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By Henry Kreisinger, John Blizard

This preliminary statement presents some of the results of tests carried out at the Lakeside Station of the Milwaukee Electric Railway and Light Co. , by the fuel section of the U. S. Bureau of Mines , in cooperation with the research department of the Combustion Engineering Corporation of New York . The object of these tests was to determine the thermal efficiency , ease of operation , and other particulars of a boiler equipped with specially designed furnace and burners for burning powdered coal . The boiler tested haş 13380 square feet of heating surface , and is one of eight boilers equipped with the Lopulco powdered coal system supplying steam to two 20,000 -Kw . steam turbines in the largest power house burning powdered coal . Twenty- six tests were run at rates of heat transference varying from 4000 to 8000 B.t.u. per square foot of boiler heating surface , and the mean thermal efficiency attained was about 84 per cent , based on the gross calorific value of the fuel as fired . The efficiency varied little with the rate of steaming , and its high value is accounted for by the small loss from incomplete combustion and the small amount of excess air which varied from 5 to 36 per cent . The coal burned had a gross calorific value of about 11500 to 12800 B.t.u. per pound , contained 2 to 5 per cent moisture , 33 to 36 per cent volatile matter and 9 to 13 per cent ash, and was so ground thaf 89 to 95 per cent would pass through a 100- mesh sieve . The ash had a softening point of 2150 to 2450 degrees F. , but did not fuse together at the bottom of the furnace because it was partly protected from the flame radiation by means of a series of water tubes connected to the boiler which were placed between the fumace bottom and the flame, ..

Jan 1, 1923

By Fred N. Kissell, Jon C. Volkwein

In This Chapter [How inert gas works to prevent methane explosions How inert gas is generated and delivered at highwall mines Volume and quality requirements for inert gas at highwall mines How an inert gas system is operated and Precautions to take during mining to prevent methane explosions] This chapter discusses a method, originally developed by Volkwein and Ulery [1993], to prevent methane explosions during highwall mining. In highwall mining, a horizontal auger or a mining machine enters the coal seam from a surface mine pit at the bottom of a highwall, and the coal is mined out from a series of parallel holes. Explosions can be prevented by injecting inert gas into each hole as it is mined. Coal near the surface has lost most of its methane gas over time. However, in recent years, surface mining has been used for deeper reserves of coal. This trend toward mining deeper reserves has increased the chance of encountering methane, and methane explosions at highwall mining operations have resulted in injuries. HOW INERT GAS WORKS TO PREVENT METHANE EXPLOSIONS A methane explosion requires the presence of sufficient amounts of both methane and oxygen, as well as an ignition source. If the methane cannot be reduced and the ignition source cannot be eliminated, then explosions may be prevented by adding an inert gas, which contains little to no oxygen, to the mixture [FWQA 1970]. Just how much inert gas must be added depends on the mining rate, as well as the composition of the inert gas. An explosibility diagram can be used to show whether a methane mixture is explosive after inert gas is added [Zabetakis et al. 1959] (Figure 10–1). This diagram indicates that gas mixtures fall into one of three range categories—explosive, explosive when mixed with air, and nonexplosive—depending on the percentage of methane and percentage of “effective inert.” Effective inert is calculated from the percentage of “excess nitrogen”3 and percentage of carbon dioxide in the mixture.

