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By J. F. Blandy

In October last, I was call upon to examine a copper deposit in the South Mountain, near the Pennsylvania and Maryland boundary. The specimens shown me contained oxides and carbonates with native copper, and were similar to some that had been described to me some years ago as existing at the Luray Gap in Virginia. An examination of Rogers's Report on the Geology of Pennsylvania, led me to expect to see his so-called "Primal Formation," such as exists throughout the southeastern district of the State. I was therefore much surprised on arriving at the summit of the Western Maryland Railroad to find myself on familiar ground. Instead of the "Primal" as I had known it in Southeastern Pennsylvania, I soon decided that the rocks were identical with the ('Lake Superior Copper Formation." My visit was unfortunately a short one, —part of two days, and in that time I had to pass over a good many miles,—but I saw sufficient to convince me that instead of the Lake Superior Copper Formation being a local geological feature, it would have to be considered as a widely extended series of rocks. I was unable to even approximately estimate the thickness either of the trap zone or other members, schists and slates, of the series. In an article on the Copper 'Range of Michigan, prepared by C. P. Williams and myself in 1862, and published. in vol. xxxiv of the American Journal of Arts and Sciences, we endeavored to divide that range into zones, according to the character of the traps. The limited nature of the explorations at that time made this work very imperfect. Subsequent explorations have confirmed my notes then

Jan 1, 1879

By Emory Kemler

The problem of determining the most desirable operating conditions of an oil-well pumping unit, the selection of the proper material and size of sucker rods, and the design of the pumping unit, requires that the sucker-rod loads be known with a reasonable degree of accuracy. In production practice, it is also desirable to know the effects of operating speeds and strokes on a plunger motion, as well as on the rod loads. For a particular well, data on rod loads can be obtained by measuring the load in sucker rods with a dynamometer. This method is not satisfactory because it does not permit the various factors to be investigated independently. It is also impossible to measure the plunger motion simultancously with rod motion under operating conditions. The mathematical solution is impractical because of the simplifications that have to be made to get a solution and the tremendous amount of numerical work that is necessary after such a simplified solution has been attained. This paper shows how analogies and models can be applied to the solution of these problems. The loads set up in a sucker-rod string during the ordinary pumping cycle are made up of the weight of the rods, force required to accelerate the rods, weight of the oil and force required to accelerate the oil on the upstroke, rod friction, stuffing-box friction, plunger friction, friction of the oil in the tubing and rods, arid friction loss through the valves. The problem of determining the sucker-rod load is further complicated by the fact that the long oil column and the sucker-rod column act as springs, which affect the transmission of the polished-rod motion. A further complication is the fact that the motion cannot be transmitted at a speed greater than that of the velocity of sound in the material, and this means that there will be a time lag in the transmission in the motion, as well as a modification of its magnitude and a phase displacement.

Jan 1, 1936

By Emory Kemler

The problem of determining the most desirable operating conditions of an oil-well pumping unit, the selection of the proper material and size of sucker rods, and the design of the pumping unit, requires that the sucker-rod loads be known with a reasonable degree of accuracy. In production practice, it is also desirable to know the effects of operating speeds and strokes on a plunger motion, as well as on the rod loads. For a particular well, data on rod loads can be obtained by measuring the load in sucker rods with a dynamometer. This method is not satisfactory because it does not permit the various factors to be investigated independently. It is also impossible to measure the plunger motion simultancously with rod motion under operating conditions. The mathematical solution is impractical because of the simplifications that have to be made to get a solution and the tremendous amount of numerical work that is necessary after such a simplified solution has been attained. This paper shows how analogies and models can be applied to the solution of these problems. The loads set up in a sucker-rod string during the ordinary pumping cycle are made up of the weight of the rods, force required to accelerate the rods, weight of the oil and force required to accelerate the oil on the upstroke, rod friction, stuffing-box friction, plunger friction, friction of the oil in the tubing and rods, arid friction loss through the valves. The problem of determining the sucker-rod load is further complicated by the fact that the long oil column and the sucker-rod column act as springs, which affect the transmission of the polished-rod motion. A further complication is the fact that the motion cannot be transmitted at a speed greater than that of the velocity of sound in the material, and this means that there will be a time lag in the transmission in the motion, as well as a modification of its magnitude and a phase displacement.

