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By R. T. Rudd

The impact of slimes-dam formation on water quality and pollution by R. T. RUDD*, B.Sc., AMI (S.A.) CE (Visitor) This paper discusses the mechanics of pollution by slimes dams in the gold- and fluorspar-mining industry, as well as that caused by coal dumps and slurry dams. The effect of coal mining on two typical rivers in Natal is shown and the implications discussed. The implications and trends of sulphates pollution on the Rand Water Barrage in the Vaal River are discussed. The spread of pollutants (sulphates and fluorides) from the Reef and elsewhere, and the impact on urban use and agriculture downstream of the barrage, are illustrated. Conclusions and future policy are outlined.

Jan 12, 1973

By M. T. G. Davis, J. V. Cleasby, H. J. Wright

Mining practice in the Kimberley Division of De Beers Consolidated Mines Limited by J. V. CLEASBY. B.Sc.. A.R.S.M. (Fellow). H. J. WRIGHT. B.Se.. M.Sc.. (Fellow). And M. T. G. DAVIES. B.Sc. (Visitor) T his paper highlights the changes that are taking place at De Beers Consolidated Mines Limited in mining methods, mechanization, and employment practices. De Beers has four underground mines in Kimberley itself (Dutoitspan, Bultfontein, De Beers, and Wesselton), and two open-cast mines outside Kimberley (Finsch and Koffiefontein). Emphasis is placed on the new method envisaged for Koffiefontein when it becomes an underground mine. The paper also includes notes on chemical drilling and on winding practices.

Jan 12, 1975

By J. A. Kinnaird, B. J. Youlton, K. L. Youlton

Methods for treating and processing refractory gold ores are well established. However, what is less well understood is how the formation of the gold-bearing deposits affects gold processing and extraction. In order to evaluate the effect of ore genesis on gold extraction a number of South African gold deposits were studied. These included complex Pilgrim’s Rest samples as well as refractory Fairview, Barbrook, and Consolidated Murchison samples. We found the refractory nature of gold ores is controlled by a limited number of well-understood mineralogical factors. Solid solution gold is linked to low temperature and pressure conditions in fine-grained sedimentary lithologies, while reactive pyrrhotite can form from hydrothermal fluids associated with mafic magmatic rocks. These formational controls can be used to identify and avoid complex deposits at a desktop study phase, or address and reduce complications further along the pipeline using early mineralogical studies.

Jun 1, 2021

By A. G. Journel, CH. Huijbregts

"Centre de Morphologie MathématiqueSpecial problems arise in the evaluation of lateritic-type orebodies (Ni-Co, bauxite) or, more generally, orebodies affected by surface weathering. In this type of orebody, the vertical grade distribution shows, from the hangingwall downwards, a systematic increase followed sometimes by a certain decrease, or vice-versa. These trends appear together with irregular variations from one drill bole to the other.The problem is to characterize a vertical structure that is representative not only of the drill hole but of an entire panel or zone of influence, in order to define mineable thicknesses for given cut-off grades. The vertical grade distribution observed on the drillhole is replaced by a new curve, called 'derive' (drift), which is computed by 'universal kriging'.Once the vertical study is completed, new 'service-variables' are defined in the horizontal plane, such as mineable thickness and the corresponding average grade, economical functions (combination of the grades of several minerals). The local and global estimation of these variables can then be performed by a simple bi-dimensional kriging plan. The global estimation is summed up by several tonnage-cut-off grade curves.The practical valuation according to the above scheme of a New Caledonian lateritic nickel orebody is presented."

