Search Documents

By Jean-François Dorion

In an underground mine rock reinforcement elements and surface support units are often exposed to conditions that make them susceptible to corrosion. These unfavourable conditions include high relative humidity, the presence of dust and various other particles in the atmosphere, splashing of water and gases from blasting and diesel equipment. The corrosion of support systems is often associated with a loss in capacity that can be a major safety and economic concern in underground mines. A support system is composed of several components such as bolts, mesh, plate, retaining nut, cable ties. Every individual component can deteriorate due to atmospheric or aqueous corrosion and consequently can damage the integrity of the support system. This paper reports the results of a 5-yr study on the loss in capacity of individual support and reinforcement components at selected underground hard rock mines. As part of this investigation corrosion coupons were installed at selected locations at participating mines. A number of these coupons were recovered at regular time intervals and analysed for any signs of corrosion and subsequently tested to quantify any loss in capacity. The testing of the corrosion coupons was complemented by similar tests on recovered mesh and friction bolt specimens from the site. The collected data have provided useful insights on the factors that contribute to the corrosion of support systems. This knowledge can aid in the selection of appropriate support strategies and a reliable assessment of the predicted useful life of a support system and the need for rehabilitation.

Jun 1, 2012

By D. Doyle, T. Cienski

"This paper presents and discusses the results of a detailed study conducted on the subject of energy consumption in the comminution of industrial minerals. The study was based on pilot circuit testing, plant operating data collection, detailed equipment data and literature research. The areas covered by investigations include: high efficiency classification; air classifiers for cement grinding circuits; grinding aids in dry grinding; and dry grinding circuit control based on particle size measurement. Results obtained indicate a large potential for the reduction of energy consumption, in particular in the cement clinker grinding circuits. Better classification techniques and correct application of grinding additives can significantly reduce power used per tonne of product and also substantially increase grinding circuit output."

Jan 1, 1992

By Brian C. Maynard

"Blast design is becoming more and more important as industrial limitations change in regard to economical and physical restraints. Certainly there are ways to alter the nature of the blast by using different explosives, various hole sizes and modifying the timing and charging details. However, it is not possible to alter the fabric of the rock mass. Therefore, it is necessary to learn more about the rock mass and its role in the blast design, and the resulting fragmentation. The major determinant in the degree of fragmentation, or lack of it, is proposed to be the inherent fragmentation of the in situ rock mass. A practical method of quantifying the discontinuities existing in the rock mass is presented and discussed. Likewise, the effects of inherent fragmentation on the resulting muckpile are reviewed. Finally, a fragmentation model combining the calculated inherent fragmentation and the Kuzram model is shown using a sample blast.IntroductionIn blasting, discontinuity characteristics (Fig. 1) control the method by which the rock mass will behave. Research carried out by Piteau (1970) showed a number of characteristics important in engineering design and, as proposed, in blasting processess. These included:• the nature of their occurrence (i.e. sets or isolated);• orientation and position in space;• continuity; and• intensity"

Jan 1, 1990

By J. E. Nesset

"As an alternative to conventional dewatering by vacuum filtration and oil-fired rotary dryers, Brunswick Mining conducted extensive pilot-scale testwork on its copper, lead, zinc and bulk concentrates using a Larox Oy (Finland) automatic pressure filter. The results showed that pressure filtration readily produced final cake moistures of 6-8.5 per cent on this very fine sulphide material.An in-depth analysis examines pressure filtration in terms of metallurgical performance and projects energy savings of 78 per cent for pressure filters over the current dewatering operation. Potential energy and operating cost reductions are also estimated.IntroductionVacuum filters followed by oil-fired rotary dryers are one of the most common means of dewatering mineral concentrates. They represent, however, a level of technology which is exceedingly wasteful in terms of manpower, space utilization equipment and fossil fuel dependence. In addition, the use of thermal dryers is leading to increased environmental concerns both in plant and out.These were the primary factors which prompted Brunswick Mining to consider alternative dewatering methods as the existing equipment came up for replacement and upgrading. In late 1979, company engineers were encouraged by automatic Larox pressure filters seen at several Scandinavian operations. Subsequent laboratory tests by the manufacturer (Larox Oy of Finland) on several concentrate samples were sufficiently promising for Brunswick and Noranda to lease a trailer mounted filter-lab unit and a technician from Larox for a five-week period. Extensive on-site testwork on all four Brunswick concentrates (zinc, lead, copper and 'bulk' lead-zinc) confirmed the potential of pressure filtration."

