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By John Wilson

"The Rietveld numerical method was used to calculate the relative abundances of phases in both synthetic binary mixtures and synthetic and natural ores, using X-ray diffraction data. The results were compared with those of image analysis and a chemical method. The ranges of the relative errors were estimated. The Rietveld method is found to be acceptable for determining the abundances of major and minor phases and the amorphous component of partially crystalline samples. In complex mixtures, where there are several trace phases (~<2 wt%) present, the technique becomes less accurate. It is most useful as an alternative technique to image analysis when sample preparation is problematic or sample particle sizes are sub-micron. It is a manual method which requires user input during the fitting process, but is both simpler and faster than image analysis due to the reduced set up time and sample preparation required. It is now implemented at CANMET as a technique for quantitative analysis.INTRODUCTIONUntil recently, the Applied Mineralogy group at CANMET used only image analysis and chemical techniques to determine phase quantities. An effort to develop quantitative X-ray diffraction (XRD) has been on-going for several years. Initially, the reference intensity ratio (RIR) method with external standards was tried with some success (Szymanski and Petruk, 1989). The main difficulty with this technique was finding adequate standard material for each phase present in the sample. This shortcoming made the method ultimately impractical, given the wide variety of materials which come to the laboratory for analysis.The Rietveld refinement method of quantitative XRD (Hill et al 1993, Mumme et al 1996), in contrast, requires no standards and requires minimal sample preparation and therefore a more rapid turnaround compared to image analysis. The Rietveld method also has advantages over image analysis in that it can identify and quantify polymorphs, ultra fine materials and many types of hydroxide products. As well, it is useful for analyzing materials such as bauxite or talc, which do not polish well enough for making mounts of the quality required for image analysis. To quantify amorphous material and phases which are present in amounts below the detection limit of XRD, the addition of a standard material is still required. However, in such cases only one standard is needed, which is alumina."

Jan 1, 2003

By M. Sturzenegger

This paper documents a field survey using long-range terrestrial digital photogrammetry at the Palabora open-pit mine, South Africa, for multi-scale characterization of rock mass discontinuities. Stereomodels covering the entire mine were generated based on photographs taken from a distance of 1600m across the pit, using a series of f=20-400mm lenses. Details on the methodology used and its accuracy are discussed. Preliminary results on discontinuity orientation, persistence and intensity are presented, highlighting the effect of observation scale. The potential uses of long-range terrestrial digital photogrammetry in open-pit mine and large natural rock slope environments is emphasized. The use of an f=400mm lens from distances larger than 1.5km may represent an important step forward in the geotechnical characterization of inaccessible remote rock faces.

May 1, 2009

By M. Tarvainen, J. Kallioinen

"Depressed metal prices coupled with increasing production costs have presented a great challenge for operators to control and reduce the costs of production to maintain profitability. Depleting ore reserves, added to the above has forced Outokumpu to take a hard look at its operations, to develop new methods to profitably extend the life of its mines. One of the areas investigated and approved for further development has been the use of larger and more energy efficient equipment. As a result, large flotation machines were developed and today 38 and 60m3 flotation machines are in use.Secondly, ore preconcentration has been developed to avoid processing the part of the ore that has little or no mineral values.Another quite recent development and the topic of this paper, has been the use of coarse flotation before conventional flotation. The main idea is that part of the valuable mineral is separated as early as practical by floating it with specially designed flotation equipment, installed in the grinding classification circuit. The new flotation cell is specially designed for this application and differs from the conventional cells in the tank design, feed arrangement and modified mechanisms in some cases."

Jan 1, 1984

By K. A. Lewandowski

Leach heaps are plagued with problems due to fine material migrating downwards, clogging the spaces between the coarser ore particles, resulting in decreased metal recovery rates. The use of a binder in agglomeration would allow the fine material to be immobilized, increasing the availability for the solution to come in contact with all the ore. As much as 1.64*1012 BTU per year would be able to be saved if a 25% increase in copper recovery was experienced, assuming that 70% of heap leaching units converted to using agglomeration technology. This is equivalent to approximately 18% of the energy currently being used in leaching heaps.

