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By C. A. Bruch, W. E. McHugh, R. W. Hockenbury

Commercially pure molybdenum specimens were irradiated in the Materials Testing Reactor for an estimated exposure of 1.9 to 5.9x10 20 thermal nvt. Prior to irradiation, the material was ductile in the tension test; whereas after irradiation, it was brittle. The results of tension tests conducted at various temperatures revealed that the transition temperature for this material had been increased from —30' to +70°C as a result of the radiation exposure. From metallographic studies, it is concluded that the embrittlement is due to submicroscopic changes which raise the flow stress-temperature curve of the material. PRIOR to ten years ago, the bombardment of metals with high speed heavy particles such as protons, deuterons, a particles, and neutrons was primarily of academic interest. These particles existed in extremely small numbers in a few laboratories and only under very special conditions. With the introduction of the nuclear power reactors, these particles are now available in enormous quantities and it has become important from a practical standpoint to learn how well metals withstand severe reactor radiations. The principal radiations of concern in reactors are neutrons and y rays, since the heavier charged particles exist only in limited regions of reactors. Seitz,' in a theoretical approach, has shown that all of these high energy particles, except y rays, have enough energy to knock atoms from lattice sites and that these knocked-on atoms have enough energy to cause additional displacements of neighboring atoms. The result of this process would be a lattice containing many imperfections in the form of interstitial atoms and vacancies. Hence, it would be expected that the properties of metals can be changed by reactor radiations, and such has been found to be the case. Only a limited amount of data have been published in the open literature,2,3 and these data have been for relatively low integrated-neutron-flux exposures. In general, one effect of reactor radiations on the mechanical properties of metals has been to increase strength and decrease ductility. It is now possible to irradiate specimens in the Materials Testing reactor at much higher fluxes and to higher integrated exposures than previously possible.' The data which are being presented here describe the effects of a relatively high exposure on some mechanical properties of molybdenum. Experimental Procedures Material: The molybdenum used in this investigation was obtained from the Climax Molybdenum Co. The two heats from which the material originated were melted under a vacuum of 5 to 30 microns and cast in 7 in. diam water-cooled copper molds. One ingot contained 0.061 pct C and the other 0.066 pct. Both ingots were hot worked by extrusion and rolling into % in. diam rods, after which they were annealed and straightened. The rods were subsequently heated to 1100°C in a hydrogen atmosphere and swaged to ½ in. diam rods at the Research Laboratory of the General Electric Co. The resulting material had an average hardness of 264 VPN, or 99.2 Rb, and had an average of 5000 grains per sq ml in the transverse section, Test Specimens: Substandard-size tensile specimens were prepared according to the specifications shown in Fig. 1. These specimens were used also for hardness measurements. The metallographic specimens were small disks which were polished, etched, and photographed at X1000 prior to irradiation. The field studied was

Jan 1, 1956

By Gerald C. Mathis

FERGUS County, Mont., shown in Fig. 1, is known for its once famous gold mines near the old towns of Gilt Edge, Maiden, and Kendall. But at Heath, a small farming community near the foothills of the Snowy Mountains, thousands of tons of gypsum have been mined since 1916. The value of the gold taken from the mines of Fergus County runs into millions of dollars; the value of the products made from the gypsum of the Heath mine is also in the millions. The gypsum mine will continue to produce for many years, while the gold mines are closed today. The Heath gypsum mine was developed by the Northwest Gypsum Co. in 1916. The products of the small mill built by this company were plaster, agricultural gypsum, and raw gypsum for cement manufacturing. The United States Gypsum Co. prospected the adjacent property in 1916 and 1917 by means of two adits and some exploration drill holes. During World War I, the company abandoned operations at Heath, but again became active in this area in 1928 hen it purchased all the property of the Northwest Gypsum Co. A long range program of expansion was begun with the building of a block plant and the purchase of additional land and mineral rights. A modern wall board plant was built in 1936. When the old wooden mill purchased from the Northwest Gypsum Co. burned in 1937, an all-metal calcining plant located at Blue Rapids, Kansas, was dismantled, moved to Heath, and erected on the site of the mill. In August 1951 a new mine was opened 3000 ft north of the mill. Rock is conveyed from the mine to the mill by an 18-in. belt conveyor. The Heath gypsum deposit lies at the base of the Ellis formation of Jurassic Age. The Ellis at Heath lies unconformably on the black fissle shale of the Heath formation of the Big Snowy Group, which is Mississippian in age. The strike of the gypsum bed is N45°E and the dip approximately 3" NW; the regional strike and dip of the area. The gypsum lies in a series of six layers separated from each other by thin seams of shale. The lower layer is composed of' gypsum and shale intermingled and is not of commercial grade. The upper five layers are high in purity, but only the middle four layers are mined on the advance, as the top layer is left for roof support. This top layer is mined on retreating operations at the same time the pillars are robbed. Total thickness of the gypsum layers varies from 12 to 14 ft. Fig. 2 shows the average thickness and arrangement of the layers. Mining Methods The mine was originally developed by driving an adit into the gypsum horizon. The Northwest Gypsum Co. mined in the top four layers, the top layer being split, leaving about 12 in. for roof support. A modified room and pillar method was used: entries were 15 ft wide and rooms varied between 20 and 30 ft and were turned on 90" from the entries. Crosscuts between the rooms left pillars from 10 to 20 ft square. The rock was loaded by hand into 1-ton mine cars and pulled to a central gathering point by mules; from the gathering point, mules or horses were used to pull the string of cars to the mill tipple. This method was continued by the United States Gypsum Co. from 1928 to 1937.

