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By W. H. Andrews

The constantly increasing consumption of Portland cement in the State makes the above subject of particular interest at this time. The increasing demand is due to the rapid settling of the country and the fact that new uses are being found frequently for the above named commercial article. The industry is one that is bound to grow as the population increases, and this being the case it may be well at this time to consider briefly the matter of the chemical and physical composition of proper raw materials. A cement mixture is one that contains approximately 75 per cent, carbonate of lime, 15 per cent. silica, and 5 to 7 per cent. alumina and iron oxides; the other elements being magnesium carbonate and mall quantities of the rarer elements generally associated with limestone deposits. It can be readily seen from the above composition that it is possible to build up this mixture from a number of different materials. First.—A rock high in carbonate of lime can be mixed with clay or shale in such proportions as to bring about the desired composition ; the chief difficulty in the building up of such a mixture is that it is hard to find a clay or shale in which the silica-alumina ratio lies between 4 to 1 and 3 to 1 and at the same time shows physical characteristics which will make certain its adaptability to the practical manufacture of Portland cement. Very often clays or shales are found which are right chemically but contain large quantities of grit or free silica. Such clays or shale must be ground to extreme fineness in the mixture in order to make the silica and alumina combine with the lime when the mixture is burned. On the other hand, clays or hales are often found that have the proper physical characteristics but in which the amount of alumina is too great. Second.—A mixture can be built up of different limestones some of which run above the 75 per cent. requirement and others below;

Jan 1, 1914

By Clyde Williams

A MAN who is a first-class metallurgist, engineer, and scientist and an outstanding organizer, administrator, and executive and who, at the same time, has an innate ability to "make friends and influence people" everywhere he goes is an exceptional personality at any time. And if such an individual can retain this combination of virtues during a great war despite the fact that the Government loaded him with enough work and responsibility for three such men. he is a most exceptional personality. And if he can keep his head and maintain an unfailing sense of humor during the trying war years and, while dealing with hundreds of jittery metallurgists and metalworkers, with Army and Navy brass, and with red-tape-entangled war agencies by the dozen, he is a rare personality indeed. Such a man is Clyde Williams, director of Battelle Memorial Institute. who will be President of AIME in 1947. The Institute is fortunate in having him as its mentor during what may be a critical and important year.

Jan 1, 1947

By William E. Ford, Edward Salisbury Dana

506. Scope of Descriptive Mineralogy. - It is the province of Descriptive Mineralogy to describe each mineral species, as regards: (1) form and structure; (2) physical characters; (3) chemical composition including blowpipe and chemical tests; (4) occurrence in nature with reference to geo- graphical distribution and association with other species; also in connection with the above to show how it may be distinguished from other species. Further, it should classify mineral species into more or less comprehensive groups according to those characters regarded as most essential. Other points which may or may not be included are the investigation of the methods of origin of minerals; the changes that they undergo in nature and the results of such alteration; also the methods by which the same compounds may be made in the laboratory; finally, the uses of minerals as ores, for ornament and in the arts.

Jan 1, 1922

By Koichi Kashida, Mayumi Someno, Kazuhiro Goto

The present work has two objectives: first to develop an experimental method which would give some new information on the micromechanism of the reduction of oxides by gases at elevated temperature; second to clari,fy the intermediate phases of the W-0 system, formed during the reduction. A Galvanic cell with the solid electrolyte , ZrO2 . CaO, was imbedded in powders of W03, CuO, or Fe20s with two measuring electvodes and with a reference electrode. The change of the intraparticle gas composition was measured at An oxygen concentration cell consists of two electrodes separated by an electrolyte through which the transference of electrical charge is accomplished predominantly by the migration of oxygen ions. Many works have been reported on the oxygen con- 600" to loo@ C during the reduction by the gas mixture of hydrogen and argon. The intraparticle gas composition changes stepwise with time. The electromotive force of such temporary interruption corresponds to the equilibrium electromotive force of two solid phases formed during the reduction. The intermediate phases of W-0 system, which are formed in a large quantity during the reduction by hydrogen, are W0 2 W02.72 and WOz. The micromechanism of the reduction of oxides by gases is discussed. centration cells with the solid electrolyte of solid solution of zirconia and lime, since Kuikkola and wagnerl demonstrated the possibility of determination of standard free energy of formation of oxides by an electromotive-force method with the Galvanic cell. One of the present authors (K.G.) and his coworkers have applied the cells with the solid electrolyte of zirconia and lime to the following measurements:

Jan 1, 1969

By J. F. Myers

THE Tennessee Copper Company's operations are in the Ducktown Basin, in the extreme southeast corner of Tennessee. The ore is of the heavy sulphide type, the predominating sulphides being pyrite, pyr-rhotite, chalcopyrite and sphalerite. The gangue is a micaceous schist, with varying amounts of free quartz. The mining operation develops two classes of ore, each of which is concentrated by the flotation process in separate mills. Table 1 shows a typical analysis of the ore treated in each mill. TABLE 1.-Typical Analysis of Ore Treated Composition, Per Cent Mill Tons Capacity Cu Fe S Zn London 1,350 1.41 28.4 20.2 1.10 Isabella 850 0.69 44.7 31.6 0.31 LONDON MILL The London mill was built in 1922, with a capacity of 400 tons per day. This was gradually increased to 600 tons by 1926, to 900 tons in 1928, and to 1350 tons in 1938. Fig. 1 shows the crushing and grinding flowsheet in 1928, when the capacity was 900 tons; Fig. 2, the crushing and grinding flowsheet that was developed by 1938, for the treatment of 1350 tons per day. A comparison of these flowsheets reveals that this increase in tonnage, with a subsequent improved operation, was accom-plished with identically the same major equipment. Improving a concentrator's capacity, metallurgical results, and costs as time goes by is a commonplace practice, and is accomplished in various ways, depending upon the local conditions. The reason for presenting the data of how this was accomplished in the mills of the Tennessee Copper Co. is that a fast-running rod mill plays such an interesting role

Jan 1, 1940

By A. H. Geisler, R. F. Mehl, C. S. Barrett

The mechanism by which the supersaturated solid solution of 20 per cent silver in aluminum decomposes has been reported in two previous publications.1'2 The analysis of streaks in Laue photograms showed that thin platelike particles (the so-called Guinier-Preston aggregates) form upon matrix planes in the early state of decomposition.1 The size of these particles is larger, the higher the temperature at which they form in accordance with nucleation theory;³ at all temperatures they increase in size with aging.2 When they have grown thick enough to afford three-dimensional diffraction, powder X-ray photograms show that the structure is not that of the equilibrium precipitate but that of a transition lattice . Sincc this is also platelike in shape and also lies upon the (III) matrix planes with the [IIO] direction in the matrix parallel to the [II.O] direction in it seems likely that the original platelet particles are merely in an early stage of formation, and thus finely dispersed. The atomic spacing and pattern on the (00.1) plane in y' are identical with those on the (111) matrix plane to which it lies parallel, and since comparable directions in the two planes are parallel, the lattices are thus coherent at the interface; an analogous coherence has been found in aluminum-copper alloys.3 The structures y' and y are both close-packed hexagonal and are oriented alike; they differ only in interatomic distances. Consequently, y' is regarded as y strained from its ordinary dimensions by the lattice coherency between it and the matrix.2 The lattice movements that transform the matrix to the equilibrium precipitate appear to be very simple.2 The mechanism of precipitation in this system is simpler and is more precisely known than that in any other system hence the system should be a profitable one for the difficult task of correlating property changes with structural alterations. The present report provides additional studies on powder X-ray diffraction from alloys of 10 per cent, 20 per cent and 30 per cent Ag, and presents the correlation of crystallographic changes with changes in microstructurc, Brinell hardness and electrical resistivity of the three alloys. Preparation of Samples and Experimental Procedure The preparation of the 20.2 per cent Ag alloy has been described2 Alloys containing 9.9 and 29.7 per cent Ag were prepared from 99.97 per cent A1 and 99.99+ per cent Ag using a similar procedure. Rolled

