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By G. F. Friel, J. C. Edwards

A series of seven underground-coal-mine fire experiments was conducted in the Safety Re-search Coal Mine at the National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory. Coal and styrene-butadiene-rubber conveyor belting were burned upwind of two sensor stations, 18 m and 148 m from the fire source. Exhaust from a diesel locomotive flowed over the fire sources in six of the tests. Metal-oxide-semiconductor (MOS), CO, and optical-path-smoke sensors were positioned at both stations and found to be an optimum set of sensors for the fire discriminations. A representative set of 7,679 samples of CO data and data from the smoke and diesel-exhaust MOS sensors were used as inputs to train a neural network (NN). By testing 42,538 data samples from the seven experiments, all fires were detected by the NN within 9.67 min from the onset of significant changes in the MOS voltages without any false alarms.

By A. W. Frolli

This paper, describing the open-cut mining milling, and cyaniding methods and costs at the Yellow Aster gold mine, is one of a series being prepared by the Bureau of Mines on similar practices in the United States. It is presented primarily to show methods and costs of mining and treating low-grade gold ore on a large scale.

Jan 1, 1940

By Keith S. Olson

During 1982 and 1983, the Bureau of Mines concentrated its fugitive dust control research on haulage road dust suppression by newer chemi-cals relatively unknown in the mineral industry, innovative dust control designs for haulage trucks, chemical tailing basin stabilization, and combined chemical and vegetation tailing basin stabilization. Relatively unknown dust suppression chemicals and innovative aerodynamic modifications to haulage truck fender designs were tested on a Minnesota sand and gravel operation haulage road. Magnesium chloride salt at 95-pct control efficiency and a petroleum derivative at 70-pct control efficiency were effective in suppressing dust generated by haulage vehicles; however, none of the fender modifications were successful. Commonly used dust suppressant chemicals were tested on a Minnesota taconite tailing basin to reduce the dust lift-off during the spring and fall dry seasons. The most successful chemical was lignin sulfonate with a seasonal cost of less than $200 per acre to achieve 90-pct dust control. When chemical treatments for immediate dust control were com-bined with revegetation for permanent control, the most promising chemical treatment based on vegetation response was lime-neutralized lignin sulfonate.

Jan 1, 1987

By J. Chilton

The fact that methane ignitions continue to occur at the mining face indicates that monitoring with machine-mounted methanometers does not always indicate the presence of high methane concentrations. Methane concentrations at the face change quickly due to changes in airflow. By measuring these changes in airflow, it may be possible to predict changes in face methane levels more quickly. Currently there are no techniques or instruments to accurately measure airflow in by the mouth of the ventilation curtain or tubing. Tests conducted in the NIOSH ventilation test gallery compare the data provided by one-, two-, and three-axis ultrasonic anemometers. The effects of changes in airflow direction and turbulence on instrument readings are discussed, and guidelines are given for selecting the type of instruments to be used for monitoring airflow near the mining face.

