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By J. W. Harden

APART from the merits of the respective systems of mining under conditions alike, there is much in the nature of the coal and the measures with which it is associated, to make that system which is successfully practiced in one locality ill adapted to that of another; the structure of the coal itself, the roof, the floor, the depth and character of the overlying strata, each exercising more or less controlling influence. Again, in the highly bituminous districts, and with such as have caking coals, where the size of the coal as it comes off the face does not affect its value, as the very smallest of it may be utilized, and in the hard, the open and free-burning coals, in some of which the round only (large coal) is merchantable,

Jan 1, 1873

By Charles R. Keyes

A COMPLETE transformation has taken place in the boras industry during the year 1908. A most remarkable factor in this radical change in method of producing the crude borates has been its removal from the realm of industrial chemistry to the field of mining. With the development of extensive deposits of borate-minerals interstratified in thick sequences of Tertiary clays and sands, their winning becomes a strictly mining-enterprise, of the same kind and of the same certainty as the digging of coal or iron-ore. The major supply of the world's production of commercial borax now comes from the United States. While formerly all of the boric salts of commerce were laboriously extracted from the waters of saline lakes of the arid regions, or from the bottom-salts of desiccated ponds, it later was largely slowly leached from ancient desert shales and clays. During these periods the borax industry was a very hazardous and expensive vocation.

Oct 1, 1909

By V. H. Gottschalk

THE solubility of gases in metals has been of interest since Graham's time in 1866, but, although the subject was actively studied by iron and steel metallurgists during the eighties, the era of painstaking laboratory investigation begins in 1907 with the publication of Sieverts'1 thesis on the occlusion and diffusion of gases in metals. Since then, Sieverts has worked almost continuously in this field, and his views on the subject are the prevailing ones at the present time.2 Probably the most important result obtained by Sieverts, and frequently verified since by other observers, is the discovery that at a constant temperature the solubility of almost all gases in both the liquid and solid state of most of the metals is proportional to the square root of the pressure (for pressure above 100 mm.). The obvious explanation of this fact is that the gas dissolves as atoms and not as molecules, although it has been pointed out a number of times, first by Donnan and Shawl in connection with their work on the solubility of oxygen in silver at 1075° C., that the formation and solution of a compound of the metal and gas would also be indicated by a variation of the solubility with the square or higher root of the pressure. Sieverts4 himself raised the question whether the usual explanation (i. e., that the gas dissolves as atoms) may not be wrong, when he found that the square root law held also for the solubility of sulfur dioxide in molten copper; in which case dissociation into simpler molecules or atoms does not take place. Stubbs5 subsequently showed that Sieverts and Krumbhaar's "constant" for sulfur

Jan 1, 1932

By Dwight Farnham

Description of Quarry THE shale used at the Renton plant of the Denny-Renton Clay Coal Co., for the manufacture of vitrified paving brick occurs in a hill rising from 200 to 300 ft. above the level of the valley in which the plant is situated. The shale deposit, which is of unknown thickness pitches about 10° to the southeast. The 150-ft. face worked extends approximately east and west, so that the clip, as shown by the photograph, is to the left and into the hill. The shale is overlain with about 50 ft. of gravel, 70 ft. of clay, and 30 ft. of mixed loam and gravel, making altogether from 125 to 150 ft. of overburden. Disposal of Overburden The overburden is removed by sluicing. For this purpose a No. 2 Joshua Hendy giant is used, throwing a 12-in. stream', and having 60 lb. pressure at the nozzle. The water is drawn through an 8-in. pipe from Cedar river, about 1,000 ft. distant, by means of a Worthington four-stage centrifugal pump, direct connected with a 100-h.p. motor placed just south of the factory, and 1,500 ft. from the nozzle This plant handles the material satisfactorily to a height of about 75 ft. above the level of the top of the shale. When the higher levels are worked, an auxiliary plant consisting of a four-stage Byron Jackson centrifugal pump with a 100-h.p., belt-connected motor, is thrown into the system. This plant is situated on top of the shale and can be discerned at the extreme right of the trestle work in Fig. 1.

