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This report describes the development, installation and performance of a lonpwall illumination system. The longwall illumination system was installed at the Greenwich Collieries 112, Cockport, Pa. It utilized flourescent luminaires, intrinsically safe power distribution and is the first longwall system installed in Pennsylvania.

Jan 1, 1976

By Bradford F. Townsend, Marc R. Kritzer, Michael F. Roach, Dennis Ofiara

All Rights Reserved. Printed in the United States of America. Information contained in this work has been obtained by SME, Inc. from sources believed to be reliable. However, neither SME nor its authors guarantee the accuracy or completeness of any information published herein, and neither SME nor its authors shall be responsible for any errors, omissions, or damages arising out of use of this information. This work is published with the understanding that SME and its authors are supplying information but are not attempting to render engineering or other professional services. If such services are required, the assistance of an appropriate professional should be sought. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Any statement or views presented here are those of the authors and are not necessarily those of SME. The mention of trade names for commercial products does not imply the approval or endorsement of SME.

Dec 1, 2008

By E. C. Potter

FUEL-OIL was first substituted for coal at these works in September, 1888. It was first applied in the converting-department to the battery of boilers, consisting of 14 tubular boilers, 16 feet in length by 5 feet in diameter. To operate these boilers with coal for 24 hours required 14 strikers, 3 ash-wheelers, 6 men unloading coal, and 2 water-tenders, making a total of 25 men. With fuel-oil the same boilers require for the same period 2 water-tenders and 4 men to attend to the burners, making a total of 6 men. This gives a saving of 19 men, which, at an average of $2 per day each, amounts to $38 per day. Comparing the consumption of oil with that of coal, we find that for the week ending January 5, 1889, with an ingot output of 6403 tons, 2731 barrels of fuel-oil were used as against a necessary consumption of coal for the same work of 848 tons, showing 3.22 barrels of fuel-oil to be equivalent to one ton of Indiana block-coal. Figuring oil at 60 cents per barrel, and coal at $2.15 per ton, we have as the cost of oil $1.93, as against $2.15 for its equivalent in coal. In December, 1888, the rail-mill battery of 26 boilers, of the same dimensions as those in the converting-department, was equipped for fuel-oil. For the week ending January 5, 1889, with a rail out-put of 5208 tons, 5987 barrels of oil were consumed, as against a necessary consumption of coal, to do the same work, of 1805 tons, showing 3.31 barrels of fuel-oil to be equivalent to one ton of Indiana block-coal, which at the costs named above would show $1.98 worth of fuel-oil to he equal to $2.15 worth of coal. The labor required to operate the rail-mill boilers for 24 hours, with coal as fuel,is: 26 stokers, 4 water-tenders, 6 ash-wheelers, 12 men unloading coal; total, 48 men. With oil as fuel, the same work requires 4 water-tenders and 6 men to attend to the burners; total, 10 men; a saving over coal of 38 men in 24 hours, which, at an average price of $2 per day, would be $76 per day. In the brief experience we have had with oil as fuel, we find that the efficiency of the boilers is somewhat increased and the repairs are

