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By J. A. Kromhout, J. Trouw, A. A. Kamperman, M. Kick

Mould powders play an important role in the stability of the continuous casting process. The main functions of mould powders are to provide sufficient lubrication and to control the horizontal heat transfer. Because process control of thin slab casting is more stringent, it is generally assumed that mould powder properties become more critical as well. In 2000, the Direct Sheet Plant at Corus IJmuiden (DSP) was commissioned, incorporating a thin slab caster designed for casting speeds up to 6 m/min. During commissioning, several operational problems with mould powders were encountered i.e. insufficient liquid pool depth and the formation of rims/lumps. To investigate the operational mould powder problems, some of the mould powders were characterized using physical and mineralogical methods. The results were linked to operational experiences. It was concluded that for thin slab casting, a stable slag formation is obtained with a proper choice of free carbon and an even distribution of the carbon particles within the granules. The physical properties of mould powders are not as critical as expected when the additional mineralogical requirements are taken into account. Keywords: mould powder, characterization methods, thin slab casting.

Jan 1, 2004

By Yijun Caoa, Xiuxiang Taoc, Zhongbo Hub, Yinfei Liaoa

A new preparation scheme for a difficult-to-float coking coal from the Kailuan Mine, Tangshan, China was investigated. The results showed that grinding followed by column flotation was beneficial for obtaining products with low ash content. The positive effect of grinding on the coal floatability is attributed to the liberation of intergrowths and coal surface improvement. Tests indicated that 10 minutes was the optimum grinding time, and over grinding resulted in a deterioration in flotation performance. With a grinding time of 10 minutes, conventional flotation had potential to yield a product with around 12.42% ash content and 69.15% combustible recovery. Column flotation can reduce the product ash content to 11.15%and increase combustible recovery to 74.47%. Consistently better flotation results reveal that column flotation is more efficient than conventional flotation for such fines.

Jan 1, 2015

By Mike McWha

Drivers to increasing RM use ?Compliance issues ?Section 12 JSE Listing Rules ?Canadian NI 43-101 ?Sarbanes Oxley ?Shortage of African ore reference materials ?Poor perceptions about quality of some local RM?s

Jan 1, 2005

A comprehensive review of ore pass records, from ten Quebec underground mines, indicated some of the limitations of available design tools to predict the occurrence of ore pass interlocking hang-ups in metal mines. The Distinct Element Method was used to perform a series of numerical experiments in order to investigate the influence of ore pass geometry, rock fragments shape and size distribution on material flow in an ore pass. Guidelines have been developed to help limit the occurrence of interlocking hang-ups in an ore pass. The proposed guidelines were evaluated with respect to field observations. Ein kompletter Bericht der Erzrollezeichnungen, von 10 Quebec unterirdischen Gruben, hat einige der Beschränkungen der vorhandenen Designwerkzeuge angezeigt, um das Auftreten Erzrolle der blockierenhang-ups in den Metallgruben genau vorauszusagen. Eine Reihe numerische Experimente mit der eindeutigen Element-Methode, wurden aufgenommen, um den Einfluss von Erzrollegeometrie, Partikelform nachzuforschen und Felsenkorngrößenverteilungen auf Materialfluss in ein Erz überschreiten. Dieses hat zu die Entwicklung der Richtlinien geführt deren Implementierung das Auftreten der blockierenhang-ups in eine Erzrolle begrenzen sollte. Die vorgeschlagenen Richtlinien wurden in Bezug auf Labor- und Feldbeobachtungen ausgewertet. Une revue de la performance actuelle des cheminées à minerai dans 10 mines souterraines du Québec a indiqué les limites des outils de conception servant à dimensionner les cheminées pour minimiser le nombre d’accrochages par enchevêtrement rocheux. Des séries de modélisations numériques, utilisant la méthode des éléments distincts, ont été réalisées afin d’évaluer l’influence de la géométrie des cheminées, de la forme des fragments rocheux et de la distribution granulométrique sur l’écoulement du matériel dans les cheminées. Cet exercice a permis de développer des lignes directrices pour le dimensionnement des cheminées afin de limiter l’occurrence d’accrochage par enchevêtrement rocheux. Les lignes directrices proposées ont été évaluées en fonction des observations effectuées sur le terrain.

