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By Eleanor Kentish, Nathan Bond, Edward Batty, Simon Webber, Alan Skarda

"Crossrail is Europe’s largest construction project — a new 100km rail route running through central London. A joint venture of BAM, Ferrovial and Kier (BFK) has constructed the tunnels and escalator shafts at the new Bond Street and Farringdon Stations. The recent trend in the UK industry towards sprayed secondary linings is driven by the potential for significant savings in cost and time. BFK is unique within Crossrail by constructing both sprayed and cast secondary linings. This paper presents a direct comparison between sprayed and traditional cast in situ secondary linings at Bond Street and Farringdon Crossrail Stations. An objective comparison is drawn between procurement and mobilisation periods, production rates, flexibility, tolerances and logistics in the tunnels. The technical challenges surrounding cast and sprayed secondary linings are explored, and recommendations are made of how each method could be improved for future use. INTRODUCTION It is well established that sprayed concrete offers a fast and effective method to seal the face of an excavation. In a relatively short space of time, sprayed concrete can be applied to an open face to support the short term ground loading on the tunnels during construction. Advances in sprayed concrete lining (SCL) technology — such as the use of wet mix processes, improved accelerators, fiber reinforcement, remotely controlled spraying robots, innovative surveying equipment and nozzleman competency schemes — have greatly increased the speed and safety of tunnel excavations using this technique. As a result, design engineers have become increasingly confident to use SCL primary linings as part of the permanent structural lining (Su 2014). Historically, long term ground and water pressure loads have been considered to be carried by the main structural or secondary lining, constructed using cast in situ concrete (Pickett 2014). However, the advances described above have made sprayed secondary linings a viable option, which has already been proven on the A3 Hindhead Tunnel (Arnold 2012). Sprayed concrete secondary linings offer potentially significant savings in cost and time during the construction process. The contractor does not need to procure a bespoke formwork system for each different sized tunnel — the SCL plant required is already on site for the primary lining. Each bay is sprayed with accelerated concrete, becoming self-supporting almost immediately — compared to moving and resetting the shutter, pumping concrete and waiting for it to cure. With sprayed concrete, working sequences and cross sections can easily be changed."

Jan 1, 2016

By Richard E. Steffens

The underground portion of Duke Power Company's Bad Creek Pumped Storage Project in northwestern South Carolina consists of a powerhouse cavern (132 m. long, 23 m. wide, 50 m. high), 407 meters of shafts and approximately 3615 meters of tunnel, both lined and unlined, with diameters varying from 4.2 meters to 9.0 meters. A case history is presented, including the early pilot tunnel exploratory work and how this affected design, the design of the project, and the excavation, rock support and tunnel lining work. Problems and experiences encountered during the construction are given. The effects of high horizontal insitu stresses in the granitic gneiss are discussed along with solution taken.

Jan 1, 1989

By A. R. Conroy

Microscopic observation of physical and chemical changes which take place in various materials under conditions of elevated temperature and controlled atmosphere can often yield valuable insight into the fundamental physical-chemical reactions which control processes in which these materials play an active role. The technique of high-temperature microscopy thus becomes an important tool for basic and applied research in pyrometallurgical and allied fields. Investigators have long been aware of this and through the years have applied the technique to a wide variety of problems. However, up to this time, application has been on a rather limited scale due to the high initial cost of equipment and the relatively low rate of production of data resulting from the complexity of the apparatus and attendant problems in manipulation.

Jan 1, 1964

By Leszek W. Lunarzewski, Adam L. Lunarzewski, Raymond C. Pilcher

The Floorgas and Roofgas simulation programs are used to identify strata relaxation zones and their boundaries, to assess active gas sources from coal seams and gas¬bearing rocks and to determine relevant gassiness prediction coefficients for any local longwall. The paper shows that by use of the print-outs from the Floorgas and Roofgas programs the following benefits are achievable: • identification of the shear and gas discharge zone positions in the floor, strata relaxation angles and various gas discharge zone positions in the roof, which are both relevant to local geological and mining conditions • optimisation of cross-measure drainage hole length, location, number and angle of inclination calculation and definition of gas make prediction coefficients such as the release ratio from adjacent coal seams, specific gas emission during longwall extraction and the relationships between gas make, longwall width and coal production levels.

