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By Andrew Chegwidden, Tara Wilk

Shaft 18B-1 is the second shaft to be constructed as a part of contract C547A along the New York City water supply system Tunnel No. 3. More complex than Shaft 17B-1, this site has an additional 30 m (100 ft) of overburden for a total excavation depth of approximately 78 m (256 ft) through water-bearing overburden soil and 145 m (475 feet) of gneiss bedrock to connect to the underlying Water Tunnel No. 3. round freeing was specied as the method to provide temporary earth support and ground water control for the overburden material. An extensive supplemental geotechnical investigation (SGI) and frozen soil testing program was performed to develop the design of a temporary ground freezing system, consisting of over 7,315 m (24,000 ft or 4.5 miles) of drilling for the installation of 95 freeze pipes. At the start of shaft excavation, the upper sandy silts strata was found to have an unprecedented low thermal conductivity, leaving the frozen soil face approximately 0.6 to 1 m (2–3 ft) behind the cutline. The ground freezing earth support needed to be augmented with ring beams and liner plates to support this soil face and allow for the excavation to proceed and be completed safely.

Jun 23, 2024

By B. Morris

This presentation will describe the process by which the Quebrada Blanca (QB) copper project in northern Chile was financed. It will also show how a relatively junior mining company addressed the problems created by its inability to provide its share of the equity funding and the guarantees required by the project lenders. QB is located in the semi-arid Andean highlands of northern Chile, 170 kilometres southeast of the port of Iquique and 30 kilometres west of the border with Bolivia, at an altitude of about 4,300 metres (14,000 feet). Figure 1 depicts the project's location. The QB orebody is a secondarily enriched porphyry copper deposit containing reserves of 85 million metric tons grading 1.3 percent copper. Underlying the enriched zone is a significant primary ore zone containing several hundred million metric tons grading about 0.5 percent copper. In the late seventies and early eighties Falconbridge and its affiliates spent $20-30 million dollars exploring the deposit and conducting feasibility studies. For a variety of reasons they decided not to develop the property which was returned to its owners, Empresa Nacional de Mineria (ENAMI), which is a Chilean state mining corporation. In 1988 ENAMI announced its intention to privatize the property through a public bidding procedure.

Jan 1, 1993

By Stephen C. Moore

The Grossschloppen vein-uranium deposit, Bavaria, West Germany, was examined utilizing underground workings during 1980-82 by Esso Erz GMbH, an affiliate of Exxon Minerals Company (EMC). Geologic evaluation entailed dense drilling of a portion of the deposit from workings constructed specifically for the program. Discovered in 1977, the deposit was initially explored by surface diamond drillholes which allowed definition of a 30-60 m wide vein system discontinuously mineralized along a 1000 m strike length and to at least a 450 m depth. The underground program was conceived as a cost effective procedure to answer questions on vein correlation, grade continuity and variability. A 1200 m decline allowed access for detailed sampling of approximately 10% of the known area of mineralization. Fanned drillholes, logged by gaga probe, were spaced to provide intersections of veins at 10 to 20 m intervals. Six cross cuts also penetrate the pitchblende and uranophane mineralization which occurs in 0.1 to 2.5 as thick quartz veins. Detailed cross-sections and level plans were constructed for resource estimates of the intensively studied portion of the vein system. The program resulted in the discovery of local, high grade areas and an average grade in the evaluated area nearly double that expected from surface drilling.

Jan 1, 1983

By Verya Nasri, Agustin Rey

Once completed, the Montreal Réseau Express Métropolitain (REM) will be the fourth largest automated transportation system in the world. The REM represents construction costs of approximately 7.0 billion Canadian dollars. The project consists of 67 km of twin tracks over four branches connected to downtown Montreal. The project includes 26 stations with 3 underground stations in downtown Montreal. One of the underground stations was built using the NATM method with thin permanent shotcrete initial and final liners separated by a sprayed on waterproofing membrane. The 2 other underground stations were built with the cut and cover approach including one using permanent secant pile wall with permanent walers and struts as the support of excavation and the final perimeter wall of the station. The project also includes the rehabilitation and enlargement of the Mont Royal Tunnel. This 100-year-old double track tunnel is about 5 km long. The REM also consists of 3.6 km new TBM tunnel connecting downtown to the Montreal International Airport through saturated soft ground and karstic rock. By the time of RETC, the construction of REM underground structures will be completed. This paper presents the design and construction aspects of the underground structures of this mega project.

