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By Joseph J. Wallace, Lloyd Williams, D. A. Reynolds, James J. Dowd, R. F. Abemethy

"SUMMARY AND CONCLUSIONS1. The investigation shows that the most important beds in Allegany County, from the standpoint of known recoverable reserves are: Lower Bakerstown, Upper Freeport, Upper Bakerstown, Upper Kittraing - less important beds are: Sewickley, Waynesburg, Pittsburgh, and Barton. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 tons per acre-foot of coal in place, are estimated to be 556 million short tons, as of January 1, 1951. Of this total, 304 million short tons is in beds 23 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics are too meager to permit making an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total eat ted reserves.3. Recoverable reserves of coal have been estimated in beds 28 inches and more thick. This thickness is about the minimum now being mined by hand-loading onto conveyors in the Appalachian region. The weighted average recovery for all beds in Allegany County, as determined by this investigation, is 49.8 percent. This percentage is based on the total thickness of coal (less partings 3/8 inch or more thick) in the bed rather than on the thickness of the coal mined. Based on the weighted average percent recovery for all beds in Allegany County, the recoverable reserves are estimated to be 152 million short tons as of January 1, 1951.4. The Allegany County coals are low-volatile bituminous in rank.5. The Allegany County coals are strongly coking."

May 1, 1953

By D. Harrington

"In order to stimulate general interest in mine safety among their employees the mining companies of Butte, Mont., instituted in 1918 a Miners' Field Day, and this field day has since been held annually about the end of July, the last one being on July 25, 1921. The mining companies of the Butte district finance this meet in proportion to the number of men employed at the time of the meet, the contributing companies with number of working force, end proportional contributions for the opening field day in 1918 being given below:COMPANY NUMBER EMPLOYED AMOUNT CONTRIBUTEDAnaconda Copper Mining Co.,12,500,$ 1,078.53Butte & Superior Mining Co.,1,800,155.32North Butte Mining Co.,,1,294,111.67East Butte Copper Co.,,850,73.36W. A. Clark Interests,,600,51.78Davis-Daly Mining Co.,,340,29.35,,,,17,384,$ 1,500.00*Note: In many mining districts it is now the custom to hold an annual Miners' Field Day. The field day, as a rule, is financed principally by the mine operators, and was instituted primarily to promote interest among miners in the ""Safety First"" movement. Usually demonstrations or contests in first aid and mine rescue are the leading feature of the day's events, which include games, races, dancing, and all the other amusements usual to a gala holiday. Thus the field (ley serves the double purpose of stimulating interest in mine safety and promoting cordial relations and community fellowship. This paper is an interesting account of the way in which the Miners' Field Day in the Butte district is organized, with data on costs, plan of organization, method of conducting, and the practical benefits derived from it. - Ed"

Oct 1, 1921

By J. C. Gerdeen

A new analytical model for the shear stiffness at a joint of the fully-grouted resin roofbolt is developed using the Theory of Elasticity and an analogy to a beam on an elastic foundation, Gerdeen [2]. The model developed in this study treats the elastic foundation modulus of the resin as being composed of both an elastic rock and an elastic resin. All previous attempts have neglected the elasticity of the rock and treated only the resin. A three dimensional finite element model of the bolt-resin-rock system is developed also and comparisons are made between the predictions made by it and the analytical solution. It is found that the agreement between the two representations ranges between 1.2% and 10.5%, with the greater differences being observed for systems of very large or very small bolt diameters and resin annulus thicknesses. Since such configurations are not the rule in practice parameter studies are performed using the analytical solution with the finite element solution being used as a check. For a 0.75 in. bolt, a resin annulus thickness of 0.1375 in., a resin with E = 7 x 105 psi and -1) = 0.210, and a rock of modulus E = 6.8 x 106 psi and V = 0.159 the shear stiffness is found to be 1.220 x 106 lb,/in, from the analytical solution and 1.245 x 106 lb,/in, from the finite element model. Applying the finite element model to the problem of the axial stiffness of the fully-grouted resin roofbolt a value of 6.002 x 106 lb./in. is obtained which proves to be at least 50% higher than any of the now existing analytical predictions.

