Search Documents

By Herbert L. Lines

This paper is one of a series on mining and milling methods and costs published by the Bureau of Mines. The Ash Peak mine of the Veta Mines, Inc., Duncan, Ariz., is of particular interest in that the only metal of commercial value in the ore is silver. The silver is concentrated by flotation; the concentrate is shipped to a smelter for treatment.

Jan 1, 1940

By J. A. Woolf, E. S. Leaver, N. K. Karchmer

"In the cyanidation of silver ore, the need of oxygen is well recognized. Various methods have been introduced for supplying the oxygen. In usual practice, air is the source of oxygen and the methods of application are mechanical.This article gives the results of touts made to show the rate of dissolution of silver from each of the common silver minerals in cyanide solution, under conditions similar to those used in the practical recovery of silver from its ores. The effect of oxygen in aiding the dissolution of the silver from each mineral is also shown by a comparison of the methods of supplying the oxygen. Oxidation by preliminary roasting (500°C.) of each mineral sample gives the maximum extraction of the silver by treatment with cyanide.Each silver mineral5 used in these experiments was as pure as could be obtained from the mineral dealer. In their natural occurrence, silver minerals are not usually free from mineral impurities. They are usually closely associated with other minerals often forming, a complex mixture. The form of crystallization, the proportions, and properties of the diluent that incases or has been dispersed with the silver mineral may decidedly affect the dissolution rate of the silver from each mineral. While the following results should aid in the cyanidation of silver ores, each ore should be studied from the basis of the form and condition of the silver that is to be recovered.All the tests reported in this article were made on synthetic samples, prepared by mixing the particular silver mineral with clean sea sand. Each mineral was ground in an agate mortar to pass 100-mesh before mixing with the sand which had previously been ground in a porcelain pebble mill to 100-mesh. Such proportions of each mineral and the sand were used as to give a head assay of approximately 20 ounces of silver per ton to the synthetic sample.Agitation was carried on in stoppered bottles approximately one-third full of pulp, method apparently supplied all the atmospheric oxygen that would be taken up by the solution under usual conditions, because tests conducted in open bottles did not show increased recovery,"

Jan 1, 1931

By Henry M. Harris, John E. Kelley, Thomas D. Roberts

A penetrometer apparatus for measuring viscosity of glass at temperatures up to 1,450 ° C was developed for use in establishing the viscosity coefficients required for high- temperature forming of ceramic materials . The major advantage of the method is that it can be used with samples of almost any shape or size without the necessity of forming or measuring shapes to close dimensional tolerances . Also , it has proved accurate in the range of 106 to 109 poises , a gap between the normal limits of other methods . The device , which operates on a single penetrometer principle , was used to determine the absolute viscosity coefficient of substances in centimeter - gram- second units of poises instead of relative penetration - rate units as with other penetrometers . Penetration of the viscous sample was sensed with a linear , variable differential transformer . The output of this transformer was recorded versus time , and the penetration rate was used in calculating the viscosity coefficient . The general equation relating penetration rate and viscosity coefficient was found to be 11 = F ( ln L/a 0.72 ) 2 π UL · where is the viscosity coefficient in poises , F is the penetrator load in dynes , L is the penetration depth in centimeters, a is the penetrator radius in centimeters and U is the penetration rate in centimeters per second . The penetrometer was tested using a standard viscosity sample of sodalime - silica glass obtained from the National Bureau of Standards ( NBS ) . Values obtained at several temperatures all agreed within 10 percent with comparable data calculated from the Fulcher equation derived by NBS for this glass . Equivalent accuracy was obtained with other glasses used to evaluate the apparatus .

