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By George S. Koch

In preparing diamond-drill core samples for assay at the Homestake mine, Lead, S. Dak., 5-foot intervals of core are processed through three stages, crushing, grinding, and pulverizing, and portions of the core material are discarded after splitting at each stage of preparation. Then two 1-assay-ton fractions are taken from the pulverized material and assayed. This report investigates alternative methods of sample preparation. The consequences of crushing, grinding, and pulverizing all rather than part of the core are appraised through the statistical analysis of assay results from 118 5-foot intervals of core. Evidently, a substantial improvement in precision at small additional expense is obtained by grinding most or all of the core before splitting. Pulverizing all of the core would be desirable only if doing-so would cost less than assaying five random splits from each interval. Graphs and tables detail appropriate procedures to obtain specified precisions. The experimental design and methods can be applied to similar problems in preparing core and other geological samples.

Jan 1, 1972

By Clarence O. Babcock

ROCK BEHAVIOR has proved of national interest in a variety of fields. The behavior of rock consequent to a nuclear blast was used to detect such blasts, as criteria for the design of underground military defense installations that would resist nuclear blasts, and for judging the feasibility for peaceful uses of nuclear explosives. An obvious peaceful application of nuclear explosives would be for large-scale rock excavation, and plans were presented during the year to improve the present Panama Canal or create a new canal by this method. These plans were based largely on earlier crater tests that demonstrated rock behavior when subjected to a buried nuclear blast. A knowledge of rock behavior under impact was used to evaluate the materials of the moon by means of the geometric configurations visible in the close-up pictures of the moon surface taken by the U.S. rocket Ranger 7. The composition of the moon must be considered in devising methods for taking samples of the surface layers or in designing underground shelters as bases for future explorations of the moon.

Jan 1, 1965

By Walter J. Frank

Thls report summarizes work done under Bureau of Mines contract H0357100, "Development of a Crimp Connector for Trailing Cable Splices." The purpose of this effort was to establish optimum connector design conditions to meet flex cycle, pullout and electrical resistance criteria on phase power conductors. Field testing of "optimum design" connectors is briefly discussed. One of the primary objectives of contract H0357100 was to enable one to design better performing phase conductor connectors. Illustrating the practical significance of this 1s a discussion on the development of a new splice kit for trailing cables. The connectors in this kit were designed in accordance with the design methods described in the contract final report. Kit components, test data, and a connector installation tool are also discussed. The successful effort on the phase connector has resulted in contract H0377042, entitled "Design and Testing of Joining Sleeves for Trailing Cable Ground and Pilot Wires." The purpose of this contract (currently in effect) is to improve ground-conductor and pilot-wire performance. Significant findings to date are discussed.

Jan 1, 1979

By W. E. Lamont

The Bureau of Mines studied the potential for recovering marketable barite concentrates that meet oil well drilling-mud specifications from barite waste pond materials. The study was conducted as part of the Bureau's research program to conserve domestic mineral resources by advancing mineral recycling technology. The samples, which were obtained from Georgia, Nevada, Missouri, and Illinois, varied widely in character, particle size, and barite content. The samples were treated with sodium silicate and sodium cetyl-stearyl sulfate and then floated. The flotation flow sheet was modified to reject barren coarse and/or slime fractions from some of the samples, and one feed sample had to be scrubbed prior to flotation to remove residual flotation reagents. The cleaned concentrates had BaS04 contents ranging from 95.0 to 96.9 percent, while recovering 81.2 to 95.9 percent of the barite in the feed. The specific gravity of each concentrate exceeded the specification of 4.2. The removal of the flotation reagents from the flotation concentrate was not investigated.

Jan 1, 1982

By Andrew B. Cecala, Edward D. Thimons, George W. Klinowski

The U.S. Bureau of Mines has designed and evaluated total mill ventilation systems at two different mineral processing operations. Both systems have proven very effective at reducing respirable dust levels throughout the mill in a cost-effective manner. A 25,500-cfm system installed at a clay processing mill provided approximately 10 air changes per hour. This system reduced respirable dust concentrations by approximately 40 pct throughout the mill building. The second evaluation was performed at a silica sand operation. Tests were performed with 50,000 and 100,000 cfm of ventilation to the mill building, corresponding to 17 and 34 air changes per hour. Average mill-wide respirable dust reductions were 36and 64 pct, respectively. Not only did these systems reduce respirable dust concentrations and increase visibility throughout the mills, they were also easy to install and required minimal maintenance. A total mill ventilation system provides a general purging of the mill air; the system should be viewed as a supplemental technique to assist other dust control systems in operation.