Jan 1, 1976

By G. R. Hopkins

According to reports received by the Bureau of Mines, Department of Commerce, as of January 1, 1929 there were 413 completed refineries in the United States, with a total daily crude-oil capacity of 3,509,540 barrels. In addition, 14 refineries, with a potential capacity of 99,000 barrels, were being constructed. Of the completed refineries, 341, with a capacity of 3,325,890 barrels, or 95 per cent of the total capacity, were in operation; and 72, with a capacity of 183,650 barrels, or 5 per cent of the total, were shut down. The improved condition of the refining industry in 1928 was indicated in several ways; namely, in an increase in the total capacity of the completed plants, in the opening up of a few plants which were shut down during 1927, in a decrease in the number of plants dismantled, and in an increase in the number of plants under construction. The majority of the refiners have followed a steady expansion program commensurate in most cases with the increase in demand for petroleum products. Obsolete equipment has been dismantled and modern equipment has been installed, with the net result that the total capacity of the completed refineries in the United States has shown a steady increase since January 1, 1918, the date of the first Bureau of Mines survey. Between January 1, 1928, and January 1, 1929, the number of completed plants fell from 423 to 413, but their total capacity increase 259,160 barrels, or 8 per cent. This compares with an increase in runs to stills of domestic and foreign crude petroleum of 10 per cent, and of domestic crude alone of 7 per cent.

Jan 1, 1929

By W. A. McKinney

Bureau of Mines Research has demonstrated that it is technically feasible to segregate oxidized copper ores by use of a direct-fired, refractory-lined rotary kiln. Previously, the segregation process had been effected only in much more complicated indirect-fired, stainless steel kilns, The method comprises heating crushed ore premixed with small quantities of salt and carbonaceous material, such as coke, to about 830° C to produce copper as fine flake and metallic films on the surface of the coke particles. After grinding of the cooled furnace calcines, the copper is recovered by conventional flotation. During direct-fired segregation it was necessary to closely control the air-gas mixture in the burner. Good copper recoveries were obtained only when adding air in the limited range of 1.15 to 1.2 times the theoretical amount required for combustion of the natural gas. Batch trials of the new technique on quartzite-, limestone-, sandstone-, and limonite-type oxidized copper ores containing from 1.4 to 6.2 percent copper yielded flotation concentrates containing from 3.7 to 45 percent copper, representing 84 to 95 percent recoveries. Analyses of the furnace gases showed that loss of copper by volatilization was negligible. The preliminary direct-firing segregation studies were complemented by continuous runs on the quartzite ore, containing 1.4 percent copper, in an integrated segregation-flotation pilot plant having a 60 pound-per-hour capacity. In a typical test, 84 percent of the copper was recovered in a cleaner flotation product containing 25 percent copper. The study will be continued to further delineate the conditions for good segregation as effective use of standard ceramic-lined kilns will render the process more attractive from a commercial standpoint.

Jan 1, 1963

By Frank D. Lamb

"INTRODUCTION The use of beryllium and its alloys has come into prominence in the last 15 years and increased considerably during the war. In contrast to other light metals, such as aluminum and magnesium, beryllium is relatively hard, has a high melting point (1,285° C.), and other properties that make it resemble steel in many respects. It has a specific gravity of 1.85, is only slightly heavier than magnesium (specific gravity 1.74), and is appreciably lighter than aluminum (specific gravity 2.7). Its lack of ductility prevents its use as a structural material, but this difficulty may be overcome in the future by the use of various alloy forms. The only important commercial alloy in which beryllium is used today is with copper. The addition of small percentages (1/2 to 2 percent) of beryllium to copper imparts properties to the alloy that make it desirable for use in springs carrying electrical current, particularly at high temperature. Many other uses of berylliam are known, and new uses are being found constantly that make the metal of increasing interest.Possibly the main factor preventing the use of more beryllium is the lack of a large source of beryllium ore. Many beryllium minerals are found as minor constituents of natural deposits, some of the more common ones being beryl (Be3Al2(Si03)6), chrysoheryl (Be A1204), helvite (3(Mn, Fe) Be Si04. MnS), and phenacite (Be2Si04). Of the known beryllium minerals, beryl is by far the most common and has been found distributed rather widely throughout the world. It usually occurs associated with granitic rocks and is commonly found as a constituent of granitic pegmatite."

