd June, 1970, members of the Institute visited the C.S.I.R. in Pretoria. More members had booked for this tour but the current flu epidemic caused cancellations which was unfortunate. The visit was organised with military precision, which prevented detailed discussion of any particular subject, but provided a bird&apos;s eye view of a large number of interesting projects. The visit was packed with interest for all and those requiring further information were invited to contact the relevant divisions afterwards. Or Denkhaus welcomed the delegates and stressed the importance of integrating research efforts with industry&apos;s requirements. An excellent colour and sound film was shown which depicted the work of the Rock Mechanics division. This showed very clearly methods used for preparing rock samples and demonstrated the machines and instruments for the various tests. It made one realise the extent to which this research has been integrated with the actual mining situation. The fullscale experiments underground showed the failure of pillars under applied loads and were very interesting. This is undoubtedly a film which all mining people should see. After the film the rock mechanics laboratories were visited where the actual machines were seen and described. We then visited the metal and strength mechanics sections where the metallurgists were able to see some interesting experiments and tests. We also visited the Aeronautics Research group where a large 1 000 hp wind tunnel was inspected. We were told enough about this to realise something of the complexities involved in the design and operation of a closed circuit tunnel of this type. The tunnel is used for tests on models which are necessary for the design and modification of aircraft. After a very excellent lunch at the C.S.I.R. recreation centre, the delegates attended two lectures-one by Mr. Mandersloot of the Chemical Engineering group, who outlined the varied functions of this group and told us something of their work. Of particular interest was the research into the suitability of various South African manganese ores for dry cell batteries. Work on the thickener settlement studies interested the metallurgists. The second lecture was given by Mr Donaldson of the National Building Research Institute. This Institute has about ten divisions each of which covers a particular aspect of building research. The work of the soil mechanics division was described in detail and illustrated by coloured slides. This was particularly interesting and demonstrated clearly how building failures result from lack of attention to detail of construction where unstable soil conditions exist. Cracks in walls of compound blocks brought the subject home forcibly to the mining delegates. This division has also caried out important work on sinkholes and sUmes dams and produced some positive results. Altogether the visit was most interesting and enjoyable. It was made more worthwhile because the emphasis was on the work being carried out and not on just seeing the laboratories. The Institute is greatly indebted to the C.S.I.R. and its staff for the very excellent arrangements made.

By X. Gumede

Mud houses are common structures in most South African rural homes closer to the mining operations. Fulltime dwellers in these properties are often the elderly. The mine codes of practice and the South African legislative instruments attempt to define the damage criteria to limit the effect of the blast-induced noise and ground vibrations to different structures. All these assessment criteria are based on the peak particle velocity and noise generated during blasting. The South African safe limit criterion that was adopted was initially derived from the international standards, which were then used as a local guideline. This paper evaluates the currently adopted safe limit criteria used in South Africa for a mud house, currently rated at 6 mm per second and 120 decibels to134 decibels, for blast-induced seismicity and noise, respectively. Further, a study was performed on a residential house near a coal mine (5.26 km) based in Mpumalanga following numerous complaints by the owner, launched at the mine and to the Department of Minerals and Petroleum Resources. The aim of the study was to measure the magnitude of blast-induced triggers experienced at the aggrieved homestead and to establish if there is a likelihood that an irritation or damage may be caused by these triggers. The seismometer was installed at about 2 m from the mudhouse, from 1 July 2022 to 31 of July 2022. Five blast-induced triggers were recorded during the period showing an average of 0.09 mm/s and 121 decibels for blast-induced seismicity and noise, respectively. The results obtained indicated a maximum seismicity of 0.15 mm/s. This seismicity was below the perceptible vibrations obtained from daily home activities such as walking, jumping, and door slamming, which produce 0.8 mm/s, 7.1 mm/s, and 12.7 mm/s, respectively. Seismicity was therefore not likely to have caused any annoyance and or damage. For noise, the results indicated a maximum of 123 decibels and an average of 121 decibels from five events recorded. A literature review suggests that slight damage may occur when airblast frequencies match the natural frequencies of structures at 120 decibels. Based on these results, it can be concluded, therefore, that the noise, rather than seismicity, is more likely to be the cause of damage to the structure assessed. For improvement, a new approach is proposed based on relating the safe limits to the structural and human response.

