Search Documents

By Arthur Taggart

A GENERAL awakening of interest among mill men concerning the mechanical efficiencies of their crushing machines is evident from a perusal of the recent files of mining publications. Considering the large part of the power bill which must be debited to the crushing department, such. interest is natural. When, however, the articles on the subject are read, the only statement upon which the writers agree is that fine grinding consumes a large amount of power, and that the machine which, from a concentration standpoint, offends as a slime producer is, for that reason, a serious offender in wasting power. When the mill man attempts to find a method for measuring the power wasted, or to compare the efficiency of one machine with that of another for the same work, he is confronted with a choice of methods which lead to conflicting results. There are two reasons why the work of crushing is not more generally understood. In the first place, experimental data are difficult to obtain; and in the second place, before these data can be put in general form certain assumptions must be made. A difference in these assumptions by different investigators has led to conflicting conclusions. This conflict has resulted in the proposal of two laws. The first of these is the so-called Rittinger's law, which is variously stated as follows: . "The work of crushing is proportional to the reduction in diameter."-R. H. Richards: Ore Dressing, p. 304 (1903). "The Work required to crush rock is very nearly proportional to the reciprocals of .the diameters crushed to."-A. Del Mar: Engineering and Mining Journal, vol. xciv, No. 24, p. 1129 (Dec. 14, 1912). "The Work done in crushing is proportional to the surface exposed by the operation, or better expressed for this purpose, the Work done on a given mass of rock is proportional to the reciprocal of the diameter of the final product, assuming that all the mass has been reduced to one exact size, which is only theoretically possible."- A. 0. Gates: Engineering and Mining Journal, vol. xcv, No. 21, p. 1039 (May 24, 1913).

Jan 1, 1914

By Wayne E. Glenn, R. W. French, Lincoln F. Elkins

The Lance Creek Sundance reservoir provides a case history of ro years performance of a reservoir in which unit operation has permitted effective utilization of gravity drainage augmented by primary pressure control with injection of gas into top structural wells. Detailed performance of the reservoir is presented by means of maps of Well status, reservoir pressure, individual well recovery, etc., and by pool-performance charts. Analysis of reservoir performance indicates only minor water encroachment, so that gravity, injected gas, and expansion of gas are the main oil-expulsive agents. A simplified theory of regional drainage of oil from upstructure location to downstructure location due to gravity is presented and checked by means of comparison of "reservoir" permeability and "well" permeability from the pool performance. Good order of magnitude agreement was obtained. Individual well performance and overall reservoir performance indicate possibility that maintenance of pressure makes ineffective those parts of the reservoir in which permeability is too low to permit effective drainage of oil by action of gravity. Oil from these parts can be recovered only when pressure is reduced locally by selective withdrawal or when overall reservoir pressure is finally reduced.

Jan 1, 1949

By Leo P. Tarasov

Magnetic torque studies of ferromagnetic single crystals have been carried out in a number of laboratories during the last decade&apos;s2 and some work has been reported on polycrystalline material showing preferred orientation. Goss3 used the method extensively in developing electrical sheet with desirable magnetic properties, but he used it as a control rather than as a means of studying the texture. Bozorth4 made a quantitative correlation of a torque curve he obtained from some cold-rolled iron with the texture as determined from X-rays, but did not extend his studies beyond the one specimen. Other studies, which have been reported from time to time2,5 have also been incomplete in the sense that no effort was made to study a whole series of samples, differing only in degree of cold reduction or in the annealing temperature, in order to ascertain the effect of such treatments on the texture as revealed by torque measurements. It is the purpose of this investigation to make such a study, mainly in order to see how useful the method can be made when used under favorable circumstances and to find what kind of a correlation can be expected between magnetic and X-ray studies of texture. Before proceeding further, it is desirable to say a little about single crystals, so as to make clear the concepts involved in magnetic torque measurements. Magnetic Torque Method It is fairly well known nowadays that single crystals of ferromagnetic substances have directions of easy magnetization and of hard magnetization. In Fig. 1 are reproduced typical magnetization curves for a single crystal of iron, which show that in a < 100 > direction saturation occurs at low fields compared to those required to saturate the same crystal in a <110> or a <111> direction. (The magnetization intensity I is defined by the equation B = H + 4pI.) At fields high enough to

