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By A. D. Garman

This paper presents one of a series of digests of foreign mining leg- islation and court decisions which is being repared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countrics. This interpretation of the laws of Panama has been prepared from the best available information in Washington, but is released subject to correction and amplification, if necessary, by the proper American diplomatic and consular officers to who it is being referr ed through the courtesy of the Department of State.

Apr 1, 1930

By G. M. Kintz, E. H. Denny

Although some engineering colleges recognize the importance of instructing young engineers in industrial safety , the different institutions handle this instruction in various ways . It is believed that a recent industrial safety course , conducted at the Colorado School of Mines through the cooperation of this school and the Bureau of Mines , U. S. Department of Commerce , presents some unusual features that are of interest to other schools and to the mining public .

Sep 1, 1930

By Jr. Hardy, H. Warren Shen

"A study is presently underway by the authors to investigate the character of the bit-coal interaction during coal cutting and its influence on the size and shape distributions of the generated dust. An important aspect of this on-going project is the development of acoustic emission (AE) criteria which would make it possible to carry out remote monitoring of coal cutting operations. The on-going AE studies are fundamental in form and were undertaken to evaluate the general feasibility of AE monitoring techniques using simplified coal breakage and cutting procedures. The present paper will focus on the test facilities, experimental techniques, and results associated with linear, single-bit cutting. An AE-transducer, attached directly to the bit, detected AE signals during the cutting process.Experiments have been carried out on seven specimens of coal obtained from the USBM experimental mine at Bruceton, Pennsylvania. Three separate cuts were made for each of two bit angles (10 and 45 degrees) and two bit velocities (0.085 and 0.169 cm/sec), for a total of 12 separate cuts. Data associated with resulting particle size distribution and AE characteristics (major dominant frequency components) will be discussed. Data analysis has also been underway using a computer-based pattern recognition system known as ICEPAK (Intelligent Classifier Engineering Package). This program is able to evaluate over 100 features of an AE event and to make objective comparisons between AE signals associated with different loading or cutting parameters. The results to date show that AE generated during some of the test conditions can be recognized by ICEPAK with a recognition rate of 90% and higher while other conditions cannot at present be separated with a suitable recognition rate. Further analysis of the experimental data is presently underway.The reduction of the severity, and eventual elimination, of Coal Workers' Pneumoconiosis (CWP) depends on gaining fundamental understanding in a number of major areas. These include dust generation and entrainment, transportation, suppression, medical effects of dust, and possible treatment. At present a project is underway by the authors to investigate the character of the bit-coal interaction during coal cutting and its influence on the size and shape distributions of the generated dust. An important aspect of this on-going project is the development of acoustic emission (AE) criteria which would make it possible to carry out remote monitoring of coal cutting operations. Suitable on-line analysis of monitored AE data would allow engineers to evaluate factors such as shearer bit conditions and cutting efficiency, and to quantify the particle size and shape distribution of the generateddust. The on-going AE studies are fundamental in form and were undertaken to evaluate the general feasibility of AE monitoring techniques using simplified coal cutting procedures. To date experiments have been carried out on coal under uniaxial compression, linear single-bit cutting, and cutting using a laboratory-scale, single-bit shearer. A brief outline of the overall study has been presented in an earlier paper (Hardy, Shen and Kimble, 1995). This paper will consider the linear single-bit cutting studies in more detail.It is generally accepted today that most solids emit low-level seismic signals when they are stressed or deformed. In this paper this phenomenon will be referred to as acoustic emission (Hardy 1972, 1981, 1989). In essence, the measurement of AE activity in a field or laboratory structure is relatively simple. A suitable transducer is attached to the structure, the output of the transducer is connected to an associated monitoring system, and the AE signals occurring in the structure, due to internal or external stress, deformation, and failure are suitably acquired, pre¬processed and recorded."