Jan 1, 2014

By A. Chagnes

This paper presents a modelling tool that can be used to predict the behaviour of solvent extraction processes. In particular, this model allows calculating metal extraction efficiency as a function of pH, solvent flowrate, stripping flowrate and aqueous feed flowrate in the mixers-settlers. This model is applied to the recovery of cobalt from acidic chloride media by using CYANEX® 272 as extractant diluted in kerosene. Keywords: Cobalt, mixer-settler, modelling, solvent extraction

Jan 1, 2020

By A. Tosun

"The size distribution of the muckpile formed as a result of open pit blasting operations has a considerable effect on the efficiency of loading, hauling, and crushing. Various researchers have developed specialized computer software that uses image analysis methods for determining the size distribution of the muckpile. However, these methods have some limitations. One of the most important of these limitations is that the very fine fragments in the muckpile cannot be used in the size distribution calculation. In this study, 18 test blasts in total were carried out in two limestone quarries belonging to Batiçim Corp. in Izmir, Turkey. A new model was developed in order to ensure that very fine fragments are used in the size distribution calculation. The size distributions of the test blasts were calculated by both the Wipfrag computer program and the new model. Correlations were established between the muckpile size distributions determined by both methods and the parameters determining the efficiency of the loader. IntroductionThe size distribution of the muckpile formed as a result of open pit blasting operations has a considerable effect on the efficiency of loading, hauling, and crushing. Various researchers have established certain correlations for predicting the efficiency of the operations according to the muckpile size distribution so that production can be carried out economically (Tunstall and Bearman, 1997; Nielsen and Kristiansen, 1996; Workman and Eloranta, 2004; Michaud and Blanchet, 1996; Frimpong, Kabongo, and Davies, 1996; Osanloo and Hekmat, 2005; Molotilov et al., 2010). In these studies, the 50% passing size (X50) is generally used. These methods rely on the correct measurement of the size distribution of the muckpile formed by the blast. The most reliable measurement method would be to subject the entire muckpile to a sieve analysis, but this is obviously impracticable. Therefore, computational method based on image analysis have been developed. These include IPACS (Dahlhielm, 1996), Tucips (Havermann and Vogt, 1996), Fragscan (Schleifer and Tessier, 1996), Cias (Downs and Kettunen, 1996), GoldSize (Kleine annd Cameron, 1996), Wipfrag (Maerz, Palangio, and Franklin, 1996), Split Desktop (Kemeny, 1994), PowerSieve (Chung and Noy, 1996), and Fragalyst (Raina et al., 2002). In these methods, the size limits of the fragments forming the material are determined by image analysis on photographs of the muckpile. However, the computer software has some limitations. It does not take into account the third dimension of the muckpile, nor the size distribution of very fine fragments. In particular, the fragment size ranges below 2.5 to 3 cm cannot be determined, and therefore these cannot be included in the muckpile size distribution. However, the muckpile formed by a bench blast contains a wide range of particle sizes (Tosun et al., 2015)."

Oct 1, 2018

By H. L. Monro

Contribution by B. K. Martust I congratulate the author on his interesting paper. In my view, the establishment of the level at which South African gold output is at some kind of optimum is an interesting though somewhat academic exercise. Contribution by D. M. Hawkins* The thesis of the paper is a very interesting one, but, before it is used as the basis of any firm proposals to restructure the mining industry, which changes may be irreversible, one should be very sure that the basis of the calculations is sound. Contribution by P. J. Niewenhuizen* The hypothesis advanced by Mr Monro that the demonetization of gold in August 1971 introduced a major new policy variable, namely the supply-pricejdemand-price relationships, into the decision making process touches on a matter that has never really been given serious thought by the industry. Contribution by B. G. Kingsman* As a co-worker on the development of an econometric model for supply and demand in the world gold market with Mr H. L. Monro, it would perhaps be useful for me to make some comments on the various points raised in the discussions on his paper.