Jan 6, 2006

By Joseph T. Singewald

The term "titaniferous magnetite" is used to designate those mag- netic ores of iron that carry more than 2 or 3 per cent of titanium. Large and easily workable deposits of these ores occur in different parts of the world, and have attracted attention for many years. Under present furnace practice, however, the smelting of these ores is both difficult and expensive, and for that reason they are not accepted by furnaces, so that the deposits are practically worthless. The problem of finding a feasible method of utilizing these ores has naturally been attractive, and numerous attempts have been made to solve it. Experiments to that end embrace two lines of investigation. The one that has been the more frequently tried is the elimination of the titanium from the ores, so as to make possible their smelting in the usual way. The other is the devising of a method of smelting by which titaniferous ores may be reduced as economically as are non- titaniferous ores. The former method involves a physical process, the latter a chemical process. The measure of success attainable by the first method depends entirely on the relations between the iron and the titanium in the ore. Views in regard to these relations have been divergent. Some investi- gators have believed the titanium to occur as a part of the magnetite molecule, in which case, of course, any process of mechanical separa- tion would be impossible. Others have believed that the titanium occurs as the mineral ilmenite, and that the ores are aggregates of magnetite and ilmenite. In this case a separation of the two minerals is theoretically possible. Magnetite is highly magnetic; ilmenite is nonmagnetic or only feebly magnetic. Crushing and magnetic con- centration should separate them. Numerous experiments in mag- netic separation have been made with various degrees of success, but rarely has more than a very imperfect separation been obtainable. In other words, some of the titanium exists in a separable form and some in an inseparable form, and the ratio between the two forms is

Jan 1, 1913

By Donald P. Tuchman, Robert P. Vinson, Steven J. Page, Linda J. McWilliams, Gerald J. Joy, Steven E. Mischler, Jon C. Volkwein

The United States National Institute for Occupational Safety and Health, through an informal partnership with industry, labor, and the United States Mine Safety and Health Administration, has developed and tested a new instrument known as the Personal Dust Monitor (PDM). The new dust monitor is an integral part of the cap lamp that coal miners normally carry to work and provides continuous information about the concentration of respirable coal mine dust within the breathing zone of that individual. Previous laboratory testing demonstrated that there is a 95% con?dence that greater than 95% of individual PDM measurements fall within ±25% of reference measurements. The work presented in this paper focuses on the relationship between the PDM and respirable dust concentrations currently measured by a coal mine dust personal sampler unit utilizing a 10 mm Dorr Oliver nylon cyclone. The United Kingdom Mining Research Establishment instrument, used as the basis for coal mine respirable dust standards, had been designed speci?cally to match the United Kingdom British Medical Research Council (BMRC) criterion. The personal sampler is used with a 1.38 multiplier to convert readings to the BMRC criterion. A strati?ed random sampling design incorporating a proportionate allocation strategy was used to select a sample of mechanized mining units representative of all US underground coal mines. A sample of 180 mechanized mining units was chosen, representing approximately 20% of the mechanized mining units in production at the time the sample was selected. A total of 129 valid PDM/personal sampler dust sample sets were obtained. A weighted linear regression analysis of this data base shows that, in comparison with the personal sampler, the PDM requires a mass equivalency conversion multiplier of 1.05 [95% C.I. (1.03, 1.08)] when the small intercept term is removed from the analysis. Removal of the intercept term results in a personal sampler equivalent concentration increase of 2.9% at a PDM measurement of 2.0 mg m-3.

By Thomas O. Glover

Economic growth in Cameroon was restricted during 1987 owing to a decrease in oil prices during 1986 and the falling value of the U.S. dollar in 1987. The yearly budget reflected a significant drop in revenues and expenditures. Taxes on imports and some exports were increased to raise revenue. The shortage of revenue and the lack of liquidity had restricted the Government's operation and investment programs. External public debt reached an estimated $3.2 billion2 representing 20.8% of the estimated gross domestic product (GDP) of $12.3 billion. The Government operated at an 8.7% deficit in 1987. The GDP growth rate had fallen to 0.6% in 1987 and was projected to remain at that level in 1988. Economic planning was managed through a series of 5-year plans. The country was under the sixth 5-year plan, which would end in 1991. The plan stressed balanced development as one method to achieve the desired results. Sources of revenue for the year included direct and allied taxes (31.2%). customs collections (31.0%), and oil royalties (28.0%). The oil royalties in 1987 represented a larger part of the budget than in 1986. In January 1987, eight African oil exporting countries, including Cameroon, formed the African Petroleum Producers' Association (APPA). The eight countries represented about 80% of the total African oil production of 5.2 million barrels per day in 1987. Cameroon produced approximately 3% of total APPA oil production. Cameroon produced approximately 68.5 million barrels of crude oil in 1987, slightly less than that produced in 1986. Earnings also fell in 1987, not only from falling production, but also from declining oil prices and the fall in value of the U.S. dollar on world markets. Oil had been the main stimulus of Cameroon's growth throughout the past decade, and a key generator of export revenues and financial resources for the economy.