By H. Kenworthy

"INTRODUCTION ..Although the occurrence of iron ore in Missouri was recognized by Marquette as early as 1673, the first known mining and smelting operation was conducted in 1815. This operation was near Arcadia, Iron County, the first of its kind west of the Mississippi-Ohio River system. Several small furnaces of short life were erected in Missouri in the ensuing 30 years. However, until the extensive deposits of Iron Mountain and Pilot Knob were opened between 1843 and 1850, the state remained a minor producer of iron. It was this district which was chiefly responsible for the prominent position Missouri held in the iron industry until the late 1880's. At this time the easily minable high-grade ores became exhausted and the discovery of the immense Lake Superior deposits depressed the raw-ore price to such an extent that any mines ceased to operate. 3/Small yearly production of iron ores continued in Missouri to the present. Owing to war demands for hard ore suitable for open-hearth steel, the M. A. Hanna Co., through its subsidiary, the Ozark Ore Co., reopened the Iron Mountain, deposits and installed new equipment in an old concentrator to handle the low-grade ores left from previous operations. At present, ore production is from open pits, but underground mining is contemplated in the future. About 2,000 tons a day of iron ore is treated by gravity concentration of material from the open pits in the immediate vicinity. The concentrate is shipped to the Birmingham, Ala., district and to Granite City, Ill., for smelting. The coarse tailing is sold for ballast and concrete aggregate. The iron requirements of the concentrate stipulated by the purchaser are not difficult to meet, but the phosphorus is frequently higher than desired. For 1946 the concentrates averaged 54.18 percent iron and 0.235 percent phosphorus with low sulfur. The Ozark Ore Co. concentrate, however, sometimes contains as much as 0.40 percent phosphorus. The phosphorus in ores from those portions of the deposits wherein the phosphorus occurs with siliceous gangue is readily rejected in the milling, but in much of the ore the phosphorus is associated with the iron and concentrated with the iron minerals. Selective mining is impossible owing to the spotty occurrence of the phosphorus mineral. Often within 5 feet the ore will change from low phosphorus to high phosphorus, and it would be expedient to find a method of rejecting enough phosphorus at the mill from the latter type of ore to meet the phosphorus specification."

Feb 1, 1948

By D. W. Blaylock

1. The Lower Freeport and Lower Kittanning beds are the most important beds in Clearfield County, Pa., from the standpoint of production. The Lower Kittanning bed has the largest remaining recoverable reserves of any of the beds in the county. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 short tons per acre-foot of coal in place, are estimated at 1,909 million short tons as of January 1, 1953. Of this total, 1,177 million short tons is in beds 28 inches and more thick. Areas in some beds were omitted from the estimate because available data relative to the bed characteristics are too meager to make an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1955

By Joseph W. Horne

This report presents the results of an investigation by the U. S. Bureau of Mines in cooperation with the State of Colorado, on the yields and properties of oils produced from oil shale, lignite and subbituminous coal using the standard assay method developed by the Bureau for oil-shale testing,. The purpose of this work, which is part of the general study of oil shales being conducted by the Bureau of Mines and cooperating agencies, was to obtain information on the amount and character of the yield of crude oil or tar from different typical oil shales, the yield of light oil or naptha that might be suitable for use in motor fuels, and other products of shale oil. As the west has large resources both of oil shale and low-grade non-coking coals, it is of interest to know the relative yields of tars, light oils, and combustible gases that can be produced from these coals when retorted under conditions similar to those suited for oil-shale retorting. Source of Samples The coal samples were obtained from deposits on or adjacent to the public lands in the States of the Rocky Mountain region. Many of the mines sampled are operating under Government leases or permits. The number of coal samples secured from the various states are: Colorado, 6; Montana, 9; north Dakota, 6; New Mexico. 1; South Dakota, 1; Wyoming, 9. Of these samples, 14 were lignite coal, 16 subbituminous coal, and a bituminous coal. The standard channel method of the Bureau of Mines was used for sampling. Coal samples received at the Boulder Office weighed about twelve pounds each, and duplicate samples were sent to the Pittsburgh Station for proximate and ultimate analyses. The origin of the samples and description of the deposits are given in Table 1.

