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By W. L. Anderson

Standard tellurium analytical procedures were modified to obtain the greater sensitivity needed to support a survey of tellurium resources by the Bureau of Mines. Resulting volumetric and spectrophotometric methods for determining tellurium in all types of tellurium-containing materials are described. Sample decomposition and preliminary separations of interfering selenium, gold, and silver are the same in both procedures. The volumetric method is applicable to samples containing a minimum of 10 parts per million of tellurium, In this method the tellurium is reduced to elemental form, and the colloidal suspension is titrated with 0.01 normal iodine solution. The weight of sample for analysis, from 0.25 to 10 grams, should be selected so that the sample contains 0.1 to 5 milligrams of tellurium. To insure accuracy, duplicate samples should be run and the results averaged, particularly on samples of low tellurium content: The limit of determination is 0,001 percent tellurium, which is equivalent to 0.1 milligram of tellurium when using a 10-gram sample. The spectrophotometric method is particularly applicable to low-tenor materials containing from 0.5 to 50 parts per million of tellurium. Up to 10 gram samples are required for making accurate determinations in the low-concentration range. The sample used should contain between 5 and 100 micrograms of tellurium. The turbidity of a colloidal suspension of tellurium prepared from such a sample is determined in a spectrophotometer .t at a. wave-length of 440 millimicrons, and this value is compared with those of standard samples containing known amounts of tellurium.

Jan 1, 1963

By H. B. Brunot

A complete list of permissible mine equipment, tested and approved by the Bureau of Mines previous to January 1, 1947, was published as Information Circular 7432.2/ A list of permissible mine equipment tested and approved by the Bureau of Mines during the calendar years 1947, 1948, and 1949 was published as Information Circular 7569. The present list supplements Information Circulars 7432 and 7569 and includes all of 'the equipment approved during the calendar year 1950. Information Circular 7465, which included a list of permissible mine equipment tested and approved by the Bureau of Mines during the calendar year 1947 therefore is superseded.

Jan 1, 1951

By L. C. IlsLey

Cooperation between the United States Bureau of Mines and the Safety in Mines Research Board of Great Britain, continuous since 1924, has made possible this and other papers on safety subjects. Grateful acknowledgment is made to representatives of the Safety in Mines Research Board of the Mines Department for their assistance in arranging visits to several mine safety stations, and to F. R. Wynne, Deputy Chief Inspector of Mines, Great Britain, for arranging visits to mines in Great Britain, Belgium, Germany, and France. During the summer of 1927 the writer had the privilege of visiting the mine safety testing stations in Great Britain, Belgium, Germany, and France, in the order named. All of these countries have large coal mines, many of which are rated as gassy. Therefore, when installation of electrical equipment is contemplated, each of these countries is confronted with the same safety problem as is the United States - the development of electrical equipment that will not ignite gassy mine atmospheres which might, through neglect or accident surround the equipment. The means used by these countries in safeguarding gassy mines should therefore be of general interest to safety engineers of American coal mines, and it is proposed to give a brief survey for each of the four countries mentioned. This paper presents the second of these surveys, which covers conditions in Belgium.

Jan 1, 1929

By L. C. IlsLey

"There are two general classes of accidents that prevail in and about mines, namely - (1) those that through the nature of mining work can only be lessened, and (2) those that by proper precaution can be eliminated altogether. Explosive accidents that ordinarily take place while explosives are being transported in and about mines belong to the second class, that is, by proper care all such accidents can in general be avoided.The following table gives a brief summary of several accidents and disasters that have occurred in the United States and indicates the need of universal preventive measures as a basic part of all State regulations.ACCIDENTS AND DISASTERS OCCURRING WHILE TRANSPORTING EXPLOSIVES.***"

Sep 1, 1923

By K. K. Kershner

The purpose of this research by the Federal Bureau of Mines was to investigate the recovery of tin from mine-run ores and low-grade concentrates. Over 95 percent of the total tin in such materials was volatilized to tin chlorides at temperatures ranging from 520° to 565° C. Gaseous mixtures of hydrogen and hydrogen chloride were used for reducing cassiterite to stannous oxide and for converting this compound to tin chlorides. The chlorides were swept from the reaction zone of an oscillating kiln by a rapid flow of reactant gases and collected in a condensing system. Losses of tin that occur in current metallurgical processing were prevented. Approximately the same time of treatment was required for minus 35-mesh mine-run ores and low-grade concentrates. In a continuous process, the circulating gases would require some enrichment.

