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By J. M. R. Carvalho, M. T. A. Reis, M. R. C. Ismael, M. J. N. Correia, S. M. C. Santos, J. M. Carvajal

A sulphide zinc concentrate (Zn-40%) has been leached in sulphuric and chloride media to optimize the conditions for the recovery of zinc and copper. Previous results showed that extractions of 95% zinc and 20% copper can be achieved in just one stage, after two hours of leaching at 80°C with a solution 0.5M in Fe2(SO4)3 and H2SO4 and a solid/liquid ratio of 5%. This work presents the results obtained in the leaching experiments carried out in sulphuric and chloride media using two and three crosscurrent stages and a countercurrent process simulation for a solid/liquid ratio of 10%.

Jan 1, 2008

By R. W. Boyle, W. Dyck

"Scientists throughout the world have observed radioactive disequilibrium in the uranium decay series. Radiometric and fluorometric determinations of U in plants from the Goldfields district and in sediments and rocks from the Beaverlodge district exhibit marked radioactive disequilibrium. The eU/U ratio in plants rooted in mineralized ground shifts from greater than unity to less than unity for those rooted in background soils. A similar shift is observed in the transition from rocks to stream sediments and to lake sediments in the Beaverlodge district.Results of a Rn-Ra-U survey of lake bottoms in the Key Lake district show that anomalous hydromorphic U from U mineralization is parallelled by anomalous Rn, even though there is much less Ra in the lake-bottom sediments than one would expect from the amount of U present. IntroductionDisequilibrium in the U decay series has been studied for many years and is observed in almost all surficial environments. Rosholt (1959) measured U, 234Pa, 23O'fh, 226Ra, 222Rn, and 210Pb in a large number of U ores and outlined six types of situations to explain disequilibrium. Davy (1974) outlines the geological significance of radioactive disequilibrium situations with respect to exploration. Levinson and Coetzee (1978) discuss possible mechanisms by which separations of parent and daughter elements are affected and suggest analytical pitfalls that may be encountered in the use of radiometric techniques when disequilibrium has occurred. Generally, it is the oxyphile and easily complexed parent 238U (with its associated isotopes 235 U and 234U) that is leached from rocks and soils at a faster rate than are the daughters, 230Th, 226Ra, 2loPb, and 206Pb. This mobilized U is adsorbed on sediments in streams and lakes, or enters groundwaters, where it is eventually precipitated under reducing conditions, occasionally in oregrade concentrations. This surface leaching and"

Jan 1, 1980

By D. Madsen, B. Salamondra, A. Moss, D. Etienne

"Raise mining at the Namew Lake Nickel Mine in Manitoba uses 3 m diameter bored raises driven at 45 to 50 degrees dip for stope access and drilling. These raises are developed within the orebody on 20 m centres to accommodate electric-hydraulic longhole jumbos and charging wagons. Critical elements of stope development include delineation of are contacts, control of deviation during raise development, optimal stope sequencing to permit a high extraction rate, drill anchorage installation, production drilling and blasting, and ground control. Procedures to deal with these elements are described, with emphasis on the geotechnical investigation for design of open stopes and pillars.Although mining with drilled raises does not have the flexibility to follow large variations in orebody dip, results to date indicate that it can be used successfully in the thicker ore zones. Thinner zones are currently mined using a modified Avoca method. Some flexibility to accommodate variations in orebody dip in thin are zones may be obtained by using alimack raise climbers to drive access raises, and carry longhole drills and charging equipment. Rock quality has been sufficiently good to maintain stable stope walls for full-height mining of primary stapes at 20 m strike length.IntroductionThe Namew nickel deposit is located 60 km south of Flin Flon, Manitoba. It is a moderately dipping (45 to 50 degrees) pipe-like ultramafic intrusion with a sulphide halo enrichment. The diluted recoverable ore reserves at January I, 1990 are 2.2 million tonnes grading 2.05% Ni and 0.7% Cu. The operation is a joint venture between Hudson Bay Mining and Smelting (60%) and Outokornpu Mines Ltd. of Toronto (40%). The mine is budgeted to produce 530 000 tonnes in 1990. The deposit was discovered in 1984 and mine development commenced in 1987.In the raise mining area, primary stopes will be filled with a high quality backfill consisting of cement and quarried limestone. Secondary stopes will be mined out between the primaries in the second pass of mining. The design extraction rate is 94% over all.The orebody above 120 level has an average mining width of 2.4 m, so is too narrow for raise mining. A modified form of Avoca stoping is used."

