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By W. Zheng

Pipelines can develop stress corrosion cracks in either intergranular or transgranular form. Since the mid-1980s, numerous colonies of transgranular cracks have been found across Canada and many other countries in the world. While the intergranular form of cracking has been well studied in the past 40 years, the mechanisms governing SCC in near-neutral pH environment, i.e., the transgranular form of the cracking, are yet to be understood in greater depth. Over the past ten years or so, a large number of research publications have been available on this subject and this paper summarize our latest progress in understanding the mechanistic aspect of the problem. Better understanding of the role of mill scale surface and the steel metallurgy in crack initiation has been indicated in the recent literature. However, the initiation of SCC in the lab research still relies on loading conditions that are far more aggressive than those encountered in the field. Most crack growth studies in the past are also performed under very aggressive mechanical conditions, which could have prevented the observation of environment effects. However, more recent research at lower K or Delta K ranges seems to suggest a strong role of the environment. Naturally, modeling of growth should reflect the effect of the environment, steel metallurgy, and the changing mechanical properties of the pipe steel with time. For a specific steel in a given environment, the crack growth rates tended to increase with the strain rate, indicated either by the nominal applied loading frequency or by the calculated crack tip opening rate. Future research needs to address the issue of concurrent growth of multiple interacting cracks. More attention should also be given to concurrent initiation of multiple cracks in a colony, as failure is usually caused by a coalesced crack not by an individual crack. The effect of soil environment should not be limited to the chemistry of soil solution; other factors such as cathodic processes, the variation of environment with time and physical conditions of coatings should also be considered as part of the study.

Jan 1, 2005

By A. Roy MacLean

"In the Maritimes, there are twelve coal areas. From east to west, these include the Sydney coal field, the St. Rose - Chimney Corner, Inverness, Mabou, Port Hood, Pictou, Colchester - Debert, Springhill, Joggins - Chignecto, Beersville, Lake Stream, and Minto. The first eight are in Nova Scotia while the remaining four are in New Brunswick.In all these areas, the coal was formed during the Carboniferous period, which existed some 300 million years ago. However, within this period not all coal formation took place during the same time. There were three main intervals, which occurred at the time that the Riversdale, Cumberland and Pictou groups were laid down (Hacquebard, 1970). The oldest coals are those of the Riversdale Group. These coals were of rather limited extent, and only a few mineable seams are present, particularly at St. Rose -Chimney Corner and Port Hood. From these two areas only 2 M tons have been extracted, and 'measured' resources of 7 and 9 M tons respectively remain. The Cumberland Group coals are confined to Cumberland County and include the coals of Springhill and Joggins River Herbert -Chignecto. Some 43 M tons have been removed and only 7 M tons of 'measured' coal remain, with an addit10nal 39 M tons of 'inferred' resources. However, there are additional resources at Springhill, which will be discussed in more detail in a later section. The coals of the Pictou Group are the youngest and the most abundant, both in actual number of seams and in regional distnbution. These coals were formed during the Westphalian C and D, a time during which the main coal deposition in Europe also took place. Here belong the coals of the Sydney, Inverness, Mabou, Pictou, Debert, Beersville, Lake Stream and Minto fields. Their total production amounted to 469 M tons or 91 % of the Maritime total of 514 M tons. The remaining resources of all Pictou Group coals have been calculated at 254 M tons of 'measured' coal and 949 M tons of 'inferred' coal. As can readily be seen, the bulk of both past production and remaining resources occur in the Sydney coal field. The Sydney figures represent 73% of total production, and 87% of total 'demonstrated' resources in the Maritime Provinces. Next to Sydney, the Pictou coal field has been the greatest producer, with 59 M tons; it also has the second largest 'measured' resources, amounting to 25 M tons. However in terms of 'inferred' coal resources, the Mabou coal field, ~ith 140 M tons, ranks second to Sydney."

Jan 1, 1985

By W. J. Kuit

Since closure in 1968, the Wedge Mine, situated adjacent to the Nepisiguit River in New Brunswick, has been flooding with acidic water containing toxic levels of heavy metals. Cominco Ltd. has undertaken a series of pollution control measures to mitigate the threat posed to the river quality. Included has been a successful treatment campaign in 1976 which discharged in excess of 30 million gallons of high-quality effluent from the accumulated volume of mine water. The sources of contamination have been identified as actively leaching waste dumps. A comprehensive program of permanent corrective measures has been prepared which will culminate in mine backfilling. Once completed, the unacceptable burden of water treatment in perpetuity at a non-producing property will be removed.

