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By John D. Galloway

Mining is one of the important primary industries of Canada, with a gross production in 1927 estimated at $241,773,000- the highest in the history of the country-and an impressive dividend record. It is quite apparent, therefore, that mining is a business worthy of the careful attention of the people of Canada. Furthermore, with a vast undeveloped territory more or less mineralized, it is highly probable that our mining industry will continue to expand indefinitely, with a consequent increase in production and in the amounts of the yearly profits distributed. In recent years, the public has taken a larger interest than formerly in mining-an interest, moreover, that is not academic, but primarily from the viewpoint of profits. It is quite evident that mining is a profitable business, at least to some, and the average man on the street, hearing of these profits, is attracted thereto. I have no doubt that many of you have .read in promotion prospectuses, with figures to prove it, that mining is the most conservative, the safest, and the highest-yielding business in the world. Now, a lot of this information is best judged by the old saying that "While figures don't lie, liars figure". At the same time, mining, properly conducted, is a profitable business, even though speculative, and undoubtedly much profit will come from Canadian mines in the future. In this paper my conclusions regarding mining investments are based largely on British Columbia experience, together with some slight knowledge of mining conditions in the other Provinces. It is considered, however, that the inferences drawn are applicable to mining throughout Canada.

Jan 1, 1928

By W H. Poole, E. R. W. Neale

A new style of tectonic map based on age of folding has been prepared for the Canadian Appalachian region as part of the Tectonic Map of Canada Project. This style of map pro-vides a clearer picture of the tectonic history of the region than any meth-od hitherto attempted. Precambrian blocks that were relatively unaffected by Palaeozoic de-formation are distinguished on the Great Northern Peninsula and in the Conception Bay region of Newfound-land. K/ A age determinations suggest that these blocks were intruded and metamorphosed during Grenville orogeny. Other Grenville-like rocks, on Cape Breton Island and in New Brunswick, were more actively involved in subsequent Palaeozoic orogeny. Taconic orogeny, the first phase of Palaeozoic deformation, took place in Middle and/or Late Ordovician time and was accompanied by intrusion of ultrabasic rocks. Evidence of the -

Jan 1, 1961

By J. N. De La Vergne, J. S. Redpath

"The authors make recommendations that they believe will improve the efficiency of a mining company's use of a mining contractor's services. The recommendations are in the form of specific ""DO"" or ""DO NOT"" instructions, giving explanations and covering the contracting process from the end of the feasibility study to the end of the job. IntroductionThis paper is an attempt by the authors to set out some of the things which they feel an owner should consider to achieve maximum effectiveness from mining contractors. It is based on our experience as contractors as well as our experience as consultants to owners. Should this paper create the impression that we feel all the responsibility lies with the owner, this is neither our intention nor our belief.Before the Tendering Process BeginsUse Defined EstimatesIn Feasibility Study DO NOT estimate your cost or schedule by telephoning contractors and asking them for ballpark figures. The only kind of estimate that is worth anything is the one that is clearly defined on paper and bears the signature of the author. This type of time or cost estimate takes time to prepare. In general, the estimate will be worth what you pay for it.Ensure Adequate FinancingDO NOT ask contractors to tender on a project unless the funds have been approved for it. Remember that, depending on the size of the job, it will cost the contractor from $5,000 to $50,000 to prepare his tender. When financing is not assured, a single contractor should be approached regarding a detailed estimate and he should be paid for it. Contractors should not be expected to finance speculative mining ventures."

Jan 1, 1980

By Odette Corbu

The Canadian Trade Commissioner Service: Who we are ? A worldwide network of professionals in international business development, with preferred access to business knowledge and contacts, committed to advancing Canada?s interest ? Our global presence ?At home: 17 Regional Offices with over 100 trade officers ? Abroad: 149 offices in 101 countries with over 900 trade officers.

