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Control of flotation processes is mostly managed by plant operators, who assess the performance of the plant based on their own experience and other heuristic rules. These rules tend to be subjective or ill-defined, since most of them are concerned with the structure of the flotation froth, such as colour, bubble size and shape distributions, froth mobility and froth stability. These phenomena are very difficult to quantify objectively, and inexperience on the part of the operators, human error, etc., can lead to significant inefficiencies in plant operation. In this paper the development of a fuzzy system to support the control decisions of plant operators is described, which leads to significantly smoother control action and more stable plant operation than could be obtained with crisp sets of rules or manual control strategies. Keywords: flotation, fuzzy logic, image analysis, genetic algorithms, rule induction

Jan 1, 2000

By R. G. B. Pickering

Over the last few years Lonmin Platinum and Sandvik have embarked on a unique partnership of collaboration through a systematic approach to developing equipment to mechanize and automate narrow reef platinum mining. After the initial design and manufacture of the equipment the key aspect is the integrating equipment, people and method into a mining system. Another key aspect of mechanization is the optimization of equipment utilization, and this philosophy has ensured continual evolvement of mining methods. This paper describes the trials and development that have resulted in the mining method described as Lonmin mechanized breast.

Jan 1, 2007

By K. I. Afewu

A modified approach to the implementation of Gy?s sampling theory is discussed and used to design a procedure for sampling crushed gold ore feed to metallurgical process plants. The approach involves calibration of certain ore-specific parameters. These parameters were calibrated for two different crushed gold ores en route to grinding mills in process plants. The model predictions were compared with the predictions from Gy?s original model. Far smaller masses of samples are required by the modified model than by Gy?s model at the same relative variance. The representativeness of the sampling procedure if normally distributed errors are assumed was also calculated. These procedures and evaluations lead to significant savings on cost of handling and preparation of the samples and to a quantifiable degree of confidence in the analytical results for the process plant.

Jan 1, 1998

By N. Ragoonanthun

Paper written on project work carried out in partial fulfilment of B.Sc. (Mining Engineering) degree This report investigates the optimization of a raiseline in order to open up the ore reserve quicker. The project was carried out at Mponeng Mine (an Anglogold shaft formerly known as Western Deep Levels 1 Shaft and South Mine, in Carletonville). The project was divided into two focus areas namely: ?To design an optimum layout of a raiseline, which includes the scheduling of all activities for the establishment of the infrastructure. Consideration was given to the blasting practice, mining cycle, orepass placement and slusher positioning. Two designs were carried out on the above basis. ?The design of a ledging operation/practice to match the optimized layout of the raiseline. The ledging cycle design involved a thorough investigation into the possible use of drill rigs, Electronic Delay Detonators (EDD) blasting technology, longer drilled holes, Threshold Blasting (THROB),and water jet cleaning.

Jan 1, 2003

By J. T. Kalala

Energy consumption and wear of grinding media and liners are the major cost factors in milling plants. Since the beginning of the last century, much effort has been directed at the prediction of the power draw as affected by the mill operating conditions. This paper explores the prediction of the liner wear using the discrete element method (DEM). A mathematical model taking into account adhesion, abrasion and impact wear which occur in dry mills is derived in order to predict the loss of material on liners. The mathematical model is implemented in the DEM code using an objective function in order to produce realistic simulated profiles. Our DEM simulated predictions are compared to published experimental and industrial data. Keywords: modelling; discrete element method; liner wear

Jan 1, 2004

By L. du Preez, J. D. Steenkamp

This paper introduces the concept of clean steel production from a pyrometallurgist’s perspective to the broader metallurgical community. A simplistic overview of the steelmaking process from iron ore to car body manufacturing is followed by an introduction to the South African steel industry and the technologies that it utilizes. The process is illustrated by an overview of the flow sheet and technologies for the production of clean steel at Saldanha Steel, South Africa.

Jan 1, 2015

By J. Dvorácek

Similar to the case of any other business venture, the activities of mining industries are profit-oriented. Nothing will stop successful businesses in their quest for new localities to be prospected for minerals of their choice, because the useful economic life of any mine is limited. Before starting the process of land acquisition, it is important for any mining company to be able to forecast the profitability of the venture. The focus of this paper has been on the prospects of success, concerning the case of the opencast extraction of aggregates for construction. A set of 70 successful and loss-making quarries was subjected to investigation. An international company owns the quarries, which are located in seven European countries. The method of discriminate analysis provided the criteria for assessing future economic performance. The same criteria served the purpose of classifying other quarries belonging to the company.

