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By Charles M. Means

A thoroughly modern coal-handling system has been installed at the Pittsburgh Terminal H. H. &. Coal Co.'s new No. 8 shaft, or Cover-dale mine, about 11 mi. (17.7 km.) from Pittsburgh on a spur of the Montour R. R. The Pittsburgh scam, which is the one worked, is reached at a depth of 342 ft. (104 m.). Power is delivered to the mine at 22,000 volts over a transmission line of the bow-arrow type of construction. A private telephone line connecting the various mines and the main office in Pittsburgh is carried on the same poles. The high-tension line is brought to an outdoor, step-down, transformer substation, where three 833-kv.-a., single-phase, 60-cycle, oil-insulated, self-cooled transformers reduce the potential to 2300 volts. The transformers are protected by electrolytic, aluminum-cell lightning arresters, horn gaps, and choke coils. High and low-tension busses, together with fuses, choke coils and air-break horn-gap switches with thcir remote-control operating mechanism are mounted on a substantial structural-steel tower 25 ft. (7.6 m.) in height. Mine Substation The transformer substation is adjacent to a. pressed-brick building that houses direct-current substation equipment together with switchboards, etc., for the control and distribution of power. This building also contains the hoist for the men and supplies. Main Switchboard The 2300-volt circuit is carried underground in a conduit from the transformer substation to an oil switch in the substation and supply hoist building. This is the main switch controlling the 2300-volt busbars mounted back to a twelve-panel black-slate switchboard. From the switchboard, 2300-volt circuits are carried to transformers feeding the street and house lighting systems and to other transformers furnishing power for the elevator and lighting circuits in the store building. Other 2300-volt circuits run from this switchboard to the main hoist building, fan house and auxiliary or man-and-supply hoist. High-tension wiring,

Jan 1, 1922

By Richard S. McCaffery

This paper considers certain aspects of the acid bessemer process, particularly in its relations to the duplex process—that combination in which the pig iron is first desiliconized and decarburized in acid bessemer converters and then dephosphorized in basic open-hearth furnaces. The acid bessemer process employs an acid-lined converter and produces an acid slag. The blow is usually thought to eliminate the silicon and manganese as oxides and then to burn off the carbon as carbon monoxide On account, however, of the relatively large amount of metallic iron present in the converter, compared with the relatively small amount of the impurities it is desired to oxidize, the first reaction in the converter probably is the formation of iron oxide, which dissolves in the bath and acts as an oxygen carrier for the silicon and carbon. As soon as iron oxide is dissolved throughout the bath, the oxidation of silicon commences; but in the early stages of the blow the mass law would indicate that iron oxide must form first, and this oxide probably increases up to some saturation point. The molten metal in the converter from the early stages of the blow right through to its completion remains basic, while the slag produced is siliceous. This fact is shown by the corrosion of the acid bottom and the tuyeres, which is greatest at the tuyere orifice where oxidation is most active and where there is the most iron oxide. Why does this acid bottom corrode? Because it is attacked by a base. The thought, therefore, suggests itself, why not. make the bottoms of basic or neutral material?' As the converter slag is acid, those parts of the converter coming in contact with the slag should be acid; but those parts of the converter that are in contact with the molten metal saturated with metallic oxides should be basic. or neutral. Bessemer operators have for some time tacitly admitted this condition, for the blast pressures have steadily increased with the object of keeping the metal in suspension, and so preventing bottom corrosion; if the molten metal were not basic, it would not attack an acid bottom. In addition, the tuyeres are bunched together at the middle of the bottom and a clear space is left around the outside of the bottom; if tuyeres are placed too near the side walls the

