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By Reichardt Y

Fine feed fractions in the size range from 1 to 40 ¦m of materials with different hardness as limestone and silicon carbide have been stressed in two different devices. A tungsten-carbide-blodc allows a single stressing with a pressure up to 2000 MPa and a 4-piston-block enables a multiple stressing procedure in which the material bed is stressed in alternating directions with a pressure up to 700 MPa. The experiments show energy absorption as the major factor for the interparticle breakage of hard material, like quartz, zircon silicate, silicon carbide and smelted oonindum, pressure, however, does not influence the results within the investigated range from 100 to 700 MPa and even up to 2000 MPa for corundum. But the breakage of the middle-hard limestone depends on the pressure so far as more fineness can be produced if the same energy is introduced at a lower pressure level. The creation of very fine and microfine fragments decreases strongly with increasing hardness of the feed materiaL The energy consumption for producing microfine material with a multiple stressing procedure on a particle bed is much lower than that one of a usual milling process. But this procedure needs a classification with a seperation cut at a couple of microns, which is not easy to accomplish.

Jan 1, 1993

By Anthony Anable

THE definite trend to stricter specifications with respect to hydraulic concrete has become increasingly manifest in the last six years or so; but it remained for the vast reclamation projects of the Bureau of Recla-mation of the Department of the Interior of the last few years to focus attention on this trend, and to demonstrate how thousands of tons of concrete-making aggregates can be produced continuously and auto-matically with a control of fineness comparable with that obtained with small samples in well equipped private and governmental laboratories. Pioneer work in this direction was done, to be sure, by private com-panies, notably the Kaiser Paving Co. of San Francisco, prior to the present vast public works program. Then in 1931 came the first great, aggregates-preparation plant of the Six Companies, Inc. to supply construction materials for Boulder Dam' in Nevada, and now, in 1936, the aggregates plant of the Mason-Walsh-Atkinson-Kier Co., general con-tractors on the Grand Coulee dam in Washington. At Boulder dam and to an even greater degree at Grand Coulee dam, sand production is recognized as probably the most important single element affecting the physical characteristics of the concrete. For in the construction of dams accurate grading of the fine aggregate has consider-able bearing on the attainment of a uniform and homogeneous concrete of a high degree of workability and placeability and, at the same time, combining high density and low cement content. Low cement content is of value not only from the standpoint of economy but also because the use of an unnecessarily rich concrete causes certain undesirable characteristics to develop. This paper will relate how at Grand Coulee dam methods that are more advanced than ever before are producing four sizes of gravel and a sand having a fineness modulus of 2.5-3.0. The design capacity is 1000 tons an hour. Significantly, the methods and equipment employed are broadly those that have been used for a generation in metallurgical mills for accurately sizing and grading both precious

Jan 1, 1936

By B. J. Walsh

ABSTRACT Segregation of sphalerite minerals in zinc concentrates into christophite, marmatite and ordinary sphalerite by means of magnetic fractionation is investigated. A Frantz ferromagnetic filter, 1.2 amp., and a Dings magnet, 0.3 amp., is used to fractionate seven zinc concentrates produced in the Province of Quebec. The Dings magnetic product contains the pyrrhotite, and the sphalerite as christophite. The Frantz magnetic product contains sphalerite as marmatite, while the Frantz nonmagnetic product contains ordinary sphalerite. The results indicate that the magnetic susceptibility of sphalerite increases with increasing isomorphous iron content and that a satisfactory separation into christophite, marmaite, and ordinary sphalerite may be accomplished by magnetic fractionation. INTRODUCTION SPHALERITE, the chief ore of zinc, is almost never pure zinc sulphide. Iron is almost always present isomorphously replacing an ?equivalent amount of zinc. What may be referred to as 'ordinary' sphalerite contains up to 10 per cent iron. More highly ferriferous varieties, with 10 to 26 per cent or more iron, have been named marmatite .and christophite.