Dec 15, 2025

By C. Ntsele

Stirred milling technologies have firmly established themselves in concentrator circuits as energy-efficient alternatives to tumbling ball mills. High and continued increases in electricity costs, coupled with the ever-increasing power consumption by primary grinding circuits due to declining head grades of ore-bodies, provides a compelling case for these technologies. Additionally, the ability to successfully deploy stirred milling in coarse grinding applications extends the range of use in concentrators, thus increasing the opportunity matrix for energy optimization in a flowsheet. This paper therefore details methodologies and strategies that can be applied to evaluate the optimum stirred milling solution for different concentrator applications. These methods and strategies will focus specifically on the two major stirred mill machine types; namely, gravity-induced (VERTIMILL? grinding mill and Nippion-Eirich tower mill) and fluidized (SMD, Isamill?, Knelson-Deswik mill, etc. ). Finally, case studies from circuits across industry and laboratory tests will be used to illustrate the energy benefit from the use of stirred mills.

Jan 1, 2012

By B. Matsetela, S. Amos, V. Nkuna

"The Kamoa-Kakula copper project—a joint venture between Ivanhoe Mines, Zijin Mining Group Co. Ltd, and the government of the Democratic Republic of Congo—has been independently ranked as the world's largest undeveloped high-grade copper discovery by international mining consultant Wood Mackenzie. It is a very large, near-surface stratiform copper deposit with adjacent prospective exploration areas within the Central African Copperbelt, approximately 25 km west of the town of Kolwezi and about 270 km west of the provincial capital of Lubumbashi. A phased development approach is currently envisaged. The first phase of the project involves the development of a 6 Mt/a underground mine and surface processing complex (dual stream concentrator) at the Kakula deposit, a discovery announced in early 2016. The second phase involves an integrated 12 Mt/a two-stage development, beginning with initial production from the Kakula mine, to be followed by a subsequent, separate underground mining operation at the nearby Kansoko mine, along with the construction of a smelter. Project description and locationThe Kamoa–Kakula project comprises a newly discovered, very large stratiform copper deposit with adjacent prospective exploration areas, located within the Central African Copperbelt in Lualaba Province, Democratic Republic of Congo (DRC). The Kamoa–Kakula project lies approximately 25 km west of the town of Kolwezi and about 270 km west of Lubumbashi. Ivanhoe owns a 49.5% share interest in Kamoa Holding, an Ivanhoe subsidiary that currently owns 80% of the project. Zijin Mining owns a 49.5% share interest in Kamoa Holding, which it acquired from Ivanhoe in December 2015 for an aggregate cash consideration of US$412 million. The remaining 1% interest in Kamoa Holding is held by privately-owned Crystal River.The Kamoa–Kakula project consists of the Kamoa exploitation licences (exploitation permits 12873, 13025, and 13026, which cover an area of 397.4 km2) and one exploration licence (exploration permit 703 covering an area of 12.74 km2). The Kamoa exploitation licences, approved 20 August 2012, grant Kamoa Copper the right to explore for, develop, and exploit copper and other minerals, for an initial 30-year term, expiring on 19 August 2042. The permits can then be extended for 15-year periods until the end of the mine’s life."

Nov 1, 2018

By M. Handley

The Witwatersrand Basin contains by far the most gold ever found, and has hosted mining from its discovery in 1886 to the present. For many years, South Africa was the world’s largest producerof gold, nearly all of which came from the Witwatersrand. Since 2000, South Africa has fallen back several positions because of declining gold output. There are many complex and varied reasons for this; however, declining gold resources in the Witwatersrand Basin are not one of them. As far as the author knows, there are no qualified estimates in the literature of gold remaining in the Witwatersrand Basin. This paper collects mining data from several sources and then, using elementary gold accounting and error analysis, attempts to estimate the amount of gold remaining in the Witwatersrand Basin. It includes gold underground in existing and defunct mines, in evaluated ore resources, and dumps. Compiled data from 1887 to 2019 shows that 50 200 t of gold were produced by Witwatersrand mines, while it is estimated that a further 48 100 t remainunderground, both within and outside of mine leases, a further 1 600 t on the surface in tailings,and an unknown amount in rock dumps. Nearly all of this gold will remain inaccessible with current mining methods, and major technical developments in mining will be necessary before any of the gold can be categorized as a code-compliant resource or reserve. To win this prize, the mining industry will have to rethink its approach to mining, both in old mining leases and in the unexploited ground. It will also have to find effective means of preventing gold theft and informal mining, which are on the rise.

