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By E. K. C. Williams, Nathaniel Arbiter

INTRODUCTION The surface processes involved in preparing ores for flotation and for operations depending on their flocculation/dispersion characteristics * vary widely in agitation dependence. Most of the reagents used for these purposes are added to grinding circuits, pump sumps, launders, or directly to flotation cells with the turbulent flow conditions usually adequate both for mixing reagents and for surface reactions without special conditioners. However, some reagent systems do require specific control of agitation intensities and reaction times, the more important of these being the following: 1. Activation of ZnS with CuSO4. With the usual conditions pH about 10, with collector added with the CuSO4, Cu 2+ is almost completely precipitated as basic compounds and as collector salt. As a result the levels of reagent in solution are extremely low which probably accounts for the need for separate conditioning. The agitation intensities are at about the 0.01 HP/ton level.** 2. Flocculation with natural or synthetic polymers. In this case the agitation problem is two-fold; first, to insure adequate initial mixing of the viscous stock solution of the

Jan 1, 1980

By Malcolm F. Hawkes, Robert F. Mehl

THE rate of isothermal transformation of austenite to pearlite depends upon the rate of nucleation, N, and the rate of growth, G, of pearlite in austenite.1.2 Values of N are given in terms of the number of nuclei forming in unit time per unit grain boundary area of unreacted austenite; values of G are given in terms of the linear rate of radial growth. Variations in the isothermal rate with temperature result from variation of -N and G with temperature. Depth of hardening of a steel depends fundamentally upon values of N and G; changes in carbon and alloy content effect changes in N and G and thus affect depth of hardening. Quantitative studies are available on N and G for the formation of pearlite in plain carbon eutectoid steels.3 Systematic studies in this field are necessary if the phenomena are to be well enough known to furnish. a proper basis for full rationalization and for theory. Accordingly, the studies are continuing, both with respect to the effect of alloying elements upon the values of N and G in the formation of pearlite, and to the values of N and G for the formation of ferrite in hypoeutectoid steels. The present paper is the first relating to the effect of alloying elements upon the values of N and G for pearlite. It offers special interest since cobalt is known to have an anomalous effect upon the rate of formation of pearlite, accelerating it, whereas all other elements retard it.' It will be shown that cobalt increases both N and G for pearlite and that this effect is inherent in the Fe-Co-C system and not dependent upon factors relating to austenite heterogeneity nor upon any recognizable adventitious factor. Inasmuch as the rate of diffusion of carbon in austenite and the interlamellar spacing of pearlite are variables related to G and possibly to N (in a manner not yet certain), measurements of the "effect of cobalt upon them are also reported here. In the course of the work, measurements were made on the effect of cobalt upon the martensite temperature and these are given. COBALT AS AN ALLOYING ELEMENT IN STEEL PROPERTIES OF COBALT Cobalt resembles iron more closely than does any other chemical element. Its atomic number is 27, hence it is the element immediately following iron in the periodic system. The two differ in atomic structure only in the fact that cobalt contains seven electrons instead of six in the third, or transition, level of the third shell. The next shell, which is the

Jan 1, 1947

By Raymond D. Sloan

During 1944, substantial gains were recorded in practically every phase of the petroleum industry in Oklahoma. With the spotlight of activity focused on other states during the more recent years, the production momentum that was achieved in Oklahoma through the discovery and development of such outstanding pools as Oklahoma City, Fitts. and major pools in the Seminole area during the late 1920's and early 1930's was practically spent by the end of 1943. However, with much of the industry's exploratory efforts greatly reduced in Illinois, Indiana and Kentucky, the strong demand for Mid-Continent crude and the optimism created by some discoveries in the state toward the end of 1943, Oklahoma has again become the recipient of much activity and interest, with its 1944 drilling activity, production and refinery runs to stills registering substantial gains over the preceding year. Development and Exploration Since the discovery of the West Edmond pool in April of 1943, with the substquent drilling and development boom, the scene of exploratory activity has shifted from the central. south and east portions of the state to the general trend of the . Granite Ridge, where leasillg and wild-catting were greatly activated within a wide radius of this high subsurface feature. Leasing activity, however, jumped the confines of the Granite Ridge trend and extended into all of the northwestern counties in the state. Seismograph activity at once began following and keeping pace with this shift in the leasing and exploration locale, by the concentration of a large number of seismograph crews in the area. At one time during the year,35 crews were concentrated in Oklahoma, the majority being west of the Granite Ridge and extending into the northwestern counties. To illustrate the increase in geophysical work done in the state during the year, records indicate that 377 crew months were worked in 1944, which is a 21 per cent increase over the 311.5 crew months activated in 1943. With the discovery in 1943 of several encouraging prospects and the finding of West Edmond as an incentive, drilling operations increased some 54.3 per cent, for a total of 1986 completions during the year. This is compared with a figure of 1287 for wells drilled in 1943, an increase of 699 wells. The industry, with a total of 1064 oil producers, enjoyed a success percentage of 53.6 per cent. Gas wells completed were 223, while 699 dry holes were drilled. In 1943, completions included 587 oil wells, 127 gas wells, and 573 dry holes. The number of oil producers completed during the Year was almost double the numher of wells in 1943. Of the total drilling wells completed in the state, 350, or 17.6 per cent, were wildcat operations—an increase of 5.1 per cent over the 194.3 total of 333. The wildcat success percentage was 13.4 per cent, 47 successful wells being completed for an average initial potential of 160 bbl. In the state, 23 gas wells were completed with an average initial production of

