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By C. E. Jordan

Domestic cobalt resources are relatively large, but low grade. The full potential for cobalt production from domestic sources is at least 19.4 million lb of cobalt per year exclusive of offshore resources. A summary of the cobalt processing technologies for the major domestic resources is presented in this Bureau of Mines report. The processing technologies for the Blackbird, Madison Nine, Duluth Gabbro, iron ore pyrite, laterites, and manganese sea nodules are nearly complete, but the economics are not favorable. Research on these resources should be limited to approaches that promise to cut the total processing costs by at least 50 pct. The most promising sources of cobalt are the spent copper leach solutions and siegenite from the Missouri lead ores. Research on cobalt processing from these two sources needs to be completed.

Jan 1, 1988

Provide the mining industry with a method for determining the gas content of ore bodies and associated strata for use in mine planning, Approach Samples of various rock types are collected and tested to determine gas content in conjunction with sample size, the collection method (i.e. whether the sample was collected from a core sample or by hand) mine gas emission, and the geologic location from which the sample was taken, such as near a fault, outburst area, or other geologic anomaly. How It Works Two methods were developed by the Bureau of Mines to determine the gas contents of rock samples. The first method developed involved dissolving minerals to measure gas emission. This method, however, can only be used with soluble minerals. A second method, therefore, was developed for use with insoluble minerals. With this method, the sample is crushed in a ball mill. Although the dissolution method is faster and more accurate to use, the crushing method is also advantageous because its use can more closely approximate a mining situation; the sample is crushed as in mining and the amount of gas released relates to the amount of gas that would be released during a mining operation. The dissolution method is applied to soluble minerals, such as rock, salt, or trona, in a sealed chamber. Gases released during dissolution are collected for analysis by gas chromatography. One advantage in using the dissolution method is that the test apparatus is relatively inexpensive. In addition, test can be performed at any scale, from single crystal samples to a solution mining operation.

Jan 1, 1983

Enhance the critical skill of hazard recognition among miners by providing quality training that can help jot performance and lead to a higher degree of safety in the workplace. Background In mining, as in many other occupations, the safety of the worker depends on his or her ability to recognize hazards in the workplace. Some of the information needed by the miner for recognizing potential areas of danger is available in the form of visual cues found throughout the mine. One aspect of the dynamic mine environment it which the task of hazard recognition is critical for al workers is that of ground control. Regardless of job responsibilities, every worker is continuously exposed to roof rib, and floor hazards. Fatality injury data for the "underground coal" segment of the mining industry continue to show that about half of all fatalities are due to falls of ground each year. It is hypothesized that some of these accident, can be prevented if miners are better able to recognize visual cues that forewarn of potential roof and rib problems.

Jan 1, 1992

By Basil Dimitriades

Five recently developed methods for determining nitrogen oxides in automotive exhausts have been evaluated from the standpoint of accuracy and applicability in current exhaust studies. Results showed that methods requiring conversion of nitric oxide to nitrogen dioxide as a part of the analytical procedure are subject to errors introduced by the instability of NO2. The extent of some of these errors has been determined and procedures have been developed to minimize undesirable influences. On the basis of the results obtained from this study, recommendations are made regarding procedures for batch type or continuous measurement of nitrogen oxides in exhaust streams.

Jan 1, 1968

By M. D. Schlesinger

As part of the development of processes for producing synthetic fuels from coal, the Bureau of Mines prepared a special jet fuel in a pilot plant for evaluation by the Air Force. This jet fuel had all the required physical properties, including the important specifications of high heating value and high density. However, the finished fuel did not pass the stability test specified by the Air Force and conducted by the Southwest Research Institute in a high-temperature research coker. The cause for this instability is being investigated because pure compounds of the type identified in this fuel are known to be stable. The tar acid oil used was a 230° to 300° C. fraction of low-temperature tar obtained by carbonization of a West Virginia bituminous coal in the pilot plant of the Consolidation Coal Co. Both the desulfurization at 400° C. and saturation at 300" C. were done in the vapor phase at 2,500 p.s.i.g. After catalytic treatment and distillation the final jet fuel had a boiling range of 194° to 247° C., a net heating value of 18,420 B.t.u./lb. and a specific gravity of 0.8463 60° F./60° F. It also had u pour point below -62° C., and at 0° C. its viscosity was 4.5 cs. The oil was virtually all bicyclic, 41 pct. noncondensed and 56 pct. condensed.