Jan 1, 1927

A new personal respirable dust monitor developed by Rupprecht & Patashnick Co., Inc. in a multi-year project funded by the National Institute for Occupational Safety and Health (NIOSH) generated promising results in underground coal mine testing performed by NIOSH and industry representatives during the summer of 2003. The mine data showed that the personal dust monitor (PDM) performed similarly to co-located manual reference samplers for full-shift samples at all four underground coal mines at which the evaluation took place. The technology that forms the heart of the PDM, called the tapered element oscillating microbalance (TEOM system), is unique in its ability to collect suspended particles on a filter while simultaneously determining the accumulated mass with National Institute of Standards and Technology traceability. Because the monitor measures the true particle mass collected on its filter, its results do not exhibit the same sensitivity to water spray as do optically based measurement approaches. The technique achieves microgram-level mass resolution even in the hostile mine environment, and reports dust loading data on a continuous basis. Using the device, miners and mine operators have the ability to view both the cumulative and projected end-of-shift mass concentration values, as well as a short-term 15- or 30-minute running average. During underground mine trials in the summer of 2003, technical personnel used the readings from the PDM to identify and correct several abnormal dust generating scenarios. These events demonstrated the potential of the PDM to be used as an engineering tool to evaluate the effectiveness of various dust control strategies. In a separate evaluation performed by CONSOL Energy, Inc., the mine operator evaluated the benefit of a proposed new water spray-based dust control system. Engineers measured the dust concentration upstream and downstream of a production location under different dust control scenarios using two PDM units. By evaluating the change in the dust loading between the upstream and downstream monitoring sites, the company was able to determine in a few hours which hardware configuration would yield the greatest benefit to the workplace environment. BACKGROUND Measuring underground coal mine dust concentrations is an essential part of protecting miners' health. The U.S. Secretary of Labor and the Federal Advisory Committee on the Elimination of Pneumoconiosis among Coal Mine Workers has recommended that better monitoring of coal miner dust exposures be used as a method to improve miner health. In consultation with labor, industry, and government, NIOSH issued a contract to Rupprecht & Patashnick Co., Inc. (R&P), Albany, N.Y., to develop a one-piece PDM. The object was to miniaturize TEOM technology into a form suitable for a person-wearable monitor that would enable accurate end-of-shift dust exposure information to be available to miners. Furthermore, any person-wearable dust monitor should minimize the burden to the wearer by incorporating the monitor into the mine worker's cap lamp battery, with exposure data continually displayed during the shift to enable workers and management to react to changes in dust exposure. In the summer of 2003, NIOSH conducted extensive testing of the PDM to determine its laboratory and in mine performance. In addition, anecdotal information collected in the mines showed several occasions where miners were able to identify situations that produced high levels of respirable coal mine dust The PDM's response to unplanned changes resulted in action being taken to keep dust exposures as low as possible. In another case that demonstrated the PDM's versatility, a mine was seeking to find a better dust control solution on its longwall headgate stageloader. In this instance, the PDM was used as a diagnostic tool by the miners to quickly evaluate the control technology. [ ] HOW DOES THE PDM WORK? The PDM is configured to provide accurate respirable dust personal exposure information in a form that is as convenient to wear as a normal cap lamp (See Figure 1). Respirable dust exposure data displayed by the device has two main objectives: providing the miner and mine operator with timely values to avoid overexposure to dust, allowing them to make any necessary changes during the course of a work shift; and computing an accurate end-of-shift statistic for a miner's average respirable dust exposure. The mass sensor embedded in the PDM, holds the key to the accurate, time-resolved dust concentration measurements. The inertial, gravimetric-equivalent, mass measurement technique used in the device typically provides a limit of detection on par with that of the most sensitive laboratory-based microbalances.

By A. J. Kauffman

This study compiles data on the zircon resources of the Pacific Northwest States, Alaska, and California, to determine the productive capability of industrial concerns to make ductile zirconium and hafnium, and to investigate markets for the nonmetallic products of zircon. West coast zircon resources are large but mostly marginal to submarginal. Development of a stable and profitable zircon mining industry on the west coast will depend upon recovery and utilization of the other associated heavy minerals needed by regional and national markets. The west coast has the only completely integrated facility for processing zircon sand to reactor-grade zirconium and hafnium and for making fabricated products from these metals. The future of the zirconium metal industry appears to be good because of increased use of the metal for nuclear propulsion and power-generating plants.

Jan 1, 1965

By A. J. Kauffman

This study compiles data on the zircon resources of the Pacific Northwest States, Alaska, and California, to determine the productive capability of industrial concerns to make ductile zirconium and hafnium, and to investigate markets for the nonmetallic products of zircon. West coast zircon resources are large but mostly marginal to submarginal. Development of a stable and profitable zircon mining industry on the west coast will depend upon recovery and utilization of the other associated heavy minerals needed by regional and national markets. The west coast has the only completely integrated facility for processing zircon sand to reactor-grade zirconium and hafnium and for making fabricated products from these metals. The future of the zirconium metal industry appears to be good because of increased use of the metal for nuclear propulsion and power-generating plants.