May 1, 2009

By S. H. Logan

Mr. B. Neilly: A week or so ago the Secretary was good enough to forward me an advance copy of this paper by Mr. Logan and it was suggested that I comment on it at this meeting. At that time I was not very certain that I would be here, so I committed my thoughts to paper. As a matter of courtesy to Mr. Logan, I sent him a copy of my proposed remarks and I would like to give you just what I sent to him. Appreciating fully Mr. Logan's ability and many sources of information, one naturally hesitates to question anything seriously set forth as his considered opinion. Neither does one of my political stripe like to accuse him of being too 'conservative.? However, in places his paper reminds me of another general manager of a Canadian bank. While I was still Secretary of the Ontario Mining Association, this general manager wrote asking for our forecast on the current year's mineral production, stating that he proposed to refer to such production figures in his annual address to his shareholders. The request was considered very complimentary to the Ontario Mining Association and, in my opinion, justified a great deal of serious study and effort. Finally, the estimate was prepared and forwarded, showing a modest increase over the previous year's total. Picture our surprise and chagrin on reading his address to find that he predicted not an increase but, if you please, a decline of over $10,000,000. Before I cooled off I wrote asking the basis of such a prediction and got a reply to the effect that men in his position had to be ultra conservative in picturing the future.

Jan 1, 1931

By T. Banerjee, R. deS. Almeida, D. Gudgeon, F. C. F. Batista, L. deÁ. Silva

"Yamana Chapada’s mine is one of the larger copper-gold mines in Brazil. The mine is located in Goiás state, in the central part of Brazil. The mine has estimated Mineral Reserves of 4.1 million ounces of gold and 3.2 billion pounds of copper as of December 31, 2016. While gold and silver are significant, Chapada’s process flowsheet is configured closer to that of copper facilities. This includes a SAG/Ball configuration for grinding followed by flotation. In the case of Chapada, the mineralogy results in higher-than-normal complexity, notably a significant circulating load both in the grinding and flotation circuits. From an operating perspective, the complexities are controllable, but require careful attention to ensure that circulating loads are effectively managed and gold is not lost to tailings. Chapada created an automation roadmap in 2016 designed to increase plant performance (tonnage, recovery and efficiency). Based on strong potential, the project was fast tracked and within 4 months instruments were installed, control algorithms implemented, and training sessions took place to ensure sustainability at site. This paper will follow the Chapada journey from identifying the opportunities through to implementation and testing.IntroductionYamana Chapada mine is a Copper-Gold mine located in Goiás State, Brazil. Although the mine contains large quantities in Mineral Reserve of gold (4.1 million contained oz as of December 31, 2016), Chapada is primarily a copper mine with copper principally found as chalcopyrite. Accordingly, the processing flowsheet at Chapada is comparable to that of other copper mines with a SAG and Ball mill each partnered with a cyclopack, followed by a flotation circuit. While the overall design is conventional, the mineralogy at Chapada results in significant circulating loads both in the grinding and flotation circuits. This does introduce certain complexities for operating strategies and practices, but, importantly, favourable recoveries and elevated processing rates can be maintained, albeit they need to be closely managed. Plant automation helps in this regard."

Jan 1, 2018

By W. Hunka

PACIFIC PETROLEUMS, Ltd. first discovered commercial quantities of gas in the Peace River area in 1952. Development of gas wells in this area is quite ex-pensive due to low penetration rates. To improve the economics, the potential of the wells in many cases had to be increased. At that time, well stimulation was still in its infancy in Canada and in this area, in particular, no treatment of any consequence had been attempted. Therefore, trial-and-error was the only means available to determine the stimulating technique that would give optimum results. Various fluid treatments were available and these were used wherever the application was warrant-ed. This paper covers acid fracture and explosive treatments as carried out on various gas-bearing horizons.

Jan 1, 1958

By D. R. E. Whitmore, J. M. Harrison

There are five logical stages in the search for orebodies in virgin territory, namely: (1) reconnaissance inventory of geology, and related investigations; (2) development of broad concepts as a basis for selecting regions of potential mineral deposits; (3) assessment of criteria leading to specific localities within these regions; (4) geo-physical and geochemical studies that will delineate small anomalous areas; and (5) stripping, drilling or other means of locating ore. In addition, the development of new means of extracting mineral resources and the finding of new uses play a vital role in our mineral industry. The continued growth of this industry will be largely governed by our ability to develop or to adapt new concepts and techniques, and to produce a greater number of scientists and engineers. It should always be remembered that more than one-third of Canada's exports are dependent upon our ability to find, develop and economic-ally exploit new orebodies.