Jan 1, 1961

By Frederick C. Trutt, Jeffery L. Kohler, Joseph Sottile

Condition-based maintenance (CBM) of industrial equipment is generally recognized as being the most cost-effective means for improving equipment availability. However, prerequisite to successful implementation of CBM is a reliable detector of failing components. One such detector, termed the effective negative-sequence impedance, had previously been identified as an indicator of induction motor stator winding degradation. However, a limitation of this detector is that it does not change in a predicable manner under certain motor operating conditions. This paper presents an experimental investigation of an improved technique for on-line detection of induction motor stator winding degradation. The paper begins with a brief description of the detectors, followed by a detailed description of the experimental setup, the experiments conducted, and results.

Develop a means for analyzing seismic crosshole data to predict and monitor the Flow of leach solution during in situ mining. Background Improvements in predicting and monitoring in situ leach solution flow would aid in planning well field configurations. These improvements would also facilitate permit application by assuring regulatory agencies that leach solution would not escape from a well field undetected. Seismic tomography can detect fractured zones, which enables the prediction of probable flow paths, and it is a promising technique for monitoring leach solution injected above the water table. Tomographic analysis of crosshole seismic data provides a two-dimensional picture of the distribution of seismic velocities between the transmitter and receiver boreholes. The positions of fractured zones and of leach solution can then be inferred from the seismic velocities.

Jan 1, 1989

By D. B. Dow

This report on methods employed for dehydrating oil-field emulsions, is the second of a series prepared as a result of a study of oil-field emulsions recently completed by the writer. The first paper2 dealt with the factors responsible for the formation of emulsions. A third paper will discuss the physical chemistry involved in the formation and resolution of such emulsions. In the early development of the oil fields of Pennsylvania, no emulsion troubles of any consequence were encountered, nor to any serious extent in the oil fields of other Eastern States: However, with the development of fields west of the Mississippi in Oklahoma, Kansas, Texas and California, where heavier oils of different characteristics were found, the problem of dealing with cut oil soon became of great importance.

Jan 1, 1925

Reduce workers' dust exposure by capturing airborne coal and quartz dust generated by a continuous mining machine. Approach Install a water-powered scrubber system operating at 1,000 psi on the boom of a continuous miner at the conveyor throat. Dusty air from the face area is drawn through the scrubber and cleaned air discharged into the return. How it Works Most coal mines use exhaust face ventilation to send fresh air over the miner operator and contaminated air behind the line curtain to the return. The problem with exhaust ventilation is that the line curtain should be within 10 ft of the face for maximum effectiveness. If the line curtain is not extended properly, or water sprays for dust control are poorly installed, dust rolls back towards the operator. An effective way of removing this dust is with a scrubber mounted on the mining machine.

Jan 1, 1988

Improve the safety and reduce the cost of longwall entry support. Approach Replace the conventional wood cribbing with stronger, non-rotting and lower cost cribbing made of steel-fiber-reinforced (SFR) concrete. How It Works Conventional concrete can suddenly fail under excessive compression loads, but adding steel fibers to the concrete, before it is mixed with water, changes the failure mode to a gradual and controlled failure characteristic similar to wood. A system for making SFR concrete crib blocks was designed and developed (or use in constructing walls and cribs to support coal mine roofs. The SFR concrete cribbing is stronger and stiffer than wood, and avoids wood's disadvantages of: flammability, deterioration under chemical or bacteriological attack, methane generation, and relatively high cost. Use of SFR concrete also allows freer movement of miners, equipment, and ventilation air, because much less volume of SFR concrete is required than wood for a given amount of support, and because the roof-to-floor closure is greatly reduced by the stiffer supports.

