Search Documents

By Ben A. Kornhauser

Benin's industrial sector experienced severe economic and financial problems in 1986, including disappointing performances of the Onigbolo cement plant and the Semé Oilfield, plus a shortage of technically trained personnel and experienced management. Oil production remained about 1,000 barrels per day. Import and export trade between Benin and the United States remained minimal. Because much of Benin's outstanding external debt was in U.S. dollars, the stronger dollar greatly increased the debt burden. The 1985 budget of $304 million' was composed of an investment budget of $194 million and a current budget of $110 million. Of the investment budget, 84% was expected to be externally financed. About $45 million was given to three priority projects: the joint Benin-Togo Nangbeto hydroelectric project scheduled for completion in 1986; drilling of new exploratory wells of the Semé petroleum project, and the Dassa-Parakou highway. The budget deficit was projected to exceed $43 million despite a decrease in projected revenue owing to an anticipated decline of 25% in import tax revenue, normally the largest source of Government revenue.

Jan 1, 1987

By David M. Hyman

Outbursts are sudden and violent releases of gas and coal that result from a complex function of geology, stress regime, and gas pressure and content. The Bureau of Mines has reviewed methods for prediction and mitigation of such outbursts in use worldwide, as an aid in selecting the proper techniques for use in specific mine environments. Outburst-prone coal may be distinguished from normal coal by its sorption-desorption velocity. Three types of methods used to characterize the kinetics of sorption-desorption are described; all are based on the ability of outburst-prone coal to release, through desorption, methane or carbon dioxide much more rapidly than normal coals. Other prediction methods, based on borehole samples, are also described. Various mitigation methods described and evaluated include (1) working the least stressed, less disturbed, lowest gas content seam in multiple-seam areas; (2) mine opening geometry; (3) inducer shot firing; (4) water infusion; (5) localized stress relief, using boreholes or by cutting a reliever slot in the longwall face; and (6) other gas drainage methods.

Jan 1, 1987

By E. D. Gardner

"It has only been in recent years that the proper ventilation of metal mires has received serious consideration. Increasing temperature and humidity with greater depth in some of the larger mines of the West prevented the efficient operation of the mines and made the installation of mechanical ventilation systems necessary. Doors that interfere with tramming are generally needed to control properly the mechanically induced air currents and are one of the inherent disadvantages of the system. In fact the necessity for the use of doors in the main haulageways has discouraged the installation of mechanical ventilation in some metal mines.A number of mining companies in Arizona are using ventilation doors which can be opened and shut mechanically by the motorman without leaving his seat or stopping his train, end thus interfere very little with the transportation of the ore. The Copper Queen Branch of the Phelps-Dodge Corporation at Bisbee introduced these ventilation doors and adapted them from those in use in the company's coal mine at Dawson, New Mexico. Other mining companies have installed the same type of door and it is now being used in a number of districts in Arizona.The doors at the Calumet and Arizona mine in the Bisbee district are representative of those in use. The doors at this mine are substantially built of 2-inch lumber, are air tight, are well placed and have two openings or passageways. The main door, which is used for the motor trains, is 5 feet wide by 6 feet high and is opened by compressed air and closed by a counterweight. At the side of the motor door is the man door, which is 16 inches wide by 5 feet high and is opened and closed by hand."

