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By Fred W. Johnson

The first section of this circular has been prepared with a view to answering inquiries frequently received by the Bureau regarding laws governing the staking of claims and regulations covering requirements for holding them and obtaining title in fee to placer ground. These laws and regulations were summarized briefly in Information Circular 6796, "Placer Mining in the Western United States." These laws, however, are administered by the General Land Office, Department of the Interior, and it has been considered advisable to combine an authoritative résumé thereof by the Commissioner of that Bureau with information on small-scale placer mining previously published by the Bureau of Mines. The second section of this circular is largely a revised reprint of Information Circular 6611, "Small-Scale Placer Mining Methods", first published in April 1932 for the purpose of answering the many daily inquiries then being received on this subject. This circular has been reprinted repeatedly, and about 30,000 copies have been distributed, most of them in response to applications therefor. At present (June 1937) requests for this publication continue to be received daily.

Jan 1, 1938

By Jerry G. Rose

This paper addresses a process by which both the disposal and utilization of preparation plant coal refuse can be simultaneously accomplished with an attendant benefit of significantly increasing the percentage of extractable coal. A laboratory study is described in which coal refuse was successfully utilized as an aggregate in low cost concrete (coal-crete) mixes under simulated mine environments. Coal-crete specimens with compressive strengths of 14,000 kPa (2,000 psi) were consistently produced. A construction sequence and mining plans are offered for placing the low-cost coal-crete pillars in accessible areas in room-and-pillar mines so that a Substantial portion of the remaining coal pillars could be extracted. The method could be applicable in areas where mining procedures do not permit pillar extraction because of possible surface subsidence, roof problems, or other conditions. Possible structural difficulties with the coal-crete pillar support system are discussed. Using a discounted cash flow analysis, the economic feasibility of mining with the coal-crete pillar system is investigated. The cost of the coal-crete pillar system is compared to the cost of a mining system which would have less coal recovery. The analysis indicates that although at higher coal selling prices the coal-crete mining system may yield an acceptable rate of return, the alternative of leaving the coal pillars is more attractive at the present time.

Jan 1, 1977

Bosworth, T. 0. The Mackenzie oilfield of northern Canada. Petroleum Times, vol. 5, Apr. 30, 1921, pp. 489-491. Jour. Inst. Petroleum Technologists, vol. 7, Oct., 1921, pp. 276-290; discussion, pp. 290-297. Gives location of the field, some of its geology, mode of occurrence and character of the oil. See also Oil Trade Jour., vol. 12, June, 1921, pp. 48-108. Canadian Min. Jour., vol. 42, May 27, 1921, pp. 420-422. Oil and Gas Jour., vol. 20, June 3, 1921, pp. 90-90. Petroleum World (London), vol. 18, June, 1921, pp. 233-2.64, 236-238, 240-241. Bull. Canadian Inst. min. and met., July, 1921, pp. 629-638. Mining and Metallurgy, Oct., 1921, pp. 47-48. Bureau of Foreign and Domestic Commerce. Resources of Balkan and Near Eastern countries. Commerce Repts., Oct. 24, 1921, pp. 488-489. Includes summary of the mineral resources of these countries, mentioning petroleum and allied substances in Roumania, Albania, Anatolia, Mesopotamia, Palestine, Arabia, Persia.

Jan 1, 1921

By J. -F. Lepage, M. A. Tomlinson, K. K. Murray

"The Éléonore mine, located in the James Bay region of Northern Quebec, generates a gold bearing flotation concentrate rich in pyrrhotite. Direct leaching of the finely ground concentrate results in high cyanide consumptions and poor recoveries, so effective pre-treatment to passivate the pyrrhotite is required before leaching. Following a number of process upsets at the mine, test work was performed to better understand the requirements for passivation so a more effective operational strategy could be implemented. This paper outlines the testing and implementation of the new strategy at Éléonore.ÉLÉONORE CONCENTRATOR The Éléonore mine is located 800 km north of Montreal, in the James Bay Region of Quebec, Canada. The ore, containing gold disseminated in sulfide minerals and free fine gold in silicate gangue, is crushed in a two-stage crusher plant before being ground in a single 9,000 kW ball mill. The ball mill is in closed circuit, with about 25% of the cyclone underflow passing through a gravity plant with two, 48” Knelson concentrators. Gold recovery in the gravity circuit varies between 15 and 20%, with gravity concentrate leached daily in an Acacia intensive leach reactor. Cyclone overflow, at a target P80 of 65 microns, flows to the flotation plant where the gold bearing sulfide minerals, mainly pyrrhotite and arsenopyrite, are recovered to concentrate with a mass pull of about 5%. The flotation concentrate, typically containing between 80 and 120 g/t of gold, is thickened and finely ground using a 1500 kW Isa Mill. The finely ground concentrate is diluted, to generate a slurry with about 32% solids by weight, before feeding the leach plant. Initially the concentrate slurry is pre-treated with oxygen and lead nitrate, to passivate the sulphide minerals before cyanide is added for gold dissolution. Gold is recovered from the leached slurry using carbon-in-pulp (CIP). The flotation tailings are also thickened and gold is recovered in a dedicated leach-CIP plant."

