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By J. Landau, A. Dim, R. Houlihan

Recent developments in the application of solvent extraction in hydrometallurgical processing make it desirable to reassess the present state of availability of suitable equipment for these applications. The range of solvent extraction applications now includes very large scale applications with a modest demand on separation performance (the treatment of some base metals) and applications in which the decisive factor is a very high requirement on separation performance. The extraction column to be described in the present paper is of the type in which mechanical energy is provided for the two- liquid system inside the column. The active elements for this are reciprocating sieve plates designed and mounted so as to uniformly load the driving mechanism, to eliminate vibration of the plant, to have sufficient control over the degree of dispersion of the dispersed phase, and to reduce axial mixing effects, which are highly detrimental to the separation performance of production-scale plant. The operating features of the reciprocating-plate column will be illustrated mainly by experimental results obtained on a 4" diameter column in the extraction of uranyl nitrate with TBP. Some mechanical features of the operation of reciprocating-plate columns will also be discussed.

Jan 1, 1973

By M. L. Jeremic

Abstract-Observations of ground behavior in mining the Choka Dulkan ore body have been described. Ore recovery was limited to approximately 60% because unconsolidated hydraulic fill did not permit either the widening of stope spans nor secondary ore recovery from pillars. Stope undercutting induced high stress concentrations. However, as extraction progressed, ground conditions improved but before extraction was complete they deteriorated again. After completion of a stope, the remnant rib and crown pillars continued to be deformed by other stresses for some time.

Jan 4, 1978

By J. H. Wiggins

This paper first pictures the economic phase of evaporation losses and the actual evaporative conditions in handling and storing crude and gasoline in the United States; then follows a discussion of some of the theories of physics involved in evaporation loss and lastly an application of these theories to handling oil and gas on producing properties. GRANTING that about 600,000,000 bbl. of light oil will be produced in the United States this year and taking the Bureau of Mines' statement that 7 1/2 per cent. of the total crude production will be lost before the finished gasoline is shipped from the refinery, the volumetric evaporation will be 45,000,000 bbl. of the cream of the gasoline. This is a conservative figure and is equivalent to 1,890,000,000 gal. The real value of this liquid is at least 150 per cent. of the value of an equal volume of motor fuel. At only 10 c. per gal., the value lost is $189,000,000; at 15 c. per gal. the loss is $283,000,000. If 750,000,000 bbl. of light and heavy oil are produced here this year and the average price per barrel is $1.333, the gross return to producers will be $1,000,000,000 and the net returns about $200,000,000, if the cost of production is only $1 per barrel. Thus, the evaporation bill is about 20 per cent. of the gross income and is equal to the net income of the crude-oil producers. Two other comparisons with popular phases of the petroleum industry will help give an adequate conception of the evaporation problem. These are: cost of preventing evaporation compared to cost of cracked gasoline and volume of gasoline evaporated compared to volume of gasoline manufactured from natural gas.

Jan 7, 1924

By W. Z. Price

The coal lands that the Nemacolin mine is to develop embrace over 8400 acres; the tract is oblong and its eastern edge is along the Monon-gahela river. As shown in Fig. 1, the mine is divided into two parts (the North mine and the South mine) by a 150-ft. barrier, which however, is cut through at intervals by haulageways. Each part is fed from seven main entries—a loaded track, an empty, a manway, and four return air courses. The loaded tracks converge at the shaft bottom but the empty roads maintain their identity throughout their length. With three intakes and four returns on either side, there is ample room for expansion of air and every facility for ventilating is provided. The four south air courses converge into two, crossing the shaft bottom, and then into one at the south side of the air shaft. The four north air courses converge in a similar manner on the west side of the same shaft. This convergence is accomplished by concrete arched

Jan 1, 1927

By Edwin H. Olson, Morton Smutz, Charles J. Baroch

IN 1949 an orebody containing some 10 billion lb of recoverable rare earth metals was discovered in the Mountain Pass district of San Bernardino County, California.1 The following year Molybdenum Corp. of America purchased a number of claims at the deposit and a mill on the property which had been constructed to process the district's gold ores. Average composition of ore from the San Bernardino deposit is less than 0.1 pct ThO2, 25 to 35 pet calcite, 10 pet rare earth oxides, 15 to 20 pet silica, and 30 to 40 pet barite.2 Rare earth content of the ore analyzes 50.7 pet CeO2, 4.2 pet Pr6O11, 11.7 pet Nd2O3, 1.3 pet Sm2O3, and 34.3 pet La2O3, and others.2

Jan 3, 1959

By Charles Means

A THOROUGHLY modern coal-handling system has been installed at the Pittsburgh Terminal R. R. & Coal Co.'s new No. 8 shaft, or Coverdale mine, about 11 mi. (17.7 km.) from Pittsburgh on a spur f the Montour R. R. The Pittsburgh seam, 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 their 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.

