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By C. E. Julihn

In the fall of 1933 a new discovery of gold was made in the old Mojave mining district of California about 70 miles north of Los Angeles. It led to mining operations that have surpassed in their results all reasonable expectations and are of exceptional promise for the future. In less than 3 years, exploration has opened up a number of veins, from some of which a substantial amount of high-grade ore has been shipped, while a large tonnage of milling ore has been disclosed. Two mills, operating on ore averaging better than $12 a ton, will probably produce more than a million dollars worth of gold in 1936, and a considerable increase of their output in the following year is anticipated. While continuance of these operations for a number of years is already assured by ample reserves of ore, future discoveries of still other veins are reasonably possible, as occurrence of gold throughout the volcanic rocks of the district is widespread and the veins now being mined showed little to attract attention at the surface.

Jan 1, 1937

By Ludwig Schmidt

Investigations conducted by the Bureau of Dines pertaining to the reduction of evaporation losses of petroleum have shown that such losses may be reduced 70 to 80 per cent by the use of vapor-tight tanks equipped with vacuum and pressure relief valves, and vapor-tight thief hitches. Additional studies have shown that it is often economical to supplement this type of construction with other measures that will reduce evaporation losses still further. Water-cooling systems, insulation, and light colored paints are the measures most often used in connection with vapor-tight tanks. Painting with light colored paints probably is employed in the greater number of cases. On account of the cost of insulation, or of installing water cooling systems, the use of these methods are restricted to tanks containing gasoline or crude petroleum with a very large content of low-boiling fractions. The effect of cooling systems has been discussed in a previous report.2 In choosing paints for tanks many factors must be considered. Probably the three most important are cost, protective value, and color. Many companies have adopted a standard color for all of their tanks in this way they reduce the initial cost of paint by buying in large quantities. The tank farms of such companies usually have a neat appearance, resulting from the uniform painting of all tanks. This procedure also has advertising value. Unfortunately, most of the paints used to protect steel are of the darker colors, usually red or black. These colors accelerate the rate of evaporation. Several companies have solved this difficulty by using a dark colored metal-protective paint as a primer coat, and a paint of any desired color for the final coat. Special metal-protective primers to be used under light-colored cover coats have been placed on the market by several paint manufacturing companies.

Jan 1, 1925

By T. F. Tomb

This paper describes field and laboratory investigations conducted on a dust-collection system recently designed for integral use with a continuous mining machine. The results of the field study showed that the average respirable dust concentration measured at the machine operator's position was reduced by about 60 percent (from 8.7 to 3.5 milligrams per cubic meter), and total and respirable dust concentrations in the return air were reduced by approximately 70 percent. The data indicated that approximately 20 percent of the dust generated at the face was not passed through the scrubber. The lab-oratory results showed that the overall efficiency (by particle count) was approximately 80 percent for total dust concentrations (minus 20 micrometers in size) typical of those encountered underground. Calculations based on total dust concentrations measured during the underground study indicated that the respirable mass concentrations of the effluent from the scrubber would still exceed acceptable levels even if scrubbing of all the air at the face were possible.

Jan 1, 1973

By M. J. Brevoort

Research work in the Bureau of Mines cryogenic laboratory requires the use of high-sensitivity galvanometers of the d'Arsonval type in a building that is subject to unusually severe vibrations. A modified form of the galvanometer suspension described by Julius3 has damped the vibrations so successfully that a short note concerning it is thought to be desirable, The laboratory is on the site of the Amarillo helium plant near a building that houses gas engines of from 180 to 250 hp., driving compressors and electric generators. The distances from the galvanometers to the individual engines range from about 80 to 180 feet. The subsoil, consisting of black clay loam, transmits the impulses without much damping. The usual methods of protecting galvanometers from vibration were tried and proved fruitless. A Julius suspension purchased on the market was carefully installed in the hope that it would overcome the difficulty, but the conditions were too severe even for this elaborate arrangement. Several mudifications of the original Julius suspension, which were then introduced, resulted in almost complete elimination of all vibrational effects.

