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By David B. Brooks

INTRODUCTION Resources are not; they become (Zimmermann 100) . The companion concepts of reserves and resources appear, one way or another, in almost all considerations of mineral supply. Yet, no other concepts in the economics of the mineral industries have occasioned so much confusion. Whereas everyone agrees that in general the terms refer to the amounts of material that-depending upon technology, market conditions, and institutions-will become available for production in the near or more distant future, the apparent agreement disappears when we come to more specific definitions or to application of the definitions. Some definitions emphasize the physical aspects of reserves and resources, while others emphasize the economic. Some treat reserves and resources as fixed quantities, while others regard them as continually varying. Some consider that reserve and resource estimates have validity only for individual deposits, while others insist that they can be measured with sufficient accuracy for regional or national planning. This confusion in concepts that lies at the very heart of mineral economics is both strange and not so strange. It is common in the social sciences to find concepts that have been adopted into scientific jargon from popular usage and given rather special meanings -at the same time that they continue to be widely used without such qualifications. Psychologists have the same trouble with personality and sociologists, with community. Nevertheless, an attempt must be made to straighten out the various meanings of reserves and resources, or at least to clarify the conditions under which different meanings are applicable, before much progress in analysis of mineral problems can be expected. That is the objective of this chapter. Throughout the chapter, an attempt has been made to provide enough references to guide the interested reader to the most pertinent works on the concepts under study. However, even in a review article, it is no longer feasible to provide a comprehensive set of citations; there are simply too many. In many instances the works cited will themselves include the bibliographies needed to complete a literature search; those that are particularly useful in this respect are so noted. Also, because of the limited availability of foreign periodicals, some important works -originating largely in Canada, France, the

Jan 1, 1976

By C. L. Bulow

In this discussion of stress-corrosion cracking of widely used copper-base alloys, no attempt has been made to prepare an extensive review or bibliography since this has been quite ably covered by other investigators. An excellent bibliography was published by H. P. croft(1)2 in connection with his studies of stress-corrosion cracking in mercurous nitrate solutions and his analyses of the magnitude and distribution of stresses in brass parts. We are reporting on a few of the results which have been obtained to date in connection with an ammonia vapor test and an alternate immersion test. These are accelerated corrosion tests for determining the susceptibility of materials to failure from season or stress-corrosion cracking due to the presence of moist ammonia and oxygen so prevalent in nature. Our experiences with the ammonia test seem to indicate that it is a more searching test, than the mercurous nitrate test.