Jan 1, 1977

By L. E. Puddington, A. L. Mular

"Since the inception of spherical agglomeration, few investigations to exploit commercially the technique in the metallurgical field have been conducted. Of these, none appear to have been carried sufficiently far to demonstrate commercial feasibility.This paper describes a continuous agglomeration-separation process that can rapidly handle large tonnages of ore material. A small pilot plant de-signed from information obtained with the semi-batch unit described herein is currently in operation.In the absence of a reagent recovery system or cheap reagents, the process is probably not economically attractive for many common ores. However, for iron ores, the fuel content of the agglomerates can be used in a subsequent step such as direct reduction."

Jan 1, 1968

By Ernest Davis

WATER power, until developed, produces nothing, but when harnessed it continues to produce, it might be said, indefinitely. Hence the importance of developing all feasible water powers. British Columbia, like the western states of America, is subject to variable meteorological conditions which cause most streams to be erratic in their flow. The wet season, usually commencing in October and continuing to March or April, together with the melting of the snows during the early summer, produces a heavy run-off which diminishes considerably during the later s1.1,mmer months, with the result that storage is essential on practically every stream in order to regulate the flow to obtain a discharge which will meet the requirements of the load of the markets the power is to serve. Storage sites of sufficient capacity to equate the flows are not always present and it follows that, where such a deficiency exists, the difference must usually be met by burning fuel in steam plants. Fortunately, there are within the Province deposits of high-grade coal, suitable for the operation of such auxiliary steam plants. One of the strongest reasons for the development of water powers is the conservation of fuel. All use of coal or oil depletes resources that can never be renewed. Every water power developed means a saving in fuel and, even if at first it does not possess an over-powering financial advantage, it must become of ever increasing value as fuel resources become depleted. However, sight must not be lost of the inter-relation which should exist between the two methods of generating electrical energy, as each makes an admirable supplement to the? other with respect to suitability for carrying different types of load. In general, it can be said that the fixed charges of a water power development are usually high in relation to the operation costs, while those of fuel power plants are usually the reverse, so it is sometimes possible to combine the two methods of generation for the more efficient production of energy.

Jan 1, 1942

By M. Melashvili

"The SART Process was introduced to the gold mining industry in the late 1990s and several commercial plants were built over the following 10 to 15 years. Most of these plants have operated well and enjoyed plant performance in line with expectations based on the underlying chemistry of the process. However, two of the plants have consistently suffered from high reagent consumption and poor product quality, which has motivated a re-examination of the process fundamentals.The primary product in the SART Process is synthetic chalcocite, Cu2S, and the stoichiometric requirement for sulphide addition is therefore 0.5 moles per mole of copper in solution. It is shown here that when sulphide is added in excess of this amount (generally with the express purpose of lowering residual copper in solution) it not only fails in its intended purpose, but can have a negative impact on the settling and filtration characteristics of the copper sulphide product, as well as the final product quality. Moreover, these problems are exacerbated the higher the selected operating pH in the pH 3 to 5 range, and the longer the residence time of slurry in this pH range.Freshly precipitated copper sulphide compounds are known to be very fine and slimy, with poor settling and filtration characteristics. It is therefore important to engineer the SART Process in such a way as to encourage growth in the average particle size of the precipitate crystals. This was the rationale for recycling a portion of the thickener underflow to the primary reactor when the SART Process was developed. However, the theory of crystallization predicts that compounds of extremely low solubility, such as chalcocite (Cu2S: KSP = 10-48), are unlikely to experience growth in crystal particle size through heterogeneous nucleation and are more likely to grow through aggregation. On this basis, the SART practice of recycling a portion of thickener underflow to the primary reactor in the commercial plants is unlikely to lead to crystal growth via nucleation, and could in fact promote breakage of the aggregates that formed in the thickener. Recycling thickener underflow could therefore have the opposite of the desired outcome. The result of testwork that is reported here lends credence to this theory and questions the wisdom of recycling in the SART process."