Jan 1, 1995

By Donald Babbitt

In 1971, during the planning and design stages of a $300 million expansion, the Iron Ore Company of Canada Ltd. through its Engineers, Canadian Bechtel Ltd., came out with a preliminary request for two (2) 10,000 LTPH belt conveyor scale systems. These Systems were to provide weighing accuracies within 2.5% of the iron ore pellets and concentrates in transit on two (2) 72" wide conveyors from the stockpiles to the ships. Each conveyor system would be fed by a rail mounted bucket wheel reclaimer, with the conveyed material moving directly to the ship loaders with no inter- mediate surge and/or storage bins between the stockpiles and the ships. The bucket wheel reclaimer discharge rates would vary from 0-9600 LTPH in cyclic periods, with the periods varying from 1-5 minutes - dependent on the level of the reclaim buckets in relation to the stockpile as well as the slewing rate of the reclaimer. There would be frequent interruptions for bucket wheel repositioning (laterally and vertically), changing ship holds, and trimming ship holds. These frequent zero flow conditions, approximately 500 per 150,000 ton ship, could last 1-5 minutes. In addition, the conveyors on which the scales were to be mounted would be over the water and subject to the wind and cold of Northern Quebec. These Systems would be in use 350 working days of the year and would load 30,000,000 LT/yr. (An average of 90,000/working day).

Jan 1, 1975

By C. C. Bailie

This paper will be concerned with those mineable coal measures at depths necessitating deep mine operations in the range of 200 feet to 800 feet in depth. The area is generally classified as the Southern Illinois Field but more specifically includes that part of the state south of a line extending from St. Louis, Missouri on the west to Vincennes, Indiana, on the east. This embraces an area which presently includes a total of 38 shipping mines and 5 local or truck mines. Of these shipping mines, 22 are deep (shaft or slope) mines and the remaining 16 are strips. The average annual production of the shipping mines is around 29 million tons. The presently classified mineable reserves of the area are estimated at around 70 billion tons.

Jan 1, 1964

By James R. Boulton

Fire detection using Carbon Monoxide sensors is based on the assumption that a rise in the level of Carbon Monoxide in the atmosphere over a fixed, predetermined ambient level is indicative of a fire. The method is simple, reliable, and effective in those mines where the only source of CO is from undesired combustion. Ambience for this purpose is defined as that level of the gas that is present on a day to day basis whose source is not a fire. In a diesel powered mine the level of CO can and does vary so widely from hour to hour and minute to minute that the selection of a predetermined, fixed level represents a compromise between sensitivity and reliability. The compromise is a best of both and worst of both situations and the computer system often resembles the little boy who cried wolf instead of a state of the art early fire monitoring and detection system. Cyprus Coal personnel have developed method of determining the ambient level of CO in the atmosphere on a real time basis and using that dynamic ambient level to determine whether or not a fire exists in the mine. The method has been given the name of Wave Trend Crossing.

Jan 1, 1991

By T. Kretschmer, F. Villwock

Conveyor systems are an essential part of many material movements in all conceivable areas of application. They are used to transport goods in raw materials extraction, agriculture, and even articles for daily use. In the process, not only distances of several kilometers but also differences in altitude of several hundred meters are bridged. The layout of the conveyor usually follows the topography at the respective installation site. Particularly in the case of large height differences, safety devices must be provided to prevent uncontrolled movement. Backstops can take over this task in predominantly ascending overland conveyors and are used either as a primary or as a secondary safety system in conjunction with a service brake. They are always used when the system comes to an unplanned standstill, whether due to a power failure, an emergency stop or a defect. When designing backstops, it must be ensured in any case that all conceivable circumstances are taken into account so that failure is ruled out without the product being unnecessarily large in size. Various safety factors are applied, some of which are even prescribed by authorities. One example is the Australian standard on machine safety for bulk material belt conveyors (AS/NZS 4024). This stipulates a redundant acceleration safety device that can absorb at least 150% of the maximum load. ALTRA Industrial Motion with its sister companies Marland and Stieber manufacture backstops for a wide range of applications. With more than 85 years of business activity in freewheeling and backstop applications, they are among the most known and experienced companies and provide a great know-how.