Jan 1, 1998

This manual is for use by mine operating personnel and vehicle manufacturers in the selection and proper use of automatic fire protection systems for underground metal and non-metal mining vehicles. Most of the currently available systems are manually operated, dry chemical fire suppression systems. When properly designed, installed, and maintained these systems have proven to be effective both in fire suppression and in withstanding the rugged mine environment. Portable fire extinguishers and manually actuated systems have provided adequate protection for most of the reported fire incidents. However, there have also been incidents where injuries and property losses would not have occurred if the vehicle had been protected with an automatic fire protection system. The need for reliable automatic systems exists when the operator is not present, especially when the vehicle engine is running without the operator in the cab; and also in cases where the operator leaves the vehicle to fight a small fire with a portable and is then forced to abandon the vehicle because the small fire becomes uncontrollable. In the later cases manual systems on the vehicle are never actuated. Although these incidents have been relatively few in number in the past, the increasing use of mobile diesel powered equipment and the related importance of personnel safety, high costs of the mining vehicles, and high cost of down time warrant consideration of automatic fire protection systems. The fire history data and the design concept discussed in this manual were developed under the Bureau of Mines Contract H0252038 which is part of the government's mining research safety program. The purpose of the contract was to develop a low cost, reliable, prototype automatic fire control system for underground vehicles. The industry needs were determined through an extensive mine visitation program, and the prototype system was demonstrated on a vehicle in an underground mine fire test. The system developed under this contract was specifically designed for a load-haul-dump. However, the design concept is applicable to the full general class of mobile underground mining equipment.

Jan 1, 2011

By A. D. Garman

This paper presents one of a series of digests of foreign mining legislation and court decisions which is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries . This interpretation of the laws of El Salvador has been prepared from the best available information in Washington , but is released subject to correction and amplification , if necessary , by the proper American diplomatic and consular officers to whom it is being referred through the courtesy of the Department of State . Under the terms of the Code of Commerce ( arts . 12ff . ) , foreigners living in El Salvador can engage in business on the same terms as nationals . This involves ( = $434.00 ) - except for those with a working capital , of less than a thousand pesos inscription in the merchants ' register , which can be refused only in case of manifest disability of a permanent nature .

Sep 1, 1930

By F. S. Crawford

Safety devices and guards are often looked upon as the last word in safety by the men around the shop or large industrial plant . However , thorough knowledge of the details of their jobs and of the dangers attending them are even more important . It should be unnecessary for all men to go through the experience of the first man to meet an unknown danger , but that appears to be about the only way by which many learn . Practically every danger connected with the job around a mine , blast furnace , steel mill , foundry , coke oven , cement mill , or other operation , was encountered for the first time by someone , and if he was fairly fortunate he either got hurt or just missed being injured and lived to tell his " budaies " how it happened; he spread the knowledge of that particular danger . Sometimes , but not often , a man can foresee a danger . If he could always be on guard and remember everything he had ever learned and also know everything that had happened to the other fellow , and then let that knowledge keep him aware of the dangers in his own immediate " job , " so that he would work the safe way for both himself and the other fellow , he would have what safety engineers call " safety consciousness . " Being safety conscious is a fine attribute , as it really means knowing all about one's job . A man who is really safety conscious is one of the best and most efficient workmen in the whole plant . The boss wants men of that kindmen who want to learn and who try to learn every little detail about their jobwhere there is danger of spoiling the heat or getting burned by hot metal in a steel plant or of loading rock instead of coal or ore in a mine . Such men know how to do whatever job they are on easily and with the least amount of hard work and at the same time get it done as quickly as possible with safety . A man who is safety conscious has to nearly all intents and purposes developed eyes in the back of his head , if he is in a big mill where there if something going on all around him . These eyes are not real eyes , but they are what might be termed a sixth sense which he has developed by his experience in the mill as well as in other dangerous work which he may have done before in other plants . There may be occasions when a man's safety consciousness will leave him for just a short time ; this is likely to happen when he is thinking about a quarrel he had with his wife which has not been cleared up happily , or perhaps when he has bought too many things on installment and with sickness at home

