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By Foster Fraas

This report describes the application of pulsed magnetic fields derived from alternating and intermittent magnetizing currents. Application of such pulsed magnetic fields to the matrix-type separator permits (1) the complete discharge of the magnetic fraction with wet feeds and (2) the dry separation at particle sizes down to 325 mesh. At smaller particle s indications are that frequencies above 60 hertz will be required. Applications of intermittent magnetizing current to the cross-belt separator give the cross-belt-separator an advantage over the conventional constant-field cross-belt and induced roll separators; the intermittent current enables the cross-belt separator to separate matted fibrous and magnetically coagulating feeds, a type of feed that occasionally occurs with mineral, industrial, and secondary materials.

Jan 1, 1973

By S. L. Windes

For a number of years, the Bureau of Mines conducted tests on various types of structures to determine the effect of seismic vibrations emanating from quarry blasting in an effort to determine an index of damage . Associated with these tests , occasional records were made of the characteristics of. the air blast or concussion from the explosions . Although the importance of the air - blast problem was recognized , the equipment was not designed for air -blast measurements , nor was the early research program concerned with the problem . After the ground - vibration tests had been completed , attention was turned to study of the air blast and its effect . The air - blast problem in reference to quarry and mine blasting may be divided conveniently into three phases : (1 ) Determination of the fundamental characteristics of the air blast , such as the pressure - time relationship , speed of propagation, attenuation , and the like ; ( 2) effect of blasting conditions on these air -blast characteristics ; and ( 3) determination of the conditions necessary for damage to structures . The initial step was the development of microphones suitable for recording the anticipated blast pressures. Such microphones were designed and built during 1940 , and described in technical detail for publication ( 2)3/. Briefly, the microphone adopted was a small, plate - diaphragm condenser type . The recording was through special transducer amplifiers with low -frequency response to zero cycles per second and a Duddell - type oscillograph of special design .

Feb 1, 1942

By Stephen A. Swan

Certain types of mobile surface mining equipment are required to be equipped with rollover protective structures (ROPS) capable of protecting the operator in case of a rollover accident. The Bureau of Mines has developed ROPS performance criteria for wheeled front-end loaders. This report reviews the development of rollover test procedures and subsequent testing of ROPS for 52,000-, 286,000-, and 390,000-lb gross vehicle weight (GVW) loaders. The program consisted of both dynamic (roll) and static tests to assist in the development of the ROPS performance criteria. Each test included extensive instrumentation and photographic documentation to fully evaluate the performance of the ROPS. Data summarizing side, longitudinal, and vertical force and deflections are included. The data indicate that for loaders in excess of 240,000 lb, GVW, a side force-to-mass ratio of 1.0 and an energy-to-mass ratio of 6.0 appear to be adequate criteria to protect an operator in the event of a 5400 rollover. For smaller machines, Society of Automotive Engineers (SAE) 11040 performance criteria provide adequate protection. Longitudinal loading, though not ad-dressed in previous ROPS performance criteria, was shown to be a potentially significant factor in ROPS failure. Longitudinal loading and energy criteria equal to 80 pct of side loading criteria are recommended.

Jan 1, 1988

By Gopala N. Krishnan

The most promising candidate for the recovery of alumina from non-bauxitic sources is the leaching of clay by HCL acid followed by crystallization of aluminum chloride hexahydrate (ACH) by hydrogen chloride sparging. Hydrothermal precipitation of boehmite ( ?-A100H) from aluminum chloride solution will simplify the process, will reduce energy consumption and will eliminate corrosion problems involved in calcination of ACH to obtain alumina. This report summarizes the results of Phase I of a program to study the precipitation of boehmite from AlC13 solutions. The amount of boehmite precipitation from dilute A1C13 solutions (5 wt%) is . negligible below 200°C. Above 200°C the precipitation increases with increasing temperature approaching 40% at 300°C. Addition of HCl acid to the dilute A1C13 solution even in small quantities drastically reduces boehmite precipitation. Solution impurities such as Fe, Ca, Mg, or Na substantially promote the precipitation of boehmite. No precipitation is observed from concentrated A1C13 solution (30wt%) representing the leach liquor.

