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By T. E. Green

The Bureau of Mines Heavy Metals Program emphasizes the need for improved analytical methods for gold determination. A commercially available ion exchange resin with high selectivity for gold was investigated as a potential method to collect gold from solution. The resin was found to quantitatively collect gold from acid solutions over a wide range of acid concentrations. Common metals were not collected by the resin nor did they seriously interfere with the collection of gold. X-ray spectrographic and neutron activation methods based on the use of papers containing this resin are proposed.

Jan 1, 1970

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

1 11 THIS IS A DIGITAL COMPUTER SIMULATION OF THE VENTILATION SYSTEM OF A MINE LOCATED IN WASHINGTON COUNTY, PENNSYLVANIA. THE VENTILATION SURVEY ON WHICH THIS SIMULATION IS BASED WAS RUN FROM OCT. 27-30 AND ON NOV. 2, 1976 IN THE ACTIVE PORTION OF THE MINE INBY COMBS SHAFT AND THE INACTIVE PORTION AFCUND AND INBY DONAHOO SHAFT. FOLLOW-UP SURVEYS WERE THEN RUN ON FEB. 18 AND FROM MARCH 7-11, 1977 TO INCLUDE THE MAIN HAULAGE SYSTEM OUTBY THE ACTIVE AREAS OF THE MINE. ALL SURVEY DATA WAS NORMALIZED TO A STANDARD DENSITY OF 0.075 POUNDS/CU.FT. PRIOR TO THE CALCULATION OF INPUT PARAMETERS FOR THIS SIMULATION. IN THIS RUN, THE ORIGINAL VENTILATION NETWORK HAS BEEN MODIFIED TO INCLUDE NEW INTAKE AND RETURN AIRSHAFTS AT THE WEST MAINS.

Jan 1, 1977

Are you afraid of the dark? Of course not, at least not since you were about six years old, anyway. But early man was - afraid of the dark, and he had good reason to be. Since he had no illumination other than fire and moonlight, he was at a disadvantage when it came to mixing it up with some of his fellow creatures. Sabre-toothed tigers, for example, could probably see quite well In the dark, and they were very real enemies. Sabre-toothed tigers haven't been seen in mining country for some time now; but it's st111 dark In a mine and, make no mistake about it, there are still enemies in the dark. The enemies are all the things that can injure you if they are not seen. Modern mines can be safe places to work for the trained miner who follows good work practices. But there are mining machines that make sabre- toothed tigers look like pussycats, and if you can't see well enough they can be ten times more dangerous.

Jan 1, 1976

By Lloyd A. Morley, Alan M. Christman

General A review of the literature has revealed important areas which should be investigated during the field work. Of the utmost importance is the safety of mine personnel. Should a phase-to-ground fault occur on a shovel or other piece of equipment, current may return to the substation through the machine's contact surface with the mine floor, thereby raising the frame above ground potential and posing a shock hazard to anyone who touches the equipment. If the frame-to-earth resistance is very low, then no dangerous potentials will be developed, and a basis for elimination of the ground conductors from trailing cables could be postulated. However, should the contact resistance be high, then lethal voltages could be present on the machine frame. In this instance, low-resistance ground conductors in the trailing cable would be a necessity. Therefore, field tests should include measurements of the earth resistance of electrically operated portable or mobile mining equipment such as shovels, draglines, and drills. When the electrical distribution system is subject to lightning discharges, the grounding grid must safely carry to earth and dissipate enormous current surges. It is essential that the grounding grid have a low value of earth resistance, because any potential developed across the grounding grid as a result of current flow will appear on the frames of all machinery connected to the grid. Thus, an earth resistance

Jan 1, 1976

By Audrey F. Glowacki, August J. Kwitowski, Richard L. Unger, Edward F. Fries

Well-prepared personnel and an effective emergency response plan are essential components of any emergency command center. Unfortunately, evaluating emergency preparedness is often difficult until a disaster actually occurs. For example, unexpected events may develop during an emergency that were not considered during the planning phase. Also, the command center may need to cooperate with organizations that it has not worked with previously. Preparation can be especially difficult for smaller or remotely located command centers, or those with limited resources to conduct mock drills. This paper explores the potential of using the Internet to teach and evaluate command center skills. The National Institute for Occupational Safety and Health (NIOSH) is developing an Internet-based, computer simulation training package for the mining industry. Trainees will play the role of command center leaders at a mine, while the actions of other individuals and organizations are simulated. Trainees will be able to test their emergency response plans and learn valuable lessons from past mine emergencies. Nationally recognized experts will be able to create new training scenarios and make them available to mines throughout the U.S. This product should better prepare command center personnel for large-scale disasters such as fires and explosions. Keywords: emergency preparedness, simulation, training, internet

