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By E. E. Remmenga

Often a collection of analytical data, which should reasonably be expected to follow the normal distribution, contains too many extreme values, which the experimenter is inclined to eliminate according to some arbitrary procedure. The stepwise computer procedure described for this purpose is similar to many other truncation procedures; however, because truncation of a basically normal distribution causes a downward bias in the estimated variance, this procedure provides a graphical method to compensate for the bias.

Jan 1, 1971

To recover metals as sulfide concentrates from contaminated waste streams using hydrogen sulfide (H2S) generated by the bacterial digestion of waste organic materials. Approach The goal of this research is to develop a treatment method for metal mine effluents that will rival the cost and convenience of conventional lime treatment, and that will provide better effluent water quality, result in less expensive sludge disposal, and allow for the selective recovery of metals.

Jan 1, 1993

By Manuel Gomez

Prediction models were constructed for seam elevation, overburden, and sodium concentration for a lignite deposit in Ward County; N. Dak. These models were developed by mathematical-statistical techniques using surface coordinates as independent variables to permit interpolation between drill holes. The results suggest that sodium concentration in lignite may be predicted in advance of mining. This information is helpful to mine planning, specifically, in scheduling production to deliver a uniform product to existing powerplants.

Jan 1, 1970

By Martin Harper

This paper concludes a five year program on research into the use of a portable X ray fluorescence (XRF) analyzer for analyzing lead in air sampling filters from different industrial environments, including mining, manufacturing and recycling. The results from four of these environments have already been reported. The results from two additional metal processes are presented here. At both of these sites, lead was a minor component of the total airborne metals and interferences from other elements were minimal. Nevertheless, only results from the three sites where lead was the most abundant metal were used in the overall calculation of method accuracy. The XRF analyzer was used to interrogate the filters, which were then subjected to acid digestion and analysis by inductively coupled plasma optical emission spectroscopy (ICP OES). The filter samples were collected using different filter holders or "samplers" where the size (diameter), depth and homogeneity of aerosol deposit varied from sampler to sampler. The aerosol collection efficiencies of the samplers were expected to differ, especially for larger particles. The distribution of particles once having entered the sampler was also expected to differ between samplers. Samplers were paired to allow the between sampler variability to be addressed, and, in some cases, internal sampler wall deposits were evaluated and compared to the filter catch. It was found, rather surprisingly, that analysis of the filter deposits (by ICP OES) of all the samplers gave equivalent results. It was also found that deposits on some of the sampler walls, which in some protocols are considered part of the sample, could be significant in comparison to the filter deposit. If it is concluded that wall deposits should be analyzed, then XRF analysis of the filter can only give a minimum estimate of the concentration. Techniques for the statistical analysis of field data were also developed as part of this program and have been reported elsewhere. The results, based on data from the three workplaces where lead was the major element present in the samples, are summarized here. A limit of detection and a limit of quantitation are provided. Analysis of some samples using a second analyzer with a different X ray source technology indicated reasonable agreement for some metals (but this was not evaluated for lead). Provided it is only necessary to analyze the filters, most personal samplers will provide acceptable results when used with portable XRF analysis for lead around applicable limit values.

Jan 1, 2007

By W. J. Fene, H. B. Humphrey, J. J. Forbes

"INTRODUCTION Loss of life from coal-mine explosions in the United States in 1949 was the lowest in any year since before 1870. Although fatality reports from coal nines before 1910 were incomplete,' the explosion fatalities from single disasters or individual States exceeded the 1949 total in each year as far back as 1870, when the records become fragmentary. Since 1890, the only other year in which fewer than 35 were killed was 1946, with a total of 32. Figure 1 shows the total yearly fatalities from explosions in all coal mines and those in anthracite mines alone since 1870. The fatalities in bituminous coal mines were not completely reported before 1910, but enough reports were issued by major coal-producing States to compile reasonably representative figures back to 1885. Any corrections would be additions to these totals.The reason for the moderate total of 46 explosion fatalities in 1948 and the low total of 8 killed in 1949 is thought to be the serious and careful attention devoted to elimination of coal-mine explosion hazards after the disastrous explosions in 1947. The standards now being observed generally with respect to ventilation, rock-dusting, and inspections for gas are better than those found earlier in even the mines having the best reputations for safety. Exceptions are still numerous, but they are fewer, month by month, because of the pressure of Federal and State inspections and a changing conception of the hazards that should not be permitted underground. The prevailing precautions have not eliminated all ignitions of gas or dust, but they have limited propagation to small explosions and have prevented serious loss of life.The number of ignitions (14) reported for the year was less than the average (24) for the 5 years 1944-48 and only half the average for the fiscal years 1929-44. Another favorable factor is that Bureau of Mines representatives were probably in closer contact with both small and large mines in nearly all coal-mining districts. Inspectors now assigned to individual districts are better able to keep informed on the happenings and the progress of safety in their districts. In 1948, one-fourth of the explosions were in mines that employed fewer than 10 men; this condition was duplicated in 1949."

