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By Joseph B. Perry, G. M. Kirwan

MAGNESITE is found in 22 California counties, but many of the deposits are too small or too impure to be of commercial value. Several of substantial size and quality were entirely exhausted by wartime operation. At present, three properties comprise the only known workable deposits in the state. Of these, the Western mine and the Patterson mine have been known and worked for many years, and have been described in considerable detail in various publications, therefore need only brief mention here, because of their proximity to the Bald Eagle mine. The latter, recently developed, is unusual in type of ore deposit, plant design and operation, as well as products made, and very little has been written concerning it. WESTERN MINE The Western mine, 32 miles south of Livermore, Calif., was formerly operated by C. S. Maltby. It has been a consistent producer for many years.1 The ore is of amorphous variety, occurring along fracture zones in serpentine. The veins vary greatly in width, the average being perhaps 8 ft., with the maximum indicated in one early stope of 40 ft.; 2 ft. is considered the minimum for economical mining. The strike of the veins is predominantly north and south, with dip to the west varying from 40º to 75 º. Walls are well defined and as a rule firm and easily supported. Veins range in length from a few hundred feet to 1000 or more. Their maximum vertical extent is about 350 ft., but many run less. Early mining consisted of open-cut and glory-hole work on the larger outcrops. This was followed underground by a modified shrinkage system, the waste and low-grade horses being removed by hand sorting on the tramming levels and transported to surface dumps. Filled-stope mining is used now, in order to eliminate the handling of waste, which has

Jan 1, 1938

By Charles E. Packard

Many coal producers have been faced recently with the problem of arranging their production facilities to accommodate recent trends in the transportation of their product. Each operator is normally faced with a different problem requiring a system to meet his specific needs. It may be that he would be required to load a seven or eight thousand ton integral train each day which would naturally call for a large storage pile, high loading rate, accomplished in a minimum of time On the other hand, it may be that he is faced with furnishing coal to make up one-half of a unit train that is to be assembled twice a week. Whether the problem is large or small, many considerations must be given to each specific problem to be certain that the proper scheme is applied. The operator actually has several choices as to what type of storage and loading facilities he may consider. The storage pile, for instance, may be open type, conical in shape, kidney-shaped, or long and wedge-shaped. It may also be enclosed by steel or concrete

Jan 8, 1964

By Tim O’Neil

Until about three years ago, Asarco's copper business consisted predomi¬nantly of custom smelting of ores and concentrates produced by other mining companies. Since then, the company has been transforming itself into a fully integrated producer in copper mining, smelting, and refining. In doing this, Asarco has lowered its costs and restructured its operations and finances. Now, Asarco hopes to complete this process by spending $260 million over the next three years, to expand and modernize its copper facilities and boost production by some 40%. The capital spending program includes: • $130 million at the Ray mine about 113 km (70 miles) north of Tucson, AZ, to expand mining capacity and install an in-pit ore crusher, mill, and concentrator; • $100 million, to expand the mining capacity at the Mission Complex located south of Tucson, AZ, and refurbish the adjacent, idle Pima mill and concentrator. (Asarco had earlier exercised an option to purchase the Pima mill for about $6 million); and • $30 million, to modernize the copper smelter in El Paso, TX, with a new flash smelting process. The new program is in addition to a recently completed first-phase expansion of the Mission mine, mill, and concentrator. This $13 million debottlenecking of existing operations in¬creased production capacity by 46% or 24.5 kt/a (27,000 stpy), to 79 kt/a (87,000 stpy) of copper in concentrates. In addition, a previously an¬nounced $12 million expansion program at the Ray mine is scheduled for completion in early 1990. It will expand mill capacity, to offset the anticipated effects of increasing ore hardness as the pit deepens. Ray produces 68 kt/a (75,000 stpy) of copper in concen¬trates and an additional 36 kt/a (40,000 stpy) of electrowon copper. By 1992, when Asarco's expanded and modernized copper facilities are operating at capacity, the company's mine output will have increased by 67 kt/a (74,000 stpy), to 263 kt/a (290,000 stpy) of contained copper. That will be enough to provide all of the feed required for Asarco's two copper smelters - by then, both of them modern, state-of-the-art facilities. Asarco's expansion and modernization program will further reduce costs and provide added assurance that the company's copper business will be profitable at the bottom of the cycle, according to Chairman Richard de J. Osborne The Ray mine portion of the new program will include construction at the mine of a new mill and concentrator, with a capacity of 18 kt/d (20,000 stpd) of ore. These new semiautogenous grinding mills and large capacity flotation cells will augment the present 27.2 kt/d (30,000 stpd) concentrator located 29 km (18 miles) away, in Hayden, AZ. A 29 km (18 mile) pipeline will be built to carry tailings in slurry form from the new Ray mill to the present tailings pond. Concentrates from the new facility will be shipped by rail to Asarco's Hayden copper smelter. Ray's present 27.2 kt/d (30,000 stpd) crusher, adjacent to the open-pit, will be replaced by a 54.4 kt/d (60,000 stpd), portable in-pit crusher and conveying system. This will reduce the more expensive ore haulage by truck. The Ray project is scheduled for completion by 1992. It will increase the mine's annual output of copper in concentrates by an additional 33.5 kt/a (37,000 st), to 102 kt (112,000 st). And the project could mean an additional 400 jobs at the 730 employee Ray operation. Work at the Mission Complex involves reactivation of the Pima mill and concentrator and expansion of mine output sufficient to provide ore to both the Pima mill and the present Mission mill. In 1985, Asarco purchased the Pima mine, which occupies one end of the Mission pit. The work at Mission will increase its annual capacity by 33.5 kt (37,000 st), to 112 kt/a (124,000 st) of contained

