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By D. S. Choi

This paper presents a theoretical analysis of the effect of shape and size on strength of geologic materials. The results indicate that the shape effect is caused by the development of confining pressure at the interfaces. The linearization of the obtained formula is of the same form determined by experiments. The size effect is attributed to the fact that the geologic materials contain discontinuities in the form of fractures, bedding planes, and cleats. The maximum reduction factor for the size effect is the one-sixth power of the volume of a cubic test specimen. The results of this work are particularly useful in determining the strength of coal pillars in underground mines.

Jan 1, 1989

By T. Serradj

A study has been carried out to: develop a method for routine characterisation of rock strength and drillability through the particle-size distribution of crushed or drilled rock products, defined by the Protodyakonov index; establish correlations between the Protodyakonov index, uniformity coefficient and the constant grading equations; and propose an alternative rock characterisation index to classify rock strength and drillability for the northeast region of Algeria

Dec 1, 1996

The 1981 Review: In the late 1970s there was an upsurge of interest in the prospecting and mining of this countryÆs mineral resources. That upsurge of interest was accompanied by a mounting public concern over the damage mining operations might do to the environment. Concern was also expressed about what some people perceived as inadequacies in the legislation which regulates mining and the grant of mining privileges, and inconsistencies in the relationship of that legislation to other legislation regulating land use and the use of resources.

Jan 1, 1984

By Alfred V. C. Meyer

A Blastcorder4 was calibrated on the Bureau of Mines shaking table in the frequency range of 12 to 40 c.p.s. and in the amplitude range' of 0.25 to 1.0 g. The results of this calibration study show that in the frequency range of 12 to 30 c.p.s. the average accuracy of the Blastcorder is approximately ± 0.1 g.

Jan 1, 1962

By C. Crussard, R. Tamhankar

It is the policy of The Metallurgical Society to provide, in the TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME, a prompt and accurate medium for publication of reports of significant new research in both the scientific and engineering aspects of metallurgy. Papers submitted to the Society are judged by competent reviewers accord-ing to established criteria for technical merit, accuracy, originality, and presentation. STAFF: Editor, Gerhurd Derge Carnegie Institute of Technology Schenley Park Pittsburgh 13, Pa. Editorial Assistant, M. A. Redmerski Staff Coordinator, James J. Burke THE METALLURGICAL SOCIETY: W. R. Hibbard, Jr., President; J. C. Kinnear, Jr., Past-President; John Chiprnan, Vice President; T. D. Jones, Treasurer; R. W. Shearman, Secretary. PUBLICATIONS COMMITTEE OF THE METALLURGICAL SOCIETY: A. W. Thornton, Chairman; Dennis Carney, John Chip-man, J. C. Fulton, J. H. Hollomon, H. H. Kellogg, A. E. Lee, R. Maddin, J. D. Sullivan, and D. Swan. Review and selection of manuscripts is under the supervision of the following Publications Committees: Extractive Metallurgy Division: T. B. King, Chairman; S. J. Dickenson, R. P. Hermsdorf, R. Schuhmann, Jr., and P. T. Stroup. Institute of Metals Division: Robert Maddin, Chairman, F. Lincoln Vogel, Jr., Vice-chairman, W. A. Backofen, R. W. Balluffi, J. H. Bechtold, M. B. Bever, R. S. Busk, C. G. Goetzel, Paul Gordon, C. D. Graham, .Jr., Robert F. Hehemonn, R. I. Jaffee, F. E. Jaumot, Jr., Irving R. Kramer, A. J. Lena, Harold Margolin, C. J. McHorgue, Russell A. Meussner, J. B. Newkirk, H. W. Paxton, G. E. Pellissier, I. S. Servi, Alan U. Seybolt, A. J. Shaler, and Jack Washburn. Iron and Steel Division: J. C. Fulton, Chairman; T. B. King, F. C. Langenberg, W. 0. Philbrook, and T. 0. Winkler. Published bimonthly by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc., 29 West 39th Street, New York 18, N. Y. Telephone: PEnnsylvania 6-9220. Subscription $20 per year for non-AIME members in United States and North, South, and Central America; $25, foreign; $5 for AIME members. Single copies, $4.00, single copies foreign, $5.00. The AIME is not responsible for any statement made or opinion expressed in its publications . . . Copyright 1958 by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. . . . Registered cable address, AIME New York ... Indexed in Engineering Index, Industrial Arts Index, and Chemical Abstracts... Second class postage paid at New Yark, N. Y., and Ann Arbor, Mich. Volume 212, Number 6.

