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By T. B. Brooks

THE iron ores of the Marquette region are mostly extracted in open excavations; hence the process is more properly quarrying. Several attempts at underground work have been made, which have not, on the whole, been successful. The Edwards mine has been almost entirely wrought by candle-light. The slate ore pit, NO. 1, of the New England mine, is now worked in the same way, as is also the Pioneer furnace pit of the Jackson mine. The Champion mine was opened systematically for underground work, with two levels, 60 feet apart, and three shafts at distances apart along the bed of 200 feet; but this idea has been practically abandoned, the greater part of the ore in that mine being now taken out in open pits. Several other mines have occasionally worked underground stopes, but only temporarily; if such stopes could not be opened out to daylight, they have usually been abandoned. In brief, it may be said that no considerable amount of ore has as yet (1870) .been extracted underground in the region, and of that so mined very little has been taken out at a profit; and I may add that it seems to be the belief of the most experienced mining men that this state of things will hold for some time to come for reasons which will appear. Nearly the same remarks may be applied to the mines of the Iron Mountain region, Missouri, the ores of which are very similar in character to those of Marquette. Some of the New York and New Jersey magnetic deposits are wrought open, but this is the exception, underground mining there being the rule. The following brief sketch of the geological structure of the Marquette deposits will indicate some advantages of the method of mining employed. The iron-bearing (Huronian) series of rocks, are stratified beds, the principal ore formation being overlaid by a quartzite, and underlaid by a diorite, or greenstone. This ore formation is made up, first, of pure ore; second, of "mixed ore" (i. e., banded

By J. Gordon Parr, A. J. Goldak

OgdEN et al.1 and Bumps et al.2 suggested that the solubility of aluminum in a titanium extended to 30 pct.* Sagcl,3 Clark and Terry,4 Anderko et al.,5 Ence and Margolin6 and Saulnier and croutzelles,7 subsequently proposed the existence of an intermetallic compound in the region of 25 pct Al. Although Anderko et al.5 suggested that the structure of this phase, Ti3Al, was of the DO,, (Ni3Sn) type, their conclusion was based only upon the results of a powder photograph that included reflections from ? = 0 to ?= 27° (CuK),some of which were reported to be indistinct. Ence and Margolin,6 referring to a 25 pct alloy (but without indicating whether the figure referred to weight or atomic pct) stated: "The structure of Ti2Al is isomorphous with Ti3Sn DO19, as pointed out by Pietrokowsky". But the point was not proven, because Ence and Margolin did not report values of calculated intensities of Ti2Al with the DO,, structure. In fact, the observed intensities they reported are in poor agreement with the values we calculate for DO19 (see Table I). Saulnier and croutzelle7 concluded, on the basis of electron micrography and microdiffraction studies, that the structure of the 25 pct A1 alloy was ordered hexagonal. Our purpose has been to unequivocally determine the Ti3Al structure. Alloys containing 25 pct Al were prepared from iodide titanium and spectrographic standard aluminum by levitation melting. The levitation chamber was evacuated to 10-6 mm Hg before filling with 99.999 + pct A. After casting, the alloy was chilled to liquid air temperature and crushed to -200 mesh in a percussion mortar. The powder, wrapped in molybdenum foil, was annealed (by induction heating) at 1000 "C for 2 hr in the argon atmosphere of the levitation chamber. No sublimate was seen on the foil or elsewhere, and therefore the assumption is

