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By T. T. Matuludi

Kleinkopje Colliery has five Wemco drums that were installed and commissioned in 1978. Over the years, there have been remarkable changes in mining and geological conditions at the colliery. First, an increase in the percentage of fines was recorded, which resulted in an uneven split or an imbalance in silo levels between material feeding the cyclone (-12 mm) and Wemco drum (+12 mm) sections respectively. This problem was solved by doing modifications around the banana screens to allow finer material to the drums. The imbalance challenge was then followed by spontaneous combustion that takes place in situ and results in low product yield. The results obtained from efficiency tests indicate that although there is a limit in the percentage of -6 mm material in the feed, Wemco drums are still very efficient and applicable to the current mining conditions. These results also suggest that it is essential to lower the throughput when the drums are treating low yielding coal.

Jan 1, 2010

By H. Karabulut, S. Gündüz, K. Karacif, M. A. Erden

The corrosion properties of iron-based composite materials containing graphite and silicon carbide (SiC) reinforcement were investigated. The effects of silicon carbide reinforcement were investigated by adding 0.5% graphite and 1%, 2%, and 4% SiC. A powder metallurgy method was used to produce the composite samples. Iron, graphite, and silicon carbide powders were blended for one hour with a threeaxis mixer and then unidirectionally pressed under a pressure of 750 MPa. After pressing, the composite materials were sintered at 1100°C for one hour. The corrosion properties and microstructure, density, and hardness properties of the composite materials that can affect the corrosion properties were also investigated. It was determined that the pore ratio and hardness of the composite material increased, and corrosion resistance decreased, with increasing silicon carbide content.

Jun 2, 2022

By S. Banisi, S. Zare, M. Mahmoudi, M. Maleki-Moghaddam, M. Yahyaei

As the orebodies become more complex and lower grade, there is an increasing demand from crushing circuits for a finer product. When the product from a crushing circuit does not satisfy the requirements of the downstream processes, the cost of production increases. Thus, enhancing the performance of cone crushers through optimisation of their operating factors becomes important. One of the key factors affecting performance of cone crushers is the filling of the crushing chamber during the operation. The effect of varying the filling of the crushing chamber of a cone crusher was investigated. To assess the crusher performance, parameters such as crusher capacity, power utilisation, and reduction ratio were used. Extensive plant trials were conducted to obtain samples and operational data when the crusher chamber was 50% full (half-full) and 100% full, which is 300 mm above the top of the crusher chamber (super-choked condition). The results indicated a 62% difference in the crushing capacity when the crusher was operated in a super-choked condition compared to the half-full chamber level. In the super-choked condition, the size-specific energy at 12.7 mm was 20 % lower than that of the half-full condition. The Bond ball mill work index (BBWI) of crusher product indicated that the BBWI of the product of the super choked condition is 5.6% less than that of the product of half-full condition. This can be attributed to the generation of micro cracks in particles due to increase in the interparticle breakage when the crusher was operated in the super-choked mode. Keywords: Cone crushers, crushing efficiency, crushing chamber filling

Jan 1, 2020

By J. Petersen, T. Moyo

Waste Printed Circuit Boards (PCBs) are a metals-rich fraction of electronic waste (e-waste) streams, and globally it has been demonstrated that they can be recycled gainfully to recover the metals. Reported successful cases of PCB recycling are carried out in large volumes, using high-level technology and high capital investment smelter house operations. This presents entry barriers for recyclers in developing economies where capital may not be accessible, and the waste volumes are not sufficient to warrant large scale operations. Hydrometallurgical processes have the potential to provide an option for the scalable processing of smaller volumes of PCBs and can be set up at relatively lower capital costs. However, to date, the hydrometallurgical treatment options available rely on precursor communition and classification processes that also require high capital and energy costs. This paper presents an overview of the work done under the Minerals to Metals signature theme towards understanding e-waste recycling processes and developing pre-processing and characterisation of PCBs in order to unlock potential for local end processing in developing economies, using South Africa as a case study. The structure of PCBs is reviewed, and the current size reduction techniques and the subsequent leaching processes are discussed. Keywords: Printed circuit boards (PCBs), PCB structure, pre-treatment, liberation, ammoniacal leaching