Jan 1, 2012

By P. Rosario

The application of high pressure grinding rolls (HPGR) has been growing in the mining industry for the last 10 to 15 years. The major benefits supporting this trend are better energy efficiency, improved grinding capacity, and higher metal recovery in downstream processes such as heap leaching and flotation. In general there is limited quantitative knowledge on the true benefits of HPGRs relative to SAG mills in comminution, and about which situations one deals with better than the other. This paper will present a structure for comparison of the energy requirements for HPGR versus SAG mill considering complete circuits for comminution of precious and base metals hard ores. The work presented is from the design of four complete circuits based on ore data from two sites.

Jan 1, 2010

By N. Sahay

Improvement in work place environment by conventional methods viz., installation of higher capacity fan, fans in parallel operation or booster fan is a risky proposition in many coal mines in India because of difficult geo-mining condition such as shallow depth, multi seam workings having thin parting and inter connected goaves one above the other. The situation is further worsened if the mines have fire affected sealed off area connected to different ventilation circuits. On many occasions circulation of more air quantity by increasing fan pressure have resulted in initiation of spontaneous heating. To address these problems, authors have made some improvement in conventional Dynamic Balancing of Pressure Technique and worked out few ventilation schemes which are aimed for neutralization of pressure differential across sealed off area at the same time having improvement in ventilation in the mine. The excess pressure differential across sealed off area is mainly caused by introduction of higher capacity fan. Similar situation prevailed in one of the mines of Jharia Coalfield, India. The problem was solved by application of the above technique. In this paper, brief description of the technique, the problem in the mine, results of investigation, computer simulation studies of various schemes and methodology adopted for implementation of the technique in the mine have been discussed in some detail. Keywords: Dynamic Balancing of Pressure Technique, Spontaneous heating, Work place environment.

Jan 1, 2003

By Q. Cheng

This paper introduces the multi fractal interpolation method (MIM)developed for handling singularities in data analysis and for data interpolation. The MIM is a new moving average model for spatial mapping and interpolation. The model decomposes the raw data into two components: singular and nonsingular components. The former can be characterized by a localized singularity index that quantifies the scaling invariance property of measures from a multifractal point of view. The latter is a smooth component that can be estimated using ordinary kriging or other moving average models. The local singularity index characterizes the concave/convex properties of the neighbourhood values. The paper utilizes a binomial multiplicative cascade model todemonstrate the generation of one- and two-dimensional data with multi-scale singularities which can be modelled by asymmetrical multifractal distribution. It then introduces a generalized moving average mathematical model for analysing and interpolating data with singularities. Finally, it is demonstrated by a one-dimensional case study of de Wijs’ data from a profile in a zinc mine, that incorporation of spatial association and singularity can improve the interpolation result, especially for observed values with significant singularities.

Jan 1, 2015

By L. Bbosa

Paper written on project work carried out in partial fulfilment of BSc (Hons) (Eng) (Mechanical) degree Discrete element methods (DEM) are being used to provide detailed impact histories of the particles in comminution devices, such as mills. To match this immense detail of information, far more informative breakage tests than those that are generally conducted are now required. The split Hopkinson pressure bar apparatus is used in this study, as it allows the calculation of breakage forces and absorbed energies. The geometry of rock particles has been identified as significant, so this project undertook to identify the influence of shape on the breakage pattern of blue stone. Comparisons are then made between the breakage pattern of angular rocks and rounded, milled rocks for single impact fracture and consecutive impact loading at low energy. Results of this experiment indicate that although breakage for both geometries occurs over a similar energy range, rounded particles have the greater probability of fracture because they absorb more of the impact energy for a given loading. Size distributions of progeny show that five pebbles or more are sufficient to predict the distribution of most particles in small energy regimes. Cumulative impact testing shows that considerably more energy is required to break a rock through cumulative damage than through a single impact?this is of considerable importance in the light of the indications from DEM simulations that most breakage in a mill will be from cumulative damage rather than single impact breakage.