Jan 1, 1981

By John J. Sammarco

As part of a project to automate coal extraction, computer control of a continuous mining machine test bed has been developed and tested by the Bureau of Mines. A computer system and control software were developed for accurate positioning of the conveyor elevation and swing, stabilizer jack, gathering head, and shear elevation. Tramming actions are also controlled by the computer. The computer system was designed to access data from sensors installed on a continuous miner and to interface with the existing control circuits of the miner. Testing in free space was used to characterize the operation of the machine. From this information, control algorithms were written and stored in the computer. The ability to control each function of the continuous miner with a high degree of accuracy and stability was successfully demonstrated in a series of tests in free space and in mining a block of simulated coal. In the mining of simulated coal, the cutting drum was instructed to position the shearer at the top of the block and shear down to the bottom under closed loop control. The cutting drum came within 0.27 in of the top and within 0.49 in of the bottom of the block for this shearing test.

Jan 1, 1988

By W. R. Reed

A computer model named the "Dynamic Component Program" (DCP) was specifically designed for predicting the dispersion off dust from haul trucks at surface mines. Validation of the DCP was completed by comparing its results with the results of the 1SC3 model and with actual dust measurements taken front two operating mine sires. Comparisons of the field measurements, predictions of the ISC3 model and the predictions of the DCP demonstrate that the results from the DCP represent, on average, an 85% improvement truer the ISC3 dust dispersion model results.

Jan 1, 2008

To more rapidly and economically prepare solutions for chemical analysis, of a wide range of ores, slags, minerals, and metals. Approach A Simple pressure-dissolution system was devised using an inexpensive, heavy wall plastic bottle containing a sample in an acid medium. Using the technique, a complex silicate sample can be dissolved in less than 1 hour. How It Works A weighed portion of a sample, ground to minus 100-mesh, is placed into a polycarbonate or polysulfone plastic bottle. A mixture of hydrochloric acid, nitric acid, and hydrofluoric acid then is added. The bottle threads are wrapped with a layer of Teflon tape to prevent leakage, and the bottle cap is screwed on tightly. The sealed bottle is placed in a balling water bath. In the hot water, the plastic bottle acts as a pressure vessel to contain the pressure generated inside it. This technique should only be used by trained experienced people who are familiar with the hazards of hot acids under pressure. After being cooled in cold water, the resulting solution is brought to the final volume by adding 1.5 weight-percent boric acid solution to the bottle. The cap is replaced, and the bottle and solution is reheated. Precipitated fluorides, as well as any residue, are dissolved by the fluoride-boric acid reaction. The resulting clear solution then is suitable for spectro-photometric examination or other analysis.

Jan 1, 1980

By M. E. Tyrrell

Work in this investigation was undertaken by the Bureau of Mines to demonstrate how waste glass might be utilized to lower the required firing temperature and firing time of structural clay products. Mixtures of waste glass and common clays were formed by stiff-mud extrusion and fired to the temperature required to produce a body having 6 to 7 percent absorption. Substitution of glass for one-half of the clay in a red body reduced the firing temperature 500° F, which made possible a 30-percent increase in production; in a tan body, the firing temperature was reduced 400° F, which made possible a 23-percent increase in production.

Jan 1, 1972

By J. D. Dixon

The Bureau of Mines has developed structural design data for unreinforced concrete tunnel linings in the form of stress and deflection coefficients from which bending, axial, shear, and boundary stresses, moments, thrusts, and shear forces, and structural deflections can be determined at any point on the lining. Results were obtained by structural analyses of nine concrete-lined tunnel configurations subjected to 22 biaxial load conditions. The tunnel configurations include three basic shapes, circular, rectangular, and horse-shoe, with dimensions based on designs evolved by the mining industry. These analyses were made by the direct stiffness matrix method, a computer-oriented procedure. Numerical results agree closely with those obtained experimentally.