Jan 1, 1982

By G. R. Heffernan

"In the early 1970ssteelmakers worldwide were looking forward to many years of expansion and profitability. Huge government investments in Europe, the United Kingdom, Japan, Brazil, and Venezuela were committed in anticipation of growing market s based on long-term OECD forecasts. In 1973 the first OPEC oil shock occurred. Steel demand shrank. Restructuring became the buzz word of the day as billions of dollars in taxpayers' money was poured into eliminating excess capacity and labour. In the United States, where government help was not available, inefficient companies went bankrupt; capacity was cut to 100 million tons from 155 million tons. The industry throughout the industrialized world shrank. By 1979the world economy seemed back on track and a modest degree of optimism could be detected in the international steel fraternity. Then came the second oil shock. By 1982 the industry was in the midst of another shakeout. More bankruptcies, more rationalization, and fewer jobs resulted. In Canada some well-known companies came close to the brink as low prices and high interest rates took their toll. In the light of the turmoil in the steel market over the past 20 years an attempt to forecast the trends through to 2001 is intimidating.However, there are good reasons to be optimistic today about both markets and technology.An economic super power is emerging in western Europe as 1992 draws near. The creation of a single market of 320 million well educated and economically ambitious people has major positive implications for steel demand. The mega projects of the channel tunnel, a European network of high speed railways, and the London docklands are the forerunners of greater things. Still to come is another $200 to $300 billion by the year 2001 in identifiable major projects for highways, railways, airports, water and sewage systems. Add to that the demands of an increasingly affluent population for automobiles, appliances and housing. On top of all that place large increasing demands for electric power and you have a potential beyond anything seen during the 1970s and 1980s. In 1988 the EEC steel industry operated at 90% and in 1989 at 92% of effective capacity. A surge in spot prices indicated that 92% was close to the ceiling. This pace moderated in early 1990 but any slack will probably be taken up rather quickly."

Jan 1, 1990

By M. A. EI Zeky, A. E. El-Nikbaily, M. A. Shahin

"Possible mechanisms of microsilica dust formation and factors affecting its quantity have been discussed. General mathematical models to predict the dust quantity based on electrical and coke consumptions, and flue gas temperature as functions of silicon recovery in the process and silicon content of the alloy have been established. It has also been shown that the flue gas temperature can be used as an additional process control parameter. Comments are made on the effect of the dust formation on the whole process economics and it is pointed out that the formed microsilica dust is a valuable by-product and not an industrial waste. INTRODUCTIONFerrosilicon is produced in electric arc furnaces with submerged electrodes. The charge mixture consist s mainly of quartzite, coke as the reducing agent and iron chips. The products are ferro silicon and carbon monoxide, various other volatile materials, water vapour and silicon monoxide gas. Carbon monoxide and silicon monoxide oxidize at the charge surface when mixed with air entering through the furnace hood openings. The off-gas contains a considerable amount of dust, which is mainly very fine particles of silica formed as a result of oxidation. The emission of dust containing gases to the atmosphere causes serious pollution problems to the environment. Therefore, the control of the formation of the dust, preventing it from escaping to the atmosphere, and dealing with this very fine dust collected from the flue gases represent important technological and economical parameters in the ferrosilicon production industry.This paper is concerned with the relations between the quantity of formed micro silica dust, as a function of both silicon recovery and silicon content in the alloy, and various other technological parameters; and their possible effects on the energy consumption and economics of the whole process."

