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By T. F. Witherbee

Discussion of Mr. Baker's paper, read at the Lake Superior Meeting, September, 1904. MR. T. F. WITHERBEE, Durango, Mexico (communication to the Secretary*) : Mr. Baker's paper is very instructive in that it shows how furnace-derangements sometimes originate from apparently slight causes. In 1896 a similar burning through of the lining occurred at the Mayville furnace of the Northwestern Iron Co., Mayville, Wis., in exactly 38 days from the time the furnace was blown in. At that time I attributed it to the fact that the bell was carried several inches to the front side of the furnace, the length of the versed side of the arc described by the lever, thus dumping a little more of the charge on the back side, which made the front side of the furnace-charge more open and consequently increased the circulation of the furnace gases through it. After reading Mr. Baker's description, I believe that possibly a little more ore was charged on the back side of the hopper, due to the fact that it was nearest to the elevator. This unequal charging, however, was unconsciously done, as the fillers were both honest and faithful. The illustration of the burned lining of Furnace No. 1, given in Fig. - of Mr. Baker's paper answers very well for the Mayville furnace. It shows that in both cases the destruction of the lining was largely due to faulty construction, in that there were no cooling-plates in the angle of the bosh and in one or two courses of brick above it, where I believe they are-more in demand than anywhere else in the furnace. The presence of these cooling-plates at the angle of the bosh would have obliged the current of the hot gases to turn the corner and would have prevented them from following the angle of the bosh com¬pletely through the lining and shell.

Mar 1, 1905

Edward Eeller, Baltimore, Md. (communication to the Secretary): Mr. Miller's improved method of the cyanide-assay for copper will, without doubt, be much appreciated by assayers and chemists who are engaged at copper mines and works. The writer, as one who, at one time, had much work of that kind to do, entertains no doubt of its practical value. In enumerating the factors which affect the accuracy of cyanide-titration, Mr. Miller omits to mention time. This I have always considered an essential one; i.e., in order to secure accuracy, I have believed it to be necessary to run the cyanidesolution at the same rate of speed in standardizing as in the titration of the samples. I have accomplished this, without the use of a time-keeper and without noticing the volume of the solution, in the following simple manner: In running the cyanide-solution from the burette, the stream was so regulated, by manipulation of the cock, that it retained its continuity for a distance of about one inch below the orifice, and, below that, broke into individual drops. This means that a constant pressure is maintained at the orifice of the burette, so that, during equal intervals of time, equal volumes of the solution pass through. The stream of cyanide-solution was left to flow in the manner indicated until the blue ammoniacal copper-solution began to show a distinct change in color, after which the cyanide was added by drops at regular intervals until the desired end-reaction. When several burettes are used they should have orifices of equal diameter; otherwise, the timefactor must be considered separately for each. In accordance with Mr. Miller's views, I have always considered the cyanide-method as of very satisfactory accuracy for all copper-assaying in which I did not employ the electrolytic method. It may interest some of my colleagues to know the modified method which I employed some fifteen years ago in making great numbers of copper-estimations on ores and

Jan 1, 1902

By R. W. Raymond

(Pittsburg Meeting, March,1910.) THE Giroux Consolidated Mines Co. is equipping a five-compartment shaft at Kimberly, Nev., which will serve the Alpha mice. The depth of this shaft, January, 1910, is 963 ft., and of this depth 948 ft. was opened by raising, 15 ft. of sinking was done so that the bearers, collar-set, and three shaft-sets might be installed and concreted, and with this done it was possible to erect the necessary surface-equipment for resuming shaft-timbering on the completion of the raise. The arrangement of the shaft-timbering is shown in Fig. 1. At the 1,000-ft. level of the Alpha, and 750 ft. SW. from the Alpha shaft, a 14- by 18-ft. station was cut, and a 25-h-p. air-hoist *as installed. From here the raising commenced on July 5, 1909. The raise was cut approximately 13 by 21. ft. in area, and supported by timbering with square sets, illustrated in Fig. 2, which shows the division into four compartments. The end compartments, which were used as chutes, had the center girts heavier than in the others on account of the wear from falling rock. The chute-lining was braced by inserting 8- by 8-in. stiffeners parallel to and half way between successive caps. Similarly, the lagging on the wall sides of the cage-way and the compartment for pipes and ladder was stiffened with 4- by 6-in. timbers. In the pipe-and-ladder compartment the chute-stiffeners were reinforced with 8- by 8-in, struts, and as the cage-way was partitioned off by braced lining, there was practically no chance of rock entering the ladder-way in case a chute burst into the cage-way. Over the two center compartments the last two, sets were always bulkheaded with 8- by 12-in. timbers, shown in Fig. 3, and from the lower bulkhead the cage sheave-wheel was suspended. After a round of holes had been blasted and the loose