Jan 1, 1965

By Paul M. Tyler

The outstanding trend in the graphite market is the fast-growing demand for cheaper qualities of graphite and the declining consumption of the more expensive varieties. The manufacture of graphite, crucibles for melting metals was one of the earliest applications of the-mineral and for many years constituted by far the leading source of demand. In later, years, however; and more especially since the Great War, the increasing demand for high-grade steel ingots and castings instead of enlarging crucible sales has permanently curtailed the domestic demand for crucibles because it has hastened the introduction of electric, oil or gas fired furnaces to replace the older types requiring pots to hold the metal during melting. While there has been a substantial increase in the use of graphite for miscellaneous refractories the total consumption for such purposes is too small to offset the shrinkage in demand for crucible making, and though it consumes the better and hence more expensive grades of crystalline flake graphite, it does not call so insistently for the still costlier Ceylon grades.

Jan 1, 1929

To improve the ventilation of large-opening under-ground stone mines by using stoppings made from stone left in place. Background Underground stone mines typically use large room-and-pillar openings with little ventilation control. Stone miners may be exposed to contaminants that include silica dust, diesel particulate matter (DPM), exhaust gases, nuisance dust, and face shot (blasting) fume gases. The health risks from breathing these fine particles and toxic organic materials are well documented. Although contaminants such as dust or diesel exhaust can be some-what controlled at the source, the escaping contaminants are often diluted and removed from work areas using ventilation with minimal controls. In many cases, current mine ventilation practices use trial-and-error techniques to improve ventilation. The growing realization of the importance of a healthy work environment along with increased regulations will require many stone mines to implement new ways to improve ventilation. In-place stone stoppings are one option. Mine air flows from one point to another because of a pressure differential between those points. This pressure differential is established using a mechanical fan in conjunction with separations (stoppings) between high-pressure (intake) and low-pressure (return) airways. The separation of intakes and returns is an important concept that is used in most other types of mines. Normally, air moves through underground stone mines with minimal control technology. Fans are placed in locations where they are thought to be most beneficial, and intakes are not separated from returns. In a few smaller underground stone mines, proper ventilation can be achieved with a few strategically placed fans. However, as these mines increase in size, moving adequate quantities of air through-out the mine becomes harder, and separation of intakes and returns becomes a problem. Building traditional mine stoppings to separate the intake and return airways in entries with a cross-section area often exceeding 800 ft2 is difficult. The stoppings must be able to withstand both the dynamic pressure from face shots and the static pressures created by the fans. Construction and maintenance difficulties, as well as high costs, are the main factors preventing these traditional mine stoppings from gaining wide acceptance by the stone mining industry.

Dec 1, 2002

By Gerrit V. R. Goodman

A laboratory study assessed the impacts of water spray pressure, face ventilation quantity, and line brattice setback distance on respirable dust and SF6 tracer gas concentrations around a continuous mining machine using a sprayfan or directional spray system. Dust levels were measured at locations representing the mining machine operator and the standard and off-standard shuttle car operators, and in the return airway. The results showed that changes in all three independent variables significantly affected log-transformed dust levels at the three operator sampling locations. Changes in setback distance impacted return airway dust levels. Laboratory testing also identified numerous variable interactions affecting dust levels. Tracer gas levels were measured on the left and right sides of the cutting drum and in the return. Untransformed gas levels around the cutting drum were significantly affected by changes in water pressure, face ventilation quantity, and setback distance. Only a few interactions were identified that significantly affected these concentrations. Gas levels in the return airway were grouped by face ventilation quantity. Return gas levels measured at the low curtain quantity were generally unaffected by changes in water pressure or curtain setback distance. At the high curtain quantity, return airway gas levels were affected by curtain setback distance. A field study was conducted to assess the impact of these parameters in an actual mining operation. These data showed that respirable dust levels may have been impacted by a change in water pressure and, to a lesser extent, by an increase in curtain setback distance. A series of tracer gas pulse tests were also conducted during this study. The results showed that effectiveness of the face ventilation was impacted by changes in curtain flow quantity and setback distance. Laboratory testing supported similar conclusions.