Jan 1, 1989

By C. A. Herbert

"The Bureau of Mines for a number of years has conducted experiments at its experimental mine near Bruceton, Pennsylvania, on the explosibility of coal dust, with particular reference to dust explosions in coal mines, and the knowledge so rained may well be applied to the handling of coal dust at industrial plants and elsewhere.Powdered coal is coming into use more and more as a fuel, and the dangers incident to its use should be recognized and guarded against, as a number of accidents have occurred in recent years due to ignorance of this danger or to carelessness.Within the past three years two very serious accidents, under almost identical circumstances, have occurred on the surface at two different coal mines in Southeastern Iowa, due in each case to the sudden ignition of a cloud of fine coal dust.The first accident resulted in the burning of six men, three of them fatally; the second burned eleven; three men died as a result of their burns.The mines in the Southeastern part of Iowa, where these two disasters occurred, are operating in a thin coal bed averaging about three feet in thickness, and are worked on the long-wall advancing system similar to that of Northern Illinois.The miners in this section are paid on a screened coal basis; in other words, receive no pay for the fine coal. As a result they use forks in loading the coal into the mine cars, and naturally a considerable quantity of coal is left along the roadways. Subsequently this fine coal, together with the roof rock that is taken down to give sufficient height on the roadways, is loaded into cars and dumped in piles on the surface. This roof rock is a block, oily shale and the contribution of fine coal and oil shale gives ample combustible material to thoroughly burn the rock as it is dumped."

Jul 1, 1923

By Maria I. De Rosa

Table 46 and figure 16 show the number of fires and fire injuries for metal/nonmetal mills by state during 1990-2001. Table 46 also shows the injury risk rates, employees' working hours, and lost workdays. In all, 77 fires occurred in 26 states. Thirty-seven of the fires caused 41 injuries and 1 fatality (including 5 fires and 3 injuries involving contractors). The yearly average was 6.4 fires and 3.4 injuries. Fifty-four fires with 26 injuries and 1 fatality occurred at metal mills; 23 fires with 15 injuries occurred at nonmetal mills. The Ewhr value was 845 x 106 hr (Irr = 0.01), and the LWD value was 6,681. Minnesota had the most fires (16 fires and 5 injuries), followed by Arizona (9 fires and 3 injuries), Wyoming (8 fires and 3 injuries), Nevada (7 fires, 4 injuries, and 1 fatality), and Texas (4 fires and 7 injuries). Of these states, Texas had the highest injury risk rate value (Irr = 0.033). Table 47, partly illustrated in figure 17, shows the number of fires, fire injuries, fire fatalities, risk rates, employees' working hours, and lost workdays by time period. The number of fires increased slightly during the second period, then decreased during the remaining periods. The number of fire injuries show a decrease during most of the periods (an increase is seen during the third period), accompanied by a decline in employees' working hours during most of the periods. The Irr values follow patterns similar to those shown by the injury values. Tables 48-53 show the number of fires by ignition source, method of detection and suppression, equipment involved, location, and burning material by time period. Figure 18 shows the major variables related to fires for 1990-2001. Table 54 shows the number of fire injuries per number of fires causing injuries and total fires by year, ignition source, equipment involved, and location.