Aug 1, 1921

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

MFIRE is useful for the analysis of ventilation networks under thermal and mechanical influence MFIRE simu¬lates a mine&apos;s ventilation system and its response to altered ventilation parameters, external influences, and internal influences Extensive output enables detailed quantitative analysis of the effects of the proposed alteration on the ventilation system MFIRE was written in FORTRAN 77 and compiled with Microsoft° FORTRAN for the Intel 8086-8088 central processing units The source code is listed in appendix A for users who wish to modify the source code for operation on other computers MFIRE MODIFICATIONS OF MTU-BOM CODE The program described in Bureau of Mines Informa¬tion Circular 8901 has become known as the MTU-BOM codes MFIRE is an evolutionary product of the MTU¬BOM code with major improvements and enhancements 6 For users previously familiar with the MTU-BOM code, the following is a listing of the major improvements and enhancements incorporated by MFIRE 1 The length of an airway is an input value, LA The elevation difference of the airway is calculated from the elevation input, Z, in both programs It is possible for a data file to describe an airway that is shorter than its el¬evation difference The MTU-BOM code does not check for this error and uses the values of LA and Z This does not cause a computational problem, only a simulation problem MFIRE issues a warning message for this case, and the airway length is made equal to the elevation dif¬ference if LA is less than Z 2 To evaluate rock temperatures (average wall surface temperature of airway before a fire), it is assumed that the air temperature at an airway entrance is equal to the air temperature at the airway starting junction, and that the air temperature at the airway exit is equal to the air tem¬perature at the exit junction. The MTU-BOM code follows this assumption in all cases When a rock temperature of less than 0° F is calculated, an average temperature is used to represent the rock temperature of the airway MFIRE uses the same principle, except the consideration of unlikely rock temperatures When the exit junction of an airway is the atmosphere (a fixed condition junction), the air tempera¬ture at the exit is made equal to the air temperature at the airway beginning If an unlikely value of wall temperature (<0° F or > 150° F) results from calculations, a message is issued and the rock temperature is set equal to the air temperature at the airway exit The program user can always input rock temperature (TROCK) for an airway to override the calculated value. 3 MFIRE allows use of an optional reference airflow rate to define and limit the heat generation of a fire source This allows the simulation model to more closely resemble a real fire and to improve simulation conver¬gence Heat generation corresponds, but is not linearly related to airflow rates reaching the fire In the simula¬tion, heat generation is calculated from oxygen consump¬tion and is directly related to the variable incoming airflow Use of this optional reference airflow rate allows the heat generation to vary, but in a damped, user defined manner When the airflow rate passing through a fire source is equal to its reference airflow rate, the data items describ¬ing the fire source are not modified If the airflow rate is lower or higher than its reference airflow rate, the data items used to define the fire source are modified according to the following equations

Jan 1, 1990

By Jonisha P. Pollard

In restricted vertical working heights such as low-seam coal mines, workers are forced to assume kneeling or squatting postures to perform work. These postures are associated with increased risks for the development of significant knee pathologies such as meniscal tears and osteoarthritis [1,2]. Previous research has shown an increased applied knee flexion moment when kneeling in high flexion [3]. However, these models have been applied to flexion up to 140° which neglects contact between the thigh and calf which occurs beyond 140°. In addition to thigh-calf contact, when kneeling near full flexion there may be additional contact between the heel and gluteal muscles. To the author?s knowledge, heel-gluteus contact has not been previously investigated, but thigh-calf contact has received some attention. Zelle (2007) reported thigh-calf contact forces up to 30% bodyweight (BW) [4]. Zelle (2009) reported decreased knee forces when accounting for thigh-calf contact [5]. Caruntu (2003) reported erroneous force and moment estimations when thigh-calf contact was neglected from models to determine muscle and ligament forces [6]. In this study thigh-calf and heel-gluteus contact forces were quantified to determine their effect on the externally applied flexion moment in high flexion.

Jan 1, 2009

By Launa Mallett, Michael J. Brnich

The first step to emergency preparedness is defining and analyzing hazards. Although all hazards should be addressed, resource limitations usually do not allow this to happen all at once. Risk assessments are used to establish priorities so that the most dangerous situations are addressed first and those least likely to occur and least likely to cause major problems can be considered later. While the examples provided in this training package are specific to mine fires, the concepts and tools can be applied to any mine hazard. Purpose: This training package was developed to assist instructors, as they: 1) determine how to use risk assessment to improve preparedness for mine fire emergencies and 2) present risk assessment concepts and tools to trainees. Audience: This package is appropriate for workers/trainees from all types of mines. A risk analysis can be conducted by anyone familiar with the location(s) being studied. Why Conduct a Fire Risk Assessment? During a risk assessment, hazards are evaluated in terms of the likelihood that a problem may occur and the damage it might cause. Mine fire preparedness requires consideration of all possible fires that could occur. However, at a given mine some fires are more likely than others and some would result in greater damage than would others. Conducting a risk analysis identifies these differences. The results can be used to target resources at the types of fires that are most likely and/or are most destructive. Hazards that are very likely to result in fires that would do considerable damage to people and property should be targeted first for remediation and/or effective response if remediation isn&apos;t possible. Potential fires that are less likely or that would have less severe consequences are identified for attention later, after the more serious situations have been addressed.

Jan 10, 1992

By E. P. Youngman

The mining law of the Belgian Congo does not cover the Province of Katanga nor the District of Kivu (in Eastern Province). Regulations of the Comité Spécial du K tanga are in force in Katanga and those of the Comité National du Kivu in Kivu. The three laws differ only in detail, and grants made by the Comité Spécial du Katanga or by the Comité National du Kivu must be approved by the Ministry of Colonies. The following résumé is designed to coordinate the three sets of regulations.

