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By Charles L. Kimbell

Available statistics on 1991 worldwide consumption of selected non fuel mineral commodities shown in table 12 indicate downturns for all but 3 of the 15 listed commodities. It should be stressed that in most instances, the consumption declines were primarily the result of lower levels of use in the former U.S.S.R. and the former centrally planned economy nations of Eastern Europe. However, several commodities suffered use cutbacks in market economy countries. In the case of the nonferrous metals covered In the table, the differences in performance between market economy countries and the former centrally planned economy states are immediately evident from the table itself. Among these important commodities, refined lead, primary magnesium, and refined tin registered downturns for market economy countries as well as among the centrally planned economy countries. Also notably, cadmium use showed no significant change from 1990 levels in either group of countries. Global consumption of iron ore fell by 3.4 % or about 31 million tons, and this was a greater decline than that logged for production of marketable iron ore and related products, which was down by only 3.0% or almost 28.2 million tons. Thus, it would seem that for another year there was a net addition to stocks. The 1991 drop in iron and steel scrap use was about 5.5 % or about 18 million tons, on the percentage basis somewhat greater than the 4.8% or 36.9 million ton drop in global steel production. Although consumption of iron ore and iron and steel scrap are not broken down by region in table 12, it seems almost assured that the pattern of 1990 continued into 1991: drops in use in the former U.S.S.R. and Eastern Europe were the overwhelmingly dominant declines and accounted for much, although not all, of the global decline, whereas among market economy countries as a group, there were upturns for both materials. On a global basis, it would appear that the slight shift in the ratio of pig iron to scrap in steel furnace charges noted in 1990 continued into 1991, this shift being toward a slightly larger proportion of pig iron with a corresponding decline in the share accounted for by scrap.

Jan 1, 1993

By L. C. IlsLey

The theory and practice followed by the Bureau of Mines in investigating electrical equipment4/ made for service in gassy mines are of particular interest not only to manufacturers but also to those organizations that deal with safety anal inspection at the mines. This publication purposes to discuss the theory upon which tests of equipment in explosive atmospheres are based and to consider inspection and other matters pertaining to investigations made by the Bureau in ascertaining whether a machine merits approval. The material in this report is taken from an earlier bulletin,5/ which is row out of print, and has been revised and brought up to date to make the information again available to manufacturers, inspectors, and others interested in the development of safe equipment.

Jan 1, 1954

By John A. Davis, John Gross

Six tests were made by the Alaska Station of the Bureau of Mines on a sample of black sand delivered to the station by Messrs. James, Eagan & Griffen from Fairbanks Creek, Fairbanks mining district, Territory of Alaska, to devise a method of recovering the gold content. More than 90 per cent of this black sand consisted of magnetite and garnet which can be separated magnetically. The Station has no equipment for magnetic separation other than an electromagnet similar to the one used by Day and Richards, (Day, D.T., and Richards, R.H., Investigations of Black Sands from Placer Mines, U. S. Geol. Survey, Bull. 285, 1906, pp. 150-163), which can only be used satisfactorily on small samples. To treat the entire lot of black sand with this machine would have been impracticable. Therefore only a small part of the sand was so treated, the rest being divided into five lots in order to obtain comparative results from other methods of treatment.

Aug 1, 1920

By R. L. Grant

An investigation was undertaken by the Bureau of Mines to determine the relationship between freespace and ignition probability for borehole shots. A series of experiments was concluded which covered six freespace conditions for a pemissible explosive in a 3/4-inch borehole and encompassed some 700 shots. The results were analyzed statistically. From the analysis of variance, it was concluded that the freespace means were different and that this conclusion is not impaired by possible differences in the explosives used. Within the limitation of this experiment, a definite relationship was found between the freespace and the ignition probability. Specifically, the incendivity increases with increased freespace up to a maximum; beyond this maximum there is some indication of decreasing incendivity. Further investigations are in progress to establish whether the effects of freespace on ignition probability reported here are applicable to the large test gallery, INTRODUCTION A borehole loaded with an explosive charge is a common feature of the routine gallery tests for determining the permissibility of coal-mine explosives, of Experimental Coal-Mine shots, and of the small steel cannon shots used in connection with certain research programs on the ignition of firedamp (6, 10).6/ The question of the interrelationship of freespace, weight of charge, and ignition probability of the methane-air atmosphere has been raised

Jan 1, 1959

By Terry L. Muldoon

The Bureau of Mines conducted an investigation to quantify microphone response variations that could result when the microphone is worn by a worker, as with a personal noise dosimeter, and to suggest an optimum placement and orientation of the microphone for noise exposure measurements. Previous studies have shown no significant variations in a diffuse field. This investigation, therefore, was conducted in the free-field conditions of an anechoic chamber using an anthropometric dummy as a subject, and broad band noise as the acoustic stimulus. This investigation established that, in a free field, the wearer's body does significantly affect microphone response; the response variations are a function of azimuth, and location and orientation of the microphone. Results suggest that locating the microphone on top of the subject's shoulder, oriented parallel to the body axis, should yield data comparable to that obtained using a sound-level meter.

