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By Scott A. Shapkoff

High strength cable strand supports are predominately used as a supplemental means of ground control in longwall and development operations in the U.S. The advantages of cable strand supports have been documented and include flexibility, strength, and ease of installation. Since the majority of cable supports installed in the U.S. today are partially grouted, and this same segment of supports has no inherent installed tension, the supports are considered currently arbitrarily strictly supplemental and therefore, cannot currently be deemed primary support (in most mining districts). This paper details and discusses two distinctly different configurations and the technical advantages of active partially grouted cable supports for certain primary support applications. The evolution of the designs for both systems is highlighted. Field data illustrates the amount of active load in relationship to installed torque and the affects that component variables have on this load measurement. Roof control patterns using active cable supports are examined as alternatives for combination patterns using primary and supplemental systems. The importance of maintaining consistent installation procedures plays an important role in the level of performance of the system. Economics comparing the installation of active cables with other primary/supplemental patterns is also included.

Jan 1, 2006

By J. F. Lupo

There are numerous mines throughout the world that have open pit highwalls developed partially or wholly in soil or soil-like materials. Soil-like materials are considered to include soils (either transported or residual) and highly weathered rock, which may have soil-like behavior. These materials generally have characteristics or material properties that vary considerably from those of moderately weathered or fresh rock. Given these differences, it is important to consider the characteristics of soil-like materials to design safe open pit slopes. In the design of open pit slopes in soil-like materials, it is important to recognize the behavior of these materials is strongly dependent upon their mineralogy, degree of weathering, cementation, stress history, depositional history, and presence of water. As a result, soil-like materials may contain one or more of the following characteristics that can have a significant effect slope stability and design: - Relict structural features (joints, faults, etc), - Sensitivity to moisture (both wetting and drying), - Zones of alteration with variable strength and drainage characteristics, - Zones of low permeability creating perched ground water conditions, and - Undrained and drained strain softening or strain hardening behavior.

Jan 1, 2011

By D. M. Doyle

"A study of the various components contributing to energy costs and their relationships to generally trended operating data, such as tonnage, operating costs, etc. over progressively shorter time periods provides information for an energy audit. A study of annual data gives some insight into the importance of various energy components. As the time frame of the study 11rogresses through monthly, daily and finally, into quarter hourly data, the variations become more evident and most important, strategies develop to minimize energy costs. The results of an audit conducted during the summer of 1978 at Wesfrob Mines are reported to illustrate this important phase, prerequisite to a meaningful energy cost avoidance program.The balance of the paper deals with the energy conservation program at Falconbridge Nickel Mines Sudbury Operations, the material and control equipment, the commitment, the new energy accounting practices and lastly, the policies. Examples of successful energy conservation endeavors include automatic peal electrical load control, waste heat recovery from mine air and compressor cooling water, energy reductions resulting from lower building temperatures and curtailmen: of idling loads. The use of pulse meters to measure the flow of gas, steam, compressed air and electrical energy, with their signals interfaced to process computers, allows monthly, daily and if necessary, immediate reporting of energy and energy per unit of production information. The program so reported at Falconbridge’s Sudbury Operations is credited with an annual cost avoidance of .9 million dollars in a 14.0 million dollar annual energy account."

Jan 1, 1979

By H. Ozturk

In this paper, the computer program ‘SHAFT’ developed for estimation of support requirements for circular mine shafts is introduced. Theory of support design is based on the analytical solutions of circular excavations under non-hydrostatic loading (Detourney and St. John1), and Lame’s thick-wall cylinder theory (Timoshenko6). For rock mass strength property determination Hoek-Brown failure criterion (Hoek et al.2) is used. Mainly two types of support, concrete and steel are taken into consideration as a support member. Program is written in Quick Basic language. Input parameters of the program are shaft radius, number of zones having the same properties along the shaft depth, and depth, unit weight, horizontal to vertical stress ratio, GSI, and uniaxial compressive strength of intact rock of each zone, and compressive strength and safety factor of support member. Output of the program is the graphical representation of shaft with the required support member and thickness throughout the depth of the shaft.