Jan 9, 1914

By HOMER L. WILLIAMS

WHILE some of the mining companies have been pumping a small amount of water for some time, it is only in recent years that large quantities of water have been encountered in the Tonopah district. The water appears to be in different zones or belts so that the draining of one property does not necessarily affect the one adjoining. Consequently, each company has its own pumping plant and its own conditions. The companies panes handling the largest amount of water are the Tonopah Extension Mining Co., Halifax Tonopah Mining Co., West Tonopah Consolidated Mining Co., and Great Western Consolidated Mining Co. The Halifax shaft is on the eastern end of the district and the other three properties on the western. The ore-bearing formation occurs at greater depth on -the eastern and western ends, hence the water problem in these properties.

Jan 1, 1921

By R. Neilson Clark

THE discovery of a thin pay streak, yielding carbonates of copper, native silver, and perhaps chloride of silver, was made on the 9th of April, 1874, within the trachytic belt which forms part of the Sierra Mojada. The discoverer named it the Humboldt Mine. On the 2d of May, 1874, another discovery was made, in a northwest direction from the Humboldt, at about five hundred feet distant, this was named the Pocahontas Mine. After some exploration these two discoveries were proven to be on the same vein. To the southeast of the Humboldt a claim had already been taken up, called the Virginia; and to the northwest of the Pocahontas, one called the Southeast Leviathan. On these last two this same vein has been found and worked. This paper will therefore treat of the Humboldt-Pocahontas vein, as worked on these four claims, to wit: beginning at the northwest, the Southeast Leviathan, the Pocahontas, the Humboldt, and the Virginia claims. Since the spring of 1874, there has been sunk on this vein a total of twenty-seven hundred and fourteen feet of

Jan 1, 1879

By Hobart M. Kraner

THE mineralogy of blast furnace sinter is of interest because its mineral content is one of the important factors contributing to its character. There are so many other factors affecting the properties of the sinter, however, that it is well to mention them here. The proportion and character of the raw materials, that is, raw ores, concentrates, returns, and fuel, as well as the mixing and the water content, all have a marked effect on the physical properties of the product and the degree to which sintering action can be carried on. The process of sintering is a relatively fast operation. In as much as appreciable time is required to carry on processes of fusion in such masses of low thermal conductivity, large lumps of hematite ore frequently remain unfused and partly unchanged in state of oxidation in the sintering process. The kind, the grain size, and the amount of fuel used affect both the completeness of the fluxing reaction and the prevailing atmosphere. The rate of reduction in laboratory tests is not only dependent upon the state of oxidation of the sinter but also upon the sizing and porosity.

Jan 11, 1953

By Paul T. Benson

MOST important of the various departments of a custom smelter, so far as the financial welfare of the plant and the confidence of shippers are concerned, is that responsible for correct weights, accurate moisture sampling, and the obtaining of control samples that are strictly representative of the lot of ore from which they come. Treatment rate schedules are based on the metal content of ores received, reduced to dry weight. These rates must be low enough to keep the ship- per from taking his business else- where and still must allow the smelter a profit. Assay results, likewise, must satisfy the shipper, but if they show too high a metal content for the ore they represent, the smelter will actually lose money. It is always considered, and constant checks through umpire assays prove, that laboratory results are closely correct, so the bur- den of the plant profit and loss and the satisfaction of the shipper rest squarely upon the sampling department.

Jan 1, 1936

By S. F. Emmons

IT was said by many who discussed Professor Posepny's admirable paper on the " Genesis of Ore-Deposits," read at the Chicago meeting of the Institute, in 1893, that its most valuable feature was the clear distinction which it drew between the influence upon ore-deposits of the "vadose " circulation of waters descending directly from the surface, and that of the deep underground circulation of waters generally coming from the depths, and assumed by the author to be ascending through more or less open spaces under the influence of heat. A little later the effect of the oxidizing action of the vadose circulation upon ore-deposits was ably and exhaustively treated by Prof. R. A. F. Penrose, in a paper on " The Superficial Alteration of Ore-Deposits "f-the only one, so far as I know, which has been exclusively devoted to this important subject. My own first detailed study of ore-deposits was made at Leadville, in 1880, at a time when almost the only minerals visible in those deposits were in oxidized forms. That this form was the result of the alteration of earlier sulphides by surface-waters had to be proved at the time by induction or analogy, the general correctness of which was, however, abundantly confirmed by subsequent developments. Thus I was early impressed with the importance of distinguishing, in the study of an ore-deposit, the alteration-products, resulting from the action of oxidizing waters descending from the present surface, from the earlier-formed sulphides; and, assuming that the latter were primary or original, I called the former secondary. I also went so far as to say$ with regard to oxidized ores passing into sulphides in depth "So generally is this accepted as a rule in ore-deposits that it would require special demonstration to prove beyond a doubt that the native metals or their

