Search Documents

This paper describes the operating practice and design features of an intensive-cyanidation plant at the East Gold Plant of Vaal Reefs Exploration and Mining Company Limited (V.R.E.M.). After the development oh cyanidation route for the treatment of gold-plant gravity concentrates by the Anglo American Research laboratories (A.A.R.L.), a full scale plant was commissioned at Western Holdings (Welkom Division) Gold Mine in March 1977, and the V.R.E.M. plant was commissioned in August 1981. Although the gravity-concentration route does not now enjoy the prominence of former times, in an existing conventional plant the intensive-cyanidation route can successfully replace mercury amalgamation.

Jan 1, 1984

By F. Hörtkorn, Y. Narainsamy

Rather quietly, a new generation of European norms dealing with earthworks has been developed over the past few years, in particular a part of EN 16907 pertaining to extractive waste. Whereas the majority of the parts deal with routine geotechnical aspects, one part deals specifically with tailings dams. The standard is currently in draft form but if this becomes a European Standard, members of the European Union are bound to comply with the regulations. As such, the standard has the capacity to influence mining in Europe and potentially in South Africa. In this paper we review the standard and compare it to the South African standard on mine residues and the recently published Global Industry Standard on Tailings Management (GISTM). We conclude found that although the European norm makes great strides towards increasing tailings dam safety, there is room for improvement. The current South African standard has served well since its inception, but can be improved by using concepts from the European and global tailings standards.

Jun 2, 2022

By E. Maritz

"The localized uniform conditioning (LUC) technique was proposed by Marat Abzalov in 2006. The technique converts conventional uniform conditioning (UC) grade-tonnage curves into single grade values attached to each smallest mining unit (SMU). This is achieved by ranking the SMUs within a panel in increasing order of their grade (based on the direct kriging of SMUs). This ranking is then used to localize the conventional UC grade-tonnage curves for each panel by dividing them into classes and computing their mean grades, which are assigned to the SMUs. The quality of this localization process will depend heavily on the validity of the grade patterns predicted by the direct kriging of the SMUs. Abzalov noted that where the distribution of data available for the direct kriging of the SMU is characterized by strong short-range variability, the advantages of using the LUC approach may be more limited. Consequently, a study was undertaken to determine how valid the predicted grade patterns of a typical Birimian-style gold deposit (with high nugget effect and strong short-range variability) might be expected to be. This was determined by comparing the direct SMU kriging ranking (based on sparse data) with the grade control model ranking (based on close-spaced data and the best available estimate of the deposit). The results showed a satisfactory correlation between these rankings and it was concluded that, although the grade patterns predicted by the direct kriging of the SMUs may be less meaningful for deposits exhibiting strong short-range continuity, there is nevertheless a convincing relationship with the actual (or best available) rankings. Therefore, the LUC technique is still considered to be useful for this style of deposit. IntroductionFor adequate technical and financial evaluation of a project, attempts should be made to estimate the recoverable resources – the portion of the in situ resource that can be economically extracted by mining. To achieve this, the estimates of the tonnage and grade of the mineralization should be produced above a given economic cut-off and should take into consideration the proposed mining selectivity."

Jan 1, 2016

By S. Ling, T. Liu, Y. Shang

A new copper-molybdenum flotation technology developed for a certain coppermolybdenum ore is introduced. We achieved copper-molybdenum bulk flotation in lowalkali conditions. Locked-circuit test results showed that the bulk concentrate contained 21.05% Cu and 1.10% Mo, with copper recovery of 87.37% and molybdenum recovery of 77.07%. For the copper–molybdenum separation process of the bulk concentrate, we use a new depressant, BK511, to replace the traditional sodium hydrosulfide. We achieved copper–molybdenum separation through one rougher, nine cleaner, and two scavenger processes. The results of locked-circuit tests showed that the molybdenum concentrate contained 46.19% Mo and 0.75% Cu, with molybdenum recovery of 93.80%; the copper concentrate contained 21.50% Cu and 0.069% Mo, with copper recovery of 99.92%. This new technology overcomes disadvantages of using large amounts of lime, sodium hydrosulfide, and other reagents in traditional copper–molybdenum flotation.