Jan 1, 2016

By Edward Sampson

Bases of National Power At a time when the economy of the world is in a particularly troubled state it is appropriate to examine some problems of the distribution of natural resources. I should like particularly to call attention to the remarkable increasing demand for natural resources, to give an analysis of the demand for certain mineral resources, and to direct attention to some problems in satisfying this demand. All industrial power is based on natural resources and the most basic of these are soils, energy resources, and mineral resources. There is a strong interrelation of these resources, more than is obvious, and I shall take up certain aspects from the point of view of a geologist. Few nations are well endowed with all three of the kinds of natural resources I have mentioned and much has been done by some small countries whose peoples are industrious and enterprising and where conditions for free world trade have been favourable. However, major industrial power is dependent on a substantial endowment of all three classes.

Jan 1, 1949

By R. T. Jones

"Technical publications in the field of mining and metallurgy have existed for a long time. Recent developments in electronic publishing on websites make it possible to disseminate information more widely and cost effectively than before. Professional societies have an opportunity to serve their members and their industry by publishing high-quality peer-reviewed papers on their websites as well as in printed form. Older publications can be scanned, and optical character recognition can be used to provide searchable text. Various business models exist around this process. This paper outlines the approach used by the Southern African Institute of Mining and Metallurgy (SAIMM) to provide free open access to their journal papers and conference proceedings, as well as the work being done by OneMine.org to collect technical papers from a number of international societies and make them available to subscribers via a large database. An approach is outlined that should be of benefit to authors, readers, and society at large.INTRODUCTIONGeorgius Agricola (1494-1555) was not the first writer on the subjects of mining and metallurgy, but is well known as the author of De Re Metallica (‘of things metallic’ or ‘on the nature of metals’), a book that documents and illustrates the observations he made in the course of his extensive travels in the 1500s. Agricola wrote extensively about mining methods and metallurgical processes that were in place in the Middle Ages. The original Latin version of De Re Metallica was published in 1556, the year after Agricola died. It was translated into English by Herbert Hoover, a mining engineer and later President of the United States, and his wife Lou Henry Hoover, a geologist and classicist. The English version of De Re Metallica was published in 1912."

Jan 1, 2012

By George Brien, O&apos

The history of the lighting of mine workings dates back to the early part of the 18th century, when small candles known as tallow dips, were used. These were set or held in a lump of wet clay. When looking for gas the flame of. the candle was reduced to a mere glimmer by surrounding the wick below the flame with clay. The candle was then very cautiously raised from the floor toward the roof, the observer screening the brighter portion of the flame with his hand and watching for the first appearance of the pale blue cap above the flame, even at that time, known to indicate the presence of gas. When this appeared the candle was lowered quietly and its flame extinguished before attempting to drive out the gas. A very common and dangerous practice adopted at that time was to get rid of the gas by firing it. This was done by a person selected for his nerve rather than for his caution. Dressed in a? suit of dampened sackcloth or leather, this man well termed a "fireman", would lie prone on the floor of the roadway and light the gas above him by raising his candle fastened to the end of a long stick. If he survived, which was not always the case, he would withdraw promptly to fresh air after the flame had passed over him.

Jan 1, 1924

By F. G. Vetsch, F. A. Ronaghan

"Introduction1N THE FALL of 1951, Peace River Allied Fort St. John No. 1 well was drilled in Lsd. 1, Section 9 Township 83, Range 18, West of the 6th Meridian, on the flats of the north side of Peace river, six miles southeast of the village of Fort St. John, B.C. During this operation, non-commercial shows gas in three zones and of oil in one zone were obtained during the drill-stem tests. Further geological study indicated that this well was on the southeastern edge of the Fort St. St. John structure.Pacific Fort St. John No. 4, drilled shortly afterwards, obtained possible commercial gas flows on drill-stem test in five zones and thus encouraged development of what has become Canada's largest multizone gas field.In general, the productive horizons in this area possess fair per-meabilities and high porosities, a combination which provides for high reserves and moderate productivities. Development to date has therefore stressed experimental techniques in drilling and completion practice to provide high deliverability wells.Data and information of a specific nature apply, in all cases, to the pools in the Fort St. John structure."