Jan 1, 1936

By Verne E. Hooker, Robert M. Becker

The evaluation of in-situ rock stresses from measurements of the change in diameter of a borehole that is stress-relieved by overcoring has become a common practice. Generally the stress evaluation has been based on isotropic relations whereas rock in varying degrees is aniso tropic. A plane elasticity solution fora circular hole along one axis of an orthotropic medium has been adapted to evaluation of in situ stress. The necessary elastic parameters for this evaluation may conveniently be obtained from static tests on the overcore in conjunction with a consistent orthotropic thick-wall cylinder solution. The method and equations for the laboratory and field evaluations are summarized and illustrated. The determination of in-situ rock stresses from boreholc deformation measurements has gained widespread acceptance. Hastl measured the change in diameter of a borehole that was stress-relieved by drilling a larger concentric core; this overcoring method has produced a major portion of the field data for recent stress evaluations in rock. These evaluations are based on the elastic properties of the rock, which are conveniently determined by testing the overcore.6-8 The stress evaluation and the overcore testing procedures generally assume isotropic relations whereas rock is anisotropic in varying degrees. Recently, an anisotropic plane stress solution was adapted for evaluation of in-situ stress9 and a related plane strain solution was developed for the testing of stress-relief core. 10 The present paper unifies the stress evaluation and overcore testing procedures for a general class of anisotropic rock. Equations are presented for calculating the state of stress in a plane normal to the borehole, and a consistent thick-wall cylinder solution is given for determining the necessary elastic properties. In addition, a complete example of stress evaluation from laboratory and field data is presented, and the order of error in computing the state of stress from isotropic relations is illustrated. Several limitations of the results should be emphasized. All results assume small linearly elastic deformations of a homogeneous medium. Rock characterized by orthotropic, transversely isotropic, and isotropic elasticity is considered; however, the anisotropic results assume a special relation among certain elastic constants in addition to geometric orientation with respect to a plane of elastic symmetry. For some stress determinations in rock, these may be severe limitations. On the other hand, the anisotropic evaluation procedure involves little additional effort and is much more flexible than the corresponding isotropic evaluation procedure. The collection of field data is identical. The laboratory determination of elastic parameters is no more difficult and time-consuming for the anisotropic than for the isotropic model. Only the calculations require some additional effort for the anisotropic evaluation, and this additional effort is eliminated by use of a small computer. The flexibility of the anisotropic procedure is greater because more than two independent elastic constants are available in fitting rock data. For the special relationship assumed among orthotropic constants, five independent elastic constants are available for the determination of in-situ secondary principal stresses as compared with two independent elastic constants for the isotropic model. Much of the material presented is either directly from the literature or adapted from the literature through superposition or the usual transformations. Consequently, only enough detail for clarity of presentation is included. RELATIONS FROM ANISOTROPIC ELASTICITY Materials that have three mutually orthogonal planes of elastic symmetry are called orthotropic. By directing the axes of the coordinates perpendicular to these planes, Hooke's law for an orthotropic solid 11 is

Jan 1, 1970

By Harry V. Warren

During the past few years the author has had an opportunity to examine a number of base-metal mines in the western United States, France and Spain. Nearly all of these mines produced some silver, and laboratory studies of the relationship between the silver and the various base-metal minerals in the ore have given some interesting and, it is to be hoped, enlightening facts. As this work was undertaken primarily to ascertain the amount of silver chemically associated with, not controlled by, the various base-metal minerals, the laborious and not always satisfactory method of picking out "pure" samples of each mineral from many localities was employed. However, the results obtained have justified the time that has been spent. Not only have the conclusions arrived at in different mining areas been in accordance with one another but in many instances they have afforded scientific support or explanations for much of the knowledge that operators in the various camps have acquired by practical experience. Although many of the conclusions are not new, many of the facts are, and the results, if they do nothing else, serve to confirm the findings of some of the other workers in this field, particularly the work of Nissen and Hoyt1 and of F. N. Guild2. Dr. S. G. Lasky3 has suggested a novel method for determining from a series of algebraic equations the amount of silver controlled by each of the base-metal minerals but I doubt very much whether his method can be justified, chiefly because there appear to be more variables to be considered than the few that appear in his equations. Typical Examples of Irregular Silver Distribution Combination Mine, New Mexico, U.S.A.—In this mine an examination of the assay plans either of the mine or of the average mill feed or products