Jan 1, 1939

By C. A. Czako

INTRODUCTION In recent decades sintering and pelletizing of finely divided materials have become the primary tonnage producing modes of agglomeration. This statement is especially true in the iron and steel industry and, to a lesser degree, in the nonferrous, chemical and non-metallic minerals processing industries. In every industry the main objectives in agglomerating fines are essentially the same, namely to convert ores, minerals and chemicals of undesirable fineness into agglomerates characterized by a size consistency desirable for subsequent use or processing. Depending on the type of agglomeration process selected and the conditions maintained during agglomeration, the physical process of increasing size is complemented by a number of other unit processes. These processes can occur simultaneously, consecutively or in an overlapping manner. Some of these additional unit processes are incidental to the agglomeration operation, but at the same time can be critical, depending upon the subsequent use of the product. Accordingly, during processing, conditions have to be controlled to either suppress or enhance the extent of completion of these unit processes. The purpose of this report is to review laboratory testing as the basis for engineering modern sintering and pelletizing plants. Considering that most typical applications are for the iron and steel industry, agglomeration of ferrous materials is reviewed and discussed. When these total processes are adapted to suit non- ferrous materials, chemicals, or non-metallic substances, the over- all approach remains the same; only the processing parameters are affected as necessitated by the different nature of the materials.

Jan 1, 1977

By Walter H. Bucher

This symposium is designed to lay the basis for a general discussion of the place of geophysics in the training of geologists. As there is danger that in the ensuing debate individual interests may be given emphasis out of proportion to their place, we shall do well to view the whole field of geological inquiry in order to see the problem in true perspective. The Nature of Geological Inquiry "Basic" and "Complex" Sciences It is convenient to divide all science into two major divisions, the basic and the complex sciences. The basic sciences separate out from reality such entities as "substances" and "movements," describe their behavior in terms of arbitrary units of measurement and derive from them by progressive abstractions concepts and patterns of behavior that exist between them, so-called general "laws" and "properties" of nature. The complex sciences, on the other hand, deal, with little or no abstraction, with those objects of reality that are accessible to man in the atmosphere, the hydrosphere, the lithosphere and the biosphere. Their work comprises two types of inquiry. One is concerned with abstractions to the extent of dealing with types rather than individuals—that is, with such things as plants, animals, protoplasm; clouds, streams, gla- ciers; volcanoes and mountain ranges. It comprises the search for general properties and patterns of behavior or "laws" that characterize the objects and their reactions to each other. These properties and laws apply always, everywhere. They are independent of the stream of time. We may call the results of this sort of inquiry timeless knowledge. The other type of inquiry is concerned with the objects themselves—that is, with this animal and that plant; this river system and that mountain chain; this glacier and that valley. Like all concrete objects in nature, they are subject to change with the passage of time, especially when it is measured in years, centuries, eons. The characteristics by which we recognize them —indeed, their very existence—are dependent on their position at this point in the stream of time. This we may call time-bound kntowledge. The so-called descriptive sciences are all bound to the past of which the objects of their study are the product and through which alone their present properties call be understood. They are historical sciences. This obvious fact is easily overlooked, which leads to serious misunderstanding, as we shall see later. Dynamic Geology With this broad picture in mind, let us now examine the nature of geological inquiry, defining, for the purposes of this discussion, geology as the science of rocks. Air is not a rock; water is. Meteorology and climatology are, correspondingly, gen-

