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By Briony C. Ruse, David V. Boger, Fiona Sofra1

"The sustainability of the mining industry must be addressed through improving tailings management. The use of thickened tailings and pastes stems from a paradigm shift towards designing tailings disposal sites to suit their surrounding environment, rather than manipulating the environment to accommodate the tailings. Thickened tailings and pastes usually exhibit non-Newtonian behaviour, so a thorough understanding of the rheological characteristics of the material is required in order to determine the disposal plant operating conditions.As environmental factors translate into economic issues, minimising waste production using dry disposal methods is gaining popularity. The use of rheological information is of high importance in evaluating the spreading characteristics, the transportation and the dewatering of thickened mineral tailings. The principles outlined may be applied to many industries encompassing a wide range of waste materials. The main obstacle to the widespread implementation of dry disposal methods has been the high initial capital cost of the methods due to the dewatering step, and the high cost of pumping thick suspensions across any great distance. Proper and thorough costing of tailings disposal activities combined with an accounting approach that shows closure and post-closure care costs on a per tonne basis of tailings disposed throughout the life of the tailings facility will show that dry disposal methods are more favourable than they might seem on initial appraisal."

Jan 1, 2003

By Yuriy V. Gulyaev, Galina V. Sedelnikova, Valeriy D. Lunin, Valentin A. Chanturiya, Igor J. Bunin

"Probable mechanisms of disintegration of mineral particles in gold-containing sulphides and benefication products exposed to high-power electromagnetic pulses are discussed. Experimental data are presented to confirm the formation of breakdown channels and selective disintegration of mineral complexes as a result of pulse irradiation, which makes for efficient access of lixiviant solutions to precious metal grains and enhanced precious metal recovery into lixivia during leaching. Experiments with different gold-containing products revealed a synergetic effect of high-power electromagnetic pulses with widely varying parameters and moisture in mineral pores on breaking-up and gold extraction processes for various resistant goldcontaining mineral products.Several series of tests performed in IPKON RAS, IRE RAS and TsNIGRI yielded an absolute gain in precious metal recovery, up to 30-80 % for gold and 20-47 % for silver, with resultant gold recovery as high as 90 %. An essentially new, environmentally safe and energy-saving breaking-up technology has been developed for resistant gold-containing products. This new method would shorten the way from raw minerals to final products and help significantly reduce the cost of these products as it obviates the necessity for using the expensive procedures of energy-intensive and environmentally hazardous oxidative roasting and autoclave breaking-up for ore concentrates."

Jan 1, 2003

By G. Demi, G. Belardi, N. Shehu, S. Cico

The physico-chemical interaction between minerals such as olivine, chromite and serpentine and the ions most commonly present in solution, like Ca and Mg and flotation reagents such as EDTA and oleic acid was investigated. The study was conducted via release tests, electrophoretic measurements and microflotation of selected minerals coming from the Kukes deposit (Albania). The results were confirmed by means of beneficiation tests on various types of ores, from the Kukes (Kalimash), from Bulquiza area and from the Rizo deposit (Greece). It has been demonstrated that when Na-K Oleate is used as collector chromite, olivine and serpentine can be separated at pH = 2.5 and/or 5.5 employing EDTA (EthyleneDiamineTetraAcetate) on previously deslimed material. This approach ensures flotation concentrates with a Cr2O3 content about 50%, at a recovery in excess of 65%.

Jan 1, 2003

By P. Huang, D. W. Fuerstenau

Various factors that control the natural flotability of talc, including differences due to crystal face and edge effects, were delineated. For study of talc depression phenomena, dextrin was used as a model depressant. For the enhancement of talc flotation, dodecylammonium acetate (DDAA) was used as the collector. The interaction of DDAA with talc was assessed by flotation experiments and electrokinetic (zeta potential) measurements, from which the role of hydrophobic bonding can be demonstrated. The results presented in this paper provide useful information on how the crystal chemistry and surface chemistry control the electrical double layer, adsorption phenomena, wettability, and flotation behavior of talc in aqueous media.

Jan 1, 2003

By de Vaux. D.

Synthetic water with a calcium concentration of 80 ppm and 500 ppm was prepared and the flotation results obtained compared to a simple electrolyte in order to determine the effect water quality has on pentlandite and pyroxene surface alteration and, ultimately, floatability. During the study, the possible effect of interactions between the minerals investigated and Ca2+ ions in the presence of sodium isobutyl xanthate was studied at pH 6 and pH 9 by means of zeta potential determinations, microflotation tests and ToF-SIMS analysis. The results obtained have demonstrated that water quality does play a significant role in flotation recovery at the experimental conditions used.