Jan 1, 1989

By D. Pearcey, S. T. Vessey, V. Hegde, J. Staples

"Pellet quality has taken on a new dimension during the last ten years. Quality in the seventies was generally defined as adherence to certain physical and chemical specifications. Today, the talk is in terms of how the business is managed, how customer's expectations can be exceeded, not only in product quality, but in service responsiveness.Coke breeze and flux additions, lower silica levels, and improved furnace control practices have all contributed to the improvement of pellet physical and metallurgical properties. Statistical process control has provided additional insight into the parameters that affect pellet quality.Increased customer contact and product quality surveys have heightened our awareness of customer needs and also provide direction for quality improvement test work. Current work is focussed on improving reducibility and understanding the relationship between tumble, fired compression and metallurgical properties.This paper will review the Iron Ore Company of Canada's efforts during the past decade and describe some of its initiatives for the future.IntroductionThe Carol Pellet PlantThe Iron Ore Company of Canada's Carol Project is located in Labrador City in the southwestern portion of Newfoundland and Labrador , approximately 965 Ian northeast of Montreal. The project consists of mining facilities, beneficiation complex and a pellet plant, which began operations in 1962. The pellet plant consists of six Dravo-Lurgi straight grate machines, regrinding, filtering and balling facilities. The current capacity of the Carol pellet plant is approximately 10.5 million tonnes , while the concentrator has the capacity to produce about 18 million tonnes of concentrate.The orebody consists of specular hematite, magnetite and small quantities of limonite and goethite. The average grade of the orebody is approximately 39% iron."

Jan 1, 1991

By J. Bigu, M. G. Grenier, S. Hardcastle

"This study was undertaken in a belt conveyor drift of an underground hard rock mine. The conveyor transported ore or waste from a crushing operation located upwind from the drift sampling locations. A 250 m section of this drift was selected and several types of measurements were taken. Average respirable concentrations in the drift were 0.43 mg/m3 and 0.19 mg/m3 for total and silica dust, respectively. From the respirable dust concentration profile along the drift, it may be possible to estimate the contribution from extended sources such as dust produced by the belt and return idlers.The airborne dust in the drift had an average mass-median aerodynamic diameter of 4.2 micron. A continuous dust monitor showed that the crushing operation produced fairly high dust concentrations (sometimes greater than 4 mg/m3) over short periods of time.IntroductionAirborne dust in the respirable range is known to be the cause of various forms of lung ailments . In underground mines, respirable dust sources are created at many stages of production. All mining operators are responsible for de signing and establishing means of reducing airborne dust. In some cases, sources of dust are well defined and suppression methods are standard.In the case of interest here, the airborne dust cloud was formed from the contribution from many sources, which may be either discrete or extended. At the experimental site, the discrete or point sources were the crushing operation and the belt conveyor transfer point (tail pulley). These sources may be controlled by proper dust capture and scrubbing systems as well as dilution ventilation. Examples of extended dust sources in the area include dust produced by the re-entrainment of settled particles along the drift. Ventilation air movement and vehicular traffic both contribute to this phenomenon. Dust produced by the conveyor is another example of an extended dust source. Caked deposits on the return strand and idlers as well as the transportation of dry material on the belt, can be major contributors. Proper wetting of roadways and muck as well as proper belt cleaning techniques can help reduce these emissions. The cleaning apparatus, used on the belt where these experiments were conducted, is shown in Figure I. These and other belt cleaning techniques are described in more detail elsewhere."

Jan 1, 1987

By W. Petruk, D. R. Morris

"The lead concentrate produced from the volcanogenic base metal ore of Brunswick Mining and Smelting in New Brunswick contains major to trace amounts of iron, zinc, cadmium, arsenic, antimony, copper, silver, selenium, tellurium, bismuth, sulphur, tin, indium, mercury and manganese as impurities. When the concentrate is sintered some of these impurities enter a variety of oxide phases, whereas others precipitate as metals. In the lead blast furnace the oxide phases decompose and the impurities recombine 10 form new phases, most are eventually discharged to the slag. The metals of the sinter remain as metals in the lead blast furnace where even more are produced, and are discharged largely with the lead bullion,IntroductionMany lead concentrates are produced from volcanogenic base metal ores . Such ores contain a wide variety of trace minerals and trace elements , therefore, concentrate s obtained from them will contain the trace elements as impurities . The impurities in the lead concentrate from one such ore, the Brunswick No. 12 deposit of Brunswick Mining and Smelting Corporation (BM S) in the Bathurst area in New Brunswick , were studied as pan of a larger investigation that was conducted to determine the extent of chemical reactions of the sinter within the lead blast furnace(1,2) The lead concentrate was investigated to identify the host mineral s for the impurities, the lead sinter was studied to identify the host phases, and frozen products from different depths within the BMS blast furnace at Belledune, New Brunswick were studied to determine the behaviour of the impurities.T he investigation was performed by pre pa ring polished sections o f the samples and studying them with a reflecting microscope, a scanning electron microscope (SE M) equipped with a Kevex energy dispersive X-ra y analysis system, a microprobe, and a Quantimet 720 image analyzer. The samples were also analyzed by X-ray diffractometer, and individual grains were analyzed by the Debye-Scherrer X-ray powder film method."

