Search Documents

The morphology of environmentally assisted cracks in stressed pipeline steel has been investigated, For a dilute and neutral solution (NS4) simulating ground water in contact with the steel, semi-elliptical cracks grow faster on the surface (2c) than in the depth (a), hence, the aspect ratio (a/c) decreases, This is explained using a deterministic concept since corrosion is dominant and the primary constraint is the conservation of charge, By contrast, when mechanistic conditions prevail, significant growth occurs in the depth, When underloads are imposed in the loading history, temporary accelerations in crack growth occur because corrosion rather than mechanical effects become dominant.

Jan 1, 2005

By A. Plumtree

The morphology of environmentally assisted cracks in stressed pipeline steel has been investigated. For a dilute and neutral solution (NS4) simulating ground water in contact with the steel, semi-elliptical cracks grow faster on the surface (2c) than in the depth (a), hence, the aspect ratio (a/c) decreases. This is explained using a deterministic concept since corrosion is dominant and the primary constraint is the conservation of charge. By contrast, when mechanistic conditions prevail, significant growth occurs in the depth. When underloads are imposed in the loading history, temporary accelerations in crack growth occur because corrosion rather than mechanical effects become dominant.

Jan 1, 2005

By Mark Freberg

"IntroductionThis chapter is intended to provide information on the operation and maintenance of several pieces of equipment used in heavy media separation. Most heavy media separation circuits, particularly those involving bath separators can be considered as high maintenance areas. Because of this the efficient operation and maintenance of these circuits is very important if the cost per ton of material treated is to be kept to an acceptable level.Heavy media separation (HMS), is a process used to separate particles of different specific gravities. Under laboratory conditions the ideal way to separate two types of particles which have different specific gravities is to suspend them in a heavy liquid which has a specific gravity between those of the two types of particles. Those particles with the lower specific gravities will float on top of the liquid while the higher specific gravity material will sink to the bottom. Given enough time and a sufficient volume of heavy liquid this process will be essentially insensitive to the sizes of the particles involved.Heavy media separation circuits make use of the same principles described above. The material to be treated is introduced into a mixture of finely ground solids, called media, and water which takes the place of the heavy liquid; the mixture of solids and water is known as medium. The separating force can be either gravity or centrifugal force. The type of solids used as media varies but it is usually a high specific gravity material such as magnetite, galena or ferrosilicon.Heavy media separation is used extensively in the cleaning of coal and to a lesser extent as a preconcentration step in base metal and iron ore operations."

Jan 1, 1989

By R. P. Smith

PRIOR to June, 1937, the employees of Hollinger Consolidated Gold Mines, Ltd., at Timmins, Ontario, received medical care for themselves under a contract system developed through an agreement between the employer, employee, and a contract physician. This form of practice is common to the mining industry in Ontario. But with the improvement in mining methods and conditions of living, and through an increasing demand for provision of a complete medical care, it was not any surprise when the employees of the Hollinger mine approached organized medicine and indicated their desire for a plan to provide their families with a more or less complete medical service in addition to that supplied for themselves. In April, 1937, this approach was made, and on June 18th, 1937, the Hollinger Employees' Medical Services Association was formed and started to provide medical services. A review of five years' experience is now presented. The Association provides complete medical service for the employee, his wife and family, as well as those dependents who are the total responsibility of the employee. The employee membership is limited to employees at the Hollinger mine in Timmins who reside in the immediate vicinity. The employee is examined by a Company doctor on application for employment and is subject to further examination by a specialise in chest diseases under the direction of the Workmen's Compensation Board of Ontario. The wife and family are not subject to examination but have to be registered when the employee is accepted for employment. The dependents, other than the immediate family, are subject to medical examination and approval after the employee has applied for such dependent or dependents to be admitted. Membership in the Association is obligatory when the employee is hired, but at the end of any Association year he may drop out if he so wishes.