Jun 1, 1910

By R. W. Raymond

PROF. HENRY Louis, of Armstrong College, Newcastle-on-Tyne, England, a distinguished member of this Institute and other technical societies, has recently sent to the Institution of Mining Engineers, and to the Institution of Mining and Metallurgy, in Great Britain, a communication, the substance of which is as follows Prof. Louis calls attention to the absence of any recognized English term for the definite description of a frequent phenomenon-namely, the oblique position of an ore-body in the plane in which it. lies. In this connection, Prof. Louis says that in America the term " pitch " has been occasionally applied to this relation, and proposes that, in the literature of ore-deposits, it shall be hereafter restricted to this particular meaning, the angle of the pitch, like that of the dip, being always measured from the horizontal, and the dip being always taken at right angles to the strike, while the pitch is taken on the plane of the dip, in the direction of the strike. Thus, for example, in a vein or bed striking N-S., and dipping, say, 45° E., there might be an ore-body, the axis of which pitched northward, at an angle of 45° below the horizontal line, as measured on the plane of the inclosing vein or bed. If the term " pitch " had this universally recognized meaning, the situation could be simply and perfectly expressed by its use, in connection with the general data of strike and clip. As Prof. Louis says ?This suggestion has a certain practical value, and is not merely academic. Every mining engineer of practical experience in such types of ore-deposit will have met with cases, in which a vertical shaft has been sunk with the object of cutting the deposit, but has missed it, because the dip alone has been taken into account, while the pitch has been overlooked." He adds the acute observation that such an oversight is much likelier to occur with regard to a condition not definitely desig-

Mar 1, 1908

By James Douglas

In discussing the waste upon which hinges, or is supposed to hinge, so largely the preservation of our national resources, the conclusions reached would be more reliable if actual experience were consulted, and fewer deductions were drawn from general statements, which are often the product of the imagination. It cannot be questioned that the value of by-products has .not been sufficiently appreciated by us, and that our tardiness in recovering the useful ingredients of the escaping gas of our coke-ovens is one of the most glaring instances of shortcoming in that direction. And yet even for that sin there is some palliation in the immature condition of affiliated industries. I presume that it is admitted, without argument, that, except under very exceptional conditions, all the elements cannot be recovered from most of the ores or natural products which we treat. While it is a shame that the by-products from our coke-ovens should be dissipated, Edward W. Parker's report to the U. S. Geological Survey for 19061 supplies a fairly good excuse in justification of this appalling waste. He says (pp. 773 to 774.): " What has been already commented on in previous reports about the slowness of manufacturers to change from the better known but wasteful beehive practice to the by-product recovery method of coke manufacture is particularly emphasized in the statistics presented in this chapter. For it would appear from the table following that the construction of by-product ovens had about come to a standstill, especially when the records for the preceding five years are taken into consideration. At the close of 1901, when there were only 1,165 by-product ovens completed in the United States, there were 1,533 in course of construction, 498 of which were completed during the following year. At the close of 1902, 1,346 retort ovens were building, 293 of which were added to the completed plants in 1903. At the close of 1903, 1,335 new ovens were building and 954 of these