Jan 1, 1931

By M. Howard Berliner

The Harding pegmatite dike is well known for the production of spodumene and lepidolite in the period 1920 to 1930. It attained greater prominence during the last war by being the largest producer of domestic tantalum ore from the rare mineral microlite. The deposit is believed to be the only proved reserve of tantalum ore in the United States today. In 1943 the main portion of a large tantalum-bearing zone in the Harding dike was developed by the Bureau of Mines with the assistance of the Federal Geological Survey. Analysis of this zone from 39 diamond drill holes and quarry exposures showed a large deposit containing 2 pounds of microlite per ton and 21 percent spodumene, In September 1948, the Bureau of Mines resumed development of the deposit with a view to extending the tantalum-bearing zone farther to the southwest or delimiting the ore body. Seven diamond-drill holes failed to penetrate the ore zone in its southwestward projection, Much of the following general information is summarized from the report on the first exploratory work of the Bureau of Mines by John H. Soule.2/

Jan 1, 1949

Prevention of coal-mine explosions depends largely upon thorough knowledge of the causes that initiate explosions. A review of coal-mine explosions in one geographical area when supplemented by nationwide data of similar nature, should serve as a guide for the adoption of measures for explosion prevention. Explosions in bituminous-coal mines of the United States during the 10 years ended December 31, 1932, ranked third in the causes of fatal accidents and constituted 16.1 percent of all fatal accidents in bituminous mines. Kentucky now ranks fourth in coal output in the coal-producing States of this country; a study of the coal-mine explosions in this state will be of definite interest locally among coal-mining people, as well as to those in the coal-mining industry who are concerned in preventing coal-mine explosions. This circular reviews gas and dust explosions in Kentucky coal mines to show their hazards, to point out the influence of certain factors in causing explosions, and to indicate the effectiveness of preventive measures.

Jan 1, 1934

By P. M. Sullivan

This report describes a new application of electroamalgam metallurgy in recovering all the zinc as refined metal from galvanizers' sal skimmings. Pure zinc was recovered by electrolysis of skimmings leach liquors in amalgam cells. The following information was gained as a result of literature studies and subsequent laboratory investigations. 1. Reports in the literature indicate that pure zinc can be recovered from chloride solutions with the aid of amalgam cells. From Europe it was reported that amalgam cells could be used to recover pure zinc and chlorine from leach liquor obtained from pyrite cinders following a chloridizing roast.

Jan 1, 1956

By W. T. Millar

Magnetite mines in the Sterling tract, Orange County, N. Y., were operated almost continuously from pre-Revolutionary days until 1923. The Red-Back mine, one of several in this tract, was discovered in 1780; operated briefly in 1880; and abandoned, presumably because the iron ore contained considerable sulfur. The mine is in rough, mountainous country, with altitudes ranging from 500 to 1,100 feet. The magnetite deposit occurs in complex metamorphosed pre-Cambrian formation and is thought to be a replacement of limestone by magnetite. A dip-needle survey, completed in 1916, traced magnetic anomalies for a mile along the outcrop. A preliminary examination of the Red-Back mine was made by W. T. Millar, Bureau of Mines engineer, in December 1942. The Bureau of Mines bored seven diamond-drill holes aggregating 2,727.6 feet during the winter of 1943-44. A zone of magnetite mineralization was intersected in each of the holes.