Jan 1, 2003

By M. B. McClenaghan

"This paper summarizes diamond exploration techniques used in glaciated terrain, focussing on indicator mineral and geochemical methods applied to glacial sediments. Understanding the ice flow history, depositional history, and stratigraphy of glacial sediments is essential to successful sampling, interpretation and follow-up of indicator mineral and geochemical anomalies related to kimberlites. Kimberlite indicator minerals survive glacial transport over long distances and the relative abundance of each mineral in till is a function of the primary mineralogy of individual kimberlites. Indicator mineral distributions observed at a regional scale define the net effect of glacial dispersal, often along different ice flow directions. Local-scale distributions define individual dispersal trains. The medium sand (0.25 mm to 0.5 mm) fraction of heavy mineral concentrates, * GSC Contribution No. 2002028 prepared from glacial sediment samples, is best suited for indicator mineral surveys. The application of till geochemistry to diamond exploration is increasing because it is significantly cheaper than indicator mineral analysis and it can be performed quickly. The <0.063 mm (silt+clay) and 0.5 mm to 2.0 mm (coarse sand) fractions provide the best geochemical contrast between background and kimberlite-rich till. Kimberlite pathfinder elements that provide good contrast include Ni, Cr, Ba, Co, Sr, Rb, Nb, Mg, Ta, Ca, Fe, K, Ti and LREE, the relative importance of which will depend on kimberlite composition and that of the surrounding bedrock.IntroductionIn Canada, glacial erosion is the principal means by which kimberlite and its associated minerals have been dispersed, from a few tens of metres to tens of kilometres down-ice. Post-glacial weathering has had little impact on kimberlite debris in the glacial sediments, thus boulder tracing, indicator mineral methods and trace element geochemistry of the fine fraction of till (“drift prospecting” methods) can be used to detect kimberlite dispersal within areas covered by glacial sediment. This paper provides a summary of drift prospecting methods for kimberlite exploration in glaciated terrain, and includes examples of reconnaissance- , regional- and local-scale kimberlite indicator mineral and till geochemical distribution patterns.Weathered kimberlite is more susceptible to glacial erosion than the surrounding bedrock, thus many kimberlites in glaciated terrain are found in low or swampy ground, under small lakes, or covered by thin (< 1 m) to thick (>50 m) glacial sediments. Glacial erosion has removed varying amounts of the pre-glacially weathered kimberlite and, in some cases, the hard competent kimberlite below. For example, glacial erosion of the Peddie, McLean and Seed kimberlites near Lake Timiskaming, Ontario, removed pre-glacially weathered kimberlite, leaving a polished striated subcropping surface (McClenaghan et al., 1999a). In contrast, glacial erosion of the B30 kimberlite, near Kirkland Lake, Ontario (Fig.1), was much less vigorous and left a >10 m cap of soft and highly weathered dark green clay-rich kimberlite (McClenaghan et al., 1996). The thickness of remaining pre-glacially weathered kimberlite will influence the geophysical signature of the kimberlite."

Jan 1, 2002

By Vinícius Resende Domingues, André Pacheco de Assis, Bernardo Cascão Pires e Albuquerque

"The increasing demand for underground works in urban centers, and in particular the need to build undercrossing tunnels, requires constant evolution in building techniques in order to achieve success and safety. In the case of Brasilia, capital of Brazil, in order to preserve an important avenue (Eixo Monumental), where are located many historical monuments, the construction of a tunnel was envisioned as an option to interconnect the National Stadium (on one side of the avenue) to the Convention Center Ulysses Guimarães (on the other side). The excavation design is comprised of a coverage smaller than one diameter, height of 7.5 m, width of 9.0 m and length of 25 m. In order to enable a negligible influence on the avenue’s usage, the structure is designed as a portico system composed of pipe canopy. In this context, this study presents the portico analytical solution computed with the aid of the software Mathematica and a numerical solution using the software ABAQUS. INTRODUCTION Undercrossing tunnels are increasingly common in urban centers as alternative roads or as access to underground works of large dimensions (stations and parking lots). The geomechanical conditions of the soil mass, not always favorable, and the low distance between tunnel’s ceiling and the surface require intense treatment of the soil massif and execution of a rigid support system. The importance of the road just above the undercrossing tunnel emphasizes the need for a highly competent monitoring system because existing structures require minimum allowable displacement and do not allow the interruption of traffic. The soils that are excavated for the construction of undercrossing tunnels are composed, in most cases, of layers of fill and / or soft soil or weak rock, showing stability problems when subjected to tunneling operations. The combination of low coverage and week ground is solved by soil improvement techniques and strengthening of the excavated cross-section with further advance with the so-called New Austrian Tunneling Method (NATM). Another option is to build structural frames that support the surface. In this research, and based on the context of a case study, we propose the study of the construction technique comprising a portico structure composed of pipe canopy. For this paper, the technical standards used are the Brazilian ones as the case study refers to this country."