Jan 1, 1954

By B. F. Buie

For over 200 years meerschaum has been a significant item of trade between the Near East and countries to the west. Best-known for its use in making smoking pipes and cigar and cigarette holders, it is also used in making a variety of decorative and ornamental items. It is easily carved, and is given an attractive, lustrous finish by rubbing. No published specifications are known, but compact form, purity, uniform whiteness or light color, and uniform, porous texture appear to be requisites. Fig. I a shows the appearance of a piece of crude meerschaum from Turkey; Fig. lb a carved item; and Fig. lc, d, and e show the fibrous and porous texture as revealed by the scanning electron microscope. Neither a major industrial mineral nor a precious stone, meerschaum nevertheless holds a record of long-and continuing-association with art and personal affairs of man. It is also a mineral to which modem methods of exploration and production probably could be profitably applied. An interesting account of the preparation and use of meerschaum in the early part of this century is given by Sterrett (1907). Geology and Mining Mineralogy Meerschaum is recognized now to be the compact variety of sepiolite, the claylike variety of which is one of the minerals included in the chapter on clays. The word meerschaum, from the German meaning "sea foam," was in earlier times used synonymously with sepiolite, a word of Greek origin suggestive of the resemblance of the compact variety-then the only variety known-to cuttlefish bone. At one time meerschaum was used as the commercial name, and sepiolite for the scientific name. However, to think of meerschaum as the name by which sepiolite is known commercially is no longer valid, in view of the recent emergence of the earthy variety as a competitor of bentonite and other clay materials. Present tendency is to restrict the term meerschaum to the compact variety, and to use the term sepiolite as a more general name to include both the compact and earthy varieties. This is the terminology followed in this publication. Meerschaum typically is white to light gray, has a hardness of 2 to 2 ½ , conchoidal to irregular fracture, and specific gravity varying with porosity from about 2 to less than 1. The composition is somewhat variable,- but is near that determined by Schaller (1936) for sepiolite as 2MgO.3SiO2.4H2O. A more modern for mula based on X-ray determination of the crystal structure is given by Caillére and Henin (1961) as (Site) (Mg9)030(OH)6(0H2)46H20. The reason for the firm, compact nature of meerschaum, in contrast with the earthy variety of sepiolite, is not fully understood. It may be due to the presence of a very minor amount of some bonding material such as silica. Scanning electron microscope (SEM) photographs of a specimen from Turkey (Figs. lc-le) indicate that the meerschaum is composed predominantly, if not entirely, of crystalline fibers which merge into sheetlike forms in a complex, intertwined mass. Detailed X-ray and crystal structure data, as well as some data on thermal stability range, are given by Caillère and Hénin (1961) for the sepiolite family of minerals. Mode of Occurrence and Origin Most authors have attributed the origin of meerschaum to alteration of serpentine or other magnesian minerals. The occurrence in alluvium and other surficial deposits does not necessarily indicate that the alteration was supergene. In fact, hydrothermal origin appears more likely for some deposits, though not for all.

Jan 1, 1983

By Hamid Maleki

This study presents a historic overview of the role of mobile roof support (MRS) technologies in improving stability and worker safety and presents the results of recent field evaluations of the MRS load rate monitoring device and other remote deformation-monitoring techniques. Field studies were implemented at two sites in cooperation among researchers from the National Institute for Occupational Safety and Health (NIOSH), Maleki Technologies, Inc., and J. H. Fletcher & Co. The objective of the field programs were to (l) study the interaction between MRS's and coal mine strata and (2) develop and test suitable monitoring systems for assessing roof and pillar stability. An MRS consists of a roof canopy, four hydraulic cylinders, a caving shield canopy, and associated electromechanical systems mounted on crawler tracks. The machines are controlled by radio from a remote location and operate on self-contained power units. Typically, MRS's have capacities of 5,340 and 7,120 kN (600 and 800 tons). In comparison to posts, an MRS is capable of maintaining the yield load after significant amounts of roof-floor deformation. Because the mining cycle is accelerated, MRS's help reduce the potential for time-dependent roof falls. MRS performance has been monitored in the laboratory under controlled static loading conditions and in the field under deep, two-scam mining conditions. Laboratory studies have quantified support capacity and system stiffness as a function of machine height. Field investigations have focused on determination of optimum operating conditions and development of warning systems that indicate excessive load on the machine and/or impending roof-pillar stability problems. Analyses of field data show that roof instabilities are influenced by (1) pillar failure, (2) pillar yielding, (3) mine seismicity, (4) geologic structures, and (5) panel layout designs and mining practice. Pillar yielding and failure (unloading) and seismicity can be conveniently monitored by the load rate monitoring device, but for consistent detection of roof falls, additional deformation measurements directly within the cuts ate needed.

