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By George A. Page, Hewitt Wilson, Vance S. Cartwright

"Purpose of InvestigationThe process of removing solid material from liquid suspensions has been studied at the Northwest Experiment Station, United States Bureau of Mines, in cooperation with the University of Washington, as part of a general program to investigate the dewatering of Pacific Northwest plastic kaolins, which is difficult by ordinary filter-pressing methods. The present paper is a progress report of the work began by Vance S. Cartwright in 1928 and continued in 1931 and 1932. Spray evaporation is believed to be valuable for the following classes or grades of clay and clay mixtures:(1) Highly colloidal, plastic-type clays, which release their mechanically attached water with difficulty; (2) clays prepared for shipment in pulverized or powdered condition; and (3) synthetic, ceramic, porcelain, and tile mixtures prepared as aqueons suspension, dried and pulverized before molding. Dilute suspensions can be dewatered by spray evaporation to produce concen-trated casting slip or plastic clay with a lower water content.The most common dewatering method used in preparing powdered kaolin for the market comprises the following steps: Reduction of the water content by filter-pressing from approximately 75 percent in the thick ""slip"" condition to about 30 percent in the condition; further reduction of the water in the filter-press cakes by heat to about 5 percent; and pulverization of the dried cakes in hammer or dust. These three steps can be simplified to a single process by spray evaporation."

Jan 1, 1935

This manual provides instructions for installing, operating, and maintaining a protective canopy on the Galis Mfg. Co. roof drill. The instructions are based upon two actual installations: one made in a mine on roof drill, model 300, and one in the factory. The parts list and engineering drawings for the protective canopy are included at the end of the manual. And a discussion of some alternative design concepts is also included. The manual can also be used for retrofitting other roof drills with similar protective canopies. Skilled mechanics can determine if the instructions herein would be applicable to the other roof drills and can determine any necessary modifications if they are not.

Jan 1, 1973

By E. W. Felegy

Since 1920, the Bureau of Mines and, other agencies have conducted numerous investigations of methods of communication for use in mines in times of disaster or emergency. The results of these investigations have been reported in various publications (3, 4; 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16). In November 1944, the Bureau of Mines resumed the study of emergency underground communications. Until March 1946, the program was directed toward reexamining methods of underground communication that indicated possibilities of success. Since April 1946, the principal interest of this investigation has been in methods of application of radio to communication in mines, low-frequency radio seeming to offer the most promise as a successful method of emergency mine communication. Results achieved in reexamining other methods and in the investigation or the application of low-frequency radio between November 1944 and September 1946 were reported previously in a publication entitled "Some Studies on Emergency Mine Communications".

Jan 1, 1948

By Martin Hertzberg

The concept of limit burning velocities, formulated in an earlier Bureau of Mines report (RI 8127), is applied to the problem of flame propagation through tubes of finite size. The limit burning velocity for conductive-convective wall-loss quenching (process b) is (Su)b = [aPe,] where the proper choice of critical Peclet constant, Pe, is determined mainly by the ratio of contact-perimeter loss area to flame-zone cross sectional area. This ratio of loss area to propagation area relates to the shape of the flame front and its control by buoyancy and by boundary conditions. The comparison of (Su)b with previously defined limit velocities for systems mixed by natural convection allows one to assess the influence of tube dimensions and boundary constraints on the "true" or earthly limits for the three directions of propagation. The flame quenching caused by inert powders is shown to be similarly described in terms of a limit burning velocity, (Su)?b. The tube's surface-to-volume ratio (~1/ro) is simply replaced by the powder's surface area per unit volume of the flammable mixture. Thermal loss quenching by these "internal walls" occurs at a critical Peclet constant somewhat higher than that observed for tubes, and the problem is complicated by the finite heat capacities of the powders and particle lag effects in the flame front.

Jan 1, 1980

By Walter J. Frank

The purpose of the work covered by this contract is to develop a means of designing splice connectors which will significantly improve mine trailing cable splice performance. A brief discussion on splice problems is presented as an introductory means and substantiates the need for the development and test programs outlined in this report. Because of the empirical nature of this effort, time has been devoted to explaining the derivations of the test procedures used. Special attention is given to the splice flexing machine which served as the backbone of the test program. In order to familiarize persons with connector terminology, a section is devoted to a glossary of pertinent terms. Various types of cable joints are also defined. The major effort is a connector design parameter study. Utilizing the optimum parameters developed along with the suggested design procedure outlined in Appendix I should result in significantly improved splice performance and thus meet the objectives of this contract. A field test program was instituted for the purpose of insuring adaptability of connector design and associated installation tooling along with a field performance study. During the course of work, other significant factors affecting splice performance were uncovered. Although not covered by the scope of this contract, a brief discussion is presented for the purpose of stimulating interest in what is considered other fruitful areas for improved splice performance.