Jan 1, 2016

By J. S. Hansen

In support of its objective to conserve mineral resources by minimizing premature failure of materials, the Bureau of Mines conducted a cooperative study with the U.S. Department of Energy on the erosion and abrasion resistance of hard materials for valves in coal conversion systems. This report describes a newly developed erosion-testing apparatus and presents data on the erosion resistance of over 200 materials. Erosion resistance of most metals was comparatively low. In contrast, ceramics and cermets such as B4C, WC, SiC, Si3N4, and TiB2, when fabricated to minimize porosity, displayed greater than five times the erosion resistance of metals. Coatings such as boron diffused into Mo and WC, chemical-vapor-deposited TiCN, and electrodeposited TiB2 were highly erosion resistant if applied in thicknesses ranging from 60 to 75 µm. Erosion resistance of cemented carbides was inversely related to metal binder content.

Jan 1, 1979

Contract No. H0110929 was awarded by the U.S. Bureau of Mines in February, 1971, to DeTer Company, Incorporated, of Mountain Lakes, N. J. The contract provided for the modification of the contractor&apos;s Model 5000 Pressure Foam Generator to fit it for the suppression of coal dust in mines, a detailed testing program in a working coal mine, and for additional modifications and testing for the suppression of fires in coal mines. The contractual program was completed in April, 1972. The results of the dust suppression tests showed conclusively that the modified DeTer equipment effectively reduced the level of respirable dust in a working coal mine well below the present and future acceptable levels set by the Mine Health and Safety Act of 1969. The fire tests, carried out in a simulated mine entryway erected on the surface, demonstrated the ability of the DeTer equipment in suppressing fires of varying degrees of severity within an acceptably short time.

Jan 1, 1972

By T. Yeomans

NVI Mining’s Myra Falls operation is a forty-year-old underground mining operation feeding a 4,000 metric tonnes per day concentrator. The current mill, built in 1985, was designed to process a massive sulphide ore-body. This orebody, known as the HW, contains about 50% pyrite. Minerals of value are chalcopyrite and sphalerite, with precious metals occurring in all mineral types. By 1997, mining of a new ore-body, known as Battle-Gap, commenced. Mineralogically complex, the new orebody contains about 15% pyrite copper minerals, including primary chalcopyrite and secondary bornite, chalcocite and tennantite, combined with increased galena and sphalerite. Flotation performance generally decreased with increasing amounts of Battle-Gap ore types, with both copper concentrate quality (increased lead and zinc content) and copper recoveries being affected. Following significant metallurgical test-work, a new, fully sequential copper-lead-zinc flotation flow sheet and reagent scheme was developed. This sequential flow sheet was progressively installed and commissioned during 2006. Copper concentrate lead and zinc smelter penalty contents have been reduced by some 40%, while increasing copper recovery by 10%.

