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By B. Panton, J. Carvalho, E. T. Brown

"A major consideration in the design of high capacity tiedown anchors for dam, bridge and tower foundations is the tensile resistance of the rock mass to pullout, typically as a result of overturning moments or hydrostatic uplift. Rock mass pullout capacity for installed anchors is developed from the tensile strength and fracture propagation properties of intact rock, the orientation and physical properties of the discontinuities and anchor confinement at depth. The typically assumed, but generally conservative, design approach is to calculate anchor pullout capacity using the dead weight of a uniformly shaped inverted “cone” with an assumed initiation point and breakout angle. In some cases, some tensile or shear strength is considered across the area of the assumed pullout cone, however, these strength estimates are based primarily on based on limited historic testing data, empirical relationships for rock mass strength developed for other applications, and engineering judgement.As an alternative to the current foundation anchor design method, this paper presents a new approach to the rock cone pullout problem using Discrete Fracture Networks (DFN) combined with numerical simulations. The simulations presented in the paper investigate the influence of fractures in a synthetic rock mass on ultimate anchor strength. In addition, the global influence on fracture network statistics on rock mass pullout failure is also discussed and it is contended that some of the aleatory and epistemic uncertainty inherent in the design of rock anchors can be reduced by considering fracture statistics in anchor design."

Jan 1, 2015

By John C. Loretto

"Answers to some of the problems ofRecovery and Metallurgical AccountingIn Gold and Silver Hydrometallurgical PlantsThe start-up over the last few years of new hydrometallurgical plants for the recovery of gold and silver has brought to the surface again a number of problems. Most of the problems have existed for some time and they manifest themselves mainly in two ways. Firstly, the plant results do not agree with the Metallurgical Test work figures and secondly, the Metallurgical Accounting figures do not balance.The plant results not agreeing with testwork figures are mainly due to:a) The testwork samples were not representative of the eventual plantfeed;b) Misinterpretation or misunderstanding of testwork;c) Plant losses;d) Plant design not allowing testwork results to be achieved;e) Operating deficiencies.a} The testwork samples being dissimilar to the plant feed occurs on a very high proportion of projects. The effects of this can beccr.ie exaggerated because the upper levels of the mining company often regard the original testwork figures as sacred and therefore base their judgement of current plant performance on these figures.Frequently the test work samples represent only a minor part of the orebody or alternatively a single composite of the whole ore body is used for the testwork long before it has been determined that all of the potentially different ore zones behave in the same manner. These errors can be compensated for by repeating the ""testwork tests 11 on current plant feed on a routine basis and using these tests to determine whether or not the plant is operating satisfactorily."

Jan 1, 1982

By Martin Wacker

Cameco Corporation, on behalf of a joint venture, is preparing surface and underground facilities at their northern Saskatchewan property in preparation for the future operation of a high-grade uranium mine. The Cigar Lake orebody is situated about 430 metres below surface at the unconformity between metamorphic basement rocks and flat lying sandstone. Major technical factors influencing the mining method selection include ground stability, control of ground water, radiation exposure and ore handling and storage. A decade-long test mine program resulted in the selection and validation of ?jet boring? a non-entry mining method. Cigar Lake?s jet boring mining method involves several major steps; artificial ground freezing of the orebody and surrounding rock, TBM (tunnel boring) type development of access crosscuts below the orebody, installation of cased pilot holes upwards through the ore, and ore extraction using a rotating high pressure water jet within the pilot holes. The resulting cavities are surveyed and backfilled with concrete. The ore slurry will be processed underground and pumped to surface. This paper discusses the jet boring mining method in general terms and includes highlights of the Cigar Lake test mine program completed in 2000.