By C. W. Owings, F. E. Cash

"Transportation of explosives in mines is extremely hazardous, and where electric haulage is employed the danger is intensified. Insulated mine-car couplings have been adopted by at least five companies in Alabama and Pennsylvania - and undoubtedly in other States - to prevent an electric current passing from a mine locomotive to a car or between care joined by this coupling. The need for such protection is recognized in the report of an explosion.""Four hundred kegs of black blasting powder had been loaded into four mine cars at the railroad, to be hauled to the magazine, upgrade, by a trolley locomotive. On starting, the motorman put sand on the rail and a grounded circuit passed through the hitchings and so exploded the powder. No insulation was used between the locomotive and cars."" When used on man trips the insulated coupling further serves the purpose of guarding the men against shock. Four couplings are described so that a clearer understanding may be obtained of the details of construction.ConstructionThe general principles of construction are similar in all insulated couplings. The piece containing the hole for the coupling pin is made of steel and the steel parts are separated by an insulating material, such as fiber or wood. The coupling is either rigid or semirigid to prevent the bumpers of the mine cars from coming in contact and to keep the cars insulated from one another at all times."

Apr 1, 1928

Objective Develop field measurement and computer modeling methods to predict the potential for hang-ups and structural failures in underground mine ore paws. Background Analysis of Mine Safety and Health Administration (MSHA) accident statistics has identified ore pass hazards as a significant safety problem in underground metal mines in the United Stales. Recent ore pass failures have underlined the lack or ore pass design methods ant1 standards available to both MSHA and mine engineers. Injury and fatality data for the 20-ycar period between 1975 and 1095 show that nearly 75% of the injuries were directly or indirectly related to pulling or freeing ore pass chutes, the use of hand tools, falls or broken rock, and structural failures or chutes or gates and ore pass walls.

Feb 1, 1998

By Dana Reinke, Launa Mallett

Interest in training evaluation in the mining industry was piqued with the promulgation of Title 30, Part 46, of the Code of Federal Regulations. Under Part 46.3, a training plan is considered to be approved if it contains certain information, including “The evaluation procedures used to determine the effectiveness of training.” The present paper is a broad overview of training evaluation and is intended to give trainers and decision-makers a framework for planning or assessing training evaluation strategies. It discusses questions to consider when starting an evaluation plan, Kirkpatrick’s model of evaluation categories, and various ways to collect data. It does not provide detailed instructions on how to develop evaluation methodologies, but reviews topics to consider when creating an evaluation plan. Training evaluation is a term that has many different meanings: assessing the quality of a course, effectiveness of materials used, teaching style of an instructor, or the comfort of a classroom. An evaluation can be done informally over lunch or with highly structured data-gathering tools. It can produce results that are useful to trainers, program administrators, corporate decision-makers, or no one. The key to a worthwhile evaluation is clearly defining why the evaluation is being conducted. Once the purpose is defined, planning the evaluation strategy can begin. For an evaluation to be effective, it should be incorporated into the development of the training activity itself. The training evaluation worksheet at the end of this paper can be used to guide evaluation planning.

Jan 1, 2002

By P. R. Bremner

In keeping with its mission to maximize mineral and metal recovery from domestic sources, the Bureau of Mines investigated a method to extract silver from tailings not amenable to cyanidation. Results of a laboratory study on the recovery of silver from cyanide tailings containing 1.7 ounces of silver per ton by leaching with an acidic ferrous chloride-sodium chloride solution are presented. The effects of reagent concentration and reaction time on the leaching of silver were investigated. A leaching solution containing 5 wt-pct NaCI, 2.5 wt-pct FeCI2, and 1.2 wt-pct HCI (for acidity) extracted 82 pct of the silver from the tailings during a 24-hour leach. The amount of HCI consumed during the leach was 46 pounds of HCI per ton of feed. Only 23 pct of the silver was extracted by conventional cyanidation. Ninety-nine percent of the silver was recovered from the pregnant solution by cementation onto iron powder.