Jan 1, 1922

By Richard S. McCaffery

This paper considers certain aspects of the acid bessemer process, particularly in its relations to the duplex process—that combination in which the pig iron is first desiliconized and decarburized in acid bessemer converters and then dephosphorized in basic open-hearth furnaces. The acid bessemer process employs an acid-lined converter and produces an acid slag. The blow is usually thought to eliminate the silicon and manganese as oxides and then to burn off the carbon as carbon monoxide On account, however, of the relatively large amount of metallic iron present in the converter, compared with the relatively small amount of the impurities it is desired to oxidize, the first reaction in the converter probably is the formation of iron oxide, which dissolves in the bath and acts as an oxygen carrier for the silicon and carbon. As soon as iron oxide is dissolved throughout the bath, the oxidation of silicon commences; but in the early stages of the blow the mass law would indicate that iron oxide must form first, and this oxide probably increases up to some saturation point. The molten metal in the converter from the early stages of the blow right through to its completion remains basic, while the slag produced is siliceous. This fact is shown by the corrosion of the acid bottom and the tuyeres, which is greatest at the tuyere orifice where oxidation is most active and where there is the most iron oxide. Why does this acid bottom corrode? Because it is attacked by a base. The thought, therefore, suggests itself, why not. make the bottoms of basic or neutral material?' As the converter slag is acid, those parts of the converter coming in contact with the slag should be acid; but those parts of the converter that are in contact with the molten metal saturated with metallic oxides should be basic. or neutral. Bessemer operators have for some time tacitly admitted this condition, for the blast pressures have steadily increased with the object of keeping the metal in suspension, and so preventing bottom corrosion; if the molten metal were not basic, it would not attack an acid bottom. In addition, the tuyeres are bunched together at the middle of the bottom and a clear space is left around the outside of the bottom; if tuyeres are placed too near the side walls the

Jan 1, 1922

By C. A. Hartnagel, D. H. Newland

The market for Pennsylvania grade showed a drop both in demand and in prices, which reacted unfavorably on New York oil production, all of which comes under that classification. The output for the year in New York amounted to 5,045,200 bbl. The production in 1937 was 5,478,000 bbl., the largest in any year for the last half century or more. Falling prices, of course, affected new drilling. They declined from $2.20 a barrel, which was posted at the start, to $1.68 in the final months of 1938. With this came a reduction in the amount of oil that would be accepted by the refineries operating in the New York fields. Conditions therefore have combined to halt, at least temporarily, the growth of oil production in the state, which had experienced a steady gain for the last 15 years or more, the yield having risen from less than 1,000,000 bbl. to the round total of 5,500,000 bbl. in 1937. Practically all the oil now obtained is from old, developed fields. No new pools have been found in the last quarter of a century or more. The larger share comes from flooding the sands. Although there are many wells that still produce without the aid of the water drive, they are small and for the most part are pumped periodically. Of late, new drilling has been restricted mainly to that required to maintain existing flood projects. Because of the high initial cost and time required to put a flood into production, the depressed condition of the market has been a serious handicap financially, and, further, has been an unfavorable influence on the planning of operations to secure the maximum recovery of the oil. Unless market conditions improve, it is certain that the effects will be shown in the yield for some time to come. Gas Developments Drilling was active in the southwestern area, chiefly in Allegany and Steuben Counties, and some notable wells were brought in that tapped the Oriskany sandstone. Altogether 42 holes were put down in the two counties, of which 31 were listed as producers and 11 were dry. The new wells gave an initial daily flow of 239,000 M cu. ft. At the close of

