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By Chester L. Arnold, Reinhardt Thiessen, Alexander Lowy

"INTRODUCTION Peat is the accumulated mass of plant materials that remain after partial decay under specific conditions. In the swampy peat bogs dead material which falls on the surface immediately is attacked by fungi and aercbic bacteria. Decay under these conditions is rapid, but of relatively short duration, since the constant addition of new material soon forces the older layers below the water level, in this position, without access to oxygen, the plant constituents are attacked mainly by anaerobic bacteria, and decomposition proceeds slowly. The largest part of peat is contributed by the woody tissues of plants, the chief constituents of which are cellulose and lignin, together with a small proportion of hemicelluloses. During the normal process of biological decay celluloses disappear more rapidly than lignin. The result is a complex substance known as humin, from which the humic acids may be extracted.In 1826, Sprengel 5 found that when decayed plant materials were extracted with alinnli and the resulting black liquid acidified with mineral acid a brown gelatinous precipitate was formed. To this product, which was a brown amorphous powder when dry, he gave the name ""humic acid'. Since that time, chemists have used the name rather loosely to designate products which have been isolated by very diverse means from soils, decayed woods, peat, lignite, and coal. An excellent review of the early work on humic acids was published by Baumann 6 in 1909. This publication aroused the interest of Oden, who then investigated the humic acids. An account of Oden’s work, as a good survey of the literature, is contained in his monograph “Die Huminsauren”. 7"

Nov 1, 1934

By R. V. Thurston, Edmund S. Leaver

"During the development of the sulphur dioxide leaching process for the treatment of ""mixed"" copper ores at the Southwest experiment station of the Bureau of Mines*** the pulp from treatment of roasted cupriferous pyrite with sulphur dioxide gases and water showed an unexpected amount of sulphuric acid. After following out several false premises it was found that this was due to iron in the solution, and also that this iron tended to oxidize to the ferric state if the concentration of sulphur dioxide in the roaster gases used did not rise above a certain figure. While the percentage of iron present was email it was enough to cause an entirely different set of conditions from those of the original sulphur dioxide leaching process and to promise a much wider application of the general idea. Sulphurous acid dissolves only certain copper minerals, sulphuric acid solutions certain additional minerals and ferric sulphate solutions certain further additional copper minerals, so this observation was of importance in connection with possibilities in the hydrometallurgy of the so-called ""mixed"" or partly oxidized copper ores.The work has been carried along by a number of experimenters. L. R. Eckman, junior chemist of the Southwest station, contributed largely to the early developments. L. Roberts, W. D. Bonner and C. G. Maier each in turn physical chemists at the Pacific Experiment station, (Berkeley, Calif.) have studied the reactions involved. A complete report of all the work on this process will be prepared later under the direction of O. C. Rolston. The purpose of the present paper is to place a summary of the more practical phases of this seemingly important piece of work before those interested."

Dec 1, 1923

By H. J. Heinen

This report summarizes preliminary research studies by the Bureau of Mines in electrowinning molybdenum directly from pure or impure molybdenum trioxide (MoO3) by fused-bath electrolysis in an open graphite cell without need of a protective inert atmosphere. A formulated electrolyte of the tertiary system containing 41.6 percent sodium pyrophosphate, 16.7 percent sodium tetraborat, 33.3 percent sodium chloride, and 8,4 percent molybdenum trioxide, by weight, electrolyzed at 1,000° C,, gave excellent results. Current density studies were made over a range from 20 to 260 amperes per square decimeter. Current efficiencies of 80 to 90 percent were obtained over the entire range. Yields up to 500 grams of molybdenum per kilowatt-hour were obtained. Higher current densities, however, reduced yields and produced a finer grained metal. The two most important facets in electrowinning molybdenum from MoO3, in an open cell, are temperature and electrode spacing to minimize or eliminate the formation of the suboxide MoO2, the major source of oxygen contamination. At temperatures of 1,000° C. and higher, together with the proper spacing of the electrodes, formation of oxides are practically eliminated. Molybdenum metal electrowon from pure MoO3 was 99.9 percent pure and contained 0,056 percent oxygen and 0,007 percent carbon. This metal, when arc-melted, had a Vickers hardness number of 175 and contained 50 parts per million oxygen and less than 10 parts per million carbon. Molybdenum metal electrowon directly from an impure MoO3 containing 90 percent MoO3 resulted in a metal of 99.8 percent purity.