Jul 1, 1950

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

The usual run time errors occur when illegal mathematical operations are attempted by MFIRE For exam¬ple, if the user enters a negative value for the input variable HEAT to model a heat sink or cooling station, a run tame error will occur because an exponential function is employed to better model the changing temperature dis¬tribution in the airways. DATA FILE ERRORS Two types of data file errors can occur. 1 An error may occur because the input data file itself is invalid This may be caused by: The data file cannot be found due to incorrect spelling, drive, or path specification Check the spelling and path at the prompt for location of the data file. The data file contains non-ASCII symbols Check op¬eration of the text processor to insure that only ASCII characters are produced Delete all non-ASCII and/or all out of place characters. 2 Data are accepted by the program, but are incorrect for the data types or ranges or the combination causes a data inconsistency This may be due to. An invalid character is located where a numerical value is required The input data value is outside the reasonable range The input data is insufficient to build the model for simulation. The input data exceeds the capacity of the program. PROGRAM ERROR DETECTION When the program is running, tracing messages are given on the screen indicating the group and lines of data that have been read and the section of the program that is executing Program termination indicates that problems are caused by the subsequent (not read) data file section. For each detected error, descriptive message starting with * ERROR * is issued and the program terminates. When a possibly wrong value and/or its calculated intermediate result is detected, a descriptive message starting with * WARNING * is issued and the program continues. If a modification of input value or calculated intermediate result is automatically made by the program, descrip¬tive message starting with * ATTENTION * is issued and the program continues. LOCATING ERRORS If a message indicates that the error condition occurred due to the data input file, locate and correct the data item. If no error message is issued, but the simulation results are not as expected, carefully check the list of input data shown in the output file WARNING messages and ATTENTION messages may reveal an error in the input data even though the program continues to operate Insure that the default values or modifications adopted by the program run are acceptable. Anomalistic data, though not incorrect or impossible, may lead to an unusual simulation For example, making a fan unusually powerful may prevent a normal strength fire from affecting the airflow distribution in the system Much care must be employed before considering an ex¬treme case. If a message indicates that the accuracy criterion in the temperature section of the program was not satisfied, a table detailing the current parameters of airways which have large fluctuation in the average air temperature from iteration to iteration is produced If the pattern of the parameters is clearly cyclical, while the variation of natural ventilation pressure is stable or cyclical from iteration to iteration, then, most likely there is no single equilibrium stage for the event If the variation of natural ventilation pressure decreases steadily though slowly, increasing the value of data item variables MADJ or ITN (on control line number 1) may allow convergence.