Jan 1, 2003

By K. W. Stöckelhuber, A. Wenger, H. J. Schulze

"An important elementary step of the flotation process is the forming, drainage and rupture of a thin intervening liquid film between bubble and mineral particle.After the encounter of the bubble with the solid surface a wetting film is formed. The initial thinning of this film is driven by the capillary pressure inside the bubble. When the film has reached a certain thickness rupture can take place.There are two possible mechanisms describing this process:-, Growing fluctuation waves (spinodal dewetting) on fluid interfaces under the influence of any kind of attractive forces (electrostatic, van der Waals). -, Nucleation inside the film.Metastable wetting films on negatively charged, hydrophobic glass surfaces (gaseous phase methylated), or on hydrophilic, positively charged glass surfaces (with Al3+ ions), have been analysed by means of the kinetics of film thinning according to the Reynolds law. These experiments demonstrate that both mechanisms can be responsible for the rupture of a thin wetting film. In the case of hydrophobic surfaces the nucleation mechanism is preferred; in the case of opposite charged silica surface the capillary waves mechanism due to an attractive electrostatic double layer force between silica and air bubble takes place.Hereby the existence of a long range hydrophobic force. on a hydrophobic surface can be excluded. The apparent interaction can be explained by the presence of gas nuclei formed on heterogeneous surface sites. The results provide deeper insight into the mechanisms of wetting film stability, adhesion process in flotation and droplet coalescence."

Jan 1, 2003

By P. Harris, D Bradshaw

"Comparison of the two most commonly used classes of depressant in the South African platinum industry is complicated by the fact that these polymers induce different effects on the surfaces onto which they adsorb. The use of carboxymethyl cellulose (CMC), which is ionically charged in solution, can lead to increased particle dispersion in addition to the effect of reduced surface hydrophobicity (depression). Guar is typically only slightly charged in solution. Comparison of these two depressants is complicated since it is uncertain whether differences in their action is a result of either depression of dispersion effects.This work investigates the role of dispersion independently to that of depression in the batch flotation of a platinum bearing ore. An inorganic dispersant, sodium hexametaphosphate (NaHMP) was added in parallel to the uncharged guar depressant to simulate the action of depressants with varying degrees of dispersion. By distinguishing between the material recovered by entrainment and the floatable gangue and by including the effects of froth stability it was possible to decouple the effects of dispersion and depression.The results show that both dispersion and depression led to increased grade of the sulphide minerals. Depression leads to a decreased recovery of floatable gangue minerals. Dispersion leads to an increased recovery rate of these minerals and an accompanying decrease in froth stability."

Jan 1, 2003

By David Dreisinger

"The leaching of base and precious metal ores and concentrates continues to progress in both laboratory study and industrial application. These developments are being driven by the need to respond to difficult ores and concentrates that are not amenable to conventional treatment. In many cases alternatives are being developed to conventional treatment (e.g. Pyrometallurgy) for technical and economic reasons.In this paper, a brief general review of some new developments in leaching will be followed by a more detailed explanation of three process developments that have either been industrially applied or are expected to be applied in a short time frame. The three processes to be reviewed in detail are the Mt. Gordon Copper Process, the Anglo American Corporation/University of British Columbia Copper Process and the PLATSOL Process. These leaching processes operate at low (90°C), medium (150°C) and high (220°C) temperature and are successful in quickly and completely extracting metal values from ores and concentrates.INTRODUCTIONThe process of leaching is widely used in hydrometallurgy to selectively recover a metal of interest from an ore or a concentrate. Leaching and by extension hydrometallurgy is well established in the recovery of copper (copper heap leach ? SX-EW), nickel (Moa Bay and Caron process), zinc (roast ? leach ? electrowin and zinc pressure leach), gold (cyanidation) and uranium (acid sulfate leach). Of course this success extends to many of the metals found in nature. Recently, the importance of hydrometallurgy appears to be increasing with hydrometallurgy viewed as an attractive alternative to both traditional mineral processing and conventional smelting/converting/refining. This increasing interest has led to intensive study and increasing application. Selected developments include:Copper ? the Mt. Gordon process and new concentrate processes such as INTEC, Activox, CESL, Dynatec, Total Pressure Oxidation, MIM Albion, BioCop, and the AAC/UBC Process.Nickel ? Voisey Bay process for hydrometallurgical treatment of Voisey Bay concentrate, HPAL processing of laterites at Murrin Murrin, Bulong and Cawse, atmospheric leaching of laterites, heap bioleaching of nickel sulfides by Titan Resources (Australia).Zinc ? establishment of zinc leach, solvent extraction and electrowinning technology for treatment of the Skorpion deposit in Namibia, new developments in atmospheric and pressure leaching, the Hydrozinc process.Gold ? development of a number of thiosulfate leaching processes for recovery of gold from refractory carbonaceous ores or concentrates."