Jan 1, 1973

By Jim F. Lemons

The Bureau of Mines Minerals Availability System collected and analyzed data for 34 nonlaterite and 9 nickeliferous laterite domestic chromite deposits in order to assess their viability as sources of chromium under present technologic and economic conditions. These 43 deposits, none currently in production, contain approximately 6.3 and 22.3 million metric tons of Cr203 at the demonstrated and identified resource levels, respectively. Approximately 4.6 and 15.6 million metric tons of Cr203 are recoverable at the demonstrated and identified levels, respectively, for the 34 nonlaterite deposits. None of these resources are economically recoverable at January 1981 market prices. Production of metallurgical-grade chromite (market price $128 to $144) would require a minimum chromite market price of $237 per metric ton. Chemical-grade chromite production (market price $74 to $85) would require a chromite market price in excess of $188 per metric ton. From the 34 nonlaterite deposits, roughly 5.4 and 17.6 million metric tons of ferrochrome could be produced at the demonstrated and identified resource levels, respectively; however, a minimum market price of $770 per metric ton of ferrochrome would be required to stimulate production. The nine nickeliferous laterite deposits were not evaluated through production stages because of uncertainties in process technology and cost.

Jan 1, 1982

By R. Agarwal

The in-situ stress field was determined, using the overcoring technique, at two underground sites at the Pea Ridge Mine, Sullivan, Missouri. At one of the sites in magnetite, the three dimensional stress field showed the largest principal stress to be compressive (-4564 psi), nearly horizontal and closely parallel to the strike of the orebody. The smallest principal stress was also compressive (-2047 psi) and nearly vertical. Considerable difficulty was experienced in drilling porphyry rock at the second test site in the host rock. Only one hole was drilled at this site. The secondary principal stresses obtained in the porphyry are -9464 and -4945 psi, respectively. The-test site in magnetite is located at a depth of 2505 feet whereas the site in porphyry rock is at 2475 feet. The vertical stresses: due to overburden loading at these sites are -3590 and -2782 psi, respectively. Field determined values of the vertical stress are -2207 and -5098 psi, respectively. The variance; between the two sets of values is most likely attributable to the orebody formation and the differences in the modulii of the host rock and the orebody.

Jan 1, 1977

By Samuel S. M. Chan

The objective of this project was to collect information applicable to the design of ground support systems in deep mines to include in-situ rock deformations, deformation-modulus, stresses, and geology and laboratory physical properties. All data collected was to be integrated and evaluated using a finite-elements computer code. In addition, considerable professional "cross pollenization" was anticipated from the association of University and SMRC personnel. Scope of Investigation Before a ground supporting system can be evaluated, the loading conditions existing in the region of investigation, strength, deformation characteristics, as well as other engineering properties of the rock structure immediately surrounding the openings, together with the pertinent geological information, must be obtained and analyzed. It was for this reason the following items were included in this research project: (1) The selection of a suitable area for the investigation. (2) The mapping of the important geological features of the area of investigation. (3) The measurement of in-situ deformation of rock masses immediately surrounding an underground opening of the area of investigation. (4) The determination of ground stresses. (5) The obtaining of in-situ modulus of deformation of the rock masses. (6) The testing of useful engineering properties of

Jan 1, 1972

By J. E. Tiffany, Z. C. Gaugler

An active list of permissible explosives was published in December 1943 as part of the Bureau of Mines Report of Investigations 3736 under the title "Active List of Permissible Explosives and Blasting Devices Approved Previous to June 30, 1943." This list included 180 brand names. Changes in the list that have been authorized to December 31, 1945, placed 10 additional brands of permissible explosives on the active permis- sible list as a result of tests and changes in brand names.. Twelve permis- sible explosives were transferred from the active. to the inactive list. The present list contains 178 brand names. The brand names of the permissible explosives placed on the active list are as follows: American 3-A By test. Apcol No. 1-B Do. Black Diamond No. 11-B DO. Black Diamond No. 55 DO. Coalite G-1 DO. Coelite K-1 Do. Do. Coalite L-1 Coalite IS-1 Columbia B-2 DO. By change in name. By test. Monobel AA The permissible explosives transferred from the active to the inactive list are as follows: Anthracite B, L. F. Big Red No. 8 Independent No. 1, L. F. Independent No. 2, L. F. Independent No. 3, L. F. Independent No. 4, L. F. Independent No. 5, L. F. Independent No. 9, L. F. Independent No. 9-C, L. F. Independent No. 10, L. F. Independent No. 11, L. F. King No. 9

