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By John E. Urosek, Dennis A. Beiter, William J. Francart

In This Chapter [Designing bleeder systems Examining and maintaining bleeder systems Evaluating bleeder system effectiveness] INTRODUCTION Bleeder systems are that part of the mine ventilation network used to ventilate pillared areas in underground coal mines. Pillared areas are those in which pillars have been wholly or partially removed, including the areas where coal has been extracted by longwall mining. Bleeder systems protect miners from the hazards associated with methane and other gases, dusts and fumes, and oxygen deficiency that may occur in these mined-out areas. Effective bleeder systems control the air passing through the area and continuously dilute and move any methane-air mixtures and other gases, dusts, and fumes from the worked-out area away from active workings and into a return air course or to the surface of the mine. A bleeder system includes the pillared area (including the internal airflow paths), bleeder entries, bleeder connections, and all associated ventilation control devices that control the air passing through the pillared area. Bleeder entries are special air courses designed and maintained as part of the mine ventilation system. [This chapter focuses on the design, examination, maintenance, and evaluation of bleeder systems in underground coal mines.] The history of coal mine explosions in the United States is a reminder of the importance of adequate ventilation. Some of those disasters were the result of inadequately ventilated pillared areas. The importance of developing bleeder systems to ventilate these pillared areas and evaluating the bleeder system’s effectiveness is reflected in present-day federal regulations. For more information on bleeder systems, see Tisdale [1996] and Urosek and Francart [2002].

Jan 6, 2006

By Javier A. Llano

GPS, wireless communications and on-board and off-board computing capabilities provide today’s mining companies with unprecedented process improvement and cost reduction opportunities. All aspects of the operation from engineering, surveying, drilling, loading, hauling and support can benefit from products like CAES and Drill Monitor. These technologies, which have been working at world class mines around the world in some cases for over three years, are helping customers achieve new lows in cost per ton. Manually intensive and time-consuming processes like in field surveying are replaced by timely mine status information wirelessly transmitted from the machines to the office.

Jul 17, 2000

By Gleason

"From June 16 to 19, more than 1,400 tunneling and underground construction professionals gathered in Chicago, IL for the bienial Rapid Excavation and Tunneling Conference (RETC). There, they were greeted by a full technical program and an exciting exhibit hall that provided a comprehensive look at the world’s bustling tunneling and underground construction industry.The successful conference was a reflection of the industry itself, which is to say, busy. As much of the world has begun to focus on creating a cleaner and greener environment, the global tunneling industry has seen an uptick in infrastructure projects move from design-build to construction phase. With a global shift away from the use of fossil fuels, major cities around the world are looking to increase public transportation options, which leads to the need for more transportation tunnels. And as urban populations continue to grow, the need for clean water calls for more tunnels, and as urban footprints continue to expand, the need to increase and update combined sewage overflow tunnel grows with them.During two and a half days, more than 20 sessions covering all of these topics were presented at the Hyatt Regency in Chicago, many to packed rooms in which every seat was taken and people were standing along the side and back walls.RETC is a biennial conference and one of the largest in the North America for the tunneling and underground construction industries. As such, it hosts a robust exhibit floor. This year 172 vendors occupied 205 booth spaces. The exhibit included everything from tunnel boring machine manufacturers, like Robbins and Herrenknecht, to the companies that supply all kinds of parts and services to the industry."

Sep 1, 2019

By Aleksandar D. Bugarski

Despite extensive research efforts conducted in the past decades, occupational health risks associated with exposure to nano and ultrafine aerosols emitted by diesel power equipment are still not completely understood. The complexity of physical and chemical properties of diesel aerosols, constantly changing with the implementation of advanced diesel emissions control technologies, make this task rather challenging. The objective of this paper is to identify and characterize nanometer and ultrafine aerosols emitted by diesel engines in the underground environment and evaluate the effects of selected contemporary control technologies on physical properties, chemical composition, and in-vitro toxicology of diesel aerosols. The physical and chemical properties of the nanometer and ultrafine diesel aerosols are to be characterized through a test series in the NIOSH Lake Lynn Laboratory experimental mine. The crucial part of the study has been development of a facility that allows researchers to generate field results with precision and accuracy characteristics of a laboratory environment. The knowledge obtained from this study should strengthen our understanding of the health implications related to exposure to diesel particulate matter and aid in assessing the potential of various control technologies for reducing this exposure.