Jan 1, 1985

By J. S. Roper

"IntroductionSNOW LAKE is situated in northern Manitoba at latitude 54° 55 and longitude 100°, 400 miles northwesterly of Winnipeg, 80 miles northeast of The Pas, 80 miles east of Flin Flon. A 38-mile road from Wekusko, on the Hudson's Bay railway, serves the community.The mine is located in and close to the southern edge of the Precambrian Shield in typical low-relief muskeg and lake country.The Howe Sound Exploration Company, Limited optioned the property from Nor Acme Gold Mines, Limited, after preliminary diamond drilling had outlined two orebodies of low-grade arsenical gold ore.Following the examination and study of geological data and of 50,000 feet of diamond-drill core, and metallurgical tests made during 1942 to 1945, a decision was made to develop the mine and build a 2 ,000-ton mill concurrently. This development has been described by G. C. Lipsey in a paper entitled The Development of a Mining Operation from Diamond-Drill Data which was published in the August. 1952, issue of Mining Engineering.Geological Features of the OrebodiesThe orebodies at Snow Lake occur in volcanic rocks of acid to basic composition and, to a lesser extent, in intrusive hornblendite. The hornblendite is a massive, uniform, .coarse-textured rock except in the immediate vicinity of the ore zone, where it becomes sheared and carbonatized. The acid volcanics have been converted to quartz-garnet-biotite gneiss, and the basic volcanics to amphibolite gneiss. Orebodies have been formed by the replacement of all three rock types."

Jan 1, 1955

By M. Roy, Y. Roux, R. McIvor

"La Compagnie Minière Québec Cartier at Port Cartier. Quebec, utilizes six parallel wet grinding open circuit ball mills to grind iron ore concentrate for the pellet making process. In an attempt to improve grinding efficiency, a mix of 605 25 mm (1 in.) and 405 38 mm (1 ½ in.) grinding balls was charged to mill D while the opposite mix was used in all the other mills. Because media costs were higher for mill D, it was necessary to find out if the smaller balls provided a net economic benefit. Therefore, a test program was undertaken to determine the relative efficiency of the charge in mill D compared to the other grinding mills. Mill F was chosen for comparative efficiency measurements.The first problem was to choose a suitable definition of grinding efficiency. In management's view, previous attempts to quantify milling performance using population balance modelling were ineffective because they were unable to relate breakage rate functions to grinding circuit economical in any meaningful way. Work index analysis was also not favoured because of a number of complicating effects, including the fineness of the feed and product streams and open circuit grinding.It was decided to adopt a recent innovative approach which had been successfully applied to closed-circuit ball milling. For ""functional performance analysis of ball milling"" (McIvor et al., 1990; McIvor et al., 1991), a size criterion is first chosen to define ""fines·' and ~'coarse particles"". In this case 45 microns (325 mesh) was chosen to distinguish fines from coarse material. The relative grinding efficiency of each ball mill environment would then be ~e cumulative grinding (disappearance) rate of coarse (plus 45 nucrons) material per kilowatt hour of energy applied to the coarse material in the mill, divided by the grindability (measured in the laboratory) of the coarse material in the mill feed.Because the disappearance rate of coarse particles is also the production rate of fines, the following equation can be written for the efficiency of the mill environment, Effe, as defined above:"

