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By O. I. Rychkova, M. N. Sycheva, E. V. Poryadochnova, G. V. Sedelnikova

Deposits of copper-porphyry type occupy a leading position in the mineral resource base of the world copper industry. They are characterized by large and gigantic scales, often complex composition, their development is carried out in an open way. The raw material base of the Russian copper industry is mainly sulfide copper-Nickel and copper-pyrite ores. Exploration of copper-porphyry deposits and the creation of long-term large mining facilities on their basis is one of the most promising and priority tasks for the Russian industry. This task is especially acute for the copper enterprises of the Urals in connection with the depletion of copper - pyrite ore reserves. In recent years, Russia has carried out a large complex of studies on the composition and technology of processing of copper-porphyry ores of different subtypes. In this work the complex poor copper-molybdenum-gold ore of one of the deposits is investigated. The chemical and mineral composition of the ore containing 0.49% copper, 0.020% molybdenum, 0.39 g/t gold, 5.85 g/t silver was determined. The forms of finding metals and their distribution by size classes are established. The dependence of extraction of metals into concentrates of collective-selective flotation on the size of ore grinding, pH of the medium, reagent consumption is shown. Under optimal flotation conditions, copper concentrate with 18.6% copper content and 92.32% extraction and molybdenum concentrate with 21.5% molybdenum content and 73.4% extraction were obtained. With a high concentration of molybdenum in selective flotation products, it is possible to conclude about the expected molybdenum concentrate with a content of 45% and a recovery of 70%. The associated extraction of gold and silver into copper concentrate is 76.8 % and 73.4%. Keywords: Collective-selective flotation, copper, molybdenum, porphyry ore, grinding, pH, reagents

Jan 1, 2020

By G. G. Rogers, A. Vna Der Linde, N. B. Strydom, W. H. Van Der Walt

Changes in the level of serum vitamin C in mineworkers by N. B. STRYDOM, M.Se., Ph.D. (Illinois) (Fellow), G. G. ROGERS, M.Se. (Pta) (Visitor), W. H. VAN DER WALT, B.Se. (Poteh.) (Visitor), and A. VAN DER LlNDE, B.Se. (O.F.S.) (Visitor) The levels of serum vitamin C in the blood of mineworkers were determined on the first and fifth days of the normal heat-acclimatization period (i.e., before and after exposure to heat) and again after I, 2, and 4 months of underground employment. Supplementary vitamin C was administered to the men during the heat-acclimatization period. Six groups of 20 men featured in the study and, except for one of the two 4-month groups, all the values were obtained after a full shift of underground work. It was found that adequate levels of serum vitamin C were maintained during the heat-acclimatization period, and the 250 mg of vitamin C given daily to each man must therefore be regarded as sufficient. The serum vitamin C decreased significantly with time of exposure to underground conditions, showing that the vitamin C utilized during heat stress is more than that provided in the men's diet. At the end of 4 months, not a single subject had more than 0,4 mg of serum vitamin C per 100 ml, most of them having only 0,3 mg per 100 ml; 90 per cent of the men had had more than 0,4 mg per 100 ml during the acclimatization period. It is therefore recommended that the mineworkers' diets should be supplemented with 100 to 200 mg of vitamin C per man per day.

Jan 5, 1977

By A. A. Hazell

Mine management by objectives by A. A. Hazel Published in the Journal, September 1972 DISCUSSION H. H. McGREGOR Mr Hazell is to be complimented on a thoroughly down to earth analysis of the uses ot which work study can be put and the benefits of properly applying it in the management of underground production.

Jan 9, 2007

The comments by Mr Chaston were constructive and much appreciated. Considering firstly the recovery of cassiterite from fine deslimed material. A size distribution analysis shows that 58 per cent of cassiterite in Union Tin flotation concentrate reports in the minus 15 micron (quartz) size range. This is achieved at a recovery of 67 per cent and concentrate grade of 42,6 per cent. It is of interest to note that at Altenberg in East Germany 85 per cent of the tin in deslimed minus 43 micron material is recovered into a 14 to 16 per cent Sn concentrate using para-tolyl arsonic acid as collector. Reconcentration of this material is then carried out using two shaking table stages which recover 53 per cent of the tin in a 50 per cent Sn concentrate. Flotation was resorted to after recovery rates of 35 per cent and concentrate grade of 30 per cent had been achieved in a 275 ton per day plant comprising 130 tables. Tests on tabling of deslimed minus 43 micron material have not been carried out at Union Tin. The cost of equipment actually associated with cassiterite flotation amounts to about R60 000. The

