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By Stanley W. Sundeen

2.3-1. Introduction. The subject-"Preliminary Evaluation of Coal, Metallic and Industrial Mineral Deposits for Surface Mining'-seems at first glance to be definitive and not likely to be misinterpreted. Nevertheless, there are widely divergent opinions as to what is meant by "preliminary" and even as to what is meant by "evaluation." Some definition and qualification is necessary in order to provide a readily recognized basis for discussion. Evaluation evokes the idea of organizing extant data and judging its significance especially in the economic sense. It also may evoke the concept of the physical processes of acquiring the data that will characterize the deposit such as the geologic mapping, drilling, etc. Castle (5) considers that evaluation may embrace psychological aspects wherein human traits as, for example, over optimism might cause the evaluator to overlook obvious project weaknesses. In this chapter, evaluation is discussed primarily from the viewpoint of economically appraising a project from data available at a given point in time. The qualifying adjective "preliminary" is not easily defineable. In fact, some kind of evaluation proceeds, if not continuously, intermittently over the full span of exploration and early stages of development of a deposit. Bailly (1) comments: "Sometimes, before starting exploration in new areas or countries for a given commodity, we establish models to define what minimum combinations of re- coverable grade and tonnage are needed to give the minimum acceptable rate of return established by corporate policy. Then, before starting physical exploration in any target area we try and guesstimate optimistically what best 'geometry-grade-tonnage' can be expected. If these are acceptable in light of above minimum combinations, exploration is started as soon as funds are appropriated for the target area.''

Jan 1, 1968

By A. R. Powell

Four, general methods have been used in the study of the decomposition of coal. The first has been directed toward the processes of coal formation, the second has been by means of microscopic studies, the third from the data of destructive distillation, and the fourth has made use of various solvents. Applying these methods to the sulfur of coal, it has been found that the organic sulfur of plant and animal life enters into the formation of coal and remains in organic combination in the final product. The inorganic sulfur is almost entirely combined as iron pyrites and marcasite. The infiltration of hydrogen-sulfide waters is doubtless a large factor in these combinations. Sulfates are found in very small quantities except where free oxygen has entered the coal strata. The mechanical mixing of detritus with the early coal material is another source of sulfur. In this case the sulfur is distributed in microscopic particles throughout the mass. In destructive distillation, a part off the sulfur comes off as hydrogen sulfide and various thiophen compounds, but this furnishes little information as to the nature of the sulfur compounds in the coal itself. The use of solvents has given valuable data concerning the sulfur compounds in coal. Fremy1 and later E. Guignet2 noted the action of alkaline solutions on coal after treatment with nitric acid and Anderson and Roberts3 showed' the presence of large quantities of organic' sulfur in the extract so obtained. In a study of the phenol extract of coal, Parr and Hadley4 found organic sulfur in the soluble organic material. These investigations proved the presence of organic sulfur in coal in addition to the inorganic forms, such as iron pyrites and sulfates. T. M. Drown5

Jan 9, 1919

By E. C. Tveter, R. B. Tippin

The separation of minerals by heavy liquids is a standard laboratory technique which goes back at least 50 years, but commercially economic application of this principal to ore concenfration has been prevented by problems of liquid recovery. Recent investigations which demonstrate the different types of liquid-solid systems on various ores using the two major heavy liquids - methylene bromide and tetra-bromoelhane — are discussed in this article. As a result of these studies, over-all liquid recovery, and especially desorption of heavy liquid from the mineral surface, was improved by the use of surfactants as well as both thermal and mechanical energy. The examples given in the article indicate that heavy liquids which should find major commercial use in ore concentration are now available. The sink-float process using a heavy liquid medium has long been recognized as a nearly perfect method of mineral separation based on the differences in density of the minerals. The use of heavy liquid separation (HLS) offers the potential of an ore dressing method that provides the maximum possible natural concentrate grade and high recovery. In addi- tion the process requires no water, causes no waste disposal problems, and is extremely simple — the crushed ore is merely introduced into a liquid whose density is between that of the minerals to be separated. The minerals lighter than the liquid float while those heavier than the liquid sink. As such, HLS has become a standard laboratory tool but major commercial application has been prevented by the requirement for complete recovery of the heavy liquid, imposed by economics and materials handling hazards. Investigations, both in the United States and abroad, have shown that improved liquid stability as well as improved chemical engineering techniques brighten the future for HLS in ore dressing. The available commercial heavy liquids suitable for mineral separation cost from $2.00 to $20.00 per gallon1 and on this basis alone their complete recovery is economically desirable. Possibly of even greater importance is the fact that any residual heavy liquid remaining on the products could create a serious toxicity hazard. Consequently, to make the process commercially attractive requires (1) essentially complete removal of the liquid from the ore products and (2) optimum recovery of the liquid for reuse. Until recently these two stipulations have remained as obstacles but laboratory and pilot plant research now in progress suggests that these may soon be overcome. Various heavy liquid recovery systems have been proposed to meet these requirements and might be classified into one or more of the following three general classes: Solvent Wash (Fig. 1): The dissolution of the heavy liquid from the ore with a less expensive solvent,