Jan 1, 2001

By Charle Lawrence, Murray E. Blanchard

"A significant addition to Canada's commodity export transportation capabilities is being built by Ridley Terminals Inc. on Ridley Island in the Port of Prince Rupert on British Columbia's north coast.Site preparation began in early 1982. By the end of 1983 the terminal will be receiving coal from two major new mines being developed in B. C.'s massive $2.5 billion northeast coal development.The RTI terminal will have initial capacity to transfer 12 million tonnes of coal a year from railcars to storage and to ships. Capacity will be doubled to 24 million tonnes as market opportunities are developed.The challenge of building this $220-million facility in less than 24 months, the benefits Canada has received from the work the project is generating, and the long-term faith in Canada that this project represents, are all part of the excitement which surrounds the Ridley Terminal and northeast coal developments.RIDLEY TERMINALS INC. (RTI) is building a very significant addition to Canada's commodity export transportation capabilities. The facility, on Ridley Island at Prince Rupert, on the north coast of British Columbia, is a key link in British Columbia's northeast coal development which in itself is a massive undertaking involving investment of some $2.5 billion. The entire project is making a substantial contribution to Canada's economy at a time when such contributions are sorely needed.The development is creating employment, not only in British Columbia where its various parts are being created by mining companies, railways and others, but also across the country where suppliers are manufacturing a wide variety of good s and equipment for the development's participants.The RTI terminal is no exception. It is a critical cog in this mega project's large transportation system and its construction is contributing substantially to job creation and to other economic activity, in the Prince Rupert area and in many other parts of British Columbia and the rest of Canada."

Jan 1, 1983

By B OÆNeil

The Trent-Severn Waterway is a 386 km long navigation route through central Ontario between Lake Ontario and Georgian Bay, and is operated by the Parks Canada Agency. Its primary focus is to pass recreational boats through a system of 44 locks. The Big Chute Marine Railway (BCMR) is one site in the system that provides transportation for boats. The BCMR carriage is used to transport boats and their passengers on the inclined railway a distance of 230 m over a natural barrier from one body of water to another, with an elevation difference of 18 m. The unique feature of the haulage system used in this application is the variable angle of the incline from about 20 per cent rise changing to horizontal and followed by 20 per cent decline. In such conditions, unlike as in standard incline haulage, special configuration of hoists and drives is required. On the uphill part of the track, there is a need to have a motoring mode, on the downhill part a regenerating mode and on the horizontal part a combination of motoring and regeneration is required. The original system was built in 1978 and employed four 100 hp dc drive mine hoists to haul the 100 tonne conveyance loaded with 90 tonnes of boats. Due to failures and operational problems with the original system, in 1999 Parks Canada awarded a turnkey contract to ABB for a new, modern system of four single drum hoists. The new system was put into operation in 2000, only six months after receiving the order. The hoists are controlled by digital drives and a digital control system. Due to dramatic changes in the load conditions for individual hoists involved, the new system features many interesting solutions like changing drive modes from speed to torque control and a multiple, regulated braking system. It is a unique hoisting system, which could be also used in mining applications.

Jan 1, 2005

The products of Lower Miocene calc- alkaline activity on the east coast of Northland, New Zealand are described and contrasted with coeval rocks of the northern North Island. These rocks, the Eastern Volcanic Belt (EVB), occur in four main centres aligned north-west to south east as either plutonic/hyabyssal bodies or as agglomeratic piles and dyke intrusions. Significantly the plutonic members always occur to the north-west of the volcanic members, probably indicative of differential uplift along faults (upthrown to the north) aligned perpendicular to the EVB. A full basalt-rhyolite (diorite-granodiorite/ adamellite) spectrum is represented, with a temporal progression towards the silica-rich endmembers indicated by cross-cutting field relationships. Modal mineralogy parallels this trend, consisting of two-pyroxene, hornblende, biotite, quartz/alkali feldspar modal assemblages, and with rare occurrences of olivine and garnet-bearing volcanic phases. Chemically the EVB is medium-K, calc-alkaline (with respect to AFM and total-Fe/MgO vs. Si02 indices) and quartz and hypersthene normative. The thirty two available K-Prisotope dates indicate that activity was largely confined to the Lower Miocene (24Ma-16Ma), with an apparent younging towards the south east. Initial B7Sr/e Sr ratios (0.70335- 0.70679) are indicative of a continental- arc-type setting, however it is unlikely that a straightforward tectonic reconstruction for this part, of the Pacific Margin is possible. Evidence from xenoliths, both petrologic and isotope, within EVB magmas and from regional geologic studies suggests that hypotheses pertaining to a volcanic arc sited over a subduction zone may hold little relevance in this case. The review concludes that the EVB developed from the partial melting of a geochemically evolved lower crust as indicated by xenolith evidence. This occurred in response to thickening initiated by a short-lived obductive event in the uppermost Oligocene, and controlled spatially by pre-existing basement structure. Intra-suite chemical and mineralogic variation reflects not only crustal variability, but localized differences in physico-chemical conditions best illustrated by the rare occurrences of olivine and garnet.