Jan 1, 1959

By J. W. van der Merwe, A. Palazzo

"Owing to the corrosiveness of the untreated brackish cooling water typically used for steel mills (and other environments), it is important to treat the water and monitor corrosion in such systems. Generally, corrosion rates are monitored with corrosion probes inserted into a pipeline or vessel. This has been standard practice for many years, and is widely accepted in industry. Typically, two kinds of probes are used - electrical resistance and linear polarization resistance (LPR) probes.In this study, the effectiveness and accuracy of the LPR technique was evaluated by comparing the electrochemical measurements with the results of mass loss tests using corrosion coupons. The corrosivity of the environment, a synthetic brackish water, was varied by varying the calcium hardness and alkalinity, and to simulate actual plant conditions temperatures of 35°C and 45°C were used. In addition to the corrosion rate measurements, the iron concentration was measured, as well as the imbalance from the probe.The corrosion rates obtained by LPR were from 57% lower to 385%higher than those from the immersion tests. Most probe measurements were higher than the immersion results, and 50% of the probe results were50% or more higher than the immersion results. The best correspondence between the two methods was obtained at low calcium levels, except for one measurement that was 93% higher than the coupon results. There was no clear correlation between parameters such as temperature and total alkalinity and the difference between the results. It would therefore appear that LPR measurements can differ significantly from immersion results, and LPR results should therefore be used with caution in industrial applications."

Jan 1, 2015

By Carlos G. C

Geological mapping in various parts of Australia is revealing a number of regional associations of mineralizations with particular persistent stratigraphic horizons. Such associations have been found in the Broken Hill district of New South Wales, in the Nairne district of South Australia, in the Mount Isa district of Queensland, and in the Cloncurry district of Queensland. The question has arisen as to whether such mineralizations are of sedimentary origin, syngenetic with the enclosing formation, or whether they are of epigenetic origin, and reflect the selective hydrothermal mineralization of favourable beds on a regional scale.The purpose of this investigation is to test the use of sulphur-selenium ratios as an objective method of distinguishing between suphide deposits or sedimentary or supergene origin, and sulphide deposits of hydrothermal origin, with particular application to the districts mentioned. At the same time much data has been accumulated as to the selenium content of Australian sulphide ores. The possible use of sulphur-selenium ratios for this purpose was first demonstrated by Goldschmidt and his coworkers (1933; 1935), and later by Carstens (1941). Goldschmidt and Strock (1935) found that pyrite of sedimentary origin had a sulphur : selenium ratio of the order of 200,000 or more, whereas pyrite of hydrothermal origin had a sulphur: selenium ratio of 10,000 to 20,000. Carstensfound that sedimentary pyrite deposits in Norway contained less than 1 g. Se per ton, whereas hydrothermal pyrite deposits contained 20 to 30 g. per ton.

Jan 1, 1954

By Wilson O. A

TABLE OF CONTENTS1. Introductiona. Process Changes since 1939.b. Current Practice.2. Ore Characteristicsa. Copper Minerals.b. Gold Occurrence.3. Treatment of High Grade Acid Orea. The Ore Treatment Planti. Coarse Crushing SectionDust Controlii. The Concentrating MillDesliming SectionGranular GrindingGranular FlotationGranular Flotation ReagentsFlotation MachinesSlime FlotationConcentrate CleaningConcentrate Handlingiii. Scavanging No.1. Mill Granular Tailings at No. 2 MillRegrinding UnitScavenger Flotationb. Pyrite Productioni. Pyrite Flotationii. Pumping of Pyriteiii. Storage of Pyriteiv. Pyrite Loading

Jan 1, 1952

The following brief paper is intended, to apply to the concentration of the silver-lead ores at Broken Hill, New South Wales, generally, but more particularly to the process as applied to the ores in the Block 10 mine. The attached plans are similar inmany respects to those prepared, recently for the Block 10 company.Most of the information here given is already well known to those members who are conversant with the concentration practices of this field, but it is the writer's object to give just a few of those figures which he found difficult to obtain when first engaging in practical work. At that time no text-books were at hand from which it was possible to get sufficient details for practical working purposes.It is first supposed that the mine has been thoroughly explored and has been found to contain a lbde sufficient in size ·and quality to warrant the erection of a concentrating plant. The points then to determine are:-(1.) The quantity and cost of water available for steam-making and ore-dressing purposes.(2.) The most convenient site for the mill.