Jan 1, 1961

By R. N. Roby

"INTRODUCTION A preliminary examination of the Green Monster and Benich copper prospects was made by engineers E. W. Newnan and George N. Bennett, of the Bureau of Mines, on December 13, 1943. In an unpublished report, it was stated that certain geologic features appeared to be similar to those associated with the copper deposits of the nearby Butte district. On these premises, a preliminary diamond-drilling program was recommended to explore 300 to 400 feet below the mineralized outcrops for the possible presence of a sulfide enrichment zone. In accordance with that recommendation, three holes were drilled. This report presents the data provided by that preliminary drilling exploration.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell D. Moon, chief, conducts preliminary exminations, perform the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyses samples and performs beneficiation tests.The field work on the Bull Run exploration project was supervised byE. W. Newman engineer in charge of the Helena field office. The chemical analyses and assays included in this report were performed under the direction of A. C. Rice, acting engineer in charge, Bureau of Minos Rare and Precious Metals Experiment Station at Reno, Nev. The diamond-drill cores were logged by geologists of the Federal Geological Survey."

Mar 1, 1947

By Charles H. Atkinson

The Rio Blanco massive hydraulic fracturing demonstration has been undertaken by the Bureau of Mines, Atomic Energy Commission, and a group of 15 industry participants. CER Geonuclear Corp. has been retained as program manager to evaluate the stimulation effects of very long fractures, suitably propped open in thick sections containing multiple intervals of low-permeability gas-bearing sands. The zone of interest for this demonstration includes Fort Union and Mesaverde sands from about 5,800 to 8,.200 feet deep in Rio Blanco County, Colo., about 1 mile from the site of the May 1973 triple nuclear detonation aimed at stimulating production from the same reservoirs. Drilling the test well and evaluating the reservoir prior to fracturing was funded by Government participants; fracturing and production testing will be funded by industry. The test well has row been completed at a total depth of 8,170 feet, and data obtained from logs, cores, production and drill-stem tests indicate reservoir conditions to be less favorable for gas production than anticipated. Structural position is lower than expected, resulting in higher water saturation than was determined for the same sands at the nuclear fracturing location. The lower sands of the Fort Union sequence appear to have higher shale content than has been encountered in other wells in the area. Despite the likelihood that gas productivity will be undesirably low following stimulation, the industry participants decided to proceed with the stimulation program with the thought that the resulting data would be useful. The success of the stimulation test probably will have to be judged by production increase rather than by production volume.

Jan 1, 1975

By L. A. Haas

The feasibility of removing sulfur dioxide by carbon monoxide reduction in a fixed-bed catalytic reactor was investigated by the Bureau of Mines. The reduction rate of sulfur dioxide with carbon monoxide was significantly dependent upon the iron and alumina content of the mixed catalyst. Maximum catalytic activity was obtained with about 40 percent iron-alumina mixture with a nominal gas mixture of 10 percent carbon monoxide, 5 percent sulfur dioxide, and the balance nitrogen. The synergistic effect of this catalyst mixture was explained by a dual reaction site mechanism, with both iron and alumina augmenting their specific sites at their interparticle contacts. The catalytic activity also increased with decreasing catalyst pellet size. With O.7-mm pellets, the entire pellet appeared to be catalytically active in a 2-gram catalyst bed. The apparent activation energy of the reaction was 18.3 kcal per mole in the temperature range of 350° to 600° C. Carbonyl sulfide (COS) was produced by the interaction of carbon monoxide and sulfur. The amount decreased with decreasing CO concentration. The ratio of COS formed per SO2 removed reached a maximum at about 400° C. The reaction rate appeared to be independent of S02 concentration in the range of 0.2 to 16 percent. The rate, however, increased directly with the CO concentration in the range of 5 to 20 percent. The presence of CO2 (<15 percent) had no appreciable effect on the rate. However, not over 0.5 percent oxygen could be tolerated. This method appears feasible for removing S02 from waste gas if the oxygen is removed prior to the catalytic S02 reduction process.