Jan 1, 1946

By Howard Willey

Mining operations of the Charcas unit at present are limited to the Tiro General mine at Charcas, in the State of san Luis Potosi, Mexico. The Tiro General mine was first operated during the Spanish occupation of Mexico for rich silver ores in an oxidized zone along the outcrop of the principal vein. In depth the ore is a complex sulfide with widely varying proportions of sphalerite, argentiferous galena and chalcopyrite ; and until recent years, it was economically impossible to carry on mining otherwise than irregularly in sections of the veins richest in galena and chalcopyrite. The advent of selective flotation brought the orebody as a whole within the field of economic interest, and a flotation mill of 650 metric tons daily capacity was constructed in the year 1925. The mining of partly worked-out sections of the mine, as well as the very heavy ground in most of the stopes opened in virgin ore, presented an unusually difficult problem. This paper describes the so-called "filled top slice" stoping method finally adopted as the standard system. Physical and Geological Conditions The principal orebody of the mine is an oreshoot about 1400 ft ng in a fissure vein striking about east and west and with an average lip of 70" to the north. The footwall of the orebody is fairly cleancu and regular both longitudinally and vertically and generally shows a dell-marked post-mineral slip. The footwall rock varies from a fairly strong limestone to a broken, metamorphosed limestone which requires heavy timbering. In some sections it is an altered, crumbly porphyry, which swells badly and necessitates frequent renewal of drift and raise tirnber. The hanging wall is irregular and frequently an assay wall. The stopina width ranges from a few feet up to more than 90 ft.; it averages about 30 ft. For the most part the hanging-wall rock is a shattered and altered monzonite porphyry, nearly aways requiring heavy timbering. The orebody is greatly fractured by post-mineral movement, which usually followed the footwall and left it as a smooth surface frequently covered with a slippery clay gouge. Two well marked transverse faults

Jan 1, 1931

By P. R. Kalischer

IN the production of alloys by powder metallurgical processes it is often necessary or desirable to include one or more components that tend to form very stable oxides Included in this group of metals are aluminum, manganese, magnesium, silicon, and a few others In many cases it is not necessary for the sintered compact to have full density and the other physical characteristics of a cast alloy and in that event no undue precautions need be taken If, however, it s required that the sintered part be entirely homogeneous, and have maximum density and physical properties, some method must be found to reduce the surface films of oxide, which are always present on the metals, and for the metals mentioned above this is always extremely difficult, if not impossible Since the production of high-density alloys is of particular interest to powder metallurgists, some experiments were undertaken to devise methods of reducing the refractory oxides For this work, alloys of iron, nickel, and aluminum were chosen because aluminum oxide is one of the most stable oxides and because these alloys in the right compositions form excellent permanent magnets All of the pertinent properties of the magnets could be accurately and delicately measured by density measurements and magnetic tests of sufficient scope to give a complete demagnetization curve From such a curve the maximum coercive force, residual magnetism, and energy products could be obtained and compared with the same properties for a cast material Any lack of homogeneity, density, or solid diffusion would be immediately apparent as a decrease in the magnetic properties NATURE AND REMOVAL OF SURFACE BARRIERS The early work of the present investigation was based upon published processes In the published information it was claimed that by intimately mixing iron, nickel, and iron-aluminum alloy (50 per cent Fe, 50 per cent Al) powders, compressing such a mixture into the desired shape and size, and then sintering (heating to a temperature below the melting point of the component metals) in hydrogen at 1200ºC or higher, a sound, homogeneous article could be made having the desired physical size, shape, and strength, and good magnetic characteristics However, this early work showed clearly that something in the powder compress was inhibiting diffusion and the process was almost entirely unworkable In the initial phase of the investigation samples of iron powder, nickel powder, and iron-aluminum alloy powder were pressed into separate bars and sintered in hydrogen Both the iron and nickel powders sintered

Jan 1, 1941

By George W. Neumann

The mines and concentrator of Brunswick Mining and Smelting Corporation are located in the northern part of the province of New Brunswick, approximately 20 miles distant from the City of Bathurst. Discovery of the No. 6 orebody by diamond drilling in 1952 was followed by the finding in March 1953, of the larger and higher- grade No. 12 orebody, approximately six miles to the north of the No. 6 deposit. Original development was financed by St. Joseph Lead Co., and included a small open-pit operation with a 10C ton per day pilot mill at No. 6 orebody, shaft sinking and underground development at No. 1; orebody, and an extensive program of laboratory and pilot plant metallurgical research on No. 12 ore. These operations were suspended in May 1958, and remained in standby condition until June 1961, when the equity of St. Joseph Lead Co. was purchased by a group headed by M. J. Boylen, K. C. Irving, Maritime Mining Corporation, and the Patino Corporation. Construction of a mine plant and concentrator at the No. 12 mine commenced in October 1962 and the concentrator was placed in operation in March, 1961b. Preparation of the open pit mine for production, construction of the No. 6 Concentrator to produce bulk Pb-Zn-Cu-Ag concentrate from No. 6 ore, and construction of an Imperial Smelting Process smelter at Belledune were started in 1964 and placed in operation in September 1966.