Mar 1, 1947

By J. T. McCartney

Thin sections of coal have been prepared for many years either by cutting on a microtome (1,2)5 or by grinding and polishing (2,1). Specimens of most coals had to be demineralized in hydrofluoric acid and softened in caustic solutions before they could be successfully cut with a conventional microtome. Some lignites could be cut without pretreatment. Jeffrey (1) obtained sections from coals of all ranks, although long and tedious pretreatment was required for anthracite. His sections were less than 1 cm.2 in area (probably much less for high rank coals) and about 5 microns thick. Thiessen (2) also cut sections of softened coals, mostly of low rank. His sections were a few square millimeters in area and about 3 microns thick. However, Thiessen preferred ground and polished sections for detailed studies because they were larger and had not been chemically attacked by softening media. He prepared ground sections as large as 4 cm.2 in area and usually 5 to 10 microns thick. Thousands of such sections, covering complete column samples of many coal beds, were studied for a number of years (4). With the development of the electron microscope and increased interest in quantitative optical studies of coals, a need for much thinner sections arose. However, no suitable technique for preparing such sections was known until Fernández-Morán developed a diamond knife for cutting ultrathin sections of hard materials (5). Workers at the Centre d'Etudes et Recherches de Charbonnages de France applied this new tool to the cutting of coal sections and have recently described their technique to the Burg, of Mines. Using their methods, with some modifications, researchers of the Bureau of Mines have succeeded in cutting ultrathin sections of coals ranging in rank from lignite to

Jan 1, 1961

By E. J. Ostrowski, P. L. Woolf, J. P. Morris, Norwood B. Melcher

By injecting natural gas through auxiliary tuyeres into the smelting zone of the Bureau of Mines ' experimental blast furnace in January 1959 , the investigators succeeded in reducing the coke consumption by approximately one - third that of the base period . This caused a 30 - percent increase in pig iron production with no increase in wind rate . The maximum gas addition in these experiments was 4,665 cubic feet per ton of metal produced . Sharp reduction in gas consumption occurred when high hot blast and high wind rates were used , although the gas injection rate in percent of air blown remained constant . As the heat energy produced by burning natural gas to carbon monoxide and hydrogen is much less than burning coke to carbon monoxide , greater blast temperatures were required during the test runs . The gases produced from the methane were , however , more effective reductants ; so it was possible to increase the production rate while reducing the total heat requirements per ton of metal produced . During a base period with an all - sinter burden , before introduction of natural gas , a coke rate of 1,484 pounds per net ton of pig iron was attained , using an average blast temperature of 1,518 ° F. Gas was introduced gradually over a two -week period until an average 7 percent of the air blown was reached . During this period , the wind rate was adjusted downward to maintain a constant flow of gas in the bosh . The production rate of the furnace remained relatively constant . The quality of pig iron, however , improved as the sulfur load on the furnace was reduced as a result of the substitution of gas for coke . Blast temperatures were increased during this period from 1,518 ° F. to 1,939 ° F. , when the maximum gas addition was reached .

Jul 1, 1960

By D. N. Nilsen

The Bureau of Mines is developing a method to recover Ni, Co, and Cu from laterites containing less than 1.2 pct Ni and 0.25 pct Co. The method consists of the following basic unit operations: (1) reduction roasting, (2) leaching, (3) solvent extraction, and (4) electrowinning. The method reflects three Bureau of Mines objectives: (1) recovery of critical minerals that are domestically in short supply from low-grade domestic laterites, (2) lower processing energy requirements, and (3) solution recycling. This report deals with the extraction of cobalt and the preparation of a suitable cobalt electrolyte by solvent extraction from liquor produced by this method. Nickel and copper are coextracted with LIX64N from an ammoniacal ammonium sulfate leach liquor containing about 1.00 g/l Ni, 0.30 g/l Co, 0.03 g/l Cu, and 0.02 g/l Zn. Cobalt (III) in the nickel-copper barren raffinate is reduced to cobalt (II) with cobalt metal. Reduction of cobalt (III) to cobalt (II) greatly aids subsequent extraction. Commercially available XI-51 extracts about 94 pct of the cobalt from the treated raffinate in one stage in a laboratory mixer-settler continuous circuit. Ammonia loaded on the solvent is removed in two washing steps. About 94 pct of the cobalt then is stripped from the XI-51 in one stage with spent cobalt electrolyte containing about 77 g/l Co and 18 g/l sulfuric acid (H2S04), Electrolytes containing less H2S04 also may be used. Preliminary data indicate that coextracted zinc may be removed from pregnant cobalt eletrolyte containing 3 g/l or less H2S04 with di-(2 ethylhexyl) phosphoric acid (D2EHPA).