Jan 1, 1971

By Maria I. De Rosa

During 1990-2001, a total of 518 fires occurred in all metal/ nonmetal mining categories; 296 of those fires caused 308 injuries and 4 fatalities. Surface operations had the most fires and the highest injury risk rate values. Forty-five fires destroyed or heavily damaged facilities and equipment (including 19 pieces of mobile equipment) because of failure of firefighting methods, late fire detection, undetected fires, or fire size. In the future, many of these fires and injuries might be prevented or detected and extinguished at their earliest stage by improving current fire safety procedures, adopting existing/ improved fire detection and suppression technologies, and/or developing new technologies. Several strategies for reducing and/or preventing the number of fires and fire injuries follow. I. Increase vigilance, improve safety procedures, and develop new technologies in order to prevent fires and injuries caused by fame cutting and welding operations. 2. Improve equipment hydraulic/fuel/electrical systems inspection programs; adopt fire-resistant hydraulic fluids and electrically powered motors for use in underground mines; develop new technologies (equipment/cab rapid fire detection/ prevention/suppression systems, emergency line drainage systems, and fire barriers); adopt an optimal ground level location for the activation of emergency systems; improve operator&apos;s fire preparedness training programs; and develop effective and rapid local firefighting response capabilities. 3. Adopt existing/improved systems for continuous and early detection of combustion gases and smoke along beltlines. 4. Adopt existing/improved technologies for monitoring equipment (beltlines) operational functions. 5. Increase vigilance and adopt improved safety procedures for handling f amenable liquids and refueling fuel in the vicinity of heat sources.

Jan 1, 2004

By R. V. Ramani, C. B. Manula, A. Owili-Eger

MINE PROTOTYPE The prototype chosen for application demonstration is from Kingery (1960). The mine and the ventilation plan is presented in Figure 11. A new coal mine is projected with entrance by slope 1,500 feet long. Nine train entries will be standard for development, five as intake and four as return. One return shaft is planned near the slope bottom. The slope will have an area of 150 square feet and a perimeter of 55 feet. The return shaft will be circular with a diameter of 18 feet and will be 500 feet deep. Two hundred feet of the shaft and 500 feet of the slope will be concrete lined. Will it be possible to operate five units per shift with amount of air at each unit not less than 25,000 cfm? Additionally, a shop at the slope bottom will require 10,000 cfm. The problem is completely worked out using standard ventilation formulas and simple manual calculations in the above reference and is reproduced here in Appendix II for ready reference. APPLICATION In this manual, four different applications of the PSU/MVS are outlined. An article by Stefanko et al (1972), outlines how one can move from a mine map to a network for the generation of computer input. Attention is drawn to Figure 12, which is the network line diagram of the mine ventilation system in Figure 11. Note that every roadway junction has been numbered. The dotted lines represent leakage paths and the letter &apos;R&apos; on a branch denotes that the split is regulated for the quantity shown. For example, there is a leakage

Jan 1, 1975

By Maria I. De Rosa

Table 37 and figure 13 show the number of fires and fire injuries for surface stone mines by state during 1990-2001. Table 37 also shows the injury risk rates, employees&apos; working hours, and lost workdays. In all, 96 fires occurred in 31 states and 1 fire occurred in Puerto Rico. Sixty-eight of the fires caused 67 injuries and 1 fatality (including 6 fires and 5 injuries involving contractors). The yearly average was eight fires and 5.6 injuries. The Ewhr value was 689 x 106 hr (Irr = 0.02), and the LWD value was 7,399. Indiana had the most fires (eight fires and four injuries), followed by Georgia (seven fires and seven injuries) and Pennsylvania (seven fires and five injuries). Of these states, Georgia had the highest injury risk rate value (Irr = 0.058). Table 38, partly illustrated in figure 14, shows the number of fires, fire injuries, fire fatalities, risk rates, employees&apos; working hours, and lost workdays by time period. The number of fires and fire injuries show an increase during the second period followed by a decrease during most of the remaining periods. Employees&apos; working hours increased during most of the periods. The In values follow patterns similar to those shown by the injury values. Tables 39-44 show the number of fires by ignition source, method of detection and suppression, equipment involved, location, and burning material by time period. Figure 15 shows the major variables related to fires for 1990-2001. Table 45 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 Deno M. Pappas, Christopher Mark, Eric R. Bauer