Jan 1, 1994

By Chris Blain

"Abstract - Based upon an extensive database, this paper analyzes the record of modern mineral exploration success and establishes the 50-year trends in discovery. The record clearly shows that the overall discovery rate rose during the 1950s and 1960s, peaked in the 1980s, and fell during the 1980s and 1990s. By commodity and ore-type target, the pattern of discovery is not continuous. Typically, it is episodic as a series of waves with minor resurgence. The waves reflect the order of the so-called discovery booms, led by uranium, then nickel, and copper, polymetallic base metals and gold. With the possible exception of gold, the discovery booms appear to be independent of metal price, although favorable perceptions of the price outlook may well have initiated the boom or led resurgence. Although difficult to quantify, an emerging trend in modern discovery is the integration of several detection techniques into the search process. No doubt, this trend will continue as orebodies become more and more difficult to find. The record of the past two decades shows that greenfield discovery rates have progressively fallen even though the level of investment in exploration has risen to an all-time high. This trend reflects increasing discovery risk. Several factors are contributing to this trend. Perhaps the two most important are: (1) deteriorating economics as increasing real costs and decreasing real prices continue to raise the economic hurdles for minimum acceptable exploration targets, and (2) increasing exploration maturity in many search terrains, particularly those in the traditional regions of North America and Australasia. To succeed cost-effectively in this new environment of increasing discovery risk will require extraordinary creativity, innovation, and technical skill coupled with commercial discipline."

Jan 1, 2000

By Torsten Zeller

Due to the increasing worldwide demand for raw materials and the resulting rise in commodity prices more expensive processing that is able to utilize complex ores becomes economically viable. This and increasing ecological awareness is why the interest in recycling and urban mining is steadily growing in Germany. In addition to that; landfills do also contain elements, which were not targeted over the period, when they were being accumulated. Examples are rare earths, indium, gallium, cadmium, arsenic, selenium and tellurium. Also copper, zinc and lead, the target components of ancient mining, can be obtained due to more effective processing and smelting technologies. Funding by the German Federal Ministry for Education and Research, entitled "r³ ? Strategic Metals and Minerals ? Innovative Technologies for Resource Efficiency" also indicates the high level of strategic interest. It is against this background that the research project "Exploitation of the Raw Material Potential of Mining and Metallurgical Tips in Respect of Sustainability as Exemplified in the West Harz Mountains (ROBEHA)" has been implemented. A major concern of this project is the possible transfer of results to landfills in other areas. Therefore the development of an expert system based on the innovative processing methods and a method manual for urban mining are the central components of the investigation. This will provide an important contribution to the cost optimization of ensuing urban mining projects. To ensure the success of landfill mining projects it is necessary to record the composition and quality of the deposits accurately. Also the environmental impact caused by landfill mining and changes in the natural and cultural landscape will be considered in a multicriteria evaluation method. Depending on their origin the tips are divided into the categories mining, processing, and smelting. The content of a landfill and thus the economic potential in terms of urban mining is dependent on the type and composition of the deposits (host rock, gangue, and ore mineral), the available processing and smelting technology, and the target components at the time of mining. Zinc, for example, was not been processed until the 19th century, when it gained attention as being material of economic importance. After such knowledge about a landfill is obtained the decision for further investigations can be made. For a total of 158 landfills in the Harz Mountains, both the volume and the approximate contents of copper, zinc, and lead has been estimated for the different types of tips within past research projects. Based on the prices of the London Metal Exchange (LME) and a euro/dollar exchange rate of 0.76 (as of 03/05/2012) and assuming a minimum density of ? ? 1.5 t/m³ a average value of 1.6 billion ? in copper, zinc, and lead can be obtained. Although only these three metals are considered in this first estimate, it demonstrates the potential of landfill mining and the need for further research. KEYWORDS Urban Mining,

Aug 1, 2013

By D. Marotte, M. David

"A new exploration procedure is proposed for volcanogenic massive sulphide deposits of the Abitibi belt. ""Samples"" of acidic volcanic rocks (Si02 > 60%) were compiled from the literature. From the 574 samples collected, 322 were used in each of a number of experiments. Forward inclusion linear discriminant analysis performed on the untransformed geochemical data shows a general depletion in Na20 and CaO along with an enrichment in MgO for a ""proximal"" group of samples relative to a ""distal"" one. The percentage of misclassified samples reaches 20% to 30%, but test sets shows good stability.The exploration procedure was applied to the Normetal deposit, where the authors took 160 samples during the summer of 1977. It quickly leads to the definition of targets for more detailed exploration together with a good recognition of the old known deposit.IntroductionVolcanogenic massive sulphide deposits in the Abitibi belt (Quebec) are mainly found in rhyolites or acidic pyroclastics in the uppermost portion of a calc-alkaline volcanic series (Descarreaux, 1972). The deposits are thought to have formed syngenetically by the action of volcanic hydrothermal exhalations during the waning episode of a felsic volcanic cycle (De Rosen Spence, 1976). Alteration pipes of disseminated sulphides are commonly present. Metal deposition from hot springs, initiating convection cells in a submarine environment, may have been the dominant process in ore formation (De Rosen Spence, 1976)."

