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J. S. UNGER, ? Pittsburgh, Pa. (written discussion ?).-Firebricks intended for, the same purpose, but supplied by different manufacturers, may be of entirely different clays, contain different proportions of flint, calcined and plastic clays; the particles may vary widely in size; the water used to make the brick will vary; the pressure in molding will vary, depend-ing on whether the brick is hand made or power pressed; and the degree of burning in the same kiln will differ. These variables affect the melting point and the strength of the brick when heated. An important property, of a firebrick is its ability to resist heat and, at the same time, weight or load without serious deformation. The soft-ening point and the melting point of a firebrick may be several hundred degrees apart, and two bricks may show considerable difference in their softening points, but the melting points may be approximately the same. Bricks are not usually employed at temperatures close to their melting points. If they must withstand very high temperatures, the firebrick is discarded and a brick of more refractory material is used. Under these conditions' it is doubtful whether the determination of the melting point of a brick has much practical value. If the determination of the melting point is necessary, the test should he made on a portion of the original brick and not on a specially prepared sample. A small triangular pyramid with a base about 1 1/2 in. and 3 in. high can be sawed from the corner of the brick with a thin-bladed car-borundum wheel, without injuring or destroying the size of particles, the bond, or degree of burning of the original brick. This specimen can then he compared with standard Seger cones or tested by any other method desired.

Jan 12, 1919

By H. C. Chao, Y. E. Smith, L. H. Van Vlack

ThE phase relationships for the MnO-MnS system have been investigated only in the eutectic region. wentrupl reported a eutectic at 1280°C (2345°F) with approximately 50 wt pct of each component, as based on the earlier work of Andrew, Maddocks, and Fowler.2 More recently silverman3 corrected these figures to 2275° ±10°F (1246°C) with 63 wt pct MnS and 37 pct MnO. Neither Wentrup nor Silverman investigated the solid-solution limits in this system. However, Wentrup did suggest with his phase diagram sketch that the maximum solubility of MnS in MnO is 10 wt pct, and the solubility of MnO in MnS is nearer 20 wt pct, Fig. 1. These figures have been utilized in subsequent publications without further verification.4 There had been evidence found in this laboratory that the above solid-solution figures were high. An investigation was therefore conducted using the following procedure. Samples containing MnO and MnS were contained in platinum foil, heated just above the eutectic temperature in a purified nitrogen at- mosphere, and quenched into distilled water. The MnO had been prepared by calcining reagent grade MnCO3 in nitrogen at 1400°C. Only MnO was detected in subsequent X-ray diffraction analyses. The MnS had been prepared by sulfur deoxidation of reagent grade MnSO4 according to the reaction: MnSO4 + S2 ? MnS + 2SO2 The details of the sulfide preparation procedure, which utilized atmospheric sulfur pressures at 950°C, are discussed elsewhere.5 The sulfur content of the sulfide was determined to be 36.8 * 0.2 pct, which matches the stoichiometric value of 36.9 pct. No evidence of either MnO or MnSO4 was detected microscopically or by X-ray diffraction. The single-phase combinations of MnO and MnS at the eutectic temperature indicate the limit of solid solution as shown in Fig. 2(a) and (c), and the revised phase diagram is shown in Fig. 2(d). The melting temperature for MnO is that provided by Glasser.6 The eutectic temperature of 1232° ± 5°C and eutectic composition of 64 wt pct MnS are in close agreement with Silverman's correction of Wentrup's work. The maximum solubility of MnO in MnS was determined to be 1.7 ± 0.2 wt pct. The maximum solubility of MnS in MnO was determined to be 1.8 ± 0.2 wt pct. These figures represent the lower limit for the presence of liquid at 1260°C and are significantly lower than the earlier estimated solid-solution figures. The authors wish to acknowledge the support of U.S. Steel's Edgar C. Bain Laboratory for Fundamental Research. The comments and critical suggestions of Drs. A. S. Keh, R. Rickett, and R. B. Snow are appreciated.

Jan 1, 1963

By AIME AIME

THE statements quoted below range widely over the field of contact between education and industry. 'Their sources are as indicated. True Education "Education must escape from its traditional warped and narrow views as to what constitutes life and preparation for life. It must train young men and women for vigorous, wholesome development of every important element of personality. It must build physical and mental health. For each student it must inform and discipline thinking in literature, in physical, bio- logical and social sciences, and in philosophy. It must awaken appreciation of beauty.

Jan 1, 1929

By J. T. Ryan

SAFETY practice or the elimination of accidents in our coal mines is specifically a problem of management. It cannot be delegated to any governmental agency except that the various coal-producing states do and should have some minimum safety standard laws. However, the legislative method of attempting to control mine accidents is ineffective because of the delay between the necessity and the action. It will always be impossible to keep our various state mining laws up to date; and when the law says you must do a certain thin there is a tendency to do this and no more. Unless the scheme for setting up state regulations is so flexible that when a new hazard develops it can be immediately and adequately covered and the whole responsibility for accident elimination placed undivided on the