Jan 1, 2023

By Xiaoxu Sun, Jianchao Yao, Qiheng Zhu, Dubo Wang, Jiancheng He, Shijie Lu

Tower mill is considered to have a better regrinding and fine grinding effect compared with ball mill, and its application is much broader. The spiral agitator of the tower mill is driven by the motor. Media inside the mill is under the combined actions of the spiral mechanism, the cylinder, and media nearby, and these parameters are key factors affecting the grinding effect. However, it is not possible to obtain detailed information of kinematic law of media based only on traditional laboratory experiments, let alone the relationship between parameters of kinematic law of media and grinding effect. Experimentation is the only way to develop industrial equipment. However, this is time-consuming and costly, which hampers the further research of the tower mill’s grinding mechanism. The paper selects two structural parameters (gap between the edge of the spiral agitator and the cylinder wall, ratio between the diameter of cylinder and that of the spiral shaft.) and three operating parameters (diameter of media, filling ratio, the speed at the edge of the spiral agitator) as variables to do an orthogonal designed experiment of five factors, four levels, and thereby obtaining change law of grinding indicators of different parameters. Experimental equipment may be simplified to enable an applicable simulation strategy. Simulation based on a discrete element method is conducted to obtain the change law of the speed of media, collision frequency, normal force, and radial force. The relational curve between parameters of kinematic law of media and energy consumption of grinding is clarified, and key factors affecting grinding efficiency are determined. Those factors will be used for optimising the design and operating process. The research result of this paper obtained from laboratory experiments and computer simulation provides data support and theoretical bases, and has directive meaning and applicable value for tower mill’s optimisation and large-sized design. Keywords: Tower mill, discrete element method, kinematic law of media, energy consumption of grinding

Jan 1, 2020

The first annual student prizegiving function of the South African Institute of Mining and Metallurgy was held in the Dorothy Susskind Auditorium, University of the Witwatersrand, on Thursday, 26th May, 1977. The address (see opposite page) was given by Dr M. G. Atmore, a director of Anglo American Corporation and Vice-President of the Institute.

Jan 1, 1977

By C. M. D. Majola, K. E. Langerman

Energy efficiency is a cost-effective way of both bolstering energy security and limiting the harmful effects of energy use on the environment. Mining is an inherently energy-intensive activity, and the 2008 revision of South Africa’s National Energy Efficiency Strategy (NEES) set a target of a 10% reduction in energy consumption by 2015 for the mining sector. In this study, we investigate the effectiveness of the NEES in improving energy efficiency in the South African coal mining sector by surveying energy intensity at a number of operations, and analysing energy efficiency trends and energy use by process and energy carrier at an underground coal mine in Mpumalanga. Most mines surveyed exhibit an increase in energy intensity over time. At the case study mine, the increase was primarily due to increased energy use in the beneficiation and discard reclaiming processes. Trends in energy consumption are a poor reflection of trends in energy intensity, as a decline in energy consumption is most easily achieved by reducing production. A more appropriate metric for energy efficiency at coal mines is energy intensity, defined as energy use per unit of saleable product, relative to a multi-year baseline. The evidence suggests that the NEES has been ineffective in promoting energy efficiency in South African coal mines. We propose that greater success could be achieved by monitoring and reporting on energy intensity at the process level, and by incentivizing energy efficiency gains.

Sep 6, 2023

By G. P. Dyke

With the removal of the majority of the shallow mineral reserves there has been an increase in the mining depths in the South African mining industry. This has, in turn, changed the industry?s and stakeholders? perceptions of risk associated with mining-induced instability. In recent years the increased mining depth, particularly in open pits, has led to an increase in pit slope failures, which has highlighted the need for appropriate and effective pit slope management programmes. Such a programme comprises many facets, including mine hazard plans, regular slope inspections, cleaning of interim and final pit faces, blasting practices, histories of failures, pit depressurization, stormwater control and evacuation procedures. However, it is arguably in the field of slope monitoring that the most significant strides have been made in terms of new technologies and best practice in open pit mining geotechnics, with the introduction of technologies such as laser scanners and slope stability radar. This paper seeks to illustrate the operational benefits associated with the implementation of new technologies into open pit mining, using AngloGold Ashanti?s Geita Gold Mine in Tanzania as an example.