Jan 1, 1949

By Daryl R. Tweeton

The Bureau of Mines compared the effects of surface-active chemicals with those of pure water on core-drilling rock and quartz and on fracturing quartz. The objectives were to determine if these chemicals assist drilling and fracturing rock and if zeta potential control was worth pursuing as an aid to full-scale drilling. All tests were performed in the laboratory. No significant increases in drilling rates were observed for 1 to 10,000 ppm Al (as AlC13) in flushing water when drilling microcline or serpentine, nor for 1 to 10,000 ppm Mg (as MgC12) when drilling microcline or marble. Concentrations near those giving a zero zeta potential were used with microcline and marble. A 50-pct rate increase was observed for drilling quartz in 0.7 ppm oleylammonium acetate, which gave a zero zeta potential. No other concentrations were used. No effect on the tensile strength of quartz thread in 0.05 ppm Al (as AlC13), which gave a zero zeta potential, was observed. Heptanol, reported to give a zero zeta potential on quartz, did not reduce the bending strength of small quartz bars below that in water. These generally negative findings raise doubt about the usefulness of zeta potential control in full-scale drilling. The results, combined with previous studies, suggest that controlling physical properties of drilling fluids, such as viscosity, is more useful than altering chemical properties.

Jan 1, 1976

By G. W. Jones

[The determination of the ignition tcqornturc ol" dict:iyl cther and othylene in air ma o;GrT;en rir..ic'r. is dcscribed In thin report J'IF.R mqdo primarily for comparison rritll sinilnr d~ton:in:~tions of ot; cr co~~o~imS-r, in the same apparatus and using the r?.:?.r.~o 1a.borntorg t cchzllique The investigation was conducted at the 2ittsbur;;h Experiment Station of the United States wcau 02 hii2cs vritEl tl~c cooperation of licrclc & Co., Inc.]

Jan 1, 1935

By Robert S. Sanford

In April 1948, the Bureau of Mines was requested to evaluate the graphite deposit' known as the Benjamin Franklin and Just mines in Chester County, Pa. After preliminary investigation, it was recommended that the Bureau core-drill, trench, and sample the deposit and make beneficiation tests on the ore. During the first and second World Wars, flake graphite was in short supply, and a number of deposits in the United States were exploited. In 1942, the Defense Plant Corporation, through its lessee, the Benjamin Franklin Graphite Co., purchased 70.263 acres of graphite-bearing land and built a complete mining and milling plant with a capacity of 300 tons of crude ore per 24-hour day at a cost of $426,250 (Plancor No. 1254).

Jan 1, 1949

By R. W. Van Dolah

An important function of stemming used to confine explosives in shot holes in underground coal mines is to minimize the chance of ignition of firedamp or coal dust by the detonation products. Until 1952, the Bureau of Mines approved only the use of fireclay or similar incombustible material for stemming permissible explosives. At least 2 feet of stemming were required except in holes less than 4 feet deep; in such short holes the stemming was required to be half the depth of the hole. Over the years, several special stemming devices have been proposed in the United States as substitutes for fireclay. Many economic and safety advantages were claimed for these devices, but only one approved device has been marketed in this country. Bureau requirements for stemming explosives in coal mines were modified at that time to permit the approved stemming device to be used as a substitute for the required fireclay.

Jan 1, 1961

By A. A. Cochran

Methods of preparing small heats of steel containing radioisotopes were developed, and the techniques of stripping film autoradiography were used to detect and study the carbide and sulfide phases in titanium-bearing steels. Metallography had revealed areas of titanium sulfide and ferrite or pearlite adjacent to areas of titanium carbide and ferrite, and unidentified, irregular phases at the boundaries between these two areas. Sulfur 35 was used to deter-mine the extent of the titanium sulfide inclusions, and carbon 14 was used to delineate the titanium carbide phase. Individual radioactive areas were located with a resolution of approximately 10 microns. A general background exposure that was not correlated with microscopically visible phases was observed in the carbon 14 autoradiographs. The evidence from both sulfur 35 autoradiographs and carbon 14 autoradiographs indicated that the unidentified inclusions were sulfides rather than carbides. INTRODUCTION The use of radioisotopes to facilitate the work at the Rolla Metallurgy Research Center was expanded in fiscal year 1959 when the Bureau of Mines authorized the installation of an intermediate-level radioactivity laboratory. Before this time, sealed cobalt 60 sources had been employed for radiography, but no tracer work was done. The primary objective of the first experiments conducted in the new laboratory was to supplement physical metallurgy investigations of selected problems in steel research.

