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By Young C. Kim, Francis Martino, Ish Chopra

For the past two and one-half years, various emission control strategies were jointly developed by the University of Arizona and the Homer City Owners to com- ply with the clean air requirements at its Homer City Power Plant. Some of the available options for the SO2 emission control by the Homer City Owners were:l)cleaning of run-of-mine coal,2) scheduling of mining operations at its captive mines, 3) blending the captive mine coal with externally purchased low sulfur coa1,and 4) placing a partial FGD system. This paper describes two specific emission control strategies developed and implemented. These are: 1) production scheduling at the mining face to minimize sulfur variability, and 2) external purchasing of low sulfur coal for further blending. The main objective of this paper is to share our experiences on implementing the developed strategies. This paper emphasizesthe need for proper mine planning on a short-term basis, if the power plant is to meet the desired objective.

Jan 1, 1983

By A. G. Weber, H. J. Welge

A published calculation method for predicting incompressible, multidimensional fluid displacement has been adapted to the problems of water and gas coning in oil wells. Since depth and radial distance from the wellbore are the two key dimensions affecting the shape of a gas or water cone, coning calculations are well suited to the use of two-dimensional methods. The alternating direction implicit procedure (ADIP) was used for relaxation calculations of two-phase potentials in a two-dimensional grid. From the potentials and the capillary pressure relationship, saturation and pressure distributions were calculated which trace cone growth with time. Predictions have been made for well producing histories both before and after core breakthrough. To check validity of the method, two-dimensional calculations have matched the coning behavior and produced water-oil ratio history of a laboratory sand-packed model. They have also matched the coning behavior of several producing wells, for which the calculations were compared with produced water or gas cuts and logs showing water or gas cone movements. INTRODUCTION The application of two-phase, two-dimensional calculations using ADIP to various reservoir flow problems has been described in the literature.1-3 When adapted for computer solution, this method has proved to be a powerful tool for simulating well and reservoir behavior. This paper discusses the method as applied to well coning calculations. Single-well and coning calculations comprise an especially difficult class of two-dimensional problems which require special techniques for computer calculation and determination of reservoir characteristics. Refs. 4 through 8 describe previous approaches to the coning problem. Several examples of water and gas coning calculations, including studies on both laboratory models and producing wells, are presented here. The two-dimensional method accounts realistically for the most critical parameters affecting coning behavior, including production rate, formation stratification, horizontal and vertical permeabilities, depth of well penetration, gravity and capillary forces. The method considers the different densities and viscosities of the two phases and the relative permeability and capillary pressure characteristics of the rock and fluids. In addition to tracing cone growth in the vicinity of the wellbore, the method calculates the overall movement of the fluid interface throughout the well's drainage volume. Incompressible fluid flow is assumed to occur between the producing interval and the well's limit of drainage. Calculations can be made for the producing history both before and after cone breakthrough. A typical two-dimensional grid or array of blocks used to solve a coning problem contains about 400 blocks. The well's cylindrical drainage volume can be represented by about 20 radial subdivisions and the formation thickness by 20 vertical subdivisions. The grid spacing is normally smaller near the withdrawal interval to define the cone shape accurately. For this work we used an IBM 7074 digital computer having a core memory of 10,000 ten-digit words. A typical study, covering 5 to 10 years of well producing history, required from three to six hours of computing time. MATHEMATICAL SIMULATION OF CONING BEHAVIOR BASIC METHOD In coning calculations, the reservoir volume drained by the producing well is represented by a two-dimensional system of blocks as shown in Fig. 1 for water coning studies. The horizontal dimensions of the blocks increase with radial distance from the well axis in geometric progression, i.e., the block size is small near the wellbore and large near the well's drainage radius (re). Vertically, the blocks are bounded by horizontal planes located at different depths through the