Jan 1, 1964

By L. H. Kalenowski

The metal lithium, its alloys, and its salts are becoming Increasingly important as industrial materials. Lithium metal, because of its great affinity for elements, such as nitrogen, hydrogen, oxygen, sulfur, phosphorus, carbon, and silicon, has become important for a wide variety of uses, ranging from purifying helium gas by removing the nitrogen to scavenging molten metals of undesirable impurities. The excellent fluxing properties of lithium salts have found increasing use in such applications as fluxes for welding aluminum and in lower melting ceramic glazes and coatings. Lithium chloride is one of the most hygroscopic salts known and is widely used as a dehumidifying agent. .About 17 lithium minerals are known. Four of these have commercial importance: Amblygonite, lepidolite, zinnwaldite, and spodumene. Spodumene is the most important source of lithium and lithium salts at present, but sizable deposits of amblygonite occur in the pegmatite area of the Black Hills of South Dakota. The size and nature of these deposits preclude the, possibility of, any assurance of an adequate supply of amblygonite for an operation processing only this mineral. Frequently spodumene and amblygonite occur associated in pegmatite minerals. Preliminary investigations indicate that a simultaneous recovery of spodumene and amblygonite can be made by froth flotation. A single process for treating spodumene and amblygonite or mixtures of thorn, would make possible more use of amblygonite as a source of lithium and obviate the separation of spodumene and amblygonite when they occur together.

Jan 1, 1952

By J. D. Davis

On May 15, 1936, Congress authorized the Bureau of Mines to conduct certain studies, experiments, and investigations of subbituminous coal and lignite .4/ Appropriations were made in July 1937, and since that date an active investigation has been underway to complete the provisions of the act. Part of the investigation has included a comprehensive survey of the known properties of the lower-rank non-coking coals, and provisions were made to obtain more data on certain varieties. In line with this plan, a typically subbituminous coal was selected for an extended series o tests in the standard Bureau of Mines-American Gas Association unit,5/ at the Central Experiment Station. This particular noncaking coal was the first one of its rank that ha& been tested in the apparatus; for this reason the results are of particular interest because the testing apparatus was originally designed for use in studying the coke- and gas-making properties of coking coals. The test as described below has been developed by the Bureau of Mines since 1927 through a cooperative agreement with the American Gas Association.6/ Ninety to 180 pounds of coal is heated in a circular retort, 13 to 18 inches in diameter, at wall. temperatures ranging from 540°C. to 1,110°C. in 100°C. steps. All products axe collected and measured; their physical and chemical properties axe then carefully determined to ascertain the gas- and coke-making properties of the coal.

Jan 1, 1939

By A. W. Fahrenwald

"About two years ago the Bureau of Mines, Department of the Interior, and the University of Idaho undertook an investigation of classification in its relation to table concentration of Idaho ores. The cooperation of the management of the Bunker Hill & Sullivan Co. in placing at our disposal their West Mill and facilities as desired, offered an unusual opportunity for studying the field of hindered classification in its practical and economic relation to table concentration.It has been shorn theoretically, and demonstrated experimentally, that ore products are more easily and economically concentrated on tables if the natural feed, consisting of various minerals and of all sizes of particles of each mineral, be classified or grouped into a series of products in which the mineral particles of greatest density are small in diameter relative to the diameter of the mineral particles of lesser density. Products in which the maximum difference in diameter of light and heavy minerals occurs are to be obtained only by true hindered settling classification. To our knowledge there has never been a really good hindered settling classifier used in practice and the present tendency seems to be to by-pass any attempt at such classification.After a careful study of the nature of hindered classification and of the requirements for hindered settling in practice, a classifier has been developed that takes fullest practical advantage of the widely known, but generally only meagerly understood, condition of hindered settling so well analyzed a number of years ago by Dr. Richards.The present paper presents briefly some of the more important practical results accruing through the investigation."

Jun 1, 1924

By D. R. Hanson

This Bureau of Mines study examines the acoustic vibrational spectra of rock slabs in the range of 0 to 5,000 Hz. The power spectra of so-called drummy rocks were found to be diagnostically enhanced in the range of 200 to 1,000 Hz. Comparison of the power in this band with that in a band from 3,000 to 3,500 Hz provides a quantitative measure of rock stability. A prototype field instrument was designed, constructed, and field-tested. This battery-powered instrument computes the power contained in the two frequency bands mentioned, compares the magnitude of these two quantities, and displays a number that is related to the detachment of the block tested. Field tests show that this instrument is capable of giving reliable measurements of block stability under conditions of noise and dust that would seriously degrade the accuracy of normal sounding techniques.

