Search Documents

By James L. Konchesky

Crushed coal, consisting of a wide range of sizes, was effectively blended by recycling it through a bin equipped with a particle distributor. Vertical blending was accomplished by simply recycling the coal; it was not significantly influenced by the horizontal blending that was achieved by the distributor. The method was effective, even though the coal was wet and possessed poor flowing characteristics. Recirculation appears capable of providing uniform blends of solids that can be more efficiently processed. Recirculation also appears useful, preceding packaging operations, to insure for blending of solids into specification products. Continuous measurement of the bulk density of the coal by a gamma ray meter proved to be an effective monitor of vertical blending effectiveness.

Jan 1, 1972

By R. V. Lundquist

Lime-soda sinters, made and processed for recovering alumina and soda, consisted of several types of compound structures differing from the ideal dicalcium silicate and sodium aluminate. Many or these compound structures were causes for low alumina recovery and contributed to the relation or leach slurries. Presence or free lime, whether in the sinter or released by hydrolysis of sinter compounds, contributed to relation of leach slurries. Free lime tends to establish the initial viscosity assumed by a leach slurry. Previous investigations by the Bureau of Mines (1, 4)4/ and by other laboratories (5) have demonstrated the technical applicability of the lime-soda sinter process to the recovery of alumina from aluminum silicate materials. The basic concept of the process is sintering aluminum silicate materials with limestone and soda ash for the production of dicalcium silicate and sodium aluminate and then extracting the sodium aluminate by leaching the sinter in causticized liquors. Alumina is precipitated from the pregnant liquors by carbonating with carbon dioxide. Reaction in the sintering operation may be represented by the following simplified equation: A1203?SiO + 2CaCO3 + Na2C03 = 2Ca0?SiO + Na20?Al203 + 3C02

Jan 1, 1960

By S. D. Maksimovic

The use of vertical surface degasification boreholes with bleeder systems and the use of a timbered bleeder system to degasify gob areas were studied by the Bureau of Mines. This report describes three gob degasification studies conducted in the Pittsburgh coalbed. One study was conducted to determine the number of panels degasified with one large borehole. The study showed that the borehole provided degasification for three panels. Another study was conducted during the retreat of a 35-acre panel with a single-entry and a two-entry bleeder system and a large surface borehole. A major portion of methane emitted from the panel was carried away by the bore-hole, leaving the bleeder entries relatively free of methane. The last study was made to determine the effectiveness of a timbered bleeder system. The bleeder entries successfully degasified the gob area when enough entries were available and adequate pressure was available to force the air through roof falls.

Jan 1, 1980

By Thomas V. Falkie, R. Venkataramani

The method of analysis was to test a large model containing potentially significant variables and on the basis of the results obtained, to reduce the model to one containing only the essential significant variables. This stepwise procedure of "scanning" a large proposed model and subsequently condensing the model consisted of two cycles of the same series of computational procedures. Data Preparation A majority of the variables measured were continuous over a specific range of values; for example, the variable "Width Ratio" varied in practice from 0.25 to 1.00. However, "dummy" values were assigned to certain operational variables in order that these varia¬bles would have numerical expression. The following variables were described in this manner. Variable "Dummy" Value x3: Development/Pillaring 0, if pillar extraction was being done 1, if development mining was being done x4: Boxcut/Open Cut 0, if a box cut was being made 1, if an open cut was being made The variables under consideration are represented symbolically as follows: Y: Loading rate (tons per minuts): TONS/MIN x1: Ratio, width of cut/width of cutter: WDRATIO x2: Ratio, height of cut/diameter of cutter: HTRATIO x3: Development or pillaring: D/P