Jan 1, 1945

By G. R. Belton, R. J. Fruehan

The Knudsen cell-mass spectrometer combimtion has been used to study the Fe-Al and Ag-Al liquid alloys. By application of the recently developed integration technique to the measured ion-current ratios, activities have been derived for the Fe-A1 system at 1600° C and for the Ag-Al system at 1340"C. The results are partially represented by the following equations: Internal consistency between the data on silver-rich and iron-rich alloys is demonstrated by application of the literature measurements on the distribution of aluminum between the nearly immiscible liquids iron and silver. The usual restrictions on the ratio of the mean free path of the escaping atoms to the orifice diameter of the Knudsen cell are shown not to be limiting in this technique. DESPITE the importance of a knowledge of the activity of aluminum in understanding deoxidation equilibria in molten steel, no direct studies have been made of activities in liquid Fe-A1 alloys at steel-making temperatures. Lower-temperature direct studies have, however, been carried out on aluminum-rich liquid alloys by Gross, Levi, Dewing, and Eilson' at 1300°C and by Coskun and Elliott' at 1315°C. Apart from phase diagram calculations by Pehlke, other determinations have been indirect and were made by measurement of the distribution of aluminum between iron and silver475 and combination of these data with extrapolated activities in the Ag-A1 system.~-% ecently, however, Woolley and Elliott have made a significant contribution by directly measuring heats of solution in the Fe-A1 system at 1600°C. The present authorslo have recently employed a Knudsen cell-mass spectrometer technique in a study of activities in iron-based liquid alloys. In this technique activities and heats of solution are determined from a series of measurements of the ratio of ion currents of the components; and since ion-current ratios are used, problems caused by changes in instrument sensitivity or cell geometry are overcome. Results obtained for the Fe-Ni system were found to be in excellent agreement with previous work, thus demonstrating the reliability of the method. The present paper describes a similar study of activities in the liquid Fe-A1 and Ag-A1 systems, this latter system being included in order that a meaningful comparison can be made with the above-mentioned indirect studies. INTEGRATION EQUATIONS A detailed derivation of the equations used to determine the thermodynamic properties from the measured ion current ratios has been given elsewhere;'' however it is useful to summarize them here. By the combination of the Gibbs-Duhem equation with the direct proportionality between ion-current ratios and partial pressure ratios, it was shown that for a binary system at constant temperature and pressure: where al is the activity of component 1 with pure substance as the standard state, N, is the atom fraction of component 2 in the solution, and I; and t'2 are ion currents of given isotopes of the components. The activity coefficient is given by: this latter equation being more suitable for graphical integration. Combination of Eq. [l] with the Gibbs-Helmholtz equation gives an expression for the partial molar heat of mixing: EXPERIMENTAL A Bendix Time-of-Flight mass spectrometer model 12! fitted with a 107 ion source and a M-105-G-6 electron multiplier, was used to analyze the vapor effusing from the Knudsen cell. The arrangement of the Knudsen cell assembly was essentially that of the commercial instrument (Bendix model 1030) but with several modifications. Instead of heating with a single tungsten filament, a cylindrical tantalum-mesh heater was employed. Up to 1400°C simple resistance heating was used but above this temperature electron bombardment between the tantalum mesh and the tantalum cell susceptor was necessary. The temperature was measured by means of a Leeds and Northrup disappear ing-filament type optical pyrometer sighted on an essentially black-body hole in the side of the cell. Details of the temperature control, temperature measurement, and in situ calibration of the optical pyrometer can be found elsewhere.I0 In the investigation of the Fe-A1 system the Knudsen cells were constructed of thoria crucibles with fitted thoria lids (Zircoa). The cells employed in investigating the Ag-A1 alloys were made up of high-purity alumina crucibles (Morganite) with lids of recrystal-lized alumina (Lucalox). The cells were 0.370 in.

Jan 1, 1970

By John R. Bartels

Jan 1, 2009

By F. G. Loper

Simulation as a mathematical technique is not new. However, recent increases in digital computer speeds and the ease of programming with languages such as Fortran have centered a good deal of attention around simulation in the last few years. By ignoring all but the relevant characteristics of a process, a mathematical simulator may be constructed which, when fed operating data, should react as the process would. The output becomes numbers, instead of tons, however. Thus, a trial-and-error operation of such a simulator will permit management to study a major system change at little cost.

Jan 1, 1967

By Graeme Smart, Thomas Fiala

"Yorkville Plaza II, a 40-storey signature condominium residence, is scheduled to open on Avenue Road in Toronto’s prestigious Bloor-Yorkville neighbourhood in spring 2017. In close proximity to Toronto’s subway system, the new tower requires six levels of underground parking, founded in wet, silty sand.Isherwood Geostructural Engineers (Isherwood) was retained in April 2012 by developer Camrost-Felcorp to provide a shoring and excavation solution to address the challenging site conditions. A 31-storey upscale residential building under renovation with three levels of parking, owned by Camrost-Felcorp, flanks the site on the north. Situated on the eastern border is a 7-storey building with three levels of parking. Avenue Road, a four-lane arterial road that brings heavy commuter traffic into downtown Toronto, runs along the western border, and on the southern border of the site is a busy City road that brings traffic into the popular Yorkville area. The tunnel for the Toronto Transit Commission’s (TTC) overburdened east-west subway is located 14.5 m to the south, running below an existing 26-storey neighbouring building. Electrical and communication utilities (Bell) are closely located along the southern side. Non-documented existing excavation shoring, installed in the early 1970s, on the southern and western sides compounded the difficulties presented by the TTC tunnel.This paper presents the unique, non-conventional hybrid shoring solutions Isherwood developed to address the challenges presented by the site, as well as other complications that surfaced during the project: non-encroachment requirements (no tiebacks) beneath uncooperative neighbours, tight geometry to install shoring, and Toronto’s two coldest winters in decades.THE PROJECTBecause of circumstances associated with this site, for this project Isherwood designed two unique shoring walls which drew on their experience and expertise they had gained over the last 40 years. The following is the story of this site:Yorkville is an affluent neighbourhood in the heart of Toronto with a vibrant mix of high-rise towers, residential homes, tony restaurants and flagship shops. The development requires six levels of underground parking (a 20m deep excavation), with three levels undermining the high-rise buildings to the north and east and extending into wet, silty sand.Isherwood was retained in the spring of 2012 to design the excavation shoring. Isherwood’s scope also included field support, design, verification and monitoring. Finite Element Analysis was employed to confirm Isherwood’s design and anticipated movement of the south shoring wall and the TTC subway tunnel.The existing site was severed in two, with the proposed condominium tower slated for the southern portion. On the north half of the site stands a 31-storey building (Yorkville Plaza I at 21 Avenue Road), with three levels of underground parking, sitting on belled caissons which were one foot from the back of the proposed shoring wall so this would have to be considered in relation to the design and drilling methods. Constructed in the early 1970s, Yorkville Plaza I is currently being converted from the Four Seasons hotel to luxury condominiums by Camrost-Felcorp. To the east, directly adjacent to the proposed shoring, stands a 7-storey building (164 Cumberland Road) with three levels of parking, supported on spread footings founded on stiff clayey silt. The tunnel for the TTC’s busy east-west subway, a double box structure built by cut-and-cover in the 1960s, is located 14.5 m to the south, 9 m below grade, and running below an existing 26-storey building. Bell fibre optic communication cables and electrical lines, along with storm and sanitary sewers, are situated on the south and west sides of the site, leaving limited room to install shoring. Due to the heavy volume of commuter traffic on the four-lane arterial road (Avenue Road) to the west, site access and lane closure were not permitted here."