May 1, 1930

By N. S. Dalal, W. Irr, X. Shi, V. Vallyathan

"Inhalation of crystalline silica is associated with a biphasic biologic response of acute cell injury and chronic pulmonary fibrosis. Dust induced cell membrane injury leading to the release of lysosomal enzymes and cell death has been implicated as the initial important biologic event triggering the fibrosis. However, it ls also possible other biologic reactions could alternatively, or in addition to these enzyme related cytotoxicity reactions, alter the normal functioning of cells. It is well known that phagocytic activation results in the production of oxygen radicals which are highly cytotoxic to cells. In healthy - lung, protection against the toxic effects of the normal balanced ·biologic reactions are provided by a number of defen1e systems including antioxidants. In disease or condition of overproduction of oxygen radicals, biochemical protection may be overwhelmed with resultant cellular injury.Our recent observations have shown that reactive oxygen radicals (ROR) are generated during grinding of crystalline silica. We hypothesized that these newly generated RORs may cause cell injury, lipid peroxidation, or even damage to macromolecules such as DHA. Biochemical aberrations caused by the inhalation of crystalline silica with ROR at occupational settings might overwhelm cellular and antioxidant defense systems of the lung leading to injury and subsequent fibrosis.To test this hypothesis, we have investigated the generation and decay of ROR produced by crystalline silica using electron spin resonance (ESR) and investigated its toxicity with conventional biologic tests at various time intervals after grinding. We also studied the decay of these newly generated RORs in buffer and the effect of antioxidants and scavengers in the abolition of cellular damages."

Jan 1, 1989

"While control of dust-related diseases, the objective of the Generic Mineral Technology Center for Respirable Dust, is of prime importance from the human standpoint it is also essential to the economic well-being of the mining industry (FIGURE 23). Although significant progress has been made, the problem continues to be a major concern to the mining community. An increasing global demand for coal and other minerals means that production and the number of miners employed is on the rise. Therefore, the importance of this research to the mining industry cannot be overemphasized.The five areas of dust research are 1) control of dust generation, 2) dilution, dispersion and collection of dust in mine airways, 3) characterization of dust particles, 4) interaction of dust and lungs, 5) relationship of mine environment, geology, and seam characteristics to dust generation and mobility. Some experimental projects where the research is conducted almost exclusively in the laboratory may still rely on industry for imput. No industrial resources are necessary to the research of the non-experimental projects, for example computer modeling .The remaining research is classified as experimental and these projects do require interaction with industry in varying degrees. Periodic trips to mining sites in Western Pennsylvania, Southern Ohio, and West Virginia are necessary to record measurements or collect samples. Or companies may provide needed samples or equipment to the university for use in the laboratory. On several projects interaction is limited to advice or information supplied to the researcher by industry personnel."

Aug 31, 1989

By BUREAU OF MINES

The cheapest method of handling gravel in placer mining operations is by hydraulic mining . In working gravel deposits by hydraulic mining , it is essential that an abundant supply of water under sufficient head can be economically developed and that there is sufficient grade for sluice boxes and for disposal of the tailing . Without dumping facilities , simple hydraulic mining is an impossibility . The cost of hydraulic mining may range from 2 cents a yard under favorable condıtions to 12 or even 20 cents under less favorable conditions and to 35 cents or more a yard in Alaska , according to conditions of operation , and if frozen gravel is encountered . When it is necessary to elevate gravel , the costs may exceed 60 cents a cubic yard . When the natural conditions do not permit of hydraulic pining proper , other methods of elevating the grade are employed , some of which are described below . Bucket dredging has replaced hydraulic mining in importance in California and other states where hydraulic mining was once extensively carried on , and is by far the cheapest method of elevating gravel when mechanical methods are required and the physical conditions are suitable for dredging . Dredging costs vary greatly under the different conditions encountered , and the total amount of gold to be recovered must of course be enough to warrant the cost of a dredge installation . Gold dredging operations in the United States are fully described in Bull . 127 , U.S. Bureau of Mines .

Jan 1, 1922

By Graham W. Marks, RALPH MILLS, FRANK COSSEY

To determine the focal length of lenses or the performance of lens systems before mounting them permanently , it is desirable to have a device in which one or more lenses can be mounted easily and their positions relative to a light source and screen changed readily . We have designed and constructed such an optical bench and lens holder . The bench is similar to that of Houstoun5/ but has been modified , whereas the lens holder is , we believe , a new design .