Jan 1, 1980

By G. L. Oldright, Virgil Miller

"INTRODUCTION The first ten papers of the series on smelting in the lead blast furnace described the operation at the custom smelter of the International Smelting Co., Tooele, Utah, and at the plant of the Bunker Hill Smelting Co., Kellogg, Idaho, which handled a very rich lead concentrate. These previous papers may be considered a picture of the traditional lead smelter treating custom ores and of the smelter that will treat the type of product likely to be made in the future - lead concentrates of an increasingly rich grade.The great plant at Trail is of special interest to those smelting lead products containing much zinc and faced with the necessity of transforming all of their byproducts into commodities which may be sold profitably. The plant is equipped to produce electrolytic zinc, lead, copper, silver, bismuth, and cadmium. Part of the sulphur evolved from treating the ores is converted into sulphuric acid. Complete fertilizers for agricultural purposes are also produced.The smelter of lead ores has long considered that zinc is one of the most difficult ingredients that he has to handle. Even with the gretat improvement in flotation practice today, the residues from electrolytic zinc plants leaching zinc concentrates must still be smelted for their lead content. Of the total gangue material not separated from the lead concentrate sent to the smelter, zinc is still one of the most notable in percentage. The most successful way of coordinating the over-all operations of a concentrator, an electrolytic zinc plant, and a smelter provided with a plant for re-treating the blast-furnace slag for its lead and zinc content must be of interest to many treating complex ores.ACKNOWLEDGMENTThe data in this paper were collected in cooperation with the Consolidated Mining & Smelting Co. of Canada, Limited, and its entire technical staff. Detailed acknowledgments of assistance received are given in the papers from which this one is briefed."

Sep 1, 1934

By W. W. Adams

The extent to which coal mines have installed various types of haulage systems and mining machines is a subject about which there is little definite information available in convenient form for the country as a whole . A few State mine inspectors include in their annual reports such information for their respective States , but uniform data for the United States have not until recently been compiled . Several years ago the Bureau of Mines compiled from one of the standard mining directories * a statement showing the kinds of machines and haulage used in coal mines . The first statement was prepared from the 1918 edition of the directory in which detailed descriptions of coal mines were given . The information presumably related to the calendar year 1917. Similar statements have been compiled from the directories for 1919 , 1920 , and 1922 , the statement for 1921 having been omitted because the directory for that year did not become available . The latest statement is given below and is based upon the directory for 1922. It relates to conditions prevailing in 1921 , and covers a total of 7,088 coal mines . Of these , 5,064 mines . or more than 71 per cent , were using animal haulage . As compared with the total number of all classes of mines , those in the animal - haul age group constituted 71.4 per cent , the percentage having remained practically stationary during the past four years , although the actual number of mines in the group has increased . Rope haulage was reported by 1,066 mines , or 15 per cent of the total , representing a larger number of mines than in 1918 , but a decrease of 2 in the percentage for the group as compared with all classes of mines . Electric haulage was reported by 3,274 mines (46.2 per cent ) , and the number of motors in use was 11,265 . The percentage of mines in this class has not changed materially, but the actual number of mines has shown a gain of about 900 during the past four years . Compressed-air locomotives have not increased either in actual or relative number , the percentage for the past year being but 1.2 . The number of mines using storage- battery locomotives has increased from 3.6 per cent of the total shown four years ago , to 9.8 per cent for last year, the latest figures showing 693 mines with 1,428

May 1, 1922

By Alan G. Mayton

The Bureau of Mines conducted a study to (1) determine from laboratory tests the feasibility of a photographic method for determining reflec-tances that may be applied to measuring in-mine mineral reflectances and (2) formulate a procedure for collecting and analyzing the data. The method uses a 35-mm camera with automatic flash and a gray-scale re-flectance standard to collect on film the reflectivity data in under-ground mineral mines. After the film is processed, the data on the photographic prints are analyzed in the laboratory with a photometer. Test results show the photographic method can provide values of reflec-tance to within ±5 pet of full scale (full scale = 100 pet). The method's usefulness for determining reflectivity values, within similar limits of absolute percent error at the lower end of the scale, however, has not been completely resolved by the study and consequently warrants further investigation. The method offers an acceptable means for collecting and analyzing reflectivity data for reflectivities at the higher end of the scale, i.e., 50 pet or above; it should be used with caution when reflectivity values are below 50 pet. Four films were evaluated; all gave relatively satisfactory results.