Jan 1, 1910

By S. R. Rao, J. Leja, K. S. Moon

A prolonged grinding of sulphide ores in steel mills appears harmful to flotation recovery and selectivity whenever xanthates are used as collectors. Particles finer than about 10µm show a pronounced decrease in floatability. A supposition was made that the cause of the reduction in floatability of ground sulphides is the presence of metallic iron abraded during grinding and deposited on the ground particles. Electro- chemical measurements were made of mixed potentials developed by different sulphide-mineral electrodes (galena, chalcopyrite, pyrite, marmatite, pyrrhotite) in xanthate solutions, without a direct con- tact or in contact with a metallic iron electrode. These measurements showed that without a galvanic contact between the sulphide and the iron, the values of mixed potentials were in the vicinity of the xanthate/dixanthogen redox potential. When contact with iron was established, the mixed potentials shifted towards the more negative reducing or cathodic values. The shift was greater the higher was the ratio of the surface areas: iron electrode to sulphide electrode. Further, the shift in mixed potentials was greater the more reducing were the conditions on the sulphide electrode. Chemical analysis of reaction products produced on the surfaces of sulphides and in the bulk solution showed that less thiosulphate was formed in all of the sulphide-xanthate systems and that more elemental sulphur was detectable on the pyrite and marmatite surfaces. Adsorption of xanthate parallels the amount of thiosulphate formed with which xanthate is exchanged by metathesis. If the supply of oxygen is limited, the demand for oxygen by the abraded metallic iron competes with that by the valuable sulphide, resulting ultimately in poorer hydrophobicity. If excessive amounts of pyrite or pyrrhotite are present as well, the conditions are so reducing that there is little adsorption of xanthate ions on the valuable sulphides to make them hydrophobic and floatable. The presence of increased quantities of sulphur on pyrite or marmatite is responsible for a non-selective flotation. Flotation tests on synthetic mixtures with and without metallic iron powder in the feed confirmed the above conclusions from electrochemical and chemical measurements.

Jan 1, 1976

By Charles W. Tandy, Wm. I. Weisman

Sodium sulfate is an important industrial chemical, being one of perhaps a dozen or so chemical commodities that are produced and consumed in the United States in quantities exceeding one million short tons per year. In recent years over half of the country's production of sodium sulfate has come from natural sources, whereas 20 years ago only 25% was derived from these sources. Production of natural sodium sulfate from various types of deposits is the main source of this chemical in Canada and Mexico, and probably in Argentina, Chile, and the USSR. [Table 1] illustrates the growth in production of natural sodium sulfate in the United States. Mineralogy and Physical Properties Sodium sulfate is widespread in occurrence and is a common constituent of many mineral waters, as well as seawater. Many of the saline or alkali lakes throughout the world contain varying amounts of sodium sulfate. In its natural form it is found as the hydrous salt, mirabilite, commonly called Glauber's salt, and as thenardite, the anhydrous variety. The largest quantities occur in the form of mirabilite. Sodium sulfate is found in varying degrees of purity, from theoretically pure efflorescent crystals of mirabilite to combinations and admixtures of other salts and impurities. It is a common constituent of some brines, and it is from this source that much is extracted commercially. Sodium sulfate is also found combined with other compounds, such as the mineral glauberite, the double salt of anhydrous sodium and calcium sulfate, and blödite, the double salt of sodium sulfate and magnesium sulfate. While these and other minerals containing sodium sulfate are not economically important, they are of interest because of their frequent occurrence. The reader is referred to other publications (Cole, 1926; Dana, 1932; Grabau, 1920) for descriptions of these minerals. Only the two economically important minerals, mirabilite and thenardite, will be described herein. Mirabilite, Na2SO4 • 10H2O, contains 55.9% water of crystallization. It is noted for its efflorescence or spontaneous loss of water. On