Jan 1, 2015

By Michael Swisdak, John Tatom, James Tancreto

In 2002, testing was proposed to generate needed data to assist in developing improved explosives safety standards within the US Department of Defense. This testing emphasizes two major areas: (1) full-scale donor/acceptor trials examining debris generation and acceptor response and (2) debris perforation testing of representative roof/wall materials. The full-scale donor/acceptor trials are referred to as the SciPan series. The first three tests in the SciPan series have been completed, as has the first phase of the SPIDER program. This paper describes the status and future of these testing programs, reasons for choosing specific tests, potential benefits, and planning for future phases.

Jan 1, 2006

By M Scoble, R A. Hall

The mining industry has aggressively sought competitiveness through increased productivity and return on investment. A primary strategy has been the pursuit of economies of scale. This has also been dependent upon the implementation of new technology and systems integration. System integration has been accomplished through the implementation of mine dispatch, global positioning and mine wide communication technologies. These technologies have tended to advance at different rates of development and implementation. The result has been that across the industry, and even within companies, mines are at various stages of operational system re-engineering in these areas, driven by improvements in productivity and operational efficiency. Although this strategy has been successful, little effort has been made to analyse change in operational performance in order to understand and model the effects of scale in a quantitative manner. This paper considers the particular impact of equipment scale, together with potential future trends. It then presents and demonstrates a preliminary method to quantify through simulation the anticipated benefits of economies of scale.

Jan 1, 2003

The 1997 Rapid Excavation and Tunneling Conference (RETC) was held at the Mirage Hotel, Las Vegas, NV. The RETC is a biennial event jointly sponsored by SME and the American Society of Civil Engineers (ASCE). Conference attendance was 573 members, nonmembers and students, an increase of seven attendees from the 1995 conference in San Francisco, CA. Exhibitors occupied 51 booths at the Las Vegas RETC. The 1997 conference encompassed 58 presentations in 15 sessions. Participants were given details on achievements and advances that have resulted in new design solutions, alternative work practices and increased productivity within the industry. The page at the end of this article tells how to get your copy of the RETC proceedings, either hardbound or on CD-ROM. Or, if you wish, for the first time a CD-ROM is available with the complete RETC proceedings from 1972 to 1997. This two-disk, archival volume has key-word search capability, is in portable file format and is compatible with PC and Macintosh platforms. RETC program sessions included design and planning, ground support, tunnel boring machine (TBM) case histories, conventional excavation, new technology, difficult ground, geotechnical, shafts and raises, future/special projects, new Austrian tunneling method, international projects, soft ground case histories and water and gas. What follows are highlights of some of the RETC presentations.

