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By J. S. Preston

The properties of some recently developed solvent-extraction reagents for the separation of cobalt and nickel sulphate solutions are reported. New commercial extractants based on alkyl phosphonic and alkyl phosphinic acids are described. These reagents show much improved selectivity for cobalt compared with established extractants. Some novel extractants developed at Mintek for the selective recovery of nickel in the presence of cobalt are also described. These reagents, which are based on mixtures of carboxylic acids and non-chelating oximes, are of interest in that no commercial nickel-selective reagents are currently available. Graphs showing metal loading and stripping, and pH-functionality, are presented. together with details of the metal separations achieved in batch countercurrent- extraction experiments with the various reagents.

Jan 1, 1983

By J. A. Cruise

With the end of the official apartheid legislation in the early 1990s, South Africa was heralded as a non-racial country. However, racial awareness has been reintroduced into the country with the Affirmative Action and Black Economic Empowerment legislation. Gender and racial transformation are the current order of the day. All organizations are required to reflect in their make-up the demographics of the population as soon as possible. Scorecard shave been drawn up to measure the rate of transformation for gender and race in organizations. The mining industry in South Africa has been in the forefront of this transformation legislation and scorecards. This paper seeks to show the effect of gender and racial transformation on mining engineering education and professionalism by analysing the changing demographics of graduating mining students at both the South African universities offering a degree in mining engineering, the professional registration of mining engineers with the Engineering Council of South Africa (ECSA), and the membership of the Southern African Institute of Mining and Metallurgy (SAIMM), the vocational institute for mining engineers. It also demonstrates the absurdity of gender and racial quotas based solely on the demographics of the current population of the country. This paper shows the degree to which mining engineering has transformed in both gender and race.

Jan 1, 2011

By W. J. Atkinson, E. M. Anderson

FOREWORD This paper is based on the authors' experience gained in the environmental assessment of major uranium projects in the former Department of Science and the Environment and Department of Home Affairs and Environment of the Australian Government. The authors gratefully acknowledge assistance received from colleagues within the Department of Home Affairs and Environment in the preparation of this paper. Special thanks go to Mr K.E. Thompson of the Department's Environment Division for his valuable comments and criticism. The views expressed in the paper are those of the authors alone and not the Australian Government or Dames & Moore. INTRODUCTION Uranium has been mined in Australia since 1954. A number of small scale mining and milling operations were active in the Northern Territory, in South Australia and in Queensland in the late fifties and early sixties. However, in the late sixties there was an increase in exploration activities in the expectation of an upsurge in world demand for uranium Substantial new resources were delineated in the Northern Territory, Queensland, South Australia and Western Australia. The most significant deposits were located in the Northern Territory, in what is called the Alligator Rivers Region located approximately 200 km east of Darwin. The Region is in the latitude of 13° South and thus lies within the Australian tropics (Figure 1). It consists of approximately 2.3 million hectares of natural wilderness containing much spectacular and attractive scenery. The area is noted for its abundant wildlife, particularly the waterbirds that gather on the flood-plains. Much of the vegetation is diverse and interesting. The Aboriginal population still maintains elements of the traditional way of life, and the spectacular Arnhem Land escarpment contains many of the best surviving examples of Aboriginal rock art. Numerous rich archaeological sites provide evidence of continuous human habitation for tens of thousands of years. Climatically, the Region is of the tropical monsoon type with a dry season from may to September and a "wet" from November to March. High intensity short period rainfall is characteristic, and the average annual precipitation is in the order of 1 350 mm. The monthly mean temperature ranges from 25° to 30°C throughout the year. The development of regulatory controls on uranium mining in the Alligator Rivers Region has been affected by the political status of the Northern Territory. While Australia is a federation, established as an independent self-governing country in 1901, it was not until 1978 that the Northern Territory became to any real extent self-governing. Prior to 1978, the Territory was administered through a special department of the Commonwealth (ie. the Federal Government). Under the Northern Territory (Self Government) Act 1978, administrative powers similar to those possessed by the Governments of the six founding Australian states were provided to the Territory Government. However, the Commonwealth government did not transfer to the Territory all such powers and functions, and in particular there has been, since 1978, a dual role for the Commonwealth and Territory Governments in the regulation of uranium development. Details of this role are provided later in this paper. RANGER URANIUM INQUIRY By 1973, major deposits had been discovered in the Alligator Rivers Region at Nabarlek, Ranger, Koongarra and Jabiluka. The estimated reserves and mine life expectancy of these deposits are given in Table I. Other radioactive anomalies have also been identified in the area but, as yet, they have not been delineated or evaluated. [ ] In 1974, an agreement was signed between the Commonwealth Government and Peko Mines Limited and the Electrolytic Zinc Company of Australia Limited for the joint development of the Ranger deposit. In July 1975, the Government announced a Commission of Inquiry under the provisions of the Commonwealth Environment Protection (Impact of Proposals) Act 1974, into the proposed Ranger development. The inquiry was known as the Ranger Uranium Environmental Inquiry or more commonly, the Fox Inquiry after the presiding Commissioner, Mr Justice Fox.