Jan 1, 1987

In the U.S. coal mining industry, a large cohort of miners is at or nearing retirement age. As these miners retire, there will be a need to hire and train thousands of new and most likely younger workers. Moreover, a large portion of safety trainers will also require replacement due to retirement. In a speech before the U.S. House of Representatives (2004), Bruce Watzman, Vice President for Safety, Health and Human Resources for the National Mining Association said, “[W]e will need to replace a major portion, approximately 50%, of the underground coal mining workforce within the next 5–7 years.” The large influx of new mine workers, along with the deficit in safety trainers, creates the challenge to provide consistent and effective safety training. Given the expected high turnover of the mining workforce, it is very likely that incoming workers will have much less experience than those leaving the workforce. Unfortunately, inexperienced miners have been shown to incur the highest rate of injuries. The piece of machinery most associated with these injuries is the roof bolting machine, which accounts for 56% of machinery-related injuries in underground coal mining. The National Institute for Occupational Safety and Health (NIOSH) has released a new report entitled “Roof Bolting Machine Operators Skills Training for a Walk-Thru Roof Bolter: Trainer’s Guide” (IC 9489). It is designed to help safety trainers develop struc-tured training for new operators of walk-thru bolting machines. This resource will help trainees learn, understand, and apply knowledge and skills. Included in the trainer’s guide are the following tools: [ ] a six-part DVD video series, a skills check survey, talking points, and a complete job training analysis. Also included is an exercise to help trainees learn more about their mine’s roof control plan, as well as a list of supplemental training and reading materials. On-site trainers can modify this guide to fit their particular mine conditions, machines and equipment, and work procedures. The goal of every coal mine safety professional is to increase safety awareness and make mines a safer place to work. The Walk-Thru Bolting Machine Trainer’s Guide will help teach new miners skills to create a safer working environment that will ultimately prevent or reduce on-the-job injuries. Safety trainers can also use the ideas and concepts from this guide to develop their own training skills for the safe operation of other pieces of underground coal mining equipment.

Jan 6, 2007

By D. H. Steve Zou, Cui Lin

"This paper first discusses the basic attributes of sustainable mining and the responsibilities of various steak holders including mining companies, governments, and engineers. It is followed by a brief overview of the current practice on regulations, inspections, waste management and mine closure planning in Canadian mining industry. A case study is then presented as an example of sustainable mining where mine planning, mineral recovery, environment protection, reclamation and community development were integral parts of the overall strategy. A comparison of the mine site before and after mining is made to demonstrate the ""best practice"" in modern mining.Sustainability in Mineral Resource Development Extraction of mineral resources and other natural resources on the Earth has been and will continue to be an essential activity necessary to support human’s life. We live on the planet and depend on the available resources to survive. The extracted materials form the base to support modern life. However, we must be aware of the fact that mineral resources are limited on the Earth and may not last forever. Every time we extract one ton of materials, there is one ton less. They are not able to regenerate or regrow. One can ask a simple question: How long will they last? Or, is there anything left for our great grandchildren and many generations to come? The answer is not simple. Some minerals have become scarce or about to deplete. Some minerals may last longer. The reserve of a type of minerals depends on what we have discovered and the minable amount depends on accessibility and technology we have. Even if there are minerals in the deep ground, we may be limited by our technological capability. At the same time, we also need to understand the action of mineral extraction from the ground and the consequences of that action. Mineral extraction is a very hard work. We must break the ground to extract the ore, either through surface mining or underground mining. This action means disturbance of the land where we live. The disturbance is much more visible in surface mining than underground mining. The disturbed land, if not properly reclaimed after mining, is not going to be reusable. The very purpose of extracting minerals from the ground is to support our life but the action has a negative impact on our life. How can we reduce and limit disturbance of land from the action of minerals extraction? How can we make the disturbed land reusable? These issues must be properly addressed and a balance achieved."

Jan 1, 2017

By S. Litke

Elemental sulfur was stockpiled at the Mount Polley Mine for use as a source of sulfuric acid as part of research into leaching copper from oxide ores, but the project did not proceed beyond an initial pilot- scale evaluation. Since placement, the sulfur has oxidized and some sulfuric acid leached into the underlying rock. The reaction of the acid with these underlying materials has been studied as part of an evaluation of the effects of leachate from the pile. The rock underneath the sulfur pile is composed dominantly of primary and secondary alumino-silicates with less than 1% carbonate (calcite) and iron sulfide (pyrite). In its unaltered condition, the rock is classified as non-acid generating. Conceptually, it was expected the sulfuric acid would be neutralized by the rock to varying degrees resulting in a series of pH-controlled weathering fronts progressing from leached near the contact with the sulfur pile (pH <3), to active neutralization by silicates (pH 4–5), to active neutralization by carbonates (pH >7). The rocks underneath the pile were sampled to determine the extent to which the rocks had reacted and their long-term stability after removal of the acid source. INTRODUCTION When rock is blasted and excavated to facilitate mining ore, it is typically placed and stored on the surface in piles. The resulting drainage may have a neutral to basic pH (i.e., non-acidic drainage) or a low pH (i.e., acid rock drainage, ARD) depending on the mineralogy of the rock being stored in the piles. Acid- base accounting (ABA) can be used to characterise the two types of rock: potentially acidic drainage generating (PAG) and not potentially acidic drainage generating (NAG) (Price, 2009). According to Price (2009), NAG is defined as having an excess of neutralization potential (NP) in the rock in the form of calcium carbonate-like minerals when compared to acid potential (AP), i.e., a Neutralization Potential Ratio (NP/AP = NPR) greater than 2.0, whereas PAG is classified as having an excess of AP (i.e., an NPR less than 1.0). This is a conservative estimate and may be slightly modified depending on the mineralogy at specific mine sites. Rock with an NPR of 1–2 is also capable of generating acid (Price, 2009) and, depending on the mineralogy, may also be classified as PAG. Drainage from PAG material can generate acid immediately, or many years after it has been exposed to surface conditions. Disposal techniques depend on the category (i.e., NAG or PAG) and reactivity of the rock stored in the piles.

