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By James A. Barr

Prospecting methods used in Tennessee have gradually improved with the years, as required by depletion of the easily accessible and shallow deposits and the universal trend toward mechanization, and as necessitated by exploring deeper beds, often occurring under limestone and flinty overburden. In the early days it was a very simple matter to dig pits by hand, using a plentiful supply of local farm labor to expose relatively shallow deposits of "brown rock" under shallow clayey overburden that would stand up without timbering. Visual inspection of the exposed phosphate and expert judgment of the "grade" analysis, aided by a "biting" test to reveal presence of unwanted silica, furnished most of the information required. All this might be helped by a few samples sent to the local chemist† who supplemented his income by judicious trading or tanning a few bear skins. The extra curricula activities did not affect the accuracy of the analysis which hold up even under present day standards. Some shot and core drilling was done in Hickman County, mostly for the limestone-like blue Phosphate deposits. The next step was the use of a 4-in. posthole auger, hand operated as described by Guenther, followed by a completely mechanized rig, as described by Pickard. Both these methods are practically adapted to the prospecting of the relatively soft brown rock deposits at moderate depths of clay overburden. For prospecting in areas of deeper overburden, such as are often found in Hickman County, up to 150 or even 200-ft depths, a modified core-drilling method is described by Guenther. Johnston describes a special diamond-drilling technique, developed by TVA, to penetrate flint horizons, which was adopted by the International Minerals in chemical corporation to prospect in Hickman County where deposits had previously been prospected at considerable expense and with difficulty, by small, temporary, hand-dug shafts.

Jan 1, 1948

By E. R. Bauer

The trend in underground room-and-pillar coal mining is to employ remote-control continuous mining machines and extended cuts, 12 m (40 ft) deep or more. This system of coal extraction, adopted by over 435 mines, can create additional worker-safety hazards. To address the ground control and worker-positioning hazards, a combination of statistical analyses and numerical modeling was conducted. Initially, the reported roof-fall incidents and fatalities were reviewed to delineate the ground-control hazards. Then, the application of the Coal Mine Roof Rating (CMRR) for estimating safe extended-cut depths was evaluated. Finally, computer modeling to predict roof displacements during extended-cut mining was completed. The paper describes the results of these studies and their impact on the safety of extended-cut mining.

Jan 1, 1999

By Bruno Santos Malaquias, Carlos Eduardo Pessoa Gomes, Diego Canez Fernandes, Henriquison Magela Bottrel Reis

A formação de depósito de carbono é inerente ao processo de coqueificação, com tendência a se acumular nas regiões da zona livre do forno (teto, boca de carregamento e paredes) e no tubo de ascensão dos gases. Contudo, o depósito quando em excesso, se não for removido a tempo, pode causar queda na produtividade, além de impactos ambientais e redução da vida útil da coqueria. Neste contexto, foram avaliados os mecanismos de formação de depósito de carbono, bem como os fatores relacionados ao processo de coqueificação e da mistura de carvões. Foi realizada uma análise estatística dos dados da coqueria, para identificar as principais variáveis que influenciam a formação do depósito de carbono. Em paralelo, foram avaliadas amostras coletadas nas regiões da boca de carregamento, no tubo de ascensão dos gases e do MIQ de alcatrão. Verificou-se que as amostras são formadas por partículas de carbono pirolítico (craqueamento do gás) e majoritariamente pelas partículas carreadas, correspondendo a 60%, 54% e 72%, respectivamente para as regiões da boca de carregamento, da base do tubo de ascensão e superior do tubo. Foram identificadas e sugeridas ações visando minimizar a formação de depósito de carbono, tais como: redução da temperatura da zona livre; aumento da densidade da carga; controle da fração superfina (< 0,105 mm); redução do teor de matéria volátil da mistura de carvões e uso de técnicas de descarbonização.