Jan 1, 1962

By A. J. Kesterton

MORE than 90 pct of the total tonnage of ingots made at Abbey Melting Shop is for steel sheet to specifications ranging between 0.055 and 0.07 pct maximum carbon. Since the rate of carbon elimination in the open hearth declines considerably as the carbon approaches these low levels, the use of oxygen for this purpose constituted a profitable field for development, particularly to increase ingot output. Development Several experiments were carried out initially in which water-cooled guns, originally of all-steel construction and later with fabricated copper heads, were introduced manually through a hole in the back wall of one of the 225 net ton furnaces, the oxygen being delivered about 4 to 6 in. above the slag. Successful blows were obtained, but manipulation of the gun was cumbersome. Application through the charging doors by means of bare steel lances was considered but rejected, because much of the scrap was light, necessitating a large number of buggies per charge, and consequent long occupation of the track in front of the furnaces by buggies. To construct an efficient mechanism it was decided to experiment with the introduction of the gun through a hole in the roof. This was eventually successfully achieved, with the following advantages. 1) The actual mechanism required is simplified, and can easily be remotely controlled. 2) No large steel framework projects out over the back platform, possibly interfering with tapping, and there is no danger of damage by casting cranes. 3) The railway track in front of the furnaces is left entirely clear for the passage of scrap buggies, eliminating interference with adjacent furnaces charging. 4) As compared with the use of bare steel lances, a water-cooled jet eliminates the manpower required to handle, control and change the bare pipes. 5) A jet through the roof can be situated over the center of the bath so that, whatever the direc-

Jan 1, 1958

By Joseph W. Richards

This method of briquetting flue-dust, or flue-dust mixed with fine ores, or, in a few exceptional cases, coke-dust, has come into large commercial use in Europe, and a small plant is already in operation in the United States. It promisea to become of such great importance to the iron industry of the United States that the following description will certainly interest the majority of our pig-iron producers. Discovered in 1908, the process Tests upon the observation of Dr. Schumacher that blast-furnace flue-dust, while possessing of itself no binding or cementing properties, acquires strong cementing properties if mixed with a very small amount of certain salt solutions, the amount of which is so small that the resulting cementation appears to be rather by catalytic action of the salts added than by the mass-action of such chemicals. To be more specific, fresh blast-furnace flue-dust mixed with from 5 to 10 per cent. of its weight of magnesium chloride or calcium chloride solution—that is to say, with from 0.25 to 2 per cent. of its weight of magnesium chloride or calcium chloride—acquires the property of setting within a short time, from 15 to 60 min., and forming a hard cemented briquette. Alkaline solutions appear to have no action such as described, and they even interfere, if present, with the action of the magnesium and calcium solutions. When treated in this way the flue-dust briquette sets very hard, apparently from pure excess of cementing- and setting-power. It is, therefore, possible to mix with the flue-dust a considerable proportion of inert ore or like material, which has no setting-power by this process, and thus to make a compound briquette containing large quantities of ore mixed with flue-dust, but in which the flue-dust may be regarded as the cement or binding-material. A particularly strongly cementing flue-

Jan 1, 1913

By G. E. Steudel

THE study of the possibility of effecting a lower cost in the manu-facture of pig iron reveals the importance of the ever present question of slag chemistry and volume. Factors that determine slag chemistry and volume are the impurities in the ore available, the ash-sulphur content of the coke, and a flux material necessary to promote removal of sulphur. Of these, the ores present by far the major source of impurities and what may prove to be the lowest practical slag volume with desired chemistry in one locality may be considered low or high in some other center of iron manufacture. The Chicago district is not only blessed with ores of high quality, but with excellent coke and flux materials as well. It is the intent of this paper to discuss slag problems at the South Works only, where burdens consist of Mesabi ores, Michigan stone, and coke ranging from 7 to 9 per cent ash and containing an average of 0.57 per cent sulphur. Early in the development of modern blast-furnace practice, the con-sideration of slags was secondary to the many adjustments of mechanical difficulties, such as furnace lines, stock distribution, stove design for obtaining higher blast temperatures, improved chemical segregation and size of raw materials. Furnace operators, after making these improve-ments, turned their attention to the study of other refinements in practice, of which slag chemistry appeared to be the most important. It is only within the last two decades that operators have become familiar with the various aspects of slag compositions. The industry, while rather slow in its recognition, is indebted to such investigators as Rankin,1 Wright,1 Feild,2 Royster,2 McCaffery,3 Kinney,4 Holbrook,5 and Joseph5, whose researches concerning the elimination of sulphur within the blast furnace and the effect of slag composition upon melting point, viscosity, and desulphurizing power have established criteria for the selection of slags of the requisite quality.