Jan 1, 1980

INTRODUCTION The pager phones used in many underground coal mines are battery- operated, party-line telephones with provisions for loudspeaker paging. The system is two-wire, non-polarized, and is operated by self-contained batteries. Many of the individual units are certified as permissible. Requirements for installation are specified in state and federal regulations, such as in the Code of Federal Regulations, Title 30, Mineral Resources, Part 75. The major federal regulations that affect communication in coal mines are noted below, with a brief description of the subject matter in each of the relevant paragraphs. Refer to the cited paragraphs of Title 30 for explicit details of these regulations. (This brief description is for reference purposes only.) Minimum Requirements (paragraphs 75.1600, 75.17 13-2, and 75.1003-1) Approved telephone or two-way communication will be provided between the surface and each main shaft landing and each working section ; to the nearest medical assistance; and shall be protected from contact with trolley wires or trolley feeder wires. Installation Requirements (paragraphs 75.5 16-2, 75.52 1, and 77.508-1 ) Communication wires will be supported on insulated hangers, attached to messenger cables, or buried, to protect against mechanical damage ; installed opposite trolley wires; and insulated near power conductors . . . each cable will have lightning arresters within 100 feet of going below ground . . . and arresters will be provided wherever telephone wires enter a building. Wire and Cable Requirements (paragraphs 75.5 16-2, 75.5 17, and 75.52 1) Communication cable means two or more insulated conductors, covered by an additional abrasion-resistant covering; power wires and cables shall be adequately insulated and fully protected; and lightning arresters shall be connected to low-resistance grounds, more than 25 feet from neutral grounds.

Apr 1, 1975

By D. W. Bridges, R. O. Dannenberg, Laird Crocker

Preliminary solvent extraction studies , reported by the Bureau of Mines (5) , have been continued and expanded to improve on the previous estimate of process requirements . The solvent extraction portion of the process was examined at a scale large enough to enable meaningful extrapolation of the results to geometrically similar equipment of plant size . About 82 pct of the beryllium was recovered from approximately 0.5 pct beryllium oxide (Be0) Spor Mountain , Utah , ore by a process involving ( 1 ) sulfuric acid leaching , ( 2 ) counter current decantation (CCD ) washing , (3 ) iron ( III) reduction by sodium hydrosulfide ( NaHS ) , ( 4 ) beryllium solvent extraction by di - 2- ethylhexyl phosphoric acid ( EHPA) , ( 5 ) caustic stripping of beryllium- bearing EHPA, (6 ) hydrolysis of sodium beryllate - caustic strip liquor , and (7 ) calcination of beryllium hydroxide (Be ( OH ) 2 ) formed in step (6 ) . The resulting beryllia assayed 98 to 99 pct Be0 and was suitable for most nonnuclear uses . Best overall results were obtained by using pH 2 , 1.6 grams of BeO per liter of leach liquor as feed and 0.25 N EHPA in kerosine containing 2 wt vol pct (grams per 100 ml of solution ) isodecanol ( IDA ) as solvent . Analysis of the data indicated that a commercial plant would achieve 95- pct overall extraction operating at 45 ° C with 20 hp per 1,000 gal of dispersion in each of seven mixer- settlers , having 290 gal per ton of ore hourly mixer capacity and 90 gal per ton of ore hourly settler capacity . At least 79 lb H2SO4 , 13 lb sodium hydroxide (NaOH ) , 3 lb NaHS , 0.25 lb kerosine , 0.07 lb polyacrylic flocculant , 0.03 lb EHPA , and 0.007 lb IDA would be required in H2SO4 leaching and subsequent processing to recover 1 lb BeO .