Jan 1, 1939

By C. A. Hartnagel, D. H. Newland

The market for Pennsylvania grade showed a drop both in demand and in prices, which reacted unfavorably on New York oil production, all of which comes under that classification. The output for the year in New York amounted to 5,045,200 bbl. The production in 1937 was 5,478,000 bbl., the largest in any year for the last half century or more. Falling prices, of course, affected new drilling. They declined from $2.20 a barrel, which was posted at the start, to $1.68 in the final months of 1938. With this came a reduction in the amount of oil that would be accepted by the refineries operating in the New York fields. Conditions therefore have combined to halt, at least temporarily, the growth of oil production in the state, which had experienced a steady gain for the last 15 years or more, the yield having risen from less than 1,000,000 bbl. to the round total of 5,500,000 bbl. in 1937. Practically all the oil now obtained is from old, developed fields. No new pools have been found in the last quarter of a century or more. The larger share comes from flooding the sands. Although there are many wells that still produce without the aid of the water drive, they are small and for the most part are pumped periodically. Of late, new drilling has been restricted mainly to that required to maintain existing flood projects. Because of the high initial cost and time required to put a flood into production, the depressed condition of the market has been a serious handicap financially, and, further, has been an unfavorable influence on the planning of operations to secure the maximum recovery of the oil. Unless market conditions improve, it is certain that the effects will be shown in the yield for some time to come. Gas Developments Drilling was active in the southwestern area, chiefly in Allegany and Steuben Counties, and some notable wells were brought in that tapped the Oriskany sandstone. Altogether 42 holes were put down in the two counties, of which 31 were listed as producers and 11 were dry. The new wells gave an initial daily flow of 239,000 M cu. ft. At the close of

Jan 1, 1939

By Max Barber

PRESENT equipment and practices in open-pit mines of the Lake Superior iron ranges have been described recently in some detail by A. H. Hubbell.1 It is anticipated that any further improvements will be the result of gradual evolution of present methods and equipment, just as those now used have been gradually evolved from earlier methods. An exception to the process of gradual evolution during the last decade has been the adoption of electric power for operating shovels and trains in open-pit mines, but it is not expected that any such revolutionary changes will be made in the future. The use of Diesel, engine equipment will gain considerable headway, no doubt, and will find favor in certain lines of operation as improvements and adaptations are evolved to meet particular requirements. The question of installing belt conveyors for handling material from deep mines of restricted area, where haulage grades become a serious consideration, or even for transferring earth, rock, or ore material for distances of several miles, is now being studied and some very interesting data are being obtained.

Jan 1, 1932

By J. M. Roberts, D. M. Barnett

The activation energy required to break a pinned dislocation line away from its condensed atmosphere of impurity atoms is calculated as a .function of applied stress, without neglecting line tension. Reasows are presented for not assuming the effect of line tension to be negligible when considering the problem of freeing a small segment of dislocation from an impurity atmosphere. The dislocation is considered to he pinned at each atomic size along its length and the pinning points are assumzed immobile. The development is a refinement of the origznal cottrell-bilby1 theory. The solution is compared to recent approximations developed by cottrell3 and Haasen5 in which line tension con- IN 1949 Cottrell and bilby1 considered the problem of determining the force required to pull a dislocation away from its condensed atmosphere of impurity atoms. They also examined the effect of thermal fluctuations on this force. The dislocation line was pictured as bowing out in a triangular loop under the action of an applied stress, and the activation energy necessary to free the dislocation from its atmosphere was calculated as a function of stress, line energy, and dislocation-solute atom interaction. siderations were neglected. A qualitative explanation of the yielding process in terms of the activation of Frank-Read sources is presented, but the lack of a realistic solution to the dynamic dislocation problem involved prevents an extension of the model at present. A self-consistent correlation between the present calculations and experimental data for delay time associated with yielding and the temperature dependence of the upper yield stress was made. Favorable agreement was noted. It is concluded that extension of the original Cottrell-~ilby' theory which includes line tension effects can just as well describe the yielding process as other approximations3,5 which neglect line tension. Cottrell and Bilby found the form of the activation energy vs stress curves to be almost independent of the line energy and the interaction energy (i.e., these parameters only affected the activation energy U by a scale factor). A check of the theory was accomplished by comparison with the experimental data of McAdam and Mebs2 for the lower yield stress as a function of temperature. cottrell,3 in 1957, attempted to obtain a simple closed-form solution for the activation energy as a function of stress by linearizing the quartic equation relating displacement of the dislocation line and applied stress. It was argued that since the contribution to the line energy/atomic plane of a dislocation is made by the long-range stress field of the dislocation through a term of the type (Gb3/2p)ln A/ro, where

