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Reduce rockfall fatalities and injuries by using innovative blasting practices to reduce damage to the rock at the excavation limits with little or no increase in cost. The Problem Falls of highwall have been a leading cause of fatalities, injuries, and equipment damage in the surface mining industry. Although the number of highwall falls is not great, when such an incident does occur it is about 14 times more likely to be fatal or result in severe injury and damage to equipment than other types of surface mine accidents. Overbreak or damage to the rock from poor or improper blasting practices is a major factor contributing to rock falls. Presplitting or cushion blasting is the technique most often recommended for improved wall control. This type of blasting however, adds to drilling and blasting costs and is not universally accepted by the industry. Air gap presplitting techniques, also called air decks, are currently being used in some mines as a less costly alternative to conventional presplitting. Approach Blasting can cause highwall damage, but proper blasting techniques have been shown to reduce the magnitude of rockfall problems. In preventing rock falls, it is important to maintain the natural strength of the rock structure to the greatest extent possible. Improved blasting practices have three main advantages: 1) they are preventive rather than corrective in nature; 2) they are cost effective; and 3) they have a very low impact on the mining operation when properly implemented. New ways of evaluating highwall integrity, such as seismic refraction tomography, were investigated.

Jan 1, 1991

By C. P. Bowie

The Bureau of Mines has been conducting investigations with the view of determining the types of containers best adapted to the stor- age of oil. These investigations have shown that tanks composed wholly of steel give the best results. Where larger containers than it is feasible to build with steel are desired, concrete-lined reservoirs can be recommended for some grades of oil. Practically all such containers in use at present have wooden roofs and this type of construction is here described, although it is the belief of the writer that concrete roofs would be far more satisfactory in every way, and that the difference in cost between a concrete and a wooden roof would, as a rule, in a few years' time, be offset by a saving of oil and in cost of repairs and renewals.

Jan 1, 1918

By Donald F. Reed

During the first 6 months of 1948 the Bureau of Mines investigated the titania, deposit on the Wynn 0. Christy property in northern Hot Spring County, Ark. The property is situated in Magnet Cove, about half a mile north of the Magnet Store and U. S. Highway 270 (fig. 1). The purpose of the investigation was to determine the extent and grade of the ore body and to obtain a representative sample of the ore in as nearly natural condition as possible for use in metallurgical testing. All of the titania that has been marketed from Arkansas mines has been in the form of rutile from a deposit about 2 miles west of the Christy property. The titania in the Christy property occurs principally as brookite, which, with fragments of novaculite, quartz, and limonite, is imbedded in red clay. It is difficult to recover a core of the material. Three types of drills - a diamond drill, a bucket drill, and a Baker cable-coring tool operated on a churn rig - were employed in an effort to procure proper samples in their natural state. The Baker tool was found to be the most efficient and to be capable of drilling to a depth of 150 feet, making 80 to 100 percent core recovery (fig. 8). Total footage drilled was 1,536.9 in 21 holes, of which 7 were diamond-drill holes, 13 were bucket drill holes, and one was drilled with the Baker tool. The ore body was found to be 900 feet long, 500 feet wide, and more than 141 feet deep and contained 5.8 percent TiO2 and 0.52 percent 1720. Most of the deeper drill holes bottomed in ore, and there is a possibility that the ore may persist to a depth of several hundred feet. The Metallurgical Division of the Bureau of Mines is conducting experimental work at the Mississippi Valley Experiment Station at Rolla, Mo., for the purpose of developing methods of concntrating and utilizing the ore.

Jan 1, 1949

By S. P. Kinney

Economy in blast-furnace practice depends largely upon efficient gas-solid contact in the shaft of the furnace. If efficient work is not done in the shaft the hearth and bosh will not function properly. A condition may be readily imagined where the particles of ore in the shaft are so large that the time entailed in the descent of these materials into the bosh is not sufficient to permit proper reduction and preparation prior to the time the ore enters the bosh of the furnace. Another condition may be pictured where the density of the stock column and the flow of stock is such that the ore will take one course and the gas another. Both of these examples will result in insufficient contact between the gas and the ore. Unreduced ore will reach the hearth, and gas which has not been efficiently oxidized will reach the stock line. The result is the use of an excess of carbon in the smelting process. An example of the result of inefficient gas-solid contact in the shaft of a blast furnace is shown by the curves in Figure 1.