Jan 1, 1969

JUDGE Samuel E. Schull, in the Court of Quarter Sessions of Monroe County, Pa., handed down a decision on July 2, declaring the Pennsylvania law for the Licensing of Professional Engineers and Land Surveyors to be in violation of the Constitution of the State of Pennsylvania and also of the 14th amendment of the Constitution of the United States. The case was that of George E. Stevenson, who was arrested in June, 1922, charged with the practice of the profession of land surveying without first obtaining a state license. Mr. Stevenson had had forty years of practical experience as an engineer and land surveyor, and as set forth in the findings "had attained unusual skill, distinction and reputation in his said profession, and, on said date and for a considerable period thereto-fore and down to the present time, was and is President of the Engineer's Society of Northern Pennsylvania." That part of the decision referring to the unconsti-tutionality of the act is quoted in full as follows: This matter now comes on to be heard on argument as to the constitutionality of the said Act of May 25, 1921, P. I. 1131. The defendant urges that the same is unconstitutional: First: Because it is in violation of Article 3, Section 3, of the Constitution of Pennsylvania, which provides: "No bill, except general appropriations bills, shall be passed containing more than one subject which shall be clearly expressed in its title." Second: That the same is discriminatory and, therefore, in violation of the 14th Amendment of the Federal Constitution. In this case, we: are confronted by the Act of Assembly bearing the title "an act to regulate the practice of profession of Engi-neering and Land Surveying; creating a State Board for Regis-tration of Professional Engineers and Land Surveyors; defining its powers and duties, imposing certain duties upon the Common-wealth and Political subdivisions thereof, in connection with public work and providing penalties." We meet in the title of this act, a recognition of the fact that it is the legislative intent to deal with two professions: First: Engineering. Second: Land Surveying.

Jan 8, 1923

By L. R. Woodyatt, H. J. Beattie, C. T. Sims

Theories correlating the formation of u and related intermetallic compounds to the electron-per-atom density of binary and ternary alloys have appeared regularly in recent technical literature. These same principles can be modified and applied to complex precipitation-strengthened alloys such as the iron-, cobalt-, and nickel-base superalloys and the stainless steels. Since these complex alloys contain carbides and other phases that normally precipitate before the U-type phases, the nature and amount of the precipitated phases must be calculated first. The following general formula is then applied to the residual matrix composition of the alloy: element. The magnitude of the resulting number is indicative of whether the alloy will form a a -type phase. When these calculations (which are computerized) are systematically applied to alloys of knoun phase analysis, a breakoff in average electron-vacancy number is noted between U-free and U-prone alloys. Alloys with an average electron-vacancy number higher than the breakoff form a-type phases, while those with lower ones do not form these phases. This method could then be used to eliminate from consideration all experimental compositions that would precipitate undesirable phases. It also is useful in evaluating analyzed heats of alloys where minor heat-to-heat variations determine whether the alloy is o-free or o-prone. THE highly significant development of strong, ductile superalloys to provide reliable construction materials in the 1000" to 2500° F temperature range has been due principally to unremitting application of Edisonian techniques and logic by the dedicated physical metallurgists who have shouldered this responsibility. Tools such as the electron microscope, phase analysis, and computers to accomplish regression analyses have been used heavily, but the effort has been essentially practice of an art, rather than a science. The objective of this paper is to describe and illustrate application of some relatively fundamental principles to certain of these alloy systems in an attempt to remove some of the empiricism from the technology. Specifically, the work presented here deals with the use of periodic-group relationships to predict the formation of intermetallic phases which can occur in primarily austenitic (fcc) structures. Calculations that have been developed might be applied in the design of new alloys and the evaluation of known alloys, and thus have the potential of eliminating vast areas of unnecessary alloy preparation and evaluation. ALLOYING CONCEPTS AND STRUCTURAL FEATURES OF SUPERALLOYS Strength is produced in austenitic superalloys by three principle mechanisms: 1) precipitation of y'; 2) formation of carbides; 3) solid-solution hardening by soluble refractory metals. The first mechanism requires the addition of aluminum and titanium, the second requires carbon and carbide-forming elements, while the third calls for the addition of molybdenum and/or tungsten. A considerable concentration of chromium is usually maintained to resist oxidation/corrosion, but it is also an important carbide-forming element. Fig. 1 shows a sketch and electron micrograph of the structure of a typical wrought nickel-base super-