Jan 1, 1991

By James H. Savory

"In recent years, there has become a growing interest toward a better understanding of balance rope behaviour. With this in mind, the auth or will present a comprehensive summary of field experience, as well as conclusions. In presenting this overview, it is the intent to stimulate further interest as well as provide a framework from which further in-depth investigation can be initiated.Topics which will be covered include rope cores, lubrication practices, loop dividers, rope failures, etc.IntroductionThe first friction hoist was designed in Belgium in J862 by Lemielle. However, it was not until 1877 when Carl Frederich Koepe installed a friction winder sheave at the Hanover Colliery in Germany, that the design was given serious consideration. The winder consisted of a motor-powered sheave over which a single rope was installed, and the end s attached to two conveyance s. Beneath the conveyances a rope was connected, designed to reduce the chance of slip. This was the first balance rope.This earl y mod el is a far cry from the modern tower or ground mounted Koepe winders employed throughout the mining industry today. There have been vast improvements in all aspects of the Koepe winders. One such improvement is in the balance ropes used. This particular area will be concentrated on, with emphasis on selection, maintenance and field experience.SelectionThe sale purpose o f a balance rope is to counter the head rope weight. Obviously then, in selection o f balance ropes, weight is of primary concern. Usually the head and balance ropes are equal in weight. However, sometimes balance ropes which are 5 to 10070 heavier than the head ropes are employed. These reduce horsepower demands during peak acceleration periods, and assist in overcoming inertia during retardation periods. As well, it is sometimes preferred to reduce the balance rope weight, in order to compensate for the eventual weight buildup of lubricant, dirt and debris."

Jan 1, 1983

By Bert S. Hall

"IntroductionThe purpose o f this paper is to review the evidence at hand concerning the earliest centuries of cast iron in Europe, from roughly 1400 A.D. until the second half of the sixteenth century. For the most part it is concerned with the relationship between two technologies which emerged first in China and then later appear in Western lands, gunpowder weapons and iron founding. We should not assume, as I hope to show later in this discussion, that weapons constituted the only product for which the iron founder had any market, but it is clearly true that attempts to produce weapons constituted the most severe technical challenge for the early founder. Firearms appear for the first time in Europe in the 1320s and develop into significant weapons on the field of battle by the end of the century. Theirs is a complex history, subject neither to easy summary treatment nor to simplified models of development. I hope to be able, through the analysis of the evidence concerning cast iron, to show that one important strand in the fabric of gunpowder's history concerns the materials from which cannon could be made. This question is subject to a number of shades of meaning, because ""cannon"" can be made for many purposes under a profusion of different names, and under sharply varying conditions of use. As a result, the question of materials is frequently really a question of competing materials, and involves a complex set of factors, of which production costs and the ultimate safety of the user seem the most important. Judged in this manner cast iron was an important but unsatisfactory metal for weapons purposes until 1543, at which time English founders learned to make iron muzzle-loading cannon which could rival bronze ordinance in most important performance criteria, but which cost much less to produce. With that event, the history of cast iron and the history of weapons entered into the close relationship that persisted until the advent of rifled artillery made of steel in the middle of the nineteenth century."

Jan 1, 1983

By H. M. Giegerich

"INTRODUCTIONThe Red Dog Project in Alaska is being developed by Cominco Alaska, a subsidiary of Corninco Ltd. of Canada, and the Nana Regional Corporation, one of the 12 native corporations created by the Alaska Native Claims Settlement Act of1971.The State of Alaska is also a very key part of the project through its financing of the transportation system for Red Dog. Red Dog will be the third, and largest, of Cominco's Arctic mining developments in the past thirteen years, after the Black Angel Mine in Greenland, which started up in 1973, and the Polaris Mine in the Canadian Arctic, which began production six years ago in 1982.Red Dog is one of the world's great mineral deposits, with a unique combination of large size, high-grade, and a waste-to- ore ratio less than I: I, which will make it the world's largest, and one of the lowest cost zinc producers, when at full production. The present mineral reserve is estimated to be 85 million tons , at a grade of 17.1010 zinc, 5% lead, and 2.4 ounces per ton of silver. Based on the current production forecast, this will give a mine life of almost 50 years, and the deposit is still open in two directions, although the structure is becoming thinner at depth. As well, there is a satellite zone about one mile south of the main deposit which could contain up to another 8 million tons of mineral at Red Dog grades or better. This is not presently included in the reserve due to potential processing difficulties.In relation to other zinc deposits, Red Dog is the second largest ever discovered, smaller than the original Broken Hill deposit in Australia, but larger than Cominco's own Sullivan Mine in British Columbia, which is number three. It is quite possible that, when the area is adequately explored, Red Dog will be number one."