Jan 1, 1984

Advanced process and equipment analytics have been around for a while. However, with accessible IT infrastructure and site maturity, it is possible to analyse, monitor, and control processing plants and equipment easily. These various disparate systems provide different reports requiring the involvement of various personnel and attention to different reporting platforms. For efficient harnessing of the systems? capabilities, as well as effective improvement and monitoring of process and equipment, a single point of entry is required. A process and equipment optimization solution was required at a concentrator in South Africa, focussing on the product stream of platinum group metal (PGM) concentrate from the UG2 Reef. The investigation of data to identify strategies for optimization was required to allow visibility into plant operations to guide operators, an easier method to identify process loop problems, identification of imminent equipment failures, and advanced process control to optimize throughput and stability. A collaborative effort between the client and General Electric Intelligent Platforms (GEIP) investigated data-driven solutions to each of the problems. With the focus on process optimization and asset monitoring, as well as equipment monitoring, a combination of approaches was utilized to address the various problem areas that were identified. Each was implemented separately in the control layer of the plant IT infrastructure. The integration was done in a centralized web-based reporting tool that integrated the detailed results from the various solutions. On the process control side, monitoring of control loops was included by calculating performance statistics that were reported daily to identify sub-optimally performing control loops and indicating potential problems. The advanced process control solution for this site includes a surge tank controller, stabilizing flow through the flotation banks, and preventing the surge tank from overflowing or running empty. Equipment monitoring was investigated, for preventative maintenance, by making use of statistical data models to indicate imminent equipment failure. These predicted alarm events included the cause for failure, drilling down, and allowing focus on a specific variable for preventative action. The results included a more stable flow through the mill, with fewer stoppages due to surge tank overflows or running empty. The causes for process drift could be identified and operators could react early. Alarms warning of equipment failure 2½ and 4 months in advance were identified in an offline analysis.

Jan 1, 2012

By J. K. Pothal, S. Basu, R. Barik, P. K. Senapati, A. Dubey

The aim of this paper is to study the characteristics of limestone particles (size varies from 4 mm to 20 mm) during its transportation from open cast mines through pipes. The influence of four different size fractions of limestone samples (4–6 mm, 6–10 mm, 10–15 mm, and 15–20 mm) on pipe flow characteristics during vertical transport in a 100 mm NB hose pipe was investigated. The flow velocities in the vertically lifting pipe was varied from 0.95 m/s to 2.78 m/s and a rotary feeder of 2 to 4 tonne/hr. capacity was employed to feed the limestone samples to the lifting pipe. The pressure drop data for the different size fractions of limestone samples at different mixture velocities were analysed. The effect of input volume fraction and superficial velocity of limestone samples on hold-up ratio were discussed. It was indicated that there was no substantial increase in pressure drop of slurry samples in the studied range of concentrations (CW = 4.22% - 12.54%), particle size, and low to medium range mixture velocities with respect to water run head loss data. The hold-up for the larger size fractions (15–20 mm) of limestone samples was found to be significant as compared to smaller size fractions, which may be due to terminal settling velocities of individual fractions of the studied samples.

Mar 4, 2025

By P. Mühlen, C. Nelson

Process control optimisation depends a lot on the availability of timely data from production to give operators a chance to make adjustments before potential process upsets or disruptions happen. A lot of data is already available with newer and updated machine technologies, but what about the process upsets coming from the raw materials that we use? They are natural products and therefore they are not of a stable composition or mineralogy. The production process depends on a certain chemical or mineralogical stability of the raw materials when they come to a roaster, kiln or sintering stage. Only then can the proposed reactions take place and the equipment be operated at stable temperatures. Laboratory analytical technologies have the limitation that they depend on representative samples and have a long time delay. Therefore online (real time) analysers are used nowadays in mining applications to obtain an early indication of the actual mined or to-be-processed ore. Most available technologies can only analyse inorganic content on an oxide or elemental level. Near infrared (NIR)- based online analysers can overcome that limitation and give a real time analysis of organic as well as inorganic composition, if required on a mineral level. The paper will present two case studies where the NIR online technology was successfully adapted.: a) Optimising refractory gold ore processing at the Goldstrike roaster operation b) Optimising the sinter process at a Japanese manufacturer. Keywords: Analyser, NIR, online, realtime, gold, roaster, iron ore, sinter, mineral phase analysis