Jan 1, 2019

By H. Rafiei Renani, C. D. Martin

"The Cohesion Weakening Friction Strengthening (CWFS) is adopted in numerical analysis to capture the observed progressive failure of hard rock pillars. As a case study, pillars at the Elliot Lake mines with width to height ratios of 0.5 to 3 were analyzed in FLAC3D. Pillars with width to height ratios of 0.5 and 1 show a very similar strain softening behavior while with width to height ratios of 2 and especially 3 indicated prolonged strain hardening. The CWFS model successfully captured the mechanism of progressive failure observed in hard rock pillars including initiation of spalling at the corners, progress of spalling towards the centre and formation of hour-glass shaped pillar, and eventually shearing through the width of pillar. Both the CWFS model and site specific empirical formula successfully separated the stable and failed cases in the Elliot Lake mines. While both models are in reasonable agreement for width to height ratios of less than 2, the empirical formula gives increasingly lower strength values for wider pillars which may result in excessively conservative and uneconomical design.INTRODUCTIONPillars are the portion of in situ rock left between the adjacent openings to maintain the stability of excavations. Conditions of equilibrium require that the loads previously carried by the excavated rocks be transferred to the pillars resulting in elevated stresses within the pillar. Hence, prediction of the behavior of pillars under these loads is important for underground design. Determination of the strength of pillars is a classic subject in underground mining. In conventional mining methods such as room and pillar operations, economic incentives point towards higher excavation ratios i.e., leaving smaller pillars between the mined excavations, while safety and stability requirements favor wider stronger pillars. In some mining methods such as caving operations, the problem is even more challenging. On one hand, the whole operation is directly dependent on the proper continuous flow of caved ore between the drawpoints which requires optimizing the spacing between drawpoints and thereby often leaving narrower pillars. On the other hand, the pillars should be wide enough to ensure the safety of mining operation. Both the blockage of drawpoints as a result of wide pillars and uncontrolled failure of narrow pillars can jeopardize the investments and mining operation.Therefore, design of pillar poses a somewhat unique challenge to rock engineers where simple conservative approaches frequently used in other design methods are no longer acceptable. The behavior of pillar under elevated loads should be predicted accurately."

Jan 1, 2015

By L. S. Darken

It has been known for sometime that in an ionic lattice, such as that of Ag,S or FeO, the migration velocity of the anion may differ markedly from that of the cation, the cation being usually the more mobile. It has been shown, for example, that during the formation of silver sulphide tarnish on silver, the tarnish layer grows principally by the motion of silver cations through an essentially stationary silver sulphide lattice. Similarly, the growth of wüstite scale on iron proceeds principally by motion of iron ions, this being accomplished with the aid of vacant iron lattice sites into which the iron may readily move. Likewise investigations of solid solutions of various salts show that there is usually considerable difference in the mobility of the different cations. Measurements of the mobility of various metals in liquid mercury indicate that the various metals move at different rates relative to the mercury. In view of the foregoing it seems reasonable to suppose that when any single phase solution is acted upon by a field, the atoms of different elements respond in different ways; in particular, that the force arising from a particular concentration gradient in a binary alloy would cause the atoms of one component to move with a drift velocity which is in general different from that of the atoms of the other component. The recent experiments of Smigelskas and Kirkendall&apos; support this viewpoint, since they found, in essence, that during diffusion in alpha brass zinc moves appreciably faster than copper. This was evidenced by the relative motion of inert molybdenum wires. Such a phenomenon is incompatible with the place interchange theory of diffdsion proposed by several authors, most recently by Bir-chenall and Mehl.2 This theory has, however, also been questioned3v4 for other reasons, principally because of the high energy required for direct atomic interchange. The rather large difference between self-diffusivity, as determined by tracer technique, and mutual diffusivity, as determined with the aid of another element at low concentration, might also be interpreted as favoring the above idea; however. Birchenall and Mehl have pointed out that there is another possible interpretation of this difference; this is discussed later. A rather interesting and pertinent observation was made by Schwartz, who noticed that tungsten lamp filaments, heated by direct current, commonly fail by necking down in the region at the temperature gradient near the positive end, with a concomitant swelling at the corresponding position near the negative end. He introduces considerable auxiliary evidence to show that this phenomenon is occasioned by the motion of tungsten cations which migrate in the high temperature region from the positive end toward the negative end. The mechanism of this migration is not clearly understood. If, however, this experimental evidence be accepted, we are forced to conclude that alloying elements in the tungsten may migrate by the same or a Similar mechanism, whatever it may be, at a greater Or lesser rate, thus giving rise