Jan 1, 1904

By J. V. Batty

Radioisotopes of selenium (se78) and tellurium (Te123) were successfully employed by the Bureau of Mines as tracers in metallurgical research directed to developing improved methods for volatilizing these elements from low-tenor raw materials. Prior research, guided and controlled by conventional analytical methods, was seriously hampered by inconsistent selenium and tellurium analyses, by the slowness of the conventional chemical methods, and by the poor accountability of these volatile elements in test products. Methods were devised and evaluated for admixing the radioactive tracer with typical raw materials and then following the deportment of the selenium and tellurium by radiometric methods with occasional chemical analysis checks. These techniques were found unusually effective in (1) quantifying the completeness and the rate of volatilization of selenium and tellurium while heating the raw materials at different rates to different temperatures and (2) accurately tracing and quantifying the distribution of minute amounts of these volatile elements in the several products made by high-temperature treatment and in the several units comprising the experimental equipment.

Jan 1, 1962

A brief review is given of the history of the Colliery to date together with the reasons for the development of an additional seam.Investigations into the quality of the coal ami its suitability for the production of metallurgical coke and determination of the economic mining limits and coal reserves are discussed. The commencement of mining operations and the inter-seamarrangements necessary for the disposal of coal won are described with the stages in the opening out of the seam itself and the reasons for the installation of a 48-in. trunk conveyor belt. Choke and manning of face equipment are considered and also the work of secondary development and pillar extraction.It is concluded that with modern face equipment and conveyor belt lines, concentrated mining followed by immediate extraction of pillars is practicable and is giving excellent results at Burwood Colliery.INTRODUCTIONBurwood Colliery, the total holding of which now comprises some 3,140 acres of land and 1,450 acres of sea leases, has mined the Borehole Seam since 1883. The early work took place from Nos. 1 and 2 shafts at Glenrock Lagoon and later on at Nos. 3 and 4 shafts at Whitebridge to which the centre of operations shifted in 1893, shaft sinking at this latter area having commenced in 1888.As all the early operations were confined to the Borehole Seam, reserves of coal on this horizon had been considerably reduced by the mid 1930's, so a cross measure drift was driven to the Victoria Tunnel Seam which is about 300 ft. above the Borehole Seam, and fully mechanized coal winning commenced from the second seam in 1938. Subsequently this cross measure drift was extended to the Borehole Seam and complete mechanization of the south-west sections of this seam achieved by 1945.Four track mounted mechanical units were put into operation in the latter area and these worked in a southerly and...

Jan 1, 1958

ABSTRACTMechanised cut and fill stoping in the Racecourse orebodies between II and 9 levels was started in 1964.Five stopes are in progress over the two level interval, extracting the full strike length (600-2,000 ft) of each orebody without transverse pillars.Each stope is served by a central 10 ft by 12 ft service intake ventilation raise and an 8 ft by 8 ft return air raise at each end of the stope. Each stope is divided into two sections for drilling. firing. mucking, and fillingto maintain steady production. All equipment is kept in the stope for one level lift stoping. Gardner-Denver 2 boom jumbos are used for uphole drilling and Wagner ST 5 Scooptrams for loading and transport to ore passes located in the footwall of the orebody. A Wagner PTIO is used for materials handling and scaling of the stope backs.Mill tailings, after one stage of cycloning are used to fill the stope, one section at a time. About 80 per cent of the water is removed by decantation while the remainder percolates through hessian-covered pipes and boxes.The ore is passed to 11 level where it is hauled by the 3 ft 6 in. gauge train to the tipple at the shaft area. The ore is crushed underground before hoisting to the surface.A performance of about 100 ton/manshift is achieved by the drilling, blasting, and mucking crews in the stopes.