Jan 1, 1972

By A. J. Kraemer

"During the past several years a great deal of discussion has centered around the question of the permissible limit of sulphur content in fuels for automotive and aviation motors. Under certain conditions of operation, sulphur in motor fuels causes the formation of corrosive substances which attack bearings, wrist pins, and other parts of engines. On the other hand, in making gasoline from certain stocks, the gasoline fraction normally contains a relatively large proportion of sulphur compounds. By the generally used processes of reducing the sulphur content, a significant part of the gasoline fraction is lost as motor fuel, and added expenses are entailed for chemicals, labor, and other process costs. This condition has been an economic burden to some refiners of high-sulphur crudes. In some instances the treating losses have been rather severe and the treating costs relatively high, but the data presented in this paper indicate that the reduction of sulphur content of motor fuel is a problem to a relatively small number of refiners and of little or no concern to the remainder; in fact, more than 90 per cent of the 153 samples analyzed passed the Federal specification requirement, Which limits the sulphur content to 0.10 per cent. 3This report is based upon the results of an examination for sulphur content, Doctor test, copper strip corrosion, and color of the samples collected during January, 1930, for the twenty-first semiannual gasoline survey of the Bureau of Mines. The results of the gravity ad distillation tests of the survey were published as Report of Investigations 2995. The numbering of the samples given in this report is the same as in Report of Investigations 2995; for example, No. 25 of this report is the same sample as No. 25 of Report of Investigations 2995."

Jun 1, 1930

By F. W. Wood

Ingots of zirconium and other highly reactive metals such as titanium and hafnium produced by the consumable-electrode arc-melting process require conditioning before forging or rolling. A nondestructive, arc-conditioning technique has been developed as a substitute for lathe conditioning. The technique employs en electric arc under an inert atmosphere to fuse surface metal on the sidewalls of ingots without seriously affecting the general quality of the ingots. Advantages of the practice are Increased yields, lower accumulation of inferior scrap, and actual cost savings. The work cited in this report was done on zirconium. INTRODUCTION The consumable-electrode arc-melting process as practiced at the Bureau of Mines3 4/ has proved to be a technique for producing sound, homogeneous, commercial-size ingots of zirconium and its alloys. Ingots produced by this process, however, have as a characteristic a layer of partly fused metal on the sidewall to a depth of 3/16 to 3/8 inch. To prevent extension of surface imperfections during forging, the ingots are ordinarily conditioned by removing defective material in a lathe. If the metal were less reactive or the requirements less severe, the machine chips could be recycled and remelted. However, zirconium, being so oxygen sensitive, is contaminated by merely being machined despite extensive cooling of the tool bit. Further, being contaminated with oxygen, the chip metal upon remelting is 10 to 25 Brinell-hardnese numbers harder than the ingot from which it was machined. For this reason, the ingot specifications for naval reactor use have prohibited remelting machine chips, except as required for starting pads. Again, were zirconium less costly or less in demand this ever-increasing pile could be burned to oxide and recycled through the Kroll sponge process. Economics do not favor this, as melting feed stock has an estimated increase In value over oxide of about $8.80 per pound of contained zirconium. The efforts of the Bureau to solve the problem have been directed along two lines: To reduce the contamination of the machine chips produced and to reduce the quantity of the chips produced. This paper presents the technique developed to reduce the quantity of chips produced by arc-conditioning the remelted ingot.

Jan 1, 1955

By Thomas V. Falkie, R. Venkataramani

Table

Jan 1, 1972

By A. L. Murray, D. Harrington

From 1870 to the end of 1929 the coal production of Utah has been some- what less than 110,000,000 tons. During this period at least three major disasters have occurred with fatalities totaling about 380, establishing a decidedly bad record of approximately 3.5 persons killed by major mine explo- sions per million tons of coal produced. Even during the period when there have been no disasters, such as the years 1914 to 1920, inclusive, the fatalities in ordinary working were about 5.4 per million tons produced, against 3.7 per million tons for the whole United States for the same years. The 5-year period following the World War, 1918 to 1922, inclusive, had 4.7 fatalities per million tons; hence, the fatality record in the coal mines of Utah has uniformly been in excess of the average of the coal mines of the entire country. Notwithstanding this poor record, Utah has given to the coal-mining world many excellent safety methods and practices, and Utah coal mines in general take greater measures toward safe mining than do the coal mines of any other State; if practices and methods allowed and pursued in coal mines of other States were tried in Utah coal mines, there would be a succession of disasters.