Jan 1, 1989

By W. Z. Rogers

U.S. feldspar output sold or used in 2005 was an estimated 760 kt (838,000 st), valued at $44 million free-on-board plant. This was below the 2004 volume and was the second year of decline in a row. Output included flotation concentrates, feldspar content in feldspar-silica mixtures, potash feldspar and aplite. The strong housing market in the United States maintained demand for ceramic tiles, plumbing fixtures and fiberglass insulation requiring feldspar. Shipments of glass containers were about the same as in 2004. Imports of ceramic tiles and plumbing fixtures continued to increase, taking the place of U.S.-produced goods and the feldspar required to make them. For 2005, 80 percent of the ceramic tiles sold and 50 percent of the plumbing fixtures sold in the United States were imported. Since 2000, manufacturing plant closures in the plumbing fixtures industry have reduced the demand for feldspar and feldspar-silica mixtures by 100 kt (110,000 st). Increased demand from the ceramic tile industry has partially offset the lost volume.

Jan 1, 2006

By K. M. Weigert

The position of the three-phase field between the alpha and the beta phases was established. The exact location differs from previous assumptions. The extremely high strength and hardness values were found near the phase boundaries of the ternary compositions. IN 1929, UenoL investigated vertical sections of the Ag-Cu-Zn diagram at constant silver and zinc values. From the evaluation of cooling curves and microscopic studies, he concluded that there was no evidence of a three-phase field in the solid state between the a and ,8 fields. The failure to find evidence for this field was due to the fact that it exists only in a very narrow range of compositions and requires special methods of heat treatment to establish phase equilibrium. In a later publication on the same subject Keinert2 rearranged Ueno's diagrams to conform with the basic phase rules. The existence of a three-phase field was postulated in the solid state between the a phases and the homogeneous ,9 phase between the Cu-Zn and the Ag-Zn binary border systems. The approximate location was based on a few microscopic observations of the structure and it was pointed out that the exact position could be determined only by a larger number of experiments. In the twenty years following these investigations alloys of Ag-Cu-Zn have become of general interest due to various technical applications, principally for brazing. In the course of an overall investigation of the physical properties of ternary Ag-Cu-Zn alloys the author found extremely high values of hardness and strength in alloys of compositions between the a and the yS fields. The exact location of the intermediate phase fields was established by the evaluation of more than a hundred cooling curves and microscopic mountings. Experimental Procedures Preparation of Test Samples: At the beginning of the investigation samples were chillcast into Vi in. diameter iron molds to determine hardness, strength, and the mechanism of primary crystallization. These