Jan 1, 2003

By Gerke Gilian, Pretz Thomas, Pehlken Alexandra

"The evaluation of health hazards within the treatment of mineral and waste materials is gaining more and more importance in industrial countries. The need to control occupational safety has been recognised, and regulations which describe general protective measurements for personnel provide a tool to protect their health. It is the aim of the paper to give an outlook for practical approaches to risk assessment and to present measures for exposure reduction in accordance with the state of the art in Germany.Both the treatment of minerals and of waste materials are described in relation to the risk assessment. The method of evaluating health hazards in the two industries is similar and therefore both examples are presented next to each other.The example presented in the paper is the German “Biostoffverordnung” (the regulation for biological materials) which is important for the waste treatment industry. All kinds of waste treatment facilities (like composting facilities, waste dumps, sorting facilities for packaging materials) are obliged to carry out an assessment of health hazards for a variety of working areas and working places. The possible safety requirements deriving from this regulation are presented and discussed under the aspect of biological hazards.All over the world each country has different guidelines and regulations but all have one target in common – to protect the employees. This can be achieved through a good management system of occupational health and safety. Therefore the health hazards have to be known and assessed.Principles of the assessment of health hazards are described through:Data collection on siteData evaluationAssessment of health hazardsDocumentation"

Jan 1, 2003

By Máximo Pérez, Julio C. Videla, Rosa Dzioba

"This paper reports the hydrometallurgical treatment of gravity concentrates of gold samples and outcrops associated with graphite ores obtained from:- flotation tailings of crystalline graphite minerals- outcrop samples of graphitic rock associated with auriferous minerals and free gold located in the Villa Union district and surrounding areas - La Rioja Province - Argentina.Previous studies of the flotation potential of crystalline graphite minerals failed to consider the presence of noble metals.The samples represent a mineralized zone of crystalline graphite which is distributed in different formations with a NE - SW trend in Maz, Punta Colorada and Las Ramaditas hills, covering an area of about 300 square kilometers.The most important variables affecting the leaching process, such as grain size, mineralogical species, reagent consumption, and so on, were previously studied. (Weiss, L.1985)On the basis of the present study results, the possible definition of an economically viable mineralization will be analyzed to define an auriferous district."

Jan 1, 2003

By Hamid-Reza Manouchehri

"The triboelectric charge attributes of feldspar, quartz and wollastonite minerals, after contacting different triboecharging medium made of different materials, were considered. Their charge acquisitions by different size fractions of minerals were monitored and accordingly their energetic work function values were estimated. Moreover the separation behaviours of these minerals through the electric field of a laboratory free falling separator were determined and the effects of some chemical reagents on separation their separation characteristics were studied.Finally an attempt was made to translate the findings from single mineral systems to a complex silicate ore, containing quartz, feldspars, wollastonite and some other silicates. The results show favourable prospect to apply the triboelectric separation technique for beneficiation such a complex raw material."

Jan 1, 2003

By Takashi Furuyama, Sukeyuki Mori, Tetsuo Ikejiri, Abel Bissombolo, Yoshitsugu Koga, Masamichi Hata

In Japan, the increasing number of automobiles newly put into circulation is followed by a larger amount of end-of-life vehicles from which valuable metals are being recovered in shredder and related plants. Nevertheless, the processing of these scrapped automobiles which has reach a recycling rate of about 75%, generates a huge volume of waste, locally known as .shredder dust., which is commonly dumped on landfills. The saturation and depletion of valuable disposal sites in the near future, as well as the social and environmental problems related to the accumulation of these residues disposals are a major challenge for the automobile shredding industry. To promote an alternative way for the management of these disposals, the authors have initiated and developed a system for their processing, on the basis that more than 90% of these residues are combustible materials that could be used as refuses derived fuel. The developed processing system points out the mechanical/physical separation of shredded automobiles residues into two streams by means of an ascending airflow passing through a vertical zigzag separator and, the compaction of the light-density fraction of materials (that is about 60% of auto shredder residue recovered as float products and mainly composed of cotton, sponges and light plastics) to form a refuse derived fuel (RDF), the density, calorific value and ignition loss of which are 1.19 g/cm3, 4470 kcal/kg and 60.7%, respectively.

