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By David H. Browne, John F. Thompson

The literature dealing with the physical constants of nickel is so fragmentary and unrelated that a synopsis presents unusual difficulties. It is only within the last few years that investigators have understood the importance of placing on record not only the determinations they have made but also the composition, physical treatment, and past history of the material investigated. For this reason much of the earlier literature is valueless. Determinations have been made of the same physical constants on samples differing widely in origin, composition, and treatment, and the results differ widely among themselves. In the first place nickel is almost as flexible a term as steel. Its physical properties are widely influenced by its composition and treatment. It absorbs large quantities of gases and is exceedingly difficult to prepare in a state of chemical purity comparable to gold, silver, or copper. It is vitally affected by thermal and mechanical treatment. Hence in the following pages the recorded literature, where quoted, must be accepted with a certain reserve and used, as far as possible, as a check on later observations, in which these important factors are noted. In every case where new determinations are given, an attempt has been made to record all available information concerning the composition and treatment of the material used so that the data may serve as stepping-stones toward a wider knowledge of the properties of the metal. As this synopsis is an attempt by men of metallurgical training to do what should long before have been done by physicists, it is to be expected that certain errors may have crept in. Any corrections or suggestions

Jan 1, 1921

By John W. Cloud

In 1877 the Pennsylvania Railroad Company removed an old bridge from its line at Duncannon, Pa., built intermediate piers and erected shorter spans of the Pratt truss type, which had previously been in use on another portion of the road. The design of this truss would not admit of diagonals larger than 19 inches diameter, and in order to stiffen the bridge somewhat steel rods were introduced for the main diagonals in the first and second panels, 19 inches and 18/8 inches diameter respectively. These rods were threaded without upsetting, and by the ordinary formulae the strains were of the same intensity upon both, viz., 16,000 pounds per square inch with the maximum loading. The other main diagonals in the truss are 19 inches diameter, and of iron. It was specified for the steel rods: Elastic limit,.......46,000 Ibs. Tensile strength,. .. ,. .. 80,000 lbs. Elongation,,.,.,. 20 per cent. The steel was procured without difficulty, and it allowed a factor of safety of 23/4 at elastic limit, while a similar factor of 2½ had for a long time been successfully used for iron. In the course of three years, from time to time, six of these steel rods broke, three of them being 18 inches in diameter, and three 19 inches in diameter. The broken rods were tested, and three of them analyzed at Altoona to ascertain the cause of failure, and what modifications should be made in the steel for such service. Examination showed that all the rods were broken in detail close under the nut. The threads were well cut and properly rounded at the root. testing the rods micrometer screws, reading to .0001" with c bell to signal the contact, were attached to the test pieces, and by this means the modulus of elasticity and elastic limit accurately obtained.

Jan 1, 1881

By William P. Shinn

Jan 1, 1881

By T. Sterry Hunt

In my address on the " Geognostical Relations of the Metals," delivered before the Institute on the 20th of February last (Vol. I Transactions, p. 331), I spoke of the rocks in the vicinity of Thunder Bay, Lake Superior, where I indicated two series of uncrystalline rocks resting upon the Huronian schists, the lower one consisting of dark-colored argillites and sandstones overlaid, apparently in slight discordance, by nearly horizontal red and white sandstone and marls, which were compared with those of Sault Ste. Marie, and those of the Portage Lake district, on the south shore. These latter sandstones, according to Brooks and Pumpelly, overlie uncomformably the Keweenaw series of copper-bearing amygdaloids, sandstones, and conglomerates, and are in turn overlaid by the Trenton limestone. I then proposed to call this lower series of Thunder Bay, that is to say, the dark-colored argillites and sandstones which are traversed by the silver-bearing lodes of that region, the Animikie group. Shortly after the publication of that address I received an abstract of a paper on the geology of that region by Professor Robert Bell, read before the Montreal Natural History Society, February 24th. He there confirms the statement made in my address that the gold of Lake Shebandowan occurs in the Huronian, which is also seen to be cut by the silver-bearing lodes just mentioned. Professor Bell, in this paper, proposes to designate both what I have called the Animikie group, and the overlying red and white sandstones, by the name of the Nepigon group, for the reason that the upper series is best displayed about Lake Nepigon. This latter series is by Logan supposed to be overlaid by the copper-bearing amygdaloids with conglomerates and sandstones of the north shore (apparently identical with those of Keweenaw); and the whole together, inclnding the Animikie group, constitute his Upper Copper-bearing group. These copper-bearing strata are by him supposed to be overlaid by the red and white sandstones of St. Mary, which are apparently the same with those sandstones which, according to Brooks and Pumpelly, overlie unconformably the similar cupriferous rocks of Portage Lake, and are, in their turn, overlaid by the Trenton limestone. Thus the sandstones which at Thunder Cape overlie the Animikie group are by Logan placed in the midst of the Upper Copper-bear-