Apr 1, 1931

By J. J. Demeter

A tube-wall reactor with a Raney nickel catalyst deposited on the outer wall of the tube by flame spraying is effective in the practically complete conversion of 3H2+1CO synthesis gas to a high-Btu gas (methane) at an hourly space velocity of 7,000 volumes of gas (NTP) per hour per volume of annular volume. Partially reacted synthesis gas containing an appreciable amount of methane can also be treated in this reactor to increase the heating value to over 900 Btu per cubic foot. Excellent heat removal through the metal wall to a coolant and temperature control were obtained. The heat transfer co-efficient from the catalyst to the coolant was about 275 Btu per hour per square foot per ° F. Synthesis tests were conducted with tubes 1.2 inches in ad by 6 inches long, and 1.3 inches in od by 36 inches long. When operating at a synthesis gas rate of 100 to 120 scfh per square foot of catalyst-coated tube, catalyst life was long enough to realize a catalyst cost for the raw Raney nickel alloy of about 0.3 cent per 1,000 cubic feet of pipeline gas (900 to 950 Btu per scf). Gas recycling at ratios of 1:1 to 3:1 was effective in increasing conversion and in extending the life of the catalyst to about 16 weeks. In cost and in operating characteristics the tube-wall reactor compares favorably with the fluidized-bed and hot-gas-recycle reactor systems for the synthesis of high-Btu gas from H2+CO.

Jan 1, 1967

By Thomas W. Martin

This chapter includes tables from 1984 that were not available in time for publication of the 1984 Minerals Yearbook, but does not include corresponding tables for 1985. The value of raw nonfuel minerals produced in the United States during 1985 was estimated at $23.2 billion, an increase of $0.07 billion over the value for 1984. This is the third consecutive year that the value has increased, and except for a decrease in 1982, the value for each year has increased since 1971, or 13 out of 14 years. However. while the value of industrial minerals production continued to grow, reflecting the growth of the domestic economy, the value of metal mine production decreased in 1985 by 6%. This drop was more than offset by a 3% increase in the value of industrial minerals production because the value of industrial minerals produced was more than three times larger than the value of metals. The decrease makes 1986 the third year in the past 5 years in which a drop in the value of metal mining production occurred in the United States where production continued to lag behind growing world production. Domestic production of such major commodities 88 aluminum, copper, iron ore, phosphate rock, and zinc continued to decline owing to a number of international and domestic factors. Gold continued to be the most active commodity in the domestic metal mining industry. Despite lower prices, gold output increased to 2.5 million troy ounces, a 19% increase over that of 1984. The estimated annual production capacity of new gold mines beginning production exceeded 1 million ounces.

Jan 1, 1987

By Joan C. Biordi

In this research by the Bureau of Mines, slightly lean CH4-O2-Ar flames at 0.042 atm with and without small amounts of the inhibitor CF3Br were probed using molecular beam and mass spectrometric techniques. Ratios of product concentrations to reactant concentrations were formed and compared with the equilibrium constant for seven reactions--(l) H+O2 = OH+O, (2) O+H2 = OH+H, (3) OH+H2 = H2O+H, (4) OH+OH = H2O+O, (5) CO+OH = CO2+H, (6) Br+HBr = Br2+H, and (7) H+HBr =H2+Br--to determine to what extent they may be considered balanced in various regions of the flame. With the possible exception of reaction 4, none of the reactions are completely balanced until maximum flame temperature is reached. Once the reactions become equilibrated, their balance is maintained as the temperature and radical concentrations falloff in the secondary reaction zone. Reaction 7, in inhibited flames, is balanced at relatively low temperatures, comparable to reaction 4. Reaction 6 was found not to balance in either the secondary or primary reaction zones. Radical decay in the secondary reaction zone was analyzed using the pool-decay concept. The important recombination reactions were judged to be H+OH+M~H2O+M, and H+O2+M?HO2+M. A rate coefficient of 2x1016 cm6 mole-2 sec-1 is calculated for M = the burnt gas mixture of Ar, HaO, CO2, and 5x1015 cm6 mole-a sec-1 is calculated for M = Ar (both for T = 1,750±150 K).