Jan 1, 2020

1. Book reviews Quantitative texture analysis, edited by H. ,}. Bunge and C. Esling. Deutsche Gesellschaft fur Metallkunde, 1982. 551 pp. Reviewer: L. 1\'1.Matthews Boundary element methods in solid mechanics by S. L. Crouch and A. M. Starfield. Reviewer: J. A. C. Diering World mineral statistics 1976-1980. Produdion,' exports,' imports, by Institute of Geological Sciences. London, Her Majesty's Stationery Office, 1983. £18.00 Reviewer: R. P. King 2. New publications Canadian mines,. perspective from 1982. Mineral Bulletin MR 197. Supply and Services Canada, Hull, Quebec K1A 059, Canada. Copper' s changing cost structure, by Commodities Research Unit Ltd (31 Mount Pleasant, London, WClX OAD, England). Petrology of metamorphic rocks, by M. Suk. New York, Elsevier, 1983. 320 pp. U.S. $68.00. Applied geomorphology, by H. Th. Verstappen. New York, Elsevier, 1983.442 pp. U.S.$95.75. Tin and its uses, no. 137, by the International Tin Research Institute. Greenford, the Institute (Fraser Road, Greenford, Middlesex UB6 7AQ, England), 1983. 3. New journals Mining Science and Technology, edited by C. 0, Brawner and B. N. Whittaker, is to be published quarterly in one volume per year by Elsevier. Aluminium, published monthly by Aluminium -Verlag GmbH, P.O. Box 1207, D-4oo0 Diisseldorf 1, F.R. Germany. DM 690.00 per annum. Rock mechanics The South African Institute of Mining and Metallurgy is to hold two schools on 'Rock Mechanics in Mine Management' at the University of the Witwatersrand, Johannesburg, from 23rd to 27th January, 1984, and from 30th January to 3rd February, 1984. The Federation of Societies of Professional Engineers The Federation of Societies of Professional Engineers (FSPE) has been a member of the World Federation of Engineering Organisations (W FEO) for many years and has regularly sent delegates to the biennial conference of that organisation. Second progress report by ASRET The Professional Engineers Joint Council was estabislhed in 1960 and initially its main fWlction was to represent the interests of engineers. Explosives technology The Center for Explosives Technology Research (CETR) has been established at the New Mexico Institute of Mining and Technology (Tech) in Socorro, New Mexico. International Tunnelling Association A conference entitled 'Ita Tunnels 1984' will be held in Caracas, Venezuela, from 2nd to 7th June, 1984. Automation The IFAC Symposium on Automation for Mineral Resource Development is to he held in Brisbane (Australia) from 9th to nth July, 1985.

Jan 1, 1983

By Brian W. Mackenzie

The mineral exploration environment has observable economic characteristics, the assessment of which provides guidelines for exploration planning in the mining company. The long-term survival of the mining company is directly dependent on successful exploration. Exploration planning contributes to successful exploration through the development of exploration strategies. The objective of exploration planning is to select exploration environments which will enable the mining company to realize best possible profit and corporate risk conditions. Thus, the formulation of exploration strategies is based on profit and corporate risk criteria. Strategic considerations include the selection of commodities as exploration targets, geographic concentration of exploration effort, the realization of acceptable survival conditions, and the structuring of an exploration programme to optimize the economic benefits of the exploration investment process.

Jan 1, 2014

"This paper challenges the traditional notion that mine planners need to plan production so as to incur the lowest mining cost. For a given mine configuration, a mine that increases its mining rate will incur increased mining costs. In an environment in which operations are fixated on cost reduction, a proposal that increases costs will not be readily accepted. Such a proposal requires financial justification—the increase in costs might be recuperated by the additional production. This paper evaluates the net present value (NPV) across a range of copper prices for two underground orebodies located at different depths, using a production rate of 300 kt per quarter and a scenario that introduces additional equipment and costs for 450 kt per quarter. The evaluation was based on the changes of NPV for the orebody located at a shallow depth compared with the orebody at a greater depth. Discrete event simulation combined with mixed integer programming was used for analysis. Unlike traditional sensitivity analysis, this study re-optimizes the mine plan for each commodity price at each production rate. The results show that, for the low mining rate at the final copper price, an NPV of A$1530.64 million is achieved, whereas an NPV of A$1537.59 million is achieved at a higher mining rate. Even though pushing mining rates beyond traditional limits may increase mining costs, this option may be beneficial at certain commodity prices, particularly when prices are elevated. IntroductionA traditional notion among mine planners is that mining rates should be planned in such a way as to reduce production costs. This concept generally relates to the mining rate that results in the highest machine utilization for the selected equipment. Although an existing mine may consider increasing its mining rate by adding equipment to a given mine configuration, this typically increases mining costs. In an environment in which operations are fixated on cost reduction, a proposal to increase costs may be very difficult to argue for. The value of the mine plan is well recognized as varying with the mining rate for a given orebody (Smith, 1997)"