Jan 1, 1930

By John J. Sammarco

Computer-related accidents have caused injuries and fatalities in mining as well as other industries. Normal accident theory (NAT) explains that some accidents are inevitable because of system complexity. NAT is a classic argument in organizational sociology although it has been criticized as having imprecise definitions and lacking criteria for quantifying complexity. These limitations are addressed by a unique approach that recasts this organizational theory into an engineering-based methodology to quantify NAT complexities of computer-based systems. In this approach complexity is categorized as external or internal. External complexity is defined by the external behavior of a system, and is quantified by these dependent variables: system predictability, observability, and usability. Dependent variable data contain the perceptions of 32 subjects running simulations of a system. The system?s internal complexity is characterized by modeling system-level requirements with the software cost reduction (SCR) formal method. Model attributes are quantified using 15 graph-theoretical metrics?the independent variables. Five of 15 metrics are correlated with the dependent variables as evidenced by structure correlations exceeding 0.25, with standard errors <0.10 and a 95% confidence interval. The results also show that the system predictability, observability, and usability decreased as NAT complexities increased. This research takes a step forward in operationalizing NAT for computerized systems. The research benefits mining and other industries as well.

Jan 1, 2005

By W. M. Weigel

"Sand is one of the commonest materials for industrial use, not only as a building material, but in many industrial processes. The general name applies to all grades, from the comparatively impure, unsorted product used in concrete, to especially sized products of extreme chemical purity. Various definitions have been proposed, all more or less open to objection, as they fail to cover special applications. One is: ""Sand - The fine granular material naturally or artificially produced by the disintegration or crushing of rock or slag"". This does not fit the definition of sand as understood by geologists, who consider sand only as a naturally formed product. Another is: ""Sand - The fine granular material naturally produced by the disintegration of rock"". This does not take the chemical com-position into account, and for practically all uses, except in concrete and plaster products, a material composed predominantly of silica or rather quarts is implied.Sand for special purposes usually requires different methods of preparation from those where the ordinary mixture of sizes as naturally occurring are suitable. One of the classes requiring the most uniformly sized grains is sand blast sand.Sand Blast SandThe use of the sand blast has increased rapidly during the past few years. It was formerly used almost entirely in the foundry to clean and remove inequalities from rough castings. This is still the most important application, but in addition, it is now employed for the removal of paint from old surfaces, carving and engraving on stone and marble, glass cutting, cleaning or renovating the rails of stone and brick buildings that have become discolored, preparing the surface of metals for the electrolytic bath, putting the final finish to metal surfaces, and has even been proposed as a means of channeling or cutting out blocks of stone in the quarry."

Jun 1, 1924

By K. C. Dean

During the investigations of the occurrence of manganese in the Western United States, a Bureau of Mines examining engineer collected samples frame two properties in Beaver County, Utah. As the ores were too low in grade to be acceptable by manufacturers of ferromanganese, beneficiation studies were made to determine the amenability of the ores to concentration. The Steelville property is about 37 miles southwest of Frisco, Utah. The deposit is an example of manganese occurring as a replacement of limestone in a bedded vein or as layers in limestone associated with shale and rock decomposition products. The Susie Q deposit, about 33 miles southwest of Milford, Utah, is also a tabular replacement deposit in limestone, apparently of limited extent. Test work was done on representative samples of 2-ton lots obtained by the examining &apos;engineer from each of the properties mentioned.

