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By Stephen Krickovic

Air quantity-pressure and methane concentration surveys were conducted by the Bureau of Mines in accessible portions of an area being pillared in a Pittsburgh coalbed mine in West Virginia. These included two mined-out and three active butt headings and a bleeder system. The particular mine workings were started in virgin coal directly from a set of main headings; the main reason for the study was the difficulty usually encountered in adequately bleeding the gobs under such conditions. Although the two separate return airways in each active butt heading and the North and 1 Left bleeders contained acceptable methane concentrations (0.01 to 0.78 percent in the butts and 0.73 to 1.0 percent in the bleeders) with significant total methane removal (109 cfm in butts and 631 cfm in bleeders), there were relatively large areas in the gobs with possible minimal airflows. This condition appears to have developed from lack of systematic regulation of the airflow across the gobs and appears to indicate the existence of considerably more methane in the probably low flow areas in the gob.

Jan 1, 1973

By W. E. Wallace, B. L. Razzaboni, P. Bolsaitis, M. J. Keane

"Therma1 and chemical treatment of respirable size silica dusts samples is shown to induce marked changes in their hemolytic activity. The cytotoxicity of crystalline a-quartz (Min-U-Sil), and fumed silica (Cab-0- Sil) particles, as measured by a hemolytic activity protocol, is decreased by calcination and can be related to the dehydroxylation of the surface. The hemolytic activity of P-cristobalite particles of respirable dust si7.e was also determined and found to be lower than that of a-quartz. The change in the surface structure resulting from thermal treatment is detectable by photo-acoustic infrared spectroscopy and zeta-potential measurements. The absorption band in the 3200-4000 cm-1 frequency region of both Cab-0-Sil and MinU- Sil disappears upon heat treatment while a sharp band, identified with single silanol groups, at 3750 cm-1 increases in intensity. The zeta potential-pH profile, in the pH range of 4.0-7 .0, of the calcined, siloxane surfaced particles is more negative than that of material with a silanol surface.The cytotoxicity of the crystalline and fumed silica dusts was also found to be strongly dependent on particle size. Fumed silica of large surface area (small particle size) exhibits an initial increase in hemolytic activity upon calcination. This result confirms other experimental observations pointing to a particle size of maximum toxicity. INTRODOCTIONThe toxicity of silica and other mineral particles, as manifested by their role in inducing pneumoconiosis, fibrosis, silicosis and other pulmonary disorders is largely traceable to the characteristics of particle surfaces and to particle morphology. The great wealth of data on the physical and chemical properties of silica is still insufficient for a comprehensive understanding of the specific parameters to be associated with fibrogenic activity and, correspondingly, with the optimum means for characterizing and quantifying the toxicity of dusts, and the design of possible preventive or therapeutic methods.The great diversity of parameters that have been proposed and tested for correlation with cytotoxicity suggest that more than one mechanism may be involved in the fibrotic activity of silica particles. The crystalline structure of the material (more active tridymite versus less active crisobalite and passive stishovite), freshly formed surfaces and free radicals associated therewith, silicic acid adsorbed onto silica surfaces, the concentration of hydroxyl groups at silica surfaces, particle size and morphology, among other properties, have been investigated and found to conelate in tests of cytotoxicity."

Jan 1, 1990

By D. S. Kingery

Investigations over several years have disclosed that the principal manners of occurrence of shuttle-car injuries are in order: 1. Victims in contact with roof or crossbars. 2. Victims in contact with ribs or timber legs. 3. Victims falling from, or jerked from, shuttle cars. 4. Victims in contact with overhanging brows or protruding pine for pin timbers, or water lines. 5. Contact with persons or collisions with parked equipment. 6. Victims injured by roof falls or falling timbers caused by knocking out roof supports with shuttle cars. 7. Victims injured by runaway shuttle cars. 8. Victims injured while loading or unloading timbers or other materials from shuttle cars. These recurring types of shuttle-car accidents reflect the physical conditions of the working sections, certain safety deficiencies in shuttle-car maintenance and design, and unsafe practices by operators.

Jan 1, 1952

By F. E. Cash

Among petroleum refinery employees and officials throughout the United States there has been marked effort to reduce accident frequency and severity. For the interest and benefit of refineries both in Louisiana and in other petroleum-refining States it has been possible to obtain from five refineries, representing 70 per cent of the production of Louisiana, tae accident experience for the past 3 to 6 years. The companies concerned have requested that their names be not used. For tide reason the four plants listed and discussed are designated as refineries A, E, C, and D. The size of the plant as regards largest to smallest number of employees is indicated by the alphabetical order.