Jan 9, 1921

By J. A. Musselman, J. B. Cheatham

In recent years considerable effort has been expended in the search for new ways of drilling into the earth's crust and for improvements of existing methods. A number of novel techniques have been explored such as explosive, flame, electric arc, abrasive jet, chemical, and various percussion-type dri1ls.l Some of the new methods are useful in isolated situations, but rotary drilling continues to be the most versatile and generally economical method for rock drilling. An understanding of rock failure during drilling can lead to improved rotary drilling techniques and to the development of new methods. Experiments 2-4 have shown that rock strength and ductility increase with increasing pressure; therefore, meaningful experimental investigations should be carried out under conditions similar to those encountered at the depths to which oil wells are drilled. The action of a roller-cone bit is not pure rolling in all cases but frequently involves gouging and scraping action. However, vertical penetration of a horizontal rock surface by a single punch has served as a first approximation of the rock/bit tooth interaction during drilling.5,6 In these experiments semi-infinite smooth rock surfaces are indented by steel tools with configurations having various degrees of dullness. Both static and dynamic tests have been investigated; however, static loading provides a good approximation of the loading rates occurring during rotary drilling. As a more realistic approximation to actual drilling conditions, chip generation must also be considered. Recently, studies have been made of indexing or chipping from a bit tooth to a previously formed crater.7-9 The purpose of the present investigation is to study indexed penetrations in greater detail. Fig. 1-A illustrates the general problem. Pittman and Cheatham 10,11 have used plastic limit analysis to study the idealized plane-strain indexing problem for a material having a linear Coulomb-

Jan 1, 1972

By James E. York

The honor so fairly earned and so incompletely and tardily paid to Henry Cort, the inventor of the puddling-furnace and the rolling-mill, has been fully set forth by Mr. Charles H. Morgan,' and needs no further emphasis here. In view of the importance of the rolling-mill in the treat ment of iron and steel, the paucity of information concerning it is surprising. With the exception of a book, written about 35 years ago, by Peter Ritter von Tunner, an Honorary Member of this Institute, and of desultory articles on simple sections, which have appeared in technical journals, I know of no publication attempting to treat this subject, although volumes have been written on the scientific theory and technical manipulations involved in other branches of the iron- and steel-industry. This strange anomaly may be due to the fact that roll-turning cannot be called a scientific business. It does not ordinarily come within the range of an educated engineer; yet it cannot be performed by an ordinary mechanic. It demands some of the qualifications of an engineer, in designing, and those of a mechanic, in execution. The men who have followeci this trade have controlled the training of their successors. In many cases the technical knowledge required has

Jan 1, 1907

By Read Winterburn

This discussion covers only one method of pressure drilling—that developed in the Kettleman Hills field. Thus it is probable that many departures from the procedure herein described would be advisable, and perhaps necessary, in using this method of drilling wells in other localities. Purpose of Pressure Drilling By the early part of 1936, formation pressures in the heavily produced north end of the Kettleman North Dome field had declined to range from 1000 to 1500 lb. per sq. in. This low pressure, combined with the depth of the wells (8000 to 9000 ft.) permitted water to be filtered out of the mud into the producing sands during drilling operations. The loss of water was indicated by loss of fluid from the suction tank while drilling, accompanied by an increase in mud weight. It was found that when water was added to the mud stream at such a rate as to keep the fluid level in the suction tank constant, the mud weight would not vary. This indicates that water only was forced into the sands. The rate of this loss at various wells ranged from 2 to 5 bbl. per hour. At some places complete loss of circulation occurred, and drilling mud to the extent of 200 to 1000 bbl. had to be pumped into the sands before returns were regained. It was believed that these conditions had already begun to harmfully affect production, and that such effect would become more pronounced as formation pressures continued to decline. Pressure drilling with oil was introduced because it eliminated the danger of loading the formations with mud and water. The method also afforded a convenient means of testing as drilling progressed, lessening the amount of formation testing, which had become necessary because of encroaching edge water.