Jan 1, 1964

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

1. Introduction This document represents Part II of our final report on the development of a "Remote Sealing System for Extinguishing Coal Mine Fires. " It is a technical report which summarizes the results of system development and field demonstration. Part I of this two - part final report is an Operator's Manual for the application of the Remote Sealing System to a coal mine fire. 1.1 Background When coal mine fires go out of control and can no longer be fought directly, the standard fire fighting technique is to construct air-tight seals in the mine passages leading to the fire area so'--,that the oxygen supply to the fire is". cut off. Ultimately, it is desirable to isolate the fire zone in such a way that normal operations can resume in the remainder of the mine. The construction of seals in the- mine causes the atmosphere to pass through a toxic and explosive phase. Explosions, if they occur, are not only hazardous to the men working at the sealing operation, but can also undo much of the sealing work which has already been accomplished. Sealing of passageways surrounding the fire zone from within the mine is extremely difficult and dangerous. Methods for direct sealing are detailed in "Control of Mine Fires'. 1 An alternative to this approach is the technique of remote sealing. This involves drilling boreholes which intersect the mine passages at the locations where the desired seals are to be constructed. The seals are then constructed by pouring material down the borehole and filling a segment of the passage from bottom to top. During this operation, there are no personnel in the mine, all operations taking place on the ground surface.

Jan 1, 1973

By Roy H. Grau, John C. LaScola

"This Bureau of Mines report contains a tabulation of methane emissions during 1980 for all coal mines located in the United States with emissions greater than 0.1 MMcfd. Listed for each mine are methane emission quantity, location, and coalbed. The report also compares records of 1975 and 1980 and describes relationships between emissions in 1980 and the Bureau's coalbed gas content data on 11 mines.INTRODUCTIONMethane gas is a threat to safety in underground coal mines. Research by Government and industry has led to great gains in reducing methane gas ignitions and explosions. The development of advanced methane control techniques is necessary for the safe operation of more gassy mines and the implementation of rapid mining techniques.As part of this research, the Bureau of Mines has surveyed total methane emission data from underground bituminous coal mines in the United States and tabulated emissions from mines producing over 0.1 MMcfd of methane. This report is an update of similar studies previously described in Information Circulars 8733, 8659, and 8558 (2-4).3The data from 1980 were compiled from Mine Safety and Health Administration (MSHA) records of air quality-quantity inspections made quarterly at each mine. The inspections involve measuring airflow and collecting air samples in the main returns. From these data, an average methane emission is calculated and used to represent the daily mine emission for each quarter. The methane emissions given in this report are the averages of the four 1980 quarters and do not include mine emissions from other sources such as degasification projects. Since a previous Bureau study showed that emissions from mines emitting less than 0.1 MMcfd represented only 2 pct of all emissions, 0.1 MMcfd was chosen as a lower limit for data collection (4)."

Jan 1, 1982

By Maria I. De Rosa

Table 28 and figure 10 show the number of fires and fire injuries for coal preparation plants by state during 1990-1999. Table 28 also shows the risk rates, employees' working hours, and lost workdays by state. For coal preparation plants, 91 fires occurred in 1 1 states during 1990- 1999. Twenty-three of those fires caused 25 injuries (the yearly average was 9.1 fires and 2.5 injuries). Ten fires and eight injuries involved contractors. The Ewhr value was 24 1 x 10' hr (Irr = 0.02 l), and the LWD value was 198. Pennsylvania had the most fires (24 fires and 4 injuries), whereas West Virginia (22 fires and 7 injuries) and Kentucky (22 fires and 7 injuries) had the most fire injuries. Among these states, Kentucky had the highest injury risk rate value (Irr = 0.025). Table 29, partly illustrated in figure 11, shows the number of fires, fire injuries, risk rates, employees' working hours, and lost workdays by time period. The number of fires decreased during most of the periods (an increase is seen only during the last period). The number of fire injuries show a decrease followed by an increase during the periods, accompanied by a decline in employees' working hours throughout the periods. The Irr values follow patterns similar to those shown by the injury values (see table 29 and figure 11). Tables 30-35 show the number of fires by ignition source, method of detection and suppression, equipment involved, location, and burning material by time period. Figure 12 shows the major variables during 1990-1999. Table 36 shows the fire injuries per number of fires causing injuries and total fires by year, ignition source, equipment involved, and location.

