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Various aspects of judgment and decision-making are key themes in this book. The model presented here serves as a loose structure for the chapters that follow this one. The notion of a model is introduced because growing research interest in the subjective aspects of group and individual behavior has led to a debate over whether judgment is a skill that can be understood scientifically. A related point of contention is whether such an understanding could lead to the development of methods for estimating people's ability to make good decisions during an emergency. There is some literature that supports the potential usefulness of this approach. However, little agreement seems to have been reached on how to define and operationalize even those basic concepts necessary to assess the soundness of decisions from within their environmental and group contexts [Jensen and Benel 1977; Godden and Baddeley 1979; Baumann and Bourbonnais 1982; Brecke 1982; Stone et al. 1985]. A look at the real-world process is clearly needed. The need to attempt a better understanding of judgment and decision-making properties stems from those occasions in the existence of an organization when there is a lot at stake. The process of decision-making (which is part of the exercise of judgment) has been analyzed in situations such as corporate takeovers [Janis and Mann1977], military combat [Begland1979], clinical emergencies [Baumann and Bourbonnais 1982], and aviation events [Billings and Reynard1984]. The fundamental assumption of these analyses is that, while there are untold successes, there are also notable numbers of failures resulting from decisions that can be ascribed to one or more errors in judgment. From a cognitive perspective, any person engaged in decision-making (either alone or in a group) is actively involved in a process characterized by certain elements. These were mentioned in chapter 1, but are reiterated briefly at this point: (1) detection of a problem, (2) definition or diagnosis, (3) consideration of available options, (4) choice of what is perceived as the best option given recognized needs, and (5) execution of the choice based on what has transpired [Flathers et al. 1982; Baumann and Bourbonnais 1982]. At any moment in this process, there are factors at play that have a large impact on one's ability to solve complex problems in a limited time: (1) an internal state [Hedge and Lawson 1979] is the sum of a person's psychomotor skills, knowledge, attitudes, etc.; (2) uncertainty [Brecke 1982] is caused by faulty or incomplete information received from the external environment; (3) stress [Biggs 1968; Jensen and Benel 1977] is generated both by the problem at hand and any background problem that may exist; and (4) complexity, as it is used here, refers to the number of elements involved that must be attended to. These variables are depicted in figure 5.1, and their relationship to each other and to an outcome is indicated. This schema is designed to suggest interaction, because while the judgment and decision-making process may be conceptualized as discrete stages, experience tells us that this is not the way people function in real-world situations.

Jan 1, 2000

By Oliver Bowles

This report covers the character, properties, origin, occurrence, and uses of the traprocks and describes briefly the methods and equipment employed in quarrying and preparing them for market. Production of traprock occupies an important place in industry. In 1960 the output in the form of crushed stone reached nearly 58 million tons valued at $87 million. Traprocks are also shaped into blocks of dimension stone for monuments, building construction and decoration, and specialized products such as surface plates.

Jan 1, 1963

By Oliver Bowles

This report covers the character, properties, origin, occurrence, and uses of the traprocks and describes briefly the methods and equipment employed in quarrying and preparing them for market. Production of traprock occupies an important place in industry. In 1960 the output in the form of crushed stone reached nearly 58 million tons valued at $87 million. Traprocks are also shaped into blocks of dimension stone for monuments, building construction and decoration, and specialized products such as surface plates.