Jan 1, 1965

By R. J. Blackwell, A. L. Pozzi

Scaled laboratory-model studies provide a powerful method for evaluation of a proposed oil-recovery process. In recent years, models have been used extensively to evaluate processes in which solvents displace oil, both for general cases and for specific reservoir conditions. Since the performance of a miscible flood in a horizontal reservoir can be significantly affected by transverse mixing between solvent and oil, this displacement mechanism must be accurately simulated in the scaled model studies. Unfortunately, precise scaling of transverse dispersion coupled with the requirement of geometric similarity requires impractically large laboratory models and long times for experiments. If scaling requirements for miscible displacements could be relaxed while accurate simulation of essential displacement mechanisms is maintained, the utility of model studies would be greatly enhanced. The purpose of the work reported herein was to evaluate the relative importance of various mechanisms affecting miscible displacement and to ascer tain whether the essential features of the displacement process can be simulated even though some scaling groups are not satisfied. These studies were performed with completely miscible systems in linear, horizontal models packed with unconsolidated media. From the experimental results, a set of relaxed scaling criteria was formulated which allows the requirements of geometric similarity and equality of the ratio of viscous to gravity forces to be omitted for specified conditions. The relaxed criteria are valid whether transverse mixing is by molecular diffusion or by convective dispersion. Correlations which permit prediction of vertical sweep efficiencies in linear, horizontal reservoirs were developed from the experimental data when transverse mixing is by molecular diffusion. These same correlations may be used when transverse mixing is by convective dispersion if an empirically defined, effective, transverse dispersion coefficient is used in the description of the mixing process. The effective transverse dispersion coefficient correlation essentially duplicates the dispersion coefficient correlation for equal-viscosity, equal-density fluid systems. Experimental values for the effective transverse dispersion coefficient can be measured readily. INTRODUCTION One of the most effective methods for evaluation of miscible-displacement oil-recovery processes is that of displacements in laboratory models scaled to simulate reservoir conditions. For these laboratory studies to be meaningful, however, the essential displacement mechanisms affecting reservoir performance must be accurately simulated. Since the performance of a miscible flood in horizontal reservoirs, or in dipping reservoirs at high rates, can be significantly affected by transverse mixing of solvent and oil, this mechanism must be considered in the design of laboratory experiments. Unfortunately, precise scaling of transverse dispersion coupled with the requirement of geometric similarity requires impractically large laboratory models and long experiment times. This difficulty seriously limits the utility of laboratory model studies. Craig,et al,1 demonstrated that geometric similarity is not required when mixing is unimportant. Their experimental data indicate, for the cases studied, that the displacement is sufficiently characterized by scaling the ratio of viscous-to-gravitational forces. This work suggests that relaxation of the requirement of geometric similarity and, possibly, other criteria might also be permissible when mixing is important, provided suitable groups describing the mixing process are scaled. The purpose of the work reported here was to evaluate the relative importance of various mechanisms affecting miscible displacement and to ascertain whether the essential features of the displacement process can be simulated even though some scaling groups are not satisfied. Consequently, laboratory investigations were made of the dependence of recovery on dispersion and other variables,

By M S. Kizil, T OÆConnor

It is predicted that underground coal mines in the Bowen Basin will have a significant rise in heat problems as mines aim to increase production, depth of extraction and length of longwall panels. At an actual Bowen Basin mine, extended longwall panels greater than 4 km in length are planned to be mined at depths with a virgin rock temperature (VRT) of more than 40¦C. Research has been completed into the reasons for the substantial increase in temperature at the face for underground coal mines in the Bowen Basin. An analysis into heat loads produced at the Bowen Basin mine for the development and production phases shows a significant amount of additional cooling will be required to ensure safe working temperatures. All of the major sources of heat, which included both natural and mine induced heating, were considered for the analysis. Maximum heat loads were assessed, together with peak intake surface temperature to determine the maximum cooling capacity required at a Bowen Basin mine. These maximum heat loads were assessed for a specific longwall panel, Longwall A, which extends to over 4.1 km in length and at a maximum depth of over 330 m, resulting in a VRT above 40¦C. The cooling system positional efficiency was analysed, determining that underground cooling via an indirect heat exchanger was preferred to increasing the capacity of the current bulk air cooling (BAC) on the surface. A preliminary cost analysis was also detailed which compared the cost of additional BAC compared to implementing underground cooling.CITATION:OÆConnor, T, Kizil, M S and Belle, B, 2013. Required cooling system capacities for extended longwall panels at a Bowen Basin mine, in Proceedings The Australian Mine Ventilation Conference , pp 249-256 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By L. M. Chan, D. H. Carlson, J. B. Johnson