Jan 1, 2020

"Chairman: Mr W. S. GALLAGHERRapporteur: Professor A. M. STARFIELDPapers:Long-term mine production scheduling by G. C. S. BurneAn application of linear programming to investment analysis by A. ErlandssonOptimizing medium-term operational plans for a group of copper mines by M. Splaine, D. C. Atkinson, W. Davison and L. SmithThe simulation of underground stoping and transport operations in gold mining by F. H. Touwen and N. C. JoughinProduction planning is a subject that lies at the interface between the computing centre and mine management. Discus¬sion during this session was thus largely concerned, directly or indirectly, with communication between computing and mining personnel, and as such was relevant to the symposium as a whole.Mr A. Weiss set the tone of this discussion by referring to `user-orientated systems'. He congratulated Mr Burne in this regard, pointing out that his long-term production scheduling program, as a computer system, was similar in approach to the manual system it replaced, and was therefore easily understood by planning engineers. He asked whether the schedule engineer had his 'hands on' the system, to which Mr Burne replied that the engineer did in fact spend several days running alternative schemes through the computer. Mr Weiss commented on the advantage of having terminals on site for this sort of engineer-computer interaction. He also commented on the flexibility of Mr Burne's approach to scheduling and how preferable this was to a one-step optimization package. This was brought home by a question from Mr H. D. Small: Mr Burne's program sometimes found it necessary to temporarily halt an advancing face, and he asked whether the logic of the program could be altered to avoid this (e.g. by suitably slowing down the rate of face advance). Mr Burne replied that it was in fact easier for the planning engineer to sort this problem out manually. The way in which the computer results were presented made it particularly simple for the production engineer to see how to avoid or remedy a stopped face.On the technical side, both Mr Weiss and Mr H. M. Wells questioned Mr Burne on the handling of grade control by his program. From answers by Mr Burne and his colleague Mr K. H. Thomson it emerged that a spot-check on grade every now and then was all that was necessary at Mufulira, and that the idea of actual grade control was more a question of short-term than of long-term planning."

Jan 1, 2014

By F. Nakhaei, Z. Pourkarimi

Tailings produced from the iron ore industry present many challenges due to the high economic and environmental impacts involved with their disposal. However, the relative scarcity of high-grade iron ores has driven manufacturers to recover and recycle these valuable tailings (secondary sources). This study aimed at the purification of ultrafine tailings with high sulphur content from an iron ore concentrator via reverse flotation to produce pellet feed fines. A specially designed flotation column featured with a nano bubble generator and a conventional bubble generator were employed to assess the effects of nano bubbles on the desulfurisation performance of iron ore concentrate under different operating conditions. Results obtained from this study indicated that the sulphur content of iron concentrate could be reduced from 1.2% to 0.22% in the presence of nano bubbles. Also, the results showed that use of nano-micro bubbles increased sulphur recovery 20% more, in comparison to micro bubbles. Keywords: Column flotation, iron ore, tailings, slime, nano bubbles, desulphurisation

Jan 1, 2020

By J. E. Dickinson, J. L. Sutherland, J. Zhou, M. J. Cole, K. P. Galvin

Interest in early gangue rejection has grown substantially in the minerals industry to reduce energy and water consumption arising from excessive comminution. Recent developments in coarse-particle flotation have proven successful by promoting a quiescent hydrodynamic environment to limit particlebubble detachment and by helping to convey more buoyant particles to the overflow. Current approaches also benefit from upstream classification to remove the finer particles ahead of the coarse-particle flotation. In this study, coarse-particle flotation was investigated experimentally using a novel hybrid gravity-flotation system called CoarseAIR™ that exploits the hydrodynamic advantages of the Reflux® Classifier. The system consists of a lower fluidised bed housing, with a system of inclined channels above. The inclined channels enhance the segregation and hence rejection of intermediate through to relatively coarse particles containing little or no surface liberation. This approach overcomes the need for pre-classification, while offering strong transport of coarse particles made buoyant through their attachment to air bubbles. The paper explores the strong relationship between the solids transport to the overflow and the input gas flux, showing firstly the potential for significant mass rejection at the relatively low gas fluxes, and robust performance in terms of recovery across the full range of gas fluxes. Keywords: Flotation, inclined channels, coarse particle flotation, Reflux Classifier