Jan 1, 1968

The study of gas emitted from face coal samples at the coal face is part of an investigation of instantaneous outbursts of coal and gas. Normally, seam gas essentially comprises methane of which the origin in the metamorphism of coal is undoubted. The origin of other gases sometimes occurring in high proportion in seam gas, particularly carbon dioxide, is more controversial. A simple meter for rapidly assessing gas in coal was developed. Tests with the meter enabled comparisons of seam gas in face coal at some outbursting and nonoutbursting mines, and under various working conditions. The varying results of widespread testing suggest certain trends, including some prospect of recognising outbursting potential at the coal face.INTRODUCTIONThe aim of this work is identification of differences in gas condition between coals subject to instantaneous outbursts and coals which have not outburst, and between faces of coals which will and which will not subsequently outburst. Any comparative test should be conducted right at the coal face on coal about to be worked and the results of testing should be available after a short period. Moreover, the method and the comparison of results should require no special skill, and be well within the capacity of junior mine officials. Any consistent relation between gas condition and subsequent mining conditions - outbursting or not might be valuable in prediction of outbursts.INSTANTANEOUS OUTBURSTSInstantaneous outbursts (Hargraves, 1958) , are largely unpredictable and unaccountable ejections of coal (up to 5,000 tons) and gas (up to 5,000,000 cu.ft.) from a standing coal face. Usually the gas is essentially methane (CH4 ) but may be essentially carbon dioxide (C02 ), or an intermediatemixture...

Jan 1, 1962

By I. R. Hanby

A simple solution to the problem of whether to round the calculated number of trucks up or down to the nearest whole number is to adopt as criterion the minimum cost per unit volume/mass moved, assuming all trucks in the fleet are of the same type. When the effects on journey time of varying haul-road slope are calculated for several rolling resistances, it is shown that the optimum angle of 7.5 degrees is moderately independent of both rolling resistance and height climbed; the lower the resistance, the lower the sensitivity to ramp angle, but if haul-road gradients do not exceed 1 in 10 (5.7 degrees) for safety reasons then travelling time will never be more than 7% greater than its theoretical minimum. Further calculations result in a graph of the maximum payload values to incur the minimum cost, for different values of total effective resistance

Jan 1, 1991

By A. M. Tunstall

Aspects of blast vibrations, damage mechanisms and the influence of rock quality on damage severity are reviewed and results presented from a monitoring programme in which the rock mass rating for six tunnels was determined. The peak particle velocity induced in the tunnels during open-pit blasting was measured and the tunnels were inspected visually for fresh damage after each blast. The results suggest that the quality of rock in which an excavation is situated has an influence on the level of ground vibration to which it can be subjected without sustaining damage. This means that the use of a single limiting value of peak particle velocity, as in the blast damage criteria for residential structures, is not ideal and may result in damage to excavations in poorer-quality rock masses

Jun 19, 1905

By Thomas J. Peters

In 1979 and 1980, the U.S. Bureau of Mines and U.S. Geological Survey conducted a mineral survey of the 15,600 acre (6,310 ha) Freel Peak RARE II area (No. 5271) in the Lake Tahoe Management Unit. This study by the Bureau of Mines indicates that potential for economic mineral resources in the area is slight. The only mineralized structures in the area consists of two quartz veins. One quartz vein, at the Mountain Top Mine (fig. 1), located by Fred Denner in 1932, is estimated to contain 2,000 tons (1,800 t) of silver and copper-bearing resources. Chip samples from the vein averaged 0.61 oz silver per ton (20.91 g/t), and 1.59 percent copper. The narrow vein is not economically mineable. The other quartz vein is poorly exposed and contains traces of molybdenum. A second reported molybdenum occurrence could not be substantiated.