Jan 1, 1902

By Norbert R. Morgenstern

INTRODUCTION An understanding of the role of water in controlling the stability of rock masses is central for a rational approach to the subject. The presence of water can hinder mining opera- tions in two ways: 1. excessive discharge 2. excessive pressure It should be noted that if the rock mass is very tight, excessive pressures can exist without large discharges. Alternatively, if abundant water is available and the rock mass is open, then substantial discharges can occur under quite small pressures. The problems associated with excessive discharge are usually well understood by the mining engineer. Vehicle mobility is inhibited, some areas are flooded and hence become inaccessible; at best, a costly nuisance exists. The methods of solving these problems are also well-known to mining engineers. They generally involve tapping the source of the excessive discharge and channeling it away in such a manner that any hindrance to the mining operation is minimized. The effects of water pressure on the stability of rock masses are less obvious and the following will be devoted solely to this aspect of the problem. The manner in which water pressures enter into the consideration of stability is made clear by an understanding of the concept of effective stress. THE CONCEPT OF EFFECTIVE STRESS The simplest mechanical model for the problem of rock slope stability consists of a rough, rigid block sliding down an inclined plane under the influence of gravity. This is illustrated in [Fig. 1]. The down-slope component of the weight of the block tends to produce movement which is resisted by the shearing force generated by friction along the base of the block. The shear stress per unit area inducing movement is

Jan 1, 1971

By W. L., Yerkes

AN interesting study of the application of air-, conditioning to the problem of mine ventilation and cooling can be found on the Witwatersrand in South Africa. Here there are a large number of deep mines in a relatively small area. Due to the nature of the reef, many mines are working at a depth of 6000 ft. and some have gone down to 8000 and 9000 ft. below the surface. At such depths, even in a country geologically as old as Africa, the virgin rock temperature approaches 110°F. The flow of heat from the- rock to the ventilation air is tremendous though the shaft or drift may have been open to ventilation for some years. In addition, there is the heat produced by machinery, lights, and men at work and the heat of adiabatic compression of air introduced into the mine. The difference in atmosphere pressure between the collar of a shaft and a level 6000 ft. below is nearly 3lb. per sq. in., resulting in an increase in heat content of nearly four B.T.U. per pound of air delivered to the mine at surface. Further the exclusive use of wet mining to reduce the incidence of miner?s phthisis increases the latent- heat content of the air.

Jan 1, 1941

By J. J. Brown

Wilkes-Barre Meeting, Julie, runs., THE ore-hearth was the earliest type of furnace used in smelting Mississippi Valley lead-ores, which are very pure, and low in silver-content. The first smelters made no attempts to recover lead from the smoke; and since about 15 per cent. of the lead -in the charge escaped in this manner, early practice with the hearth was decidedly wasteful. At most of the large smelting-plants blast-furnaces with auxiliary roasters were substituted for the hearths long ago. But, upon the introduction of the Lewis and Bartlett bag-process for collecting fume, the ore-hearth was used by companies engaged in the manufacture -of pigments, simply on account of the large percentage of fume made by it. In fact, the extraction of lead was kept down by the use of hot blast and other devices. During recent years, however, several smelting companies have realized that the preliminary roasting of galena for the blast-furnace is not economical, and have, therefore, replaced the roasting-furnace with a modification. of the old Scotch hearth, in which a large percentage of the lead in a charge is recovered directly as pig-lead, while the remainder passes partly into fume and partly into slag low enough in sulphur to be charged into the blast-furnace without further treatment. The results obtained have proved so satisfactory, both As to recovery and operating-expense, that one eminent metallurgist has predicted the universal use of the ore-hearth on non-argentiferous ores. The-ore-hearth, thus employed as an adjunct to a blast-furnace plant, is rather a desulphurizer than a smelting-furnace proper,-the chief object being to make a blue slag suitable for the cupola-furnace. Hence, no special care is taken to obtain from it a large lead-extraction. * Head of Department of Ore Dressing and Metallurgy, Oklahoma School of Mines and Metallurgy, Wilburton, Okla.