By Thomas M. Drown

Remarkable as have been the direct results of Danks's puddler, there are some indirect and incidental results, which are well worthy of study for their intrinsic value and suggestiveness. The success of Danks's machine is due mainly to the nature of the lining and the manner in which it is attached to the walls of the revolving chamber. Herein lies Danks's merit and good fortune. Given such a lining, and the success of the machine, as far as puddling iron is concerned, could easily be predicted. Other important results have, however, been obtained with this machine, which, though clearly explicable, were, nevertheless, unanticipated. These are the increased yield of bar-iron over the pig-iron charged, and the elimination of phosphorus, which, though not absolutely complete, is yet more decided than in the case of hand-puddling. As regards the increased yield, this is merely what we have a right to expect if we consider the puddling process to consist in the oxida tion of the carbon and silicon of the pig by the oxygen of the oxide of iron. That this result is attained, nearly to the extent that the theory requires, in Danks's puddler, and has never been more than partially attained by the most careful experiments in band-puddling, points clearly to the fact that the contact of the molten pig-iron with the oxide of iron is much more intimate and complete in the one instance than in the other. The action of puddling in Danks's machine may be considered to be twofold: first, the removal of the carbon, silicon, and phospho rus of the pig, which is the primary object, and, second, the produc tion of wrought iron direct from the ore, which is entirely an inci dental result. Intelligent metallurgists were not long in recognizing in this latter result a fact of deeper import and greater value than the attainment of a perfect puddling process. A new method

By A. L. Holley

The first session was held in the rooms of the American Philosophical Society, on Tuesday evening, February 26th. The President, Dr. T. Sterry Hunt, called the meeting to order, and after a few introductory remarks concerning the importance of theoretical and speculative science, which often involves principles of the highest economic value, and, more than all that, serves to enlarge our conceptions of the universe, and ennoble us, by the cultivation which it affords to our most exalted faculties, proceeded to discuss some points in the chemistry of the atmosphere. It is known that there is in the crust of the earth a great amount of oxidized carbon, not only in the shape of coal, but also in the graphite or plunlbago of the crystalline rocks, in the various bituminous shales or pyroschists, which are found in all succeeding rock-formations, and also in the forms of bitumen and petroleum. All the analogies of nature lead us to conclude that these various carbonaceous substances have had an organic origin, and have been generated by the deoxidation of carbonic acid, a process effected by the growing plant, and attended with the liberation of oxygen. He showed that the carbon of a layer of coal covering the whole earth's surface to the thickness of one meter, would, in its production from carbonic dioxide, liberate an amount of oxygen equal to that now present in our atmosphere. But bituminous coal contains also a large amount of hydrogen, derived from the deoxidation of water, which implies the liberation of a farther portion of oxygen. The amount from this latter source would equal, for the various coals and asphalts, from one-eighth to one-fourth, and, for the petroleums, onehalf of that set free in the deoxidation of the carbon which these hydrocarbonaceous bodies contain. From what we know of the composition of the stratified rocks, it is probable that they include an amount of deoxidized carbon and hydrogen many times greater than that contained in a layer of coal one meter in thickness, and, consequently, that the disengaged oxygen in past ages must have far exceeded that now present in our atmosphere. To this must be added