Jan 1, 1963

By D. B. Rushmore, K. A. Pauly

Of primary importance in mine-installations is the hoist, which has a very direct bearing on the successful operation of a mine. Conditions vary greatly with different mines, and especially in different localities. Such factors as depth, incline, the number of levels, permissible or desirable speeds, conditions of ore, etc., are always more or less special in each case. Veins of ore are never exactly duplicated, and the nature of the ground through which shafts are sunk may considerably modify permissible values. As mining-laws are made by the different States, they necessarily vary somewhat, and, even when not fully observed, they introduce factors which qualify the conditions of hoisting men and ore. The amount of timbering required is often of importance as relating to hoisting-conditions. Methods of loading ore affect the time required, as also does the question of the use of cars or skips. Safety-precautions must be very carefully considered, and the number of men in each mine, the number of compartments, and often the method of removing water from the mine, must have careful consideration. While a general discussion of the subject of hoisting is possible, most cases are entirely special, and can be considered only in connection with the peculiar conditions pertaining to that particular installation. The cost of installation of the hoisting-plant may be an appreciable amount, while the cost of raising the ore may be but a small part of the total operating-charge. In many cases, however, the output of the mine is limited by the capacity or the hoist, and the latter thus becomes of the first importance.

Jan 1, 1911

By John V. Beall

If there is one thing that makes a fellow feel like the years are catching up with him, it is to go through a second cycle in which the adequacy of mineral resources is being "viewed with alarm." The first time we experienced such a flap was in 1951. At that time, the United Nations convened a meeting at Lake Success to study ways and means of averting a crisis in minerals. Presently there is some sentiment being expressed about the mineral scarcities that will occur in the decades ahead, in view of world population trends and increasing per capita consumption of metals. To be greatly concerned about the adequacy of metal supplies is to be highly pessimistic about the capabilities of technology. As in the past, shortages will be of temporary duration for as far ahead as the most ambitious prognosticators are projecting. The study of mineral economics is a fascinating and surprising subject. The law of supply and demand is but a starting point. The iron ore market for the steel industry is an example which comes to mind because of our receipt this week of the United Nations report "Survey of World Iron Ore Resources."

Jan 1, 1970

By Blake M. Loring, Robert A. Colton

MELTING procedures for most metals and alloys usually include some provision for the control of oxygen, since this element frequently has some undesirable effect on the properties of the metal or alloy concerned. In the melting of the various bronzes, this is especially true, since oxygen can be introduced into the melt in a number of ways, most of which are difficult to control. In making bronzes from virgin materials, oxygen is usually present in the commercial grades of copper used; electrolytic he refined copper ingots usually contain from 0.02 to 0.05 per cent oxygen. When ingot metal or scrap bronze is used in the charge, oxides are almost always present to some degree. Under certain melting conditions and in certain types of melting equipment the atmosphere over the metal may be highly oxidizing. This, of course, may be desirable in the melting practice used, but is certain to introduce appreciable amounts of oxygen into the melt, and that may not be entirely desirable. From the foundry viewpoint oxygen may have several harmful effects on bronzes. The formation of excessive amounts of oxides may produce drossy metal, which, in turn, means dirty castings and a potentially high rejection rate. It is claimed, too, that oxides in the metal may combine with hydrogen to form steam and thereby produce porosity in certain of the bronzes. The presence of certain refractory oxides, such as SnO2, may be undesirable from the viewpoint of making machining difficult, or as possible stress-raisers in the metal matrix. It is often said that excessive oxide present in the liquid metal makes the metal run sluggishly. Since it appears impractical to try to control the amount of oxygen introduced into the metal beyond taking the economical limit of precaution about charging dirty scrap, it would seem that control of the oxygen content of the liquid metal offers the most promising approach to this problem. This might be done by using slags, or covers, or by the use of some element or compound added to the melt to remove oxygen preferentially. Most aspects of this problem have been considered and considerable work has been done along these lines. A reconsideration of the problem is indicated, however, by the controversial nature of the evidence at hand, especially on the possibility of using a chemical deoxidizer to control the oxygen content of bronzes. CHOICE OF DEOXIDIZER The choice of the chemical agent selected as a deoxidizer would naturally depend first on the alloy in which it is to be used; in this particular case the alloy is Navy gun metal. In Table I are listed a group of elements that might be considered as