"Abstract — Concentrations of tailpipe pollutants from diesel-powered. underground mine vehicles change over time due to engine wear and the need for maintenance. Since this deterioration in pollutant emissions may adversely affect the air quality in an underground mine, it should be monitored and controlled. This paper presents decision criteria concerning when to service a mine vehicle diesel engine. These criteria, based on mine air and tailpipe concentration measurements, are designed to maintain the tailpipe concentrations within limits that assure satisfactory mine air quality.Application of the deterioration criteria to mine vehicle emissions involves:establishing, for each pollutant, the allowable deterioration factor, anddetermining the deterioration factor, from the mine air and tailpipe diesel pollutant measurements, and the mine air threshold limit values (TLVs).If the deterioration factor is greater than or equal to the allowable deterioration factor the vehicle is removed from service for maintenance.An analysis applying the criteria to measurements made in an underground coal mine is presented. The tailpipe pollutant concentration data were collected using the Emissions Mea-surement Apparatus (EMA) developed by Michigan Techno-logical University. Since the TLV for diesel particulate matter (DPM) has not yet been established assumed mine air DPMTLVs of 15 and 1.0 mg/m3 were used in the analysis. For all of the diesel haulage vehicles included in the analysis. DPM was found to be the critical pollutant (the one most in need of control). For an assumed mine air DPM TLV of 15 mg/m3 none of the diesel haulage vehicles would he removed from service. However reducing the DPM TLV to 1.0 mg/m3 would make it necessary to remove two of the three vehicles tested from service."

Mar 1, 1992

By J. M. Bray, R. R. H. Cohen, P. Kiousis, S. R. Al-Abed

"INTRODUCTION Conventional tailing storage and management practices typically utilize engineered facilities, such as ring dikes and valley impoundments. To reduce the environmental costs associated with disposing of mine wastes in tailing storage facilities (TSFs), several beneficial re-use strategies have been developed over the years. For example, thickened tailings have been used for paste backfill. It is common for tails to comprise up to 60% of the material’s total weight and it has been estimated that TSF volumes can be reduced by 60% when using this strategy, (Benzaazoua, et al. 2004). Other beneficial re-use strategies have produced unpaved temporary access roads, hot and cold asphalt, chip seals, self-compacting concrete, and golf course sand traps. This project sampled mine tailings from two different TSFs in Colorado and produced structural concrete that could potentially be used for commercial foundations, sidewalks, and paved roads. The tailings were substituted for the fine aggregates typically found in conventional concrete. The two main objectives of this study were to investigate the structural integrity of the produced concrete samples and the leaching of heavy metals from the resulting concrete. The ratio of tailings to fine aggregate (T/FA) was carefully studied to find if there was a correlation between the substitution rate and the structural integrity. The potential maximum substitution rate was also investigated for the produced concrete specimens. The potential of leaching mining impacted water (MIW) was evaluated by comparing the leachability of the raw mine tailings to the encapsulated tailings by using standard shake extraction prediction tests. MATERIAL AND METHODS Materials The four components that make up the concrete mix design for this project are: cement, coarse aggregate (gravel), fine aggregate (sand and mine tailings), and water. The type I/II ordinary Portland cement (OPC), gravel, and sand came from local cement and concrete companies in Denver, Colorado. Mine tailings were collected from two different TSFs in the Rocky Mountain Region, where Pride of the West TSF in Silverton, CO will be denoted as Site A. The primary metals of interest at the mill site are gold, silver, lead, copper, and zinc. The location of Site B will not be mentioned in this report due to confidentiality agreements with the mining company"

Jan 1, 2016

By Bruce M. Davis

The variogram is the function used to express the intercorrelation of a regionalized variable. It is used to quantify, for example, the natural variability of mineralization and in that sense may be thought of a average disimilarity between metal quantity at two points inside a deposit.2 As David2 explains, appropriate mathematical functions of distance and direction are used to characterize variograms, a process that he says is analogous to selecting a normal or lognormal model for an observed distribution. Methods for choosing a model for the underlying variogram of a random function based on the sample data appear in the literature.3,8 A crossvalidation procedure is available to check the validity of the model.3 However, statistical validation of the choice of the model through the mechanism of hypothesis testing is not presently available. In the section to follow, notation and background material is presented upon which a large sample test procedure will be constructed. The stationarity assumptions presented refer to covariance stationarity. A test procedure is then proposed, and an example is given for the case of the one dimensional random process.