Jan 1, 1987

By B. B. Letson

The heats of formation of lithium chloride and lithium oxalate were determined with the aid of a Bureau-developed, glass Dewar-type solution calorimeter which uses thermistors as its temperature sensing element. Values obtained at 298.15° K were -98.38 ± 0.54 kcal/mole for lithium chloride and -329.02 ± 0.79 kcal/mole for lithium oxalate, using graphite as the standard state for carbon.

Jan 1, 1965

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 D. K. Deardorff, Laurance L. Oden, H. Kato, M. I. Copeland

The equilibrium relationship of hafnium and tantalum was studied to facilitate alloy and property investigations . The data obtained are presented graphically as the equilibrium diagram . Alloys were prepared from high - purity components by nonconsumabletungsten- electrode arc melting . Data for the equilibrium diagram were obtained by optical pyrometry , metallography , X- ray diffraction of heat treated specimens , X- ray diffraction using a high- temperature camera , and differential thermal analysis . During the investigations , a casting apparatus was constructed , and the existing melting - point apparatus was improved . The bcc allotrope of hafnium forms a continuous series of solid solutions , called beta , with tantalum which exhibit a minimum melting point at 20 wt pct tantalum and 2,110 ° C. At 24 wt pct tantalum and 1,050 ° C , hafnium- rich beta decomposes in a monotectoid reaction to yield alpha and tantalum- rich beta . The monotectoid isotherm extends from 5.5 to 60 wt pct tantalum . The twophase region , in which hafnium- rich and tantalum- rich beta solid solutions are immiscible , rises to a maximum temperature of 1,265 ° C at 38 wt pct tantalum . The solubility of hafnium in tantalum decreases from 40 wt pct at the monotectoid temperature to 20 wt pct at 750 ° C.

Jan 1, 1964

By G. S. Scott

The flammability of trichloroethylene vapors in air has been determined in a 7-inch cyclindrical vessel. Saturated flammable mixtures were formed with air at atmospheric pressure between 30° C (86° F) and 82° C (180° F); the trichloroethylene concentrations at these temperatures are 12.5 (lower) and 90 (upper) volume-percent, respectively. Further study is necessary to assess the effects of different variables on the flammability of this material. INTRODUCTION Trichloroethylene (TCE) (ClHC = CCl2), sold under various trade names (Blacosolv, Perm-A-Clor, Tri, Triad, Triclene, Trivec, Tromex, Vapoclean, Vapoclor, Westrosol, etc.), is an important industrial chemical. A summary of its physical and chemical properties is given in table 1. It is used to degrease metals, leather, and textiles, to extract residual oils from vegetable oil cakes, for dry cleaning, and in soap. It is a powerful solvent for fats, resins, bitumens, rubber, sulfur, and phosphorus. Several explosions in which trichloroethylene was involved prompted an investigation by the Bureau of Mines to determine the conditions under which such accidents can occur.

Jan 1, 1963

By Philip W. Holland

The Bureau of Mines has developed a trace helium analyzer for deter-mining helium-4 in the parts-per-billion range. The instrument is used for analyzing pure gases, laboratory-prepared standards, and atmospher-ic samples. Accuracy at the 95-pct confidence level in the 50-to 20,000-ppb range is within ±2 ppb or ±0.4 pct, whichever is greater. The minimum detectable helium-4 concentration is calculated to be 5 ppb. The analyzer consists of a modified helium leak-detector mass spec-trometer, a laboratory-built sample inlet system, and a liquid-nitrogen-cooled charcoal trap. A programmable integrator and event-control module make automatic operation possible. The portability of the analyzer allows it to be used in the field.