Oct 1, 2019

By Vernon A. Mrak

The Powder River Basin of northeast Wyoming was the first area in the state to receive attention during the early days of uranium exploration. Although the uranium occurrences are many and widespread, most of the known ore deposits are quite small and difficult to mine. As a result of this, detailed regional exploration in the Powder River Basin has been neglected. The uranium ore deposits occur in that part of the Wasatch Formation that is of earliest Eocene age, and they are scattered over an area of about 400 square miles. All uranium ore deposits are associated with red beds or altered sandstones within the Wasatch Formation. Uranium ore was first shipped from the region in 1953. Total production through June of 1965 is 506,257 tons of uranium ore containing 1,922,527 pounds of U3O8. The average grade of ore is about 0.19 per cent U3O8. The major producing area of the Powder River Basin is the Monument Hill district where about 91 per cent of the basin's total uranium ore has been mined. The source of uranium is presumed to have been the Oligocene, Miocene, and perhaps Pliocene tuffaceous rocks that once overlay the area. Joints, fractures, and permeable beds or zones were the passageways for the migration of uraniferous waters from the overlying beds to the Eocene host rocks.

Jan 1, 1968

By D. W. Bridges, S. R. Borrowman

Thorium and yttrium oxides were recovered from siliceous ores of the Powderhorn , Colo . , area . Processing comprised ( 1 ) acid curing and subsequent ( 2 ) acid baking , ( 3 ) leaching , and ( 4) solvent extraction of thorium , using a primary alkylamine , and yttrium , using di - 2 - ethylhexyl phosphoric acid . About 95 pct of the contained thorium and yttrium was recovered from ore containing 1.2 pct Th02 and 0.5 pct Y₂ 03. The thoria product was 99 pct Tho ; the yttria product was 77 pct Y₂ 03. A 150 - to - 1 concentration ratio was effected on the latter , but some contaminating lanthanon - group oxides remained .

Jan 1, 1964

By Pengkai Wang, Huimin Lu, Xiaoxiang Zhang

"In this paper, it was studied an electrochemical reduction process of carbon dioxide in ionic liquids such as 1-n-butyl-3-methylimidazolium hexafluorophosphate ([Bmim] PF6) as the electrolyte. The electrolysis experiments were carried out under current and potential controls. The cathode products contained carbon nanotubes, carbon nanofibers, nanographites, and amorphous carbon. To establish the actual current and potential ranges, the electroreduction of carbon dioxide dissolved in the ionic liquid was studied by cyclic voltammetry on glass-carbon (GC) electrode at room temperature. The electrochemical mechanism of carbon dioxide electroreduction was studied for explanation of all obtained results. Carbon dioxide in ionic liquids was electroreduced, similar to metals oxides being electroreduced in molten salts.IntroductionGlobal warming caused by the increase of carbon dioxide in the atmosphere has become one of the most concerning environment problems, so the solution to this greenhouse effect is very urgent. However, the carbon dioxide is also a cheap and abundant raw material that represents a potential source for the production of chemicals and fuels. Therefore, the development of the technologies that achieve simultaneous reduction and conversion of carbon dioxide to fuels is important. The electrochemical reduction of carbon dioxide is one of the effective approaches to transform CO2. Many investigations have been carried out on the electrochemical reduction of CO2 in both aqueous [1] and non-aqueous [2] electrolyte solutions with different electrodes. The solubility of CO2 in water is very low even under high pressure of CO2, and some investigators have brought focus into the electrochemical reduction of carbon dioxide in organic solvents, because they dissolved much more CO2 than water did. However, the hazardous or toxic properties of organic solvents hinder their use."

Jan 1, 2009

By Lawrence Y. Marks

During the mineral survey of the Bob Marshall Wilderness and study areas by the author in 1971, 1973, 1974, and 1976 (Marks, 1978), the area designated Reservoir-North (RARE II No. H1-485) in January, 1979, (U.S. Forest Service, 1979) was examined, along with other lands adjacent to the earlier study areas. However, the 1978 open-file report covered only areas originally designated for study. The present report on Reservoir-North is based on earlier work. No work has been done in the area since 1976. Mineral Appraisal Reservoir-North RARE II area (No. H1-485) is in the Northern Disturbed Belt which has been identified as having high potential for natural gas accumulations and lesser potential for oil accumulations (Mudge, 1978). Oil and gas lease applications in the area, indicate interest by oil companies.