Jan 1, 2017

By H. Zhong, S. Wang, Q. Sun

The flotation performance of 2-(benzylthio)-acetohydroxamic acid (BTHA) to diaspore was first evaluated by micro-flotation tests. The adsorption mechanism was further investigated through adsorption experiments, molecular dynamics simulation, zeta potential and X-ray photoelectron spectroscopy (XPS). The results demonstrated that BTHA had a stronger ability to collect diaspore in comparison with another diaspore collector, benzohydroxamic acid (BHA), especially under the condition of weak alkalinity, the flotation recovery can reach 90%. The more negative interaction energy (ΔE) between BTHA and diaspore from molecular dynamics simulation results revealed that BTHA had an easier adsorption ablity onto diaspore than BHA, which matched with adsorption results. The zeta potential and XPS revealed that Al atoms might bond with -C(=O)NHOH by formation of Al-O bonds. Keywords: Diaspore, flotation; adsorption; 2-(benzylthio)-acetohydroxamic acid

Jan 1, 2020

By X. Yang, G. D. Zhai

The prop is the most important part to ensure the proper functioning of hydraulic support. When the hydraulic support is impacted by the roof, the prop is prone to extrusion deformation, expansion, and even bursting. In order to study the stress on a doubly-telescopic hydraulic support prop under impact load, an impact simulation was carried out based on the drop weight method. First, the impact model of the hydraulic system of the prop was established in AMESim software and the dynamic response curves of the bottom and middle cylinder of the prop obtained. Then, according to the conservation of energy, the pressure formulaes in the hydraulic cylinder of the prop under impact load were derived and verified by the AMESim simulation results, and the maximum pressure on the inner surface of the hydraulic cylinder of the prop obtained. Lastly, the transient dynamic simulation of a hydraulic support prop was carried out in ANSYS Workbench software, and cloud diagrams of stress and deformation of the prop obtained using Workbench simulation. The AMESim simulation process describes the change in fluid pressure in the prop, and the pressure formulae can be used to estimate the internal pressure of the prop under impact load. The finite element analysis results show that the stress of the middle hydraulic cylinder is much greater than that on the bottom hydraulic cylinder under impact load, which can provide a reference for prop design.

Jul 2, 2022

By K. Lomberg

In this paper the process of sampling and assaying as it relates in particular to the platinum group elements (PGEs) is presented. A discussion of the geology of PGE deposits is included to provide an understanding of the mineralization that is considered necessary prior to sampling, as this has a direct bearing on the mineral resource estimate and also the selection of an appropriate mining cut. The discussion includes the selection of the sampling technique (drilling or face sampling), the size of the sample relating to the requirements of the laboratory, the potential mining cut, as well as a reference to sampling theory. The selection of an assay technique that is appropriate and will yield the optimal result based on sample turnaround, precision, accuracy, and cost is then considered. Examples are drawn from work undertaken on the Bushveld Complex (Merensky Reef, UG2 Chromitite Layer, Platreef) and Great Dyke (Main Sulphide Zone). A discussion of the appropriate QA/QC programme includes the chain of custody, CRM selection and the QA/QC process. Keywords sampling, assaying, QA/QC, platinum group elements.