Jan 1, 1943

By R. F. Mehl, C. S. Barrett, A. H. Geisler

The mechanism by which the supersaturated solid solution of 20 per cent silver in aluminum decomposes has been reported in two previous publications.1'2 The analysis of streaks in Laue photograms showed that thin platelike particles (the so-called Guinier-Preston aggregates) form upon matrix planes in the early state of decomposition.1 The size of these particles is larger, the higher the temperature at which they form in accordance with nucleation theory;³ at all temperatures they increase in size with aging.2 When they have grown thick enough to afford three-dimensional diffraction, powder X-ray photograms show that the structure is not that of the equilibrium precipitate but that of a transition lattice . Sincc this is also platelike in shape and also lies upon the (III) matrix planes with the [IIO] direction in the matrix parallel to the [II.O] direction in it seems likely that the original platelet particles are merely in an early stage of formation, and thus finely dispersed. The atomic spacing and pattern on the (00.1) plane in y' are identical with those on the (111) matrix plane to which it lies parallel, and since comparable directions in the two planes are parallel, the lattices are thus coherent at the interface; an analogous coherence has been found in aluminum-copper alloys.3 The structures y' and y are both close-packed hexagonal and are oriented alike; they differ only in interatomic distances. Consequently, y' is regarded as y strained from its ordinary dimensions by the lattice coherency between it and the matrix.2 The lattice movements that transform the matrix to the equilibrium precipitate appear to be very simple.2 The mechanism of precipitation in this system is simpler and is more precisely known than that in any other system hence the system should be a profitable one for the difficult task of correlating property changes with structural alterations. The present report provides additional studies on powder X-ray diffraction from alloys of 10 per cent, 20 per cent and 30 per cent Ag, and presents the correlation of crystallographic changes with changes in microstructurc, Brinell hardness and electrical resistivity of the three alloys. Preparation of Samples and Experimental Procedure The preparation of the 20.2 per cent Ag alloy has been described2 Alloys containing 9.9 and 29.7 per cent Ag were prepared from 99.97 per cent A1 and 99.99+ per cent Ag using a similar procedure. Rolled

Jan 1, 1943

DISCUSSION, M. Cohen presiding A. H. Geisler and D. L. Martin (GeneTal Electric Research Laboratory, Schenectady, N. Y.)—We were rather interested to note the author's conclusion that the cubic to tetragonal transformation may be of the second order, for we have been able to show that the order-disorder transformation in an analogous alloy system is a first-order transformation with a discon-

Jan 1, 1952

FRANK N. SPELLER,? Pittsburgh,. Pa.-Mr. -Hayward's paper again draws attention to the fact that copper in steel is not the enemy that a good many of us it one time thought it was. He shows clearly that steel with over 0.75 per cent. of copper is as dependable, under the :conditions which he describes, as the same steel without copper. I might add that you-can weld copper-steel- satisfactorily up to that point; in fact, we have succeeded in welding pipe by the lap weld process up to 1 per cent. copper. Notwithstanding the date that have been presented on the effects of copper on the physical properties and corrosion of steel, a maximum copper limitation is still found in many specifications. In some cases the limit is extremely low, such as below 0.05 .or 0.03: per cent., or thereabout. That is a relic of days gone by, and I think the practice should be discouraged. E. F. CONE, New York; N. Y.-Not so many years ago steel-casting makers were very particular as to the amount of copper that existed in the pig iron that they used. They would not use copper-bearing pig iron unless mixed with non-copper iron. I do not know what the practice now is in the particular foundry where I was metallurgist at one time,

Jan 4, 1918

By JOHN R. SUMAN

TONIGHT I want to speak of the current problems and the postwar difficulties facing American industry. American industry has done an outstanding job in adjusting its operations to wartime necessity. The national income for 1942 was nearly $120,000,090,000 and of this outlay approximately $55,000,000,000 went for war material. The enormity of the expenditures for war material is indicated by the fact that the expenditures for war purposes alone were greater than the annual gross national income in the period 1931-34. This tremendous production job in turning out a record output of war products was accomplished by industry in spite of a large number of restraining and hampering influences, and I want to mention several of the more important problems.