Jan 1, 2009

By S. A. Lorentz, Y. Xu, C. Theron

The failure of tailings storage facilities (TSFs) results in the discharge of significant quantities of hazardous waste material into the natural environment. Research studies relating to slope instability have identified physical mechanisms such as rainfall-induced erosion, liquefaction, and shear failure as the main triggers. The generation of transient pressure waves and the mobilization of pre-event water in the unsaturated zone have been found to trigger shallow landslides in natural hillslopes. In this paper we review these physical mechanisms, known as groundwater ridging (GWR) and the Lisse effect (LE), from other studies. Previous researchers have explained both these phenomena through field and laboratory observations, numerical modelling, as well as conceptual discussions. These case studies demonstrate the impact of rainfall characteristics on the generation of transient pressure waves that rapidly increase the phreatic surface and change pore water suction. Reference is also made to the influence and behaviour of physical porous medium characteristics on the establishment of a continuous water phase that facilitates the transmission of an induced pressure head. However, previous studies fail to recognize the possibility that the pressure increase in pre-event water through pore air propagation could cause slope instability in tailings dams. The authors suggest that the physical properties and hydraulic behaviour of unsaturated porous tailings media make it susceptible to GWR and the LE, resulting in the creation of a potential failure plane.

Feb 2, 2022

Mr R. C. J. Goode (President) was in the Chair. There were also present one hundred and thirty-six Members, including Messrs R. J. Adamson, Dr J. M. Bereza, Messrs M. Barcza, H. Britten, H. E. Cross, J. K. E. Douglas, G. W. Holl, Dr J. P. Hugo, Messrs C. J. Irving, P. Lambooy, Prof J. de V. Lambrechts, Mr D. G. Maxwell, Dr J. T. McIntyre, Prof R. P. Plewman, Messrs J. F. Reid, V. C. Robinson, H. Simon and P. W. J. van Rensburg (Council Members), G. Abdinor, C. B. Anderson, H. F. Allan, E. L. Atkinson, V. C. Barnes, J. F. Bennet, W. W. Bath, R. E. Barnes, C. L. Berrange, J. P. Buds, Dr W. Bleloch, Dr L. A. Bushell, Messrs D. L. Carson, D. D. Cornier, R. S. Cooke, R. R. M. Cousens, J. P. Coetzee, W. L. Cousens, J. Daniel, R. Daniel, D. G. Davies, S. K. de Kok, V. S. Dillon, B. S. Dykhouse, Dr H. G. Denkhaus, Dr R. S. J. du Toit, Messrs J. I. L. Edwards, R. C. Espley-Jones, J. C. Ferguson, D. T. Fourie, A. Frost, W. R. Flook, Dr N. P. Finkelstein, Messrs D. F. H. Grave, J. M. Gosnell, E. K. Gibson, R. W. Grout, E. W. Gray, J. S. Hay, F. G. Hill, H. N. Hepker, J. P. Hoffman, C. G. Hodges, D. M. Jamieson, Dr D. G. Krige, Dr N. P. Lategan, Messrs J. E. Laschinger, J. Levin, C. P. Linsell, J. O. Kempe, F. Q. P. Leiding, A. I. Lee, D. G. Malan, W. Malan, H. W. McCulloch, R. D. R. Munro, C. S. Macphail, Dr T. F. Muller, Dr A. J. Nel, Messrs S. C. Newman, G. G. Nicolson, G. Y. Nisbet, J. A. Papenfus, E. Pavitt, W. H. Pittie, P. C. Pirow, P. G. D. Pretorius, N. F. Peverett, R. P. Plaskett, M. P. Pearse, W. Pilkington, T. K. Prentice, Dr R. E. Robinson, Messrs R. B. Richardson, R. St. J. Rowland, R. J. Rouillard, F. O. Read, W. T. Ruhmer, D. Savile Davis, E. F. Statham, K. Smith, H. Simon, G. B. Stern, C. D. Storrar, Dr N. B. Strydom, Messrs J. H. Talbot, A. H. Taute, J. H. Taylor, G. W. Thiel, K. A. Tweedie, W. E. Vance, Dr H. J. van Eck, Messrs L. W. P. v. d. Bosch, P. A. von Wielligh, N. B. Vinson, S. J. Venning, W. M. Walker, D. T. Watt, Dr H. J. R. Way, W. T. L. Wayman, R. G. Williams, L. G. S. Wright and C. F. Ziervogel. Thirty Associate Members, including Messrs E. Collier, G. Douglas, D. H. Gray, H. G. Gericke, R. Hemp, N. M. Hayne, A. Hazell, P. M. Johnston, D. E. Love, Miss V. E. Marting, Messrs R. G. Matthews, P. Malpage, D. Nicolle, R. Pendreigh, J. J. Rosslee, R. W. Shearer, R. F. Taylor, G. C. Thompson and D. A. Viljoen. Three graduates, Messrs G. S. Giles, J. P. Hatfield and J. A. Jones. Five Affiliates, Messrs A. C. Collie, E. Collier, A. B. Cook, W. Jacobs and G. M. Thain. Two Students, Messrs C. J. Bircher and R. P. Henrard.