Jan 1, 1989

By I. Farr, P. Quinn, H. Mani

"Difficulties in the flotation of Inca's ultramafic ores at the Thompson Mill are related to the presence of serpentine slimes and some floatable rock minerals. Serpentine slime coatings depress pentlandite recovery while rock flotation decreases concentrate grade. Carboxy methyl cellulose (CMG) has been shown to promote sulphide flotation and to reject floatable rock.To improve ultramafic ore flotation, CMC addition in the rougher stage was studied in a laboratory scale column. Batch tests were conducted in the lab and followed up with continuous testwork at the Thompson mill. At 0.5-1.0 g CMG per kg ore, pentlandite recovery is increased by 5-10% in rougher flotation, pentlandite/rock selectivity is improved and pentlandite/pyrrhotite selectivity is unaffected.IntroductionAt Inca's Manitoba Division, two distinctly different sulphide ores are processed at the Thompson Mill, primarily by froth flotation. The sulfide ores are contained within the Thompson Nickel Belt and currently there are two operating mines, Thompson and Birchtree. Sulphide mineralization in both mines is simple, consisting of pyrrhotite (both monoclinic and hexagonal), pentlandite, and minor chalcopyrite. Both deposits are hosted by metasedimentary and metavolcanic rocks with variable ultramafic rock associations. Ultramafic rocks are mostly serpentinites: magnesium rich rocks composed predominately of serpentine. There is little serpentinite at the Thompson mine, while mineralization at Birchtree is closely associated with significant ultramafic rocks.Excellent recoveries of pentlandite (Pn) and chalcopyrite (Cp) are achieved at the Thompson Mill when processing ore from the Thompson mine. In treating the ultramafic associated Birchtree ore, nickel recoveries are some 6 to 8% below that achieved with Thompson ore. Furthermore, a typical concentrate from Birchtree ore contains more rock and is higher in MgO content. The presence of rock in the concentrate is related to free floatable rock species as well as rock locked with sulfides. The reason for the difference in flotation responses of these two ores has been the subject of on-going re-search."

Jan 1, 1998

By V. G. Papangelakis, G. P. Demopoulos

"Recovery of gold from refractory ores and concentrates presently constitutes one of the most important, challenging, and exciting areas of R&D activity in the gold processing industry. New technologies are being tested for the treatment of refractory gold materials, some of which have been advanced to the level of commercial operation. In this paper, some recent technological developments in the hydrometallurgical processing of pyritic matrix-refractory gold ores are highlighted. Key operational steps of each of the alternate hydrometallurgical technologies are analyzed and potential advantages and drawbacks are identified. The processes which are reviewed are: hydro chemical oxidation, biochemical oxidation and pressure oxidation. INTRODUCTIONOver the years the term ""refractory"" has been applied in gold ore processing to denote situations in which straightforward cyanidation failed to yield high gold recoveries. A number of mineralogical and chemical factors may be responsible for this ""refractoriness"" problem. A systematic classification of the different options for their treatment has been discussed in a recent review paper. In this paper, the pretreatment of the submicroscopic gold encapsulated within the matrix of pyrite and arsenopyrite minerals is considered. This type of gold is the ultimate refractory material because complete breakdown by reaction of the host mineral structure is required.The method which has been traditionally applied for the treatment of pyritic-type refractory gold ores is an oxidation roast (single stage or double stage depending on the As content) of a flotation concentrate to produce a porous calcine, the latter being more amenable to cyanidation. Despite its established practice, oxidation roasting is not considered particularly attractive with today's standards for high product recovery and clean environment. Roasting is known to be very sensitive to heating parameters and feed composition and deviation from optimum conditions can result in reduction in permeability which is translated to incomplete gold liberation."