Jan 1, 1970

By L. T. Sicka, H. N. Thomson

The Tooele plant of the Internationa1 Smelting & Refining Co. is situated at the mouth of Pine canyon, Tooele county, Utah. It is connected with the main line of the San Pedro, Los Angeles & Salt Lake railroad by the Tooele Valley railway, and is about 7 miles from Tooele Junction. Fig. 1 is a general view of the plant. The copper plant has been in operation since July, 1910, arid the first blast furnace at the lead plant was blown in on Feb. 29, 1912. The location of the plant was selected on sloping ground with the idea of using gravity to the fullest extent and thus keeping labor at a minimum. Practically the entire plant is constructed of steel, reinforced concrete, and brick. Bingham ores, both lead and copper, are received over the Utah Consolidated Aerial Tramway. The tram buckets, each containing

Jan 1, 1914

By Charles White Merrill, James W. Pennington

No metallurgical process developed in the 20th century compares with froth flotation in its effect on the mineral industry. Processes like gravity - concentration, amalgamation, and pyrometallurgical reduction are of ancient origin; others like cyanidation and electrolytic reduction were well established by 1900. Such metallurgical processes as heavy-media separation, ion-exchange, and solvent extraction belong to this century, but their influence is small compared with froth flotation. Data collected by the U. S. Bureau of Mines* in a canvass of 202 froth flotation plants reveal that, in 1960, 198- million tons of material was treated to recover 20-million tons of concentrates which contained approximately $1 billion in recoverable products. SIGNIFICANCE OF FLOTATION Froth flotation as described in this chapter refers to a wet process for separating properly ground mineral particles into two or more products. It involves the separation of mineral particles from each other in a liquid pulp by means of air bubbles. Finely crushed ore is agitated in water with the addition of air or other gases. Various chemicals and oils are added to cause the selected mineral particles to attach themselves to the air or gas bubbles. These bubbles, carrying the mineral particles, rise to the surface where they are removed in a froth, while the other particles remain suspended in the pulp. The earliest flotation divided the raw material into two products: a bulk concentrate that was removed as a froth and a tailing that remained in the flotation machine. The froth usually contained the valuable constituents. The successful application of such a process depended on the recovery of a single concentrate from which one or more valuable constituents could be recovered by a chemical or smelting process. With the advance of the art, however, the principle of selective flotation, by which two or more relatively pure products could be recovered from complex raw materials, was evolved. Other chapters in this volume describe the developments during the last 50

Jan 1, 1962

IN the early period of steelmaking, ingot structure and segregation were of no practical importance. Crucible melting required very small ingots that gave little segregation, and a small inserted hot top prevented pipe. As larger ingots were poured from bessemer converters and open-hearth furnaces, segrega- [ ] tion, piping, and gas evolution became increasingly important. The techniques of making semikilled and rimmed ingots were developed with little knowledge of the actual mechanism of the process. The first studies of solidification were made by the Brearleysl and Gathmann,2 who used stearine to show the effects of shrinkage and mold shape. Fig 11-1 is a picture of a series of stearine ingots at various stages of solidification. These studies showed that the liquid solidifies at a nearly uniform rate from the sides and bottom of the mold and demonstrated the formation of

Jan 1, 1951

By A. A. Blow

The productive area of the Leadville mining district immediately adjoining the city of Leadville, which, by its wonderful richness, has attracted the attention of the mining world for the past twelve years, may, with a few exceptions, he considered as divided into seven local mining centers, separated one from another by the topographical features of the country, and designated by common consent as Fryer Hill, Yankee Hill, Breece Hill, Rock Mill, Printer-Boy Hill, Iron Hill, and Carbonate Hill. Of these seven distinot mining localities, or groups of mines, the central one, Iron Hill, is the one of greatest importance and interest. It was the scene of the earliest discovery of carbonates, as far back as 1875, and since that time has always maintained its position

