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By T. A. Lang

Concepts and equations have been developed to quantitatively determine the stability of a rock bolted coal mine roof as a structural (beam-arch) member consisting of reinforced rock units. The equations take into account: rock bolt tension, length, spacing, and orientation; size of opening, strength and physical properties of the rock; and loads from distressed rock, and were critically reviewed using sensitivity analyses and the results available from relevant previous analytical and physical model investigations. It is concluded that they can essentially be validated by using small scale physical models and the full size mine entry model at the USBM Spokane Research Center. However, a comprehensive research program, including analytical and laboratory investigations and field trials in typical mines, will be required to define and validate criteria and standards for using the equations as a basis for a rational design code for rock reinforcement installations to replace the semi-empirical rules now being used. For example, these studies have shown that the practice of installing vertical roof bolts with a uniform spacing equal to the bolt length is inherently unsafe and that the spacing should be reduced near the walls to prevent shear failure of the roof strata. The development of such a rational design code would provide enhanced safety in coal mining operations and warrants a high priority in the Bureau's ground control research program.

Jan 1, 1981

By Joseph L. Buckley

A total of 55 conveyor belt fire tests were conducted in the Bureau of Mines Fire Test Gallery, located at the Factory Mutual (FM) Fire Test Center West Glocester, R.I. The objectives of these tests were to: 1) determine the fire resistance and burning characteristics of various conveyor belt materials under simulated mine conditions; 2) provide essential data for designing a reliable bench-scale conveyor belt fire resistance test; and, 3) determine fire test conditions that will discriminate between low, moderate and high fire resistant materials. Belts, representative of those which mold he found in underground coal mines were examined under n umber of experimental conditions which included; ignition intensity; air flow rate; ratio of belt bright (h2) to overall gallery height (h1); exposure time; and, belt width. It was found that fire propagation could be achieved for some "fire resistant" belts (complying with the present Schedule 2G standard for approval) when exposed to an Ignition source of =6000 Btu/min for a 15-min period at a belt height ratio of 01.66. There appears to be a dependency of flame propagation on air flow rates and belt width, although the tests performed do not provide a quantitative trend. Recommendations are made for additional work to resolve some anomalous date and to fill voids in the rest program.

Jan 1, 1978

By Joseph A. DeCarlo, Eugene T. Sheri dan

The process of converting coal into coke is known as carbonization. Essentially, carbonization is destructive distillation in which the volatile matter of coal is released when coal is heated above its decomposition temperature and passes through a plastic stage before solidifying and forming coke. The mechanics of coke formation are complex, and the specific properties of certain coals that allow them to "cake" or form coke are still unknown. Coke is a hard, cellular, carbonaceous mass, formed by heating coal in the absence of air. It is porous, irregular in size and shape, and is similar in appearance to wood charcoal. Coke, however, is denser, more porous, and more abrasive than charcoal. Coke has been in use for several thousand years. History has recorded its use in Greece before the birth of Christ, and it is thought to have been used in China even before that time. It was not until the l6th century, however, that a method for coking was developed in Europe that subsequent ly evolved into the coking process that is known today. The coke industry in the United States began in the latter half of the 19th century when beehive-coke ovens were built to supply fuel for iron blast furnaces. Before this time, an iron industry fueled principally by charcoal had been in existence for several hundred years. With the depletion of timber resources, coke gradually replaced charcoal as blast-furnace fuel, and by 1875 more iron was made with coke than with any other fuel. Before 1893 a 11 coking was done in beehive ovens. These ovens are refractory kilns with arched roofs, sometimes joined together to form batteries.

Jul 1, 1964

By D. A. Wilson

A cyclic leaching process was developed for selectively leaching and recovering cadmium from nickel-cadmium scrap battery waste. The six major steps in the process are the following: (1) washing the plates to remove KOH electrolyte, (2) roasting at 550° to 600° C to oxidize metallic cadmium and decompose cadmium and nickel salts, (3) leaching with an ammonium nitrate solution, (4) precipitation of the leached cadmium from solution as cadmium carbonate using CO2 gas, (5) removal of CO2 from the lixiviator by adjusting to pH 4.5, heating, and evacuating the system, and (6) removal of small amounts of leached nickel from the lixiviator using a solvent extraction technique. The regenerated lixiviator is then recycled to leach additional plates. Cadmium extraction was 94 percent and the cadmium carbonate product contained 0.14 percent nickel and 0.12 percent cobalt impurity. The leached plates were smelted to a high nickel-low iron alloy with no detectable amounts of cadmium.