Jan 1, 1955

By Eugene E. Brucker

In recent years, there has been increased interest in construction problems presented by karst topography. Twenty-five years ago, karst areas were by-passed for development. Today, the high cost of land and population pressures are requiring utilization of karst areas. Areas exhibiting karst features can be satisfactorily developed so that construction can proceed in a normal manner; or the areas may be left undeveloped and the underground drainage system abused by improper use causing or contributing to structural collapse, excessive erosion, and a grave threat to the stability of land development and the environment. The term "karst" is a comprehensive term applied to areas underlain by soluble rock that possess a topography formed chiefly by the dissolving of rock and the diversion of surface waters to underground routes. There are four features which contribute to the maximum development of karst. 1. A soluble rock, preferably limestone, must be present at or near the surface of the ground. Occasionally, dolomite will suffice.

Jan 1, 1970

By A. Belleau, F. Lavoie

"Quebec Iron Ore Limited (QIO), a subsidiary of Champion Iron Limited (Champion), secured assets in early 2016 from the previous Bloom Lake operations in the heart of the Labrador Trough region of Northern Quebec, Canada. A plan was developed to bring the Bloom Lake facility back in operation once the iron ore market conditions improved. The project restart involved several aggressive moves to change operational effectiveness, one of which was the utilization of the existing Phase 1 Plant with an upgraded process flowsheet and equipment. The production target was 7.4 million tonnes per annum of 66% iron ore concentrate with an approximate 10% increase in iron ore recovery. The Phase 1 upgraded flowsheet was initially based on review of historical Phase 1 data and pilot testing data undertaken during the original Phase 1 operation and was finalized once additional metallurgical test work and process modeling was carried out by Mineral Technologies in late 2016. The final upgraded flowsheet is comprised of rougher spirals, rougher middling scavenging spirals, and an up-current classifier (UCC) with overflow scavenging spiral stage. A portion of the gravity circuit tailings treated by a series of wet high intensity magnetic separators (WHIMS) to boost overall iron recovery. This paper will describe the efforts taken to test and design the Bloom Lake Phase 1 upgraded flowsheet and report on the plant performance since commissioning in first quarter of 2018.SITE HISTORY The Bloom Lake iron mine property is located approximately 13 km north of Fermont, Quebec, and 10 km north of the Mont Wright iron ore mining complex, property of ArcelorMittal Mines Canada. The Bloom Lake mine facilities include a 32 km railway to efficiently transport the high-quality iron concentrate to a loading port located in Sept-Iles, Quebec. The Bloom Lake property was first explored in 1951 and went through multiple minor exploration campaigns by different companies up until 1998. A major exploration program was conducted by Quebec Cartier Mining (QCM) in 1998. This program included line cutting, surveying, diamond drilling, geological mapping, mini-bulk sampling, bench-scale preliminary metallurgical test work and preparation of a “mineral resource” estimate."

Jan 1, 2019

By W. C. Weslow

AN extended program devoted to the development of a matrix for holding diamonds of a size and. kind not heretofore generally used is being carried on by the Carboloy Company, and this paper describes the part of the development that affects mining and its allied industries. Labora-tory and field work so far has indicated the following: 1. Tungsten carbide and cobalt form the most desirable known matrix material for the holding of diamonds for drilling work. 2. Industrial bort diamonds in sizes and of a class not generally heretofore acceptable and therefore less expensive can be successfully held in this cemented carbide matrix. 3. In exploratory drilling, the combination of bort diamonds, impreg-nated throughout a matrix of tungsten carbide and cobalt, when fabri-cated onto drilling crowns, is an indicated economic substitute for drilling crowns in which the diamonds are set by hand, mechanically or by casting. 4. This impregnated type of drilling crown or bit has definite possi-bilites of revolutionizing the drilling of blast holes, particularly in the harder formations. This will be brought about by the development of high-speed light-weight rotary equipment using an impregnated diamond bit to replace the percussion drill now in general use. (The development of this rotary equipment is well past the laboratory stage at this time.) 5. That the use of a rotary bit is a preventive measure in the fight against silicosis. The development of this product was started by G. F. Taylor at the Research Laboratories of the General Electric Co. It was early recog-nized that it had possibilities in the drilling field and the present product is the result of considerable experimental work with other powdered metals as well as with tungsten carbide and cobalt.