Jan 1, 1975

By Robert V. Whitman

INTRODUCTION Ideally, this paper should start by citing examples of slope failures in open pit mines during earthquakes. I do not know of any such examples, although - since my search of the literature has not been exhaustive - such examples may well exist. However, there certainly are many examples of devastating earthquake-induced landslides, and there is no reason why such landslides cannot occur at large open pits. Moreover, many of the actual earthquake-induced landslides have seriously affected mining operations in one way or another. Hence, this paper will treat earthquake-induced landslide phenomena in general, in the hope and expectation that the reader can apply this general knowledge to the specific problems associated with open pit mining. Ultimately, of course, the aim is to predict the likelihood of the occurrence of earthquake-induced landslides, and to delineate steps which can be taken to minimize the possibility of their occurrence. These aims can be achieved only imperfectly at the present time, for our knowledge concerning earthquake-induced landslides is still in an embryonic stage. Nonetheless, much useful knowledge does exist. In order to understand and apply this knowledge, it is necessary to: 1. Review the nature and extent of actual earthquake-induced landslides; 2. Have a grasp of the basic terminology and concepts of seismology; 3. Study the fundamentals of probability-based seismic risk analysis; 4. Appreciate the way in which earth materials behave during earthquake loadings; and 5. Have a general knowledge of the methods currently available for analyzing the dynamic response of slopes. Much of this paper is devoted to this necessary background. Information of practical use in connection with various classes of slope stability problems is assembled in the final sections. LANDSLIDES DURING PAST EARTHQUAKES Almost every earthquake in mountainous country, strong enough to be reported in the literature, has caused at least some landslides and rockfalls. Unless these slides or falls damage

Jan 1, 1971

THE problem of reaction rates in the open-hearth process is essentially that of trying to form a fairly clear picture of the "chemical mechanisms" in the bath. Quantitative data on reaction rates would perhaps not be of much practical importance even if they were available; however, what few approximate data there are can be used in combination with data given in Chapters 16 and 17 to sketch a picture of the "chemical mechanics" of the open-hearth process that is consistent with essentially all the present available evidence. The result may later be found incorrect in many details but even so it will illustrate certain useful methods for obtaining a clearer understanding of the process. Consistent with the treatment in Chapter 15, but in simpler terms, we may say that chemical reactions in general involve the following elements or steps : 1. The reacting molecules are mixed together in space in such fashion as to favor collisions among them. 2. Units of what is usually an intermediate molecular arrangement called an activated complex are formed at a certain rate, depending on temperature and concentrations. 3. .These activated complex units decompose into the reaction products (this step usually assumed to be so rapid as never to limit the over-all process). 4. In any of these steps, heat energy may have to flow into, or away from, the reaction zone to permit the reaction to proceed. 5. The products of reaction will usually have to move out of the way to permit further reaction. The temperature factor enters mainly through step 2, and its effect is very marked. (What is called temperature is really the mean energy content of all the molecules of the substance involved; at any one temperature a certain proportion of the molecules will have much higher energy content than the mean value.) Various reaction rates measured at around room tem-

Jan 1, 1964

By Bruno V. E. Nordberg

Hoisting is one of the earliest endeavors of man with machinery, for hoisting was probably used by the early Egyptians. Treadmills were used for general hoisting until early in the nineteenth century and it was a short step only to attach a Watt steam engine to the rope drum of a hoist. One of the earliest steam hoists was built for a coal mine at Frisne, near Valenciennes, France. It was a remarkable piece of engineering created by James Watt in 1811, using a wooden drum on a vertical shaft. This followed the crude hoist by Holtzhausen in 1803, which used a drum of wood on a horizontal shaft.' In this country there were examples of crude mine hoists, which have been developed into the efficient machines in use today. African and Australian mines show examples of both extremes, and have an array of fine hoisting equipment exemplified in those built by British manufacturers. The influence of both English and American engineering in hoisting is interestingly evident in Canada. The information available to the writer does not reveal this to be true of South Africa, although American-built hoists have been furnished. Mining camps develop their own style of equipment, adapted to local conditions. For instance, the Butte mining district adheres to the straight drum with friction clutches, because of the great number of levels from which hoisting is done or to which men and material are lowered and the necessity for hoisting or lowering unbalanced. The north Michigan copper country uses both straight and cylindroconical drums and hoists continually in balance, so that the drums are not clutched to the main driving shaft. The Joplin mining district, Missouri, has its own peculiar small hoists. Other individual mines or localities in which a number of mines have been developed show individualistic types of hoists, depending upon their particular problems. In each instance, however, the particular problem must be carefully analyzed, as conditions are seldom so near the same that a number of identical hoists can be used to advantage.