May 1, 2007

By R. L. Andrew

The southwest Pacific has produced at least four of the world’s premier porphyry copper-gold deposits, and the current level of exploration is likely to produce even more. An appreciable amount of gold is being produced with this copper, with obvious economic advantages. Gold content, in addition to their large size, makes the southwest Pacific’s porphyrycopper-gold deposits very attractive exploration targets. The recognition of telescoping and overprinting of porphyry systems has produced a greater awareness of the likely surface expressions, in particular the significance of advanced argillic lithocaps in porphyry exploration. The recognition of the spatial and genetic association of porphyry copper and epithermal gold systems (Sillitoe, 1972), as in other parts of the world, has had important implications for exploration in the Asia Pacific region.

Jan 1, 1995

By Jeffrey A. Shibe

A prototype Fire Safety Evaluation System has been developed and is ready to be evaluated by a Peer Consulting Panel and for performing field tests. The system can be used to determine combinations of widely accepted fire safety equipment and under-ground coal mine features that provide a level of safety equivalent to those required by the Code of Federal Regulations-Title 30 for underground coal mines. In this evaluation, equivalent safety performance is gauged in terms of overall level of safety provided rather than by a component by component comparison.

Jan 1, 1987

By Lloyd Williams

1. The investigation shows that the Coal Creek has been the most productive, bed in Campbell County and contains the largest recoverable reserves of coal. The Pewee, Red Ash, and Jullico have been relatively productive beds and contain appreciable recoverable reserves of coal. The Blue Gem also has been productive in the past, but available information indicates that most of the remaining coal is Less than 28 inches thick. The Big Mary has relatively large reserves over 28 inches thick, but the coal is high in ash and sulfur. Thick partings in the Windrock bed have discouraged mining in that bed. The Poplar Creek and Rex beds generally are below drainage, and large areas have been excluded from the reserve estimate, Reserves in the Walnut Mountain bed will be difficult to mine due to the irregu¬lar thickness and lack of continuity of the bed. Estimated coal reserves are- small in the remaining five beds. 2. Known measured and indicated reserves of coal, based on a minimum bed thickness of 14 inches and on 1,800 short tons per acre-Foot of coal in place, are estimated to be 398 million tons as of January 1, 1953, o? this total, 267 million tons is in beds 28 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics are too meager to make an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, these should be added to the total estimated reserves.

Jan 1, 1956

ZAY JEFFRIES (author's reply to discussion *).-Messrs. Merica's and Humfrey's criticisms of some of my conclusions are rendered in the true scientific spirit by means of which differences of opinion are gradually smoothed out and all participants are benefited. It is true that the statement of generalizations on such a complex subject is hazardous, but I shall endeavor to point out the explanations for the discrepancies noted. Owing to the fact that I am now submitting a long paper on the same general subject to the Institute, my present remarks will be brief. Dr. Meric&s Assumptions' I agree with No. 1 and No. 2, with the modification that the A (amorphous) metal between grains of annealed metal has substantially the same properties as that at slip planes in deformed metal, but the two have different arrangements with reference to C (crystalline) metal and they may be in different conditions as regards internal stress, thickness, and nature of contact with C metal. Assumption 3.-I believe Fig. 1 is wrong. I know of no evidence to substantiate the curves. I believe cc (elongation of C phase) = 0 (approximately) at all temperatures and ?A (elongation of A phase) has finite values at elevated temperatures only; but these play no important direct role in the ordinary deformation of metals at low temperatures. I believe Ec (elastic limit of C phase) = Tc (tensile strength of C phase) because as soon as C metal begins to deform permanently it would rupture were it not for the A metal generated by its breakdown. We know that Ec = Tc in brittle crystals and a crystal cannot be permanently deformed without generation of A metal. Therefore Dr. Merica's