Jan 1, 1879

By Hon. Abrams S. Hewitt

Gentlemen : If my first words were other than those of thanks for the high honor of being called to preside over the American Institute of Mining Engineers, I should do injustice alike to you and to my own sense of the obligation, under which I have been placed by your voluntary choice. When the position was first suggested to me, I resolutely declined to allow the use of my name, on the ground that, by training and occopation, I was not entitled to this honor, which, it then seemed to me, should be conferred only on a professional engineer. In fact, the history of the Institute, which had honored itself, as well as my distinguished predecessors, David Thomas, Rossiter W. Raymond, and Alexander L. Holley, by elevating then] to its highest office, seemed to indicate the line and the limit of safe precedent, in which I did not then see how I could be included. But my scruples were finally removed by the consideration that, as in the course of human industry, the pioneer, of whom Mr. Thomas was so marked a type, must precede the mining engineer, so fitly personified in Dr. Raymond, and be followed by the mechanical engineer, whose incarnation we behold in Mr. Holley; so all these must be supplemented by the man of affairs and finance, in order that "enterprises of great pith and moment" may be prosecuted to a successful issue. I felt, therefore, that I had no longer any right to resist your preference, or to deprive myself of what I must regard as the crowning honor of an active career. On an occasion like the present it seems appropriate to review the history in this country, during the last hundred years, of those industries which the Institute of Mining Engineers specially represents. There is much in the story with which other members of this body are more familiarly acquainted than myself; yet I fancy that to all of them, and not less to our distinguished and most heartily welcome gnests from abroad, a comprehensive outline of the progress of mining and metallurgy in the United States mill prove interesting. I ask your attention, therefore, to a condensed account of that subject, embracing a statement of the beginnings of the industry on our shores, of the notable events attending its increase, and of its present

By Robert W. Hunt

The memorable features of American history have been making fast during the last century, and notably so since 1860; and they are by no means confined to political or to any one branch of scientific development. Of all the industrial arts, none show a greater change or 'a mightier progress than the Bessemer manufacture. And this year, while we are celebrating the first centennial of our national life, we can also celebrate the first decennial of American Bessemer practice. While not forgetting or undervaluing what has been done in other countries, I have thought that a brief history of the introduction and development of the Pneumatic or Bessemer process in America would be of interest. In 1863 the Kelly Pneumatic Process Company was formed and an arrangement entered into with William Kelly, who had taken out letters-patent of the United States, Nos. 16,444; 17,628, reissued as 505; 18,910, dated January loth, 1857; June 23d, 1857; November 36, 1857; and December 22d, 1867, respectively. This association mas composed of the Cambria Iron Company, E. B. Ward, Park Brothers & Co., Lyon, Shorb & Co., Z. S. Durfee, and, later, Chouteau, Harrison & Valle joined the combination. Not satisfied with possessing the control of the Kelly patent, they sent Mr. 2. S. Durfee to England, to secure for this country Mushet's patent on recarburization, No. 17,389, dated May 26th, 1857, the same having been taken out in England on September 22d, 1856. In this Mr. Durfee was successful. Previous to the application of William Kelly for a patent, Henry Bessemer, of England, had taken out patents dated February 12th, 1856, and August 25th, 1856, in this country. Kelly claimed priority in the discovery of the principles of the process, and the Patent-office allowed his claim by granting him his patents. In the autumn of 1862 Mr. Alexander L. Holley, while in England, was impressed with the importance of Mr. Bessemer's invention, and so fully foresaw its future, that, upon his return to the United States, he induced Messrs. John A. Griswold and John F. Winslow, of Troy, New York, to join him in endeavoring to possess Bessemer's American patents. Mr. Holley returned to England in