Jan 1, 1933

By John J. Sammarco, Janet S. Flynt

This report (Independent Functional Safety Assessment Guidance 7.0) is the last in a nine-part series of recommendations and guidance addressing the functional safety of processor-controlled mining equipment. It is part of a risk-based system safety process encompassing hardware, software, humans, and the operating environment for the equipment’s life cycle. Figure1 shows a safety framework containing these recommendations. The reports in this series address the various life cycle stages of inception, design, approval and certification, commissioning, operation, maintenance, and decommissioning. These recommendations were developed as a joint project between the National Institute for Occupational Safety and Health and the Mine Safety and Health Administration. They are intended for use by mining companies, original equipment manufacturers, and after-market suppliers to these mining companies. Users of these reports are expected to consider the set in total during the design cycle. • 1.0 Safety Introduction (Part 1).—This is an introductory report for the general mining industry. It provides basic system/software safety concepts, discusses the need for mining to address the functional safety of programmable electronics (PE), and includes the benefits of implementing a system/software safety program. • 2.1 System Safety (Part 2) and 2.2 Software Safety (Part 3).—These reports draw heavily from International Electrotechnical Commission (IEC) standard IEC 61508 [IEC 1998a,b,c,d,e,f,g]and other standards. The scope is “surface and underground safety-related mining systems employing embedded, networked, and nonnetworked programmable electronics.” System safety seeks to design safety into all phases of the entire system. Software is a subsystem; thus, software safety is a part of the system’s safety. • 3.0 Safety File (Part 4).—This report contains the documentation that demonstrates the level of safety built into the system and identifies limitations for the system’s use and operation. In essence, it is a “proof of safety” that the system and its operation meet the appropriate level of safety for the intended application. It starts from the beginning of the design, is maintained during the full life cycle of the system, and provides administrative support for the safety program of the full system. • 4.0 Safety Assessment (Part 5).—The independent assessment of the safety file is addressed. It establishes consistent methods to determine the completeness and suitability of safety evidence and justifications. This assessment could be conducted by an independent third party. • Safety Framework Guidance.—It is intended to supplement the safety framework reports with guidance providing users with additional information. The purpose is to assist users in applying the concepts presented. In other words, the safety framework is what needs to be done and the guidance is how it can be done. The guidance information reinforces the concepts, describes various methodologies that can be used, and gives examples and references. It also gives information on the benefits and drawbacks of various methodologies. The guidance reports are not intended to promote a single methodology or to be an exhaustive treatment of the subject material. They provide information and references so that the user can more intelligently choose and implement the appropriate methodologies given the user’s application and capabilities. The guidance reports comprise parts 6 through 9 of the series and are listed below: [< 5.1 System Safety Guidance (Part 6).—This guidance supplements 2.1 System Safety. < 5.2 Software Safety Guidance (Part 7).—This guidance supplements 2.2 Software Safety. < 6.0 Safety File Guidance (Part 8).—This guidance supplements 3.0 Safety File. < 7.0 Independent Functional Safety Assessment Guidance (Part 9).—This guidance supplements 4.0 Independent Functional Safety Assessment.] [ ]

Jan 4, 2006

By K. E. Tame

As part of a Bureau of Mines survey of radioactive waste disposal , a laboratory investigation was made to study such problems in carbonate leaching mills . Because uranium concentrators employing carbonate leaching with caustic precipitation normally recycle barren solutions to the washing circuit , the disposal of liquid radioactive wastes is automatically controlled . However , it was deemed important to determine the actual radium 226 concentrations occurring in this type of milling so that the survey of the entire industry would be complete . The laboratory procedure consisted of leaching the ground ore at 85 ° to 90 ° C and 50 pct solids for 6 hours in a sodium carbonate - sodium bicarbonate solution . The pulp was filtered to obtain a pregnant solution that was reacted with sodium hydroxide to precipitate the uranium as sodium diuranate . Regeneration of the barren solution was accomplished by gassing with carbon dioxide . The solution then was reused by advancing the solution through the washing to the leaching operations . The radioactivity in the pregnant solution was unusually high , averaging 6,500 disintegrations per minute ( dpm ) of radium 226 per liter . However , over 95 pct of the radium was precipitated with the uranium . Consequently , no buildup of radium occurred upon reuse of the barren solutions for washing .