Jan 1, 1982

By James H. Prout

Roof warning signals were studied in 18 mines covering 5 coal seams. The results of this study confirmed that roof talk must be interpreted for each individual mine after all other conditions are present that indicate danger of roof fall. Characteristics of roof talk pulses were studied to ascertain features used in interpretation. Roof talk pulse decay time was found to be typically 0.1 to 0.5 seconds depending on the dimensions of the entires. Time between roof talk pulses was found to correlate inversely with the degree of danger under certain conditions. Roof talk and machinery noise recordings obtained during this study were used for subjective tests of ear protectors in a simulated coal mine noise environment. These tests required a detailed interpretation of roof talk and yielded results with high statistical power. Results of these tests showed that the use of personal ear protectors in high noise levels does not degrade a miner's ability to discriminate speech and roof talk. A training course was developed to encourage coal miners to pro-tect their hearing by proper use of personal hearing protectors.

Jan 1, 1973

By Louis J. Sousa

In November 1989, the U.S. Bureau of Mines sponsored a 2-day conference to stimulate thinking and discussion about changing materials technologies and implications for the Government's materials information programs. On the first day of the conference, speakers provided overviews of developments occurring in each of the major materials groups. Emerging technological developments, applications, economic and national defense significance, intermaterial competition, and potential market growth in advanced plastics, polymer composites, ceramics, metals, and electronic materials were described. In general, the speakers forecast advanced materials market growth rates in excess of overall gross national product (GNP) though high costs will tend to limit growth outside of aerospace, defense, electronics, medical equipment, and other typically high value-added businesses. On the second day, a wide range of speakers representing several facets of the materials community described how advances in materials technology are creating a need for new types of data, statistics, information, and analysis. Reflecting the speakers' broad range of organizational, professional, and personal perspectives, an array of information needs was identified. Most requirements, however, seemed to fall into one of five major categories: Federal materials research activities, material standards, market and economic information, health and safety, and public policy.

Jan 1, 1990

By E. Kamon

This report summarizes completed research pertaining to the reaction of human subjects exposed to Self-Contained Breathing Apparatus (SCBA) stressors during escape conditions (viz., resistance breathing, C02 breathing, hot air breathing, and static positive facepiece positive pressure breathing) and the development of an automated breathing and metabolic simulator (ABMS). Volume I contains summarizes of the studies performed under this contract. Volume II is an appendix which contains more detailed descriptions of these studies.

Jan 1, 1984

In the past decade, the increased engagement of business in debates around sustainable development has prompted recognition of the importance of biological diversity at the local, national and global scales. Driven by increasing populations that demand rising real incomes, a range of human induced pressures are modifying natural habitats and diminishing their ability to support life. Public policy changes have struggled to arrest the loss of habitats such as wetlands or tropical forests, and the related extinction of plant and animal species. Although conservation legislation and regulation were once the exclusive responsibility of government, new partnerships are now being forged that increase the role of the private sector and non-government organisations (NGOs) in developing and delivering conservation initiatives. Since the mid 1990s Rio Tinto has had to adapt to meet the demands of a rapidly changing conservation landscape. When Rio Tinto adopted its statement of business practice in 1998 The way we work, it explicitly recognised the need to take account of relevant environmental factors in obtaining access to lands, particularly in designated areas of high conservation value. With the revision of The way we work in April 2003, the policy on land access was strengthened through removal of the word ?designated?, thereby signalling recognition of the importance of biodiversity outside of protected areas. In addition, Rio Tinto?s revised land access policy explicitly refers to the use of land that is surplus to operational requirements for habitat protection and biodiversity conservation, subject to social considerations. In late 2003 Rio Tinto further strengthened its commitment to biodiversity with the promulgation of its biodiversity strategy and related position statement, biodiversity principles? (See Appendix 1.1) and technical guidance documents. This commitment is also embodied in a variety of initiatives at the corporate and operational levels, which are reported on annually in Rio Tinto?s Social and environment review. This guide has been prepared to support the practical implementation of Rio Tinto?s biodiversity strategy. The purpose is to provide guidance on how to effectively integrate biodiversity into Rio Tinto?s operations. It is applicable to all Rio Tinto exploration, new development projects and operations, irrespective of whether they have been operational for some years or are at the beginning or end of their operational life cycles. This guidance has been developed to support the Rio Tinto Environment Standards and the Rio Tinto Community Standard and any additional supporting documents as they are developed.

Apr 1, 2005