By Lewis A. Riley

I desire to submit, for the consideration and information of the members of the Institute, the following data, drawings, and tables, showing what I believe will be interesting information with regard to the diamond drill, and its uses in developing mineral lands. I would first say that the results given have been obtained during the past two years by means of two drilling machines belonging to the Lehigh Valley Coal Company, operating on their coal lands in the Mahanoy, Lehigh, and Wyoming regions. 1st. A tabulated statement, giving location of borings, date, progress, total cost, itemized cost per foot, etc. 2d. Section showing strata bored in Nos. 5 and 10 holes at Mt. Carmel, see Plate VI. 3d. Section showing strata bored in No. 19 hole at Hazleton, see Plate VI. 4th. Photograph and description of drill No. 2. From the first it will be seen that the total number of test-holes bored up to May 1st of this year is 24; 9 of these are in the Mahanoy region, 6 in the Lehigh region, and 10 in the Wyoming region, in all of which cores have been taken for the whole distance. The total distance bored is 9902 feet. The majority of the holes have been put down for the purpose of proving the lower veins of the coal series, and have had to encounter the harder rocks of the coal formation. Much of the distance has been through the lower conglomerates, going in some cases through the coarse egg conglomerate, the foundation of the coal deposit, and to the green sandstone and red shale which underlie it. These lower sandrocks and conglomerates are among the hardest known to geologists, and present a formidable resistance to the exploring drill. This fact must be taken into consideratiotl in comparisons of cost of drilling, and when considered will still further improve the very favorable results I am able to show in my statement of costs. In illustration, I will cite the work of one bit when boring in the upper or softer rocks of the Wyoming region, where 280 feet were obtained without resetting, while in the Lehigh and Mahanoy regions, in the lower and harder rocks, bits set with the same quality of diamonds would only bore from 3 to 20 feet before being worn out. In this connection it may

By W. E. Coxe

In 1857 the Philadelphia and Reading Railroad Company, whose main line extended from Philadelphia to Pottsville, Pennsylvania, with branches into the coal regions of Schuylliill County, made a contract with the Fairmount Rolling Mill, at Philadelphia, for the rerolling of some four thousand tons of iron rails. The essential features of the agreement were that the old rails should be piled with puddled iron and rolled into flats for the rail pile, which latter was • to be of a section seven inches square, and after being heated, and reduced, by rolling, to a bloom of a section about fire inches by six inches, was to be reheated, before being finished into the rail of the T pattern, four inches high, weighing sixty-four pounds per yard. Great care was exercised in the execution of this contract, and the rails being distributed over all parts of the road, gave general satisfaction by their excellent wear. Five years afterward, the principal proprietor and manager of the Fairmount Rolling Mill was elected President of the Reading Railroad, and very many of the rails made under his supervision were still in use in the tracks of the company, of which he had just assumed the management. His first efforts were, therefore, directed to the procuring of more rails of the same quality wherewith to replace those worn out. Here he encountered some trouble, makers refusing to bid because of the details in the specification, the required reheating being the objectionable feature, for which it was generally intimated they would not be sufficiently remunerated for the increased labor, extra coal consumed, and the changes necessary from the established methods of working. Most of the new rails were, therefore, bought, and the old rails rerolled without regard to any particulars as to the manner of piling, heating, etc., each manufacturer furnishing what he deemed the best article possible for the money. As a consequence, rails of all imaginable grades were placed in the tracks, some giving out in six