Jan 1, 1964

By Robert H. Peters

How can employees be stopped from engaging in unsafe work practices? It is often easier to prevent employees from performing unsafe acts through manipulations of the work environment than through various training or motivational programs. Therefore, it is important that accident prevention programs seek to identify the reasons for the unsafe behavior and to redesign tasks and the work environment (e.g., tools, equipment, physical surroundings) in order to remove employees from sources of harm and to prevent situations from arising that would prompt them to perform unsafe acts. Unfortunately, in the mining industry the work environment is often innately hazardous, rapidly changing, and difficult to predict, making it very difficult, perhaps impossible, to fully protect the employee by environmental manipulations. Therefore, it is important that effective methods be identified for influencing mine employees to work safely. Various strategies have been used to convince employees to avoid unsafe acts and/or adopt self protective behaviors. The intent of this article is to provide guidance to mine operators concerning the use of four techniques for influencing mine employees to work safely: (1) employee surveys, (2) incentives, (3) fear communications, and (4) disciplinary actions.

By William Seymour, L. D. Schmidt

A preliminary survey of coke and steel plants conducted by the Bureau of Mines in cooperation with the Office of the Solid Fuels Administrator for War and with the advice of the Coke Production Committee indicated that production of pig iron could be increased. appreciably if present blast furnaces were supplied with a more uniform coke.4/ Nonvarying percentages of ash , sulfur , and fixed carbon in the coke , together with uniform physical characteristics , such as size , strength , and porosity , would aid the blast -furnace operator greatly in his trial - and - error methods of obtaining maximum production . With nonuniform raw materials he must employ certain factors of safety in operation , such as an excess of coke , an excess of limestone , and operation of the furnace below the maximum rate . Even so , he often has trouble from iron not being up to specifications , hot tops , high blowing pressures , furnace hanging up , etc. The more uniform his raw materials (of which coke is probably the most important) , the nearer to ideally can he run his furnace and thereby save raw material and increase production . One cause of nonuniformity of the coke produced by ordinary American plant practice is the prevailing lack of precise control of the bulk density ' of the coal charge in the byproduct oven . This report summarizes the available information on the subject of bulk density of crushed coal and its control . It includes brief reviews of some of the literature , some results obtained at plants visited by the authors , and results of a few preliminary tests made at the Pittsburgh Station of the Bureau of Mines .

Dec 1, 1943

By L. J. Froisland

The Bureau of Mines conducted a 4-year research program at Uravan, Colo., on a 2-1/2-acre reclamation plot on the slope of a uranium tailings pile that had been covered with mine waste rock. The purpose of this study was to determine the effects of plant species, type of irrigation, type of fertilizers, and use of dust control chemicals on plant growth and surface coverage. Best grass coverage, nearly 100 percent with 240 plants per square foot, was developed in a section that was seeded with crested wheatgrass, fertilized with sewage sludge, and sprinkler irrigated. For comparison, a section that had been treated with commercial fertilizers developed 3.1 crested wheatgrass plants per square foot and 24 percent coverage without irrigation, and 8 plants per square foot and 75 percent coverage with irrigation. Results of spraying a dust control chemical were inconclusive. Russian-thistle invaded all test sections and ranged in density from 0.6 to 7.3 plants per square foot.

Jan 1, 1982

By G. L. Neumann

The Andover-Sulphur Hill iron mines in Sussex County, N. J., have a production record extending over 100 years. The last production recorded was about 1880. These mines produced high-grade ore of two types: Bed ore (hematite) and blue ore (magnetite. Some sulfides (lead, zinc, and copper) were found underlying the iron deposits. Data as to size and grade of these sulfide bodies are very sketchy, Toward. J. Hewitt of Elizabeth, N. J., lessee of the Sulphur Hill mines from 194045, prospected for lead, zinc, and copper. .His Only production was several hundred tons of low-grade iron ore, which was crushed and used as heavy aggregate to make concrete blocks for ship ballast. In October and November 1942 made a magnetic survey of this area and bored six-diamond-drill holes with the dual objective of prospecting for sulfides and testing for extensions of the iron-ore deposits indicated by the magnetic survey. In 1944, an iron-mining company examined this property and diamond-drilled seven holes Between December 1949 and March 1950, the Bureau Of Mines in search of sulfide deposits, bored three additional diamond-drill holes. Two of these were on the Sulphur Hill tract and one on the adjoining Tar Hill tract.

