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By John P. Shubilla1, Nicholas Kyriazi

A joint effort by the Pittsburgh Research Center (PRC) and the Mine Safety and Health Administration (MSHA)3was undertaken to determine how well self-contained self-rescuers (SCSR's), deployed in accordance with Federal regulations (30 CFR 75.1714), held up in the underground environment with regard to both physical damage and aging. This report presents findings regarding laboratory-tested SCSR's in the fifth phase of testing from mid-1993to early 1996. The SCSR's were tested on human subjects and on a breathing and metabolic simulator (BMS) at PRC. These results indicate that most of the apparatus, if they pass their inspection criteria, perform satisfactorily.

Jan 4, 1996

By Liu Q, Siefken T. C, Misra V. N

The bubble size was measured in a laboratory flotation column. The effect of variables such as air flowrate, frother dosage and type, pulp density, particle size and water column height on the bubble size was investigated. The results show that an increase in either air flowrate or pulp density cause the bubble size to increase, while increases in water column height, frother dosage, surface tension or solid particle size cause the bubble size to reduce. Among the frother types tested, MIBC was found to be the most effective in reducing the bubble size.

Jan 1, 1992

By Kevin Stuffle, James E. Sharp, Sean Premeau

Two process enhancements for the biological oxidative pretreatment of sulfidic gold ore for subsequent treatment with cyanide are discussed. These are the use of a high areal density ring and pin packing (BioBalls™) as substrate, and the use of a novel biological ferric generator. The BioBall™ packing when coated with concentrates for heap leach processing offers higher areal densities, while leaving more open volume for fluid flow than more commonly used substrates such as aggregate. An oxidation rate study was performed on crushed auriferous arsenopyrite whole ore to demonstrate the benefits of using the packing. The auriferous arsenopyrite grading 2.9% Fe and .212 OPT gold was 50 percent oxidized in 24 days. The biological ferric generator is a passive air-side trickle bed reactor that efficiently converts ferrous to ferric in a process stream. Conversion rates of .8g/L h ferrous to ferric are routinely obtained. Although the biologically generated ferric solutions have not yet been tested on gold ores or concentrates, prior work has demonstrated that the high ferric solutions which will result in rapid oxidation of sulfidic gold ores or concentrates.

Jan 1, 1997

By M. A. Mahtab, A. S. Burgess, R. G. Charlwood, P. O. Sandstrom, J. L. Ratigan

"Addressing a current operating and environmental concern, this paper first presents an overview of the design program for an underground radioactive waste storage vault. It then reviews the construction, operational and thermal-mechanical aspects of such a project. The relevant experience from major underground construction projects is reviewed and the paper concludes with brief comments on the design-oriented research and development requirements . 1. IntroductionA program to develop techniques for the ultimate disposal of high-level radioactive waste into geologic formations was announced by AECL in 1975 (Tamrnernagi, 1976), and is discussed more fully in a later document (Boulton, 1978). Our paper summarizes the studies caried out, as part of the AECL waste management program, by the authors and associates on the development of design concepts for a vault situated in crystalline rocks of the type present in the Canadian Shield.The design studies have been carried out in three phases, the elements of which are described in Section 2.1 (also see Fig. 1). The general vault designs are presented in Section 2.2. These provide for emplacement of either immobilized fuel or solidified reprocessing wastes in a room-and-pillar facility at a depth of 1,000 m.Section 3 reviews the principal design considerations from the construction, operation and thermal-mechanical response aspects. The concepts have been studied in both temporal and spatial domains, and the requirements and responses assessed in each as appropriate.Section 4 briefly reviews the availability of relevant experience from previous major underground construction projects. Finally, in Section 5, brief comments are given regarding design-oriented research and development requirements."

Jan 1, 1980

By Yi Luo

Regulating the face advance rate in longwall mining operation can be an effective means to reduce the disturbance potential to surface structures associated with a longwall subsidence process. However, there are two seemingly different views about the relation between the face advance rate and the disturbance potential associated with dynamic subsidence process. The US mining industry prefers a faster but a constant face advance rate while the German counter- part is forced to select a slower rate due to its mining conditions, especially while undermining sensitive objects. In order to gain a better understanding about these two different approaches, the experiences in longwall mining subsidence in both Germany and US are presented in this paper with the fundamental differences in geological conditions and mining practices.