By Adolph Henry

The manufacture of wheels of metal for locomotives and cars constitutes an important branch of the iron industry, and one closely related, moreover, to many of the conditions of railway practice, such as speed, safety of passengers, and economy of working. It has been, also, since the introduction of iron roads, a subject of constant study on the part both of engineers of construction and iron manufacturers. The car-wheels at first used in Europe had spokes of wrought iron and a hub of cast iron. Subsequently endeavors were made to make the wheels entirely of wrought iron, by forging successively the different parts which constituted the hub, spokes, and rim. By this treatment the expansion of the heated portions at the last forgings gave rise to interior ruptures in the already cold and finished parts. The metal was thus strained before use, and the wheels broke frequently in service. It was in consequence of these failures, doubtless, that the engineers of this country were led to employ exclusively wheels of cast iron. The railway companies are nevertheless greatly interested in the reduction of the weight of rolling stock, while preserving abundant, strength, and by the employment of wroughtiron wheels one may attain this double end if the defects of manufacture which we have just mentioned are avoided. This may be accomplished by making the wheels in such a manner that the different parts are welded at the same time, whereby the interior strains which so frequently give rise to ruptures in wheels successively forged are avoided. This result has been attained by what is known in France as the Arbel process, of which I will give you a short description if you will kindly give me a few minutes' attention. The process may be briefly summed up as follows: A pile of puddled bars of the general form of the wheel to be made is prepared,

By Charles Himrod

In presenting this paper it is not intended to enter into any discussion of the theory of the blast-furnace, but simply to give the results of a number of determinations of CO and CO 2 in furnace gases, and some conclusions arrived at, and the result of an experiment made in hopes of increasing the production of CO 2. In the first table, on page 198, is given the averages of a number of analyses of gases of different furnaces, and in the second, of two stacks of different sizes under varying circumstances. The conclusions arrived at as to what influences the production of CO2 are as follows: lst,. Kind of fuel. Bituminous coal not permitting the formation of as much CO, as coke. 2d. Kind of ores. Rolling-mill cinder being much less favorable to formation of CO2 than hematite ores, magnetites probably less than hematites, but more than cinder. 3d. Length of time of contact of gases with ore. Small furnaces and too rapid driving both waste fuel by riot allowing enough time for conversion of CO into CO2. 4th. The temperature of blast. The hotter the greater the quantity of CO2. 5th. Regularity of passage of stock through the furnace. The hanging and dropping of the stock, however slight, seems to pack it more solidly in the hearth, increases the resistance to the blast, and decreases the quantity of CO2. These are the most common causes noticed which influence the production of CO2, unless we except the one that might be considered the greatest of all, the one that has spoiled so many tons of iron, and the amiability of so many furnacemen, the one most dreaded, the great unknown. It would seem a self-evident proposition that the better the contact of the gases with the ore and the less with the fuel, the greater would be the amount of CO2 produced. To prolong the contact of gas with the ore furnaces are enlarged with advantage, and pains are taken to charge the stock in such a manner as will best promote it. Still, with furnaces of most approved construction and most skilful manipulation, the gases leave the furnace so rich in CO, that not half the heating power of the fuel is obtained, and the highest

By Richard P. Rothwell

Though coal has been mined in this country for more than a century, no systematic effort was ever successfully made to ascertain the total amount produced. The production of the Cumberland Basin, Md., and the shipments from the anthracite fields of Pennsylvania, have been placed upon record, thanks to the intelligence and foresight of Mr. C. Slack in the former case, and to the late Mr. B. Bannan in the latter. For some of the years between 1822 and 1842, the production of the Richmond Basin was reported by Mr. R. C. Taylor, but since that date till the author undertook this work it was impossible to obtain any statement of the production of this field. A few of the newer fields, such as that of Mt. Diablo, Cal., have been fully reported, and a few of the newer States have also had this service performed by some intelligent private individuals; but no statistics of coal production have ever been collected either by the State or General Government, if we except the returns for the years 1869—70 of the census report. During the year 1875, by great exertions, I succeeded in obtaining, and July 3d, 1875, gave in the Engineering and Mining Journal what, " though not an accurate statement of our coal production," was " by far the most full and reliable that had ever been published." Though that report showed the production of bituminous coal to be 23,630,094 gross tons, or about six million tons more than had ever before been reported, it was in reality two and a half million tons below the actual output. The more full returns I obtained for 1875 gave many figures for 1874