Jun 13, 2023

By ANGELA NAIR AVELAR, Reiner Neumann, PAULO R. G. BRANDÃO

The understanding of the influence of the different types of apatite on the performance of mineral processing of igneous phosphate ores is still a challenge due to the difficulty to explain why some types of apatite floats in the froth flotation cell and others do not under the same conditions. Three types of apatite were identified by means of cathodoluminescence (CL) images in flotation concentrate and tailing samples from the Catalão mine: predominantly blue apatite, followed by green apatite and less frequently yellow apatite. The chemical composition of these types of apatite was determined by electron microprobe analysis (EPMA) and LA-ICP-MS. Blue and green apatite respond well to the process, thus remaining in the concentrate, while yellow apatite remained in the tailings. Yellow apatite is the one bearing the lowest P2O5 content and the largest anionic and cationic sites substitution, followed by green apatite, whereas blue apatite is the most homogeneous, with highest P and Ca grades and lowest substitution level. A negative correlation of the amount of phosphorus with fluorine was observed. Furthermore, impregnation of iron oxide-hydroxides in the yellow apatite was also observed. Therefore, the low flotation behaviour is due to low crystallinity coupled with impregnation onto its surface.

Jan 31, 2022

By B. Y. Wong

In April 1989, Southern Company Services signed a 3.5 year contract with DOE-PETC for generic engineering development of an advanced physical fine coal cleaning technology known as selective agglomeration. This technology offers the potential for significantly higher pyritic sulfur removal (90% +) than conventional coal cleaning (30 to 50%) while maintaining high Btu recovery (90% +). Engineering development will include bench-scale process development; component development; adaption or modification of existing unit operations; proof-of-concept (POC) module design, fabrication, testing and evaluation; and small commercial facility conceptual design. The information obtained during POC operation will be sufficient to result in a technical and economic design base that can support construction and operation of a small commercial plant. The major goal of the research is to develop selective agglomeration technology to achieve 90% pyritic sulfur removal while operating at Btu recoveries above 90% based on run-of-mine quality coal. This objective will be accomplished in two phases: Phase 1 -bench-scale and component development, and Phase 2 -POC module operation and conceptual design of a small commercial plant. Currently, work is proceeding under Phase 1 (Tasks 1-7) of the project. A review of the status of Tasks 1-7 is presented in this paper.

Jan 1, 1991

By K. A. Foo

Minproc Resources Inc. is developing a tailings retreatment project in Bolivia at the Colquiri zinc-tin-silver mine, in the Bolivian Andes. Mining at Colquiri has been continuous since 1940 and COMIBOL, the Bolivian state mining company, has owned and operated the underground mine since 1964. There are 10 million tonnes of tailings at Colquiri containing 0.51% Sn, 4.21% Zn and 50 g/t Ag. Minproc plans to mine and concentrate the tailings at 1.15 million tonnes per year to produce feed for pyrometallurgical upgrading. The tailings are moderately complex, with cassiterite grain size ranging from 200 to 5 pm. The marmatite (ZnFeS) in the tailings is relatively easily recovered, with zinc recovery of 80% to a 40%-45% Zn concentrate. The major problem with the zinc metallurgy is that the marmatite is complexed with iron, which results in iron contents of 14%-17% Fe in concentrate. This makes the product very difficult to sell because of the low Zn:Fe ratio. Most zinc smelters require a Zn:Fe ratio of 6:1 or 7:1, whereas this concentrate has a 3:1 ratio. Concentrate sale terms are therefore unfavorable, and the high cost of transportation from Bolivia to the smelters is an additional burden.

Jan 1, 1992

By C. G. Carlström

The total iron ore production in Sweden in 1969 was 33.3 million metric tons. 31.7 million tons were exported mainly to Western European countries. 27.8 million tons (87 per cent) originated from the mines at Kiruna, Svappavaara and Malmberget, located just north of the Arctic Circle in Sweden. Planned production for 1970 is 25 million tons during 10 months, due to a strike at the beginning of the year. Present production plans for the next five years expect an annual export capacity around 33 million tons in 1975, including 5.7 million tons of pellets. The mining and shipping at the loading terminals of Narvik on the Atlantic coast and Luleå at the Gulf of Bothnia are managed by LKAB - a 96 per cent state-owned company. 4 per cent of the share capital is owned by the private Grängesberg Company. The railway - 106 miles from Kiruna to Narvik and 130 miles from Malmberget to Luleå - is operated by the State Railways in Sweden and Norway. Comprehensive expansion of the Narvik ore port will be carried through during the next five years to increase the annual shipping capacity to at least 35 million tons and meet the development of rapidly growing ship sizes.