Jan 1, 2004

Table 1.-Salient aluminum statistics (Thousand short tons and thousand dollars) [ ]

Jan 1, 1967

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 Lloyd A. Morley, Alan M. Christman

1. Anonymous. "Getting Down to Earth," booklet 25T, James G. Biddle Co, Plymouth Meeting, Pa. (1970) pp. 1-48. 2. Anonymous. "Megger Ground Tester, Special Instructions," booklet 25-J-1, James G. Biddle Co, Plymouth Meeting, Pa. (1961) pp. 1-16. 3. AIEE Committee. "Application Guide on Methods of Substation Ground¬ing," AIEE Transactions on Power Apparatus and Systems (April 1954) pp. 271-277. 4. AIEE Committee. "Voltage Gradients Through the Ground Under Fault Conditions," AIEE Transactions on Power Apparatus and Systems (October 1958) pp. 669-692. 5. American Standards Association. "American Standard Safety Rules for Installing and Using Electrical Equipment in and about Coal Mines," U. S. Bureau of Mines Information Circular 8227 (1964). 6. Armstrong, H. R. "Grounding Electrode Characteristics from Model Tests," AIEE Transactions on Power Apparatus and Systems (December 1953) pp. 1301-1306. 7. Beck, Edward. Lightning Protection for Electric Systems, McGraw¬Hill, New York (1954) pp. 281-295. 8. Bellaschi, P. L. "Impulse and 60 Cycle Characteristics of Driven Grounds," AIEE Transactions (March 1941) pp. 123-128. 9. Bellaschi, P. L. "Lightning Strokes in Field and Laboratory," Elec¬trical Engineering, Vol. 58 (November 1939) pp. 466-468. 10. Bellaschi, P. L., Armington, R. E., and Snowden, A. E. "Impulse and 60 Cycle Characteristics of Driven Grounds-II," AIEE Tran¬sactions (1942) pp. 349-363. 11. Bewley, L. V. "Theory and Tests of the Counterpoise," AIEE Transac¬tions (August 1934) pp. 1163-1172. 12. Brereton, D. S. and Hickok, H. N. "System Neutral Grounding for Chemical Plant Power Systems," AIEE Transactions on Applica¬tions and Industry (November 1955) p. 315. 13. Bruce, C. E. R. and Golde, R. H. "The Lightning Discharge," Journal of the Institute of Electrical Engineers, London, Vol. 88 (December 1941) pp. 487-505.

Jan 1, 1976

By Charles L. Kimbell

The estimated value of world crude mineral production in 1989 was nearly $1,420 billion in terms of current dollars or more than $1,168 billion in terms of constant 1983 dollars. This latter figure was almost 4.7% above the 1988 level but did not attain the historic high of $1,207.1 billion 1983 dollars set in 1980. The accompanying tabulation provides the latest available revised time series for the value of world crude mineral production in terms of both constant 1983 dollars and current dollars. It also provides one of the two statistical bases for the estimation, this being the data on the value of production of a group of key commodities that was compiled for and published in the authoritative French language mineral industry periodical Annales des Mines for years up to 1983.l It should be stressed that the values just discussed and those presented in the tabulation are for crude minerals only and by no means reflect adequately the role of the entire mineral industry in the world economy. These figures represent only the value of mineral materials as they are mined or otherwise extracted from the earth. They do not reflect the value added to these materials through downstream processing within the facilities commonly accepted as mineral industry plants. That is, value added through beneficiation of ores, smelting, refining, and similar processing is not included in these figures. Comprehensive world data on the value added by such processing are not available; however, a conservative estimate of [ ] the total value of processed output from mineral industry plants derived wholly from primary (newly mined) materials would be on the order of about $2,800 billion constant 1983 dollars or $3,400 billion in terms of 1989 dollars.