By W. J. Taylor

It is, perhaps, more important to put on record the particulars of experiments that are derided failures than those that are successful, as those of the latter class are certain to live, while the former may be lost sight of in a short time, and repeated by others. TO this end, I propose to give the particulars of a straight or no-bosh furnace just tried at the Chester (New Jersey) works, which was such a decided failure as to leave no doubt of the plan being wrong, and determining the necessity of a bosh of some kind, as of old. Some experiences during the past year led me to suppose that the bosh or belly of a furnace was unnecessary, and that the contraction of the walls toward the bottom for the stock to wedge in, in its descent, facilitated dirty walls and scaffolding; hence, irregularity and high fuel. I concluded, however, that a very shallow bosh for a skew-back support to the stock would be necessary, and that the proper place for this was in the tuyere-section, beginning just below the tuyeres and ending just above them, where there is nothing in the solid state but fuel, which is consuming, and no slipping or travel of stock takes place. The cubical capacity of a furnace of this design would necessarily be much less than in the old style, unless it was made very much higher. But I assumed that the loss of room for reduction could be overcome by making the size of the ore and stone charged much smaller, so that the gases would act more quickly. The next point was, what should be the size of the shaft, crucible, tuyere-circle, and tunnel-head for a given quantity of air? My first design was 12 feet diameter of shaft for 7000 feet of air, with a 9-foot crucible and 8-foot toyere-circle. This I soon reduced to 8-foot shaft diameter, which I concluded was large enongh for economical work, if regular travel of the stock on the walls could be maintained. I consulted with a number of experienced furnacemen and furnace-engineers, and the plan was well thought of by many of them; and, as I had also some offers of financial aid from them toward the risk of trying the experiment, my firm concluded

Jan 1, 1885

By Anievas JB, Sevillano AC

This paper describes the acquisition, exploration, development, initial operation and subsequent financing of the Bulawan mine by means of a listing on the Toronto Stock Exchange of a subsidiary of the parent company, Philex Mining Corporation.Located on the island of Negros in the Philippines the property is unique on at least two counts: it is a disseminated gold deposit that occurs in a region of predominantly porphyry copper mineralisation; and it is a gold deposit that is mined by a bulk method of extraction (front and block cave) instead of the normal selective mining methods.

Jan 1, 1997

By J. B. Dilworth

OUTCROPS of coal have bees discovered is many localities is the Philippine archipelago, and practically all of the larger islands contain deposits of this mineral. Very little prospecting has been done to determine the value of the various coal-bearing areas, but so far as known, the largest and most promising fields are found : (1) is northern Cebu; (2) is the small island of Batan, a part of the province of Albay is southeasten Luzon; (3) is the somewhat larger island of Polillo, off the east coast of Luzon, and (4) is southern Mindoro, sear the small coast tows of Bulalacao. Northern Panay, south-central Cebu, and various localities is southern Luzon, Masbate, Negros, and Mindanao also afford evidences of the existence of coal-beds, the extent and value of which have not yet bees proved. The general position of these islands and districts is shows on the map of a portion of the Philippine Islands, Fig. 1. Some of these coal-fields have been known for many years (coal was discovered is Cebu 1827 and is Batas is 1842),1 and several futile attempts were made by the Spaniards to operate mines is these districts. But owing to many circumstances, chief among which were indifferent management, the political unrest of the islands, natural difficulties of transportation, and those inherent in the mining of steeply-inclined and somewhat irregular seams, no considerable output was ever obtained from any of these mines, and the fuel required is the many departments of industrial and political life has continued to be drawn largely from Australia and Japan. These conditions exist to a great degree at present, and though much interest is the coal-deposits of the Philippines

Jan 1, 1909

Consideration of the questions: (i) is it feasible to study groups of processes in a generalised way? (ii) to what extent does purpose affect the form of a process model? (iii) are there any significant, novel investig- ations which can be made by computer simulation? (iv) what long-term developments are desirable in extractive metallurgy? has led to some new broad objectives for research in hydrometallurgical process engineering. Propositions for grouping processes, developing models for different specific purposes, using a systems engineering approach and developing high technology processes are discussed, and the role of computer simulation indicated by reference to particular projects.