Jan 1, 1940

By C. C. Russelll, V. T. McLemore

The Metals Mining Sector of the Acid Drainage Technology Initiative (ADTI-MMS) addresses technical drainage-quality issues related to metal mining and related metallurgical operations, for future and active mines, as well as, for historical mines and mining districts. One of the first projects of ADTI-MMS is to develop a handbook describing the best sampling, monitoring, predicting, mitigating, and modeling of drainage from metal mines, pit lakes and related metallurgical facilities based upon current scientific and engineering practices. One of the important aspects of planning a new mine in today’s regulatory environment is the philosophy of designing a new or existing mine or expansion of operations for ultimate closure. The holistic philosophy taken in the ADTI-MMS handbook maintains that sampling and monitoring programs should be designed to take into account all aspects of the mine-life cycle. Data required for the closure of the operation are obtained throughout the mine-life cycle, from exploration through post-closure.

Jan 1, 2004

By R. C. M. Minnitt, W. Dr. Assibey-Bonsu, F. A. Camisani-Calzolari

Born in Bothaville (OFS) on the 26th August 1919, Daniel G. Krige grew up in Krugersdorp on the West Rand. Hematriculated from Monument High School in Krugersdorpin 1934 at the age of 15 and graduated with a B.Sc. (Eng.)degree in mining engineering from the University of the Witwatersrand at the end of 1938 (age 19). In 1938 he joined Anglo Transvaal where he worked on a number of gold mines until 1943, gaining a wide range of valuable practical experience in surveying, sampling and ore valuation. He then joined the Government Mining Engineer’s Department where he worked for 8 years during which time he participated in the uranium negotiations with the British and American authorities and designed the uranium pricing formula for the contracts which led to the establishment of South Africa's profitable uranium industry in the early 1950s. During the same period he began his pioneering work in the application of mathematical statistics to the valuation of new gold mines using a limited number of boreholes and of ore reserves for existing mines. His early papers in the application of mathematical statistics, some republished in French, created world-wide interest that led to the development of the science and concepts that surround the spatial evaluation of mineral resources and reserves known as geostatistics. This technique has contributed to improved ore evaluation techniques as well as the reduction of the financial risks associated with investment in mining enterprises. Furthermore, it led to the recognition of his contributions to the evaluations of mineral deposits through the coining of the term ‘kriging’ that is used to describe a spatial mineral evaluation process known and practised in international mining circles. He continued his work in geostatistics throughout his career as Group Financial Engineer of the Anglovaal Group until his retirement in1981 and afterwards for ten years as Professor of Mineral Economics at the Witwatersrand University. He is still active as a consultant and is a registered Professional Engineer. He has published some 90 technical papers both locally and overseas, some in Russia, and has lectured and participated in international congresses in many countries. His contributions were recognized by the Witwatersrand University through the award of the D.Sc. (Eng.) degree in1963, by three honorary degrees (from the universities of Pretoria, UNISA and Moscow State Mining University), by many awards from the South African Institute of Mining and Metallurgy, the International Association for Mathematical Geology, Die Suid Afrikaanse Akademie vir Wetenskap en Kuns, the SME of the American Institute of Mining Engineers, the International APCOM Council in1999, the University of Antofagasta in Chile, and by the South African President (Order for Meritorious Service, Class 1, Gold). He has served on various Government committees, notably that for State Aid for gold mines (1967/8) and designed the State Aid formula which enabled many mines to survive a period of low gold prices; also various taxation committees, and the mining mission to Iran in 1974. He is a fellow and/or honorary life member of various technical societies locally and overseas, including the Royal Society of South Africa. During the period in the Government service he also handled several of the post-war lease applications in the Free State and Klerksdorp goldfields. The fact that decisions on new gold mines of critical importance to the State and the economy as a whole, were being taken on a limited number of drillholes without any scientific analysis of the risks of failure, stimulated him to start basic research into ore evaluation. His approach was based on the application of Mathematical Statistics to these problems, an approach of which very little was known world-wide at that stage but which had already been initiated in South Africa by Sichel via the lognormal frequency distribution model. In Krige's 1951 paper published in the Journal of the Chemical, Metallurgical and Mining Society of South Africa he covered the statistical explanation of the conditional biases in ore block valuations and stimulated the use by several gold mines of regression corrections for routine ore reserve valuations, a technique which, in effect, was the first use on an elementary basis of what is now known as kriging. His 1952 paper introduced, inter alia the basic geostatistical concepts of ‘support’, ‘spatial structure’,’ selective mining units’ and ‘grade-tonnage curves’. His 1951 paper was based on his M.Sc. (Eng.) thesis submitted in the Department of Mining Engineering to the University of the Witwatersrand, and expounded his pioneering work in geostatistics in more detail. His early research papers that had stimulated interest in several mining circles overseas, were republished in French in1955, resulting in a major research effort by French mining engineers in this field. This, in turn, led to the establishment of the now world-renowned French school of ore evaluation in Fontainebleau, Le Centre de Geostatistique de l’École des Mines de Paris. As the Group’s Financial Engineer at the Anglovaal Head Office until his retirement in 1981, he was responsible for