Jan 1, 2008

By Peter Claus

In the last years, supported gold catalysts with particle sizes smaller than 10 nm have attracted a lot of attention. While gold bulk metal is rather inert in chemical reactions and, thus, is of low interest for catalysis, highly dispersed gold particles supported on oxides as TiO2 or ZrO2 show surprisingly high activities in some reactions important for the chemical industry. The oxidation of carbon monoxide at low temperatures is mainly used as model reaction to study the unusual properties of gold catalysts [1]. On the other hand, to evaluate the catalytic potential of gold, other chemical reactions which allow to control also the selectivity have to be considered. The selective hydrogenation of ???-unsaturated aldehydes to allylic alcohols is of both commercial relevance (e.g. in fine chemical and pharmaceutical intermediate production) and specific scientific interest [2]. Note that thermodynamics favors hydrogenation of the C=C over the C=O group (stronger negative free reaction enthalpy of 35 kJ/mol), and for kinetic reasons the C=C bond is more reactive than the C=O group. Thus, in the presence of most of the conventional hydrogenation catalysts, based on Pt, Rh or Pd, -unsaturated aldehydes such as acrolein and crotonaldehyde are hydrogenated predominantly to the saturated aldehydes and only to a minor extent to unsaturated alcohols. Therefore, it is desirable to find catalysts which are able to control the intramolecular selectivity by hydrogenation preferentially the C=O group while keeping the olefinic double bond intact (Fig. 1).

Oct 1, 2003

By Gerasimenko MP

The authors consider the features and advantages of a new promising trend in mineral processing - column flotation. Design aerohydrodynamic and process characteristics of pilot-scale columns are studied. Optimum process parameters for various ores and operations are studied. Flow patterns in cells of various cross-sections are investigated and the relationship between Peclet criterion and specific capacity of cell is determined. On this basis options were developed for optimisation of hydrodynamic characteristics of large capacity cells, including longitudinal sectionalising of the collection zone. It is shown that advantages of high column cells (10 - 13 m) produced in the West can be implemented in a sectionalised machine of smaller height (5 - 6 m). Investigations on the influence of slurry and air bubbles flow patterns indicated that to increase flotation rate of particles of various flotabilities it is expedient to combine co- and counter-current flows of phases in a single column. The proposed designs allow tailings to repeatedly return tailings to the collection zone and alternate co- and counter-current slurry and air flows. For the first time columns with alternating slurry flows (combination of co- and counter-current flows) are developed and commercialised. Unique multi-sectional cells having a number of essential advantages compared to monocells are developed. Design features of the cell allow: implementation of different flotation process flowsheets in a single unit, improved beneficiation process results, reduced specific power requirement, and elimination of sludging of the aerator and cell bottom part. Operational problems restricting introduction of column cells are connected with the aeration unit. The new cells are supplied with pneumohydraulic and stepped airlift spargers, allowing control of bubble size distribution with a service life of not less than three years. Successful operation of the new generation of columns with cell volumes of 15, 25, 40, and 80 cu m and the height of 5 - 6 m in copper, molybdenum, antimony, tungsten and nickel ores and coal slurry processing at different plants in this country illustrated their considerable process and operational advantages and verified the proposed options and relationships. A simulation technique of the flotation process and models for the solution of various problems are developed. A modular model of column flotation is constructed taking into account the kinetic relationship of the process and the hydrodynamic regime in the cell. Based on this, a technique of calculating the column parameters based on laboratory tests is developed (scaling-up), and applied for calculating the design of commercial-scale columns is developed.

Jan 1, 1993

By Theo. A. M. Salet

The historic centre of one of the most beautiful cities in Northern Europe -Amsterdam - is being excavated to accommodate the new North/South metro line. This new line is due for completion in 2012, and will link the Buikslotermeerplein district north of the harbour, underneath the Central Station and the old city with its gables and picturesque canals, to the commercial centre in Amsterdam Zuid/WTC. Three underground stations are being construction in the old city at Rokin, Vijzelgracht and Ceintuurbaan. The logistics of working in the middle of an historic city are demanding -maintaining tram, vehicular traffic and pedestrian access along narrow streets, providing suitable protection for the public alongside the working areas, arranging adequate delivery routes, as well as monitoring the old and mostly historical buildings for potential settlement. Safety of both the public and adjacent properties is paramount. Diaphragm walling - 1.2m & 1.5m thick and up to 48m deep - was chosen as the support system for the three deep metro stations. Challenging engineering as well as state-of-the-art equipment to construct the diaphragm walls was needed in order to meet the tight working specifications, in the narrowest locations imaginable. Extreme conditions call for innovative solutions.

Jan 1, 2006

By L Forrester

The tube bundle system is an integral part of an underground coalmine’s gas monitoring system. The maintenance of these systems is vital to ensure the quality of the data produced. Integrity testing of the tube bundle lines is required monthly, as specified in Standards Australia AS/NZ 2290.3 (1990). The various forms of integrity testing are reviewed, including pressure testing and introduction of a known gas. This paper provides a recommended and standardised methodology for those techniques where none currently exists. A strengths, weaknesses, opportunities, threats (SWOT) analysis is performed. The parameters considered for the SWOT analysis include resourcing required by the mines, time for the testing to be performed, and quality of the results produced. The suitability of such integrity testing protocols to be used in a mine emergency situation is also evaluated.CITATION:Forrester, L, 2017. Tube bundle integrity testing methodologies, in Proceedings Australian Mine Vent Conference 2017, pp 129–136 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Olaf Andersen