Jan 1, 1997

By G. Don Sullivan

Surface mine operators have organized a voluntary group known as the Mined-Land Conservation Conference for the specific purpose of developing and expanding reclamation programs on mined land. As a part of the Conference program, a Voluntary Industry Program was adopted and subscribed to by its membership. This program stated: "The basic approach to a sound conservation program is the restoration of mined land to its most practical and productive use within the shortest possible time . . . reclamation of mined lands, including planting to grasses or tress, should be done on a planned basis, under technical guidance by personnel trained in this field."

Jan 7, 1965

By Robert Warner

WHEN a new mine is opened, and often when an operating mine must adapt itself to physical or economic changes, a mining system must be selected in complete detail. In the past the plan chosen was usually the product of the local staff alone, however limited the training and experi-ence of that staff might be, which often resulted in the introduction of methods that were familiar to the staff, but not so well suited to the con-ditions as others unknown to the local men. A new management, noting the difficulties with the existing layout, might make modifications or complete changes, so that many mines in their history have seen a whole series of mining systems, each somewhat laboriously grafted on to its predecessor. This should not be interpreted as a condemnation of the older staffs for sticking to the tried systems, such as open square-sets in the early days at the Homestake, because they knew it would work after a fashion, nor does the statement apply to the technically trained, and usually broadly experienced staffs of most present-day properties. The older miners did not have the variety of tools and methods, nor the present freedom of transfer of information as to what the other man is doing, and so did the best they could under the circumstances. Finally, the higher grade of the ores made the choice less vital. The ever-increasing need to mine low-grade orebodies, with a fixed or even lower price for the metal produced, has caused an increasing need for low-cost mining. In most new mines this has simplified the problem of selection by eliminating from consideration all of the high-cost systems, but it has also complicated the choice by the necessity for refinement in detail and a close adjustment of the plan selected to all the conditions at the property. In these low-cost problems any textbook division of mining systems as applied to "beds, veins or masses" avails little as a guide. It should be realized at the outset that to' be successful under modern competitive conditions a system of mining must be worked out with elaborate detail, with careful time scheduling and control of the various elemental operations, and that after it is introduced it must be run with a large amount of technical direction.

Jan 1, 1933

By Z. Zhang, R. G. Reddy

Viscosities of industrial lead slags with various compositions were measured as a function of temperature using a Brookfield viscometer. Based on the experimental data from this study and other investigations reported in the literature, an expression has been developed to correlate the viscosities of lead silicate slags as functions of composition and temperature. The effect of each individual slag component on the variation of the slag viscosity is identified. The composition dependency of viscosity of lead silicate slags is discussed. The calculated results using this viscosity expression are in good agreement with the measured data.

Jan 1, 2001

By T. H. Jeffers

The U.S. Bureau of Mines' Salt Lake City Research Center. has developed porous polymeric beads containing immobilized non-living biological materials for extracting metal contaminants? from wastewater&. Immobilized biological materials include peat moss, algae, biological polymers, and other materials that demonstrate high .affinities for heavy metals. The beads, designated as BIO-FIX beads, have distinct advantages over traditional methods of utilizing biological materials in that they have excellent handling characteristics . and can be used in conventional processing equipment or low-maintenance systems.. Toxic metals such as copper, cadmium, zinc, lead, and mercury are several of the many heavy metals effectively removed from mine wastewater& using B'IO"FIX beads. Continuous cyclic testing indicated that the beads continued to produce treated effluents which met National Drinking Water Standards (NDIJS) after 175 loading-elution cycles, Adsorbed metals were removed from the beads using dilute ?mineral .acids. In many cases" the extracted metals were further concentrated to enable processors to reclaim the metals, thus minimizing the generation of a hazardous sludge. Tests indicated that use of the beads in a low-maintenance system was particularly effective for treating remote acid mine drainage waters? and small toxic seeps from hardrock mining districts ..