During 1998-99, groundfall incidents resulted in 27 fatalities and were responsible for over 70% of all deaths in U.S. underground coal mines. To obtain a better understanding of where and why these incidents occurred, a comprehensive analysis of ground fall injuries and fatalities was conducted. The first portion of the study examined various factors associated with roof and rib fall injuries and reportable roof fall noninjuries that occurred during 1995-98. The study found that the room-and-pillar mining method has twice the groundfall incident rate than the longwall method. Mine locations with high groundfall rates seem to correlate to regions where there is a higher concentration of problematic coalbeds. For example, the Illinois Basin has very high groundfall rates, which can be traced back to several key coalbeds-Kentucky No. 13, Herrin/No. 6/Kentucky No. 11, and Springfield No. 5/Kentucky No. 9. High rib fall rates were found in mines located in thick seams. Groundfall rates were found to be 30% to 40% higher during the months of July through September, possibly due to high humidity that may cause the shale mine roof to deteriorate. The second part of the study examined the root causes of failure by reviewing all groundfall fatality reports for 1996-99. Primary and secondary hazard factors were assigned to each groundfall incident. The primaryf actors resulting in these groundfall fatalities were pillar extraction, traveling under unsupported roof, skin failure, construction, longwall faces, intersections, and geologic discontinuities. Defining prominent ground control incident trends and hazards will identify areas where additional study is needed and where innovative solutions need to be developed to reduce these severe occupational hazards.

Jan 10, 2000

By Dennis A. Long

"The size of off-highway trucks has increased substantially over the last decade, bringing about a radical change in truck maintenance practices and procedures. As a result, surface mine maintenance mechanics today are faced with the increased hazards of working with larger and heavier tools and components and doing repairs at greater heights, thereby exposing them to a high potential for serious injury or death. Not surprisingly, the number of accidents involving truck maintenance mechanics is significantly increasing.The Bureau of Mines has assessed the haulage truck maintenance safety problem, analyzing maintenance-accident data over the 7-yr period, 1978- 84, in terms of personnel, job activities, truck components and systems, tools involved, and truck design. This assessment, based on the review and interpretation of 1,225 haulage truck maintenance accident reports, identified major factors contributing to these accidents. Overall, young, inexperienced workers are involved in most accidents. A typical maintenance accident involves a male mechanic under 33 yr old, with less than 5 yr job experience. INTRODUCTIONOver the past decade, surface mine maintenance and repair operations have changed radically. The number of maintenance personnel has grown along with the hazards of working with larger and heavier components at greater heights and with larger and heavier tools. Furthermore, transfer of skills from over-the-road vehicle mechanics is not as feasible as it once was, because of the ever increasing size of mining equipment and the complexity of its design. In short, surf ace mine equipment maintenance and repair has become increasingly sophisticated as well as labor intensive, necessitating further research and evaluation in terms of both safety and efficiency (1, 7-8) 2"

Jan 1, 1986

By Allen D. Look, Stanley M. Walker, Van Fleet. Leonard A.

"INTRODUCTION The hazards to be encountered in temporarily or permanently abandoned underground mines, quarries, and open pits are numerous, and hardly a year goes by without several reported cases of fatal or serious injuries occurring to unwary people who enter these old mines. Persons visiting mining areas for the first time, tourists, and young people, especially, proceeding in the spirit of adventure common to youth or to the venturesome have suffered many such accidents during exploration trips. The possibility of salvaging salable or usable equipment prompts men and boys to go into old mines, some through ignorance of the attendant hazards, but some jeopardize their lives hopeful of gain (in some cases pitifully small), thinking the hazards are not dangerous and that they can ""get away with it.""Persons fall into unprotected holes, some seek shelter from storms under high banks, and quarries and open pits are often chosen as places for recreation, picnics, swimming, etc; all such uses of these places are likely to be hazardous and to lead to accidents, frequently fatal.These hazards are known to men in the mining profession, and the danger to the public is realized by most of them. A solution to the problem has been sought at many mining meetings, and it is recognized that complete prevention of entry into old mine workings and surface mining areas is the ideal solution, but this, unfortunately, is not always practical; better education of the public, particularly children, should help to reduce the number of such accidents and will be effective in direct proportion to the extent and vividness of such education."

Aug 1, 1948

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

Computer input data for an operating mine is developed on the basis of a detailed ventilation survey which includes air quantity, air quality, pressure loss and fan performance measurements. Quantity measurements must be reviewed extensively and assumptions made about leakage quantities and airflow paths. Pressure measurements must be reviewed and developed into a pressure gradient for the mine system. Air quality measurements are used to determine methane sources and amounts. Finally, the fan test data is used to develop the correct fan characteristic curve. Quantities and pressure losses for each branch in the system are used to calculate the branch resistances which are then utilized in the ventilation simulator to model the mine system. QUANTITY BALANCE The quantity of air coming into a mine based on field measurements will rarely equal the quantity exiting the mine, even if allowances are made for methane or compressed air input to the system. The same statement can be made for airflow through any isolated part of the mine ventilation system such as individual working section or main aircourses leading to an area isolated from the rest of the mine. The reason for the apparent discrepancies is the accuracy of the indicated quantities which in turn is based on the accuracy of the individual velocity and area measurements. Even with measurements following the guidelines described in the previous section on quantity measurement, this error can only be minimized but not eliminated. As a result the ventilation system must be carefully balanced so that, for any loop, the quantity in plus any methane or compressed air injection will equal the quantity out. The continuity of flow described by the balanced system must approximate the