Jan 1, 1952

By G. W. Elger

This report describes pilot-plant studies and an economic evaluation of a process developed by the Federal Bureau of Mines, Albany Metallurgy Research Center, to produce synthetic rutile from a rock-type ilmenite concentrate. In this process, ilmenite blended with coke and lime is smelted in an electric arc furnace to separate most of the iron as salable pig iron and to form a titania-enriched slag of low iron content, which is treated with oxygen and titanium pyrophosphate. The titanium oxides are converted to crystalline rutile; the phosphate glass contains most of the associated impurities. The treated slag is ground and leached with sulfuric acid to liberate rutile crystals, which are concentrated by physical methods. In pilot testing conducted to obtain data for a cost estimation, a synthesized product containing about 88 wt-pct TiO2 and less than 2 pct FeO was extracted from a rock-type ilmenite concentrate containing about 45 wt-pct TiO2. The estimated fixed capital cost (on a mid-1975 basis) of a plant producing 500 tpd of synthetic rutile is $28,290,100. Based on 330 operating days per year, the estimated operating cost for this process is $351 per ton of synthetic rutile. The estimated selling price of synthetic rutile made from rock-type ilmenite is $344 per ton, based on a credit of $160 per ton of pig iron and a 20 pct interest rate of return on investment after taxes.

Jan 1, 1976

By Elaine Cullen, Launa Mallett, Mike Jenkins, C. M. K. Boldt, Thomas Camm

The material in this Information Circular was presented at the National Institute for Occupational Safety and Health’s (NIOSH) open-industry briefing held during the 2004 Northwest Mining Association conference in Spokane, WA. The open-industry briefing discussed results of recently completed and on-going mine safety- and health-related research conducted at NIOSH’s Spokane and Pittsburgh Research Laboratories on the human side of mining—the miner. The first paper sets the stage for what mining has achieved and what we mean by “getting to zero.” The second paper, “Help Experienced Miners Become Great On-the-Job Trainers,” distinguishes between experienced miners and trainers. This paper provides some key concepts for turning great miners into great trainers. “The Power of Story-Telling in Getting Through to Miners” explains the history and importance of stories in the culture and training of miners. Finally, “Understanding Self in Stressful Working Environments,” describes the personal and social aspects of the working environment, much of which parallels familial theories. The downward trend of deaths in U.S. mining has been remarkable. The number of miners killed or injured each year has decreased steadily over the past 100 years. Some charts show these trends overlain with important events such as World War II and the Mine Safety and Health Act. However, this downward trend in mining fatalities has flattened out. How can you get to zero accidents? Do you concentrate on technological advances and equipment maintenance to avoid malfunctions? Do you concentrate on developing work processes and organizational structures that minimize risk? Do you combine them and take a systems approach that links one to the other with an evaluative loop? Safety efforts in mining have used all of these approaches. What more can we do to get to zero? Getting to zero will require two objectives: A clear and unshakeable belief that it can be done and attention to the human side of mining. Getting to zero is not a new idea; it has been used by mine companies and safety professionals for years as the safety goal. But getting to zero is not so much a physical goal as it is a belief that there are no insurmountable barriers to achieving the goal.

Jan 3, 2006

By Jr. Dubaniewicz, Gregory M. Green, Kenneth L. Cashdollar

Laser-based instruments are used in areas where coal dust ignition presents a safety hazard. The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory ~NIOSH, PRL! is conducting a study to help determine when an optical beam may be considered a potential ignition source in underground coal mines or coal storage facilities. Researchers conducted experiments to determine threshold igniting powers for Pittsburgh seam bituminous coal dust clouds using an 803 nm continuous wave laser. For fine sized coal dust dispersed in air, concentrations ranging from 600 to 2000 g/m3 were the most easily ignited. A heated layer of coal dust that deposited on the fiber tip during dispersion ignited the dust clouds. Minimum observed igniting powers for laser beams delivered by 200, 400, and 800 mm core fiber optic cables and directed into coal dust clouds were 2.0, 3.0, and 5.0 W, respectively. Threshold igniting power was proportional to beam diameter, and threshold igniting power density decreased with larger fiber diameters. Ignition delay times averaged 0.6 s and did not vary significantly with laser power under initially turbulent test conditions and with flammable targets. Comparisons are made with the results of other researchers.