Jan 1, 1967

By J. L. Jones

1. Brinell tests at progressively increasing temperatures are given for a representative lead-base and a representative tin-base babbitt, showing that the former has superior resistance to deformation at the working temperatures of bearings. 2. Small squares of bearing bronze, tinned and then babbitted with a representative lead-base babbitt and a representative tin-base babbitt were subjected to compressive loading. The lead-base babbitt showed less average compression than the tin-base babbitt. Compression did not materially increase the Brinell hardness of the babbitts. 3. A process and a tool are described for giving smoother and more accurate surfaces to bearings than has heretofore been possible. The following experiments have recently been carried out in the chemical laboratory of the Westinghouse Electric and Manufacturing Co., Pittsburgh, Pa. While the work is incomplete, it is described at the present time because data on the comparative merits of lead-base and tin-base babbitts are of interest in connection with the present shortage of tin. BRinell Habdness of Babbitt at Increasing Temperatures Bearings fail because of wiping, or deformation. Hence tenacity is desirable in a bearing metal, especially tenacity at high temperatures. The Brinell test is commonly regarded as a measure of tenacity. In fact, it has recently been proposed to substitute for Brinell hardness number the expression " tenacity number."l It seemed, therefore, that the Brinell test was especially adapted for the tests described. Disks, 4 in. (101 mm.) in diameter and 1.5 in. (38 mm.) thick, were made of the babbitts to be studied, designated A, B, C. They were poured into metal molds, pyrometer leads being soldered in the center of each disk. The composition of the babbitts was as follows:

Jan 1, 1919

By Luther Lennox

DURING the last few years, one of the great problems in the milling of all ores has been that of crushing. This subject involves not merely the cost of the operation, but also the selection of the proper degree and character of crushing to yield the best metallurgical results on the given ore. Considering the diversity of machinery, one is led to wonder at the variety of crushing methods employed, even when realizing that metallurgy demands varying products. In an attempt to investigate the relative crushing resistances of a number of ores now being milled in this country and Alaska, the management of the Portland mills requested samples of average mill-run of ore from various companies. The request met with a ready response, indicating the desire of all operators to gain information on the subject. The difficulties involved in this investigation were numerous, lack of time for outside problems during this strenuous period being a serious one. Also, we were unable, in the time, to obtain a correct 150-mesh . screen; in the screen analyses tabulated and plotted herewith, the 150 mesh screen was used merely to protect the 200-mesh screen, not to ascertain points on the curves.

Jan 8, 1918

By Walter B. Lenhart

Introduction and Importance of the Industry Sand, as described in this chapter, is a crude product used for ballast on railroads and highways, and as the fine aggregate in concrete, mortar, plaster and in asphalt paving materials. The sand used in glass, as a molding sand, and as a source of silica is described in Chapter 43. Sand and gravel together constitute the mineral raw materials of largest volume produced from the earth. In 1958, as reported by the U.S. Bureau of Mines,21 680,080,000 tons of sand and gravel (including industrial sand) were produced in the United States. The nearest competitor was crushed rock of which 532,818,000 tons were produced. Coal, both bituminous and anthracite accounted for only 431,616,689 tons in the same year. In dollar value, sand and gravel were exceeded only by cement, crushed rock and fuels. Hence it is a major unit of the mineral-producing industry. As an example, one plant in California operates around the clock at an average rate of 1,500 tons per hour, and at peak intervals has shipped over 4,000 tons per hour, all by trucks. Nevertheless, it is controlled by one man through a panel of push buttons that control the crushing, screening, washing, grading, stock piling, and reclaiming of the products. Because sand and gravel are low-valued commodities, but are used in every construction undertaking in every city, village, farm, dam and highway, they are produced in almost every county in the United States and southern Canada, by thousands of individual operators, very few of whom operate in more than one community. Many operations, particularly those established to supply the needs of major dams that are under construction, or of major segments of new highways, are temporary in nature, and the equipment installed is more or less portable. Because of the bulky nature of sand and gravel, there is very little interstate movement, and almost no exports or imports, except a little movement back and forth across the border of the United States and Canada. First, the material needs definition. Definitions Sand and gravel have been defined as continuously graded unconsolidated materials that appear in the earth's surface as a result of the natural disintegration of rocks. Both normally appear together, but in a wide variety of sizes, types and range of size classification. The American Society for Testing Materials has tentatively revised its definition of "sand" as: granular material passing the 3/8-in. sieve and almost entirely passing the No. 4 (4760-micron) sieve and predominantly retained on the No. 200 (74-micron) sieve, and resulting from natural disintegration and abrasion of rock or processing of completely friable sandstone (ASTM Designation C 58-55T). The Society's tentative revision of its definition of "gravel" is: granular material predominantly retained on the No. 4 (4760-micron) sieve and resulting from natural disintegration and abrasion of rock or processing of weakly bound conglomerate (ASTM 125-55T). Sand and gravel deposits contain materials from the finest silt to the largest boulders. Chemical definition of the two materials is nearly impossible. Sand and gravel always are