Jan 1, 1979

By Ning Yang, Yuxiang Chen, Ming Chen

An ultraviolet laser Raman spectrometer was developed to detect and analyze material components of seawater, seafloor sediment and rock at a depth of 7000m maximally. Wave length of the excitation resource of the spectrometer is set to 355nm, which can enhance eigen scattered intensity and detecting sensitivity, and avoid fluorescence interference. Miniaturization design was adopted for deep-sea application. Design of the optical system and pressure cartridge, material selection and seal design of the observation window, and design of the Lithium batteries are the key technologies in the procedure of research and development. The spectrometer was carried by a Lander sank to sea bottom of the Pacific's Mariana Trench for verification. During the sea trials, data acquisition for Raman spectra was conducted for analyzing seawater in the detection area, and the spectrometer was verified synthetically. According to the data, the spectrometer is stable and practicable with high resolution and precision, and it is appropriate to detect and analyze composition of substance under the tremendous ocean.

Jan 1, 2017

By B Mohanty

The current basis for rating of commercial explosives is examined, with particular emphasis on calculated bulk and weight strengths, detonation velocity and underwater energy measurement. The calculated strengths still form the basis for selecting explosives for most blasting applications, with the measured detonation parameters serving only as a measure of the quality of the explosive. The major drawbacks with this approach are discussed, in view of the non-ideal nature of commercial explosives and the field conditions prevalent during the blasting operation. A unified approach to rating explosives on the basis of blasting performance rather than calculated energy alone is presented for various types of explosives. This incorporates the relevant field parameters as well as the effect of non-ideal reactions, both of which affect explosive energy release and its transfer to target rock.

Jan 1, 1988

By Leonardo Massone

The p-y method is one of the most popular methods in pile design and has been calibrated for various boundary conditions using numerical and experimental studies during recent years. Most studies on reinforced concrete (RC) piles have included the impact of flexural nonlinearity, (e.g. nonlinear moment?curvature relations) but not considered associated pile shear deformations when deriving p-y curves from field data. Common p-y curves may be better applicable for piles with flexure dominated failures (e.g. piles with free- head boundary conditions). For piles with fixed head boundaries (i.e. rotation restrained piles) shear deformations could be of significant influence. To study this problem, a coupled shear flexure interaction model for axial-bending-shear behavior coded in OpenSees was applied to a 0.61 m (2 ft) diameter flagpole and a 0.61m (2 ft) diameter fixed head pile specimen to investigate the possible influence of shear deformations to the overall pile responses. The surrounding soil was represented by p-y curves derived from prior large scale testing on piles with similar boundary conditions. Analysis results show that for flagpole piles, shear forces and shear deformations were insignificant. Considerable contributions of pile shear displacements and forces were observed for the fixed head pile, with shear displacements contributing up to 40% of the total pile displacement. Results suggest that nonlinear shear deformations for reinforced concrete piles should be considered for fixed-head or similar conditions, and that currently used p-y curves may underestimate the actual lateral pile displacement and possibly lead to unsafe design for the particular boundary condition.

Jan 1, 2012

By C. Kirmanli

The purpose of this paper is to develop an expert system for hydraulic excavator and truck selection in surface mining. Hydraulic excavators and trucks are finding increasing applications in mining operations. Hydraulic excavators are extensively used especially when bringing electricity to rural areas is difficult and for small-scale mining. This paper describes an expert system, which selects the optimum hydraulic excavator truck configuration such that unit production cost is minimized and technical constraints such as geological, geotechnical and mining constraints are satisfied. The system has four modules: user interface, rules and an methods, databases and output module. The expert system in this study is developed within KappaPC shell. It supports object-orientated technology for the MS Windows environment. The software provides a very useful tool to practitioners, saving time and cost. Equipment selection is a recurring and expensive problem of mine planning and often involves interdisciplinary experts from different fields. It is very difficult and expensive to bring together all these experts. The capabilities of the expert system developed are illustrated in the paper. The software overcomes the difficulties of selecting the proper equipment for surface mining operations, which is very important, and results in substantial savings. Equipment databases for hydraulic excavators with 15-59 yd3 capacities and trucks with 35-360 tons are constructed and these databases are used to select the proper configuration. A case study is carried out for Soma Surface Coal mines in Turkey. Keywords: surface mining, expert systems, equipment selection, hydraulic excavators, diggability