Jan 1, 1961

By Loyal Clarke, H. H. Storch

"The discovery of large deposits of polyhalite (K2S04.MgS04.2CaSO4.2H2O) in Texas has led to an investigation of possible industrial proecsses for the extraction of potash from this material. This mineral was first discovored in small quantities in the European potash deposits in or about the year 1800. Chemists fire thought it to be a form of calcium sulphate, but a more accurate analysis by Strohmiyer indicated the composition as given by the above formula.The decomposition of polytalite by aster is very slow and results in the formation of a layer of gypsum at the surface of the polyhalite which retarts the solution of the potaseium and magnesium sulphates. To obtain a substantial yield of K2S04 in solution it is necessary to use large amounts of water at room temperature, for he concentration of K2S04 is limited by the low solubility of syngonite (K2S04.CaS04.H2O) whereas at 100º C. several days boiling are necessary to obtain more than a 6 per cent K2S04 solution even when finely powdered polyhalite is employed.In 1854 H. Rose discovered that calcination, followed by leaching with water, resulted in a larger extraction of the potassium and magnesium sulphates, as compared with leaching without precalcination. During the course of a series of investigations concerning formation of oceanic salt deposits, Van't Hoff and his pupils obtained sufficient data to construct the equilibrium diagram for the system K+Mg+SO4--Ca++.H2O for 25° C. and for 83° C. These data are very well summarized. in the International Critical Tables' and by Boeke and Eitel. From a consideration of the diagrams for 83º C. one would conclude that an extraction of polyhalite with moderate amounts of water at 33º C. would result in a solution whose maximum concentration of K2So4 would be about 3.6 grams per 100 grams of water and of M2SO; about 4.0 grams per 100 grams of water, corresponding to equilibriumwith the solid phases: Polyhalite potassiam-calcium pentasulphate and anhydrite.The fact that it has been found possible to obtain as high as 11.4 grams of K2S04 per 100 grams of water (see table 6) and an equivalent amount of MgSo4 (8.1 grams per 100 grams of water was obtained corresponding to a ratio K2/Mg of 0.98; indicates that the formation of these complex salts is very slow. To be sure, this results was obtained at 100° C. instead of 83º C. However, the work of Anderson and Nestall 9 on the double salts of calcium and potassium sulphates at 100º C. indicates that the diagram at 100º C. C. would not be greatly different from that at 83º C. This slow rate of approach to equilibrium when combined with precalcination of,of polyhzli-,a is the 17,asis of some of the more p:olisinE methods of extracting potash from polyhalite."

Jun 1, 1930

By John C. Hartley

Three systems that monitor ventilating fans are described. These electronic monitoring systems automatically perform most of the operations required to conform with the provisions of the Federal Mine Safety Code in the event of fan failure or slowdown.

Jan 1, 1964

By V. R. Spironello

The Bureau of Mines is conducting studies of the slags related to ferrous technology to evaluate acceptable substitutes for the auxiliary flux, mineral fluorspar, in foundry operations. This work is directed toward the Bureau's goal of minimizing the Nation's dependence on scarce and critical minerals Comparative basic practice cupola (18-inch-ID) trials were made to evaluate a waste material called "used potlining," which contains significant levels of fluorine, sodium, and aluminum in various compounds. Used potlining is recovered from alumina reduction cells after its useful life, and was supplied by the Aluminum Co. of America (Alcoa) to the Bureau for evaluation. The material in the lump and pelletized form (with limestone) provided extremely fluid slags based on visual observation during cupola operation. No adverse effects were found on cupola performance, metal and slag chemistry, the environment, or mechanical properties of the castings produced. Fluorine recovery in the slag was equal to, or higher than, that of fluorspar; fluorine losses to the scrubber water and solids were lower. The acidity of the scrubber Hater was somewhat neutralized. No difference was observed in furnace-refractory attack, as determined by the level of magnesia in the slag and visual inspection. The recovery of sodium in the slag, presumably as the oxide, significantly increased slag fluidity, suggesting that less than equivalent fluorine may be required. There was no contamination of the gray iron by the aluminum from the used potlining. Used potlining was completely satisfactory as a substitute for fluorspar in cupola ironmelting.