Jan 1, 1938

By Alfred James

John Stewart MacARthUr, born in 1856, was the son of Robert MacArthur of Glasgow, and came of Scots stock distinguished for character and religious conviction. His election as elder of the Free Kirk gave him greater pride than the receipt of the gold medal of the Institution of Mining and Metallurgy. The former honor was for character— it marked him as a son worthy to follow in his father's footsteps; the latter was awarded for his life work of eminent service to the gold industry. Cheery optimism, resolution, tenacity of purpose, and industry ever characterized his actions. Apprenticed to the Tharsis Sulphur & Copper Co., his work on the chemical staff brought him to the notice of the Cassel Gold Extracting CO.,. at that time struggling with an unworkable electrolytic process..He was engaged by that company, in 1886, as technical manager and before long brought out the perchloride process, which was speedily followed (in 1887) by the epoch-making cyanide process. This process revolutionized gold mining and directly led the way to the elevation of the mining engineer to the most broadly trained product of the engineering profession. A noteworthy feature of the cyanide process was its completeness when introduced. Over thirty years have elapsed and the use of the process has been worldwide, but no suggested improvement has stood the test of time. The extension of the process to the beneficiation of silver ores—containing far more metal per ton and thus requiring the employment of stronger solutions—has brought us the Merrill and Crowe improvements in precipitation and the Nipissing desulfurization process for certain silver-hearing minerals. Roasting apparatus, fine crushing, filtration, and settling equipment have all aided the extension of the process in and from its original field. As Hennen Jennings put it,, the cyanide process today is essentially that of 1890. This self-containedness of the cyanide process arose from no mere chance; it was directly due to MacArthur. It was he who personally investigated every known method of precipitation and then every form of zinc from sheet, punchings, filings, millings, rods and shaving down to fume; it was he who investigated the effect of protective alkalies, of so-called accelerators, and of the addition of lead salts; he was determined to leave nothing to chance.

Jan 1, 1921

By H. E. Doerr

THE writer has been unable to find much information relative to tests made to determine the effect of forging on the specific density of steel. The opinion, however, among men engaged in the business, seems to he that forging greatly compresses or consolidates the steel. While such is doubtless the case with spongy or porous steel, the following experiments indicate that there can be little or no change in the density with steel initially free from cavities: Ten ingots of basic open-hearth steel cast as shown in Fig. 1 were used in the experiments. All the specimens were 0.53 carbon with all other elements the same, the analysis being determined from drillings taken midway between the center and outside of the upper end, as shown in Fig. 2. The specimens were selected from over one thousand ingots so that the tests could be comparative for the work done in forging only, but no two of the ingots were cast in the same heat. Each ingot remained in the mold approximately 30 min., when it was removed and air-cooled. About 12 hr. later, when the temperature had been reduced to approximately that of the surrounding atmosphere, the head was discarded and the ingot heated in an oil furnace to approximately 2250° F. (1235° C). Approximately 1 min. was required to forge under the steam hammier to 1 ¼ in. (31.75 mm.), rough diameter, as shown by the dotted lines in Fig. 2. All ingots were allowed to air-cool after forging. Cylinders ½ in. (17.7 mm.) in diameter and ½ in. high were then turned from the forged and unforged parts of the ingots and numbered. The ten pairs of specimens were submitted to Louis E. Endsley, Professor of Railway Mechanical Engineering, University of Pittsburgh; A. N. Talbot, Professor of Applied Mechanics, University of Illinois; L. Z. Slater, chief chemist, Scullin Steel Co., St. Louis, Mo. No in-formation was furnished as to which specimens were forged or unforged and each laboratory used the same specimens, submitting the average of three independent determinations, a tabulation of which is shown in the accompanying table in which the laboratories are designated by

Jan 1, 1919

By R. G. Woolery

INTRODUCTION Since 1975, Union Carbide Corporation has been conducting uranium exploration in southwestern South Dakota. This program has resulted in the discovery of an ore body about eight miles north of Edgemont in Fall River County. The site which was previously mined for uranium in the 1950's and 1960's consists of 950 lode claims (approximately 20,000 acres) and is within the Black Hills National Forest. Preliminary development plans indicate that fewer than 200 surface acres will be involved in the mining and heap leaching of the ore. The ore occurs in both the Fall River and Lakota formations. The exploration to date has developed something in excess of two million tons of ore averaging -0.1% U308. About 75% of the ore is expected to be mined from underground with 25% coming from five to seven small pits. The surface mining will be extensions of previously mined areas with a disturbance of 35-40 new acres near 35-40 previously disturbed acres requiring a total reclamation of 70-80 acres. Several options for processing the ore including conventional milling by UCC, conventional milling in joint venture with another producer, and heap leaching are under consideration. This paper is concerned with the preliminary assessment of the heap leaching option based on the limited test work conducted on surface samples and on available cores from the deeper ones. The final design for a commercial operation will not be available until an underground bulk sample has been obtained and evaluated. Union Carbide has been operating heap leach facilities commercially since 1973 at Gas Hills, Wyoming and Maybell, Colorado. During this period, we have made considerable progress in heap construction