If the Journal is to fulfill its mandate to the mining and metallurgical industry, it needs to expand its readership and, by implication, membership of The South African Institute of Mining and Metallurgy. This we hope to do by increasing the appeal of the Journal to a wider audience through the inclusion, in addition to our high-quality research papers, of equally high-quality papers, articles, and contributions that will be of interest to our less research-minded members.

Jan 1, 1990

By R. Singh, A. K. Dhawan, M. Dixit, H. Dev

ABSTRACT: The modulus of deformation of rock mass is an important engineering parameter required for the design of foundation of hydraulic structure and to study the interaction of rock mass and the structure at the foundation support. Different equipment and techniques are used to arrive at the design modulus value. Since any error in the estimation of modulus values results in multiplication of its effects in the analysis, it is necessary to know about the reliability of testing equipment and procedures. In the present study modulus values obtained by different in-situ equipment at different project sites have been compared. KURZFASSUNG: Der Verformungsmodul von der Felsenmasse ist technisch ein wichtiger Parameter, den man zur Konstuktion des Grunds fuer die Hydro – Tektonik, benoetigt um auch die gegenseitige Beeinflussung der Felsenmasse und der Tektonik am Traggrund zu betrachten. Verschiedene Geraete und Methoden werden angewandt, um den Ausfuehrungsmodul -Wert zu erreichen. Es ist erforderlich, die Zuverlaessigkeit der Pruefeinrichtung sowie des Verfahrens zu kennen, da irgend ein Fehler in der Abschaetzung von Modulwerten in der Analyse zu einer Vervielfachung ihrer Einwirkung fuehrt. In der vorligenden Arbeit werden die Modulwerte gewonnen aus unterschiedlichen Einrichtungen an Ort und Stelle and verschiedenen Projekt -Stellen mit einander verglichen. SOMMAIRE: Le module de deformation d’une roche est un parametre important pour la conception et realisation des ouvrages hydrauliques ainsi que pour etudier l’interaction de la roche et de la structure d’appuis de base. De divers equipments et techniques sont employes pour determiner la valeur de ce module de conception. Puisque l’effet d’une erreur d’evaluation du module devient multiplie dans l’analyse, il est necessaire de savoir la fiabilite des equipments et des methods qu’on ulilise. Dans cette etude, on a compare les valeurs des modules obtenues en employant les equipments in-situ aux sites differents de projets.

Jan 1, 2003

By L. E. Salinas-Farran, S. J. Neethling

Key variables in heap leaching include permeability, mechanical stability and mass transport. All of these properties can be manipulated by agglomerating and curing the ore before stacking it into heaps. The chemical and structural evolution of the agglomerates during curing is key to improving agglomerate properties and, ultimately, heap performance. It is possible to image the internal structure of agglomerates using SEM/EDX (e.g. QEMSCAN or MLA), although these methods are destructive and do not represent the 3D structure of the agglomerates. A non-destructive alternative is to image the agglomerates using X-ray Microtomography (XMT). Not only does this provide 3D information, it also allows the same samples to be repeatedly scanned, allowing the time evolution of the agglomerate structure and chemical composition to be tracked. In this paper we compared the behaviour of ores agglomerated using a combination of sulphuric acid and ferric sulphate with ones in which chloride ions are added to the recipe, since chloride leaching is gaining in popularity as a chemical alternative to bioleaching for sulphide ores. We tracked the curing process beyond the typical time scales to see the impact that this has on both the agglomerate structure and the subsequent leaching behaviour. Keywords: Heap leaching, curing extent impact, leaching kinetics, ferric-chloride leaching