Jan 1, 2020

By B. Rezai, Z. Pourkarimi, M. Noaparast, S. Chehreh Chelgani

Nanobubbles (NBs) flotation separation can be an indicator for improving the efficiency of fine particles through the conventional process. Since flotation reagents such as frothers can reduce bubble size, they can potentially be used for the generation of NBs and develop a selective NB flotation separation. This study explored the flotation separation of fine phosphate particles from their associated minerals in the presence of NBs, which were generated by using a phosphate flotation reagent (Flo-YS: collector-frother). The results of flotation tests showed that in the presence of NBs, the flotation efficiency was significantly improved. However, in the presence of NBs, surface chemistry analyses (Fourier Transform Infrared Spectroscopy and High-Performance Liquid Chromatography) illustrated that the collector adsorption on the surface of phosphate particles decreased. A comparison between outcomes of various phosphate flotation conditions indicated that increasing the flotation efficiency in the presence of NBs may be due to the aggregation of fine particles by the generated NBs, and also selective adsorption of NBs (hydrophobisation) on the surface of particles. In other words, generating NBs by selective collectors may increase efficiency and decrease the collector consumption of a flotation process. Keywords: Phosphate, selective separation, fine particles, collector-frother, efficiency, mechanical flotation cell

Jan 1, 2020

By S. G. Mgenge, J. D. Steenkamp

Tronox Namakwa Sands operates two ilmenite smelters for the production of high-titania slag and low-manganese pig iron. Slag or metal is tapped from one of two product-specific, bi-level tap-holes. In this paper the refractory design specific to the tap-hole refractory layout is described, as well as practices for slag and metal tapping and refractory maintenance. Further developments planned are briefly described.

Jan 1, 2014

By А. Klemyatov, T. Vologdina, U. Gordeeva, S. Zbinets, А. Kalugin, N. Rozhdestvenskiy

The plants integrated in the PhosAgro group of companies perform processes from scientific research to the project, from ore mining to shipment of fertilisers and feed additives to consumers. An extensive process chain maintains smooth interaction at all stages from research to production. As an example, the paper shows the revamp of two beneficiation plants (ANOF-2 and ANOF-3), requiring a comprehensive approach to task solving. The intention of the revamp was to increase the total yield of apatite and nepheline concentrate, taking into account the gradual decline in the quality of ore being processed and ensuring the yield stability of final products during re-equipment of the plants. At ANOF-3, the crushing and grinding cycle was modernised, the production of nepheline concentrate was implemented, and the capacity of apatite flotation, dehydration, and drying was increased. At ANOF-2 a new process chain was implemented for the production of apatite concentrate in workshops previously used for the production of nepheline concentrate. The main building was withdrawn from operation, where ore grinding, apatite flotation and apatite concentrate thickening had been carried out. The total increase in apatite concentrate yield at two beneficiation plants was 1.3 times. A further increase in concentrate production is planned. Keywords: Apatite, nepheline, fertilisers, beneficiation, flotation, column flotation machines, revamp, fine screening

Jan 1, 2020

By R Linares

For centuries, diamond's superlative properties have earned it a reputation as the 'dream' material for mankind in its search to create advanced applications. Until recently, this dream has been realized only in the use of diamond for gemstones and abrasive applications where several tons of diamonds are now used on an annual basis. The vision of having large, high quality diamond as part of a broad engineering tool-kit for many diverse high tech industries is now becoming a reality however, with the advent of early stage commercial availability of single crystal and poly crystalline CVD diamond.