By R. Jacobs, R. E. L. Pobe

The Moab Khotsong Metallurgical Complex comprises a gold recovery circuit (Noligwa Gold Plant) and a uranium recovery circuit (South Uranium Plant). The metallurgical complex employs the reverse leach technology for the recovery of uranium; specifically, uranium extraction prior to gold using acid leaching processing. The inherent uranium species in the ore are uraninite, coffinite and brannerite. The slurry that has been subjected to the uranium leach is further subjected to solid-liquid separation to separate the uranium in a solution through counter-current decantation and the solids (solids carrying all the gold), which are repulped and returned to the gold plant for gold processing. The uranium leaching process is critical to the uranium playing a pivotal role as a value adding by-product to the gold operation. The benefit of adopting this reverse leach process, for improved gold recovery, is that it exposes gold particles occluded within the uranium matrices and avails them for cyanidation. However, the drive for operational efficiency in uranium extraction must be weighed against the incremental operating cost against the backdrop of depressed spot uranium market prices. Over the years, efforts were directed at maintaining the benefit of extracting uranium to enhance gold recovery and simultaneously, optimising the operating cost model for the uranium operation to remain relevant to the gold operation. The aim of this paper and the corresponding presentation is to give an account of the uranium processing optimisation journey embarked on over the years; namely, the operational tradeoffs made in the process of ensuring that uranium continues to add value to the gold operation. These challenges were faced while striking a fine balance between processing cost and operational efficiencies against the prevailing depressed uranium spot market prices. Mineralogical- and laboratory tests conducted form the support basis for the results and observations articulated in the paper. Keywords: By-products, gold extraction, reverse leach benefit, uranium extraction

Jan 1, 2020

By S. O. Castro, R. E. González, L. E. Velasco, J. M. Van Sint, P. V. Lois

Abstract Several zones with expansive rocks were encountered during construction of two tunnels of the water conduction system for the Chacabuquito Hydropower Plant, located in the Aconcagua river valley of the Chilean Central Andes Mountains, at elevation 1.075 m a.s.l., and 65 km north-northeast of Santiago. The expansive behavior was associated to three different geological features. Firstly with the crossing of important north-south trending faults, with montmorillonitic and caolinitic fillings. Secondly to the presence of zones of rock mass showing a penetrative presence of clay minerals (montmorillonite, illite and caolinite) and penetrative thin veins of ceolites. And thirdly to the hydrothermal alteration of the rock and the consequent generation of clay minerals (predominantly montmorillonite, sericite and minor caolinite). The geological and mechanical characteristics of the expansive rock domains, as well as the field and laboratory reconnaissance and characterization program, are described in the paper together with the bases for design and the guidelines for construction and definitive tunnels support. Resúmè Pendant l’excavation des deux tunels du système d’adduction d’eau pour alimenter la centrale hidroélectrique Chacabuquito, plusieures zones de rochers expansifs ont été découvertes. Ces tunnels sont dans la vallée du fleuve Aconcagua de la Cordillère des Andes du Chili Central, à une altitude aproximée de 1.075m s.m.n. et à 65km vers le nord-nord-ouest de Santiago. Cette conduite expansive est associée à trois différentes caractéristiques géologiques du massif rocheux. Un premier lieu, à l’intersection de plusieures zones de failles, d’orientation nord-sud et subverticales, avec remplissage de rochers désintégrés, montmorillonite, caolinite et sérite. En seconde lieu, a la présence de zones de rochers expansifs, avec des nombreux minces veines de céolite-calcite et aussi des minéraux argileux (montmorillonite, illite et caolinite). Et, dans troisième lieu, dût à la présence de zones d’altération hidrothermale du massif rocheux et la conséquente génération de minéraux de remplacement argileux (surtout sérite, montmorillonite et en plus petit degré, caolinite). Les caractéristiques géologiques et géomécaniques des rochers expansifs, ainsi que la reconnaissance du terrain et les résultats du programme d’essais de caractérisation géomécanique du laboratoire sont décrits dans ce travail, ainsi que les bases de dessin et recommandations constructives pour placement du support définitifs pour ces tunnels Zusammenfassung Während der ausgrabung der zwei tunnels der wasserleitungssystem, um die Chacabuquito Wasserstromzentrale zu besorgen, wurden verschieden ausgedehnte gesteinadern gefunden Die beiden tunnels befinden sich im Aconcaguatal, wo der Aconcagua Fluss fliesst, auf einer Höhe von 1.075 m über dem Wasserspiegel und ca. 65 Km Nord-Nordest von Santiago entfernt, in mittleren Anden Cordillere (chilenische Gebirgskette). Drei verschiedene geologische merkmale dieser massiven gesteine können dieses ausgedehnte verhalten erklären. Erstens, hier befinden sich verschiedene und auch ganz wichtige