Jan 1, 2004

By H. M. Lawrence

"In the land-pebble district of Florida a lively interest in the possibilities of obtaining increased recoveries of phosphate rock is evident. Research in several directions is being carried on by companies operating in the district to increase the yields obtained by the washing plants. The Bureau of Mines is cooperating with this research program to promote more efficient plant practice and to avoid unnecessary depletion of mineral resources.Washing practice, as carried on in the district at present for the recover of phosphate rock from the crude ores or matrix, is not a complicated process. Flow sheets of the several companies are similar, although the equipment varies with the preferences of the individual operators. For disintegrating the matrix log washers are favored, although revolving drums equipped with flights to break up lumps of clay are also used. Fine sand is removed by screening. Vibrating screens have become well established in the district, although stationary flat screens and trammels are also employed.The writer acknowledges with appreciation the cooperation of the phosphate companies in the land-pebble district; suggestions and criticism by Will. H. Coghill, supervising engineer, Ore Dressing Section of the Bureau of Mines; and the laboratory assistance of J. O. Davie, J. W. Pamplin, and E. Roca, cooperative fellows of the University of Alabama.Losses in the Finer SizesOf the phosphate that is not recovered by present washing methods the greater portion is in the finer sizes. In these sizes the phosphate grains are accompanied by grains of sand - largely quartz - of the same size, and recovery of these phosphate grains as a commercial product is not possible by simple washing methods. Phosphate recoveries approaching complete extraction can only be effecte by applying metallurgical processes, either mechanical or chemical. As yet, most of these processes have not advanced much beyond the laboratory or perhaps the pilot-plant stage. Such processes may have some application to the beneficiation of phosphatic ores or washer rejects, but a discussion of them is not within the scope of this paper."

Apr 1, 1929

Reduce the hazards to which mine personnel are exposed by providing safer procedures for removing dragline wire rope terminations. Background The termination points of wire ropes used on draglines consist of a wedge and socket that lock the rope in place through friction. These components must be separated when the wire rope is changed. At present, the cannon method is the most common procedure used to accomplish this. However this method, using a small cannon and primer (detonator) cord to propel a steel projectile that will knock the wedge out of the socket, has the potential of causing injuries to mine personnel and damage to equipment. The Bureau of Mines, has devised safer, and equally efficient methods of removing wire rope terminations. The Bureau began by studying the cannon method, its merits and draw-backs. Safety guidelines were then developed for the cannon method, and two alternative methods-the pendulum ram and hydraulic pusher-were devised and tested. The Cannon Method The steel projectile used to separate the wedge and socket in the cannon method was found to be very effective. However, the method poses the inherent hazards of any explosive de-vice-hazards that could be increased by lax work procedures. There is no strict uniformity in the manufacture of the cannon or in the work procedures used in the mines employing it. Hazards could be reduced, or even eliminated, with adaption of certain manufacturing and work-procedure guidelines, such as 1) making the cannon and projectile de-signs, as well the work procedures used, uniform, 2) ensuring separate loading of the charge and detonator with insertion of the detonator through a separate port, 3) connecting electrical firing circuits only after the charge and projectile are loaded and the cannon is placed in its final firing position, 4) using approved detonating devices, 5) anchoring the cannon before firing and, 6) placing armor netting over the cannon before detonation.