Jan 1, 1943

By George Mah, Charles Wert

Internal-friction peaks caused by diffusion of oxygen and nitrogen have been observed in ytterbium. They are thought to be caused by the redistribution, under stress, of strain dipoles around an interstitial oxygen or nitrogen and a neighboring substitutional impurity. With the use of a simple geometrical model, diffusion coefficients for oxygen and nitrogen between special interstitial sites have been calculated. a) APPLICATION OF INTERNAL FRICTION TO MEASUREMENT OF DIFFUSION RATES IN DISSOLVED INTERSTITIAL ATOMS In bcc metals, the interstitial atoms occupy the centers of cube faces (0, 1/2, 1/2), or their equivalents, the center of the cube edges (0, 0, 1/2). An interstitial atom in this position causes an aniso-tropic distortion in the lattice. When stress is applied, mechanical relaxation can take place by the movements of the interstitial atoms. This relaxation has been used to obtain information concerning the movements of the interstitial atoms in the bcc metals. Data for these alloys have been compiled by Stanley and Wert. Other researchers have extended the investigation of interstitial diffusion to the close-packed metals. Gupta and weinig2 found an oxygen peak in a titanium, the height of which is linearly dependent on the oxygen concentration. They assumed, therefore, that they were dealing with movement of atomic ally dispersed oxygen in titanium. KG and wang3 determined that the diffusion coefficients of carbon in fcc steels and in nickel obtained by internal-friction methods were consistent with those obtained by macrodiffusion methods at much higher temperatures. Bisogni found oxygen and nitrogen peaks in hafnium by use of which he deduced the diffusion coefficient of these gases in hafnium. He observed further that the half-widths of these peaks corresponded almost exactly with those of a single-relaxation process; he assumed it to be caused by movement of atomically dispersed oxygen and nitrogen. From these studies, the deduction can be drawn that, in general, diffusion data can also be obtained for the interstitial diffusion in close-packed metals (or more precisely, in slightly impure close-packed metals). One group of such metals for which little data exist for the diffusion of dissolved oxygen and nitrogen is the rare earths. They have great affinity for gases, which enter solution interstitially. In this investigation results were obtained for the Yb-O and Yb-N interstitial solid solutions with traces of substitutional impurities; these solid solutions are of fcc structure. b) MECHANISM OF THE RELAXATION IN FCC CRYSTALS In the fcc structure, an interstitial gas atom is usually situated in the octahedral position (1/2, 1/2,