Jan 1, 1989

By J. A. Rogers

"The Arthur W. White Mine (formerly Dickenson Mine) is a structurally controlled, hydrothermal gold deposit. A gold producer since 1948, it has, to December 31, 1990, processed 6.9 million (m) tons (T) of ore grading 0.45 ounces per ton gold (oz/T Au). As of December 31, 1991, Proven and Probable Ore Reserves were 3.2 m. T. at 0.32 oz/T Au. The mine is located just east ofPlacer Dome Inc. 's Campbell Mine, within the Cochenour-Gull.rock Lake deformation zone. It is situated on the hanging-wall side of a southeast-plunging anticline in a sequence of metamorphosed Archean volcanic, sedimentary and plutonic rocks of the Red Lake greenstone belt. Ore-bearing structures, found mainly within basaltic rocks, are brittle within greenschist-facies rocks to the northwest, but become more ductile toward the southeast, in amphibolite-facies rocks. Within and proximal to these structures, carbonate and arsenopyrite alteration decreases, whereas biotite, actinolite, pyrite and pyrrh otite all increase to the southeast.Ore and shear structures occur symmetrically about the northwest-trending, steeply southwest-dipping, flattening foliation . The three most common ore trends are on average: (A) northwest trending with a 55 degree to 85 degree dip to the southwest; (B) north-trending with a 40 degree to 50 degree dip to the west; and (C) due east-west-trending with a vertical dip. In general, the dominant direction of economic gold concentrations are explained and thus predicted by considering deformation style (brittle or ductile), rock anisotropies such as bedding and lithological contacts, and direction/magnitude of relative block movement. Direction ""A"" can be found adjacent to both right- and left-handed faults. Direction ""B "" occurs with dominantly right-handed systems and direction ""C"" is found with predominantly left-handed movement. Major faults active prior to, during, and after ore formation can have offsets in the order of 2500 feet. Movements along these faults were transpressive while their conjugate breaks were dilatant, thus creating zones for alteration and ore solution emplacement. A series of faults , each with offsets up to 30 feet were established under lower temperature brittle conditions during late- to post-ore formation. In more complex zones, formed during more ductile deformation, these faults controlled the localized geometry and, thereby, the depletion and enrichment of ore shoots, causing a high nugget effect.Although an important aspect of production planning and monitoring, grade control is also very important within a complex ore zone so that the nuggets are not missed. Detailed observation of structure at the hand-sample scale and detailed mapping at the stope scale give valuable clues to interpreting the structures on a mine-wide scale. Determining the relative movement along fault structures is very important so that using an action-reaction- type logic, potential dilatant areas can be predicted and targeted for development and diamond drilling."

Jan 1, 1992

By R. del Villar, A. R. Laplante

"This article presents four grinding simulation programs, written in Applesoft BASIC. The firs t two calculate residence time distributions (RT Ds) for open and closed loops mills. The third program calculates the select ion functions from the RTD, breakage function and particle size distribution (PSD) o f the feed and discharge. Two linear regression programs are also included to calculate the breakage function. These results are used in the fourth program to simulate continuous or batch grinding kinetics.The modelling approach presented is the size discrete, time continuous matrix formulation presented by Reid (1965) from concepts originally proposed by Epstein (1948). It is at the present time the most widely accepted phenomenological model of grinding kinetics and is standard textbook material (Austin et 01., 1982; Kelly and Spottiswood, 1982, p. 152). The concepts of RTDs and tracer testing originated from chemical engineering theory and practice, and are well presented in Leven spiel (2n d Ed . 1972 , Ch. 9) .Applesoft* was chosen because it is compatible with many micro computers. It is also one of the simplest and least powerful BASIC versions. Thus it can easily be adapted to other more complex BASIC versions.Open Loop Residence Time Distributions (Program RTDOPEN)As mixing, channelling, stagnation and short-circuiting all affect slurry motion in tumbling mills, transport characteristics are very complex an d cannot be derived from fundamental principles. Fortunately , as grinding follows first order kinetics, transport characteristics for the purpose of grinding simulation ca n be represented by the RTD of the slurry phase . It is normally determined using liquid tracers, as it has been demonstrated and is commonly accepted that in industrial ball mill s, the RTD of the so lid phase is particle size independent and equal to that of the liquid phase."