Jan 1, 1935

W ill the location of the world's largest reserve of rutile, a titanium oxide mineral, in Sierra Leone, Africa, put an end to the worldwide shortage of this important mineral? According to officials of the Pittsburgh Plate Glass Co. and the British Titan Products Co. Ltd., the answer is yes. These two firms have formed Sherbro Minerals Ltd., a new company that will recover and refine the relatively rare mineral near Africa's West Coast. PPG owns 80% of Sherbro, and British Titan 20%. The rutile reserves of Sierra Leone have been reported to be larger, on a comparable grade ore basis, than existing proven reserves throughout the world. The African operation is on a strip of coastal

Jan 8, 1964

By S. E. Bretherton

(San Francisco Meeting, September, 1915) DURING the year 1878-79, Anton Eilers, who was then interested in the lead smelting and refining business near Salt Lake City, Utah, made a somewhat radical departure from the regular practice at that time, which was to use but little lime in the slag, with a high percentage of iron. Lime was not only a cheaper flux than iron, but it enabled the metallurgist to make a more siliceous slag, an economical advantage in smelting where the smelting companies had to purchase either iron or lime to neutralize the excess silica, and penalize the ore shippers accordingly. The larger amount of both lime and silica in the slag also made it of lighter specific gravity, and a better separation of the metals and mattes was secured. This change in the formation of slags for lead smelting was brought about by Anton Eilers, prior to the Leadville mining excitement of 1879. We must also give Mr. Eilers credit for the general introduction of the hollow water-cooled cast-iron jacket for the blast furnace. Again referring to the use of more lime and less iron in the formation of slags,. there is no doubt but that it prevents the formation of a great many so-called "sows" in the lead crucible, such as were made in the early history of lead smelting in the Rocky Mountains; these sows consisted of lead, iron, arsenic, sulphur, copper, and other metals, including gold and silver, mixed with unconsumed fuel, and often, after vain attempts to cut them up or melt them to a suitable size for handling, were buried in the slag clumps to get them out of-sight. Another advantage derived from the adoption of high-lime slags. when smelting ore containing arsenic is the production of less speiss (a by-product heavier than matte, resulting from careless operation of the furnace, the lead being driven out of the crucible and sows built up). This speiss, while usually not as rich in precious metals as matte made at the same time, is too valuable to be thrown away; but it is difficult to treat, and it was thrown away or piled on the slag clumps in the pioneer clays of lead smelting in this country.

Jan 8, 1915

By E. R. Parker, E. A. Smith

Metallurgists and engineers have always been interested in the mechanism of high-speed deformation because metals are rapidly deformed in various applica-tions and manufacturing processes. The deformation of metals by impact loads has recently engaged the attention of a number of investigators. Many of their results have not been disclosed but some of the published investigations1-8 have shown that the tensile strength, yield strength and elongation generally increase with increasing strain rate. The investigation reported herein is an attempt to determine the reason for this increase in strength and elongation. found to depend upon the strain rate. In the bars broken at high speeds, the slip bands appear to be more numerous. This might account for the higher strength as well as the greater elongation. Experimental Procedure Single crystals of copper (approximately 99.98 per cent) were made in graphite molds by the conventional method of lowering the mold out of the hot zone of a hydrogen furnace at a rate of one inch per hour. Solidification progressed from the bottom upward, forming a single crystal. The crystals were about 0.30 in. in diameter and 4 in. long. They were