Jan 12, 1918

By T. G. Joseph

"The Oil sands-Equipment Interactions Program (OsEIP) is a collaborative research venture between Syncrude Canada Ltd., James Progithin International Ltd. (JPi), the University of Alberta, P&H MinePro, and Caterpillar Inc. The objective is to better understand the behaviour of oil sands as it interacts with mining equipment, in particular, large trucks and shovels. With a move to ever larger equipment, mining oil sands of highly variable bitumen content, ground stability comes into question. This paper outlines this aspect of OsEIP and provides some insight into how some of the findings enable an improved understanding of oil sands behaviour that may impact large equipment design, operational and maintenance strategies. IntroductionThe mechanical behaviour of oil sands in the underfoot and in the face yields some of the harshest stability and digging conditions of any mining environment. High maintenance costs from truck and shovel fatigue failures predominate as a result of ground stability issues. Wear rates of shovel and dozer ground engaging tools (GET), rollers, roller paths and crusher screens result in costly and frequent replacement, or even more frequent and costly sacrificial wear zone building. From the shovel face to the crushers and screens, dry oil sands mechanics affects the degree of fragmentation and, ultimately, bitumen production.An increased knowledge of the behaviour of oil sands with respect to stability, fragmentation and abrasion, etc. would enhance the long-term equipment design process at the vendor level, and provide the end user with improved short-term operational guidelines and long-term strategies for future purchases and operation. Truck vendors recognize that the interaction between operator, seat, frame, suspension, tires and oil sands is unclear, and must be better understood before proceeding to next generation designs. Similarly for shovel manufacturers, the relationship between bucket/dipper motion, carbody, side frame, rollers, track and oil sands follow in the same vein."

Jan 1, 2002

By B Dold

Western Europe is a dynamic region, with an emerging co-operation between the individual nations both politically, economically, technically and scientifically. The European Union, today with 15 member States and with a range of central European States applying for membership, is a catalyst for this Cupertino, using a combination of EU funds, for financing research initiatives, and legislation to enhance development of technology and environmental performance. Europe is a major net importer of metals but with a large potential for own production, in particular in the accession countries. The metals and mining sector is furthermore identified as having a large potential to generate wealth both in todayÆs EU and in the future, widened Union. This paper provides a chart of examples on the many research initiatives presently underway in Europe, addressing environmental issues related to mining. The list of programmes and projects does not claim to be complete; it is rather an illustration on the wideness of the approach, describing various ways for transboundary Cupertino. The approach taken by many of the programmes goes beyond the strict ARD scientific area and therefore only a limited number of the many programmes can be identified as ARD research programmes. Also national programmes, without EU funding, are operating, eg in Sweden, Germany, and UK. The picture is continuously changing with new programmes being commissioned and old ones being completed.

Jan 1, 2003

By G. W. Preckshot, J. W. Gorman

MOLTEN metals offer an excellent medium for the study of molecular diffusion and interphase transfer. In the absence of intermetallic compound formation, solutions of molten metals are solutions of elements. Therefore, complicating factors such as molecular structure, dissociation, association, polarization, and so on, are generally absent. Further, metals remain in the liquid state over a wide range of temperature. Thus, the effect of temperature on transport processes can be studied in more detail. Although some data are available for the diffusion of metals in the molten state at high temperatures,"""".'!' the most useful and accurate data are those for the diffusion of various elements in mercury at room temperature. The effective radius of diffusion for the various elements in mercury may be calculated from the Stokes-Einstein relation.'-These calculated radii are compared with the atomic and ionic radii calculated from X-ray data on crystals." The effective radii of diffusion of the alkali and alkali-earth metals correspond to those of the neutral atom; those of cadmium, silver, lead, zinc, thallium, bismuth, and tin correspond to ionic radii; and those of copper and gold indicate larger radii due to association with mercury or more likely, faulty diffusion data. Independent evidence"' supports the notion that alkali metals are uncharged in amalgams. The concept of metals moving free of their conductance electrons in the liquid state has been discussed by Eyring, et al,'" in connection with studies on the viscosity of pure molten metals. Considering the approximate nature of the tabulated atomic and ionic radii and the variance in the diffusion measurements, the application of the Stokes-Einstein equation to the diffusion of metals in mercury gives gratifying results. It is noted that a number of these metals have article radii eaual to or less than those of the solvent mercury.".'*,"' Soba1,'" sing the inaccurate Roberts-Austin20 data, indicated that the effective radius of diffusion might well be a function of temperature. Additionally in studies of mass transfer between phases, many conflicting opinions have been expressed concerning the assumption of equilibrium at the interface." ,","," The results of the present work on the diffusion of solid copper in molten lead throws light on the tempera- ture variation of the diffusion radius as well as the extent of the interfacial resistance. The theoretical background and experimental procedure are presented here in detail. Results on other systems will be presented in subsequent papers. Nomenclature The following nomenclature is used in the paper: A—cross-sectional area of diffusion column, sq cm C, C,—concentration of solution and saturated solution respectively, g per cc D,D'—-diffusivity, sq cm per sec e—Naperian base h—ratio, k/D k—mass-transfer coefficient, cm per sec L—diffusion column length, cm n—series index q—flux, g per sq cm-sec r—radius, cm or A R—-gas constant t—time, sec T—temperature, K V—volume, cc w—weight of copper-lead alloy on copper cylinder WT—-total copper transferred to lead diffusion, column, g Z—distance from top of diffusion column, cm 2'—distance from copper-lead interface, cm (2' = L-2) u,,—roots of diffusion equation Mathematical Apparatus The model shown in Fig. 1 applies to the diffusion of solid copper into molten lead. Here Fick's first law may be written where all terms are defined in the nomenclature. It is assumed that the volume of the lead column is constant. This is justified since experimental densities compared favorably with calculated densities based on perfect interstitial mixing. Thus there is no counter diffusion of lead. It is clear that 2 in Equation [I] should be measured relative to the interface which moves relative to the diffusion cell but not to the liquid phase. Hence, the frame of reference is the plane of the copper-lead interface. The diffusivity calculated at constant volume, D", is that defined by Hartly and Crank" and is designated herein as D. No Interfacial Resistance—The two situations of the presence and absence of interfacial resistance will be treated. The simplest is the latter which re-