Jan 1, 1937

By J. W. Stewart

That our American civilization will have extensive postwar problems in such fields as economics, unemployment, and social adjustment is now well understood by all readers of the press and listeners to the radio. But precious little is heard from these sources regarding the impact of the war on education, though education is one of the fields where the effect of the war is going to be felt most-for youth is fighting the war. Unquestionably, serious educational problems will ;rise in the postwar period, challenging the best efforts of our educators. Most acute will be the problems at the college level of education, for it is this age group that will have had its educational process most thoroughly disrupted. The return of these students to our college and university campuses wiI1 bring about a new set of conditions which we might as well try to foresee and begin to prepare for now. To begin with, the average returning college student who has had his education interrupted by war service will certainly be more mature in both years and mental outlook, and possibly married. As a result he will want to finish his college education as quickly as possible. His natural action will be to shop around among the various schools of the country to see where he can get the most credit for work he has done or thinks he has done. It is just possible that what might impolitely be termed "dark - market" schools may arise to cater to his needs. These schools will not think of them- selves in this light, of course, but will be conscious only of a keen sympathy for the veteran student and an urgent desire to help him solve his pressing problems. A considerable number of American colleges are going to be pretty well impoverished before this present war is ended and unless some professional organization takes it upon itself to place this possible situation under supervision and regulation, we may well suffer a serious setback to the

Jan 1, 1944

By Herbert Hoover

THE time has arrived in our national development when we must have- a definite national- program in the development of our great engineering problems. Our rail and water transport, our water supplies for irrigation, our reclamation, the provision of future' fuel resources, the development and distribution of electrical power, all 'cry out for some broad-visioned national guidance. We must create a national engineering sense of provision for the nation as a whole. If we are to develop this national sense of engineering wand its relations to our great human problems, it must receive the advocacy of such institutions as this. We, together with our sister engineering societies, represent the engineers of the United States. It is our duty as citizens to give voice to those critical matters of national policy which our daily contact with this, the fundamentally constructive profession, illuminates to us. Just as our medical associations voice the necessity of -safeguards to national health; as the bar associations of safeguards to our judiciary, so the engineers should exert themselves in our national engineering policies. We have none; but we need some, or the next generation will face a lower instead of a higher standard of living than ours.

Jan 1, 1920

The paragraphs quoted, regarding Mr. Hoover's appointment as chairman of the newly organized food board of the United States, are taken from the editorial page, of the New York Times for April 13: ?The country is fortunate in commanding the services of Herbert C. Hoover as Chairman of the newly established Food Board. This is n, problem of first importance. Few realize the extent to which American food stuffs will enter into the decision of the war, and it is doubtful if it has occurred to many minds as yet that we shall have to deny ourselves what we have regarded as necessaries in order to keep our European allies supplied. " Mr. Hoover is one of the leading mining engineers of the country. At the outbreak of the war he put his private affairs aside to become the head of the American Commission for Relief in Belgium. He has had an experience that perhaps no other man has ever had, covering the raising of money and the purchase and distribution of supplies on a large scale; He has been brought into close relations with the neutrals and the belligerents on both sides. By them all he is recognized is one of the best executives brought to the fore by the mar. Mr. Hoover is in a position now to place abilities and experience at the service of his country. He will come back with comparative data that will enable him to measure resources and deficiencies accurately. This appointment gives renewed assurance of our Government's grasp of the problems of war and its resolve to apply, business principles to their solution."

Jan 5, 1917

By H. M. St. John

THE melting department is the heart of the foundry. From it clean metal flows to the molding floor, in the right quantity, at the right time and at a sufficiently low cost-or, if not, the foundry fails to thrive. Since it is our purpose here to discuss present-day melting practice in the foundry, it may be well at the start to emphasize the wide differences in foundries and the conditions under which they must operate in order to reach the goal stated in the first paragraph. In every foundry, large or small, jobbing or captive, the same factors must be dealt with but they are of varying consequence and must be dealt with in varying ways in different foundries. Particularly in the nonferrous industry, there is so wide a variation in the composition of alloys used and in the character of castings made that no one type of furnace, nor any one method of operation, can be expected to produce the best results at all times. The present discussion will not attempt to include all nonferrous metals. It is intended to cover only the copper-base alloys in which copper is the dominant element, most of which are commonly known as brass or bronze. The discussion is further limited to the melting of these copper-base alloys for use in sand-casting foundries. Die-casting plants, the brass-rolling mills and certain other metal industries have melting problems peculiar to those industries, which will not be considered here. The following considerations are elemental in all foundries and are listed in what is believed to be the relative order of their present-day importance: I. The melting department must meet the foundry's requirement for dean, fluid metal, of specified composition and purity, at a temperature suitable for the work the foundry has in hand. This is the prime consideration in any foundry, at any time, anywhere. 2. Working conditions surrounding the melting furnaces and attending their use must be good. 3. The cost of molten metal at the mold must be as low as possible. 4. The operating characteristics of the furnaces must be sufficiently flexible, to meet normal variations in foundry requirements. 5. The operation and maintenance of the melting equipment must not require more skill and experience than is available in the particular foundry in question. METAL QUALITY It is not a function of the melting furnace to refine or improve the quality of the metal but simply to melt it without impairing its quality. Good practice requires, therefore, that care must be taken to supply the melting department with metal of inherently good quality, assured by specification or otherwise, having all the properties necessary to produce the castings desired. An alloy contains a number of primary elements, which must be present in definite proportions if the castings made from it are to have the desired properties. If the castings are made to a customer's specification, this will state the range within which these principal elements (for example, copper, tin, lead and zinc) are permitted to vary.

