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By M. J. Ferrante

The Bureau of Mines investigated the applicability of the freeze-drying technique for preparing dispersion-strengthened tungsten powders suitable for conversion by powder metallurgy into materials which might have improved high-temperature strength. Extruded rods from compacts of tungsten-5 vol pct thoria had at 1,650° C a tensile strength of 30,300 psi and a 10-hour stress-rupture strength of 12,700 psi, These are slightly below those measured for swaged rods of commercial tungsten-3.7 vol pct thoria. Only those tungsten-thoria dispersions containing a stoichiometric deficiency of oxygen yielded a significant strengthening effect. A low-melting eutectic formed in extruded tungsten dispersions containing either zirconia or yttria, which caused a lowering of the tensile strengths. These tensile strengths were only slightly higher than strengths of elemental tungsten made from commercial powder having a particle size of 2.4 microns (Fisher subsieve). Sheet made from this commercial tungsten had a slightly higher tensile strength than tungsten made by freeze drying, but the freeze-dried tungsten sheet had a lower recrystallization temperature, a lower ductile-to-brittle transition temperature, and a higher purity.

Jan 1, 1971

By Joseph M. Kurtak

The Bureau of Mines is currently conducting a four year mineral assessment of the 5.7 million acre Valdez Creek Mining District in Southcentral Alaska, as part of its ongoing statewide mining district evaluation program. This report is a summary of the 1987 field work, which included the examination of mines, prospects, and mineral occurrences in the study area. Placer gold has been the most important metal produced in the area, and production totaled 161,131 oz, with the majority of the production coming from the Valdez Creek Mine. Lode gold and silver production totaled 1,581 oz and 8,617 oz, respectively and came mainly from the Golden Zone Mine. Varying amounts of other metals, including copper, lead, zinc, molybdenum, antimony, chrome, nickel, cobalt, tin, tungsten and platinum exist in the study area. Occurrences of industrial limestone and coal are also located in the area.

Jan 1, 2011

By J. A. Vallejos

Re-entry protocols are a tactical approach for controlling risk after blasts or large events in seismically active mines. Based on the results of a survey on 18 seismically active mines, mostly in Ontario, current re-entry practices are summarized. Over half of the mines in Ontario use event decay rate analysis as their primary re-entry decision making parameter. We study in detail the applicability of the Omori?s law as an equation for describing the event decay rate for more than 250 mining-induced aftershock sequences in seven different environments. Practical guidelines for the use of the Omori equation as a re-entry criterion are proposed.

May 1, 2009

By A. W. Bester

Paper written on project work carried out in partial fulfilment of B. Eng. (Mining Eng.) Cullinan Diamond Mine currently handles 3.2 million tons of run of ore per annum. This is done by means of an underground train system, which is located at 763 metre level. Four trains, one in each quarter of the pipe, collect ore from passes and transport it to centrally located tips in the north and south of the pipe. The ore is then split into coarse and fine fractions. The coarse fraction proceeds to the primary crushers in the north and south. Historically, mining has been performed in such a manner that an equal amount of ore has reported to each quarter of the pipe. However, the tonnage profile of the mine will change such that the ore will no longer be split equally. For approximately five years the majority of ore will report to the east and thereafter most of the ore will report to the western portion of the mine. This will continue for the remainder of the current infrastructure level?s operational life. Coupled with this is the fact that the mine is aiming to increase its annual production to 3.8 million tons. The result is that the current ground handling system cannot accommodate the additional tons and therefore alternative ground handling options have been investigated. The continued existence of Cullinan Diamond Mine relies on finding a system that can economically handle the additional tonnage. Three options were investigated. Firstly, a train option, which would be an upgrade of the current system, was investigated. Two truck options were also investigated, the first of which was a conventional truck option. The second truck option was more interesting and involved an unfamiliar Combi truck system. The truck options were investigated primarily due to the fact that the block height of the BA West (a new production block) can be increased by 15 meters if a truck option is decided upon. This would create a significant increase in revenue for the BA West project. Each of the options was assessed in terms of its physical and financial feasibility. In terms of the physical constraints, it was found that all three systems could work. Detailed financial analysis indicated that either of the two truck options would be a suitable solution. However, due to the limited information regarding the Combi truck option, it should be further investigated. This applies particularly to the actual running and maintenance costs for the equipment.