Jan 1, 1984

By Hal McVey

"Philosophy" addresses the definition and assigning of importance to the marketing of by-products. Two examples, one in metals and the other in industrial minerals, explore prime product to by-product relationships. Relative revenues from all products illustrate the importance of by-products to economic feasibility. "Mechanics" takes a broad view of the types of marketing organizations that are applicable to individual circumstances in the marketplace. In-house marketing as well as agents, merchants and trading companies are outlined and discussed. Philosophy Definition Of Terms Philosophy Definition Of Terms The definition of terns for a paper such as this is generally a necessary but not-very-interesting exercise. However, in simply trying to clearly define the term "by-product" some interesting relationships between products arise and the line of demarcation between "product" and "by-product" often becomes obscure. The search for that distinction represents the philosophy portion of the title. A couple of definitions of philosophy can even help to set the tone for what follows. According to Webster, philosophy is : 1 Pursuit of wisdom. 2. A search for a general understanding of values and reality.

Jan 1, 1983

By Sharon Brady, Catherine O’Donoghue, John V. Beall, Paul C. Merritt

Between 1950 and 1965, more than 80% of all phosphate rock produced in the world each year was used as fertilizer, either directly applied to the soil or processed into mixed chemical fertilizers. Of the potassium salts produced, 95% followed suit. A variety of uses in industrial chemicals and consumer products absorbed the remaining percentage of each. Future trends in these two commodities will be dominated by what happens to the fertilizer market. Farming is much the same as mining the soil. Plants remove the minerals little by little. Phosphate and potash comprise two of the three primary nutrients removed in this way, the third being nitrogen. Phosphate stimulates early root formation and growth, whereas potash is a salt necessary to root strength.

Jan 10, 1966

By Chester A. Fulton

In Polk County, Florida, the mining of raw phosphates began some 50 years ago with dredging operations on the Peace River, and in other near-by places by removal of shallow overburden with negroes and wheelbarrows, or with mules and scrapers, and the excavation and screening of deposits found close to the surface. There were many individual operations of comparatively short life. Later steam shovels removed the overburden, and still later hydraulic methods were substituted for the steam shovel. Within the last 10 years large electrically operated draglines have almost entirely replaced hydraulic mining for overburden removal. The matrix is still mined by hydraulic giants and pumped to the washer or recovery plant. The many small operations have long since disappeared and the most desirable phosphate lands have gradually been acquired through purchase or merger by the seven companies that are operating in the field today. These companies are producing and selling about 2,000,000 long tons of phosphate per annum, or about two-thirds of what the industry likes to think is the normal output, with 1929 and 1930 in mind. To produce these 2,000,000 long tons of raw phosphate, they mine and treat about 1,000,000 tons of tailings from older and less efficient operations, about 11,000,000 tons of matrix, and remove from above this matrix some 22,000,000 tons of overburden. The mining practice that has made possible the excavation and handling of 34 million tons of material to win but 2 million tons of merchantable product, selling for probably an average of only $4 per long ton when dried, should be of interest to the mining profession, though little has been written of it. The Florida Pebble Field, as it has come to be known, comprises an area (Fig. 1) within a radius of about 18 to 20 miles centering around Mulberry in Polk County, a small town 30 miles east of Tampa, Florida's largest port on the Gulf coast. The geology1 of these phosphate pebble deposits may be described briefly. A fairly pure limestone was altered to a secondary apatite.

Jan 1, 1938