Jan 1, 1946

By James A. Barr, R. B. Burt, I. S. Tillotson

DISCUSSION Howard Howie (Knoxville, Term.)—The authors are to be congratulated on the presentation of a paper containing so much valuable information on the pipeline transportation of phosphate, as there is very little literature on the subject. The writer is especially interested in the paper, as he conceived the arrangement of the Akin and Godwin plants and was in charge of the design work and the engineering incident to their construction. The Akin and other phosphate deposits in the Tennessee phosphate area lie on beds of limestone that are very irregular. The limestone beds, after the phosphate matrix has been removed, are similar in appearance to land severely eroded by the action of water and denuded of top soil. Depressions in the limestone, called cutters, are irregular in depth with vertical or overhanging walls, having the general appearance of cracks in dried clay. They change abruptly in direction, width, and depth, and vary on the Akin tract from 1 to 25 ft in depth and from 1 to 50 ft in width. Pinnacles of limestone commonly occur in the cutters which appear, when exposed, like small clifflike islands in a river. Limestone floats also occur. The phosphate matrix fills the cutters and covers the uncuttered areas, the thickness of the cover varying continually and sometimes rather abruptly. It occurs generally as stratifications of phosphate rock and clay of varying thickness. The phosphate rock in the matrix varies in hardness and in percents of silica, lime, iron oxides, and fluorine, and the clay varies in toughness. In some places the deposit consists of narrow strata of rock almost devoid of clay streaks. In other nearby locations the clay will predominate. When it is excavated, the phosphate rock breaks into thin irregular lumps, locally known as plate rock. Limestone lumps are also excavated with the matrix. Akin plate rock is generally much softer than that occurring in other deposits in the area. Because of the above described physical and chemical variations of the excavated material, the resultant slurry varies in size distribution, specific gravity, and percent of slimes. When the rock is soft or when there is an increase of clay, the slime fraction is greatly increased as it passes through pumps and pipelines, resulting in reduced pipe friction. It is obvious that the longer the pipeline the greater the reduction of coarse fractions into fines, causing a decrease in pipe friction that cannot be accurately evaluated. The matrix is mined with a dragline that drops it into a hopper with a grid composed of 9-in. parallel bar spacings located above the hammer mill. The matrix on, and passing through the grid, is subject to the action of powerful sprays which wash it down to the hammer mill, together with any limestone lumps that are not removed before passing through the grid. The hammer mill reduces the feed to lumps of plate rock and clay, most of which will pass through the 8-in. pump suction. The mixture discharges into a pool containing the pump suction pipe. Water from a hydraulic nozzle moves the mixture to the pump suction intake. The pump, driven by a variable speed motor, is the same size as the pumps mentioned on p. 279. Provision is made to remove any lumps that lodge in a bend in the suction pipe in a manner similar to that used in the Florida phosphate fields. The hammer mill and pump units are mounted on wide steel skids so that they can be moved as the mining operation progresses. The discharge from the pump flows through an abrasion-resistant spiral welded steel pipe 8 1/4 in. actual inside diam, 8 in. nominal diam, for a maximum distance of 2200 ft, which is the limiting pumping distance for one pump. This pipeline, referred to hereafter as pipeline A, discharges into a ball mill without balls, which in turn discharges into a rotary screen attached to it that separates the slurried matrix into 11/4-in. oversize and undersize fractions. The oversize is returned to the mill for further reduction; the undersize is pumped to a Dorrco washer and then flows into a hydroseparator 160 ft in diam. In spite of the size reduction in the hammer mill and the blunging and washing of the slurry in its passage through the pump, pipeline, mill, and washer, the discharge to the hydroseparator frequently contains mud balls almost perfectly spherical. Sometimes the discharge from the 16,000-ft pipeline at Godwin contains mud balls the size of bird shot and smaller. This pipeline will be referred to subsequently as line B. Liquid caustic is added to the slurry at the Akin plant before its passage through the hydro-separator, which decreases the size of particles in the overflow by dispersion. In passing through pumps 1, 2, and 3 and pipeline B, the slime fraction in the underflow is increased by abrasion and blunging and also by continuing dispersive action of the caustic. The matrix for use in the experimental tests referred to on p. 279 was obtained from three small surface openings on the Akin tract that were made previous to the purchase of the tract by the Authority. Matrix used in the 2 and 4-in. experimental pipeline tests was taken from the three openings and proportioned to obtain a sufficient quantity that would be fairly representative of the average in the Akin deposits. Prospecting samples of matrix had been obtained from drill holes which showed no small variation in physical and chemical properties. Some of the physical variation is evident from the size distribution of solids in samples taken during the tests covering line B flows so thoroughly made by the Authority under the direction of Mr. Burt, see Table V, p. 280. Hydraulic gradients for a pipe of 8-in. diam were derived from the 2 and 4-in. pipeline tests using the so-called representative matrix as above described, and plotted on the profile of pipeline B. Gradients of other materials in slurry form passing through pipelines that bore some similiarity to the Akin matrix slurry were also plotted. After a study had been made of the hydraulic gradients plotted on the profile and the varying slurry flow that would probably occur during actual operation, three pumps were ordered, referred to as No. 1, 2, and 3 on p. 279. No. 1 and 2 pumps were installed and the third kept in reserve should the operation of 1 and 2 pumps prove satisfactory, since installation of the third pump would require an attendant, as well as the laying of 5400 ft of pipe to supply it with seal-water from the Akin plant. Subsequently, it was found desirable to install the third pump to maintain capacity when the slime fraction was low and the coarse fractions were large. Reference to Fig. 6 will show that the flow in B line goes upgrade in three locations. At the outlet at Godwin, the slurry flows between two 45" bends for an approximate distance of 18 ft to rise above the ground a sufficient height to discharge into a launder feeding the first classifier. This condition requires extra energy, which is taken care of by keeping the hydraulic gradient a sufficient distance above the high points. Although there are rather heavy upgrades in the line, the choking condition that might occur at the