Jan 1, 1890

By Clarence Seyler

THE technical difficulties of cutting thin sections of coal for examination by transmitted light have hitherto restricted the investigation of the important subject of the microstructure of coal to the few possessed of the requisite skill and time. Apart from this, the method fails with anthracites and other coals rich in carbon, owing to the opacity of the material. Occasional use of the method of polishing a surface, with or without etching, has been made, but it was not until Winter1 published an account of his results that attention was seriously directed to the method. In May, 1923, a specimen of dull anthracite came into my hands; I tried Winter&apos;s method on it and the presence of megaspores and other vegetable structures became clearly visible. A preliminary notice was published by me;2 but I soon abandoned the use of Schulze&apos;s solution having found that a mixture of chromic and sulfuric acids gave far better results. In the meantime Turner and Randall, in America, had independently developed the method of flame etching, as applied to anthracite, with great success. I have spent a year studying the method of chromic etching, which gives excellent results with bituminous coals and cannels, as well as with anthracite. For anthracites, I have used the chromic method and Turner&apos;s method of flame etching, whichever was the more convenient or as a check one on the other. The polishing is done, according to metallurgical practice, by the use of a polishing machine and successively finer emery paper, followed by polishing on cloth moistened with a suspension of levigated green oxide of chromium, and a final rubbing on "selvyt" (a cotton velvet polishing cloth) moistened&apos; with alcohol. The polished sample is examined by reflected light with a 2/3 and 1/6 in. objective. Bituminous coals usually show considerable structure, and even anthracites show it faintly in places. The sample is then etched by immersion in a boiling solution made by adding 10 c.c. of concentrated sulfuric acid to 30 c.c of a saturated solution of chromic acid; enough water is then added to dissolve

Jan 3, 1925

By Augustus Locke

In 1900, when. the public first heard of "secondary enrichment," the Butte chalcocite seemed clearly supergene. Mining, through successive regions of leached capping, bonanza sulfide, and sulfide less rich, had paused at lean bottom levels which, though chalcocite-bearing, suggested the waning of copper. The deepest chalcocite, at 1500 ft., was yet too shallow to disturb the supergene hypothesis. But, with deeper mining, lean levels yielded to fat ones. Here and there they showed, within the same vein, an inverted distribution, chalcopyrite above and chalcocite below. To the miners&apos; astonishment, they carried chal-cocite, unaffected by cross faults, on an independent course to the depth of 2500 ft. The pattern of ore distribution, hitherto revealed only in fragments, was now appearing in perspective, and, in the depth of the chalcocite, was beginning to make Butte differ from all districts where the chalcocite is indubitably supergene. The idea of hypogene origin at length came into favor; by 1913, when Sales&apos; advocated this origin, the argument had become a powerful one. This argument rested on field evidence; but, already, there was beginning to emerge microscopic evidence not included in this argument. Especially pertinent was the proof that (1) the deep chalcocite lies in-mixed with bornite, often microscopic; (2) the deep chalcocite often replaces bornite; and (3) replacement of bornite by chalcocite is accomplished more easily than that of pyrite, enargite, or chalcopyrite. The microscopic evidence has been accumulating for ten years and it demands