Jan 1, 1949

By Donald Whittaker

Severe climatic conditions in mines are normally associated with working at depth. More precisely, it is a matter of working in regions of high strata temperature, since, for example, some coal mines in the Ruhr have strata temperatures at 1000 m which are matched only at 3 times that depth in the South African gold mines. In Britain we are perhaps fortunate in encountering strata temperatures in our deeper coal mines some 10-15 K lower than at the same depth in the hot mines of the Ruhr. Nevertheless the problems of high temperatures and humidities in UK mining operations, which in the past have been confined to a few specific sites, have in recent years become more widespread, and there is every reason to suppose that the trend will continue. Clearly strata temperature is not the only .causative factor. Long ventilation circuits serving districts remote from the shaft must also play a part, while the heavy use of machinery and the rapid, rates of excavation of modern mining methods are obviously important. It is necessary to understand the mechanisms of all such factors, and to measure their magnitudes and fluctuations, if remedial measures are to be properly designed or predictions made which are accurate enough to be of use in ventilation planning. This paper presents the results of a long-term (and continuing) investigation carried out in several mines to measure the major sources of heat and moisture on longwall districts and trunk conveyor roadways. The variation with time of these sources is reported, and the resultant effect on the climate is considered. In their investigations of the heat exchanges occurring in a whole mine Oakes and Hinsley (1955-56)1 listed and estimated the magnitudes of a large number of heat sources. Some of these, namely autocompression of the air in the shaft, diesel engines and compressed air mains, do not apply to the present investigations, which refer to longwall districts with conveyor transport and no compressed air supply. Others, such as oxidation of coal and, desorption of methane, have not been taken into account in the measurements, but are discussed later. One other source, the importance of which was pointed out by Gracie and Matthews (1975)2, is the coal on the conveyor, a form of strata heat emission, but one which is strongly dependent on the rate of coal production. The heat emissions measured in the present investigations were the energy consumed by electrical machinery, the heat conducted from the strata and the heat lost by the conveyed coal. Most of the emitted heat was removed from the district by the ventilation air, and was measured by continuously recording the enthalpy of the air at fixed stations. The heat removed by service water, supplied for machine cooling and dust suppression, was also measured. Account was of course taken of the relatively minor changes in level around the districts, in terms of the potential energy gained or lost by the coal and by the ventilation air (autocompression).

Jan 1, 1980

By L. S. Darken

It has been known for sometime that in an ionic lattice, such as that of Ag,S or FeO, the migration velocity of the anion may differ markedly from that of the cation, the cation being usually the more mobile. It has been shown, for example, that during the formation of silver sulphide tarnish on silver, the tarnish layer grows principally by the motion of silver cations through an essentially stationary silver sulphide lattice. Similarly, the growth of wüstite scale on iron proceeds principally by motion of iron ions, this being accomplished with the aid of vacant iron lattice sites into which the iron may readily move. Likewise investigations of solid solutions of various salts show that there is usually considerable difference in the mobility of the different cations. Measurements of the mobility of various metals in liquid mercury indicate that the various metals move at different rates relative to the mercury. In view of the foregoing it seems reasonable to suppose that when any single phase solution is acted upon by a field, the atoms of different elements respond in different ways; in particular, that the force arising from a particular concentration gradient in a binary alloy would cause the atoms of one component to move with a drift velocity which is in general different from that of the atoms of the other component. The recent experiments of Smigelskas and Kirkendall&apos; support this viewpoint, since they found, in essence, that during diffusion in alpha brass zinc moves appreciably faster than copper. This was evidenced by the relative motion of inert molybdenum wires. Such a phenomenon is incompatible with the place interchange theory of diffdsion proposed by several authors, most recently by Bir-chenall and Mehl.2 This theory has, however, also been questioned3v4 for other reasons, principally because of the high energy required for direct atomic interchange. The rather large difference between self-diffusivity, as determined by tracer technique, and mutual diffusivity, as determined with the aid of another element at low concentration, might also be interpreted as favoring the above idea; however. Birchenall and Mehl have pointed out that there is another possible interpretation of this difference; this is discussed later. A rather interesting and pertinent observation was made by Schwartz, who noticed that tungsten lamp filaments, heated by direct current, commonly fail by necking down in the region at the temperature gradient near the positive end, with a concomitant swelling at the corresponding position near the negative end. He introduces considerable auxiliary evidence to show that this phenomenon is occasioned by the motion of tungsten cations which migrate in the high temperature region from the positive end toward the negative end. The mechanism of this migration is not clearly understood. If, however, this experimental evidence be accepted, we are forced to conclude that alloying elements in the tungsten may migrate by the same or a Similar mechanism, whatever it may be, at a greater Or lesser rate, thus giving rise

Jan 1, 1949

By C. Dodds, R. S. Ferrari-John, The University of Nottingham, G. Dimitrakis, J. Katrib, A. R. Batchelor

"Sorting technologies have the potential to reduce energy use in comminution by rejecting uneconomic ore before feed material enters the mill. However, a major challenge for sorting porphyry copper ores is providing a basis of discrimination between valuable and non-valuable fragments, due to their complex mineralogies and textural features. Microwave heating in combination with infra-red detection (MW-IR) has been shown to provide upgraded feedstock for certain ores at bench scale. Selective heating of copper sulphide minerals compared to the gangue leads to an increased thermal response for valuable fragments, providing the basis for sorting.Rapid scale up of MW-IR from bench scale to a 100 t/h continuous pilot plant facility has been facilitated by the design of microwave choking structures to allow continuous operation at industrially meaningful throughputs, whilst meeting health and safety and electromagnetic compliance standards, and the integration of materials handling with electromagnetic systems.Laboratory batch testing on a pilot scale microwave system has been undertaken to investigate the thermal response of copper ores under industrial conditions, at microwave energy inputs up to 1 kWh/t. These results provided the operating window and recommended test conditions for the continuous pilot plant. Sortability curves predicted in the laboratory are in good agreement with separations achieved during continuous pilot plant operations. The potential microwave sortability of a number of ores has been studied, allowing informed decisions to be made about potential ore candidates based on mineralogy. Future development of the technology will be underpinned by the creation and validation of scale up concepts for 1000 t/h operations. Understanding the value proposition for individual sites/applications will be central to unlocking the potential economic and environmental benefits of microwave sorting."

