Search Documents

By Q. C. Reynolds

Keywords: Pyrometallurgy, plant, photography, GIS, satellite images, Google Earth Google Earth is a piece of software able to display an interactive three-dimensional map of the world, combining aerial and satellite photography with maps, terrain, and user-generated geographical information systems (GIS). Many structural features of the planet, both natural and man-made, are of great interest to the mining and metallurgy field, and in this paper a study is made of the current state of the art of data accessible by Google Earth.

Jan 1, 2006

By W. P. Johnstone

The computer assisted generation of geological models to represent the geometry of, and grade distribution within, orebodies is a rapidly growing area of the geological profession. Such models are increasingly used as a necessary starting point in determining the mineability of mineral deposits in terms of practical mine design and economic considerations. The transition from traditional techniques such as field or underground mapping and the manual calculation of grade and tonnage estimates, as well as related activities such as the interpolation of cross-sections, the use of stereographic projections, core logging and hand contouring, to computerized applications, is by no means complete. In fact, many geological professionals deliberately avoid the use of computer simulations based on the perception that the resulting models are simplistic and that their construction is not founded on sound geological principles. The purpose of this paper is to assess current thinking on this topic by considering; (a) an overview of advances in the drafting of geological maps, (b) the theoretical basis for multi-dimensional geological modelling, (c) the case for combining traditional and modern techniques, and (d) the benefits to the mining value chain.

Jan 1, 2003

By C. A. Ozturk

The compressive strength of rock (sc) has an important effect on design of structures in rock engineering. Compressive strength can be determined in the laboratory using the uniaxial compressive strength (UCS) test. Some other index tests, such as the point load test, are also used, particularly when suitable samples for UCS are not available. The quantification of rock texture has introduced a new method in rock engineering for estimating the mechanical and physical properties of rock materials from microscopic investigations. The aim of this study is to quantify rock texture to estimate rock strength from the texture coefficient (TC), which is determined from a statistical assessment of thin section images. Rock texture is quantified by twelve different images from a single thin section to increase the reliability of texture analysis. A data-set is prepared to investigate correlations between TC and sc. The statistical correlations are computed after classifying of the rock samples based on their lithology as well as grain features. Equations derived based on the results of this study are used to predict the approximate value of compressive strength from the texture coefficient. This method is particularly useful for preliminary studies in rock engineering projects prior to detailed site investigation.

Jan 1, 2014

By L. A. Cramer

Platinum metal was first utilized by the Inca civilization in South America where it was found in alluvial deposits along the San Juan and Atrato rivers that lie between the Andean mountain range in Colombia and the Pacific Ocean. The nuggets found in these rivers average between 77% and 86%platinum, 7%?8% iron and small amounts of copper, gold and other Platinum Group Metals (PGMs). The Incas often alloyed platinum with copper to increase its workability and fabricated various ornaments from it.

Jan 1, 2001

By Klaus Hasselwander

Fluctuating SO2 gas streams represent a difficult task for designers of SO2 removal systems (with respect to designing the plant), but in spite of the designers great efforts to solve the problems, the operation of such plants requires much care and attention. A fluctuating gas flow usually results from metallurgical smelting processes. Both gas composition and gas flow rate may vary. The first part of this paper outlines some existing technical solutions and presents the Pros and Cons of the different solutions. These solutions outline are: - Sulphuric acid plants operated with a preheater permanent in operation - Sulphuric acid plants with concentration increase of SO2 gas either using regenerative SO2 removal or cryogenic partial condensation of the SO2 - Sulphuric acid plants with additional burning of sulfur to increase SO2 content - Single-stage sulphuric acid plants followed by a tail gas system (which is) designed for periods of low SO2 input In the second part, this paper describes some existing technical solutions for removal of SO2 at low concentrations (i. e. less than 0.1 - 2 %-by volume), which could be used as tail gas treatment system for acid plants. While selecting an appropriate solution, special attention should be given to operating costs, which usually to a large extend depends on the type of absorption agent and the costs for disposal of the sulfur compound produced.