Jan 1, 1943

By Li Chongyang, Liu Baolan, Jia Xiaolin, Li Suping

An Al/Al2O3 gradient coating applied on a heat-resistant stainless steel was prepared through a slurry process by using aluminum and ?-Al2O3 powders as the transition filler material, alpha alumina as the surface coating material, aluminum dihydrogen phosphate as the binder, and sodium molybdate as the corrosion inhibitor. The effects of heat treatment temperature, adhesive/filler ratio and ?-Al2O3 content on the bonding strength, microhardness and thermal shock resistance were investigated. The crystal phase and microstructure were characterized by XRD and SEM. The results indicated that the composition of the coating changed continuously from surface to coating-substrate interface. The coating could offer high bonding strength and good thermal shock resistance when heat treated at 700°C.

Jan 1, 2010

By R. W. Thompkins

The two largest contributors to silicosis in machine men are dust from drilling and dust from blasting. With the advent of the shatter-cut method of blasting, the evils of blasting dust were greatly reduced. The problem of dust from drilling has been attacked from two different angles: (1) The adoption of dustless frontheads or enlarged water tubes, both of which have proved capable of reducing dust concentrations; and (2) The adoption of better ventilation. Many operators are loath to adopt dustless frontheads or enlarged water tubes on Leyner drills because of the increased repair costs on drills, and also because it has been found difficult to enforce 'the proper usage of dustless machines: for example, workmen sometimes plug the vents in the fronthead.

Jan 1, 1943

By J. A. Finch, M. Mimezami, M. S. Hashemi A.

The adsorption of magnesium and calcium ions on sphalerite and pyrite is discussed. These ions are common in process water and often considered be detrimental in sulphide flotation. The study attempts to characterize the adsorption mechanism, which has been less studied than the oxide system. Generally for oxides metal ion uptake occurs when cations are hydrolyzed. Our findings reveal that magnesium and calcium adsorb on sulphides at pH below hydrolysis, but adsorption is not chemical. At higher pH, charge reversal occurs that does correspond to presence of hydrolysis products. Advances

Jan 1, 2009

By David J. McDougall

"The production of pig iron, wrought iron bars and castings in Quebec during the 18th and 19th centuries has been so closely identified by historians with Les Forges du St. Maurice on the St. Maurice River a few miles north of Trois Rivieres (Three Rivers), that one is sometimes left with the impression that it was the only iron works that ever operated in the province. There were however, about twelve others, one of which was so completely re-built that it should probably be considered as a separate entity. All but two were constructed after the midpoint of the 1800s, coinciding with the growing Canadian demand for ""charcoal pig"" for railway car wheels and castings for industry, and about half of them were technically, if not economically, successful. The misconception about Les Forges du St. Maurice may have come about either because of its long history of somewhat less than continuous production over a century and a half, or a tendency of Quebec historians to concentrate on events in the French-Canadian milieu, but whatever the reason, the other Quebec iron works have been generally ignored. All but one of the Quebec blast furnaces could be described as ""pre-industrial"" with capacities ranging between three and ten tons per day, the exception being the Radnor furnace built in 1892 with a maximum production of about 35 tons per day and an alleged capacity of 50 tons per day. Until a railway network was completed in the 1880s, the location of all the Quebec iron works except the Grantham Iron works was dictated by close proximity to adequate ore reserves because horse transport was of little use beyond a ten-mile radius. The other essentials of forest resources (mainly soft woods) for charcoal, limestone for flux and water power, were generally available except within a few miles on either side of the St. Lawrence River. Among the dozen iron works established in Quebec between 1732 and 1880, seven used bog iron ore in charcoal-fired furnaces. Five of these, including Les Forges du St. Maurice, were located on or near the St. Maurice River which enters the St. Lawrence River from the north, and two, the St. Francis Forges and the Grantham Iron works were on or near the St. Francis River which enters the St. Lawrence from the south. In a general way deposits of bog iron ore in the St. Lawrence lowlands of Quebec were contained within the limits of the post-glacial Champlain Sea, with many clustered along the flanks of the St. Narcisse recessional moraine which is crossed by the St. Maurice and other near-by streams, and the Drummondville recessional moraine which is crossed by the St. Francis River."