Jan 1, 1992

By Lloyd A. Morley, Robert Stefanko

1 Abaibanel, S , "Deflection of Confining Walls by Explosive Loads," Israel Jour. Technology, vol. 4, n. 1, Feb 1966. 2 Albertoni, S and others, "Numerical Computation Methods for Implosion Processes," EURATOM Proc. of the Conf. on Megagauss Magnetic Field Generation by Explosives and Related Experiments, Milan (Italy), July, 1966. 3 Alexander, S. J , and Hambly, E. C., "Design of Structures to Withstand Gaseous Explosions," Concrete, vol. 4, n 2, Feb. and March, 1970. 4 Anonymous (Belgium Institute of Extractive Industries), "Report for 1968 (covering approved equipment for Belgiums gassy coal mines)," (in French and Flemish), Amales des Mines de Belgigue, n. 6, June, 1969. 5. Anonymous (Ghent Univ., Belgium), "The Welding of Very Thick Steels. Margin of Uncertainty of the Robertson Test," EURATOM Contract 042-61-9-RDB, May 20, 1965. 6. Anonymous, "Inportance of the Nature and Size of Weld Defects with Regard to the Mechanical Strength of Pressure Vessels, (in Flemish), A. Sys. Rev. Soudure, vol. 27, n. 3, 1971. 7. Anonymous (Raentgen Technische Dienst N V., Rotterdam), "Non¬Destructive Welding," Quarterly Report No 13, EURAEC - 1342, March 30, 1965. 8. Anonymous (Staff, USBM Safety Research Center), "Research and Technologic Work on Explosives, Explosions, and Flames: Fiscal year 1969," USBM IC8492, 1970. 9. Anonymous, "Symposium on Flameproofing Intrinsic Safety and Other Safeguards in Electrical Instrument Practice, April 27, 1962," IEEE Conf. Report Ser. 3, 1963. 10. Anonymous, "Unfired Pressure Vessels," ASME Pressure Vessel Code, Sec. 8, 1965. 11. Anonymous, "Unusual Pressure Relief Devices," Industrial and Engineering Chemistry, vol 54, n. 1, Jan., 1962. 12. Archer, G. L., "Design to Avoid Brittle Fracture in Welded Structures," Paper No. 4, Improving Welded Prod Design, vol. 1, Welding Inst., Cambridge, England, 1971. 13. Bailey, F. C., "Buckling and Failure Strength of Plating Panels Loaded in Shear," Final Report NASA Contract NObs-72290, Lessels and Assoc., Inc., Waltham, Mass., Sept. 20, 1963.

Jan 1, 1974

By William W. Adams

Reports for the calendar year 1923 that have been transmitted to the Bureau of Mines of the Department of the Interior by mine officials of the various coal-producing States show that accidents in and around the coal mines resulted in the death of 2,452 men. The output of coal during the year, as reported to the United States Geo- logical Survey, was 641,476,000 tons; hence the fatality rate per million tons was 3.82 as compared with 4.15 for 1922, a decline of about 8 per cent. The average rate for the decade ending with 1922 was 4.11. This reduction of 8 per cent in the fatal-accident rate per million tons is equivalent to the saving of 210 lives--that is, had the fatality rate of 1922 continued through 1923 the number of lives lost would have been 210 more than they actually were. Not only was there a net reduction in the fatality rate from all causes combined, but each of the main causes of coal-mine fatalities also showed a decline. Falls of roof and coal, which generally account for nearly half of all deaths in coal mines, were responsible for 1,158 fatalities in 1923, which represents a rate of 1.81 per million tons as compared with 1.90 in 1922. (See Table 2.) Haulage accidents underground usually cause about 17 per cent of all fatalities, and the reports for 1923 show that 413 deaths were due to this cause, indi- cating a rate of 0.64 per million tons, as against 0.71 for the previous year. Gas and dust explosions killed 372 men, the fatality rate being 0.58; the rate for 1922 was 0.65. Seventy-five deaths were due to electricity, for which class of accidents the fatality rate per million tons was 0.12 as compared with 0.16 the year before. Powder and other explosives caused 114 deaths, representing a rate of 0.18 as compared with 0.19 for 1922. Of the 2,452 fatal accidents during the year, 2,249 occurred under- ground, 46 in shafts, and 157 on the surface. At bituminous coal mines the number of deaths was 1,943, of which 1,816 were under- ground, 31 in shafts, and 96 on the surface. At the anthracite mines

Jan 1, 1923