Jan 1, 2005

By George A. Laird

I. INTRODUCTION. THIS old and once famous district played, through its enormous production of silver and gold, an important part in the history of the State of San Luis Potosi. According to a pamphlet prepared under the direction of the Governor of the State, Sr. Don Blas Escontria, and presented to the visiting members of the Institute during the Mexican meeting of 1901, this district is situated 20 km. east of the city of San Luis Potosi, in a range of mountains of moderate height, extending 135 km. N. and S., and 16 km. E. and W.; and the mineralized area hitherto developed is about 600,000 sq. m. The history of the district,. as given by the record dated 1778, and formerly kept in the San Francisco convent, says that it was discovered in 1575 by Sr. Don Pedro Irarte, and adds that the city of San Luis Rey de Francisco del Potosi received its name (in allusion to the famous Potosi mines in Bolivia) by reason of the remarkable productiveness of its gold- and silver-mines in the first period of their exploration, during which they paid to the Crown, as " quintos " (the fifth part of the product), $97,000,000, as appears from the accounts of the royal treasury. The amount of the quientos paid during the " bonanza period " of 80 years was $72,000,000. The larger sum first mentioned probably represents a longer series of years. But either will suffice to indicate the great wealth of the mines. In 1663, the decadence of the industry began with the caving¬ in of several mines, concerning which the record of 1778, al¬ready cited, says, in substance, that on Good Friday one of the owners in the enterprise, in view of the unfavorable prospect of a lawsuit in which he was engaged, set fire to the timbers supporting the underground galleries and workings of the San

Jan 1, 1905

By Franklin M. Grynkewicz

The subject of bearing pile performance installed by vibratory hammers has been a matter of increasing study and continued controversy. A recent case study from a major bridge replacement project is discussed which provides encouraging data on the use of vibratory pile hammers as a primary means of pile installation and also presents the problems associated with its general acceptance. The bridge project case study foundations consisted of HP 14 x 89 pile sections, designed to develop capacity primarily in friction. Preliminary tip elevations were determined by traditional static analyses. Production pile installation was performed using an IHC S-70 Hydro-Hammer. Driving criteria and final production pile tip elevations were determined after preliminary indicator pile drive tests and static load test results at bridge pier cofferdam locations. Based on impact driven production pile performance, the Contractor wished to investigate vibratory driven piles as a means to accelerate construction schedule. Dynamic pile testing procedures were used as the primary measurement tool and test results were compared to the production pile drive records and prior static load tests. Field testing consisted of driving and monitoring with the PDA impact driven piles to the design tip elevation. Three vibratory driven piles were installed to the same tip elevation and immediately subjected to impact driving and dynamic testing to compare dynamic pile resistance. The results indicated that the site soil conditions were favorable for vibratory pile hammer installation. Recommendations and procedures for proceeding with vibratory hammer pile installation were presented to the Owner. These procedures included quality control in conformance with latest AASHTO recommendations. The Owner, in spite of the site specific data base and QA/QC procedures, would not accept vibratory pile hammer installation, due to the absence of precedence. It is concluded that for vibratory methods to become accepted a rational method of analysis, design and field QA/QC procedures requires development. In addition, the engineering community and Owners/Agencies must be more open to alternate methods of foundation construction. The continued development of dynamic methods of monitoring vibratory pile installation is considered to be key to the general acceptance of this installation procedure.

Jan 1, 1991

By Robert L. Virta

This U.S. Bureau of Mines paper discusses the structure of the talc industry, talc production, processing of talc ore, applications and demand for talc, and the outlook for the talc industry.

Jan 1, 1989

By Eric C. Halpin

"1. Introduction and Backgrounda. In its fundamental form, risk is simply the likelihood of an adverse impact. Expanding on this theme, the Corps of Engineers has broadly defined risk associated with infrastructure as a factor of three distinct elements: a probabilistic assessment of a hazard such as a flood or earthquake; a probabilistic assessment of how the infrastructure performs in the face of this hazard; and a measure of the likely consequences – loss of life, economic damage, environmental impacts – associated with the resulting inundation scenarios.b. The lessons and observations described herein relate to the Corps of Engineers experiences in implementing risk concepts for infrastructure management during the period 2005 through 2013. The Corps of Engineers is a large, decentrally operated and centrally led federal agency that plans, designs, constructs, operates, maintains, and/or manages a portfolio of over 3,000 built dam and levee systems within the United States. The infrastructure in this portfolio is 55 years old on average, and although much of the structures provide for flood risk management benefits, many of the dams deliver multi-purpose benefits. Scale matters – where scale and uncertainty are large, risk concepts provide great opportunity and arrangement for application.c. The amount of organizational change that is demanded for the implementation of risk concepts is considerable and should not be under estimated, but need not be feared if the path others have taken is considered. This paper is, in many ways, an opportunity to step back from the last seven years of implementing risk informed management, check our own azimuth and maturation, and share the purpose and energy behind our own continuing actions. Hopefully, this azimuth check is also beneficial to those that are either considering the use of risk or are in the process of implementing risk concepts.d. Success at managing the massive change related to incorporation of risk concepts will directly affect success of the infrastructure program. The three key organizational elements to consider –human systems such as governance and competencies; policies that outline the who, when, and why of decisions and management; and the processes and technology that outline how work is to be performed - are changed fundamentally. From senior leaders to project team members and all of the people in between, there is a need to discuss, confront, and vet the change and the role people and organizations have in the process. For the Corps of Engineers, with a history of over two centuries, deeply embedded beliefs about infrastructure aren’t transformed over night - the change process is decadal in scope. Given our self imposed “project execution” mantra and corporate objective, risk seemed threatening at first to the cost and schedule of delivering infrastructure projects. In reality, risk concepts have been responsible for savings and cost avoidance of nearly $6 billion over the last three years alone while at the same time justifying increased investment by several fold for the highest risk needs."