Jan 1, 1960

By James J. Bean

HE task of measuring the specific gravity of the -*- operating medium in a heavy-media separation system has never presented a particularly difficult problem because the medium is fairly stable and the overflow of the separatory vessel, as well as its underflow, can be sampled easily and accurately and the specific gravity of the suspension determined easily by weighing a known volume. However, while this method is simple and accurate it does require the operator to take the sample by hand and to weigh it and there is considerable temptation to avoid the periodic sampling if everything seems to be going well, or if something is occupying the attention of the operator. Furthermore all operators do not sample in exactly the same manner and considerable practice is required for two operators to be able to "check" each other to the last few hundredths, particularly if the sample is cut underneath the drainage screen where location of the point of sampling and load on the screens tends to influence the determination. While none of the above presents much of a problem, we have all recognized that some mechanical method of continuous measurement and recording would be advantageous since the operator would merely have to glance at the meter to check the gravity and to have an indication of the trend of any changes. Also if the instrument were of the recording type, a permanent record would be available for the guidance of the superintendent. The Eagle-Picher Mining and Smelting Co. was the first heavy-media user to actually install such a recording meter. In 1946 they installed in their Central Mill at Cardin, Okla., a specific gravity recorder manufactured by the Bristol Co. of Water-bury, Conn. R. A. Barnes, of the Bristol Co., working with E. H. Crabtree, Jr. and Elmer Isern, of Eagle-Picher, made the application and worked out the problems of sampling and measuring. Their attempts to measure the specific gravity of the medium in the cone itself were not entirely successful and they resorted to an outside sample tube for actually making the determination. Because of the particular flowsheet used, it was possible to tap off from the medium return pipeline a stream of medium and divert it into the sampling tube, which was provided with a constant level overflow and a spigot underflow, and into which the bubbler tubes dipped. The Eagle-Picher installation was successful and its possibilities were recognized by the Mineral Dressing Laboratory of the American Cyanamid Co. It was decided to install a similar unit in the heavy-media pilot plant to investigate further its possibilities. Chief among these was the continuous record which it was felt would be proof of the steadiness of the gravity in a heavy-media cone, something which is not always appreciated by POtential users. Because the heavy-media pilot plant is required to operate at a wide range of specific gravities, it was realized that the unit would have to record all gravities from 1.25 to 3.50, and do it to the nearest 0.01. It would not be necessary to record all of this wide range on a single chart and the method selected was to have 4 bands, each band range overlapping the other a small amount and calibrated so that with standard charts one division would represent 0.01 sp gr. A shift from one band to another could be arranged without alteration of the instrument itself, being accomplished by a simple change in the bubble-tube lengths, as described later. Accordingly, a recording type instrument was purchased and installed. Because there were some advantages in doing so, the first installation attempted to measure the gravity of the cone proper by placing the bubble tubes in the cone. This was not at all satisfactory and the second scheme utilized a fixed vertical screen at the surface of the cone, and an external sample-tube arrangement. We were particularly anxious to make this work as we felt it would be advantageous to measure the top level of medium where the separation was actually being made, but we were doomed to disappointment because it was impossible to keep the screen clean of float. Since the top gravity of the cone is the most convenient place to sample for control, a launder about 2 in. wide was installed longitudinally beneath the