Jan 1, 2003

By L. Holappa

Ferroalloys like FeCr and FeMn are mostly produced in submerged electric arc furnaces. Typical for these processes is that the amount of slag is quite high. The role of slag for the process is thus very essential and specific chemical, physical and electrical properties are required. Slags in FeCr process are Al2O3-MgO-SiO2based with minor contents of CaO and CrOx. Slags in FeMn process are principally similar originating from silicate minerals but can have quite a large composition range depending on the manganese ore and its gangue minerals. Characteristic for FeMn process is that the slag is rich in manganese oxide up to above 30%. A common feature is that the ?ore oxides?, CrOx and MnOxin slag are not only divalent oxides but also containing some higher valent of Cr3+ and Mn3+, respectively. In FeMn production conditions the slag consists mainlyMn2+. This is a clear difference from CrOx containing slags in which both two and three valent coexists in slags in FeCr process conditions. Oxidation state of the slag depends on the ambient oxygen partial pressure and temperature in the examined process. Thermodynamics of slags in ferroalloys production are discussed in terms of phase diagrams, activities and oxidation state of chromium and manganese oxides. Further, slag properties influencing reduction kinetics and furnace operation i.e. viscosity and electrical resistivity are discussed. Keywords: review, slags, ferroalloys, ferrochromium, ferromanganese, thermodynamics, physical properties.

Jan 1, 2004

By Xu H.

In recent years, the mineral applications dealing with more complex data in distributed environment have grown rapidly. Many mineral and mining organizations have to organize internally and globally distributed manufacturing and experiment sites, which share the roles of databases and other multi-services like software programs. Thus, there are commercial and technical pressures pushing the mineral software vendors to move their current service toward Web service. XML has gained wide acceptance for representing, storing and transferring structured data and documents of many kinds, especially in scientific communities. However, so far there is no such a Markup Language in mineral industry. A XML-based uniform encoding, which is called MineML(Mineral Markup Language), is proposed and developed in this project. The framework of the MineML specification is created. MineML will play the role as shared protocols within mineral domain for archiving, transferring the multi-nature data between the software packages on the desktop over the Internet and sharing the services between users at different sites. Inspired by MLA’s (Mineral Liberation Analyser, JKMRC, University of Queensland, Australia) Mineralogical Data Presentation Program, a proof-of-concept prototype of Web Service is developed here to validate and demonstrate the MineML specification. Certain strategies, specific technologies and tools are adopted to create such an environment. To accomplish that, a set of experimental MineML documents including correlated XML, XSD (schemas) and XSL(stylesheets) documents have been elaborated for archiving, presenting and transferring the mineralogical data information, with the persistence on flexibility and extensibility for generic mineral and mining data handling.

Jan 1, 2003

By A. Beitz, P. Smartt, G. Einicke, G. Rowan, P. Glynn

Coal is Australia’s highest export earner and Australia is the world’s largest exporter of coal. With coal now being extracted from deeper reserves under increased risk profile, and in the interest of aiding the stability of coal supplies, Japan is funding a number of safety projects in Australia and China. The CSIRO, Australia’s premiere research organisation with the country’s largest exploration and mining research group, are currently undertaking a jointly funded Japan-Australia safety project at Anglo Coal’s new Grasstree Colliery in central Queensland. The project, entitled Mine Communication and Information for Real-time Risk Analysis, will deliver step-change capabilities in data integration, decision support, gas monitoring, geo-technical monitoring, emergency response and personnel safety to the Grasstree Colliery. Some key activities include: developing and installing underground coal mine Ethernet LAN components, real-time monitoring of gas and geo-technical sensors, MODBUS serial to TCP/IP converters, e-reporting of underground conditions, emergency guidance systems and underground trials of Internet Protocol telephone and video. The project seeks to integrate (in real time) key data sets from the comprehensive and diversified range of propriety system currently in use at mines (ventilation, strata, operations e.g. haulage, pumps, conveyors etc) into a single integrated risk management interface. This interface will filter the data through a rules-based inference engine that will cross reference the various data streams, compare with past events and outcomes associated with the similar historical data and present this “intelligence” to