By A. L. Johnson

In this Bureau of Mines report, time-resolved infrared emission spectra and corresponding pressure and temperature histories are reported for large-scale propagations of CH4-air, CH4-air-N2, and CH4-air-CF3Br ignitions in a 12-ft-diam sphere. Absolute spectral radiances were obtained throughout combustion over the 1.6- to 4.8-gym range, and the radiance growth patterns for the H20 (2.5-µm) bands are presented as a function of methane stoichiometry and diluent concentration. Flame temperatures were determined from the C02-band emissions, which approximated unit emissivity shortly after ignition. Burning velocities are also given for some of the test-mixture compositions. Measured flame temperatures were in excellent to fair agreement with theoretical adiabatic values for the CH.-air and CH4-air-N2 mixtures; the best agreement was for the stoichiometric CH4-air mixture. The CH4-air-CF3Br mixtures with =2 pct CF3Br gave poor agreement with theory. The measured temperatures were significantly lower during the early stage of combustion; furthermore, the later stage of combustion was uninhibited and yielded unexpectedly high pressures. Supplemental data from a 2-ft-diam sphere at various initial pressures confirmed that the CF3Br inhibition effectiveness decreases with increased pressure. The possible effects of buoyancy, turbulence, and changing kinetics are discussed.

Jan 1, 1977

By Robert F. Chaken

The National Institute of Occupational Safety and Health (NIOSH) is dedicated to achieving "safety and health at work for all people -- through research and prevention." An important procedure in pursuing this goal is the NIOSH surveillance studies where the number of injuries are monitored according to demographic, employment, and injury characteristics. These numeric data are then used to identify injury risk factors, develop safety programs, and monitor implemented remediation methods. In essence, ongoing surveillance data form the bases for directing the resources of NIOSH in setting of research and prevention priorities, and in evaluating safety procedures. This surveillance techmque, which is based on the Public Health Service approach to identification and control of disease (1, 2, has been used quite successfully in dealing with relatively high number injuries such as hearing loss, musculoskeletal disorder, respiratory disorder, falls, etc. (2). However a problem arises when extending this paradigm to lower frequency traumatic events; particularly those often referred to as disasters (i.e., high impact events like mine explosions, airplane crashes, etc.). One can ask the question - there hasn&apos;t been a coal mine fire fatality in the U.S. for over ten years, to what extent should we be concerned with mine fire safety (resource-wise)? - The National Traumatic Occupational Fatalities (NTOF) system (4J which NIOSH uses to survey occupational fatalities annually, would suggest that underground mine fires would not be a high priority item in occupational safety. Yet, miners&apos; (i.e., the exposed workers) do consider mine fires and explosions to be major safety concerns. I believe that we need to rethink our evaluation of work place disasters, what is worker exposure, and what are the underlying assumptions (both explicit and implicit) as to the impact that economic, societal and degree of hazard factors make on risk evaluation. The answers to all these problems, will require much broader considerations than those in current surveillance safety and health models. This paper discusses some facets of those considerations.

By R. A. Friedel

Data on compositions of natural substances are important in the study of possible interrelationships. The similarity of the low molecular weight alkane isomers from crude oil and Fischer-Tropsch catalytic synthesis product has been reported (8).3 A similar composition for the alkane isomers from high-temperature coal carbonization has been found. The composition of the C4 to C 7 alkane isomers from these three sources can be calculated quantitatively with the equations previously developed to calculate alkane isomers in Fischer-Tropsch product. An KM sting reversal of the concentrations of the monomethyl isomers from C6(2 Me > 3 Me) to C7 (3 Me > 2 Me) occurs in all three products; fragmentary comparisons at higher carbon numbers indicate some dissimilarities. Naphthene isomers in the C6 to C7 range for crude oil and high-temperature coal carbonization also have similar compositions. Aliphatic hydrocarbons from low-temperature coal carbonization processes are considerably different, consisting mainly of normal alkanes.