Jan 1, 1964

By Leonard B. Gulbransen, John R. Lewis, W. Martin Fassell, J. Hugh Hamilton

A simple reproducible method was developed for determining the ignition temperatures of magnesium and magnesium alloys and by this method magnesium and over 100 magnesium alloys were measured. The ignition temperature of magnesium was determined in O2-SO2, O2-N2 mixtures and in O2 from 0.166 to 10 atm pressure. The ignition temperature of magnesium is generally lowered by alloying and increased by an increase in oxygen pressure. WITH the expanded use of magnesium alloys in industry, ignition temperatures are of considerable importance, especially in heat treating and for service at elevated temperatures. Magnesium alloys exhibit a relatively slow linear oxidation rate up to temperatures near the melting point.' At some critical temperature the rate of oxidation becomes extremely rapid. This high rate of oxidation is accompanied by the emission of light and additional characteristics suggesting a flame. The literature concerning the ignition temperatures of magnesium and magnesium alloys is relatively incomplete and the values reported by various authors are not in agreement. The most probable reasons for this are: 1—The absence of a suitable definition of ignition, and 2—the need of a standardized method of determining the ignition temperatures of inflammable metals and alloys. The exact date of the discovery of the fact that magnesium will ignite and burn is unknown. It is likely that H. Davey encountered this property of the metal during its preparation in 1808. The first reference in the literature specifically on ignition of magnesium is by Lenze, Metz, and Rubens.' They investigated the inflammability of certain magnesium alloys. Brown3-' reported that magnesium ribbon will ignite in air at 507 °C by what was called the rising temperature method. Hartman, Nagy, and Brown" reported that magnesium powder ignites from 475" to 560°C depending on particle size. According to Guise, Mars, and Wilson prolonged heating in air at 427°C of common casting magnesium alloy causes it to ignite. Samples of magnesium alloys were placed directly in the flame of a torch by Carapella and Shaw.' These investigators obtained some evidence of melting prior to ignition. For commercial magnesium, they reported an ignition temperature of 650°C. Their values varied from 450" to 800°C for magnesium alloys. Willmore and Peterson" studied the effect of air velocity, humidity, rate of heating, and foreign metal contact on the ignition temperature of magnesium. They conclude that melting is not a prerequisite for ignition and that the conditions which influence ignition are complex and difficult to analyze. The only quantitative theoretical treatment of the ignition temperatures of magnesium and magnesium

Jan 1, 1952

By B. Post, F. W. Glaser

Three borides of zirconium have been reported: ZrB,l ZrB2,2,3 and ZrB12, 4 The phase relationships, ranges of stability, and some physical properties of these compounds are described. THE zirconium borides differ considerably from one another, particularly with respect to their relative stabilities at high temperatures in the presence of carbon.4,5 ZrB2 is extremelv stable at all temperatures (to the melting point) in contact with carbon. Both ZrB and ZrB12 tend to decompose at elevated temperatures when carbon is present in excess of about 0.5 pct. ZrB forms ZrB2 and ZrC, and ZrB12 decomposes to form ZrB2 and a boron-carbide phase. In the ZrB12 preparation, boron present in excess of that needed to form ZrB2 reacts with carbon, if present, to form carbides, in preference to forming the higher boride. Similar instability of borides, other than diborides of the transition metals of the 4th and 5th groups of the periodic table, has been reported.5,6 special precautions had, therefore, to be taken to minimize carbon contamination in the preparation of ZrB and ZrB12. Reactions below 1400°C were carried out by heating powdered mixtures of zirconium hydride and boron in quartz tubes in a hydrogen atmosphere. For temperatures above 1400°C, reactions were carried out in graphite molds. Carbon contamination from the molds was minimized by employing extremely rapid heating rates to reduce carbon diffusion into the body of the specimen, and by subsequent "shaving" of sample surfaces that had been in contact with the graphite dies. A heating rate of about 2000°C per min was obtained by heating the dies (by direct conduction), using a current of 40,000 amp. Although this type of heating cycle apparently allowed little time for "homogenization," close approximations to equilibrium conditions were usually obtained as a result of the very strongly exothermic reactions between zirconium hydride and boron at elevated temperatures. Reproducibility of results in repeated runs under varying conditions was taken as a reasonable indication that equilibrium conditions had been effectively achieved. Quenching was accomplished by rapidly immersing the entire die, containing the reaction products, in water. Specimens could also be cooled at controlled rates by adjustment of the rate of flow of water through the water-cooled copper electrodes in contact with the graphite dies.