Jan 1, 2020

By M. Le Roux

The dewatering of coal, and particularly fine coal, continues to challenge coal prepatration engineers to find a cost-effective solution. With known world oil reserves being depleted daily, it is envisaged that the future price of coal may justify the use of thermal drying to achieve lower coal product moisture levels. The effect of exposure of the coal to elevated toemperatures on the mechanical strength of the coal was investigated. It was found that temperature does not play a major role in determining the volume breakage of a particle and that other variables such as orientation during impact has a much greater influence. A double breakage mechanism was reported during the grindability tests. Surface, as well as volume breakage, occurs for the first 4 minutes while only surface breakage takes place thereafter. Due to this double breakage action, it was found that exposure to temperature does play a role in the amount of breakage and breakage rates during grindability tests. It was also concluded that a particle will break to an optimum size due to impact, after which only its surface will grind away as it is subjected to breakage forces.

Jan 1, 2008

By T. Copland

"The decreasing availability of resources amenable to surface operations has led to increasing numbers of underground mines, with trends indicating this will continue into the future. As a result, there is a need for additional optimization processes and techniques for underground mines, with many analogous methods having already been developed for surface mining. Current methods for design and optimization of stope boundary selection and scheduling mainly involve heuristic methods which focus on a single lever. Individual optimality may be approached, but globally optimal results can be obtained only by an integrated, rigorous approach. In this paper we review previous methodologies for stope boundary selection and medium- to long-term scheduling and highlight the need for an integrated approach. Previous integrated approaches are reviewed and an improved modelling system proposed for shorter solution times and greater applicability to mining situations. Randomly generated data-sets for gold-copper mineralization are used to investigate the model performance, describing solution time as a function of data complexity.IntroductionThe increasing need for mineral resources is driving an increase in underground mines. Lower grade mineralization with larger amounts of overburden is becoming economically viable due to technological advances; however, the software and tools available for strategic underground mine planning are not well developed. Advances in the methods used to determine underground layouts and scheduling must occur to ensure underground mining is as optimized as open pit operations, as underground mining involves many more technical restrictions.The process of determining stope boundaries and scheduling is an example of an aspect of underground mining amenable to optimization (Topal and Sens, 2010). The current industry standard for medium- and long-term planning for sublevel stoping (SLS) is to exclusively determine stope outlines and then determine an appropriate sequence and schedule accordingly. This process violates the concept of optimality as integrating the constraints imposed by pre-determining stope outlines does not allow for considerations in scheduling to influence boundary planning (Ataee-Pour, 2005). An integrated planning process that combines both stope outlines and scheduling would approach the optimal solution and hence generate more value for operations. This investigation specifically deals with the underground sublevel stoping (SLS). Other underground mining methods such as block caving, sublevel caving, and room and pillar mining have unique characteristics and therefore require specific stope boundary/production scheduling considerations."

Jan 1, 2016

By H. Askari-Nasab, S. Upadhyay, A. Moradi-Afrapoli

Material handling in surface mines accounts for around 50% of the operational cost. Optimum truck dispatching plays a critical role in the reduction of this operational cost in truck and shovel surface mines. Researchers in this field have presented several mathematical models to solve the truck dispatching problem optimally. However, a critical survey of the literature has shown that three significant drawbacks exist in the available truck dispatching models. The published models underestimate the importance of the interaction between truck fleet, shovel fleet, and the processing plants. They also disregard goals set by strategic-level plans. Moreover, none of the available models account for the uncertainty associated with the input parameters. In this paper we present a new truck dispatching model that covers all of these drawbacks, using a fuzzy linear programming method. The performance of the developed model was evaluated through implementatin in an active surface mining operation. The results show a significant improvement in production and fleet utilization.