Jan 1, 1977

By R. K. Koch

The vapor pressures of liquid molybdenum and liquid zirconium were determined by the Langmuir free-evaporation method. An electron-beam furnace with a water-cooled copper crucible was used for melting. Temperature was measured with a two-color ratio pyrometer. The vapor-pressure data led to the following equations: [log p (atm) = 5.429 - 28,380 T for liquid molybdenum in the range 2,890° to 2,990° K, and log p (atm) = 6.521 - 30,940 T for liquid zirconium in the range 2,229° to 2,795° K.] Third-law evaluations of each data set gave mean heats of sublimation (298.15° K) of 157.6 ± 1.8 kcal/mole and 148.4 ± 2.4 kcal/mole for molybdenum and zirconium, respectively, where the uncertainties are two standard devia¬tions. Second-law standard heats of sublimation determined from sigma plots and tabulated enthalpies were 143.5 ± 2.7 kcal/mole and 149.2 ± 3.8 kcal/mole for molybdenum and zirconium, respectively. The better agreement in heats of sublimation for zirconium is attributed to the 566° K temperature range studied which permitted a more accurate definition of the vapor pressure curve than could be obtained from the 100° K span for molybdenum. This supposition was verified by making a sigma-prime plot which utilized solid vapor pressure data for molybdenum to extend the evaluation range by 800° K. This gave a standard heat of sublimation of 155.2 ± 1.6 kcal/mole which is in good agree¬ment with the third-law value. The plot also gave a standard entropy of sublimation (298.15° K) of 35.73 ± 0.48 eu.

Jan 1, 1968

To develop and design a bit that will rapidly drill smooth and precise instrumentation holes in soft rock. Approach Use a one-piece bit made by combining a drag bit and a diamond bit. Because a smooth-walled borehole with a precise diameter is needed for borehole pressure cells (BPC) and other borehole instruments, a diamond bit is usually used. However, diamond bit drilling is slow, and the bit will tend to bind when squeezing ground is encountered. On the other hand, the drag bit will cut faster, but the walls of the drill hole will be rough and the diameter will not be as precise. The combination will provide a bit which penetrates as rapidly as a drag bit, but retains the smooth-wall and precise borehole diameter of a diamond bit. How It Works A three-foot-length of EW-size drill rod is centered in a diamond bit by welding it to three equally-positioned spacers at each end of the bit. A drag bit is attached to the EW rod with a standard EW-to-drag bit adapter as shown in the diagram. Three equally-spaced diamond inserts are set to the desired hole size and welded to the diamond bit barrel behind the crown. These inserts increase the smoothness and precision of the hole by cut-ting away any hole closure. Three equally-spaced shims are set approximately 0.020-inch under the overall insert diameter size and welded to the rear of the diamond bit barrel. The combination bit should be used on a diamond drill with either water, mist or air as the coolant.

Jan 1, 1982

By T. N. McVay

The various applications of beryllium and its compounds in atomic - energy technology and a growing recognition of possible increased utilization of the metal in the aircraft and space - missile fields have resulted in increased interest in domestic and world reserves of beryllium . Unfortunately, little dependable data on beryllium resources and reserves are available , as past consumption of the element has been small and only limited prospecting and exploration work has been done . The scarcity of resource information is attributed partly to the difficulty of recognizing beryllium minerals in the field . These minerals frequently do not have distinctive characteristics of specific gravity, color , or other physical properties , that enable ready identification by the average prospector . This is particularly true of fine - grained minerals . As a result , a simple field test for identifying beryllium- bearing rock is needed . Recognizing this , technologists of the Federal Bureau of Mines investigated several of the proposed qualitative chemical tests for beryllium . This report describes various modifications of one of these methods to make it more suitable for use in the field . In the modified method , duplicate samples are fluxed -- one with potassium bifluoride and one with potassium bisulfate -- followed by dissolution of salts in water , conversion of the solution to an alkaline condition, addition of morin , and examination of the solution for fluorescence under short -wave ultraviolet light . This method provides a fast , dependable field test for beryllium minerals containing as little as 0.2 percent beryl or its equivalent . The test involves no radiation hazards , and it can be performed by persons having no technical training ; therefore , it should be useful to prospectors in discovering beryllium mineralization .

