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By Gordon A. Gross

During the last half century major steel industries of the world have become dependent on iron and manganese resources derived from siliceous ironformation sediments. More than two billion years ago vast amounts of iron and manganese were deposited in ironformation sediments on all continents and until recent years their genesis was considered to be a uniquely Precambrian phenomenon. Research work has demonstrated that the origin of the banded ironformations was related to major tectonic features and associated volcanogenic processes that were active throughout geological history. Similar sedimentary-tectonic environments are being explored on the seafloor where metalliferous sediments are forming today. Ironformations are now considered to be a major part of the stratafer group of stratiform metalliferous deposits. They developed in sedimentary basins in areas where deep tectonic fracturing intersected high thermal gradients in the earth?s crust and gave rise to profuse volcanism and the hydrothermal effusive discharge of metals in the vicinity of the volcanic centres. Concepts for the genesis and metamorphism of stratafer deposits as revised in the last half century have had a profound impact in the development of iron ore resources and have had a dramatic impact in the use of metallogenetic concepts for guiding exploration for other mineral resources. They are based on the tectonic history and stratigraphy in the sedimentary basins, the role of hydrothermal volcanogenic processes , as well as environmental and sedimentation factors which influence the deposition of silica, iron , and other metals that were emphasized in the past. Topics of special interest in the genesis of ironformation and stratafer deposits and for guiding mineral exploration are: biomediation in their sedimentation and genesis, the significance of metamorphism in the processing and beneficiation of iron ore and in the genesis of iron ore by natural enrichment processes, syngenetic concentrations of Mn, Ti, Cu. Zn, Pb, Ni, Co, REE, F, Ba, B, As, Hg, W and Au in ironformations and stratafer lithofacies, and the mobilization of gold and other elements by alkaline solutions during diagenesis of ironformation and other stratafer metalliferous sediments.

May 1, 2003

We describe a new method of characterising the effect of dissolved materials on the rate of coalescence of bubbles in aqueous media. Single bubbles were allowed to rise to meet the surface of an aqueous solution, and the time of persistence between arrival and bursting of bubble was measured as a function of solute concentration. A laser beam was placed just above the surface of the liquid, with a detector in the light path, so that any disturbance at the surface could be seen as a break in the beam. The arrival of a bubble at the surface could be detected from the behaviour of the trace on an oscilloscope, and when the bubble broke, another significant change in the signal could easily be seen. The time between disruptions was reported as the persistence time. The effect of a homologous series of n-alcohols (C1 to C8) on the persistence time was measured, in aqueous solution. It was found that with increasing concentration of a particular solute, the persistence time increased up to a point, and then declined. However the magnitude of the persistence time was found to increase with increasing numbers of carbon atoms in the molecule. Bubbles of 1, 2 and 3 mm diameter were used. Persistence time increased with increasing bubble diameter, the maximum values observed being of order 100 secs. For a given solute, the persistence (drainage) time increased with increasing bubble diameter. The concentration Cmax at which the maximum persistence time was observed, was found to be independent of the bubble size. It decreased uniformly as the carbon number increased, and was well correlated by the function y1/2 (dy /dc) -2 I dc)-2 . There was no apparent correlation with the surface excess at maximum persistence time.