Jan 1, 2004

By Jon A. Hummer, Emanuele Cauda, George H. Schnakenberg, Aleksandar D. Bugarski, Samuel J. Janisko, Larry D. Patts

A series of engine/dynamometer tests was conducted to assess the effects of three types of uncatalyzed diesel particulate filters (DPFs), a diesel oxidation catalytic converter (DOC) and three types of high temperature disposable filter elements (HT DFEs) on the concentrations and size distribution of diesel aerosols and concentration of nitric oxides in underground mine air. Tests were conducted in the NIOSH Diesel Laboratory at the Lake Lynn Laboratory experimental mine, a facility developed to allow evaluation of these and other control technologies directly in an underground environment. The aforementioned technologies are evaluated by comparing the aerosol and gas measurements in the mine air 60 m downstream of the exhaust from a naturally aspirated, mechanically controlled engine fitted with the tested systems or muffler and operated at four steady-state engine speed and power modes. The tested DPF and HT DFE systems caused a 10-fold reduction in total mass concentrations of aerosols. The size distribution and number concentration measurements showed that all tested DPF systems and HT DFE elements effectively removed accumulation mode aerosols (D50>30 nm) for all test modes. An increase in peak number concentrations of nucleation mode (D50>30 nm) diesel aerosols is evident for some of tested DPF systems when engine was operated at high-load modes. The effects of uncatalyzed DPFs on nitric oxide (NO) and nitrogen dioxide (NO2) concentrations are found to be minor. A four-fold increase in percentages of NO2 in total nitrogen oxides (NOx) over baseline case was observed for the DOC when the engine was operated at high-load modes. The findings from this study should contribute to better understanding the potential for various control technologies to reduce exposure of underground miners to nano and ultrafine aerosols. In addition, detailed physical characterization of diesel aerosols made directly in occupational setting should foster a better understanding of the health risks associated with exposure to nano and ultrafine diesel aerosols.

By Michael Schmitz, John A. Organiscak

ABSTRACT: A method (patent pending) has been developed to determine the quality of environmental cab filtration systems. This method utilizes specially configured filter cartridges to remove carbon dioxide from the ambient air with the environmental cab’s air filtration system. A real-time gas monitor is placed inside an unoccupied cab with the filtration system running to time decay the carbon dioxide to its lowest concentration or equilibrium level. The outside carbon dioxide concentration level can be measured concurrently with another gas monitor or with the same inside cab gas monitor during a representative period before and after the inside sampling is conducted. Cab filtration system leakage is comparatively deduced from the difference between the special cartridge filter efficiency and overall cab efficiency. Laboratory trials have illustrated that desirable high efficiency test filter configurations (greater than 99 % efficiency) can be devised, but have air quantity and test time limitations. These trials also demonstrated that CO2 penetration was reflective of controlled air leaks around a high efficiency filter under equilibrium conditions. This report examines the elements of this patent pending method.

By E. R. Spencer, E. Reeves

National Institute for Occupational Safety and Health (NIOSH) researchers conducted an investigation to quantify sound levels and to determine the amount of sound reduction provided by engineering noise controls installed in a talc processing plant. Baseline sound level and sound intensity measurements were performed at the plant and the measurement locations were recorded for comparison to post-control measurements. Follow-up measurements were then made at the same locations after the initial noise controls were installed. The plant subsequently decided to implement additional noise controls and the researchers returned to conduct measurements for a final analysis of all noise controls. The most significant results showed a sound level reduction in the main mill area from a range of 93-104 dB(A) down to 90-94 dB(A), and a total sound power level reduction of 21 dB(A) for air classifying mill 3.