Jan 1, 2017

This report is the 23d in a series summarizing research and technologic work by the Federal Bureau of Mines on coal and related investigations; it is the fifth report to be issued on a calendar-year basis.2/ Publications by Bureau personnel in 1958 are cited;3/ in addition work in progress during the year is briefly described. To conserve our reserves of coal the Bureau of Mines conducts a program concerned with the development of fundamental information on coal characteristics and behavior, and the improvement of technology related to its production and utilization. The ability to anticipate and meet future demands for coal depends on a number of factors: (1) Knowledge of reserves from a stand- point of both quantity and quality; (2) the development of improved mining methods, health and safety measures, and preparation techniques that will insure its most efficient exploitation; and (3) knowledge of the controlling factors in efficient use of coal in combustion, carbonization, gasification, direct and indirect hydrogenation, and other new processes. The Bureau is concerned with each of these areas.4/,5/

Jan 1, 1960

By Donald A. Voigt

This publication is intended as a guide for persons responsible for obtaining classifications and approvals Tor explosive compounds, mixtures, or devices from the U.S. Department of Transportation (DOT). It deals with the procedures for obtaining a recommendation for classification of an explosive compound, mixture, or device through the Bureau of Mines. Completion of the procedures detailed in this guide is necessary to obtain a final classification of an explosive compound, mixture, or device and assignment of an "EX" number by DOT, which will allow the producer to offer the explosive for shipment within the United States. This guide also gives procedures for obtaining United Nations (U.N.) classification for shipping outside the United States.

Jan 1, 1990

By George W. Maynard

(Pittsburg Meeting, March, 1910.) AT the Pittsburg meeting of the Institute, May, 1879, I made the first announcement in America of the results obtained by Sidney Gilchrist Thomas and Percy C. Gilchrist, ill their efforts to eliminate phosphorus in the manufacture of steel in the Bessemer converter and the open-hearth furnace.1 The first published statement in an American newspaper was a reprint of the first Thomas-Gilchrist paper, 2 which I sent to J. C. Bayles, at that time the editor. At the suggestion of many friends who were present at the Pittsburg meeting, and others who are cognizant of the beginnings of the process in the United States, and for the information of the younger generation of the iron and steel fraternity, I have thought it eminently proper that the history of the process in detail should be given where I made the first announcement and where the process has had its largest development. During my residence in England, from April, 1873, to February, 1879, and as a member of the Iron and Steel Institute since 1874, I was present at many of its meetings during those years. At nearly -every meeting the burden of discussion was the question of the use of pig-iron containing phosphorus in the. manufacture of steel by the Bessemer or the open-hearth process. In my biographical notice of Thomas;3 read at the New York meeting of, the Institute, February, 1885, I show that the working-out of the process was not a hap-hazard or accidental inspiration, but the culmination of many years of investigation of experiments and theories which had been carried on and advanced by chemists and metallurgists at home and abroad. 1 Trans., viii., .5 (1879-80). 2 The Iron Age, vol. 22, No. 17, p. 3 (Oct. 24, 1878). 3 Trans.. xiii., 785 to 791.

Jul 1, 1910

By Hani Henein

Most metals and alloys processed undergo a solidification processing step. Increasingly, there is a growing number of solidification processing routes that involve rapid solidification of the alloy. These include strip casting, high pressure die casting, 3D printing, and atomization for the production of powders or spray formed parts. By contrast, there are few experimental techniques developed to study the solidification path of alloys during rapid solidification. Amongst these laser melting and solidification, Electromagnetic Levitation (EML) and Impulse Atomization (IA) are the most prominent. Of relevance is the formulation of the solidification path of an alloy and the resultant identification and quantification of metastable phases and their relationship to processing conditions. This typically involves the understanding of the interplay between undercooling and cooling rate for the various phases that form. This presentation will outline some of the methodologies developed to quantify phase fractions and their solidification path as a function of processing conditions using EML and IA.