Apr 5, 2023

By Y. R. Murthy, S. Angadi, A. K. Bhatnagar, S. K. Tripathy, L. O. Filippov

Dolomite is an essential raw material for the refractory industry, a flux in the iron and steel industry and also for the extraction of magnesium metal. Generally, particle size reduction, screening and classification are used for the preparation of the high-grade sized material for different applications, whereas low-grade fine fractions are not utilised. These fines or low-grade overburdens are dumped at the mine site for future utilisation, which creates environmental issues along with inadequate space management. In the present investigation, a detailed study was carried out to decrease the silica content of the low-grade dolomite fines from Gomardih , India, containing 28.6% CaO and 20.1% MgO along with 8.3% silica. Different process flow sheet options were evaluated with a combination of dry classifier, wet classifier, gravity concentrators as well as flotation. Different process variables were assessed along with mineralogical characterisation to optimise the process for efficient rejection of siliceous gangue minerals. Results indicated that dolomite, calcite and quartz are the major mineral phases present in the ore along with other minor minerals. It was concluded that two-stage flotation was an effective process for the reduction of silica up to below 1% after grinding to a particle size below 212 μm. A process flow sheet with a combination of gravitation air classifier and flotation can produce a concentrate with silica content below 4.5%. Keywords: Dolomite, flux, dry classification, flotation, characterisation, beneficiation

Jan 1, 2020

By M. Z. Emad, M. U. Khan, A. ur Rehman

The use of stemming plugs in surface blasting is gaining popularity because of the environmental, technical, and economic advantages. Although previous studies have established the operational effectiveness of different types of stemming plugs, evaluations of the economic and ergonomic impacts are lacking, thereby hindering their application in many mining operations. Consequently, a significant proportion of mining operations end up performing less efficient blasts. We evaluated the effectiveness of three types of stemming plugs by conducting multiple full-scale production blasts. The results show that stemming plugs reduce the need for secondary blasting and increase blast performance. An economicanalysis showed that the incorporation of stemming plugs can reduce blasting costs significantly.

Jul 1, 2021

By S. Sinha, S. Ganguly

"In an opencast mine explosives are used for fragmentation of rock. Inefficient use of explosive energy in an opencast operation produces excessive ground vibration, which is measured by peak particle velocity (PPV). To mitigate ground vibration, it is essential to develop a model to predict PPV. At present empirical models are used. These models are based on only a few input variables, hence they fail to take into account the effects of the myriad factors that cause ground vibration. Due to lack of explicit knowledge about the complex mine blasting system the scope of application of mathematical and statistical modeling techniques is limited. The artificial neural network (ANN) technique is a learning algorithm that can remove some of these limitations and can be applied to predict PPV. In this paper an ANN model is developed for prediction of blast vibration using 248 data records collected from three coal mines with diverse geomining conditions. The correlation coefficient between measured PPV and model output was found to be 0.96 and the average error percentage 11.85. The ANN model output was compared with the output of three empirical models that are widely used for prediction of PPV. The correlation coefficient between the PPV predicted by an empirical model and measured PPV data was 0.63 and the relative error percentage 38.47. This result demonstrates the superiority of the ANN model compared to empirical blast models. By using site-specific structural discontinuities as input the model performance can be further improved. Sensitivity analysis and 3D plotting were used to gain further knowledge about blast-induced ground vibration. IntroductionIn an opencast coal mine explosives are used for fragmentation of coal and overburden. If the explosive energy is not fully utilized it causes blast-induced ground vibration, which may damage nearby structures. Ground vibration is expressed as peak particle velocity (PPV). During different stages of mine planning and operation, it is necessary to use a ground vibration prediction model for blasthole design. Selection of the modelling technique is crucial. Mathematical and statistical modelling techniques have limited application because of the lack of explicit knowledge about the complex mine blasting system. Vogiatzi (2002) highlighted the problem of multicollinearity in case of statistical modeling techniques. Mutalib et al. (2013) stated that mathematical models are unable to capture the nonlinear relationship between several blasting-related parameters due to the complexity of the model input data. However, the difficulty involved in modelling complex blast vibration problems can be removed by adopting an alternative soft computing modelling approach. One of the soft computing techniques is the artificial neural network (ANN). Ragam and Nimaje (2018) developed an ANN model for predicting PPV using six input variables. Kosti et al. (2013) stated that the conventional predictors fail to provide acceptable prediction accuracy. They showed that a neural network model with four mine blast parameters as input could make significantly more accurate on-site predictions. Sayadi et al., (2013), using a database from Teheran Cement Company limestone mines, found that a neural network resulted in maximum accuracy and minimum error. Khandelwal and Singh (2009) developed an ANN model using 150 data records from an Indian coal mine with site-specific rock characteristics and geomining setting. Khandewal and Singh (2007) built a ground vibration prediction model for a magnesite mine using four prediction variables with 20 data records. Kamali and Ataei (2010) predicted PPV in the structure of the Karoun III power plant and dam using an ANN. El Hafiz et al. (2010) evaluated ground vibration predictors using data from a single-station seismograph at a limestone quarry in Egypt."