Jan 1, 1953

By J. A. Barr, R. B. Burt, I. S. Tillotson

DISCUSSION Howard Howie (Knoxville, Term.)—The authors are to be congratulated on the presentation of a paper containing so much valuable information on the pipeline transportation of phosphate, as there is very little literature on the subject. The writer is especially interested in the paper, as he conceived the arrangement of the Akin and Godwin plants and was in charge of the design work and the engineering incident to their construction. The Akin and other phosphate deposits in the Tennessee phosphate area lie on beds of limestone that are very irregular. The limestone beds, after the phosphate matrix has been removed, are similar in appearance to land severely eroded by the action of water and denuded of top soil. Depressions in the limestone, called cutters, are irregular in depth with vertical or overhanging walls, having the general appearance of cracks in dried clay. They change abruptly in direction, width, and depth, and vary on the Akin tract from 1 to 25 ft in depth and from 1 to 50 ft in width. Pinnacles of limestone commonly occur in the cutters which appear, when exposed, like small clifflike islands in a river. Limestone floats also occur. The phosphate matrix fills the cutters and covers the uncuttered areas, the thickness of the cover varying continually and sometimes rather abruptly. It occurs generally as stratifications of phosphate rock and clay of varying thickness. The phosphate rock in the matrix varies in hardness and in percents of silica, lime, iron oxides, and fluorine, and the clay varies in toughness. In some places the deposit consists of narrow strata of rock almost devoid of clay streaks. In other nearby locations the clay will predominate. When it is excavated, the phosphate rock breaks into thin irregular lumps, locally known as plate rock. Limestone lumps are also excavated with the matrix. Akin plate rock is generally much softer than that occurring in other deposits in the area. Because of the above described physical and chemical variations of the excavated material, the resultant slurry varies in size distribution, specific gravity, and percent of slimes. When the rock is soft or when there is an increase of clay, the slime fraction is greatly increased as it passes through pumps and pipelines, resulting in reduced pipe friction. It is obvious that the longer the pipeline the greater the reduction of coarse fractions into fines, causing a decrease in pipe friction that cannot be accurately evaluated. The matrix is mined with a dragline that drops it into a hopper with a grid composed of 9-in. parallel bar spacings located above the hammer mill. The matrix on, and passing through the grid, is subject to the action of powerful sprays which wash it down to the hammer mill, together with any limestone lumps that are not removed before passing through the grid. The hammer mill reduces the feed to lumps of plate rock and clay, most of which will pass through the 8-in. pump suction. The mixture discharges into a pool containing the pump suction pipe. Water from a hydraulic nozzle moves the mixture to the pump suction intake. The pump, driven by a variable speed motor, is the same size as the pumps mentioned on p. 279. Provision is made to remove any lumps that lodge in a bend in the suction pipe in a manner similar to that used in the Florida phosphate fields. The hammer mill and pump units are mounted on wide steel skids so that they can be moved as the mining operation progresses. The discharge from the pump flows through an abrasion-resistant spiral welded steel pipe 81/4 in. actual inside diam, 8 in. nominal diam, for a maximum distance of 2200 ft, which is the limiting pumping distance for one pump. This pipeline, referred to hereafter as pipeline A, discharges into a ball mill without balls, which in turn discharges into a rotary screen attached to it that separates the slurried matrix into 11/4-in. oversize and undersize fractions. The oversize is returned to the mill for further reduction; the undersize is pumped to a Dorrco washer and then flows into a hydroseparator 160 ft in diam. In spite of the size reduction in the hammer mill and the blunging and washing of the slurry in its passage through the pump, pipeline, mill, and washer, the discharge to the hydroseparator frequently contains mud balls almost perfectly spherical. Sometimes the discharge from the 16,000-ft pipeline at Godwin contains mud balls the size of bird shot and smaller. This pipeline will be referred to subsequently as line B. Liquid caustic is added to the slurry at the Akin plant before its passage through the hydro-separator, which decreases the size of particles in the overflow by dispersion. In passing through pumps 1, 2, and 3 and pipeline B, the slime fraction in the underflow is increased by abrasion and blunging and also by continuing dispersive action of the caustic. The matrix for use in the experimental tests referred to on p. 279 was obtained from three small surface openings on the Akin tract that were made previous to the purchase of the tract by the Authority. Matrix used in the 2 and 4-in. experimental pipeline tests was taken from the three openings and proportioned to obtain a sufficient quantity that would be fairly representative of the average in the Akin deposits. Prospecting samples of matrix had been obtained from drill holes which showed no small variation in physical and chemical properties. Some of the physical variation is evident from the size distribution of solids in samples taken during the tests covering line B flows so thoroughly made by the Authority und'er the direction of Mr. Burt, see Table V, p. 280. Hydraulic gradients for a pipe of 8-in. diam were derived from the 2 and 4-in. pipeline tests using the so-called representative matrix as above described, and plotted on the profile of pipeline B. Gradients of other materials in slurry form passing through pipelines that bore some similiarity to the Akin matrix slurry were also plotted. After a study had been made of the hydraulic gradients plotted on the profile and the varying slurry flow that would probably occur during actual operation, three pumps were ordered, referred to as No. 1, 2, and 3 on p. 279. No. 1 and 2 pumps were installed and the third kept in reserve should the operation of 1 and 2 pumps prove satisfactory, since installation of the third pump would require an attendant, as well as the laying of 5400 ft of pipe to supply it with seal-water from the Akin plant. Subsequently, it was found desirable to install the third pump to maintain capacity when the slime fraction was low and the coarse fractions were large. Reference to Fig. 6 will show that the flow in B line goes upgrade in three locations. At the outlet at Godwin, the slurry flows between two 45" bends for an approximate distance of 18 ft to rise above the ground a sufficient height to discharge into a launder feeding the first classifier. This condition requires extra energy, which is taken care of by keeping the hydraulic gradient a sufficient distance above the high points. Although there are rather heavy upgrades in the line, the choking condition that might occur at the