Jan 1, 1993

By D. Caruso

The health and financial costs of cumulative injuries are plaguing the mining industry. Industry leaders are concentrating on reducing the risk of injury to their workers through design and redesign of work environments. While ergonomics is not a currently regulated field, many mines are realizing that the only way to tackle their most costly injuries, cumulative injuries, is to make the proactive choice to understand those injuries, their root causes and to make workplace changes to prevent them from occurring. Reduction of these injuries not only improves the health and morale of the workers but increases productivity and profit for the companies. Knowledge and reporting of ergonomic risk factors by employees and ergonomics committees is key to these changes and to the reduction of cumulative injuries. NIOSH is developing strong relationships with industry associations and equipment manufacturers to leverage their communication abilities to transfer knowledge to their customers and make a difference in the health and safety of U.S. miners. The benefits of a formalized approach to reducing these injuries along with examples will be presented.

By Mark A. Ackerson, Kenneth E. Hjelmstad

An ideal fire warning alarm system for underground mines would be low cost, convenient, fast, reliable, and able to warn all underground workers. Present warning systems, such as phones, messengers, and stench, fail one or more of these criteria. The U.S. Bureau of Mines may have devised the ideal system. The one way communication system employs a large loop antenna and transmitter to create a 630 hertz (Hz) electromagnetic field to send information through-the-earth to cap lamp battery mounted micro- receivers worn by underground miners. Field tests of prototype equipment in 1986 resulted in through-the- rock signal transmission of over 762 m (2500 ft). Subsequent hardware upgrades for more recent tests resulted in transmissions of over one mile. Recently developed receiver circuitry employs phase- locked-loop detection circuitry responsive only to a specific series of pulses of given time duration, that eliminates false alarms from electromagnetic noise emitted by mine equipment, power lines, or lightning. A multichannel system can relay standard messages to miners

By C. A. Rhoades

A major contributor to the problem of short life expectancy for blade-type conveyor belt cleaners is uneven wear along the blade edge. Uneven wear results in the formation of channels in the blade edge, which allow material to be carried back between the blade and the belt. In an effort to reduce the uneven wear problem, the U.S. Bureau of Mines has studied the mechanisms responsible for effective belt cleaning. From this study emerged a design for a cleaner blade that would greatly reduce uneven edge wear. The design consists of a standard cleaner blade incorporating air passages that allow for the expulsion of air along that part of the blade edge in contact with the conveyor belt surface. The results of 18-h tests indicated that the expulsion of air on the blade edge prevents scratches from developing into deep grooves. These tests showed that effective blade cleaning life can be extended 25 times using the pneumatic cleaning blade, compared with solid metal cleaning blades.

Jan 1, 1989

By Donald O. Capstick

In 1981, U.S. Bureau of Mines personnel conducted a survey of claims and prospects in the Wheeler Ridge RARE II area to determine if mineral resources or potential for resources exists at deposits in the area. Results of Bureau of Mines investigations indicate the area contains no identified mineral deposits. However, the geologic setting at the Round Valley Peak Prospect near the center of the study area is considered to be favorable for the discovery of tungsten resources with associated molybdenum and copper. Tungsten deposits, should they be present, would be expected to occur at depth in tactite at or near the calcareous rock-granite intrusive contact. Sand, gravel, and stone deposits in the area are not considered to be resources because equal or better quality material is available closer to major markets. INTRODUCTION The 16,200-acre (6,560 ha) Wheeler Ridge study area is 11 mi (18 km) northwest of Bishop, California, on the eastern flank of the Sierra Nevada range. The John Muir Wilderness adjoins the study area's western boundary (fig. 1).