Jul 1, 1946

By E. D. Gardner, Edmund Stein

"IntroductionMassive sulphides occurring in metal mines are inflammable and furnish the fuel for many mine fires. Actual sampling has shown that dangerous amounts of sulphur dioxide and hydrogen sulphide may occur in mine atmospheres after blasting in massive sulphides. Probably some .of the finer sulphide in the material being blasted burns while it is in contact with the flame from the explosion. It’s also possible that oxygen of the explosive enters into the reaction.That sulphide dusts are explosive under some conditions has long been suspected, but the theory has not been generally accepted as having been proved. Evidence now at hand appears to be conclusive that such explosions do occasionally occur in mine workings in massive sulphides. Information from several mines working in heavy sulphides shows that occasionally, sulphur dioxide in larger amounts than could be expected from the blasting alone are occasionally thrown out into the mine atmosphere during blasting. Accidents have occurred and lives have been lost by men being caught in such gases. Also it appears in a few cases that damage done to timber in stopes by concussions has been greater than could 112.ve been expected from the regular blasts. In most of these cases the unusually large amounts of Sulphur dioxide could only be accounted for by an explosion or by an ignition of sulphide dusts. When this occurs it is probable that the settled dust is stirred up by the first shot of a round, then the dust cloud is ignited by this or a succeeding shot.In one instance, the senior author, while wearing breathing apparatus, returned to a station to take a gas sample immediately after a raise round had been blasted, and encountered a heavy white fume or smoke that was corrosive to the skin and which forced a retreat. The sample, which was taken farther back in a greatly diluted atmosphere, showed a high percentage (0.18) of sulphur dioxide. The station and the raise which was just being started were very dry and the walls and floor of the station contained settled sulphide dust which apparently was ignited by the blast."

Mar 1, 1928

By H. D. Raymond

This report contains a summary of designs, specifications, costs, and schedules developed for a prototype oil-shale demonstration mining program to be undertaken at the Horse Draw site in the Piceance Creek Basin, Rio Blanco County, Colorado. The objective of the demonstration program is to assess the feasibility of extracting oil shale and associated saline minerals from deep, rich oil shale zones which occur within the central portion of the Basin. Four mining systems were specified for demonstration. These include (1) chamber and pillar mining with backfill; (2) sublevel stoping with backfill; (3) sublevel stoping with full subsidence; and (4) block caving. Commercial-scale designs for each system were modified and scaled down as required to achieve program objectives. The demonstration mine layout and design includes specifications for ore handling, backfilling, ventilation, dewatering, maintenance, and supply systems. A feature of particular interest in the design is the combination of block caving and sublevel stoping methods into a single unit for demonstration of subsidence mining systems in deep oil shale deposits. The report also contains a detailed breakdown of projected capital and operating costs for the demonstration mining program.

Jan 1, 1979

By J. M. Mutmansky, S. Padmanabhan

"The subject of quartz occurrences in respirable coal mine dusts has been of increasing concern in recent years. The primary impetus for this concern has been provided by better measurement technology that has detected an increased number of mines with high quartz content in their respirable dusts. This paper presents the results of statistical analyses of quartz levels in multi-stage impactor samples from eighteen different coal mining sections located in Pennsylvania, West Virginia, Ohio, Illinois, Kentucky, Colorado and Ucah. The quartz and kaolinite determinations were then determined by combining impactor stage loadings to provide larger dust masses and applying the infrared spectrometry procedure outlined in Bureau of Mines/MSHA Method P7.The results will be presented using two categories of data collected during two separate phases of the research:(l) quartz concentration data from mines where quartz was known to be present in relatively high concentrations, and(2) quartz concentration data from mines chosen at random.The aspects of the occurrence of quartz in coal mine airborne dusts that will be reported include the size dependence of the quartz content, quartz variations with location in the mining section, and variations due to mining region. The results of the study show a strong pattern of size dependence of the quartz content in mines for which high quartz concentrations exist. A similar, though less pronounced, pattern exists in mines chosen at random. Quartz levels appear to have a varying relationship to section location and strong geographical patterns do not appear to exist in the data collected. Kaolinite content was found to be similar to that of quartz with patterns that are somewhat more consistent."