Jan 1, 1983

By T. R. Young, S. A. Scott

9.5-1. Introduction. The use of pipelines to transport solids has been successfully accomplished with many different materials. One of the oldest applications is the dredging and placing of hydraulic fill. Many installations have been made and operated for long periods of time with excellent dependability, low operating cost, and low maintenance. It is not the aim of this chapter to give the engineer the answers from which to design a pipeline, but rather to supply helpful information from which to start the project. There are several phases of solids pipelining which as yet have not lent themselves to quick engineering answers. Investigations have been carried on by many, with several theories advanced by the various investigators. In recent years certain notable theoretical advances in hydraulic transportation have been achieved. Vertical transport, using balanced "leg" operation, now appears competitive with other forms of vertical transportation. In addition, horizontal transport utilizing capsules has been proven experimentally to be attractive because of lower pressure drop than the conventional methods of solid transport in fluid media. With the aid of the computer, the laborious calculations associated with pumping calculations have been greatly simplified; and with this tool the pipeline engineers of the future will undoubtedly be able to develop a more comprehensive understanding of solids-fluid transport. 9.5-2. Theory. There have been many excellent studies made and information is available in the literature, but a general comprehensive theory of pipeline transportation of solids has not been advanced. The existing flow theories will give approximations for minimum and optimum flow velocities, friction head losses, energy requirements, and pump and pipe size The principles of dynamic similarity and scaling laws are well understood for the flow of pure liquids. There are no firm methods of scaling slurry pipelines of small diameter to larger diameters except for a few empirical.

Jan 1, 1968

By C. K. Leith

At the outset I would like to make it clear that I do not enter this discussion in a controversial spirit, but in an attempt to contribute something helpful to an understanding of a difficult problem. I have too high regard for the- sterling quality of the work of the men who have studied this subject in detail to offer anything in the way of essential contradiction to their statements of fact. Difference of opinion arises from differing valuation of the possible alternative hypothesis which these facts suggest. Some degree of recrystallization in limestone contact zones has been recognized by many investigators. Earlier investigators, for the most part, assigned an important, if not the most important, ro1e to recrystallization in development of these zones. With the growing recognition of introduction of ores and gangue materials into the contact zone from igneous rocks through the medium of primary magmatic solutions, there has been a tendency to ascribe to this process most, if not all, of the chemical and mineralogical characteristics of the contact zonc. This has involved a correspondingly diminished emphasis on recrystallization of substances already there as a factor in the process, and in some cases even the complete elimination of this hypothesis. From detailed study of a few contacts, casual observation of others, and a general familiarity with the literature, some of us have been led in recent years to raisc the question whether the pendulum has not swung too far away from recrystallization toward direct introduction from igneous sources, and to argue for more recognition of the part played by recrysta11ization.l The inevitable sequence has been that those of us who have .taken this view have been charged, at least by inference, with emphasizing recrystallization to the total exclusion of the alternative process. Scientists, like other men, like to classify and pigeon-hole views under simple and definite designations, leaving out qualifications which would tend to make the classification more difficult to state. This has made the problem seem more definite and simple, but has tended to obscure the fact that the disagreement is primarily not one relating to essential facts, but one of

