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By G. A. Vissac

In the presentation which follows, wash-ability curves, such as are commonly used in making studies preliminary to the cleaning of any coal or to the concentration of any mineral, have been reduced in each instance to a single straight line; thus all the most important characteristics of the coal or mineral are represented in a form more advantageous than that in which such data usually are shown. To obtain consistent results, float-and-sink data must be based on a single definite narrow size range, which may be designated "a coal unit." It will be shown that such units, each embodying a different size range, can be grouped to form what may be termed "a composite coal." A three-dimensional presentation will emerge, which will closely identify the coal, illustrate its characteristics in a new manner and explain many obscure facts. Float-and-sink Tests For the preliminary study of any cleaning or concentration problem, or in the control of any operation, float-and-sink tests must be made. The results of these tests are grouped in tabular form and then illustrated in various systems of curves; but if such a graphic representation is to have the utmost practical value, it must offer at least the following advantages: (I) It must be easier to read than the tabular results, and (2) it must be easy to plot, check and interpolate. The first requirement will be attained by reducing the number of curves to a minimum, and the second by some system of representation that will use only straight lines. Of the many washing curves now in use, only the "recovery curve," often known as the "composite curve"—a somewhat misleading term—will be considered; Any point on the recovery curve will show what percentage of weight of clean coal can be recovered when the mineral is washed at a certain specific gravity. As an example, the tests listed below Fig. I are illustrated in the drawing by a curve obtained by plotting (I) as abscissas the ash content of the coal recovered and (2) as ordinates the corresponding percentage of refuse discarded; but, in general practice, instead of writing down that weight, it is customary to set down its complement, which is the corresponding weight of coal recovered. From this curve can be deduced the information necessary for the solution of most practical problems. New Form of Graphic Presentation The resemblance of the recovery curve ill Fig. 1, or, for that matter, the recovery curve obtained in common practice! to a Power curve is apparent. The general equation of such a curve is Y = axn, where n is negative. Taking logarithms: log y = a + n log x. Using a logarithmic scale, the equation of the recovery curve will be Y = A + bX. On this logarithmic basis! the recovery graph will be a straight line, using the same variables as in Fig. I; namely, the ash con-

Jan 1, 1942

By G. A. Vissac

In the presentation which follows, wash-ability curves, such as are commonly used in making studies preliminary to the cleaning of any coal or to the concentration of any mineral, have been reduced in each instance to a single straight line; thus all the most important characteristics of the coal or mineral are represented in a form more advantageous than that in which such data usually are shown. To obtain consistent results, float-and-sink data must be based on a single definite narrow size range, which may be designated "a coal unit." It will be shown that such units, each embodying a different size range, can be grouped to form what may be termed "a composite coal." A three-dimensional presentation will emerge, which will closely identify the coal, illustrate its characteristics in a new manner and explain many obscure facts. Float-and-sink Tests For the preliminary study of any cleaning or concentration problem, or in the control of any operation, float-and-sink tests must be made. The results of these tests are grouped in tabular form and then illustrated in various systems of curves; but if such a graphic representation is to have the utmost practical value, it must offer at least the following advantages: (I) It must be easier to read than the tabular results, and (2) it must be easy to plot, check and interpolate. The first requirement will be attained by reducing the number of curves to a minimum, and the second by some system of representation that will use only straight lines. Of the many washing curves now in use, only the "recovery curve," often known as the "composite curve"—a somewhat misleading term—will be considered; Any point on the recovery curve will show what percentage of weight of clean coal can be recovered when the mineral is washed at a certain specific gravity. As an example, the tests listed below Fig. I are illustrated in the drawing by a curve obtained by plotting (I) as abscissas the ash content of the coal recovered and (2) as ordinates the corresponding percentage of refuse discarded; but, in general practice, instead of writing down that weight, it is customary to set down its complement, which is the corresponding weight of coal recovered. From this curve can be deduced the information necessary for the solution of most practical problems. New Form of Graphic Presentation The resemblance of the recovery curve ill Fig. 1, or, for that matter, the recovery curve obtained in common practice! to a Power curve is apparent. The general equation of such a curve is Y = axn, where n is negative. Taking logarithms: log y = a + n log x. Using a logarithmic scale, the equation of the recovery curve will be Y = A + bX. On this logarithmic basis! the recovery graph will be a straight line, using the same variables as in Fig. I; namely, the ash con-

Jan 1, 1942

By George A. Guess

THE increasing demand for greater speed and more accuracy, in making daily assays of ores and products from mills treating material containing but very small quantities of lead and copper, has caused the older analytical methods to be supplanted by new ones devised to meet the needs of modern work. For " control " work in copper analyses, I had, previous to the present equipment, introduced in my laboratory the ordinary electrolytic method, using hollow cylindrical electrodes, and with these I began a series of experiments in determining the lead-content of daily mill-samples and controls. The results, proving accurate and satisfactory, I then devised, with Mr. H. E. T. Haultain, a cheaper electrode than the ordinary jacket electrode, which costs from $15 to $20,-the expense of the older form making the installation of many units very costly. The form of cathode finally adopted as the most satisfactory, shown in Fig. 1, is cut from 0.001-in. platinum foil. It is 12.5 cm. long, and is divided into a blade 4 cm. wide and 6.25 cm. long, and a tongue 0.7 cm. wide and 6.25 long, the immersion area being 50 sq. cm. and weight 1.5 grams. The blade is first sand-blasted and then corrugated lengthwise, in order to impart the necessary rigidity. Strips of platinum foil 0.001 in. thick, 12.5 cm. long and 0.5 cm. wide, having a median corrugation, form the anodes. Three electrodes are used in each cell, one anode in the middle and one cathode oil each side of the anode. These electrodes are connected to slotted alumi¬num terminals, in which they are held by contact pressure. The terminals are -in. rods, projecting 2 in. horizontally in front of the wall of the cabinet.; at the back the middle electrode (anode) is connected with one pole of the current, and the two outer ones (cathodes) with the other pole.