Jan 1, 1940

By Bruno V. E. Nordberg

Hoisting is one of the earliest endeavors of man with machinery, for hoisting was probably used by the early Egyptians. Treadmills were used for general hoisting until early in the nineteenth century and it was a short step only to attach a Watt steam engine to the rope drum of a hoist. One of the earliest steam hoists was built for a coal mine at Frisne, near Valenciennes, France. It was a remarkable piece of engineering created by James Watt in 1811, using a wooden drum on a vertical shaft. This followed the crude hoist by Holtzhausen in 1803, which used a drum of wood on a horizontal shaft.' In this country there were examples of crude mine hoists, which have been developed into the efficient machines in use today. African and Australian mines show examples of both extremes, and have an array of fine hoisting equipment exemplified in those built by British manufacturers. The influence of both English and American engineering in hoisting is interestingly evident in Canada. The information available to the writer does not reveal this to be true of South Africa, although American-built hoists have been furnished. Mining camps develop their own style of equipment, adapted to local conditions. For instance, the Butte mining district adheres to the straight drum with friction clutches, because of the great number of levels from which hoisting is done or to which men and material are lowered and the necessity for hoisting or lowering unbalanced. The north Michigan copper country uses both straight and cylindroconical drums and hoists continually in balance, so that the drums are not clutched to the main driving shaft. The Joplin mining district, Missouri, has its own peculiar small hoists. Other individual mines or localities in which a number of mines have been developed show individualistic types of hoists, depending upon their particular problems. In each instance, however, the particular problem must be carefully analyzed, as conditions are seldom so near the same that a number of identical hoists can be used to advantage.

Jan 1, 1940

By R. M. Brick, Arthur Phillips

The Institute of Metals Division Lecture in 1936, given by R. F. Mehl, on diffusion in solid metals1, was introduced with the statement that "the phenomena of diffusion are intimately related to many basic problems of the metallic state, but in addition to this the process of diffusion is of first importance practically." In view of the scope of that lecture, it does not seem necessary to review the importance, history or present status of diffusion problems. One aspect of the subject of diffusion that has received little attention became of some immediate importance in the course of a study on segregation. When a solid solution alloy freezes, the familiar mechanism of solidification requires that the first nuclei formed be low in solute concentration, with a resultant normal segregation or coring effect during freezing. Theoretically, musion of solute atoms during solidification should result in a homogeneous solid solution. Actually, of course, it is impossible in most binary alloys to obtain a cooling rate that will permit diffusion to eliminate coring in the freezing dendrites. For a given alloy, the extent of diffusion attained up to the point of final solidification will determine the degree of enrichment in solute atoms of the final liquid phase. The flow of this liquid into dendritic contraction channels and the solute concentration of the liquid seem to be the determining factors as to whether the final gross segregation is normal, inverse or absent. The purpose of the present study of diffusion was to determine to some extent the separate diffusion rates of copper and magnesium into pure aluminum with a view to clarifying previous results on segregation in these alloys; i.e., the fact that under similar freezing conditions aluminum-copper alloys segregate inversely and aluminum-magnesium alloys segregate normally. Of concomitant interest were the questions of the homogenization times required for segregated ingots or partially melted, i.e., "burnt," structures, and the solution heat-treatment times required for cast, hardenable aluminum-copper and aluminum-magnesium alloys, for worked and annealed structures, and so forth.