Crucible melt extraction yields short metal fibers with eqivalent diameters as low as 50 µm from almost arbitrary metals and alloys. Highly porous components can be made from such fibers by suitable deposition and sintering methods. This technology is being developed at the Dresden based Department of Powder Metallurgy and Composite Materials of the Fraunhofer Institute for Manufacturing and Advanced Materials (IFAM) and has been applied to gold alloys and iron-base alloys containing small additions of precious metals. From the manufactured gold fibers, sintered structures were made for decorative applications. Additionally, it was found that due to rapid solidification during the fiber formation, precious metals can be finely dispersed in ironchromium- aluminum (FeCrAl) and FeAl20 alloys. Good catalytic activity at elevated temperatures was found in compositions containing 3 wt.-% Ce and 0.5 wt.-% Pt.

Oct 1, 2003

By P. Gonzalez, C. Ariyo, L. Holappa

Oxidation state of titanium was determined in CaO-SiO2-TiOxslags in the composition range25–53 per cent CaO, 27–46 per cent SiO2, 10–55 per cent TiOxat 1873K using gas equilibration method. In the experiments, slags with different titanium oxide contents were equilibrated with a known carbon monoxide and carbon dioxide ratio. The results were used to determine the Ti3+and Ti4+contents as well as the activity coefficient ratio of corresponding oxides in the slag. The dependency of the activity coefficient ratio as a function of oxygen partial pressure was determined. Keywords: titanium, titanium oxide, activity, activity coefficient, slag iron, carbon monoxide,carbon doixide, gas, equilibrium.

Jan 1, 2004

Suddenly, mining has been thrust into the limelight. It has a large image that casts its shadow over New Zealand. Is it any wonder that resistance has heightened and that an almost unprepared populous is currently struggling to protect the very land they hold dear. Next to the atomic bomb, mining has the demonstrated power to massively change the land and its side effects can pollute many miles beyond the operation. During the past year, New Zealand concern over the possible effects of the mining proposals has become acute. This was specially so in the areas of special environmental quality, such as the Coromandel, and here a very unhappy situation has arisen.

Jan 1, 1981

Validation of the JKMRC Rotary Breakage Tester (JKRBT) Ore Breakage Characterisation Device

Sep 13, 2010

By Andrew M. Leszcykowski

In 1984, personnel from the U.S. Bureau of Mines examined 41,550 acres of the North Fork Owyhee River Wilderness Study Area for mineral resources. This study area, in southwestern Idaho, is underlain by tuffs and basalt of Tertiary age. There are no known mines, claims, or prospects in or near the area. The northeast and southwest corners of the area are covered by oil and gas leases or lease applications, but no known exploration has been conducted. On Nickel Creek and Pleasant Valley Tables, in the southern part of the area, thin flows of vesicular, moss-covered basalt occur that are suitable for use as decorative building stone. The stone available for exploitation crops out over several square miles. However, more suitable material, outside the study area, is closer to potential markets.

Jan 1, 1986

By Gary B. Petersen

The author has developed a seven-step process called the Applied Rock Mechanics (ARM) Protocol that the author has used to solve numerous roof stability problems in mines throughout North America since 1975. It is a practical evaluation process using trained observation, innovative data collection instrumentation, video borehole cameras, analytical processes, and controlled testing methods that have become highly effective in solving ground control problems in every type of underground mine. This paper will describe each of the steps of the protocol and how the rock mechanics engineer applies them to resolve a typical ground control problem.

Jan 1, 2012

By W Shamu

The mechanical properties of rock samples of identical lithologicalcomposition may vary significantly due to existence of materialdiscontinuities. Laboratory tests were carried out to determine the effect of material discontinuities on rock sample mechanical properties. The investigations consisted of detecting discontinuities, observing the failure mechanisms during uniaxial compressive strength tests, and analysing of the factors affecting the strength. A non-destructive testing method has been adopted to assist in thedetection of discontinuities. Laboratory testing proved that fractures leading to failures initiated on the detected discontinuities. The location, orientation, size, density and extent of the discontinuities contribute to different modes of failure and these affect the mechanical parameters of rock samples. Four modes of failure were distinguished for hard and brittlecylindrical rock samples. These modes were referred to as simple shear failure, multiple shear failure, multiple fracturing and vertical splitting. To evaluate the effect of discontinuities on mechanical parameters, the ratio of uniaxial compressive to tensile (Brazilian) strength was calculated and analysed for the different modes of failure. It was found that the value of the ratio depended on the mode of sample failure. The lowest value of the ratio was observed for shear mode of failure and the highest for vertical splitting mode of failure.