Jan 1, 1963

By H. H. Schrenk

"One phase of the Bureau of Mines' work in the field of health and safety is the promotion of the use of safe, satisfactory, and reliable respiratory protective devices. To promote the development of such devices the Bureau has established schedules of minimum requirements for oxygen breathing apparatus3/ gas masks/, supplied-air respirators5/ (hose masks, airline respirators, and abrasive blasting helmets, hoods, or masks), and mechanical-filter respirators6/.Manufacturers of respiratory protective devices may submit their equipment to the Bureau for approval under the requirements of these schedules.As a prerequisite to such submittal, the Bureau requires a statement that the device is completely developed and of the design and material the manufacturer believes suitable for a finished marketable device; that the device has been subjected to inspections and tests such as described in the schedules, and that it met those requirements when tested by the manufacturer or his testing agency; and a. statement regarding the nature, adequacy, and continuity of control of the quality of the respirator. If the manufacturer can satisfy these requirements, and if the device, when tested by the Bureau, meets its requirements, a certificate of approval is granted by the Bureau of Mines. The approved devices bear distinguishing marks that indicate that they have been approved, the purpose for which they are approved, and the limitations of their use. If it is found at any time that approved devices purchased in the oven market and tested do not meet the requirements of the schedule, the Bureau may rescind that approval. Lists7/ of approved devices are published periodically for the convenient information of the public.Respiratory equipment may be divided into two main groups: (1). Those that afford protection by removing atmospheric contaminants and (2) those by which a respirable atmosphere from an uncontaminated source is supplied to the wearer.The devices that protect by the removal of contaminants may be divided into two subgroups: (1) Those that protect against gaseous contaminants and (2) those that protect against particulate matter. There may, of course, be combinations of these two.The devices by which a respirable atmosphere is furnished to the wearer also may be divided into two subgroups: (1) The self-contained type, by which the supply of oxygen, or material from which the oxygen can be generated is carried by the wearer, and (2) the hose type, by which air is supplied to the wearer through a hose or tube."

Sep 1, 1939

By J. E. Tiffany

"The new permissible blasting device, Cardox, utilizes as a blasting agent liquid carbon dioxide which is discharged.as a gas from a steel container or shell. The loaded shell is placed in a borehole, stemmed, and tamped in a manner similar to that employed with explosives, and is fired by electricity.The Bureau of Mines' approval for use of the device in coal mines was granted as Approval No. 1 under date of October 3, 1928; as the result of tests made under the conditions and requirements of Schedule 20. There have been three subsequent extensions whereby minor modifications in the original design were granted.The permissibility of the device is subject to the following conditions; (1) It shall be in all respects similar to the sample submitted for tests; (2) certain thicknesses of disc and. weights of heater ingredient and of carbon dioxide, all of which are set forth in Table 2 under the provisions governing permissibility, must be used: (3) the rear cap must always be in place after the shell has been charged, to prevent accidental firing; and (4) firing must be done by means of a permissible-type blasting unit.The permissibility of Cardox was established by gallery tests similar to those used in testing explosives for permissibility. In these tests the shell was discharged into gallery 1 without causing any ignition of gas and air or of gas, dust, and air mixtures there. The conditions of charging the shell, such as weight of the ingredients of the heater element, the carbon dioxide charge, and thicknesses of the disc, were varied according to the conditions under which it would be likely to be used in blasting. The tests made in gallery 1 are here described in detail, as are also the tests which have been made for determining the propulsive strength of the device and the quantities of poisonous gases given off when a shell is discharged."

Mar 1, 1929

By Joseph A. DeCarlo

For the first time the Bureau of Mines is combining, in one report, comprehensive tabulations on both beehive and slot-type ovens. This publication presents statistical data on the number and capacity of all such coke ovens in the United States on December 31, 1957. Combining data on both types of ovens should prove helpful to those interested in keeping abreast of the latest changes in carbonizing capacity, particularly since the coke has similar properties and uses. Annual reports furnished to the Bureau of Mines by coke-oven operators shared that 78 oven-coke plants were operating in 22 States on December 31, 1957. This was a decline of one plant from December 31, 1956, as the Republic Steel Corp. took the ovens at Canton, Ohio, out of production on December 17, 1957, for dismantling and rebuilding in 1958. Total oven-coke capacity was 80,299,400 tons in 1957.