Nov 1, 1905

By Alec M. Crowell, Harry P. McClintock

Production of oil and gas condensate from the 45 oil and gas fields of South Arkansas increased for the eighth consecutive year, the production for 1943 being 27,605,647 bbl. Six new pools were discovered during 1943, bringing the state's crude oil and condensate reserve to 475 million barrels, a net increase of 70 million barrels for the year. The gross increase in proven reserve was 98 million barrels, from which, of course, is subtracted production of approximately 28 million barrels to reach the net figure of 70 million barrels. There were 35 more wildcats in 1943 than in 1942, and 29 more wells were drilled in fields of the state. Sixteen companies operated exploratory crews during the year for a total of 677 crew weeks, divided as follows: 563 weeks seismograph, 111 weeks gravity and 3 weeks core drill. There was a decided increase in gravity work and a decrease in seismic work. The year started with 15 seismic crews and ended with 5 seismograph and z gravimeter crews. Geologically, it is interesting that the number of wells bottomed in Gulf, Comanche, and Jurassic strata were near equal for the year 1943. During 1942 Jurassic was much higher than the other two. However, Jurassic still led in wildcats for the year 1943. Abandoment of wells in the stripper areas of the state reached about the same figure for the year 1943 as for the year 1942; that is, 145 wells were permanently abandoned. However, 243 wells were drilled in 1943, as against 184 for the previous year. The completions for the year were divided into 103 dry holes, 137 oil and condensate wells and 3 dry gas wells. Among new developments perhaps the most significant was the pressure-main-tenance project for the Midway field of Lafayette County, which is utilizing fresh water as the maintenance medium. This is the first fresh-water pressure-maintenance operation during primary production of an oil field in the United States. The operator of the project, Barnsdall Oil Co., estimates that the ultimate recovery of oil from this field will be increased from 32.5 to 65 million barrels. The Midway pool is of the dissolved-gas type, but a similar project is getting underway for the Magnolia field, Columbia County, a pool of the gas-cap and water-drive type. Dual completion of wells, on concurrent production from two productive zones through a single well bore, became common practice in South Arkansas during the year. As the year ended, some 50 wells had been dually completed and it was estimated that the first 37 of these wells represented a saving of more than 2 1/4 million dollars and a saving in steel of 7000 tons. The majority of the wells dually completed were those reaching depths in the neighborhood of 9000 ft. below the surface and initially productive there. Selective completion at lesser depths in the same well bore proved mechanically feasible and economically sound. The year was marked by the successful completion and placing into operation of three large natural-gas desulphurization

Jan 1, 1944

By Harry P. McClintock, Alec M. Crowell

Production of oil and gas condensate from the 45 oil and gas fields of South Arkansas increased for the eighth consecutive year, the production for 1943 being 27,605,647 bbl. Six new pools were discovered during 1943, bringing the state's crude oil and condensate reserve to 475 million barrels, a net increase of 70 million barrels for the year. The gross increase in proven reserve was 98 million barrels, from which, of course, is subtracted production of approximately 28 million barrels to reach the net figure of 70 million barrels. There were 35 more wildcats in 1943 than in 1942, and 29 more wells were drilled in fields of the state. Sixteen companies operated exploratory crews during the year for a total of 677 crew weeks, divided as follows: 563 weeks seismograph, 111 weeks gravity and 3 weeks core drill. There was a decided increase in gravity work and a decrease in seismic work. The year started with 15 seismic crews and ended with 5 seismograph and z gravimeter crews. Geologically, it is interesting that the number of wells bottomed in Gulf, Comanche, and Jurassic strata were near equal for the year 1943. During 1942 Jurassic was much higher than the other two. However, Jurassic still led in wildcats for the year 1943. Abandoment of wells in the stripper areas of the state reached about the same figure for the year 1943 as for the year 1942; that is, 145 wells were permanently abandoned. However, 243 wells were drilled in 1943, as against 184 for the previous year. The completions for the year were divided into 103 dry holes, 137 oil and condensate wells and 3 dry gas wells. Among new developments perhaps the most significant was the pressure-main-tenance project for the Midway field of Lafayette County, which is utilizing fresh water as the maintenance medium. This is the first fresh-water pressure-maintenance operation during primary production of an oil field in the United States. The operator of the project, Barnsdall Oil Co., estimates that the ultimate recovery of oil from this field will be increased from 32.5 to 65 million barrels. The Midway pool is of the dissolved-gas type, but a similar project is getting underway for the Magnolia field, Columbia County, a pool of the gas-cap and water-drive type. Dual completion of wells, on concurrent production from two productive zones through a single well bore, became common practice in South Arkansas during the year. As the year ended, some 50 wells had been dually completed and it was estimated that the first 37 of these wells represented a saving of more than 2 1/4 million dollars and a saving in steel of 7000 tons. The majority of the wells dually completed were those reaching depths in the neighborhood of 9000 ft. below the surface and initially productive there. Selective completion at lesser depths in the same well bore proved mechanically feasible and economically sound. The year was marked by the successful completion and placing into operation of three large natural-gas desulphurization