Jan 1, 2001

By W. A. Jones

"The Hollinger gold mine is in the Porcupine area, Cochrane district, in northern Ontario. The adjacent town of Timmins, which has a population of 25,856, lies 490 miles by railway north of the city of Toronto.The property was staked in the late summer of 1909. The original four claims were staked by Benjamin Hollinger, after whom the mine was named. Development commenced in the autumn of 1909 and mill construction in the winter of 1910. A catastrophic forest fire swept the district in 19ll, destroying the surface plant, so that the original 300-ton mill was not completed until June 1912. From that date up to December 31, 1945, 44,280,750 tons of ore have yielded 13,636,796 oz. gold and 2,613,354 oz. silver. The total value of the production has been $363,638,315.0REBODIES AND MINERALIZATIONThe orebodies consist of quartz veins, stringer lodes, and scockworks, with associated pyritized wall-rocks. The width of individual orebodies, as exposed by mining operations, ranges from 1 to 70 feet and averaged approximately 10 feet in 1942. The vein system forms a complex pattern in a favourable zone, which in places is 6,000 feet long and 4,000 feet wide. The deepest level being developed is 5,150 feet below the surface. Few veins are persistent for long distances, although some are continuous for more than 1,000 feet longitudinally and vertically.The host rocks consist of a closely folded series of Precambrian lava flows of Keewatin age. These are schistose and hydrothermally altered, but are believed to have originally been of intermediate to basic composition. The schistosity strikes N.70°E. and dips to the south at 75° to 80°. The structure of the formations is complex, but in the principal ore-bearing zone the general dip of the flows is to the south at a slightly flatter attitude than the schistosity."

Jan 1, 1954

By Wils L. Cooley

The report covers tests and criteria for the establishment of safe grounding systems for coal mines. The work deals primarily with under-ground coal mines, but much is applicable to surface mines as well. Included is an extensive guide to grounding and bonding procedures for mine surface substations. Xit-Rods are evaluated and shown to deviate from manufacturer's claims. An analysis shows that very long cables are difficult to monitor using audio frequency ground-check techniques. A method is developed to detect failing cable splices without removing the cable from service. Simulation and measurement are compared for a technique to detect bad rail bonds, and an assessment is made of grounding techniques for dc face equipment.

Jan 1, 1979

By R. D. Brown

In the spring of 1977, Revenue Canada announced its intention to proceed in 1978 with a plan to impute a taxable benefit on interest-free and low-interest loans provided to employees. Such loan arrangements are often an important aspect of the compensation packages provided by many companies to their employees. Since the original announcement, there have been many submissions to Revenue Canada opposing this change, and the Finance Minister has now brought down a compromise solution with the introduction of a proposed amendment to the Income Tax Act. The amendment, which would not take effect until the 1979 taxation year, would require an employee, a shareholder or a related person to include a benefit in income measured as the difference between the interest on any such loan computed at bank prime rate and any interest actually paid. Only the amount of such a benefit in excess of $500 in a particular year would be required to be included in income. Of particular interest is the exclusion from these benefit rules of loans up to $50,000 in respect of the purchase of a house on the relocation of an employee and loans provided for the purchase of shares of an employer corporation.

Jan 1, 1978

Investigation on Multicomponent Semi-Autogenous Grinding

Sep 13, 2010

By R. E. Brown

The objective of this Bureau of Mines study was a laboratory-scale evaluation of the sodium sulfate refining process for removing copper from molten ferrous scrap. Maximum copper removal is achieved in carbon-saturated melts at 1,300° C. Low carbon concentrations and higher temperatures result in a less efficient copper removal and an increased sulfur concentration in the iron. Sodium sulfate refining significantly lowers the concentration of aluminum, manganese, and silicon; however, the copper removal efficiency is adversely affected by the presence of manganese and silicon. Compared with other reagents tested, sodium sulfide-forming slags were found to be the most suitable for both copper removal and sulfur control. The sulfur content of the refined iron was higher in tests conducted in acid-type refractory crucibles. Earlier studies showed that tin, a significant metallurgical impurity, is not removed by the sulfate process. During the present investigation, results showed that chlorination, using organic solid sources of chlorine, reduced the tin concentration to acceptable levels in molten iron.