Jan 1, 1977

By E. Chin

The mineral industry of Bangladesh was totally dominated by natural gas production and its downstream uses. A small amount of cement was produced, and clays were used locally for ceramics and construction materials. Nitrogenous fertilizer was produced from natural gas and a modest, scrap-based steel industry produced steel for local consumption. The country has been developing and using its abundant and inexpensive gas reserves as fast as practical. The population, however, was predominantly dependent on agriculture for its livelihood. The industrial sector accounted for 10% of the economy, and most of the industrial output was directly associated with agricultural products jute, tobacco, and textiles. Industrial expansion, even with the availability of gas, was severely constrained because of limited domestic demand, lack of skilled work force and management, poor infrastructure, and a low rate of domestic savings. To put greater emphasis on the industrial sector, the Government established a National Committee for Industrial Development in July. The Committee instituted policy reforms in the areas of trade and investment. One important step was to move from a positive import list to a negative list, thereby permitting imports of items not restricted or banned. The system for recovering and approving new domestic or foreign industrial investments was streamlined to expedite what had become a cumbersome, bureaucratic exercise. To encourage industrial development in areas away from the crowded urban centers, several economic incentives reportedly were adopted. These included a reduced tax rate on imported machinery, exemption of import license fees, a reasonable debt equity rate, and a 9-year income tax exemption period.2 In the trade sector, imports increased 12% in fiscal year (FY) 19843 mainly

Jan 1, 1987

Acid pollution from abandoned mines causes serious contamination of major streams in coal mining areas. In Pennsylvania alone it is estimated that 3000 miles of streams are devoid of fish and plant life because of coal mine effluent.1 The pollution arises because water and oxygen react with iron sulfide in the mine cavity to produce sulfuric acid and iron sulfate, which later find their way back into surface streams. Two general approaches to the problem are possible: (1) prevent the acid-forming reaction from taking place, (2) treat the acid mine water after it is formed so that it will not be harmful to the ecology when discharged into streams and other surface waters. The work described in this report belongs in the first category - it was based on the assumption that acid formation in the mine cavity can be prevented by keeping water (one of the reactants) out of the mine. This was to be accomplished by-forming a waterproof seal over the mine cavity which would prevent the seepage of surface water into the mine. It was planned to form such a seal at or near the surface of the ground by applying latex to the soil. Ideally a dilute latex would be applied to the soil and would penetrate to a depth of two to three feet below the surface where it would be coagulated by reacting with a constituent of the soil or by other means., A seal below the surface of the soil would have several advantages over a surface seal - it would not be subject to destruction by traffic, frost or vegetation and, more important, it would allow the use of the top soil for many agricultural purposes. A preliminary feasibility experiment was performed prior to application for the present grant. It showed that it was indeed possible to form a sub-surface seal by means of latex. A core of soil was obtained locally (Wayne, N. J.) by driving a 6.5 cm inside diameter steel pipe about 100 cm long into subsoil for a distance of 71 cm. The soil was retained within the pipe for this experiment. A part of the free space above the soil in the pipe was charged with water, and the seepage rate of the soil after it had become saturated was 15 ml/min under a total head (wet soil plus supernatant column of water) of 92 cm. After the supernatant water had drained completely, 100 ml of 5% rubber latex was added and allowed to seep into the soil. This was followed by additional water and the seepage rate was found to be 2 ml/min under the same head. This seepage rate remained unchanged when remeasured on the following day. Since there was no visible evidence of the latex in the collected drain water it is presumed to have been retained by the soil.