Jan 1, 1967

By A. Pearson, F. A. Auld, S. O. Colbeck

"""The theory of buckling of shafts and Steel tunnel-linings"" was published by E. Amstutz in 1970 and commented on by S. Jacobsen in 1974. The authors have revised and enhanced Amstutz’s work to address Jacobsen's comments on its limitations and to extend its validity over a wider range of pipe/shaft geometries, including those commonly found in deep mine access shafts. The author has looked at Amstutz’s assessment of strengthening with flexible shear anchorages and adapted the theory of non-linear shear deformation response of bolts to develop a method of assessing increased buckling capacity utilising the full plastic shear capacity of studs. INTRODUCTION “Amstutz Buckling” refers to the buckling of pipe embedded in concrete under external uniform pressure. In terms of a mining environment, this relates directly to the design of a watertight shaft. This load case will commonly occur where a main shaft is cast against a geostatically stable primary liner and the only load applied to the final shaft is that of a uniform ground water load. Ernst Amstutz wrote his first paper on buckling of pressure-shaft steel linings in 1950 and subsequently improved his theory (Amstutz, 1970), which was then widely adopted for use within the industry. Years later, an alternative approach (Jacobsen, 1974) was proposed. Within his paper Jacobsen critiques Amstutz work, identifying some mathematical inconsistencies and highlighting limitations of the theory imposed by approximations adopted by Amstutz. Despite these limitations Amstutz work has still been used as the favoured design theory for use in the mining industry. In reviewing this body of work the author realised that with the advent of readily available computing software it was possible to adopt an iterative approach using Amstutz approximate formulae to find a solution to the original precise formulae, thus eliminating the limitations highlighted by Jacobsen The shear deformation to load characteristics of bolts has long been established (Crawford & Kulak 1968) and used for the plastic design of bolted connections in shear. This relationship is directly transferable to the design of shear studs, typical properties are well known, and actual values easily established in simple lab tests. The author has taken this relationship and modified Amstutz theory (Amstutz, 1970) for shear anchored strengthened liner buckling, to give a more efficient solution, using readily available material properties."

Jan 1, 2019

By Denis Yaychuk, Gary Billingsley

The economic eva luation of a mineral property or mining venture should include the quantification of ri k as part of the analy is. The re ults of such an analysis provide the decision-makers not only with the most likely financial outcome and the probability of achieving that or any other outcome. but al o with a ranki ng of the relative impact of all the ri sk factors. These type of resu lts offer more complete information for investment and technical deci ions than the traditional cash flow/ ensitivity analysis. In addi tion. by attempting to quantify ri sk. the personnel providing the va ri able input are forced to take a much clo e r look at the data involved, and are fo rced to work together. the reby increa ing substantially the awa reness of the impact their work and others· work has on th e outcome of the analysis.

Jan 1, 1986

By K. Law

"The Hatch Product Transport (HPT) system is a highly flexible and configurable route selection and sequencing system for controlling large bulk material handling facilities. The system has a generic control algorithm that can be configured to suit any material handling facility. It can also be easily reconfigured to cater to plant expansion or modifications without incurring significant disruption to the existing production, costs in testing, and re-commissioning, thus achieving cost savings throughout a facility’s lifecycle.This new material handling control system has been installed at BHP Billiton’s Port Hedland iron ore terminal to facilitate its expansion to beyond 100 Mt output capacity."

Jan 1, 2006

By Lloyd W. Trevoy

Titanium and zirconium heavy minerals occur in the tailings streams from processing plants which use the hot-water extraction process for recovery of bitumen from tar sand. In a research program conducted by Syncrude Canada Limited, the crude tailings stream was upgraded to produce quality zircon and titanium mineral products. To process the tailings through conventional upgrading equipment, bitumen residues must first be removed from the mineral grains. Then, by gravity separation, fines and coarse sand grains were removed and a 71% heavy minerals concentrate was prepared which was further separated by high-tension equipment into zircon and titanium minerals concentrates. The zircon concentrate was upgraded by gravity, magnetic and high-tension cleaning to produce a high-quality 98% zircon product. The titanium minerals concentrate was separated into rutile, leucoxene and ilmenite fractions. Heavy minerals distribution in tar sand drilling core samples has been evaluated for various locations on Syncrude Lease 17, and expected annual production levels of heavy minerals have been estimated. A preliminary evaluation has been made of the potential for zircon, leucoxene and rutile production and for further upgrading of ilmenite and leucoxene to synthetic rutile for titanium dioxide pigment production.