Jan 1, 2010

By More-O&apos, R. C. Ferrall, J. W. Wilson

Discussion: M. D. G. Salamon* (Fellow): The theoretical principles behind the techniques of calculation used by the authors was formulated and published during the period 1962- 65. These principles, together with their practical implications, were summarized in a review paper in 1966.1 Now, in February, 1970, we have this long and comprehensive paper discussing the practical application of the theory. I think this is good progress. The large number of practical examples treated in the paper clearly demonstrates not only the skill and knowledge of the authors, but also the versatility of the techniques of analysis. I feel that the techniques described by the authors, and their improved versions, will revolutionize mine planning. I suggest that no shaft system or stoping layout should be planned in future without an adequate rock mechanics analysis. It seems that it will be progressively more difficult to white wash mistakes in rock mechanics and attribute their costly outcome to normal mining risk. We should not, however, become complacent. There is still a lot to learn and do in the future. I do not want to discuss tonight the question of further research but instead, I will raise two other problems which may hinder the future progress of practical rock mechanics. To carry out work similar to that described in the paper, mine managements require men who are capable of doing the work and who have the most efficient techniques of analysis at their disposal. As a research engineer I have been associated with the development of techniques of analysis. I can assure you that these have undergone an amazingly rapid development during the last six years. We have seen the change from the use of the electrolytic tank analogue and manual integration to the method described by the authors, that is, to the employment of the automatic network analogue and computer integration. But this is not the end. In a recent paper Prof R. P. Plewman2 and his co-authors described a completely digital technique. Here the process of calculating on- and off-reef quantities is integrated into one computer run. But these sophisticated methods of computation are useless without men to make intelligent use of them. During the last few years a new breed of mining engineers has appeared on the scene - the Rock Mechanics Engineer. I feel it is timely to call the attention of the senior members of this Institute to the fact that this new breed will succeed in carrying out its duties in a valuable manner only if we manage to attract to its ranks young engineers of the right quality. The requirements are high. The top rock mechanics engineers have to be good mine planners and they have to understand the essence of sophisticated theories. Without these attributes they will not succeed in the long term and the industry will not gain the benefit of available knowledge. To attract this quality of engineers the industry will have to ensure that rock mechanics is accepted by all concerned as a career which could lead to the top echelons of our profession. Finally, I would like to make one or two remarks concerning Part I of the paper. In Sections 3.1 and 3.2 the authors describe methods of determining the normal stress on the reef plane and the convergence distribution in the excavations. The description as given applies only to a horizontal reef. When the reef is inclined the situation is more complex since a shear component of stress on the intact reef and a ride component in the excavations must then also be determined. These can be calculated by methods similar to that described in the paper.3 The practical application of the method of calculating the released energy (Section 3.4) is in the comparison of various stoping layouts to establish an order of preference in terms of decreasing rates of energy release. To carry out these comparisons effectively, the calculations must be carried out in a manner by which the values of energy per unit area obtained are comparable. I would like to note in this respect that the method of calculation given in the paper is valid without reservation only if there is no elastic contact between the hanging and foot walls in the mined-out area. If there is contact then the calculated energy values are correct only if the mined out area is increased in small steps during the analysis. My second point in this regard is concerned with the practical method of calculation as described in Sections 3.4 (ii)-(iii). Firstly, I would like to suggest that the energy calculation should be carried out, as far as possible, by using always the same scale on the analogue. Secondly, the reading of current on a pin should be followed by the removal of that pin to obtain the corresponding reading of potential. The product of these two values will be proportional to the energy released during the mining of the small area corresponding to that pin. The method suggested by the authors tends to mask possible danger points in the layouts, since they obtain an average value for a time period, say, for six months.

By T. N. Matveev, V. V. Getman, A. Yu. Karkeshkina, L. B. Lantsova, N. K. Gromova