Jan 1, 1981

By John R. Benham

The West Pioneer RARE II study area, No. 1-006 (fig. 1), has Figure 1.--NEAR HERE a high molybdenum resource potential. Two molybdenum-bearing areas are being explored by Utah International and by Cyprus-Moly Corp, Inc. using geophysical exploration and diamond core drilling. The study area also contains potential resources of gold and silver at six prospects: the Bear Paw (Ibex), Black Bear, Coeur d'Alene, Franklin No. 1, Martin, and Maynard. In addition, the Black Rear and the Martin contain possible copper, lead, and molybdenum resources. Most of the workings are caved.

Jan 1, 1981

By P. R. Bremmer

As part of a program to devise alternative technologies for producing alumina from domestic resources, the Bureau of Mines investigated the leaching of calcined kaolinitic clay to form basic aluminum chloride solutions. Bench-scale experiments were conducted for single-stage batch leaching with AICl3 solution and three-stage countercurrent leaching with substoichiometric HCI. Variable conditions of clay calcination and leaching were studied to determine their effects on aluminum extraction and pregnant liquor composition,

Jan 1, 1984

By B. H. Clemmons

A field method has been devised for rapid determination of heavy minerals occurring in the unconsolidatod beach and dune sands. The method has been proved practical by usage in field evaluations of several hundred beach- and dune-sand samples in the Florida area. The simple equipment required and the techniques involved are described. Other data show that the method is relatively insensitive to variations in the mineralogical content or size distribution of the mixed heavy minerals contained in the samples tested. A modification of this procedure, found to be suitable for plant use in determining the relative purity of heavy-mineral flotation concentrates, is also described. A specific application is determination of the amount of feldspar-quartz in spodumene flotation concentrates. The results of the rapid evaluation techniques closely approximate those obtained by more precise laboratory procedures.

Jan 1, 1957

By C. I. Pierce

The Bureau of Mines used an electrolytic tank model to investigate the response of guard electrodes of different dimensions under different simulated reservoir conditions. Sandstone disks from the Berea and Connellsville Formations were used as resistive beds in the model, and agar gel or water was used as conductive beds. In the experiments, bed thickness, hole diameter, mud resistivity, and bed resistivity were varied. The guard electrode is an excellent tool for determining true bed resistivity in the thin-bedded oil reservoirs of the Appalachian area. Vertical resolution and resistivity values are good when there is little or no invasion. Resistivity values are near true bed resistivity in beds thicker than about six hole diameters when the electrode-to-hole-diameter ratio is close to 1. However, low-resistivity muds cause false peaks to appear on the logs near bed boundaries in thick beds, and for resistive beds having a thickness approximately three to five times the hole diameter, apparent resistivities tend to be excessively high when mud resistivity is low.

Jan 1, 1966

By Marcia L. Harris

The National Institute for Occupational Safety and Health (NIOSH), as part of its continuing research program for evaluating coal dust explosion hazards, has investigated several areas in which current practices may need to be updated in order to adequately protect mines against coal dust propagated explosions. In the United States, current rock dusting requirements remained largely unchanged since 1969. US Title 30 Code of Federal Regulations Section 75.403 is based on a coal dust particle size survey performed in the 1920s and later was supplemented by full-scale testing of the rock dust ability to inert a coal dust explosion. NIOSH recently conducted a comprehensive survey of US underground coal mines to determine the range of coal particle sizes found in dust samples collected from the mine entries. Due to advancements in technology and modern coal mining techniques, the current coal dust particles in intake airways are significantly finer than those found in the mines in the 1920s. According to past full-scale dust explosion test results, the current rock dusting practices used in today?s mines to inert a coal dust explosion may not be adequate. Other closely related issues such as rock dust testing methods and sampling procedures are discussed.