Jan 1, 1959

By K. L. Marshall

A facetious title was purposely given this talk, so that a formal paper would not be expected. TWO or three days ago, while discussing with Mr. Dickinson some of the details of the dust explosion demonstrations we are planning for this coming Saturday, I remarked that we would like to have as many people as possible see some samples of 20 and 200 mesh dust, so they would more fully understand just what was causing the explosions. Mr. Dickinson requested that I bring samples and screens and in this informal manner, give you all a ".close-up" of coal dust which is considered in Explosion Hazard reports. While sampling mines, for road, rib, and roof dust, in connection with safety service and hazard reports which the Bureau of Mines Engineers make at the request of coal operators, I have often been assisted by under- ground mine officials or other men of many years experience and on almost every occasion, while we were carefully brushing the very fine dust from timbers or coal surfaces, they would make some remark such as: "never had noticed this kind of dust, didn't know it was here", or "well, that's the first time I really understood what all 'this dust talk was about." Such experience makes me believe that the much published terms, 20 mesh and 200 mesh are just numbers to the great majority of both miners and operators. We are now going to have lesson one in the primer of coal dust explosions and I want to say, in all sincerity that a complete course in the hazards of mining is deserving of a place in the curriculum of the best mining schools of this country. Sample No. 1 is fine coal and dust and is a fair sample of what can be found every where in rooms and entries of a mine, as it is too small to be gathered up with a shovel and is left in the ordinary mining at the faces and is spilled along the entries in haulage. In this you will see some quarter inch coal, much eighth and sixteenth inch coal, in fact those are the sizes I find many people have in mind when they are asked about the dust made in mining. Although the sizes mentioned are the ones which seem to almost entirely make up this sample, such is not the case, for from 10 to 20% of such a sample will usually pass this 20 mesh screen and in Sample No. 2 we have 20 mesh dust. Result of many tests, supports .the statement of the coal mining division of the Bureau, that it is quite probable that coal over 20 mesh does not take part in any but the most violent of explosions and that all dust under 20 mesh may take part in any explosion. The largest particles in this sample will not be over .03 inches in their largest dimension and a pound of dust to a foot of average heading is very easily found in most every mine I have visited and usually a great deal more can be readily gathered up. It was .found early that the finer the dust the more dangerous it was for a given coal. So for the early explosion tests conducted by the Bureau a commercial pulverizer was used and it turned out a 20 mesh dust of which about 75% would pass 200 mesh. Some men question whether the ordinary mining methods made such a dust and so doubted the explosibility of the dust in their own mines. The question was well taken, and hundreds of dust samples were taken by the field men of the Bureau to determine the kind of dust being made in all methods of mining and all classes of coal. The result of such sampling showed some coals. resisted breakage more than others and that actual mine road dust, through 20 mesh, would show from 10 to 20% through 200 mesh, and for actual rib and roof dust through 20 mesh, they would get from 20 to 40% of 200 mesh dust. In testing the