Jan 1, 2016

By R. J. Sullivan

DURING the past twelve months the Loudon pool of the Eastern Interior Coal Basin has become established as one of the two largest discoveries since the revival of exploitation in the Illinois region and now occupies a position among the important pools of the United States. On Aug. 1, 1939, production averaged 54,000 bbl. per day from 990 wells, having accumulated a total of 10,305,000 bbl. Its very active develop-ment promises to continue for fully another year. It is the site of one of the industry&apos;s most singular large-scale gas-injection programs. LOCATION AND RESERVOIR CHARACTERISTICS At present the pool embraces an area 15 miles long by 3 ½ miles wide in eastern Fayette County, along the western rim of the now well-known Illinois Basin&apos;s deeper part, through townships 6, 7 and 8 north and ranges 2 and 3 east of the Third Meridian. It is the northernmost, and most prominent, productive structure of a group extending over a 50-mile trend southward to the Dix pool of Jefferson County. Three horizons have been proved to carry production-namely, the Weiler sandstone at 1390 ft., the Paint Creek sand at 1460 ft. and the Benoist or Bethel, at 1500 ft. Geologically, they fall in the Chester series of the upper Mississippian system, where much of Illinois&apos; early-day oil was found, having been laid down in shallow off-shore waters as a part of the vast delta deposit underlying central Illinois and parts of Indiana and Kentucky. As a result of this type of sedimentation, followed by repeated uplifts and warping along an anticlinal axis, differ-ential deposition of sands and shales contributing to great irregularity took place. This is further reflected by wide variations in permeability, porosity and thickness of all the sands and, accordingly, in the producing characteristics of wells. Permeabilities range as high as 550 millidarcies, with the average commonly lying between 60 and 100. For the three pay horizons the mean porosity is 18 per cent, at a calculated water saturation of roughly 30 per cent. The Weiler sand has an average thickness of 25 ft., the Benoist of about 23 ft. and the Paint Creek of approximately 18 ft. Of these three productive formations the Benoist

Jan 1, 1940

By David Cooper, Susan Robertson, William Wiehagen, Launa Mallett, Charles Vaught, Joan Dickerson, Richard Conkle, ROBERT PETERS, Mike Brnich, Charles Urban

This trainer’s guide is designed as a reference manual. The purpose is to offer information and examples to skills trainers to assist them in structuring training for new operators of Walk-Thru roof bolting machines. Trainers can use this manual as a resource for helping trainees learn, understand, and apply knowledge and skills. In this sense, the guide is not prescriptive. It is designed to offer information and trigger ideas on what might be done to accelerate learning to those who are new to the roof-bolting task. On-site trainers can modify this guide to fit their conditions, machines and equipment, and work procedures. They can integrate roof control plans, company policies and procedures, and operators’ manuals from the manufacturers of the original equipment into this guide. Every trainee is different and will come to the job with varying levels of relevant knowledge and skills. The trainer’s decisions on where to start, how to organize the on-the-job and classroom training portions, and when and how to offer different aspects of the training will be based on (1) a pretraining assessment of the trainee’s knowledge and skills and (2) the trainer’s experience in conducting skills training. The “Skill Check” section might be useful for deciding where training should start among miners who have underground experience but limited knowledge of roof-bolting techniques. Every job carries a learning curve and likely has a number of “teachable moments” where significantly new knowledge and skills can be learned. The videos on the DVD that accompany this guide can be shown at the beginning of training to give trainees an idea of what the job entails and related requirements. They can also be used within the training cycle (after the trainee has some experience in the job) to reinforce key points or as a trigger for eliciting questions about particularly difficult parts of the job. The video segments are meant to be visual models of good performance. They are designed to elicit discussion on good (lower risk) ways to do the job. In this context, they can be used very creatively at different times within the training cycle. The section on “Talking Points” offers a number of questions that can be used in the classroom to support and elaborate on certain aspects of the job duties. If the trainee has a fair amount of underground experience, some of the questions can also be used to support the pretraining assessment (i.e., skill check) of knowledge and skills. Likewise, some of the questions can also be used while teaching on the job to reinforce key points affecting safety, production, or maintenance. The section dealing with a mine’s roof control plan should be used at various times in the training cycle to make sure the trainee understands the plan and knows how to apply it in performing the job. The supplemental materials offer additional resources that can be used to support initial job training or follow-up. Learning continues well after an individual has been trained. The supplemental materials can help reinforce good operating skills and provide an opportunity for further discussion on better ways to do the job.