Jan 1, 2014

By A. F. Silva, R. Dockendorff, J. M. Girao Sotomayor, V. F. Navarro Torres, C. Castro

This paper shows the importance of performing probabilistic analyses in open pits, especially for mine planning, which can lead to more efficient ore extraction and meeting the acceptability criteria for safety in mine slopes. Three-dimensional stability analyses were performed to evaluate the future geometry of a large open pit for iron ore extraction in Brazil. The strength parameters of the lithologies were calibrated using ruptures in the pit walls. After determining the factors of safety (FoSs) from the calibrated parameters, probabilistic analyses were performed using the total range of values of each parameter under different field conditions to verify the reliability of the initial analysis. In this sense, it was possible to plot the probability of failure (PoF) and the FoS on the graph of slope height versus slope interramp angle (IRA) for the future pit in each lithology. IRA recommendations are made for two scenarios: (1) the best scenario: dry without ubiquitous joints and (2) the worst scenario: the water table at 10 m depth with ubiquitous joints in the most unfavourable direction. The results show that probabilistic evaluation is an important tool for establishing alert mechanisms in slopes that can be termed stable.

Jul 2, 2022

The Institute was founded in 1894 as the Chemical and Metallurgical Society of South Africa. In 1904 it was reconstituted as the Chemical Metallurgical and Mining Society of South Africa and in 1956 it became the South African Institute of Mining and Metallurgy. The objects of the Institute are to advance the science and practice of mining and metallurgy, to afford opportunities for the interchange and recording of knowledge of mining and metallurgy and to ensure high standards of professional conduct and competence. Membership benefits include monthly issues of the Journal of the Institute, monthly General Meetings at which papers are read, symposia, excursions to mining and industrial concerns and the use of club facilities at Kelvin House. Technical journals received on an exchange basis are available to members at the Johannesburg Public Library. The current membership of the Institute is over 1,600. Membership applications are accepted from suitably qualified persons and the requirements for entrance to the various grades of membership are summarised below. Fellows shall not be less than 30 years of age, shall be university graduates in pure or applied science or shall produce evidence to the satisfaction of the Council that they have successfully completed a co-ordinated course of study in pure or applied science of at least three years' duration at an approved university or institution deemed by the Council to be of equivalent status. Members shall have been employed in senior technical positions in important mining or metallurgical undertakings for at least five years or they shall have practised as mining or metallurgical consultants for at least five years. They shall be practising their profession at the time of application. Entrance fee R10.00, Annual subscription RI7.00. Letters of designation: F.S.A.I.M.M. Members shall be not less than 25 years of age and shall be university graduates in pure or applied science, or shall have successfully completed co-ordinated courses of study in pure or applied science of at least three years' duration. They shall have been engaged in work of an approved technical character in the mining or metallurgical industries, of which not less than two years shall have been in positions of responsibility. A candidate shall be practising his profession at the time of his application. Entrance fee R8.00, Annual subscription RI5.00. Letters of designation: M.S.A.I.M.M. Associates shall be not less than twenty-five years of age, and shall have been engaged in positions of responsibility in, or associated with, the mining or metallurgical industries for periods of not less than three years. If, however, the candidate for admission to the higher grade of Associate, is at the time of his application, already a Student, he need satisfy the Council only that he is, at the time of his application, engaged in a position of responsibility in or associated with the mining or metallurgical industries. In all cases the applicants shall satisfy the Council that they are fit and proper persons to become Associates. Entrance fee R8.00, Annual subscription R15.00. Graduates shall be not less than 21 years of age and shall be university graduates in pure or applied science, or have completed co-ordinated courses of study in pure or applied science of at least three years' duration at an approved university or institution. They shall not remain Graduate members after attaining the age of 30 years without the permission of Council. Entrance fee R2.00, Annual subscription R10.00. Students shall be persons not less than 18 years of age who are being educated or trained in a manner approved by the Council, to occupy a technical position in or associated with the mining or metallurgical industries and who, furthermore, shall not have attained the qualification required for a higher grade of membership. They may remain Students until they have obtained the necessary qualifications for transfer to a higher grade of membership, but not after the end of the Institute's financial year in which they attain the age of 28 (twenty-eight) years. They shall then transfer to a higher grade to retain membership of the Institute. The Council may relax the provisions of this clause in such cases as it considers appropriate. Entrance fee nil; Annual subscription R3.00. Other. The Council has the power to elect to the grade of Fellow or Member, candidates who may not fulfil all the requirements for entrance to these grades but whose status, professional achievements and practical experience in mining or metallurgy justify such election. Applications. Requests for membership application forms should be addressed on the attached form to the Secretary, South African Institute of Mining and Metallurgy, P.O. Box 61019, Marshalltown, Transvaal.