Jan 1, 2009

By R. H. Lien

The Bureau of Mines investigated nitrous oxide (N20) stability when used as a solvent for organic removal from metal powder surfaces. Both supercritical and subcritical conditions were studied. This investigation was prompted by the occurrence of a violent reaction when supercritical N20 was being used to deoil a metal powder grinding waste sample that contained 20 to 25 wt pct cutting oil. Tests were conducted to determine the cause of the reaction and to define stability limits. Test data showed that the waste's oil fraction reacted violently with N20 acting as an oxidizer; the metal powder acted as a promoter to reduce the ignition temperature. Although the data were scattered, this temperature appeared to reach a minimum at a certain pressure (dependent on vessel and sample size). The minimum ignition temperature for a 0.64-g sample in a 72-cm3 vessel was 360° C at 200 psig. As the sample size increased, the ignition temperature decreased. For example, when the sample size was increased to 10 g, a reaction occurred at 240° C and 600 psig. Because of the variability of ignition temperature with pressure and sample size, safe operating conditions were not established. Overall, this research showed that extreme caution should be exercised when using N20 in an organic or organic-metal system.

Jan 1, 2011

By Keith L. Harris

Real gross national product3 (GNP) grew at a seasonally adjusted annual rate of 4.2% in the fourth quarter compared with a revised 4.3% rate in the third quarter, according to the most recent estimates released by the U.S. Department of Commerce (table 1). Expanding inventories, Government purchases of goods and services, residential fixed investment, and a narrowing of the trade deficit fueled the growth. Significantly reduced consumer demand led to the heavy inventory growth. Almost half of the buildup in inventories consisted of automobiles because consumers reduced purchases when Detroit ceased most incentive programs in late summer. Reduced consumer demand also affected imports, however, and the narrowing of the trade deficit resumed after widening in the third quarter. Nonresi- [ ] dential fixed investment also declined after a strong gain in the third quarter. On a year-to-year basis, the economy grew at an inflation-adjusted rate of 2.9%, the same as that of 1986. However, on a fourth-quarter-to-fourth-quarter basis, the real growth reached 3.8%, the highest growth since 19M, and exceeded the Reagan Administration's estimate of 3.4%. Rising merchandise exports accounted for about one-third of the growth in GNP for all of 1987 and are expected to continue to grow as domestic manufactures benefit from the lower value of the dollar vis-a-vis other major trading country currencies. Consumer demand became a less important factor of economic growth, but employment continued to grow (table 2), and civilian unemployment declined by 0.9 percentage points (December to December) as the industrial sector geared up to increase exports. Inflation, as measured by the fixed-weighted GNP price index, remained low at 3.4%.

Jan 1, 1988

By J. B. Gayle

Both immediate and long-range economic factors are associated with blending anthrafines to produce metallurgical cokes, and they warrant careful consideration of the technology of carbonization of blends containing significant proportions of inert substances in general and anthrafines in particular. This situation has resulted in numerous publications dealing with various phases of the overall problem, particular emphasis being placed on the effects of inert substances on the yields and quality of cokes produced. Because relatively little attention has been given to the expansion behavior of coal blends containing inert substances, an investigation of this problem was undertaken using the Bureau of Mines sole-heated oven. Since experiments in the sole-heated oven do not measure wall pressures directly, a new method of interpretation of sole-heated oven data, which permits estimates of wall pressures, has been proposed.

Jan 1, 1955

By David C. Byrne

PURPOSE: Evaluate practical technological advances in level-dependent hearing protectors and inexpensive personal acoustic monitors. RESEARCH SUMMARY: The results of previous NIOSH research show that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals and that miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and gender. Using hearing thresholds at 4,000 Hz as an indicator, coal miners experience hearing loss 2.5 to 3 times greater than would be expected for persons not exposed to occupational noise. At age 50, 90% of coal miners and 49% of metal/nonmetal miners were found to have a hearing impairment. In comparison, only 9% of a nonoccupationally exposed control group had a hearing impairment at age 50. There are numerous barriers to the prevention of hearing loss among miners. In an effort to overcome some of these obstacles, this work was initiated to evaluate practical technological advances in level-dependent hearing protectors and inexpensive personal acoustic monitors. Experiments will involve analysis of this new technology under both laboratory and field conditions. Laboratory components will consist of controlled studies using an anthropometrically correct test fixture as well as human subjects to evaluate the adequacy/effectiveness of various hearing protective devices. Electroacoustical performance testing of new noise monitors will also be conducted in a laboratory setting. Subsequent field studies will determine the actual usefulness and practicality of the personal protective/monitoring equipment as used in different mining situations. It is anticipated that increased on-the-spot awareness of hazardous noise levels and the availability of better-suited hearing protectors will provide a degree of protection beyond what is currently attained in different mining environments. Therefore, the intent of this project is to identify and adapt new acoustical technologies and products that have a direct application to individual mine workers. With increased knowledge of these technological advances, a greater demand for similar devices will likely occur, which, in turn, will lead to a better understanding and awareness of hearing loss prevention methods throughout the mining community. The ultimate goal is for widespread integration of useful hearing loss prevention products and devices into the daily routines of miners