Jan 1, 1972

SMCRA contains five principal regulatory provisions that form the basis for its implementation: Performance Standards Performance standard safe intended to ensure that all surface mining is conducted in a way that protects the environment and the public and ensures that the mined land is restored to productive use following mining. Permits Before developing a surface or underground coal mine, an operator must have a permit issued under SMCRA. An application for a permit to conduct a surface coal mining operation is a detailed document that consists of text and numeric data describing the proposed mining and reclamation. Information must be furnished on pre-mining environmental conditions, existing land use, proposed mining and reclamation, how the performance standards will be met, and the post-mining land use. This provides the regulatory authority with the information necessary to determine that the operation can be conducted in accordance with the regulations. Performance Bonds Before a permit can be granted, an operator must post a performance bond sufficient to cover the cost of reclaiming the site in the event the operator fails to complete reclamation. The bond is not fully released until all performance standards have been met and reclamation of the site has been determined to be successful after five years in the East and Midwest, and after 10 years in the arid West. However, the bond can be partially released as various phases of reclamation are completed. Inspection and Enforcement If a violation of SMCRA or of a state surface mining and reclamation law is observed, an inspector issues a notice of violation to the operator. The violation must be corrected within a specific time, and the operator may also have to pay a fine based on the severity of the violation. If the violation is not corrected, acessation order is issued to immediately stop active coal mining, and the operator must pay a fine. If a violation is especially serious (for example, creates an Following reclamation, the land was immediately put back into agricultural production. Today, grain and corn crop yields have continually exceeded targets. 2 imminent danger to public health or safety or causes significant damage to land, air, or water resources) the inspector immediately issues a cessation order. An operator must correct all violations in order to obtain permits for new mines. Lands Unsuitable For Mining Congress recognized that certain coal deposits cannot be mined without permanent damage to unique cultural or natural resources. As a result, SMCRA protects these resources in two ways: It prohibits mining within the boundaries of national parks, forests, wildlife refuges, trails, wild and scenic rivers, wilderness and recreation areas; in areas which will adversely affect sites listed on the National Register of Historic Places; and within a restricted distance of occupied dwellings, public roads, buildings, parks, schools, churches, and cemeteries; and Provides a process that allows anyone whose interests may be adversely affected by proposed mining to petition to have specific lands designated unsuitable for mining.

Jan 1, 1992

By I. AITKENS

It is a common misconception that all yellow stones are topazes and that all topazes are yellow; but neither statement is true. The real topaz is a rather rare mineral, and a large number of yellow stones that masquerade as topaz are nothing more than yellow quartz, known as citrine, but almost universally called topaz. The true topaz is often called "Brazilian" topaz by the jeweler to distinguish it from yellow quartz; nevertheless, both terms are freely applied in trade to other yellow stones. Topaz is considered the most popular yellow stone for jewelry and is often used as the principal stone in brooches or pendants, especially in old-fashioned ornaments. However, many other species yield pretty yellow stones, some of which are far more numerous and less costly than the topaz.

Sep 1, 1931

By G. S. Scott

The Bureau of Mines is engaged in research to assess the hazards associated with the handling, storage, and use of combustible gases, vapors, and. liquids encountered in mines and in industry. As a part of this general pro-gram, numerous limits of flammability and ignition temperatures are being investigated for a wide variety of combustible materials, and methods are being developed to minimize the explosion hazards of these combustibles. The Bureau receives numerous requests for information on the explosion hazards of specified combustible mixtures under various conditions of use. This information circular has been prepared to assist those who may have similar requests. Destined primarily for the layman with a limited technical knowledge of the subject, it considers rather briefly the numerous factors that enter into the general problem of gaseous explosions and their prevention.

Jan 1, 1951

By H. F. Yancey

A relatively large proportion of the coal produced 1n the State of Washington, especially in the coking coal areas is of fine size; hence washing by means or coal-washing tables to reduce the ash content is commonly practiced. For this reason the program of research in coal washing conducted jointly by the U. S. Bureau of Mines and the College of Mines, University of Washington, has given special attention to the mechanism or the separation of coal from its impurities as effected by the coal-washing table with the object of increasing its efficiency. Previous work has evaluated the role of stratification the influence of size, specific gravity and respective shapes of particles in the feed, and the affect of hindered-settling classification of the feed prior to tabling.

Jan 1, 1931

By Charles Prasky

The Bureau of Mines investigated the conversion of nonmagnetic iron minerals to magnetic form through reduction Toasting operations. The primary objective was to obtain a concentrate that could be used as a direct shipping material for blast furnace consumption. Crude iron materials from the Steep Rock Lakes, Ontario, area were prepared into a blend of 8 parts siliceous ore, 3 parts pyritic ore, and 1 part tailings. Experimental work included laboratory reduction roasting tests, two continuous 10-day campaigns, and one 12-hour test all in a 34-inch by 36¬-foot rotary kiln. The objective of the project was achieved in producing an iron concentrate containing about 66 percent iron with over 90 percent iron recovery. Desirable operating conditions were developed in the kiln but optimum process variables were not completely established.

Jan 1, 1969