Jan 1, 2006

By G. Q. Zhou, H. C. Liang, X. D. Zhao

"This study describes the strain behavior in vertical shaft lining (VSL) embedded in thick soil deposits and its application in assessment of concrete deterioration. The observed strain in VSL continuously decreased companied by a sinusoidal fluctuation due to the influences derived from negative skin friction (NSF) and temperature. The increase in strain increment between peak and trough at each year and compressive strain level as the servicing time continued and VSL depth increased implies that the concrete strength was attenuated, and this attenuation was significantly dependent on the existing compressive strain level in VSL. The reliability of the proposed approach was validated by Schmidt Hammer Technique (SHT) – based concrete strength, and is applicable in concrete assessment and then fracturing prediction of VLSs in thick soil deposits.Concrete strength, Field monitoring, Strain behavior, Vertical shaft liningINTRODUCTIONOver 100 VSLs in Southeastern China subjected to an unpredictable fracturing as shown in Figure1, and there are over 1,000 VSLs embedded in thick alluvium su?ering from challenges of damaging and potential fracturing (Cheng, Yang, Zhou, Li, & Hu, 1993; Zhou, Cui, Lv, Huang, & Chen, 1999; Li & Li,2005). Therefore, a reliable assessment of these VSLs is significant to the normal servicing of mine shafts and the recycle of underground space when these mine shafts were closed.The continuous increasing of NSF induced by the drainage of water–saturated deposits well interpreted such extensive fracturing phenomenon, and it is universally regarded as the governing indicator to determine the VSL stabilization (Cheng et al., 1993; Zhou et al., 1999). Based on this recognition, the fracturing prediction and VSL strengthening according to the field monitoring on hydrogeological characteristics, servicing environments, and mechanical behaviors of VSL were carried out (Zhao, Zhou, Zhong, Zhu, & Liang, 2009; Liang et al., 2009; Xie, Lv, & Wu, 2014). As known, the compressive strain level in VSL and the in–situ strength of VSL concrete were the main factors to perform such fracturing prediction. However, the existing studies in literatures were limited to the strain accumulating or releasing behaviors (Zhao, Zhou, Zhao, Kuang, & Hu, 2017), and lack of considering the VSL concrete strength and its attenuation. In this reported study, the in–situ monitoring data on the strain in typical VSLs and the VSL elevations between 2004 and 2014 were initially analyzed. Then, an observed strain behaviors–based approach was developed to quantitatively evaluate the VSL concrete deterioration."

Jan 1, 2019

By M. Wittke

"In the course of the extension of the railway network in Israel, currently the two 4.6 km long tubes of the Gilon Tunnels on the line from Akko to Carmiel are being constructed. The tunnels run through the limestones of the Bina- and Yirka-formations, which locally are karstified. The maximum overburden amounts to 160 m.The limestones are mostly horizontally bedded and vertically jointed. Occasionally also inclined joints exist. The tunnels cross various fault zones, which mostly strike at an acute angle to the tunnel axis and are steeply inclined. The karstic cavities which were encountered during tunneling have partially been filled by clay. In the vicinity of the fault zones, the rock has often been strongly jointed and weathered respectively. The two single-track tubes have a cross section with vertical walls and an open invert. The tubes are connected by cross cuts with a spacing of approx. 250 m.During the tender phase, WBI has elaborated the tender design for a joint venture of a Chinese and an Israeli construction company. After the joint venture had been awarded the contract, the preliminary and the detailed design have been elaborated by WBI and the construction works have been guided. On the basis of the geological description, rock mechanical models have been elaborated, followed by stability analyses on the basis of the Finite Element method. The tunnels have been excavated according to the shotcrete method. The support in most areas only consisted of a very thin shotcrete lining and radial bolts in the area of the roof. Depending on the degree of jointing and weathering, locally advancing support by means of spiles has been applied.The internal lining of reinforced concrete has been constructed in parallel to the heading of the tubes. Mucking and delivery of materials was carried out through the cross cuts.The breakthrough was achieved in April 2014 and thus within schedule. The predicted distribution of the excavation and support classes along the tunnel has been in good agreement with reality."

Jan 1, 2015

By J. E. Dutrizac

Mercury balances have been obtained for the flotation circuits at Pamour Porcupine Mines, Timmins, Ontario, and at Brunswick Mining and Smelting Corporation, Bathurst, New Brunswick. The mineral form of mercury in both deposits has been ascertained. At Pamour Porcupine, the mercury is approximately evenly divided among sphalerite, native silverelectrum and tetrahedrite-tennantite; at Brunswick Mining, this element is contained mostly in the sphalerite, although tetrahedrite (and possibly pyrite) also contains minor quantities.

Jan 1, 1979

By D. D. Campbell

The Hat Creek coal deposit s occur within folded and faulted Tertiary (Eocene) strata of the Coldwater Group, which comprises weakly lithified shales, siltstones and conglomerates underlying the floor and lower flanks of the valley of Upper Hat Cr eek . This upland valley,16 miles in length and 2-4 miles in width, is located within the eastern foothills of the Coast Mountains, 120 miles northeast of Vancouver, approximately midway between the towns of Lillooet and Ashcroft, in the Interior Dry Belt of British Columbia . Most of the valley floor is covered by till and glacial outwash deposits ranging up to 500 feet in depth. Became of this overburden cover , the majority of the data on the coal deposit have been obtained from diamond drilling done during 1974?76 by the property owner, B .C. Hydro and Power Authority. Because of the limitations imposed by the lack of out crop, the Tertiary geology at Upper Hat Creek is imperfectly known; however, it appears from correlation with other coal-bearing Tertiary remnants in the southern interior of the province that these remnants, including Upper Hat Creek, may represent preserved segments of the western shoreline of a Tertiary continental sea along which deltaic swamps developed and were sustained for unusually long stable periods, giving rise to the world's thickest known coal beds.