Mar 2, 2022

By Yi Luo

Longwall coal mines are frequently located in steep mountainous areas with narrow valleys. In order to protect surrounding watersheds and residential structures, support areas are left under the valleys. However, the indirect subsidence effects to the residential structures due to the potential topography effects can be a serious problem. The present study examines a longwall mine in southern West Virginia located in an area with an average slope of about 30°, or 58%, and with an overburden depth that varies from 49 to 376 m (160 to 1,235 ft). A comprehensive investigation was carried out to assess the subsidence and topography effects, as well as other ground control issues at this site. Surface and subsurface movements and deformation were predicted and their direct effects on nearby streams and structures were assessed. The potential and indirect subsidence influences of surface topography effects were assessed. The techniques and results of this investigation are presented in this paper. It shows that the direct and indirect subsidence effects on the streams and residential structures should be insignificant. The post-mining observations agreed well with this study.

Jan 1, 2010

By N. Piret, B. Shoukry, S. Buntenbach

Traditional or artisanal goldmining, also known as small scale goldmining, has a strong and probably a negative environmental impact. The processing methods applied are very frequently a source of severe pollution due to the emissions of mercury by the extraction of gold by means of amalgamation as well as the emissions of cyanide through cyanide leaching of gold bearing ores. The emissions find their way into the environment and contaminate soils, sediments, water and atmosphere. Abnormal concentrations of mercury and cyanides in waterways are known to occur year after year destroying irreplaceable regions of the world. Mercury and cyanide compounds are highly toxic and may directly create permanent damage to the whole ecosystem. Existing methods for recycling of mercury and for decontamination of mercury and cyanide contaminated tailings are not customary applied in small scale mining and are ineffective as well. Based on investigations of traditional and small size goldmining, this paper presents: -processing methods of gold and discarded tailings under consideration of environmental protection; -figures on actual situation; -recommendations for equipment; -some decontamination methods for mercury and residual cyanide. Mineral Processing methods in traditional gold mining Gold is usually existing in its ores as the metal alloyed with metallic silver and perhaps copper. The element may occur in the form of: -native gold -inclusions also of microns or submicroscopic size metal sulfides (auriferous) such as pyrite, pyrrhotite, stibnite, arsenopyrite and galena -combined as telluride or sulphotelluride. The separation process selected depends on whether the gold can be freed from its unfavorable associations (e.g. gangue) at a sufficiently coarse grain-size, or whether it is carried in a heavy sulfide which can be freed similarly. The usual practice is to concentrate the goldbearing mineral at a relatively coarse grain-size and to regrind the ore if necessary. The gold content is concentrated by secondary or tertiary gravital methods or is extracted by chemical methods (amalgamation, cyanidation etc.) Gold, even when of fine grain-size, settle readily due to its high specific gravity from pulps in which the main gangue mineral is quartz or silicates. Amalgamation is the process of separating gold and silver from their associated minerals by binding (entrapping) them into a mixture with mercury. The cyanide process is applied to separate gold or gold-bearing compounds by dissolution from the finely ground ore (CIP, CIL, RIP), or as heap leaching. The dissolved gold is separated from the solids and the metal-rich or pregnant solution is then treated to recover its gold. Gold is also recovered by flotation methods. This process is widely used in treating base metal ores and in separating various sulfide components of ores, as well as in removing the barren gangue. The gold usually associates with a specific product in a sequence of flotation operations and is recovered subsequently in the smelting of the sulfide concentrates and refining of the metallic products, or by cyanidation of the roasted concentrates. Froth-flotation can be applied to separate gold and sulfide minerals from a finely ground pulp. The Amalgamation Process Amalgamation is the main method for the recovery of gold in traditional mining and is applied for the extraction of gold from placers as well as primary ores. The mineral technology used depends on the nature of ore deposits. In winning gold from solid ore, the matrix of minerals and rocks must be crushed and ground to sufficient fineness to liberate the gold. The liberated gold could be treated similar as free gold from placers. Gold is mainly separated from the valueless gangue (barren rock) by utilizing the difference between the density of the impure native metal (density about 16-19) and the gangue (density about 2.5). In simple operations the material is carried by a stream of water down a sluice generally equipped with small transverse barriers (riffles) against which the gold collects. The riffled sluice is the principal device used by artisanal gold miners. Nowadays, spirals as well as centrifuges, such as Knelson separator or Falcon separator, are occasionally applied for gold recovery. Gold may also be recovered from the pulp, by passing it over corduroycovered tables that catch the heavier particles - a method maybe as ancient as gold mining itself. In history, sheep skins were used to catch gold particles in this manner. Furtheron, gravity separation of gold is practiced on jigs, hydraulic traps, shaking tables and