Jul 1, 1960

By John W. Buch

"INTRODUCTION The Ruhr coal basin is estimated to cover an area of more than 1,000 square miles. Here, the total thickness of the coal bearing formation (Carboniferous) is 10,500 feet, and drilling-hole have revealed 92 coal beds with a total thickness of 262 feet. 6/ Beds pitch from 0 to 90 degrees and about 70 percent of the wartime production came from beds that pitched less than 30 decrees. 5/For example at the Minisiter Stein mine, there are 24 minable coal beds ranging from 80 centimeters. (2 ft., 7 1/2 in.) to 250 centimeters (8 2 1/2 in.). The vertical thickness of the measures is 1,000 meters (3,200 ft.), and at this mine the deposits are covered with 150 meters (500 ft.) of surface wash. The cross section (fig, 1) at Fritz mine; Hoesch, A.G., Essen, Ruhr, is characteristic, The mines have been developed and worked to vertical depths of 2,000 to 2,500 feet by vertical shafts; main-level intervals are 500 to 700 feet apart. Haulage roads are straight, driven in rock, and centered as nearly as practical between property boundaries. Levels are sectionalized by driving crosscuts at right angles to the main haulage road on 800- to 900-foot centers. The roads are the main transportation arteries for the use of trolley or Diesel locomotives. A plan of the sixth main level (fig. 2) at the Bruchstrasse mine; Gelsenkirchener A.G., Bochum, illustrates main-level development and,sectionalizing with crosscuts. The cross section in figure 3 is that of the fourth crosscut west at the same mine."

Oct 1, 1946

By Barbara Fotta, Lynn Rethi

Within the Mine Safety and Health Administration's (MSHA's) classification of metallnonmetal (MAM) mining, the number of independent contractor' employees has increased significantly in recent years. In 1985 independent contractor employee hours reported to MSHA accounted for 4.5% of all M/NM mining employee hours (excluding office workers); by 1994 that proportion had doubled to 9.0%. As a result, these workers now account for an increasingly significant proportion of fatal and nonfatal mining accidents. According to MSHA's statistics, annually computed fatality incidence rates (the number of fatalities per 200,000 employee hours) for independent contractors working in M/NM mining are consistently higher than those for operator employees. Over the five-year period from 1990 through 1994, 53 independent contractor employees were fatally injured while working on M/NM mine property (See Table 1). More than one third of these fatalities (36%) were due to accidents involving powered haulage; 21% were machinery accidents; and 11% percent were falling material accidents. Combined, these three accident classifications accounted for 68% of all independent contractor fatalities occurring on M/NM mine property during these years. Clearly, current efforts to increase the safety of the mining workforce must also address the safety of the independent contractor employee. This report is a preliminary attempt to identify trends in the employment and safety of independent contractor workers by identifying which segments of M/NM mining are experiencing the greatest increases in the number of independent contractor employees and by examining changes in the rates and types of accidents in which these employees are involved. The employment and accident data used in this report were obtained from the MSHA database. [ ]

By Joan K. Kuenzi

The purpose of this U.S. Bureau of Mines information circular (Ie) is to discuss how job analysis methods taken from different disciplines can be used together to form a more complete picture of jobs in the mining industry. "Job analysis" is a term used by many researchers, but use of the term is far from standardized. Authors of papers on this subject often state that there is confusion in how or why jobs are to be analyzed, what the resulting information is to be used for, and what the "job analysis" actually means. The process of breaking a job into elemental tasks and analyzing them is used to determine what skills and knowledge are needed to perform a given job, to improve efficiency, and to develop safer job procedures. All are valid reasons to analyze jobs, but the methods used to accomplish the analyses may be very different. In order to create a more complete picture of a job, it may be useful to incorporate methods and information from different areas of study rather than choosing one method for analysis.