Jan 1, 1954

By K. G. Chipman

THE discussion on Dr. Chipman's paper, Mapping by the Topographical Survey, centred mainly on the urgent need for aerial photographic reconnaissance of unmapped portions of the country as an initial phase in the provision of suitable topographical maps for use as a guide in geological mapping, prospecting, exploration, and development work in the areas concerned. This, ir was pointed out, would necessitate an expansion of the topographical work of the Bureau of Topography to keep pace with the photographid work and to meet the demand for maps for use by geologists of the Bureau of Geology and others. A resolution requesting Institute Council to make representations to the proper authorities, urging that aerial photography and topographic map-ping be greatly expanded to meet the pressing needs of the situation, was moved by DR. W. F. JAMES and seconded by MR. L. G. SMITH, and carried unanimously. The full text of the resolution appeared on page 221 of the May BULLETIN. Others who spoke in support of the resolution were MESSRS. E. S. MOORE, L. B. ROCHESTER, F. D. SHEPHERD, and W. J. WRIGHT. Dr. Hansen then presented his paper, Mapping by the Geological Survey, discussion on which is summarized below. MR. FRANK EBBUTT(l) spoke of the very valuable service the Geological Survey bas rendered the mineral industry, and indeed the whole nation, in its century of existence, despite the very inadequate financial support it has received. Now, more than ever before, a strong and expanded Geological Survey is essential if the Industry is to continue to prosper. Our known ore reserves are being depleted very rapidly, and we are finding no new orebodies to take their place. As an aid in prospecting and exploration, and also in the development of orebodies when they have been found, we must have geological maps of the vast sections of the country which at present are unmapped or inadequately mapped. The Institute should make every endeavour to have the Geological Survey strengthened so that such maps may be made available as soon as possible.

Jan 1, 1944

By D. C. Fraser

Copper occurs invisibly in a geo-logical environment characterized by swampy conditions and an accumulation of forest peat. This swamp, located in southeastern New Brunswick, contains up to ten per cent cop-per (dry weight), in the organic sediments. This occurrence appears unique in that the metal is apparently organically combined in a chelate compound. Unlike the acidic nature of most peat bogs, the pH of the cup-riferous peat is nearly neutral. Analyses of the peat and associated soils have indicated that the bulk of the copper is contained in the organic sediments. It appears that the cop-per distribution is affected by capillarity, evaporation and the growth of frost crystals, and that the copper fixation is effected by organic sequestration resulting in the metal being bound to the nitrogen or oxygen components of the forest peat. While such a fixation mechanism is not definitely established as responsible for the immobilization of the metal, the facts at hand are compatible with

Jan 1, 1961

By S. G. Hardcastle

The effects of air velocity in promoting cooling through the evaporation of sweat generated when working at a high metabolic rate and/or in hot environments is well known. Many of the environmental heat stress indices consider the effect of air movement directly or indirectly within their determination, be it through the use of a specific instrument i.e. a wet-bulb globe temperature meter or Kata thermometer, or inclusion of in the calculation of a stress index, including the effective temperature, air cooling power, thermal working limit, ISO 7933?s predicted heat strain model. Within these models, ambient air temperature, relative humidity and barometric pressure are also considered in varying degrees to quantify an airstream?s capacity to evaporate sweat. Deep mine studies have shown cumulative increases in heat exhaustion rates with both decreasing air velocity and decreasing air cooling powers. However, despite a capacity to cool, the resultant cooling is very dependant on sweat production and its availability for evaporation; these are included where sweat rates and skin wettedness are considered. The first depends on hydration and physiological factors whereas the second is more an engineering factor related to the degree of clothing required. As sweat rates deteriorate with aging, the benefits of evaporative cooling potential can similarly be expected to be diminished. This paper continues to report upon on-going physiological studies exploring the potential for heat stress in deep underground mines through the simulation of mining activities in environmental chambers and a human calorimeter facility. The focus of this paper is to introduce preliminary data suggesting that increasing air velocity (0.5, 1.5 & 3.0 m/s) is beneficial for young subjects (22 ± 1 yrs), as indicated by lower core and skin temperature measures and heart rate during an intermittent work protocol, and then show a lesser benefit for older subjects (62 ± 2 yrs). Both subject groups performed the same task under the same environmental condition (35°C, 60% RH) wearing a standard mining ensemble. The study similar to others being performed under the Deep Mining Research Consortium funded research continues to provide evidence that a greater understanding of heat management processes is required and that worker education is critical as environmental measures and health and safety regulations may not be expected to include all demographic factors such as age, sex and health which are known to affect human thermoregulatory response.