Jan 1, 1915

By Charles Baker

THE district of Catorce, San Luis Potosi, ranks among the first half-dozen silver-producing camps f Mexico. Mining has been more or less continuous there for 150 years. The large producing mines, Mapum, Mazapil, Palomas, Musquiz, Minas Virjas, now for the most part idle or abandoned, are grouped around the head of two valleys: one, which drains to the west, falls 2000 ft. (609.6 m.) in 4 1/2 mi. (7.2 km.) between the main Catorce and the western foot of the range and is characterized by steep canon walls; the other, east of the main town of Catorce from which it is separated by a high divide, heads in a number of steep tributaries above the basin in which lies the town of Potrero and flows nearly north for 10 mi. (16 km.) to the northern base of the range; below Potrero, it has for the most part gently sloping valley walls and a broad valley floor. The Sierra Catorce is the highest range of the region, the summits reaching altitudes of over 11,000 ft. With the exception of a few cliffs of the erosion escarpment of the lower limestone and the canon walls below the main town of Catorce, which is the highest town in Mexico, the gently rounded slopes are characteristic of a maturely eroded mountain range composed of folded sedimentary rocks. As is usual in desert regions, the heavy-bedded limestones are the most resistant to erosive forces. Folded into anticlines, they form the mountain ranges; and the intermontane valleys and basins, originally carved out of less resistant shales, clays, marls and sandstones, are covered by debris forming a mantle with surface gradually rising upwards toward the hills. In time, the debris buries, in deposits formed from their own ruins, all but the highest summits of the original mountains; some f this region has already nearly reached this stage. Most of the debris is firmly cemented by calcium carbonate (caliche). Solution f the limestone by meteoric waters afforded the supply of lime carbonate, which has been redeposited upon evaporation of the waters as a cement binding the boulders, pebbles, and finer detritus.

Jan 9, 1921

Discussion of the paper of PAUL BILLINGSLEY, presented at the New York meeting February, 1915, and printed in Bulletin No. 97, January, 1915, pp. 31 to 47. JAMES F. KEMP, New York, N. Y.-Mr. Billingsley has spoken so concisely that we may not realize the many important topics which he has passed in review and upon which lie has thrown much illumination. The exact determination of the age of the granite, itself, is one. If we were to look over a geological map containing the region of Butte and 25 years old, we would find this coarsely crystalline mass assigned, as were others of its kind, to the pre-Cambrian, or as we used to say, to the Archean. In the course of time it was found to be later. The Butte Special Folio, 1907, described it as post-Carboniferous and possibly post-Laramie. Mr. Weed in Professional Paper No. 74 of the U. S. Geological Survey (1912) placed it as probably Niocene because of its relations with the andesite, which was believed to be Eocene. Mr. Billingsley now by a very neat demonstration circumscribes it more definitely and we recognize that it must be latest Cretaceous or earliest Eocene. We see, however, that extensive field observations, ably correlated, were necessary to establish the conclusion. For some years all familiar with Butte have known that there was a central area the veins of which carried copper ores in a quartz gangue; and that outside this area there were veins carrying silver ores in a gangue of manganese minerals. Mr. Sales's able and detailed paper, read at the Montana meeting, August, 1913, not only corroborated these relations, but emphasized the transitional character of the intermediate or passage zone. Mr. Billingsley is now able to show from observations at increasing depths, the tendency of the copper ores to appear deep down in the veins

Jan 5, 1915

By J. M. Glass, C. D. Sholtess

We at Hughes Tool Co. are extremely proud of the quality of the hardware and techniques introduced through our efforts in tunnel-machine development and of the ready acceptance of them by manufacturers and contractors throughout the world. All of us who attended the conference and who are represented in the book, we believe, anticipate an increasing need for improved methods of underground excavation. The development of such methods will permit the further exploitation of our underground resources plus providing underground space for transportation and habitation at a rate compatible with demand. We hope that our comments, derived from the application of Hughes Tool Co.'s rotary boring experience, may provide a better understanding of the boring method as a possible avenue through which the desired improvement in underground excavation may be attained. We hope you may also become aware of some of the problems Hughes, as a pioneer developer of raise, shaft, and tunnel-boring equipment, must face prior to further major undertakings in this very interesting field. Our task is to acquaint you with the present status of the Hughes Tool Co. development program as it relates specifically to tunnel-boring machines. We feel this task can best be accomplished by a brief review of the general sequence of events leading to and constituting an equipment development program and more specifically the manner in which these events have occurred to either influence or further our boring-machine development program. The development of a machine to accomplish a certain function or series of functions is usually a very long and tedious process to which any number of individuals must contribute, perhaps over a period of centuries. Of particular irony is the fact that often those who contribute most generously do not necessarily reap the greatest immediate benefit. A marketable ma- chine will, however, result from a sequence of events such as these: 1) A problem or need is defined. 2) An idea is born to eliminate the problem.