Jan 1, 1951

By James J. Bean

HE task of measuring the specific gravity of the -*- operating medium in a heavy-media separation system has never presented a particularly difficult problem because the medium is fairly stable and the overflow of the separatory vessel, as well as its underflow, can be sampled easily and accurately and the specific gravity of the suspension determined easily by weighing a known volume. However, while this method is simple and accurate it does require the operator to take the sample by hand and to weigh it and there is considerable temptation to avoid the periodic sampling if everything seems to be going well, or if something is occupying the attention of the operator. Furthermore all operators do not sample in exactly the same manner and considerable practice is required for two operators to be able to "check" each other to the last few hundredths, particularly if the sample is cut underneath the drainage screen where location of the point of sampling and load on the screens tends to influence the determination. While none of the above presents much of a problem, we have all recognized that some mechanical method of continuous measurement and recording would be advantageous since the operator would merely have to glance at the meter to check the gravity and to have an indication of the trend of any changes. Also if the instrument were of the recording type, a permanent record would be available for the guidance of the superintendent. The Eagle-Picher Mining and Smelting Co. was the first heavy-media user to actually install such a recording meter. In 1946 they installed in their Central Mill at Cardin, Okla., a specific gravity recorder manufactured by the Bristol Co. of Water-bury, Conn. R. A. Barnes, of the Bristol Co., working with E. H. Crabtree, Jr. and Elmer Isern, of Eagle-Picher, made the application and worked out the problems of sampling and measuring. Their attempts to measure the specific gravity of the medium in the cone itself were not entirely successful and they resorted to an outside sample tube for actually making the determination. Because of the particular flowsheet used, it was possible to tap off from the medium return pipeline a stream of medium and divert it into the sampling tube, which was provided with a constant level overflow and a spigot underflow, and into which the bubbler tubes dipped. The Eagle-Picher installation was successful and its possibilities were recognized by the Mineral Dressing Laboratory of the American Cyanamid Co. It was decided to install a similar unit in the heavy-media pilot plant to investigate further its possibilities. Chief among these was the continuous record which it was felt would be proof of the steadiness of the gravity in a heavy-media cone, something which is not always appreciated by POtential users. Because the heavy-media pilot plant is required to operate at a wide range of specific gravities, it was realized that the unit would have to record all gravities from 1.25 to 3.50, and do it to the nearest 0.01. It would not be necessary to record all of this wide range on a single chart and the method selected was to have 4 bands, each band range overlapping the other a small amount and calibrated so that with standard charts one division would represent 0.01 sp gr. A shift from one band to another could be arranged without alteration of the instrument itself, being accomplished by a simple change in the bubble-tube lengths, as described later. Accordingly, a recording type instrument was purchased and installed. Because there were some advantages in doing so, the first installation attempted to measure the gravity of the cone proper by placing the bubble tubes in the cone. This was not at all satisfactory and the second scheme utilized a fixed vertical screen at the surface of the cone, and an external sample-tube arrangement. We were particularly anxious to make this work as we felt it would be advantageous to measure the top level of medium where the separation was actually being made, but we were doomed to disappointment because it was impossible to keep the screen clean of float. Since the top gravity of the cone is the most convenient place to sample for control, a launder about 2 in. wide was installed longitudinally beneath the

Jan 1, 1951

From the beginning to the end, the attendance and enthusiasm of the 119th meeting, which was held in New York, Feb. 17 to 20 surpassed all expectations. Besides the ten technical sessions, one of which was in conjunction with the American Institute of Electrical Engineering and one a session of the National Research Council, there were two memorial meetings, one for Dr. Raymond and one for the members who died in service; two joint sessions with the Canadian Mining Institute; and a meeting devoted to pictures of copper mining, milling, and smelting. Of the 732 persons registered, 119 registered in the Institute of Metals Division. Monday's sessions were devoted to the problems of industrial organization, the Institute of Metals Division, and to petroleum and gas. Among the special features of these sessions were the topical discussions on housing and. Americanization. Americanization, too, was the topic for discussion by the Woman's Auxiliary Wednesday morning. On Tuesday, nearly 100-members of the Canadian Mining Institute were present to discuss the possibility of bringing about uniform mining laws for the United States, Canada, and Mexico, to obviate the maintaining separate legal departments and managerial forces for the several countries; and to avoid the confusion which, it is said, has led to a duplication of effort and has sometimes created a barrier to international cooperation in mining. Among the Canadian delegation were D. B.

Jan 3, 1919

By Alexander Anderson

In many oil fields a great variation in the production of adjoining wells has long been observed, and a certain proportion of dry holes, situated between prolific producers, has been regarded as normal without thorough investigation as to cause. Similarly, an occasional prolific producer has been found in a part of a field where all other holes have proven disappointing. Adjoining wells which showed an unreasonable difference in production have been surveyed, and the bottom of the poorest producer has been found to have lost sufficient vertical depth, through its drift, to diminish seriously its penetration in the oil zone. Again, the bottom of the good producer has been found to he more favorably situated by its migration up structure. Surveying of wells in California fields has shown many instances where the dry hole has drifted far off the structure to such a degree that no amount of deepening could ever convert it into an oil well. In other cases, edge wells have been found to drift into the field. At this time, in California, the surveying of oil wells is beginning to he accepted as a routine part of operating procedure. Some operators are surveying all of their new wells and, in some of the recently discovered fields, this practice is providing invaluable assistance in methodical development. The information that has been obtained from the surveying of many wells has convinced most operators that it pays to give careful attention to the drilling of wells. Chews are now usually cautioned to avoid reckless competition with each other. Whereas, formerly, certain companies demanded a large footage from their drillers, they now issue orders that a very moderate speed in drilling shall he maintained and that every care be taken to avoid practices likely to cause excessive deviation of the hole frorn vertical. As a result of these new instructions to drilling crews, a distinct decline in the average drift of the wells drilled by these operators has taken place and fewer dry holes are being drilled from good locations. To the petroleum engineer and the geologist, oil-well surveys provide the necessary data required for the construction of the correct cross-