Nov 1, 1931

By Philip C. Good

The Bureau of Mines investigated the feasibility of utilizing low-grade phosphatic shale as a feed for phosphoric acid production. Present practice in the phosphate mining operations of southeastern Idaho is to remove and either stockpile or waste low-grade phosphatic shales as the high-grade phosphate beds are selectively mined. Acid digestion studies were performed on uncalcined shale and on shale calcined to remove free carbon to determine phosphoric acid quality, yield, and amenability to filtration. The untreated shale, containing 21.4 pct P205, was digested with sulfuric acid in a single-tank reactor to yield phosporic acid and gypsum residue. Although 96 pct P205 recovery was attained in digesting uncalcined shale, only the calcined product gave satisfactory filtration rates. Calcined shale yielded phosphoric acid recovery of about 93 pct of the contained P205. It was higher in impurities than commercially prepared acid derived from high-grade western phosphate rock. An acid filtration rate of 745 lb P205/ft2/day was attained. This value is lower than the rate of 900 lb P205/ft that is generally considered to be acceptable in industrial production of phosphoric acid from high-grade phosphate rock.

Jan 1, 1981

By R. L. Grayson, W. E. Wallace, T. Simonyi, J. C. Harrison

"Application of an SEM-based methodology suggests a reason for past contradictory results on the relationship between quartz and coal workers' pneumoconiosis (CWP). Results indicate that coal seams with the same bulk analysis of quartz may have different amounts of surface-availablequartz. Our research shows that the amounts of pure and surface-available quartz in a respirable dust vary directly with the rank of a coal seam, except in the case where rock materials are mined. The estimated amount of surface-available quartz therefore provides a measure of the quartz-related fibrogenic potential of a respirable dust.INTRODUCTIONFrom our previous work (Grayson, 1991), we have shown that the amount of pure quartz in a respirable coal mine dust sample appears to vary directly with the rank of the seam (using fixed carbon as the basis for comparison), except when a substantial rock parting, roof or floor are mined. Our other work (Wallace et al., 1989) showed that high-silica particles in a clay mine may generally be coated with clay, rendering the quartz core non-available for surface reaction in the lung. The combination of these findings led us to hypothesize that the coating phenomenon may indeed be present in coal mines as well, and that a rank relationship may be present regarding this phenomenon. Thus higher rank coal seams may have more surface-available quartz as well as more pure quartz particles in their respirable dusts. The scientific protocol for testing this hypothesis and the results obtained to date are discussed in this paper. Thus far, there is no reason to doubt that the relationship holds."

Mar 1, 1992

By W. J. Fene

It is often desired to obtain samples of air in places where collection by ordinary methods is not feasible, as in shafts amore means of descent or ascent are not provided, in sewer manholes, in gas or water wells, in empty oil tanks, and in sealed areas in mines. Heretofore, when such sampling was required, it was necessary to utilize the aspirating method, which was not always satisfactory; and to obtain samples of air in deep shafts, it was necessary to use long sections of rubber tubing, which was not always available. DESCRIPTION OF NEW DEVICE A new method or "device" employs a common snap-type mousetrap to break the neck of a vacuum tube at the place where it is desired to collect the sample (see fig. 1). A mousetrap is mounted on one end of a block of wood 11-3/4 by 3 by 3/4 inches in such camper that a lead weight attached to the trigger hall spring the trap when the device is given a sharp jerk. A vacuum tube is placed on the other end of the block and held in place by a strong rubber band. A strip of corrugated rubber is placed on each side of the grooved block to prevent the tube from clipping when the sample is taken. An adjustable shoulder, provided with a rubber cap, is pieced se that the neck of the vacuum tube will rest on it. The shoulder is made adjustable to accommodate various sizes of tubas and to keep the neck of the tube from breaking tee far back from the point. A metal handle is fastened to one end of the block, with a hole in the end through which the brass wire used for lowering the device is tied. The device is enclosed by a strong wire-gauge covering, hinged on one side and so arranged that it can be locked shut on the other side. This covering prevent: breaking of the tube while it is being lowered or raised in a shaft or other place. Brass wire of not less than 22 gage should be used for lowering the device. A detailed drawing of the device is shown in figure 2.