Jan 1, 1946

By P. W. Rainier

THE Chivor emerald field is situated on the eastern slope of the Andes in the Department of Boyacá, at an elevation of about 8000 ft. above sea level. It overlooks the Llanos (plains) of the Orinoco and is watered by many streams flowing into the Rio Meta, the Orinoco's largest tributary. The Rio Meta is navigable from the Orinoco to a point within about 50 miles of the Chivor district and may eventually prove to be the reasonable outlet for the future development of this part of the country. The topography of the district is extremely rugged and mountainous (Fig. 1), the difference in elevation between two points on a mining claim 1 km. square being sometimes as much as 4000 ft. The ground is covered with dense forest growth and the available timber is suitable and sufficient for mining purposes, but it is becoming gradually depleted by Indian clearings as the country around the mines becomes settled. The many streams combined with the rough topography give good possi-bilities for hydroelectric power. The center of population nearest to Chivor is Bogota, the capital of the republic and a city of some 300,000 inhabitants; the distance is two and one-half days' travel. The first stage of the journey from Bogota, is accomplished by rail to Chocontá, some 4 hr. travel. From Chocontá the journey is made in the saddle, one night being spent in Guateque. The latter is a small town and the nearest post office to the mines, being some 10 hr. ride distant. The roads are mere bridle paths, in parts hazardous and almost impassable in the wet season. All supplies brought to the mines, other than those produced locally, are carried by pack mule; mule freight from Chocontá costs 3 centavos1 per pound. The climate of the Chivor district is healthful and bracing. The wet season begins in March and concludes in November, the remaining months being dry. The annual precipitation is about 150 in. The temperature throughout the year is nearly constant, varying from about 45° F. to about 65° F. shade temperature. The rains are cold and unpleasant, and for the greater part of each day in the wet season the country is shrouded in dense mist. A fire can with comfort be kept burning in a living room all the year round. There are a few slight

Jan 1, 1929

By Carl Gatlin, S. Srini-Vasan

It is shown thar k k ratios cornputed on the as.sutnption that the average sandstone reservoir has a pore-size distribution characrerized by a linear 1/P saturatioN plo are in good agreewient with correspotlding k,,/k,, ratios obfairzed by Wahl, Mul-/ins and Elfrink by correlatiotz of field measurements. Methods of calculating relative permeability data have recently been reviewed and extended.' It was shown that for sandstone reservoirs where ' is approximately a linear function of effective saturation (as suggested first by Corey') it is possible to express relative permeabilities in very simple terms. For systems wetted by connate water and producing oil and gas (gas saturation growing at the expense of oil) the expression for the The accuracy of Eq. I has been frequently confirmed in our laboratories; because of its simplicity we make routine use of it in the analytical solution of proble~ns in reservoir engineering. Nevertheless, comparisons of the k,,,/k,, ratios yielded by Eq. 1 with appropriate reservoir data have been few. The publica- tion by Wahl, Mullins and ElfrinkV of an empirical equation for k,,/k,, ratios is thus of interest since this equation is specificalljl stated to be Vased on the correlation of field measurements made on sandstone reservoirs. Not surprisingly these authors found that it was necessary to