Jan 1, 1977

By F. Q. Su

Underground Coal Gasification (UCG) is a promising environmentally acceptable clean-coal technology. A typical UCG system has two wells drilled from the surface into a coal seam with some separation of injection from production. The wells are connected underground by various linking techniques. After creating a combustion reactor in an underground coal seam, air and oxygen flow through the injection well. Heat energy and gases are collected from the production well. As gasification progresses, the combustion reactor is moved along the linking hole. Using this process, the fracturing activity inside the coal seam serves an important role for enlargement of the gasification zone because the surface area oxidization increases continuously by coal cracking. For effective coal gasification, fracturing activity must be controlled. Moreover, excess fractures inside the coal seam and surrounding rock can induce gas leakage, underground water contamination, subsidence, etc. Therefore, monitoring and control of fracturing activity in underground areas constitute key technologies for efficient and safe UCG. To monitor fracturing activity, we conducted laboratory and small-scale field experiments of UCG using acoustic emission (AE) measurements. UCG model tests were conducted for linking and coaxial types UCG models. Coaxial UCG systems are compact and are anticipated for application in underground coal seams having a complex geological structure. The UCG model consists of a coal block molded in a steel canister (20 liter capacity) with heat-resistant mortar, with a linking hole or a coaxial-hole passing through the coal block. During coal combustion, coal temperatures, production gas contents, and AE activity were monitored under the control of injection-air and oxygen flow rates. Results show that the combustion propagated inside the specimen along the linking hole. Many AE events were generated during coal combustion. The AE activity was related closely to temperature changes inside the coal block. This AE generation apparently results from crack initiation and extension around the coal combustion area under the influence of thermal stress. However, comparing the results from UCG models of linking and coaxial types, the gasification of the linking type model showed an average calorific value as high as 11.3 MJ/m3. The coaxial type yielded an average calorific value of produced gas as only 5.79 MJ/m3. In the coaxial type of UCG model, the combustion region was limited to the area around the coaxial hole. The AE activity was lower than in the linking type model. For small-scale UCG field experiments, linking and coaxial types were tested at an open pit coal mine in Hokkaido, Japan. Using a linking type UCG, 58.2 kg coal was processed in 39 h, with the calorific value estimated as 11 MJ/m3. However, the coaxial type UCG processed 7.0 kg coal in 9 h, yielding an estimated calorific value of 6.0 MJ/m3. These tendencies resemble those of results of laboratory UCG experiments. Results of these experiments demonstrate that AE monitoring is a useful tool to evaluate combustion reactors for efficient and safe UCG systems. To develop a coaxial UCG system, results show that fracture control around combustion reactors is indispensable.

Aug 1, 2013

By Y. Chino

Cross-rolling, in which the roll axis is tilted by 7.5 degrees against the transverse direction, was carried out on a commercial magnesium alloy. The (0002) texture intensity of the cross-rolled specimen was lower than that of the unidirectionally rolled specimen. Also, the grain size of the cross-rolled specimen was smaller than that of the unidirectionally rolled specimen. As a result of the Erichsen tests at 433 ? 493 K, the press formability of the cross-rolled specimen was higher than that of the unidirectionally rolled specimen. The high formability of the cross-rolled specimen is attributed to both the reduction in (0002) texture intensity and the enhancement of grain refinement by the cross-rolling.