May 1, 1911

By H. B. FERNALD

THE interesting and carefully developed formula which Professor Bucky presents for answering the question of whether proposed new equipment will give a net return on investment equal to or greater than that on present equipment starts with an assumption that the management may make this relative return a determining factor in its decision whether or not the new equipment should be provided. I do not question that in some cases the management may take this position, but I would point out the error involved in so doing. The proper test is not a comparison of the return on new as compared with the return on old investment, but is rather a comparison of the return on a particular new investment as compared with the return which would be obtainable from some other new investment which now might be made. Then I would point out that I believe Professor Bucky is in error in using as a factor in his computations the item of unamortized cost of old investment. The financial advantage to be derived from a new investment does not depend on the extent to which we may in the past have written off the cost of old equipment, nor does it even depend upon what was the original cost of that old equipment. Even the salvage or resale value of the old equipment will only enter into the picture to the extent that the present salvage or resale value differs from the ultimate salvage or resale value otherwise to be obtained, after due allowance for the interest factor.

Jan 1, 1930

Twelve Directors, the Secretary, and ten guests were present. It was unanimously resolved that the sense of this body is that the name of the Institute should be changed to American Institute of Mining and Metallurgical Engineers. Messrs. J. W. Richards and Bradley Stoughton were appointed a committee to formulate the necessary steps for bringing the matter to a vote. The committee in charge of the New York meeting, with Allen Rogers, Chairman, was appointed. The rules of the American Engineering Standards Committee were approved. The Bulletin was presented to the Springfield Arsenal. The sum of $250 was appropriated to the Southern California Section. The By-laws were changed to increase the Secretary's cash from $500 to $1000. The report of the Treasurer was accepted. Sixty-eight members, thirteen associates, and forty-eight junior associates were elected. Four members were reinstated. The resignations of seven members were accepted. Thirteen members on active duty at the front had their dues remitted. Upon the recommendation of the Finance Committee, it was resolved that the clues of any members who have attained the age of seventy (70) years and have been members for a continuous period of at least thirty (30) years shall be remitted.

Jan 7, 1918

By Frederick G. Clapp

SINCE oil journals commenced to feature the progress of Iraq pipe-line developments and since newspapers undertook to follow the discussions between a certain large oil company and an Asiatic nation, I have repeatedly been asked questions that are only answerable by setting forth the essential geographic and historical facts of concessions in that part of the world. In so doing effort will be made to correct erroneous statements made in various quarters: and mistakes herein are being kept as low in number as possible. Perhaps the best-known concession in the Middle East is the one of the Iraq Petroleum Co., covering the greater part of the portion of the kingdom of that name- lying east of the Tigris River. West of the stream is the concession of the British Oil Development Co., which takes in all presumed petroliferous areas in western Iraq. No other important oil concessions exist in that country, except for the lands of the Khanikin Oil Co., which operates in "Transferred Territories" on the border of Persia. East of and continuous with the Iraq fields are those of Persia where the Anglo-Persian Oil Co. holds the well-known D'Arcy concession comprising three-quarters of the country, omitting the five northern provinces. This is the only valid existing concession in Persia, so far as known, except certain old firmans that permit development at Semnan in central Persia and possibly also certain regional grants to a French banking syndicate in eastern Mazanderan Province.