Jan 1, 1924

By G. V. Woody, J. D. Price

Many producers of by-product coke have spent considerable time and given considerable thought to the use of a substitute for low-volatile coal as an admixture with high-volatile coking coal for charging high-temperature by-product coke ovens. Generally speaking, there are two principal reasons for this, one being occasioned by the lack, in certain localities, of low-volatile coal delivered at a cost sufficiently low to permit its use, and another being the desirability of finding a substitute product with a delivered cost lower than the cost of the low-volatile coal. It was for the first of these reasons that the Colorado Fuel and Iron Corporation was particularly interested in this subject. This paper deals with the experimental work and the results obtained by that company in producing and using low-temperature char. Overcoming Defects in Coke from Colorado Coals Colorado coking coals are all of the high-volatile type and were all laid down during the Cretaceous period, which makes them something like 80 million or so years younger, geologically, than eastern coals. They behave, when coked alone, something like the Pittsburgh-seam coals. They make a very brittle, highly cross-fractured, fingery coke of fair shatter value but quite low in resistance to abrasion. Mixed with a low-volatile coking coal such as Poca- hontas or certain Oklahoma coals, they make a coke that is equal to virtually any of the eastern cokes. The inferior quality of Colorado coke has long been recognized, and a considerable amount of time, effort and money has been spent upon investigations of means for improving its physical properties. While it has been found that some improvement in quality of coke can be secured by the adjustment and control of such variables as pulverization, moisture content, oven temperature and bulk density of charge, and through the addition of certain inert materials such as pulverized coke breeze, pitch, high-volatile noncoking or semicoking coal, the benefits so gained have been comparatively small. There are no low or medium-volatile coking coals available within a reasonable freight-cost distance. Therefore a substitute for low-vol-atile coal was developed through low-tem-perature carbonization—or, more correctly speaking, through the partial devolatiliza-tion—of high-volatile coals. The blending of this lower volatile char with the high-volatile coking coal distinctly improves the quality of coke made from Colorado coal. There is nothing especially new about this idea. In 1908 a Japanese patent was taken out by Kotaro Shimomura, whose claim was: The method of making a nonfingery coke out of bituminous coals, without using natural coals of low-volatile matter; according to which a certain coal is heated at a temperature between about 300°C. and about 600°C. so as to leave about 15 to 25 per cent volatile matter in the coal; this coal is mixed with the

Jan 1, 1944

INTRODUCTION IT is 10. years this summer since the first of the contributions which it has been my privilege to make to the working tools of the hydrometallurgist was set at work, but a full description of what has come to be known as "Dorr Machinery" has never been published in the Transactions of the Institute, and it has been suggested to me that an account of the same would prove of interest to members, although most of those engaged in cyaniding and concentration are probably familiar with it. The account which I shall give of the development of the machines must be recognized as being written from the viewpoint mainly of my own local experience and not from that of one who was familiar with the general metallurgical practice throughout the world. Most advances in any art are conceived before the time is ripe for their development and any .invention which comes into general use will usually be found to have been tried out in a crude way and abandoned more than once. If the early experimenter went as far as the Patent Office, his work may serve no other purpose than to prevent the issuance of the broadest patent to those who later may develop a commercial process. The cyanide process in the United States early in 1904 was mainly confined to the leaching of dry crushed ores, both coarse and fine, and sand treatment of tailings from concentration and amalgamation. In the Black&apos; hills some plants were crushing in cyanide solution, leaching sands and handling the slime by the well-known decantation process. Filter pressing, in use for some years in Australia,had been tried in several places in this country and the Moors process had been abandoned at Mercur after&apos; a short run, but was doing good work at the mill of Lindbergh, Dorr & Wilson, at Terry, and being installed at Bodie and the Liberty Bell. A general feeling, however, still existed that, slimes were to be avoided when possible, on account of the losses in treatment and the difficulty of making a good leaching product when they were present in large amounts, especially when the crushing was done in cyanide solution.