Jan 1, 2003

By S. E. Olsen, K. Tang

Slag-metal and slag-metal-gas heterogeneous equilibria involving MnO-containing slags have been simulated using recently developed Mn-based alloy and IRSID oxide thermochemical databases. A large number of experimental equilibrium data have been used to verify the calculation results. The experimental slag-metal and slag-metal-gas equilibria in MnO-SiO2binary, MnO-SiO2-CaO and MnO-SiO2-Al2O3ternary, MnO-SiO2-CaO-Al2O3quaternary andMnO-SiO2-CaO-Al2O3-MgO higher-order system can be reproduced within experimental uncertainties. The influence of temperature, CO partial pressure and slag chemistry on the Mn-and Si-distribution equilibria have been quantitatively evaluated. This leads to a sound basis for optimizing the manganese ferroalloy production processes. Key words: MnO-containing slag, manganese ferroalloy, equilibrium simulation, thermochemical database

Jan 1, 2004

By B. Unver

Effective strata control is a prerequisite for maintaining an efficient mining operation. If the strata in the vicinity of an opening are not controlled effectively, it is impossible to perform a safe, efficient and economical operation. In this paper, the reasons and outcome of instability problems observed in roadways opened in clay and marl at the Bolu Colliery of Yeni Çeltek Establishment are investigated. Roadways under examination were located in a syncline causing high residual tectonic stresses. Factors affecting the instability have been studied thoroughly by examining geology and tectonics of the area, establishing convergence measuring stations to understand in situ behaviour of supports and laboratory tests to determine engineering properties of samples taken from nearby convergence measurement stations. As a conclusion, a new production strategy and a new support system are recommended to maintain stability.

Jan 1, 1999

By O. I. Ostrovski, D. K. Belashchenko

The aim of this paper is the construction of models of systems with ionic and ionic-covalent bonds (molten salts) using experimental diffraction data and the calculation of their structure and thermodynamic and transport properties. Modelling was performed using algorithm BELION, in which the non-coulomb part of interaction potential between ions in the model was determined by the method of iterative simulation which targeted agreement between calculated and experimental partial pair correlation functions (PPCFs). The ionic charges in salts, which can be fractional, were determined by minimization of internal energy. In this paper, the algorithm BELION is applied for chlorides of alkaline-earth metals. Pair potentials, PPCFs, atomization energies, self-diffusion coefficients and electric conductivity are calculated. The charge of alkaline-earth metals was in the range of 2.0-2.1, slightly increasing from Mg to Ba. Partial pair correlation functions and atomization energies of models agree well with experimental data for MgCl2, SrCl2and BaCl2. Keywords: molten salt, molecular dynamics, partial pair correlation function, ionic charge, atomization energy, diffusion.

Jan 1, 2004

By Dave Capstick, Ken Garner, Jim Porter

Technologies and systems used in the management of energy consumption in the mining and metal processing industry are well understood and documented from the supply side of the business. It is our contention that in many instances, through a more complete understanding of the demand side of the business, based on the detail of the operations plan, will provide greater lead time in terms of the design, implementation and utilisation of power supply infrastructure. Thus, optimal management of demand in a proactive manner, based on production requirements, will ensure both security of supply as well as continuity of operations. This paper describes the technology and methodology that is being developed to enable the above statement to be achieved. We use a case study to demonstrate the ability of the tools and methodology and conclude by outlining the business benefits achievable as well as the future developments emanating from this initiative.

Jan 1, 2005

By K. C. Mills, R. Thackray

A test has been devised that can predict accurately the % crystallinity developed in a slag film formed between the steel strand and the mould. The % crystallinity in the test samples was determined and compared with that for slag films formed in the mould when casting with that flux. There was good agreement between the % crystallinity in the test samples and the slag films. It was found that additions of TiO2and ZrO2had little effect on the amount of crystalline phase formed, but additions of CaO caused a dramatic increase in the amount of crystalline phase formed. Various parameters (which can be calculated from chemical composition of the flux) have been plotted against % crystallinty in the test samples. It was found that the modified (NBO/T) ratio provided the best relation with % crystallinity for the various parameters tested. There commended relation is % crystallinity=141.1(NBO/T)-284.0. Keywords: continuous casting, mould flux, slag film, crystallinity, chemical composition