Jan 1, 1948

Track and control the tram maneuvers of continuous mining machines by developing and evaluating a laser sensor system. Background Progressive technology has the potential to greatly improve mine-worker safety, helping to create a safer, better working environment for mine workers by keeping them away from the dangerous face area. To benefit from such technology, the Bureau is investigating remote, computer-assisted operation of mining systems for underground, highwall, and surface mining applications. A cornerstone for computer-assisted operation is an effective guidance system. Since there are no guidance systems on any commercial continuous miners (CM&apos;s), the Bureau it-self developed and tested a laser-based sensor system, based on a commercial sensor called Lasernet. The laser-based guidance system employs four laser scanning sensors at fixed locations in a mine entryway to report the angular coordinates of two cylindrical retro-reflective targets mounted on a CM. Using triangulation, a real-time microcomputer system processes the sensor data and updates the xy position and heading (h) of the CM five times per second. Using a simple control algorithm and communications interface to the CM control computer, the system also controls rotational and translational tram maneuvers.

Jan 1, 1992

By C. L. Severy

On the Pacific coast during World War II, a tremendous ship-building industry was developed, Early in the war it became impossible to obtain in- got or steel scrap for ship ballast. Magnetite, an oxide of iron, was sub- stituted as it fulfilled the requirements of weight for available space in the ships. Consequently, a new use for the western magnetite was rapidly developed.

Jan 1, 1948

By W. J. Fene

"The prevalence of accidents in the coal-mining industry has prompted a study of the workmen's compensation laws of the various States and the statistics of accident costs, for the purpose of explaining to operators how the compensation laws are regulated and to show the cost of accidents.The subject of compensation laws and accident costs is by no means new, but the prevalence of coal-mine accidents would indicate that the mine operator in general is not thoroughly conversant with their importance. Unquestionably, compensation laws are a large factor in promoting accident prevention, and it is believed that a greater measure of success would be accomplished in preventing accidents if all mine operators were fully aware of their important bearing on the cost of production.Many operators seem to be indifferent to accident occurrence; possibly they do not real¬ize the seriousness of the accident hazards that exist in their mines, even after the hazards are brought to their attention. There is no question that material financial advantages are to be gained by the prevention of accidents and it would appear that when these advantages are thoroughly understood, operators would be anxious to eliminate, insofar as is feasible, conditions likely to cause accidents.The unsettled state of the mineral industry and the irregular operation of mines during the past several years has probably been an important factor in influencing the apparently indifferent attitude of the operator. The chaotic conditions in the mining industry and especially in coal mining are unquestionably a factor that tends to increase accidents, just as mine idleness increases roof hazards and results in deterioration in mechanical, electrical, and haulage equipment, and promotes disorganization of the personnel. During such times greater efforts should be exerted toward the prevention of accidents because of these increased hazards and of the financial advantages brought about by the various savings to be effected when mine accidents are held to a minimum.This report on accidents in the coal mines of Pennsylvania was made possible largely through the cooperation of William J. Maguire, director, Bureau of Statistics, Pennsylvania Department of Labor and Industry, and Rush N. Hosier, superintendent, Coal Mine Section, Pennsylvania Compensation Rating and Inspection Bureau, who made available their records and extended much assistance and numerous courtesies during this study."

May 1, 1932

By Oliver Bowles, J. E. Crawshow

A line of cordeau detonating fuse was placed in hole No. 2, no electric detonators being used in the hole. After 12 or 13 cases of 40 per cent nitro starch powder had been poured into the hole in loose form, it was found that a space of only 17 ft. remained for stemming. It was decided that space for an additional case of powder might be obtained by tamping the charge. The tamping was done with a heavy plunger, about 3 or 3 inches in diameter and 10 inches long, made of lead with an iron core with an iron eye in the top to which a 3/4 inch rope was attached, and weighing between 30 and 40 pounds. This weight was intended for use in sinking explosive in wet holes, and not for tamping. It is estimated that the tamping had continued at least 10 The quarry superintendent had gone a considerable distance for a box of powder, returned, and reached a point about 10 feet from the hole, minutes.

May 1, 1920

By R. D. Currie

Many coal companies have a system for checking men into and out of the mine , and generally such systems appear to be perfectly sound and adequate . However , when the real test comes at the time of a mine disaster , too often the system is found to have failed , and hours and sometimes days pass before it is known how many men are in the mine and who they are . Most of the systems in use , when properly maintained , are adequate for the routine work of the mine , and some of them may prove adequate at the time of a mine disaster . All systems , however , depend upon proper supervision and strict adherence to the system .