Apr 1, 2005

By Mohamad Kharseh

There is general acceptance that climate change, which is the most important challenge facing humanity, is anthropogenic and attributed to fossil fuel consumption. Therefore, improving the performance of our existing energy systems and deploy more renewable energy resources is an urgent issue to be addressed. Geothermal refers to existing of heat energy in deep rock and sedimentary basins. This energy can be used to drive a power turbine to generate electricity. Traditionally, geothermal has been exploited in places with the plentiful hot water at relatively shallow depth. In the light of fact that ground temperature increases with the depth everywhere on the Earth, engineered geothermal systems (EGS) can be installed in any place to exploit the geothermal in generating energy. Unfortunately, the high exploration and drilling costs of boreholes is the main barrier to commerciality of EGS worldwide. In addition, there are technical problems associated with drilling big depth. In oil producing countries such problems can be addressed by utilizing whether active or abandoned oil or gas wells and, consequently, EGS can produce power at profit. The current study presents an analysis of a binary geothermal power generation system for commercial electricity generation in Qatar. For this purpose, two binary cycles are assumed the main difference between them is that the first one is air cooled while the other will be water cooled. The performance of the two cycles and the possibility of improvement has been shown. Economic analysis the power plant shows that the levelized costs of electricity is 3.6US¢/kWh and the pay-back time is less than 8 years.

Aug 1, 2013

By D. B. Nazzer

"ANY DISCUSSION of energy today is incomplete without consideration of nuclear energy. In the Maritimes, with plentiful supplies of coal, with relatively easy availabilty of imported oil brought in to the deepwater terminals, with future sources of large supplies of oil and gas anticipated from under our neighbouring continental shelf, and with the Fundy tides, you may question why nuclear energy should be considered. What follows may not give you a specific answer to that question, but it may provide a basis for better understanding. Energy from the sun, from hydraulic sources and from combustion has been available to man from prehistoric times, for thousands of years, but the most sophisticated source of energy, the actual conversion of matter into energy by man, has been developed entirely within the last one-third century, since the discovery of fission in 1939, and the application to generation of electric power has all been done within a generation or less. The pressure of military needs during and after the second world war was largely responsible for the speed of initial development, by funding and focussing the effort needed to develop the basic technology, and in particular materials. The U.S. defence program yielded, for example, the large-scale isotope separation processes for fissile U'35 and for heavy water. The nuclear submarine program yielded zircaloy, a key structural material for the core of the Canadian Candu type reactor."

Jan 1, 1972

By Peter F. Pullen

The need to apply the latest available technology to develop better tools and methods to meet problems in the mining industry was recognized by six of Canada's leading mining companies. As a result, MIROC (Mining Industry Research Organization of Canada) was chartered to identify problem areas in Canadian mining and to have research carried out to develop the tools and equipment to meet these perceived needs. The initial activity of MIROC has been in the environmental field, with improved clothing and protective devices being developed by contractors. Work clothing for miners is now being field tested. Respiratory protection and a new personal light source combined in a new "space-age" helmet are about to be issued for testing. Further developmental work is being carried on to offer these units and probably other personal protective devices on an individual basis as well as in a combined package.

Jan 1, 1979

By J. Spross

"The Key Lake mill has operated since the fall of 1983. The ore from both Key Lake open pits will be depleted by 1997. It is planned to use this mill, located about 60 km southwest of McArthur, to process the McArthur River ore.While the geological data collected so far on the McArthur deposit are encouraging, more information of the deposit is needed before any detailed mine planning can begin.The surface drilling program identified the orebody and provided information on the geomechanical and hydrological properties of the overlying sandstone. It was proposed to conduct an underground exploration program to further delineate the orebody. This was air proved following a public hearing and review process. This program involves the sinking of a 630 metre deep shaft and the driving of one or two drifts along a portion of the orebody. From these drifts, exploration drilling every 10 m to 15 m through the orebody will provide the information required for the preparation of a feasibility study and an Environmental Impact Statement (EIS)."