Jan 1, 1981

By F. Habashi

Lead is an ancient metal, has been produced to-date from its ores exclusively by pyrometallurgical route. The process suffers from high operating cost and excessive pollution problems. Extensive research has been going on since the beginning of the twentieth century to find a non-polluting process for its production and a solution for its complex refining scheme. It has been assumed correctly that the hydrometallurgical route should be the most promising. Pilot plants have been constructed and operated for a reasonable periods, but no process has proved to be satisfactory. As a result, a number of smelters and refineries have been shut down. The present review analyses the situation and suggests that the best route to treat lead sulfide concentrates is by leaching with fluoroboric acid, HBF4, containing ferric fluoroborate, Fe(BF4)3, and electrolyzing the solution in a diaphragm cell - - a process recently invented by Italian metallurgists. In this process, any silver present in the concentrate remains in the residue together with elemental sulfur and can be recovered by known methods.

Jan 1, 2008

By Kefton H. Teague

Attempts to locate domestic supplies of sillimanite have been unsuccessful until recently. This paper describes recent discoveries of sil-limonite-bearing schists in the Southeastern States, with emphasis on geology of the deposits, mineral composition, origin, and reserves. Statements concerning possible methods of mining, milling, and utilization of sillimanite are given. Results from refractory tests on a laboratory scale are summarized. SINCE 1917, when synthetic mullite was first used in spark plug porcelains, there has been a continued search for natural sillimanite. During the recent war this search was intensified, not only for sillimanite but also for any materials which could be used satisfactorily as a substitute for the imported kyanite from India. The Indian massive kya-nite does not decrepitate during calcination as does our domestic bladed kyanite, thus a coarse grog can be obtained from it. Some of the most promising domestic materials suited for high temperatures are limited in quantity. Massive topaz from Chesterfield County, S. C., showed promise of possessing desirable refractory properties; but the action of combined fluorine, liberated during calcination, upon equipment and surroundings, as well as a limited supply of ore and the presence of impurities discouraged its use. Residual lumps and boulders of massive kyanite, similar to the material imported from India, occur in Georgia. This material, like the massive topaz, is of limited quantity. Andalusite from California and dumortierite from Nevada are satisfactory high-temperature refractory materials. Their uses have been restricted to specialized products since the location and character of the deposits are such that large production is impractical. Sillimanite, like kyanite and andalusite, has the theoretical chemical composition of Al2SiO5. It has a hardness of 6 to 7; vitreous, silky to subadamantine luster; specific gravity of 3.2 to 3.3; and is gray to bluish gray in color. Under the binocular microscope, the crystals are transparent. The mineral may occur as dense, fibrous mats (fibrolite) composed of fibrous, sometimes radiating hair-like crystals in schist which are associated with igneous intrusions. Deposits of this type have widespread distribution, but none discovered to date appears to have commercial possibilities. Sillimanite also occurs as bundles of crystals disseminated in biotite schist, as noted in the Hart-Elbert-Madison County, Ga., area and in some of the South Carolina and North Carolina deposits. This type of material has been called prismatic sillimanite by the U. S. Bureau of Mines. Deposits of this variety appear to offer commercial possibilities. When heated above 1650°C, sillimanite expands about 6.5 pct and is converted into a mixture of mullite (3Al2O3 . SiO2) and vitreous silica. This is a stable mixture which has a specific gravity of about 3.15. General Geology: Sillimanite (fibrolite) is a mineral common to the pre-Cambrian metasedi-ments of the Southeast. It occurs throughout the crystalline schists which lie between the Fall Line on the southeast and the established Paleozoic rocks on the northwest (fig. 1). In addition to the meta-sediments, this area contains pre-Cambrian igneous