Jan 1, 1953

By R. B. Burt, J. A. Barr, I. S. Tillotson

DISCUSSION Howard Howie (Knoxville, Term.)—The authors are to be congratulated on the presentation of a paper containing so much valuable information on the pipeline transportation of phosphate, as there is very little literature on the subject. The writer is especially interested in the paper, as he conceived the arrangement of the Akin and Godwin plants and was in charge of the design work and the engineering incident to their construction. The Akin and other phosphate deposits in the Tennessee phosphate area lie on beds of limestone that are very irregular. The limestone beds, after the phosphate matrix has been removed, are similar in appearance to land severely eroded by the action of water and denuded of top soil. Depressions in the limestone, called cutters, are irregular in depth with vertical or overhanging walls, having the general appearance of cracks in dried clay. They change abruptly in direction, width, and depth, and vary on the Akin tract from 1 to 25 ft in depth and from 1 to 50 ft in width. Pinnacles of limestone commonly occur in the cutters which appear, when exposed, like small clifflike islands in a river. Limestone floats also occur. The phosphate matrix fills the cutters and covers the uncuttered areas, the thickness of the cover varying continually and sometimes rather abruptly. It occurs generally as stratifications of phosphate rock and clay of varying thickness. The phosphate rock in the matrix varies in hardness and in percents of silica, lime, iron oxides, and fluorine, and the clay varies in toughness. In some places the deposit consists of narrow strata of rock almost devoid of clay streaks. In other nearby locations the clay will predominate. When it is excavated, the phosphate rock breaks into thin irregular lumps, locally known as plate rock. Limestone lumps are also excavated with the matrix. Akin plate rock is generally much softer than that occurring in other deposits in the area. Because of the above described physical and chemical variations of the excavated material, the resultant slurry varies in size distribution, specific gravity, and percent of slimes. When the rock is soft or when there is an increase of clay, the slime fraction is greatly increased as it passes through pumps and pipelines, resulting in reduced pipe friction. It is obvious that the longer the pipeline the greater the reduction of coarse fractions into fines, causing a decrease in pipe friction that cannot be accurately evaluated. The matrix is mined with a dragline that drops it into a hopper with a grid composed of 9-in. parallel bar spacings located above the hammer mill. The matrix on, and passing through the grid, is subject to the action of powerful sprays which wash it down to the hammer mill, together with any limestone lumps that are not removed before passing through the grid. The hammer mill reduces the feed to lumps of plate rock and clay, most of which will pass through the 8-in. pump suction. The mixture discharges into a pool containing the pump suction pipe. Water from a hydraulic nozzle moves the mixture to the pump suction intake. The pump, driven by a variable speed motor, is the same size as the pumps mentioned on p. 279. Provision is made to remove any lumps that lodge in a bend in the suction pipe in a manner similar to that used in the Florida phosphate fields. The hammer mill and pump units are mounted on wide steel skids so that they can be moved as the mining operation progresses. The discharge from the pump flows through an abrasion-resistant spiral welded steel pipe 81/4 in. actual inside diam, 8 in. nominal diam, for a maximum distance of 2200 ft, which is the limiting pumping distance for one pump. This pipeline, referred to hereafter as pipeline A, discharges into a ball mill without balls, which in turn discharges into a rotary screen attached to it that separates the slurried matrix into 11/4-in. oversize and undersize fractions. The oversize is returned to the mill for further reduction; the undersize is pumped to a Dorrco washer and then flows into a hydroseparator 160 ft in diam. In spite of the size reduction in the hammer mill and the blunging and washing of the slurry in its passage through the pump, pipeline, mill, and washer, the discharge to the hydroseparator frequently contains mud balls almost perfectly spherical. Sometimes the discharge from the 16,000-ft pipeline at Godwin contains mud balls the size of bird shot and smaller. This pipeline will be referred to subsequently as line B. Liquid caustic is added to the slurry at the Akin plant before its passage through the hydro-separator, which decreases the size of particles in the overflow by dispersion. In passing through pumps 1, 2, and 3 and pipeline B, the slime fraction in the underflow is increased by abrasion and blunging and also by continuing dispersive action of the caustic. The matrix for use in the experimental tests referred to on p. 279 was obtained from three small surface openings on the Akin tract that were made previous to the purchase of the tract by the Authority. Matrix used in the 2 and 4-in. experimental pipeline tests was taken from the three openings and proportioned to obtain a sufficient quantity that would be fairly representative of the average in the Akin deposits. Prospecting samples of matrix had been obtained from drill holes which showed no small variation in physical and chemical properties. Some of the physical variation is evident from the size distribution of solids in samples taken during the tests covering line B flows so thoroughly made by the Authority und'er the direction of Mr. Burt, see Table V, p. 280. Hydraulic gradients for a pipe of 8-in. diam were derived from the 2 and 4-in. pipeline tests using the so-called representative matrix as above described, and plotted on the profile of pipeline B. Gradients of other materials in slurry form passing through pipelines that bore some similiarity to the Akin matrix slurry were also plotted. After a study had been made of the hydraulic gradients plotted on the profile and the varying slurry flow that would probably occur during actual operation, three pumps were ordered, referred to as No. 1, 2, and 3 on p. 279. No. 1 and 2 pumps were installed and the third kept in reserve should the operation of 1 and 2 pumps prove satisfactory, since installation of the third pump would require an attendant, as well as the laying of 5400 ft of pipe to supply it with seal-water from the Akin plant. Subsequently, it was found desirable to install the third pump to maintain capacity when the slime fraction was low and the coarse fractions were large. Reference to Fig. 6 will show that the flow in B line goes upgrade in three locations. At the outlet at Godwin, the slurry flows between two 45" bends for an approximate distance of 18 ft to rise above the ground a sufficient height to discharge into a launder feeding the first classifier. This condition requires extra energy, which is taken care of by keeping the hydraulic gradient a sufficient distance above the high points. Although there are rather heavy upgrades in the line, the choking condition that might occur at the