Feb 1, 2019

By T. Uysal

The increasing demand for rare earth elements (REE) in highly strategic sectors such as hybrid electric vehicles, renewable energy, communication technologies, and the defense industry has made REE production methods important. In recent years, studies on REE have increased rapidly; however there are many studies on REE, there are not enough studies in the literature on the economics of the beneficiation process. RE ores are generally leached after beneficiation by gravity, magnetic and flotation methods. In this study, direct leaching, attrition scrubbing and leaching, and flotation and leaching methods are evaluated economically based on the data for the Mountain Pass (MP) facility. According to the sensitivity analysis performed as a function of capital cost (CAPEX), operating cost (OPEX), and rare earths oxides (REO) recovery, REO recovery has the biggest effect on the process economies. Although the flotation method entails additional investment and operating costs, transportation and operating costs are significantly reduced result of the higher grade and recovery. The flotation method is more profitable, with larger NPV and IRR values and a shorter payback period.

Jul 2, 2022

By I. Ince, S. Kahraman

Preparation of suitable core specimens for physico-mechanical testing s not always possible, particularly for soft and clay-bearing rocks. Although several indirect test methods have been proposed to predict the properties of rocks, specimen preparation from soft rocks for some indirect tests is still difficult. For such cases, the needle penetration test has been developed. In this paper we present a study on the predictability of the physico-mechanical properties of pyroclastic rocks from the needle penetration index (NPI). The NPI, uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), density, and porosity tests were performed in the laboratory on specimens from ten different locations in Turkey. Correlations were established between the NPI values and the physico-mechanical properties. Strong correlations were observed between NPI and both UCS and BTS. General correlations were found between NPI and both density and porosity.

Sep 6, 2023

By L. Roux

This review was initially motivated by the author’s own experience in attempting to reconcile run-of mine production tons with the Coal Resource and Reserve estimation of mineable, in-situ tonnages. The primary scientific measurements and observations that are collected during exploration at the beginning of the value chain will have a profound effect on the future of the mining operation. Due diligence must be exercised during the planning of a new mine and during the life of an existing mine. The comments provided by the technical and economic assessment group of Venmyn Deloitte confirmed the need for this critical review. They found the reporting of Coal Resources in South Africa to be inconsistent. This was particularly problematic in the Waterberg Coalfield in Limpopo Province. In this coalfield there are two types of coal deposit present. The first is comprised of the thick intercalated, cyclic coal and shale/mudstone sequences of the Volksrust Formation. This overlies multiple coal seams within the Vryheid Formation, each of which is thick enough to be extracted as an individual raw coal unit. On the other hand, the interbedded coal and shale seams of the Volksrust Formation require beneficiation to separate the coal from the shale. The review examines practices and methods, investigates alternatives, provides checks and balances, and tests these against actual production reconciliations. In conclusion, the best estimates of the mineable, in-situ tonnage will be obtained from the air-dry raw material density. These estimates should be adjusted afterwards to allow for free moisture content. The adjustments are derived from reconciliation data. The greatest contributing factor to the over-estimation of Reserve tonnages is the moisture content of the raw material. This fluctuates significantly under varying conditions in situ, as well as upon exposure to the natural environment. The air-dried density of the raw material includes inherent (structurally bound) moisture within the matrix. It provides credible tonnage estimations of raw material available while also providing an indication of voids within the volume of material being assessed. The calculated solids percentage can be used to adjust the specific gravity, which is determined via the Archimedes principle. This will supply a representative estimate of the material to be mined.

Nov 1, 2021