Jan 1, 2014

By M. Remillard, M. Garon, M. Thérien, D. Hodouin

"Nineteen streams in the copper and zinc flotation units of the concentrator of the Matagami division of Noranda Inc. have been sampled for particle size distributions chemical assays, and gold and silver contents in each particle size interval. The data are upgraded by the mass balance package BILMAT. These results, in conjunction with microprobe analyses, are used to quantify the silver losses in the copper clean¬ing flotation stages and to determine how overall silver and three silver-bearing minerals are recovered in the plant final products.RESUME Dix-neuf produits des circuits de flottation du cuivre et du zinc de la division Matagami de Noranda Inc. ont été échantillonnés pour leur distribution granulométrique, analyses chimiques et le contenu d'argent et d'or des fractions granulométriques. Le bilan métallurgique a été obtenu à l'aide du programme BILMAT. Ces résultats couples avec une etude minéralogique à la microsonde sont utilises pour quantifier les pertes argentifères aux diverses étapes de nettoyage du circuit de cuivre et pour de¬terminer la repartition de l'argent et des trois minéraux argentifères dans les produitsfinals de l'usine.INTRODUCTION The Matagami division of NORANDA INC. produces copper and zinc concentrates from a sulphide ore which contains a small amount of gold (0.34 g/t) and silver (20 g/t). Only a small part of the silver (~-30%) is presently recovered in the copper concentrate. The objective of this study is to evaluate the metallurgical behaviour of silver, and secondarily of gold, in the flotation circuit for a possible increase of its recovery in the copper concentrate to improve its economic value. For that purpose it is worthwhile to study the minerals which bear silver and to determine the critical flotation stages where they are lost in the tails. The methodology proposed here is based on a coupling of a mineralogical study and a detailed mass balance calculation in the flotation circuit."

Jan 1, 1986

This chapter presents proportionate mortality ratios (PMRs) derived from death certificate data in the National Occupational Mortality Surveillance (NOMS) database for the years 1986 through 1993. At the time this report was prepared, 1993 was the latest year for which data were available. Industry is classified under the 1980 U.S. Bureau of the Census classification system [Bureau of the Census 1982]; cause of death, under the International Classification of Diseases, Ninth Revision (ICD-9) [World Health Organization 1977]. A PMR of 100 indicates a mortality risk for a particular industry group that is similar to that for all industry groups combined. A PMR over 100 suggests a higher risk; a PMR under 100 suggests a lower risk. PMRs are subject to many factors that affect their reliability and validity and may not be comparable across populations with very different causes of death. An elevated PMR for a specified cause of death among an occupational or industry group may indicate a relationship between a work exposure and the cause of death specified. However, there are many limitations of PMRs as a measure of risk; they are most useful for generating hypotheses about exposure-disease relationships, which can then be tested in other studies. Selected PMRs are presented separately for males and females for coal mining, metal mining, nonmetallic mineral mining and quarrying (which includes nonmetal, stone, and sand and gravel), and for oil and gas extraction. All PMRs have been adjusted for age and race. In general, PMRs are presented only if the lower 95% confidence limit exceeded 100. If a PMR in an ICD-9 subcategory was above 100, however, the PMR for the larger category into which the subcategory falls is always presented and may be less than 100. PMRs can be expected to be elevated for conditions that have a high prevalence in particular occupational groups. PMRs showed elevated values for conditions known to affect miners, such as coal workers' pneumoconiosis, pneumoconiosis due to silica, tuberculosis, chronic pulmonary heart disease, and injuries. Additional findings of interest were- • An elevated PMR for myocardial infarction among male coal miners (table 2-1); • Elevated PMRs for neurologic disease in general and anterior horn cell disease, in particular among male metal miners (table 2-3); • An elevated PMR for rheumatic heart disease in male metal miners (table 2-3); • Elevated PMRs for malignant neoplasms of the digestive organs and peritoneum and for malignant neoplasms of the colon and rectum in female nonmetal miners (table 2-6); and • Elevated PMRs for non-A, non-B hepatitis and arteriosclerotic heart disease among male oil and gas workers (table 2-7).