Jan 1, 1970

By Guillermo Krstulovich

Pillar strength is a fundamental variable in the design of room and pillar mining. A number of researchers have investigated the strength of mine pillars by loading cubical, cylindrical and rectangular model pillars to failure in a compression testing machine (1). Several of these researchers have observed an increase in the compressive strength of model pillar with an increase in friction at the platen-specimen interface (2, 3, 4, 5). It has been postulated that the friction prevents lateral expansion of the specimen, thereby exerting a confining pressure at the interface. Seldenrath and Gramberg in their work with cylindrical specimens of limestone and marble noted that the effect of clamping the ends of the specimens, i.e., to restrict lateral movement of the specimen face, was to increase the compressive strength about 10% for marble and from 50-75% for the limestone, as compared to the same type of specimens when tested with the end planes free (6). No attempt was made to determine the confining pressure exerted by the clamps. In recent years, Bureau of Mines has conducted an extensive study, similar to Seldenrath and Gramberg's, with dog bone specimens. The confining pressure exerted by the clamps was determined and an increase in the compressive strength with increasing confining pressure noted (7, 8).

Jan 1, 1970

By Theodore H. Eyde

In 1971, the Minerals Division of The Superior Oil Company acquired exploration rights to an unpatented claim group in the Superior (Pioneer), Arizona mining district, lying west of the Concentrator fault. This major post-mineral fault displaces the Magma vein-fault, which is mined in the Magma Mine at Superior, Arizona. The Magma vein-fault and the enclosing section of pre-mineral rocks consisting of Paleozoic and younger Precambrian sediments and diabase, is overlain by a thick section of post-mineral rocks, consisting of the Gila conglomerate, the Apache Leap dacite, and the Whitetail conglomerate. Geologic information on the thickness and attitudes of the rocks obtained from previous diamond drilling indicated that the section of post-mineral rocks might be from 3,000 to over 4,010 feet thick in the target area. (Figure 1) The Magma vein-fault is a steeply dipping vein which has produced nearly a billion dollars of copper, zinc, silver, and gold. It has been mined continuously for nearly 10,000 feet along the strike and nearly 5,000, feet vertically down the dip. It ranges from less than a foot to over 50 feet wide and contains sulfide mineralization con¬sisting of pyrite, chalcopyrite, bornite, and chalcocite.

Jan 1, 1973

By R. K. Singhal

In 1990, Canada produced 69.4 million tonnes of coal of which some 65 million tonnes was produced by surface mining methods. The two Western Canadian provinces, Alberta and British Columbia produce approximately 55 million tonnes of coal by surface mining. These two provinces also provide the bulk of the metallurgical coal for export. The geological conditions in the Western provinces particularly in the mountain region are complex. The coals are friable and the seams are steeply inclined, sheared, intensely folded and faulted. There may be as many as 15 to 20 coal seams present with true thickness ranging from 2.5m to over 8m. Most of the Canadian surface mines are large (over one million tonnes per annum) using modern mining equipment such as shovels, high capacity trucks and draglines. At present the industry is going through another of its up and down cycles but has continued to make impressive gains in productivity. This has been achieved through greater mechanization, better management practices and a will to succeed in a highly competitive world market. This paper presents an insight into the current status of the Canadian Coal Industry and essentially updates the information given by the authors at previous SME meetings.

Jan 1, 1992

By J. E. Friant

The Mini-Disc TM cutter drill bit is a radical design departure from the traditional tri-cone rock drill bit. Miniature disc type cutting tools as small as 3.25 inches (82.5 mm) diameter are fitted to a bit body to cut individual concentric kerfs. The action is the same as that commonly used on large tunnel boring machines but miniaturized. The high performance rate and efficiency of a disc cutter are the result of producing a large proportion rock chips rather than sand or powder. The Mini-Disc TM drill bit, referred to as the "Disc Bit" has other unique features as well. It can be re-greased between runs. It can be rebuilt in the field in about 15 minutes, cutters can be replaced and the Disc-Bit appears to require less down hole hydraulic power than conventional bits. Thoroughly tested in the laboratory, the bit has recently been undergoing field trials in well drilling, blast hole drilling and shaft drilling. As any engineer knows, the laboratory cannot shake out all the problems but it eliminates the more glaring weaknesses. Performance results have been exhilarating, and a few mechanical problems were discovered and largely overcome. This paper is a progress report.