Jan 1, 1995

The Sago Mine Disaster, on January 2, 2006, placed renewed focus on several different aspects of safety in the underground coal mining industry. One area which received increased attention since Sago and other underground coal mining events is the concept of Safety Culture. This report describes the results of a pilot Safety Culture Assessment implemented at a small Appalachian underground coal mine, hereafter referred to as the Mine. The purposes of this pilot assessment were to (a) evaluate the feasibility and usefulness of a methodology for assessing safety culture that had previously been developed for use within other industries, (b) to initiate an investigation into the understanding and defining of the existing safety culture of the underground coal mining industry, and (c) provide meaningful and useful recommendations for the participating mine for their consideration in their ongoing quest to enhance their existing safety culture. This pilot assessment was conducted in July 2007. The report provides information regarding the presence or absence of safety culture characteristics within the Mine. Observations regarding the characteristics of the Mine?s safety culture that should be sustained are presented. Areas in need of attention and management focus to improve the Mine?s safety culture are presented as well as recommendations for moving forward. Safety culture characteristics that are important for the existence of a positive safety culture have been identified to include: - Safety is a clearly recognized value in the organization. - Accountability for safety in the organization is clear. - Safety is integrated into all activities in the organization. - A safety leadership process exists in the organization. - Safety culture is learning driven in the organization. - A process for establishing a strong and effective Safety Conscious Work Environment (SCWE) is in place. Performance objectives are associated with each of the safety culture characteristics and particular behaviors and attitudes have been identified that can be measured to evaluate these objectives. Using a methodology originally developed with the support of the U.S. Nuclear Regulatory Commission, an assessment of selected organizational behaviors and attitudes was conducted to evaluate the Mine in terms of these safety culture characteristics and their associated performance objectives. The methodology involves obtaining a variety of quantitative and qualitative information, using multiple data-gathering methods. The information collected is largely based upon the perceptions of the individuals in the organization. The evaluation is a ?point in time? snapshot of the Mine, but cultural beliefs and assumptions do not change quickly. The feasibility and usefulness of the methodology was successfully demonstrated during this pilot assessment. All aspects of the methodology including functional analysis, structured interviews with accompanying behavioral scales, work observations, and the paper and pencil

Aug 1, 2007

By James J. Olson

The Bureau of Mines recorded and analyzed overpressure levels for three production blasts at the White Pine copper mine, Upper Michigan, to obtain representative data from single-heading blasts in a long, straight haulageway and to estimate the damage potential inherent in production blasts fired in close proximity to underground structures. Commercial pressure gages with a flat response to 1 kHz were used with an FM tape recorder to record the overpressures from one dynamite and two AN-FO (ammonium nitrate-fuel oil), 500-msec production blasts having zero-delay charge weights of about 75 lb (34 kg). The recorded waveforms from the underground blasts (1) were more complex than the typical free-air wave, (2) were of longer duration, and (3) had numerous secondary arrivals due to reflections from the ribs and roof. The waveforms showed that the zero-delay charges produced the only high overpressures. First pulse peak overpressures from the blasts ranged from 0.10 lb/in2 (6.9 X 102 N/m2) at a distance of 471.1 ft (144 m) to a maximum of 1.76 lb/in2 (121.3 X 102 N/m2) at 191,7 ft (58.4m) from the blasts. An analysis of variance of the first pulse overpressures from the three White Pine blasts showed that no statistically significant difference existed among the overpressure levels from the dynamite and AN-FO blasts and that a single equation P = 4.9 x 103 (D /W1 / 3) 2 .15, where P = overpressure in pounds/inch2, D = d-stance from the blast in feet, and W = zero-delay charge weight in pounds, could be used to describe the falloff of overpressure with distance.