Jan 1, 2003

By Olgac Kangal, Ali Guney, Gulay Bulut, Guven Onal, Ayhan A. Sirkeci

This paper presents the results of pilot scale column flotation applications in the two different copper concentrators in Turkey. The Kure Copper Plant is located in the Black Sea Region of Turkey. In Kure, a very fine grinding requirement for an adequate level of liberation makes a successful flotation difficult and consequently the final concentrate can hardly assay above 16% Cu Column flotation tests were conducted at the plant site using two different column types The experiments proved that the grade of the concentrate could be increased from about 14% Cu to 25-26% Cu. Murgul Cakmakkaya Copper Concentrator is the largest copper concentrator in Turkey. Although concentrate production capacity is around 170,000 tons annually with 22-23% Cu content, this figure tends to be much lower than that. In Murgul a Turbo Column of Multotec Company of South Africa was employed. As a result of systematic column flotation tests, the grade of the concentrate was increased from 20.3% Cu to 28.7% Cu.

Jan 1, 2003

By Rodney J. Hundermark, Sharif Jahanshahi, Shouyi Sun

"The major platinum producers in South Africa make use of electric furnaces for the melting of PGM bearing nickel - copper concentrates. To gain better understanding of the furnace operation, research was conducted at CSIRO Minerals in Melbourne, Australia. One aspect of the research project was the investigation of the factors affecting the electrical conductivity of melter type slags.Electrical conduction in slags can occur through two mechanisms: ionic and electronic. There is good understanding of the ionic mechanism. In slags containing high levels of iron, the dominant mechanism is electronic. There is limited understanding of the electronic mechanism and one of the aims of the research was to investigate this mechanism further.Experimental work was carried out on Al2O3.CaO.FeOx.MgO.SiO2 slags similar in composition to the melter slags. Conductivity increased significantly with iron oxide content. Above 20wt% FeOx, electronic conduction was significant and the conductivity varied with the oxidation state of the slag. As the iron oxide content was increased further, the electronic mechanism became more dominant. The conductivity reached a maximum at around pO2 = 10-7 to 10-4 atm., although this value was dependent on the total iron oxide content and basicity of the slag."

Jan 1, 2003

By James A. Finch

"Developed countries are in the midst of re-structuring education in minerals-related disciplines as raw materials, once vital to wealth generation, contribute progressively less to the economy. The changing circumstances mean institutions must justify mineral processing by new criteria. After considering what a mineral processor needs to know the ways to deliver are considered. Taking twenty graduates per year to illustrate, one institute could justify this number as a program in a department or school (of whatever grouping of disciplines). A strong research component would make the package additionally attractive. Divide among four institutions and mineral processing is best served in a research centre with delivery taking advantage of multi-centre and distance learning opportunities.INTRODUCTIONThis is one of five plenary lectures at the Congress. I may have preferred a technical subject, as that is what occupies most of my thinking hours, but it is reasonable as an academic that this topic should come to one of us. The fact the topic has not been high on my agenda may provide one advantage: that I can suggest directions free of pre-conceived notions, just as when reviewing the background to a technical article the temptation to select in support of one?s interpretations is resisted. The trick will be to add something new.One reading of the title seems to query whether mineral processing education has a future. (I will refrain at this juncture from defining mineral processing and assume for now we share an understanding of the term.) The proximity of natural and human resources led to the Industrial Revolution and the interaction continues to stimulate and sustain industrial and economic development in many parts of the world. The search for raw materials has historically played a key role in opening frontier areas, with undersea and outer space next. The reason is obvious: raw materials along with food and energy underpin society. Thus mining will remain part of human activity along with the need to pass on the knowledge and skills.What happens over time is resource relocation. Raw materials become exhausted in one area to be replaced by sources elsewhere; the demand for some materials lessens while growing for others. Educational institutions can find themselves with the wrong geography or with staff focussing on the wrong subjects. When this happens the restructuring produces much discussion. This is where we are in parts of the world. Japan, Western Europe and the United States are the prominent examples (Dowd, 1998; Flemings and Suresh, 2001; McDivitt, 2002). Mineral processing is becoming a series of courses in related disciplines: resource engineering, environment engineering or materials engineering. The start of the transition is evident in Canada and Australia, perhaps earlier than expected given the contribution of raw materials to their economies. A common backdrop in the developed countries is social pressure to reduce the impact of the ?untidy? aspects of life, and that includes mining. (This is not new: in classical times the mine face was the preserve of slaves and convicts.) These values are exportable, potentially affecting recruitment into mining schools everywhere."