Jan 1, 1951

By Kefton H. Teague

Attempts to locate domestic supplies of sillimanite have been unsuccessful until recently. This paper describes recent discoveries of sil-limonite-bearing schists in the Southeastern States, with emphasis on geology of the deposits, mineral composition, origin, and reserves. Statements concerning possible methods of mining, milling, and utilization of sillimanite are given. Results from refractory tests on a laboratory scale are summarized. SINCE 1917, when synthetic mullite was first used in spark plug porcelains, there has been a continued search for natural sillimanite. During the recent war this search was intensified, not only for sillimanite but also for any materials which could be used satisfactorily as a substitute for the imported kyanite from India. The Indian massive kya-nite does not decrepitate during calcination as does our domestic bladed kyanite, thus a coarse grog can be obtained from it. Some of the most promising domestic materials suited for high temperatures are limited in quantity. Massive topaz from Chesterfield County, S. C., showed promise of possessing desirable refractory properties; but the action of combined fluorine, liberated during calcination, upon equipment and surroundings, as well as a limited supply of ore and the presence of impurities discouraged its use. Residual lumps and boulders of massive kyanite, similar to the material imported from India, occur in Georgia. This material, like the massive topaz, is of limited quantity. Andalusite from California and dumortierite from Nevada are satisfactory high-temperature refractory materials. Their uses have been restricted to specialized products since the location and character of the deposits are such that large production is impractical. Sillimanite, like kyanite and andalusite, has the theoretical chemical composition of Al2SiO5. It has a hardness of 6 to 7; vitreous, silky to subadamantine luster; specific gravity of 3.2 to 3.3; and is gray to bluish gray in color. Under the binocular microscope, the crystals are transparent. The mineral may occur as dense, fibrous mats (fibrolite) composed of fibrous, sometimes radiating hair-like crystals in schist which are associated with igneous intrusions. Deposits of this type have widespread distribution, but none discovered to date appears to have commercial possibilities. Sillimanite also occurs as bundles of crystals disseminated in biotite schist, as noted in the Hart-Elbert-Madison County, Ga., area and in some of the South Carolina and North Carolina deposits. This type of material has been called prismatic sillimanite by the U. S. Bureau of Mines. Deposits of this variety appear to offer commercial possibilities. When heated above 1650°C, sillimanite expands about 6.5 pct and is converted into a mixture of mullite (3Al2O3 . SiO2) and vitreous silica. This is a stable mixture which has a specific gravity of about 3.15. General Geology: Sillimanite (fibrolite) is a mineral common to the pre-Cambrian metasedi-ments of the Southeast. It occurs throughout the crystalline schists which lie between the Fall Line on the southeast and the established Paleozoic rocks on the northwest (fig. 1). In addition to the meta-sediments, this area contains pre-Cambrian igneous

Jan 1, 1951

By N. Bakhshizadeh

In this investigation, the aging effect on creep behavior of A12024-10%SiC composite fabricated by powder metallurgy was studied. P/M bars were manufactured by hot powder extrusion method at 450°C with a ratio of 16 to 1. Creep specimens were over-aged at 187 ºC for 43 h. It was found that almost full density composite with relatively homogenous distribution of reinforcing particles throughout the aluminum alloy matrix could be attained by direct powder extrusion process. Creep tests were conducted at temperatures from 275 to 325°C under stresses from 25 to 60 MPa. The analysis of the creep mechanism determined that dislocation glide was the predominant mechanism of plastic deformation. The activation energy of the creep process was found to be higher than that of lattice self-diffusion in pure aluminum.