Jan 1, 1889

By Earl S. Greiner, Eric R. Jette

ALTHOUGH the mechanical and chemical characteristics of certain iron-nickel-silicon alloys have been investigated,1 the available literature shows no results of a systematic investigation of the constitution of this system. This paper describes the results of an X-ray investigation of the constitution of the iron-rich iron-nickel-silicon alloys at 600°C. Data on the constitution of the included binary systems obtained in other investigations have been correlated with the structure of the ternary alloys. Jette and Foote2 have presented a tentative constitutional diagram of the iron-nickel system following X-ray studies on quenched specimens. This diagram shows that the alloys at 600°C. containing from zero to approximately 4 atomic per cent nickel consist of a body-centered cubic (alpha) phase, the alloys containing 4 to 24 atomic per cent nickel consist of body-centered cubic (alpha) and face- centered cubic (gamma) phases, and the alloys containing from 24 to 100 atomic per cent nickel consist of a face-centered cubic (gamma) phase. These investigators recognized that it was not possible to retain the gamma phase in equilibrium by quenching alloys containing less than approximately 25 atomic per cent nickel and that high-temperature X-ray methods were desirable to determine the gamma-phase solubility limit. In a later investigation of the iron-nickel alloys, Owen and Sulley3 determined the alpha-phase solid solubility limit to be 3.5 atomic per cent nickel at 600°C. High-temperature X-ray methods showed the solid solubility limit of the gamma phase to be 14 atomic per cent nickel at 600°C. Since the high-temperature X-ray method should reveal equilibrium conditions in these alloys better than the quench method of other investigators, the results of Owen and Sulley pertaining to the gamma-phase boundary are to be preferred. As the result of an X-ray investigation of quenched iron-silicon alloys, Greiner and Jette4 have shown these materials to consist of a body-centered cubic (alpha) phase containing from o to 26.4 atomic per cent silicon at 600°C. The alloys containing from 26.4 to approximately 50 atomic per cent silicon consist of two phases at 600°C.; namely, alpha and eta. The eta phase corresponds to the stoichiometrical formula FeSi (33.4 wt. per cent Si).* The literature pertaining to the constitution of the nickel-silicon alloys has been reviewed by Ackerman,5 who found disagreements in the results of various investigators on several parts of the system. Subsequent data on the constitution of the nickel-silicon alloys were reported by Osawa and Okamoto.6

Jan 1, 1943

By Eric R. Jette, Earl S. Greiner

Although the mechanical and chemical characteristics of certain iron-nickel-silicon alloys have been investigated,1 the available literature shows no results of a systematic investigation of the constitution of this system. 'This paper describes the results of an X-ray investigation of the constitution of the iron-rich iron-nickel-silicon alloys at 600°C. Data 011 the constitution of the included binary systems obtained in other investigations have been correlated with the structure of the ternary alloys. Jette and Foote2 have presented a tentative constitutional diagram of the iron-nickel system. following X-ray studies on quenched specimens. This diagram shows that the alloys at 600°C. containing from zero to approximately 4 atomic per cent nickel consist of a body-centered cubic (alpha) phase, the alloys containing 4 to 24 atomic per cent nickel consist of body-centered cubic (alpha) and face-centered cubic (gamma) phases, and the alloys containing from 24 to Ioo atomic per cent nickel consist of a face-centered cubic (gamma) phase. These investigators recognized that it was not possible to retain the gamma phase in equilibrium by quenching alloys containing less than approximately 25 atomic per cent nickel and that high-temperature X-ray methods were desirable to determine the gamma-phase solubility limit. In a later investigation of the iron-nickel alloys, Owen and Sulley3 determined the alpha-phase solid solubility limit to be 3.5 atomic per cent nickel at 600°C. High-temperature X-ray methods showed the solid solubility limit of the gamma phase to be 14 atomic per cent nickel at 600°C. Since the high-temperature X-ray method should reveal equilibrium conditions in these alloys better than the quench method of other investigators, the results of Owen and Sulley pertaining to the gamma-phase boundary are to be preferred. As the result of an X-ray investigation of quenched iron-silicon alloys, Greiner and Jette4 have shown these materials to consist of a body-centered cubic (alpha) phase containing from o to 26.4 atomic per cent silicon at 600°C. The alloys containing from 26.4 to approximately 50 atomic per cent silicon consist of two phases at 600°C.; namely, alpha and eta. The eta phase corresponds to the stoichiometrical formula FeSi (33.4 wt per cent Si)." The literature pertaining to the constitution of the nickel-silicon alloys has been reviewed by Ackerman,' who found disagreements in the results of various investigators on several parts of the system. Subsequent data on the constitution of the nickel-silicon alloys were reported by oSawa and okamoto.6