Jan 1, 2003

By André Mans, Frans B. Waanders

Current losses of Ferrosilicon (Fe-Si), which is used in the dense medium separation (DMS) of iron ore at Kumba Resources, Sishen, South Africa occur due to adhesion to the separation products and also by being present in the effluent stream, due to abrasion. The losses contribute greatly to the running cost of the plant and the purpose of this project was to determine the characteristics of the unused Fe-Si and then to characterise the changes that occur during storage and the use thereof. A Scanning Electron Microscope (SEM) and Mössbauer Spectroscopy (MS) were used to investigate the characteristics of the fresh and used Fe-Si. It was found that the biggest loss of Fe-Si was due to the abrasion of the particles during the DMS process, which resulted in the liberation of Fe and subsequent formation of an oxihydroxide froth. A possible change in magnetic properties was also observed, leading to further losses that could occur during prolonged use of the medium. No clear changes to the Fe-Si occurred during correct storage methods, as was initially thought.

Jan 1, 2003

By U. M. J. Boin, W. L. Dalmijn, T. P. R. de Jong

"This paper explores the complex interrelationship between the resource cycle, recycling and metal production as a function of economics, environmental legislation, and product design. It is argued that central to optimising this resource cycle lies the control in particular of physical separation plants by the application of advanced sensor technology and sorting equipment, as well as suitable control and sampling algorithms supported by optimising mass balance models.Metals are produced through a long chain of processes. For primary resources, metals production goes through mining, mineral processing, ore smelting, conversion and refining steps or via low temperature hydrometallurgical processes, or a combination of both pyro- and hydrometallurgical operations. For the recycling of resources, metals are separated and recovered from metal scrap, which plays an increasingly important role in the world. Metals after being produced, either from primary or recycling resources, have to be further refined or manufactured into various types of alloys and finally shaped into different products for the end-users. Since the end-user discards products the contained materials find their way back into the resource cycle as scrap. Therefore, controlling the metallurgical reactors also controls, in a much broader sense, the material quality in the complete metals cycle, from the production phase, to the end-use phase, up to the recycling phase (Reuter et al., 2003). The recycling phase includes separation of materials into saleable intermediate products, which are reintroduced into the production phase as a recycling resource. Therefore, the metallurgical processes in each unit operation in the metals production and processing chain have to be controlled, so as to achieve optimal performance of high product quality, low energy and materials consumption, and low environmental impact."

Jan 1, 2003

By Keith Spence

"The notion of ""value"" has always been a subjective and contentious issue. Indeed, Value is in the eye of the beholder. There are varied methods and practices for valuing property, as there are industries in which they are applied. For example, there are ""replacement value"", ""insurance value, ""salvage value"", ""appraised value"", ""book value"" and ""fair market value"", to name a few, although in the mining industry, valuations usually refer to fair market value.In the Canadian mining industry, at present, there are no comprehensive regulations or guidelines that specify which approaches or methods are appropriate for use in the valuation of mineral projects. In January 1999, The Mining Standards Task Force of the Toronto Stock Exchange and the Ontario Securities Commission recommended that the Canadian Institute of Mining, Metallurgy and Petroleum establish a committee to review and advise on approaches and methodologies for the valuation of mineral properties. Among the approaches to be considered, are included the following: the Discounted Cash Flow Approach, the Cost Approach, the Option Pricing Approach and Market Comparables Approach. In addition, methodologies differ depending on whether the project is at the exploration stage or the producing stage.The CIMVal committee expects that its final report will form the basis for a standard Canadian Code for the valuation of mineral properties."

Jan 1, 2003

By Benoit Clermont, Jan Lux

"Magotteaux and Anglo Platinum started a co-operation program with the main aim of establishing the optimum milling configuration measured in terms of throughput, fineness and energy consumption.For this purpose, a fully instrumented pilot milling plant, supplied by Magotteaux (Pty) Ltd, and equipped with a 0.9 x 1.0 m ball mill, was erected at Frank concentrator (Merensky Pt ore). The primary ball mills at Frank concentrator were surveyed in order to set the conditions for the base case. This data was then replicated in the pilot mill under the same configuration. Thereafter, a series of different parameters were varied in order to attempt to optimize the milling system.Some of the grinding parameters that have been studied are:•,Gate versus overflow discharge•,Open versus closed circuit•,Different filling degrees•,Different shell liner profilesOnly grate versus overflow discharge and open versus closed circuit will be discussed in this paper.It should be noted that this paper does not attempt to give a universal solution as to what milling configuration is optimum in all cases. The conclusions apply for this particular case and probably most others, but it would be advisable to consider each case on its own."

Jan 1, 2003

By Karl J. C. Harries

Mineral Agreements and Royalties

Jan 1, 2003