Jan 1, 1976

By William W. Adams

The quarrying and related industries of the United States improved their safety record in 1938 by reducing their accident-frequency rate to a lower acid more favorable position than it has occupied at any time except 1935 since comparable accident statistics became available in 1916. The rates for 1935 and 1938 were identical. The number of men employed in 1938, although smaller than in 1936 and 1937, was larger than in any other year since 1930. Volume of employment, as measured by the number of man-hours worked in the industry as a; whole, likewise was larger than in any year since 1930 except 1936 and 1937. Reports from operating companies to the Bureau of Mines, United States Department of the Interior, showed that 77,497 men were employed in 1938, a decrease of 6,597 compared with 1937. This figure represents the average number of employees for the period during which the quarries and plants were active during the year, which in 1938 averaged 223 workdays per employee compared with 241 in 1937. A total of 17.3 million man-days or 133.8 million man-hours of work was shown for the industry as a whole, which indicated a weighted average of 7.75 hours per man-shift. Reports for 1937 showed a total of 158.3 million man-hours for the entire industry and an average workday of 7.81 hours. Accidents resulted in the death of 82 employees, 5 more than in 1937, and in 5,027 nonfatal injuries involving disability for more than the remainder of the day on which the injuries were received. The number of nonfatal injuries was 1,321 less than in 1937. As the number of deaths and injuries was reduced more, proportionately, than man-hours of employment, the accident-frequency rate per million man-hours of work declined, the rate for 1938 being 38.19 compared with 40.59 for 1937. In other words, accident occurrence to the average employee was 6 percent more favorable in 1938 than in 1937 on the basis of actual number of accidents and actual number of man-hours worked during the 2 years.

Jan 1, 1940

By Craig C. Hustwit

A pilot-scale treatment study was conducted on a copper-zinc bearing metal mine drainage using a pipeline treatment system called the In-Line System (ILS). The objective of this U.S. Bureau of Mines study was to determine whether the ILS could be extended from the treatment of coal mine drainages to the treatment of metal mine drainages. Hydrated lime (Ca(OH)2), quick lime (CaO), and caustic soda (NaOH) were used to neutralize the drainage. A novel reagent slurry of Ca(OH)2 and type C fly ash was also evaluated. Except for Ca(OH)2-fly ash slurry, treatment performance was evaluated for all reagents at pH values of 7,8,9, and 10. The Ca(OH)2-fly ash slurry was evaluated at a pH of 10. All reagents tested neutralized the metal mine drainage and substantially reduced the dissolved metal concentrations. It was concluded that the ILS could be useful in the treatment of metal mine drainages.

Jan 1, 2010

By Anthony W. Sparks

The Bureau of Mines conducted tests designed to compare its breathing metabolic simulator (BMS) with other methods that are currently used to evaluate the performance of respiratory protective equipment. The BMS is a commercially developed device that uses a piston cylinder to simulate breath movement. Using a propane furnace that consumes oxygen and forms CO2, the BMS also simulates the respiratory metabolism of humans. The breathing and metabolic subsystems of the BMS are described in detail in this report. Results are compared from tests that used the BMS to evaluate respiratory equipment and from tests that used human subjects for the same purpose. The BMS was also tested against a pulsatile breathing machine (PBM) previously designed by the Bureau. Both machines were used to test respiratory equipment, and the test results are compared in this report. To illustrate typical applications of the BMS, the report briefly describes how the BMS was used to test two different types of closed-circuit respiratory apparatus, and the test results are presented. This research showed that BMS test results compared more closely to the results of tests that used human subjects than did results obtained using the PBM.

Jan 1, 1980

By Foster Fraas

The objective of this research was separation of one highly conductive mineral from a second conductive mineral , a procedure which is impractical in commercial electrostatic separators using metal rolls . Such separators permit separation of nonconductive from conductive minerals . A new technique involved use of carrier electrode rolls specially prepared by anodizing and / or oxidizing at high temperatures to form suitable oxide surfaces . Specific oxides included aluminum , copper , and nickel . The significant result provided by the new surfaces was the extension of the separation range to higher conductivities , an extension in relative mineral conductivity from 10-14 mhos . The results are in accordance with the blocking- layer theory .