Aug 1, 2013

By I. Demers

The abandoned Manitou mine site covers an area of approximately 190 ha near Val d?Or, Quebec. This old site has been generating acid mine drainage for several decades. In 2006, a partnership was established between the Quebec Ministry of Ressources Naturelles (MRN) and Agnico-Eagle Mines to reclaim the Manitou site using tailings from the nearby Goldex mine. These neutral tailings were to be deposited on top of the Manitou site. An extensive study was performed to evaluate specific reclamation scenarios to control acid mine drainage using Goldex tailings as cover material. The article first describes the global approach used for this evaluation, which includes in-situ hydrogeological monitoring, tailings characterization, laboratory column tests, and numerical modelling. Of the thirteen column tests, three were conducted to evaluate the parameters affecting the performance of covers made of Goldex tailings placed over the spillage area of the Manitou site. Geochemical and hydrogeological parameters were assessed during the leaching column tests for almost two years. The tests aimed at evaluating the effect of water table level and monolayer cover thickness on the overall performance. The testing procedure involved monthly leaching and measurement of geochemical parameters. Results indicate that water table position is the most important factor affecting the monolayer cover performance to control AMD. Based on these results, it was established that the water table must be located near the interface between the Goldex and Manitou tailings to effectively reduce AMD generation. Cover thickness also has an impact on cover performance, which is however less significant than the water table position. The testing scenario with a water table located at the interface with a one-meter Goldex tailings cover showed progressive improvement in effluent quality.

Aug 1, 2013

By Jean Scott, G. A. Collins, G. W. Hodgson

WHILE it is well known that trace metals in crude •oils and distillates have been a matter of deep concern to refining engineers because of the damage done .by the metals to cracking catalysts and refractories (8, 5), the trace metals in crude oils may be of great benefit in correlation studies and in origin studies. During the geological processes in which the oil is formed from •animal and vegetable life, the hydrocarbons are subjected to a host of inter-related reactions, both physical and chemical. It has been well demonstrated that the lighter materials, certainly the short-chain paraffin hydrocarbons, are degradation products of the heavier molecules, and it might be concluded that for correlation studies it would be advisable to direct attention as much as possible not to the degradation products of the large molecules but to the large molecules themselves. Be this as it may, the methods at •hand to conduct the study are not particularly precise and, in the past, attention has centred on the simpler small molecules, as evidenced by the great mass of work involving distillation and chromatography with painstaking separation of the simpler 'front-end' hydrocarbons.

Jan 1, 1954

By Lars A. Bergstrom

High-voltage direct -current transmission is a relatively new technology. The successful development and operation of AC/DC converters, capable of handling large power blocks, have made HVDC transmission generally accepted by utility engineer s and planners around the world. HVDC technology still has significant development potential and, as a result, it is expected that equipment costs will escalate at a substantially slower rate than those of conventional AC equipment. This development will also result in still more compact terminal stations. This paper reviews two modern HVDC installations. In Zaire in Africa. a 1700-km overhead DC line rated at 500 kv, will supply power to the copper mining district in the Shaba region. Another HVDC link connects Norway and Denmark through a submarine cable rated at 250 kv. This is the longest HVDC cable in the world, 127 km, and the water depth , maximum 530 m, is also much greater than for any previous similar cable. The reasons for selecting HVDC are discussed, and the design and layouts are presented.

Jan 1, 1978

By Trang T. Tran-Valade

With continually increasing energy prices, the mining industry has been on the search for new energy optimization technologies. One area that is garnering great interest is Ventilation-On-Demand (VOD). Prior to selection and implementation of a VOD solution, it is important to fully understand the mine requirements as well as its existing infrastructure and the interaction with other automation in place at the site. With this information, a business case can be generated including a cost versus benefit comparison for various control strategies. To assist in the development of the business case, this paper will identify key areas for consideration and recommendations for an implementation plan.