Jan 1, 1985

By Louis C. Brichta

The Kline tract ?3.nd the Frey tract are two separate properties situated in the Wentworth district on the easterly edge of the Tri-State zinc-lead region (fig. 1). The Kline tract is in the southwestern corner of Lawrence County, Mo., and the Frey tract, 1 1/2 miles west of the Kline, is in the northeastern part of Newton County, Mo. A bureau Of Mines drilling project embraced work on both properties, but the amount of work done on the Frey tract was comparatively small. At the time of the project the Kline tract was under lease to the Wentworth Mining & Milling Co. The Surprise Mining Co. held the lease on the Frey tract. Underground workings on the generally flat-bedded are deposits of the Kline property-covered an area of-about 15 acres. No total metal-production records are available. In 1942-1943 the mine, operated by the Wentworth Mining & Milling Co., produced at an average monthly rate of 83 tons of 60-percent zinc concentrate derived from mining and milling 1,700 to 2,100 tons of ore. At the end of that period no significant amount of reserve ore was in sight. The gravity-flotation mill on the property was operating at about one-sixth capacity.

Jan 1, 1949

By D. Harrington

The desirability of efficient control of air currents, and the necessity of supplying metal-mine workers with better and safer working conditions, has created an active interest in metal-mine ventilation, especially in recent years. This paper discusses the subject both with regard to efficiency and economy, as well as safety and health. It is based on personal observations of the writer from over four year's study of metal mines in six States, in which more than 50 mines were visited. Many of these were studied in detail; in all several thousand working places were examined, and readings taken relative to ventilation run into the tens of thousands.Object of ventilating metal mines:Whereas in coal mines ventilation is generally regarded as essential, in many metal mines, especially shallow ones, the operators pay little attention to ventilation, or ignore it altogether. Recent shortage of labor, and numerous accidents to which State compensation laws have directed attention, are causing metal-mine operators to regard ventilation more seriously, especially in deep, large mines.There is, in fact, greater necessity for adequate ventilation of metal mines than of coal mines. The latter require air currents to remove explosive gases and the fumes of explosives, but metal mines, in addition to the need of removing fumes of explosives, and occasionally explosive gases, frequently have need of removing dusts dangerous to health, reduction of high temperatures and high humidity, and removal of inert but unhealthful gases like CO2 and nitrugen. The generally accepted superior healthfulness of coal miners as compared with metal miners, is probably due in large part to the better air circulation in working places of coal mines.

Jun 1, 1920

By G. M. Kintz

From 1895 to 1932, inclusive, 1,0163/ men were killed in and about New Mexico coal mines. Of these, 473 (approximately 47 percent) were killed in the 17 explosions listed in this paper. The second largest explosion of record in the United States, in so far as fatalities are concerned, occurred in New Mexico. The data in this circular were taken from publications of the United States Bureau of Mines and published annual reports of the State inspector of coal mines of New Mexico. The tables included are complete only with regard to major disasters. The Bureau of Mines considers as a major disaster one in which 5 or more men are killed. A few minor disasters are included, however.

Jan 1, 1934

By Fred D. Wright

Some new equipment for drilling vertical holes, cleaning blast holes, hauling explosives, and conditioning Diesel exhaust gas has been developed. at the Bureau's Experimental Oil-Shale mine near Rifle, Colo, The equipment has application, not only in oil-shale mining, but in many of the country's underground mines in which room-and-pillar methods of mining are employed. This report presents the Bureau's experience in testing the following equipment in the Experimental Oil-Shale mine: 1. A four-drill benching jumbo for drilling 23-foot vertical blast holes 2. A jet borehole blower for efficient cleaning of deep, vertical blast holes. 3. An explosives truck equipped with two compartments to provide safe conveyance for dynamite and detonators. 4. A mobile, electric substation to provide switching equipment, low-voltage and overload protection, and transformer facilities to remote locations in the mine. 5. A chemical conditioner for scrubbing the exhaust gases from Diesel-powered equipment used in underground operations. 6. Other units of equipment which have been tested at the Experimental mine.