Sep 1, 2021

By D. Clement

A comparison between hydraulic and pneumatic rockdrills by D. CLEMENT The regulation of compressed-air reticulation systems is very poor compared with that of electrical systems; this means that electrohydraulic rockdrill systems offer greater flexibility, additional power being readily available at the working face. Hydrometallurgy A new journal devoted to all aspects of the aqueous processing of metals is scheduled to appear this year. Entitled Hydrometallurgy, the journal will be published in quarterly issues, one volume per year. Mineral dressing Contributions are invited for the Symposium on Recent Progress in Mineral Dressing in South Africa, which is to be arranged jointly by the South African Institute of Mining and Metallurgy and the National Institute for Metallurgy. Mineraalbereiding Bydraes word verlang tot die Simposium oor Onlangse Vordering met Mineraalbereiding in Suid-Afrika wat gesamentlik deur die Suid- Afrikaanse Instituut vir Mynbou en Metallurgie en die Nasionale Instituut vir Metallurgie gereel gaan word. Rock mechanics The Sixteenth Symposium on Rock Mechanics is to be held at the University of Minnesota from 22nd to 24th September, 1975. The Symposium is the official Symposium for 1975 of the International Society for Rock Mechanics (I.S.R.M.), and the Council for I.S.R.M., consisting of members from 25 countries, will meet during the Symposium. Powder metallurgy The annual meeting on powder metallurgy organized by The Metals Society is this year to be held at the Stratford Hilton Hotel, Stratford-upon-Avon (the notification did not include the date of the meeting). Vacation School The South African Institute of Mining and Metallurgy has great pleasure in announcing its intention of holding a vacation school on the topic of electric-furnace melting. NIM reports Report no. 1681 The determination of sulphur and phosphorus in chromite. Report no. 1687 The viscosities and electrical conductivities of slags associated with the production of high-carbon ferromanganese alloys.

Jan 3, 1975

John Keith Elers Douglas recently retired from active participation in the activities of the South African Institute of Mining and Metallurgy after over forty years of diligent and valuable service to the Institute. This account of his contributions to the mineral industry and associated organizations is presented as a tribute to all his hard work and dedication. Mineral processing The Fourteenth International Mineral Processing Congress, sponsored by the Canadian Institute of Mining and Metallurgy, is to be held in Toronto from 22nd to 27th October, 1982. The theme of the meeting is 'Worldwide industrial application of mineral technology'.

Jan 1, 1981

By V. van der Merwe, C. W. Siyasiya

"A petrochemical company experiences premature thermal fatigue failure of the casting moulds used in catalyst production. The aim of the project was to find an alternative alloy that would outperform the current low-alloy cast steel used for the moulds. Based on their thermo-fatigue properties, 3CR12 ferritic stainless steel and H11 tool steel were chosen for testing and comparison with the currently used BS3100 B7 cast steel. Samples of each material were subjected to temperature cycling in a Gleeble 1500TM thermo-mechanical processing simulator, followed by surface analyses. The main parameters derived from the test work were the total true strain, the hot strength of the materials, and the number of cycles to failure. Additionally, the coefficient of thermal expansion for each material was measured using a Bähr dilatometer. H11 tool steel yielded the best performance by way of having the fewest surface cracks, the lowest total true strain per cycle, the most cycles to failure, the highest hot strength, and the lowest coefficient of thermal expansion.IntroductionThe Catalyst Manufacturing Plant (CMP) is a dusty environment with temperatures higher than ambient. Molten mill scale (magnetite, Fe3O4) is tapped from the electric arc furnace into the casting moulds at temperatures close to 1600°C. After 10 seconds the magnetite is quenched with a water spray for 50 seconds to a minimum temperature of 400°C. Sometimes there is residual water in the pans from the cooling fog process (water sprays) in the empty mould. In a typical plant, the factory produces 40–44 batches a day containing between 150–300 moulds, depending on the time required for the specific batch (Buchholz, 2014). The typical batch in the CMP usually weighs about 6 t. The thickness of the tap, speed of the casting belt, and tilting angle all affect the number of moulds per batch.One of the main problems faced during the molten mill scale casting is the premature failure of the casting moulds. Cracks initiate on the surface of the mould, which is in contact with the hot catalyst, and propagate into the interior of the mould. Cracks are generally concentrated in the middle area of the mould where the catalyst makes first contact with the mould, and which experiences the highest temperature fluctuations. This suggests that the cracks are caused by thermal fatigue during the casting process."