Jan 1, 1981

By Toshiharu Hayashi

We prepared the water dispersed with Au particles ranging from 10 to 20 nm size by a novel wet chemical synthesis; generating seeds of Au cluster by adding a borane dimethylamine complex into chloroaureic acid (gold salt) solution, and then growing simultaneously with aminoalcohol included in the solution. As-prepared Au nano-particles with chemical surface modification were found to have some attractive performances, i.e., showing a high dispersiveness in an aqueous solution in a long time, sintering nano-particles at low temperature, and having low resistivity in the film prepared from nano-particles. In the case that smaller Au nano-particles were removed from as-prepared colloid, especially, Au thin film formed on the surface of Si plate showed the excellent value of 7.0x10-6ohm cm (reference peculiar resistance: 2.35x10-6 ohm cm).The sintering temperature was dependent on the elimination of 2-aminoethanol that modified on the surface of Au nano-particles.

Jan 1, 2006

By Robert W. Hendricks, John B. Newkirk

A simple method is described for determining the orientation of a single crystal by means of a cylindr cal X-ray camera. Orientation setting to within ±1 deg is attainable by a stereographic analysis of a single cylindrical Laue pattern produced by the originally randomly mounted crystal. Final precision adjustments which permit orientation of the crystal to within ±5 min of arc from the desired position can be made by the method of Weisz and Cole. A chart, originally Presented by Schiebold and schneider7 and which allows a direct reading of the two stereographic polar coordinates of the corresponding pole of a given Laue spot, has been recomputed to aid in the stereographic interpretation of the cylindrical Laue X-ray photograph. Detailed instructions for the use of the chart, a simple example, and a comparison with the conventional flat-film Laue Methods, are presented. 1 HE problem of determining the orientation of the unit cell of a single crystal relative to a set of fixed external reference coordinates is fundamental to most problems of X-ray crystallography and to many experimental studies of the structure-sensitive physical properties of crystalline materials. Several techniques for measuring these orientation relations have been developed which correlate optically observable, orientation-dependent physical properties to the unit cell. Examples of such procedures include the observation of cleavage faces or birefringence, as discussed by bunn,1 or the examination of preferentially formed etch-pits, as discussed by barrett.2 Each of these methods is limited, for various reasons, to an orientation accuracy of approximately ±1 deg—a serious limitation in some experimental studies. Several other limitations decrease the generality of these methods. Of these, perhaps most notable is the absence in many crystals of the physical property necessary for the orientation technique. The most widely used methods for determining crystal orientation are variations of the Laue X-ray diffraction method. Because of the indeterminacy of the X-ray wavelength diffracted to a given spot, the interpretation of Laue photographs is now limited almost exclusively to the procedure of using a chart to determine the angular coordinates of the corresponding pole for each spot. For the flat-film geometries, either a leonhardt3 or a Dunn-Martin4 chart is used in interpreting transmission patterns, whereas a greninger5 chart is used for interpreting back-reflection patterns. A less common method of interpreting flat-film transmission Laue photographs is by comparing the Laue pattern with the Majima and Togino standards,6 or with the revised standards prepared by Dunn and Martin.4 Although this last method is applicable only to crystals with cubic symmetry, it can be very rapid and just as accurate as the graphical methods. The primary limitation of all the X-ray methods mentioned is the relatively small number of Laue spots and zones which are recorded on the flat film. Often, few, if any, major poles appear, thus making interpretation tedious and sometimes uncertain. The use of a cylindrical film eliminates this problem. Schiebold and schneider7 prepared a chart by which the orientation of the specimen crystal could be determined from a cylindrical Laue photograph. However, it was only drawn in 5-deg intervals of each of the two angular variables used to identify the Laue spots, thus limiting the accuracy of orientation to about ±3 deg. An examination of this chart indicated that if it were drawn in 2-deg intervals, crystal orientations to ±1 deg would be attainable. Subsequent use of the replotted chart has confirmed this accuracy. It is the purpose of this paper to describe the redevelopment and use of this chart, and to point out its advantages and limitations. I) CAMERA GEOMETRY AND CHART CALCULATIONS The geometry of the cylindrical camera with a related reference sphere is shown in Fig. 1. The X-ray beam BB&apos; pierces the film at the back-reflection hole B, strikes the crystal at 0, and the transmitted beam leaves the camera at the transmission hole T. One of the diffracted X-rays intersects the film at a Laue spot L. The normal OP to the diffracting plane bisects the angle BOL between the incident and diffracted X-ray beams. The point P on the reference sphere can be located uniquely by the two orthogonal motions 6 and 8 on the two great circles ENWS and BPQT respectively. Because the Bragg angle 8 (= 90 - < BOP) is always less than 90 deg, P always remains in the hemisphere BENWS. Therefore, if every possible pole P is to be recorded on the same stereographic projection, it is necessary that the projection reference point be at T with the projection plane tangent to the sphere at B.* The great