Jan 1, 1994

By W. A. Green

Introduction While pilot-mill operations were being carried on at Flin Flon, as described by R. E. Phelan (1), a detailed topographic map was being made of the area in the vicinity of the ore-body for later use in laying out plans for the final plant. The area covered by this survey was 6,600 feet by 6,600 feet, with contours on 2-foot intervals. As mentioned by Mr. Phelan, it was definitely decided at the end of November, 1927, to take up the option on the Flin Flon property and to proceed immediately with the plans for construction of a metallurgical plant at Flin Flon to treat 3,000 tons of ore per day, and of a hydro-electric power plant at Island Falls, Saskatchewan, to supply power for the future operations at Flin Flon. Railway Built From The Pas to Flin Flon Just as soon as the decision was made to go ahead with the construction work and opening-up of the property, it was of course essential to give immediate attention to the building of a railway to the mine. Many years previously, a preliminary survey had been made for a railway to branch off the Hudson Bay railway at a point 4.7 miles northeast of The Pas, and, during certain negotiations in 1925, the Provincial Government of Manitoba had agreed to guarantee the railway bonds necessary to finance the building of the line, so that it was possible to organize for this work immediately. A contract was let by the newly organized Manitoba Northern Railway Company to the Dominion Construction Company, Ltd., and Tomlinson, for the building of the railway to the mine, a distance of approximately 87 miles (see Figure 1). The Manitoba Northern railway is a subsidiary to the Canadian National railway, and all engineering and supervision of the contractors was done by the Canadian National engineers. Actual construction work was started in January, 1928. The first 52 miles of the railway from The Pas to Cranberry Portage is over fairly level, although slightly rolling, country, and a considerable portion of the route is over muskeg area. Rails were laid on top of the frozen muskegs. Gravel deposits were opened-up along the line and, before warm weather; sufficient ballast .was distributed in the muskeg areas to prevent thawing under the track, and thus give the necessary support to allow uninterrupted transportation over the line.

Jan 1, 1935

By D. A. Brown, C. Lowe

"Abstract -A multi-sensor (electromagnetics, magnetics, gamma-ray spectrometry, and VLF) geophysical survey was recently conducted in the Purcell Basin of southeastern British Columbia in an area encompassing the world-class Sullivan Sedex deposit. The purpose of the survey was to geophysically characterize the known mineral occurrences and to develop strategies to enhance future mineral exploration in the basin. Follow-up investigations of geology and measurements of rock physical properties helped constrain interpretations of the geophysical data sets.Despite extraction of more than 90% of the ore from the Sullivan deposit, it is clear that the mineralization there, as well as at other Sedex occurrences surveyed, is characterized by high conductivity values, strong bedrock conductors, and elevated magnetic anomaly values. The albite-sericite alteration which accompanies this mineralization yields high potassium and low thorium-potassium ratio values. Associated Moyie gabbro is characterized by low electrical conductivity and radioelement concentrations and by high magnetic anomaly values. The study has also aided exploration for other mineral deposit types including stratabound Cu-Ag, placer gold, vein and disseminated basemetal deposits. In addition, the geophysical data have helped constrain geological interpretations of the basin."

Jan 1, 1998

By Carmen M. Neculita

Optimizing the long-term efficiency of passive systems for the treatment of highly contaminated acid mine drainage (AMD) is still a challenging issue. The optimization lies, among others, on improving the understanding and quantification of metal removal mechanisms in order to predict and enhance the stability of neo-formed minerals in secondary phases. Sorption, and precipitation as oxides-hydroxides, carbonates and bio-sulfides are likely the most important metal removal mechanisms involved in passive biotreatment of both slightly and highly contaminated AMD. In the same time, the preferred mechanism is precipitation of metal sulfides that are more stable and less pH dependent than carbonates and oxides-hydroxides. However, results of relatively recent research studies performed at laboratory scale showed that sulfides accounted only for up to 15% of total metals removed in passive bioreactors treating highly contaminated AMD dominated by iron (around 500 mg/L). Several approaches were used in the aforementioned studies to understand and quantify metal removal mechanisms in spent reactive mixtures collected from long-term (12-15 months) operating column bioreactors. These included: thermodynamic equilibrium modeling and various chemical extractions and mineralogical analyses (such as single and sequential extractions, acid volatile sulfides-simultaneously extracted metals determination, scanning electron microscopy, X-ray diffraction, and thermo-gravimetric analysis). The large proportion of metals (85%) removed by sorption and precipitation as oxides-hydroxides and carbonates suggests a relatively high mobility of the neoformed minerals, especially in low pH conditions. However, no data is available on the long-term stability of spent reactive mixtures and, on the implications for the sustainable management of this type of solid waste. Lately there is almost a consensus that the efficiency of highly contaminated AMD treatment is warranted by the use of multi-step passive systems, including both chemical and biological units, installed sequentially. However, very few well-documented studies are available on the design, construction, operation and long-term efficiency of these multi-step systems. A leading example is the tri-unit passive system installed on the abandoned Lorraine mine site (Québec) to treat a highly contaminated AMD dominated by iron (about 2,500 mg/L). This tri-step system (160 m3), consisting in two bioreactors separated by a unit filled with wood ashes, achieves to date a satisfactory removal of iron (up to 99%). Moreover, based on the data collected during laboratory testing, iron was mainly removed in the wood ashes unit (from around 3,200 mg/L to 10 mg/L) by precipitation of oxides-hydroxides as predominant mechanism and only partially by sorption. However, no data is available on the actual metal removal mechanisms in the field. Overall, theses multi-step systems are more complex and their long-term performance is even less predictable than the single unit systems. This paper presents the current knowledge and the research needs on metal removal mechanisms in passive bioreactors and multi-step systems for the long-term treatment of highly contaminated AMD. KEYWORDS