Jan 1, 1958

By C. J. Johnson, C. J. Bise

"IntroductionCoal extraction by continuous miners (CM) is currently the most common underground method in the US industry and accounts for slightly more than two-thirds of the nation· s deep mining production (National Coal Association, 1987). Even if longwall mining should become more commonplace, it can proceed only af1er ventilation and access entries have been driven by CMs. Since an area of concern continues to be the effects of the dust generated on the health of mineworkers, this paper discusses the relationship between the elemental composition of mining-generated airborne dust sampled from the immediate ventilation return of a CM and laboratory-generated dust derived from channel samples taken from the mines.There are several potential contributions of this type of study to the coal mining industry. First after more fundamental knowledge of the causes of Coal Worker's Pneumoconiosis (CWP) is learned, the laboratory-generated respirable dust could be used to identify a potentially hazardous coal seam. Also, this study could possibly aid in understanding the fundamental causes of CWP by producing mining-simulated samples of coal dust that could be used in epidemiological studies.Further, assuming that there is no difference in the elemental composition of a drill-core sample and a channel sample from the same location a mining company could predict anew mine's respirable dust elemental composition In the immediate ventilation return by using exploratory drill core samples of the roof ,coal, and floor rock to prepare the laboratory dust. Ventilation engineers could then use engineering design and control measures during premine planning to reduce the incidence and severity of CWP by better ventilating the potentially hazardous coal seam. If this proper planning prevented any future changes to the ventilation equipment and mine design, much time and money could be saved.Scope of workTo investigate the variability of the chemical characteristics of respirable dust, airborne dust samples from eight underground coal mines located in the eastern and mid western United States were collected with eight-stage Sierra Model 298 Marple cascade impactors, as well as 25 channel samples of mined material. Each channel sample was removed from the middle of the coal face before mining occurred. Sampling of the mining-generated dust was conducted by Lee ( 1986) by sampling the entire working sections, primarily for characterization purposes, to obtain information on the locational variability of dust characteristics. Research performed for this study used the elemental analyses of the mining-generated dusts he sampled in the immediate ventilation returns of CMs."

Jan 1, 1989

By Thomas A. Phillips

The Bureau of dines present, an economic evaluation of its process for the ferric chloride leaching of chalcopyrite concentrate. In this process, chalcopyrite concentrate is leached with ferric chloride solution to extract copper, which is precipitated from the solution by electrolysis while leaving sulfur in the residue. Spent liquor from electrolysis is treated with oxygen to regenerate the ferric chloride leach solution and the sulfur-laden residue is processed to recover the sulfur. A cost estimate was prepared for a plant capable of processing 600 tons of chalcopyrite concentrate per day, 330 days per year. The fixed capital cost, on an early 1.975 basis is $27,831,600 and the estimated operating cost is 9.9 cents, per pound of copper product. In comparison, the estimated operating cost of a smelter equipped with a citrate process plant to recover sulfur is about 13.6 cents per pound of copper product. No charge for chalcopyrite concentrate or credit for recovered byproducts has been included in either operating cost. The ferric chloride leach process, therefore, appears to be economically attractive.

Jan 1, 1976

By Robert E. Wood

[The temperature dependency of the low-density thermal conductivity coefficients, ?°T, of nitrogen, 100° to 1,200° K, is correlated with the Keyes' equation, ?T ½ -1 -12/T) WT = aT+ bT 10 The equation ?T,P = ?°T +a[ ]ß represented 509 experimental higher V pressure thermal conductivities in the temperature range 131.2° to 973.15° K for pressures to 500 atmospheres, with a mean absolute deviation of 2.35 percent. This equation was used to compute thermal conductivities of gaseous nitrogen for 47 pressures, 1 to 240 atmospheres, and 110 temperatures, 133° to 740° K, which are common to conditions encountered in Bureau of Mines helium purification processes. Isobaric heat capacities, CP, and viscosities, ?T,P, from previous work were combined with the present thermal conductivities, ?T,P, to compute Prandl1 numbers, C?T P / ?T ,P, of nitrogen. Tabular values of Prandtl num¬bers are presented for 49 pressures, 1 to 240 atmospheres, and 75 temperatures, 133° to 740° K. Estimated uncertainties are ±5 percent in the tabulated thermal conductivities and ±15 percent for the computed Prandtl numbers. However, the uncertainty may rise to ±10 percent for thermal conductivities and to ±30 percent for Prandtl numbers as the critical conditions of nitrogen are approached.]