Jan 1, 1978

By M. Rafati

In this investigation, the effects of T4 and T6 heat treatments of AZ91 magnesium cast alloy have been studied. The effects of different microstructural details such as morphology, size and distribution of precipitates and their influence on fracture mechanisms were investigated by optical and scanning electron microscopy. The mechanical strength of the alloy after T6 treatment was found to increase in comparison to the T4 treatment, due to the formation of discontinuous precipitates in the grain boundaries. Precipitation in this alloy occurs in two ways: continuous precipitation, which nucleates and grows inside the grains, and discontinuous precipitation, which forms at the grain boundaries. During ageing, the length of the continuous precipitates increases, and, hence, interprecipitate distance decreases. The formation of discontinuous precipitates causes initiation and propagation of cracks at and the weakening of the grain boundaries. This is the principal reason for the reduction of the ultimate tensile strength in T6 heat treatment in comparison to the T4 condition.

Jan 1, 2006

By T. J. Langan, M. Ramajayam, T. Dorin

"6xxx-series Al alloys are the most commonly used alloys in the automotive industry as they have an appropriate balance of strength, corrosion resistance and formability. The main strengthening phase in these alloys is the ß’-Mg2Si precipitates. One opportunity to achieve stronger 6xxx-series Al alloys, without affecting corrosion and formability, is the use of Sc. The main challenge of using Sc in 6xxx-series lies in the heat treatment, which must be designed to allow for a fine precipitation of both Al3Sc and ß’-Mg2Si. In this work, two model alloys are used, an Al-Sc-Zr and an Al-Mg-Si-Cu-Sc-Zr, to explore the impact of the 6xxx-series key elements (Mg, Si and Cu) on the Al3Sc precipitates. Transmission electron microscopy and atom probe tomography are used to investigate the precipitates present in the microstructure after casting. We find that higher Si content results in the formation of dispersoids upon casting. The average composition of these dispersoids is (Al0.8,Si0.2)3 (Sc0.888,Zr0.024,Mg0.08,Cu0.008). A closer look at the solid solution reveals that most of the Sc and Zr is supersaturated after casting even in the presence of Mg, Si and Cu. We discuss the impact of these results on the design of a suitable heat treatment for 6xxx-series alloys with Sc.INTRODUCTION The most common strategy to strengthen aluminum (Al) alloys is by micro-alloying to form a fine distribution of precipitates (Gladman, 1999). Whilst precipitates enhance the strength, this is often done to the detriment of ductility and corrosion performance (Davis, 1999). The 6xxx-series Al alloys are heavily used in the automotive industry as they offer an appropriate balance of strength, ductility and corrosion resistance (W. S. Miller et al., 2000). The strength increment in these alloys comes from the formation of the ß’–Mg2Si and the quaternary Q’ phase (Chakrabarti & Laughlin, 2004; Polmear, St. John, Nie, & Qian, 2017). One opportunity to achieve stronger 6xxx-series alloys, whilst keeping good balance of corrosion resistance and formability, is the use of small additions of scandium (Sc). Sc is one of the most potent strengtheners in Al alloys (Dorin, Ramajayam, Vahid, & Langan, 2018; Røyset & Ryum, 2005). Most of the strengthening benefits from Sc come from the formation of fine Al3Sc dispersoids. The following strengthening mechanisms apply to Sc: 1) Solid solution strengthening, 2) precipitation hardening, 3) inhibiting recrystallization, 4) assisting nucleation of other strengthening phases (Dorin, Ramajayam, Lamb, & Langan, 2017). As compared to other dispersoid phases, Al3Sc dispersoids have good electrochemical compatibility with Al alloys and hence do not affect their corrosion resistance (Cavanaugh, Birbilis, Buchheit, & Bovard, 2007). The coarsening resistance of Al3Sc is often improved by adding zirconium (Zr), as it forms a Zr rich shell around Al3Sc which prevents Sc from moving across the interface."