Jan 1, 1995

By J. D. Cooper, D. W. Thompson, J. Basiuk, W. Cass, R. Ilves

The Department of Thoracic Surgery and Pathology at the Toronto General Hospital have had a long standing interest in the early detection and treatment of carcinoma of the lung. Our initial experience was with a population at risk due to a prolonged period of cigarette smoking. More recently our efforts have turned to industrial exposure, specifically in the nickel and uranium industries. [Initial Screening Project] (1) For a three year period 1963 to 1966 a cytology screening program was carried out through the Out-Patient Department. The study was limited to cigarette smokers over 40 in age. A total of 1586 patients were examined. Of the sputa collected, the classification is seen in Table 1. There were 11 malignant sputa present. Added to this number were 25 patients with symptoms, normal chest X-rays, but malignant cells on cytology, and a further 5 patients in whom an abnormality (eventually proven non-malignant) showed on X-ray, and sputum showed malignancy which was radio logically occult. (Table II). This gave a total of 41 patients with malignant sputum who were evaluated between 1960 and 1966. The clinical course of these patients is seen in Table III. Only 19 of 41 patients had localization and treatment of their tumour during that study period and this low rate of localization attests to the technical difficulties endoscopy in that day presented. The method of localization was as follows: a) 6 patients showed an area of segmental pneumonitis somewhere in this time period b) Using the rigid bronchoscope localized the tumour in 9. This was proven by direct biopsy, and frequently required more than one bronchoscopy over a prolonged time period. c) bronchograms and tomograms showed abnormalities in 5 patients. Of these 19 patients, 5 were treated by radiotherapy because of general condition or refusal of surgery. Three of the irradiated patients died of recurrent cancer within three years. The other two died within one year of unrelated disease. Fourteen patients underwent resection, with one operative mortality. At pathology, the tumours were "in situ" in 6 and invasive in 13. There was no evidence of nodal spread. When last followed up in 1979, there were no cases of recurrent tumour and no cases of second lung primary tumours. Similar experiences have been reported from the Mayo Clinic (2), Johns Hopkins (3) and Memorial Hospitals (4). Early detection of radiologically occult tumours which are in situ or minimally invasive has given uniformly good results. There have been no deaths from recurrent or metastatic cancer in surgically resected patients, and only one second primary tumour has been detected. Interestingly, the Hopkins group reports that 5 patients with Stage I squamous cell tumours refused operation. One refused any treatment and died of disease at 12 months. Three were radiated, and were alive from 14-38 months post-treatment, all with evidence of recurrent disease. [Sudbury Sintering Plant Study](5) From 1948 to 1963 an open travelling-grate sintering process was employed to convert nickel sulfide to nickel oxide at an International Nickel Company operation. The environment in this plant was particularly dusty and filled with fumes. It became apparent by 1969 that the incidence of bronchogenic carcinoma was markedly increased in workers from this plant. A concerted effort was made to track down all workmen with this exposure. During 1973 and 1974, 268 men were studied. Chest radiographs were done and showed no mass lesions. Sputum was collected on three consecutive days and analyzed. There were 12 men with malignant sputum, all of the squamous cell variety. Two refused any investigation, one presenting 31/2 years later with extensive hronchogenic carcinoma, and the other 5 years later with extensive carcinoma of the maxillary sinus. In the remaining ten patients careful rhinolaryngeal examination as well as a detailed bronchoscopy, involving examination, brushings and biopsy of all pulmonary segments was carried out. One patient was found to have laryngeal carcinoma and was treated by radiation. In nine patients, the malignancy was localized to the lung, leading to six lobectomies, two pneumonectomies and one sleeve lobectomy at operation. However, the follow-up in these cases suggests a different biological behaviour with these industrially related tumours. While no tumour has recurred locally, one patient has died of metastatic cancer and two patients have developed second and one patient a third pulmonary primary cancer. However, survival has still been much better than wits radiographically manifest lung cancer. [Technique of Localization] (6) Following a careful rhinolaryngeal examina examined and then the lower respiratory tract is examined. This is all performed under general anaesthesia. The trachea is examined with the rigid Jackson bronchoscope, collect-