Jan 1, 1971

By John E. Shelton

Flotation tests were conducted on two samples of copper-nickel-bearing ore from the Harriman area near Rockport, Maine. The samples were taken by Roland F. Beers, Inc., for tests in cooperation with the Federal Bureau of Mines. One sample, analyzing 0.38 percent copper and 0.71 percent nickel, was essentially a disseminated pyrrhotite in hypersthene. Pentlandite, chalcopyrite, pyrite, and millerite were intimately associated with the pyrrhotite. Locked series flotation tests on this sample showed that 87.4 and 73.4 percent of the copper and nickel, respectively, could be recovered in a bulk concentrate that analyzed 3.47 percent copper and 5.34 percent nickel. The copper-and nickel-bearing minerals were collected with sulfhydric collectors in an alkaline circuit. Cleaning the concentrate three times with the addition of pH regulators was sufficient to attain the previously stated grades. The second sample had analyses of 0.31 percent copper and 0.85 percent nickel; talc and hypersthene were the main gangue minerals. Bulk sulfide flotation, made while depressing the talc, resulted in a concentrate that analyzed 2.33 percent copper and 4.70 percent nickel at recoveries of 70.0 and 54.4 percent, respectively. Flotation of the talc followed by bulk sulfide flotation resulted in a nickel content greater than 5 percent. A locked-series test showed that 60.7 percent of the copper and 73.7 percent of the nickel could be recovered at grades of 1.29 and 4.85 percent, respectively.

Jan 1, 1961

By John D. Sullivan

The recovery of copper by leaching from relatively low grade ores containing both oxidized and sulphide minerals is rapidly gaining in commercial importance. There is an economic limit below which certain ores can not be treated by concentration methods, and material with values below this limit must be discarded, possibly to be treated later, or the copper must be extracted by wet processes. Heap leaching has been carried out by the Phelps Dodge Corporation, Copper Queen Branch, for several years, and to-day its plant is a large producing unit. The Ohio Copper Coy at Bingham, Utah; has been leaching in place since 1919. Many other leaching operations are also being; carried out in various parts of the United States and in foreign countries. The plant at Rio Tinto, Spain, may be considered the father of heap leaching.

Jan 1, 1931

By A. E. Back

A method has been developed in the laboratory for successfully treating titaniferous magnetite ore from the deposit at Iron Mountain, Wyo. The ore is roasted with 15 percent sodium carbonate to convert the vanadium to a water-soluble form and fix the soda for the subsequent electric-smelting step. Approximately 90 percent of the vanadium is recoverable in a product assaying 80 percent V2O5. The leached calcine is briquetted and smelted in a graphite-lined electric-arc furnace. Substantially all of the titanium is recovered in a soda slag, assaying 60 percent TiO2 and 2 percent Fe, which can be upgraded to 75 to 80 percent TiO2 by leaching with dilute sulfuric acid. The upgraded slag could be utilized for the production of titanium dioxide pigments or titanium tetrachloride. About 90 percent of the iron is recovered as pig iron, containing only minor amounts of vanadium, titanium, and sulfur. The high TiO2 slag compares favorably with slag containing about 70 percent TiO2 being produced by the Quebec Iron & Titanium Corp. at Sorel, Quebec. The data obtained from this investigation indicate that a feasible process has been developed for treating Iron Mountain ore, and larger-scale testing is warranted to develop engineering data for the ultimate utilization of this deposit as a source of titanium, iron, and vanadium. There are adequate supplies of basic raw materials, electric power, water, sodium carbonate, coal, and petroleum products within fairly short distances of Cheyenne and Laramie, Wyo., the nearest cities and probable plant- and labor-supply points.