Jan 1, 1943

By Charles T. Baroch, Charles J. Baroch

In 20 years of commercial development, nuclear reactors have demonstrated that they are a safe, dependable, and economical source of power. Operating experience with commercial power reactors has firmly established nuclear power as a practicable source of energy. For both boiling-water (BWR) and pressurized-water (PWR) reactors, performances to date have generally met design predictions. Furthermore, it has become possible to analyze and understand the nuclear, chemical, and physical behavior of this class of reactors. The United Kingdom has had similar success with gas-cooled reactors. The Experimental Boiling Water Reactor (EBWR), the first United States experimental power reactor, began operation in 1956. It proved to be capable of supplying 4500 kw (kilowatts) of power. This reactor was followed in 1957 by the Pressurized Water Reactor at Shippingport, Pa. It was the nation's first full-scale central-station nuclear power plant and the first in the world designed exclusively for the production of civilian electric power. The Shippingport reactor was originally designed to produce 60 megawatts (MW) of electricity, and it was increased to 100 MW in 1964. In 12 years of operation, this reactor generated over 4.5-million MW-hr of electricity in spite of many shutdowns for experimental alterations. By 1969, a total of 15 central-station nuclear power reactors were operable in the United States with an aggregate electrical capacity of over 4200 MW. Early in 1964, Jersey Central Power & Light Co. announced plans for constructing a 515-MW nuclear plant at Oyster Creek, N.J., to be built without government financial assistance. The company stated that a nuclear plant had been selected competitively with fossil fuel. Their economic analysis stated that the plant would generate electricity at less than 4 mills per kw-hr, competitive with coal at 200 per million Btu (British thermal units). Coal cost in 1964 for that region averaged 26.00 per million Btu. The Jersey Central report created wide interest in public-utility circles; nevertheless, no other nuclear plants were announced in 1964. However, in 1965, six nuclear plants were announced by utilities, followed by 26 in 1966, 29 in 1967, and 10 in 1968. By Sept. 30, 1969, 97 reactors were operable, being built, or planned. The cost of these, all committed by electric utilities, was estimated at about $12 billion. When constructed, they will have an electrical capacity of 72,000 MW. The unprecedented surge in power reactors that started in 1965 tapered in 1968, and only seven reactors were announced in

Jan 1, 1976

By Earl S. Greiner, Eric R. Jette

Although the mechanical and chemical characteristics of certain iron-nickel-silicon alloys have been investigated,1 the available literature shows no results of a systematic investigation of the constitution of this system. 'This paper describes the results of an X-ray investigation of the constitution of the iron-rich iron-nickel-silicon alloys at 600°C. Data 011 the constitution of the included binary systems obtained in other investigations have been correlated with the structure of the ternary alloys. Jette and Foote2 have presented a tentative constitutional diagram of the iron-nickel system. following X-ray studies on quenched specimens. This diagram shows that the alloys at 600°C. containing from zero to approximately 4 atomic per cent nickel consist of a body-centered cubic (alpha) phase, the alloys containing 4 to 24 atomic per cent nickel consist of body-centered cubic (alpha) and face-centered cubic (gamma) phases, and the alloys containing from 24 to Ioo atomic per cent nickel consist of a face-centered cubic (gamma) phase. These investigators recognized that it was not possible to retain the gamma phase in equilibrium by quenching alloys containing less than approximately 25 atomic per cent nickel and that high-temperature X-ray methods were desirable to determine the gamma-phase solubility limit. In a later investigation of the iron-nickel alloys, Owen and Sulley3 determined the alpha-phase solid solubility limit to be 3.5 atomic per cent nickel at 600°C. High-temperature X-ray methods showed the solid solubility limit of the gamma phase to be 14 atomic per cent nickel at 600°C. Since the high-temperature X-ray method should reveal equilibrium conditions in these alloys better than the quench method of other investigators, the results of Owen and Sulley pertaining to the gamma-phase boundary are to be preferred. As the result of an X-ray investigation of quenched iron-silicon alloys, Greiner and Jette4 have shown these materials to consist of a body-centered cubic (alpha) phase containing from o to 26.4 atomic per cent silicon at 600°C. The alloys containing from 26.4 to approximately 50 atomic per cent silicon consist of two phases at 600°C.; namely, alpha and eta. The eta phase corresponds to the stoichiometrical formula FeSi (33.4 wt per cent Si)." The literature pertaining to the constitution of the nickel-silicon alloys has been reviewed by Ackerman,' who found disagreements in the results of various investigators on several parts of the system. Subsequent data on the constitution of the nickel-silicon alloys were reported by oSawa and okamoto.6