Jan 1, 1971

By B. P. Martinez

This report presents the results of a research and development program in recovering waste-rolling oils conducted by the Bethlehem Steel Co., before 1954 at its Sparrows Point plant, Sparrow Point, Md., with the cooperation of the Bureau of Mines, U. S. Department of the Interior, College Park, Md. The objective of the program was twofold: First, to recover oil for reuse in the plant; and second, to stop pollution, by oil, of the stream and harbor areas in the immediate vicinity of the plant. The sequence of the investigations was laboratory and pilot plant studies on sedimentation, simple aeration, and flotation for the separation of oil and water; and construction of a production unit using standard flotation equipment. This work was only preliminary for the Bethlehem Steel Co. and it has continued research on this problem. Recent progress indicates that new, improved processes will soon replace the flotation units described in this report. The first efforts to separate oil and water by simple sedimentation were unsuccessful. To establish the cause of this failure, microscope examinations and measurements were made on cold-reduction rolling mill cooling-water effluents containing oil in suspension. It was discovered that an average oil globule, held in suspension, was only 0.001 inch in diameter and would not coagulate with other globules for normal sedimentation at room temperature. The next step in the sequence of studies was to coagulate the oil suspension by simple aeration with air under slight pressure. The aeration methods studied were effective in removing up to 68 percent of the total oil but were approaching flotation in principle. The final investigation of the series was flotation of the oil in conventional laboratory-size flotation cells. The small-bubble method, without reagents, floated up to 89 percent of the total oil held in suspension and was the process selected for pilot-plant development.

Jan 1, 1959

By Charles L. Kimbell

The estimated value of world crude mineral production in 1990 exceeded $1,501.5 billion in terms of current (1990) dollars, or almost $1,160 billion in terms of constant 1983 dollars. This latter figure was 0.3% below the 1989 level and about 3.9% below the record high to date of $1,207.1 billion 1983 dollars set in 1980. Table 1 provides the latest available revised time series of the estimated value of world crude mineral production both in terms of 1983 constant dollars and in terms of current dollars. It also provides one of the two statistical bases for this 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 selected years up to 1983.1 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 pro-cessed output from mineral industry plants derived wholly from primary (newly mined) materials would be on the order of about $2,780 billion constant 1983 dollars or $3,600 billion in terms of 1990 dollars.

Jan 1, 1993

By John Nagy

Data from experiments and literature on gas and dust explosions in closed vessels are presented to show the effects of the vessel size and shape; the initial pressure, temperature, and turbulence; and the fuel-air ratio and the strength of ignition source on pressure and rate of pressure rise. An attempt is made to correlate some of these parameters with an elementary mathematical model. Analyses of data on 17 vessels--spherical, cubical, cylindrical, and rectilinear in shape--ranging from 0,018 to 905 cubic feet in volume were made. Although the study was initiated to provide information primarily on dust-explosion phenomena, some data were obtained for gas explosions so that the factor of initial turbulence caused by the pneumatic blast used to disperse dust could be evaluated. The mathematical interpretation of the explosion phenomena was in general accord with the experimental data, and correlation was obtained for several factors affecting explosion development. Neither vessel size nor shape affected maximum pressure (when heat loss was neglected). The rate of pres-sure rise decreased as vessel size increased, and the rate was proportional to the ratio of the surface area of the vessel to its volume. Induced initial turbulence markedly increased the rate of pressure rise and slightly increased the maximum pressure. Changes in initial pressure produced proportional changes in maximum pressure and rate of pressure rise. Initial temperature and maximum pressure were inversely related, but initial temperature had little effect on the maximum rate of pressure rise. Comparative experiments showed no appreciable difference in explosion development of gas and dust fuels. The vessels and experimental work are described, and all data are given in tables. The mathematical model will facilitate extrapolation from laboratory to industrial conditions and will allow comparison of results obtained in different laboratories.

Jan 1, 1971