Jan 1, 1983

By Robert J. Timko, R. Lincoln Derick

This U.S. Bureau of Mines study examined spontaneous heating episodes in coal mine pillars in an active underground coal mine. The information obtained from these incidents was then analyzed to learn which sampling methods provided the earliest indication of pillar heating. The objective of this study was to discover if the location of future events of pillar spontaneous heating could be inferred from the available information. The spontaneous heating-prone area in this evaluation involved pillars located just in by the mine portals. Several detection methods were used to determine gas levels outside as well as inside the affected pillars. It was hoped that, by incorporating external and internal sampling methods into an organized program, locations undergoing spontaneous heating could be determined more readily. This study found that by drilling small-diameter boreholes into the pillars, then obtaining gas samples from the affected pillars, the ability to locate early spontaneous heating episodes was improved. However, the ability to accurately predict future spontaneous heating events remains in question.

Jan 1, 1995

The Bureau of Mines has developed test procedures and criteria for evaluating explosive reactivity of explosive-contaminated solid waste substances generated by U.S. Army ammunition plants. These substances are produced as explosive-contaminated sludge from wastewater treatment plants, residues from the burning of munitions and explosives on open ground, and residues from deactivation furnaces. The characterization of explosive reactivity is a prerequisite for disposal of such waste materials, which may be contaminated with primary explosives, propellants, or pyrotechnic materials. The Bureau has proposed two tests for this purpose. These tests were developed to evaluate the explosive reactivity as defined in Title 40, Code of Federal Regulations (CFR), part 261.23(a)(6) and (7). These are the Bureau's gap and internal ignition tests, which determine the sensitivity to shock and thermal stimuli, respectively. This report also includes gap and internal ignition reference data for typical blasting agents, high explosives, propellants, and marginally reactive substances. These reference data were used to establish test criteria. The Bureau has evaluated over 400 samples of contaminated soil, sludge, and burning residues using these two test methods.

Jan 1, 1988

By T. E. Marshall, D. R. Dolinar, T. M. Barczak, T. P. Mucho

Over a portion of the older limestone mine workings at the NIOSH Lake Lynn Laboratory, a mining health and safety research facility, a large sinkhole formed caused in part by the intersection of several tightly spaced joint sets and unusual weather conditions. The anticipated propagation of the associated roof failures threatened to encroach upon a portion of the facility’s secondary escapeway. To protect the escapeway, two cribs walls and over 80 cable bolts were installed. In addition, extensometers were installed to monitor roof movement in the escapeway. However, a large roof fall associated with the propagating roof failures in the sinkhole area partially destroyed one crib wall where the adjacent escapeway was not reinforced by cable bolts. Recent roof movement information indicates that this area is still active. Based on these measurements, steps have been taken to stabilize this portion of the escapeway. This paper discusses roof monitoring, the roof movement, the large roof fall, propagation of the roof failures, and the recent support measures undertaken to stabilize the escapeway.

By S. A. Gustavson, H. E. Olund

This report has been prepared to review the history of the Premium Price Plan for copper, lead, and zinc, which was in operation from February 1, 1942, to June 30, 1947. It includes various charts and tables comparing costs and production data, and data on exploration premiums that were included in the Plan during the last year of its operation.

Jan 1, 1950

1. In 2003, 14,391 mining operations reported employment statistics to the Mine Safety and Health Administration (MSHA). Almost half (49%) were sand and gravel mines, followed by stone mines (30%), coal mines (14%), nonmetal mines (5%), and metal mines (2%).

Feb 1, 2005

By Rudolf E. Greuer, Linneas W. Laage, Xinton Chang

All output is saved in the file MFIRE OUT m the di¬rectory and on the disk containing the program The file can be inspected with a text processor and sent to a print¬er, if needed CONTENTS OF OUTPUT FILE The comment lines, reference temperature, air densi¬ty, a table of the units of measure for the results, and the average values are shown at the beginning of MFIRE OUT All input data will be shown in the output file if LOUT on Control line number 1 is _<-1 For each contamination source, a new branch will automatically be setup The new airway and junction ID numbers will not interfere with the original numbering scheme of the data file Next are the results of the selected simulation(s) in the following order network balancing, network balancing considering temperatures, transient-state modeling, and altered equilibrium due to fire and distribution of the contaminants. Depending upon the contents of the data file, and the simulation selected, attention, warning, and error message will be shown at locations where calculations resulted in unusual conditions

Jan 1, 1990

By Franklin P. Hall

U.S. supply and demand data for utility electricity by States and regions were tabulated for the years 1960 and 1965. Estimates are provided of State-by-State quantitative data for the utility electricity industry that can be integrated into State and regional energy balances by source, form, and major consuming sectors, and used to determine basic flow-patterns. The difficult problem of compiling interstate and interregional shipments of electricity was resolved by (a) assuming the negligibility of interregional shipments and (b) deriving a theoretical line loss percentage used for determining interstate shipments. The data developed were able to show an estimated total supply of utility electricity available for consumption. The tables also report the distribution of the supply among the major consuming sectors (household and commercial, industrial, and transportation). To compare the various energy sources of utility electricity, quantities were converted to their British thermal unit (Btu) equivalents. The Federal Power Commission, Edison Electric Institute, and Bureau of Mines are the sources of the data used in this study.