Jan 1, 1985

By C. Gu

Flow field design is critical for PEM fuel cells. The flow field design can affect reactant distribution to the catalyst surface, water management, thermal management and current collection. Therefore, it has tremendous impacts on the fuel cell performance and durability as well as reliability and operational flexibility. In this paper, an optical method is used to study the reactant distribution in the flow field channels of two commonly used flow field designs, straight channel design and serpentine channel design. Images of the flow patterns are shown followed by discussions of the flow patterns.

Jan 1, 2005

By O. E. Andrew

THE object of this paper is to present a brief summary of the dust control system in use on the 3,825-foot level at the jaw crusher station, Lake Shore mine. During the years 1936 and 1937, dust survey reports were presented to the management showing that high dust concentrations were being created during operating periods. At that time, however, this crusher was running only an hour or so each shift, and it was felt that no large capital expenditure for dust control equipment could be justified. In order to afford some protection to the operators, a number of respirators then on the market were .tested and the 'Comfo' respirator was adopted for use by the crusher-men. In 1938 this crusher began to handle a large share of the total mine tonnage and the hours of operation were increased. Further dust sampling showed increased dustiness with the longer operating time. It was also realized that the operators suffered considerable inconvenience if they wore their respirators throughout the shift. If the respirators were not worn, then dangerous amounts of dust were being inhaled. The fact that the crusher station was situated on the 3,825-foot level limited the means that could be employed to eliminate the dust hazard. At that rime there was not available the 5,000 c.f.m. of fresh air which would be required to sweep out or dilute0 the dust, and there was also no way of disposing of the contaminated air without passing it on for other men to breathe. Thus it became apparent that a self-contained dust disposal system would have to be installed.

Jan 1, 1941

By David L. Anderson

"The objective of this paper is to describe the potential impact of inter-provincial competition f or new output capacity on the Canadian potash industry. It will be shown that the ramifications of such actions are potentially severe, especially since the potash industry is one of the few non-fuel minerals in which Canada purportedly possesses a significant degree of market power. More specifically, the paper addresses the impact of possible expansions in New Brunswick, Manitoba and, perhaps, Saskatchewan. The findings suggest that such initiatives could result in substantial excess capacity and the dissipation of monopoly rents. In summary, given the market structure of the industry, it is unlikely that the employment and economic effects associated with industry expansion will offset the loss in national welfare attributable to rent dissipation.IntroductionThe objective of this paper is to discuss the potential impact of inter-provincial competition for new output capacity on the Canadian potash industry. The ramifications of such competition are potentially severe: given that the potash industry is one of the few non-fuel minerals in which we purportedly possess a significant degree of market power(1), it is important that sound supply management practices are followed. However, possible initiatives by New Brunswick, Manitoba and, perhaps, Saskatchewan may initiate an inter-provincial competition which could result in substantial excess capacity and the dissipation of economic rents(2). Given the market structure of the industry, it is not intuitively obvious that the employment and economic effects associated with industry expansion will offset the loss in national welfare attributable to rent dissipation."

Jan 1, 1985

By M. H. Govett, G. J. S. Govett

"The current American ""energy crisis"", occurring in the midst of a global debate on the adequacy of mineral supplies to support present and projected levels of world consumption, has focused attention on Canada as a major world producer of minerals. Exports of minerals account for approximately one-third of Canadian foreign earnings; more than half of these exports are to the United States. Although the United States is a net importer of most industrially important metals, with the exception of nickel and zinc, only a small part of American mineral imports are from Canada; these imports are minerals for which geographical proximity and strategic considerations are important. In the short-term, Canada is more dependent on her exports to the U.S. than America is on imports from Canada. It is argued that Canada, far from indulging in economic nationalism to preserve her resources, should expand her exports while the markets are available."