Jan 1, 1939

By Paul M. Tyler, Oliver Bowles

The extensive employment of nonmetallic minerals antedates the use of metals, but only within the last two decades has the production of nonmetals begun actually to keep pace with the complicated activities which characterize the so-called Machine Age. The economic changes ushered in by the Industrial Revolution were reflected first in an increased demand for metals and for fuels. In the modern sense, therefore, the nonmetallic mineral industries are new and afford new opportunities for engineer and economist alike. A certain amount of caution is indicated, therefore, before attempting to apply ready-made formulas to the problems of these industries. Economics is not an exact science. In the field of production technology where the number of variables is fairly well known, the principles of economics are readily applicable, but as the student proceeds through the province of marketing into the unexplored regions of psychology and sociology he must distinguish carefully between scientific reasoning and purely metaphysical speculation, even when the latter masquerades as economics. The present paper attempts to prove no preconceived theorems and is designed primarily to stimulate careful thinking on sundry neglected phases of these industries. An attempt is made to differentiate the general problems into single aspects which afford promise of being comprehended separately; also, some fundamental statistical data are presented, but merely to indicate a method of scientific approach applicable to more intensive studies. Definition Before discussing the economics of the nonmetallic mineral industries, it is appropriate to consider what we mean when we say "nonmetallic minerals." This term, inasmuch as it is merely a negative description, is somewhat loose and ambiguous and gives rise to questions in regard to minerals that, like chromite or bauxite, are alternatively classed either as nonmetallic or as metallic minerals (or ores). The chrome ore used to make ferrochrome for steel manufacture is undoubtedly metallic in character; similar material destined for use as a refractory in the same

Jan 1, 1934

By Carl Zapffe

A Rise in less than ten years from obscurity into great prominence economically, tersely summarizes the history and status of the Cuyuna manganiferous iron ores. The Cuyuna district produces and ships mostly high-phosphorus iron ore, but the annual production of manganiferous iron ore is increasing rapidly and productions from individual mines are becoming more regular and more dependable as to grades and tonnages. This ore bids fair to become, shortly, the principal product of the district and is responsible for its present economic prominence. The iron ores of the district have been described, by the author and others, in many publications and will not be discussed here. Lately the manganiferous iron ores have been given some attention, but the range and variations of chemical composition of the ores, the principal physical characteristics of the ores and their deposits, the relative importance of the different ores and their possibilities in future developments, and the life of the respective reserves have not been discussed. It is impossible to give all of this information with the positiveness necessary for it to constitute a reliable guide for investment or even for future mine development. Each property and each party presents a special case and deserves critical consideration. We are dealing with special ores and always with a set of new conditions. Sufficient information of a general nature can be given, however, to indicate the reason for and the trend of the presently augmented developments in the district. In a great thickness of a big variety of sedimentary rocks, probably of Upper Huronion age, prevailingly of green, schistose phases of slaty and volcanic material intricately intermixed, lies a thin bed containing lenses of iron-bear ing formation. These lenses occur singly or in groups, thus causing the variation in the thickness of the formation; or they are separated at their ends and give rise to discontinuity or they overlap and display continuity with lateral offsets. Intense folding has added to the complications.