Jan 1, 2006

By P. J. Petit

Changing mining conditions, legislative issues, rising costs, and the constrained supply of skills and electricity in South Africa, have been some of the criteria forcing mine operators and engineers to review the traditional use of compressed air to power underground hand-held drilling operations in narrow-stope, hard-rock mines. In answering the question, 'What is the best way to power this mine?', they have resorted to trade-off studies with results of limited usefulness, because they are site-specific, and use only a few comparative parameters, based on a small data set. This paper aims to provide definitive, objective, and quantitative decision-making approaches to evaluating alternative energy-delivery systems for stoping in narrow-reef hard rock mines, based on primary and relevant criteria. These include quantifiable criteria such as capital expenditure, operating costs, resulting financial returns, energy and water usage, production performance, life-of-mine, etc. Other important criteria with qualitative aspects are integrated. These are safety, health, and environmental concerns, legislative requirements, business risk, technology change, etc. The paper begins with a review of decision-making processes available, and proposes the use of the analytical hierarchy process (AHP) method as a multiple-criteria decision-making tool and the decision tree based on milestone-driven uncertainties, to validate the selection of the energy delivery system. The results of a multiple-criteria questionnaire completed by a variety of industry experts and professionals, such as production and operation managers, consultants, suppliers, and techno-financial analysts, are discussed. The evaluation indicates the potential for hydropower to be the best solution for narrow-reef hard rock mines, based on current information, mine design layout and production.

Jan 1, 2013

By S. Vorberg, J. Preussner, B. Fischer, U. Glatzel, R. Völkl, M. Wenderoth

Pt-Al-X alloys have shown good mechanical properties and adequate oxidation resistance. Starting from a promising Pt-Al-Cr alloy, the influence of Ni additions was investigated. After ageing finely dispersed precipitates are observed. Nb, Ta, Ti and Re increase strength when added as partial substitute for Al. Minor additions of B increase creep resistance and rupture time remarkably, owing to strengthening of the grain boundaries. The evolution of the alloy development programme as well as selected properties of the multi-component Pt-base alloys are presented.

Jan 1, 2006

By J. D. Steenkamp

Keywords: Thermal, conductivity, diffusivity, expansion, history, density, specific heat capacity, industrial rich high-carbon manganese slag The thermal conductivity of slag is an important parameter in the design of furnace-containment systems based on freeze-lining technology. Literature indicates that the crystal content of a slag has a significant influence on its thermal conductivity. Industrial, rich, manganese-bearing slag was cooled at different rates to create samples with different microstructures. The coefficients of thermal conductivity of these samples were measured in a nitrogen atmosphere from room temperature to 990°C at 100°C intervals. The laser-flash measurement technique was used for this purpose. Follow-up investigations included XRF and XRD and modelling in FACTSage.

Jan 1, 2011

By A. Mboma

Keywords: Furnace, decommissioning, care and maintenance, re-start, funding, nickel Bindura Nickel Corporation (BNC) operates two nickel mines, and treats concentrates from these mines as well as toll concentrates from the region around its Bindura Smelter and Refinery (BSR) complex. At the smelter, concentrates of at least 5% nickel content are blended and dried to 4% moisture in a coal-fired rotary kiln. Matte smelting of concentrate is carried out in a six-in-line electric arc furnace, where the furnace slag is granulated and discarded. Furnace matte is transferred via ladles into Peirce-Smith converters, where, after granulation, a leach alloy containing 68%Ni, 20%Cu, and 6%S is produced. Converter slag is recycled via the matte-smelting furnace. The onset of the global economic recession towards the end of 2008 resulted in a collapse of metal prices, worsening the local situation that was already marred by unfavourable macro-economic conditions in Zimbabwe. As a result, BNC mines were put on care and maintenance in November 2008, followed by Bindura Smelter and Refinery in February and March 2009 respectively. The business environment has since changed, and BNC is getting ready to re-start the plant. This paper describes the decommissioning of the Bindura furnace, asset preservation during the care and maintenance programme in the past two years, and preparation for starting up of the Bindura smelter in the near future.