Jan 1, 2009

By M. B. Haggerty, R. J. Sheets, F. Abbasy

To address coal refuse tailings storage needs for a mine operation in western Canada, a feasible solution was to convert excavated open pits into tailings cells. A slope stability investigation and design study were completed to determine the necessary width and slope geometry for in-situ native plugs as the impoundment embankment. The native plugs separate the previous open pit from the current active open pit. This configuration allows for the deposition of refuse tailings in the previous pit while allowing mining to safely continue “downstream” of the temporary impoundment. As mining progresses, each subsequent pit will be filled with refuse tailings; thereby, buttressing the upstream slope of the previous native plug. Although these cells are excavated, and the timeframe for downstream exposure is relatively limited, the native plugs are classified as dams and must be designed to meet applicable safety of dam standards since they impound water and tails above mining personnel in the subsequent open pit. The presentation and paper will discuss the investigation and analysis conducted to develop the geotechnical and hydrogeological design recommendations.

Mar 2, 2022

By J. A. Danko, C. D. Pears, L. D. Schmidt, J. P. McGee

This paper describes a pilot plant built on the campus of West Virginia University by the Federal Bureau of Mines station at Morgantown, West Virginia, for gasifying pulverized coal in a mixture of oxygen and steam at pressures in the gasifier up to 450 psig. The work upon which this report is based was done under a cooperative agreement between the Bureau of Mines and the West Virginia University. The goal of Bureau of Mines work at Morgantown is development of a low-cost process for producing mixtures of carbon monoxide and hydrogen for the modified Fischer-Tropsch synthetic-fuel plants, which may be shifted to produce hydrogen for coal-hydrogenation plants. Gasification with oxygen offers the inducement that the gas may be generated at the pressure at which the gas will be utilized in a gas-synthesis plant. Since the optimum pressure for the synthesis appears to be about 400 psig, the gas should be produced at approximately 450 psig to take care of pressure drops in the purification train and control valves. If the gas is generated at the pressure of utilization, only the oxygen need be compressed, not the raw synthesis gas. This means a saving in power of 5 hp per hour per 1000 cu ft (CO + H2), which is approximately a saving of 4 cents per gallon of gasoline. For example, consider a commercial plant generating 18,000,000 standard cubic feet per hour of raw gas that would produce approximately 10,000bbl of liquid product per stream-day. Assume that this gas would be 85 pd CO + H2 and that the oxygen required would be 320 cu ft per 1000 cu ft of CO + H2. The following estimate is based on a commercial centrifugal compressor. If the 18,000,000 std cu ft per hour of synthesis gas is compressed to 450 psig with 74 pd efficiency, 107,000 hp is required for compression. If the synthesis gas is generated at 450 psig pressure, only

Jan 1, 1953

By Albert D. Brokaw

THE accompanying chart was devised to provide a rapid and simple method of correcting for temperature and compressibility (deviation from Boyle's law) of gas under relatively high pressures and temperatures, such as are encountered in many deep reservoirs. The chart was prepared by interpolating for the desired values in the experimental data of Burke and Keyes1 and Kvalnes and Gaddy2 on the compressibility of methane, after adjusting their results from 0°C. to 60°F. and combining the correction factors for compressibility and temperature into a single multiplier, which, applied to the product of pressure and reservoir volume, gives at once the volume at one atmosphere (14.7 lb. per sq. in. abs.) and 60°F. The relationship 0f this multiplier to the compressibility factor Z, as used in most discussions, is simply: [Multiplier = 460° + 60°ZT –] where Z is the compressibility factor and T the absolute temperature (Rankine). Fahrenheit temperatures are shown on the vertical axis and pressures in pounds per square inch absolute on the horizontal axis. Correction factors or multipliers at intervals of 0.05 from 0.55 to 1.40 have been plotted on the chart and are calculated t0 give volume of gas at one atmosphere pressure (14.7 lb.) and 60°F. The operation is as follows: The reservoir volume, times the number of atmospheres pressure, times the multiplier, gives the volume of gas measured at one atmosphere (14.7 lb. per sq. in.) and 60°F. For example, a reservoir is estimated to have a volume of 10,000,000 cu. ft., bottom-hole pressure is 2940 lb. per sq. in. and temperature is 184°F To make the correction for methane, follow the 184° line horizontally to the 2940-lb. pressure line. The intersection lies between the 0.85 and 0.90 correction lines, and by interpolation we may estimate the multiplier at 0.863. The computation is simply: [ ] Using the chart for methane prepared by Prof. G. G. Brown3 and his associates, the multiplier is found to be 0.867. Details 0f computation are as follows: Correction factor to apply to PV to correct for deviation from Boyle's law and adjust to measurement basis of 60°F.: [ ]