Jan 1, 2003

By Andrew D. McCallum, Russell A. Heins

"Until the advent of intensive cyanidation, gold gravity concentrates were generally treated by tabling. The table concentrates were smelted while table middlings and tailings were recycled to the milling circuit for further grinding and subsequent leaching in the CIP/CIL circuit. Gold recovery on production tables is relatively low, often only 30 percent, and rarely above 60 percent. Significant factors in tabling performance are; mineralogy and the operator’s experience and ability. Units have been developed by Gekko Systems to treat both batch and continuous gold concentrates. Unit sizes are determined by leach kinetics and the required residence time of the concentrate in the unit.Gekko commenced the commercialisation of intensive leaching of gravity gold concentrates in 1997 with the first commercial prototype of the InLine Leach Reactor (ILR). Over 20 units are now installed worldwide with half that number on the African continent. South African mines, South Deeps (Placer Dome WAJV) and Target (AvGold) have both installed InLine Leach Reactors. Ashanti Goldfields have placed the ILR on their standard equipment list and have six operating units with a seventh on order. AngloGold installed one of the first ILR production units at Morila in Mali.Gekko Systems successfully installed an ILR1000 Batch unit at the Antapite Mine in Peru in December 2002. The unit was installed to treat gravity concentrates and to replace a shaking table. Following installation, gravity gold recovery increased from 15% to 40% of total gold. The unit was operational from start up and the first gravity batch treated achieved 98% gold recovery. The gravity concentrates also have a high silver content and 95% recoveries on silver were also achieved.Preliminary testwork identified that the concentrates required additional oxygen to achieve peak performance. As a result of optimisation work in the laboratory, leach kinetics in the ILR have been excellent with only 6 hours residence required to achieve maximum gold extraction."

Jan 1, 2003

By R. Q. Honaker, D. Tao, D. Taulbee, B. K. Parekh

A significant amount of energy exists in the waste generated by the coal and timber industries. In the coal industry, the energy loss is mainly due to the discharge of fine coal to the waste impoundment. Despite the fact that the fine coal has the greatest cleaning potential, dewatering, handling and transportation concerns prevent its use as product in many cases. Likewise, the sawdust generated from wood production has energy value and is used as industrial boiler fuel when the transportation distance is relative short. However, wood waste is often discarded into cumbersome landfills due to uneconomical transportation alternatives. Recent research found that these two waste materials can be combined to provide a high energy fuel of around 13000 btu/lb that can be easily handled and transported to end users.