Jan 1, 1929

By H. Engelmann

THE very extensive development of a brown coal formation, in the region of the Rocky Mountains, is well known to all of you. The existence of these coals was known years ago, but they were of no practical importance until within a few years, when the mineral wealth of that country began to be developed and railroads were built. As their qualities became better known, their adaptability to domestic manufacturing and metallurgical purposes was more appreciated. They are still much undervalued, although they are mined at some points on a very extensive scale. A large portion of this coal formation is of cretaceous age, while it appears to extend into the tertiary epoch; but whatever difference there may be in the ages of these coals of different localities, they all have some common characteristics which distinguish them from our Eastern stone coals of the

Jan 1, 1876

By Howard N. Eavenson

From the Pittsburgh coal bed in the four states of Pennsylvania, Ohio, Maryland and West Virginia has been produced an output that, at mine prices, represents a greater value than any other single mineral deposit in the world has yielded.12 While this distinction may in a few years pass to the gold reef of the Witwatersrand, it is possible that eventually, owing to the tremendous reserves still remaining, the ultimate yield of the Pittsburgh bed will be greater than that of any other known single deposit. Considering its importance, not a great deal has been written of its early history and development as a whole; most of the accounts have been of limited localities, or, at the most, of the area within a single state. In "Coal through the Ages" the writer mentioned some references to its early history, but this study will deal not only with its history but with the character of the bed, where and why it was first developed, and its effect upon the states in which it is found. It has not been the intention to write a detailed history of the development of the seam in each locality, as neither time nor inclination were available for doing such work, but only to show the influences that tended to hasten or retard such development. In general the historical matter ends about 1830, when geological surveys began to be made. Some of the maps show data available only since that time, and the sections about coal preparation and coking have been extended to the present time to show the changing conditions. It is believed that the early history includes all published records, and many more sources than those shown in the bibliography were consulted. It is quite likely that some references to coal in this area may be found in the unpublished papers of some of our early soldiers and colonizers, which exist in several libraries, and it is hoped that some future * Dedicated to Dr. Thomas S. Baker, President Emeritus, Carnegie Institute of Technology, whose labors in promoting the International Coal Conferences and in establishing the Coal Research Laboratory have done much in showing the industry how science can be of help to it. Manuscript received at the office of the Institute Feb. 15, 1938.

Jan 1, 1938

By Howard N. Eavenson

From the Pittsburgh coal bed in the four states of Pennsylvania, Ohio, Maryland and West Virginia has been produced an output that, at mine prices, represents a greater value than any other single mineral deposit in the world has yielded.12 While this distinction may in a few years pass to the gold reef of the Witwatersrand, it is possible that eventually, owing to the tremendous reserves still remaining, the ultimate yield of the Pittsburgh bed will be greater than that of any other known single deposit. Considering its importance, not a great deal has been written of its early history and development as a whole; most of the accounts have been of limited localities, or, at the most, of the area within a single state. In "Coal through the Ages" the writer mentioned some references to its early history, but this study will deal not only with its history but with the character of the bed, where and why it was first developed, and its effect upon the states in which it is found. It has not been the intention to write a detailed history of the development of the seam in each locality, as neither time nor inclination were available for doing such work, but only to show the influences that tended to hasten or retard such development. In general the historical matter ends about 1830, when geological surveys began to be made. Some of the maps show data available only since that time, and the sections about coal preparation and coking have been extended to the present time to show the changing conditions. It is believed that the early history includes all published records, and many more sources than those shown in the bibliography were consulted. It is quite likely that some references to coal in this area may be found in the unpublished papers of some of our early soldiers and colonizers, which exist in several libraries, and it is hoped that some future * Dedicated to Dr. Thomas S. Baker, President Emeritus, Carnegie Institute of Technology, whose labors in promoting the International Coal Conferences and in establishing the Coal Research Laboratory have done much in showing the industry how science can be of help to it. Manuscript received at the office of the Institute Feb. 15, 1938.

Jan 1, 1938

Discussion of the paper Of ROBERT H. BEDFORD and WILLIAM HAGUE, presented at the Salt Lake meeting, August, 1914, and printed in Bulletin No. 92, August, 1914, pp. 1807 to 1816. W. L. SAUNDERS, New York, N. Y. (communication to the Secretary *) . -Messrs. Bedford and Hague have given us a very interesting and practical paper. No better excuse for such a paper could be desired than the statement made that the expense of drilling. in this mine is one-third of the cost of delivering the ore at the mill. This statement. should be written in red letters, because it applies to a great many mines besides the one referred to and because it is generally true that in a mining plant, as also in papers read before the Institute, more attention by fat is given to the metallurgical side of mining than to the excavation of the ore, and no study of the excavation work is properly made that does not involve a careful inquiry into the merits of the rock drill used. Next in importance to the selection of a good rock drill, in a case where the actual drilling cost is one-third the cost of delivering the ore, is that. the drill should be maintained in order and kept up to its highest efficiency. The best rock chill may run down in efficiency through accidents, wear, or other conditions which are sometimes beyond supervision or control. The machine is usually in the hands of men who know how to get workout of it, not men who know how it works. The best drill runners are not machinists,. but miners. They could not tell you how the valve operates or the principle of the rotation, but they know how to get the work done. A testing machine, particularly the type described in this paper, may he of the greatest value in maintaining a uniform state of efficiency.