Jan 1, 1990

Surface mining of coal involves removing soil and rock that overlay coal beds in order to expose the coal. Compared to underground coal mining, surface mining generally costs less, is safer for miners, and usually results in more complete recovery of the coal. However, it also results in much more extensive, though temporary, disturbance of the land surface, which can cause serious environmental problems unless the mined land is carefully reclaimed. The earliest commercial U.S. coal production was in the anthracite region of Pennsylvania. Beginning in 1807, mining became important enough for the federal government to begin keeping statistics on annual production. During those early years of coal mining, reclamation of mine sites and Support facilities was not required by law; however, in the 1930's, as surface mining became more widespread, the idea of mandatory environmental protection and reclamation started to grow. In 1939 West Virginia enacted the first law to regulate the coal mining industry. Similar laws were enacted by Indiana in 1941, Illinois in 1943, and Pennsylvania in 1945. During that period, coal production accelerated greatly and the surface mining of coal became much more prevalent. During World War 11, the demand for coal took priority over environmental concerns, with little consideration for reclaiming the land after mining. Mining pits were not backfilled. Dangerous highwalls were left exposed. Trees and other vegetation were buried by waste material that was simply dumped down the slopes below mines. Topsoil was buried or allowed to wash away. Landslides formed on unstable hillsides. Slopes eroded rapidly because of the lack of vegetation. Polluted water collected in mine pits. Streams became clogged with sediment. Streams and rivers were frequently polluted by acid mine drainage. This vivid image of surface coal mining remains indelible in the minds of most Americans, who remain unfamiliar with modem surface coal mining methods and the changes brought about by the Surface Mining Control and Reclamation Act. After 1945, more coal-producing states instituted regulatory pro- grams. Many required permits for mining. Some included inspections. A few made operators post performance bonds to guarantee reclamation when mining was completed. However, due to the variations in those individual programs, it cost less to produce coal in states with less stringent reclamation requirements, giving operators in those states an economic advantage, generally at the expense of environmental quality. With the 1970's came a surge in the demand for coal resulting from the nation's need for increasing electric power generation and the uncertain supply and increased cost of imported petroleum-based fuels. The resulting increased coal production prompted a series of state laws, primarily in the West, aimed at controlling the environ- mental effects of surface mining. During the late 1960's and early 1970's, North Dakota, Wyoming, Colorado, and Montana passed laws to regulate mining and reclamation. The continuing lack of uniformity among the state surface mining programs and the increase in unreclaimed land and associated pollution of water and other resources caused a growing demand for nationwide regulation of surface coal mining, both to remove the economic inequities and to is sure an acceptable standard of reclamation. After many years of debate, Congress passed the Surface Mining Control and Reclamation Act (SMCRA), which was signed into law August 3, 1977. The Act established a coordinated effort between the states and the federal government to prevent the abuses that had characterized surface coal mining in the past. The law also applied to surface disturbances created by underground coal mining.

Jan 1, 1992

By L. C. IlsLey, M. W. Means

The United States Bureau of Mines under provisions of Schedule 20 issues approvals covering complete operating units such as loading machines, room hoists, and storage-battery locomotives. Certain manufacturers design and build entire machines. Other manufacturers purchase a part or all of the electrical accessories from manufacturers of electrical equip- ment and assemble them, thereby making up a permissible unit. Before the assembler purchases electrical accessories for use in such contempla.ed units he may require certain information from the accessory manufacturer as to whether these par- ticular accessories are suitable for assembly in his proposed permissible outfit. In order to aid accessory manufacturers in marketing their product, a provision was incorporated in Schedule 20 whereby tests might be made on individual accessories and reports rendered as to the suitability of a given accessory for use in permissible assemblies. The section of Schedule 20 which permits this special work reads as follows:

Jan 1, 1932

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

The PC version of the program MFIRE contains many improvements and enhancements previously unavailable for the modeling of mine ventilation networks and the interaction of fires with mine ventilation Transient-state simulation with dynamic modifications of the ventilation system and mine, the fire, and resulting POC transport and ventilation alterations are accommodated with MFIRE. MFIRE is more flexible and provides more error checking, and more informational messages about prob¬lems with input files than its predecessor, the MTU-BOM code The desirable features of the MTU-BOM code such as calculation and identification of recirculation, the air to rock heat exchange, and the basing of calculations on mass flow rates have been retained. MFIRE is useful for the planning and analysis of ven¬tilation networks, simulation for emergency planning, and the evaluation of fire detector layout Inquiries relating to this program should be directed to the Bureau of Mines, Twin Cities Research Center, 5629 Minnehaha Avenue South, Minneapolis, MN 55417

Jan 1, 1990

By J. V. Batty, K. C. Dean, H. D. Snedden, W. J. Long

As a part of the investigation of strategic-mineral deposits in the United States under the Strategic Minerals Act, engineers of the Bureau of Mines examined and sampled numerous deposits of fluorite ore from Utah. From those deposits that warranted further investigation, samples were submitted to the Ore Dressing Section of the Salt Lake City Station for metallurgical testing. This paper gives data summarizing the results obtained from laboratory ore-dressing studies of the fluorite ores submitted. Test work was done on samples from four properties in the Washington Mining District, Beaver County; two properties in the Star Mining District, Beaver County; one property in the Wah Wah Mountains, Beaver County; and three properties in Tooele County, Utah. In general, the Washington District ores were found amenable to concentration by flotation for the production of acid-grade fluorspar. None of the other ores were beneficiated to acid-grade, but several were amenable to concentration for the production of metallurgical-grade fluorspar concentrates.