Jan 1, 1989

By Paul S. Schopf

The results of an experimental investigation into the possible use of medium energy acoustic fields (130 to 140 dB) to precipitate 1 to 10 micron particles is presented. The aerosol was produced with a LeMer generator using oleic acid and nitrogen. The sound field was a sinusoidal standing wave field in an acrylic tube, with light transmission data used for concentration determination. The results showed collection efficiencies of up to 80% on 2 micron particles with a residence time of 11.8 seconds at a sound pressure level of 139 dB re 2x10-5 N/m2. A discussion of the possible turbulent mechanism is made, as well as review and comparison with others? work.

Jan 1, 1972

By R. D. Brown

There are techniques for separating aluminum alloys from mixed scrap, but there are no efficient ways to separate wrought aluminum from cast aluminum. This Bureau of Mines report describes a novel technique for separating mixed aluminum alloy scrap into cast and wrought aluminum alloy fractions. The technique, which uses conventional heating, fragmentizing, and screening equipment, exploits differences in the mechanical properties of cast and wrought aluminum alloys at elevated temperatures. The cast alloys become brittle at high temperatures owing to intergranular melting of regions of eutectic composition. This melting begins to occur as the solidus temperature for each alloy is reached. Solidus temperatures for casting alloys generally range from 520° to 580° C, but are above 600° C for most wrought alloys. Thus, the casting alloys are easily fragmented while the wrought alloys remain ductile in the proper temperature range. Starting with a mixture containing approximately 80 pct cast and 20 pct wrought alloys, fractions of 100 pct cast and 98 pct wrought have been produced.

Jan 1, 1985

By T. T. Campbell

Although secondary recovery of lead and lead-tin alloys has been common practice in the United States during recent years, there is little published in-formation concerning recovery techniques. Available information does not cover metal recovery from wet dross skimmings. This investigation by the Bureau of Mines was undertaken to develop techniques that would allow lead-tin alloys to be recovered from wet dross skimmings containing large amounts of zinc chloride. A process was developed, on a laboratory scale, for recovering lead-tin alloys from wet solder dross skimmings. Straight water leaching, either with or without a second leaching operation carried out with a Na2C03 addition for removing chloride, produced a dross that could be smelted without further treatment. Overall recoveries averaging 92 percent of the metal values in the dross were obtained in the form of lead-tin alloys, which had an average tin content of 16 percent and lead content of 84 percent. The recovered alloy contained less than 0.02 percent zinc, as determined by both chemical and spectrographic analyses.

Jan 1, 1956

By Wesley A. Grosh

The Vest nickel prospect, in Floyd County, Va., was discovered about 25 years ago. Limited exploration of the deposit had indicated some appreciable nickel mineralization in the sulfide ore. The property was examined on March 9, 1943, by an engineer of the Bureau of Mines in company with C. W. Vest, owner of the property. A limited exploration program was recommended. Two holes totaling 320 feet were diamond-drilled in January 1944. Drilling indicated the sulfides are sparsely disseminated. The only nickel values of interest were at the old prospect shaft.

Jan 1, 1949

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 Philip G. Freeman

The growth-promoting properties of coal-derived humus were tested by a variety of bioassay methods. Humate materials used included leonardite, a form of naturally oxidized lignite, and humic acids extracted from leonardite. It was found that the greatest effects were evident when water-soluble humic acid was applied to excised root tips. No significant short-term effect was noted when water-soluble humic acid was applied to stem or coleoptile sections. Root initiation was promoted in bean stems when high concentrations of coal-derived humate were applied. Gross weight of tomato plants was increased by up to 40 percent when coal-derived humates were added in concentrations of 101 to 104 ppm to the nutrient in a hydroponic growth test of 6 weeks' duration. It is concluded that coal-derived humate promotes the uptake of minerals, specifically iron, by serving as a metal chelate.

Jan 1, 1968

By Alla D. Mah

The heat of combustion of aluminum carbide (Al, C3 ) , obtained directly by combustion calorimetry , was AH298.15 -1,029.6 ± 1.9 kcal / mole . == The heat of formation of aluminum carbide corresponding to this value was AH298.15 = -53.4 ± 2.0 kcal /mole .

Jan 1, 1964

Mining officials, as well as members of the Bureau of Mines staff, in their efforts to make mining safer are confronted from time to time pith complicated problems concerning solution of which there is a diversity of opinion. To reduce these differences of opinion as much as possible and to obtain a generally acceptable decision on any mine-safety question, the Director of the U.S. Bureau of Mines established the Mine Safety Board on June 1, 1924- *** to consider questions arising within any divisions of the Bureau that require a definition of tie Bureaus s collective opinion as to safety practices, safety devices, or safety methods for underground operations or open-pit mining. The approved2/decisions shall form the basis of teaching and policy for the Bureau.

Jan 1, 1935