Jan 1, 1973

By Richard Cyr, Peter Larsen, William Quesnel

"The need to continually improve efficiency and lower costs in mining operations is of paramount importance to all concerned in the industry. Mining operations are constantly testing new methods and equipment in order to lower costs and improve productivity. Equipment suppliers strive to fulfill the demands of the mines through improved design and innovative ideas for productivity increases. In some cases, however, an increase in productivity does not require new equipment design, but rather the application of an existing mining method into different operating parameters. Such is the case in applying longhole methods to narrow vein ore deposits.Bulk mining methods have long been recognized as efficient, low-cost alternatives in narrow vein operations. Typically, shrinkage and some cut-and-fill methods are employed. The shortfall of these methods is the tendency to be labour intensive. The demand for miners skilled in these methods far outweighs their availability. Consequently, labour-efficient methods have to be employed to fill the void. The application of longhole drilling techniques to narrow vein deposits is one such method.IntroductionPercussion longhole drilling evolved in Canada in the early 1940s. Prior to percussion drilling, blast holes were drilled using diamond drill equipment. Jack Gardner, of Gardner Steel, began testing with carbide percussion bits and extension drill steel in applications where diamond drills had been previously employed. Percussion drilling equipment proved to be considerably more productive and cost-efficient. The experiment eventually led to the replacement of diamond drills in this application.Over the years, the percussion methods were improved, with particular emphasis on the equipment used. Rifle bar rotation machines evolved to independent rotation. Bar and arm set ups evolved into self-contained mobile drill carriers that increased productivity while reducing the physical labour. The introduction of hydraulics further improved efficiency and production figures. Today, it is not uncommon to see fully computerized jumbos in production longhole drilling applications. These machines represent the ""state-of-the-art"" in longhole drilling equipment.Production longhole drilling is considered to be one of the most efficient bulk mining methods in use today. Production statistics normally exhibit low-cost, efficient ore extraction. As a rule, longhole (blasthole) methods are associated with substantial ore deposits. These methods have exhibited high production figures and low mining costs.Over the past decade, long hole methods have been applied to several narrow vein deposits. These applications have proven that, given the right parameters, longhole methods will produce the same advantages in narrow vein deposits as are seen in more conventional applications."

Jan 1, 1990

By D. M. Watson

Mineral discoveries and subsequent extraction have led to the establishment of many small communities, some major towns and a few cities . In Canada, such developments have essentially occurred without benefit of long-range regional or local planning. In the past, this was not a cause for concern. Now, however, rising expectations and reorientation of social values have placed increasing responsibility on government and industry to ensure the long-term viability of communities and regions. Such responsibility means large investments by government in infrastructure and by industry in extractive and processing plants. Uncertainty in the interpretation of ore reserve estimates becomes a critical factor. The traditional methods of reporting reserves - "proven", "probable" , "possible" - may be useful in individual mine production planning, but they are inadequate for planning industrial and public infrastructure, The need for a better information base is critical, with clear and precise definitions of what is being reported, but we are a long way from achieving it. The challenge is therefore to develop a closer professional relationship between government and industry and to tie mineral development to long-range regional strategies.

Jan 1, 1977

By Norman M. P. Low

"IntroductionIndustrial applications of mica utilize two commercially important varieties of mica: muscovite and phlogopite. Muscovite mica is a potassium mica with a general chemical formula, H2KA1(Si04)3 h, and is sometimes referred to as a potas hsilicate. Phlogopite is a magnesium mica having a general chemical formula, H2KMgSi(Si04)3, and is distinguished from the muscovite mica by its decomposition in sulphuric acid.Canada is one of the major natural mica producers in the world. A large tonnage of the mica powders is at present mined and processed in the Eastern Townships of Quebec. This Canadian mica is of the phlogopite type. A closely related mineral of the mica family which is widely used in the construction industry is vermiculite. It is a dehydrated magnesium-aluminum-iron silicate characterized by a foliated structure. Expanded vermiculite, which is often referred to as exfoliated mica, is used as many types of thermal and acoustic insulation, as loose fill in buildings, as an aggregate in concrete, as an ingredient in plaster and insulating concrete , and in fire-proofing compositions. Natural phlogopite and muscovite mica powders are used extensively as reinforcing agents in organic polymers. They also have a wide range of applications in commerical products. For example, dry-ground mica powders are used in large tonnage as a surface finish in roofing materials and as a bonding agent in wallboard joint cement. Common products such as paint, rubber, plastics and welding rods contain mica. Recent studies have also shown that mica powders can be added to portland cement in the preparation of concrete products, as they could improve the tensile strength of the concrete products. The potential and possible"