Jan 1, 1981

By J. Castaneda, J. Schmidt

"INTRODUCTION Chino is an open-pit copper mining complex faced with intricate material routing requirements. Historically, this was challenging at the mine, in part because the shovel dig plan, haul plan, and dump plan were prepared completely separately. The mine now uses an integrated workflow for faster evaluation of schedules, which facilitates preparing balanced cutoff grade-to-equipment requirements, supports better mineral production, and improves schedule viability, while considering operational implications. Located in the state of New Mexico, Chino is one of nine Freeport-McMoRan mining operations in North America. This presentation discusses the benefits of implementing an integrated approach to tactical mine planning, and shares practical examples that were learned as Chino implemented an integrated tactical planning method. This includes improvements in completion time for preparing a schedule, minimal risk from manipulating Excel macros, data integration required to make short-term planning decisions, and better understanding of the mine plan’s effect in relation to the business’s key performance indicators. Ultimately, the integrated approach to tactical mine planning at Chino has led to production forecasts which are more achievable and reduced planning and execution variance. PROJECT OVERVIEW Chino mine is a porphyry copper deposit wholly owned by Freeport-McMoRan, the largest publicly traded copper producer in the world. Chino mine is located in Grant County, New Mexico, a short distance east of Silver City. Ore material mined from the pit today includes oxides, primary sulfides, and secondary sulfides. The mineralized material is sent to a mill, with a rated throughput of 42,000 tons per day, or to ROM leach pads with variable dumping capacities. At Chino, the short-range objective is to maximize total copper pounds sent to the mill, but no fixed cutoff grade accomplishes this for all periods. Instead, 12 different material classifications, including four sulfide classes that can feed either the mill or other destinations, and 38 cutoff bins, are aligned with the needs from operations, leaching, and the concentrator to create a schedule. Cutoffs vary from one week to another to cope with a highly intermittent ore body."

Jan 1, 2018

By T. A. McAfoose

As one of the major suppliers of the chestnut Ridge energy center, Rochester and Pittsburgh Coal Company continues the search for more efficient haulage systems. This search is one that is essential in providing coal to the Keystone and Homer City power plants at the most economical cost. These two electrical generating plants located in west central Pennsylvania are part of the energy center which consists of four generating stations. Prior to the time the two stations were put on line, August, 1967 for Keystone and August, 1969 for Homer City, our company made the decision to rely on belt conveyors from the section to the surface to provide for continuous main line haulage. The proximity of these generating stations to proven reserves allow for minimal truck haulage and minemouth setups. With the addition of seven new mines, in the past ten years, revisions have been made on the original setup to interconnect the haulage of several mines to deliver the product by belt to the power plants.

Jan 1, 1979

Zirconium chloride is of great commercial importance as starting materials for production of ZrO2, Zirconium metal and other Zirconium compounds from its main resources (Zircon Sands). The present study concerns with preparation of pure ZrO2 from Zircon by direct chlorination technique. Different parameters affecting the chlorination process are studied viz. carbon, chlorine flow rate temperature and time. The chlorination extent is determined from the loss in weight and chemical analysis of reaction products. The maximum chlorination extent -92% are achieved at 1100°C for 30 min. Zirconium oxide is produced from the collected zirconium tetrachloride either by calcination at 900°C or by hydrolysis in water in presence of RCI with a purity = 99%. Evaluations of the products of the process are investigated microscopically and by X-ray diffraction. The apparent activation energy of the chlorination of Zircon is determined to equal 36 kJ/mole.