Jan 1, 2003

By I. Mc Dougall

Water-cooled copper tap-hole blocks provide an effective means of extending the life of tap-hole refractories, as the lower temperature of the refractory material inhibits wear and other damage and promotes the formation of a protective frozen slag layer. This is particularly beneficial during prolonged tapping cycles. The copper block forms an integral part of the lining, and provides mechanical support to the refractory, facilitating rapid replacement of tapping channel bricks without disturbing the surrounding lining. Safety considerations are an important design factor, and the positioning of the water channels is optimized to prevent leaks although the copper is not in direct contact with the molten fluids during normal operation. Water-cooled copper blocks designed by Tenova Pyromet have successfully been utilized on metal, matte, and slag tap-holes for a number of processes, including nickel, platinum group metals, and mineral wool.

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 Q. Cui, B. Z. Zhou, Z. G. Song, Y. G. Zhu, G. B. Zheng

The complex refractory Cu-Pb-Zn polymetallic ore in Xinjiang, China is a massive sulphide ore with complex mineral components. In the past two years, the ore mineralogy has changed, resulting in a decline in metallurgy, with too much zinc reporting to the lead and copper concentrates. A detailed mineralogical study indicating the presence of secondary copper minerals, which could be activating the sphalerite early in the present circuit, was used to develop a novel reagent and flotation flowsheet termed “Pb-Cu co-flotation, Cu intensified flotation, Zn flotation”. It was tested and found to significantly contribute to improving the flotation performance of the ore. In the Pb-Cu co-flotation circuit, successful depression of pyrite and sphalerite was achieved using a BK612- Na2S based depressant system. Most of the galena and some of the Cu bearing minerals with excellent floatability were collected with the use of the selective collector BK906. The rest of Cu bearing minerals were floated in a copper Z200 circuit using a BK537-lime-zinc sulphate based depressant scheme. Zinc flotation from the copper tailing was performed in a SIBX circuit using lime as a pyrite depressant. Using the proposed flowsheet, overall Pb, Cu, and Zn recovery increased significantly to 88%, 87%, and 90% respectively. Keywords: Complex polymetallic ore, Cu-Pb-Zn, Pb-Cu co-flotation, particle size

Jan 1, 2020

By M. C. Holton

South Africa has the world?s largest in situ deposits of platinum group metals, but economically exploitable resources are shrinking due to escalating costs and technical challenges. The South African National Research and Development Strategy comments that an increase in the knowledge intensity of the resource-based sectors is required to turn these resources to account. Highly trained human resources, continuous improvement, technological innovation, and smart acquisition of know-how will become the major differentiators in the global mining market. Mechanization and, ultimately, automation in mining have the potential to reverse the negative mining trend and resolve safety and other challenges. However, the adoption rate of mechanized mining in platinum (and hard-rock gold) has been slow for various reasons. Changing systems from conventional drill?and-blast to continuous mechanized mining is a big step-change endeavour. The problem of transformation is discussed, and the discipline of systems engineering is examined because of its successful application in aerospace and defence.

Jan 1, 2012

It is well understood that to develop wagon wheels with higher abrasion resistance, fracture toughness, and fatigue resistance, steels with lower amounts of inclusions need to be used. Clean steels are produced with technologies that minimize the amount of inclusions in the microstructure. The demand for cleaner steels is high, and lowering of non-metallic oxide inclusions and controlling their morphology, composition, and size distribution is vital. Reduction of residual impurity elements such as sulphur, phosphorus, hydrogen, nitrogen, and trace elements is essential in the production of cleaner steel. Material cleanliness is vital for fatigue endurance, since oxide inclusions may act as stress concentrators and initiation points for fatigue cracks. To better understand the relationship between the cleanliness and toughness of the 34-inch cast wagon wheels, two samples of different levels of cleanliness were supplied for investigation. This paper presents the results of metallurgical analysis using scanning electron microscopy(SEM), energy-dispersive spectrometry (EDS), and mechanical tests for the pearlitic high-performance cast rail wagon wheel (identified as Class B) that are currently being used. The Charpy V-notch impact test results for the three samples from wagon wheels were compared. With the aid of SEM/EDS analysis system, non-metallic inclusions in these steels were detected, and it was possible to determine the position, size, shape, and composition of each particle. Alumina and manganese sulphide inclusions could be identified as the dominant inclusion types in the investigated samples. Fracture surface analysis of the Charpy specimen with high inclusions indicated that transgranular cleavage was the predominant fracture mode. Fractography of fracture surfaces of Charpy impact test samples also showed improvement of toughness properties on the clean sample.