Jan 8, 1914

By J. D. Price, G. V. Woody

Many producers of by-product coke have spent considerable time and given considerable thought to the use of a substitute for low-volatile coal as an admixture with high-volatile coking coal for charging high-temperature by-product coke ovens. Generally speaking, there are two principal reasons for this, one being occasioned by the lack, in certain localities, of low-volatile coal delivered at a cost sufficiently low to permit its use, and another being the desirability of finding a substitute product with a delivered cost lower than the cost of the low-volatile coal. It was for the first of these reasons that the Colorado Fuel and Iron Corporation was particularly interested in this subject. This paper deals with the experimental work and the results obtained by that company in producing and using low-temperature char. Overcoming Defects in Coke from Colorado Coals Colorado coking coals are all of the high-volatile type and were all laid down during the Cretaceous period, which makes them something like 80 million or so years younger, geologically, than eastern coals. They behave, when coked alone, something like the Pittsburgh-seam coals. They make a very brittle, highly cross-fractured, fingery coke of fair shatter value but quite low in resistance to abrasion. Mixed with a low-volatile coking coal such as Poca- hontas or certain Oklahoma coals, they make a coke that is equal to virtually any of the eastern cokes. The inferior quality of Colorado coke has long been recognized, and a considerable amount of time, effort and money has been spent upon investigations of means for improving its physical properties. While it has been found that some improvement in quality of coke can be secured by the adjustment and control of such variables as pulverization, moisture content, oven temperature and bulk density of charge, and through the addition of certain inert materials such as pulverized coke breeze, pitch, high-volatile noncoking or semicoking coal, the benefits so gained have been comparatively small. There are no low or medium-volatile coking coals available within a reasonable freight-cost distance. Therefore a substitute for low-vol-atile coal was developed through low-tem-perature carbonization—or, more correctly speaking, through the partial devolatiliza-tion—of high-volatile coals. The blending of this lower volatile char with the high-volatile coking coal distinctly improves the quality of coke made from Colorado coal. There is nothing especially new about this idea. In 1908 a Japanese patent was taken out by Kotaro Shimomura, whose claim was: The method of making a nonfingery coke out of bituminous coals, without using natural coals of low-volatile matter; according to which a certain coal is heated at a temperature between about 300°C. and about 600°C. so as to leave about 15 to 25 per cent volatile matter in the coal; this coal is mixed with the

Jan 1, 1944

By J. J. Rutledge

On Sept. 4, 1914, Mine No. 1 of the Union Coal Co., Adamson, Oklahoma, suddenly caved, entombing thirteen miners whose bodies were never recovered. The seam of coal mined, the Lower Hartshorne, averaged 5 ft. in thickness and dipped at an angle varying from 22" to 30n. The strata overlying the coal seam were sandstones and shales. The mine was worked by the pillar-and-room method, the rooms being driven directly up the dip of the seam. All coal was blasted off the solid. Rooms were turned on short centers and room pillars were thin and irregular, as shown in Fig. 1. Fig. 2 is a cross-section of the form; showing the mine workings. Some cracks had been observed on the surface, it is said, at least a month before the squeeze occurred, but the collapse of the mine workings came very suddenly. As is usual when squeezes occur on such steep dips and the pillars fail, the crush progressed rapidly down the dip until it reached solid coal; there was a line of break, or draw, over in the solid coal. Several well-defined cracks appeared on the surface, after the mine had squeezed, but there was no appreciable subsidence of the surface, the weight seemed to be thrown entirely to the dip. About one year after the squeeze, and after the workings of the adjoining mine, NO. 4, had been retimbered and made safe, the writer inspected the tenth north (right) entry, or lift, off of No. 4 slope, which was below and fairly near the lowest caved portion of mine No. 1. The roof shale was composed of thin layers, which had been bent in somewhat the same manner as the leaves of a book having flexible covers are bent when the book is folded or rolled up in the hands. Though the mine workings are immediately beneath the streets and buildings of the mining town of Adamson, business was not disturbed by the squeeze, so far as any subsidence of the surface was concerned. No surface monuments were available and no elevations were taken, but the mine workings had been accurately surveyed and traversed, and the streets of the town overlying the mine workings had been carefully platted on the mine map, so that it was possible to locate accurately the cracks on the surface.