Jan 1, 1984

By G. E. McElroy

This report discusses the construction and use of an all-pressure psy- chrometric chart in which the requirements of simplicity of appearance and absolute accuracy have been waived, to a certain extent, to provide for the rapid determination of psychrometric data and for the rapid solution of air- conditioning problems of major interest to the mining industry. Many mines in which air-conditioning problems are important are situated at elevations far above sea level and embrace great differences in elevation - in excess of 8,000 feet in certain mines → throughout their airflow circuits. Under these conditions, the effects of variations in the pressure of the at- mosphere upon the physical properties of the mixture of air and water vapor of which it is composed are considerable and should be taken into account in the solution of problems. The simple types of psychrometric charts in common use, such as the Carrier, Bulkeley, Hill, and Goff (American Society of Heat- ing and Ventilating Engineers Guide), are not generally suitable, in that they are drawn for a single barometric pressure 29,92 inches mercury.

Dec 1, 1947

By L. G. Marshall

The geology, mining, beneficiating, types of products, and costs in terms of percent of total costs and of labor, power, and supplies of two crushed-limestone operations in Madison County, Iowa, are described in this paper. The operations are basically similar, differing in refinements in mining, product types, and markets. The operations are comparable as to personnel and as to weighted costs in terms of percent of total costs and in terms of man-hours, power, and sup-plies. The waste-to-stone stripping ratio is 1 to 0.8 at both operations, the powder factor is 0.29 pound of explosives per ton of stone, and daily production is 95 tons per man-shift. Both companies use crawler-mounted diesel shovels for loading, truck transportation, wagon drills, and dry screening.

Jan 1, 1963

By ALICE V. Petar

Among the rarest of the rare metals are four that are linked together by a common historical background as well as by chemical relationship. With the excep- tion of indium, these metals are likewise characterized by the patriotic nature of the names given them by their discoverers. The existence of gallium, germanium, and scandium, was predicted by the Russian cherist, D. I. Mendeleeff some time prior to their discovery; and these elements might well have been overlooked, had not the search been stimulated by the urge to confirm the scientific hypothesis of their existence. Nowhare found in sufficient quantities to attract attention, these little known elemente are nevertheless widely distributed in the earth's crust. So far they are found commercially mostly in the sulphide ores of zinc and must be considered as being largely curiosities of the zinc smelter. Recent progress in electrolytic zinc refining, however, now gives promise that the way may be open for the recovery of these very rare metals in larger quantities-- possibly in quantities sufficient to permit of their finding commercial utilization.

Nov 1, 1930

By G. R. Hopkins

"The average heat requirement per barrel of crude refined in the United States rose from 579,000 B. t. u. in 1940 to 584,000 B. t. u. in 1941. This marked the second successive year in which there was an apparent loss in fuel efficiency at refineries. This ""loss"" took place despite an increase in crude runs, which used to be an invariable indicator of a lower average.Probably the chief factor in the increased heat requirement in 1941 was the gain in the over-all gasoline yield from 43.1 percent in 1940 to 44.2 percent in 1941. Possibly another important factor was the further use of obsolete equipment to increase throughput.The refiners used more of all kinds of fuel excapt coke in 1941 than in 1940. However, the only fuels which increased materially in relative importance were refinery gas, which contributed 51.6 percent of the total heat units in 1941 compared with 50.7 percent in 1940, and natural gas, the share of which rose from 17.1 percent in 1940 to 18.0 percent in 1941. The changes in the percentages for the other fuels were as follows: Oil decreased from 25.7 to 24.1 percent; acid sludge fell from 2.7 to 2.5; coal remained at 3.4 percent; and coke (including steam) fell from 0.5 to 0.4 percent.New records for fuel efficiency were set in all three of the districts east of the Mississippi, namely, East Coast, Appalachian, and Indiana, Illi¬nois, etc. All the ether districts reported higher average fuel requirements in 1941, except the Louisiana Gulf and Arkansas-Louisiana inland.Since the year of the first statistics, the refiners have steadily increased their purchases of electricity. In 1941 total purchases were 1,862,996,000 kilowatt-hours, or 11 percent more than in 1940."

Apr 1, 1943

By Nicholls Harry R.