Jan 1, 1944

By E. A. Smith, E. R. Parker

Metallurgists and engineers have always been interested in the mechanism of high-speed deformation because metals are rapidly deformed in various applica-tions and manufacturing processes. The deformation of metals by impact loads has recently engaged the attention of a number of investigators. Many of their results have not been disclosed but some of the published investigations1-8 have shown that the tensile strength, yield strength and elongation generally increase with increasing strain rate. The investigation reported herein is an attempt to determine the reason for this increase in strength and elongation. found to depend upon the strain rate. In the bars broken at high speeds, the slip bands appear to be more numerous. This might account for the higher strength as well as the greater elongation. Experimental Procedure Single crystals of copper (approximately 99.98 per cent) were made in graphite molds by the conventional method of lowering the mold out of the hot zone of a hydrogen furnace at a rate of one inch per hour. Solidification progressed from the bottom upward, forming a single crystal. The crystals were about 0.30 in. in diameter and 4 in. long. They were

Jan 1, 1944

By F. E. Wood

Since the earliest discoveries of oil in the Rocky Mountain area the spirit of cooperation in drilling and production programs has prevailed. There has scarcely been a field which has not been developed in an orderly manner through mutual agreement between competitive operators. An appreciable saving has resulted, as many unnecessary wells have been eliminated. We have unit operation plans and agreements which were developed at an early date. Rock River, found in 1918, has been a unit operation. One of the first prorate agreements ever attempted was made in Salt Creek in 1921. Teapot, first developed in 1922, has been a unit operation; the lessee, the Government, and the lessor, one operator. South Casper Creek, found in 1918, has been developed as a unit. Rex Lake, found in 1923, is a unit operation. The list might be extended materially but it serves to indicate that the Rocky Mountain region enjoyed the fruits of unit operation at an early date. It is concluded from this unitization study in the Rocky Mountain region that there is an appreciable saving in both development and production costs as well as the elimination of waste of a natural resource. Certainly, when unit operation conserves an irreplaceable natural resource as well as capital, any legal or political impediment to its successful development will be overcome. If one company supervises the operations in one field, it appears to be a unit operation. This may not be true if the lands involved have been leased from a great number of lessors. Royalty holders create a most intense competitive operation. The Rocky Mountain region has its full quota of such diversified interests. The original study calls for consideration of two types of fields, unit and near-unit operation. This Committee has felt that if an agreement of any character has brought about a saving it is an approach to unit operation. The fields have been classified into four types: 1. Unit Operation.—Any field whereby the competitive drilling-drainage feature is or will be absent in the development and operation of the pool.

Jan 1, 1930

LATEST estimates of Russian steel production for 1951 give rise to the belief that on at least one vital front, the Western bloc of nations has maintained a definite advantage. On the surface, we are outproducing the Eastern bloc by more than twice. The United Nations Economic Commission for Europe estimates Russian output at 31.30 million tons, a 15 pct increase over the previous year. Production for the entire Iron Curtain is figured at 40.93 million tons. Western Europe alone produced 17 pct. more steel during the same period. The figures are misleading in one sense. We have no precise idea of how much steel is being used for arms. The Western nations are still expending much of their production for consumer goods, and you cant throw washing machines in a shooting war. It is significant to note that Russian production is well, beyond estimates made by world authorities prior to the current international situation. INTERIOR Secretary Oscar L. Chapman warns that the United States must make use of the resources of other nations or face mineral impoverishment once the time of struggle is over. He pointed out that the present struggle between two ideologies can leave the United States in such a state as to preclude anything but political' victory-with an accomp anying economic loss that will be irreparable. Chapman scored the attitude whereby conservation programs are looked upon as a luxury, pointing out that the nation faces an ever increasing need for action on that front. He also announced that the Bureau of Mines doubled its facilities for producing pure zirconium during 1950-51 at the request of the Atomic Energy Commission. Zirconium may be an important structural metal for atomic power devices. The Interior Secretary also said that the AEC has provided the Bureau with funds for the study of radioactive minerals and to help test and evaluate about 9000 ore samples believed to contain uranium.