Jan 1, 1923

By Donald W. Scott

This paper describes the application of ore-dressing methods to the reclamation of milled frit from over-spray, or waste, porcelain enamel. Frit is the name given by enamelers to a granulated glass produced by the smelting and subsequent water quenching of various ingredients capable of forming a glass, usually including a compound to produce opacity. It is the major component of porcelain enamel, and normally commands a price ranging from 7 to 12 cents a pound. In the *preparation of a white enamel slip, usually 6 or 7 parts of clay, 2 parts of opacifier, small amounts of electrolytes, in some cases inorganic color stabilizeis and organic dyes, and 35 parts of water are added to 100 parts of frit; the mixture then is milled to a fineness of the order of 92 to 95 pct through a 200-mesh sieve. The frit forms the base of the enamel; the opacifier imparts opacity or reflectance; the clay suspends the frit while in slip form and serves as a binder in bisque form (dry and unfired); and the electrolytes control the workability. Spraying is used commercially, in many cases, to apply the finish coat of enamel to the ware, prior to drying and firing. In the spraying operation, only about 50 pct, by dry weight, of the enamel slip adheres to the surface of the ware, the remainder forms the over-spray. From 1/2 to 2/3 of the overspray goes up the flue where it is lost or recovered, depending on whether the plant is equipped with a dust-collecting installation; the coarser portion of the over-spray is collected in the spray booth. The former product is termed flue reclaim enamel, and the latter booth reclaim enamel. Although the spraying operation is done in specially constructed booths, which are partially or completely enclosed, it is extremely difficult to keep out contaminating dirt, which joins the reclaim. Some present-day large enameling plants use 20 tons of frit a day, of which 10 tons go into reclaim with a potential value of $1400 to $2400. When two-coat finish enamels were common, the reclaim was used satisfactorily for the undercoat, but the relatively recent advent of one-coat finish enamels prevented use of the reclaim because, even when blended with first-run enamels, it gave dirty finishes with poor gloss. It was thought that the pitting and specking encountered with reclaimed enamels were caused by the contaminating dirt, and that the poor gloss was caused, primarily, by the high clay content; more clay usually was added to give proper suspension properties to the slip when the reclaim was used. A clay content in excess of about 10 pct usually imparted refractoriness to porcelain enamels. Present-day one-coat porcelain enamels must combine high gloss and opacity with freedom from surface defects. Methods of beneficiating the over-spray,

Jan 1, 1948

By Donald W. Scott

This paper describes the application of ore-dressing methods to the reclamation of milled frit from over-spray, or waste, porcelain enamel. Frit is the name given by enamelers to a granulated glass produced by the smelting and subsequent water quenching of various ingredients capable of forming a glass, usually including a compound to produce opacity. It is the major component of porcelain enamel, and normally commands a price ranging from 7 to 12 cents a pound. In the *preparation of a white enamel slip, usually 6 or 7 parts of clay, 2 parts of opacifier, small amounts of electrolytes, in some cases inorganic color stabilizeis and organic dyes, and 35 parts of water are added to 100 parts of frit; the mixture then is milled to a fineness of the order of 92 to 95 pct through a 200-mesh sieve. The frit forms the base of the enamel; the opacifier imparts opacity or reflectance; the clay suspends the frit while in slip form and serves as a binder in bisque form (dry and unfired); and the electrolytes control the workability. Spraying is used commercially, in many cases, to apply the finish coat of enamel to the ware, prior to drying and firing. In the spraying operation, only about 50 pct, by dry weight, of the enamel slip adheres to the surface of the ware, the remainder forms the over-spray. From 1/2 to 2/3 of the overspray goes up the flue where it is lost or recovered, depending on whether the plant is equipped with a dust-collecting installation; the coarser portion of the over-spray is collected in the spray booth. The former product is termed flue reclaim enamel, and the latter booth reclaim enamel. Although the spraying operation is done in specially constructed booths, which are partially or completely enclosed, it is extremely difficult to keep out contaminating dirt, which joins the reclaim. Some present-day large enameling plants use 20 tons of frit a day, of which 10 tons go into reclaim with a potential value of $1400 to $2400. When two-coat finish enamels were common, the reclaim was used satisfactorily for the undercoat, but the relatively recent advent of one-coat finish enamels prevented use of the reclaim because, even when blended with first-run enamels, it gave dirty finishes with poor gloss. It was thought that the pitting and specking encountered with reclaimed enamels were caused by the contaminating dirt, and that the poor gloss was caused, primarily, by the high clay content; more clay usually was added to give proper suspension properties to the slip when the reclaim was used. A clay content in excess of about 10 pct usually imparted refractoriness to porcelain enamels. Present-day one-coat porcelain enamels must combine high gloss and opacity with freedom from surface defects. Methods of beneficiating the over-spray,

Jan 1, 1948