By Milton E. Wadsworth, J. Brent Hiskey

INTRODUCTION Fifteen years ago a distinguished electrochemist referred to electrochemistry as an "underdeveloped science " In the article in question, Professor Bockris (1) stated that many areas of.natura1 phenomena and applied technology are not perceived as being electrochemically based At that time, this was especially true for much of non-ferrous extractive metallurgy and was a particularly accurate description of hydrometallurgy During the last decade, there has been considerable advancement in applying the theory of electrochemistry to our know1 edge of hydrometallurgical processes and in understanding the mechanisms of underlying electrode reactions. Impressive as these advances are, there is still a growing need for electrochemical research of mineral systems and electrochemical engineering to apply this work in practical situations In a broad sense electrochemistry is defined as the physical chemistry of ions in solution and of phenomena which occur at the electrified interface. Bockris and Reddy (2) refer to electrochemistry as being divided into two fundamental domains, ionics and electrodics ionics is restricted to the behavior of ions in solutions, examples being many familiar redox processes Electrodics represents the main part of electrochemistry, and is the study of charged interfaces and the conditions governing charge transfer reactions across them. Considering hydrometallurgical applications, electrodics suggests the following relationship for a conducting solid (bulk or surface)

Jan 1, 1981

By C. W. Vaupell

THE Huitzuco mines lie in north central Guerrero, Mexico; production has been about 90,000 flasks of quicksilver since 1873. Near-surface ores fill extinct mud geysers and the deep deposits are chambered veins, stock-works in brecciated blocks, and replacements in limestone. The epigenetic minerals livingstonite, stibnite and sulphur occur in limestone, gypsum and dolomite through a developed vertical range of 260 meters. The deepest workings expose an increased amount of stibnite, which probably indicates that the lower limit of mercury mineralization is being approached. A resurgence of heat and water formed geysers over an extended area after the period of mercury mineralization. Mud geysers, which are situated, in the outcrops, contain the secondary mercury minerals, cinnabar and barcenite in the gravel and mud filling the vents. A 150-ton flotation plant is in operation concentrating stope fills that assay 3.0 kg. of mercury per ton. In one open stope, which is more than one hectare in area and 60 m. high, 150,000 tons are available. INTRODUCTION The Huitzuco mercury mines are of interest because of the unusual occurrence of ore in extinct geyser vents and the presence of several rare mercury minerals. Some of the deposits have typical characteristics of the telethermal zone and there is a gradation towards typical epithermal mineralization in depth. Halse,1 Villarello,2 Mactear3 and Merrill4 have described the geology and the early operations in the district, and Barcena5 and Mallet6 have described the rare mercury minerals, livingstonite and barcenite, found at Huitzuco. LOCATION The village of Huitzuco lies in the north central part of the State of Guerrero, Mexico, 27 km. (16.7 miles) east of Iguala, which is the largest and most important town in the area. Iguala is served by the Mexican National Railways and also by the Mexico City-Acapulco highway. The highway is surfaced from Mexico City to Iguala, a distance of 200 km. (124 miles) by road, and there is a fairly good, level, dirt road from Iguala to Huitzuco. The elevation above sea level is about 1000 m. (3280 ft.). The climate is warm and very dry except during the rainy season, from June to

Jan 1, 1937

By Oswald J. Heinrich

IN the coal review for the United States for 1875, the Engineering and Mining Journal, January 1st, 1876, remarks about the Richmond coal basin " It has contributed but little to the supply of fuel during the year past, notwithstanding the fact that it is the most favorably situated of all our coal-fields, and possesses a fuel of good quality, well adapted to many important uses. An unaccountable lethargy seems to have fallen on all who have touched this field ; and yet, in the future it can scarcely fail to become one of the great sources of coal supply." In most respects indorsing the above remarks, I take occasion to lay before the Institute the following facts in defence of the Rich¬mond basin; and not willing to criticize other mining enterprises in this field, I will make this one remark in general for all of them. While it is true that very little coal has been raised during the year in this field, it is equally true that even the little that has been raised could hardly be sold. When the output of the largest coal districts in the United States decreases, in consequence of the state of the market, it is not to be wondered at that the former small output of this basin dwindled down to almost nothing. But a far deeper¬seated evil, under which this field is suffering, may be discerned from the following remarks, which I hope will show that the latter part of the above remark in the Journal is not altogether fair. As the history of one mine in this district very nearly represents the history of the whole field, I will endeavor to give an account of the development of the Midlothian Mines, ranging amongst the old¬est in the district, partially taken from a report of Col. Wooldridge, in 1841. Coal was mined in this neighborhood as early as 1700, and used (then so-called extensively) in the vicinity in 1775. A