Jan 1, 1969

By F. C. Turin, K. M. Cornelius

1. INTRODUCTION Underground mining in the USA has undergone significant change in the past 20 years. Two key elements have been increased mechanization and a more educated work force in spite of these changes, many jobs continue to be labor-intensive and repetitive in nature. They entail tasks that, performed over time, can take a toll on the soft tissues and joints. The problem may be compounded by an aging mining workforce. In 1996 the mean age of the coal mining work force was 45 years and the median total years of experience was 20 (NMA 1998). As a person ages, the body resilience to chronic wear and. tear is reduced, which may cause a worker to pay an increasingly higher health price for performing the same task. Mining companies, like many others, are becoming more aware of cumulative effects to the worker as reports of these types of injuries rise. . Conducting a job analysis is an important step when considering a job redesign or modification to reduce worker cumulative trauma exposure. A basic approach to job analysis is to examine the types of aches and pains reported, the tasks performed, and work site conditions. The US Bureau of Mines (USBM) conducted an evaluation of roof-bolting tasks performed at an underground coal mine concerned about early warning signs of cumulative trauma. This evaluation will comprise the primary focus of this chapter. The approach used for the roof-bolting race study may be applicable to other work environments. 2. FUNDAMENTALS OF CUMULATIVE TRAUMA EXPOSURE Musculoskeletal injury is a term used to describe a wide range of soft tissue disorders that affect the nerves, tendons and muscles. Common examples include lower back pain, tendinitis and carpal tunnel syndrome. The majority of these injuries are not the result of sudden mishaps, but usually develop gradually from repeated wear and tear. Symptoms may not appear immediately, but can take weeks, months or even years. Symptoms may result from many types of activities, performed at work or at home, and it is often difficult to attribute there to a single event. In fact, it is more common to identify factors that may have contributed to the development of the condition. The terms repetitive strain injuries or cumulative trauma disorders (CTD) have been commonly used to refer to disorders that have occurred due to work-related activities. Three main risk factors contribute to CTD: force, repetition and awkward postures. Any one or combination of these may contribute to the development of CTD. Therefore, the design of equipment in conjunction with the required tasks should be evaluated when attempting to reduce these risk factors. Examining the layout of the work area to help identify tasks which may contribute to cumulative trauma is necessary. The following list (Putz-Anderson 1988), describes ergonomics concerns that, overall, should be minimized at the work area: • Crowding or cramping the worker: a work area layout may unnecessarily constrain movements of the worker. • Twisting or turning: placement of tools and materials may require the worker to twist the spine to fulfill the requirements of the job. • Repeated reaching motions: the layout of the work area may require the worker to lean to reach and grasp the necessary tools and controls. • Misalignment of body parts: the arrangement of the work area may require the worker to frequently have one shoulder higher than the other or have the neck or spine bent to one side. While many of these concerns are a function of equipment design and environmental conditions, making workers aware of these issues may help them to adapt their work habits to reduce risk of injury. Additionally, this information is useful when conducting an ergonomic evaluation of a work area and associated tasks. 3. UNDERGROUND MINING ENVIRONMENT The underground mining environment is a unique challenge. It is more difficult to develop controls for an underground mine site as compared with a factory setting where equipment and facilities can be more easily designed to reduce worker force, posture and repetitive exposures. In an underground mine, workers are required to perform labor-intensive tasks that often cannot be avoided due to environment constraints. The dynamic nature of the environment does not allow easy implementation of mechanical assists to reduce force exposure. Many of the tasks performed by workers are repetitive. Restrictive work areas due to low ceiling height, low lighting levels and large pieces of equipment cause workers to perform these tasks in postures that are not desirable. Designers of underground mining equipment can control how a machine will function, but not the environment in which it will be used, Hazards in an underground mine cannot be completely removed by redesigning the system. There are many hazards and information sources that must be continually monitored by workers including their position in relation to large pieces of mobile equipment and unpredictable geological anomalies. Thus, immediate dangers may take priority over awareness of ergonomic considerations while performing a job. 4. CASE STUDY OF UNDERGROUND ROOF BOLTING 4.1. Roof Bolting and Cumulative Trauma Exposure In an underground coalmine, after an area is mined it is necessary to support the roof to keep it from collapsing. Since 1950, the primary method for supporting the mine roof has been installation of roof bolts. Long bolts installed into the roof compress the layers of strata achieving a uniformly distributed support anchorage. Roof bolts, typically 6-8 feet long, are installed by workers using large roof-bolting machines. There are different types of machines