Jan 1, 2016

By D. R. Tweeton

The U.S. Bureau of Mines has developed tomographic computer programs for geophysical applications and is distributing them as part of a Bureau plan to facilitate the transfer of technology to potential users. These programs were developed for predicting and monitoring the flow pattern of leach solution during in situ mining. The Bureau has also applied them to assessing high-wall blast damage and examining the integrity of mine-related geological structures. This report describes the curved ray program BOMCMTR (Bureau of Mines curved ray tomographic reconstruction), tells how to run it, and gives examples with synthetic and field data. BOMCRATR provides optional mathematical constraints to counteract the nonuniqueness of tomographic reconstructions with crosshole data. These constraints include limiting the maximum and minimum velocities, fixing the velocity at any point to any value, and establishing layers in which velocity does not vary with horizontal position. The user can test for nonuniqueness by varying the initial velocity pattern, The program can perform either curved or straight ray analysis. Ray paths are calculated analytically in triangular pixels, which is faster than incremental numerical approximations,

Jan 1, 2010

By David M. Gullikson

As part of its program of petroleum production research the Federal Bureau of Mines has long been engaged in the study and development of systems of analysis of oilfield waters (8, 12, 20, 21, 22, 27, 30).21 However, many of the early chemical procedures developed by the Bureau and widely adopted by the petroleum industry are time consuming, and some are unreliable for determining certain constituents found in California oilfield waters. Because of the need for more rapid and more accurate methods having greater sensitivity with low concentrations of some constituents, a study has been made by the Bureau's Petroleum Research Laboratory at San Francisco, in developing new techniques and modifying previously published techniques for analyzing oilfield waters by flame spectrophotometric, potentiometric, and colorimetric methods. Test solutions were synthesized for testing the suitability and accuracy of the procedures, and the effect of interfering ions. These solutions contained known quantities of characteristic constituents of oilfield waters including sodium, magnesium, potassium, calcium, lithium, strontium, barium, sulfate, chloride, bromide, iodide, carbonate, bicarbonate and borates in a wide range of concentrations. The compositions of these synthetic brines are listed in table 22. Many California oilfield waters contain salts of petroleum-derived organic acids and several synthetic oilfield waters also were prepared to which large quantities of naphthenates or salts of petroleum acids were added.

Jan 1, 1961

By Neda Zangeneh

Production efficiency from low permeability gas shales require techniques to optimize hydraulic fracture completions. One completion strategy involves the simultaneous or near simultaneous hydraulic fracturing of multiple horizontal wells to maximize the fracture network area and stimulated reservoir volume. However, changes to the in-situ stress field caused by an earlier hydrofrac on subsequent hydraulic fractures are not accounted for in traditional hydrofrac design calculations. Presented here are the results from a set of transient, coupled hydro-mechanical simulations of a rock mass containing two wellbores using the discontinuum-based distinct-element method. The results demonstrate the influence of stress-shadows generated by a hydraulic fracture on the development of subsequent hydrofracs from an adjacent well. It is shown here that these interactions have the potential to change the size and effectiveness of the hydraulic fracture stimulation by changing the extent of the hydraulic fracture around the secondary well.