Jun 1, 1930

1. In 2003, a total of 734 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Examples of nonmetal mining operations include, but are not limited to, the mining of clay, shale, barite, potash, trona, phosphate rock, rock salt, gypsum, talc, gemstones, mica, perlite, and pumice. • Nonmetal mines comprised 5.1% of all mining operations. • Nonmetal mining operations are located in all states and territories except Alaska, Delaware, Maine, New Hampshire, Rhode Island, Puerto Rico, and the Virgin Islands. • Mines producing common clay comprised 28.6% (n = 210) of all nonmetal mining operations.

Feb 1, 2005

By Stephen L. Tillim

Tubular Handles can negatively affect the contents of the carpal tunnel. Years of injuries from grasping handles for tools and machines can cause carpal tunnel syndrome, tendonitis and wrist joint injuries. The can cause inability to use a hand and resulted in the longer absences from work than injuries from falls, accidents or fires.1 Cylindrical, tubular and rectangular handles are rolled flat structures. They place the hand on a rolled flat surface where the ends of the middle and ring fingers overlap the index and small fingers. They are pulled along a series of lines that contact the end joint of the index finger, the middle bones of the middle and ring fingers and the end bone of the small finger. Cylinders are pulled diagonally in the hand toward the carpal tunnel (CT) area. Gripping in this manner tenses asymmetric muscle groups in the forearm. Handles could work better if they do not place pressure on the CT and conform to the natural function or neutral hand position where the hand rests or dangles at the side of the body, the finger tips form a diagonal, the palm and fingers form a cup, the thumb rests between the index and middle fingers and the wrist is mildly extended. However, handles designed for the neutral position are pulled by diagonally oriented fingers into the valley between the thenar and hypothenar muscles where they can compress the median nerve and tendons exiting the CT. Seven principles for handles that do not place pressure on the carpal tunnel and employ optimal hand position are presented. First, handles should align the ends of the fingers parallel to the horizontal crease and not diagonally. Second, handles should extend from the cupped fingers to meet the muscles at the base of the thumb on the radial side of the hand and extend further on the other or ulnar side to meet a portion of the small muscles. Third, handles should have a recess on the proximal side to prevent contacting or placing pressure on the carpal tunnel. Fourth, handle design should be based on hand measurements in a position of function. Fifth, handles should come in sizes. Sixth, handles should be placed on tools to maintain the wrist and elbow in neutral position. The seventh is handles should support the maximum area of the hand and absorb, but not direct, vibration to the carpal tunnel. These principles led to prototypes and patents for handles for gripping, pinching and squeezing2,3,4 . The poster will illustrate and explain the principles Bonsil handles. Research, with existing tools, is needed to substantiate claims made for the Bonsil handle.

Jan 6, 2006

By Jack C. White

Studies were made to determine the character and distribution of the copper lost in copper mill tailings. Acid soluble (oxide) and acid insoluble (sulfide) copper were determined for heavy-liquid sink and float products of screen-sized fractions from 12 copper mill tailings. In most of the tailings studied, the coarse-size fractions are higher in copper grade than the respective bulk tailings, high in sulfide copper, and low in oxide copper. Oxide copper occurs predominantly in the minus 325-mesh "slimes." Microscopic examination of heavy-liquid sink products indicated that recovery of liberated copper sulfide minerals is complete in most mills, and that copper minerals not being recovered are locked with gangue particles. Additional copper could probably be recovered from most tailings by size classification, scavenger froth flotation of the coarse fraction, and regrinding of the concentrate to achieve liberation of the locked sulfides.

Jan 1, 1971

By A. B. Cecala

A cooperative research effort was established between the Tilden Mining Company LC, the United Steelworkers of America, and the National Institute for Occupational Safety and Health to lower respirable dust levels in an iron ore grinding and concentrator plant. This cooperative effort involved three field studies to evaluate different techniques to lower respirable dust levels. The greatest impact on lowering respirable dust concentrations throughout this facility was achieved through ventilation changes. The most significant improvement was realized by changing the ventilation profile throughout the entire facility. The ventilation to this grinding and concentrator facility was provided by approximately 40 roof fans operating in either the intake or exhaust mode. The operation of these fans was significantly changed in an attempt to pro-vide more of a directional flow pattern throughout the facility, as well as to more closely balance the intake and exhaust air volume. This change accounted for a 31 pct reduction in respirable dust levels in the primary grinding area of the mill. Another successful modification was to improve the sealing of a reclaim tunnel to the outside and by barricading the access point from the reclaim tunnel to the concentrator plant. This minimized the dust liberated in the conveyor tunnels from traveling through the reclaim tunnel and into the plant. These two modifications illustrate the impact that improvements in ventilation can have on lowering respirable dust concentrations in iron ore processing facilities.