To restore ventilation and prevent the accumulation of explosive or toxic gases by quickly installing substitutes for stoppings blown down by an explosion. Approach Temporarily replace blown down stoppings with a parachute-shaped brattice which can be erected in minutes. How It Works The self-sealing brattice is secured to the roof, ribs and floor by anchoring its nylon edge strip at several points using extensible poles, shads, or available projections such as roof bolts. The air pressure in the entry pops open the chute of lightweight sailcloth, forcing it tightly against floor, roof and rib. See Figure 1. This emergency brattice has been tested at two locations in the Bureau's Experimental Mine at Bruceton, Pennsylvania. In a test last December, one MESA inspector wearing full rescue apparel (including self contained breathing apparatus) installed a self sealing brattice in an entry at the Bruceton Mine. Although he did not have any previous experience with the device, he easily erected it in slightly less than 10 minutes, using two extensible supports (pogo sticks). Research to improve and refine the self-sealing brattice is continuing.

Jan 1, 1977

By S. A. Ferguson

Purpose: Marras et al. developed a technique to evaluate sincerity of effort during dynamic trunk motion performance. The validity and reliability of the technique have not been evaluated. Therefore, the objective of this study was to first determine whether or not a sincerity of effort measure correctly identified those giving a sincere effort in a blinded randomized control trial and second to quantify inter-rater and test-retest reliability. Methods: This article reports the findings of a two phase study. In phase one, the blinded evaluation, participants were randomly assigned to either a sincere or insincere performance condition. An examiner tested participants without knowledge of the participant's group membership. In the second phase, two examiners evaluated each participant twice to quantify inter-rater and test-retest reliability. Results: In the blinded phase the specificity was 100% and sensitivity was 90% for identifying sincere and insincere effort, respectively. Phase two results showed no significant difference in probability of sincere effort between raters or between testing sessions. Conclusion: A performance criterion that accurately identifies sincere vs insincere group membership during functional evaluations was identified. There were no significant differences between raters or between testing sessions. These findings indicate that this test is reliable and possesses good predictive validity in assessing sincerity of effort.

Jan 1, 2003

Provide a means of evaluating the in place structural properties of coal seams and coal measure rocks in advance of mining. Approach Develop a sonic logging probe for use in dry wells, a condition common to shallow wells and semi-arid coal regions. How It Works The Bureaus' sonic probe differs from conventional sonic probes because it does not require fluid in the well to couple sonic vibrations to the drill hole wall. A self-contained hydraulic system forces pistons containing the measurement transducers against the wall and clamps them in position until the sonic waveform information has been recorded. The pistons are then retracted and the probe is raised or lowered in the well as required. In the clamped position, the piezoceramic transmitter emits a sonic pulse which travels along the drill hole wall and is detected at the receivers in the form of compressional (P) and shear (S) wave motion. The receivers are designed to be sensitive to either the (P) wave or (S) wave motion as determined by the operator so that discrimination between the two wave types is improved by comparison of the respective output channels, and the travel time between transmitter and detectors can be accurately determined. Use of two receiver stations eliminates errors in timing of pulse travel because of electronic delays inherent in the probe.

Jan 1, 1981

By Horace M. Lawrence, Edmund S. Leaver

"The sulphidizing filming of minerals in oxide ores as a preliminary treatment to aid their recovery by flotation is known practice. In this work the use of barium polysulphide does not appear to have been considered. A study of the properties of barium lead to the following comparative investigation of the sulphides and polysulphides of the alkaline and alkaline-earth metals. It is thought that barium polysulphide may prove to be a more satisfactory sulphidizing reagent than others now in use under conditions that favor the cheaper barium reagent.For the investigation two fairly typical oxidized ores of copper and lead were selected. The copper ore came from the Big Indian Mine in southeastern Utah, and assayed 3.8% Cu; the copper was present in a sandstone gangue mainly as the carbonates, malachite and azurite, with less than 0.2% as sulphides, or silicate. The lead ore is from the Tintic Standard mine in the Tintic district, Utah. It is typical of the oxidized lead-silver ores of that district; the lead is present in an oxidised form in a siliceous gangue, much: Uncolored by ferric oxide. The sample assayed 5.15% Pb and 11.3 oz. Ag.In addition to the results obtained in this investigation, there are included some results secured by Mr. J. B. Lain, consulting metallurgist of Reno, Nevada, on a sample of ore from the Chino Copper Co. The ore assayed about 1.7% Cu, of which about 0.25% was nonsuiphide."

Aug 1, 1925