Jan 2, 2000

By A. C. Fieldner, S. H. Katz

"Introduction.Recent experiments (Fieldner, A.C., Katz, S.H., Kinney, S.P., and Longfellow, E.S., Poisonous gas from carbon tetrachloride fire extinguishers, Jour. Franklin Institute, October, 1920, pp. 543-565), by the Bureau of Mines have shown that carbon tetrachloride extinguisher liquids when applied to fires produce small quantities of irritating and poisonous gases which may be dangerous in very closely confined spaces where conditions are such that the user can not escape without breathing the fumes. The results of the experiments have been confirmed in an independent investigation by the Underwriters Laboratories (Nuckalls, A.H., Corrosive action and products formed when carbon tetrachloride extinguisher liquids are applied to fires, Nat. Fire Protection Assoc. Quarterly, vol. 14, January, 1921, pp. 221-236) who conducted similar experiments for the purpose of determining the corrosive action of these fumes on metals. Both investigations showed that carbon tetrachloride vapor, hydrochloric acid gas, and phosgene were produced in addition to the ordinary products of combustion, such as smoke, carbon monoxide and carbon dioxide. The Bureau of Mines' tests were made by applying a one-quart extinguisher to a wood fire of excelsior in a gas-tight room of 1000 cubic foot capacity. The glass and metal construction of this chamber limited the experimental fire to very small dimensions. It was, therefore, deemed desirable to make a test on a larger scale in the entry of the Bureau's experimental mine in order to similate more nearly the practical use of carbon tetrachloride and other types of extinguishers in mines.Description of extinguishers.Two series of tests were made under identical conditions on different days. Commercial carbon tetrachloride extinguishers were used in the first series of tests and ""foamite firefoam"" extinguishers in the second series of tests."

Jun 1, 1921

By K. A. Johnson

Marshall and Bird have published the results of a cooperative investigation by the Bureau of Mines in which they developed a procedure for measuring the agglutinating value of coal.4 As stated in their paper, the procedure outlined was suggested by the early worn of Richters5 and Campredon,6 whose procedures were hurriedly modified to meet the need of an investigation then in progress. Since the publicatien of that paper, further work has been done in an attempt to show how the variables involved affect the concordance of the results, in order that such results may be obtained in different laboratories. Briefly, Marshall and Bird's method for determining the agglutinating value of coal consists in carbonizing an intimate mixture of 10 parts by weight of sand and 1 part by weight of coal in a porcelain crucible at a uniform temperature of 950° C. in a, vertical, cylindrical, electrically-heated furnace. After carbonization, the resultant buttons are crushed in a testing machine and the breaking strengths recorded in grams. The agglutinating value reported is the average breaking strength of 10 buttons. The coal for the test is prepared by crushing to pass a 100-mesh screen. The sand used as a diluent is sized between 40 and 50 mesh sieves with openings of 0.381 icon and 0.279 millimeters, respectively.

Jan 1, 1930

By S. H. Katz

In the Bureau of Mines investigations of respiratory apparatus, a laboratory study of dust respirators has been conducted, and the results will be published in detail as a technical paper. Many industrial dust respirators, and many fabrics and filtering materials were tested. The principal results of these tests, and the conclusions drawn from them, are presented below. Reference to the patent literature discloses numerous types of dust respirators, mostly based on the filter principle. The present study included only representative filter-type respirators, purchased on the market.

Jan 1, 1926