Jan 1, 2016

By L. I. Boshoff, S. Gracie

This paper discusses pilot and laboratory-scale metallurgical test work conducted on bulk samples from a low grade heavy mineral deposit and provides an overview of basic practical metallurgical techniques applied to ascertain the suitability of existing production plants to process material from this orebody. Previous investigations have shown this specific orebody to be more challenging in terms of mineral beneficiation as it has a high gangue mineral content. Test work was conducted on targeted stratigraphic units based on lithology and assay results to enable identification of the stratigraphic units portraying quality issues. Unit specific metallurgical pilot work has never been conducted on any of the RBM orebodies and is a new field currently being explored. During this investigation focus was placed on potential quality and yield issues for ilmenite product, with particular reference to CaO quality. A basic evaluation of zircon and rutile separability was also conducted. The test work was conducted using a comparative baseline methodology with metallurgical test work methods specifically aiming at mimicking the existing production plant as closely as possible. This enabled not only the likely metallurgical performance to be assessed but also indicated whether current plant design would be suitable to process the low grade ore types into products of acceptable quality at acceptable yields. The methods and findings discussed in this paper indicate that although there is considerable variation between different units, a blended feed can be successfully processed. With unit specific metallurgical data applied to the existing geological block model, expected yields and recoveries using current plant designs could be predicted.

Jan 1, 2007

By F. T. Cawood

The new mineral royalty regime for South Africa was signed into law in November 2008, with its main objective being to compensate the State for the depletion of public minerals through a royalty charge payable from 1 March 2010. The aims of this paper are to establish the potential impact of mining royalties on State revenues, industry affordability, and explore whether the dual formula system is likely to encourage miners to become refiners. It also measures the royalty dispensation against economists? tax standards in an attempt to make a judgement on the ?equity? of the new system. This paper argues that most stakeholders should be comfortable with most of the requirements of the Act for most of the time. However, the new regime is unlikely to motivate miners to become refiners, as the benefit of the reduced rate on refined minerals appears to be insufficient to justify the additional costs to refine the mineral resource to the prescribed states of beneficiation.

Jan 1, 2011

By C. Chapman, M. G. Reading, M. P. Amsden

Ecstall Mining Limited, a subsidiary of Texas Gulf Sulphur Company, operates the Kidd Creek Mine, a 10000 tons per day base metal producer, near Timmins, Ontario. Two different types of ore are mined and milled: copper-zinc and silver-lead-zinc. At the highly automated Ecstall concentrator the ores are processed by selective flotation in three individual circuits. One of the most important metallurgical tools for process control is a sample system incorporating continuous on-stream X-ray analysis. Recently this system was automated further by the addition of computer control of reagents for two copper-zinc flotation circuits. The computer programs, utilizing optimum seeking methods and smelter contract terms, have increased copper recovery by 1.1 per cent, zinc recovery by 1.4 per cent, and have reduced reagent costs by 16 per cent. Although not expected, copper and zinc concentrate grades were improved slightly as well.

Jan 1, 2014

By I. Nolet

Matte tapping is one of the most critical operations of a matte smelter. Every smelter has developed particular matte tapping practices and tap-hole repair strategies that are often based on the experience of the smelter personnel. As a result, very little information has been published on these critical topics. This paper aims at providing the information gathered from a survey conducted in the PGM and Ni industries on matte tapping practices and tap-hole maintenance strategies for different PGM-Ni matte smelting operations.

Jan 1, 2014

By T. Nghipulile, M. Moys, M. Bwalya, H. Simonsen

The quest for efficiency in comminution is an ongoing concern as comminution usually constitutes a major cost component in the metal production industry. Such improvements can be made by circuit optimization or development of more efficient equipment. A novel crusher, known as the rotary offset crusher (ROC), promises to deliver in this space. The ROC was invented in 2002 by Michael Hunt, Henry Simonsen, and Ian Sinclair, but failed to garner enough support to progress to production. The original design concept was recently rekindled, and a laboratory version of the crusher has been built and commissioned at the University of the Witwatersrand. The crusher is simple in design, with two cylindrical discs that are parallel to each other, and, as the name implies, there is an offset between the vertical axes of the discs. The top disc has a conical section on its lower face, and this creates a crushing zone between the opposite faces of the two spinning discs. Centrifugal motion transports particles through the crushing zone. Batch experiments have been conducted with quartz at various crusher settings (discs offset, rotational speed, and vertical exit gap) for various feed size distributions. The indications so far suggest that the disc speed is a key factor affecting the performance. Size reduction ratios as high as 11 were recorded from experiments with quartz at a speed of 830 r/min.