Jan 1, 2011

By F. T. Wang, Y. Yuan, S. H. Tu, X. G. Zhang

Hydraulic support instability (HSI) is one of the most common causes of disasters in underground coal mining, posing a threat to the safety of mine workers and normal operation of the equipment. It is prone to occur in fully-mechanized mining faces with a large mining height (FMMLMH), especially when the dip angle of the coal seam is large. The key to controlling HSI is to deduce its mechanism and employ effective control techniques. This paper focuses on the analysis of HSI types, the key parameters and techniques to control HSI in FMMLMH, the establishment of a model of HSI in FMMLMH, and a multi-parameter sensitivity mechanical model of different HSI forms in the no. 7219 longwall face in Xutuan Coal Mine, Huaibei Mining Group, by using sensitivity analysis . The results show that HSI mainly presents in three forms: hydraulic support gliding (HSG), hydraulic support tilting (HST), and hydraulic support tail twisting (HSTT). The occurrence of the above three forms depends mainly on support anti-instability capability. In the no. 7219 longwall face, HSG and HST are the main two forms of HSI. The dip angle of the working face and the friction coefficient between floor and hydraulic support are the sensitive parameters for HSG, while HST is strongly dependent on the dip angle of the working face and the friction coefficient between roof and hydraulic support. By the applications of measures such as the oblique layout of the working face, cutting the floor into a step pattern, moving the support under pressure, and raising the setting load, the support stability was controlled effectively.

Jan 1, 2015

By M. Royker

Gold has been demonstrated as a possible catalyst for oxidation reactions. Some evidence for a possible promotion effect of platinum has also been recorded. The influence of platinum as promoter for Au/?-Al2O3 prepared via anionic ion-exchange for the oxidation of glycerol was investigated in a batch reactor at 60°C. It is inferred that the addition of platinum reduces the catalytic activity and therate of deactivation, resulting in an overall higher final conversion of glycerol with increasing platinum loading. The addition of platinum to the catalyst favours the formation of the desired product, glyceric acid.

Jan 1, 2012

By S. Sridhar, R. E. Aune, M. Hayashi

Thermophysical properties of silicate melts are strongly structure dependent. It is well known that the viscosities of slags increase with increasing the degree of polymerization of silicate anions. Even the thermodynamic properties of slags are dependent on the types of species and the population of the same in the melt. Thus, a link between the thermophysical and thermochemical properties of silicate melts is logically expected. The present paper elucidates the salient features of Darken?s excess stability approach to the Gibbs energies of solutions as applied to the viscosities of silicate melts. It is demonstrated, that the second derivatives of the viscosities of binary silicate melts with respect to composition indicate a maxima corresponding to the existence of stable compounds in these systems. The concept was successfully applied to the following systems: Al2O3-SiO2, CaO-SiO2, FeO-SiO2, MgO-SiO2and MnO-SiO2. In all the cases, the second derivative plots of viscosities with respect to composition showed peaks corresponding to the metasilicates. The second derivatives of the activation energies of viscous flow with respect to temperature has earlier been shown to reflect the formation of associates/embryos in the homogeneous silicate melts, indicating the readiness of the melt to separate a solid phase. Thermodynamic coupling of thermal diffusivities in the case of the system CaO-Al2O3-SiO2from the laser-flash measurements of these slags as a function of temperature are examined as part of the present study. Densities are estimated from integral molar enthalpies in the case of silicate systems and the results are presented. Keywords: silicate melts, viscosity; activation energy, thermal diffusivity; density

Jan 1, 2004

By P G. Gaylard

The minerals Industry carries out over US$ 2 billion of R&D annually. The R&D is performed at three levels ? in house research facilities; on a one-on-one basis with a research provider; as syndicated (collaborative) research. The key to a successful R&D programme is project selection. It is suggested that at this time of ?bounty? for the minerals industry the research portfolio should contain some ?blue sky? but potentially long term significantly beneficial projects. This said, the projects should align the technical concepts with the business imperatives. AMIRA has found the ?Road Map? concept has assisted in defining areas for R&D. Examples of this methodology using a Copper Road Map developed by AMIRA for the copper producers operating in South America is presented. The benefits derived from syndicated research are also discussed.

Jan 1, 2007

By J. de Villiers

Through the application of the Rietveld method, X-ray diffraction analysis has developed into a fully quantitative method for phase analysis. The Rietveld method itself has progressed from an unstable method that required constant operator intervention to a stable and robust method suited even for routine analysis. The method, however, requires a good initial calibration and periodic checks on its precision and accuracy. Several examples from minerals processing, pyrometallurgy, and materials science show the strengths and applicability of the method. The limitations and sources of error are also discussed.

Jan 1, 2007