Jan 1, 1953

By R. B. Burt, James A. Barr, I. S. Tillotson

DISCUSSION Howard Howie (Knoxville, Term.)—The authors are to be congratulated on the presentation of a paper containing so much valuable information on the pipeline transportation of phosphate, as there is very little literature on the subject. The writer is especially interested in the paper, as he conceived the arrangement of the Akin and Godwin plants and was in charge of the design work and the engineering incident to their construction. The Akin and other phosphate deposits in the Tennessee phosphate area lie on beds of limestone that are very irregular. The limestone beds, after the phosphate matrix has been removed, are similar in appearance to land severely eroded by the action of water and denuded of top soil. Depressions in the limestone, called cutters, are irregular in depth with vertical or overhanging walls, having the general appearance of cracks in dried clay. They change abruptly in direction, width, and depth, and vary on the Akin tract from 1 to 25 ft in depth and from 1 to 50 ft in width. Pinnacles of limestone commonly occur in the cutters which appear, when exposed, like small clifflike islands in a river. Limestone floats also occur. The phosphate matrix fills the cutters and covers the uncuttered areas, the thickness of the cover varying continually and sometimes rather abruptly. It occurs generally as stratifications of phosphate rock and clay of varying thickness. The phosphate rock in the matrix varies in hardness and in percents of silica, lime, iron oxides, and fluorine, and the clay varies in toughness. In some places the deposit consists of narrow strata of rock almost devoid of clay streaks. In other nearby locations the clay will predominate. When it is excavated, the phosphate rock breaks into thin irregular lumps, locally known as plate rock. Limestone lumps are also excavated with the matrix. Akin plate rock is generally much softer than that occurring in other deposits in the area. Because of the above described physical and chemical variations of the excavated material, the resultant slurry varies in size distribution, specific gravity, and percent of slimes. When the rock is soft or when there is an increase of clay, the slime fraction is greatly increased as it passes through pumps and pipelines, resulting in reduced pipe friction. It is obvious that the longer the pipeline the greater the reduction of coarse fractions into fines, causing a decrease in pipe friction that cannot be accurately evaluated. The matrix is mined with a dragline that drops it into a hopper with a grid composed of 9-in. parallel bar spacings located above the hammer mill. The matrix on, and passing through the grid, is subject to the action of powerful sprays which wash it down to the hammer mill, together with any limestone lumps that are not removed before passing through the grid. The hammer mill reduces the feed to lumps of plate rock and clay, most of which will pass through the 8-in. pump suction. The mixture discharges into a pool containing the pump suction pipe. Water from a hydraulic nozzle moves the mixture to the pump suction intake. The pump, driven by a variable speed motor, is the same size as the pumps mentioned on p. 279. Provision is made to remove any lumps that lodge in a bend in the suction pipe in a manner similar to that used in the Florida phosphate fields. The hammer mill and pump units are mounted on wide steel skids so that they can be moved as the mining operation progresses. The discharge from the pump flows through an abrasion-resistant spiral welded steel pipe 8 1/4 in. actual inside diam, 8 in. nominal diam, for a maximum distance of 2200 ft, which is the limiting pumping distance for one pump. This pipeline, referred to hereafter as pipeline A, discharges into a ball mill without balls, which in turn discharges into a rotary screen attached to it that separates the slurried matrix into 11/4-in. oversize and undersize fractions. The oversize is returned to the mill for further reduction; the undersize is pumped to a Dorrco washer and then flows into a hydroseparator 160 ft in diam. In spite of the size reduction in the hammer mill and the blunging and washing of the slurry in its passage through the pump, pipeline, mill, and washer, the discharge to the hydroseparator frequently contains mud balls almost perfectly spherical. Sometimes the discharge from the 16,000-ft pipeline at Godwin contains mud balls the size of bird shot and smaller. This pipeline will be referred to subsequently as line B. Liquid caustic is added to the slurry at the Akin plant before its passage through the hydro-separator, which decreases the size of particles in the overflow by dispersion. In passing through pumps 1, 2, and 3 and pipeline B, the slime fraction in the underflow is increased by abrasion and blunging and also by continuing dispersive action of the caustic. The matrix for use in the experimental tests referred to on p. 279 was obtained from three small surface openings on the Akin tract that were made previous to the purchase of the tract by the Authority. Matrix used in the 2 and 4-in. experimental pipeline tests was taken from the three openings and proportioned to obtain a sufficient quantity that would be fairly representative of the average in the Akin deposits. Prospecting samples of matrix had been obtained from drill holes which showed no small variation in physical and chemical properties. Some of the physical variation is evident from the size distribution of solids in samples taken during the tests covering line B flows so thoroughly made by the Authority under the direction of Mr. Burt, see Table V, p. 280. Hydraulic gradients for a pipe of 8-in. diam were derived from the 2 and 4-in. pipeline tests using the so-called representative matrix as above described, and plotted on the profile of pipeline B. Gradients of other materials in slurry form passing through pipelines that bore some similiarity to the Akin matrix slurry were also plotted. After a study had been made of the hydraulic gradients plotted on the profile and the varying slurry flow that would probably occur during actual operation, three pumps were ordered, referred to as No. 1, 2, and 3 on p. 279. No. 1 and 2 pumps were installed and the third kept in reserve should the operation of 1 and 2 pumps prove satisfactory, since installation of the third pump would require an attendant, as well as the laying of 5400 ft of pipe to supply it with seal-water from the Akin plant. Subsequently, it was found desirable to install the third pump to maintain capacity when the slime fraction was low and the coarse fractions were large. Reference to Fig. 6 will show that the flow in B line goes upgrade in three locations. At the outlet at Godwin, the slurry flows between two 45" bends for an approximate distance of 18 ft to rise above the ground a sufficient height to discharge into a launder feeding the first classifier. This condition requires extra energy, which is taken care of by keeping the hydraulic gradient a sufficient distance above the high points. Although there are rather heavy upgrades in the line, the choking condition that might occur at the