Jan 1, 1951

By F. E. Walker, S. J. Aresco, J. B. Janus

The Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal , expressed in British thermal units , and the composition as shown by proximate analyses . To these , when required , are added the ash- softening temperature , the free- swelling index , and the Hardgrove grindability index . Under most of these specification contracts the bidders guarantee the quality of the coal , and that guaranteed by the successful bidder becomes the standard of his contract . The deliveries are sampled in accordance with instructions 4/ issued by the Bureau of Mines ; the samples are analyzed in the Bureau laboratory to determine whether the coal is of the quality guaranteed by the contractor and , if it is not , a price adjustment is made . Analyses of the delivered coal and tipple samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks ) provide valuable data for use in evaluating future bids . In addition , the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal . The Government purchased approximately 5 million tons of coal in fiscal year 1963 . In connection with these purchases , the Bureau analyzed 6,999 samples . These are published ( table 1 ) for the use of Government officials and the public . A series of publications has been completed on coal analyses by States or , where production is small in any one State , by groups of adjacent States . In addition to analytical data showing composition and quality of coals of the States , the publications contain brief descriptions

Jan 1, 1964

By F. E. Walker, S. J. Aresco, J. B. Janus

The Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal , expressed in British thermal units , and the composition as shown by proximate analyses . To these , when required , are added the ash- softening temperature , the free - swelling index , and the Hardgrove grindability index . Under most of these specification contracts the bidders guarantee the quality of the coal , and that guaranteed by the successful bidder becomes the standard of his contract . The deliveries are sampled in accordance with instructions 4/ issued by the Bureau of Mines ; the samples are analyzed in the Bureau laboratory to determine whether the coal is of the quality guaranteed by the contractor and , if it is not , a price adjustment is made . Analyses of the delivered coal and tipple samples ( samples collected at mine tipples as coal is being loaded into railroad cars or trucks ) provide valuable data for use in evaluating future bids . In addition , the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal . The Government purchased approximately 5 million tons of coal in fiscal year 1962. In connection with these purchases , the Bureau analyzed 7,114 samples . These are published ( table 1 ) for the use of Government officials and the public . A series of publications has been completed on coal analyses by States or , where production is small in any one State , by groups of adjacent States . In addition to analytical data showing composition and quality of coals of the States , the publications contain brief descriptions

Jan 1, 1963

By D. Harrington

"Since its establishment in 1910 the Bureau of Mines has consistently recommended the rock-dusting of bituminous and lignitic coal mines as a preventive of widespread explosions. As with many other proposed innovations, the response to the bureau's recommendation has been slow; but during the past 10 years many coal mines have done some rock-dusting, even though probably fewer than 50 of the country's approximately 6,000 coal mines are thoroughly rock-dusted. Notwithstanding the inadequacy of the rock-dusting which has been done in most of the mines which have adopted the new system, numerous cases are at hand. indicating the well-founded basis of the bureau's claims regarding the effectiveness of rock-dust in stopping explosions. Very brief descriptions will be given of several cases in which explosions in coal mines of the United States are fairly definitely known to have been stopped by rock-dust during the past 5 or 6 years; in addition, several cases are cited in which explosions were stopped through the agency of rock-dust and moisture.A rock-dusted mine is one in which the floor, roof, and sides of every accessible working place, including haulage ways, airways, manways, and rooms and connections have an application of rock-dust - for instance, limestone - such that the incombustible content of the aggregate dust on those surfaces is over 60 per cent. The dust in these workings should be sampled at regular intervals to determine whether the incombustible matter in the coal-dust is less than the necessary minimum of 60 per cent; another application of rock-dust should be given when the incombustible percentage is less than 60. (As an example of thorough rock-dusting, see Bureau of Mines Information Circular 6578, 1932, which describes how rock-dusting is done in Alabama at a cost of 1.8 cents per ton of coal for a thorough application; Report of Investigations 3060, February, 1931, Rock-Dusting In A Pennsylvania Coal Mine; or Information Circular 6244, 1930, giving data, including costs, on rock-dusting in coal mines in New Mexico.)An explosion may be started by the ignition of gas, even when rock-dust is present; hence it is not correct to say that rock-dust will prevent an explosion of gas; however, if rock-dust has been applied to a working place which has present an explosive mixture of me-thane and air, and if an open light is used or a blown-out shot or an electric arc occurs, although there will very likely be an ignition and possibly an explosion, the rock-dust will certainly prevent ignition of the coal-dust nearby, and unless the general atmosphere has an explosive gas mixture, the rock-dust will stop propagation of the flame throughout the mine. In other words, if an explosion is started by gas or by coal-dust and the mine has been rock-dusted as defined, the rock-dust will prevent widespread extension of the explosion, unless the general atmosphere contains methane and air in explosive proportions.With these definitions clearly in mind, instances are now given where rock-dust has played a prominent part in the stopping of several explosions. No cases have been included where there was any reasonable doubt that rock-dust had taken a definite part in the limiting of the explosions."