Jan 1, 1963

By F. F. Peng

The raw-coal feeding system and the upward medium current flow in a dense-medium vessel (DMV) are, in addition to the residence time of particles in the separator, important factors for efficient coarse particle separation. The feed material from a raw coal screen and/or pre-wet screen merge with the major volume of circulating medium as push medium, guided by an adjustable submergence baffle plate deep fed into the separator for effective separation. The remaining volume of the circulating medium enters from the purge and drain hoppers at the bottom of the DMV. This generates a gentle upward medium current flow in the separator, which prevents dense medium stratification/settling and merges as part of the push medium. A two-dimensional, two-phase model developed using computational fluid dynamics (CFD) is used to describe the flow pattern and evaluate the function of the dip plate for understanding the mechanisms of particle separation in the separator. The particle movement in the DMV is also tracked to investigate the major operating parameters affecting the separation performance of the DMV. The simulation results of the DMV separation performance are validated by in-plant test data.

Jan 1, 2007

Aluminum alloys are used in two broad classifications: wrought and cast. Wrought alloy products, which are formed into final shape by rolling, forging, extruding. etc., contain low percentages of alloying elements; whereas cast aluminum products, which generally are not worked before use, may contain higher percentages and a somewhat different selection of alloying elements. For example, wrought aluminum alloys usually contain less than one percent silicon and cast alloys contain as much as 18 per-cent silicon. While there are good techniques available for separating aluminum alloys from mixed scrap, there are no efficient ways to separate wrought aluminum from cast aluminum. The high levels of silicon, iron) copper, and zinc from the cast alloys make wrought-cast mixtures unacceptable for wrought alloy production. Consequently, separated wrought aluminum scrap commands a premium price on the market. Since increasing amounts of mixed aluminum alloys are being recovered from automobile scrap, this separation is important for efficient recycling of these alloys. Approach The difference in thermo-mechanical properties between the two classes of aluminum alloys is used as the basis for the separation process. Casting alloys lose their ductility within a certain temperature range while wrought alloys remain ductile. As temperature increases, aluminum alloys gradually become weaker, and at a certain temperature, each alloy loses strength and ductility due to incipient melting in localized areas. For casting alloys that temperature generally lies between 520° to 560° C, but it is above 600° C for most wrought alloys. Mild crushing, therefore, in the proper temperature range will result in complete fragmentation of the casting alloys but only plastic deformation of the wrought alloys. A simple screening step then is used to separate the oversize wrought pieces from the fragmented cast alloys.

Jan 1, 1984

By Lynn Crayne

We used Glyoxal as the hardener, at a final concentration of 10% by volume and therefore 20% by volume in the A-Component. They worked pretty well what we did was we shaved the joints on each of the pipes when we assembled them so they wouldn&apos;t rip the packers and then we greased the packers very well going in. We had to replace some but we have any getting stuck or didn&apos;t lose any pipes.