Jan 1, 1925

By J. L. Sepulveda, R. F. Yap, R. Jauregui

INTRODUCTION The Third Theory of Comminution, oftentimes called the Bond Theory, was first published by Fred C. Bond in 1952. Since then, it has been widely used in the milling industry to size crushing and grinding equipment as well as to predict and evaluate their performance. Although two other comminution theories were advanced almost a century earlier, one by Rittinger, 1867, and the other by Kick, 1885, their use was limited because they did not agree with actual commercial comminution systems (Bond, 1961). According to Bond's Third Theory, the work input is proportional to the new crack tip length produced in particle breakage, and equals the work represented by the product minus that represented by the feed. For particles of similar shape, the crack tip length is equivalent to the square root of one-half the surface area, and the new crack length is proportional to [(1/vT - vF)]; where P and F are particles diameter of product and feed, respectively. For practical calculations, the particle diameter can be expressed in terms of the 80% passing sizes, P and F, respectively. Therefore, the work input is given by, [10 _ 10', W = Wi [7P_7F(1)] Where W = the energy input to the mill, (kwh/t) Wi = Work Index, (kwh/t) P = square sieve opening which 80% of the product passes, (microns) F = square sieve opening which 80% of the feed passes, (microns) Equation (1) is the mathematical statement of the Third Theory, or the Bond equation. Numerically, the work index is the energy required in kwh/t to reduce a given material from theoretically infinite feed size to 80% passing 100 microns. The work index of a particular material is determined in the laboratory by conducting the standard Bond grindability test. Bond developed separate tests for the rod mill and the ball mill. The simplified test method described in this paper, which is used at Anaconda Research Center to approximate the work index, is an alternative procedure to the ball mill

Jan 1, 1982

By R. S. Dean

THE numerous theories of hardening which have been advanced in recent years are all satisfactory in accounting for some of the phenomena observed in hardening metals, but none so far presented account for all of the facts observed. Some years ago one of the authors, R. S. Dean,1 presented a theory to account for some of the properties accompanying work hardening. The present paper develops this theory further in the light of recent experimental, work and extends it to other forms of hardening. Many of the ideas included have come from the writings and personally communicated thoughts of others. We have attempted to give proper credit in every case, but it is possible that we have not always done so. As an historical basis it is desirable here to review very briefly the hardening theories which have been current. The first comprehensive theory of work-hardening phenomena was due to Sir George Beilby.2 He contributed the idea that with cold work part of the structure of the metal was rendered amorphous and that it was to this amorphous material that the cold-worked metal owed its difference in properties. According to Beilby's theory this amorphous material was a super-cooled liquid and, therefore, had the characteristics of a vitreous material. That such a theory is not capable of explaining the property changes in metals has been repeatedly pointed out. This theory also allowed a slip to take place only once on a given plane, which, as has been pointed out by Jeffries and Archer,3 is not consistent with the observed length of an individual slip and the amount of elongation which can be obtained by wire drawing. The modifications, which have been proposed to this hypothesis to make it coincide with the experimental facts, have to a considerable extent robbed the theory of its clean-cut characteristics. The commonest of these modifications replaces the amorphous phase with an

Jan 1, 1927

By Guy W. Crane

The geology of the Tintie mining district, fully treated, would occupy an elaborate monograph. This less comprehensive paper is devoted primarily to the occurrence and origin of the orebodies of the district, while space is given to those phases of the general geology only which seem necessary to a proper setting of such a discussion. The first geological report on the Tintic district to be issued was that by Tower and Smith, published in 1899, in the form of a paper in Part III of the Nineteenth Annual Report of the U. S. Geological Survey, and also as Folio No. 65, Geologic Atlas of the United States. About four years ago a second investigation was begun by Waldemar Lindgren and G. F. Loughlin, of the U. S. Geological Survey. With the exception of a paper on the oxidized zinc ores of the Tintic district by Mr. Loughlin, the results of their work are still unpublished. The writer's acquaintance with the district began in the fall of 1913, and has extended over a period of about two years. 1. Location The Tintic district lies about 65 miles due south of Salt Lake City, and on the west central slope of the Tintic Mountains, a short range, which forms the connecting link between the Oquirrh Mountains on the north and the Canyon Range on the south—the group constituting the first of the Basin ranges to the west of the Wasatch Mountains. The productive portion of the district embraces an area about 6 miles long and 2 miles wide, which is divided between Juab and Utah Counties. Within this area are the towns of Eureka, Mammoth, Robinson, Silver City, and Knightsville. All these points are tapped by the Denver & Rio Grande and S. P., L. A. & S. L. Railways. 2. Topography As in most of the Basin ranges, topographic relief is strong, dropping rapidly from peaks of 8,100 ft. above sea level to elevations of 5,600 ft. in Tintic Valley on the west and 4,500 ft. in Goshen Valley on the east.