Sulfide-type tin deposits in Russia are characterised by the complex mineral composition of ores and dump products of their processing. Tin-sulfide ores contain industrial quantities of copper, lead, zinc, tungsten, silver, rare and trace elements (indium, scandium, etc.). In addition, the ores are characterised by uneven dissemination of sulfide minerals (chalcopyrite, galena, arsenopyrite, etc.) and tin minerals (cassiterite, stannine, etc.). X-ray phase and spectral analysis, scanning electronic microscopy (SEAM), laser SIM and AFM microscopy helped to identify the selective fixing of sodium dibutyl dithiocarbamate (DBDTC) on chalcopyrite and galena, as well as the tall oil fatty acids (TOFA) and IM-50 on cassiterite. For the first time, collectors and flocculants of slurry fractions of silver and tin, thermomorphic polymers TMPF were used to isolate more than 80% silver from the tin tailings of the Solnechny mine into a copper-silver rough concentrate. It has been established that preliminary ultrasonic treatment and desliming according to the 0.02 mm class removes up to 20% of sludge material, which impairs the process of gravity separation. The combined flotation-gravity scheme using new reagent compositions helped to obtain tin concentrate with a tin content of 5.42%, which meets the requirements for further metallurgical processing (at least 5%). This work was supported by the RSF according to the research project No. 17-17-01292. Keywords: Flotation, flotation reagents, tin-sulfide ores, casiterite, adsorption, flocculation

Jan 1, 2020

By H. Vuthaluru, O. Kavianipour, C. -Z. Li, N. Suresh, D. Sahu

The paper describes a CFD model developed for 76mm Dense Medium Cyclone (DMC) using Ansys Fluent Software to gain insights into the separation of particles according to their size and density. The simulation used in this paper includes the Reynolds stress model to predict the turbulence inside the cyclone body. An Eulerian-Eulerian multiphase CFD model was applied to model a number of physical aspects such as the separation of coal particles and the segregation of magnetite media solids. The experimental results generated in a laboratory scale DMC were used for the validation purpose and the predicted results of CFD have been validated for the flow splits of water, magnetite and coal. The simulation results obtained from the Eulerian-Eulerian multiphase model revealed that the prediction agreed with experimental results, and matched reasonably well in terms of the mass flow rates of water, magnetite and coal. Furthermore, the partition curve of the DMC when mapped for the separation of - 3.0+0.50 mm size also showed to be in agreement with the experimentally obtained curves. The gravity of cut (SG50), also predicted by the Eulerian-Eulerain multiphase CFD model, was found to be in the vicinity of observed experimental value of SG50. Keywords: Dense medium cyclone, Eulerian-Eulerain multi-phase modelling, computational fluid dynamics, cut gravity (SG50)

Jan 1, 2020

By E. Moosavi, K. Tolouei

In mine production scheduling problems are well-known, where most are categorised into deterministic and non-deterministic NP-hard problems because of their complexity. Many researchers have attempted to solve the problem by applying various optimisation techniques. While using traditional methods they observed extreme difficulty in solving highly complex problems. In the 1990s, many researchers addressed long-term production scheduling (LTPS) by using simulated annealing, the genetic algorithm, the tabu search algorithm, and the ant colony algorithm. These algorithms are known as the meta-heuristic algorithms, and have proved to be the most efficient algorithms for solving LTPS thus far. The firefly algorithm is one of the best methods for visualising problems related to LTPS, and provides the best possible optimisation. It is one of the simplest methods, and easy to apply to any NP-hard problem. The experimental, and comparison with other recently published algorithms shows that the proposed algorithm is feasible, and is an effective approach for long-term production scheduling problems. The results indicated that a better solution is obtained by the proposed method, compared to other methods in terms of cumulative net present value, and average ore grade. Additionally, the CPU time via the proposed model is roughly 2.52% higher than the other method.

Sep 1, 2021

By M. L. Mahlatji

Mechanical alloying of an equiatomic mixture of crystalline Ti and Pt elemental powders in a high-energy ball mill formed an amorphous alloy by solid-state reactions. Mechanical alloying was carried out in an argon atmosphere at a rotation speed of 1200 r/min and a 20:1 ball-to-powder weight ratio, for time intervals of 4 to 40 hours. At an intermediate stage of mechanical alloying, scanning electron microscopy showed the formation of characteristic layered structures of inhomogeneous composition within the powder particles. X-ray diffraction analysis showed the gradual disappearance of crystalline Bragg peaks and the emergence of broad amorphous maxima as milling progressed. The amorphization process was completed after 8?12 hours. The amorphous state of the product indicated that temperatures during processing did not exceed the crystallization temperature of the alloy.