Feb 10, 2003

By A. R. Gaba

Phase I of the Canary Wharf development in London&apos;s docklands involves the construction of six fifteen storey buildings located predominantly over water of the West India Docks. The buildings are supported on some 1000 No., 25m long, open ended steel tubular piles driven through 10m of dock water to found in dense sand at a depth of about 15m below dock bed level. The piles are of composite section with reinforced concrete within the upper 17m of the steel tube. Three trial piles were installed in the dock to investigate the driveability and performance of the driven steel tubular piles. The piles were subjected to dynamic and static load testing. Loads were applied in both vertical and horizontal directions. Vibrating wire strain gauges were installed on the inside of the steel piles, on the reinforcement and in the concrete to determine the relative proportions of the applied load carried by the steel tube and concrete infill and to establish how these proportions varied along the length of the piles. Inclinometers were also installed to monitor the lateral deflection of the piles. This paper describes the driving, construction and testing of the three trial piles. The results of the vertical and horizontal loading tests are discussed and comparisons are made between dynamic and static tests carried out on the piles.

Jan 1, 1989

By A M. Sherwood

The Otago and Southland lignite deposits represent by far the largest known fossil energy resources in New Zealand. Despite their size they have remained virtually untouched since exploration in the 1970s and 1980s defined their extent. In total there is an estimated 10.9 billion tonnes of lignite in 13 defined fields in Otago and Southland. Much of the exploration work only targeted seams at shallow depth and it is highly probable that there are further resources at depth in the fields that have been explored to date. &nbsp; L&amp;M Lignite Limited (L&amp;M) holds exploration permits over a number of lignite deposits and is currently engaged in pre-feasibility studies to investigate the potential of the lignites for gasification. L&amp;M is focussing its studies on the Hawkdun and Ashers-Waituna deposits. Coal quality in these deposits, particularly Ashers-Waituna, is highly suitable for gasification. In total the two deposits contain 1647 Mt of potentially recoverable lignite. L&amp;M has engaged a variety of consultants to progress this project. The Hawkdun and Ashers-Waituna deposit databases have been re-evaluated and the resources remodelled. Further drilling has been carried out and the coal quality database has been expanded. The baseline project is to develop a mine to feed a plant that will produce liquids, specifically low-sulphur diesel and naptha, using the Fischer-Tropsch process. The project anticipates a staged development of 10 000 barrel per day units, each requiring mining at the rate of 12 700 tonnes of lignite per day. The production of other products including ammonia-urea, methanol, hydrogen and electric power is also under study.

Jan 1, 2005

By Yongping Hu, Dianchen Cai, Congya Zhang

China is a rich in stromite mineral resource. Unfortunately, the resource is very difficult to separate by using conventional flotation method because stromite and gangue minerals are very fine disseminated, the average size of them is about 10 µm or below, and the content of clay minerals such as illite is 19% or even more. In this paper, the aggregation floatation behavior of ultrafine (-10 µm) stromite, illite, ablbite and quartz using anion collector were studied. The result show that, Oxidized paraffin (O.P) is a good collector and has better selectivity for stromite particles flotation. The salted sodium silicate depressed illite gangues minerals effectively. The separation of mineral mixtures was carried on successfully at one stage flotation by the technique. The mechanism of O.P. and salted sodium silicate were studied and discussed by using IR and Zeta- potential measurements.

Jan 1, 1995

The Main Seam occurs in two &apos;pods&apos;, termed North and South, separated by an east-west oriented &apos;want&apos; zone (most probably a palaeo-channel). The seam on either side of the &apos;want&apos; area reaches thicknesses of over 30 metres but the North Main Seam adjacent to the &apos;want&apos; zone has been split into multiple seams of 10 to 15 m thickness. Rock types in the inter-burden of this area are characterised by inter-bedded sandstones and carbonaceous mudstones varying in thickness from 0.5 to 5 m. In the South Main Seam, an area of un-split coal exists and is characterised by few inorganic partings. Overburden in this area varies geographically from relatively thick mudstones in the south and east part of the coal deposit to inter-bedded sandstones and carbonaceous mudstones adjacent to the &apos;want&apos; area. The sandstone/mudstone overburden probably represents a splay or splay-channel complex emanating from the larger &apos;want&apos; area palaeo-channel. Modelling lithological variability is of use because it is one of the factors used in predicting cavability and roof support system design. The coal in both the north and south deposits were found to exhibit highly predictable quality and breakage parameters in relation to the coal geometry. Although ash yield and sulphur are mostly low and not variable, volatile matter and thus fixed carbon, varied in relation to seam thickness. In general, volatile matter (dat) decreased and moisture increased with decreasing seam thickness whereas moisture increased with decreasing seam thickness. In addition to these parameters it was found that the energy needed to crush the coal was lowest at the top and bottom of the seam and, on a whole seam basis, decreased with seam thickness. All of these parameters were found to vary in relation to the vitrain band content of the coal which itself was controlled by seam geometry. These parameters can therefore be modelled and inputted into mining plans and quality control operations.

