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By Z. Zborovszky

The feasibility of using the nucleation properties of combustion generated particulates for the identification of their sources was investigated, using the Cloud Condensation Nuclei (CCN) Spectrometer. The Investigated materials included coal, wood, belt materials, electrical insulation, brattice cloth, and diesel exhaust. The materials were heated In an oven using filtered air flow, and their time, temperature, and the critical supersaturation spectrum of condensation nuclei (also referred to as the CCN spectrum) produced by the combusting material were recorded. Some data was obtained on a typical metal-mine background containing blasting products. The data was processed and analyzed In an attempt to specify parameters and limits that would allow the identification of the combustion sources. It appears that under controlled test conditions It Is possible to Identify the source on the basis of data derived from the CCN spectrum. More general use of the Idea for fire detection under uncontrolled practical circumstances in an actual mining environment does have potential but would require further research.

Jan 1, 1978

By John M. Popovich

Disposing of coal mine waste at the surface has been and continues to be a problem which has yet to be resolved within the coal mining industry. A possible solution to this problem is to return the refuse back into the operating underground mine generating the waste material. It is believed that the approach described will provide an inexpensive and pratical solution to the problem. The designed system is installed and operable at the Millers Cove Energy Company, Inc. property in Lee County, Virginia. This system limits surfact facilities to a minimum size. It incorporates state-of-the-art hydraulic transport and backfilling technology and equipment to systematically backfill areas within the active mine. It maximized the benefits of reducing treatment of coal wasts while it minimizes environmental impacts on groundwater. The system approaches the problem in a manner to maximize benefits and minimize risks. The cost of returning coal waste back underground at the Millers Cove site is estimated at $0.67 per ton of marketable coal (1982 dollars), which is slightly higher than their surface disposal cost of $0.61 per ton of marketable mat (1982 dollars). The underground disposal costs do not include cost savings that should be realized within the preparation plant and treatment facilities at the surface. Preliminary tests of the system were conducted at the surface; funding restrictions prevented an in-mine trial. Efforts should continue to demonstrate the feasibility of solving the problem of refuse disposal. The installed system and plant at Millers Cove should provide the opportunity to test an underground disposal operation. This report contains guidelines to pursue this opportunity.

Jan 1, 1986

By Andrew F. Conn

This report summarizes the results from the first year of an anticipated multiphase program to develop improved coal mining equipment which utilize the CAVIJET? cavitating water jet method. This laboratory parametric study demonstrated the advantages of cavitating jets over non­cavitating jets in cutting coal, by producing comparable slot depths at one-fifth of the operating pressure, at better than one-half of the spe­cific energy. These results suggest that CAVIJET-augmented mining devices can be developed with compact, low-pressure pumps. Thus, CAVIJET should be capable of operating with safer, lighter support equipment, while providing all of the advantages (reduction of dust and sparks, reduced damage to cutters) of conventional hydraulic mining methods.

Jan 1, 1976

By John E. Trombly

System objectives and design criteria for an in-mine ULF radio paging system are discussed Coding formats, frequency and bandwidth selection criteria leading to the system design are discussed. The prototype call alert transmitter and pocket page receiver is functionally described. The report includes circuit descriptions, schematics, parts lists, printed circuit fabrication and assembly drawings. The report concludes with an estimate of the manufacturing cost for each assembly.

Jan 1, 2011

By John E. Miller

Supercompressibility factors, Fpv, were derived from experimental compressibility data for five helium-nitrogen mixtures containing from 50 to 100 pct helium. These Fpv values are required as volumetric correction factors for or if ice meter measurement of "crude helium" (helium-nitrogen) purchased by the Government in a program of helium conservation. Although compressibility measurements were made by the Burnett method (2)3 - for pressures from 100 to 3,400 psia and temperatures from 40° to 100° F, Fpv values were needed only for pressures from 400 to 2,000 psia. Consequently, values at increments of 2° F, 2 pct helium, and 10 psia were tabulated only for the required pressure range. Values for pressures outside this range can be calculated from information shown in the tables. Values for the second, third, and fourth coefficients in the equation Z = 1 + BP + CP2 + DP3 are also included.

Jan 1, 1963

By William N. Patterson

This report describes the design and testing of an improved quiet hard rock percussion drill. The improved drill incorporates a tappetless design with independent rotation in a hand held drill weighing 50 lbm. Laboratory and field testing in three mines were conducted. The testing showed improved drilling performance with no increase in measured noise levels over the fist design.

Jan 1, 1985

By Robert R. Perron

The U.S. Bureau of Mines is engaged in many diverse programs fur improving mine safety. One area of interest to the Bureau is new and improved means for minimizing the hazards of accidental gas ignition or electrical shock should the frame of an off-track machine assume potential above ground. Various means presently used to prevent such occurences are the use of ground fault detectors for phase to ground faults in ac machines, and grounding conductors and diodes in dc machines. In a three phase ac power center, a phase to ground fault may be detected by monitoring the current in the grounding resistor which is required between the power center neutral on the load side of the power center transformer and ground. Another method for detecting a ground fault is to pass the three load conductors through a toroidal core transformer. The phase currents vectorially add up to zero if none of the phases are faulted, and hence the voltage of the transformer secondary is either zero or not zero if one of the phases is unbalanced or faulted.