Jan 1, 2009

By R. H. Wright

This paper describes the design philosophy and methods employed in constructing the foundation elements for the Little Britain Project in the City of London. The Contract is a design and construct package for the foundations of a 3-storey basement which will be built using "top-down" construction techniques and is to be carried out by Fairclough Piling and Marine on behalf of Wimgrove Nominees. The Project includes 8000 sq.m. of diaphragm wall and barrettes 139 No. large diameter piles ranging from 900mm to 3000mm in diameter and up to 45m deep, and 9 No. cruciform barrettes for the heaviest column loads. Major factors influencing the design of these foundations include differential settlement, heave analysis and a fast track construction approach. Little Britain will provide 43000 sq.m. of space in two linked buildings which will bridge a new road joining London Wall to Newgate Street. The foundation contract is well advanced and the building is due for completion in the Summer of 1990.

Jan 1, 1989

By J. Winterton

Estimating the residual metal inventory of large heap leaching operations is desirable for many reasons. Several methods have been tried with limited success. Drilling data from the Valley Leach Facility at AngloGold Ashanti&apos;s Cripple Creek and Victor Gold Mine has been used to develop a robust inventory estimation technique. The technique is presented along with discussion of the particular inventory components and evaluation methodologies.

Feb 27, 2013

By Zhang Jiaju

For the highrise buildings with deep foundstion of irregular plane shape, an appropriate calculate model to the heave of foundation soil after excavation is proposed and studied using analytic method and FEM (Finite Element Method) respectively to provide an effective way for solving this kind engineering problem. Also combined with the practice of construction deep foundation of Capital Mansion, calculation of the heave of foundation soil after excavation is given. Compared these results from above two methods with the results measured in situ, it is conformal on the whole, and the results by FEM are much closer with the measured.

Jan 1, 1991

By M. E. Kuchta

Research is currently being conducted at the Colorado School of Mines in the use of high-pressure water for scaling down loose rocks in underground mine openings. In addition to improved miner safety, the adhesion strength of shotcrete applied to rock surfaces treated with high-pressure water is also increased significantly resulting in improved overall support capabilities of the shotcrete layer. Test results show an increase in adhesion strength by a factor of four on a concrete test wall cleaned with water at 21 Mpa (3000 psi) as compared to a surface cleaned at 0.7 Mpa (100 psi).

Jan 1, 2002

By R. P. Gardner

Results of work on the development of a phenomenological model for the continuous flotation process using short-lived radioactive tracer techniques for the determination of model parameters is reported. A model that incorporates a flotation first-order rate constant and a residence time distribution based on the cross flow finite state (CFFS) model has been derived and investigated. The short-lived radioactive tracer techniques necessary to extract the model parameters have been developed as have the necessary nonlinear search methods. The conditions under which all the model parameters can be extracted from a single radiotracer experiment are detailed and illustrated. A microcomputer-based unique data logging system has been designed, assembled, and implemented for collecting the necessary transient radiotracer data. Results are reported for a continuous laboratory flotation system for the two systems mica ore and coal.

Jan 1, 1985

By M. K. Foster

Ten horizontal retort zinc blocks of a modified Hegeler design are in operation at Nueva Rosita, Coahuila, Mexico, and produce approximately 170 t of spelter daily, or 62 000 t/year. A block consists of two furnaces of 448 retorts each, making 8960 retorts as the plant complement. Each furnace block is fired with natural gas and air maintaining the combustion mixture in the furnace always slightly reducing. No attempt to recover energy through waste heat boilers is made. The spelter moves to market by rail and truck either in palletized bundles weighing approximately 1060 kg, as loose slabs weighing 26.5 kg each, or as 1088 kg ingots. At present 46% of the metal is exported and 54% is consumed domestically in Mexico. The present day trend toward equalized or alloyed spelter, as well as special shaped castings results in sales of 35% of the entire plant&apos;s production. Sulfuric acid is also produced by the Contact Process using vanadium pentoxide as the catalyst. The plant is basically a Monsanto contact system, producing approximately 68 t of 100% sulfuric acid daily. Both 98.5% sulfuric acid and 20% oleum are available. All of the acid made is consumed in Mexico. Shipments are made in 26,900 dm3 tank cars.

Jan 1, 1970

By Wenshan Zhang

Three important methods of removing Fe in hydrometallurgy of zinc, manganese, copper, nickel, cobalt and etc are described, including neutralized hydrolysis method, jarosite method and goethite method. The reactions, technical requirements and thermodynamic analysis during Fe removal process are also discussed in this paper.