Jan 1, 1952

ARTICLE I NAME AND OBJECT SEC. 1. This Institute is incorporated under the Membership Corporations law of the State of New York; its corporate name is American Institute of Mining and Metallurgical Engineers, Inc.; and its objects are such as are stated in its Certificate of Incorporation. ARTICLE II- MEMBERS SEC. 1. The membership of the Institute shall comprise four classes, namely: 1. Members; 2. Honorary Members; 3. Associates; 4. Junior Associates. All members shall be equally entitled to the privileges of membership, excepting that Honorary Members, Junior Associates, and Members and Associates whose residences shall be outside of the United States, Mexico, and Canada shall not e entitled to vote. Members and Associates residing within the United States of America, Mexico, and Canada, and not in arrears for dues, shall be entitled to vote in person at the meetings of the Institute, or, as hereinafter provided for, by letter ballot. SEC. 2. Members shall comprise all those persons who on the third Monday of February, 1918, were members of the Institute, and in addition thereto, all those thereafter elected or transferred into the class of Members. A person to be eligible for election or transfer into the class of Members must be at least 27 years of age and must have had at least six years' employment in the practice of-engineering, mining, geology, metallurgy or chemistry, during at least three years of which he must have held positions of responsibility in one or more of these fields. Graduation from the scientific course of a college, approved by the Committee on Membership, shall be considered equivalent to two years' employment, as required in the previous sentence. Employment as a teacher of engineering, mining, geology, metallurgy or chemistry, if in direct charge, may be considered a position of responsibility as specified in the second paragraph. Persons employed in research or any scientific literary work or in teaching in the scientific departments of colleges, approved by the Committee on Membership, who at the same time are engaged in consulting or in the active practice of mining, geology, or metallurgy, shall be entitled to consider the time so spent in active practice as equivalent to an equal length of time of employment in positions of responsibility, . provided the work done or the positions held seem to the Committee on Membership to warrant the. equivalency. The requirement of three years' employment in positions of responsibility may be waived by the Committee on Membership in the case of persons who have done notable original work in mining,. geology, or metallurgy, or have won distinction by

Jan 1, 1925

By Donald E. Scheck, Da-Rong Chou

The application of geostatistics to coal reserve analysis is discussed. One problem in particular, the selection of the optimum locations for exploratory drill holes, is considered in detail. A new interactive program to help the geologist determine the best locations is described and applied to a specific property. The steps in the process are described and then illustrated using a mine's actual data. First, a variogram is selected based on graphical displayed information from the known sample data. Kriging estimates are made for the region of interest and the blocks within the region. The location of future exploratory drill holes is selected based on the criterion of minimizing the region estimation variance for a given number of exploratory holes. The least number of exploratory holes required to meet a specified upper limit on the regional variance is also determined. The computer generated recommendations for the exploratory drill holes are compared to a manually prepared drilling plan. The post- drilling analysis of the results is compared to the predicted values.

Jan 1, 1983

By Douglass D. Donald

The New Jersey Zinc Co. successfully holed through a 2 ½ -mile haulage tunnel connecting its new Ivanhoe shaft with the Van Mater Shaft at Austinville, Va. This 8 x 10-ft cross-section tunnel was driven from both ends and met at a point approximately a mile from one shaft and a mile and a half from the other. In order to make certain that the faces met accurately on line and grade it was necessary to refine conventional mine surveying practices. The mines that are serviced by these shafts are located in the southwestern part of Virginia approximately midway between Roanoke and Bristol at the west foot of the Blue Ridge. While the presence of lead-zinc sulfide ores has been known in this area for more than 200 years, it was in 1902 that New Jersey Zinc Co. acquired the Austinville property, which has been in constant operation since that time. About ten years ago the company undertook an extensive diamond drilling program at Ivanhoe several miles to the southwest. This program was successful in locating sufficient ore to justify the purchase of a number of the properties in this area and plans were made to develop the new orebodies. The discovery of this ore as well as substantial additional reserves at Austinville resulted in a decision by the company to increase its daily milling capacity to 3000 tons, of which about 1000 tons would be supplied from the Ivanhoe mine.

Jan 9, 1958

By E. Alan Haley

Accurate and economic control of line and grade on long tunnels, large structures, excavations and waterways has been a problem to surveyors and engineers for decades. The conventional method of surveying, incorporating a level, transit and a number of surveying technicians, has proven to be a very expensive and time-consuming operation. Now, however, engineers have adapted the laser to help ease the problems of surveying, at the same time increasing the efficiency of such operations. The laser, which projects a continuous, narrow red beam of brilliant light, provides a constant alignment reference that does not interfere with personnel or equipment. A complete laser alignment system, specifically designed for and suited to a variety of mining and tunneling operations, has been developed by the Perkin-Elmer Corp. The engineering significance of this development can be fully realized when it is noted that, aside from potentially tremendous economic advantages in terms of labor savings, the laser beam provides a system of alignment that is at least ten times more accurate than presently used optical systems. The new laser system provides accuracies within 10 microinches per foot (1 x 10-5in.) when used with an accessory centering detector. In one of its first field trials, the laser was used for alignment of a two-mile tunnel which showed a total deviation of less than 5/8 in.