Jan 1, 2007

By Charles Roeder, Amy Leland, Dawn E. Lehman

Concrete filled steel tubes (CFSTs) are composite members that are commonly used in many countries today. CFST components are used in the United States, but they are more common in Asia, in part because the connections used in Asia are quite labor intensive and there are not standard connections in the U.S. In addition, US design specifications are prepared by separate groups for structural steel and reinforced concrete structures and so composite systems that use CFST components are not overseen by a single group and as such there are several, conflicting design standards. In the US, steel tubes used for CFST are more slender (i.e., the diameter-to-thickness, D/t, ratio is larger) than some other countries, and labor practices (structural steel labor is different than reinforcing steel labor) also cause potential conflicts in construction. As a result, CFST has had some use in tall building construction in the US, but very limited use in bridge construction. A research program at the University of Washington has been in progress to address many of these issues with an eye towards universal design expressions, simpler, standardized connections and promotion of accelerated bridge construction (ABC). The research has resulted in recent changes to the American Association of State Highway Officials (AASHTO) bridge design specification as well as state departments of transportation (DOTs), which supports the increased use of CFST in bridge pile and drilled-shaft foundations. An experimental research study which investigate the flexural strength, shear strength and connections was conducted. These connections provide good performance under both seismic and gravity loads and address the concerns of US construction. These connections, their design rules and requirements, and their impact on composite behavior and system performance are discussed. These results permit rapid and economical construction of CFST bridge piers, piles and drilled shaft foundations. They encourage the use of more slender and economical tubes, while achieving the benefits of composite construction. INTRODUCTION Concrete filled steel tubes (CFSTs) are widely used for bridge and building construction in Asia, but the use of CFST in bridge construction is limited in the US. The historical use of structural steel and reinforced concrete in US bridge construction have resulted in more developed design expression for those construction methods, which has limited the use of CFST. Bridge construction in the US is inherently different than in Asia because of differences in codes, labor costs and construction practices. As a consequence, design and construction practices that are economical and practical in other countries may not be practical for US bridge construction.

Jan 1, 2019

By William G. Kegel

Apart from a usable product and good &apos;mining conditions, the greatest asset for a profitable coal mining organization is an effective mine maintenance program. The first step in achieving this is to have good mechanics-or men who want to be mechanics and are interested in knowing more about the design and control of the machines in their charge. A good mechanic&apos;s knowledge and ability result from ambition, curiosity, and determination. Starting with these qualities, the aspiring mechanic can launch his career by learning all he can about mechanics, electricity, and hydraulics. Though the path is rough, the end result is rewarding. Mining machinery probably receives as much, if not more, abuse as any other heavy equipment in use today. Considering the conditions under which much of the repair work must be done, it is essential that the mine operator has the best men and tools to perform the work. Mining machines, from their inception, have utilized the electric motor; and down through the years of mechanization, this power source has undergone many changes to better adapt it to the job. The first motors used were direct-current (d-c) motors since d-c power was the most economical power source for mining at the time of early mechanization. These motors were large open-type machines which are seldom used in modern mining. Because of the mine environment, the d-c motor has been reduced in size to better suit the application in mining machines and is now manufactured with dust-tight or explosion-proof enclosures. The d-c motor is constructed with either (or both) series and shunt fields located on the stationary part of the motor (stator) and- an armature coil wound on the rotating part of the motor (rotor). Power is supplied to the armature by brushes which are held stationary and make sliding contact with the armature. The brushes requires regular and careful maintenance because worn or defective brushes will cause heat or arcing which can destroy the motor. D-c motors can be used as d-c generators when mechanical power is supplied to them by the rotating shaft. In the case of a locomotive, this principle is used in dynamic braking. The momentum of the locomotive drives the motor and generates d-c power. The power is regulated with resistors and provides opposition to the motion of the locomotive.

Jan 1, 1981

By Kihong Park, Matthews C. Habjan, Arthur L. Miller

New Mining Safety and Health Administration (MSHA) regulations limit the mass concentration of airborne diesel particulate matter (DPM) or, more specifically, the concentration of elemental carbon (EC), in underground mines. The mine operators are responding by introducing a variety of controls to reduce DPM in the mines, potentially including the evaluation of new maintenance procedures to reduce underground mine vehicle emissions. There is currently a lack of an inexpensive and dependable method to directly measure the DPM concentration emitted from the vehicle tailpipe. To that end, this work demonstrated a simple field portable method for estimating the mass concentration of elemental carbon exiting the tailpipe of a diesel engine using a direct reading photometer. Simultaneous measurements of tailpipe exhaust were made with a Thermo Electron Personal DataRAM 1200 photometer (particulate mass concentration based on light scattering) and by analyzing PM2.5 and PM1.0 samples collected on quartz fiber filters using the National Institute of Occupational Safety and Health (NIOSH) method 5040 (mass concentration of EC via thermal-optical method). Results indicate surprisingly good correlation (R2 ) 0.97) of the two methods when the data are adjusted for relative humidity (RH) and corrected using an empirically generated calibration factor. Although preliminary, it may be possible to implement this method in maintenance shops to monitor emission trends and to compare emissions of various vehicles in a fleet. Such data will be useful for fleet planning to meet new air quality standards.