Jan 1, 2006

By James W. Myers

"Packaged fuel" is the trade name applied by the industry to a product consisting of coal screenings and a binder compressed into 3 -or 4-inch cubes and wrapped (six or eight in a package) in sturdy paper and sealed with gummed tape. Parry describes the product in greater detail and distinguishes clearly between packaged fuel and briquettes. The industry developed from the desire of retail coal dealers to improve utilization of the relatively large quantities of slack sizes that result from the degradation, during shipping and handling in the yard, of friable coal, particularly Pocahontas coal. During the war an attempt was made to apply this technique to anthracite fines, and a recent publication of the U. S. Bureau of Mines reported the results of physical and combustion tests on packaged fuels containing anthracite fines. References made in this report to the previous investigation on packaged fuels containing anthracite represent data or conclusions presented in Report of Investigations 3882. This investigation was conducted as a continuation of the previously reported studies and consisted of physical and combustion tests of packaged fuels made from high-volatile bituminous coal, as well as the low-volatile bituminous coal ordinarily used in the industry, to determine their relative suitability for domestic firing. Particular attention was given to the smoke-producing properties of the packaged fuels because of the increasing importance of the prevention or reduction of smoke from hand-fired domestic heating plants resulting from the widespread enactment of smoke-prevention ordinances.

Jan 1, 1951

By W. P. Diamond

The direct method test was developed for general mine safety applications by the U.S. Bureau of Mines in the early 1970&apos;s to measure the gas content of coal samples obtained from the relatively shallow depths of eastern U.S. coal mines. Over time, applications for gas content data evolved which required increasingly accurate desorption values. It became evident that some of the inherent weaknesses in the original direct method test could best be addressed by abandoning the water displacement based desorbed gas volume measurements. The ideal gas law based modified direct method (MDM) and associated desorbed gas volume measurement apparatus was developed to provide the most accurate desorption values possible for rock samples obtained from any gas-bearing strata. The MDM has a number of significant advantages, including: (1) increased accuracy, especially for low gas content samples, (2) a test apparatus with an integral sampling port to facilitate the collection of uncontaminated gas samples, (3) an inherent head space effect correction in the periodic MDM desorbed gas volume calculations, (4) measurement of positive and negative desorbed gas volumes, (5) elimination of differential gas solubility effects as a source of error inherent in the water displacement methods, and (6) a compact and rugged test apparatus that along with the elimination of the ?glassware? required for the water displacement methods, facilitates its use in the field.

Jan 1, 2008

By Gerrit V. R. Goodman

A laboratory study assessed the impacts of water spray pressure, face ventilation quantity, and line brattice setback distance on respirable dust and SF6 tracer gas concentrations around a continuous mining machine using a sprayfan or directional spray system. Dust levels were measured at locations representing the mining machine operator and the standard and off-standard shuttle car operators, and in the return airway. The results showed that changes in all three independent variables significantly affected log-transformed dust levels at the three operator sampling locations. Changes in setback distance impacted return airway dust levels. Laboratory testing also identified numerous variable interactions affecting dust levels. Tracer gas levels were measured on the left and right sides of the cutting drum and in the return. Untransformed gas levels around the cutting drum were significantly affected by changes in water pressure, face ventilation quantity, and setback distance. Only a few interactions were identified that significantly affected these concentrations. Gas levels in the return airway were grouped by face ventilation quantity. Return gas levels measured at the low curtain quantity were generally unaffected by changes in water pressure or curtain setback distance. At the high curtain quantity, return airway gas levels were affected by curtain setback distance. A field study was conducted to assess the impact of these parameters in an actual mining operation. These data showed that respirable dust levels may have been impacted by a change in water pressure and, to a lesser extent, by an increase in curtain setback distance. A series of tracer gas pulse tests were also conducted during this study. The results showed that effectiveness of the face ventilation was impacted by changes in curtain flow quantity and setback distance. Laboratory testing supported similar conclusions.

Jan 1, 2004