Jan 1, 1924

By W. D. Mcmillan

Although the Shafter district of Presidio County, Tex., is principally renowned for silver production from the Presidio mine, the occurrence of lead-zinc ores in the western part of the district has been known for at least 50 years, and there has been some production. An area of about 3 square miles in the vicinity of an extending westward from the Presidio mine was investigated in detail by C. P. Ross of the Federal Geological Survey in 1934. In the fall of 1943, A. B. Needham, an engineer of the Bureau of Mines, called the attention of the Geological Survey to the area west of that included in Ross's map, and requested a detailed investigation of that area by the Survey in advance of development by the Bureau of Mines. After a brief reconnaissance by the Survey in the spring of 1944, detailed studies were made by Federal geologists in the summer of 1944, during which about 450 acres were surveyed, on a scale of 1 inch to 100 feet. Recommendations for the exploration of certain parts of the area were made in the accompanying report.

Jan 1, 1949

By J. D. Davis

THIS report gives results of an investigation of the carbonizing properties of the following eastern Kentucky coals: Elkhorn No. I bed, No. 28 mine, Wayland, Floyd County; Elkhorn No. 2 bed, Turner No. 5 mine, Drift, Flood County; Leatherwood (Haddix No. 5) bed, Leatherwood mine, Leatherwood. Perry County; and Harlan bed, Path Fork mine, Path Fork, Harlan County. The carbonizing properties were determined by Bureau of Mines-American Gas Association (BM-AGA) tests at 800° and 900° C. and by expansion tests in the sole-heated oven. Plastic properties were determined by tests in the Gieseler and Davis plastometers. The coals were tested singly and as blends with 20- and 30-percent low-volatile Pocahontas No. 3 coal. The dry, mineral-matter-free, fixed-carbon content of the carbonizing samples ranged from 56.7 percent for Elkhorn No. 2 to 59.7 percent for Leatherwood, and the heating values on the moist, mineral-matter-free basis ranged from 14,420 B. t. u. per pound for Elkhorn No. 2 to 14,720 for Harlan. The percentage of ash ranged from 2.9 to 6.1. The fluidity of three coals, measurer. In the Gieseler plastometer, ranged from 230 to 670 dial divisions; the fluidity of Elkhorn No. 2 could not be determined by this method. Blending lowered the fluidity of each coal; the fluidity of the blends containing 20 and 30 percent Pocahontas No. 3 ranged from 16 to 53 and from 8 to 17 dial divisions, respectively. Agglutinating values determined on silicon carbide-coal mixtures in the ratio 15:1 ranged from 3.8 to 6.3.

Jan 1, 1952

By A. R. Harrington

BEFORE discussing some of the technical aspects of the steam generating plants of Nova Scotia Light and Power Company, Limited, it might be of interest to go back through history and see the development of steam generation in this public utility. Back around 1902 Nova Scotia Light and Power Company, Limited, had three slide-valve engines in-stalled at its Water Street, Halifax, generating station for a total capacity of 1,800 kilowatts. The plant remained at about this size until 1910 and in 1911 a 2,000 kilowatt steam turbine was installed to raise the total capacity of the plant to 3,800 kilowatts. In 1916, a 3,000 kilowatt turbine was installed and one of the slide-valve engines was removed to make a total plant capacity of 6,200 kilowatts. The total demand in the Company's service 8rea was at that time 4,000 kilo-watts.

Jan 1, 1958

The importance of reducing the moisture content of fine coal, the nature of the retained water, and the means of its removal are discussed. A statistical technique, using a balanced block design, was used to isolate the significant factors determining water content of a coal filter cake. The most significant factor was particle size distribution. A simplex evolutionary operation (evop) was used to determine the optimal quantities of additives required to produce the lowest moisture content for a selected coal size. For this optimum condition (18·6 Ib H20 per lOO Ib dry coal), additions of 0·045 Ib magnesium ion, 0·0026 lb Separan AP30, and 0·098 Ib Aerosol OT, per lOO Ib dry coal were required. The work illustrated the uses of a statistical evop technique for the determination of optimal conditions in industrial research projects.