Jun 1, 2012

By M Singh, R C. Steinhaus, J J. Rust

Metallurgical process control systems in mineral plants often employ state-of-the-art monitoring analysers in an attempt to optimise plant operations and enhance mineral recoveries. These systems are unfortunately invariably fed by simplistic ‘sampling’ designs consisting of various in-stream methods or pressurised probes. These are unfortunate compromises and provide a false picture of what a mineral flotation or other process can achieve. The situation is further aggravated by some manufacturers using misleading marketing to suggest discrete cross-stream methods for metallurgical accounting and unreliable continuous in-stream off-takes for control sampling and that they are of synonymous integrity.Reliable, absolute or representative samples are often absent in many modern day concentrator plants, due to compromises around sample taking, particularly in terms of delineation and extraction errors and thus leading to sample bias. For more reliable information from online analysers we need a continuous, but much more reliable sample taken, than is current practice.Online analysers require a fully proportional and continuous supply of sample for effective process control, otherwise maximised or benchmark recoveries will be nothing but a pipe dream. Large discrete cross-stream samples from mechanically less reliable equipment cannot be used as feed to online analysers, as it will negatively impact real-time feedback and efficient process control.It is possible to build correct sampling systems that could do both process controls online and metallurgical accounting at the same time. Multotec Process Equipment (Pty) Limited, in close association with experienced sampling consultant Francis Pitard, have jointly patented a concept to achieve this and which is embodied in the design of the unique Rotating Cone® Sampler (International Patent Application No. PCT/IB2016/057464). This versatile unit for dry and wet applications has high division ratios via two-step sampling and division.A prototype was built and tested to validate the design and levels of precision achievable when employing the unit to split dry mineral fines or even certain foodstuffs.CITATION:Steinhaus, R C, Rust, J J and Singh, M, 2017. Does process control sampling always have to be a compromise?, in Proceedings Eighth World Conference on Sampling and Blending , pp 197–202 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By J. -C. Tricket, W. A. Düweke, S. Kock

The high-resolution three-dimensional (3-D) seismic reflection data acquired for Impala Platinum between 1998 and 2002 in the western Bushveld Igneous Complex form an integral part of Impala?s mine planning and development programme. These data are of sufficiently high quality to provide unprecedented 3-D models of the geological structure of the Merensky Reef and UG2Chromitite Reef, from which the mine deduces the size, geometry and distribution of mineable blocks. Conversely, the seismic data details zones of un-mineable ground caused by structural disturbances in the form of potholes, fault zones and pegmatoid intrusions. Furthermore, variations in dip and strike are well imaged, allowing the mine planners to optimize the mine design and layout. Current interpretation work is focused on enhancing the accuracy of these geological model seven further through the analysis of ?seismic trace attributes.? Preliminary testing on the Impala Platinum 3-D seismic volume has shown that attribute analysis has the potential to illuminate a number of geological reef disturbances that are otherwise ?invisible? in the original seismic time volume. Potential areas of improvement include inter alia: ?Improved definition of major fault zones ?Improved definition of zones of reef depression (?slumping?) ?Identification of reef terracing and/or reverse dip.. Keywords: 3D reflection seismics; Impala Platinum Ltd; seismic attribute analysis; Seismic Micro Technology (SMT); rock solid attributes; dip-azimuth; instantaneous phase and similarity.

Jan 1, 2004

By George Hope, Brigitte Lacouture

"The Red Dog mine has increased mill throughput most years since start-up. Although flotation equipment has been added over the last 10 years, the Red Dog metallurgical performance has been restricted by a lack of adequate flotation capacity. Two reduced tonnage trials conducted in 1997 as well as numerous SAG relines have consistently indicated the potential to significantly increase both zinc concentrate recovery and grade with additional flotation capacity. Later in 1999, a new circuit was designed with increased flotation capacity while simplifying the current circuit, providing for three stages of dilution cleaning, and creating a retreat section. The purpose of the retreat section is to target the more complex particles and allow the chemical environment to be fine tuned for improved iron depression. In total, 21 Outokumpu OK50 (50 m3) mechanical flotation cells and four 3.66 mØ column cells were added to the current flotation circuit. The VIP (value improvement program) mill optimization project is also addressing thickening, water treatment, and power generation issues and has a total budget of US$105 M. Start-up of equipment was phased in to minimize the impact on current operations and the project was completed by the end of 2001. IntroductionRed Dog Operations started production in November 1989. The mine is located above the Arctic Circle in northwest Alaska. It is linked by an 80 km road to a port-site facility where the concentrate is stored. Concentrate is shipped to markets throughout the world during the one hundred days of open seas. As of January 2002, the Red Dog main pit had 38.4 Mt of reserves grading 19.2% Zn, 5.3% Pb, and 102 g/t Ag. Additional reserves and resources contribute an additional 72 Mt at 15.6% Zn, 4.2% Pb, and 78 g/t Ag. Red Dog is a Mississippian to Permian, black shale-hosted, zinc-lead-silver deposit located in the DeLong Mountains, western Brooks Range, Alaska. All the rocks associated with the mineralizing event are considered to be part of the exhalite rock package. Silicification was a dominant component of the mineralizing event and the host shale has been silicified and locally resembles a chert. The major sulphides in decreasing order of abundance are sphalerite, pyrite, marcasite and galena. Most of the deposit’s silver occurs within the crystal structure of the galena. The dominant ore mineral, sphalerite, is very fine grained to amorphous and is commonly intergrown with silica. Ore textures are massive, fragmental, chaotic, veined and rarely show classic sulphide sedimentary layering. The upper portion of the orebody has been physically and chemically weathered. Oxidation has altered the sulphides to sulphates. The zinc and iron sulphates are very soluble and are readily depleted from the weathered cap, while the lead sulphate is residual and is, therefore, enriched."