Jan 1, 1981

By Denni Nikols, Farrukh Z. Khan

"Highvale Mine, located at Wabamun, Alberta, produces thermal coal for TransAIta's Keephills and Sundance generating plants. Overburden stripping in the mine is conducted by draglines which normally operate on top of the overburden bench. In certain areas oj the mine, however, these overburden benches are susceptible to slope failure. In these areas, due to safety considerations, the draglines are utilized in the less productive chop-cutting mode, supplemented by mobile equipment where the bench height exceeds the dragline chop-cutting limit. This paper proposes maintaining the draglines in their normal digging mode through areas of unstable or jailed overburden, by utilizing a dragline carried toe buttress 10 ensure adequate bench stability. The data requirements and methods of slope analysis to design a toe buttress across an unstable highwall area are examined in rigorous detail. INTRODUCTIONLocationHighvale Mine is owned by TransAlta Utilities Corporation and operated under contract. It is Canada's largest coal mine with an annual coal production in excess of II million tonnes. The mine is located approximately 80 km west of Edmonton on the south shore of Wabamum Lake (Fig. I) and production is currently provided by three pits 02. 03 and 04 (Fig. 2). The entire coal production is consumed at the nearby Sundance and Keephills power generating plants.ScopeThe mining operation at Highvale Mine has had occasional slope stability failures of its high wall overburden bench. This paper examines one such failure which occurred in the summer of 1983 at Pit 03. In addition to an investigation of the failure, Terracon was asked to recommend mine operation procedures which would minimize the impact of these slide zones on dragline productivity. A method of removing the failed material by utilizing the dragline in its normal digging mode is designed. The method's advantages and disadvantages as well as the required support procedures are reviewed."

Jan 1, 1989

By Brian W. Mackenzie

"This paper briefly outlines the characteristics which should be considered in assessing the economics of mineral exploration, and illustrates such an assessment by using data from the Canadian base metal sector. Implications for the sector are found to include the following:(1) base metal exploration has the potential to create a substantial amount of new wealth;(2) investment incentive for exploration under current conditions is not unattractive over-all;(3) because of existing taxation policies, there is much more incentive for large companies to explore than for smaller enterprises;(4) succesful exploration is sensitive to the size, financial resources and organizational structure of the exploration entity;(5) the general level of recent exploration expenditures should be adequate to maintain the current rate of production and perhaps to support very modest growth; and(6) there is an important opportunity for growth in the sector.The findings of the study suggest that government policies should be made more flexible, in order to take into account the risks associated with exploration and with price fluctuations in the base metal sector. Recommendations are also made concerning improvements in provincial regulations for disclosure of exploration information."

Jan 1, 1981

By R. Ricketts, D. G. Vanderveer, F. Kirby

"A program of mapping, sampling and testing to determine the potential of the aggregate resources throughout Newfoundland and Labrador was commenced in 1978. A 6-km-wide corridor parallel to all transportation routes was selected as the study area.The study consisted of a preliminary surficial interpretation followed by field mapping and sampling. Granular resources were sampled at a 500-m interval and non-granular materials were sampled at a 1.5- to 2-km interval. Data were gathered on landforms and stratigraphy as well as a field description of the sample and deposit types. Particle-size and lithologic analyses of the samples were also conducted.The locations of samples and deposits were mapped on 1:50,000 topographic base maps and summarized for publication at a 1:250,000 scale. Surficial geology maps were produced at a 1:50,000 scale. A computer program is being developed for the search and retrieval of field data.The first phase of the Inventory of Aggregate Resources program is nearing completion and to date has collected information on approximately 9,500 samples throughout Newfoundland and Labrador. This data will be used to provide f or the effective management of these vital non-renewable aggregate resources.The mineral aggregate industry in Newfoundland and Labrador is very competitive, but undercapitalized when compared to other provinces. The demand for aggregates is forecasted to increase to in excess of23 million tons per annum by the year 2002.In terms of over-all mineral production, the extraction of sand, gravel and stone has a significant impact when compared to other minerals in terms of value and tonnage produced.IntroductionThe province of Newfoundland has approximately 18,000 km of coastline. A large proportion of the population lives in coastal communities where, traditionally, beaches have been a major source of construction materials. Beaches have, therefore, often been subjected to overutilization, resulting in erosion of back beach areas or adjacent headlands."