Jan 1, 1982

By J. A. Brusset

THE Greenhill mine of West Canadian Collieries, Limited, is situated at Blairmore, Alberta, and produces 2,500 tons per day of bituminous coal. On Monday, October 25th, 1943, smoke was discovered by a party of firebosses on their regular weekly inspection of air-ways. Probably the fire had been smouldering for several days but, as it had started on the outcrop at the top of an old raise filled with dirt, only a small quantity of smoke could filter through, and the plume of mist that crowns the fan at that season had prevented the fan-man from noticing it. This raise is only about 200 feet from the fan, and is 70 feet long between the fan-drift and the outcrop. It was impossible to prove the origin of the fire, as it had probably started several days before it was discovered, but it is possible that a careless smoker may have thrown a match into the opening at the outcrop, and that the old, dry timber had caught fire. The airways are in No. 2 seam, a bituminous seam 18 to 25 feet thick surmounted by shales and sandstones. Only 45 feet vertically above it is No. 1 seam, 12 feet thick, overlain by a strong conglomerate. In that vicinity, No. 1 seam had been worked out about ten years ago and the strata between the two seams are undoubtedly fissured. The pitch of both seams is 43 degrees.

Jan 1, 1945

By L. I. Kiss, S. Perron, S. Poncsák, A. Perron

Aluminium industry has an increasing interest in the diminution of the energy consumption of the Hall-Heroult process by the reduction of the anode bottom covering with gas. Electrically isolating carbon-dioxide bubbles, produced at the anode, increase the ohmic resistance of the cell. As the gas production rate is determined by the applied current density, anode covering can be decreased only by a faster evacuation of the gas from the inter-electrode space. Among others, the inclination and curvature of the anode bottom promotes the release of the bubbles and thus decreases the mean value of the covering. Indeed, anode, insert in the molten cryolite bath has a square shape with horizontal bottom. However, inhomogeneous anode consumption, electro-erosion, bath circulation and the inclination of the bath-metal interface modify this shape gradually during electrolysis. Anode bottoms become inclined with rounded comers. This concentrates the gas generation to the center zone of the anode. As the bubble layer cannot be observed directly because of the hostile environment and the opacity of the bath, real scale air-water systems are used to study the impact of the anode geometry on the anode covering and the bubble induced flow. However, the physical properties of such a system are different than that we can found in the real cells. A simulator using the Lagrangian description of the bubble layer has been built and presented in earlier papers. This tool was used to investigate the effect of the anode inclination on gas covering and bath velocity, for both C02-cryolite and air-water system. Results obtained for the second system were compared to experimental data .

Jan 1, 2006

By C. P. Verschuren, P. W. Kingston, W. F. Caley

"In recent years, there has been rapid growth in the use of natural stone building and construct ion products. The largest growing markets are for pre-fabricated natural stone panels for interior and exterior wall facing and flooring. This increased demand is attributed to advanced quarrying and processing technologies, renewed appreciation for the aesthetic appeal of natural stone, and to the superior durability of natural stone when compared to glass, steel, and concrete. Geologically, plutonic rocks, and to a lesser extent marble and limestone/dolostone, are used extensively for these applications. This paper details the economic structure of the dimension stone industry, describes the necessary characteristics of a stone quarry, and outlines the geological criteria which favour an economic quarry.INTRODUCTIONThe world building stone industry has remained relatively stable over the last 5 to 6 years. In contrast, the North American stone industry has experienced substantial growth during that period. The increased use of commercial granite is primarily responsible for this growth, where use as exterior wall veneer for commercial, industrial, and institutional buildings represents the largest and fastest growing market.This increased usage in the construction industry has been sparked by the application of new technologies in quarrying, processing and installation , ma king natural stone more competitive with man-made materials which are energy intensive to produce, and have risen dramatically in price. The development of safer, time-saving stone installation techniques has also appealed to the liability-conscience construction industry. Finally, there is a trend by designers and architects toward utilizing long-la sting weather-resistant building materials, and a renewed appreciation of the aesthetic appeal of natural stone. The other large user of granite is the monument industry of North America which, although it has decreased slightly in recent years, still consumes approximately 40% of all commercial granite produced. The local use of commercial marble has remained relatively stable, and North America still relies heavily on European sources and suppliers. There has been some concern over the use of marble for exterior applications in areas subject to acid rain, and in colder climates where the marble ma y be vulnerable to freeze thaw cycles. Despite these concerns, the greatest problem is not with the structural breakdown of marble but the inability of some marbles to retain their polished finishes in the se environments. As a result, there has been an increase in the use of granite at the expense of marble for exterior applications. Finally, commercial marble is used extensively for interior flooring, wall s, counter tops, furniture, sculptures, and stairway components"

Jan 1, 1989