Jan 1, 1951

By Oliver Bowles

The wire saw, introduced by the Bureau of Mines about two years ago, has revolutionized slate quarrying in Pennsylvania. The success of the saw since its early accomplishments has become greater and greater as the equipment has been perfected and skill acquired .in its use. In the first test made, a cutting rate of 9.7 square feet per hour was attained; in the next four cuts, made early in 1927, the average rate of cutting was increased to 12.8 square feet per hour; in 1928 a maximum of 34 square feet per hour had been attained, with a general average of about 20 to 25 square feet, The wire saw is now regarded as essential equipment in practically all of the quarries in the Bangor, Pen Argyl, and Windgap districts. The wire saw consists of a three-strand steel cable of 3/16 or 1/4 inch diameter running as an endless belt. The driving pulley is a 40-inch double-groove cast-iron sheave. A tension pulley supported by a frame mounted on wheels may travel back and forth on a short track. A weight of 800 to 2,000 pounds gives the desired tension on the wire. The driving units consist of electric motors with direct-drive compactly enclosed gear reduction, or double-belt speed-reduction units; the former is preferred. Silent chain and. pinion gear reductions are used to a limited extent. The travelling speed of the wire is about 15 feet per second. The driving and tension equipment are shown in Figure 1, A.

Jan 1, 1929

By J. K. Whyatt

Researchers at the U.S. Bureau of Mines have been exploring recent advances in the use of strain-softening constitutive laws that approximate shear fracturing. The purpose of these tests is to investigate shear-fracture-related rock bursts in hard-rock mines. The capabilities and remaining problems in the use of strain-softening laws in finite-element, distinct-element, and finite-difference methods are reviewed. Performance of the finite-difference implementation of strain softening is compared to classic experimental results and observations of rock mass behavior in the Coeur d'Alene Mining District of northern Idaho. The results show promise for developing methods to identify the general location and orientation of shear fractures and their sequence of occurrence, but such methods cannot be relied upon to quantify post-fracture loads or displacements accurately. Uncertainty over the amount of energy consumed by failing rock and the dependency of energy consumption on model mesh definition prevent direct application of the results to analyses of rock bursts.

Jan 1, 2010

By J. Roger Loebenstein

Demand for arsenic trioxide exceeded supply in 1978 and 1979, and the major domestic and foreign producers allocated available supplies to customers. Major demand has been from the cotton-growing and wood-preserving industries. Ample supplies of arsenic metal produced in the United States and Sweden were available in 1978 and 1979. Major demand for metal was from the automobile battery industry in Japan, Europe, and the United States. Legislation and Government Programs.-The Occupational Safety and Health Administration (OSHA), promulgated the final standard on the occupational exposure to inorganic arsenic, effective August 1, 1978.2 The need for the standard was a result of OSHA's conclusion that inorganic arsenic is a human carcinogen. The purpose of the standard was to minimize the incidence of lung cancer among workers exposed to inorganic arsenic. The maximum exposure to arsenic was lowered from the previous ceiling of 500 micrograms per cubic meter of air to 10 micrograms per cubic meter over an 8-hour time period. OSHA had originally recommended a ceiling limit of 4 micrograms per cubic meter in January 1975. Provisions of the new standard require exposed employees to wear respirators and undergo continuous medical monitoring. Other provisions establish regulated areas limited to authorized employees and require the construction of special lunch-room and worker hygiene facilities and the posting of signs and labels warning of the presence of arsenic. The new arsenic standard will have a significant economic impact on copper, zinc, gold, and lead smelters as well as consumers of arsenic trioxide. A number of copper companies have joined together to contest the standard in court. However, measures to comply with the standard have been initiated by ASARCO Incorporated at its Tacoma, Wash. plant.

Jan 1, 1980

By Nicholas Kyriazi

The Bureau of Mines subjected three commercial compressed-oxygen self-contained self-rescuers to a series of laboratory treatments designed to simulate various environmental conditions in underground coal mines. The environmental treatments consisted of extremes of temperature and of shock and vibration. The tests were designed to predict the ability of the self-rescuers to withstand those environmental stresses without causing a decrease in wearer protection. A critical concern was internal damage to an apparatus that would cause it to malfunction or seriously degrade its performance without any obvious external signs. The Bureau has previously tested chemical oxygen self-contained self-rescuers in a similar research program. Although the three compressed-oxygen units are not as sturdy as the chemical oxygen self-rescuers tested previously, they performed reliably after treatments on treadmill tests with human subjects and on machine tests using a breathing and metabolic simulator. Serious damage was caused by both the heat treat-ment of 71° C (venting of the 02 bottle in most cases), and in the shock treatment (breaking open of the case and dislodging of the components). When physical damage is obvious, a complete refurbishing of the damaged self-rescuer is recommended.