Apr 1, 1932

By J. D. Davis

The carbonizing properties of No. 2-bed coal from the Bartoy mine and No. 5- or Miller-bed coal from the Wilkeson-Miller mine, both at Wilkeson, Pierce County, Wash., were determined by the Bureau of Mines-American Gas Association (BM-AGA) method. Tests were made in the 13-inch retort at 500°, 600°, and 700° C. and in the 18¬inch retort at 800°, 900°, and 1,000° C. Fischer low-temperature and United States Steel Corporation high-temperature assays were made and the results compared with those of the BM-AGA tests at corresponding temperatures. Agglutinating and plastic properties were determined, and chemical and petrographic analyses were made. The No. 2 bed is 58.5 to 88.0 inches thick at three points sampled in the Bartoy mine. The coal is 98 percent bright and contains only a trace of fusain. A composite of three mine samples contained 13.8 percent ash. The washed sample, which was used in the tests described herein, contained 11.4 percent ash, 2.2 percent moisture, and 0.6 percent sulfur upon the as-carbonized basis and 68.4 percent fixed carbon upon the dry, mineral-matter-free basis. The heating value was 15,183 B. t.u. per pound upon the moist, mineral-matter-free basis. No. 2 therefore ranks as a high-volatile A coal and is very high in that, rank. The ash softens at 2,910° F. Except for its ash content, which is higher than the limit of 9.0 percent specified by the American Society for Testing Materials, No. 2 coal fulfills the requirements of a coking coal. It also is classed as extremely friable, the friability being 88.0 percent. The agglutinating index (7.6 for the 15 : 1 ratio of silicon carbide to coal) is high, and the plasticity as indicated by the Gieseler test (60 divisions per minute) is low for a high-volatile A coal.

Jan 1, 1942

By M. Didyk

The final objective of a mine ventilation project is to find a way of supplying the working faces with the necessary quantity of air to dilute all the possible air contaminants to safe limits and to maintain the temperature, humidity and oxygen content within desirable limits. To accomplish the aforesaid, decisions have to be made at early stages of planning and design of a mining operation. That is, ventilation and mine planning are closely related and interdependent, and experience has proved that improvisation as related to mine environment is rarely optimal in ventilation engineering. Mine management should be concerned with two general aspects of ventilation problems. The first is related to the statuatory requirements which are usually the minimum standards that have to be maintained. During the last two decades, mining laws have become increasingly stringent and management of operating mines had to face the effects of these externalities. In some cases these required either a production rate reduction or additional mine development. The second aspect that management should not overlook is the technical and economical importance of mine ventilation on the overall mining cost. In coal mining it is necessary to move, on an average, five tons of air through the mine for each ton of coal produced. The power cost incurred is perhaps the single most important direct cost assigned to ventilation but it is not the only one. Other costs that should be considered include the supervisory labor cost, fan depreciation and maintenance, doors, stoppings and regulators construction cost and maintenance, the additional mine airways development and maintenance because of ventilation requirements. That is,

Jan 1, 1977

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 Bruce K. Cantrell, Winthrop F. Watts