Jan 1, 1999

By W. E. Cockfield

THE object of this paper is to review recent geological work in the Cariboo district and to present notes on the recent development of mineral properties. The Geological Survey has done considerable work in the Cariboo district, extending over a period of years. In 1885 and 1886, Bowman (1) mapped the geology of a large area. In 1922 and 1923, Johnston and Uglow (2) mapped Barkerville area in some detail and prepared a report on the placer and lode gold deposits. In 1931 and 1932, Cockfield and Walker (3) mapped the Quesnel Forks area. In 1933, Hanson reported on Willow River area ( 4), and in 1934 made a detailed examination of part of the Barkerville area (5). In 1935, Lang commenced work on the Keithley area, lying to the southeast of the Barkerville area, and in 1936 published a preliminary re-port (6). The work on Keithley area was continued in 1936 by both authors of the present paper. As the results of the earlier work have been published, this paper will be concerned largely with Keithley area, that is, the part of the region lyinp between longitudes 121° 00' and 121° 30', and latitudes 52° 45' and 53° 00 . This area lies astride Cariboo (Swamp) river and extends north some 17 miles from Keithley, which is situated near the southern border of the map-area (see sketch-map). Points in the western part of the map-area are fairly accessible. A road extends from Barkerville to upper Cunningham creek, and from this a trail crosses Snowshoe plateau to Keithley. A second trail from this road leads to the lower falls on Cariboo river. From this road, a branch road leads to upper Antler creek, with a trail leading from this branch road to Keithley. Part of this western half of the area is made up of the Snowshoe plateau, which constitutes a gently rolling surface, at or above timber line, where trails are largely unnecessary.

Jan 1, 1937

By H. Kroog

"This contribution reports recent mineral sorting experience and lists the possibilities of the newest generation of automatic mineral sorters with a special focus on electromagnetic detection, optoelectronic technology and the latest innovative X- Ray transmission units. In industry, mineral and ore are still hand-picked and current automation potential is only utilised in a handful of specific applications. Recently a number of technological developments took place that may increase sorting potential, save mill costs and lead to lower overall tonnage costs. The mentioned technologies provide automatic dry separation of minerals and rock as an alternative for conventional processing. The MikroSort technology is environmentally friendly:•,The remaining waste is free of contaminations•,The dump volume is reduced•,The concentration of the high grade material•,at an early stage saves resources"

Jan 1, 2005

By L. M. Cumming

"The contact between dolomite of the St. George formation (Cambro-Ordovician) and limestone of the overlying Table Head formation (Middle Ordovician) is a regional disconformity. This is best illustrated from exposures on Pointe Riche Peninsula, near Table Point, and along Port au Port Bay. The contact occurs along 180 miles of the west coast of Newfoundland from St. John Island in the north to the western part of Port au Port Peninsula in the south. A disconformity of the same age occurs between the Romaine and Mingan formations on the north side of the Gulf of St. Lawrence.Dolomitic beds beneath the disconformity locally contain concentrations of base-metal sulphides. Sphalerite occurs in dolomite pseudobreccias of the St. George formation at Zinc Lake, 7 miles northeast of Daniels Harbour. The 'Western Newfoundland Lower-Middle Ordovician regional disconformity is interpreted as having originated on and near the edge of a broad platform, and to have provided an important regional geological control in the localization of zinc mineralization."

Jan 1, 1968

By Joseph Sawicz

By now, the concept of remotely controlling heavy equipment in underground mines has become commonplace. Personnel safety is the biggest justifier for remote control, followed by an inherent cost saving (in certain cases) when wireless video is added to the mix. There are a handful of vendors targeting this need, and for years the mines have remained loyal to their brand. But as the number of remote-control related accidents and maintenance costs increase it forces our industry to take another look at this commonplace concept. And as the blinders are taken off, the mines are getting the revelation that not all remote control systems were created equally. This paper highlights the differences between various remote control systems, and then moves into an in-depth look at HARD-LINE?s package which drastically cuts maintenance costs, and also provides a solid investment toward full Tele-operation.