Jan 1, 1916

By Jed H. Mosgrove

Ventilation is the method of producing, conducting, and distributing a constant current of fresh air through mine workings and returning the impure air to the outside atmosphere. Without ventilation no operations are possible in an underground mine. Therefore it is the most important single phase of mining, one on which everything else depends. A good ventilation system, therefore, must be correctly designed, properly conducted as the workings advance, and continually checked to make sure it is functioning correctly. Good air is essential for men to comfortably and safely perform their work. It is also essential to dilute, render harmless, and sweep the mine of any explosive fumes and the gases that are released in varying degrees by all coal seams and the rock strata in which they are contained. GENERAL The body of air that is being moved through the mine, known as the ventilating current, must have a definite way to enter and leave the mine. In other words, there must be a definite intake and return. The main consideration is to get the proper amount of good quality air to the working faces where it is needed. Inasmuch as the mine is divided into sections with interconnecting corridors, known as entries, it is necessary that there be a proper means of conducting the air to the proper points. As a simple explanation of a mine, consider a long tube and think of it in terms of a mine entry ill which the air must pass. The tube must have at least two openings before air can travel through it and this is the same for coal mine entries. The problem in ventilation is to find some means that will cause the air in the tube to flow from one end to the other. The only possible way to do this is to cause greater pressure at one end of the tube than at the other. Air at the end with the greatest pressure would then, of course, flow to the en which has the least pressure. Mine

Jan 1, 1973

By Earl S. Greiner, Eric R. Jette

The literalure on the binary alloys of iron and silicon has been reviewed by Stoughton and Greiner.1 Another even more extensive and detailed survey of the present knowledge has been prepared under the auspices of the Alloys of Iron Research Committee by Greiner, Marsh and Stoughton. Since the latter surrey has already been issued in its preliminary form, it will be unnecessary to review the literature in the present article. However, in this connection there should be noted the important work on the crystal structures of the iron-silicon alloys by Phragmén,2 who investigated the entire system, identified the various phases and determined the homogeneity ranges of these phases. It was evident in the surveys cited above that in the range from 0 to 15 per cent silicon, which includes the commercially most important, alloys, the results obtained by thermal analysis, microscopic examination and the determination of electrical, magnetic and mechanical properties were extremely confusing. From time to time various compounds between iron and silicon have been postulated to account for the results yielded by the classical methods, and much argument has ensued. It was presumed that if compounds occurred which are sufficiently diverse in their properties to account for the characteristics of the alloys, they should be recognizable as separate phases but satisfactory proof of this sort has not been found by thermal or microscopic methods. Contributing to the confusion is the fact that the electrical, the magnetic and some of the mechanical properties are "structure sensit'ive"; i. e., they are influenced to a marked degree by the presence of minute amounts of impurities, the specific characters of these impurities, the grain size, the character of the grain boundaries, small general or local strains, etc. Thus interpretations of the discontinuities in the various property versus composition curves that identified these discontinuities with phase changes or compound formation have always been open to question.