Jan 1, 1943

By K. L. Sutherland, J. Rogers

The relationships between collector and mineral, activator and mineral, and activator, collector and mineral will be considered herein. We propose to criticize current theories of flotation but we will not repeat the many pertinent arguments presented by Wark and Cox28 in 1937 in which the "chemical" or more strictly the "solubility" theory proposed by Taggart and co-workers22 is shown to be untenable. Recently Taggart, Arbiter and Kellogg24 have studied the long-chain aliphatic amines as collectors and have attempted to resuscitate the solubility theory for these particular collectors. Dean and Ambrose3 have felt that "we stumble over words" when we distinguish different mechanisms of adsorption. Our view is that nothing is more stultifying to the development of a science than attempts to force widely different phenomena into one classification. This oversimplification leads immediately to difficulties in the interpretation of results. Experimental Procedure The response of minerals to activator and collector was determined by "captive-bubble" tests. The methods of preparation of specimens26 and of testingin have been previously described. Results from captive-bubble tests were confirmed by flotation tests in glass-stoppered cylinders.26 The full lines shown in the figures relating solution composition to contact (flotation) distinguish solutions in which contact (flotation) is possible from those in which it is not. The curve is derived by successive approximation and the accuracy is ±o.2 pH units and ±5 mg. per liter of collector or depressant. Solution compositions for which it was shown experimentally that contact or flotation is possible are marked by a circle, those for which it is not possible by a cross and those for which it is doubtful by a cross within a circle. It is assumed that at all other solution compositions within (without) the curve, contact or flotation is possible (not possible). After testing in the collector solution, the mineral was removed, washed, and tested by the captive-bubble method in water, or floated in a cylinder with frother only. In this way the composition of solutions in which a mineral was conditioned but in which properties of the collector solution prevented contact or flotation can be defined. The composition of solutions in which conditioning was possible lie between the full and broken curve, the experimental results being indicated on the figures by a square. The curves show the limits of composition of solution in which flotation in a cell would be possible. Many factors other than those considered in these tests determine recovery or grade of a given mineral in practice.