Jan 1, 1991

By Jeffrey R. Hill

To extend the life of the Merchants Railroad Bridge crossing the Mississippi River in St. Louis, MO, the owner implemented a rehabilitation and reconstruction project. The Merchants Bridge provides a key link in the transcontinental railroad system. The bridge is of local importance to the Terminal Railroad Association ? providing a link between St Louis and a rail switching yard in Venice, IL. The intent of the bridge rehabilitation is to keep the Merchants Bridge in service, even though the bridge was originally constructed in the 1890?s. The project involved replacing the East and West approach deck truss spans with new deck girder spans. The rehabilitation program required construction of new concrete piers to support the new spans. In order to reduce the track down time to two, ten day single track shutdowns, the specifications required that all foundation and substructure work be completed while leaving the existing spans in place. The preliminary bridge design specified rock-socketed drilled shaft foundations. Drilled shafts proved to be challenging due to working from beneath the existing bridge, a high water table, utilities, a flood wall, and existing rail way lines. The micropile alternative was technically appropriate given the access limitations, shortened the foundation rehabilitation schedule by several weeks, and realized a significant cost savings to the Owner.

Jan 1, 2006

By G. McIsaac

This paper discusses the formulation of a linear program with the objective of maximizing the cash flow of the long-term plan of an underground operation. A mine is split into eleven independent ore zones, each characterized by its reserves, required development, and mining method. Based on practical considerations, maximum rates are set for each zone?s development and production capacity. For the total mine plan, a minimum daily production rate is set along with a minimum feed grade to the mill. A maximum daily development capacity is set based on the equipment and labour available. Proven and probable ore is mined preferentially over possible ore in the early years of the plan. Also, the fixed cost of operating the mine is taken into consideration whenever mining activities take place. Once the linear program is solved, it can be critically reviewed, and unrealistic results can be identified. Some resource allocations constraints can then be changed in certain sectors, and new results can be analyzed. ?Whatif? scenarios can also be examined, such as determining the impact of hiring a contractor to develop a given sector, or dropping an ore zone completely from the plan.

Sep 1, 2005

By T. G. Hawkins, T. M. Naciuk

"The Katie Cu-Au deposit is situated in southeastern British Columbia, 425 km east of Vancouver. The deposit is a member of the alkaline group of porphyry Cu-Au deposits associated with potassically and propylitically altered andesitic volcanic rocks.The Katie porphyry system occurs in mafic to intermediate alkaline volcanic rocks of the Lower Jurassic Elise Formation of the Ross/and Group. Host metavolcanic rocks include andesitic to basaltic flows, flow breccia, massive fine tuff and crystal tuff Gabbroic intrusions alternate with the volcanic rocks in drill core. The lack of chilled margins and shear contacts, as well as their similar composition to the volcanic rocks, suggest that the gabbro was synvolcanic.Alteration exhibits a zonal pattern spatially related to zoned porphyry-style mineralization. Propylitic alteration is common and assemblages consist of epidote, chlorite, sericite and calcite. Potassic alteration zones are accompanied by elevated copper-gold grades and are composed of K-feldspar, plagioclase, quartz, biotite and chlorite. Narrow drillhole intervals of secondary magnetite, generally less than 2 m across, occur above the potassic alteration zones. A thick oxidized cap lies above the mineralized zones, although only local supergene enrichment has been identified. The lack of supergene enrichment is perhaps due to intense near-surface fracturing and leaching from a high energy groundwater environment.Sulphide mineralization consists mainly of pyrite within the propylitic halo, and pyrite and chalcopyrite with trace pyrrhotite, sphalerite, tetrahedrite, bornite and molybdenite within the potassic alteration core. Malachite, azurite and traces of chalcocite occur within the oxidized cap.Discovery and exploration techniques have included airborne geophysics, regional stream sediment sampling, prospecting, geological mapping, ground geophysical surveys, soil sampling surveys, and diamond drilling. Two primary targets of porphyry copper-gold mineralization have been identified by exploration. The Main zone strikes northwest, has an apparent true thickness ranging from 70 m to 135 m, and is a minimum of 500 m in length. The 17 zone strikes northwest, has an apparent true thickness of 90 m, and is a minimum of 300 m in length. The two zones are defined by grades that generally exceed 0.2% Cu and 0.25 g/t Au. Both zones are open along strike and to depth."