Jan 1, 2004

By G B. Ebsworth, J Krokowski de Vickerod

Several drilling programs at Maldon have produced 7790 core samples, which were assayed for gold, with 2825 of the samples assayed for nine other metallic elements. There is a lack of correlation between gold and all other elements. The situation, however, changes dramatically when sorted according to the abundance of arsenic. In the populations where As >200 ppm, there are strong, positive correlations between gold and several elements. There is also a strong positive correlation of Au with the weighted sums and products of all elements with the elemental averages as a weighting factor, and Bi*Sb and Bi*As elemental products. In these populations, there is also a strong positive correlation between the logarithms of Au and logarithms of each element, as well as the elemental sums and products described above. The correlation coefficients increase with higher As cut-off values.All elemental distributions but especially gold show a high-nugget effect and display high skewness and dispersion, low kurtosis, and common outliers. The distributions of their logarithms are several magnitudes less scattered and without outliers. Thus, the logarithmical distribution correlations are best for practical use.Correlation coefficients were T-tested and are statistically significant. The elemental correlations, particularly those of logarithmic values of weighted sums and Bi, could be used as a gold path finding tool at Maldon. After a preliminary assay for gold and arsenic, only samples with As > 200 ppm should be assayed for other elements. Higher values of gold-correlated elements or elemental ratios, in samples with low gold grades, may increase confidence that gold is under reporting due to its highly nuggetty nature.CITATION:Krokowski de Vickerod, J and Ebsworth, G B, 2012. Correlation as a gold path finding tool at Maldon, Victoria, in Proceedings Narrow Vein Mining 2012 , pp 131-144 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By Richard M. Foose

Five miles southwest of Mt. Holly Springs, Cumberland County, Pennsylvania, the Philadelphia Clay Co. has been mining and milling a white clay since 1896; for use in white cement, as a filler in rubber, pigment and paper, in the manufacture of insecticides, and for other minor purposes. Until late in 1942, when the mine was abandoned because of labor shortage, combined underground mining and surface stripping produced approximately 30,000 tons of clay a year, of which 10,000 tons were refined in the mill. Geology Lower Cambrian Antietam quartzite and the Rilontalto quartzite, stratigraphi-cally older, trend N.55°E. and make a sharp 1600-ft. anticlinal ridge of the South Mountains. The Tomstown dolomite overlies the Antietam quartzite on the southeast flank of the anticline, which is displaced near its crest by a steeply dipping oblique fault. Erosion of the less resistant Tomstown formation has resulted in a narrow valley at an elevation of 700 ft. Directly on top of the Antietam quartzite and at the base of the Tomstown formation is a zone of sandy white clay, lenticular along the strike of the formations, ranging in thickness from 10 to 300 ft. within a mile. All of the formations dip steeply to the southeast, from 65" to vertical. The clay crops out at an elevation of about 1000 feet. Origin and Character The uppermost part of the Antietam formation is sericitic and schistose at many places, and at all these places weathering is in an advanced stage. The clay is the residual product of weathering of this sericitic quartzite or sandy schist. The crude clay has the physical aspect of a sandy kaolin, but there Are large areas in the clay formation that are low in free silica, and commonly the 30 ft. adjacent to the Antietam quartzite is notably free of silica. The overlying Tomstown dolomite has been weathered almost completely to a mixed yellow and brown clay, which carries a zone of nodular and chunky limonite and manganese ore, 4 to 12 ft. thick, about loo ft. from the contact with the white clay. In mining, this zone is an important "marker," indicating where the white clay may be expected in an advancing tunnel. The contact of the white clay formation with the yellow and brown clay of the Tomstown formation is relatively sharp, although the line of contact is irregular and therefore responsible for the lenticular character of the white clay formation. Following is an analysis of the refined clay containing less than one per cent of moisture when dried at 212°F.: SiO2, 67.05 per cent; Al2O3, 22.27; Fe2O3, 0.40; CaO, 0.00; TiO2, 1.05; MgO, 0.52; Na20, 0.04; K2O, 0.88; ignition loss, 7.65; total, 99.86.