Jan 1, 1944

By Frederic L. Kadey

Perlite, as a volcanic glass, has been recognized since the Third Century, B.C. (Langford, 1978). The precise details of discovery often become lost in antiquity, and the variations among the stories pertaining to the more recent discovery of perlite as a material of commerce are no exception. Credit in the United States is given to a dentist who, while experimenting with tooth enamels about 1941, discovered that perlite-the rock-intumesced when subjected to heat. At about the same time it is reported that the chief geologist of Silver and Barytes Ores Mining Co. attempted to put out a picnic bonfire on the shores of Milos Island, Greece by throwing beach sand on it. The ensuing pyrotechnic display immediately conjured up in that man's mind the possibility of a new use for the volcanic rock that constituted most of the island. Very little was done with this discovery either here or abroad until after World War II. Today the name perlite is applied to both the hydrated volcanic glass, generally of rhyolitic composition, and to the lightweight aggregate that is produced from the expansion of the glass after it has been crushed and sized. Petrologically, it is defined as a glassy rhyolite that has a pearly luster and concentric, onionskin parting. Occurrences of perlite are restricted to several Tertiary to Quaternary age rhyolitic belts that trend in a generally north-south direction around the world. Commercially suitable deposits generally occur as domes of several hundred feet in height, although glassy zones in welded ash-flow tuffs and others associated with dikes and sills also have been reported. Mining is by ripping and blasting from open pits. Because of weight considerations, perlite usually is shipped to the local market area for subsequent expanding. In the United States, New Mexico leads in production with Arizona, California, Nevada, Idaho, and Colorado following in approximately that order. The principal use for expanded perlite is as a lightweight insulating aggregate in cryogenics, in plaster, concrete, and in loose fill insulation. Expanded perlite is also used in horticultural applications, and after subsequent milling and classification, as a filter aid. The United States is the world's largest producer and consumer of perlite. Table 1 shows the world production of perlite and Table 2 shows the perlite mined, processed, expanded, and sold or used by producers in the United States. Geology Composition and Morphology Any discussion of perlite must take into consideration its dual nomenclature, for it is known by the same name as both the naturally occurring rock and, after processing and expansion, as the lightweight aggregate of commercial significance. In its naturally occurring form, perlite is a rhyolitic glass that contains from 2 to 5% combined water. While perlite also can occur as andesitic or dacitic glass, these latter types are of negligible commercial significance. Table 3 lists the chemical composition of a few typical perlites (Anderson, et al., 1956; Langford, 1979). What sets perlite of commercial significance apart from other volcanic glasses is the fact that under the proper conditions of preparation-crushing and sizing-it will, when rapidly introduced into a flame of sufficient temperature, expand or "pop." All of the elements of composition contribute to the expansibility of the rock. The role of the combined water, however, is the most significant because it is believed not only to produce a fluxing effect in the softening of the highly siliceous glass prior to expansion, but it is also responsible for the explosive force of expansion through volatilization during heating. The current theory of the origin of the water in perlite is now less con-

Jan 1, 1983

By Philip E. LaMoreaux

Fluoride, generally less than 0.5 ppm, is present in ground water from rocks of Paleozoic age and older, in northern and eastern Alabama. Some of the water-bearing formations in the Coastal Plain area of the State yield water with as much as 6.8 ppm fluoride.

Jan 1, 1950

By J. C. Holm

ALTHOUGH the main constituents of Portland cement are the oxides of calcium, silicon, aluminum, and iron, characteristics of the cement are seriously affected by such contaminants in the raw materials as magnesium, phosphorus, sodium, potassium, sulfur, and others of lesser importance. Sources of cement raw materials comprise a long list of minerals occurring in nature in various degrees of purity. The calcareous raw materials are generally limestone of purity varying from calcite to cement rock (a low-grade limestone of natural, almost correct chemical composition), chalk, marl, seashells, coral, and coral sand. The argillaceous raw materials supplying silicon, aluminum, and iron are mainly various forms of clay and shale, to which may be added silicious sand, iron ore, bauxite, or kaolin for minor adjustment of the chemical composition. The quality of Portland cement in this country, as in most parts of the world, is controlled by rigid specifications limiting both its chemical and physical characteristics, and cement manufacturers must comply with these specifications to market their products. Brandon Raw Materials: An unusual deposit of marl, limestone, and clay occurs 12 miles east of Jackson, Miss., near the village of Brandon. The deposit is of sedimentary origin and of relatively young geological age. Layers of marl vary from putty-like consistency to such hardness that it can be cut with a knife. Interspersed between the layers of marl are bands of limestone varying from very soft to hard. the compressive strength of the hardest layers exceeding 15,000 lb per sq in. The layers of marl range in thickness from a few inches to about 25 ft. The limestone bands seldom exceed 2 to 3 ft but often occur in thinner veins in the quarry face. Above the top layer of the deposit, which may be marl or limestone, a layer of clay ranges in thickness from a few inches to more than 20 ft. Part of this clay is harvested with the raw material to supply part of the argillaceous components, but most of it is stripped as overburden and wasted. A highly silicious clay of extreme fineness, harvested from the bottom of the quarry below the marl and limestone bands, is to correct the silica content. Fig. 1 shows typical examples of the interrelation of the various materials, based on drill logs obtained during exploration of the deposit. The marls vary in moisture content in the bank from 15 to 30 pct and contain up to 70 pct -200 mesh particles and up to 40 pct —10 p particles. A large percentage of the fine fraction is within the colloidal range, making the marl extremely sticky. The limestone beds range in hardness from that of the hardest marl to a medium hard limestone and in moisture content from 2 pct to approximately 14 pct. The line of demarcation is often difficult to draw and the moisture content is possibly the best means of classification. The ratio of soft to hard material is not constant throughout the deposit, but the average is approximately 70 pct soft to 30 pct hard material. Through the years this deposit had been repeatedly explored by cement companies and rejected as unsuitable for cement manufacture, mainly because of physical characteristics. In 1950, after careful exploration of the deposit and comprehensive laboratory and pilot plant tests of the raw materials, officials of Marquette Cement Mfg. Co. of Chicago were convinced that a practical and economical method of processing the raw materials had been devised and authorized construction of a new plant that began production in December 1951. Marl and limestone, common raw materials for Portland cement, usually occur in such a manner that they can be worked separately. Their harvesting and processing normally have presented no difficult problems, as standard equipment and methods are available for handling either sticky or hard materials. No other cement plant utilizes a deposit of the nature of that at Brandon, however, and for this reason no prior art was available for design. When properly blended, the raw materials produced an excellent cement without additives. Basic problems to be solved in designing the cement plant were:

Jan 1, 1957

By William A. Kapp

INTRODUCTION Coal is being mined from beneath residential areas, structures, bodies of water and other surface features in the coalfields to the north, south and west of Sydney. The particular problems faced by mine operators in these areas vary considerably due to differences in the overlying strata, the variation in the depths of cover and also depend on the number of seams being mined. Detailed subsidence work first commenced in the Southern Coalfield in 1965 and is now being carried out over areas of extraction at roost collieries. The analysis of the results of the early investigations and of the work which continues in other areas has shown that there is a consistent relationship between subsidence and mine geometry and has led to a reliable empirical method for the prediction of subsidence. In addition, particular aspects of each of the studies in the Southern Coalfield results in a clearer understanding of strata movements and of the resulting subsidence. The features of a subsidence trough apply generally to all areas but the magnitudes of specific features vary according to the stratigraphy of the particular coalfield. The aim of the subsidence work is to quantify the effects of subsidence for a range of mining geometries and mining conditions to enable the maximum safe recovery of coal from beneath surface features. The importance of local subsidence investigations is becoming more evident to mine operators and to authorities or organisations with surface interests. The subsidence work also provides important information on the stabilities of pillars of coal which remain unmined between panels of extracted coal. These pillars are not extracted either because of poor mining or geological conditions, or because pillar extraction is not part of the particular mining operation. Subsidence studies over these coal pillars clearly establish whether the pillars have remained stable or have failed to support the overlying strata. With subsidence studies continuing over several years, it is possible to assess the stabilities of these pillars on a long term basis. BACKGROUND TO THE STUDY OF SUBSIDENCE Geographical setting Most of the black coal production in Australia comes from the Sydney Basin. The coal seams extend for approximately 350 km along the coast of New South Wales and inland for distances up to 150 km. The City of Sydney is located near the centre of the coastal extent of the Basin where coal has been mined at a depth of 900 m. The Sydney Basin is part of the Main Coal Province of NSW and is divided into several coal- fields. The Southern Coalfield to the south of Sydney contained 15 operating mines and produced 12.7 million tonnes of raw coal during the 12 months to June 1981. The collieries discussed later are shown in Fig. 1. The prominent topographical feature of the area is the Illawarra Escarpment which rises to 400 m above sea level, or 300 m above the coastal strip along the South Pacific Ocean. The escarpment is mainly sand- stone and the weathering of the cliff line has resulted in a covering of talus material at its base. Several collieries are located near the seams which outcrop along the escarpment. The city of Wollongong is located in a scenically attractive area on the coastal plain. The suburbs of Wollongong extend north along the coastline, south to beyond Lake Illawarra and west to the lower slopes of the escarpment. The Illawarra Escarpment forms the eastern boundary of the Woronora Plateau. On a regional scale the surface dips gently to the west and thus forms a watershed for the rivers, most of which flow in a general north westerly direction, sometimes forming steep gorges in the sandstone. These rivers join the Nepean and Hawkesbury River system and flow into the Pacific Ocean north of Sydney. Seven dam have been constructed over the Southern Coalfield (Fig. 1) and with one large dam further to the west, their stored waters provide the needs of the Cities of Sydney and Wollongong and the surrounding districts. A large part of the area affected by mining is the undeveloped bushland of the associated catchment areas. In general no special precautions have been required with respect to subsidence with the exception of the dam structures and stored waters. With the increase in coal mining activities and the expanding residential development south of the City of Campbelltown in the outer Sydney Metropolitan area, subsidence is becoming an increasingly important area of research. Structures which have been affected or considered are townships and extensive residential areas, buildings of historical importance, major tollways, and a high pressure natural gas pipeline. The subsidence effects of mining beneath natural features within national parks is coming under study as mining approaches these areas. Geological setting The coal seams of the Southern Coalfield lie within the Illawarra Coal Measures. They contain high rank coking coal used in the local steel industry and for export. The Bulli Seam is mined extensively through- out the Southern Coalfield with the lower Wongawilli Seam being second in importance with regard to coal production. The top of the Bulli Seam is taken to be the marker horizon between the Permian Coal Measures