Jan 1, 1933

By Franklin Moeller

THE application of electric power for driving, mine hoists handling heavy loads at high speeds has recently been extended by the installation of what is probably the largest electrically driven hoist in this country at the Granite Mountain shaft of the North Butte Mining Co., Butte, Mont. While the weight of rock which is hoisted by this machine is not the largest now being handled by electric mine hoists, the speed of hoisting is so, and the combination of the high speed with the heavy load has resulted in a machine of considerable interest to all those actively engaged in mining. Aside from mere consideration of size, this installation deserves attention because of the careful attention given, not only to the question of economy of operation, but to the details of construction and installation of the entire equipment. The conditions to be met in this installation were as follows: Weight of rock to be raised per trip, 7 gross tons 15,680 1b. Weight of skip 8,0001b. Weight of cage 1,8001b. Maximum depth of hoisting 4,000 ft. Diameter of rope 153 in. Total weight suspended on one rope from drum 42,000 1b. Normal hoisting speed 2,700 ft. per minute. Maximum hoisting speed : 3,000 ft. per minute. Desired capacity-200 tons per hour from 4,000 ft: depth. The ore is mined in several levels and hoisting is carried on from the 800-ft. level down to the 2,700-ft., which is at present the maximum depth from which the ore is raised regularly. Development is proceeding and a depth of 2,900 ft. has already been reached. The rock is handled underground in cars holding ¾ ton, and about 10 cars are the usual load for a skip. All of the ore is clumped into underground bins, which are of different capacities varying up to 250 tons. From the bins the ore is fed into the skips without passing into measuring pockets. At the surface the

Jan 2, 1916

OUTSTANDING symbol of the machine age, the steam shovel needs no introduction. Few individuals there are, in the United States at least, that have not watched with fascination the almost human motion, the more than human strength, the rhythm of the whole steam-shovel cycle of crowding, digging, swinging, dumping, swinging, and crowding again. A mass of steel with some copper and other metals, fed with water and coal, guided by a single alert and dexterous operator, or perhaps two, does the work that would require 50 to 500 men or even more. The largest shovels working in the copper mines have loaded into waiting railway cars as much as 10,000 tons of ore in a single 8-hour shift. With no equipment but hand shovels, it would, in fact, be impossible to duplicate the work with any number of men; first, because they would be in each other's way, and second, because the steam shovel can lift single pieces of rock weighing 5 or 10 tons with effortless ease. Of recent years, internal-combustion engines and electric motors have displaced steam as a motive power in many instances; and of course the detailed design of the shovels has been improved immensely. Whereas the largest dippers used 30 years ago had a capacity of 3 ½ to 4 cu. yd., today the 350-ton shovel used at Chino has an 8-yd. dipper, as has the 320-ton shovel at Chuquicamata. Incidentally, for stripping at coal mines a shovel having an 18-yd. dipper is in use. However, the principle of operation of the modern shovel, regardless of the size and type of motive power, is essentially the same as that of the earlier shovels. It is fair to say that the indispensable of open-cut mining is the steam shovel, or, to be more precise, if perhaps less picturesque, the power shovel. Somehow the electric shovel seems to lack the glamour that

Jan 1, 1933

By Eugene McAuliffe

TWO years ago the American Institute of Mining and Metallurgical Engineers made a memorable contribution toward a better understanding of the problems that have for many years confronted the coal industry. Specific suggestions toward betterment were then advanced, certain of which were taken up, amplified and endorsed by men who were conscien-tiously interested in the work of lifting this great industry out of the morass it has lain in for years. Two certain suggestions then made-provision for seasonal variations in railroad freight rates that would tend to encourage the purchase and movement of coal during the low summer production period, and provi-sion for the collection by the United States Government of all the facts surrounding the industry-were intro-duced in the form of legislation in the United States Senate by a member of that body, a man whose personal character, antecedents and business training put him above and beyond all suspicion of demagoguery; however, as the result of the insistent, vindictive opposition of the industry itself, these two bills, con-structive in their nature, were buried under an ava-lanche of misrepresentation. Today, with all mines that employ union labor at a stand still, the work of stabilizing the industry is yet before us. As aptly stated by Herbert Hoover, in March, 1920, when he was president of the Institute; An engineering organization is particularly the body to under-take this work. It is an economic problem, an engineering pro-blem within the ken of our experience; it is a problem that requires not only constructive thought but quantitative thought and wise social thought. The engineers of the United States occupy a position midway between capital and labor. They enter upon problems of this kind without prejudice either way, and they have that faculty of mind for quantitative thought, as distinguished from qualitative thought, that takes such problems as this out of the region of politics into the region of matter-of-fact solution.