Jan 1, 2003

By M. J. Marcinkowski, A. Szirmae, R. M. Fisher

Room -temperature hardness measurements obtained from single and polycrystalline samples of a 47.8 at, pet Cr-Fe alloy which were aged for various times al 500°C show a two-fold increase over that of the unaged alloy after annealing for 1000 hr. A detailed examination of the deformation markings in the neighborhood of the hardness imbressions reveals that twinning becomes an increasingly more important mode of deformation as aging proceeds. this observation is shown to be inconsistent with the Proposals that the transformation is eve of order-disorder On the other hand, the results are in agreement with previous observations of Fisher et al. of a coherent chromium-rich precipitate which forms in an iron-rich matrix as a result of a miscibility gap in this alloy system as proposed by Williams . Using the coherent precipitate hypotlzesis as a model, a detailed analysis of the various possible strengthening contributions to both the slip mid twinning stresses is made. In the case of' slip, lattice friction within the chromium-rich phase and the chemical energy associated with the interface between the two phases contribute about 60pet to the total strength. The contributions from coherency strains and modulus differences are thought to contribute the remaining 40 pet of the strength but are difficult to evaluate because of uncertainties regarding the flexibility of the dislocation line. All of the factors have nearly the same or else a smaller effect on the twinning stress in the aged alloy. Twinning is never observed in the unaged alloy because the twinning stress is much higher- than that for slip. With increased aging times, the various contributions to the total stress for both twinning and slip increase, but most of those for slip increase much more rapidly, so that, in the fully aged alloy, it surpasses the stress for twin propagation. When a twin is nucleated by the chance occurrence of an internal stress concentration during a test, the subsequent twin burst results in a low hardness reading. FeRNTIC Fe-Cr alloys from about 15 to 80 at. pet Cr content show considerable change in properties such as hardness, electrical resistivity, saturation magnetization, and so forth, after aging in the vicinity of 500°C.* The most marked change is a large increase in hardness accompanied by a sharp decrease in ductility, so the phenomenon has often been referred to as the 475°C (885°F) em-brittlement problem. Changes in microstructure are rather subtle and most investigators have not been able to observe any X-ray diffraction or metal-lographic changes during aging. There is little doubt that the phenomenon is inherent to the Fe-Cr binary system and is not directly related to the formation of a phase. Two distinct schools of thought have developed during the past decade concerning this problem. Masumoto, Saito, and sugiharal have concluded, from their own specific-heat measurements, that atomic ordering occurs in this temperature range. Pomey and Bastien2 have also attributed the changes in physical properties with aging in the neighborhood of 500°C to atomic ordering. In addition, Takeda and Nagai3 claimed to have found X-ray verification for superlattices corresponding to the compositions FesCr, FeCr, and FeCr3. However, all known attempts to observe superlattices in Fe-Cr alloys using neutron diffraction, which should be much more sensitive, have been unsuccessful. These have been reported by Shull et al.4 for 25 at. pet Cr, williams5 for 75 at. pet Cr, and Tisinai and samans6 for a 28.5 at. pet Cr. steel. The second and more prevalent opinion ascribes the 475°C embrittlement phenomenon to the formation of a coherent precipitate due to the occurrence of a miscibility gap in the Fe-Cr system below about 550°C. This latter concept was first indicated by the results of Fisher, Dulis, and Carroll,7 who were able to extract fine particles about 200Å in diameter from samples of 28.5 at. pet Cr steels aged from 1 to 3 years at 475°C. The extracted material was found to be nonmagnetic, to have a bee structure with a lattice parameter between that of iron and chromium, and to contain about 80 at. pet Cr. Williams and paxton8 and williams5 confirmed these results and first explicitly proposed the existence of a miscibility gap below the a region in the equilibrium diagram. Alloys aged within this gap