Jan 1, 1976

By J. Torma-Krajewski, C. Hipes

Although many mining companies apply ergonomic principles, it is usually done either informally and/or reactively. An example of an informal approach is replacing worn equipment (such as seats) with models that have ergonomic features. Another example is modifying a task to eliminate safety hazards. Such approaches reduce risk-factor exposures that can lead to musculoskeletal disorders (MSDs). A reactive approach is followed when modifying a task/ equipment after an MSD occurs. However, neither of these approaches involves a systematic method of proactively applying ergonomic principles to actually prevent injuries or illnesses. This paper discusses how Vulcan Materials Company applied ergonomic principles and implemented interventions to reduce risk-factor exposures.

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 Marcel Vanpee

Eight extinguishing powders KCI, were tested on five types of diffusion flames. The effect of flame temperature on the inhibition efficiency was investigated by varying the oxygen index of the flame supporting atmosphere. Inn addition a spectrographic investigation of powder flame dissociation products was carried out on the methane/air/ABC (NH4H2PO4) flame. Dissociation products for this flame included P0, PH, NH, and Na. It is concluded that the main factor to be considered in the efficiency of tie powder is the flame temperature Purple K (KHC03) was typically inefficient in low temperature flames and very efficient in high temperature flames. On the other hand, ABC (NH4H2PO4) was found to lose its efficiency at high temperature but to be quite efficient in the low temperature flames. The effect of temperature is offered as an explanation of the poor efficiency of Purple K (KHC03), against coal dust explosions as contrasted to the high efficiency of phosphate salts against coal dust explosions.

Jan 1, 1982

By William C. Cooley

This volume contains copies of the 5 x 8 in. accession card file for all items collected which were judged to be relevant to underground hydraulic coal mining. In many cases, abstracts are included. Abstracts were taken from the source, from other reviews, or from the preliminary screening of Russian documents performed by Dr. A. L. Brichant. No attempt was made to write abstracts for every accession item.

Jan 1, 1975

By David Hill

The Australian underground coal mining industry has made extensive use of the Coal Mine Roof Rating (CMRR) classification system for a diverse range of purposes in recent years. These include mining method selection, and coal pillar and roof support design. This paper outlines a series of case histories, from large-scale feasibility studies to local support design investigations, that collectively illustrate the broad applicability, advantages, and usefulness of the methodology, as well as some of the current limitations. The key role of the CMRR in an overall hazard definition methodology is demonstrated for a major Australian project, and some ideas with regard to the future application of the CMRR, in the context of geotechnical risk management within a progressive, highly productive extractive industry, are put forward.

Jan 5, 2007

By Alan Mayton, Bertrand Valero, Farid Amirouche

Handling of heavy vehicles such as tractors, trucks and buses require a large roll stiffness which causes large high accelerations at the seat level during impacts. To provide comfort and minimize the energy transfer from the chassis and the seat a pneumatic active seat suspension is proposed. An active seat suspension design and control algorithm under development at the University of Illinois at Chicago, UIC, is being developed and tested. Preliminary results are presented in this paper. The design of a passive suspension typically consists of optimizing the value of two parameters: the stiffness and the damping of the suspension. The general dynamic performance of the suspension is limited to the conditions under which these parameters were obtained. A change in the input conditions might lead to poor suspension and an amplification of the vibration transmitted to the body. The focus of this paper is a robust, semi-active suspension system with a variable controlled damping and using the body response an index measure to minimize the acceleration at the interface of the seat and operator. A summary of existing suspensions, such as MR and ER fluids, and spring loaded and dual valve shock absorbent will be discussed to highlight the need of a semi-active pneumatic suspension system design. Methods A model of the proposed suspension was developed in MATLB (Simulink) and different control strategies for the valve position in relation to the cylinder pressure tested. The effects of stiffening and softening resulting from pressure changes in the cylinder were examined. The vertical accelerations of the seat was computed for different control strategies and configurations of the suspension and compared to the response of a passive seat suspension. A lump -mass model was created to represent the human body including the head, the upper, middle and lower torso as well as the legs. The connective forces between body segments were modeled through modal analysis techniques from previous experiments at the Vehicle Technology Laboratory. ISO standards and absorbed power were used to evaluate the different configuration of the seat suspension system in relation to the dynamic response of the operator. Results Initial results of the semi-active suspension system show a significant reduction in the RMS value of the acceleration of the seat. A reduction of the total absorbed power by the operator is expected to provide an insight into the control strategies adapted in the active suspension.