Jan 1, 2018

By M. Somppi, Z. Yamak

"Gold producers invest significant effort in mining, processing, and creating an intermediate gold doré product. Nonetheless, equal effort should be extended to the final handling and processing of the doré bar, and managing the high-purity gold produced at the fine-gold toll refiner. This detailed attention to bullion handling and refining provides rigor and confidence that the mine site is achieving, through fair and controlled methodology, the most appropriate value for the final product. With the above in mind, the following study explores the importance of preparing a set of site best-practices for bullion handling and specifically, detailing the peculiarities of sampling methodologies and the impact on assays.INTRODUCTION Gold and silver handling practices are common place at mine sites and refineries. The practices include but are not limited to smelting, ingot casting, weighing practices, and secure transportation. Proper handling and processing of the bullion material ensures that the mine site is achieving the true value of the final product. Various handling aspects can critically impact the perceived value of the bullion. A few of these particulars include weight tracking, scale recertification and calibration, refining and melting practices, melt temperature measurement, sampling, pouring, bar cleaning, furnace technology and crucible selection, and assaying. Nevertheless, this report discusses and focuses on the importance of proper sampling and molten-metal temperature measurement and their potential impact on the final doré bar value. Refining or re-melting operations achieve a proper measure of the precious metal content of its bullion when the sample accurately represents the whole bar. At first this task appears seemly straightforward, however, taking a representative sample can be challenging and is also one of the most important tasks for valuing gold during the settlement stage at the precious metal refinery. Various bullion sampling methodologies exist; including: dip sampling, granulation, drilling, cutting, and vacuum pin sampling. The Royal Canadian Mint (2009) indicated in their technical review of refinery operations that pin sampling is one of the best methods for cases where representative sampling and accuracy are required, e.g. to determine the payable metal content. Pin sampling consists of inserting a sealed glass vacuum tube (Figure 1) into the molten metal; when the molten metal contacts a purposely-designed weak portion of the glass, the seal breaks and the metal is suctioned into the hollow centre (Figure 2)."

Jan 1, 2018

By N. A. Beier, N. Slingerland

"Oil sands tailings impoundments rank among the largest (spatially) in the world, covering a total of approximately 220 km2 of northern Alberta, Canada. A preliminary geomorphic design for an oil sands tailings storage facility (TSF) landform was completed with the goal of eventual closure and delicensing in mind. This paper outlines methods identified during the design process that streamline closure when implemented early in the mine planning and TSF design stages. With most oil sands TSFs currently in active operation (and some still in the planning stages), geotechnical engineers and mine planners have the opportunity to make operational and design decisions, such as those outlined herein, that are likely to improve the geotechnical and environmental performance of the landform post closure. ¦ KEYWORDS Alberta, Athabasca oil sands (AOS), Landform design, Reclamation, Sand dam, Tailings storage facility (TSF) RÉSUMÉ Les bassins d’accumulation des résidus issus des sables bitumineux font partie des plus grands (en termes d’espace) au monde, et couvrent au total environ 220 km2 dans le nord de l’Alberta, au Canada. Une conception géomorphologique préliminaire a été réalisée pour le modelé d’une installa¬tion de stockage des résidus (ISR) issus des sables bitumineux en gardant à l’esprit la fermeture et le retrait de permis à terme. Cet article présente les méthodes identifiées pendant le processus de conception qui simplifient la fermeture lorsqu’elles sont mises en oeuvre dès les premières étapes de planification de la mine et de conception de l’ISR. La plupart des ISR issus des sables bitumineux se trouvent dans des exploitations actives (dont certaines en sont encore aux étapes de planification), aussi les ingénieurs géo¬techniques et les planificateurs miniers ont la possibilité de prendre des décisions en termes d’exploita¬tion et de conception, telles que celles présentées ici, qui pourraient améliorer la performance géotechnique et environnementale de la phase suivant la fermeture du modelé. ¦ MOTS CLÉS Alberta, assainissement, barrage de sable, conception du modelé, installation de stockage des résidus (ISR), sables bitumineux de l’Athabasca (SBA)INTRODUCTION The Athabasca oil sands (AOS) underlie 140,200 km2 of land in northeastern Alberta, Canada. Oil sands located within 100 m of the original surface account for 4,800 km2 of the total area and are considered to be economically mineable (Figure 1; ERCB, 2009). Bitumen, the thick, tar-like substance contained in the AOS, is extracted through open-pit mining and in-situ methods. During mining, the overburden is first removed as waste and the sandy, bitumi¬nous ore (“oil sand”) is transported to processing facilities via conveyor belts and 400 t trucks. Warm and hot water, as well as process aides such as caustic soda, are mixed with the oil sand, creating a slurry from which bitumen is mobilized and extracted. The resulting slurry waste product is called “tailings” and contains mineral solids, process water, and small proportions of unrecovered bitumen (Masliyah, Zhou, Xu, Czarnecki, & Hamza, 2004; Sobkowicz & Morgenstern, 2009)."