Jan 1, 1975

By C. P. Sandberg

Having been occupied in inspecting and testing iron and steel these twenty years in England, and previous to that having served on the Board of Iron Masters in Sweden, I have naturally been very much interested in the subject of the use of steel for structures. I regret that I can offer but comparatively small experience on that had, having had principally to do with steel for railway plant and rails, but granting these to be a kind of "structure," and also that steel for rails has similar duties to perform in many respects, and is generally manufactured in the same way and at the same works as steel for stuctures, properly speaking, I may be entitled to offer an opinion on the use of steel in construction. In a paper recently presented to the Institution of Civil Engineers in London, Mr. Ewing Matheson has recommended that the Board of Trade rules should be amended so as to allow of a maximum straining of 8 tolls per square inch instead of 6 1/2 tons. But it is equally necessary to fix the amount of ductility or elongation of the metal for such a strain as 8 tons. Strength and ductility should always be spoken of together. Mr. Matheson says that steel can be manipulated in the factory in the same way and with the same tools as are used for iron. This can only be granted for mild steel; for hard steel would be spoilt by the rough mechanical treatment which iron can stand, such as punch ing, for instance; and the remedy for regaining the strength lost by punching hard steel, viz., annealing, cannot always be applied. Noth ing proves this fact better than the punching of steel rails of consid erable hardness, which caused fractures at an early period of steelunaking, and which resulted in the stipulation for drilling instead of punching the bolt-holes, which had been formerly applied to iron rails without any damage. In fact commissions to establish standard tests are now working on the Continent, principally in Germany, where

Jan 1, 1882

By Gaulton R

The Commission maintains a data base first computerised in 1957 and containing information from over 18 000 boreholes located mainly in the Latrobe Valley area. Some of the borehole derived information dates from the turn of the century, although most of it has been collected as a result of Commission investigations conducted over the past 40 years. The Resource Data Base contains not only information gained directly from the drilling itself but includes the results of chemical and physical testing on many hundreds of thousands of samples retrieved from boreholes. Replacement value of the Resource Data Base has been estimated to be around $200 million, and it's integrity and accessibility is clearly of paramount importance, not only to existing mining and power generating functions but to the future evaluation and use of the vast brown coal Resource.

Jan 1, 1992

By Daniel N. Tallman

To provide technology for achieving more efficient water filtration systems for the mineral industry, the Bureau of Mines performed demon-stration filtration tests at three iron ore mines and one steel mill. A comparison of equivalently sized magnesium oxide (MgO) and sand filters showed that MgO had a higher capacity and could operate at higher fil-tration rates than sand. In demonstration tests when alum (AlK(S04)2) was the coagulant, suspended solids breakthrough occurred even though the pressure across the filter (head loss) was 7 psig or less. Under these circumstances, the MgO demonstrated 20 to 100 pct greater filtra-tion capacity, defined in terms of the volume of water filtered before breakthrough. When an organic floccu1ant was used at one location, head loss was the run-limiting factor; the filters essentially plugged with-out any solids breakthrough.

Jan 1, 1985

By Réjean Lévesque

SIDBEC-NORMINES a été incorporée en 1976. Depuis la fin de 1977, ses activités comprennent outre la concentration au lac Jeannine, près de Gagnon, du minerai de fer extrait du gisement du lac Fire, I'exploitation d'un atelier d 'enrichissement secondaire et une usine de bouletage à Port Cartier. L 'objectif principal de SIDBEC-NORMINES est de produire six millions de tonnes de boulettes d'oxyde de fer par année, dont trois millions auront une faible teneur en silice afin de répondre aux exigences de la réduction directe. Les installations de SIDBEC-NORMINES sont adjacentes aux installations portuaires de la Compagnie Minière Québec Cartier, à l'est de la ville de Port-Cartier. L 'ensemble est conçu pour produire les deux types de boulettes avec deux circuits d'agglomération installes en parallèle. La production de concentré enrichi (68% Fe et plus) est obtenue dans une usine d'enrichissement utilisant le precédé de séparation magnétique hum ide ahaute intensite (separateurs Jones). À l'usine de bouletage proprement dite, on effectue Ie broyage du concentré et sa mise en boulettes sur disques; l'in duration des deux types de boulettes est obtenue sur deux chaînes d'agglomération Dravo dont chacune a une capacité annuelle nominale de trois millions de tonnes.

Jan 1, 1979

By Henry B. Estabrooks

As was the case with many other mining companies, the management of Tennessee Copper Company' viewed with some interest reports in various trade and technical journals of the successful use of ammonium nitrate-fuel oil mixtures as an explosive in coal stripping., construction, open pit mining and finally in underground salt mines. The apparently simple transition from the "interested" stage to a point where in excess of 80% of the ex¬plosives used is ammonium nitrate may be of interest. The Tennessee Copper Company operates five mines in the "Copper Basin" of Polk County which lies on the extreme southeast corner of Tennessee. The ore is a massive sulfide principally pyrrhotite and pyrite with some tough lime silicates as gangue while the walls are greywacke interbedded with schist. Average total production is 28,000 tons per 5-day week and an average of 422 feet of development per week. Development work consists of 8'x 8?, 6?x 7?, 5'x 7? and 4'x 6? drifts driven with drifter drills using 1-5/8" carbide detachable bits and 5'x 5' raises driven with stopers using 1-5/8" bits.