Jan 1, 1982

By E. Marburg

Most ingots complete solidification vertically rather than transversely. This conclusion is based on complete solidification patterns of big-end-up and big-end-down ingots developed from dumped and split ingots. New mechanisms for segregation in ingots are proposed. Internal soundness in ingots is found to depend upon adequate width of vertical core. A LTHOUGH it has long been recognized that the A internal soundness of ingots is principally been recognizedthatthedependent on the process of solidification, knowledge of this process is still only fragmentary. The mechanisms causing the several types of segregation in ingots, which mechanisms are necessarily related to the solidification process, are not well understood. In absence of a better conception of the solidification process, it seems hardly surprising that mold design varies widely. Guiding principles for mold design are needed. At stake in the improvement of ingot quality are not only improved properties of steel but also appreciably higher yields of sound steel, which would considerably decrease manufacturing costs. In the present study, following a general description of the several types of segregation in ingots, Fig. 1, complete solidification patterns of a big-endup and a big-end-down ingot, including the zones of accelerated solidification, have been reconstructed. In both ingots, a core of vertical solidification extends from the base cone to the hot-top junction. Based on the finding that ingots complete solidification vertically rather than transversely, as has been previously assumed, new mechanisms for segregation in ingots are proposed. Internal soundness in ingots is found to depend upon the width of the vertical core, which in turn depends principally upon the width to height (w/h) ratio of the ingot. Solidification patterns of ingots are of three general types: 1—those in which vertical solidification does not reach the top, 2—those in which vertical solidification just reaches the top of the ingot, and 3—those in which vertical solidification reaches the top some time before transverse solidification would reach the middle of the ingot, so that a vertical core of definite width at the top of the ingot is developed. Axial defects vary characteristically with the solidification pattern. Examples of ingots of each type are presented. Dumped ingot data reported by Nelson' have been used in developing families of curves of transverse and vertical solidification, and in deriving the effect of the w/h ratio upon the solidification pattern. Photographs of many ingots split at Homestead and at Duquesne Works, United States Steel CO., as well as those published by the British Iron and Steel Institute,' have been studied and analyzed. In the interest of brevity, only typical ingots of each type or classification from the above sources have been reproduced. Segregation in Ingots Segregation in ingots falls into three principal classifications: 1—lamellar segregation, as revealed in sulphur prints (Figs. 2 and 3); 2—zone segregation, or broad variations in composition; and 3— interdendritic, or microsegregation. The last class, of minor importance, is not considered here. When liquid metal cools, according to the theory of differential or selective solidification,2 metal of relatively high purity selectively solidifies first. Liquid segregates (principally carbon, phosphorus,

Jan 1, 1954

By Joseph L. Patrick

Geologic exploration, which has experienced an upward trend in the United States since 1962, continued with increasing activity through 1965. New, spectacular discoveries of recent years and continued questionable economic and political climates in many areas of the world have continued to focus the exploration attention of an increasing number of companies on the United States. Traditional geologic field methods are being bolstered by development of new methods, techniques and geophysical instruments. Reports from the states emphasize that successful exploration is dependent upon the combined effort of geochemistry, geophysics and geology, with high quality laboratory support of the field effort becoming increasingly necessary. PROGRAMS NOW UNDERWAY IN WEST During 1965 mineral exploration reached an all- time high in Nevada. Although examinations are being carried on throughout the State, much of the work is limited to two areas. The first area to attract recent exploration interest, initiated by discovery of the Carlin gold mine by Newmont Mining Corp., is an area of windows near the leading edge of the Roberts Mountains thrust fault in northeastern Nevada. Included in this area are the old camps of Mountain City, Battle Mountain, Cortez, Mineral Hill and Eureka. Major mining companies are using a combination of surface mapping, geochemistry, geophysics (largely induced potential surveys), following up with drilling. The second area of exploration is along the Walker Lane, a wide shear zone that parallels the Nevada-California boundary from Virginia City to Las Vegas. Activity has been intense in the Tonopah-Yerington area. Discovery of a large copper-iron deposit following an airborne magnetometer survey first focused recent attention on Walker Lane. Sixteen major companies are involved in exploration in the State.

Jan 2, 1966

By Harrison Souder

THE object of this paper is to bring to. the notice of engineers a safety detonating fuse by the use of which misfires in blasting may be eliminated and safety in blasting operations promoted. This new detonator is a French invention and is known as Cordeau detonant or detonating fuse and is sold under the name of Cordeau-Bickford. It consists of a lead tube 5 to 6 mm. in diameter, filled with trinitro-toluene. While applicable to all classes of mining it will appeal especially to those who have to do with deep-hole blasting in open-cut clines or quarries, or any operations where a large number of holes are to be shot at one time. Since the introduction of the deep-hole blasting in the Cornwall iron mines, much trouble has been experienced from misfires and many experiments were made to determine the best and safest method of blasting. Before the introduction of the detonating fuse it was found that to insure the best results, two or more high-power electric exploders, not less than No. 6, with specially insulated conductors, should be placed in each hole; the holes wired in parallel, and for a large number of holes the current to be supplied by a live wire to the bus or lead wires at about the middle of the bench. The voltage in general use is 110 to 220, but as our material is a magnetic iron ore and the holes are generally damp, we found it advisable to reduce this to about 30 volts to prevent short circuits. A No. 7 or No. 8 special insulated detonator was adopted. But with the best of care and attention to the minutest detail, we were not able to eliminate occasional misfires and the consequent ever present danger of accidents.