Jan 1, 2006

By R. A. Sudisman, T. Yamabe, M. Osada

"Geological material can be subjected to some different loading conditions, mainly due to three inter-related physical processes which are mechanical, thermal, and hydrological. Freezing and thawing process of rock that occurs in sub-zero temperature condition may contain some or all those three physical processes depended on its initial condition. Those inter-related physical processes may lead the ground into failures. Therefore, understanding the physical properties such as deformation process of geological material under freezing and thawing condition is required for the artificial ground freezing projects and engineering construction activity in the natural cold region.In order to study the strain characteristic of rocks during freezing and thawing process, a series of freezing and thawing experiments of core samples of three different rock types and mortar has been conducted under varying temperature from -20 °C to +20 °C. Four core sample types are Sandstone, Granite, Tuff, and Mortar with 50 mm diameter and 50 mm height, which were naturally dried before the freezing-thawing experiment. Freezing-thawing experiment was conducted by submerging the vinyl covered core samples into a temperature-controlled liquid coolant box. Firstly, temperature of liquid (brine solution) was set at -20 °C so that the temperature of subjected sample was decreasing to as low as -20 °C. And then the temperature of brine was returning to initial room temperature after the coolant system was stopped. Strain gauge and thermo couple were attached on the core’s perimeter to measure strains and temperature changes.Sandstone and Mortar samples show relatively similar results than other two samples. Both presents linearly shrink with the temperature decrease and expand almost to its initial condition with the temperature increase. Granite shows less-linear strain-temperature relationship during thawing process, while the Tuff sample shows abrupt strain increase during thawing process on the temperature higher than +10 °C. Thermal expansion value of each rock types were obtained by fitting the major strain-temperature relationship on -19 °C to +10 °C temperature range. Overall, anisotropic deformation was observed on the entire samples and possible mechanisms for each hysteresis characteristic are discussed, which need to be confirmed by further experiments."

Jan 1, 2015

By S. P. Lowe

Flotation testing of Flin Flon ore was started in the Denver laboratory of Complex Ores Recoveries Co. in March, 1926. There had been a considerable amount of flotation testing previously which had shown possibilities of success, and it was felt that, with the increased knowledge of flotation and the comparatively new reagents then available, flotation held out the best prospects for a successful commercial treatment of this ore. There remained available for this experimental work a small amount of the rejects from a thorough sampling of the mine and some ore from the mine dump.

Jan 1, 1930

By B. Lafrance, C. J. Beaumont-Smith, L. R. Jones

"Abstract - The Burnt Timber gold deposit is located in the Paleoproterozoic Lynn Lake greenstone belt of the Trans-Hudson Orogen, Manitoba. The deposit occurs along the Johnson shear zone, and is hosted by enriched and depleted tholeiitic volcanic arc basalts cut by feldspar porphyry dikes. The Johnson shear zone is a regional, belt-parallel structure characterized by the intensification of the regional S2 foliation. At the Burnt Timber deposit, S2 is folded by centimeter- to meter-scale, Z-shaped, F3 chevron folds that have an axial planar S3 crenulation cleavage. Within the 20 to 30 m-wide core zone of the shear zone, S2 and F3 are transposed parallel to S3 and the volcanic rocks are strongly sheared parallel to S3. The presence of a steeply plunging stretching lineation, together with dextral shear sense indicators along both S2 and S3 on horizontal surfaces, suggest that the Johnson shear zone is a dextral transpression zone. Gold was introduced in pyritic, biotitic, and carbonatized mafic volcanic rocks along the core of the shear zone. Mylonitic mafic volcanic rocks contain localized high-grade zones (=10 g/t Au) that differ from wider carbonatized, low-grade zones (<3 g/t Au) by the presence of deformed gold-bearing quartz-pyrite veins. High-grade zones are also associated with swarms of quartz-pyrite veins that cut across sericitized and carbonatized feldspar porphyry dikes, which acted as brittle, competent bodies during shearing. Gold deposition in the high-grade zones was controlled by the channeling of hydrothermal fluid along the core of the shear zone during shearing of the volcanic rocks, and brittle fracturing of the porphyry dikes. Sommaire - Le gîte aurifère de Burnt Timber est situé dans la ceinture de roches vertes Paléoprotérozoïque de Lynn Lake dans l’orogène Trans-Hudsonien, au Manitoba. Ce gîte est situé le long de la zone de cisaillement de Johnson et est encaissé dans des basaltes tholéiitiques d’arc enrichis et appauvris recoupés par des dykes porphyriques. La zone de cisaillement de Johnson est une structure régionale parallèle à la ceinture de Lynn Lake caractérisée par une intensité accrue de la foliation régionale S2. Au gîte de Burnt Timber, S2 est affectée par un plissement F3 en chevrons en Z d’échelle centimétrique à métrique associé à un clivage de crénulation de plan axial S3. Dans la zone centrale de 20 à 30 m de largeur au sein de la zone de cisaillement, S2 et F3 sont transposés parallèlement à S3 et les roches volcaniques sont fortement cisaillées le long de S3. La présence conjointe d’une linéation d’étirement à forte plongée et d’indicateurs cinématiques dextres sur les surfaces horizontales S2 et S3 suggère que la zone de cisaillement de Johnson est une zone transpressive dextre. L’or a été mis en place dans des volcanites mafiques altérées en pyrite, en biotite, et en carbonate au coeur de la zone de cisaillement. Les roches volcaniques mylonitiques présentent des zones aurifères locales à haute teneur (=10 g/t Au) qui diffèrent des zones à basse teneur (<3 g/t Au) par la présence de veines de quartz et de pyrite aurifère. Des zones à haute teneur associées à des essaims de veinules de quartz et de pyrite sont aussi notées dans des dykes porphyriques à plagioclase altérés en séricite et en carbonates; ces dykes se sont comportés comme des corps compétents durant le cisaillement. La déposition de l’or dans le zones à haute teneur a été contrôlée par la circulation du fluide hydrothermal au coeur de la zone de cisaillement durant la déformation des roches volcaniques et la fracturation des dykes porphyriques."