Jan 1, 1948

By Richard M. Foose

Five miles southwest of Mt. Holly Springs, Cumberland County, Pennsylvania, the Philadelphia Clay Co. has been mining and milling a white clay since 1896; for use in white cement, as a filler in rubber, pigment and paper, in the manufacture of insecticides, and for other minor purposes. Until late in 1942, when the mine was abandoned because of labor shortage, combined underground mining and surface stripping produced approximately 30,000 tons of clay a year, of which 10,000 tons were refined in the mill. Geology Lower Cambrian Antietam quartzite and the Rilontalto quartzite, stratigraphi-cally older, trend N.55°E. and make a sharp 1600-ft. anticlinal ridge of the South Mountains. The Tomstown dolomite overlies the Antietam quartzite on the southeast flank of the anticline, which is displaced near its crest by a steeply dipping oblique fault. Erosion of the less resistant Tomstown formation has resulted in a narrow valley at an elevation of 700 ft. Directly on top of the Antietam quartzite and at the base of the Tomstown formation is a zone of sandy white clay, lenticular along the strike of the formations, ranging in thickness from 10 to 300 ft. within a mile. All of the formations dip steeply to the southeast, from 65" to vertical. The clay crops out at an elevation of about 1000 feet. Origin and Character The uppermost part of the Antietam formation is sericitic and schistose at many places, and at all these places weathering is in an advanced stage. The clay is the residual product of weathering of this sericitic quartzite or sandy schist. The crude clay has the physical aspect of a sandy kaolin, but there Are large areas in the clay formation that are low in free silica, and commonly the 30 ft. adjacent to the Antietam quartzite is notably free of silica. The overlying Tomstown dolomite has been weathered almost completely to a mixed yellow and brown clay, which carries a zone of nodular and chunky limonite and manganese ore, 4 to 12 ft. thick, about loo ft. from the contact with the white clay. In mining, this zone is an important "marker," indicating where the white clay may be expected in an advancing tunnel. The contact of the white clay formation with the yellow and brown clay of the Tomstown formation is relatively sharp, although the line of contact is irregular and therefore responsible for the lenticular character of the white clay formation. Following is an analysis of the refined clay containing less than one per cent of moisture when dried at 212°F.: SiO2, 67.05 per cent; Al2O3, 22.27; Fe2O3, 0.40; CaO, 0.00; TiO2, 1.05; MgO, 0.52; Na20, 0.04; K2O, 0.88; ignition loss, 7.65; total, 99.86.

Jan 1, 1948

By Peter L. Raffo, Walter R. Witzke

RHENIUM has a melting point of 5750°F, the second highest value among the metals.1 Its refractory nature should thus make it a useful material at high temperatures. The only available data on the high-temperature properties of bulk rhenium are from the work of Flagella and Tarr.2 These authors have shown that, over a wide range of temperatures and stresses, no appreciable linearity exists in a log-log plot of the minimum creep rate or rupture life vs stress. The purpose of the present letter is to describe some exploratory experiments designed to study the creep rate-stress-temperature relation and other facets of the creep of rhenium. The tests were carried out in vacuum in the temperature range 2200" to 4000°F (0.43 to 0.72 Tm,) at stresses ranging from 4 to 20 ksi. The powder metallurgy rhenium was purchased as 0.04-in.-thick sheet. The sheet is nominally 99.97 pct pure with the major impurities being iron (70 ppm) and molybdenum (25 ppm). The sheet was machined into specimens having a 1-in. gage length and a 0.25-in. gage width. The specimens were preannealed in hydrogen at 3000°F for 1 hr. This treatment produced

Jan 1, 1970

By Paul W. Jeran, Michael A. Trevits, William P. Diamond

In this U.S. Bureau of Mines study, production trends have been analyzed for 82 gob gas ventholes on 7 longwall panels in the Lower Kittanning Coalbed, Pennsylvania. Cumulative production from individual holes was found to vary considerably, ranging from 0.03 x 106 to 10.1 x 106 m3. Peak production rates were generally about 0.03 x 106 to 0.06 x 106 m3/d, but rates over 0.10 x 1@ m3/d were observed. The variability of gas production from individual holes can be attributed to several factors, including completion practices and problems, the extent of fracture development in the strata above the extracted panel, water production, and location on the panel. Of particular significance is hole location. Holes on the ends of the panels, where overburden strata are in tension because of the support of the surrounding pillars, were generally the highest and longest producers. This observation led to the experimental placement of gob gas ventholes in the zone of tension along the margin of a panel, instead of in the traditional centerline location, which is in compression. Analysis of 7 months of gas production data indicates that the experimental near-margin holes produced 77 pct more gas than did centerline holes on the same panel.