Jan 1, 1951

On 23rd October, 1969, 54 members of the Institute set out at an early hour from Rand Airport in two chartered Dakota aircraft for a visit to the Hendrik Verwoerd Dam site. The weather was at the start rather unpromising but after passing Bloemfontein the overcast cleared and it turned into a glorious day for a most memorable visit. The Institute is indebted to U.C-Dumez-Borie Dams Limited, the main civil engineering contractors, and Mr J. D. McNamara their executive manager, for the very excellent arrangements made for this excursion. From the time the aircraft landed till a slightly belated departure the organisation of the extensive tours arranged for the parties was quite outstanding and a matter for congratulation to all concerned. At each of the many places visited there was a senior official to give an authoritative and comprehensive description of the work under his control. In addition the guides on the buses, loaned by the Department of Water Affairs, kept up an interesting running commentary throughout the day. A further much appreciated facet was the introduction of many of the experts on the site and a brief talk by each after an excellent lunch served at the recreation club. Each visitor also received a brochure with a progress report and a detailed site plan, with various sections highlighted in colour, and obviously prepared at the cost of much time and effort. The visit included tours of the large dolerite quarry, where some 150 000 tons of rock are removed each month, the 42 in. gyratory primary crusher, the secondary crushing and screening plant, the rod mill plant for sand production, and the automated blending and concrete batching plant. The transport of mixed concrete by 'silobuses' to the 6 cu. yd buckets of four Blondin cableways, two of which are radially movable and two with buffing towers, and the placing of the concrete in the huge blocks of the wall was watched from a vantage point. The most interesting part of the visit was without a doubt the inspection of the wall itself and the explanations of the many intricasies of its design and care in construction, covering aspects such as positioning of galleys, interlocking of blocks, reinforcement, refrigeration, actual concrete placing, subsequent grouting, etc. Other points of interest were the very complicated design of the wall itself, the river diversion plans, with three stages of coffer dams, the spillways, and the very well cut penstock tunnels.

By M. Kanda, W. D. Bensema, J. W. Adams

Two different techniques were used to make measurements of the absolute value of electromagnetic noise in and above an operating coal mine, McElroy Mine, located near Moundsville, Nest Virginia. The electromagnetic environment created by 300 volt dc and 480 volt ac machinery was measured. In one technique noise was measured over the entire electromagnetic spectrum of interest for brief time periods. The noise was recorded using broadband analog magnetic tape. The noise data was later transformed to give spectral plots. In the other technique, noise amplitudes were recorded at several discrete frequencies for a sufficient length of time to provide amplitude probability distributions. The specific, measured results are given in a number of spectral plots and amplitude probability distribution plots.

Jan 6, 1974

By A. L. Engel

In recent investigations of chloride Volatilization of gold at the Reno Station, it was found that the addition of small amounts of copper and NaCl to the charge brought about improved volatilization of the gold. The investigations described in this report were concerned with the recovery, in an aqueous medium, of fumes from chloride volatilization of gold. It was attempted to discover a suitable aqueous medium that would permit absorption, solution, or precipitation of all the volatilized gold immediately upon contact with the medium. A simple laboratory apparatus was employed to produce fumes by volatilization. To this furnace was attached an absorption train consisting of a series of chambers containing the aqueous medium, through which the fumes were drawn by suction. A satisfactory synthetic ore that contained metallic, gold in a quartz-matrix was made and utilized, enough. gold being present in a' small amount of material to permit an accurate, metallurgical balance of the volatized values' to be obtained in all the experiments.

Jan 1, 1949

By Stephen D. Cramer

The objective of the present studies was to develop thick adherent and coherent coatings of platinum and palladium on refractory metals and other substrates of industrial and engineering importance. Existing platinum and palladium electrolytes were modified to make them suitable for the electrodeposition of thick deposits. The optimum operating conditions for these electrolytes were established. Pretreatment procedures for columbium, copper, graphite, molybdenum, nickel, stainless steel, tantalum, titanium, tungsten, vanadium, and zirconium substrates were studied. New pretreatment procedures for columbium, molybdenum, stainless steel, tantalum, tungsten, and nickel were developed. The internal stress and hardness of selected electrodeposits were measured. The effects of heat treatment upon the properties of electrodeposits were studied.