Jan 1, 1983

By H. S. Chiang, Y. Luo, S. S. Peng

"IntroductionThe way in which the particle sizes distribute in the airborne coal dust plays an important role in the transportation of the dust in the mine air and human respiratory systems. Though the particles of a size less than 10 microns could be inhaled, the real distractive portion of the dust is that the sizes range from 1 to 5 microns since only they can reach the lungs and be retained there. Those with an equivalent diameter larger than 5 microns will settle on the membranes of the branchial tubes(1) while those with diameter less than 1 micron can either be exhaled out of the lungs or the settled quantity is so insignificant that does very little harm to the lungs. In the transportation process, the finer dust will fly farther away from the sources than the coarser ones. Thus once the fine dust is generated and becomes airborne, it will spread out to a larger area.In this paper, the coal samples collected from two longwall faces were analyzed statistically for size distribu¬tion. A mathematical model is proposed and the effects of different conditions on the dust size distribution were analyzed using the mathematical model.Sampling and Statistical AnalysesSampling Instrument and ProcedureThe instrument used in the sampling were Mine Safety Appliance (MSA) personal sampling units equipped with 10-mm nylon cyclones, pre-weighed MSA PVC filters and constant-flow pumps.Two longwall operating faces were selected for the dust sampling. The two faces were located in two coal mines ex-tracting Pittsburgh seam. The double-ended ranging-drum shearer applying the unidirectional cutting sequence was employed. The two-leg shield supports were used for face support. The width of the two faces was about 215 meters.In each of the two faces, four sampling stations were set up. The stations were located at the cross-cut immediately outby the headentry side, the 15th support (25 m), 65th support (107 m) and 111th support (182 m) from headentry T-junction, and numbered as #1, #2, #3, and #4 station, respectively (Figure 1). At each sampling station, a group of three sampling units was hung at proper position. At cross¬cut (#1) station, the units were hung about one foot under the roofline in the center of the cut (Figure 2a), and at the stations in the face, the units were position near the hydraulic legs and one foot below the support canopy (Figure 2b).One complete set of 12 samples was collected for each day. The sampling were performed for five consecutive days. All the samplings were conducted in the morning shifts. The time duration of the sampling for each day was about five hours. During that time, the shearer might complete 5 to 7 mining cycles."

Mar 1, 1989

By George S. Rice

"The author was a member of a Commission sent by the Secretary of the Interior to France to investigate developments in mining and metallurgy under stress of war conditions, and also to observe the extent and character of the destruction of the collieries and the steel and iron plants, and methods which were being taken to reestablish them. This commission consisted of F. G. Cottrell, Chief Metallurgist of the Bureau of Mines, Frank H. Probert, Dean of the University of California Mining School, and George S. Rice, Chief Mining Engineer of the Bureau. While conducting this investigation a trip was made to the Saar Basin to observe the conditions there. Following this Mr. Rice acted as advisor on mining matters to the Representative of the Economic Council in an Interallied conference held at Cologne in April 1919, and subsequently visited the mining districts in central and southern France, Belgium, and Great Britain.The Germans, in planning a campaign for world supremacy, had as one of their first objectives the seizing of the important Briey iron ore deposits of France and the coal fields of Belgium and northern France.Large resources of coal and iron have led to the commercial greatness of the countries possessing them, as exemplified by the great development first in England then in the United States, and in Germany when the minette high phosphorus iron ores became useful through the invention of the Thomas and Gilchrist dephosphorizing process in 1878. However, this development was anticipated by the German scientific advisors in 1871, and led to the then known deposit of minette ore in Lorraine being taken from France by Germany.When these ores became available, Germany made such tremendous strides that its minette ore developments were not sufficient and importation of ore was necessary. Meantime France, by drilling, had established the extension of the minette ore field into French Lorraine. Then it was discovered that France had greater resources, while the German resources were being rapidly depleted.Although Germany, in its Westphalian basin, possessed the most important coal field on the Continent, containing the largest resources in coking coal outside of Great Britain, its coal was distant from the sea coast, so it could not be an important factor in the export business. No doubt this fact caused the German Imperialists to look forward: to securing the coal basin of Belgium and northern France for future ocean trade.It was a striking feature in the German conduct of the war that, although the steel and iron plants of Belgium and France and other industrial establishments in the invaded regions of Belgium and France were utterly destroyed, the iron mines in French Lorraine were not destroyed nor materially damaged by the Germans in their retreat, while the destruction in France continued until the day of the Armistice. The other striking fact is that the coal mines Of Belgium were not destroyed. It can only be conjectured whether this was due to President Wilson's threat of retribution, which did not stay their hand in France, or was due to the fact that they did not consider Belgium as a real competitor. It was evident they wished to cripple France industrially when they could not hold these northern provinces."