Jan 1, 1962

By A E. Annels, M NoppT

Ore Reserves are key mining company assets and their reliable estimation is crucial for both feasibility studies and the day to day operation of a mine. The reserve is based on the Mineral Resource after the application of certain technical and economic parameters. Engineering aspects of reserve estimation can be accurately determined to ¦10 per cent, however the majority of project risk will revolve around the resource. A final Ore Reserve generally contains a set of figures quoted without reference to its potential errors. Rarely are overall confidence limits quoted and, if they are, they often do not take into account many of the factors that cause uncertainty in the grade and tonnage estimates. There is thus an unquantifiable risk, which the operator should be aware of. This paper presents a review of the possible sources of error that might occur during the various phases of an exploration and estimation programme which are carried through into the Ore Reserve and hence mine design.

Jan 1, 2002

By Carlos Eduardo Pinedo

A nitretação dos aços inoxidáveis tem sido objeto de diversos estudos nas últimas décadas. O objetivo primordial é promover o endurecimento superficial e com isso elevar a resistência ao desgaste, sem comprometer a resistência à corrosão. Em vista disto, a nitretação sob plasma a baixa temperatura, abaixo de 430oC, tem se mostrado um processo eficiente para inibir a precipitação de nitretos de cromo e promover o endurecimento superficial pela formação de fases expandidas pela supersaturação de nitrogênio. Este trabalho mostra a formação de ferrita expandida em um aço inoxidável ferrítico. Para isso foi utilizada o processo de nitretação sob Plasma-DC na temperatura de 400oC por 20 horas em mistura gasosa contendo 75%N2 e 25%H2. Os resultados de Difração de Raios-X mostraram que a nitretação em baixa temperatura é capaz de formar uma camada nitretada de ferrita expandida. Em Microscopia óptica observa-se uma camada homogênea com profundidade média de 32 microns de profundidade e dureza média de 1296 HV promovendo um endurecimento superficial do aço inoxidável ferrítico em mais de 5 vezes sem que ocorra a precipitação de nitretos de cromo e, com isso, preservado a resistência à corrosão.

Oct 30, 2017

A Mark IV surface force apparatus (SF A) was used to conduct direct force measurements in dodecylamine hydrogenchloride collector solution between mica surfaces at varying pHs. It has been found that the long-range hydrophobic forces reach a maximum at pH 9.5, which also corresponds to the maxima attained by the contact angle and flotation recovery of quartz. The charge densities are comparable on both mica and quartz surfaces (0.40-0.48 run2), making it possible to draw conclusions on the flotation of quartz from the direct force measurements conducted on mica. Therefore, it may be suggested that the maximum flotation recovery of quartz m the range of pH 8.0-10.3 may be attributed to the appearance of long-range hydrophobic force, which in turn can be related to the formation of a close-packed monolayer (or hemimicelle) in the presence of neutral amines formed as a result of hydrolysis.

Jan 1, 1996

By Hisahiro Kinoshita, Derek Temple, Yoshio Higashitsuji

The zinc-lead blast furnace process has been installed by two smelters in Japan. In 1966 a unit was commissioned at Harima in Hyogo prefecture by Sumitomo Metal Mining Co. Ltd. and in 1969 a consortium of other Japanese zinc and lead smelters completed their unit at Hachinohe in Aomori prefecture, managed by Mitsui Mining & Smelting Go. Ltd. , the major shareholders. The special characteristics of these two plants are described with particular emphasis on their location and operation. Reference is also made to the processing of a wide range of raw materials, including residues from other processes. Both plants pay scrupulous attention to plant and environmental hygiene to meet the high standards set by the local prefectural governments; the ways in which this has been achieved are discussed. General performance data on each furnace is included, showing that this pyrometallurgical process is supplying 16% of Japan's zinc and refined lead consumption. Note - All tonnes (t) are metric of 2204 lbs.

Jan 1, 1976

By F. A. Jones

Increased mechanization .of coal mines has emphasized the need for study of actual power requirements of the various machines employed in the production of coal and losses in the distribution of power to these machines. These studies are being made in order that hazards, excessive use of power, and high maintenance cost of equipment resulting from these losses may be analyzed and eliminated where possible. Research on the use of electric power in-coal mines was suggested by the Advisory Committee of the Bureau of Mines in 1937, and it was decided to begin with a study of individual machines of various types under operating conditions in modern coal mines. The transmission of power, particularly line losses and inadequate return circuits, should be a part of the investigation. This report presents some of the data of an initial study in commercial mines. ACKNOWLEDGMENTS The superintendents, engineers, and other officials of the two mines studied cooperated fully and aided in setting up and transporting the test equipment, giving such information as was requested.

Jan 1, 1942