Jan 1, 1876

R. S. Shoemaker: Our first question is, is there a need for a grizzly before a primary crusher? What is its effect on crusher capacity and crusher maintenance? Is it worth the extra capital cost in a crusher installation? Vincent: ASARCO has a grizzly at Mission. Utah Copper uses grizzlies ahead of their gyratories. There is some quite abrasive ore at Mission, an argillite type of rock, which has a work index of 16.5 to 20, which is getting up toward the taconite classification. We get a life of 12- 16 million tons per set of concaves or per mantle with the grizzly ahead of the crusher. At Duval Corp., some 6 miles to the south of Mission, their crusher installation on a good, hard rock does not have a grizzly, and the last information I had is they get a life of about 2 ½ -3 million tons on their mantle and concave. At Silver Bell, our other copper unit in Arizona, they do not have a grizzly ahead of the gyratory and there they get a life of about 5-6 million tons. At Utah Copper, which we all know is a fairly soft ore, relatively speaking, they get a life of 24-27 million tons with grizzlies ahead of the crushers. I think a grizzly has a very definite effect on the life of the mantle and the concaves. As far as a jaw crusher is concerned, I think that usually it is desirable to have a grizzly if it is properly designed, which means it is self- cleaning. Otherwise I would not like to see one in the circuit.

Jan 9, 1967

By Robert I. Kingman

SUFFICIENT testing has been performed with the Dutch State Mines Cyclone for thickening and desliming flotation feed at the concentrator of the National Lead Co., Tahawus, N. Y., to prove its application for this work. It is the purpose of this article to present some of the test results, operational details and advantages of cyclone thickening and classification. The metallurgy of the mill operation was described by Frank R. Milliken, assistant manager of the titanium division.l The present flowsheet for the recovery of ilmenite consists in grinding the crushing plant product in four open-end rod mills in closed circuit with mechanically vibrating screens to approximately -20 mesh. The screen undersize is treated in Crockett magnetic separators which produce three products: magnetic concentrate, nonmagnetic tailing containing ilmenite and gangue, and a Crockett slime overflow. The non- magnetic tailing is classified into eight sizer spigots products and a classifier overflow. The spigot sand products are tabled separately to produce a rough ilmenite concentrate, a middling product and a tailing. The table middlings are returned to Crockett feed. The table concentrate is dewatered and dried and further concentrated on Wetherill magnetic separators to produce the finished ilmenite concentrate.

Jan 8, 1950

By G. Richards Gwinn

Graphite is one .of the so-called minor nonmetals that have become of major importance during the present conflict. Requirements of the domestic industry for graphite are relatively small and uses have changed so greatly in the past 25 years that different types, with few exceptions, are more nearly interchangeable in use. However, the quality of the graphite required for crucibles is exacting and under present manufacturing practices only a small part of the world production can be utilized economically by this industry. Graphite, for the domestic crucible industry, was supplied almost entirely by imports from Madagascar and Ceylon before the present war. The quantity required has been increased by the war and the greatest demand is for Madagascar flake. The fall of France to Germany in 1941 and the Japanese expansion southward threatened our supply of crucible-grade graphite, therefore the domestic industry was revived to supplement imports and to act as insurance in the event of complete stoppage of imports. Two plants were constructed for the Government, one at Ashland, Alabama, called the Crucible Flake Graphite Co., operated by Haile Mines, Inc., and one near West Chester, Pennsylvania, operated by the Benjamin Franklin Flake Graphite Co. Loans were made by the Reconstruction Finance Corporation to the Alabama Flake Graphite Co. at Ashland, the Ceylon Graphite Co., at Goodwater, Ala., and the Southwestern Graphite Co., at Burnet, Texas. However, by the end of 1943 the import situation had improved and it was no longer necessary to continue Government assistance to mine and stock-pile the high-cost domestic material. Graphite is found in virtually every country of the world. Most occurrences are of no economic importance because of their poor quality, prohibitive mining and milling costs, inaccessibility, and poor location with reference to the industrial centers where graphite is used. The principal commercial deposits are found in Ceylon, Madagascar, Chosen (Korea), United States, U. S. S. R., Canada, Germany, and Mexico. Graphite is a typical international mineral in that it is utilized mainly in countries noted for industrial activities, whereas the two islands, Ceylon and Madagascar, which produce the major part of the world's high-grade graphite, are virtually devoid of any manufacturing establishments requiring its use. The industry thus is violently disturbed by wars. Types oF Graphite Used in Crucibles Graphite of various kinds and from many countries has been used for making crucibles. Passau (Bohemian) flake was first used in Europe, but by the middle of the seventeenth century crucible formulas were established largely on Ceylon graphite and German Klingenberg clay. Ceylon graphite is granular and the grains are subdivided into more or less