Jan 1, 1941

By Per-Lennart Nystedt

"The Boliden Lead Kaldo Plant for the treatment of lead bearing flue-dust from the Copper Smelter and the Slag Fuming Plant has been in operation at the Ronnskar Works of Boliden Metall since the middle of 1976. At the present stage, the plant can treat lead-bearing dust of different kinds and compositions. The process allows good separation of arsenic and halogens from lead.The flue dust from the Copper Smelter and the Slag Fuming Plant is very complex and, apart from lead, also contains zinc, copper, tin, bismuth, cadmium, antimony, arsenic, sulphur, silver, chlorine and fluorine. The metallurgical process has been developed by Boliden Metall and has been tested on a pilot scale at the Foundation for Metallurgical Research (MEFOS) in Lulea, Sweden.The pelletized dust is smelted in the converter, where the heat is generated by an oil oxygen burner. The second step consists of reduction with coke. A lead bullion and slag are obtained. The slag, transported in liquid form, is treated in the Slag Fuming Plant for the recovery of zinc. The third step is the elimination of arsenic from the bullion. This is achieved by treating the lead with iron (turnings or pellets). The result is a crude lead and speiss. The lead contains silver, tin, antimony and bismuth, and is suitable for the final refining stages in normal plant equipment for refined lead.For process control, we use the rapid analysis centre, which is pneumatically and electronically linked to 'all major plant sections and allows for a quick turn-around between delivery of the sample and feedback of results. All three steps in the process are performed in the same converter.Since the starting up of the plant, the original process has been subjected to some modifications. Initial problems related to equipment, maintenance and environment have been solved step by step. Examples are quoted. Recent operating particulars are presented."

Jan 1, 1980

By John Dasher, Wilfred L. Freyberger, James H. Pannell, A. M. Gaudin

WHEN beryllium is bombarded by gamma rays under suitable conditions it evolves neutrons. This nuclear reaction, Bes + y + n + Be", [I] is utilized in the process that is described in this paper. The equation, which physicists often abbreviate to Bevy, n)Be" shows that a photon, y, is absorbed by the Be- sotope of beryllium which then emits a neutron, n, leaving Be8 as a residue." It has been determined that the threshold for this reaction is 1.63 mev; that is, gamma rays having an energy less than 1.63 million electron volts do not have enough energy to remove a neutron from the beryllium nucleus. The threshold value for the beryllium (y, n) reaction is lower than that for any other element. The next most sensitive element is heavy hydrogen (deuterium) whose gamma neutron reaction, D2 (-y, n) H1, has a threshold of 2.2 mev. Thus, gamma rays having an intensity between 1.63 and 2.2 mev will evolve neutrons from beryllium and from beryllium only. Nuclear reactions can be considered as occurring between a projectile and a target. The probability of the occurrence of any such encounter can be expressed in terms of the "cross section" of the target nucleus for the projectile and projectile energy. This cross section, then, is the area normal to the path of the projectile controlled by the target for the purpose of the reaction under consideration. Cross sections are usually expressed in barns, in which a barn is lo-" sq cm. The cross section for Eq 1 is very small, even for nuclear reactions, and of the order of 10"3 barns. It is therefore necessary that a high flux of gamma radiation at the appropriate energy be used to obtain an appreciable neutron yield. In view of the nuclear properties of beryllium it seemed that if pieces of beryllium ore on a moving belt were bombarded with an intense beam of gamma rays, those pieces which are rich in beryllium minerals would emit neutrons at a sufficiently high rate to make it possible to detect that emission, and to use it to actuate a mechanical device for removal of the active from the barren particles. The principal economic source of beryllium is the mineral, beryl. Beryl occurs mainly in pegmatites which are characteristically coarse grained. The suitability of mechanical concentration depends upon the size at which the desired mineral can be liber-