Jan 1, 1954

By W. L. Dennen, V. H. Wilson

This paper is a description of the opera-tion and results of a Humphreys Spiral Silt Cleaning Plant at the Powderly Colliery 01 The Hudson Coal Co. during the first nine months of operation and follows a preliminary description given at the .Institute cite Institute in May, 1947, in a paper titled "Preparation of Anthracite Silt for Boiler Fuel in a Humphreys Spiral Test Plant" by H. H. Otto, V. H. Wilson and W. L. Dennen. This plant is considered a full size op-erating test plant and, like all new plants, numerous minor changes in the methods of operation have been made from time to time to secure the results desired. Views of the silt preparation plant and of the screening house are given in Fig I and 2. This plant consists of 48 spirals in 8 batteries of 6 spirals each, 36 of which were to be operated as primary spirals and the remaining 12 as secondary spirals. A brief description of the plant and its operation follows. The only material cleaned at the plant during 1947 was that carried in the underflow from the Thickener which han-dles the Breaker waste water. This under-flow, amounting to approximately 2000 gpm of water and containing 12.6 pct of solids, is pumped to vibrating screens where the plus 3/16-in. material is removed. (Fig 3). This oversize material drops into a pocket from which it is trucked to the run-of-mine tipple for re-preparation.

Jan 1, 1949

By B. W. Gonser, C. M. Heath

The importance of grain size and its control in wrought brass needs no lengthy discussion, since specifications so often make exact control imperative. Aids to this control are therefore of interest. The effect of a number of different elements on the grain growth of brass under various conditions of annealing has been reported in the technical literature. In particular, a paper by Cook and Miller1 a few years ago, with the discussion that followed, gave valuable information on the effects of iron, phosphorus, manganese, aluminum, aluminum plus nickel, and aluminum plus silicon. Price12 in his discussion of that paper, added a description of some commercial brasses that exhibited a grain-refining effect owing to the presence of 2 per cent A1 and 1 per cent Ni. Gibson and Doss3 have recently given data on the effect of iron on annealing high brass. No comprehensive study, however, has been given to the effect of additions of chromium. It has been the purpose of this investigation to determine the effect of adding various amounts of chromium to a plain cartridge brass, particularly in regard to the effect on grain growth in various annealing treatments after cold-working. Prepakation of Alloys Alloys of high-purity brass of 68.5 Cu, 31.5 Zn composition were made containing from 0 to 0.17 per cent Cr. These were produced in induction furnaces, using unlined graphite crucibles to hold the charge. The melts were cast into rectangular chill molds giving ingots about % by 3 by 10 in. in size.

Jan 1, 1938

By C. M. Heath, B. W. Gonser

The importance of grain size and its control in wrought brass needs no lengthy discussion, since specifications so often make exact control imperative. Aids to this control are therefore of interest. The effect of a number of different elements on the grain growth of brass under various conditions of annealing has been reported in the technical literature. In particular, a paper by Cook and Miller1 a few years ago, with the discussion that followed, gave valuable information on the effects of iron, phosphorus, manganese, aluminum, aluminum plus nickel, and aluminum plus silicon. Price12 in his discussion of that paper, added a description of some commercial brasses that exhibited a grain-refining effect owing to the presence of 2 per cent A1 and 1 per cent Ni. Gibson and Doss3 have recently given data on the effect of iron on annealing high brass. No comprehensive study, however, has been given to the effect of additions of chromium. It has been the purpose of this investigation to determine the effect of adding various amounts of chromium to a plain cartridge brass, particularly in regard to the effect on grain growth in various annealing treatments after cold-working. Prepakation of Alloys Alloys of high-purity brass of 68.5 Cu, 31.5 Zn composition were made containing from 0 to 0.17 per cent Cr. These were produced in induction furnaces, using unlined graphite crucibles to hold the charge. The melts were cast into rectangular chill molds giving ingots about % by 3 by 10 in. in size.