Jan 1, 2009

By H. F. Niemand, C. J. Postma, P. L. Crouse

"SynopsisThe separation of zirconium and hafnium is essential in the nuclear industry, since zirconium alloys for this application require hafnium concentrations of less than 100 ppm. The separation is, however, very difficult due to the numerous similarities in the chemical and physical properties of these two elements.Traditional methods for separation of zirconium and hafnium rely predominantly on wet chemical techniques, e.g. solvent extraction. In contrast to the traditional aqueous chloride systems, the AMI zirconium metal process developed by Necsa focuses on dry fluoride-based processes. Dry processes have the advantage of producing much less hazardous chemical waste.In the proposed AMI process, separation is effected by selective sublimation of the two tetrafluorides in an inert atmosphere under controlled conditions, and subsequent selective desublimation. Estimates are made for the sublimation rates of the two tetrafluorides based on the equilibrium vapour pressures. A sublimation model, based on the sublimation rates, was developed to determine if the concept of separation by sublimation and subsequent desublimation is theoretically possible.IntroductionZirconium requires several purification steps to conform to nuclear-grade specifications. Little information is available on the sublimation separation of Zr and Hf compounds, especially in the fluoride form, the majority of which deals with sublimation under vacuum conditions. On the industrial scale, only vacuum sublimation of ZrF4 has been reported. No records were found for the sublimation of ZrF4 in an inert atmosphere. Information on the sublimation rate of ZrF4 or HfF4 in an inert atmosphere is also limited. The rate is assumed to be dependent on several factors, of which temperature, area, and composition are considered the most important."

Jan 1, 2015

By D. J. Adams, W. K. Rymon-Lipinski

Rock engineering plays a crucial role in contributing to sustainable development in South African mining. A framework for this has been created through legislation and structures to encourage the mining industry to have a long and prosperous future. However, rock engineering input is an essential element to achieving success. The most accessible deposits have been mined in South Africa and although large reserves still remain, many of these are difficult to access and will require excellent rock engineering knowledge and skill in the future. This is borne out by the fact that more than 50 % of fatal accidents are related to rock engineering issues. Many of these may be addressed with rock engineering solutions which are not beyond current rock engineering technology. A reduction in fatalities and injuries contributes to a sustainable mining industry.

Jan 1, 2003

By Huang Zhiwei, Paul Skayman, Kevin Holley

In 1989 The First Brigade for Geology and Mineral Exploration of Qinghai Province discovered gold at Jinlonggou and Qinlongtan, Tanjianshan. Between 1992 and 2002 small scale mining was carried out at these sites using underground mining methods at Jinlonggou and an open pit at Qinlongtan. During 2003 and 2004 geotechnical investigations were carried out in support of a bankable feasibility study. An important objective of this investigation was to meet both internationally accepted standards and codes of practice, and also to satisfy the Chinese requirements. Extensive use of local experience was utilised. Where possible geological drilling information was incorporated into the assessment. Extensive geotechnical mapping of surface and underground exposures, and index testing to gain an appreciation of rock intact strength were used to characterise the sites. Rock mass classification (MRMR) was used to assess indicative overall slope angles and appropriate bench stack heights for the proposed pits at Jinlonggou and Qinlongtan. Measured discontinuity orientations were used in kinematic analysis to assess stability of possible pit slope geometry at a batter and overall scale to provide preliminary recommendations for the pit slope configuration. Numerical modelling was also carried out to improve the understanding of anticipated pit behaviour. Site investigation and preliminary geotechnical design details, that incorporate site specific conditions for the formation of open pits at Tanjianshan, are discussed in this paper.

Jan 1, 2006

By M. G. Maruma

The effect of the amount of cold reduction and annealing temperature on the evolution of the texture of AISI 441 steel is reported. The steel was cold rolled by 62%, 78%, and 82%, followed by isothermal annealing of each sample at 900°C, 950°C, and 1025°C for 3 minutes. The crystallographic texture was determined by Phillips X?Pert PROMPD texture diffractrometer. Microstructures were characterized using optical microscopy and scanning electron microscopy (SEM).The results show that sample that received 78% cold reduction and annealing at 1025°C presented the highest Rm-value and lowest ?R-value, which would enhance its deep-drawing capability. In addition, this sample showed the highest intensity of shifted ?-fibre, notably {554}<225> and {334}<483>. It can therefore be concluded that the ?-fibre, which favours deep drawing, is optimal after 78% cold reduction and annealing at 1025°C.

Jan 1, 2013

By L Singheiser, W. Willenborg, M. Mueller, K. Hilpert

The limitation of fossil fuel resources and the necessity of reducing CO2emission require an increase of the efficiency of power plants by using combined cycle power systems. Pressurized Pulverized Coal Combustion (PPCC) is a potential concept to realise these objectives. The direct use of hot flue gas for driving a gas turbine requires a hot gas cleanup to achieve corrosion prevention of the turbine blading. One of the main problems is the alkali release during the coal combustion process. Molten coal ash slag has a high potential for alkali retention which depend son the alkali oxide activity in the slag. Knudsen Effusion Mass Spectrometry (KEMS) was used to determine thermodynamic data of alkali gas species over molten coal ash slags and of alkali oxides in molten coal ash slags. The main interest of the investigations focused on the structural dependence of the thermodynamic properties of the alkalis. It was found that there is a strong correlation between the thermodynamic properties and the ratio of nonbridging oxygen to tetrahedral oxygen (NBO/T). An increase of the polymerization of the slag results in a decrease of the alkali oxide activity in the slag and thus a decrease of the alkali partial pressure over the slag. Keywords: coal ash slag, structure, alkali oxide activity, alkali vapour pressure, PPCC, KEMS.