By Gerry Norton

The overall economics of a coal production unit are governed by a number of interdependent parameters which individually and collectively affect the final result. A business judgement is measured through return on investment considerations and in this respect, a sensitivity analysis proves useful. Figures 1 and 2 show how the various parameters affect return on investment through unfavourable change from planned or expected values. In the case of metallurgical coals, the selling price negotiated is the primary and most sensitive variable, followed by transportation, clean coal yield and capital funds invested in mining. It is clear that coal preparation plant capital and operating costs are the least sensitive to R.O.I. For energy coals, the selling price is determined by heat energy content (x cents per million BTU&apos;s) and is therefore not con¬sidered as an interdependent variable. In this case, transportation cost is the major primary factor affecting the level of income. Again the amount of saleable clean coal or total yield has a major effect on return on investment. Most of the factors considered in Figures 1 and 2 are fixed and unfavorable change from planned values becomes critical but clean coal yield is to a great extent controllable during actual operations. Once the theoretical yield for a particular coal has been determined, the optimum return is achieved by approaching this theoretical yield as nearly as possible in practical commercial operation.

Jan 1, 1975

By J. A. Porter

This paper uses project examples, primarily associated with large iron ore mines in Brazil, to demonstrate opportunities for the mining industry to go beyond traditional compliance and impact mitigation to proactively operate within the ethics of environmental and economic sustainability.

Jan 1, 1994

By Michel Brissette

"To recover more valuable ore and considering the complexity of minerals, the needs to grind finer is increasing. To reach the desired fine grinding targets, using the existing grinding media size, the energy consumption is increasing exponentially. As already proved at this conference, small grinding media represents the best potential to improve grinding efficiency. How do the small grinding media perform in industrial grinding mills?The use of small grinding media in regrind mills proved that finer grinding can be achieved at lower energy consumption. In ball mills, smaller grinding media versus 25 mm media generate a power saving from 10% to 44%. In vertical stirred mills, the power saving increases from 20% to 60%. More potential savings have been identified.For the same operating conditions, how a vertical stirred mill is performing compared to ball milling? In regrind application, a vertical stirred mill with small media (5-12 mm Millpebs) will require at least 62% less energy than a ball mill charged with 25 mm grinding media.INTRODUCTIONIn some mining applications, fine grinding is needed to liberate further the valuable ore. The purpose of regrind mills is to achieve the last stage of grinding before final flotation stage: the cleaners. In part because of high prices of small grinding media as well as availability, the most widely used size of grinding media is 25 mm.When calculating the recommended ball top size from Bond’s formula (Bond, 1961), the size for regrind applications is much lower than 25 mm. Today, the barrier for small grinding media is broken. They are best suited in regrind application. The size of grinding media is one of the most important variables affecting the mill efficiency (McIvor, R., 1997; Nesset, J.E., Radziszewski, P., Hardie, C. & Leroux, D.P., 2006).Conventional ball milling was discarded for fine grinding because of its very poor energy efficiency (Zheng, J., Harris, C.C. & Somasundaran, P., 1994; Yan, D.S., Freeman, M. & Dunne, R., 1995). Therefore, new technologies as stirred mills were developed to grind finer more effectively. Three fundamental questions should be asked. What is the best fine grinding technology? What should be the best media size to use? Is it possible to grind finer by using less energy with the existing regrind equipment?"

Jan 1, 2009

By J. Douglas Causey

In 1984, at the request of the Bureau of Land Management, the Bureau of Mines studied 29,020 acres of the 43,165-acre Terry Badlands Wilderness Study Area (MT-024-684) in order to evaluate its mineral resources. Within this report, these 29,020 acres are referred to as the study area. Located in Custer and Prairie Counties, MT, the study area is about 2 miles northwest of Terry. The study area is underlain by essentially flat-lying units of the Fort Union Formation of Paleocene age with some Quaternary alluvial deposits in stream valleys. No mines or prospects were found in the study area. Bentonitic clays and lignite coal units were examined and sampled; however, no clay resources or coal reserves were identified. Estimates of coal resources will be reported by the U.S. Geological Survey in a joint U.S. Geological Survey-U.S. Bureau of Mines publication. Gravel along the Yellowstone River, a source of agate for private collectors, could also be used as sand and gravel aggregate although material on the south bank of the river is closer to population centers and road systems. Clinker found in the study area could be a source of road metal, but is not well situated in relationship to areas of use. No geothermal resources have been identified although water suitable for direct heat applications may underlie the study area. All the area is leased for oil and gas exploration.