Jan 1, 1964

By S. M. Molloy

The postwar demand for insulating material such as mineral wool, in-creased in proportion to the rapid construction of new buildings, placing an enormous burden on the existing mineral-wool industry both in known sources of raw materials and in available plant facilities. In view of the increased demand on the industry, the Bureau of Mines in its Mississippi Valley Experiment Station" Rolla, Mo., undertook an investigation to aid the industry by establishing resources of raw materials through actual laboratory wool-blowing tests and by developing certain methods for evaluating the physical proper-ties of a mineral wool. As material was received from the public, laboratory-evaluation technique had to be developed, the results of which would reflect in the mineral-wool-industry standards. The methods of testing used by the mineral-wool industry, not only would have required a pilot-plant installation capable of producing a large tonnage of mineral wool, but each wool-blowing campaign would have been very expensive and necessitated considerable personnel and equipment. The present laboratory wool-blowing equipment can produce as high as eight wool-blowing campaigns a day. The nature, simplicity, and size of the physical testing equipment permit testing as small a sample of wool as 25 grams and give information as reasonably accurate as in a 40-pound bag of wool. The purpose of this report is to describe the laboratory method of production and the evaluation of the physical properties of small quantities of mineral wool. Considerable work has already been done, and the interest of the public and industry is measured in the number of samples being submitted for testing.

Jan 1, 1948

By G. R. Hopkins

Although many small refineries were dismantled in 1934 the total number of plants, including a few under construction, increased from 604 at the beginning of the year to a new high of 638 on January 1, 1935. The capacity also reached a new record, the total of 4,072,400 barrels of crude oil daily being about 45,000 barrels higher than the previous high of January 1, 1932. The number of refineries increased materially in 1933, following construction in east Texas and the building of many small plants in the Rocky Mountain district and elsewhere. Most of the new plants of 1933 were built to provide an outlet for crude or because the ratio between crude oil and gasoline prices appeared conducive to profits However, low gasoline prices and increased costs in 1934 dispelled the hopes for profits; many plants were shut down, and some were dismantled. The number of operating plants declined from 454 on January 1, 1934, to 435 on January 1, 1935, but the number of inactive plants increased from 137 to a new high of 196 during the same period. As indicated above, new construction was at a minimum in 1934, and on January 1, 1935, only 7 plants were being built.

Jan 1, 1935

By D. E. Redmon

Linear programing provides a mathematical technique by which activities can be planned in such a way that an optimal result is obtained. Routine applications of linear programing require only a knowledge of algebra. However, a complete understanding of the fundamentals of linear programing requires a knowledge of advanced mathematics. The purpose of this publication is clarification of terminology and illustration of applications in comparatively simple mining problems. Two mining situations are considered: Mine stopes from which ore is to be produced at a minimum production cost; also, uranium mines from which ore is transported to one mill, a maximum monetary value is desired. The details of data arrangement for solution by linear programing are described and the solutions are presented. Results of these solutions indicate successful applications of linear programing to mine production scheduling.

Jan 1, 1964

By Robert R. Stein

Using an automated drill test fooure, the U.S. Bureau of Mines measured the sound power levels produced by a small, pneumatic, rotary roof drill. A series of tests was conducted to determine (1) the relative effectiveness of several drill muffling schemes and (2) the relationship between drill sound power and pneumatic power supplied to the drill. The influence of rotation rate (i.e., airflow) and feed thrust on the penetration rate of the drill was also noted.

Jan 1, 1989

By L. Kaufman

A range of processing conditions and compositions have been evaluated in order to optimize the properties of TiB2-(Ni,Cu) composites for application as a non-sparking tool material for use in coal mining operations. Fifty billets containing from 70 to 9S weight percent titanium diboride were hot pressed at 3000 psi between 2400°F and 2650°F. Samples which were cut from these billets were used to measure hardness, bend strength and impact strength so that composition/processing optimization could be effected. Eight compositions selected on this basis were evaluated by incendivity tests in order to choose the best composition. The best results were obtained for an 85 w/o TiB2-12 w/o Cu-3 w/o Ni composite hot pressed at 2650°F and 3000 psi. This material appears to be the best choice for fabrication of coal cutter bits to be evaluated in field tests.