Jan 1, 1986

By R. F. Randolph, R. S. Fowkes, J. J. McClelland, G. H. Schnakenberg

Between 1986 and 1992, there were268 deaths and 54,642 severe injuries to workers in underground U. S. mining operations. Clearly, this level of health and safety risk is not acceptable. While most underground coal mining jobs are dangerous, some are much more dangerous than others. Many jobs in an underground coal mine are clustered around the working face—the place where machinery digs coal from the surrounding rock. The hazards in this area are numerous: When the coal is removed, the ground around it becomes unstable and can cave in on the workers. The mining machines used there are large, heavy, powerful, and move in many different directions in a very confined space, presenting danger to workers. Also, the machines churn up coal dust that causes black lung and other ailments. Figure1 shows a modern radio remote controlled continuous mining machine and its operator. In a typical mine, the jobs with the greatest exposure to hazards involve operation of machinery that cuts tunnel-like passages into the coal (the continuous mining machine) and machines that insert supportive steel bolts into the rock above the work area (roof bolting machines). The workers who endure these hazards are at almost twice the risk of death or disabling injury than co-workers in other safer areas of the mine. Of the statistics quoted above, 106 of the 268 deaths and 21,552 of the 54,642 severe injuries occurred in jobs involving equipment at the working face. The operators of roof bolting and continuous mining machines account for only 21% of the work force but suffered 40% of the deaths and 39% of the lost-time injuries during1986-1992. These death and injury rates are almost twice the rate for workers in other underground mining jobs (see figure 2). The estimated total cost of the 106 fatalities and21,552 lost-time injuries was $327 million from 1986-1992. On average, each fatality cost over $1 million and each lost-time injury costs in excess of $9,000.

Jan 1, 1994

By Ronald D. Hill, Elmore C. Grim

Surface mining drastically alters the ecological characteristics of the area disturbed and in some cases has a decided effect on surrounding areas. Vegetation is removed, topographic features and characteristics are changed, and the original geologic overburden profiles are destroyed. Spoil banks generally are a heterogeneous mixture of rock fragments, rock particles, and soil-sized material derived from the overburden strata. With proper mining techniques, the various strata can be partially or completely segregated. Segregation of over- burden material offers the opportunity to bury the toxic, acid, or salt-pro producing strata under growth supporting material. In some situations, lower strata may have more desirable characteristics than surface material and can be placed near or on the surface. For example, limestone strata appear in some lower overburden profiles that have shale and/or sandstone near the surface. Also, some lower strata have higher nutrient levels that have been leached from the surface. Experience has shown that natural revegetation is a very slow process on strip mined areas. Native vegetation may not be compatible with the environment on the mined areas, for example : 1. Low nutrients in the spoil. 2. Toxic spoils (very acid or highly alkaline ). 3. Surrounding vegetation may be of the climax type and may not have pioneer- or primary-invader-type species present. 4. The seed source may be to far away from the adjacent mined areas. Early attempts to revegetate strip-mined lands with trees also proved to be unsatisfactory as they did not provide the initial ground cover required to stabilize the spoil. Erosion control with trees only may take up to 10 years before the canopies close and an effective cover is established. They are slow to form soil profiles and do not provide effective chemical pollution control until long after planting. A quick growing cover of herbaceous species is necessary to obtain quick stabilization and initial protection against erosion by reducing runoff and rain-drop splash. Vegetative cover will also build up a concentration of organic matter in the soil, which in turn will

Jan 1, 1974

By Ren G. Dong, Jay Kim, Daniel E. Welcome, Won Joon Song, Charles Hayden

Prolonged, extensive exposure to hand-transmitted vibration could cause a series of vibration-induced disorders in the vascular, sensorineural, and musculoskeletal structures of the human hand-arm system, which have been collectively called hand-arm vibration syndrome (HAVS).1 To assess the risk of HAVS the international standard ISO 5349-1 (2001)1 recommends using the root-mean-square (rms) acceleration of the measured vibration with a frequency weighting. While a few epidemiological studies have reported results consistent with the predictions made according to the recommendation, many other studies have reported results with large discrepancies.2 This may be partially attributed to the time-averaging effect involved in calculation of the frequency components, especially for impact type tools. Because the spectral characteristics of impact tools change dramatically with time, a time-frequency (T-F) analysis can provide better characterizations of such highly transient vibrations. The analytic wavelet transform (AWT) is an ideal T-F analysis tool because it possesses the advantages of both the Fourier transform and the wavelet transform.3 The objective of this study was to explore the application of the AWT method for characterizing the impact tool vibrations and assessing their exposure risk. Methods Five tools (two chipping hammers, two riveting hammers, and one concrete cutting saw) were used in this study. The saw vibration was measured when it was used to cut a section of road pavement during a repair. The vibrations on the other tools were measured by the procedure specified in ISO 8662-2 (1992).4 A sampling rate of 16,386 Hz was used in the measurement. The AWT and Fourier analysis were applied to these signals and to identify their characteristics. Results Figure 1 compares the T-F characteristics of the accelerations measured from the relatively steady concrete saw and a riveting hammer. The frequency weighting specified in ISO 5349-11 was applied in the calculations. The comparison clearly shows that the two tools have completely different T-F characteristics.