Apr 1, 2005

By J. R. Smith

"The Lake Dufault orebodies were discovered by deep surface diamond drilling. When a reasonable amount of outline drilling had been completed, the decision to go into production was made. The fact that shaft sinking, lateral development, the detailing of the orebodies and stope preparation were to be carried out as rapidly as possible necessitated very close scheduling.After a study of varions possible mining methods, an open-stoping system using long-hole blasting was chosen. Diesel-powered Transloaders were selected for the mucking and transportation of ore from the drawpoints to the orepass.At the time of writing, the choice of mining method appears to have been fully justified, although more time will be required to arrive at true operating costs and efficiencies."

Jan 1, 1966

By Kevin Azocar, Jim Hazzard

"Slope stability analysis is performed most commonly using limit equilibrium calculations or numerical models assuming a two-dimensional slice through an infinitely long slope surface. In areas such as open pit mining, where most slope surfaces are not planar, the importance of curvature becomes important due to the economic gains associated with creating a steeper slope. With advances in computing capabilities within the last decade, three-dimensional slope analysis can be performed within reasonable time frames. Some work has been done on the potential importance of curvature on slope stability, mainly assuming homogenous materials with a circular shear-failure mechanism. However, many open pit mines are excavated in jointed rock mass where a completely different set of failure mechanisms can be seen. Depending on the geometry and radius of the pit, the curved geometry may influence the factor of safety and failure behaviour compared to a two-dimensional slice.A series of numerical analyses were performed to investigate the effect of curvature on jointed rock slope stability compared to an equivalent two-dimensional slope analysis. By using discrete element method models, the influence of joint planes and interaction between distinct blocks can be seen. With a three-dimensional model, the effect of curvature can be combined with multiple joint sets at any orientation, which cannot be seen in a single slice. Numerous three-dimensional models are created, along with an equivalent unit-thick slice. The effect of curvature on a variety of different types of failure mechanisms is observed, and graphical relationships are created to quantify the difference between the three-dimensional factor of safety and the two-dimensional factor of safety based on the degree of curvature."

Jan 1, 2015

By E. Benguerel, G. Monteith, L. Centomo, S. Pelletier

In early 2007, it became apparent that with changing concentrate feeds, the magnesium (Mg) load projected for CEZinc starting in 2009 and beyond would quadruple and overwhelm the current Mg process bleed capacity. A project was started, following design for six sigma (DFSS) standards, to select both the optimal process and to evaluate its target capacity for the Mg bleed circuit. The economic and process risks of under or over-designing while Mg reduction efforts were underway at the mines also needed to be evaluated. This paper describes the project methodology, the impact on the plant, and some potential optimizations for CEZinc's basic zinc sulphate (BZS) Mg bleed process.

Jan 1, 2008

By M. P. Rennick, D. M. Burton

Abstract -The Murray Brook massive sulfide deposit, which was the first geochemical discovery in the Bathurst camp, is one of the largest sulfide deposits in the area. The massive sulfides are hosted by quartzose metasedimentary rocks in the lower part of the Ordovician Tetagouche Group. This thick succession of sedimentary rocks is overlain conformably by felsic volcanic rocks, and is structurally overlain by mafic volcanic rocks. The massive-sulfide body is polydeformed, but primary metal zoning is still discernable and may permit future exploitation of discrete lead-zinc and copper zones. Although it was discovered in 1956, the deposit was not developed unti11989, when Murray Brook Resources commenced processing of gossan containing precious metals. Recovery of gold, silver, and mercury is accomplished by indoor vat leaching on a year-round basis.

Jan 1, 1992

By H. Salamanca

HighService has developed different equipment using wireless technology and machine vision systems that were specially designed to allow 1) the online determination of the SAG mills liner's service life, 2) the automatic detection of a missing dipper tooth in mineral extraction shovels, 3) the reduction of accident risk potential in the mineral transportation within the mine, and 4) the reduction of collision risk potential between shovels and wheel dozers during mineral extraction. For the development of all these systems at HighService, extensive research has been done in radio frequency and image processing fields. The integration of both technologies with the expert knowledge of the company on the typical harsh environment conditions of the mining industry has led to the development of heavy duty equipment that tolerate the extreme mechanical requirements of SAG mills and electrical mining shovels.