Jan 1, 1973

By B. H. Eccleston, R. F. Kendall, D. E. Hirsch, Norman G. Foster

The mass spectra of 23 alkylthiophenes are presented , including 21 that have not been previously reported . Correlations between mass spectra and the structure of the thiophene homologs are discussed . Comparisons with , and corroboration of , earlier workers ' correlations and predictions are made . Several additional correlations are reported to enable the spectroscopist to identify the substituents on alkyl - substituted thiophenes , and the relationship of the mono - substituted and 2,5 - disubstituted alkylthiophenes is discussed in detail .

Jan 1, 1964

By F. H. Nehl

Ion elutriation was used to extract silver cyanide complexes and free cyanide from aqueous streams containing up to 10 ppm silver and 5 ppm free cyanide. Screening tests selected nine of 350 different surfactants for further, larger scale experiments. The screening procedure used 0.1 g of each of the surfactants in 300 mL of synthetic wastewater. Air was sparged into the test cell at 50 cc/min. The foam was refluxed during the tests and was not sampled. Samples of the solution were taken at specified intervals and analyzed by wet chemical methods for free cyanide and by atomic absorption for silver content. The most effective surfactants lowered the silver and free cyanide concentrations to less than 0.5 ppm in 1 h or less. These surfactants were quaternary amine salts with one long chain (C12-C18) organic group and three methyl groups. Experiments using 3 L batches of wastewater or an ion elutriation cell continuously fed with solution draining from an inactive heap leach operation confirmed the results from the screening tests.

Jan 1, 2010

By J. E. Schiller

The Bureau of Mines is investigating methods to treat waste water that contains cyanide. This report describes a new method that removes heavy metals and all forms of cyanide. In the first step, hydrogen peroxide and sodium thiosulfate are added at pH 7 to 9 in a 1:2 molar ratio to convert free and weakly complexed cyanide to nontoxic thiocyanate. Then steryldimethylbenzylammonium chloride is added to precipitate ferro-cyanide, and finally, ferric sulfate is added as a sweep floc and sequestrant for heavy metals. After the suspended solids settle, the water is polished by filtering. The water initially contained 1 to 5 mg/L Fe, 1 to 5 mg/L Cu, and 10 to 30 mg/L total cyanide; the level of each of these constituents was reduced to less than 0.02 mg/L.

Jan 1, 1983

By J. N. Geyer

In coal mining it is essential to maintain the roof over working places and roadways in the safest condition possible. To this end every effort should be made to win the coal with the least injury to the immediate roof strata, as broken strata certainly present a greater hazard than a sound roof. The chief causes of injury to the roof in mining are inherent in the method of development and recovery and the blasting practices followed. The first, which may produce severe stresses in the roof, weakening it over comparatively large areas has been discussed in previous papers3 and will not be treated here. The second cause is local in effect, but with the same general method of blasting being employed throughout a mine having uniform roof conditions, similar effects on the roof may be expected. In the Bureau's investigation of accidents caused by falls of roof and coal it has been necessary to make a careful study of blasting practices and their effect on the immediate roof. The purpose of this paper is to show the effect of the observed methods of blasting on different types of roof and to point out methods that have been proved to be least harmful to the roof strata. The data used in preparing this paper have been compiled from reports made by Bureau engineers engaged in the study of falls of roof and coal, and embrace mines opened in the Pittsburgh coal in Ohio and Pennsylvania and the Pittsburgh and Sewickley coals in West Virginia.

Jan 1, 1933

By Albert L. Toenges

This paper is the third of a series4/ that describes some methods and practices of mining coal mechanically where operations are conducted on more than one shift. The mining of coal by means of mechanical devices has emphasized the need for continued study of the relationship, of these devices to existing physical conditions and to planning of the operations for increased safety and economy. The purpose of this investigation is to stud the operations of different types of mechanization used in mines under various systems of mining and physical conditions to reach conclusions as to the safest and most economical methods and practices of mining. Physical conditions very in different and in the same mining districts and determine, together with economical conditions, the systems of mining and the types of mechanical loading equipment used. The information presented in this paper

Jan 1, 1941

By Albert L. Toenges

The Deep River coal field is in Chatham, Lee, and Moore Counties, N. C. The coal-bearing part of the basin is about 35 miles long and 5 to 10 miles wide. Sanford, the county seat of Lee County, is the largest town in the area, with a population of 10,000. Four railroads provide transportation to the area, and four United States highways and improved county roads provide easy access to the field. The Carolina mine at Farmville is the only operating mine in the field. The mine was opened in 1921 by two rock slopes driven from the surface to the Cumnock bed. Mining operations continued intermittently until 1945 and then stopped. In the fall of 1947 the mine was reopened by the newly organized Raleigh Mining Corp.

Jan 1, 1952