Jan 1, 1994

By AIME AIME

0 N March 5, at Carnegie Hall, Cleveland, the Ohio Section held a joint meeting with the Cleveland Engineering Society, and the local sections of the American Chemical Society, American Society of Mechanical Engineers, and the American Society for Steel Treating. Prior to the meeting there was an informal dinner attended by 50 men. Then followed an address, "The Principles of Corrosion Protection," by Ulick R. Evans, the well-known British specialist in this problem. There were 266 present, presided over by Zay Jeffries, president of the American Society for Steel Treating and a member of the Cleveland Engineering Society. The address was well received and some discussion followed

Jan 1, 1929

By W. M. Hart

Business Process Improvement (“BPI”) Change to Survive “It is not the strongest of species that survive, nor the most intelligent, but the one most responsive to change.” [Charles Darwin] “If you want to understand something, try to change it.” [Kurt Lewin, social scientist] Many companies have tried one or more process management initiatives. Each effort may help develop a culture that is more receptive to change. Executive Management needs to be unwavering in support of change with systems and structures, staffing, development of people, measures, with incentives and rewards. General Electric developed principles for quality change management that are necessary for effective, continuing Business Process Improvement (BPI). Change Acceleration Process (“CAP”) One of the tools General Electric developed has been used successfully by companies around the world in a wide variety of industries. This tool, named Change Acceleration Process (“CAP”), is designed to improve acceptance of change. Acceptance is the method by which the creative energies of the workforce can be fully tapped. Over time, every employee receives CAP training at least once, and in many instances three (3) or four (4) times, and will work on one or more High Performance Teams. Thus, BPI can achieve and maintain its goals. The CAP tool focuses on: • Leading Change • Creating a Shared Need • Shaping a Vision • Mobilizing Communication • Making Change Last • Monitoring Progress • Changing Systems and Structures

Jan 1, 2006

By Gustavo Henrique Bolognesi Donato

Frente ao crescente número de falhas por fadiga, o projeto considerando cargas cíclicas passou a ser uma fase natural da concepção e otimização de componentes, em especial de setores de responsabilidade, como aeronáutico, automobilístico e de óleo e gás. Em geral, as avaliações se baseiam em resultados de ensaios uniaxiais que empregam máquinas universais servo-controladas de tração-compressão ou tração-tração. Entretanto, embora precisos, tais equipamentos custam centenas de milhares de dólares, apresentam elevado custo operacional e de manutenção e exigem expressivo tempo para a realização dos ensaios. Como alternativas simples e baratas existem as máquinas do tipo flexão alternada (biela-manivela), as quais podem apresentar curvas de vida à fadiga comparáveis ao caso uniaxial se os campos de deformações e tensões nas amostras forem bem conhecidos. Dessa forma, buscando avançar nesse tópico e fazendo uso de refinados modelos não lineares de elementos finitos, este artigo apresenta uma metodologia de ensaios de flexão alternada controlada por deformação (curvas e-N), assim como uma análise crítica dos resultados experimentais. Foram ensaiados um aço SAE 1008 e um alumínio 1200 H14 e, além da geometria recomendada pela ASTM B593, uma nova geometria é proposta para menor dispersão dos resultados experimentais. A metodologia desenvolvida obteve sucesso na condução dos ensaios e a geometria proposta reduziu a dispersão dos resultados para o aço SAE 1008 que apresenta elevado encruamento. As curvas e-N obtidas, além de diretamente úteis para projetos mecânicos, apoiarão comparações futuras com resultados de fadiga uniaxial dos mesmos materiais.

Aug 17, 2017