Jan 1, 1971

By Herbert H. Einstein

Instability of rock slopes often occurs in the form of excessive movement of bodies that are bounded by discontinuities. The well known limit equilibrium analysis for wedges and blocks suffer, however, from procedural simplifications and from the basic deficiency of limit eguilibrium analysis--the rigid body assumption. Thus, stability analysis for 2-and 3-plane wedges with a wide range of additional features regarding failure modes and external forces have been developed. The deficiency, due to the rigid body assumption, was corrected by an approach that includes the effects or the in-situ stress field and of the stiffness of discontinuities. The final step in making limit equilibrium approaches more valid was achieved with the method of artificial supports which makes it possible to identify among all possible failure modes the critical one and to determine the corresponding factor of safety. The analytical development includes the creation of appropriate computer codes and routines for programmable pocket calculators.

Jan 1, 1979

By Robert T. Davis

An award is a form of recognition given for superior performance in a special field of endeavor. Each year awards are given by the Joseph A. Holmes Safety Association and the National Safety Council to the coal-mining industry's underground and open-pit mines that have worked a specific number of man-hours without a lost-time injury. These awards have a dual significance in that they prove efficiency can be attained without injury to persons. Safety awards do not result from luck or good fortune but do result from sincere desire coupled with sufficient effort and cooperation to achieve a desired goal.

Jan 1, 1964

By Samuel P. Harteis

Many mining operations rely on retention bulkheads to provide a barrier between impounded water and active mine workings. However, bulkhead failures can cause catastrophic flooding that puts the underground workforce at risk. Underground observations and evaluations of existing bulkheads indicate that a systems approach is required when building an underground water or slurry retention system. In addition to engineering the bulkhead, the designer must ensure the quality control of materials and workmanship of the bulkhead, the reaction of the mine strata when exposed to water under pressure, and methods to monitor the performance of the retention system. Researchers from the National Institute for Occupational Safety and Health (NIOSH), with the assistance of the Mine Safety and Health Administration (MSHA), conducted an extensive review of bulkhead permits submitted to the MSHA Technical Support office in Bruceton, PA. In addition, the researchers visited accessible bulkhead installations at undeground mining operations to gather information related to construction practices, maintenance issues, and monitoring and emergency response procedures. Several key items were identified that must be considered when permitting the installation of an underground fluid retention system.

Jan 1, 2008

By Harvey Patashnick

Current state-of-the-art microweighing technology represented by the Tapered Element Oscillating Microbalance (TEOM) is utilized as the basis for a new generation of Personal Dust Exposure Monitors (PDEM's). Two design configurations are presented. The first is an end-of-shift analysis system which uses small TEOM-PDEM cannisters that replace the filter cartridges in the current PDEM system. All other components carried by the miner (cyclone preseparator and pump) are the same. After the shift the TEOM cannister is plugged into an interface box which enables a minicomputer to automatically identify the unit, determine the dust mass increase during the shift, compute the shift average dust mass concentration, and print out and/or store the data. The second design is a real-time TEOM-PDEM system which is capable of operation over a 10-hour shift and on demand display real-time dust concentration level, time weighted average, and shift average concentration. As a result of the design study, a prototype end-of-shift analysis system was fabricated and delivered to the Bureau of Mines. A description of this system which consists of six TEOM cannisters, interface electronics and minicomputer is given. The system represents a significant advance in the dust monitoring program in terms or accuracy and automation.

Jan 1, 1983

By Juh W. Chen

A process for recovery of energy from waste coal fines was investigated. The process, which was developed through laboratory, bench, and pilot plant scale experiments, consists of mechanical cleaning followed by high temperature oil agglomeration and pelletization. The process can produce a quality product under an economically and environmentally acceptable condition. Waste coal fines with ash less than 35: and HHV greater than 6,000 BTU/1b have been upgraded to a product with less than 15% ash and HHV Greater than 11,500 BTU/lb. A computer model has been developed to optimize the processing costs and to perform economic evaluation of specific sites. Ultimately tine model can be utilized to establish a priority listing for a region in assisting the determination of reclamation strategy.

Jan 1, 1983

By Boyd Wise

A jet pump injector was developed and successfully tested, thereby demonstrating the feasibility of a jet injector for introducing coarse coal into an operating slurry face haulage system: In Phase I a variety of injection concepts were evaluated, and the jet pump was identified as best, due to its simplicity, compactness and performance potential. In Phase IIA subscale jet pump injector tests were conducted, and a computer model of a jet pump injector was developed whose performance predictions correlated well with subscale test results. In Phase IIB various system configurations were defined for integrating a jet pump injector into a fully operational underground coarse slurry face haulage system, further highlighting the feasibility and practicality of such a system. In Phase III a full-scale mobile haulage vehicle embodying a jet pump injector and coal sizing equipment was detail designed into a practical vehicle with attractive performance characteristics. More importantly, fully operational full scale jet pump injector -and feeder/breaker subassemblies were tested and proven successful in their ability to down-size coal to 3" in all 3 dimensions and to consistantly provide slurry of 4217 weight concentration at 6.4 TPM throughput under a wide range of operating conditions including zero to maximum feed rate within 5 seconds.