Jan 1, 2004

By K. Schwerdtfeger

Data are presented on the effect of iron oxide on the electrical conductivity of CaO-SiO2-FeO-Fe2O3melts, and on limiting current and impedance in direct current or alternating current charge transfer at iron electrodes. The strong influence of iron oxide content can be utilized for in situ determination of total iron oxide content and Fe3+/Fe2+ratio. The possible probe designs are presented and the principles and procedures of the measurements are explained. Keywords: in situ probe for iron oxide determination in steelmaking slags, electrical conductivity of CaO-SiO2-FeO-Fe2O3slags, direct current over voltage and alternating current impedance at iron/slag electrodes.

Jan 1, 2004

Viscosity measurement was carried out over a narrow range of silica content around the fayalite composition. A wide range of temperature and oxygen potential was covered where the slag was completely liquid. In order to keep the slag composition and the Fe3+/Fe2+ratio constant, theCO2/CO ratio was kept constant as the temperature was varied. Increasing the Fe3+content has little effect on viscosity for slags with a silica mole fraction of 0.31. At higher silica contents, increasing the Fe3+content brings about a small decrease in the viscosity.

Jan 1, 2004

By A. D. Pelton

The evolution of thermodynamic models of molten salts and slags, starting with Temkin in 1948, has culminated in today?s sublattice models. These modern models have permitted the development of large thermodynamic databases of model parameters, which can be used to calculate and predict accurately the properties of multicomponent solutions. The model parameters are mainly obtained by the critical evaluation and optimization of available thermodynamic and phase equilibrium data for binary and ternary subsystems. The models are then used to estimate the properties of multi component slags and salts from these assessed binary and ternary parameters. When used in conjunction with thermodynamic databases for solids and solid solutions (salts, oxides, sulphides, metals, etc.), other liquid solutions (such as liquid metals),and gases, these databases permit the calculation of complex multiphase equilibria in multicomponent systems, with applications in a wide variety of industries. These calculations can be performed with general commercial software for Gibbs energy minimization, which can also be incorporated into process simulation software packages. Keywords: slags, salts, solution models, thermodynamics, phase diagrams, oxide systems, molten salts

Jan 1, 2004

By C. M. Rule

Stirred milling using either horizontal or vertical mills has made a rapid entrance into PGM ore and tailings concentrator flow sheets. Currently there are in excess of 40 units installed in either mainstream, ?MIG? or intermediate concentrate regrind, ?UFG?, applications in PGM, primary ore treatment plants or in tailings scavenging and reclamation treatment plants. This represents a total of approximately 70 MW of installed fine grinding equipment. This paper outlines the reasons why the technology take-up has been rapid and illustrates the advantages of this technology over conventional milling. Keywords PGM, platinum group metals, UG2, Merensky, platreef, stirred milling, MIG?mainstream inert grinding, UFG?ultra fine grindingof intermediate flotation concentrates, IsaMill?, Metso SMD?, Deswik, ceremic grinding media, QEMSEM, MLA.

Jan 1, 2011

By A. M. Hefny, F. P. Siew, P. G. Ranjith

Fracture initiation and propagation, being one of the most intensive subjects in rock mechanics; contribute significantly to the deformation of jointed rock masses. An experimental study on fractured granitic rock was carried out to determine the peak strength of specimen under triaxial loading conditions. The commonly observed failure mode for rock specimens in this study was found to be the shearing of the plane of weakness. The minimum peak strength of fractured rock is observed when the joint orientation is approximately 70° to the horizontal axis. Based on experimental test data, an empirical expression was developed to accommodate the effect of joint orientation and joint trace length in estimating the peak strength of fractured rocks. The predicted values of peak strength using the proposed equation well agree with the experimental results carried out on singly fractured specimens under triaxial loading conditions. The threshold stress values of crack initiation and propagation depend on joint geometrical parameters, their degree of interconnectivity, as well as surrounding stresses on the fracture plane.