Jan 1, 1933

By Persifor Frazer

I DESIRE to say that, owing to the number of papers which have been more or less crowded at this session of the Institute, and the fact that, as one of the Local Committee, I have the distinguished honor to feel somewhat like one of the hosts, I should not tax the patience of members at this late hour, but would have my paper read by title were it in any way possible to do this. But the task I have set myself this evening is to present to the eyes of the members of the Institute certain objects which have occupied more or less of my time during the last eighteen months or two years. The objects I allude to are some of the igneous rocks of this country, which, until quite recently, have been less understood than any others. It will be well known to some of the members that some of the cooled lavas of a previous age of our planet, when not directly coarsely crystalline and granular, were considered and spoken of as " natural glasses," or perfectly uncrystalline, vitreous, or hyaline masses of matter. Among the first results of the use of the microscope was the dispersion of this fallacy. Sir David Brewster, Mr. H. C. Sorby, and William Nichol (the discoverer of the celebrated calcite prism, which bears his name), had, with greater or less success, examined sections of various rocks and minerals, both by transmitted and reflected light, and also in the form of powder. But, until the genius of Vogelsang undertook the subject, these investigations had no permanent value, nor did they constitute an independent line of mineralogical and geological research. Since the close of his labors, by Vogelgang's premature and much-lamented death, the subject has been made one of renewed interest by his brother-in-law, Ferdinand Zirkel, as well as by Rosenbusch, Tschermak, and many others abroad, and at home by the commencement of a systematic study of the traps of Connecticut by Messrs. E. D. Dana and G. W. Hawes, of New Haven, and by the splendid set of described sections of the traps of the West which have been furnished by Zirkel to illustrate Clarence King's report. I had the honor of presenting a large number of thin sections of our traps at the Washington meeting, for the inspection of the mem¬bers, with the aid of a table microscope belonging to the Smithsonian Institution. Here I propose to project these sections upon the

Jan 1, 1877

By Henry Louis

THE work performed by the Royal Commission on Mining Subsidence is likely to prove of permanent value, less perhaps for the conclusions it has reached and for the recommendations it has based upon these than for the admirable exposition which it affords of the law concerning mining subsidence and of the legal status of the person who has suffered damage by reason of such subsidence, as also of him whose working has caused the damage. The Commission was appointed by Royal Warrant in the middle of 1925 and delivered its final report in the middle of 1927. The terms of reference to the Commission were as follows: "To consider the operation of the law relating to the support of the surface of the land, and of buildings or works on or under the surface, by underlying or adjacent minerals; to enquire into the extent and gravity of the damage caused by subsidence owing to the extraction of minerals and the incidence of the resulting liability; and to report what steps should be taken, by legislation or otherwise, to remedy, equitably to all persons concerned, any defects or hardships that may be found to arise in existing conditions."

Jan 1, 1929

By Henry G. Granger

DURING upwards of three thonsand miles of canoc-travel in South America, including several mishaps, the writer has unfortunately lost his book of notes taken during the year 1894 in Dutch Guyana, or Surinam. But a year spent in a foreign country, visiting its principal mining properties, is necessarily productive of indelible memories and impressions, and some of these may be of interest to the Institute. The Guyanas include British, or Demerara, Dutch, or Surinam, French, or Cayenne, and the Disputed Territory, or that portion of Brazil on the northeast coast of South America. After passing the picturesque mountainous coasts of Colombia and Venezuela, one reaches a low, flat mud-bank which extends far out into the sea, so that from the steamer, over a couple of leagues of turbid, shallow water, one call just see the dismal outline of the pestilential "bush" that fronts the Caribbean sea, clear around to the mouth of the Amazon. Here, iii the order mentioned above, are the Guyanas. So much has been said about this out-of-the-way section during the late excitement over the Venezuela boundary question, that the historical part of the subject may be advantageously condensed. Gold-mining in the Guyanas is altogether placer-mining, and is of the same general nature throughout; hence by describing the methods in use in Surinam and the results there achieved, ail idea will be given of the work throughout the field. The product of this section is about three to four millions of dollars annually, mostly from Demerara, not because of superior richness of its placers, but as a result of its very much larger population, which exceeds twice the aggregate census returns of both Surinam and Cayenne. Mining ill all this section is of comparatively recent date, and is indirectly due to the decline of the sugar-industry. After the introduction of beet-sugar scores