Jan 1, 1985

Objective To develop safety training tools for mine safety and health professionals that fill gaps in currently available materials. Background Over the past 4 years, NIOSH has developed and released a series of training videos targeted at underground mine safety. These videos were developed in close cooperation with the mining industry and safety training professionals and were intended to provide realistic, interesting, effective training to both new hires and experienced miners. The videos cover the mining cycle, starting with the breaking of the rock (Handling Explosives in Modern Mines), making certain the work area is safe after a blast (Rock Falls— Preventing Rock Fall Injuries in Underground Mines), installation of ground supports and recognition of failed supports (Miner Mike Saves the Day), and hauling both ore and materials in the mine (Hazards in Motion). A separate video (Hidden Scars) captures the story of a fatal rock burst through an interview with a miner who nearly died and who lost his partner in the accident. These videos have been extremely popular in the mining industry and are being used across the nation as well as in 18 other countries. Two of them, Rock Falls and Miner Mike Saves the Day, have won Alice Hamilton awards, NIOSH’s highest recognition for Excellence in Occupational Safety and Health, in the Educational Materials category. Approach A recently completed independent evaluation of the SRL mining videos identified five themes that mine safety trainers consider necessary for successful training materials: high quality, credibility, accurate content, effectiveness, and an engaging nature. All of the NIOSH videos were rated very high for each theme. Using these measures of effectiveness, a more difficult challenge has been undertaken. Much has been written in the mining industry about the coming turnover in employment. The average age of miners in the United States is approaching 50, and many of the “experts” will be leaving the industry as they reach retirement age. The mining industry, like many industries involving skilled labor, relies heavily on a master-apprentice relationship between new hires and older miners. New hands learn from experienced miners. Their learning falls into three primary categories—they learn what’s important to know, they learn how to do things correctly and safely, and they learn the culture.

Mar 1, 2002

By Pedro Lilienfeld

This report presents a design and cost investigation for several alternative versions of a field-worthy mining machine-mounted respirable dust monitor. Three main design variations are considered: (a) light scattering sensing, (b) Beta-filter tape sensing, and (c) a combination of the two preceeding methods. Eventual instrument production coats as a function of design complexity are tabulated. Cost estimates for the development and field testing of field-worthy prototypes are also presented. A general discussion on the technical aspects of these design alternatives is included following a modular-hierarchical approach of progressive complexity. The technical background to this report has been provided by the experience and results derived from the work performed under U.S. Bureau of Mines Contracts Nos. H0166097 and H0377092.

Jan 1, 1980

By Stephen A. Swan

This Bureau of Mines report discusses research to analyze and evaluate extended bumper systems in order to determine the degree of protection provided to equipment operators in the event of rear-end collisions be-tween off-road rear-dump haulage trucks. The basic characteristics of rear-end collisions were determined, and a detailed analysis of the col-lision dynamics was performed to identify the magnitude and direction of impact loads, the amount of energy that must be absorbed during impact, and the major factors that affect the outcome of a collision. Separate bumper designs were developed to facilitate attachment to four 170-st-capacity haulage truck frame types.

Jan 1, 1987

By Walter L. Finlay

The Bureau of Mines has developed prototype instruments promising to improve the ability to warn of imminent roof falls. An unusually good opportunity to test these comparatively under natural caving conditions was afforded by the forecasted caving in August 1977 of a mined-out region of the White Pine Mine. The latter's rock strata closely resemble those in many coal mines. The anticipated cave was of the competent-roof/weak-pillar type. It occurred as, and when, predicted. Automated convergence and bed separation gages agreed well with the standard manual convergence gage measurements. A micro seismic gage was found to be insensitive to the fall and may require different test conditions for effectiveness. A roof resistivity unit was tested under a separate Bureau of Mines contract. (No. H02720J7). An unplanned addition showed interesting potential.

Jan 1, 1978

By Gary M. Larwood

A study was conducted to determine the amount of transportation equipment required to move 1.2 billion tons of coal in 1985. The Federal Bureau of Mines has investigated a majority of the various practices associated with coal transportation and has gathered information on the regional origin-destination patterns, methods of movement, equipment stocks, rate structures, and operational capacities of the most important modes of coal haulage currently in use. Models employing this information were developed to establish the origin-destination pattern for 1985 coal shipments, estimate practical tonnage capacities for selected coal hauling rivers, develop modal shares for both unconstrained (by river capacity) and constrained cases, and present a range of coal transportation equipment requirements for given sets of constraints. Projected transportation shares for rail ranged from 63.7 to 72.3 percent, and for river, from 8.8 to 16.4 percent. Other coal transportation modes (truck, conveyor, Great Lakes, and tidewater) are expected to retain their historic shares of coal traffic. Equipment estimates were made for 1985 rail and water transportation based on 1973 average and best practice. Average practice estimates ranged from 675,000 to 710,000 hopper cars (100-ton) and 3,100 to 5,940 barges (1,400-ton equivalent). Best practice estimates ranged from 126,000 to 142,000 hopper cars and 1,750 to 3,450 barges. Full implementation of 1973 best practice by 1985 is unlikely.