Jan 1, 2003

By Rodney Ishak, Merete Tangstad

In the HC FeMn production, better utilisation of coke and electric power is vital for reducing the production costs. The higher manganese oxides in the charge are reduced to MnO in the prereduction zone, where also the Boudouard reaction is active. These gas-solid reactions are to a large extent decisive for the total consumption of both coke and electrical power in ferromanganese production. In the present work formulas for calculating the Degree of prereduction have been developed for industrial practice. It shows that the typical Degree of prereduction is between 10-40%, but it may in good periods be as high as 60%. Statistical analysis has been done in order to find how various operational parameters influence the Degree of prereduction. A few parameters were observed to have an effect on the prereduction. Comilog ore definitely had a positiveinfluence on the prereduction, Comilog sinter and Mamatwan ore probably had a positive influence on the prereduction, all in relation to the average prereduction in the selected periods. Meanwhile, As man ore definitely, % H2O in raw materials and increasing Hd probably, had a negative influence on the prereduction. The findings for these raw materials were very much in coherence with the results of laboratory scale experiments performed, where the CO-reactivity of different ore materials was studied.

Jan 1, 2007

In the 1980s and?90s the gold mining industry in South Africa came under pressure from the continued poor dollar gold price and escalating Rand based costs, furthermore the external impacts on the industry were changing. Thus, the Chamber of Mines (COM) shifted its focus away from many historical areas of support towards the new industry challenges in safety and health, labour markets, environmental responsibility, mineral rights legislation and social responsibility. During 1997 the lack of funds and the changes facing the tertiary institutions were often subjects of discussion at the various sub-committee meetings. The Metallurgical Sub-committee of the Chamber Education Fund or the Sub-committee of Consulting Metallurgists as it was known identified the need for the funding structure to change with the times. Up to this time the Chamber of Mines operated an Education Fund that supported mining industry academic departments at various South African tertiary institutions; these funds were derived exclusively from the country?s gold and coal mines the basis of Chamber membership. Funds of less than R5 million per annum were available for distribution by the three disciplinary sub-committees of mining, metallurgy and geology.

Jan 1, 2003

By I. Matsunaga, K. Aoki, W. -j. Jung

Blasting is widely used in mining and basic construction because of its speed and economy to destroy the rocks. Blasting has the advantages of reduced excavation costs and shorted construction time when compared to the use of heavy machinery for excavation and cutting such as that with a tunnel boring machine. There are numerous problems with blasting, including the noise, vibration and fly rock. So it is necessary to accurately evaluate fracture mechanics of rocks on the dynamic loading condition to control the fracture process of the blasting. The tests using Hopkinson&apos;s effect for the dynamic condition using the precise detonators were performed for various strain rates on three different kinds of rocks. In the tests using Hopkinson&apos;s effect for the dynamic condition, the high-speed camera was used to observe the fracture process of the test sample rocks. As the results of experiments there was an increase in the tensile strength of rock with an increase in the strain rate for three kinds of rock on the dynamic loading. The tensile strength of rocks with high porosity on the water saturation condition was decreased on the both static and dynamic condition. It is clear that the strain rate and water saturation were influenced to the tensile strength of the rocks.

Jan 1, 2003

By M. Kawakami, K. Suzuki, T. Takenaka, S. Yokoyama

Molten NaNO3-NaNO2-KNO3mixture is used as a heat transfer medium at high temperature. One of the most important properties of this mixture is the heat capacity. In the present work, the enthalpy change with temperature was measured by the drop calorimetric method to evaluate the heat capacity. The results are summarized as follows: The enthalpy of the mixture increased linearly with the temperature. From the slope of the line, the heat capacity was evaluated. The heat capacity of pure NaNO3, NaNO2and KNO3was 0.129,0.110 and 0.142 kJ/mol/K, respectively. These values are in fairly good agreement with the published data. In the binary and ternary systems, the molar additivity of heat capacity, which is well known as Neumann-Kopp’s law, was obtained. The heat capacity of HTS1and HTS2, which are well known ternary mixtures of practical use, were in the range of published data.

Jan 1, 2004

By R. J. Hundermark, L. R. Nelson

The critical importance of tap-hole design and management to furnace performance and longevity is explored through examining some of the specific matte, metal and slag tapping requirements of non-ferrous copper blister and matte converting and smelting, ferroalloys smelting and ironmaking systems. Process conditions and productivity requirements and their influence on tapping are reviewed for these different pyrometallurgical systems. Some critical aspects of the evolution of tap-hole design to meet the diverging process and tapping duties are examined. Differences and similarities in tapping practices and tap-hole management are reviewed. Finally core aspects of tap-hole equipment and maintenance are identified that are considered important to securing improved tap-hole performance and life, so pivotal to superior furnace smelting performance.

Jan 1, 2014