Jan 11, 1914

By J. M. Callow

THe results obtained by pneumatic flotation throughout the country on all classes of ore, and the tonnage now being treated by this particular method, speak for themselves. Its advantages over the so-called agitation process are now established by facts and data from practicc. The comparative efficiency of a rapidly revolving paddle, as a means for aerating an ore pulp, and of a cyeloidal or turbine blower for the same purpose, would seem to be so obvious as to leave no room for discussion. Practitioners in this art are to be congratulated on the acquisition of the valuable literary contributions that have recently been made on the theory of flotation by Messrs. Ralston, Van Arsdale, Taggart and Beach, and others, and the very valuable and able articles by Messrs. Laist and Wiggin on "Flotation Concentration at Anaconda, Mont.," by Dr. Rudolf Gahl on the "History of Flotation at Inspiration," and by David Cole on "The Advent of Flotation in the Morenci District." It is not within the province of this article to attempt an answer to the various issues raised in regard to the theory, or to defend the one advanced by me a year ago. But since discussion usually benefits the profession, a reply will be made to some of the statements made by the last-named writers. CoMPABATIVE SENSITIVENESS AND ATTENDANCE Concerning the article, "Flotation Concentration at Anaconda, Mont.," by Laist and Wiggin, a little explanation is in order. It should be stated that, with the exception of about 24 days at the end of the testing period, the Callow experimental plant at Anaconda was not run under my direction. This perhaps accounts for some of the concIusions drawn on page 499 of the descriptive paper. The conclusion that the use of acid seems to be of considerable advantage, calls for some comment. While the tests conducted by the Anaconda Copper Co. do show acid to be of considerable benefit, this is a consequence of using acid sludge as a flotation agent. My belief has always been that the Anaconda

Jan 1, 1917

By S. B. Sargent, V. J. Collins, Lester C. Uren

[The conclusions arrived at by authors in paper read before the Petroleum Division and the California Sections of the Americam Institute of Mining and MetallurgicaI Engineers and the Standardization Division of the American Petroleum Tnstitute, at a joint session held at Los Angeles, Cal., Jan. 21, 1926, are presented below.] From the theoretical discussion and experimental evidence presented in this paper, the following conclusions may be drawn: 1. The efficiency of the oil-well plunger pump is dependent to an important degree upon the submergence provided. 2. Ample submergence must be secured in order to provide sufficient static pressure to force the oil through the restrictions interposed in the oil path at the standing valve and at the plunger nut surrounding the garbutt rod. These restrictions should be no smaller than is structurally necessary, in order to reduce resistance to oil flow to a minimum. 3. A part of the static pressure developed below the standing valve by submerging the pump is dissipated in overcoming the inertia and in providing upward acceleration for oil left between the pump valves at the conclusion of the down-stroke of the plunger, and of oil below the standing valve in the gas anchor above the oil inlet. This loss in effective static pressure can be reduced to a minimum by dispensing with the garbutt rod and placing the working valve at the lower end of the plunger. The valves should be as near together at the conclusion of the down-stroke of the plunger as is consistent with security in avoiding striking of the lower end of the plunger on the standing-valve crown. Gas anchors should be short, and oil inlets should be as near the standing valve as is consistent with proper gas exclusion. 4. Because of the presence of gas in solution in the oil, which tends to escape from solution under the reduced pressure conditions above the standing valve, the effective length of stroke of the plunger is reduced, and the suction effect of the rising plunger is largely nullified. The influx of oil through the standing valve is therefore chiefly dependent on static pressure developed by submergence.