Jan 10, 1914

By A. L. Baxley

An Untapped Energy Resource As much as 20 billion cubic feet of natural gas per day are flared from remote oil fields for lack of a commercially viable means of capturing, transporting, and marketing such gas. The magnitude of these gas flares can be put into perspective from an early satellite photograph (Fig. 1) which shows lights from the major cities of Russia and Eastern Europe dwarfed by the natural gas being flared in the Persian Gulf. Together, these wasted resources contain the energy equivalent of about one-half of the gasoline consumption in the United States today (Fig. 2). Additional trillions of cubic feet of natural gas are "shut-in" because of no economically viable means of commercial recovery. Methanol and liquified natural gas (LNG) are the only two practical fuel products which can be produced economically from these gas supplies. Many of these gas supplies are less than 500 million cubic feet of gas per day, making an LNG facility uneconomic. In contrast, barge-mounted methanol plants can economically convert billions of cubic feet of gas per day into safe, clean-burning methanol. The methanol approach offers the only economical route to transform vast, known reserves of natural gas into a highly versatile primary liquid fuel. Methanol Barges: An Innovative Solution The barges will be towed to suitable offshore and upriver locations such as Alaska, South America, Africa, Southeast Asia, Australia, New Zealand, and the South Pacific Islands, as well as fields in the Persian Gulf and Mediterranean Sea. At the offshore production site, a barge will be anchored by a single point mooring buoy that will also serve as an entry point for natural gas feedstock and an offloading point for methanol (Fig. 3). At some sites the barge would be beached. Each barge will produce methanol and store it in internal tanks with a capacity of 18 million gallons. The methanol will be offloaded into conventional tankers and safely transported directly to market. Unlike LNG, methanol requires neither specially built carriers nor specially built receiving terminals. Once a particular gas field has been exhausted, the barge will be towed to another location to continue production. Each barge will measure 320 by 500 ft, approximately the size of four football fields, and will have the capacity to produce 1 million gallons or 2800 metric tons of methanol per day, from approximately 100 million cubic feet of natural gas per day (Fig. 4). The barges will use the highly successful "low- pressure" design developed by the Lurgi Company of Germany, a process proven in land-based methanol plants throughout the world during the last ten years. The decision to use Lurgi technology for "sea-trans- portable" methanol plants was based on the higher efficiency and greater operability of the technology compared to other commercially proven processes. The conversion plant will be designed to accept a wide variety of feed gas compositions, and will produce chemical-grade methanol for the broadest market base (Fig. 5). To minimize costs and construction time, the barge-mounted plants will be built in the high technology environment of a domestic or foreign shipyard. Selection of the construction site for each barge will be dictated by the location of the production site and by the relative construction costs. A number of shipyards have the capacity to build several barges per year. The detailed marine engineering to integrate the design of the processing plant with the floating platform can be performed by numerous major engineering companies around the world. Production Economics The barge-mounted plant concept not only assures large volumes of methanol, but it also keeps the overall production cost low by minimizing construction cost and providing access to low cost natural gas feedstock with no alternative or a negative value. Together, these advantages make the barge-mounted methanol plants economical today. The cost structure of a new barge-mounted methanol plant differs from that of existing methanol producers around the world (Fig. 6). For example, if a U.S. Gulf Coast producer is paying $4.70/MMBtu in 1985 for natural gas, the barge plant could afford to pay about $1.6O/MMBtu for gas and be able to deliver methanol to the Gulf Coast at the same price. At some future date such as 1990, a gas cost of $6.70/MMBtu for a domestic producer would have cost parity with about $3.60/MMBtu gas cost for the barge plant. In many foreign markets, feedstocks other than natural gas are used for methanol production (Fig. 7). For example, most of Japan's capacity is based on LNG while Western Europe uses residual oil or naptha. Because these feedstocks are substantially more ex- pensive than natural gas used by U.S. producers, the barge plants will compete even more favorably in these foreign markets. As crude oil prices rise, the value of methanol in each of these markets will increase. However, the hierarchy of methanol values in these markets should remain unchanged. Furthermore, the cost advantage for using methanol in these markets will improve as world energy costs increase since the value of remote gas should not escalate significantly.

Jan 1, 1982

By S. D. Michaelson

Open pits and quarries are the major sources of all "hard rock" tonnage mined today. Normally, ore is fractured from the pit face by blasting and then truck-hauled to a primary crusher where pro- cessing begins; overburden (or waste) is generally truck-hauled from the pit to dump areas. Truck haulage of blasted ore and overburden accounts for some 25 to 50% of total mining costs in a typical open pit and commonly is the largest single cost factor. Obviously then, cost reduction efforts should properly focus on improving existing haulage systems and developing new breakthrough techniques for material transport. Continuous flow systems for large tonnages ordinarily will result in a lower cost than batch systems such as truck or rail haulage. Continuous flow with pipelines for liquids and slurries, or conveyors for medium to coarse dry materials (in the -8-in. range) are the economic answers for bulk materials handling over reasonable distances.

Jan 11, 1968

By T. L. Joseph

Charcoal was the predominant blast-furnace fuel until 1838, when it was found, by the operation of a 2-ton experimental furnace, that anthracite could also be used. This information was a stimulus to the iron industry, particularly in eastern Pennsylvania where anthracite was available at low cost. The production of anthracite pig iron increased steadily and, in 1855, its tonnage exceeded that of charcoal iron. Of the 680 furnaces in operation in 1874, the 226 using anthracite produced nearly one-half the total tonnage. In 1869, the production of coke furnaces exceeded that of charcoal furnaces and, in 1875, coke surpassed anthracite as a metallurgical fuel. In 1907, the output of anthracite pig dropped well below a million tons and its present significance is largely historical. In recent years, the production of coke has gone hand in hand with the production of pig iron and it has gradually attained the position it now occupies as a universal blast-furnace fuel. Charcoal, however, has great merit as a blast-furnace fuel chief1y because of its freedom from ash and sulfur. The harmful effect of the latter and the necessity of keeping the percentage of this element in pig iron at a minimum are well recognized. Other contaminating elements can be reduced to specified limits in the steel-making process, but the control of sulfur belongs essentially to the blast furnace. The purpose of this paper is to point out the distribution of this impurity in blast-furnace materials and to indicate how its presence alters the composition, quantity, and free-running or critical temperature of the slag, and the relation between these factors, fuel economy, and the cost of iron. Sulfur Distribution in MateRials Table 1 shows the distribution of sulfur in charcoal practice. Similar figures taken from coke practice are given in Table 2. These data were