Jan 1, 1962

By John Campbell, Miller. W. E., G. W. Jones

"INTRODUCTION Because of its interest in accident prevention, the Federal Bureau of Mines has cooperated with city officials and utilities in investigating the causes of explosions in sewers, manholes, and other underground spaces and has aided in the development of means to prevent such explosions. For several years this Bureau has cooperated with the Boston Edison Co. and the Boston Consolidated Gas Co. of Boston, Mass.,for the purpose of detecting and eliminating combustible and physiologically harmful gases in manholes in Boston and vicinity.These investigations 5/ have shown that combustible gases from the usual sources — leakage from gas—distributing systems and underground tanks and gasoline wastes — can be located and the dangerous conditions remedied by a well—planned, adequately supervised, systematic, and continuous manhole survey. However, other types of gas contamination, termed ""soil"" gases, are present in manholes at times and are more difficult to eliminate because they have no fixed origin and because seasonal and barometric chances affect their production and passage into the manhole. Soil gases usually are abnormally high in carbon dioxide and low in oxygen and contain varying amounts of methane. They are especially dangerous to men entering manholes because they lack sufficient oxygen to support life."

Feb 1, 1940

By Bertrand L. Johnson

Fertilizers are indispensable to national preparedness and defense. Production of adequate supplies of nourishing food for sustaining life in the United States is absolutely dependent in many parts of the country on the use of artificial fertilizers of various types. Only by using fertilizers can we maintain our present volume of production without great additional expense. Otherwise we would have to increase crop areas constantly to compensate for declining yields, we would have to lower the quality of food marketed, and standards of farm living and rural civilization would decline. About 60 million of the 360 million acres of crops grown annually in the United States Vow require fertilizing each year, and between 7 and 9 million tons of commercial fertilizers are consumed annually for this purpose.

Jan 1, 1941

By M. J. Brevoort

Research work in the Bureau of Mines cryogenic laboratory requires the use of high-sensitivity galvanometers of the d'Arsonval type in a building that is subject to unusually severe vibrations. A modified form of the galvanometer suspension described by Julius' has damped the vibrations so successfully that a short note concerning it is thought to be desirable. The laboratory is on the site of the Amarillo helium plant near a building that houses gas engines of from 180 to 250 hp driving compressors and electric generators. The distances from the galvanometers to the individual engines range from about 80 to 180 feet. The subsoil, consisting of black clay loam, transmits the impulses without much damping. The usual methods of protecting galvanometers from vibration were tried and proved fruitless. A Julius suspension purchased on the market was carefully installed in the hope that it would overcome the difficulty, but the conditions were too severe even for this elaborate arrangement. Several modifications of the original Julius suspension, which were then introduced, resulted in almost complete elimination of all vibrational effects. These modifications were suggested by careful study of the original idea embraced in the Julius construction. They were designed to give further constraint to motion in any direction other than that parallel to a line from the point of support through the center of gravity of the suspension, This was accomplished by making the suspended frame more rigid and by improving the means of adjusting each of the supporting wires to the same degree, thereby transmitting any impulse symmetrically through the three wires. The result was a suspension that is more effective, particularly for severe vibration, than the form described by Julius; also, it is believed to have advantages in stability, simplicity, and ease of adjustment over the few suspensions for this type of service that the author has found described in the literature.

Jan 1, 1931

By L. A. Schutz

Personnel of the Bureau of Mines have conducted investigations in the principal asbestos mines and mills in the United States, to determine the concentration of airborne asbestos fibers in the workplace, and to establish the exposure of workers to such fibers. 'The surveys were conducted using the sampling and evaluation method recommended by the National Institute for Occupational Safety and Health. The method consists of collecting the air-borne sample on filters and, after appropriate sample preparation, counting the fibers utilizing phase contrast microscopy. The results of the investigation show that fiber concentrations are low in the asbestos mines but high in the asbestos mills, ranging well above 5 fibers/ml of air based on a count of fibers greater than 5 urn in length.