Jan 1, 1897

THE first mention of the mining and use of coal in the Pittsburgh district refers to the mine under Duquesne Heights that furnished coal for the garrison at the fort at Pittsburgh in 1760. Coal had been dug and used as fuel just outside of Brownsville, Fayette county, in 1759, but this was not a regular mine as the opening was in an outcropping. Maps of Ohio in 1770 showed "Cole Mines" at various points. The Penns purchased all the coal south of Kittanning in southwestern Pennsylvania from the Chiefs of the Six Nations for a reported price of $10,000. During the Revolution, coal from Herron Hill, Minersville, and Coal Hill, all within the present city limits, was used in Pittsburgh. There is today one custom pit opened in Coal Hill (Duquesne Heights). The first steam engine was set up in Pittsburgh in 1794 and used coal as fuel. The first mine in the Youghiogheny gas district was opened in 1796. In 1803, the first shipment of coal by water was made from Pittsburgh down the Ohio river and landed at Philadelphia, where it sold for approximately $9.50 per ton. The mines along the Monongahela were naturally the first to be opened. With the completion of locks and dams in 1844, permitting slack-water navigation, the industry began to thrive. The No. 8 field of Ohio and the Fairmont region of northern West Virginia were opened in the period 1840 to 1855. From that time on there has been a continuous development of the coal resources of this district, until at present-productive capacity is enough to supply 30 per cent. of the country's needs of bituminous coal. The original method of working the Pittsburgh seam was to drive under cover at some .easily accessible point on the outcrop with a single entry, usually 1 1/2 yd. wide. Rooms or gangways were turned to the

Jan 10, 1926

By Adam L. Wesner, A. C. Richardson

DURING World War II the demand for electrode carbon was greater than could be met by the supply of petroleum coke available for this use. It was believed that coke made from an extremely low-ash coal might be a suitable substitute for petroleum coke. Requirements for electrode carbon to be used for the production of aluminum are that the silicon plus iron content shall be not more than 0.14 pct of the coke. However, during the period when petroleum coke was in short supply, it appeared that relaxations of the specifications might be allowed to permit 0.4 pet iron plus silicon in the coke. For this work, the specifications were that the coal should contain less than 1 pet of ash, and the combined iron and silicon content of the coal should not exceed 0.28 pct. Heavy-liquid separations made on a number of coals showed that if certain size fractions of some coals were separated at low specific gravities the resulting float products would meet the required specifications. The objective of this work was to develop a continuous, commercially feasible process for producing low-ash coal. After consideration of various processes, the method chosen was a float-and-sink separation using a solution of calcium chloride as the separating medium. Eagle Seam coal was used for the experiments. The -10 +35 mesh fraction was found to be the most promising feed for producing the low-ash [ ] content coal. A batch of 30 tons of -3/8-in. coal was screened at 10 and 35 mesh; the yield of -10 +35 mesh was 20 pct of the feed. This fraction comprised the feed for the separation tests. In spite of the fact that this portion was screened a second time at 35 mesh, the coal still contained 16 pct that was finer than 35 mesh. Three-fourths of the undersize was in the -35 +48 mesh range. A representative portion of the -10 +35 mesh fraction was subjected to batch float-and-sink separations to determine the best gravity to be used in the continuous tests to obtain a high recovery of low-ash content coal. The heavy liquid used was a mixture of carbon tetrachloride and benzene which assured complete wetting of all of the particles. As usual in batch separations, adequate time was allowed for each separation so that even the near gravity particles had ample time to separate. The separations were made at increments of 0.01 sp gr from 1.25 to 1.28 and also at 1.32 and 1.59. Each specific-gravity increment was assayed for ash content. From these data it was concluded that 1.27 sp gr was best for the continuous separation of the coal. The products from the batch separation were composited into float 1.27 and sink 1.27 sp-gr fractions; these were assayed for ash, iron, and silicon. Table I shows the results of the batch separations. The composite float 1.27 fraction contained 66.04 pct of the total weight, and had an analysis of 0.79 pet ash, 0.073 pct iron, and 0.112 pct silicon, or 0.185 pct iron and silicon combined. These data are indicative of the results possible if a perfect separation is made at 1.27 sp gr under static conditions. Inasmuch as the method under investigation is a dynamic system these results could not be obtained. It remained to be determined, however, just how close to the theoretical results the actual continuous separation would be.

Jan 1, 1952