Jan 1, 1999

By L. H. McGuire

Many coal beds in the State of Washington, pitching as much as 90°, offer unusual mining conditions. This paper describes methods and safe practices of mechanized mining in pitching bituminous-coal beds that have attracted the attention of mining people from most of the coal-producing countries of the world. The development and use of continuous miners as part of the mechanized program apply particularly to the Roslyn-Cle Elum coalfield, Kittitas County, Wash. All three mines now operating in the field use continuous miners and during 1957 furnished 72 percent of the State's total coal production. Mining operations are now conducted in three coal beds of the Roslyn-Cle Elum field. The coal measures range from 3-1/2 to 20 feet in thickness and vary in dip from 5° to 45° in the localities where the coal is mined. Some safety measures adopted by-the principal operating company in the field during the past 30 years of mechanized mining follow: Use of only permissible electrical or compressed-air-operated equipment on other than intake air; providing and using an explosion gallery to test repaired permissible electrical equipment before taking it underground; use of only compressed-air-operated drill augers in preference to permissible

Jan 1, 1959

By R. B. Steele

The paper contains the results of the physical and mathematical simulations (based on the finite elements simulation) of the length and shape influence on the mechanical strength of the brex. Key words: Stiff extrusion, extruded briquettes, BREX, mechanical strength, cold strength, compressive strength, tensile splitting strength, oval shape, finite elements simulation. INTRODUCTION Extruded briquettes (BREX) exhibit a set of unique properties when compared with briquettes formed by alternative methods. Brex generally have sufficient integrity right after extrusion to withstand the necessary handling and stockpiling and does not require any special means and tools for the green briquettes strength conservation. In a typical die without an ancillary cutting device green brex tend to have very high length to diameter (L/D) or length to section area ratios. For round hole dies the brex are typically 5to 6 times the diameters and even longer. Stiff-extrusion allows also for the very easy changing of the forming dies. Dies with different cross-sectional shapes of the brex (round, ovals, square, hollow structures and many other two dimensional shapes) are possible, and common. The results of our investigations show how these geometrical shape factors contribute to overall quality of the brex both in terms of strength and as new charge components in metallurgical furnaces and processes [2-4]

Feb 27, 2013

By R. Pixler

Arch Mineral Corporation and Rocky Mountain Energy's Medicine Bow Mine in Wyoming presented an interesting challenge to the concept of mining a multiple-seam, dipping coal in the Hanna Basin. The 3362 and 2962 pits at MBCC were designed in a multiple seam coal consisting of 4 (and in some areas 5) bands of coal; these coal beds are all in the Ferris formation. The area was subject to some localized faulting and a major fault caused a physical restraint that we mined up against in our final cut. Using a 1570 dragline as the principal stripping machine, the concept of developing a bench for stripping the lower seams from the low-wall side of the pit was initiated. The results of this method of stripping were very satisfying for this pit through the completion of pit life and prompted us to use it in other areas at MBCC and at our other operations. Mining a dipping coal presents a small twist to conventional "flat" coal stripping. The spoil has a tendency to continually try to slide into the pit and the increased overburden on each cut as you mine down the dip creates spoil problems unless adequate design provisions are made prior to stripping.

Jan 1, 1986

By C. J. Newman

Prior to 1995, the smelting process at the Kennecott Utah Copper Corporation (KUCC) smelter consisted of Noranda reactors and Pierce-Smith converters. In the consideration of expansion opportunities, the existing process did not lend itself to a program geared towards processing the total output of KUCC mining and milling operations. During 1989 and 1990, a number of smelting options were evaluated. The final selection was the Outokumpu flash smelting process, coupled with the new Kennecott-Outokumpu flash converting technology. Facilities were designed and installed to process 1.0 million tonnes per year of copper concentrate, with the ability to expand to 1.2 million tonnes per year. Following the shutdown of the smelter facility utilizing the Noranda technology in May 1995, the flash smelting furnace commenced operation in June with the flash converting furnace startup following a few weeks later. The smelter has achieved design production targets and environmental goals. Current operating rates are at or above design rates for concentrate and matte processing. Emissions are lower than the permit levels and equate to less than 3.5 kg of S02 per tonne of copper. This paper outlines the design, construction, startup and the first two years of operation of the modernized KUCC smelter.