Jan 1, 1967

By Alistair James, Mo Shahsavari, Leon Botham

Recent catastrophic failures of heap leach facilities have revealed fundamental weaknesses in prevailing design paradigms, modeling toolkits, and oversight practices that continue to treat heaps as static, free-draining earthworks despite compelling evidence to the contrary. The core proposition advanced in this paper is that heap materials are intrinsically dynamic: their structure, permeability, and shear strength evolve under the sustained influence of irrigation, climate, and geochemical reactions, and these timedependent changes can precipitate abrupt transitions from granular stability to flow-like failure. Drawing on investigations of recent failures at Çöpler Mine in Turkey and Eagle Gold Mine in the Yukon, alongside earlier incidents in Peru, Arizona, Nevada, and Chile, the analysis identifies a recurrent sequence driving catastrophic behavior: progressive weathering elevates fines and suppresses permeability; drainage systems designed for initial conditions become overwhelmed; pore pressures rise heterogeneously within the heap; and static liquefaction initiates rapid mass movement with long runout. Current guidance, including ICOLD and ANCOLD frameworks and ASTM testing standards, provides a necessary foundation but is tailored to tailings and conventional soil mechanics. These documents offer insufficient direction for characterizing timedependent material degradation, quantifying rheology of weathered ore, and modeling post-failure mobility. To address this deficit, the paper proposes an integrated framework combining enhanced characterization, multi-physics numerical modeling that couples hydro-geochemical processes with large-deformation mechanics, and comprehensive monitoring with Trigger Action Response Plans. The conclusion argues for a heap-specific standard that embeds these elements from concept to closure, aiming to materially improve safety performance and reduce the likelihood and consequences of future failures.

Feb 22, 2026

By William P. Blake

(Canal Zone Meeting, November, 1910.) A DEPOSIT of manganese-ore near Tucson, Ariz., merits notice by reason of the peculiar form in which it occurs, and as a striking. example of ore-deposition by vadose upward capillary flow of metal-bearing solutions with concentration at the surface of the country-rock. This deposit occurs at the northern end of the Coyote mountains, about 40 miles west of Tucson, upon the outcropping beds of porphyritic rock, which appear to be partly-metamorphosed strata of volcanic tufa, probably of late Secondary or of Tertiary age. The strata dip northward at a low angle, and present a series of basset-edges in parallel lines of outcrop, east and west, facing the south and extending over many acres. Successive groups of these outcrops, from 5 to 20 ft. in breadth, are coated with oxides of manganese in lustrous black films and crusts, shining in the sunlight like polished ebony, and covering the whole surface of the rock above the soil. Seen at a little distance, these croppings look like solid ledges of massive and pure ore; but closer inspection and a few blows of the hammer reveal their true nature as a superficial coating allied in origin to the blackened shining surface of rocks exposed in desert-regions, familiarly known as " desert paint" or "desert varnish,"' similar to the phenomena described by me in a former paper, but much thicker and heavier. * By reason of the death of the distinguished author, this communication, probably his last communication to technical literature, is published without revision of the proofs by him. A term first given y G. K. Gilbert. See Rocks, Rock-Weathering, and Soil; by George P. Merrill, p. 256 (New York, 1897). Superficial Blackening and Discoloration of Rocks, Especially in Desert Regions, Trans., xxxv., 371 (1905).

Sep 1, 1910

By Lauri E. K. Holappa

Ferrochrome, as the central constituent in stainless steels is one of the most rapidly growing primary metallic products. In this contribution results of a comprehensive study on the reduction process of chromite ore to FeCr are presented including thermodynamic examination, experimental work on kinetics and mechanisms in solid state, and smelting reduction conditions as well as kinetic modelling of solid state reduction.