Jan 1, 1970

By Benjamin C. Greene, H. Beecher Charmbury

Water is a most remarkable substance, essential for life of all kinds. As well as needing water to survive, man has always used it for agriculture, transportation, recreation, and many other things. When our country was young and inhabited by few people, the streams, rivers, and lakes were able to provide all the clean water needed by man and take away all the wastes created. However, with our growing population and an ever-increasing demand for goods and services, the public, industry, and government at all levels have become acutely aware of the need to manage the nation's water resources more efficiently. Abundant energy from many sources has helped this nation to become the greatest industrial nation in the world. Coal has contributed a major portion of this energy, generating electricity, running railroads, and maintaining national security during wartime. The result has been the highest standard of living in the world and a time of widespread economic prosperity. The use of water in coal mining is somewhat different from its use in most industries. With the exception of water used in cleaning plants, for underground dust control, and for fire protection, most of the water en- countered in coal mining operations serves no useful purpose. In other words, it is an undesirable element and must be removed, otherwise it will interfere with operations, cause potential water quality problems, and may even stop operations by flooding. In the past, removing water from working areas of most mines was usually a fairly simple matter. Pumps with piping were installed at sumps or low spots in the mine and the water was pumped to the surface or to drainage control facilities constructed for the operation. Ditches were often used to collect and drain the water by gravity to the outside or to main sumps for pump discharge. In either case, the water was allowed to flow into the nearest stream or river. The concept of "water is water" was generally accepted without too much concern for what was in

Jan 1, 1981

By C. G. Brehm

The anthracite-producing region is in the northeastern section of Pennsylvania, and has an area of approximately 484 square miles. It is divided geographically into three separate fields, known as the Northern, Middle and Southern. The Northern field, with Wilkes-Barre approximately at its center, is a basin about 60 miles long and almost 6 miles wide at its greatest distance across. Generally speaking, it may be said that the coal measures in this field lie horizontally, or on slight pitches, and consist of from 11 to 19 veins of coal, varying in thickness from several inches to several feet. The intervening strata between veins may be composed of slate, clay, rock or shale, or a combination of several, and are sometimes very thin. This condition often causes a treacherous roof, therefore roof support and the attending hazard of mining are problems of concern. The Middle field is made up of a number of small basins of not very great depth, and the measures, which are in like number to those of the Northern field, are varying inclinations running from nearly flat to steep pitches. The Lower, or Southern field, is made up of basins of great depth, some being 4000 ft. deep, and its measures are mostly on very steep pitches. In certain sections this Southern field is being mined at an elevation of 1300 ft. below sea level, on a pitch ranging from 50' to practically vertical, and because of the tremendous pressure and the inherent gas in the seams, outbursts of coal frequently occur at the face, locally known as "bumps." These outbursts are accompanied by a rumbling noise, after which gas is usually found. This condition makes mining a difficult and extremely hazardous undertaking, and unusual skill is required on the part of the miner to drive and maintain openings necessary to the production of coal. Miners working in such seams on the heavy pitch must carry face batteries (Fig. 1) to afford proper protection while working at the face, because of the outbursts and free running coal. To drive haulageways or gangways in this field it is

Jan 1, 1940

By C. G. Brehm

The anthracite-producing region is in the northeastern section of Pennsylvania, and has an area of approximately 484 square miles. It is divided geographically into three separate fields, known as the Northern, Middle and Southern. The Northern field, with Wilkes-Barre approximately at its center, is a basin about 60 miles long and almost 6 miles wide at its greatest distance across. Generally speaking, it may be said that the coal measures in this field lie horizontally, or on slight pitches, and consist of from 11 to 19 veins of coal, varying in thickness from several inches to several feet. The intervening strata between veins may be composed of slate, clay, rock or shale, or a combination of several, and are sometimes very thin. This condition often causes a treacherous roof, therefore roof support and the attending hazard of mining are problems of concern. The Middle field is made up of a number of small basins of not very great depth, and the measures, which are in like number to those of the Northern field, are varying inclinations running from nearly flat to steep pitches. The Lower, or Southern field, is made up of basins of great depth, some being 4000 ft. deep, and its measures are mostly on very steep pitches. In certain sections this Southern field is being mined at an elevation of 1300 ft. below sea level, on a pitch ranging from 50' to practically vertical, and because of the tremendous pressure and the inherent gas in the seams, outbursts of coal frequently occur at the face, locally known as "bumps." These outbursts are accompanied by a rumbling noise, after which gas is usually found. This condition makes mining a difficult and extremely hazardous undertaking, and unusual skill is required on the part of the miner to drive and maintain openings necessary to the production of coal. Miners working in such seams on the heavy pitch must carry face batteries (Fig. 1) to afford proper protection while working at the face, because of the outbursts and free running coal. To drive haulageways or gangways in this field it is

Jan 1, 1940