Jan 1, 1997

By S. Peng, Yi Luo

Subsurface strata movements and deformations associated with underground longwall mining activities could cause certain influences to subsurface structures and water bodies. Methods have been developed for the prediction of final and dynamic subsurface movements and deformations induced by underground longwall mining operations in the eastern coal fields. Two new types of strata deformation, vertical and total strains, which could be useful in the field of subsidence research in assessing subsidence influences to the subsurface structures and water bodies, have been introduced. Using the subsurface subsidence prediction model, three types of subsidence influences to surface and subsurface hydrological systems have been identified. Attempts have been made to quantify the two types of subsidence influences that could cause water loss and could lower water levels in aquifers.

Jan 1, 2010

By John S. Burton

Mineral policy in Canada has been in a state of transition and change over the past several years. 1976 has witnessed some settling of troubled waters and the pattern of the currents of change is becoming more clear. The provinces play a key role in this process and have provided much of the thrust for new initiatives. On the other hand, the federal government in Canada in recent years has taken a much more active interest in mineral affairs than previously and has asserted its powers on a number of key policy questions. Some of the initiatives from the two levels of government in Canada have come into conflict with each other and, thus, contributed materially to a state of affairs that includes change, uncertainty and conflict.

Jan 1, 1976

By J. R. Johanson

In recent years the procedures for functionally designing bulk storage bins and hoppers have evolved from qualitative guess and try methods to a quantative method based on theory and tests of the bulk solid to be stored. This quantative method, developed and implemented by Dr.'s A. W. Jenike and J. R. Johanson as with any new design, must prove its effectiveness and validity in the actual operation of the finished equipment. How accurate are the theoretical predictions? Is it possible to extrapolate from bench size tests on a small ample of the bulk solid to the full scale bin design? Can the theoretical designs be economically translated into working hardware? In this paper the answers to these questions are discussed in light of actual bin operations.

Jan 1, 1968

Lack of selectivity in mixed mineral flocculation can be attributed to one or more of the following factors: dissolved ion interference, heterocoagulation, mechanical entrapment in flocs and entrainment of fines between flocs. In a study of apatite- dolomite system, it was determined that dissolved ions do not have a significant effect on selectivity. Heterocoagulation was minimized by choosing proper process conditions and addition of a dispersant. Mechanical entrapment was proved to be insignificant and efforts were made to reduce entrainment by choosing an appropriate method of separation of flocs from fines. A new factor termed "polymer induced entrapment" which occurs due to limited affinity of the polymer to the mineral which is not flocculated is postulated to be the cause for the loss of selectivity.

Jan 1, 1986

By G. C. Adams, J. H. Fowler

Canada's gypsum industry began more than 200 years ago in the Maritime provinces when farmers attempted to supplement their incomes by selling "land plaster" to traders bound for the United States. Rising from such humble beginnings, gypsum now contributes significantly to the economies of nine of Canada's 10 provinces. Thirteen open-pit and three underground mines produced a total of 8.4 Mt (9.3 million st) of crude gypsum, and 17 processing plants manufactured 2.5 Mt (2.8 million st) of finished products in 1985. Recent economic growth in North America has resulted in steady increases in gypsum production. However, competition from foreign producers and by-product gypsum pose a growing threat to Canada's gypsum mining industry.

Jan 1, 1987

By D. D. Harbuck, G. K. Green

The Bokan Mountain area on Prince of Wales Island, AK, contains vast quantities of heavy rare earth minerals. To lessen the US dependence on foreign sources, the US Bureau of Mines (USBM) investigated yttrium recovery from this ore. By sulfating the ore at 250 ° C for 1 hr at an H2S04:ore ratio of 1:1 and then water leaching the sulfated material for 1 hr at 20% solids and 25ºC, over 74% of the yttrium, cerium, and lanthanum were solubilized. Solvent extraction (SX), using a synergistic combination of OPAP and DEHPA, selectively loaded 100% of the yttrium. Yttrium was stripped directly as a solid using a 2M, 35 ° C NaOH liquor. When the OPAP/DEHPA mixture was tested in a continuous SX circuit, yttrium loading and stripping were 100% and 96%, respectively. The organic showed excellent recyclability properties with minimal solvent loss.

Jan 1, 1996