The U.S. Bureau of Mines and others have conducted a number of occupational exposure surveys since the publication of the International Agency for Research on Cancer report of 1989(1), which labeled diesel exhaust as a probable human carcinogen. These surveys have assessed diesel exhaust exposure using measurement of diesel aerosol and/or specific polycyclic aromatic hydrocarbons as indicators of exposure. This report reviews, available diesel exhaust aerosol and gas measurement techniques. Measurement of human exposure to toxic agents is the first step in determining the exposure-dose-response relationship. It is a fundamental step in risk assessment. Measuring exposure to diesel exhaust pollutants is particularly challenging due to the complexity and variability of exhaust components. This paper reviews current occupational health standards for diesel emissions and available diesel exhaust gas and aerosol measurement techniques. Although surveys in mines have primarily assessed diesel exhaust exposure using diesel particulate matter (DPM) some exhaust gas measurements have been used as indicators of exposure. DPM is emphasized because it is a major component of diesel exhaust, is suspected to make a major contribution to the health hazard, and is measurable. OCCUPATIONAL HEALTH STANDARDS Occupational exposure surveys of diesel exhaust frequently measure regulated pollutants, or pollutants that are suspected carcinogens, even if no permissible exposure limits (PELs) have been established. In the United States, various organizations recommend a range of allowable values for diesel exhaust gaseous constituents, including carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO.), nitrogen dioxide (NO2), nitric oxide (NO), and formaldehyde (HCHO). Table I summarizes these recommended levels, showing 8-hour or 10-hour time-weighted-average values where available; where these are not available, 15-minute short-term [ ]

By L. M. Burman

The phase-boundary pressure required to maintain a natural hydrocarbon fluid in a single phase must be considered in planning the recovery of reservoir liquids by miscible-phase processes. The change in the phase-boundary pressure at reservoir temperature that results when a light component or a mixture of light components is added to a reservoir fluid is an especially important consideration. The cricondenbar pressure (maximum phase-boundary pressure) and the critical pressure are unique correlated pressures that have been utilized to calculate the change in phase-boundary pressure that may result when the composition of a reservoir liquid is altered by an additive. In this study one reservoir oil and three gas-condensate fluids are used as examples. Correlations pertaining to the critical and cricondenbar states in chapters 4 and 5 of Bureau of Mines Monograph 10 (3)5 were used to demonstrate how butane and lighter components added to these reservoir fluids affect their phase-boundary pressures.

Jan 1, 1962

By Kathleen Kowalski-Trakofler, Edward Barrett

Problem: It is estimated that 5 to 10 arc flash explosions occur in electric equipment every day in the United States. In the mining industry the largest single injury category of electrical injuries are caused by non-contact electrical arcs. Method: This investigation progressed in two phases: (a) 836 Mine Safety and Health Administration (MSHA) reports of electric arcing incidents that occurred over a period of 11 years were reviewed, and (b) personal interviews were conducted with 32 individuals. A theoretical Safe Job Performance Model guided the study. Results: Behavioral dimensions were identified and included the effect of worker experience, judgment and decision-making ability, behavioral and organizational controls, and safety culture. Summary: The National Institute for Occupational Safety and Health (NIOSH) conducted an investigation of behavioral components associated with arc flash incidents and developed recommendations for interventions based on findings. Impact on Industry: This study fills a vacuum in electrical training with a focus on the organizational and behavioral aspects of arc flash incidents. There search is cross-cutting in its scope, in that the results apply not only to mining and construction, but many other industries employing electricians. Although the majority of mine electrical injuries are the results of burns from electrical arcs, few miners are aware that such a hazard exists. A safety training program, which includes a video and an instructor&apos;s discussion guide, was developed for electricians based on this study&apos;s findings. “Arc Flash Awareness” was released in 2007 (DHHS NIOSH PublicationNo.2007-116D) and is available through1-800 CDC-INFO. Phone:1-800232-4636 or email cdcinfo@cdc.gov. It is also available from MSHA at MSHADistribution@dol.gov or 304-256-3257 (DVD-576). Private industry is producing Portuguese and Spanish language translations.