Jan 1, 2006

By Benoît Valley

Optimization of the mining sequence in terms of economics (maximizing net present value) often leads to multi-front mining methods generating pillars. Significant resources are tied up in these pillars, but mining them is often challenging. In order to improve our understanding of rock mass behaviour while extracting these pillars, an extensive monitoring program has been designed and implemented at Vale?s Coleman mine (Sudbury, Canada). The program focuses on existing and new technologies that have potential for monitoring deformation and rock mass property changes. It includes both active and passive methods: gravimeters, multi-point borehole extensometers, fiber optic strain meters, fixed and portable three-component seismic arrays, borehole imaging and sonic logging, and, repeated LiDAR surveys. This paper reports results from an initial project phase, when only a small amount of mining has taken place. The goal was to test and compare technologies in order to assess their sensitivity, accuracy, repeatability and suitability for underground mining conditions. Value is gained by having a broad range of monitoring devices running side by side, enabling comparisons and benchmarking.

Jun 1, 2012

By J. D. Stewart

One of the first important questions that should be settled on the opening of a mine or the development of a new deep is the system of haulage to be used, since the layout of the haulage-ways at the pit bottom, or, in case of a slope mine, the arrangement of the surface works, depends largely upon the type selected. Should it later become desirable to install a system of haulage of a type other than that for which the mine roadways were originally laid out, considerable difficulty would likely be encountered in its installation and with the result that it would in all probability be most unsatisfactory and expensive in its operations. It therefore becomes very necessary that full consideration be given the haulage problem at an early date in order that the type best suited to the mine conditions and the required outputs can be intelligently planned for. It is sometimes found, however, that no matter how well the mining engineer explores the seam to be developed, or how accurately he anticipates its eccentricities, there will still remain some unrevealed or unsuspected conditions, or shall we say obstacles, placed by Nature to prevent the too easy winning of her treasures and incidentally to frustrate or modify the application of the plan so painstakingly laid down on paper, and to adversely affect the cost estimate.

Jan 1, 1928

By Getu F. Biftu

There is general agreement among scientists that global surface temperatures have been increasing during the past decades. The increase in temperature is postulated to be the result of either an increase in greenhouse gases emission or climate variability (i.e., due to variations in sun or volcanic activity or El Nino and La Nina events) during past decades and may continue to increase. The effects of a predicted rise in the Earth?s surface temperature include an increase in average global evaporation and increase or decrease in precipitation (Bloomfield, 1992; Mann et al., 1991; Vinnikov et al., 1990; Gan 1995; Zhang et al., 2000a). The general circulation models (GCMs) project a global warming due to greenhouse effects of 1.5-4.5°C by the mid 2050s, with the most pronounced changes taking place in northern latitudes (Nicholls et al., 1996). However, similar predictions at a watershed scale or even a regional scale using GCMs are mot possible yet (Arnell et. al., 1996; Georgievskii et. al., 1996; Zhang et al., 2000a). Detection of historic trends, changes and variability in climatic variables is another indirect means of understanding potential future changes or variability at regional and local scales. The main objective of this paper is to review studies related to climatic change or variability and associated hydrologic changes at a regional scale and local scale, particularly those studies applicable to the Oil Sands Region (OSR) of Alberta. This paper identifies gaps in our current understanding of the hydrologic processes that may be affected by climate change; it discusses potential implications to developments in the OSR; and it explores mitigation opportunities including several that have already been implemented.