Jan 1, 1970

By The Satff

"TEXADA Island is situated in the Strait of Georgia, about 100 miles northwest of Vancouver. The property of Texada Mines Ltd. lies on the southwest coast of the northern end of the Island. A part of the ""Sunshine Coast,"" the climate is moderate, with about 30 inches of rain during winter months and relatively dry summers. Texada has been shipping high-grade magnetite concentrate continuously since 1952 to Japanese ore buyers. In 1959, a 3,000-foot tunnel was driven just above sea level to explore the possible downward extension of known orebodies then being mined by open pit. In January of 1961, because the open-pit operations had a limited life, C. C. Huston and Associates were brought in as mining consultants to do a feasibility study on the possibility of going underground for production. This study was completed in March, 1961. With the completion of the report, the Company went to Japan seeking a ,long-term contract to justify the capital outlay necessary for setting up an underground operation. Concurrently, underground diamond drilling revealed more ore, and the Company planned some modifications to the concentrator for increasing the copper recovery. By November, 1961, a ten-year contract was signed with Japanese ore buyers for the sale of 450,-000 long tons of concentrates beginning in October, 1963. Since that time, the Company has built its own 65 000-ton ore carrier and an additional three-year contract has been negotiated, with an annual tonnage increase of from 450,000 to 550,000 tons."

Jan 1, 1967

By B. H. Kim

It is hypothesized that the standard approach adopted to characterize the ground and to determine the rock strength properties at depth are flawed and generally tend to underestimate the rock strength and possibly the stiffness, particularly when the rock mass is characterized as massive to moderately jointed or blocky to very blocky. It is therefore necessary to conclusively established that the hypothesis, that the rock strength in highly confined rocks is greater than generally anticipated, is actually valid and generally applicable, and then to develop new procedures to establish rock parameters that can be reliably used for the design of deep excavation.

May 1, 2009

By J. W. Hunter, J. H. Jacobs

"Approximately 355 tons of nodules from Chamberlain; S. D., ore were processed in the 1-ton-per-day electrolytic-manganese pilot plant of the Bureau of lanes at Boulder City, Nev., in a continuous 3-month operation. The ore, ground to minus 48-mesh, was found to be amenable to leaching with acid directly or after roasting under reducing conditions in a Skinner muffled multiple-hearth furnace.Unroasted ore gave an acid-leach extraction of 84 to 88 percent of the manganese, which after neutralization showed an over-all extraction of between 81 and 85 percent of the manganese. The amount of iron extracted varied, but it was always,enough to permit the use of ammonia for neutralization.Roasted ore showed an acid-leach extraction of 89 to 91 percent of the manganese. A large amount of iron went-into solution, so that it was not economical to neutralize it entirely with ammonia. By neutralizing with calcine to a pH of 5.0 and completing -neutralization with ammonia to a pH of a.5 an over-all manganese extraction of 84 to 86 percent was obtained. The slight increase in. extraction on roasted ore probably would not justify the cost of roasting.Acid consumption averaged 1.75 pounds per pound of manganese extracted. Settling rates of the residue in leach solution were to slow to permit clarification in thickeners, but a Moore vacuum leaf filter proved to be satisfactory. Purification of raw leach solution was .accomplished readily by hydrogen sulfide with a low gas consumption. Electrolysis was normal, without difficulty, and with -current efficiency ranging between 62 and 66 percent.The use of Chamberlain modules for the production of electrolytic manganese would result in an operating cost of 0.8316 cent per pound higher than the cost of producing electrolytic manganese from Three Wids ore."

Mar 1, 1946

By Lowell L. Patten

The Federal Bureau of Mines participated with the National Aeronautics and Space Administration and Martin Marietta Aerospace in developing, building, and testing a portable X-ray fluorescence spectrometer for use as an analyzer in mineral-resource investigative work. The prototype battery-powered spectrometer, measuring I1 by 12 by 5 inches and weighing only about 15 pounds, was designed specifically for field use. The spectrometer has two gas-proportional counters and two radioactive sources, 109Cd and 55Fe. Preliminary field and laboratory tests on rock specimens and rock pulps have demonstrated the capability of the spectrometer to detect 33 elements, to date. Characteristics of the system present some limitations, however, and further improvements are recommended.

Jan 1, 1982