Jan 1, 1998

By R. D. Lord

This paper deals with the search for the best practical means of storing sulphide bearing tailings, where there is no residual excess of carbonate material. It is the common experience that the sulphide content decomposes, with the aid of bacterial action, and the resulting sulphuric acid escapes, along with any heavy metal solutes, through embankments that are usually porous to some degree. The problem is typified in the tailings of the uranium operations of Elliot Lake, Ontario, where mining started some 20 years ago. The approach to tailings disposal paralleled the practice for other hydrometallurgical plants treating gold and base metal ores. Impoundment areas were designed to retain solids, and a clear and neutral overflow was considered satisfactory practice. Now experience has shown that these areas, some idle for over a dozen years, release acids, in seepage and overflows, to an unacceptable degree. To protect natural water courses neutralizing plants are operated wherever required. Lime slurry is fed continuously into the tailings outflows in a quantity sufficient to raise the pH to 8.5 and precipitate heavy metals that may be in solution. The objection to this procedure is that the plants will require servicing indefinitely, unless a better remedy is found.

Jan 1, 1975

By David G. Thompson

There are basically two commonly used methods of drying washed coal. They are mechanical drying (sometimes called dewatering) and thermal drying. The common methods of mechanical drying are by using vibrating screens, cross flow screens, sieve screens or Vor-Siv, vacuum filters and centrifugal dryers. With thermal drying, the common types include direct fired fluid bed, rotary drum, flash or suspension, vertical tray or cascade continuous carrier or vibrating fluid bed dryers and hollow screw dryers. In the past, it has more or less been a general rule that any time the total product is being washed, both mechanical and thermal drying was required. The reason for this was that a product moisture of 3 to 4% was required and thermal drying was and is the only practical method by which this can be accomplished. With the advent of air pollution controls and the ever increasing concentration on dust elimination, a 3 to 4% moisture product is no longer practical in either the preparation plant or in the processing plants which utilize the coal. Under the new standards, it is desirable to have a product with a 6.5 to 7% surface moisture. With this moisture range, dusting, due to handling, will bc kept at a minimum.

Jan 1, 1975

By S. Tyson

The American Coal Ash Association, Inc. (ACAA) is an organization of producers and marketers of coal combustion byproducts. Since 1968, the goal of ACAA has been to gain recognition and acceptance of ccbs as an engineering material on par with competing virgin, processed and manufactured materials by advancing ccb uses that are technically sound, commercially competitive and environmentally safe. The use of ccbs is affected by local and regional factors including production rates, processing and handling costs, transportation costs, availability of competing materials, seasonal adjustments, and the experience of materials specifiers, design engineers, purchasing agents, contractors, legislators, regulators, and other professionals. An annual, survey of coal-burning electric utilities is conducted by ACAA to determine the quantities of ccbs produced and used in the USA. In 1993 approximately 88.5 million tons of ccbs were produced in the form of fly ash, bottom ash, boiler slag and byproduct from flue gas desulfurization (FGD). Approximately twenty-two percent of the combined production of these byproducts was used, while the remaining portion was deposited in disposal areas. The major markets for ccbs include cement and concrete products, structural fills, road-base layers, mineral filler in asphalt, grit for snow and ice control, blasting grit and roofing granules, grouting, coal mining applications, and waste solidification and stabilization.

Jan 1, 1995

By Michael E. Salovich

The U. S. Department of Interior, Bureau of Mines (Bureau) has developed a prototype version of a computer application that combines hydrologic analysis with object-oriented graphics. This software is unique in that it presents analytic element analysis within an object-oriented CAD environment. Its user interface employs mouse handling, scrolling windows, dialog boxes, palettes, and pulldown menus. It can import scanned images of maps and overlay these images within the same window. This application was developed using object-oriented programming techniques. Several programming issues concerning graphics had to be resolved during development of this system. These include (1) how to represent hydrologic elements as graphical objects, (2) how to translate screen coordinates to map coordinates, (3) how to implement ?zooming? (changing the magnification level of a window), (4) how to overlay layers of images, and (5) how to import scanned images of maps. An object library was used to implement graphical user interface features such as scrolling windows and pull-down menus. Algorithms for CAD features such as map coordinate translation, zooming, and the layering of images were developed by Bureau researchers. The application has a modular source code structure and can be modified for use in other research applications.

Jan 1, 1992