Jan 1, 1996

By D. E. L. Zapata, O. J. R. Baena

"INTRODUCTION Mining is a fundamental part of the historical and economic development of a country. In Colombia, this is reflected from pre-Columbian jewelery, to being now one of the first exporters of coal worldwide, in 2017, the Colombian mining sector contributed approximately 6% of GDP (Ministerio de Minas y Energía, 2017). Coal, nickel, gold, platinum, emeralds, limestone, salt, phosphate rock, clays, siliceous sands and to a lesser extent copper, manganese, magnesite, barite, gypsum and various types of ornamental rocks, among others are produced (UPME, 2016). The contributions of mining activity in the economic dimension is more measurable, on the contrary in other dimensions, as the social and environmental, for this, every day there are new proposals and tools oriented to strengthen how to evaluate the contributions in terms of the sustainability and responsibility, with the aim of quantifying, concreting and non-utopian, to improve the life quality of a community and not only to comply with reporting and gaining prestige. Colombia has a generalized increase in the mining sector where the levels of informality and illegality are evident only 10% of mining activity is legal (UPME, 2014), also, the mining sector is accused of human rights violations, high levels of inequality, poverty and the affectation of ecosystems due to bad environmental management, among other situations (ACNUDH Colombia, 2015). This problem has generated rejection to the realization of the mining activity in many places of Colombia. At this point, it is important to clarify this problem is more complex, different actors are involved in this conflict, but it is an evidence that is needed a sustainability model for specific realities such as the Colombian mining. This situation in the current mining activity, is similar to the chemical industry situation three decades ago, because of an extensive problem in relation to repeated work accidents, natural disasters and indications as a highly polluting and unsustainable industry, with the aim of improving, not only this public perception, but also in the way of carrying out the business activity. Thus, in 1985, the Canadian Chemical Producers Association released the Responsible Care Program (RCP) (ICCA, 2015). Being aware that companies were responsible for the affected lives in some way by the operation and needed to improve workers safety, environmental protection and most importantly how legal persons should comply with the law, but go beyond this. RCP is most recognized sustainability initiative in the chemical sector, companies associated are recognized for having high quality standards, continuous improvement, visibility, corporate ethics, environmental and social management (ACC, 2015). In addition, to meeting the objectives is set out the creation of a model that increasing reputational sector levels. This initiative is considered to be a worldwide successful case of reporting corporate responsibility indicators and contributions to sustainability from the industry sector to local development (BASF Group, 2016)."

Jan 1, 2018

By R. C. A. Thurston

AT A FATIGUE SESSION organised by the A.S.T.M. in 1949, R. E. Peterson presented a brief introductory paper ( 1) in which lie referred to a discussion on the fatigue of metals which took place in England in 1849, and then proceeded to review some of the subsequent researches concerning the mechanism of fatigue. In the course of the review, he discussed metallograpl1ic studies with single crystals and polycrystalline materials, studies with X-ray methods, and the application of the electron microscope. During that hundred-year period considerable progress was made toward a better under-standing of the nature of fatigue, although it is probable that even greater attention was directed to the more practical aspects of the problem, such as the effects of notches, temperature, corrosion, surface treatment, residual stresses, and so on. Since then there has been an appreciable acceleration in the tempo of the fundamental work, partly influenced by the rapid development of the theory of dislocations, with the result that our knowledge of the mechanism of slip, the initiation of fatigue cracks, and their subsequent propagation, has still further advanced, although it is by no means complete as yet. The present paper is an attempt to out-line the more recent developments in these basic studies, to correlate them when possible, and to draw attention to those directions in which research might profitably be pursued.