May 1, 2013

By P. Mpofu

In this work, the modification of interfacial chemistry of colloidally stable kaolinite clay dispersion has been carried out to improve its flocculation performance and dewatering behaviour. Synergistic action between dispersion pH, hydrolyzable metal ion and high molecular weight polymeric flocculant structure type (anionic polyacrylamide-acrylate copolymer (PAM) and non-ionic polyethylene oxide (PEO)) was found to play a pivotal role in inter-particle bridging, the enhancement of the settling rate and extent of consolidation of the pulps. Flocculation with PEO led to higher settlings rates in acidic than alkaline pH, whilst for PAM, the maximum dewatering rate was achieved in the neutral pH range 6 - 7.5. Upon shear, the PEO flocculated pulps showed dramatic improvement in consolidation to 40 wt%, the extent of which was greater at lower than high pH values. For PAM-based pulps were however, not shear-responsive, lower sediment solid contents of 15 - 23 wt% was observed between pH 3 and 11. Hydrolysable metal ions, Mn(II) and Ca(II), used respectively at pH 7.5 and 10.5 in conjunction with PAM and PEO, significantly enhanced the settling rates and consolidation of the pulps. The findings exemplify the strong links existing between pH-mediated particle surface chemistry. polymer structure-conformation, inter-particle bridging and dewaterability of kaolinite dispersions.

Jan 1, 2004

By Antonio Segatori, Bjørn Holmedal, Kai Zhang, Trond Aukrust, Knut Marthinsen

"The visual appearance and mechanical properties of aluminium alloy extrusions are strongly dependent on the microstructure and texture of the extruded profiles, where the desired microstructure and texture may depend on the specific applications. In the present work, the evolution of deformation, as well as recrystallization textures during extrusion of AA6xxx aluminium alloys, have been experimentally and numerically investigated. Extrusion trials were performed in a laboratory extrusion set-up, which enabled immediate water-quenching of the profiles at the exit of the die, and thus the possibility to capture the deformation texture prior to post-extrusion recrystallization. The textures and their through-thickness variations were experimentally measured by the electron back-scatter diffraction technique (EBSD, and the deformation textures numerically modelled by coupling FEM flow simulations and crystal plasticity (CP) simulations. Different CP models as well as different choices of model parameters were employed and evaluated for texture predictions. With an appropriate choice of crystal plasticity model and model parameters, the deformation texture can mainly be predicted, although the accurate intensities are hard to reproduce. The corresponding recrystallization textures, either generated through spontaneous recrystallization of the extruded profiles or through post-extrusion annealing, are far more challenging to reproduce with available recrystallization models.INTRODUCTION Extrusion is a widely applied thermal-mechanical process to produce aluminium profiles. The properties of the profiles, for example mechanical, fatigue, fracture, corrosion as well surface appearance, are strongly dependent on the underlying microstructure and texture, and the requirements with respect to these aspects may vary with applications (Ralston et al., 2010; Dumoulin et al., 2012; Donati et al., 2013). Moreover, it is often a challenge to produce extrusions with a consistent and homogenous grain structure and texture along as well as through the cross section of the profiles. It is thus vital to understand and be able to predict (model) how different microstructures and textures are formed and how they evolve during and after extrusion, as basis for controlling the final appearance and properties of extruded profiles."

Jan 1, 2018

By D. F. Zhang, X. Q. Jiang, N. Tahreen, D. L. Chen, F. S. Pan, D. Y. Li

Alloying with rare-earth elements has been proven to be an important tool for magnesium to achieve superior properties via texture randomization. The role of yttrium in texture weakening and the link between texture and formability are fairly well known. Since annealing is a vital part of metal processing which could significantly contribute to ductility, it is important to ascertain the impact of annealing in terms of texture change. Also, an understanding about texture development during pre- and post-deformation annealing is essential to improve the industrial deformation processing as texture is closely related to formability. While there is independent information in the literature regarding the effect of rare-earth addition and heat treatment on the texture formation, no systematic studies have been reported on the collective impact of yttrium addition, annealing and deformation on texture evolution. The present study was, therefore, aimed to identify the inter-relationship among texture evolution, yttrium content, heat treatment and deformation behavior in an extruded Mg-Zn-Mn-Y alloy. Annealing at 450°C for 1 hour and uniaxial compression tests at a certain amount of deformation were performed. The deformed and annealed samples were then subjected to annealing and compression test, respectively, followed by texture measurements. It was observed that yttrium addition effectively weakened the crystallographic texture in all conditions, which was evident from the changes in the microstructures and textures.

Jan 1, 2015