May 1, 2004

By Edouard Asselin, Tasawar Javed

This study was conducted as a part of ongoing work to characterize sulphide concentrate leach residues generated under CESL (Cominco Engineering Services Limited) and Vale pilot and demonstration plant medium temperature (150 °C) process conditions. Three different samples were analyzed. Derivative samples were prepared by extracting gypsum, sulphur and amorphous/poorly crystalline iron oxyhydroxide phases from the leach residues. Thermal behavior of the samples was studied by thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) in the temperature range 25 to 800 °C in both air and nitrogen atmospheres, with XRD analyses both before and after heating. Thermal transformation temperatures for different iron oxides/oxyhydroxides present in hydrometallurgical leach residues vary over a wide range which suggests the variable crystallinity of the phases. Raman spectroscopic analysis was carried out to help identify the type of iron phases in the residues. Furthermore, hydroxylamine hydrochloride (HaHC) and oxalate extractions were used to compare the fractionation of the amorphous/poorly crystalline iron phases in the residues. Given the compositions of the residues, any thermal events in the temperature range of 200 °C to 480 °C were attributed to amorphous/poorly crystalline iron phases.

Jan 1, 2014

By Euler De Souza

"The uninterrupted operation of a ventilation system is critical to ensure the mine meets its scheduled production and, as important, is vital to the health and safety of all personnel working underground. Those operating the mine ventilation system must have fundamental engineering training in the art of fluid dynamics and have a good comprehension and control of the mine ventilation network. Ventilation management by untrained and inexperienced personnel may result in serious consequences when the system becomes ineffective. This paper shares observations and experiences pertinent to the occurrence of upset conditions as a result of the improper design and operation of mine ventilation systems. A series of real life case studies are presented to describe disruptions to mine ventilation systems and the gradual deterioration of system operational efficiencies leading to eventual failure. Special focus is given to mistakes made and on the resulting serious consequences. The case studies also demonstrate how each upset condition was resolved, permitting the mines to safely resume production activities.INTRODUCTIONThe ventilation of operating mines is a continuously changing and evolving system; upset conditions will occasionally occur, but should be promptly resolved in order for the system to function properly, according to design, and in compliance.Those designing, managing or operating the mine ventilation system must have pertinent training and have a good understanding of fundamental ventilation concepts to be able to devise and implement engineering solutions to day-to-day challenges. Realistically, the operator must also have extensive practical experience and be able to effectively apply operating procedures, design criteria and ‘best practices’. They must be able to, on a daily basis, evaluate the mine ventilation system, determine and locate any problems, understand the causes of each problem, find a solution, and promptly and efficiently correct those problems.Ten case studies are presented to demonstrate how fundamental design or operational mistakes can lead to adverse conditions or to catastrophic consequences, how detailed on-site engineering assessments can be employed and how simple, low cost, engineering solutions can be implemented to successfully resolve the issues and return the ventilation system to compliance, permitting the mines to safely resume production activities."

Jan 1, 2019

By R. A. L. Drew, F. Jalilian, M. Jahazi

Joining of superalloy Inconel 61 7 with a foil interlayer using transient liquid phase bonding (TLP) technique was studied. Inconel 617 is a solid solution, Ni - Cr - Co- Mo alloy with an exceptional composition of high temperature strength, oxidation, carburization resistance and thermal stability. In this investigation, two bonding temperatures, 1065°C and 1150°C, and two interlayer thicknesses with joining times varying from 5 minutes to 24 hours were employed. Experiments were carried out using nickel base interlayer (A WS BNi-3) with boron as the melting point depressant (MPD) element. Joints were characterized using optical microscopy, SEM, FEG-SEM, EBSD, XRD and microhardness. The results indicated that the rate of elimination of the liquid phase with increasing the bonding temperature, holding time and decreasing the thickness of the interlayer increased. The main precipitates in the diffusion layer had platelike and blocky morphologies for both bonding temperatures and all holding times.