Jan 1, 2004

By M. A. W. Bryson

It is well documented that a significant amount of the new PGM (Platinum Group Minerals) production that is coming on stream now, and over the next few years, is to come from the UG-2 reef. Clearly the reservations, or perhaps the perceived reservations, attached to the processing of this ore are no longer there. What were the metallurgical issues that delayed the exploitation of the PGM values from this reef? Traditional furnaces treating Merensky concentrates were not able to accept the concentrate produced from a UG-2 plant due to the relatively high chromite content of this product. The chromite reports to an insoluble spinel phase that accretes in the furnace, resulting in the necessity to shutdown and dig the furnace out periodically. This was clearly not an attractive economic option, so producers stayed away from it in the early days. The Merensky ore had all higher base metal credits anyway, and you needed them to get a matte fall, so there was no driving force to look seriously at the UG-2 reef. Platinum demand at this time could be easily met from the Merensky ore, so the motivation to tackle more complex ores was not there. The low price of PGMs meant that these operations were not particularly profitable and there was little effort directed at improving the operations. Concentrators were generally not run very efficiently and the emphasis was on cost reduction through increasing milling rates.

Jan 1, 2004

By D. R. Hack, N. M. Sirakov, M. L. Feves, M. Iwanowski

This paper presents a new approach capable of volume calculation of 3D reconstructed geological objects. The method is based on a well-known concept that states the volume of an object can be computed as the limit of the sum of the area of infinite number of sections, which cut the 3Dobject. Since shortage of input data about the geological objects usually exists, Mathematical Morphology and polynomial interpolation are employed to generate a set of intermediate sections between the set of initial sections. A Mathematical Morphology tool is applied to compute the area of the two of sets initial and generated 2D sections. Regularities together with Delaunay Triangulation are employed to perform 3D reconstruction. A formula is developed on purpose of volume calculation of the reconstructed objects. A set of ten theoretical, electrical resistivity cross-sections were generated and used to perform an experiment to show the capability of our approach to estimate the volume of complex 3D geological object in case of sparse 2D sections. The volume determined using the morphological approach presented in this paper show good correlation with the volume of the original input object. Advantages and disadvantages of our volume calculation approach are discussed in the conclusion of this paper. Keywords: electrical resistivity, sparse 2D sections, geological objects, smooth 3D visualization and volume calculation.

Jan 1, 2003

By K. -H. Lux, Z. Hou

ABSTRACT: It is well known in underground mining and waste disposal that the development of excavation damaged zones (EDZ), and thus, hydraulic pathways, is closely related to the excess in the corresponding damage boundary (= long-term strength) of the rock mass and the resulting damage. By integrating short-term and long-term strength, dilatancy, damage and healing into the newly extended Hou/Lux constitutive model for rock salt, it is possible to treat the tertiary creep, to identify the EDZ around underground facilities and to predict the time-dependent development of the EDZ in rock salt. Under in-situ conditions, the EDZ of a 37-year-old drift at the Sondershausen salt mine and the EDZ around a drift dam in rock salt are numerically examined. The numerical analysis gives satisfactory results. RÉSUMÉ: Dans les exploitations minières et le stockage souterrain des déchets, le développement des zones endommagées et fracturées (EDZ – excavation damaged zone), créant des chemins préférentiels pour écoulement, est étroitement lié au contexte géotechnique et à la méthode d’excavation. En intégrant la résistance court et long terme, la dilatance, l’endommagement et le colmatage, le nouveau modèle rhéologique Hou/Lux pour le sel gemme est capable de traiter le fluage tertiaire, d’évaluer l’extension de l’EDZ et de prédire l’évolution de EDZ dans temps autour des ouvrages creusés dans le sel gemme. L’EDZ d’une galerie datée de 37 ans dans la mine de sel de Sondershausen et les EDZ autour de barrage des galeries dans un sel gemme ont été modélisées. Les résultats numériques fournissent des résultats satisfaisants. ZUSAMENFASSUNG: Bekanntlich ist die Entstehung von Auflockerungszonen und damit hydraulischen Wegsamkeiten in der unmittelbaren Umgebung um bergmännische Hohlräume mit der Überschreitung der entsprechenden Schädigungsgrenze eng verbunden. Unter Berücksichtigung der Bruchfestigkeit, Schädigungsgrenze, Dilatanz, Schädigung und Verheilung kann das Stoffmodell Hou/Lux das Verhalten des tertiären Kriechens beschreiben, die Auflockerungszone im Salzgebirge ermitteln und ihre zeitabhängige Ausdehnung vorausberechnen. Mit diesem Stoffmodell werden die Auflockerungszonen einer 37jährigen Strecke in der Salzgrube Sondershausen und die Auflockerungszonen um ein exemplarisches Abdichtungsbauwerk im Salzgebirge numerisch untersucht. Dabei werden zufriedenstellende Berechnungsergebnisse erzielt.