Jan 1, 1952

By V. F. Parry, W. S. Landers

"INTRODUCTION The primary object of this investigation was to determine changes in physical and chemical properties of subbituminous lump coal while in storage for 8 months in a typical residence and to demonstrate how this fuel may be stored without degradation or spontaneous combustion. The second object of the study was to determine how the stored coal performed in a hand-fired furnace operated under practical conditions.The investigation revealed that if care is exercised in placing sub-bituminous lump coal in a closed bin, no significant slacking or degrada¬tion occurs, no hazards arise, and over-all indicated efficiencies of about 65 to 69 percent can be obtained under practical,firing conditions that the average home owner can meet.Owing to the war emergency, much attention is being given to the proper storage of coal, and campaigns are being conducted to increase the quantity of coal being stored to relieve transportation and production overloads. Ordinarily, coal dealers do not recommend storage of subbituminous coal in homes owing to deterioration of the coal and to possible hazards from spontaneous combustion. This practice has grown from some troubles that have been experienced, which can be traced to improper preparation, improper bins, and poor technique in placing coal in a bin. There is no good reason why subbiturninous lump coal cannot be stored safely in homes."

Jun 1, 1944

By Mary A. Barrett

The Bureau of Mines conducted a laboratory-scale investigation of grouting mixtures containing iron or aluminum to determine the existence of health or explosion hazards, due respectively to oxygen depletion or hydrogen emission. Mixtures containing iron created an oxygen deficiency in less than 24 hours and released small amounts of hydrogen; a health hazard could occur but only under extremely unfavorable conditions. Mixtures containing aluminum released little hydrogen and consumed little oxygen; however, if improper on-site mixing yielded high local metallic aluminum concentrations, enough hydrogen might be released to produce an explosive atmosphere in a confined space.

Jan 1, 1969

Continuous remote sensing of methane concentration in underground mines. Approach A methane transducer, developed as a fixed point rib-or face-mounted operating device, measures ambient levels of methane and produces a signal that is proportional to the measured concentration. How It Works The methane transducer, developed under contract for the Bureau of Mines, uses a catalytic-type sensor which will detect methane concentration. The transducer is mounted vertically, as shown. This type of mounting minimizes dust accumulation on the sensing element, which might cause degraded operation. The unit must not be located in an area where water can continuously drip or run on It. The transducer generates an electrical signal proportional to methane concentration at the sensor. A sensor failure output indicates the status of the sensing element A circuit within the methane transducer detects whether the sensing element is shorted or open. A high signal (approximately 8 Vdc) on the failure output Indicates the sensor element is operating In Its normal range. A low output (less than 1 Vdc) indicates an element fault. The methane transducer, enclosed in a stainless steel

Jan 1, 1982

By Peter F. Steidl

As part of the Bureau of Mines methane control program, the Upper Free-port coalbed was studied in Fayette County, Pa., where this coalbed lies about 650 feet below the Pittsburgh coalbed and contains the largest remaining reserves of any coalbed in the county. Coal and overburden isopachs, structure and joint pattern maps, and a fence diagram were prepared using data from gas and oil exploration logs and coal outcrops. These maps will aid in deter-mining the need and/or feasibility of degasifying the Upper Freeport coalbed in the study area. Much of the coalbed in this area is under 600 to 1,400 feet of overburden. By correlation with data from the Pittsburgh coalbed, the gas content at depths of this order is estimated to be between 140 to 300 cf/ ton of coal, for a total of 190 to 400 billion cubic feet of methane in this coalbed in Fayette County.