Jan 1, 1940

By W. W. Adams

"A gratifying decrease is noticeable in the number of men killed in the coal minas of the United States during the past six months as compared to the quantity of coal produced.During July last year, when 221 men lost their lives, the production of coal was over 50 million tons. In January, 1920, the production had increased to 56 million tons, or 11 per cent, while the fatalities, instead of increasing proportionately, actually decreased to 166, or nearly 15 per cent. Nor is this decrease a mere accident or coincidence peculiar to the month of January, as may be seen from the following table.From the figures shown above it may be observed that the average monthly production for January and the five months immediately preceding, was 49,500,000, or only 2 per cent below that for July, while the average number of men killed was 183, or a decrease of over 17 per cent."

Mar 1, 1920

By R. D. Ladoo

"At the beginning of 1920 a general feeling of optimism was noted in many talc-producing districts. The industry seems to have recovered from the temporary depression of the first half of 1919 and many mills are running at capacity production with their entire output for 1920 contracted for. The imports of talc for 1919 were only slightly larger than in 1918 by weight and probably no more by value. Thus foreign competition has not begun to be seriously felt. Several new companies in this country have been organized, some to operate new deposits and others to continue the work done by others.An interesting phase of the present situation is the possibility of increased use of talc in paint. There is a shortage of barium sulfate used as,paint filler. Since, for some uses, talc is considered second only to BaSo4 as a filler for paint, it is possible that part of the shortage could be relieved by an increased use of talc.A series of physical tests upon all pigment materials used in the manufacture of paints is being conducted for the Paint Manufacturers Association of the United States. It is important that all types of talc be represented in these tests. Producers of finely ground talc, 200 mesh and finer, are urged to submit samples of at least two pounds each of these grades that are available to paint makers with trade name and quality data, to the Institute of Industrial Research, 19th & B Streets, Washington, D. C., where the tests are being conducted.The Talc Products Company, Inc., Washington Building, Los Angeles, California, has recently been organized to develop a large body of talc one mile north of Riggs, San Bernardino County, California, This deposit contains a compact, white talc which can be sawed into crayons. The company's mill, at Los Angeles) is equipped with a unit of the Raymond system of grinding and air separation, and pencil sawing machines. It is reported that the pencils are being successfully used in Pacific Coast ship yards.The mining of talc where no mill is owned by the operator and the consequent sale of talc in its crude massive state has not proved profitable in a number of cases recently noted. Under exceptional circumstances, where mining costs are low and the product can be sold to a mill near the mine, the operation maybe profitable, but this condition is not common. One mine of this type has recently closed down, at least temporarily; but a second, more fortunately situated, in another district, is continuing operations, although plans are being made to erect a mill in the early spring. Most satisfactory results are ordi¬narily obtained where the mine and mill are owned by the same company.The sale of the Balmat mine of the International Pulp Company, near Gouverneur, N. Y., to J. H. McLear, Gouverneur, and H. G. McLear of New York, has been reported. It is stated that a large part of the property has been already leased to the Sylvia Lake Company, who will operate it. ""Cement, Hill, and Quarry""* states that ""the first mining done on this property was for silver and lead, but it developed into a good zinc producing property and later it was worked for its talc deposits. It has passed through several hands, the American Pulp Co., the Union Talc Co., and the International Pulp Co., all having had it in successive periods since 1891."""

Jan 1, 1920

By J. J. Bean

This paper, describing the milling practice at the oxide concentrator of the International Smelting Co., is one of a series on milling methods and costs being published by the United States Bureau of Mines. GENERAL DESCRIPTION The oxide concentrator is properly an integral part of the Tooele plant of the. International melting Co., located 5 miles from Tooele, Tooele County, Utah. It has a capacity of 300 tons of ore per day and uses an all-flotation process to treat custom siliceous oxidized lead ores obtained principally from the Tintic district in Utah. Ores found amenable to the process are purchased on a custom basis, the principal tonnages being obtained from the Tintic Standard and North Lily mines.

Jan 1, 1933

1. In 2001, a total of 7,131 sand and gravel mining operations reported employment statistics to the Mine Safety and Health Administration (MSHA). Sand and gravel mines comprised 48.8% of all mining operations, the largest percentage of all mining sectors. Sand and gravel mines are distributed throughout all 50 states. The median number of operator employees per sand and gravel mine was 3.0.