Jan 1, 1969

By John J. Sammarco

The functional safety of programmable electronic (PE) mining systems is an international issue and concern. From 1995 to 2001, 11 PE-related mining incidents in the U.S. were reported by the Mine Safety and Health Administration (MSHA); 71 PE-related mining incidents were reported in Australia. MSHA does not have regulations for formal evaluations of the functional safety of PE mining systems. Hence, the National Institute for Occupational Safety and Health (NIOSH), in partnership with MSHA and the industry, generated the NIOSH safety framework for functional safety of PE mining systems. An overview of the NIOSH framework is given; the key framework elements, the safety life cycle and safety integrity levels are detailed. The safety framework approach has impacted the national and Australian mining industries by enabling the industries to advance from an ad-hoc approach to a formalized and systematic functional safety process. In retrospect, valuable lessons were learned for addressing functional safety and for changing industry perspectives and practices. These lessons continue to benefit mining and are applicable to other industries as well.

By Yael Miron

Coal mines that undergo self-heatings, and specifically mines that sustain both floor heave and self-heatings, would benefit from the use of sealants to minimize air ingress to susceptible areas. The U.S. Bureau of Mines (USBM) evaluated three sealant systems for this purpose, bentonite-water mixtures, silicate gel, and guar gum gel. The guar gum-based gel was the only sealant that possessed the desired properties of elasticity, ease of preparation, adaptability to the mine, and a long life. In addition, since the gel consists mostly of water, it could quench or cool nearby heatings. Optimal formulations were determined in laboratory tests, and then tested in the USBM Safety Research Coal Mine. Two for-mulations resulted in stable gels that lasted for at least 12 months in the mine. Semicontinuous preparation of gel using an eductor was evaluated and appears feasible. Although guar gum gel is expensive, selective use to prevent heatings in specific areas would be cost-effective, both in terms of productivity and enhanced mine safety.

Jan 1, 2010

By Lucia Kuizon

Results of the U.S. Bureau of Mines&apos; survey of mineral resources in the Cuyama RARE II study area indicate there is no potential for metallic minerals and low potential for the development of gypsum resources. There are no producing or developing mines within the study area. The Santa Barbara Canyon Prospect contains 30,000 tons (27,000 t) of subeconmic gyspum resources, the Wagon Road Prospect 276,000 tons (250,000 t), and the Brush Fence Canyon 61,000 tons (55,000 t). Most of the resource in the Brush Fence Canyon Prospect is outside the area. Gypsum was not observed at the Cuyama River deposit. Present gypsum and gypsite requirements are being met by larger deposits closer to major markets. INTRODUCTION Location (USGS) Present and Previous Studies (to be combined with USGS section) The Bureau of Mines reviewed literature and mining claim records for the study area. A field examination of known mineral properties was made in October 1980; it included mapping and sampling of prospects to evaluate the economic potential of mineral resources.

Jan 1, 1981

By Dorsey A. Lyon

At the main experiment station of the U. S. Bureau of Mines , situated in Pittsburgh, Pa . , three phases of its work in behalf of the safety of the coal miner are the establishment of permissible explosives for use in gaseous and dusty mines , the development of electrical equipment that can be used with safety in mines of this character , and improvement in the safety of mechanical devices used in and about the mines . Also That these efforts are beginning to have a cumulative effect in lives. saved is evident from the fatality statistics of the industry . Although nearly 80,000 more men are employed in coal mining than ten years ago and much more coal is mined , the fatalities each year are considerably less than ten years ago . the amount of coal mined in a year for each life lost has risen between 60,000 and 70,000 tons . In 1909 , the year before the Bureau was created , the production of coal for each life lost was 174,416 tons . In 1920 , the production for each life lost was 285,000 tons .

Mar 1, 1921