Jan 1, 2003

By L. K. Smith

The position of Australia as a continuing long-term supplier of mineral sands, and their upgraded products, has been reinforced with the discovery of the extensive mineral reserves in the Murray Basin, an area covering parts of South Australia, New South Wales and Victoria. A major impurity in the Murray Basin is chromium, mainly present in ilmenite concentrates as individual chrome spinel grains. Magnetizing roast treatments are being evaluated as a means of removing the chrome spinel impurity from the ilmenite and as a result of the roast and magnetic separation treatments, the chrome spinels can be expected to be concentrated in the non-magnetic reject fractions. It is from these fractions that attempts were made in this study to recover a chromium-rich product by magnetic fractionation and by application of flotation. The high gauss non-magnetic rejects from the roasting of a primary and a secondary ilmenite fraction were magnetically fractionated to obtain a product with 40.5 and 28.7 per cent Cr2O3,respectively. From the high gauss non-magnetic reject from the roasting of a primary ilmenite, flotation produced a chromium-rich product assaying 29.5 wt per cent Cr2O3at 69.0 per cent recovery. In another test a magnetic fraction assaying 32.9 wt per cent Cr2O3was floated to yield a chromium-rich product with 39.7 wt per cent Cr2O3at 96.4 per cent recovery. X-ray diffraction patterns of all the products indicated that the spinel concentrated was a ferroan magnesiochromite with rutile, ilmenite and hematite as impurities. Since all products were from a single pass, further processing can be expected to remove the impurity minerals and yield higher grade products. The material produced from the Murray Basin ilmenites in this study had similar compositions to commercial chromite ores, except for titania levels that were much higher. The high titania levels were due to residual rutile in the products, but it is expected that this can be removed with further processing. The mineral sand deposits in the Murray Basin are scattered over a wide area and the amount of chromite that may be produced from each of these deposits is unlikely to be sufficient to support an export market. Consequently, any chromite produced in the Murray Basin will most likely need to be processed locally to value added products for a niche market such as chemicals production. Keywords: Murray Basin, ilmenite, chrome spinel, roasting, magnetic separation, chromite ore

Jan 1, 2003

By Marko Lampi, Marc Nicolle, Janne Karonen, Kari Valkama

"In the ten years from 2003 to 2013 global mine production of copper has increased by over 23% to meet demand while the weighted average head grade has dropped from 0.9 to 0.7% Cu. These divergent trends of increasing demand and declining economic grades will extend the life of many existing mines and improve the viability of marginal and/or complex copper deposits. Against that context this paper outlines hydrometallurgical copper sulphide leaching options as alternatives to the more conventional pyrometallurgical processing route of copper sulphides. Three copper sulphide leaching and refining processes are discussed: total pressure oxidation, ferric sulphate leaching and copper chloride leaching. The effect of mineralogy on the choice of processing technology is discussed as well as some of the unit processes used. Additionally, possible benefits that a hydrometallurgical process may offer over an existing pyrometallurgical route are discussed. Subsequently, two very important aspects to the development of projects involving the leaching of copper sulphides are discussed. Finally, a number of conclusions are presented that will be useful to keep in mind when considering projects involving the leaching of copper sulphides. INTRODUCTION In the ten years from 2003 to 2013 global mine production of copper has increased by over 23% to meet demand while the weighted average head grade has dropped from 0.9 to 0.73% Cu (Murphy, 2014). If these divergent trends of increasing demand and declining economic grades continue, they will contribute to the extension in life of many existing mines and improve the viability of marginal and/or complex copper deposits. Against that context, this paper outlines hydrometallurgical copper sulphide leaching options as alternatives to the more conventional pyrometallurgical processing route for copper sulphides. Three copper sulphide leaching and refining processes are discussed: total pressure oxidation, ferric sulphate leaching and copper chloride leaching. Ferric sulphate leaching and copper chloride leaching are carried out at atmospheric pressure while total pressure oxidation takes place at elevated pressures."