Jan 1, 1982

Develop a simple and practical technique to measure in situ rock mass properties for realistic design and stability evaluation of underground structures. Background The Bureau of Mines has developed basic principles and techniques to determine in situ rock mass properties including Poisson's ratio, deformation modulus, and yield and failure strengths. An instrumentation package consisting of three pressure cells is installed in a single drill hole. Cell pressure response data are acquired and used to calculate and determine the rock mass properties. How It Works A test hole of BX size (approximately 5.7 cm) or larger is drilled to the approximate depth of the measuring point. The last portion of the test hole is drilled with precision bits to EX size (approximately 3.8 cm). The instrumentation package, which consists of one 3.8-cm-diameter cylindrical pressure cell (CPC) and two 5.7-cm-diameter cement-capsulated, flat borehole pressure cells (BPC's), is then installed. A complete history of cell response to changing strata loads is acquired on a continuous basis with a chart-type hydraulic pressure recorder. From these cell pressure data, Poisson's ratios, deformation moduli, and yield and failure strengths are calculated and determined.

Jan 1, 1990

By Peter Kovalchikb, Gregory Colec, Syd Peng, R. J. Matetic, Jeffrey Petersond

Mine Safety and Health Administration (MSHA) data indicates that the roof bolting machine is third among all equipment and second among equipment in underground coal mining whose operators exceed the MSHA-PEL (Mine Safety and Health Administration-Permissible Exposure Limit). In response to this, the National Institute for Occupational Safety and Health (NIOSH) has conducted a study to reduce overexposures of noise to operators of roof bolting machines. An important segment of the research is to determine, characterize and measure sound power levels radiated by a roof bolting machine during different drilling configurations. The determined sound power levels generated during the drilling cycle are of major interest because the levels represent the overall sound power generated by the machine. These sound power levels, determined from laboratory tests, can be used to accurately assess the effectiveness of proposed controls for reducing noise exposure to roof bolting machine operators. By using the sound power level results obtained from the laboratory and a commercially available acoustical modeling package, a method for predicting sound pressure levels to roof bolting machine operators for differing drilling types and parameters could be determined. This paper provides a method for predicting sound pressure levels at the operator’s position of a roof bolting machine in an underground coal mine using sound power levels determined in the laboratory. To determine validity, underground coal mine data was also collected to compare predicted and measured sound pressure levels. The results of the predicted sound pressure level data were the same as the underground measured results. This research will provide the mining industry with a valid method for predicting a roof bolting machine operator’s noise dosage underground given any type of drilling configuration or drilling method utilized from laboratory testing.

Provide the mining industry with an easy-to-use means of accurately predicting surface subsidence caused by longwall mining in the northern Appalachian Coal Basin. Approach The Bureau of Mines developed a subsidence prediction model using the novel approach of a variable subsidence coefficient. This approach had to be used because of the resistant strata types which commonly occur within the relatively thin overburden material typical in northern Appalachia. Such resistant strata precluded the use of the popular European methods that assume homogeneous overburden or overburden behaving as homogeneous from a subsidence point of view. The model is available in a BASIC computer program for use on most personal computers. The user has the options of obtaining individual subsidence calculations or may choose to develop a subsidence profile using an average overburden value. The program output can be generated in graphic or tabular form showing the location of the surface point with respect to the longwall panel edge, overburden depth, and the subsidence value.

Jan 1, 1986

This chapter presents MSHA data on mine employment and active mining operations during 1986-1995. Figures 3-1 through 3-10 show, for each commodity, the location of mine operations in 1995, and employee hours and active mining operations by year during 1986-1995 for mine operators. For coal and nonmetal operators, the number of active mining operations and the number of employee hours decreased over the 10-year period. For metal operators, the number of active operations decreased, while the number of employee hours increased. For stone and sand and gravel operators, the number of active operations and the number of employee hours remained about the same. Figures 3-11 and 3-12 show that over the 10-year period, there was an increase in the proportion of hours worked by contractors in coal mining, while the overall employment decreased. For metal, nonmetal, stone, and sand and gravel combined, the proportion of contractor hours increased, with overall employment also increasing. Table 3-1 shows the distribution of hours worked during 1986-1995 by commodity and type of operation. For coal, the majority of hours worked were in underground mines. For metal, nonmetal, and stone, the largest number of hours worked were in mills and preparation plants. For sand and gravel, all work hours other than office were in surface mines. [ ]