Jan 1, 1947

By J. Rogers, K. L. Sutherland

The relationships between collector and mineral, activator and mineral, and activator, collector and mineral will be considered herein. We propose to criticize current theories of flotation but we will not repeat the many pertinent arguments presented by Wark and Cox28 in 1937 in which the "chemical" or more strictly the "solubility" theory proposed by Taggart and co-workers22 is shown to be untenable. Recently Taggart, Arbiter and Kellogg24 have studied the long-chain aliphatic amines as collectors and have attempted to resuscitate the solubility theory for these particular collectors. Dean and Ambrose3 have felt that "we stumble over words" when we distinguish different mechanisms of adsorption. Our view is that nothing is more stultifying to the development of a science than attempts to force widely different phenomena into one classification. This oversimplification leads immediately to difficulties in the interpretation of results. Experimental Procedure The response of minerals to activator and collector was determined by "captive-bubble" tests. The methods of preparation of specimens26 and of testingin have been previously described. Results from captive-bubble tests were confirmed by flotation tests in glass-stoppered cylinders.26 The full lines shown in the figures relating solution composition to contact (flotation) distinguish solutions in which contact (flotation) is possible from those in which it is not. The curve is derived by successive approximation and the accuracy is ±o.2 pH units and ±5 mg. per liter of collector or depressant. Solution compositions for which it was shown experimentally that contact or flotation is possible are marked by a circle, those for which it is not possible by a cross and those for which it is doubtful by a cross within a circle. It is assumed that at all other solution compositions within (without) the curve, contact or flotation is possible (not possible). After testing in the collector solution, the mineral was removed, washed, and tested by the captive-bubble method in water, or floated in a cylinder with frother only. In this way the composition of solutions in which a mineral was conditioned but in which properties of the collector solution prevented contact or flotation can be defined. The composition of solutions in which conditioning was possible lie between the full and broken curve, the experimental results being indicated on the figures by a square. The curves show the limits of composition of solution in which flotation in a cell would be possible. Many factors other than those considered in these tests determine recovery or grade of a given mineral in practice.

Jan 1, 1947

By E. P. Klier, S. M. Grymko

The transformations in eutectoidal systems have been extensively studied as they occur in steels.&apos; As a consequence of these studies the martensite, bainite and pearlite reactions found for most steels are widely recognized. Further, because of the work of Smith and Lindlief2 and of Greninger and Troiano3 these reactions, except for the bainite reaction, are considered as typical for all eutectoidal systems. The primary alloy studied by Smith and Lindlief2 was a CuAl alloy of near eutectoid composition as was the alloy more recently studied by Mack.4 The transformations in these alloys were, for the most part, studied metallo-graphically, while an X ray analysis of structures was essentially wanting. It has appeared desirable, therefore, to investigate selected CuAl alloys at and slightly away from eutectoid composition. For this purpose three alloys were prepared containing 10.5,11.9 and 13.5 pct A1 respectively. The results of a metallographic and X ray analysis of structures obtained for isothermal transformation of the ß-phase are reported here for the 11.9 and 13.5 pct A1 alloys. Introduction The phase equilibria in the CuAl alloys of immediate concern are indicated in the equilibrium diagram section presented in Fig 1.5 The equilibrium and transition structures which have been reported in this system are as follows: a = copper rich terminal phase (f.c.c.) ß = high temperature eutectoidal phase (b.c.c.) r2 = aluminum-rich intermediate phase (r-brass structure) a&apos; = modified a-phase postulated by Bollenrath and Bungnrdt.26 ß1 = ordered ß (b.c.c.) ß&apos; = martensite structure: A1 < 13 pct (near h.c.p.) ß" = ß&apos; of Smith and Lindlief2 7&apos; = martensite structure: A1 > 13.5 pct (h.c.p.); ß2 of Bollenrath and Bungardt.26 The eutectoid transformation can be suppressed at sufficiently high cooling velocities. The ß-phase is then retained to about 500°C where ordering sets in. The ordering interval is not satisfactorily known but indirectly appears to be non-suppressible. Subsequent to the ordering reaction and consequently at lower temperatures, the ordered ß1 decomposes to a marten-sitic structure. The kinetics of these reactions and in particular those of the martensite reaction have an important bearing on the results obtained in this investigation. Since some confusion exists concerning certain reported aspects of these reactions, they will be considered in some detail. THE MARTENSITE REACTION The martensitic structure is formed on cooling through a critical range6

Jan 1, 1950

By S. M. Shelton, A. L. Engel

"This report presents the results of investigations of ore-testing projects assigned to the Ore-Dressing Section, Metallurgical Division, Bureau of Mines, at the Mississippi Valley Experiment Station, Rolla Mo. During the fiscal year ended June 30, 1941.The manner of approving ore-testing projects has been explained in a previous reports. 4/ The testing procedures likewise have been described. 5/The treatment methods described are based upon laboratory experiments with small amounts of sample and naturally are subject to the inherent, normal, limiting conditions of such procedure. It is not intended to describe treatments in detail, but rather to indicate applicable methods. Local operating conditions, when the laboratory results are applied to plant operations, may require further study. Large-scale pilot-plant tests should be made before commercial operations are begun, so that translation from the experimental stage will yield satisfactory results."