Jul 1, 2003

By R. R. Wells

This report summarizes the results of laboratory testing of copper-bearing magnetite ore from the Poorman, Bush & Brown, and Copper Center deposits, Kasaan Peninsula, Prince of Wales Island, southeastern Alaska. The ores contain minor amounts of chalcopyrite and pyrite. Intimate association of these sulfides with magnetite necessitates fine grinding for adequate liberation and rejection of copper and sulfur and for the production of high-grade iron concentrate low in objectionable impurities. Laboratory tests indicated that the optimum results can be obtained by flotation of ore ground to minus-100-mesh, with subsequent wet magnetic separation treatment of the flotation tailing. A summary of results obtained by this treatment of the three samples tested is shown in table 1.

Jan 1, 1957

By Gerald W. Elger

A new process under development by the U.S. Bureau of Mines for producing synthetic rutile from ilmenite is described. Rutile formation is based on oxidation and fluxing of titania slag produced by electric furnacing of ilmenite. Laboratory tests show that phosphorus pentoxide flux additions to oxidized slag enhance conversion to rutile by forming a phosphate-based glass matrix. This matrix contains most of the major impurities, including the oxides of iron, aluminum, magnesium, manganese, and silicon. Rutile crystals of 5 to 150 microns in size were formed in slags heated to temperatures of 800° to 1,550° C. The synthetic rutile crystals were liberated from ground slag by treating with phosphoric acid to weaken the glass matrix, followed by attrition scrubbing. Rutile fractions analyzed as high as 94 percent titania content. In several instances, more than 90 percent of the titanium in the shag was recovered to yield combined rutile fractions containing 90.2 to 92.6 percent titania.

Jan 1, 1971

By J. D. Tolman

In view of present interest in a revival of gold mining enterprises, papers dealing with the development of small gold properties are apropos. The present paper deals with the operation of a small gold property in the exploration and development stage, mining and milling 25 tons of ore daily, and indicates what may he expected in the way of mining costs under northern climatic conditions, by practicing rigid economy, at a property where disproportionate overhead costs are unavoidable bacause of the small rate of production. The output of this prospect is treated in a small amalgamation plant which has been described in a previous circular.. HISTORY Prospecting in the district was begun in 1909, and by 1911 the adjoining mines, Hollinger and McIntyre, were in operation. Actual work was begun on the Rochester claim in July, 1922, and carried on through 1924. The property was closed until 1928 when the present company took it over, together with the other holdings of the Canadel Mining Co. A small mill was started as a pilot plant on March 24, 1929, and is still in operation.

Jan 1, 1931

By Wilbur Duvall

For the past few years the Applied Physics Branch has been investigating, experimentally, the generation and propagation of strain waves in rock. The strain waves are produced by the detonation of a high-velocity explosive placed in a small cavity in the rock. Strain gages mounted in the solid rock surrounding the cavity record the strain pulses propagated away from the source. Numerous strain-wave pulses have been recorded in different rock types for charges of various sizes and at various distances from the charge. Analysis of these records has shown, among other things, that there is associated with the strain wave a characteristic pulse width. This pulse width is dependent on the rock type and the distance from the shot point to the gage, but is apparently independent of the charge size or cavity size. Recent published literature on the generation and propagation of seismic waves indicates that the characteristic frequency of an elastic wave generated by an explosion should be a function of the rock type and the size of the cavity created by the explosion. Also, internal friction in the rock would produce absorption of high-frequency components, which would cause continual change in the shape of the pulse propagated. As the experimental data did not verify the expected change in pulse shape with cavity size, a theoretical investigation of the vibrations associated with a spherical cavity in an elastic medium was undertaken.

Jan 1, 1950

By Wesley A. Grosh

The Valzinco mine, Spotsylvania County, Va., is a lead-zinc deposit with minor quantities of copper. The property was reopened n 1942 by Panaminas, Inc. The Bureau of. Mines, in an effort to increase the reserves of the deposit to justify greater production, diamond-drilled nine holes totaling 4,213 feet during 1943. Drilling by the Bureau delimited the original ore body and discovered another ore body on the hanging-wall side, which was being developed by the company at the close of the project.

Jan 1, 1949