Jan 1, 2015

By L. Andrews

Nickel is recovered as a by-product of the platinum-producing process operated by Anglo Platinum. The metal is mined mainly as sulphide minerals contained in platinum ores. These pass through the concentrating, smelting and converting process route and nickel is finally recovered by electrowinning. Smelting of the concentrated ore in the electric furnace produces a melt with a high slag to matte ratio. The resulting furnace slag is granulated and later milled and floated to recover matte. A project was initiated to investigate the distribution of nickel in the slag in order to improve recovery. Slag samples were examined using a combination of chemical and mineralogical techniques. The granulated slag was found to consist mainly of a silicate glass phase, which reflects the composition of the molten slag in the furnace. Nickel occurs as free matte granules, as matte phases locked inside the glass, and in the glass phase itself. Whereas nickel in the matte is as sulphide, most of the nickel in the glass phase appears to be oxide- bound(i.e. in solid solution). Milled slag as flotation feed showed recovery-limiting features such as free matte with oxidized surfaces and unliberated matte inclusions in the slag. The biggest nickel losses, assuming no tapping problems, are in the glass phase solid solution. Only around 40% of nickel would be recovered from the slag, even under ideal conditions. Spoon and pot slag samples were also examined to see if casting and crushing would improve recovery. Although larger and therefore more easily recovered matte phases formed, nickel partitioned into crystalline silicate phases, limiting the maximum theoretical nickel recovery to 70%.

Jan 1, 2004

By J. Nell

An overview is given of the matte melting process used for the beneficiation of South African Platinum Group Metal (PGM) ores. Most producers use six-electrode furnaces to melt the concentrate and Pierce Smith converters to oxidize excess iron sulphide from the furnace matte. Concentrates from two reef-types (the so-called Merensky and UG-2 reefs) dominate the feedstock supply. Concentrate from the Merensky reef is low in chromium and do not pose significant melting problems. Concentrates from the UG-2 reef contain much higher levels of chromium, which results in the formation of chromium-rich spinels during melting. This is attributed to the low solubility of chromium in furnace slag under typical operating conditions (an oxygen partial pressure of 10-8-10-9bar at temperatures of 1550°C to 1600°C). During the converting process care is needed to avoid excessively oxidizing conditions, which result in cobalt, nickel and copper losses to the slag. High nickel losses result in the formation ofFe2NiO4(trevorite), which often forms solid solutions with FeCr2O4and Fe3O4. In future, the main challenge in the processing of South African PGM ores will be to cope with ever increasing levels of chromium in the concentrate. A short-term solution to the problem would be to melt the concentrate under slightly reducing conditions to promote the formation of CrO, which is more soluble in the slag than Cr2O3. A longer-term solution to the problem would be to abandon the current matte-smelting process in favour of an alloy-based process, which would offer total flexibility with respect to the amount of chromium that can be tolerated in the feed. Key words: Merensky, UG-2, furnace, slag, matte, converting, spinel, chromium.

Jan 1, 2004

By Y. Nakata, K. Nagata

Plasma is partially ionized gas composed of ions, electrons and activated elements at high temperature. Some flying ash from incinerated municipal waste is melted to become glass by a transfer-type arc plasma furnace. As the glass is ionic silicate, when an electric current passes through anode to cathode, ions in molten slag electrochemically react with electron in plasma at the surface of molten slag. In case of molten Na2O-SiO2, sodium ions in the molten slag carry electric current and SiO2are reduced to evaporate as SiO gas by electron in plasma. The cases of Ag+in NaNO3-KNO3molten salt and Fe2+in FeO-SiO2slag were examined. The amount of cathodic reaction is larger than that of anodic reaction and not apparently according to the Faraday?s law on the electrochemical reactions.

Jan 1, 2004