Mar 1, 1942

The investigations reported herein comprise preliminary studies to evaluate large scale mining systems adaptable to the thicker oil shale deposits in the deeper central portion of the Piceance Creek Basin. The studies include an evaluation of the geology, hydrology and resources of the Basin., evaluation of a potential prototype mine site, synthesis of rock mechanics data on Green River Formation oil shale, selection and preliminary design and cost evaluation of six potential mining systems and a ranking analysis to aid in selecting the most promising system. Results of the ranking analysis indicate the following four systems to be most promising for large scale underground oil shale mining: - Chamber and pillar (using spent shale backfill) - Sublevel stoping with spent shale backfill - Sublevel stoping with full subsidence - Block caving with LHD&apos;s Recommendations for phase II are to investigate the above systems in greater detail, refine present cost data, and perform economic evaluations of oil shale mining using these systems.

Jan 1, 1975

By Thomas P. Dolley

Building stone, cassiterite, kaolin, gold, lime, and peat were the only commodities mined, The country&apos;s main economy was in agriculture, primarily in coffee exports. Tribal violence occurred again, between the Hutu and Tutsi tribes, causing an estimated 50,000 deaths, mainly in rural and mining areas. The inflation and a large deficit continued. The country continued to import cement, fertilizers, oil, and petroleum products. Burundi possessed numerous small gold deposits. The northwest and north-east were the country&apos;s two most important gold-bearing regions. A large kaolin deposit was found at Ngozi, and its mining was specified in the fifth 5-year development plan for 1988-1992. In the area of Rugombo, limestone was being explored with the intention of opening a cement plant.

Jan 1, 1990

By George W. Toth

Uranium in situ leach mining has recently emerged as a viable alternative to conventional miring techniques. The cost implications of in situ mining are therefore of increasing interest to mining paracticioners as well as public officials. This report presents the results of an assessment of uranium in situ leach mining costs through the application of process engineering and discounted cash flow analysis procedures. A computerized wasting technique, termed a cost model, was developed through this effort to facilitate rapid cost analyses. Application of this cost model will generate mine life capital and operating costs as well as solve for economic production cost/lb. U308. Conversely rate of return may be determined subject to a known selling price. The data bases of the cost made! have been designed to reflect variations in Texas vs. Wyoming site applications. The results If applying the model under numerous ore deposit, operating, wellfield and extraction plant conditions for Texas and Wyoming are summarized in the report. Sensitivity analysis of changes in key project parameters have also been tested and reported.

Jan 1, 1981

By J. C. Norman

The United States was the world’s largest producer and consumer of boron compounds during 1995. According to estimates from the US Geological Survey(USGS), boron mineral concentrate and chemical production in the United States totaled an estimated 1.1 Mt(1.2 million st) yielding 602 kt (663,000 st) of B2O3 for an estimated value of $462 million. This level of production exceeded 1994 revised production figures by about 9%. The United States continued to provide nearly all its own boron supply while maintaining a strong position as a source of sodium borate products and boric acid to foreign markets. During 1995, about 900 people worked in domestic boron mines and plants, about the same as in1994. USGS estimated total world production of boron during 1995 to be about 3 Mt (3.3 million st), yielding about 1.6 Mt (1.8 million st) of B2O3. World production in 1995 was about equal to revised 1994 levels.