Aug 1, 2013

By D. R. Murray

A four-year study was carried out to determine the ability of coniferous trees to aid in the reclamation of uranium tailings at Elliot Lake. Five species were planted: white cedar, white spruce, jack pine, scotch pine and red pine. More than 570 bare-root, two-year-old seedlings were planted on bare tailings and in areas of established grasses. A further division was made between areas of coarse and fine tailings. Over-all survival and growth of the trees has been far below expectations based on previous experience with several varieties of grasses. The criteria for assessment have been per cent survival and yearly growth as determined by plant height. Pine was superior, with 68% survival when planted in bare coarse tailings, 45% for vegetated coarse tailings and 34% for vegetated fine tailings. Cedar had the worst survival rates at 49%, 14% and 7% respectively. No species survived on bare fine tailings. The survival and growth of the coniferous trees have been related to species, environmental conditions and tailings properties.

Jan 1, 1978

By Georges Houlachi, Akram Alfantazi, Maysam Mohammadi

Manganese ions in zinc electrowinning electrolytes form a protective MnO2 layer that ultimately decreases Pb contamination in the zinc product. In this study, the effect of dissolved Mn2+ on the electrochemical performance of Pb, Pb-Ca and composite Pb-MnO2 anodes was investigated. The properties of the MnO2 layer formed on these anodes were studied and compared. Potentiodynamic polarization and cyclic voltammetry experiments were performed in 180 g L-1 sulphuric acid to study the electrochemical reactions occurring on the anodes. The anodes were subjected to galvanostatic polarization at 50 mA cm-2. The morphology and uniformity of the MnO2 layer on the anodes were examined using scanning electron microscopy (SEM). Experimental results revealed that the MnO2 layer formed on the composite anode was more compact and uniform compared to that formed on the Pb and Pb-Ca anode. It was also observed that the cell mud formation rate, and consequently manganese ions consumption, depended on the anode type. Although initial formation of the MnO2 layer decreased the oxygen evolution overpotential, its growth might negatively affect electrocatalytic activity of the anodes.