Jan 1, 1937

By J. W. Cunningham, M. J. Stultzman

THE demand for improved materials for high-temperature service has increased during the last few years. Iron,- nickel,- and cobalt-base alloys have been investigated extensively and many alloys with outs'tanding high-temperature strength have been developed. Considerable research has been directed toward improved methods of processing these alloys. The vacuum furnace as a tool for the purification and improved control of high-temperature alloys has been studied extensively and production units are in operation. The research covered by this paper studied the effects of casting in air, vacuum, or argon upon the elevated-temperature properties of two nickel- and two cobalt-base alloys. The alloys investigated were Stellite 31, He 1049, Udimet 500, and Guy Alloy. MELTING AND CASTING PROCEDURES Two heats of each of the four alloys under investigation were melted and investment cast under the following conditions: 1) Stellite 31 was melted and investment cast in air and in vacuum, with an argon atmosphere for pouring. 2) He 1049 was melted and investment cast in air and in vacuum, with an argon atmosphere for pouring. 3) Udimet 500 was melted and investment cast in vacuum with and without additions of zirconium and boron. 4) Guy Alloy was melted and investment cast in vacuum and in argon. The heats were all melted in induction furnaces equipped with preformed magnesia crucibles of 50-lb capacity. The air-melting furnace was powered by a spark-gap converter of 40 kw capacity. The vacuum-melting furnace was powered by a motor-generator set of 100 kw capacity. The argon heat of Guy alloy was melted in the vacuum melting furnace under an argon atmosphere. Virgin materials were used for preparing all heats except the air heats of Stellite 31 and He 1049. The charge for the air heat of Stellite 31 was a commercial blend of shot. The charge for the air heat of He 1049 was Stellite 6 shot plus those virgin materials necessary to give the desired composition. All of the materials used were of the same grade used com-

Jan 1, 1960

By L. B. Lindemuth

To those who are in a position to carry the thought to a conclusion; I would like to present a theory for the cause of blisters in galvanized sheets. Blisters that are caused from piping and shrinkage cavities will not be considered because the reason for their formation is entirely obvious. Blisters that occur periodically with no apparent system of ocation, number, size or grouping, and then disappear with no. apparent change in manufacturing method, are the ones to which this theory would apply. Examination of blisters of the latter type has shown that they contain hydrogen gas at atmospheric pressure, and that occasionally traces of oxide or sulfide are found on the inner surface of the blisters. These two characteristics have led to the rather general idea that hydrogen gas generated in pickling, and that iron oxide supposed to be inherent in the ingot and causing weak spots were, in some manner, responsible for the development of blisters in galvanizing. The theory which I wish to advance is that these blisters are caused by moisture that has penetrated the steel after the annealing operation. This moisture comes from the atmosphere, or from pickling or washing and when it is suddenly expanded into superheated steam in galvanizing, the increase in volume is so great that it cannot escape with sufficient rapidity through the small opening where it entered as moisture.The pressure so generated forces the sheet apart along those lines of lamination ;hat may be found in practically all flat sections of steel rolled comparatively cold. The increase in volume. from moisture to steam at 800° F. is 2244 times the original volume of the moisture. The pressure generated by ;he moisture heated to 800° F. and entirely confined would be enough to expand or explode any container. This would explain the source of sufficient pressure to cause a sheet to blister.

Jan 3, 1927

By Bruno V. E. Nordberg

HOISTING is one of the earliest endeavors of man with machinery, for hoisting was probably used by the early Egyptians. Treadmills were used for general hoisting until early in the nineteenth century and it was a short step only to attach a Watt steam engine to the rope drum of a hoist. One of the earliest steam hoists was built for a coal mine at Frisne, near Valenciennes, France. It was a remarkable piece of engineering created by James Watt in 1811, using a wooden drum on a vertical shaft. This followed the crude hoist by Holtzhausen in 1803, which used a drum of wood on a horizontal shaft.1 In this country there were examples of crude mine hoists, which have been developed into the efficient machines in use today. African and Australian mines show examples of both extremes, and have an array of fine hoisting equipment exemplified in those built by British manufacturers. The influence of both English and American engineering in hoisting is interestingly evident in Canada. The information available to the writer does not reveal this to be true of South Africa, although American-built hoists have been furnished. Mining camps develop their own style of equipment, adapted to local conditions. For instance, the Butte mining district adheres to the straight drum with friction clutches, because of the great number of levels from which hoisting is done or to which men and material are lowered and the necessity for hoisting or lowering unbalanced. The north Michigan copper country uses both straight and cylindroconical drums and hoists continually in balance, so that the drums are not clutched to the main driving shaft. The Joplin mining district, Missouri, has its own peculiar small hoists. Other individual mines or localities in which a number of mines have been developed show individualistic types of hoists, depending upon their particular problems. In each instance, however, the particular problem must be carefully analyzed, as conditions are seldom so near the same that a number of identical hoists can be used to advantage.