Jan 5, 2000

Organization Place - Date 1918 American Iron and Steel Institute New York, N. Y. May American Water Works Association :.. St. Paul, Minn. May 20-25 American Institute of Chemical Engineers Berlin, N. H.. June 19-22 American Concrete Institute Atlantic City, N. J. June 24-26 American Society for Testing Materials Atlantic City, N. J. June 25-28 New York Electrical Society New York, N. Y. June National Association of Stationary Engineers Cincinnati, 0. Sept. 9-13 National Exposition of Chemical Industries New York, N.Y.. Sept.23-28 American Chemical Society Cleveland, 0. Sept. National Petroleum Association Atlantic' City, N. J. Sept.

Jan 5, 1918

By G. S. Harper

Noise in general and drilling noise in particular have received increasing attention within the South African mining industry during the last 10?15 years. The Mine Health and Safety Committee1, during their 2003 annual summit, established two significant milestones to be met by December 2008 and December 2013. The 2008 milestone target is that of no more than ten per cent deterioration in hearing among occupationally exposed individuals, whereas the 2013 milestone target is that of less than 110 dB sound pressure levels at any place in the workplace. While these targets relate to general noise within the mining industry, it is widely believed that the most significant source of noise contributing to noise induced hearing loss (NIHL) among the underground workforce, is that of pneumatic rock drills. Data pertaining to the noise emission level of any machine is generally reported as either a sound pressure level or a sound power level of a single machine measured under free field conditions as defined in Appendix 3 of SABS-ISO 37442. However, rock drills are seldom used in isolation and underground conditions cannot be considered as free field. A methodology for the selection of rock drills on the basis of total operating cost has been developed. However, this paper focuses on the noise elements of the generic methodology and provides a model for the prediction of the composite sound pressure level and the equivalent noise exposure levels of groups of individuals from machines, used singly and in combination in an underground environment based on the sound pressure level determined according to SABS-ISO 3744 under free field conditions. The methodology includes provision for the consideration of the effect of hearing protection devices and the use of multiple machines in combination and provides an indication of the potential costs of hearing compensation.

Jan 1, 2006

By F. D. DeVaney

Manganese-bearing deposits f the Leadville, Colo., district are of two distinct types. Manganosiderite, a combined or intimately mixed ferrous and manganous carbonate, occurs in unaltered zones as the predominant mineral. From 50 feet below the surface to as deep as 900 feet, psilomelane and wad, both black manganese oxide minerals, are found in intimate contact with hematite and limonite. A typical analysis of the black oxide ore shows 20.08 percent Fe, 18.64 percent Mn, 15.91 percent insoluble, 14.91 percent moisture, 0.94 percent Zn, and 2.13 percent Pb. A considerable tonnage of the oxide ore has been mined for production of spiegeleisen and for other purposes.

Jan 1, 1940

By David Mast, Irwan Halim, Seung Han Kim

Nowadays more infrastructure tunnel projects are procured using design-build method. In this environment, the Owner’s engineer would typically provide performance requirements for the design-builder, and the Contractor’s designer would work with the contractor to design the tunnel lining based on the Contractor’s means and methods and manufacturing process. This paper will describe the typical requirements provided by the Owner based on its design objectives, and the means and methods by the Contractor that would significantly impact the design. Project examples and recommendations for Owner’s requirements will be provided that can optimize the design and still achieve the Owner’s performance objectives.

Jun 13, 2021

By W. L. Falke

The Bureau of Mines has developed a system that permits the "soft" soldering of aluminum and aluminum alloys with standard tin-lead solders. The method employs application of a thin nickel-copper-alloy coating to the substrate, which enables the tin-lead solders to wet readily and spread over the areas to be joined. With conventional technology, aluminum and aluminum alloys are extremely difficult to solder because tenacious surface oxide films prevent wetting. With the Bureau-developed method, the aluminum substrate is mechanically or chemically cleaned to facilitate bonding to a minute layer of zinc that is subsequently applied with an electroless zincate solution. The nickel-copper-alloy (30 to 70 pct Ni) coating is then applied electrolytically over the zinc, using immersion cell or brush-coating techniques. Development of acetate electrolytes has permitted deposition of the proper alloy coatings. The coated areas can then be readily joined with conventional tin-lead solders and fluxes. The joints so formed are ductile, strong, and relatively corrosion resistant, and exhibit strengths equivalent to those formed on copper and brass when the same solders and fluxes are used. The method has also been employed to soft-solder magnesium alloys.