Jan 1, 2014

By R. V. Fox, L. K. Sinclair, D. L. Baek

"In this study, rare earth elements were recovered from bastnasite concentrate and waste fluorescent lamp phosphors using supercritical carbon dioxide extraction with a nitric acid/tributyl phosphate adduct. Several pretreatment methods were used to alter the crystal structure of the source materials, and thus improve rare earth element recovery. Pretreatment methods included 1) dry roasting of the source material at 730oC, 2) decomposition with 50% sodium hydroxide solution at 150oC for 4 hours, and 3) decomposition with 12 M sulfuric acid at 300oC for 4 hours. Treated and untreated samples underwent supercritical extraction at 24 MPa and 65oC for 1 hour. Untreated bastnasite and phosphor samples showed <10% rare earth element recovery, but sodium hydroxide digestion resulted in >60% recovery for most rare earth elements. Dry roasting of the bastnasite concentrate was also effective, resulting in >60% recovery for cerium.INTRODUCTIONRare earth elements (REEs) consist of the 15 lanthanides, scandium, and yttrium. Scandium and yttrium are included because they are in the same group as lanthanum, appear in many of the same ore deposits as the rest of the lanthanides, and exhibit many similar chemical properties. REEs are used in a wide array of applications including electronics, magnets, catalysts, glass, and solid-state lighting (Xie, Zhang, Dreisinger, & Doyle, 2014). Because of China’s continued dominance of worldwide REE production, the United States Department of Energy has sought to diversify domestic supplies of REEs (United States Department of Energy, 2011). A key part of this strategy is the development of improved extraction methods for both ores and recycled sources.Supercritical fluid extraction (SFE) is a promising technology for extraction and separation of rare earth elements. Contact with an acid adduct dissolved in supercritical carbon dioxide allows for the rapid extraction of REEs from solid matrices. Supercritical CO2 has several potentially useful properties as a solvent, including high diffusivity and the ability to tune solvation properties by adjusting pressure. Such tunability may have applications in separating the REEs once they have been extracted from the solid phase. Tributyl phosphate/nitric acid adducts (TBP:HNO3) are a particularly promising class of adducts for SFE extraction of rare earth elements. Using TBP:HNO3 adducts in supercritical CO2, several researchers have successfully extracted REEs from their oxides (Wuhua, Pijia, & Yongjun, 2010; Zhu, Duan, Xu, & Zhu, 2009). However, there is a complication in applying this technique to many types of ores and recycled sources: REEs are often locked in refractory minerals which are resistant to acid attack, resulting in limited recovery in supercritical extraction."

Jan 1, 2016

By Iain Sommerville, Hugh Mountford, Dawid D. Smith, Claude Dube, Brett Hixson

JW Aluminum use lean and Six Sigma techniques to continuously improve their target of reliable, repeatable and reproducible (3R) manufacturing. Six Sigma’s second stage gate, known as "Measure" involves identification and qualifying appropriate measuring systems. Metal quality (inclusions) are known in the industry to be an important element in 3R casting. The measurement of inclusions at JW Aluminum historically depended on outside vendors. In order to establish real time inclusion measurement ability within JW Aluminum, inclusion measurement systems in the marketplace were investigated. The qualification of a MetalVision MV20/20 ultrasonic inclusion analyzer are discussed as well as the subsequent application of the system in melting and casting improvement projects.

Jan 1, 2015

By G. Lafont

Aug 1, 2013

By Frederick J. Browne

Water, water everywhere, but not a drop (fit) to drink! Trite, but how often only too true? What is there met with in mining which, under various circumstances, may be said to be the most sought-for and highly-prized and also the most objectionable and most feared? Water! What visions that combination of five letters brings to all thoughtful minds? Up to near the end of the eighteenth century water was thought lo be an element but was then discovered to be the result of the combustion of two volumes of hydrogen with one volume of oxygen, and water so produced is chemically pure. Pure water is a clear and colourless liquid when seen under ordinary conditions, but appears bluish when seen through a long tube, and this same bluish tint may be observed in many lakes, especially those of glacial origin. A story often told describes a prospector in the desert who, failing to find water to replenish his canteen, suffers torture and death under fearful circumstances. Then again we may recall the flooding of mines, where water poured in so quickly that there was no opportunity of saving the unfortunate workmen. Instances might be multiplied without number showing that either the lack or excess of this essential fluid has taken heavy toll of human life. In all branches of mining and associated industries water must be dealt with to a larger extent, from an economic point of view, than any other substance, and very often the purity of the water is a matter of considerable importance.