Jan 6, 2006

By C. O. Karacan, S. J. Schatzel, W. P. Diamond

In coal mining, longwall mining is a preferred method to maximize production by extracting large blocks of coal that have been outlined with a set of development entries. In U.S. mines, longwall panels are typically 305 m (1,000ft) wide (with a continual trend towards even wider panels), and usually over 3,050 m (10,000ft) in length. The increasing size of longwall panels, while helping to increase coal production, may also increase methane emissions due to the exposure of the mining environment to a larger area of fractured, gas-bearing strata. Thus, understanding the impact of increased panel widths on methane emissions, and designing gob gas ventholes and bleeder systems accordingly, can enhance the safety of the underground workforce by reducing their exposure to potentially explosive accumulations of methane/air mixtures. As part of its mine safety research program, NIOSH’s Pittsburgh Research Laboratory has initiated a reservoir modeling effort to better understand the interaction of the various geotechnical factors influencing gas flow within and to the underground longwall mining environment. A focus of this modeling effort has been 1) the prediction of the incremental amount of methane emissions to be expected due to increasing longwall panel widths, and 2) optimizing gob gas venthole completion practices to capture more of the gas in the subsided strata above longwall panels before it can enter the ventilation system of the underground workplace. The history matching phase of the study has been carried out on a 381-m (1,250ft) wide panel in the Pittsburgh Coalbed. Simulations have also been completed for a 442 m (1,450ft) wide panel to estimate the incremental increase in methane emissions and the performance of current gob gas venthole placement configurations. Additional venthole placement configurations were simulated to investigate options for optimizing methane capture from the subsided strata above the wider longwall panel.

By Steven R. Munts

The U.S. Bureau of Mines investigated mines, prospects, and mineralized areas in the South Providence Wilderness Study Area (WSA) in 1982. No mines are currently operating in the WSA, however, the Golden Gift Mine in the southeastern part of the WSA produced $6,800 1/ worth of gold and silver and five mines adjacent to the east boundary of the WSA had a total production of about $3,500,000 1/ in gold, silver, lead, and copper. There is no recorded placer gold production. Over 350 lode and placer mining claims are in and immediately adjacent to the WSA. Of these, 74 were actively held (1982) and at least one area, which is partly within the northeast portion of the WSA, was being actively explored by private industry in 1982. Adjacent to the southeastern border of the WSA the Big Horn Mine contains an estimated 200,000 tons of indicated and inferred marginal reserves averaging 0.25 oz/ton gold; and the Hidden Hill Mine has 550 tons of subeconomic resources averaging 0.60 oz/ton gold. An additional 11,000 tons of marginally economic gold-bearing dump reserves average 0.17 oz/ton gold at the Bighorn, Hidden Hill, and the Buena Vista Mines and the Midas Touch Prospect. Sample analyses indicate eight mines and prospects in, and five adjacent to the WSA may have additional gold-silver-lead-copper vein-type resources. Five of these prospect areas may have a disseminated gold resource and one may have gold resources in a skarn. One prospect may have a porphyry-type copper-molybdenum resource. Although gold placer claims were filed sporadically throughout the WSA, none appears to have placer gold resources. Likelihood for mining is greatest at the Big Horn Mine; if a mill is built there, it could process Big Horn Mine ore, ore from the Hidden Hill Mine, and gold-bearing dumps at the Big Horn, Hidden Hill, and Buena Vista Mines and the Midas Touch Prospect. All of these resources are adjacent to the WSA; however, their development would increase likelihood for development of resources in the WSA. Two major fault zones (the Hidden Hill, and the Big Horn) appear to have controlled the mineralization at many of the prospects and mines. All of the prospects or mines with vein-type occurrences and resources are on or adjacent to one of these fault zones. Veins throughout the eastern half of the WSA contain various amounts of gold, silver, and copper; only veins near the Big Horn Mine and in the northeastern corner of the WSA contain lead. Some veins are as thick as 6 ft, are traceable intermittently for over 2 mi along strike, are sporadically mineralized, are encased in prophylitic, argillic, and phyllic altered host rock, contain pyrite, chalcopyrite, galena, specularite, barite, or fluorite, and display multiple stages of quartz veining and (or) brecciation. Sample analyses at five prospects (map nos. 3, 18, 23, 24, and 31) indicate they may have disseminated gold resources. To date no oil or gas has been discovered within the WSA. However, some oil and gas leases are currently (August 1982) held within this study area.