Jan 4, 1968

By C. W. Crispell

THE four nomograms presented in this article were designed to simplify and make more, rapid the calculations connected with the compression and transmission of air. The formulae involved are rather complicated, but the graphic solutions are simple; their use requires an ability to follow explicit directions and to interpolate values on a logarithmic scale. ? For the sake of convenience, the nomograms will be divided into two classes, and the purpose and accuracy of each will be discussed. Compression It is frequently desirable to determine the horsepower necessary to compress a given amount of free air from atmospheric pressure to a certain final pressure. The nomograms in Figs. 1 and 2 present a rapid method of calculating the horsepower required to compress 1 cu. ft. of free air per minute by single or two-stage compression. The general formula for the horsepower required to compress air adiabatically is: HP = S X 144/33,000 PVn/(n-1) [(P'/P) n-1/Sn -1] (1) where: P = absolute atmospheric pressure at compressor, in pounds per square inch. P' = final absolute pressure of compressed air, in pounds per square inch. V = volume of free air compressed per minute, in cubic feet. S = number of stages. n = exponent of the compression curve.

Jan 6, 1917

By E. J. Freeh, W. E. Horst, R. C. Kellner

A technique useful in the important area of process-model building is described. The procedure is illustrated in the development of a mathematical model to describe the unsteady-state process of batch ball-mill grinding. The influence of certain assumptions relative to model structure are quantitatively evaluated and reviewed.

Jan 1, 1969

By Henry A. Ley

Oklahoma produced about 40,000,000 bbl. less crude oil in 1930 than it did in 1929, but developed the largest initial production from current well completions ever recorded in its history. The output of this year would have exceeded all previous years had it not been for state-wide production curtailment. The record initial production of 5,911,982 bbl. from new oil wells completed during the year is accounted for entirely by the rapid development of the Oklahoma City field. Completions declined to the lowest levels since 1909, as a result of a marked reduction in number of dry holes incident to reduced wildcat exploration. Leasing was most active in western and northern counties of the state west of Oklahoma City, but on a much smaller scale than in the preceding year. Geological and geophysical surveys were likewise most active in this western territory. The urge to deeper objectives resulted in the discovery of oil on the Cement fold. Changing economic conditions have created a distress situation among the marginal operators in northeastern localities of the state. Elsewhere in the state production records and successful exploitation of new supplies have been eclipsed by a new social concept of the industry in accord with natural economic developments. Many of the producers of crude oil have organized for a voluntary stabilization of the industry by regulating the output of wells. To enforce their measures these operators have sought for and secured the support of the state. Consequently, the current position of the crude-oil producer is not unlike that of the natural-gas producer—withdrawal of supplies in accordance with market needs. And while the industry as a whole is artificially stabilized by these measures individual operators and some of the integrated concerns suffer hardships. Oil Developments and Production The early operations in Oklahoma were confined to northeastern and eastern localities, beginning in 1885. The first commercial oil wells were completed in 1894, near Chelsea in Craig County, from Cherokee sands in the lower portion of the Pennsylvanian section. Scattered