Jan 1, 2021

By J. Rajala

The Kupol mill facility processed a high grade free milling gold/silver ore containing 28.2 g/t Au, 324.8 g/t Ag and approximately 0.5% pyrite during 2008 operation. Gold predominantly occurs a selectrum in the ore and silver is predominantly present in the forms of acanthite, stephanite, pyrargyrite and proustite. Mill start-up was in mid-May 2008 and the mill reached the design throughput of 3 000 tpd in October. The ore was ground to approximately 70%?53 microns. A Knelson Concentrator recovered 9.8% gold and 0.5% silver. The gravity tails reported to a cyanidation circuit that has 14 hours pretreatment and 116 hours leaching. The slurry from cyanidation was then processed by counter current decantation (CCD) thickening to wash and separate the leach residue from the pregnant leach solution. Precious metals are recovered fromthe pregnant solution using the Merrill-Crowe process. The washed CCD leach residue slurry is treated with calcium hypochlorite to destroy cyanide and then sent to the tailings impoundment. Leaching is performed with a new technology called ?CELP? (CANMET Enhanced Leach Process). The Kupol mill overall gold and silver recoveries for 2008 were 95.4% and 85.6% respectively, which were 2.8% and 7.5% higher than targets. Gold and silver extractions in the leach circuit were 94.2% and 84.5% respectively. Leach profiles indicated that gold extraction reached a plateau in the 4th tank while minor silver dissolution occurred in the 5th tank. With the CCD circuit included, total gold and silver extractions increased to 95.4% and 86.6%, respectively. Optimization of the leaching strategy made it possible to reduce sodium cyanide concentration to as low as 410 ppm without compromising precious metals extractions. Silver was effectively leached from the refractory silver minerals because CELP produced more oxidized mineral surface relative to the conventional cyanidation leached mineral surfaces. The average cyanide consumption for 2008 was 1.3 kg/t. The new leaching technology proved to be very robust and performed efficiently even with changes in feed grade and ore mineralogy. Laboratory experiments produced results that were indicative of plant performance. The robustness of the technology and the laboratory test work contributed to the success of the Kupol mill start-up.

Jan 1, 2009

By M. E. C. Snyman, N. Naudé

"Coal fines produced during processing are difficult to dewater and result in a lower quality product and consequent lower value. A South African coal mine experiences severe difficulties with belt filter dewatering operations due to the presence of fines reporting from the thickener underflows. Plant 2 currently handles super-fine particles of size -34 µm and has low belt filter efficiency: excessive moisture retention lowers the product quality and strains downstream processing. It was necessary to determine an alternative method for dewatering these fines. Blending of fine material with coarser material was proposed as a solution. The effect of coal particle size and layering during ultrafines belt filter dewatering was evaluated using various blends of the fine Plant 2 material with coarser Plant 1 material. The best layering arrangement of the two materials and its optimum blend required to achieve reduced filter cake moisture content was determined in practise using a vacuum filter to simulate belt filtration. A blend of the two materials gave improved dewatering efficiency for the belt filters compared with that of the Plant 2 material alone. The best layering configuration was with Plant 2 material at the bottom and Plant 1 material on top. The optimum blend for industrial applications comprised 48% fines from Plant 2. IntroductionFines are produced during the processing of coal. It is estimated that 2 to 3% of run-ofmine coal reports to the ultrafine portion (-100 µm) (le Roux, 2005). The particle size of coal is inversely proportional to the amount of water adsorption, so smaller particles adsorb more moisture. Moisture removal requires either mechanical processes or thermal drying: mechanical processes are less expensive, but the fines still have high moisture retention. Discarding of fines leads to economic losses, so it is essential that they be dewatered so that they can then be sold as a product: fines need to be treated for both resource management and conservation reasons (Kenney, 1994). Removal of free surface moisture from ultrafine coal particles using a belt filter therefore remains a process that needs to be continuously improved. Ultrafine coal originating from a thickener underflow is known to be difficult to dewater owing to factors such as filter cloth blockage and moisture retention due to clogging. Mixing of finer and coarser materials has been proposed to deliver better dewatering efficiency and improved the quality of the recycled water (Kenney, 1994)."

Mar 1, 2019