Jan 1, 1982

By S. Yannacopoulos, L. Bichler, P. Wanjara, J. Gholipour

Characterization of a virgin and in-service Inconel 718 alloy was undertaken to study the changes caused by the service conditions on the grain size, ?? phase, MN-type nitrides and MC-type carbides. The size, distribution and volume fraction of these phases and grain size were studied using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electron backscattered diffraction (EBSD) analyses. A considerable difference in the grain size, as well as distribution and volume fraction of the precipitates was observed in the in-service material as compared to the virgin Inconel 718. As a result of these microstructural changes, a notable dissimilarity in hardness between the materials investigated was observed. The results presented in this study are important for proper development of repair parameters and heat treatment of in-service Inconel 718 material.

Jan 1, 2014

By T. H. North, A. G. Glover, R. J. Pick

"Girth welding operations represent the rate-limiting step in pipeline construction. A joint industry-university program was set up to establish the field welding characteristics of large-diameter, high-strength line pipe.Theoretical work carried out at the University of Waterloo showed that pipe wall thickness and joint misalignment prior to welding has a marked influence on the lifting stresses acting on the root pass of girth welds. Pipe diameter and pipe ovality had negligible effects. Super-position of lifting and residual stress (caused by the fusion welding operation) highlighted regions of the weld bead most susceptible to hydrogen-induced cracking.The field welding characteristics of 1219-mm-diameter, 13.72-mm-wt Grade 483 line pipe were evaluated using a specially designed test rig. The principal test variables were lift height, delay time after root pass deposition, preheat temperature, pipe composition and joint misalignment prior to welding. For any given life, preheat and joint misalignment prior to welding had the most significant effect on cracking tendency.The output of this program has industrial significance and illustrates the beneficial features of university-industry collaboration.IntroductionField welding operations comprise the rate-limiting step during pipeline construction. Crack-free girth welds must be made in a wide range of weather conditions and consequently the field weldability of line pipe compositions directly affects pipeline integrity and construction economics.Pipe-laying practice comprises root bead deposition followed by a skidding operation involving lifting (or lowering) the pipe length onto skid s so that the next pipe length can be aligned prior to welding. Consider pipeline construction using 24.4-m lengths of 1219-mm-diameter , 13.72-mm-wt Grade 483 pipe weighing approximately 10,000 kg. Skidding involves loading a 3-mm-thick root bead by moving the free end of the pipe through vertical distances of up to 700 mm . The likelihood of cracking in these circumstances depends on the inherent crack susceptibility of the pipe composition employed, on the hydrogen content of the deposited weld metal and on how well the joint handles the external stressing caused byskidding."

Jan 1, 1981

By T. D. Brown

"A review of the current status of gasification technology shows that many engineering systems are immediately available for use in the gasification of coal. Widespread international experience can be brought to bear on the atmospheric pressure gasification of all Canadian coals.Unless a high ash content dictates the use of a fluid-bed gasifier, it appears that bituminous coals can be used in gravitating (fixed] bed systems and that the strongly caking coals are most suited to the high-pressure entrained-bed systems . Existing and developing technologies in fluid-bed gasification are attractive for reactive lignites and subbituminous coals.The Fischer-Tropsch based process is the only commercial embodiment of coal liquefaction; the use of Canadian coals in this process depends only on their gasification characteristics. Current developments in hydroliquefaction are directed toward carboniferous coals of medium or high rank. It is not clear that cretaceous coals of the same rank will give similar process yields and economics.IntroductionThe twin coal conversion processes of gasification and liquefaction have a history which dates back beyond the current energy shortages of the western world. Indeed, liquids and gas from coal were produced before this century.Coal gas produced from a coal carbonization process was originated before 1800, and the development of gasification of non-coking coals was patented by Siemens in 1860.This patent represented the first use of air and steam together in the gasmaking process. The pioneering development of coal gasification Using oxygen and steam was demonstrated by Lurgi in the late 1920s. This historical sequence was all carried out at atmospheric pressure, and it was not until the immediate pre-war (1939/45) years that operation of the coal gasification process at elevated pressure became a reality."

Jan 1, 1981