Jan 5, 1922

By H. Y. Yancey, B. M. Bird

During the past four years the experimental work in coal washing carried on by the U. S. Bureau of Mines and the University of Washington has been devoted mainly to the development of special methods for the tabling of fine sizes of coals that are difficult to wash. One important outgrowth of this investigation has been the application of hindered-settling classification to coal tabling. Although used for many years in ore dressing, the term "classification" as used here may be new to many readers. It may be defined as the separation obtained when a bed of particles is held in a uniform state of suspension in an upward current of water, either continuous or pulsating, just sufficiently strong to keep the bed in a mobile condition. A common example of this type of separation is a jig in which there is no suction stroke. When the hindered-settling classifier is used with the coal-washing table, the fine-size raw coal, instead of being fed direct to tables, as is the prevailing practice, is first fed to the classifier and grouped, according to the rate of settling against the upward current of water, into perhaps six separate products. After dewatering, each of these except the sixth, a refuse product, is elevated to a seperate feed bin arid washed on a separate table. This paper gives a brief discussion of the basis for the use of hindered-settling classification of a table feed; a description of the experimental work; a comparison of the results obtained with and without classification; and a discussion of the application of the classifier in commercial coal washing. Basis for Use oF Hindered-settling Classification of Table Feed Although theoretical reasoning might be used to justify treating a table feed by hindered-settling classification,l the simplest method of demonstrating the need of such a step before tabling is to show the

Jan 1, 1930

By Waldermar Lindgren

[The observations here presented were made during a short visit at Calico, in December, 1886. The accompanying map, which does not claim to be more than a careful sketch, is based on the position of a few mines obtained from Mr. F. Lewis, at Calico, and the plats in the Land Office with the patented claims. Only a few claims are shown by their boundary lines: as usual in mining districts, there is an enormous number of them, often conflicting or overlapping, the correct mapping of which would be useless for the present purpose. The rest of the topography and the drainage are mapped from sketches, aided by compass and aneroid. The elevations are taken from Daggett as base, the altitude of this station being determined by the railroad to be 2000 feet.] Until a few years ago the product of silver in California was of little importance, compared with that of gold, and often fell short of $1,000,000, the only noteworthy counties being Mono, Inyo and San Bernardino. About 1881, however, important discoveries were made in the deserts of San Bernardino, and the remarkable increase in the production may be seen from the following figures, taken from the Reports of the Director of the Mint: Silver Production of California. Of San Bernardino Co. 1883,. .. $1,460,000 $1,050,050 1884,. .. 3,000,000 2,550,000 1885,. .. 2,568,036 2,363,436 By far the largest portion of the product of San Bernardino is derived from the district surrounding Calico, although the success there has also given fresh stimulus to prospecting and mining in other parts of the county. San Bernardino borders towards the east on Nevada and Arizona, towards the south on San Diego County, California. Topographically, as well as geologically, the largest part of it belongs to the Great Basin. Broad shallow lake-beds or valleys with an elevation of 2000 to 3000 feet, are separated by low mountain chains and

Jan 1, 1887

By George Stanley Scott

Many requests for information as to the possibility of washing coals to some predetermined percentage of ash or sulfur have suggested that the producers aim to satisfy some degree of purity set by the user of the fuel, rather than to attain the greatest economic benefit to all concerned. This paper is written to show that the highest economic purity of washed coal can be determined from washability studies of the raw coal, costs of mining and washing coal, and data on the effect of ash and sulfur on the value of the coal for the particular use for which it is intended. Coke fob Blast-fuenace Use For purposes of illustration, we take the case of coal washed for coke to be used in the iron blast furnace. The method outlined can be made general in its application by substituting for the figures used here the actual operating figures for the particular case under consideration. In general, it costs the blast-furnace operation from 8 to 25 c. per ton of pig iron to slag out each 1 per cent. of ash introduced into the blast furnace by the coke. This figure depends on which one per cent. of ash is removed, and decreases with decrease in ash. When blast furnaces and coal mines are considered as a whole, the figure decreases to zero and then becomes negative, on account of low recovery of washed coal. Various figures1 have been given by different investigators. These figures necessarily differ, not only on account of the differences in operating costs but on account of the difference in the respective fuels as well. For the purpose of this paper, which, as explained, is to point out a method of attacking a certain problem, the figures used in the exposition of the method are of secondary importance. It is apparent that no universally applicable figures can be used, because there are none. Each plant has its own coal,2 its own operating cost, and its own conditions.