Jan 1, 2006

By A. Singh

Deformation structures after tensile and compression tests on Mg926Zn64Y alloy extruded at 250°C and 400°C are studied, in as-extruded and heat treated conditions. The icosahedral phase particles stimulate recrystallization during extrusion, resulting in fine grain size. Tensile and compression tests at room temperature show comparable yield strength, with a yield asymmetry ratio up to 0.98. c-type dislocations are observed in the grains near the submicron size icosahedral phase particles. The source of these dislocations is believed to be dissociation of <c+a> type non-basal dislocations. No dislocation pile-ups on icosahedral phase particles are found. {10 1 2} type twinning occurs in compression.

Jan 1, 2006

Shafts are the most important workings in the underground mines. Their technical state to a large extent determines the safety and efficiency of mining operations. However, in many cases periodically performed inspections show unsatisfactory technical state of the shaft lining (local defects, cracks, cavities, losses of the outer surface of the lining or, in case of the bricks, losses of the masonry). The most common cause of these types of damage is progressive deterioration of the lining material, impact of aggressive mine waters, impact of mining operations, deformation of the lining due to the rock mass saturation, seismic activity or periodic freezing of the lining in the upper part of a shaft. The paper presents legal requirements associated with the use of mine shafts in Polish coal mines as well as the ways and range of their control. Furthermore, examples of typical damage to shaft lining and ways to repair it, such as additional bolting, filling cavities or a wire mesh and shotcrete installation, are shown. In the final part, the paper presents a short example of a shaft, in which damage to the lining was one of the main causes of the shaft&apos;s failure. Due to the damage to the shaft lining, at the depth of approx. 65.0 m, the shaft was spontaneously filled with overburdened soil material. It resulted in a large crater to come to the surface, which, in turn, caused damage to the buildings and facilities present in the impact zone. On the surface the diameter of the crater was approx. 60.0 m, its depth approx. 11 m and the estimated volume was of about 30,000 m³. The disaster also caused disturbance in the ventilation of two neighbouring mines and the increase in methane hazard. Given the size of the crater, the measures to eliminate consequences of the catastrophe were undertaken in several stages.

Aug 1, 2013

By L. Wolofsky

"The Candego property is in Boisbuisson and Christie Townships, Quebec, about 13 miles south of Marsoui, a village on the north coast of the Gaspe peninsula, 80 miles east of the railhead at Matane. It was the first producing mine in the peninsula. Production to October 1954, when operations were suspended, totalled 68,497 tons of ore, which yielded concentrates containing 8,706,535 lb. lead, 5,870,272 lb. zinc, 355,526 oz. silver, and about 1,000 oz. gold. The property was acquired by the present company in the summer of 1955.The mine has been developed by seven adits, driven into the west slope of the valley of the Marsoui River. The river here is at an elevation of about 1,600 feet, and is roughly 1,500 feet below the level of the adjacent upland. Adit elevations range from 1,760 to 2,330 feet. Five of them are in one vertical zone, on what was originally believed to be a single vein. Past production has come from Nos. l to 5; the chief present high-grade ore reserves are in No. 7.The author's observations were made in adits Nos. 3 to 6, in several of the old pits, in the surface trenches, and on drill core, at various times between December 1952 and September 1953. Much of the surrounding area has been mapped by Jones (I) and McGerrigle (2) for the Quebec Department of Mines. H. M. Kingsbury served as consulting geologist to the mining company for several years.General GeologyThe Candego veins occur in Lower ( ?) Ordovician sedimentary rocks which form a strip about 15 miles wide along the north coast of the Gaspé peninsula. The series includes limestones, shales, and sandstones, mildly metamorphosed in places. Three miles south of the mine is the north contact of the granitic intrusive, regarded as Lower or Middle Devonian, which underlies the Tabletop Mountains area. This batholith is about 10 miles long, in a north-south direction, and about 4 miles wide. At Mount Albert, about 5 miles west of the Tabletop intrusion, is a group of basic rocks, amphibolites and serpentinized peridotites, thought to have been intruded at the close of the Ordovician."

Jan 1, 1949