Jan 1, 1953

Theo. B. ComstocK, Los Angeles, Cal. (communication to the Secretary*):—Mr. Blake's recent paper upon this topic undoubtedly partly explains the rationale of a part of the known facts bearing upon discolorat'ion and encrustation of rocks. His quotation from Humboldt, with reference to certain South American examples, may be questioned in the light of further facts, which do not appear to bear out the great traveler's theory of causation. There is no available evidence that the waters of the tropical rivers referred to by Professor Blake contain dissolved organic matter in the varying proportions required to demonstrate Humboldt's guess, nor do the concomitant facts in any manner bear out the hypothesis that the blackening in one case and its absence in the other may, perhaps, be traced to differences in the chemical reactions of the respective waters. Careful consideration of Professor Blake's illustrations, in connection with numerous personal observations extending over widely-scattered areas, convinces me that elements of

Jan 1, 1905

By Philip D. Wilson

AS thin most important and vital component of an airplane aluminum hay rapidly become the heart and tome- of the war program. Its production ham increased amt will continue to increase, in comparison with its pre-war position further than that of any of lie other important critical metals except magnesium. Compared with the 1939 production of tons of primary ingot coming from four plants, all owned by the Aluminum Company of America the 1942 figures are more than three timer as large. Including, recoverable scrap and contracted ingot from Canada the 191,, supply of aluminum for the United States will be over siren times dial of 1939- A substantial part of this increase has been achieved during the past year as total production in 1941 was only some 307,500 tons. During 1942 six great new ingot plants sponsored and owned by the Government have come into production and three others are nearing completion.

Jan 1, 1943

By George H. K. Schenck, Peter G. Donald

There is an accelerating acceptance of change by management of cement companies. Diversity of response is noticeable in efforts across the country to reverse the downward trend in profits that brought margins in 1966 to the lowest point in 20 years. New concepts are emerging among managers as they seek to increase the efficiency in use of the basic corporate resources of men, capital and technology. The shift towards computerized control of cement manufacturing is making new gains as is diversification of cement companies into allied fields such as production and sale of natural and light- weight aggregates, crushed stone and concrete products. Increased interest in special products such as white cement and further moves overseas are also significant. Perhaps the most dramatic event of recent years occurred in Washington at hearings before the Federal Trade Commission where cement producers split on whether there should be FTC guidelines that would prevent ownership of ready-mixed concrete producers by cement companies.

Jan 4, 1967

By AIME AIME

0 N March 5, at Carnegie Hall, Cleveland, the Ohio Section held a joint meeting with the Cleveland Engineering Society, and the local sections of the American Chemical Society, American Society of Mechanical Engineers, and the American Society for Steel Treating. Prior to the meeting there was an informal dinner attended by 50 men. Then followed an address, "The Principles of Corrosion Protection," by Ulick R. Evans, the well-known British specialist in this problem. There were 266 present, presided over by Zay Jeffries, president of the American Society for Steel Treating and a member of the Cleveland Engineering Society. The address was well received and some discussion followed