Jan 1, 1930

By Charles H. Behre

SLATE (Thonschiefer, German; ardoise, French) is a rock, an aggregation of mineral grains, occurring in nature, which is used for roofing and other special purposes. It is finely granular and crystalline and generally derived from an originally clayey bed or series of beds. As a result of its having been put under essentially horizontal compression by geologic forces, this material now has its particles elongated and flattened so as to yield a very good rock cleavage along the flat surfaces of the minerals, a feature entirely independent of the original bedding in the rock. This is the gist of the definition adopted by the Committee on Slate of the American Society for Testing Materials. Slate differs in varying degrees from most other common rocks (such as limestone, sandstone, granite, and "trap") in chemical and mineral composition. Its most characteristic feature, however, is its tendency to fracture along a series of very nearly parallel and very closely spaced smooth planes, called cleavage planes. This property of cleaving, above all else, gives slate its industrial value. ORIGIN AND MODE OF OCCURRENCE Most of the features of slate might be anticipated from its origin. Being a rock rather than a mineral, its composition may vary consider- ably without impairment of value. In most slates, the material of which the rock is now composed was once deposited as clay on the bottom of a lake or sea. Subsequently these clayey strata were compressed by the kind of lateral pressure that folds rock strata, the minerals of the clay being changed or metamorphosed. In the chemical reaction involved, new and essentially plane-shaped minerals belonging to the mica groups were developed. Other minerals were formed but micas generally pre- dominated. These were oriented so that their two longer dimensions are approximately at right angles to the last effective direction of pressure. Since the crystals are thus subparallel, fractures can be developed easily along their surfaces, much as cards can be separated by inserting a knife blade between them. For the foregoing reasons, slate is found in noteworthy amounts

Jan 1, 1949

By Alfred G. Heggem

It is the purpose of this article to describe methods recently introduced into the oil and natural gas industry to safeguard the lives of the workmen and to protect property from destruction. Only such drilling methods are described as pertain directly to the operations necessary to maintain the well under complete control at all times. Wells Formerly Drilled Without Controlling Equipment It may seem incredible that practically all wells, until rkcently, were drilled without the provision of any means for control. To drill a hole into a boiler carrying high-pressure steam without first providing means to control the escape of steam would be unthinkable, yet in oil fields wells are drilled into a gas or oil formation with a possible pressure of 300 to 1,800 lb. per square inch and a daily flow of 20,000,000 to 80,000,000 cu. ft. of gas or 1,000 to 15,000 bbl. of oil per day. Some wells have produced in excess of 100,000 bbl. of oil per day, but these are exceptional cases. In addition to the loss of product, one must consider the great danger attendant upon the promiscuous liberation of such an amount of explosive and inflammable substance. Introduction of Metal Casing for Deep Drilling The introduction of metal casing to secure a permanent and impervious wall in a well made the drilling of deep wells possible and removed many of the original problems encountered in well drilling, but it did not insure the control of the well. To obtain the full value of the casing it was essential that a pressure-tight joint be made between the wall of the well and the lower end of the casing. Many materials in various forms were used, including cotton, hemp, stable refuse, oats, rice, cloth, leather, cork, rubber, lead, clay and cement, resulting, after a slow process of evolution, in the general adoption of two types of bottom fittings for

Jan 1, 1916