Jan 1, 1996

By Carl C. Nesbitt

A process has been developed to recover and recycle metals from wastes of brass foundries which contain copper, zinc and lead in various quantities. Tests were conducted to evaluate several leachants, including sulfuric acid, ammonia, hydrochloric acid, cyanide and acetic acid, and to determine the optimum leaching conditions, such as air flow rate, initial copper ion concentration, temperature, and agitation strength. Sulfuric acid containing copper sulfate with dissolved oxygen is the most successful leachant. More than 99% of the copper and zinc originally present in the waste was dissolved, while only 0.5% of the lead entered the solution after 14 hours of leaching. The leaching mechanisms of copper, zinc, and lead are proposed. The copper and zinc can be recovered from the solution by electrolytic processing. The unleached residue may be converted to a lead carbonate which can be converted to litharge at 400-450°C and to massicot at temperature above 500°C by calcination.

Jan 1, 1995

By G. Van Weert

In the spring of 2010 double refractory ores from historical stockpiles were processed through Barrick&apos;s Goldstrike pressure oxidation facility, thereby providing preg robbing feeds for a variety of metallurgical testwork. This paper describes the effects of amount, type, place and time of addition of activated carbons on CIL gold recovery and shows that native carbon in plant PDX&apos;ed discharge solids can still preg rob gold loaded activated carbon.

Jan 1, 2011

By J. A. Organiscak

Longwall mining technological improvements have provided significant increases in productivity over the last 15 years. Longwall productivity is anticipated to continue to escalate with expanded application of automated equipment. Automation technology that will likely be adopted over the next 5 years is memory cut with shearer initiation of shield movement supervised by a couple of face workers. Operations using this technology will most likely relocate many production workers from the face to the outby gate entries and position several face workers outby the shearer, exposing workers to different health and safety risks. These changing risks are primarily related to worker relocation and expected increased production levels. Workers outby the face will most likely have less dust and noise exposure, but will be exposed to other safety hazards associated with outby equipment movement, materials handling, and gate entry ground movements. The face workers will most likely be exposed to higher respirable dust and noise levels generated by the equipment at elevated production rates. Methane gas emission is also expected to increase with faster mining rates. These operational changes and the control technologies needed to reduce redefined longwall worker hazards at semiautonomous longwall operations require examination to maintain the health and safety of mine workers.

Jan 1, 1996

By C. L. Lin

The image-based On-line Particle Size Analyzer (OPSA) system has been developed at the University of Utah to measure particle size distributions under plant conditions where overlapped and segregated particles are being transported on a moving belt conveyor. Evaluation of the OPSA system at several plant sites has been completed. The results show a consistent agreement between the particle size distributions obtained from the OPSA system and those obtained from laboratory screen analysis of belt samples. These results and the stable performance of the OPSA system during the field tests suggest that continuous quality control of crushed products is possible using the OPSA system.

Jan 1, 1999

By Richard Chojnacki

The western united States is not usually noted for the production of fluorspar; however, many significant fluorspar districts do occur in the Rocky Mountain region and constitute a resource of sizable dimension and major potential. This is particularly true within the area of the West served by the rail lines of the Union Pacific Railroad (see Figure 1). Fluorspar deposits near the Union Pacific have produced over 1.3 million tons of finished fluorspar products from 2.3 million tons of ore. Approximately 80% of this production was of acid-grade and 20% of metallurgical-grade fluorspar. Production of ceramic-grade was negligible. Through the years substantial production has come from eight mining districts. Five of these have produced metallurgical-grade and three acid-grade. The best-known fluorspar producing area in the West is the Jamestown Mining District. It was one of the first producers of fluorspar in the western United States and is estimated to have produced over 500,000 tons of finished fluorspar from over a million tons of ore. The district encompasses approximately 36 square miles in central Boulder County, Colorado, about 9 miles northwest of the City of Boulder. Although small shipments were made from the district as early as 1873 or 1874, significant sustained production was not achieved until 1940 when the General Chemical Company, now a division of the Allied Chemical company, acquired the Alice, Burlington, Chancellor,

Jan 1, 1971