Dec 1, 1947

By Richard F. Link, George W. Gladfelter, George S. Koch

Contour maps, useful in mineral industries, for example, in analysis of trends in mineralization, may be constructed through statistical methods of regression analysis programed for an electronic computer, For many applica­tions, the resulting maps are more useful and objective than conventional contour maps that are necessarily subjective because they are drawn by hand methods. In principle, an equation is found that fits a quadratic surface to observed elevations of points referred to a datum plane, The quadratic sur­face, represented by a contour map may take the form of a ridge, valley, dome, or basin, Once an equation has been derived, its coefficients may be used to construct a contour map--showing lines of equal value that are derived from the original observed data points by the averaging process of fitting the quadratic surface. Methods employed are illustrated by an example analysis, based on data from a large vein of the Fresnillo mine, Zacatecas, Mexico. Computer programs to implement the methods are described in an appendix,

Jan 1, 1964

By J. V. Batty, K. C. Dean, H. D. Snedden, W. J. Long

As a part of the investigation of strategic-mineral deposits in the United States under the Strategic Minerals Act, engineers of the Bureau of Mines examined and sampled numerous deposits of fluorite ore from Utah. From those deposits that warranted further investigation, samples were submitted to the Ore Dressing Section of the Salt Lake City Station for metallurgical testing. This paper gives data summarizing the results obtained from laboratory ore-dressing studies of the fluorite ores submitted. Test work was done on samples from four properties in the Washington Mining District, Beaver County; two properties in the Star Mining District, Beaver County; one property in the Wah Wah Mountains, Beaver County; and three properties in Tooele County, Utah. In general, the Washington District ores were found amenable to concentration by flotation for the production of acid-grade fluorspar. None of the other ores were beneficiated to acid-grade, but several were amenable to concentration for the production of metallurgical-grade fluorspar concentrates.

Dec 1, 1947

By R. V. Ramani, A. S. C. Owili-eger

The Methane Generator program is a part of the Internal Environ¬mental Sub-system of the Master Design Simulator (MDS). All the sub¬systems of the MDS are controlled and activated by the main program as required. The data requirements for the Methane Generator are supplied by the Geology and Reserves sub-system through common storage. Figure 6 shows the information flow between the Methane Generator and other systems of the MDS. It should be noted that the Methane Generator can also function independently as was described under model application. AREAS OF MISSING INFORMATION In any numerical analysis, the accuracy of the solution depends entirely upon the data available. In gas flow problems, parameters that constitute basic model input data are rock porosity, medium permeability, reservoir pressure and initial reservoir pressure dis¬tribution. Unfortunately, however, most of these characteristics are not available for a lot of coal seams. The need for actual field data cannot, therefore, be adequately emphasized here.

Jan 1, 1974

By M. Terry Hoch, George J. Karabin, James M. Kramer

This paper introduces the fracture mechanics approach—a unique way to predict the stability of a coal mine panel. The technique uses analytic equations to calculate the stress, strain, and yield characteristics of coal support systems. It uses fracture mechanics to model almost every type of mine support structure. Another feature is a method that incorporates field-tested knowledge into the analytical analysis. For example, this technique can model the yield characteristics of a coal seam by combining empirical pillar strength equations into the analytic analysis. It may be possible to simulate multiple-seam mining by incorporating subsidence methods into the analysis. The method is simple and quick, which makes it attractive for stress analysis software. It should be more accessible to those in the mining industry who do not have expertise in rock mechanics or numerical modeling. Although the purpose of this research is for modeling coal mines, it should be adaptable to any mine in a tabular deposit.

Jan 1, 1999

By J. A. Eisele

As part of its goal of maintaining an adequate supply of minerals to meet national economic and strategic needs, the Bureau of Mines has studied the removal of iron from simulated aluminum nitrate leach liquors by solvent extraction. Iron must be removed from aluminum nitrate liquor produced by leaching calcined kaolinitic clay with HN03 to reduce the iron level in alumina to less than 0.02 wt-pct Fe203 for use in reduction cells. The parameters reported are for (1) extracting iron from a feed containing 1.5 g/l Fe with di(2-ethylhexyl) phosphoric acid (EHPA), (2) stripping loaded organic phase with 20-pct HCI, and (3) water washing of loaded and stripped organic phase. Recommended operating conditions are two extraction stages using 15 vol-pct EHPA in kerosene and three stripping stages using 20-pct HCI. Results are also given for tests using other extractants and stripping agents.