Jan 1, 1984

By G. R. Hopkins

"Refiners are generally considered solely as fuel producers, but actually they also comprise a group one of the largest consumers of fuel. For example, during the year 1929 the refineries-burned 51,544,000 barrels of oil as fuel, or the equivalent of over 5 per cent of the crude oil processed in that year. In addition enough other fuels - coal, natural gas, refinery or still gas, and petroleum coke - were utilized to raise the total fuel consumption based on B. t. u. equivalent to more than 10 per cent of the heat value in the total crude oil run to stills. Refineries utilize fuel chiefly as the heat-forming element distillation, but also under-boilers in the formation of steam used in refining, for the heating of buildings, and in the generation of electricity.In the early days of refining, the problem of fuel utilization and fuel economy was of scant importance to the refiners. Margins of profit were comparatively high and the major portion of the operatros1 attention was directed toward increasing their throughput. However, the keen competition that has prevailed in the refining industry over the past five years or more has taught the refiners that their expenses, one of the largest items of which is the cost of fuel, must be curtailed. Thus in 1925 the refiners used an average of 829,000 B. t. u. to refine a barrel of crude oil, wheras by 1929 this average had been reduced to 639,000 B. t. u., a decline of 23 per cent (see fig. 1)Since 1925 oil has ranked first as a refinery fuel (see fig. 2). The use of natural gas increased during 1926 and 1927 but declined in 1928 and 1929. On the other hand, the use of refinery gas has grown rapidly in importance. Coal has shown a steady decline in use at refineries since 1925. Petroleum coke has never supplied more than a very small fraction of the total fuel requirements, although there has been a steady increase in its use."

Sep 1, 1930

By J. E. Crawshaw

"The few previous observations of the effect of turbulence on limits of inflammability have been made on a small scale in turbulence produced either by a fan or by movement of the mixture.By a suitable amount of turbulence from a fan the lower limit of methane was 5 per cent as compared with 5 per cent observed for quiescent mixtures in the same vessel.3 With a streaming movement of the gas mixture within the range of speed from 35 to 65 centimeters per second (69 to 128 feet a minute) the lower limit was approximately 5 percent,4 For a quiescent mixture of ethane the lower limit was 3.10 per cent ethane, but with fan running at a moderate speed a 3 per cent mixture exploded.5The object of the tests herein reported was (1) to determine the lower limit of natural gas in a mixture of natural gas and air Which would be ignited and propagate violently when the turbulence was produced by explosives fired from a cannon into the mixture; (2) to observe the behavior when the mixture contained less than this low limit; and (3) to determine how turbulence produced by a fan affects thin limit.Four series of tests were run, three of which were to determine the effect of different sources of ignition: Tests with (1) an electric igniter; (2) 3F black blasting powder stemmed with 2 pounds of dry fire clay stemming used to ignite the mixture, and (3) 40 per cent straight nitroglycerin dynamite unstemmed. The fourth was made to study the effect of turbulence produced by a two-speed electric fan, using an electric igniter as the source of ignition.In both series of tests with explosives, charges of 50 and 200 were used to determine the effect of increased quantity of explosives on the lower limit of natural gas."