Jan 1, 1973

By D. B. Dow

In collecting and dissctinating inforr:.at'ion on ir.:,provec.. practices us0i in the pr eduction cf petroleur:1 and in the r;:;.:.1.nuf __ cture of gasoline, the Bureau of Mines ha.s aidei in creatin5 an interest i-n efficient 11:ethods in all phasas of tr.e oil ani gi:i.s iniustry. In the refinin£ ir...mstry ther.:: is a growing tend.ency for incre.:l.sea. effi. ,:;iency, ana inforr;.Eition rela:tin!s to ic:;p·roved practices should be of value not only to the larger and. core efficient plants, but particularly to srr.a.11 refineries unable to carry out a lar6e experLnental pro!§.rarn. The refi?eries of the United States required 4.3,915,029 barrels cf crude oil J.uring the year 1920*, inclu.::.in1:, 611136,210 barrels of Mexican cru::...e. This yielded. 4,8821546,599 gallons of E>asoline, a.n avara.t;,e ciaily pro;.iuct1on of 13,340,291 e,allons·, Besides the easoline obtainel fro;., cruie· oil by-fr:;.cticna.1 distillation and. from heavy oils by crackini:,, this a,-r;ount incluC1.es 3,152,924 bar­rels of natural-ga.$· gasoline blended. With asoline fro,., th otha two sourcs.

Apr 1, 1922

By ALICE V. Petar

Through the courtesy of the State Department, the Bureau of Mines has received a compreensive report on the jede industry of Burma, pre- pared by American Consul Winfield H. Scott, Rangoon, Burza. This mater- ial is the main basis for the present circular, although free use also has been made of reports on the jede industry in China and Germany by consular officers in those countries, to whom footnote credit is given. The word "jade" is said to be derived from the Spanish "piedra de ijada" (hijada) meaning, literally, "stone of the side," as jade was supposed to cure pains in the side; nephrite (a jade mineral) was named from the Greek word meaning kidney, because it was formerly warn as a re- medy for kidney diseases. To the Burmeso, jade is known as "Kyauksein," or green stone, and to the Chinese, all varieties of the material are referred to as "Yu" or "Yu-chi", According to Confucius, jade was symbolical of. justice, harmony, intelligence, and humanity, and the Chinese of today believe that by using ornaments made of this stone, the wearer is. protected from the "evil eye" as well as from diser.se. Ornaments of carved jade were known to the ancient civilizations of Mexico and Peru and to the peoples of other sections. of Central and South America, Jade ornaments also have been found in the lake dwellings of Switzerland and in Crete; thile in China, as far back as the Chou dynasty (B. C. 1122 B. C. 255) it was used in the production of various classes of precious vessels and as insignia of rank.

Jan 1, 1936

By Robert K. Koch, Henry E. Blake

Laboratory tests were made to determine if aluminum fluoride of commercial grade could be synthesized by reacting alumina hydrate with dilute ( 25 to 75 grams per liter of fluorine ) aqueous fluoride solutions . • Products containing up to 90 percent aluminum fluoride ( A1F ) were synthesized by reaction of alumina trihydrate ( A120 3H2O) with either dilute hydrofluoric acid ( HF ) or ammonium fluoride ( NHF) solutions , the ammonium fluoride solution resulting from ammonia ( NH ) desilication of a hydrofluoricfluosilicic acid ( HF - H₂ SiF ) solution . Fluorine recoveries of over 80 percent were obtained with either type of solution . The hydrated precipitates of AlF, and ( NH4 ) , A1F ( ammonium aluminum fluoride ) obtained by reacting hydrated alumina with these solutions were subsequently converted to anhydrous AlF, by controlled heating .

Jan 1, 1964