Jan 1, 1948

By G. Richards Gwinn

Graphite is one .of the so-called minor nonmetals that have become of major importance during the present conflict. Requirements of the domestic industry for graphite are relatively small and uses have changed so greatly in the past 25 years that different types, with few exceptions, are more nearly interchangeable in use. However, the quality of the graphite required for crucibles is exacting and under present manufacturing practices only a small part of the world production can be utilized economically by this industry. Graphite, for the domestic crucible industry, was supplied almost entirely by imports from Madagascar and Ceylon before the present war. The quantity required has been increased by the war and the greatest demand is for Madagascar flake. The fall of France to Germany in 1941 and the Japanese expansion southward threatened our supply of crucible-grade graphite, therefore the domestic industry was revived to supplement imports and to act as insurance in the event of complete stoppage of imports. Two plants were constructed for the Government, one at Ashland, Alabama, called the Crucible Flake Graphite Co., operated by Haile Mines, Inc., and one near West Chester, Pennsylvania, operated by the Benjamin Franklin Flake Graphite Co. Loans were made by the Reconstruction Finance Corporation to the Alabama Flake Graphite Co. at Ashland, the Ceylon Graphite Co., at Goodwater, Ala., and the Southwestern Graphite Co., at Burnet, Texas. However, by the end of 1943 the import situation had improved and it was no longer necessary to continue Government assistance to mine and stock-pile the high-cost domestic material. Graphite is found in virtually every country of the world. Most occurrences are of no economic importance because of their poor quality, prohibitive mining and milling costs, inaccessibility, and poor location with reference to the industrial centers where graphite is used. The principal commercial deposits are found in Ceylon, Madagascar, Chosen (Korea), United States, U. S. S. R., Canada, Germany, and Mexico. Graphite is a typical international mineral in that it is utilized mainly in countries noted for industrial activities, whereas the two islands, Ceylon and Madagascar, which produce the major part of the world's high-grade graphite, are virtually devoid of any manufacturing establishments requiring its use. The industry thus is violently disturbed by wars. Types oF Graphite Used in Crucibles Graphite of various kinds and from many countries has been used for making crucibles. Passau (Bohemian) flake was first used in Europe, but by the middle of the seventeenth century crucible formulas were established largely on Ceylon graphite and German Klingenberg clay. Ceylon graphite is granular and the grains are subdivided into more or less

Jan 1, 1948

By K. A. Grace

Reserves are the basic foundation of any mining enterprise, but a lack of understanding of the concept of resources and reserves is still a frequent cause of failure in mining ventures. A review of the development of the resource-reserve concept emphasizes the necessity for a common language, and the classification system as set out by the US Geological Survey and Bureau of Mines is advocated as the basis for this. Because of its strong economic connotation, the term reserves should be severely restricted in its use, and should encompass mining and processing factors. Modifications to the basic definition of reserves to accomplish this are proposed. Caution must be used in the quantification of undiscovered or hypothetical resources, particularly in juxtaposition with known resources data.

Jan 1, 1985