Jan 8, 2006

By Louise Corriveau

A Targeted Geoscience Initiative transect in the eastern Grenville Province reveals an extensive VHMS-style cupriferous hydrothermal system among rhyolitic pyroclastic rocks of the Wakeham Group at La Romaine, Québec. The volcanic rocks outcrop sporadically along a < 10 km-wide by about 100 km-long belt correlated with the south-eastern extension of the Wakeham Group. This belt occurs among voluminous, magnetite-bearing, granitic gneiss. At Lake Musquaro, 1.51 Ga metarhyolitic to dacitic lapillistones and flows, locally with aluminous nodules and veins, are intruded by 1.49 Ga feldspar porphyries. This volcanic package was deposited on typical Wakeham Group arenite (< 1.52 Ga) interbedded with nodular, muscovite- and fibrolite-bearing gneiss, and minor marble hosting finely layered garnetiferous hornblendite, garnetite and magnetite-bearing coticule. The latter are interpreted as meta-exhalite and with the associated albitite (sodic alteration), aluminous veins (hydrothermal leaching) and magnetite-rich granitoids, they are key elements in the search for concealed mineral deposits in this area. At La Romaine, to the south, 1.5 Ga lapillistones outcrop structurally above metasediments and below a composite amphibolite unit of uncertain origin (lava or sills) with magnetite-rich (BIF?) units. An extensive zone of aluminous gneiss, with lapilli textures, provide evidences for severe hydrothermal leaching of the volcanic rocks prior to metamorphism. An adjacent siliceous vein-textured unit likely represent a zone of intense silicification (74 wt.% SiO2), while aluminous, hematite to magnetite-bearing veins in adjacent felsic gneiss (tuff?) preserve evidences for the sequence of alteration events. Despite granulite-facies metamorphism, the main characteristics of the amphibolite unit persist along the entire belt. This competent unit likely served as a cap rock; the garnetite, diopsidite and hornblendite it hosts provide effective guides to the sites of fluid discharge and mineralization. A number of Cu showings, modest in size, were discovered in this unit. Their systematic occurrence, in a structural-stratigraphic sense, indicates that this setting is attractive for mineral exploration despite high-grade metamorphism and deformation. Late-stage veins laden with fluorite crosscut these alteration zones, and are themselves metamorphosed, indicating that hydrothermal activity was polyphased. SHRIMP U-Pb ages obtained on detrital zircons (1 arenite) and on igneous zircons (5 volcanic rocks, 1 porphyry and 6 granitoids), pervasive arc-type geochemical signatures and presence of in situ rafts of barium-rich garnetite in the granitoids indicate that sedimentation and volcanism occurred between 1.52 and 1.49 Ga coevally with hydrothermal activity and emplacement of a sub-volcanic 1.5 Ga granitic batholith with early, 1.53 Ga tonalite intrusion. Such a geological context can sustain large-scale hydrothermal cells and development of VHMS, Cu-Fe oxides or SEDEX deposits.

May 1, 2003

By Hebblewhite B, Humphreys D

An experimental mining project has been carried out in the Collie Basin to demonstrate the safe operation of total extraction mining techniques in the underground mines of the basin. To achieve this, it was necessary to design and install a means of controlling or removing groundwater so that goafing of the overlying strata could be safely achieved as part of the mining operation. The site chosen for the experiment was a triangular panel adjacent to Western No 6 (WD6) underground mine, which includes the 3 to 4 m thick Wyvern Seam beneath 130 to 180 m of overburden. The test area abuts a major fault on the downdip side. The overburden and underburden sequences include several horizons of permeable sandstones which form major aquifers. Water problems have long been recognized in all underground mines in the Collie Basin, and have previously prevented the successful application of total extraction mining. Following extensive hydrological investigations, dewatering and depressurization systems were designed to dewater the immediate roof aquifers and to depressurize aquifers higher in the sequence and in the floor. This would enable stable roof conditions to develop and controlled goafing to be achieved. The roof dewatering/depressurization procedure involved a combination of in-mine vertical roof drainage holes and conventional dewatering bores constructed from the ground surface above the mining trial area. The dewatering system was installed and operated for 29 months before the commencement of mining. Mining was eventually successfully completed in two trial panels using a retreat Wongawilli extraction system using bridge conveyors and continuous miners. Water inflow into the mine workings was channelled to a constructed sump area at the lowermost corner of the panel and pumped to the surface via vertical sump bores. The dewatering and depressurization measures adopted were successful in permitting the first controlled and systematic total extraction recovery of coal from the Collie Basin. This trial mining exercise demonstrated the potential for increasing substantially the recovery of coal from the Collie Basin, where previously recovery rates of around 30 percent from underground mining were commonplace, using only bord and pillar methods.

Jan 1, 1988

By J Austin, R Bitencourt

Differences between the long-term model (LTM) and mine geology system (MGS) grade control block-outs on a blast block scale can impose difficulties to planning crusher feed grade and tonnes on a monthly to weekly blend basis. Detailed geological input to short-term planning has been integral to improve the performance and reduce risk in six-week to three-month production schedules and local variability in tonnage and grades is often not accurately represented in the LTM. The challenge of producing to combined target specifications from different mine sites in an integrated mine to ship business has been reduced with the creation of blast blockout-based short-term model. These short-term blast block models (STBBM or STM) are robust predictive tools created for upcoming benches of current mining areas by firstly collecting data from the pit in the form of bench and face mapping and projecting the structure and stratigraphy down to the next bench. A wire-frame of the projected contacts based on material destination from production blockouts is created and then checked against the LTM. Blast block data from the bench above including assay results and material logging is extracted and validated according to the projected wire-frames (geozones). Individual blast blocks and a full block model are created for each bench production defined by the STP (bench plans). Data output from the STM is in a compatible format for import into scheduling specific software packages. Additional information is incorporated into the STM to allow querying of drill penetration rates, predicted powder factors, material hardness and feed type to further aid in the production planning process and cost forecasting. To date, reconciliation of the STM has been pleasing and certainly an improvement on the LTM, especially in areas where variability is higher due to geological complexity. Short-term predictions derived from in-pit geological observations allow mine planners to more confidently decide on mining block sizes and schedule tonnages and grades, reducing the risk component attached to developing production schedules based directly upon long-term orebody models and mine plans.

Jan 1, 2005