Jan 1, 1999

By Ayumi Yoshioka

Os componentes automotivos em geral devem atender a especificações rigorosas de propriedades mecânicas, requisitos de limpeza inclusionária, entre outros. Enxofre e alumínio são dois elementos adicionados ao banho líquido, que têm papel importante na obtenção destas propriedades, mas que dificultam o processo de produção por lingotamento contínuo por favorecer a formação de partículas sólidas de alto ponto de fusão, que podem prejudicar a limpeza inclusionária e provocar a obstrução das válvulas de lingotamento. O objetivo do presente trabalho é analisar e classificar as inclusões de corridas do aço DIN 38MnSiVS6 em escala industrial e avaliar estes resultados em conjunto com os dados de processo de aciaria e com os resultados de simulação termodinâmica utilizando o software FactSage 6.4. Foi observado que as corridas apresentaram tanto sulfetos de cálcio quanto espinélios, mas as primeiras, associadas a uma fração líquida menor na escória, tiveram uma correlação mais perceptível com a má lingotabilidade.

Aug 17, 2017

By Gilbert M. Farrior

The electrical resistivity the coefficient of electrical resistivity the Hall coefficient, and the absolute thermoelectric power were determined in this Bureau of Mines investigation for nine compositions of the TiB2-CrB2 sub-system. The numerical values of the electrical resistivity and the thermo-electric power were greater for the intermediate compositions than for the end members. The absolute values of the Hall coefficients and the coefficients of electrical resistivity were less for the intermediate compositions than for the end members. The electrical resistivities and Hall coefficients were about the order of magnitude of most metals--from 34 to 202 microhm-cm and from about 0 to -23.3 X 10-4 cuP/coulomb. The thermoelectric power was somewhat greater than that of most metals--up to 15.6 microvolts per 0 C.

Jan 1, 1965

By Edward G. Cunney

Track in underground bituminous coal mines was investigated, and technology was taken from other industries in order to obtain information on conditions that impair the safety and efficiency of the track and to develop guidelines and useful information on the construction, inspection and maintenance of mine track. Volume 1 contains information on the investigations, observed track conditions, useful technology from railroads and other industries, derivations of track condition descriptors and recommended limits, conclusions, and recommendations. Volume 2, Guidelines, contains recommended standards and practices for mine track. It includes the relation of track conditions to safe speeds; descriptions and limits for measurable track features such as gage; descriptions of conditions for track components that are normally not measurable, such as subbase soils; construction requirements and techniques, inspection requirements and methods; and methods for managing and performing track maintenance work. As a research product, it does not repeat the summary or derivations. Volume 3, Inspection Handbook, summarizes recommended standards and procedures from Volume 2 and provides related information for' ready reference by inspectors in the mines. As a research product to be used in mines, it does not repeat the summary, derivations or references.

Jan 1, 1977

By Brian Wilson, Megan Atkinson, Richard Diggle, Nathan Sweeney

"Ruskin Dam, located near Mission, British Columbia, was constructed in 1929 and 1930 and comprises of a concrete gravity dam structure founded on bedrock. At the right abutment, which consists mostly of dense to very dense sands and silt, the dam abuts against overburden soils, and connects to a cutoff wall system consisting of sloping concrete slabs. Significant seepage and piping issues were encountered during first filling of the reservoir in 1930. In 2012, BC Hydro, the owner of the dam, awarded a contract for the construction of seepage control measures at the right abutment, including construction of a plastic concrete cut-off wall extending upstream of the dam, a plastic concrete seepage training wall extending downstream of the dam, tie-in of the new cutoff wall to the dam, consisting of jet grouting of the soils adjacent to the dam to allow for the construction of the special cutoff connecting the cutoff wall to the dam, and construction of additional jet-grouting ground improvement downstream of the dam.Integral to the upgrade was the requirement for the special tie-in cutoff wall, consisting of a highly flexible, impermeable membrane to connect the concrete dam to the new, 1 m thick plastic concrete cutoff wall. The tie-in extends vertically into bedrock through the dam and jet grout columns constructed adjacent and beneath the overhanging portion of the dam at the right abutment. The membrane is required to survive the anticipated earthquake induced deformation between the dam and the abutment soils.This paper describes the processes used to develop a material suitable to meet the specified flexibility and permeability criteria, as well as the innovative construction techniques utilized to construct the slot and place the bituminous material within it. The final dimensions of the slot were in the order of 7 m long by 25 m deep by 0.17 m wide. The bituminous material was placed under a head of water which was required to maintain stability of the slot, and was placed at temperatures in excess of 120 degrees Celsius."