Jan 1, 1925

By C. W. Parmalee

The ideal fuel for burning ceramic wares is the one that, among other characteristics, has little or no sulfur. For that reason wood was long considered the most desirable fuel but its high cost has practically eliminated its use except in regions where it is very abundant or other circumstances warrant its choice. The fuels commonly employed are natural and producer gas, oil, and coal. The last named is undoubtedly the most important, not only in this country but abroad. Occasionally anthracite is used but the larger part is bituminous. The quality of the coal used depends on the kind and the value of the products being manufactured. For some materials, such as common brick, hollow block, etc., the quality of the coal is of less importance than in the manufacture of polychrome terra cotta, pottery, porcelain, etc. It is obvious that in burning clays that contain notable amounts of pyrite, marcasite or gypsum, as is the case with many common clays, the sulfur content of the fuel is of much less importance. The permissible amount of sulfur in the coal used will depend on the kind of product being manufactured. "A good sample1 of coal commonly used in pottery ovens has something like this quantity of sulfur: total sulfur, 1.20 per cent.; sulfur in ash, 0.11 per cent.; volatile sulfur, 1.09 per cent." This is based on English pottery practice. Correspondence with a. number of leading manufacturers in this country has produced the following figures: Sanitary Ware.—(a) 1.0 per cent, maximum, (b) 0.5 per cent. Sewer Pipe.—(a) 1.2 per cent., (b) 1.1 per cent, present run, 3.0 per cent, has been used. Terra Cotta.—(a) 0.5 per cent, basis of contract, 1.0 per cent, approximate. Pottery.—1.0 per cent, contract, 1.5 per cent, probable content. Enameled Brick.—1.3 per cent, maximum, (a) and (6) designate different firms giving figures. Since a pottery kiln for sanitary ware will require about 14 tons of coal for a bum, the quantity of SO2 that will be generated from a 1-per

Jan 1, 1920

By Dwight H. Seely, Louis R. Records

A process for low-temperature dehydration of natural gas utilizing Joule-Thomson effect in expansion through a throttling orifice has been tested in a full-scale field installation. The results of these tests are presented in the form of performance curves from which the process may be easily evaluated. The effect of separation temperature on condensate recovery from the process is also shown. INTRODUCTION The transportation of natural gas from producing well to the consumer has always encountered the problem of hydrate prevention. This problem has become increasingly important in the past ten years due to the rapid increase in produced gas volumes, production pressures, transportation pressures and distance from producing wells to consumer. Natural gas, as normally produced from gas or gas-condensate wells, is saturated with water vapor at well-head conditions of temuerature and pressure. The solution of the hydrate problem require; but one basic process — dehydration of the gas to a water content which will result in a water dew-point below the minimum temperature to be encountered from the producing well to the point of consumption. Much of the recent development of gas and gas-condensate reserves in the Gulf Coast Area has been in locations which are accessible only by water. High well-head pressures, pipeline construction and maintenance costs and the desirability of final central gas-condensate separation facilities have stimulated the development of dehydration equipment which can be installed at each well and which will permit hydrate-free transportation of both gas and condensate in the same line to central facilities. There are four types of natural gas dehydration processes now used: 1. Adsorptive processes. 2. Absorptive processes. 3. Chemical reaction processes. 4. Refrigeration processes. The first three of these processes are indirect in that they require use of adsorbents, absorbents or reactive chemicals. These materials require regeneration and part of the total gas stream is consumed in the regenerative process. Indirect processes have a wide range of flexibility as defined by allowable operating pressure and temperature, but most are not easily adapted to automatic operation. The refrigeration process described in this paper was designed for installation at the producing well-head. It requires no regenerative cycle and with normal well-head temperatures no external source of heat. The flexibility of this process is limited only by the pressure drop which may be allowed between well-head and transportation line. THEORY There are three basic physical concepts involved in the low temperature dehydration process. These are: 1. Formation of hydrocarbon hydrates. 2. Joule-Thompson effect resulting from the expansion of gaseous mixtures through a throttling orifice. 3. The equilibrium composition characteristics of water vapor and gaseous hydrocarbon mixture.. The chemical composition and physical structure of hydrate; have been described by several investigators.3,4,5,10 Specific conditions of temperature, pressure and composition as well as the requirements for turbulence and presence of free water necessary for hydrate formation have been described by Katz.6 Natural gas hydrates, as they are found in plugged gas pipe lines, have the appearance of packed snow. The mass of these hydrates has low continuous porosity and permeability. Joule-Thomson effect. or the reduction in temperature which occurs when natural gas is throttled throusll a restrictive orifice, is the basic phenomenon which permits efficient use of refrigeration for the purpose of dehydrating natural gas. Joule-Thomson coefficients for gafeous mixture; of methane with ethane and with butane have been reported by Buder.-I~olzer, Sage and Lacey.2 Brown1 predicted temperature drops for pressure drops from enthalpy-entropy calculations. Aside from this work there were no fundamental data found which would be applicable to natural gas mixtures of varying spe-