Jan 1, 1925

By Cesar Carrasco

Mine reconciliation is the art and science of comparing predictions and real-world outcomes with the intent of revealing the true quality of performance of models, planning, mining, and mineral processing. When mine reconciliation is conducted in a systematic, transparent and sustainable way it can play a central role in the governance of Mineral Resource and Mineral Reserve (MRMR) estimation and reporting. The core processes of modelling, planning, mining, and processing need to be transparent to be able to demonstrate that MRMR are reliable predictors of mine performance and value. Transparency is also necessary for mine technical staff to generate meaningful analyses, conclusions, and business improvement actions that demonstrably maximise value for all stakeholders. Most mines have some form of mine reconciliation practice, however because there is no agreed industry standard, and because mine reconciliation is difficult for a variety of reasons, it is often unsustained and/or ineffective at delivering the required transparency of performance. To deliver true governance of MRMR and business value, mine reconciliation must be sustainable. There are two categories of issues that combine to make mine reconciliation extremely difficult to sustain, these are technical, and people related. Technical issues include defining standard terms, accurately tracking material flows, data availability/adequacy/quality, calculation of key performance indicators and tolerance limits, analysis, and interpretation of results, understanding limitations of modelling techniques, and defining appropriate actions that can deliver value. These technical challenges are non-trivial, however compounding these are a range of people issues that include personal agendas, scepticism, lack of knowledge and experience, poor teamwork, absent leadership, toxic workplace culture, staff turnover, ineffective communication, siloed organisational structure, and lack of deliberate change management. All these problems can be solved with clarity of purpose, definition of the process of mine reconciliation, discipline in following the process, appropriate resourcing, and commitment to success across the entire organisation. Outlined in this paper is a management system that delivers sustainable mine reconciliation by addressing both the technical and people issues described above. This approach can deliver significant value for a mine and adds a robust, defensible governance over MRMR estimation and reporting.

Oct 1, 2024

By L. D. Roper

"This paper introduces novel comminution flowsheet concepts involving a novel apparatus, eccentric-high-pressure-centrifugal-comminution (eHPCC), and forthcoming advantages to the international mineral processing community. eHPCC is one-machine synergising high-pressure-rolling surfaces, high-intensity-attrition and centrifugal classification. eHPCC has demonstrated: an absorbed power- intensity of 4 MW/m3; receipt of lump feed whilst producing 80% of product particles less than (p80) 120 µm (choke-fed, dry, open circuit without grinding media; an inert comminution environment); tramp metal tolerance, and a minimum embodied-free-energy saving of 15% as compared against conventional comminution (this comparison withstanding 133-times difference in throughput). Furthermore, this paper introduces: process design and operating characteristics of eHPCC (wet, dry, with and without grinding media); reline considerations (vertical-lift without confined-space). The international mineral processing community is invited to consider eHPCC as an alternative to conventional comminution circuits and/ or complimentary so as to enhance existing process flow sheets.INTRODUCTIONEccentric-high-pressure-centrifugal-comminution (eHPCC) was conceived in 2013 (Patents pending) and has the potential to eliminate the in-efficiencies and complexity of conventional tumbling mill circuits. During the development and testing phase eHPCC demonstrated improved energy efficiency and sustainability offsets.eHPCC will compliment any upstream feed source, be it run-of-mine (ROM), primary crushed rock, or any other conventional comminution stream such as tumbling mill oversize. Another novelemerging technology, Conjugate Anvil-Hammer Mill (CAHM) (Nordell and Potapov, 2011), receiving ROM, will be a complimentary open-circuit feed to eHPCC for very high throughput flow-sheets.eHPCC may compliment downstream process requirements through selective mineral liberation. Selective mineral liberation is entirely feasible as the ore is comminuted upon itself (autogenously) in the high pressure zone caused by the synchronous rotating components."