Jan 1, 1976

By D. E. Van Dillen

Three-dimensional structural analyses of three instrumented areas of a deep, longwall coal mine have been performed using the finite element code BMINES. The three Instrumented areas include two single-entry portions and one double-entry portion of the Sunnyside No. 1 Mine, Sunnyside, Utah. The finite element models simulated the sequence of excavation in each test area: the advance of the entry, installation of structural supports, retreat of the longwall, caving behind the longwall, and accumulation and loading of the gob. The structural supports considered in these finite element models include rock bolts, wood cribs, concrete cribs, steel arch sets, and chocks. Mechanical simulation of the geologic environment is achieved through elastic/ perfectly plastic material models employing anisotropy to represent finely layered regions of the medium. The results of these calculations are com-pared with the instrumentation readings from the mine. These measurements include closures, crib loads, rock-bolt forces, and stress growth.

Jan 1, 1978

By Kenneth Eilerts, Vincent Smith

"INTRODUCTION Knowledge of the Phase relations of fluids produced from combination wells 4/ at the pressures and temperatures characteristic of production from natural reservoirs is essential to efficient recovery and refining practice. An accurate sample of the fluid from such wells may be prepared by mixing (in the proportions of the measured gas:liquid ratio) gas and liquid taken from the separator conditions of steady flow; and physical properties of the sample, at significant pressures and temperatures, may be determined with suitable laboratory apparatus for use in the solution of engineering problems. The results of study of sample so obtained and of mixtures of gas and liquid from the separator combined in other proportions are presented in this report. Attention was given in the study to the relationship between the physical properties of what may be regarded as the constituent materials - the gas and liquid taken from the separator - and the properties of mixtures of these constituents. Data obtained for the complete range of mixture Proportions are expected to provide a reference scale for the study of other combination-well fluids produced at different liquid:gas ratios."

Apr 1, 1942

Mineral production was of little significance in the country's economy, and Bangladesh was not a world-ranked producer of any mineral commodity during 1977. Natural gas was the most important mineral exploited; however, reserves were sufficient to allow for much greater production, Economically, Bangladesh made some progress in 1977-782 in its struggle against poverty, underdevelopment, and rapidly increasing population. The gross domestic product (GDP) grew 8%, mainly owing to a 13% increase in food grain production, the key economic indicator in this highly agricultural nation. GDP at current prices dropped slightly in Fiscal Year (FY) 1976.77 to $6.6 billion3 and rose to $7.2 billion in FY 1977.78. The population rose from 81 million in FY 1975-76 to about 85 million in FY 1977-78, resulting in an increase of per capita GDP from $83 to $85 during the same period. The high annual population growth rate, over 3% in 1976 and about 2.8% in 1977, was recognized by the Government as the main problem facing the country. Average density was 525 people per square kilometer. A similar density would have the entire world population living within the continental United States.

Jan 1, 1981

This report provides the results of an industrial engineering study that assessed the safety and efficiency of underground ore handling in U.S. metal mines. One of the primary findings of the study was the improvement needed in controlling muck size in the ore handling stream. Oversize ore causes much additional labor, creating work stoppages and is a principal cause of accidents in metal mines. This report includes data on block caving, back cut and fill room and pillar, shrinkage stoping, and sublevel stoping.

Jan 1, 1974

[Determine how subsidence resulting from underground coal mining affects surface structures, and evaluate the usefulness s of the tiltmeter for monitoring foundation movement. Approach The Bureau of Mines is studying foundation response to mine subsidence in order to determine how subsidence-induced ground movements affect foundations in place directly above the mint. These investigations are essential if economic mitigation and repair techniques are to be made. In addition, commercially available tiltmeter are being evaluated (or use as a cost-effective monitoring technique. To study foundation response and to evaluate the tiltmeter system, full-scale model foundations were constructed, instrumented, and monitored for three years. Vertical and horizontal displacements, tilt magnitudes and directions, and observed damages were recorded. Displacements were compared with measured lilt to determine if the tiltmeter was tracking foundation response to subsidence, The Bureau developed a computer software package to aid in the reduction and analysis of the tiltmeter data.]

Jan 1, 1988