Jan 1, 1999

By P Grieve, J L. Mauk

The Central Maratoto Valley in the Coromandel Peninsula contains a sequence of veins in pervasively altered dacite + andesites of the Waipupu Formation. We recognise at least eight different vein types: (1) pyrite stringers, (2) quartz + carbonate veins, (3) crystalline quartz veins, (4) carbonate veins, (5) chlorite + carbonate veins, (6) siderite veinlets, (7) siderite + carbonate veins and (8) carbonate + pyrite veins. The overall temporal trend of the veins is from early pyrite to quartz and then to late carbonate veins. Carbonate veins and pyrite stringers both form planar and irregular veins, whereas some carbonate veins have diffuse contacts with the wall rock. Gold and base metal sulphides are associated with some of the quartz + carbonate veins. Textures within the veins reflect open space filling and multi-phase reopening. A partial record of hydrothermal activity has been preserved by vein crosscutting relationships, hydrothermal alteration minerals and fluid inclusions. Hydrothermal alteration minerals display zonation from south to north. The alteration increases from unaltered to weak propylitic alteration of andesite in the south (MVRCDC1), to sericitic alteration of andesite and dacite in the north (MVRCDC3). The alteration assemblage is dominantly sericitic, with no adularia present, drawing parallels to the Thames region where there is no adularia.

Jan 1, 1999

Despite the wealth of information available on phase equilibria of oxide systems there remainmany gaps and inconsistencies in our knowledge base. From an industry perspective there is anongoing need to adequately describe the phase chemistry of slag systems in order to optimizeprocess performance and improve productivity. Since this chemical behaviour cannot be predictedfrom first principles it follows there is also an ongoing need for accurate experimental data. The advances made in recent years in the capabilities of sophisticated analytical and measurement equipment have made it possible to develop new experimental techniques for the direct determination of phase equilibria in low order and complex multi-component slag systems. In addition the development of powerful computer modelling tools makes it possible to provide more comprehensive descriptions of the phase chemistry, to present the information in a range of perspectives, and to critically analyse the various types of related thermodynamic and structural information available. This review provides an overview of the types of information that can be used to determine phase equilibria in slags systems, analyses the influence of uncertainty and the relative importance of these types of data, and describes the advantages and limitations of the various experimental techniques that can be employed to obtain this information. Examples of recent studies are provided that demonstrate how an integrated approach to the determination of phase equilibria in complex systems, involving the use of targeted experimental studies and systematic thermodynamic model development, can lead to a better utilization of our current research capabilities and resources and more accurate descriptions of these systems. Keywords: slags, phase equilibria, experimental techniques

Jan 1, 2004

By F H. S dosSantos, R L. C Santos

The main objective of this work was to develop, at a laboratory scale, a process for treating residues from the settling stage of water treatment so as to remove and recover the aluminium as sulphate. The chemical analysis of residues from different water treatment plants indicated that the aluminium content varied from 15 to 20 per cent w/w. By using the appropriate experimental conditions, it was found to be possible to leach most of the aluminium content. The pH value of the recovered water was suitable for it to be recycled to the water treatment process and the residue appears to be suitable as raw material for bricks. The process developed contributes to the sustainability of the water treatment process.

Jan 1, 2002

By M Rattenbur, A B. Christie, S C. Cox

A new minerals initiative to increase the level of understanding of New Zealand&apos;s mineral resources and to promote the development of minerals began earlier in the year in a partnership pilot-project between Crown Minerals and the Institute for Geological and Nuclear Sciences (GNS). The project aims to gather a set of comprehensive geoscientific data and build a series of digital GIS packages to highlight New Zealand&apos;s mineral prospectivity. The pilot study was carried out at a regional scale, and is focussed on mesothermal gold mineralisation in the South Island. A significant amount of geological data and information was sourced from open file technical reports held by Crown Minerals and from various databases held by GNS and has now been compiled into a single GIS dataset, which will soon be made freely available to interested parties. In addition to this comprehensive data compilation, prospectivity modelling using Weights of Evidence techniques was undertaken to highlight those areas likely to contain ore deposits. It is clear from this study that the South Island of New Zealand remains highly prospective for mesothermal gold mineralisation. Many of the highly prospective areas, which also contain historic mine workings, remain open for exploration. The study not only highlights these areas, but also other areas where the potential for similar mineralisation exists, in all likelihood with no surface expression. The study has also highlighted the value of many of the open-file technical reports held by Crown Minerals and the need to carry out additional studies using this and other available data at a more detailed level, possibly as the basis for a web-based minerals information system.

Jan 1, 2002

By Randall S. Marks

Bonneville Dam, completed in 1938, included the smallest and busiest lock on the Columbia and Snake River Navigation System. To expedite barge traffic through this restriction, a new larger lock was designed and contracted by the U.S. Army Corp of Engineers.

Jan 1, 1997