Jan 5, 2000

By Edmund S. Leaver, Jesse A. Woolf

"The Baboquivari mining district is about 60 miles southwest of Tucson, Ariz., the present railroad shipping point. The values are silver and gold. The silver is largely associated with the black oxides of manganese. The ore is highly oxidized, and careful panning shows only a very small amount of pyrite. Our sample analyzed as follows:A flotation mill has been installed in the district, but it does not concentrate the precious metals satisfactorily. Our best laboratory flotation results were obtained by grinding to pass 65-mesh and floating with Xanthate or standard flotation oils plus sodium sulphide and polysulphide. This sulphidizing method gave a concentration of 32 per cent of the silver and 80 per cent of the gold, which about equals plant practice.We do not know of an instance where the oxidized forms of manganese have been concentrated satisfactorily by flotation.Plain cyanide on the original ore extracts practically all of the gold but only one-third of the silver. A preliminary deoxidizing roast, using producer gas or powdered coal, gives a calcine from which cyanide dissolves about 90 per cent of the gold and 75 per cent of the silver. This method of treatment, known as the Clevenger-Caron process, is described in Bureau of Mines Bulletin 226.Preliminary treatment with sulphur dioxide by burning pyrite or sulphur and passing this gas into the pulp until all of the contained manganese is dissolved or changed in form best prepares the ore for cyanidation. The acid consumption will vary with the percentage of manganese and other soluble constituents. Neither gold or silver is dissolved by this acid treatment. The washed residue gives maximum cyanide dissolution of the gold and silver with minimum loss of cyanide,"

May 1, 1928

By George S. Koch

In preparing diamond-drill core samples for assay at the Homestake mine, Lead, S. Dak., 5-foot intervals of core are processed through three stages, crushing, grinding, and pulverizing, and portions of the core material are discarded after splitting at each stage of preparation. Then two 1-assay-ton fractions are taken from the pulverized material and assayed. This report investigates alternative methods of sample preparation. The consequences of crushing, grinding, and pulverizing all rather than part of the core are appraised through the statistical analysis of assay results from 118 5-foot intervals of core. Evidently, a substantial improvement in precision at small additional expense is obtained by grinding most or all of the core before splitting. Pulverizing all of the core would be desirable only if doing-so would cost less than assaying five random splits from each interval. Graphs and tables detail appropriate procedures to obtain specified precisions. The experimental design and methods can be applied to similar problems in preparing core and other geological samples.

Jan 1, 1972

By J. L. Ellenberger

The National Institute for Occupational Safety and Health (NIOSH) has continued the research role of the former US Bureau of Mines (USBM) to engineer techniques that will reduce the hazards in the mining workplace associated with coal bumps. Recent research focused on a longwall coal mine in Utah with overburden greater than 750 m (2,500 ft) containing several massive sandstone units. The primary field instrumentation at the site was three-dimensional, full waveform, autonomous microseismic arrays placed underground and on the surface in order to surround the active multi-panel longwall district. The purpose of these arrays was to help investigate the strata mechanics associated with the redistribution of stress and the associated gob formation of the longwall. Specifically, the seismic arrays were used to determine the timing and location of the failure in the strata surrounding the active mining. Overall 13,000 seismic events were detected and located with on-site processing during the five months the panel was being mined, including a magnitude (ML) 4.2 event. Of these, a smaller subset of 5,000 well-located events was selected during post-processing to form a consistent data set for analysis in this paper. From this data set, it was observed that the seismic events generally occurred in advance of the longwall face, both above and below the panel, consistent with failure of the strata in the forward stress abutment zone. Also, the occurrence of the ML 4.2 seismic event within 150-180 m (500-600 ft) of a deep cover longwall face with no associated bump caused a re-evaluation of the nature of the connection between seismic activity and coal bumps.