Jan 1, 2019

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

By Suman Giri

Non-Intrusive Load Monitoring (NILM) is a method of extracting appliance-level power consumption information from aggregate circuit-level data with the goal of giving users feedback regarding their energy consumption so they can take control of their consumption habits. In this paper, we present a novel algorithm for classification of on and off states of appliances. We compare the performance of our algorithm in on state detection with a pervious paper that evaluated the same dataset and show that it performs up to 13% better. We also present the results of a case study where we collected data for different modes of a cooktop, microwave and dishwasher and used our algorithms to perform power estimation. The error on ten different setups in the test bed ranges from 1% to 32%. We discuss our results and lay out ideas for future work.

Aug 1, 2013

By W. Dingley, G. R. Hoey

"AbstractWear of six types of grinding balls was compared with and without corrosion inhibition in grinding Ni-Cu sulphide and hematite ores in laboratory ball mills. Forged steel balls (Rc 60 to 65) and three types of white cast iron balls (Rc 50 to 65) were susceptible to corrosive wear and two types of stainless steel balls [AISI Type 440C (Rc 65) and AISI Type 302 is; 35)] were relatively immune. The relative wear rates of the five types of hard balls (Rc 50 to 65) were dependent on the corrosivity of the ore. Ranking of the hard balls with respect to wear resistance was consistent for the sulphide and hematite ores in the presence of corrosion inhibition, whereas their ranking was different for the two ores in the absence of inhibition.The electrochemical potential of the grinding balls was measured during grinding and was found to be a useful measurement for assessing the susceptibility of an alloy to corrosive wear. Reduction of ball wear for forged steel and white cast irons with corrosion inhibition was concomitant with a shift of ball potential to less active values. Ball potentials in the presence of inhibition were indicative of non-corroding metal surfaces.IntroductionA PREVIOUS STUDY by the authors (1) showed that corrosion inhibitors - sodium nitrite, sodium chromate and sodium metasilicate - reduced wear of forged steel grinding balls by up to 49% in grinding Ni-Cu sulphide ore. Although the mechanism of wear reduction was not elucidated, it was concluded that corrosion must play a significant role in the wear of grinding media. Remark and Wick (2) of Battelle Pacific Northwest Laboratories have also evaluated corrosion inhibitors for the reduction of metal wear using abrasive and n on- abrasive te sting procedures. Their research was sponsored by 16 companies throughout the world. Preliminary results indicated that anodic inhibitors prevent from one-fourth to one-half of the loss due to corrosion."

Jan 1, 1977

By K. S. Raja, B. Pesic, S. Kshetri

"We investigated the electrochemical corrosion behavior of commercial permanent magnetic material (NdFeB alloy) in 0.1 M NaH2PO4 solution (pH:4.75) containing 0 – 1000 ppm of chloride at room temperature (298 K). The material was evaluated in magnetized and demagnetized condition with different surface preparations such as: Ni-Cu-Ni coated, uncoated (bare), and anodized (in fluoride containing ethylene glycol at 60 V for 15 minutes to form a thick nanoporous oxide surface). The nickel coated magnetic sample showed reasonable pitting corrosion resistance up to 100 ppm chloride addition. The uncoated samples showed passivity in chloride free phosphate solution. Chloride additions caused pitting and the pitting protection potential was equal to the corrosion potential with 100 ppm chloride addition. Demagnetization did not alter the electrochemical polarization. However, the passive film formed on the magnetic sample showed higher charge carrier density than the film formed on the demagnetized sample. INTRODUCTIONSintered NdFeB permanent magnets exhibit excellent magnetic properties such as large energy product [(BH)max > 450 kJ/m3], high saturation magnetization (1.6 Tesla), and high coercivity (1.2 – 2.08 x 106 A/m) (Sugimoto, 2011). However, the NdFeB magnets are prone to corrosion attack because of the presence of Nd-rich intermetallic phases, such as Nd4Fe (Jurczyk & Jakubowicz, 2000). Nd-rich and B-rich intermetallic phases are distributed in a matrix of Nd2Fe14B tetragonal ferromagnetic compound in a permanent magnet. Generally, several types of Nd-rich phases are present in the magnet with Fe:Nd ratios ranging from 1:1.2 to 1:7. The volume fractions of Nd-rich and B-rich (Nd1+xFe4B4 type) phases are about 10% and 7% respectively (Li, Ma, Li, & Wang, 2011) . Among these intermetallic phases, Nd-rich phase has the most active electrochemical potential. Therefore, dissolution of this phase occurs in preference to other phases by galvanic corrosion when exposed to moisture. Since Nd-rich phases are present at the grain boundaries of the Nd2Fe14B matrix, corrosion leads to disintegration of the magnet."

Jan 1, 2012