Jan 1, 1985

By R. H. Kuhlman

The purpose of this paper is to describe the roles of cement and concrete in construction in general and, more specifically, as construction materials of the Southeast. For purpose of this discussion, the Southeast will include the geographic area composed. of the following 13 states: Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Texas, Virginia and West Virginia. In one sense, cement by itself is not a construction material. It is a finely ground manufactured mineral product, usually gray in color. Cement is mixed with water and sand, gravel, crushed stone, or other aggregate to form concrete, the rock-like substance that is the most widely used construction material in the world. Because cement is seldom used by itself for construction but is usually a component of concrete, there is no such thing. as a "cement" sidewalk, a "cement" highway, or "cement" building. Neither is "portland" a brand name. It is a generic term used to describe any cement that hardens in the presence of water and is made to standard specifications .. For all practical construction purposes, therefore, all cement is "portland." The name "port-land" was selected by the English inventor of the product in 1824 because concrete made with his product resembled natural building stone quarried on Portland, an English island. Although portland cement is not the final material which finds its way into completed construction, as the principal component of the most widely used construction material in the world, the location and process of its manufacture warrant some discussion

Jan 1, 1977

By R. W. Hyde, B. S. Old, S. E. Eaton

INTRODUCTION ONE of the most important problems facing the steel industry at the present time is that of maintaining at a minimum the sulphur content of many grades of steel where sulphur is known to have harmful effects on both quality and yield. The present outlook in this struggle to reduce the amount of sulphur in steel is rather gloomy since the sulphur content of the raw materials available in the United States is gradually rising, with little relief in sight. A flow sheet of sulphur in the steel process is shown in Fig I. The values used here were obtained by averaging coke oven and blast furnace data at No. 5 furnace in Cleveland and are considered typical for high top pressure practice. The sulphur evolved in the blast furnace top gas was obtained by difference and since the amount is relatively small, little significance should be attached to this particular value. From Fig I it is apparent, however, that coals used in the production of metallurgical coke represent by far the largest single source of sulphur in steelmaking. As an indication of the decrease in quality of these coals as regards sulphur content the weighed average annual sulphur analysis of the coals supplied to two different steel plants, since 1925, is plotted in Fig 2.1 The sharp rise since 1940 is strikingly apparent. Another indication of this trend is found in estimates of coking coal reserves. Thus in the case of Pittsburgh seam coals available in Allegheny, Fayette, Greene, Washington, and Westmoreland Counties in Pa. as of Jan. 1937 only 25 pct of the coal reserves would contain less than 1.50 pct sulphur after washing.2,3 Many of these lower sulphur reserves have been seriously depleted in recent years because of accelerated war demands. Still another demonstration of the increasing sulphur content of coals on a country-wide basis is found in a report by the Bureau of Mines4 which shows a steady increase in the sulphur content of coke made in the United States, It should be noted that this increase continues in spite of the wider use of coal washing in recent years. Sulphur occurs in coal in three forms, pyritic (FeS2), organic sulphur, and a small amount of sulphate sulphur (CaSO4), The sulphur is subsequently found in the coke in combination with carbonaceous material of unknown composition and as calcium and iron sulphides: In considering the general problem of sulphur elimination, the Republic Steel Corp. was interested in determining which, if either, of the two major forms of sulphur in coal contributes the greater portion of sulphur to the coke, Since the ratio of pyritic to organic sulphur varies widely in different coals, it was thought that if it could be shown definitely that the major part of the sulphur occurring in coke originates from one of the two major forms of sulphur in the coal, it would then be possible to select with confidence coal which, although high in total sulphur, would yield coke of fairly low sulphur content, Using the new

Jan 1, 1948