The Bureau of Mines studied the effect of varying the, diameter of explosive charges on the generation and propagation of strain waves. The parameters compared were strain amplitude, impulse, energy, and pulse shape. Three different explosives were detonated in three different charge diameters. Charges of cast 50/50 pentolite-detonated at the same velocity in 5-, 2.5-, and 1.5-inch diameters. Charges of ammonium nitrate-fuel oil prills and 45-percent semigelatin dynamite showed a strong detonation rate-diameter dependency. Detonation of these two explosives was considered nonideal. Differences in the diameter of the charge caused less difference in the strain-generating abilities of pentolite than in those of the other two explosives. This was also true for impulse and energy. Rise and fall times of the strain pulses for all three explosives were proportional to detonation time and cavity volume, respectively.

Jan 1, 1966

By E. D. Gardner

"Introduction Ore from stopes in metal mines is generally dumped or drawn into chutes or raises through which it passes by gravity to the haulage levels. Occasionally, and under some conditions quite frequently, the ore in a chute will wedge or hang and refuse to run. This hanging of the ore may be due to the packing of damp or clayey material, to boulders forming an arch, or to loose lagging or other timber becoming lodged in the chute.In drawing material from a loading chute it is drawn out a car at a time, and the intermittent flow of the material .increases its tendency to hang. When the obstruction in the chute is near or at the loading gate, the chute pullers start the ore by punching it with iron bars inserted through openings in the chute gate. When the obstruction is beyond reach of the bars, other means of starting the ore must be used.In some systems of mining, chutes or ore raises are built with timber as the stope extends upward. Generally, a manway is left alongside of the chutes, and when the ore hangs in a chute usually it can be started by a miner from the manway ladder by pounding on the timbers of the chute or by punching the ore with a bar inserted through small holes in the chute lining. Special methods of starting clogged ore, such as shaking a chain left hanging in the chute, are used at some places.In other systems of mining, ore passes or chutes are run through solid rock and when the ore hangs in one of these passes, either it must be blasted or else started from the top. Sometimes the ore can be started by running water into the top of the chute, but if the water does not start the ore moving, it must be blasted from underneath. This is done by detonating a bundle of cartridges under the obstruction in the chute or raise."

Jan 1, 1927

By Will H. Coghill, G. Dale Cole

"INTRODUCTION This paper describes a method for the rational sorting of particles by means of a laboratory batch jig. Its purpose is to show that a material can be reliably appraised for gravity concentration without the drudgery of sink-float fractionations.Development of the batch- jig method of testing was incidental to a study of the Birmingham, Ala., red-iron ores now being conducted by the Bureau of Mines in cooperation with the University of Alabama and the ore-producing companies.APPLICATIONOres and coal are commonly tested for their gravity-concentration characteristics by specific-gravity dissections in heavy liquids. The heavy liquid most commonly used for coal is zinc chloride and for ores they are benzene, carbon tetrachloride, acetylene tetrabromide, methylene iodide, and thallium malonate formate. The last is poisonous and corrosive to the skin but is essential for separations in the 3.3 to 4.4 specific gravity range. The last two of these liquids are expensive, and several of them are hard to obtain now.Although it is not suggested that heavy-liquid dissections be eliminated entirely, sometimes a more reliable evaluation of coal and ore can be obtained by other and more simple means. For example, sink-float data were unsatisfactory as a guide to commercial gravity concentration of a red-iron ore because they did not take into account the difference in particle shape of the hematite and gangue and the differences in true and apparent specific gravity of the hematite grains, some of which were porous. For this ore, the batch-jig method of testing herein discussed proved advantageous. Not Only did the batch-jig data give a truer picture of the concentration problem, but only about one-tenth the time of the conventional sink-float tests was required."

Jul 1, 1944

By E. Morrice, R. D. Smith

Thermal expansion and electrical resistance measurements were made on cerium metal from 4° to 300° K. The apparatus developed , including a specimen holder and a cryostat system , are described along with the experimental techniques used in obtaining the measurements . The total linear thermal expansion Data at of 99.83 weight - percent cerium metal between 4 ° K and room temperature was 4.24 percent . The resistivity at 4° K was 7.0 x 10-6 ohm- centimeter . 4° K indicate a fundamental relationship between residual resistivity and purity of cerium metal . The effects of annealing and repeated thermal cycling on resistivity were determined .

Jan 1, 1964