Jan 1, 1940

By John F. Blandy

Although the question of the "waste of anthracite coal mining " has been so frequently discussed, and a committee was appointed at the first meeting of this Society to consider and report upon the subject, still but little progress seems to have been made in arriving at a conclusion as to how it ran be reduced. That committee made a preliminary report at the August meeting, 1871, in which it divided the question into three parts, namely: Waste in mining, in preparing for market, and in transportation. I shall not here refer to the first item, as so much depends upon the peculiar features of each separate mine, and the skill of those in charge; but in reference to the second, that of preparing the coal for market in breaker and screens, I wish to make some remarks. There is no use considering the question, whether the coal should be broken up to suit the fancy of consumers; all miners are satisfied that it should not be, but the consumers decide that they want it that way, and the miner must submit, and simply utter his maledictions upon the head of the man who first suggested a breaker or screen, if that is any consolation to him. What is called waste in this process of preparation, is the dust and fine coal, which results from the breaking and screening, and, as we all know, this is a very important percentage of what passes from the slope to the top of the breaker. Now, if this dust and fine coal can be utilized—the slate which is picked out is not to be taken into consideration as waste—then we get rid of this item entirely. There is no question in my mind that this article can and will be used as a steam generator at least, and I think, therefore, that in depositing

By S. F. Radtke, J. A. Snyder, R. M. Scriver

DISCUSSION, J. R. Long presiding R. I. Jaffee (Battelle Memorial Institute, Columbus, Ohio)—The authors have written a fine and important paper, and are to be congratulated. I do not entirely follow their discussion of the relationship between the ductility of titanium and its crystal structure. Since high purity titanium is extremely ductile, being capable of cold reductions of ovei- 99 pct, its ductility cannot be unduly restricted by its hexagonal crystal structure. It is true that interstitial solid solutions of nitrogen and oxygen do have a restricting effect on ductility, but this would appear to be an alloying effect rather than a crystal structure effect. The point made by the authors concerning the relative ductility between forged and rolled titanium does not appear to be conclusive, either. It would appear that in the same condition forged material would have equivalent or better ductility than sheet material. The difference between the ductility reported for forged bar and annealed sheet in Table I may be the result of a greater degree of cold work in the as-forged condition. S. F. Radtke, R. M. Scriver, and J. A. Snyder (authors' reply)—We appreciate the discussion by Dr. Jaffee. His point is well taken that the hexagonal structure of titanium does not, in itself, restrict the ductility of iodide material and, therefore, should not be limiting in this case. It is true, however, that the ductility of different grades of titanium is not necessarily related to their hexagonal structure but more likely to their orientation and composition. It is also true that the presence of small amounts of foreign elements in hexagonal metals may have more pronounced influence on ductility than a corresponding quantity in cubic metals. Average values from a large number of tests might show relatively better ductility for forged titanium than is recorded in Table I. The forged bars used in this work were tested in the annealed condition; little is known concerning the effect of forging practice on ductility in titanium metal.