Jan 1, 1968

By Seth C. Schaefer

[As part of the Bureau of Mines effort to provide thermodynamic data for advancement of mineral resources technology, the standard Gibbs energies of formation (?G°f) of MnS (manganese sulfide) and Fe0.9 S (pyrrhotite) were investigated with a high-temperature galvanic cell employing stabilized Zr02 (zirconia) as the electrolyte. Potential measurements were obtained for the cell Pt, MnS, MnO, S02 (g, 1 atm)//Zr02//02(g, 0.0114 atm), Pt with the overall cell reaction MnS (s) + 1.5 02 (g, 0.0114 atm) = MnO (s) + S02 (g) . (1) These results give the standard Gibbs energy of formation of MnS for the reaction Mn (s) + 0.552 (g) = MnS (s) (2) ?G°f = -66.487 + 15.19 x 10-3T±0.207 kcal/mole (896.4 - 1,208.1 K) (3) where temperature (T) is expressed in kelvins. Similar measurements were obtained for the cell Pt, FeO .9S, Fe304 , S02 (g, 1 atm) //Zr02//02 (g, 0.0114 atm) , Pt with the overall cell reaction 10/3 FeO .9 S (s) + 16/3 02 (g, 0.0114 atm) = Fe.,04 (s) +10/3 S02 (g). (4) These results yield the standard Gibbs energy of formation for the reaction 0.9 Fe (s) + 0.5 S2 (g) = Fe0.9 S (s) (5) ?G°f = -35.229 + 12.67 x 1073T+-0.104 kcal/mole (839.5 - 1,086.6 K). (6) A third-law analysis of MnS data yields a standard enthalpy of formation (AH°f) for the reaction Mn (s) + S (rh) = MnS (s) (7) ?H°f298 = -51.16±0.21 kcal/mole (8) A similar third-law analysis for Fe0.9S data yields a ?29°f298 for the reaction 0.9 Fe(s) + S(rh) = FeO .9S(s) (9) ?HO\°f298 = -24.01±_0.15 kcal/mole. (10) ]

Jan 1, 1980

By Edward D. Thimons

The Bureau of Mines has developed a damage-resistant brattice, intended for use as a stopping in locations where blast damage to stoppings is a problem, the roof is relatively flat, and the differential pressure across the stopping is not high. Damage-resistant brattices consist of a series of vertically hung brattice panels joined to each other by Velcro connections that improve the airtightness of the brattice. When the brattice is subjected to strong blast forces, the Velcro connections peel apart, allowing the panels to open without incurring damage. The Velcro connections can then be resealed in a matter of minutes. A preliminary test in the Bureau&apos;s Safety Research Mine and subsequent long-term testing at the White Pine copper mine in Michigan and the Retsof salt mine in New York show that damage-resistant brattices withstand blasting better than conventional stoppings, while still performing as efficient air barriers when the Velcro connections are sealed.

Jan 1, 1978

By Thomas A. Phillips

The Bureau of dines present, an economic evaluation of its process for the ferric chloride leaching of chalcopyrite concentrate. In this process, chalcopyrite concentrate is leached with ferric chloride solution to extract copper, which is precipitated from the solution by electrolysis while leaving sulfur in the residue. Spent liquor from electrolysis is treated with oxygen to regenerate the ferric chloride leach solution and the sulfur-laden residue is processed to recover the sulfur. A cost estimate was prepared for a plant capable of processing 600 tons of chalcopyrite concentrate per day, 330 days per year. The fixed capital cost, on an early 1.975 basis is $27,831,600 and the estimated operating cost is 9.9 cents, per pound of copper product. In comparison, the estimated operating cost of a smelter equipped with a citrate process plant to recover sulfur is about 13.6 cents per pound of copper product. No charge for chalcopyrite concentrate or credit for recovered byproducts has been included in either operating cost. The ferric chloride leach process, therefore, appears to be economically attractive.

Jan 1, 1976

By Bernard Porter

The solubility of UO2 was determined at 1,250° C. in ternary melts of UF4 and BaF2 with CaF2, LiF, and SrF2. The solubility of Ce02 was measured at 800° and 850° C. in a solution of CeF3, BaF2, and LiF. The amount of La203 which dissolves at 950° C. in a binary mixture of LiF and LaF3 and a ternary of LiF, LaF3, and BaF2 was also measured. In each case, the amount of soluble oxide was mound to be less than 5 weight-percent. A procedure was developed for filtering fused, oxide-saturated fluoride melts in order to obtain a representative sample for chemical analysis. The oxide content of the samples was determined by an inert-gas fusion procedure.

Jan 1, 1961