Jan 1, 2016

By R. Aubertin, G. Panneton, P. Donovan

The Detour Lake gold project is located in northeastern Ontario, approximately 300 km northeast of Timmins, within the Abitibi greenstone belt in the northwestern portion of the Archean Superior Province. Historically this greenstone belt has produced approximately 180 million ounces of gold, largely from narrow vein underground mining. The Detour Lake project is a site of extensive past exploration since 1974, as well as underground and limited open pit mining activity from 1983 to 1999. During this period, it produced 1.8 million ounces of gold. Underground mining focused on narrow vein conventional shrinkage and mechanized longhole stoping. After acquiring the property in January 2007, Detour Gold Corporation initiated a comprehensive drill campaign to define the potential for a large, open pitable, low-grade gold deposit. From 2007 to present, Detour Gold has completed over 500,000 metres of diamond drilling. A technical report completed in March 2011 defined an open pit mineral reserve of 14.9 million ounces of gold, which is Canada&apos;s largest undeveloped gold reserve. The Detour Lake project is currently in development and infrastructure construction of the mine facilities started at year-end 2010, after all the necessary Provincial regulatory permits were received. Gold production is expected to commence in early 2013. Gold mineralization at Detour Lake is associated with a large scale deformation zone (Sunday Lake Deformation Zone; "SLDZ") that occurs at the contact between the 2.72 Ga Deloro Group mafic metavolcanics and the 2.69 Ga Porcupine Assemblage metasedimentary and metavolcanic rocks. The bulk of the gold mineralization is found in the hanging wall of the SLDZ, which is associated with a stockwork of auriferous quartz veins that splay from a flexure along the deformation corridor. The mineralization forms a 200-350 metres wide auriferous corridor defined over 3 kilometres along the strike of the mafic metavolcanic assemblage, from surface to at least 1,000 metres depth. The richest gold mineralized zones are commonly associated with quartz veins with a strong biotite alteration and local zones of pyrrhotite-chalcopyrite-pyrite-gold enrichment formed during the deformation of the quartz vein system.

Jan 1, 2011

By M. Dadvand, G. Kipuros, A. Dadvand

"The ability to codeposit fillers within a nickel matrix has led to the production of a new generation of cermet coatings with properties useful for various applications. Hexagonal boron nitride (hBN) is a ceramic-type particulate matter with thermal conductivity, thermal stability, inertness, and lubricity properties that allow it to be codeposited. In this paper, a method was developed for modifying hBN surfaces to allow them to be uniformly dispersed in water-based solutions such as an electroless nickel plating bath. hBN surface modification improved wear performance of the electroless plated cermet due to enhanced interaction between the particulate and nickel matrix. RÉSUMÉ La capacité à effectuer un dépôt simultané de charges dans une matrice nickel a abouti à la production d’une nouvelle génération de revêtements cermet (une combinaison de céramique et de métal) dotés de propriétés très utiles pour diverses applications. Le nitrure de bore hexagonal (h-BN) est une matière particulaire de type céramique utilisée pour ses excellentes conductivité et stabilité thermiques, son inertie ainsi que son caractère lubrifiant, qui permettent son dépôt simultané. Cet article explore une méthode mise au point pour modifier les surfaces du h-BN de manière à ce qu’elles se répandent uniformément dans des solutions aqueuses telles qu’un bain de dépôt autocatalytique de nickel. La modification des surfaces du h-BN a amélioré la résistance à l’usure du placage autocatalytique du cermet en raison d’une interaction accrue entre la matière particulaire et la matrice nickel.INTRODUCTION Electroless nickel alloy coatings can be used for many applications; however, the need for improved tribological properties such as higher wear resistance and better lubricity has increased interest in incorporating particulates (fillers) into the nickel matrix by codepositing the particulates with nickel during the plating process. The selection of the particulate type depends on the desired properties (Sahoo & Das, 2011; Sudagar, Lian, & Sha, 2013). In terms of tribological applications, electroless nickel-based composites are categorized mainly into lubricating and wear-resistant composite coatings depending on the type of particles incorporated. The electroless nickel-phosphorus (Ni-P) composite coatings are composed of codeposited solid lubricants such as polytetrafluoroethylene (PTFE), graphite, WS2, MoS2, and hexagonal boron nitride (hBN) and, compared to nanocomposite electroless Ni-P coatings, they demonstrate a lower coefficient of friction. On the other hand, the nickel-phosphorus wear-resistant composite coatings are composed of hard particles such as silicon carbide (SiC), aluminum oxide (Al2O3), boron carbide (B4C), silicon nitride (Si3N4), diamond, tungsten carbide (WC), and zirconium oxide (ZrO2) and, compared to nanocomposite electroless Ni-P coatings, they have higher hardness and better wear resistance (Sahoo & Das, 2011; Sudagar et al., 2013; Parucker, Klein, Binder, Ristow, & Binder, 2014; Chakarova, Georgieva, Petrova, Dobreva, & Stoychev, 2016)."

Jan 1, 2018