Jan 1, 1957

By Allen W. Hatheway, John A. Albritton, Lloyd B. Underwood

Missouri River Division (FORD), U.S. Army Corps of Engineers (COE), has completed (October 1982) a study for the U.S. Air Force Ballistic Missile Office, in which desireable and needed changes in contracting methods for underground construction were identified. Due to the importance of geotechnical considerations in such construction, a good number of the resulting recommendations relate to geotechnical considerations. Corps contracts have traditionally served as models for contract documentation by public agencies and in private enterprise. Several standard features of present-day contracting methods were Corps innovations. Corps officials are generally in agreement with the recommendations of the Better Contracting reports published by the U.S. National Research Council (NAS/NRC), through its U.S. National Committee on Tunneling Technology (USNCTT). However, the findings of the 1982 MRD study indicate that additional changes are warranted for underground construction contracting methods; changes that deal specifically with site geological conditions, both known and to be reasonably anticipated, as well as with their associated impacts on construction. The 1982 MRD report identifies the need for nine specific improvements in geotechnical aspects of contracting; improvements based on recognition of geological conditions.

Jan 1, 1983

By T. P. McNulty

During the last decade, many exhaustive studies have been made of process energy requirements for the production of various metals and materials. Some excellent technical papers and text books have resulted, and some of these are included in the bibliography of this paper. These studies were, of course, prompted by the economic pressures which resulted from the beginning of the "Energy Crisis" in 1973. Our intensified consciousness of the cost of energy led, then, to a greatly improved understanding of the energy consumption attributable to individual mining, processing, and refining steps. It is worth noting, however, that an awareness of the cost of energy is not new and that efforts to minimize this cost were an important part of sound mine and plant management practice throughout the earlier days of our industry. One only has to read a few accounts of mining operations around the beginning of this century to develop an appreciation for the cost of supplying wood, coal, fuel oil, or electric power to remote locations.

Jan 1, 1983

By P. Talonen

Since the last Iron Control in Hydrometallurgy Symposium in Montreal in 1996, the Kokkola zinc plant has increased its capacity from 175,000 t/y to 280,000 t/y by installing an atmospheric concentrate leaching process, which has also affected iron control in the leaching circuit. Major changes have been made at the jarosite residue pond; a subterranean plastic wall reinforced with bentonite and cement has been built around the pond. A new water collecting system that is used for groundwater level control in the pond area was installed. With these two investments in the pond area, it is now possible to prevent any seepage flow from the pond into the surrounding environment. Water pumped from the residue pond is treated in the water treatment plant. This paper describes the behavior of iron in Kokkola&apos;s current leaching processes. The treatment of the jarosite, the improvements to the residue pond and the water treatment process are also described.

Jan 1, 2006

By L Dixon, J Carter, K Auyong

Fourier transform infrared (FTIR) spectroscopy and other near infrared (NIR) tools have been used in the bauxite industry for many years. Infrared spectroscopy exploits the differences in chemical composition and lattice structure to produce a characteristic response. Spectral devices, such as those from ASD Inc and the HyLoggerTM, provide qualitative mineralogical data targeted towards hydrated minerals detected in the near and short wave infrared region. The FTIR spectrum extends into the mid and thermal infrared range and can therefore respond to the presence of silicates and oxides, in addition to hydrates and carbonates.The key to successful utilisation of infrared spectra, however, is the interpretation methodology. In this study, FTIR spectra were calibrated against quantitative X-ray diffraction data for the determination of the mineralogy of iron ore. A full pattern profiling machine learning technique was utilised for the calibration, and the assessment of the regressions determined from an independent validation set. The abundance of key minerals – hematite, goethite, kaolinite and quartz – were determined and the results correlated against X-ray fluorescence assays and loss on ignition data. The results of the study indicate that spectral techniques using a full-pattern profiling machine learning approach and artificial neural networks can be used successfully to obtain objective and quantitative mineralogical data to support field observations and analytical results for iron ore resource modelling. A comparison of this technique to the cost, quality and timeliness of other quantitative mineralogy tools is also made.CITATION:Carter, J, Auyong, K and Dixon, L, 2017. Determination of iron ore mineralogy using Fourier transform infrared spectroscopy and machine learning, in Proceedings Iron Ore 2017, pp 519–528 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By M. O. Lai