By S. Bradshaw, A. Mabentsela

"Physical and numerical modelling methods were followed to identify mechanism(s) for tundish slag entrainment in a bare tundish and one with a flow control device (FCD).The physical and numerical models made use of water and paraffin to model steel and slag respectively. Observations from the physical model showed that the steel-slag interface remains immobile in both cases. Entrained paraffin formed droplets approximately 1 mm in diameter. Results from both models (numerical and physical) showed that in both cases (bare and FCD case), areas of high entrained slag concentration exist near the inlet region. The entrained slag concentration decreases towards the tundish endwalls.Flow patterns and velocities tangential to the steel-slag interface from the numerical model showed that slag entrainment in both the bare tundish and tundish with a FCD possibly takes place via two mechanisms. First, the slag moves across the steel-slag interface via mass transfer; secondly small velocities tangential to the interface at depths greater than 10 mm below the interface carry the already ‘entrained’ slag into the bulk steel phase. These tangential flow patterns are dominant in the inlet region, hence the high concentration of entrained slag in this region. IntroductionThe tundish serves as the last metallurgical vessel through which steel passes before solidifying in the moulds. It is in the tundish that the last traces of non-metallic inclusions should be removed, otherwise the inclusions carry over to the moulds and cause defects in the steel product. In the tundish, the slag is less dense than the melt and thus resides on the top of the melt. The slag provides a sink into which the non-metallic inclusions float to and dissolve. The slag also protects the melt from air and heat loss. However, when slag is entrained in the melt as a result of increased turbulence or shearing at the steel-slag interface, slag can become a source of nonmetallic inclusions.Numerous studies on flow patterns in the tundish have been carried out since the introduction of the tundish. These studies were aimed at improving the flow characteristics in the tundish (Chattopadhyay, Isac, and Guthri, 2010; Cloete, 2014; Jha, Dash, and Kumar, 2001; Jha, Rao, and Dewan, 2008;"

Jan 1, 2017

By M. -B. Kime

This study applies attainable region analysis to optimise cobalt recovery from oxidised ores via reductive leaching with sulphur dioxide and sulphuric acid. The attainable region framework enables systematic visualisation of trade-offs between cobalt yield and sulphur dioxide loss, guiding reactor network design beyond conventional mass balance modelling. Experimental column leaching trials, supported by validation runs, were conducted under controlled flow and reagent conditions. Kinetic parameters for cobalt dissolution and sulphur dioxide consumption were used to simulate reactor trajectories and construct attainable region envelopes. To ensure hydrodynamic realism, residence time distribution tests confirmed partial plug flow behaviour with dispersion effects, justifying the use of hybrid reactor models in the attainable region simulations. The results revealed that increasing recirculation ratios improves cobalt yield while reducing sulphur dioxide losses, with attainable efficiencies exceeding 90% cobalt recovery and < 20% sulphur dioxide loss. Importantly, the study proposes practical reactor network configurations for future implementation, including staged percolation columns with intermediate mixing zones, oscillatory flow reactors, and modular fluidised bed systems. These designs offer scalable pathways to translate attainable region-based optimisations into industrial practice. Compared to traditional modelling, attainable region analysis provides a geometric decision support tool that captures multi-objective trade-offs and reactor interactions, offering novel insights for continuous leaching system design. This work advances the application of attainable region methodology in minerals engineering by bridging theoretical optimisation with practical reactor design, supporting sustainable cobalt recovery from both primary ores and recycled feedstocks.

Mar 30, 2026