Jan 1, 1982

By Ben A. Kornhauser

Petroleum production was the principal component of the mineral industry, followed by cement production and some salt output. The French Central Fund for Economics Cooperation loaned $9.15 million2 to the Communauté Electrique du Benin (CEB), which served Benin and Togo, toward financing the construction of a dam on the Mono River at Nangbeto, Togo. The dam was to supply hydroelectric power to reduce the energy dependence of the two countries and to irrigate crops. Nine other international financial organizations, including the International Bank for Reconstruction and Development (World Bank). the African Development Bank, the Arab Bank for African Economic Development, and the French Aid and Cooperation Fund, contributed to the estimated $140 million cost of the dam. The CEB also was to contribute to the financing. Contracts amounting to $60 million already had been awarded to West German and Canadian firms. The dam was expected to be completed in 1987.

Jan 1, 1986

By P. R. Bremner

The United States is more than 90 pct dependent on imported bauxite a source for aluminum, but it has vast nonbauxitic aluminum resources, such as kaolinite, anorthosite, alunite, etc. As part of a program to devise processes for treating these resources, the Bureau of Mines investigated a bench-scale leaching process using hydrochloric acid (HC1) and fluoride to extract aluminum from Wyoming anorthosite. HC1 and fluoride-to-aluminum (F/Al) mole ratios were studied with respect to aluminum extraction for single-stage, cocurrent, and countercurrent leaching modes. Using 95 pct stoichiometric HC1 and a F/Al mole ratio of 0.27, 90 pct of the aluminum was extracted by countercurrent leaching. Single-stage leaching with the same amount of acid and fluoride extracted 48 pct of the aluminum. Three fluoride sources, CaF2, Na2SiF6, and H2SiF6, were used and gave similar results on aluminum extractions.

Jan 1, 1982

By P. D. Laverty

The U.S. Bureau of Mines treated mixed and contaminated super alloy scrap by pyrometallurgical and hydrometallurgical methods to separate and recover metal values. Best results were obtained by leaching Zn-treated or atomized scrap with HCI-02 at 9SO C and 50 psig 02' This resulted in dissolving approxi-mately 98 pet of the AI, Co, Cr, Cu, Fe, Mn, Ni, and Zn while rejecting over 98 pct of the Mo, Nb, Ta, Ti, W, and Zr as an insoluble refractory residue. Chlorine was successfully substituted for HCI to leach Zn-treated scrap but was unsuccessful for leaching atomized scrap. The leaching solution was treated by pH adjustment and hydrothermal precipitation at 2000 C for 4 h to remove AI, Cr, Fe, and other contaminants as a filterable precipitate. Recovery of Co and Ni would be accomplished by solvent extraction and e1ectrowinning. Chromium recovery as a ferroalloy was demonstrated.

Jan 1, 1989

Develop design and support guidelines for coal mine entry intersections based upon results of integrated field and numerical modeling analyses of structural parameters for improving ground stability. Background Underground coal mines contain a large number of entry intersections. Dome-shaped zones over the intersections are unstable and are often associated with roof falls. These roof falls may occur during mine development, trapping equipment and endangering miners. These high-risk areas of the mine account for 10 pct of the total number of ground-failure-caused fatalities. The falls, ranging from heights of 1 to 20 ft, cause high dilution and slow the advance rates. Stability at intersections is influenced by four structurally interrelated parameters: in situ stress, geological discontinuities and physical properties, intersection geometry, and roof span. Because of the complex interaction of these parameters, the actual mechanism of roof failure may vary considerably, depending upon the roof lithology, rock strength, and stress conditions.

Jan 1, 1990

Provide sound battery safety guidelines for mine workers who maintain mobile surface mining equipment. Approach Battery-related accidents account for about 5 percent of all nonfatal disabling injuries in coal and metal nonmetal surface mines. These accidents occur despite the fact that appropriate battery safety technology (maintenance-free batteries, cable removers, fault detectors, hot-jumping systems, etc.) exists. Mine operators are not always aware of the safety measures that could be taken because this safety information is widely scattered in numerous unrelated technical reports, vendor brochures, and journal articles. A literature search of these reports and a review of relevant industry standards, handbooks, and references on battery safety, followed by discussions with mining company and MSHA personnel, provided the Bureau of Mines with the background necessary to develop procedures for proper and safe battery usage. These procedures were condensed and written in nontechnical language to serve as guidelines in assuring battery safety during maintenance of mining equipment.

Jan 1, 1986