Dec 1, 1919

By G. M. Kintz

It is estimated that 10,000 lives were lost and $285,000,000 worth of property was destroyed by fire in 1937. Of the 103 fatalities in tie petroleum industry in 1938, 36 resulted from fires and explosions.3/ Everyone can help to prevent the tremendous losses, both in life and property, caused annually by fires and explosions, Forest fires occur every year, in which the tremendously intense heat wave ahead of the flame turns beautiful green trees into blazing torches like so much gasoline, vapor, and jumps over the tops of trees to start fires behind the firs fighters; prairie-grass fires occur, and a farmer in the path of the fire must plow a furrow around his home and outbuildings before the flame reaches them; and frequently automobiles are burned up in filling stations. Persons who have witnessed such sights know better than to throw a lighted match, cigarette, cigar, or hot coal from a pipe out of an automobile or to discard a fire or flame of any type in the forest, in the country, or in the city.

Jan 1, 1941

By E. B. Kester

A study of the composition of the corresponding fractions of a primary and a high-temperature tar was undertaken to throw light on the net results of the pyrolysis of the primary products of coal decomposition in high-temperature coking practice, with reference both to total quantities of the chemically similar constituents and to their distribution throughout the boiling range. No exactly parallel investigations are on-record. The distribution of substances in high-temperature tars, however, is fairly well understood. Such tars are more or less similar, for they consist of the more stable phenols, aromatic and olefinic compounds resulting from the pyrolytic decomposition of a wide variety of primary tar constituents. For example, from a typical distillation curve for high-temperature tar phenols it may be seen that the greatest portion of the phenols distills between 180° and 220° C., a fairly narrow range. Low-temperature tars, on the other hand, are more complex, and hence exhibit dissimilarities from one to the next. Edwards, who has made a study of the acids, bases, and neutral oil of four low-temperature tar distillates, shows that the bases and neutral oil are evenly distributed among the fractions but that the concentration of the acids is greatest in the 200° to 230° fraction. Morgan and Soule find that in tar from the "Carbocoal" process, the 237° to 281° fraction has the highest acid content, whereas Davis and Parry find the 200° to 225° fraction of Freeport tar richest in phenols. Previous investigators have noted the following differences between primary and high-temperature tar: In the latter, naphthalene and anthracene occur in large quantities, the paraffins and naphthenes are negligible, the percentage of higher phenols is much lower than in primary tar, and the lower and more stable aromatic hydrocarbons have increased. In an endeavor to reconcile the change undergone when a primary is converted into a secondary tar, the writers have been unable to find references dealing with the extent of change which any one of the constituents of primary tar may undergo when subjected to secondary heating effects in the presence of other components, and the amount of the more stable compounds that may be expected from a given starting material.

Jan 1, 1932

By E. Divers

This Bureau of Mines report presents results of an underground evaluation to determine the respirable dust and gas control effectiveness of a combined (push-pull) face ventilation system for coal mines. The system utilizes both blowing and exhaust curtain, continuous miners equipped with radio remote control, and flight conveyors. Bureau of Mines tests showed a 97% reduction in respirable dust concentrations from the usual cab position on the continuous miner to the remote control operator's position. This allowed the remote control operator to be well within, and the usual cab position to exceed, Federal respirable dust standards. Tests utilizing a safe tracer gas, sulfur hexafluoride (SF6), to determine the face ventilation effectiveness of the combined blowing and exhaust system showed that the system also has excellent methane dispersion capability. Where wide entries permit, this combined face ventilation system and use of remote control can be a very effective method for dust and gas control.

Jan 1, 1982