Jan 1, 1977

By R. A. Beall

Homogeneous zirconium-alloy ingots have been cast on a production basis by the consumable-electrode arc-melting process at the Northwest Electrodevelopment Experiment Station, Bureau of Mines, Albany, Oreg. This paper describes the various methods used to introduce alloying materials into the ingot and evaluates 1 each method by the degree of homogeneity of resulting ingots, as determined in tests on sections cut from the ingots. As many as 30 or more ingots, each 6 to 10 inches in diameter and weighing 300 to 500 pounds, were melted, using each method; and, as most of them subsequently were fabricated to strip 0.1 inch thick, the test results are considered to be representative of production practice. Ingot homogeneity has been considered more difficult to achieve in arc-melting practice than by methods where the molten metal is poured into molds and the addition can be stirred into the total mass of metal before casting. Owing to the unique requirements of consumable-electrode arc melting the addition can be made only to that part of the total mass of the ingot that is molten at one time. Observation of the flowlines in 500-pound ingots produced at Albany indicates that the molten pool has a maximum depth about equal to the ingot diameter. The weight of metal molten at one time is, therefore, not over 100 pounds. Characteristically, the arc-melting process is conducive to segregation, which can be overcome, at least partly, by adding the alloy constituents almost continuously during casting.

Jan 1, 1956

By C. D. Litton

The results of full-scale fire tests are used to determine optimum distributions of fire sensors for the protection of conveyor belt haulageways in underground coal mines. Empirical relationships are derived that relate the spacing of fire sensors to the rate of development of the fire hazard. For this application, a critical fire size is defined as that size of fire for which belt ignition and subsequent flame spread down the belt is assured. Detection and alarm, regardless of sensor type or sensing methodology, must be achieved at some point in time before the critical fire size is reached. Based upon this approach, it is found that the horizontal spacing for products-of-combustion sensors is in the range of 300 to 600 meters, while the required thermal sensor spacing is found to be ~4 meters or less. Additional design criteria are discussed for product-of-combustion fire sensing systems.

Jan 1, 1982

By Neil B. Young

Carbonate minerals constitute a major fraction of the oil shale in Colorado's Green River Formation. Quantification of carbonate minerals is important for the characterization of oil shale, particularly because of their thermal activity in production of oil from shale. The carbonate minerals found in this oil shale are nahcolite (NaHCO3), dawsonite [NaA1(OH)2CO3], dolomite [(Mg1-xFx)Ca(CO3)2], calcite (CaCO3), and ferroan [(Mg1-xFex)CO3]. Although carbonate minerals can be removed by acid extraction from the balance of the oil shale, direct determination of carbonate minerals is complicated by the occurrence of the same cations in more than one mineral. A method for assigning the acid-soluble cations to the individual carbonate minerals was developed from two assumptions based on oil shale geochemistry: (1) Calcite and ferroan do not occur together, and (2) the ratio of iron and magnesium is the same in dolomite and ferroan. These assumptions were tested by the Bureau of Mines by applying the technique for assigning cations to 219 samples from the saline section of the formation. The reported carbonate mineral amounts were compared statistically with X-ray diffraction peak heights, verifying the cation assignment method.

Jan 1, 1975

By D. Dolinar, T. P. Mucho

Horizontal stresses are caused by global plate-tectonic forces. During 1995 alone they were largely responsible for the closing of two longwall mines in the United States. This paper presents six case histories from Pennsylvania, West Virginia, Kentucky and Alabama. In each case, a mine encountered roof falls or difficult ground conditions at the headgate caused by horizontal-stress concentrations. The problems are detailed, and the control measures adopted are described. In most cases, nearby longwall panels without stress concentrations were trouble free. The paper also discusses detailed measurements that were made at two adjacent Pennsylvania longwalls. One headgate was oriented to avoid a horizontal-stress concentration, and the other was not. Eliminating the stress concentration dramatically reduced roof support loads and roof deformation. The paper concludes that proper panel orientation and sequence is the key to maintaining headgate ground control. The optimum orientation is not parallel to the maximum horizontal stress, as previously thought, but rather it is 20° in the stress shadow of the gob. Other stress-control techniques, including artificial support, are briefly discussed.