Jan 6, 2006

By B. Gillenwater

This report describes the results of investigations into four specific areas related to trolley wire power distribution systems in coal mines. These are: 1. Partially insulated (shielded) trolley wire 2. High-speed insulator fault detectors 3. Dual-wire trolley systems 4. Insulator failure indicators. Prototype devices or designs were developed in each area. In addition, a brief survey was made in an attempt to assess the Future of mine trolley systems, and data was collected and reviewed in an attempt to analyze the nature of trolley wire related accidents. Other options for decreasing the risks associated with trolley systems that arose .during the study are briefly described in appendices. These include insulating equipment and miners from return and/or energized conductors and use of a segmented trolley wire with local control of current delivering capability.

Jan 1, 1981

By Jueun Lee, Jong-Hwa Yoon, K. Rider, Bernard J. Martin

Whole body vibration is known to affect movement accuracy [1], however little is known about changes in the organization of movement and movement strategies used to limit the influences of perturbations. The specific aim of this work is to analyze the motion and coordination of upper body segments of seated operators performing reaching tasks under whole-body sinusoidal vibration exposure and simulated vehicle ride motion. The long-term objective is to model reach coordination and predict the dynamic behavior of the upper body motion under vehicle vibration exposure. Method The reach task consisted of pointing with the right hand index finger to targets located on touch screens placed in front of the subject, 45° overhead and 90° to the right in the mockup cabin of an HMMWV placed on a 6 DOF ride motion simulator. The task was performed under stable (no vibration) and vibration (sinusoidal vibration or simulated ride motion) conditions. A motion capture system was used to record kinematic data of reflective markers to recreate body link trajectories. Joint angles (torso, shoulder and elbow; Figure 1) were then computed using quaternions. Coordination between body links was defined as a) the joints angle-versus-angle relationships between the upper arm and lower arm, and b) the joint motion onset relationships between torso, upper arm and lower arm in the time domain. Results Angle–versus-angle relationships. The relationship between upper arm vs. lower arm angle and torso vs. upper arm angle for a far forward reaching movement in the stable (solid lines) and vibration conditions (dotted lines) are illustrated in Figure 2. Fig 2A compares the control condition with a 4 Hz lateral vibration while Fig 2B compares the control condition with a 6 Hz vertical vibration. It appears that under vibration exposure the reduced upper arm extension is compensated by an increase in torso flexion. This effect is seen in the last phase of the movements (encircled areas). In addition, the lower arm extension is delayed under 6 Hz vertical vibration (Fig 2B left panel). Time of joint motion onset. The timing relationship between torso, upper arm and lower arm is largely a function of the target to be reached. Examples of delays between body links are illustrated in Figure 3. The control condition is compared to a 6 Hz vertical vibration for three

Jan 6, 2006

By Howard M. Stainer

Published X-ray mass absorption coefficients were compiled and tabulated. These coefficients are required for various X-ray analytical techniques. Values obtained from 28 authors are listed for 87 elements with both experimental and calculated points included; the wavelengths range from 4.01 to 68 A. Representative graphs are presented for six elements (lithium, nitrogen, iron, silver, holmium, and uranium. A 37-item supplementary bibliography is also included.

Jan 1, 1963

By Steve Signer, Ed Mchugh

Recent studies by researchers from the National Institute for Occupational Safety and Health indicate that shear loading contributes significantly to failure of bolts used for rock reinforcement in coal mine roofs, Laboratory tests on 17 bolts were conducted to study the behavior of roof bolts subjected to shear loading over a range of axial bolt loads, Fourteen strain gauges were attached to each bolt to measure axial and bending loads at seven locations along its length. The instrumented bolts were grouted through two high-strength concrete blocks, and axial tension was applied to as much as 75% of yield strength. With the block interface acting as a failure plane, shear loads were applied to the blocks at a constant rate of displacement to the ultimate strength of the bolts. The tests characterized the relationship of axial bolt loads to shear forces across a rock bedding plane and measured the distribution of axial and bending strain along the length of the bolts. 'These results will improve the selection of roof reinforcement in mine areas where high shear stresses are present, thus improving the safety of miners working in these areas.

By Anderson Dana

THIS PAPER describing methods and costs of mining and preparing gravel and sand for market at the Port Jefferson plant of the Seaboard Sand and Gravel Corporation, is one of a series of articles on gravel and sand mining, prepared for and published by the U. S. Bureau of Mines, which is designed to disseminate technical information regarding the methods used. The cost tabulations represent operating expenditures only and not total costs, It is recognized that publication of total costs might in many instances cause embarrassment to individual producers, as well as to the industry as a whole. On the other hand, operating costs are essential to the technical [ ]

Jan 1, 1932

By Howard M. Stainer

Published X-ray mass absorption coefficients were compiled and tabulated. These coefficients are required for various X-ray analytical techniques. Values obtained from 28 authors are listed for 87 elements with both experimental and calculated points included; the wavelengths range from ~0.01 to 68 A. Representative graphs are presented for six elements (lithium, nitrogen, iron, silver, holmium, and uranium. A 37-item supplementary bibliography is also included.

Jan 1, 1963

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.