Jul 1, 1930

By L. R. Stark

Two wetland simulation experiments were carried out in order to determine the effects on manganese retention of several wetland design parameters, including flow rate, inlet pH, carbon supplementation, substrate type, and surface free water depth. The primary aim in each experiment was to determine if sustained manganese retention could be accomplished under the specific experimental treatments. If successful, these experiments could recommend design parameters for the construction of field wetland systems for manganese treatment. Crushed limestone clearly was superior to spent mushroom compost with respect to manganese retention. The presence of free surface water detracted from manganese treatment, while lower flow rates enhanced manganese treatment. Sustained manganese retention was achieved using crushed limestone as the substrate coupled with an absence of surface free water, under inlet water conditions of pH 7.0 and no appreciable iron. Sustained manganese retention was not achieved under reducing conditions using spent mushroom compost while varying flow rate, inlet pH, and carbon supplementation regimes. However, lowering the flow rate resulted in many significant beneficial effects on outlet water chemistry: lower outlet manganese concentrations (over the short term), higher outlet pH, lower outlet acidity, higher outlet alkalinity, higher outlet sulfide, lower outlet sulfate, and lower outlet redox potential. Supplementation of the wetlands with dairy whey resulted in lower outlet manganese concentrations (over the short term), marginally higher outlet sulfide levels, and acted to lower the redox potential under the high flow regime. Wetlands receiving a neutral pH had lower outlet acidity, higher outlet alkalinity, lower outlet sulfate, but equivalent outlet manganese concentrations than wetlands receiving an acidic pH. When manganese is the primary mine water contaminant and a passive water treatment system is to be used, it is recommended that crushed limestone with negligible surface water be used in place of composted materials. This recommendation assumes a source water with circumneutral pH and an absence of other metals.

Jan 1, 1993

By Northcutt Ely

This volume- summarizes mining and petroleum legislation in 18 European jurisdictions. Within these jurisdictions, primary attention is given to requirements that must be met in each country for acquisition of rights to permit development of mineral resources. Coverage includes: First, identitication of the controlling laws or statutes governing minerals acquisition and reference to the administrative authority; second, analysis; of the laws governing mines and quarries and their products; third, analysis of laws applicable to natural gas, petroleum, and related materials; and fourth, mention of laws regulating offshore operations. Where pertinent, sections dealing with historical background or administration have been added in countries where minerals are subject to control of States or Provinces, those areas are considered separately from the central government.

Jan 1, 1974

By George C. Branner

This circular is concerned with eight nonferrous scrap metals as they generated, collected, prepared, and consumed in California. Brief reference also is included with respect to Nevada and Hawaii. Four of these scrap metals - copper, lead, aluminum, and zinc - are of major importance and make up about 95 percent of the total value, whereas the remaining four - antimony, magnesium, nickel, and tin - make up the remaining 5 percent. For convenience, the subject matter is divided into three parts, (1) Data with respect to the collection, preparation, and marketing practices that are common activities to all the nonferrous scrap metals; (2) separate discussions and statistical data with respect to each of the eight nonferrous scrap metals in California; and (3) data with respect to Nevada and Hawaii.

Jan 1, 1962

By R. Y. Williams

In this report an attempt is made to discuss the first cost of each of several types of mine-ventilation stoppings, as well as the total annual expense of maintaining a stopping during its required period of service. Such data furnish a basis for comparison of the efficiency of the different types, and are of great importance to an engineer planning the development of a mine. The data given were obtained through an investigation conducted under a cooperative agreement between the Bureau of Mines, the Illinois State Geological Survey, and the department of mining engineering of the University of Illinois. The report itself is published by the Bureau of Mines as a contribution to the literature on safety and efficiency in coal mining.

Jan 1, 1915