Jan 1, 1952

By A. W. Hann

THE importance, to geologists and metallurgists, of knowing the mineralogical forms in which the silver occurs in ores has increased during the past few years, and will continue to increase as long as working hypotheses are converted into proved theories and rule of thumb methods are supplanted by scientific data. The methods used for the determination of these silver minerals have been: (1) careful study of polished ore sections with the microscope, and more recently, (2) metallurgical separation of the ground ore by flotation, tabling and panning, supplemented by microscopic examination of these separated minerals, and chemical analyses. During the course of some experimental work carried on by the testing department of the International Smelting Co. and myself, it became important to determine, in a general way, the distribution of the silver values in the minerals, as they exist in Tintic Standard and North Lilly siliceous oxidized lead-silver ores. These mines are in the East Tintic Mining District, State of Utah. In this work the second method was used. Differential flotation tests were run, separating the sulfide from the oxidized minerals, and the products were assayed. Various concentrates were carefully panned and the separated products assayed; special samples of ore were selected and assayed. The microscope was used only for the purpose of determin; ing whether the individual minerals were in the so-called "free" state. Analysis of Tintic Ores These chemical and mineralogical determinations showed the silver to be present as native silver, argento jarosite, argentite, and combined or inherent in the tetrahedrite, chalcopyrite, galena, pyrite, cerussite, anglesite, mimetite, malachite, iron oxide and occluded in the quartz. Careful microscopic work would probably show other forms in small amounts, such as the halide silver minerals and some of the antimony sulfide combinations. The tabulation of the analyses of the various products (Table 1) shows no evidences of fixed ratios of silver to any particular base metal.

Jan 1, 1929

By Ian J. Smalley

"Quickclay is an extreme case, it is by far the most mobile of all the common solid materials on the earth's surface. It has both a high water content and a mineral texture that allows it to flow with the utmost ease. A mass of quickclay that has lain undisturbed for thousands of years can be jarred into motion by any sudden shock." The quotation is from the paper by Kerr called, "Quickclay," which was published in Scientific American in 1963. This was probably the most widely read paper on quickclay ever published. It was reprinted by Fred Betz in his Benchmark collection on Environmental Geology (BM 25), A quickclay is an extremely sensitive soil. The sensitivity parameter is produced by dividing the undisturbed shear strength by the remoulded shear strength. If a value greater than 50 is obtained, then the soil can be classified as a quickclay. True quickclays are characterized by a very low remoulded strength of the order of 0.5 kPa. The classic quickclays are found in Scandinavia and Eastern Canada, but the 1964 Alaska earthquake revealed a considerable quick¬clay deposit underlying the town of Anchorage. This was discussed in a classic paper by Kerr and Drew in Engineering Geology in 1967. The Kerr views on quickclays were perhaps most clearly expressed in the paper with Liebling in Geol. Soc. Amer. Bull. in 1965. They suggested that the major critical conditions which contribute to quickclay movement are: substantial quantities of layer lattice silicates of colloidal size (about 40% or more by dry weight), sub¬stantial pore water (44%), a reduction in electrolyte concentration below 5 g/l of salt, and addition of a dispersant. There is still discussion and disagreement about the nature of quickclays and the mechanisms of quickclay slides; the "clay mineral"-based views favored by Kerr still find support, although an alternative "primary mineral" view suggests that it is the finely ground primary minerals

Jan 1, 1985

By John F. Blandy

ALTHOUGH the question of the "waste of anthracite coal mining" has been so frequently discussed, and a committee was appointed at the first meeting of this Society to consider and report upon the subject, still but little progress seems to have been made in arriving at a conclusion as to how it can be reduced. That committee made a preliminary report at the August meeting, 1871, in which it divided the question into three parts, namely Waste in mining, in preparing for market, and in transportation. I shall not here refer to the first item, as so much depends upon the peculiar features of each separate mine, and the skill of those in charge; but in reference to the second, that of preparing the coal for market in breaker and screens, I wish to make some remarks. There is no use considering the question, whether the coal should be broken up to suit the fancy of consumers; all miners are satisfied that it should not be, but the consumers decide that they want it that way, and the miner must submit, and simply utter his maledictions upon the head of the man who first suggested a breaker or screen, if that is any consolation to him. What is called waste in this process of preparation, is the dust and fine coal, which results from the breaking and screening, and, as we all know, this is a very important percentage of what passes from the slope to the top of the breaker. Now, if this dust and fine coal can be utilized-the slate which is' picked out is not to be taken into consideration as waste-then we get rid of this item entirely. There is no question in my mind that this article can and will be used as a steam generator at least, and I think, therefore, that in depositing

Jan 1, 1877