Jan 1, 2013

A Special General Meeting of the Institute was held in Kelvin House, Johannesburg on Wednesday, 29th September, 1971. The President, Prof. D. D. Howat opened the meeting at 9.55 a.m. The President read the notice of meeting which was as follows: "In order to bring industry into closer liaison with the work of your Institute and to place the Institute's finances on a sound basis your Council recommends that companies be admitted to membership of the Institute under clause 2.6 of the Constitution, that is, as Non-Corporate members. The designation for this class of member will be that of "Company Affiliate". 2 Membership: This clause to be amended as follows:- 2.6 "Non-Corporate members shall comprise the grades of:- Company Affiliate Honorary Fellow Graduate Associate Student" 2.6.1 This clause to be added:- "Companies involved in or associated with the mining or metallurgical industries are eligible to become company affiliates" 2.14 Add:- "A special certificate shall be issued to all company affiliates". After giving the background to the recommendation made by Council the President asked for a proposer and seconder for the resolution. Mr J. K. E. Douglas proposed and Mr D. G. Maxwell seconded the resolution. The meeting agreed that the constitution be amended as proposed. The meeting closed as 10.05 a.m.

By W. W. de Graaf, M. J. Ntsekhe

Klipspruit Colliery is experiencing coal losses, which leads to a negative impact on coal production and subsequently loss in revenue. This study aimed to identify the possible causes of coal losses in the No. 4 upper and lower seams. The objectives were to identify potential sources of coal losses through a literature survey, to identify areas where the coal losses occurred, to determine factors affecting coal losses, and to identify the most cost-effective methods to reduce coal losses. Highwall losses, top-of-coal losses, and coal edge losses were identified as the major areas of coal loss at Klipspruit. These losses were mostly attributed to the drilling and blasting practises of the pre-split, interburden waste, and the coal seams. Recommendations include re-visiting the current pre-split design and the tolerances adopted for the interburden and coal seam drilling and blasting design. It is furthermore recommended that Klipspruit implement a continuous improvement plan for the drilling and blasting and refresher training for the blasting crew and operators.

Jun 10, 2024

By S. Subramanian, L. Mweene

A siliceous low-grade copper ore from Mpanda Mineral Field (MMF), located in south west Tanzania consisting of SiO2 (58.3%), Fe (10.4 %) and Cu (0.9 %) was initially subjected to selective dispersion-flocculation using sodium trisilicate (STS) as a dispersant and xanthan gum (XG) as a flocculant. Subsequently, the selectively flocculated fraction was floated using a collector combination of potassium ethyl and amyl xanthate (1:1) in the presence of poly-ethylene oxide (PEO) as a silica depressant, to get a copper concentrate. The mineralogical investigations confirmed that the MMF ore was mainly composed of quartz, chalcopyrite and pyrite. Adsorption studies indicated that the adsorption density of XG on MMF ore decreased with an increase in pH, while that of PEO was independent of pH. The adsorption isotherms of XG and PEO on MMF ore exhibited Langmuirian behaviour. The zeta potential studies of MMF ore indicated that the iso-electric point (IEP) was located at pH 2.6, presumably due to its high silica content. In the combined presence of XG and STS, the zeta potential of MMF ore became more negative, with an increase in the concentration of STS. However, in the presence of PEO, the zeta potential of MMF ore became less negative with an increase in the concentration of PEO beyond the IEP, without shifting the IEP. Selective dispersion-flocculation of MMF ore improved the flocculated chalcopyrite grade to 19.8 %, yielding a degree of flocculation and a maximum separation efficiency of 12.1 % and 85.7 % respectively, after three desliming stages in the presence of 30 ppm of STS and 30 ppm of XG. A copper concentrate of 29 % grade and 90 % recovery containing silica of 0.9 % grade and 1.7 % recovery was achieved by flotation of the selectively flocculated component, using PEO as a depressant for quartz. Keywords: Flotation kinetics, flotation machines, flotation bubbles, particle size

Jan 1, 2020