Jan 1, 1927

By J. Paone, S. Tandanand

This paper studies the behavior of rock at the initial state of crater formation resulting from stresses created under a drill bit. The purpose of this study is to determine which mechanical properties of rock are important in rock fragmentation by drilling. Although a definite relation between the drilling strength and relevant mechanical properties has not been established, maximum yield strength or hardness of rock is apparently a parameter of drillability of rock. The strengths of rock were considered from the Mohr-Coulomb criterion from which the surface of failure was constructed. The results from previous triaxial tests on Solenhofen limestone were adopted in establishing a limit of failure. Inelastic behavior of Solenhofen limestone was observed under a low velocity impact of a hemispherical bit and under static indentation with a similar bit. Permanent set at low applied loads in the indented area was measured with an interferometric technique. A quantitative determination of strengths of the rock was made under static indentation. The maximum yield strength estimated from the average stress over the contact area for plastic deformation was used as the crushing strength of rock under a drill bit. Much research has been done on energy requirements and mechanisms of energy dissipation to perfect rock fragmentation by a drilling process. But more needs to be done. More needs to be known about the mechanisms of energy dissipation or failure criteria of rocks in the drilling process in order to evaluate the efficiency of energy requirements in specific rock fragmentation. This paper examines some published studies on rock failure and energy dissipation and presents some findings in that phase of research concerned with rock fragmentation by drilling. This work is specifically concerned with rock behavior at an early stage of failure induced by a concentrated load. Consideration is limited to the primary phase of the crater formation under drill bit, i.e., before chipping takes place. Failure Phenomena of Rocks: Failure of rocks can be classified into two types, fracture and plastic flow. Both involve separation of material to form new surfaces with complete or partial loss of cohesion. Fracture is further classified as extension (or cleavage) fracture and shear fracture. Extension fracture involves separation in a plane without shear stress component, while shear fracture involves slippage along a plane as a result of combined stresses. Then, shear fracture inclines to the axes of the principal stresses. Plastic flow occurs under combined stresses, especially at high confining pressure and temperature, and denotes macroscopically irrecoverable deformation of rocks. Flow mechanisms have been classified as in-tergranular failure, intragranular gliding, and re-crystallization of mineral constituents.6 Failure phenomena in rocks are complicated because they include fractures and plastic flow as well as a friction process developed intrinsically as the internal stresses increase. All can occur in one rupture process, depending on the varying stress conditions. Both fracture and plastic flow are encountered in rock drilling. Rock failure under a drill bit as observed in drop tests simulating a single blow of a percussion drill, consists of two types, crushing and chipping. Crushing is considered as a separation of material particles by many fractures resulting from the application of high compressive stresses exceeding the strength of rock at the contact area. Chipping results from subsurface fractures extended to the face surface; this phase is preceded by crushing or surface deformation. The state of stress under the drill bit and the strength of rock create and control these two types of failure. The state of stress under the bit and in the vicinity of the contact area depend on the bit configuration and the magnitude of applied force. The strength of rock, characterized by its ability to resist penetration, depends on its composition and structure. However, the term "strength" quantitatively defined, is still ambiguous and may or may not correspond to the tensile, compressive and shear strength obtained from simple tests. Rock Failure Criterion: Rocks are weak in tension, their tensile strength being many times less than their compressive strength. This characteristic excludes

Jan 1, 1967

By C. S. Westerberg, C. P. Heiner

Observation of the clinkering action of coal from the Castle Gate D seam in underfeed stokers over a period of years has given rise to the present investigation of the effect of bony coal on clinkering. Some very costly examples of slagging clinkers in particular cases have been of especial interest to the authors. In such cases coal analyses and ash-softening and fluid temperatures have been found of little value. In general, it was noted that slagging mas accompanied by a somewhat higher ash content of the stoker slack, and the suspicion naturally arose that foreign matter was the troublemaker. One would naturally suspect bony coal and rock impurities because of their occurrence and prevalence within the seam and the relative absence of sulphur or other impurities in the coal mined. The test results given herein indicate that the concentration of the bony coal and rock impurities in the coal determines the clinkering tendencies of the ash during combustion. Castle Gate D Seam Extending from the Utah-Colorado line near Grand Junction, Colo., westward to Greenriver, Utah, and thence in semicircular form north and westward to Castle Gate, and from there southward to Mt. Hilgard in central Utah, is a line of nearly perpendicular cliffs, composed of interbedded massive sandstone and shales, making up the coal-bearing horizon of the Mesaverde formation of Upper Cretaceous age. The cliffs face roughly concentrically toward the south and southeast and the strata, with conformably enclosed coal beds, gently dip away from the face of the cliffs and at right angles to their front line. Back of these cliffs the mountain masses rise to an altitude of from 8000 to 10,ooo ft. above sea level. Stretching away from their foot is a great shale plain, on which the towns are situated and over which the railroad lines and highways run. The Castle Gate mines enter the coal beds at their outcrop; the workings extending within a particular coal bed away from the outcrop and under the mountain mass back from the cliff line (Fig. I). Throughout the Mesaverde formation in the Castle Gate general area, there are from two to five workable coal beds. Usually not all of these are coincidentally of workable size and merchantable quality throughout any given large tract. In the Castle Gate mine area, the base of the Mesaverde horizon and coal measures is marked by a massive, cliffmaking, gray sandstone bed 60 to 80 ft. thick. Locally this is referred to as the "Castle Gate sandstone floor." Frank R. Clark, in U. S. Geol. Survey Bull. 793, designates it as the "Aberdeen sandstone." At Castle Gate the various coal beds are designated by the letters A, B, C, etc., commencing with the lowest bed.

Jan 1, 1942