Jan 1, 1929

By J. G. Early, F. V. Lenel, G. S. Ansell

The isothermal shrinkage rates of copper-powder compacts were determined in the temperature range from 760o to 1060oC. The rates for compacts fabricated from a pure spherical copper powder were compared, on the one hand, with those fabricated from a spherical powder containing a dispersion of aluminum oxide in the copper matrix and, on the other hand, with those fabricated from a pure copper powder having irregularly shaped particles. The irregular copper-powder compacts shrank much faster than the spherical copper-powder compacts and these, in turn, shrank faster than dispersion -strengthened copper -powder compacts. The experiments were run under a small external load. By varying this load, the stress dependence of the isothermal shrinkage rate could be measured for compacts from spherical-copper powders. This stress dependence was found to be approximately proportional to the 4th (dispersion-strengthened alloys) or 4.5th (pure metals) power of the stress. It is concluded that the material-trans port mechanism is due to dislocation climb rather than to Herring-Naharro creep. In this investigation the isothermal shrinkage rates of compacts made of copper powder with an average particle size of 70 g in the temperature range from 780o to 1060°C were studied. The aim of the investigation was to determine the mechanism of material transport responsible for the shrinkage of these compacts. Since the phenomenon observed in this investigation was shrinkage of compacts at high temperatures, it will be necessary to consider all the material-transport mechanisms possible in sintering. It is unlikely that evaporation and condensation, surface diffusion, or even volume diffusion of vacancies, in which surfaces of small radius of curvature are vacancy sources and those of larger radius of curvature vacancy sinks, will materially contribute to a sintering process involving shrinkage, i.e., one in which the centers of adjacent particles move towards each other. The two principal mechanisms which were considered were the so-called Nabarro-Herring mechanism and a plastic deformation mechanism by dislocation movement. Both of these mechanisms were originally conceived to explain creep, i.e., the plastic deformation of metals at elevated temperatures under a constant applied stress. The shrinking of metal-powder compacts which was studied in this investigation can be readily treated as a creep process. This means that the shrinkage rates observed are considered as creep rates under the influence of an applied stress. It is true that the stresses in sintering experiments are generally not constant but decrease continually with time, but, by considering creep rates or shrinkage rates over a relatively short time interval, the small changes in stress during this time interval can generally be neglected. Nabarro-Herring microcreep is a high-temperature deformation mechanism which is caused by a diffusional flow of vacancies from boundaries under a tensile stress towards those under a compres-sive stress. Herring1 has shown that in this type of microcreep the strain rate e is proportional to the applied stress and follows an equation of the form ma, aexp(-Q/RT) [l| where <j is applied stress, Q is the activation energy for self-diffusion, R is the gas constant, and T is the absolute temperature This type of creep can explain the shrinkage of a porous compact. The surface of the pores are subjected to the tensile stress of surface tension, while the grain boundaries are under a compressive stress also due to surface tension. Vacancies diffuse from the pore surface through the lattice to the grain boundaries, where they are eliminated. In order to maintain vacancy equilibrium at the pore surface the vacancies leaving the region of the pore surface are replenished from the volume of the pore, which means that the pores shrink.

Jan 1, 1964

By George C. Bravner

WITH the great expansion currently being made in the aluminum output of the United States, not only by the company that has heretofore been the sole producer but by a now organization in the field it is only natural to wonder to what degree the; ore reserves of the United States can contribute to the growing consumption. For the three-year period 1937-&apos;39 the U.S. Bureau of Mine&apos;s figures indicate that the annual domestic production of bauxite averaged about 370,000 long tons, compared with average, annual import of about 194,000 long tons. About 85 per cent of the imports came from Surinam, nearly all of which went into aluminum manufacture. Not all of the or -kipped from mines in the United States is used to make alumimun however as Bureau figures indicate that in these three years an average of only 48 per cent of the domestic ore shipment were so used the abrasive chemical and other industries taking respectively 27, 21, and 4 per cent of the output. The recent increase in the demand for bauxite has been of course in it use for aluminum manufacture. This as is well known is largely attributable to the world race for supremacy in

Jan 1, 1941

By W. C. MENDENHALL

THE problem of maintaining the mining industry is two-fold; finding new supplies in the face of increasing difficulties, and making such advances in the arts of extraction and preparation as to use supplies of lower grade. Progress in mining and reduction methods and in transportation makes ore today of that which was waste yesterday. These are the fields of the metallurgists and the transportation engineers. The geologists and mining engineers must work together on the problem of ore finding. As the old prospector fades from the scene, men with equal hardihood and patience and equal power to meet the physical obstacles which confront the seeker after ore, must take his place, armed with all that has been learned from human experience about the causes, the controlling conditions, the indications, and hiding places of the metals. Such a seeker is dealing with some of the most complex and obscure of natural phenomena. In nature&apos;s laboratory, tremendous forces are at work. Tempera-

Jan 1, 1926

By Myers, J. F.

The purpose of the mill tests reported herein, was to determine the relative power efficiency of fast and slow rod mill speeds on the ores of the Tennessee Copper Co. The tests were carried out at the lsabella Mill of the Tennessee Copper Co. under normal operating conditions. Every effort was made to keep the ore supply and other conditions constant, but it will be noted that some slight variation did occur. The open circuit 6 by 9 rod mill, and ore, used in these tests have been previously described.&apos; Four motor drive pinions were available and the tests were performed in the following manner: each pinion was used to drive the mill for a period of one week. Constant sampling prevailed during the test run, and a composite sample for each speed test was made. Realizing that some slight liner wear took place during the four-week test-run, and that some slight variation of the ore may have taken place, a second and then a third series of four-week test- runs were made with the four different pinions. The screen analysis of each of the thee-week run samples at the various speeds were composited and the results are shown in Table 1. The authors feel that the 12 weeks of operation consumed during these test-runs would represent fairly the effect of each mill speed. The data of line 37 show that within the error of sampling and plant operation, the tons of minus 65-mesh material generated per horsepower hour was the same at all four speeds.

Jan 1, 1949