"There is considerable evidence that all mine dusts do not present the same health hazard. Rank of coal and composition, especially silica content of the mine dust, shape, and surface charge are risk factors that affect the incidence and severity of CWP. Current efforts of Center researchers involve characterization of:•,size/shape/composition•,surface and functional groups•,particle interactions.Work is underway to prepare and characterize respirable coal dust samples, and to develop and evaluate techniques and procedures for the characterization of respirable dust. A suite of standard samples including anthracite, medium volatile and high volatile bituminous coals, quartz, clay, and rock dust have been prepared and thoroughly characterized with respect to the distributions of particle size and compositions. A comparison of the morphology of the standard dust particles with similar particles collected in an underground coal mine is given in Figure 43. Samples of these characterized (Standard) dusts have been distributed among various research groups associated with the Center.The aerodynamic diameter of a particle is a particularly important characteristic since this parameter determines the point of deposition in the human respiratory tract. A 3-dimensional numerical model for theoretically determining the equivalent aerodynamic diameter of irregular shaped particles has been developed and used to analyze coal dust particles and a particle shadowing technique has been developed for .experimental 3-dimensional shape analysis (Figure 44). In the theoretical technique, the equivalent aerodynamic diameter of the particle is numerically determined from computation of the fluid drag on the particle. This allows the aerodynamic diameter of any regular or irregular shaped particle to be determined as a function of the particle's orientation or as an average over all particle orientations. The technique is quite accurate in that the aerodynamic diameter of several coal dust particles have been numerically determined to be within 5% of experimentally measured values."

Nov 1, 1988

By J. J. Jakosky, D. H. Zellers

"IntroductionThis paper is the seventh of a series describing an investigation being conducted by the Bureau of Mines on underground communication. A review of past work and results obtained has been published. The present paper deals with a study of line-radio or wired-wireless methods of communication, herein electrical energy is transmitted by metallic conductors.The use of line-radio over metallic conductors has been practiced for a number of years, and at present is being used on a large scale in long-distance carrier-current telephone and telegraph. The early work of the U. S. Army Signal Corps and the Bureau of Standards in using ordinary radio transmitting and receiving apparatus for communication over metallic conductors was been descried. Later publications describe commercial applications, and an excellent treatise and resume is given by E. Colpitts and C. B. Blackwell.Scope of ReportThis report contains (1) a discussion of the chief factors affecting carrier-current transmission, with particular reference in application to underground communication for mines; (2) a description of typical underground circuits used for power and lighting; and (3) description of apparatus used and results obtained in line-radio experiments in coal mines near Pittsburgh, with circuit diagrams, and conclusions as to power requirements and limitations for mine use."

Apr 1, 1925

In presenting this list of permissible explosives and blasting devices, the Bureau of Mines desires to call attention to pages 17 and 23, outlining the conditions in use under which, and only under which, the explosive or blasting device is permissible. In view of publications recounting trade practice favoring the use of a blasting device without stemming, particular emphasis is placed upon condition 4 on page 17 and condition 2 on page 23. An explosive or y blasting device enumerated in the permissible Lists of thin Bureau is not permissible in use unless it is properly confined with clay or other incombustible stemming.

Jan 1, 1941

By John L. Reuss

A laboratory study was conducted by the Bureau of Mines to investigate the technical feasibility of decomposing hydrous magnesium chlorides by using a steam pyrohydrolysis technique. This procedure consisted of injecting steam into the atmosphere of a decomposition furnace containing samples of hydrous magnesium chloride and determining the rate of hydrolysis by measuring the rate of chloride evolution. The variables investigated were temperature, amount of water vapor in the decomposition atmosphere, and hydration stage of magnesium chloride. The application of steam was shown to accelerate both the rate and completeness of magnesium chloride decomposition reactions. For example, when magnesium chloride hexahydrate is exposed to a furnace temperature of 600&apos; C in an air atmosphere for 20 minutes, the decomposition is 37 percent. Under identical conditions in a steam atmosphere, the decomposition is in excess of 70 percent. The magnesium oxide produced by the steam pyrohydrolysis of magnesium chloride dihydrate at 800° C contained 98 percent magnesium oxide. Based on magnesium oxide composition, this is equivalent to that of burned magnesite produced at temperatures in excess of 1,300° C. To demonstrate the quality of the product on a practical basis, metal reduction tests have shown it to be equivalent to reagent-grade magnesium oxide as a carbothermic reduction feed material.

Jan 1, 1974