"Metal matrix composite (MMC) with composition of Al-4.Swt.%Cu reinforced by IOwt.%TiB2 or ISwt.%SiC particulate has been successfully fabricated using powder metallurgy technique. Disk, compression and beam specimens were prepared with (a) layered structure containing ductile Al-4.Swt.%Cu with brittle Al-4.Swt.%Cu/TiB2 or Al-4.Swt.%Cu/SiC layers, and (b) homogenous constituent with composition of Al-4.Swt.%Cu/lOwt.%TiB2' The specimens for the fracture toughness measurement were built through three ductile-brittle-ductile alternating layers. For the beam specimens, the layers were built through brittle-ductile-brittle sequence. The brittle layer consisted of Al-4.S%Cu with fixed amount of reinforcement. Fracture toughness testing revealed an increase for layered composites although the total amount of the reinforcement was the same for all disk specimens. The increase in fracture toughness is due to the existence of ductile layers which manifests a strong influence on delaying the occurrence of fracture. It acts as a barrier to resist the propagation of crack and hence increases the fracture toughness of the layered MMC specimens, Delamination in the beam specimens was observed to be due to shear stresses. Fracture surfaces of both disk, compress and beam specimens were characterized using the SEM. IntroductionMechanical and thermal properties can be achieved by the incorporation of refractory secondary phases to constrain the plastic flow of the matrix in a metal matrix composite (MMC). The size of the reinforcement particulate incorporated must be in the range larger than the dislocation cell size and strongly bonded to the matrix (I). Particulate reinforced metal matrix composites hence provide high modulus, improved wear resistance and strength (2-4). Because of the incorporation of refractory phases which are generally brittle, the major limitation in the mechanical properties of MMCs is their limited ductility in comparison to their base metals. Cracks normally initiate from the reinforcement and voids (4, 5). Due to the lack of ductility, cracks propagate rapidly with increase in load. As a result, the interactions between reinforcement particles and propagating cracks have recently been of great research interest (6). In addition, volume fraction of reinforcement and aging condition of the matrix significantly affect the mechanical behaviour of MMCs. In the case of AI-3.5%Cu reinforced with varying volume fractions of SiC particulate, it has been found that the probability of particle fracture increased with increasing volume fraction of reinforcement (7)."

Jan 1, 1996

By C. Heckman, M. S. Moats, A. Luyima, W. Cui

"Chloride ions and their interactions with two organic smoothing additives – Cyquest® N-900 and HydroStar® 4208 – during copper electrodeposition were explored using cyclic voltammetry and electrochemical impedance spectroscopy. The results revealed that chloride ions, up to a concentration of 40 mg/L, depolarized the copper deposition reaction. A combination of chloride ions and Cyquest N-900 inhibited the depolarization reaction during copper electrodeposition. It is proposed that the chloride ions acted as bridging ligands between copper and Cyquest N-900. Addition of HydroStar at a concentration of 2.5 mg/L depolarized the copper deposition reaction when no chloride ions were present. This behavior did not change with the addition of chloride ions at the concentrations tested, indicating that chloride ions and the polysaccharide do not interact.IntroductionElectrowinning is a major production method used to obtain high-purity copper. In modern tankhouses, copper is electrodeposited onto stainless steel blanks and then stripped, washed and bundled for delivery. Significant improvements in the quality of electrowon copper have been made over the last few decades. Additives, temperature, current density, electrolyte concentrations and agitation are known to influence the quality of copper electrodeposits (Jenkins and Eamon, 1990).The influence of chloride and organic additives on copper electrodeposition has been the subject of considerable research. The addition of small quantities of chloride and organic additives has been recognized to significantly improve the properties of copper electrodeposits. These additives are critical in the prevention of dendrite growth and the production of smooth, dense cathode deposits.Chloride ions have been reported to catalyze the copper reduction reaction and assist in the production of uniform deposits (Lakshmanan et al., 1977; Sun and O’Keefe, 1992). Moreover, it is generally agreed that chloride ions depolarize the copper deposition process at low (several millimolar) chloride concentrations. This is because chloride ions catalyze the reduction of copper (II) ions to copper (I) ions (Cu2+ ? Cu+ + e-) in the rate-limiting step of this process (O’Keefe and Hurst, 1978; Ilgar and O’Keefe, 1997; Hebert, 2005; Shao, Pattanaik and Zangari, 2007)."

Jan 1, 2016