Jan 1, 1951

By James H. Pannell, John Dasher, Wilfred L. Freyberger, A. M. Gaudin

WHEN beryllium is bombarded by gamma rays under suitable conditions it evolves neutrons. This nuclear reaction, Bes + y + n + Be", [I] is utilized in the process that is described in this paper. The equation, which physicists often abbreviate to Bevy, n)Be" shows that a photon, y, is absorbed by the Be- sotope of beryllium which then emits a neutron, n, leaving Be8 as a residue." It has been determined that the threshold for this reaction is 1.63 mev; that is, gamma rays having an energy less than 1.63 million electron volts do not have enough energy to remove a neutron from the beryllium nucleus. The threshold value for the beryllium (y, n) reaction is lower than that for any other element. The next most sensitive element is heavy hydrogen (deuterium) whose gamma neutron reaction, D2 (-y, n) H1, has a threshold of 2.2 mev. Thus, gamma rays having an intensity between 1.63 and 2.2 mev will evolve neutrons from beryllium and from beryllium only. Nuclear reactions can be considered as occurring between a projectile and a target. The probability of the occurrence of any such encounter can be expressed in terms of the "cross section" of the target nucleus for the projectile and projectile energy. This cross section, then, is the area normal to the path of the projectile controlled by the target for the purpose of the reaction under consideration. Cross sections are usually expressed in barns, in which a barn is lo-" sq cm. The cross section for Eq 1 is very small, even for nuclear reactions, and of the order of 10"3 barns. It is therefore necessary that a high flux of gamma radiation at the appropriate energy be used to obtain an appreciable neutron yield. In view of the nuclear properties of beryllium it seemed that if pieces of beryllium ore on a moving belt were bombarded with an intense beam of gamma rays, those pieces which are rich in beryllium minerals would emit neutrons at a sufficiently high rate to make it possible to detect that emission, and to use it to actuate a mechanical device for removal of the active from the barren particles. The principal economic source of beryllium is the mineral, beryl. Beryl occurs mainly in pegmatites which are characteristically coarse grained. The suitability of mechanical concentration depends upon the size at which the desired mineral can be liber-

Jan 1, 1951

By E. Eccleston

The ConRoast process for the production of platinum group metals involves the use of a fluidized bed reactor for the removal of sulphur from ore concentrates by roasting prior to smelting in a DC-arc furnace. Test work was carried out in 2007 at Hazen Research in Golden, Colorado to provide the data necessary for a commercial roaster to be designed by Technip. This paper discusses the rationale behind the test work, the goals for calcine composition to be used as smelting furnace feed, the results of various roaster operating parameters in terms of calcine composition (particularly residual sulphur and the fate of trace elements), and the impact of the results in terms of a commercial roaster design.

Jan 1, 2009

By Thomas W. Camm

A WINDOWS-based object-oriented expert system for prefeasibility evaluation of hard rock mines is being developed at the Western Field Operations Center (WFOC) of the Bureau of Mines. Designed for use with the Bureau's Cost Estimating System (CES), this expert system assists an evaluator in choosing an underground mining method, and the related design parameters. The system provides the engineering and design guidelines necessary for an evaluator to perform a prefeasibility type cost estimate.

Jan 1, 1992

By Theron A. Klinefelter, Sidney Speil, Sidney Gottlied

"INTRODUCTION The investigation of domestic talcs by the United States Department of the Interior Bureau of Mines, was initiated in December 1941 at the request Gen. Charles Hines of the United States Army. The urgency for such study was expressed by General Hines as follows:The radio-manufacturing industry has recently been expanded by the Army to provide sufficient, capacity for defense needs, and considerable concern has been expressed by the supply Arms and Services over maintaining continued availability of supplies of the necessary raw material. These ceramic products are used by the Signal Cores in all Army radio equipment, and to a greater degree in the new special ultra-high-frequency equipment. The Air Corps has recently become a user large amounts of radio-grade ceramics for aircraft spark-plug covers required for high-altitude operations. In addition, the use of this material is essential to the proper functioning of the radio-navigation aids of the Civil Aeronautics Board.Progress in the Bureau of Mines studies on talc was made available to representatives of the Army and Navy through frequent interim reports. Through the efforts of the several war agencies concerned with raw-materials supply and the domestic talc producers, the condition of scarcity that developed in 1942 passed to one of ease in 1943, and has so continued to date. Tentative estimate of reserves delineated indicates a supply of high-grade steatite sufficient to meet military war requirements for at least 4 or 5 years."

Apr 1, 1945