Jan 1, 1931

By Arthur Hixson

ALTHOUGH a few engineers have recognized the problem of the mechanism of filtration it has never been studied in a quantitative way. A background for a better understanding will be afforded by a survey of certain fundamental principles of filtration. In recent years, authorities have become practically unanimous in saying that the actual filtering should be done, not by the cloth itself, but by a layer of solid particles deposited upon it. Thus, a cloth may be used in which the openings are considerably larger than the particles to be filtered, provided that groups of particles form an arch or bridge over each opening. This can be accomplished if the initial pressure is so low that the arch will not be broken while it is still thin. According to Wright,1 the chief advantage of this method of filtration is that the open-weave cloth does not become clogged as easily as does one of closer weave, where the fine particles often work their way into the interior of the cloth and become caught there. If the character of the material to be filtered is such that it will not form a good film, then it becomes advantageous to use "filter aids" for pre-coating the cloth with a desirable layer of solids, and the coating need be only of a very slight thickness for good results. Until the film is formed, the first runnings of the filtrate may be cloudy, often necessitating refiltering this portion. A factor which has considerable effect on the performance of filters is the concentration of solids in the pulp. According to Wright, a. high concentration of solids gives a porous cake, since the flow is then slower than with- a thin pulp. The porosity of the cake is also affected by the pressure: a high initial pressure tends to compact the cake, and the same effect results from fluctuations of pressure. In his studies of the relation between pore size and particle size, Hatschek2 observed that the particles in a pulp tend to arrange themselves with maximum cross-section parallel to the direction of flow and that this is more marked at the higher velocities. Thus, at high pressure and high velocity, a certain pulp

Jan 2, 1926

By J. B. Wagstaff

The raceway in front of the tuyere of the blast furnace has been studied quantitatively and a correlation obtained for the penetrastudiedtion of the blast. Some evidence is presented for the height and width of the raceway which suggests that all the raceways of a ffurnace overlap. The size of the coke in this zone has been measfurnaceoverlap.ured photographically during normal operation and results are given for the various areas. IN an earlier paper,' it was shown that a raceway exists opposite each tuyere of a blast furnace. This raceway is formed by the jet effect of the air emerging from the tuyere and consists essentially of a turbulence in which coke particles are recir-culated at high speed. Its presence was deduced originally from observations on movies taken with a high-speed camera through the tuyeres of various furnaces and was confirmed by experiments made on a model. In the model described,' this raceway was shown as operating in a vertical plane only, although there was a suggestion in the motion-picture film exhibited at that time that the raceway was three dimensional, unless artificially restricted. There was also some doubt then about the factors influencing its size. This paper describes the next steps in the investigation. Since the size of the raceway is obviously of importance in the operation of the furnace, it seemed worth while to study the subject more carefully. It is probably in this region that about half the coke in the furnace is consumed, so that the movement of the stock column may well be controlled by raceway behavior. Furthermore, there is some evidence to suggest that the coke is packed densely in the center of the furnace to form the "dead man" and more loosely above the raceway. It is therefore probable that the bulk of the gases passing up the stack flow from the top surface of this raceway. Clearly then, a knowledge of this critical zone is of interest to the blast furnace operator, and the first half of this report is devoted to a quantitative discussion of the subject. A further topic of interest among operators is the degree of breakdown of coke in the furnace, with which is inseparably linked the importance of a strong coke. Indeed, the whole question of the optimum size and type of coke may be as dependent on the condition of the coke in the bottom of the blast furnace as at the top. Attempts have been made from time to time to obtain samples of coke from the tuyeres and other furnace openings but they all suffer from the fact that the coke is filled to a varying degree with metal and slag and is probably broken up by the very act of taking the sample. It has proved difficult to make any reliable studies of coke size by these methods. However, it did seem possible to use the highspeed movies mentioned earlier1 to estimate the size of the coke. These movies provide an accurate record of individual coke particles so that, in theory at least, it should be possible to measure the size of the particles one by one and to obtain, for the first time, information on the coke being blown around the raceway under actual operating conditions while the furnace is performing normally. Such a study has been made and is discussed in the second half of this paper. The results obtained enabled the blast furnace data to be correlated with the model results given in the first half. Raceway Size In order to make a quantitative study of the size of the raceway it was necessary to devise some apparatus of laboratory scale, which could be handled quickly and easily. This focused attention on models, which in turn means that the laws of similarity governing this particular process must be ascertained. Method of Procedure: Since the work was to be carried out on a smaller scale than the blast furnace, the linear dimensions of the model became unimportant provided that the scale was known; it is only important to insure that the container does not affect the raceway being observed. The studies therefore were carried out in a glass-sided box, 11 in. high x 7 in. wide x 3 in. deep, using air jets ranging

Jan 1, 1954