By Ellis S. Hertzog

The relatively large amount of phosphorous occurring in many iron ores limits their usefulness aid sometimes renders them valueless under present conditions of nip-iron manufacture. A practical method for removing the phosphorus would be valuable to the iron and steel industry. Gravity concentration has been of little value as far as the removal of phosphorous is concerned, because the compounds of this element are, as a rule, disseminated very finely. Removal of the phosphorous by leaching is not a new idea and has been the subject of some investigation,3,4/ out for data :lave been published. W.R. Crane published analyse of various ore bodies in the Birmingham ham district. The hard or unleached ores a .re much higher in phosphorous than the Soft, leached ores along the outcrops. This fact indicates that as mild a leaching agent as water removes phosphorus effectively if enough time is allowed for it to react. As the forms in which phosphorous occurs in the iron ores are important in the consideration of any leaching operation, much time was expended in devising a method for determining them. According to Professor McVey, University of Alabama, the phosphorous-bearing minerals in the red iron ores of Alabama have not been positively identified by any microscopic methods.

Jan 1, 1935

By Ellis S. Hertzog

[The relatively large amount of phosphorous occurring in many iron ores limits their usefulness mid sometimes renders them valueless under present conditions of pig-iron manufacture. A practical method for removing the phosphorus would be valuable to the iron and steel industry. Gravity concentration has been of little value as far as the removal it of phosphorous is concerned, because the compounds of this element are, as a rule, disseminated very finely. Removal of the phosphorous by leaching is not a new idea and has been the subject of some investigation,3,4/ but few data have been published. W. R. Crane published analyses of various ore bodies in the Birmingham district. The hard or unleached ores are much higher or in phosphorus than the soft, leached ores along the outcrops. Tips fact indicates that as mild a leaching agent as water removes phosphorus effectively if enough time is allowed for it to react.]

Jan 1, 1935

By Forrest T. Moyer

The safety record of the coal-mining industry, both anthracite and bituminous, in 1966 was improved over that of 1965 in all general measures of injury experience. The improvement was more pronounced in the anthracite industry. The total of 10,679 disabling work injuries comprised 233 fatal and 10,466 nonfatal injuries, 26 and 692 fewer, respectively, than in 1965. The number of fatalities in 1966 was the lowest annual total since complete records were started in 1910. Similarly, the number of nonfatal injuries in 1966 was lower than in any year since 1930 when such data were first collected.

Jan 1, 1969

By R. Karl Zipf, Kousick Biswas

The main objective of occupational health and safety research is to minimize or eliminate the events that may cause fatal or non-fatal injuries to human workers. A commonly used technique is to devise an “incident prevention plan”, which is more often the product of thorough investigations of past reported incident events. Incident documentation and methodical reporting and systematic and thorough data collection, often help identify the root cause of the incident – in other words, the etiology of the incident. These retrospective analyses of the incidents can efficiently identify the future steps to take to achieve the objective of minimizing occurrence of “events of interest”. This paper introduces a novel technique – “Taxonomic Analysis”, which identifies the root causes of an event (an incident in this case) and can provide future direction for corrective measures to reduce the probability of occurrence of the event. A taxonomic analysis involves systematic and organization of data based on observation, description, and classification. This paper utilizes the rock fall related incident narratives, available with the Mine Safety and Health Administration (MSHA) database (1984-1999), for a taxonomic analysis. The study found that 67.6% of groundfall incidents occurred in supported areas with the remainder (32.4%) in unsupported areas. Some form of rock mass failure appears to cause about 50% of groundfall incidents, although in 39.7% of the overall groundfall incidents or two-thirds of those involving rock mass failure, the exact nature of the rock mass failure could not be determined from the narratives. Human activities factors such as scaling or barring down, drilling or bolting, and setting timbers or cribbing accounted for another 34.5% of the groundfall incidents. Finally, support system failures made up the remaining 15.5%. Results from this taxonomic analysis may suggest focus areas toward which preventive measures and future research activities could concentrate.