Jan 1, 1938

Despite the uncertain political situation in Katanga, copper and cobalt mining and metallurgical operations of Union Miniere du Haut-Katanga were normal at the time of this writing. In fact operations continued normal after Congo independence on June 30, 1960, with copper and zinc production for that year being slightly higher than in 1959. United Nations military operations from September to December 1961 resulted in death, shutdowns and damage to company persons and installations. Nevertheless, results for that year were only slightly off normal production. Moise Tshombe delared Katanga a separate state after Congo independence. Although there has been tribal unrest, the new State has enjoyed relative calm and normal industry by comparison with other parts of the Congo as a result of the firm hand of Moise Tshombe's government and the continued presence of Belgian officials and technicians.

Jan 12, 1962

By Cyril Smith

A COMPLETE discussion of the literature on the subject of the influence of copper on iron and steel will be published elsewhere.1 The present paper is concerned especially with the precipitation-hardening of copper steels, and brief mention will be made here only of the work of Kin-near,2,3 Nehl4 and Buchholtz and Koster,5 who alone have studied this phase of the subject. Kinnear found that normalized low-carbon steel castings containing about 1.0 per cent copper on drawing at temperatures in the neighbor-hood of 530° C. (1000° F.) increased in tensile strength and yield point, with little decrease in ductility. The maximum effect was obtained with about 0.9 to 1.0 per cent copper, and when the copper exceeded 3 per. cent no improvement occurred on reheating. Kinnear did not study the effect of time of reheating-an all important factor where precipitation is concerned. Nehl,6 who apparently was unaware of Kinnear's work, recognized the change as due to precipitation and studied the interdependence of time and temperature of reheating, the temperature of the initial solution heat treatment, and the speed of cooling necessary to retain the bulk of the copper in supersaturated solu-tion and to give an increase in hardness and tensile strength on reheating. Nehl found that if the final rolling or forging temperatures exceeded 700° C. (1300° F.) it was not necessary even to normalize the steel, but full precipitation occurred on merely reheating the forged or rolled shapes at 500° C. (930° F.).

Jan 1, 1933

By Fun-Den Wang

An open pit rock structure usually contains geological planes of weakness. They are formed by joints, faults, bedding planes, fractures, and cleavages. Rock slope failures often occur in the form of sliding of rock blocks along a plane or several planes. Such a rock block has three- dimensional geometry, and consequently a vector method of analysis has been found useful in evaluating its stabi1ity.l-3 Rock blocks of a tetrahedral shape with one free surface have been analyzed by Londe.3 Rock blocks formed by sets of parallel joints have been analyzed by Wittke.1,2 The present chapter presents the analysis of rock blocks formed by planes of weakness of arbitrary orientation, and of three-dimensional geometry. A plane of weakness is represented by its dip and strike in vector form and is reduced to the form of a linear equation. The geometry of the rock block is defined by solving the linear equations. The geometric characteristics of a rock block are based on triangles and tetrahedrons. By this treatment, the three-dimensional geometry is simplified and the number of calculations of forces and moments is reduced. Methods of finding the geometric characteristics are presented, along with equations for calculating the resultant forces and moments and the factor of safety. BASIC ASSUMPTIONS The following assumptions are used : The solid part of the rock mass is much stronger than the rock mass at the plane of weakness and the rock mass will only fail along planes of weakness.

Jan 1, 1972

By George T. Bator

If confronted with the problem of pumping a mixture of slime-free sand, gravel and boulders up to six in. in diameter, at the rate of 175 tons per hr in one single-stage pump against a static head of 90 ft and a total head of 140 ft, of which 20 is on the suction side, an engineer might be forgiven for backing away from the job, especially if he were also told that the pump wearing parts must have a minimum hardness of 550 Brine11 for the sake of abrasion resistance. Yet precisely that feat has been accomplished in the gravel pit of John B. LaGarde, Inc., near Anniston, Ala. The pump used is of decidedly novel design and its successful operation since installation 1.5 years ago suggests that it may be of timely interest in numerous other applications in the mining industry, such as pump transportation of coal washer refuse or rock from open-pit's without unduly fine crushing.

Jan 9, 1950