Jan 1, 1964

By Dunlop A. C

A brief study from the Mt. Bulga prospect com- pares the chemistry and mineralogy of different soil fractions and other materials to suggest a sequence of surficial metal dispersion from adjacent gossans, which may have relevance for geochemical exploration in semi-arid terrains. v v v v v JIV-- v v v v a o v o/ v v v v 1 v v lv ./v '' 1 v 16400N ..I v 1635014 v 1630014 .:1 ò.t SILURIAN sillstone " lelsic volcanic sillstone -sandstone ORDOVICIAN Eandesite o quartz float gossanò pits doOP Iv o shalt v _--'fault v 1---1 soil traverse v v v v 0 100 200 mm e Fig. I Local geology and location of soil traverses, Mt. Bulga (compiled from Chisholm, 1976). The Mt. Bulga prospect in central New South Wales is a small but well documented volcano- genic massive sulphide occurrence (450,000t of 0.8% Cu, 1.3% Pb, 5% Zn and 0.45 g/t Au) Cambrell and Kirk (1974), and Chisholm, (1976). Mineralization is localised near the interface of felsic pyroclastics with overlying silt- stones and along adjacent faults (Fig. 1). In this area with a Koeppen type cf6 climate, soils are thin and skeletal along ridges with thicker and better differentiated profiles with a colluvial component up to 2m thick developed

Jan 1, 1988

By W. M. Armstrong

This paper compares research on development efforts in various countries, consideration being given to gross expenditures, manpower involved, source of funds, sector of performance and type of activity. The Canadian R & D activity is then reviewed, particularly as applied to the industrial sector, the problems of applied research in Canada are discussed and some remedies are suggested.

Jan 1, 1968

By Dennis N. Poffenroth

One concern of the Mine Safety and Health Administration is the structural integrity of steel wire ropes used on mine personnel hoists and elevators. Failure of such ropes has resulted in loss of life and property. Although thorough and regular visual examinations are performed, hoist ropes may still fail from undetected internal wear, corrosion, and broken wires. To complement visual examinations, nondestructive rope inspection techniques have been developed to determine deterioration and removal criteria. The techniques use electromagnetic and permanent-magnet test instruments designed by a Canadian firm. This paper describes the operating principles, field and laboratory testing of these nondestructive testing instruments, and discusses the feasibility of using this type of testing as a supplement to visual examination and destructive tests.

Jan 1, 1983

By G Jones

The Singapore Land Transport Authority (LTA) has been procuring the expansion of their underground mass rapid transit rail network at a prodigious rate since the first line opened in 1987. Four lines (149 km) are currently operating and several more lines are at various stages of planning/construction; one of these is the Downtown line stage 2 (DTL 2).DTL 2 contract C917 was awarded in September 2009 for S$320 M. On 18 June 2013 the original contractor became insolvent, leaving the works incomplete. Following a fast-tracked tender process, McConnell Dowell was awarded the S$254 M contract on 29 August 2013 to complete the works. This contract includes two underground stations constructed by cut-and-cover methods and twin bored tunnels between the stations. Each tunnel is 1400 m long, excavated by earth pressure balanced (EPB) tunnel boring machines (TBM) at an average depth of 20 m and segment lined to 5.8 m inner diameter. The tunnel alignment is located under a busy five-lane road lined with prime residential real estate and congested with utilities.To compound the difficulty the tunnels are located within the notorious Bukit Timah Granite formation. This has a very wide range of strength, from below 1 MPa to over 300 MPa. This strength range is a consequence of six weathering grades, from soil to fresh rock, with the fresh granite causing severe abrasion problems. The various grades can occur within a very short distance of each other. Consequently, the problem of supporting a mixed face exists, particularly in the intermediate weathering grades where intact rock is encountered in the invert and corestones within a loose soil matrix in the crown, which can increase the instability by allowing the ground to flow into the TBM.The focus of this paper will be the excavation of the bored tunnels by EPB TBM used by McConnell Dowell to complete these challenging works.CITATION:Jones, G and Shepherd, J, 2014. Earth pressure balanced tunnelling in a dense urban environment, C917A, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 41–50 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By Patricio González Santis, Jacopo Seccatore

This paper documents drilling and blasting activities from gold mining in Ecuador and Chile. First, are described the outdated and often non-rational techniques employed by miners, to provide a general framework of the current methods. Then, it is shown what can be improved and how the current methods can be modified. Finally, are shown some field applications and the comparisons of the results obtained

Feb 1, 2020