Jan 1, 2007

By J. E. Dutrizac, R. J. C. MacDonald, J. B. O'Reilly

"Sometime around 3000 B.C., primitive metallurgists working in the mountainous regions of Asia Minor bordering on the Black Sea (Pontus) produced a soft, easily fused metal today known as lead. It appears certain that the first metal was made by reductive smelting of galena, but whether this recovery arose by the accidental inclusion of galena in the stones of a fire hearth or whether it occurred as a consequence of simple pyrometallurgical experiments on a series of interesting ""stones"" will likely never be known with certainty. The properties of galena, high metallic lustre, great density and facile cleavage, must have excited the ancients, and such ""stones"" would have been the object of primitive testing111 - Shortly after the discovery of lead, the ancients found that the controlled oxidation of this metal at elevated temperatures yielded smaller amounts of a more interesting material, silver. Again, it is uncertain if the production of silver by primitive cupellation techniques was the result of a fireside accident or the consequence of a deliberate experiment, but the important fact is that silver was produced shortly after the discovery of lead. The techniques for making lead and silver spread gradually throughout the entire civilized world, likely as a result of both technology diffusion and independent rediscovery. The physical properties of lead could not have been overly attractive to the ancients, but silver was a different matter altogether. The gleaming white lustre and relative immunity to oxidation quickly assigned silver to the precious materials category, a status it still enjoys. In early times, argentiferous galena was inevitably processed only for its silver values; lead was generally an unwanted byproduct and was frequently discarded as litharge (PbO) during the cupellation process. The silver was eagerly sought, however, and resulted in considerable mining activity culminating in the famous Athenian silver mines at Laurium at the southern end of the Athenian peninsula."

Jan 1, 1999

By Nabeel Khan

Annual oil production from the Canadian Oil Sands in Northern Alberta has been rising for several decades, and more ore and overburden are excavated each year from an increasing number of open pit mines. Overburden meeting certain specifications will be used to dam tailings and fill open pits, but the remaining material must be stored in overburden storage structures (OBSS). Well-designed overburden storage structures are more stable and cost less in the short- and long-term. The purpose of this paper is to explore OBSS designs that will be stable yet economical in the short- and long-term. The geological background of the site is briefly discussed, including the effect of each of the main geologic layers (recently deposited till and muskeg, Clearwater Formation clay shales, McMurray Formation oil sands, and the Devonian limestone) on the slope stability of the OBSS. Cost is considered in the analysis when balancing between minimizing costs (steeper slopes) and acceptable factors of safety (flatter slopes), all the while considering the financial consequences of failure. Potential failure planes are identified and probabilistic analysis is conducted on the critical failure surface. The variations in the factor of safety caused by varying pore water pressure, friction angle, and cohesion, are plotted and discussed.

Jun 1, 2012

By Robert Thomson

"The Cobalt camp is by far the most productive camp of the Temiskaming silver-cobalt area. The date of discovery, 1903, is an important one in the history of Canadian mining; from then on prospecting and mining grew rapidly to take the prominent places they now hold in Canadian life.At Cobalt, prospectors and operators, who were to play prominent parts in other Canadian camps, received their initial training. The exploration campaigns leading to the discovery of several new camps were organized at Cobalt, and a considerable part, indeed, of the funds for these campaigns were profits from mining at Cobalt.The discovery of the Cobalt camp was purely accidental, not the result of any purposeful search. Fred LaRose, a blacksmith employed in the construction of the Temiskaming and Northern Ontario Railway, discovered mineral, afterwards determined to be valuable, within a few feet of the right-of-way. This discovery became part of the very productive LaRose mine. The publicity given this discovery, particularly by Willet G. Miller, later Provincial Geologist of Ontario, led to the rapid development of the camp.ProductionCobalt is a great camp by virtue of its silver production; cobalt is also important, although clearly subordinate. Copper, nickel, arsenic, and bismuth are by-products of mining for silver and cobalt and have not been of great importance to date.The following table gives the metal content of ores, concentrates, etc. from the Cobalt camp for the years 1904 to 1954 inclusive, as reported by the mines (l):"

Jan 1, 1949