Jan 1, 1983

By Andrew R. Marchbank

The application of biologically assisted methods for metal extraction in the mining industry has a long history, but development of modern techniques has been relatively slow. There is, however, a resurgence of interest in the industry with the recent development of methods to successfully treat base metals concentrates. Two major pilot plant programs for treatment of chalcopyrite concentrates have been initiated in the past year and results from one are beginning to be released. This paper provides an overview of methods that have been applied in the past; from the earliest deliberate applications of the technology, through the copper and uranium heap and dump leach applications, the more highly engineered agitated tank leach gold applications and the developments currently taking place in the industry.

May 1, 2002

By N. Wang, A. I. A. Salama

"An index to evaluate the amenability for processing of different coals is implemented. The index is based on the well-known Mayer-curve or M-curve. The index is superior to other existing indices and is implemented using Microsoft-Excel™. Several coals are used to demonstrate the implementation of the index proposed.IntroductionIn 1950, Mayer introduced a curve that carries the information embedded in the fir s t three curves or ash curves of the conventional washability tables and curves (Peng et al., 1979; Osborne, 1988). The curve was labeled the Mcurve (abbreviation for Mittlewertkurve in German or the Mayer- curve). The main idea behind the curve is to use the ordinate for the cumulative mass and the abscissa for the ash (attribute) mass. Specific slopes on the resulting curve represent the cumulative float, cumulative sink, and elementary ash (attribute) contents (Mayer, 1950, 1953, 1957; Venkatesan, 1975; Osborne, 1988; Salama, 1989). Beyond the ash values, the curve carries graphical information that can be used in evaluating coal processing characteristics. Consequently, it becomes possible to present several raw coals on a single diagram, thus making it easier to compare their processing characteristics. This is particularly useful in comparing various size ranges of raw coal or the same size range from different seams. Therefore, the M-curve is adopted as a vehicle for developing the “processing (washing) characteristics index” implemented in this paper."

Jan 1, 2001

By J Wallis

The stability of a raise bore is often assessed using the rock mass classification system published by McCracken and Stacey as a modification of the Q system. Often the assessment is done using a spreadsheet to manipulate geotechnical log(s) of boreholes. This paper discusses the inherent difficulties with this approach. Recent work by others to provide guidelines to the classification system is discussed. A recent example of the design and raise bore performance at Macraes Gold Mine, New Zealand is presented. A key issue is that a visual assessment of the drill core and/or core photographs is necessary to æground-truthÆ the classification.

Jan 1, 2008

A preliminary program dated April 25, 1974 was prepared for Development Engineering, Inc. (D.E.I.) on research and development, laboratory; field and other engineering studies for the disposal of retorted oil shale. This program was revised and published as a final document dated December 17, 1974. The document included a discussion on the peculiarity of retorted shale materials to be investigated and a discussion of the various laboratory and field tests which would need to be conducted to define their physical and chemical properties. The proposed research and development program was divided into eight work phases as follows: I - Program Development II - Exploratory Laboratory tests on old U.S.B.M., retored shale III - Laboratory tests on Pilot Plant retorted shale IV - Laboratory tests on retorted shale from Semi-Works Plant, and field and test plots and ponds. V - Field compaction tests

Jan 1, 1975

By A. L. Service, C. C. Popoff

Phosphate deposits in Montana , Idaho , Wyoming , and Utah are important factors in the mineral , agricultural , and industrial economy in the western part of the Nation . This report presents background information , including geology , mining , beneficiation , processing , resources , and economics , assembled to provide a comprehensive introduction to a series of four area reports . About 20 percent of the Nation's phosphate is produced from the Western field where there were 6 surface and 9 underground mines in operation in 1963 . This region also has an estimated 58 percent of the Nation's phosphate reserves , and continuing development is assured by these abundant resources and an increasing demand for phosphate products . Long range forecasts indicate that the United States will continue to use increasing amounts of both agricultural and industrial phosphate products . Beneficiation has become an important part of the phosphate processing industry , and two flotation plants and several washing plants were in operation in 1963. Recent studies by the Bureau of Mines Metallurgy Research Center , Albany , Oreg . , have been directed toward developing flotation processes applicable to treatment of marginal phosphate rock . Other Bureau of Mines research is being directed toward improved methods of ore recovery , ground control , and mining .

Jan 1, 1964