Jan 1, 2017

By J Caron, M Athayde, F Lavoie, R Joyce

Decarbonisation has become a major challenge for the global steelmaking industry, turning towards new technologies aimed at carbon footprint reduction, which on its own accounts for approximately 9 per cent global emissions. The iron and steel industry represents a ‘hard to abate’ sector, where much of efforts are currently being deployed into initiatives aiming to decarbonise the ironmaking through the use of green hydrogen, carbon capture utilisation and storage and state-of-the-art operation of current technologies, while little efforts being deployed to find carbon-efficient solution to iron ore burden preparation, where high-grade iron concentrate will increase in importance to ironmaking regardless of the chosen reduction route. Quebec Iron Ore (QIO), a subsidiary of Champion Iron Limited (Champion), produces high-grade hematite concentrate with one of the lowest carbon global footprints. Still, QIO is partnering with its clients to the development of burden solutions to minimise CO2 emission, in the seek for a decarbonised steel. In a strong technological partnership, Binding Solutions Limited (BSL) has developed a novel, coldbinding technology to provide a cleaner, more cost-effective alternative to induration. The technology allows miners and steel producers to reduce Capex significantly and reduce energy consumption and CO2 emissions by 90 per cent. QIO and BSL have partnered to adapt the disruptive cold binding technology developed by BSL to QIO’s concentrate to produce a high-quality low emissions iron ore agglomerate. This paper describes the efforts taken to further develop BSL’s cold binding technology and its application to QIO’s high-grade iron ore concentrate to produce a hematite cold bonded briquette (hCBB) showing comparable performances with high quality seaborne fired pellets.

Nov 8, 2021

By E. W. Parsons

Permanent support of the back is an important economic factor in maintaining a tunnel or other underground opening in condition to render the service for which it was driven. Timber has been most commonly used for support in tunneling and drifting because of its strength and ease of installation. Even when treated for decay, however, timber is subject to deterioration and, over a long period of time, should not be considered a permanent support. Concrete support or lining is permanent and has been used in tunnels of every size for many years but has been almost exclusively cast in place, a difficult, costly process. This report deals with the design and installation of precast concrete supports to combine the best features of both methods.

Jan 1, 1958

By D. C. Rance

"The Quintette Coal Limited property is located in the north east coal area of British Columbia. A basic agreement with the Japanese steel industry was ex ecuted on January 27, 1981 for the sale of 69.5 million tonnes of Quintette metallurgical coal over a 14.5-year period. This contract period can be extended by Jive years by mutual agree ment. Sale agreements have also been signed for the sale of 19.4 million tonnes of oxidized coal over a 15-year period. Work started on site development in the late summer of 1981, and at present, two of the four eventual pits-the McConkey and Frame-are under development. The pits are currently in a pres/ripping phase. These pits are notable for the stripping volumes that have to be removed from relatively small pit areas. in order to provide for the required detailed rapid short-range planning of these pits, engineering will be computerized, as will the truck dispatch system. The mining area lies 21.1 km from the plant site by road and the transport of raw coal LO the plant is by means of a highspeed conveyor system which has a total length of 13.4 km with a vertical drop of 740 m. The surface plant facility was designed on a modularized basis to facilitate maintenance, and is designed to enable the use ofgravity flow ofraw coal and heavy media in the plant to minimize the use of pumps. The construction of the plant and mine site facilities is on-going, and the first coal production is scheduled for early December 1983. Introduction Quintette Coal Limited is a Canadian company incorporated in the province of British Columbia in 1971. Denison Mines Limited is the manager of Quintette's activities. Equity in Quintette Coal Limited is held by several shareholders, with interests as follows: Denison Mines 'Limited, 500Jo; Charbonnages de France International S.A., 120Jo; and Japanese interest, 38%. The project will develop almost 120 million tonnes of coal for marketing during its first 20 years of production. All of the planned production tonnage has been committed to Japanese markets. Most of the coal will be metallurgical grade, and the remainder will be a high-quality thermal coal. The Mcconkey and Frame pits, which will initially provide the mine's production, will commence production in early December 1983 and will, in 1985, reach the full annual production of 5 million tonnes clean metallurgical coal and 1,380,000 tonnes of clean thermal coal."