Jan 1, 1995

By Syd S. Peng

Introduction The most commonly used ground control design in coal mining is the determination of pillar size by various pillar strength formulae for mine layout (Bieniawski, 1983; Holland, 1973; Hustrulid, 1976; Obert and Duvall 1967; Wilson and Ashwin, 1972). However, there have been few documented case histories concerning the validity of those strength formulae. Recently there are indications that those strength formulae tend to overdesign considerably. From a safety point of view, there is nothing wrong with overdesign. But an overdesign with large chain pillars reduces the flexibility of machine movement and decreases production. It also reduces coal recovery and, thus, shortens the reserve's life. This is especially true for small operators who own a limited reserve. Those small mines, through past practices or out of necessity, experiment with smaller pillars than those predicted by the strength formulae. Conclusive ev¬idence has been collected that points to the need of a new concept of coal pillar design. Two case studies will be cited to illustrate this point. 3-D US pillar strength formulae Figure 1 shows a sectional layout of a one-unit mine. The seam was about 1.3 m (50 in.) thick with a uniform cover of 64 m (210 ft). A house was located near the center of the section. The homeowner demanded that no surface subsidence and domestic well dewatering should ever be allowed as a result of underground room-and-pillar mining. Physical properties - strength and Young's modulus - of the rock strata including coal were obtained by testing small samples in the laboratory. The uniaxial compressive strength of the coal was 3660 kPa (823 psi). Using various pillar strength formulae, the homeowner recommended that square chain pillars be at least 11 m (35 ft) wide. The coal company, however, desired to pursue optimum coal recovery in the safest and most economical manner. They engaged in three-dimensional finite element analysis of the section taking into account the complete stratigraphic sequence of the overburden. Results indicated that the section can be developed by 5.5 m (18 ft) wide entries at 21 m (70 ft) center-to-center. In retreat, the pillars can be splitted along both centerlines leaving a stump pillar of 5.5 m (18 ft) square at each of the four corners. The 5.5 m (18 ft) square stump pillars still maintained a safety factor of 1.5, although the safety factors calculated by various pillar strength

Jan 11, 1986

This paper will discuss specifically the performances of vibrating screens having circular motion with inclined decks and linear motion with horizontal or near horizontal decks and both related mainly to coal, metalliferous, and other granulated solids applications where screening and efficient classification is required. Some misconceptions have been applied in the past with regard to making a screen type selection using either circular throw or linear throw and therefore this paper will endeavour to clarify these misconceptions.

Jan 1, 1984

By Robert A. Jankowski

The Bureau of Mines has recently identified five major factors that contribute to high respirable dust levels on the six U.S. longwall faces having the most difficulty complying with Federal dust standards: (1) a poorly structured cutting sequence, (2) a poorly designed external water spray system, (3) marginal waterflow to the cutting drums, (4) minimal controls at the stage loader and crusher, and (5) the lack of effective controls for dust generated during support advance. The results of this survey illustrate the need to address all the major sources of longwall dust generation and the need for mine operators to implement a variety of control procedures to assure compliance. The Bureau of Mines will continue to assist mine operators in implementing improved dust controls and will work to identify and evaluate controls for dust generated during support advance.

Jan 1, 1983

By Harrison Schmitt

During the past decade the writer has studied and mapped certain ore deposits and their structural associations in the states of Chihuahua, Durango, New Mexico and Arizona, and he believes that these deposits, with the exception of the manto-chimney, are representative of the principal types in the area of the states named. In this paper the deposits are described; then generalizations are drawn so far as seems appropriate. Hanover, New Mexico The Hanover, New Mexico, zinc deposits were briefly described by Lindgren and others,' Paige2 and recently in more detail by Schmitt. These, the kind ordinarily called contact metamorphic, border the southern end of an oval area of granodiorite intrusive ¾ mile wide and 2 miles long (Fig. I). The granodiorite has intruded, folded, and metamorphosed sedimentary and igneous rocks, which range in age from pre-Cambrian to Upper Cretaceous. About 90 per cent of the ore has replaced coarse, recrystallized, pure, fossiliferous, lower Mississippian, nonmagnesian limestone (Hanover limestone) 110 ft. thick;4 about 75 per cent of it occurs in the upper 50 ft. of this horizon just below an 18-ft. lower Pennsylvanian shale bed, which lies on a locally inconspicuous unconformity representing upper Mississippian time. The orebodies show five shapes or attitudes, each dependent on a special structural situation: 1. Most of the ore occurs as podlike, thick lenslike or other "three-dimensional" shoots extending from top to bottom of the Hanover limestone and lying adjacent to the outer contact of a silicate zone largely of andradite, which follows the intrusive contact (Figs. 1 and 2).

Jan 1, 1935