Jan 1, 2002

By Erica E. Hall, Robert H. Peters, Charles Vaught, Jon C. Volkwein

Coal Workers Pneumoconiosis is the leading cause of death due to occupational illness among coal miners. This disease is caused by miners’ exposure to respirable coal mine dust. A Personal Dust Monitor has recently been developed to provide near real time feedback to miners regarding the number of milligrams of respirable coal mine dust in the air they breathe. This paper was prepared by the National Institute for Occupational Safety and Health to document coal miners’ reactions to this new device, and how they make use of the information it provides. Structured interviews were conducted with 30 coal miners at four mines. A four-stage conceptual model of miners’ decision processes with respect to how they interpret and respond to the dust exposure numbers from their personal dust monitor is proposed. The stages are: Diagnosis, Action Planning and Intervention, Evaluation, and Institutionalization. The interview responses provide considerable support for the model. Most miners paid attention to Personal Dust Monitor feedback and made efforts to reduce their dust exposure. Their efforts included: changing where they positioned themselves, making ventilation system improvements, and using respirators more often. The 29 miners who reported having experience wearing both the old and new type of dust monitors were asked which dust sampling system they preferred. Eighteen (62%) preferred the new monitors, 7 (24%) preferred existing monitors, and 4 (14%) had no preference. The most frequently cited advantage of the new monitor is its ability to provide relatively quick feedback on dust exposure. Miners provided several suggestions for improving the design of the instrument.

This study presents a reservoir modeling approach to investigate the relative effects of different coalbed parameters on the migration of methane into development entries. A base coalbed reservoir model of a three-entry development section, where grids were dynamically controlled to simulate the advance of mining at a constant section advance rate, was created and calibrated for a Pittsburgh Coalbed mine in the Southwestern Pennsylvania section of the Northern Appalachian Basin. The values of coalbed parameters were varied to evaluate their effects on predicted methane emissions for various development distances. The results of these parametric simulations were then used to derive linear expressions relating these parameters to methane emissions into the workings. These models were analyzed to assess their significance and adequacy for predictive purposes. This work shows that coupling reservoir simulations with linear modeling yield a technique that can be applicable to different coalbeds. The reservoir parameters used by the linear models (coalbed thickness, pressure, sorption time constant, Langmuir parameters, permeability) can be determined by running relatively simple laboratory tests, such as adsorption equilibrium and permeability determination, on coal samples obtained either from the mining operation or from the exploratory boreholes drilled ahead of mining.

Jan 1, 2008

By Willard L. Hunter

The separation of tantalum and columbium by solvent extraction was under-taken as part of the Bureau of Mines research program to improve methods for extracting, separating, and reducing these elements to metal. The diethyl ketone aqueous HCl-HF system was one of several systems studied to determine the effect of metal and acid concentrations in aqueous solutions upon the transfer of tantalum and columbium into selected ketones. The tantalum-columbium oxide mixture used in this investigation was obtained by chemical extraction from Geomines slag. The investigation showed that tantalum 99.4 percent pure and columbium 97.2 percent pure can be produced by the selective transfer of tantalum into diethyl ketone from a solution of 2-N HF and 1-N HC1. The relatively low acid concentration necessary for tantalum transfer and the excellent selectivity of the system recommend its use for the separation of tantalum and columbium.

Jan 1, 1961

By James D. Sisler

Location and Age The main bituminous coal field of Pennsylvania lies in approximately twenty counties west of the mountain area which extends in a northeast southwest direction through the central part of the Commonwealth. The coal fields lie in a dissected peneplain, still in the youthful stage of erosion There are numerous V shaped valleys in the bituminous fields and the tributaries of the larger streams have rather steep gradients The main streams flow in rather narrow valleys with comparatively small flood plains. The coal beds of Pennsylvania are of Carboniferous age, and are confined to two systems, the Permain and the Pennsylvanian The latter system is divided into an upper or Pittsburgh series and a lower of Pottsville series The Peimain system is divided into an upper and lower series The Pottsville series of the Pennsylvanian is represented in western Pennsylvania by the Upper Pottsville only The upper or Pittsburgh series of the Pennsylvanian is represented by the Monongahela, Couemaugh, and Allegheny groups Geologic Structure. The rocks of the bituminous coal fields are folded into many anti clines and synclines extending in a general northeast direction across the western part of Pennsylvania The intensity of this folding in creases toward the mountain region West of Chestnut Ridge, which is in Fayette, Westmoreland, and Indiana counties, the folding is minor, and the coal beds have low dips East of Chestnut Ridge, v here folding is stronger, the basins are wider and the coal beds rise steeply on the flanks of the anticlines Geology. The bituminous coals of Pennsylvania are associated with shale, sandstone, clay, and limestone Each group has different proportions of these deposits, and the proportions vary at different localities within the same group.

Jan 1, 1928