Jan 1, 2014

By F. Smit

Mining and plant disciplines can benefit from pre-concentration of UG2 platinum ores in a dense medium separation (DMS) plant. The main benefit of DMS is the selective discard of waste from the feed stream, thus improving project economics while reducing the power and water requirements for processing. On the mining side, with the correct combination of variables, implementing DMS as a pre-concentration step can reduce cut-off grades and, as a result, increase ore reserves. In addition, the use of DMS technology gives the mine team the opportunity to consider alternative mining methods for an operation. The challenges of balancing the mining tonnage, methods, and resulting grades with the process plant size, recoveries, and DMS discard volumes have resulted in the development of a model to optimize value on new projects or existing operations. This paper will focus on these benefits from a mining and plant perspective, quantifying the water and power savings, and look at the economic benefits of pre-concentration and the effect of metal prices, plant feed grade, and DMS efficiency in different mining environments.

Jan 1, 2012

By M. Frenzel, K. Bachmann, M. Rudolph, R. Tolosana-Delgado, E. Schach, M. Buchmann, L. Pereiraa, K. G. van den Boogaart, N. Kupka

Geometallurgy - the science of predicting the behaviour of ores along the value chain based on their geological and mineralogical characteristics - has barely moved beyond process minerology studies. These studies typically link process behaviour to the mineralogical and microstructural characteristics of pristine or processed ores in a qualitative or semi-quantitative manner. Eventually, a trial-and-error optimisation of the operation is achieved. However, to deliver on its promise, geometallurgy should progress beyond this current approach to a fully quantitative understanding of process behaviour, including the various uncertainties involved, namely predictive geometallurgy. One of the barriers currently hindering this development is the neglect of most ore characterisation data obtained in geometallurgical studies. This is mostly due to the large extent of this information exceeding the capacity of conventional software. To address this challenge, we developed a data mining platform consisting of an SQL database, an R front-end in-house package, and back-ends to interpret data from several analytical instruments. This platform enables the use of the statistical and data mining power of the R open-source environment for any geometallurgical study. Potential applications range from ore characterisation to process understanding and forecasting, and from geostatistical prediction to operational control and optimisation. The scripting abilities of R allow for the: 1) processing of many streams in loops, thus freeing the user from repeating tedious click-and-drop tasks; 2) computation of virtually any derivate or aggregate quantity from the data; 3) distribution of the work among several processor clusters; and 4) keeping of a log file for the calculations done. This contribution presents the building blocks of this platform, and illustrates with several examples its potential to enable predictive geometallurgy. Keywords: Data mining, entropy, kernel methods, LASSO regression, predictive geometallurgy

Jan 1, 2020

By N. Hanief

This research involves the investigation of phase transformations in the platinum-chromium coated system. Single-layer 0.1 µm platinum coatings were deposited via electron beam deposition on 99.98 percent pure chromium substrates. Specimens were subjected to systematic heat treatment in a vacuum furnace at 900°C for up to 20 hours. Phase formation and the changes in surface morphology were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM).Both CrPt and Cr3Pt phases are formed during heat treatment for different times at 900°C. Significant changes in the morphology of this coated system were detected after heat treatment at 900°C for 20 hours.

Jan 1, 2012

By R. Degel

Submerged arc furnaces and electric smelters are applied in numerous metal and slag production lines. Particularly in ferroalloy and non-ferrous metal production, like silicon metal, platinum group metals, calcium carbide, and copper, the units are an essential part of the production technology. Most of these electric furnaces are considered to be highly energy-intensive units. The high level of required electrical power is defined by the process. SMS developed several measures to reduce the overall electrical energy consumption of these metal production lines. In particular, the following measures contributes to a lower energy consumption: improved electrical efficiency with intelligent design and application of components, minimizing the heat losses from the furnaces with a balanced cooling/refractory systems, minimization of process steps (such as elimination of agglomeration), recovery of energy, process optimization (resulting in higher metal yield) and the achievement of higher recovery rates, enlarging furnace capacity to reduce heat losses, and maximizing the power-on time. This paper gives an overview of the above-mentioned solutions.

Jan 1, 2012