Jan 1, 1985

By G. F. Cross

INTRODUCTION THE electrical system associated with the mining development of the Hudson Bay Mining and Smelting Company, Limited, at Flin Flon, Manitoba, may be conveniently divided into three main parts, namely, the Island Falls power plant, the transmission line, and the distribution systems at the mine and metallurgical plants. For a description of the Island Falls power plant and the transmission line, the reader is referred to the paper, to be presented at this meeting, by R. W. Davis and M.F. Huffaker (1). The transmission line and sectionalizing combinations are shown diagrammatically in Figure 1. The present paper deals with the distribution systems at the Flin Flon mine and metallurgical plants. THE FLIN FLON DISTRIBUTION SYSTEM In the high-tension sub-station at Flin Flon, each incoming 110 kv. line is provided with manually operated, gang-type disconnecting switches. Each line is connected to Canadian General Electric type F.H.K. 39-60B-F.2 T.P.S.T. 110 kv. 400 amp. oil circuit breakers, each provided with M.K.4 centrifugal motor-operated closing mechanism. Gang-type disconnecting switches are installed on each side of incoming line breakers, and a complete ring bus system is formed through station tie breaker, which is' further provided with gang-type disconnecting switches on either side. The?bus tie breaker is of Canadian Westinghouse design, type G.22B, 110 kv., 400-amp., solenoid-operated. All three breakers are provided with bushing-type current transformers, and the two line breakers are further equipped with bushing-type potential devices. Oxide film lightning arresters (121 kv.) are installed on each incoming line and are located outside the station. Each line is further provided with interlocked gang-operated ground disconnecting switches. All disconnecting switches are mechanically connected to auxiliary switches, which provide pilot service to indicating lamps in the remote-control room, located in a separate building.

Jan 1, 1935

By Baafi EY, Chatterjee PK

The quality of mine planning decisions ultimately depends on reliable estimates of the characteristics of the orebody. The quant- ifiable factors such as grades or thickness can be estimated from field data gathered from outcrops or exploratory drillholes. Since outcrop data is necessarily limited to the periphery of a deposit, extensive drilling generally is required. This paper outlines a method for selecting the number and location of additional exploratory boreholes using an iterative procedure based on a mathematical optimization concept called fixed point theory. The method is illustrated through its application to an exploratory drilling program for a coal mine where optimized locations gave a lower estimate of regional and block variances than a manual Choice.

Jan 1, 1986

By John C. Machisak

Injury data and experience, with related employment statistics, at coal mines in the United States for 1960 are presented in this publication under the following general sections: A General injury experience: Tables 1 to 6: Current data on number of injuries, decree of injury, frequency and severity rates, average severity, and related employment and production data by work location. B Selected injury experience: Tables 7 to 38: Current data on principal agencies of injuries, distribution of injuries by part of body injured, days of disability, extent of hand and machine loading, experience by employment and production groups, and various other operating factors and physical conditions related to the occurrence of injuries at the Nation?s coal mines.

Jan 1, 1962