Jan 1, 1951

By Dwight H. Seely, Louis R. Records

A process for low-temperature dehydration of natural gas utilizing Joule-Thomson effect in expansion through a throttling orifice has been tested in a full-scale field installation. The results of these tests are presented in the form of performance curves from which the process may be easily evaluated. The effect of separation temperature on condensate recovery from the process is also shown. INTRODUCTION The transportation of natural gas from producing well to the consumer has always encountered the problem of hydrate prevention. This problem has become increasingly important in the past ten years due to the rapid increase in produced gas volumes, production pressures, transportation pressures and distance from producing wells to consumer. Natural gas, as normally produced from gas or gas-condensate wells, is saturated with water vapor at well-head conditions of temuerature and pressure. The solution of the hydrate problem require; but one basic process — dehydration of the gas to a water content which will result in a water dew-point below the minimum temperature to be encountered from the producing well to the point of consumption. Much of the recent development of gas and gas-condensate reserves in the Gulf Coast Area has been in locations which are accessible only by water. High well-head pressures, pipeline construction and maintenance costs and the desirability of final central gas-condensate separation facilities have stimulated the development of dehydration equipment which can be installed at each well and which will permit hydrate-free transportation of both gas and condensate in the same line to central facilities. There are four types of natural gas dehydration processes now used: 1. Adsorptive processes. 2. Absorptive processes. 3. Chemical reaction processes. 4. Refrigeration processes. The first three of these processes are indirect in that they require use of adsorbents, absorbents or reactive chemicals. These materials require regeneration and part of the total gas stream is consumed in the regenerative process. Indirect processes have a wide range of flexibility as defined by allowable operating pressure and temperature, but most are not easily adapted to automatic operation. The refrigeration process described in this paper was designed for installation at the producing well-head. It requires no regenerative cycle and with normal well-head temperatures no external source of heat. The flexibility of this process is limited only by the pressure drop which may be allowed between well-head and transportation line. THEORY There are three basic physical concepts involved in the low temperature dehydration process. These are: 1. Formation of hydrocarbon hydrates. 2. Joule-Thompson effect resulting from the expansion of gaseous mixtures through a throttling orifice. 3. The equilibrium composition characteristics of water vapor and gaseous hydrocarbon mixture.. The chemical composition and physical structure of hydrate; have been described by several investigators.3,4,5,10 Specific conditions of temperature, pressure and composition as well as the requirements for turbulence and presence of free water necessary for hydrate formation have been described by Katz.6 Natural gas hydrates, as they are found in plugged gas pipe lines, have the appearance of packed snow. The mass of these hydrates has low continuous porosity and permeability. Joule-Thomson effect. or the reduction in temperature which occurs when natural gas is throttled throusll a restrictive orifice, is the basic phenomenon which permits efficient use of refrigeration for the purpose of dehydrating natural gas. Joule-Thomson coefficients for gafeous mixture; of methane with ethane and with butane have been reported by Buder.-I~olzer, Sage and Lacey.2 Brown1 predicted temperature drops for pressure drops from enthalpy-entropy calculations. Aside from this work there were no fundamental data found which would be applicable to natural gas mixtures of varying spe-

Jan 1, 1951

By H. Conrad, K. Janowski, E. Stofel

In a previous paper,1 the occurrence of (0001) and (0111) twins was reported for compression tests of 60-deg-oriented sapphire rods in the temperature range from 1100° to 1300° C. Subsequent to this initial work, additional tests have been conducted, and twinning has been found to occur at temperatures as high as 1500° C. Also, the temperature and strain-rate conditions for the two types of twins and for slip have been established in more detail. The present note covers this more recent work. The compression-test data are summarized in Table I. The techniques for identifying the twins are optical examination up to X1000 and X-ray analysis.' It is evident that (0711) twins are pre-

Jan 1, 1965

By H. J. Wasson

At the close of 1927 Venezuela was producing at the rate of 205,000 bbl, per day, making it the third country in the world in point of present daily production. For the year, the total was close to 64,000,000 bbl., representing an increase of about 70 per cent. over the 37,000,000 bbl. in round numbers produced in 1926. All of the 1927 production canie from fields opened up before the beginning of the year. While no new fields were added to the list of shippers, the past 12 months' wildcatting yielded a fair quota of new discoveries which, in the light of prcsent results, may be considered likely sources of production in due time. Altogether three such promising finds were made Of first importance, at least for the immediate future, is the completion by the Lago Petroleum Corpn. of the San Matins well, 4 miles north of the present edge of the Lagunillas field. Although rated as only a 125. bbl. well, at 3217 ft., it indicates a probable extension of the field over the intervening 4 miles between the two. The two other wildcat discoveries of importance were the Los Manueles well in the District of Colon, which has in all probability opened up a new field about 7 miles north of the present Tarra oprations; and the Honibre Pintado well of the Standard Oil Co. of Venezuela,. in the State of Falcon, which is considered to be a promising clc~vc~lop~ncnt. Neither of these last mentioned two discoveries will apprcciably affect production during 1928, as the Manueles area must await the carrying out of a general plan for the exploitation of the District of Colon, a problem requiring time. The Hombre Pintado area is being tested further, but doubtless several wells will be put down before. anything definite will be done towards making the pipe line. arrangements that rnust necessarily precede the commercial exploitation of the field. The San Matias Well The San Matias well is a highly significant dcvelopment,. It is located along the trend of the La Rosa-Ilagunillas producing formations, and when drilling started, production in the Lagunillas field was 4 miles

Jan 1, 1928