Jan 1, 1945

By Raymond H. Young, Paul Sennett

INTRODUCTION Kaolin clay, consisting largely of the mineral kaolinite, is widely used as a white pigment. In the United States, for instance, pigment kaolin production was nearly 6,000,000 tons in 1976 (1). Production for this year should be significantly above this level. Current prices for kaolinite 'pigments range from about $20.00/ ton to$260.00/tony,depending on the amount of processing needed to make the final product. Although much of this pigment kaolinite is used as an inert filler where product specifications are not very rigid, a large quantity of kaolinite is converted to products where very restrictive specifications exist. These specifications set severe limits on such properties as viscosity in a water suspension, particle size distribution, color, and brightness. This discussion will concentrate on methods available to improve the color and brightness of pigment kaolin and will review the advantages and problems associated with these various methods. The term "brightness" refers to the reflectance of the pigment to blue light (2). Since even the brightest commercial kaolins have a somewhat yellowish color, the blue reflectance (or brightness) is a reasonably good measure of their nearness to a perfectly white material. I KAOLINITE STRUCTURE AND SOURCES The mineral kaolinite is an aluminum silicate and can be represented by the formula (OH) 8Si4A14010. The formula is frequently written

Jan 1, 1979

By J. H. Frye, R. M. Treco, J. W. Caum

IT has been suggested that: "Insofar as the hardening due to a solute depends upon the increase of lattice parameter produced by it, it is reasonable to suppose that this hardening might be related to the resistance which the pure solvent would offer to increase in its parameter."1 It was further suggested that this hypothesis might be examined by comparing the hardnesses of analogous silver and copper alloys, since the stress necessary to produce a given lattice expansion is quite different in the two metals. Suitable data 2,3,4 are now available on these alloys, and we shall proceed to an examination of the hypothesis quoted above. HARDNESS, LATTICE PARAMETER AND IONIC OVERLAP Increase in ultimate Meyer hardness has been plotted against increase in lattice parameter in Figs. I and 2, It is believed that most of the values are accurate within the limits indicated by the rectangles, These data are also presented in Table I. Ultimate Meyer hardness, Pu, is defined by the equation: [P" - D2] where L = load, D = diameter of an impression having the same diameter as the testing ball, which in this case is 4 mm. Increase in lattice parameter is defined as the difference between the lattice parameter of the solid solution and that of the pure solvent. The curves in Figs. I and 2 are based on equal solute concentration and an equal degree of plastic deformation pro¬duced by the testing ball. Hardnesses are corrected to a constant grain size for copper and silver alloys, respectively, and these two grain sizes are approximately equal. Furthermore, all solutes are from the same period of the B subgroup of the periodic table as their solvent. [ ] The question arises as to whether or not lattice parameter is the only factor controlling the hardness of these alloys. There

Jan 1, 1943

By S. H. Ash

Mass production methods, although increasingly important for economic reasons, create new hazards, remove many hazards, and improve health and safety by reducing exposure and obtaining better supervision. Such methods must be efficient or be discarded. Skilled workmen are required who must be trained to utilize equipment that replaces picks, shovels, and explosives. The effects of working conditions on the health of workmen have long been evaluated in noncoal mines. Studies and action programs relating to environmental health hazards in the mineral industry have placed particular emphasis on dusts. The anthracite industry is conducting an action program on the problem of dust. Segments of the bituminous industry are now conducting similar investigations. An industrial hygiene survey of coal mining in the State of Washington has been conducted and the results published in 1949. (State of Washington, Department of Health, I. H. Bul letin 4.) Chest X rays were obtained from miners in the six major coal-producing counties. State Health Department mobile X-ray equipment was set up at most large mines. Participation was on a voluntary basis, and response was obtained from 70 percent. Important in successful mining safety programs are training programs for supervisors and workmen alike. These programs recognize that the employe is the focal point in injury prevention and are planned and function around him. During the war, industries had to compete with each other for workers and to obtain and hold good workers, working conditions had to be made attractive. The average age of the mine worker increased, and, contrary to what many expected, mining injury rates decreased rather than increased. To attract competent workers, risks to life and limb, as well as laborious tasks, have to be reduced, and an experienced worker is indispensable for safety. Young men are returning to modernized mines. Mass production methods and equipment are more to their liking; jobs are more remunerative, demand action, and require special training and skill that give them the mark of a craftsman. Such workmen can be taught safe methods.

Jan 1, 1950

By George M. Fowler

EVERY year it becomes more difficult to find new mining districts and new ore deposits. Nearly all of the important discoveries so far can be attributed to surface manifestations overlying the ore deposit. In the future greater skill will be necessary to find ore deposits that give little or no indication of their presence. Mining geology is making progress by broadening its attack upon mineralized regions, by including in its investigations studies of the relation of physical-chemical processes to ore precipitation and various phenomena that heretofore have not always been looked upon as major factors in the problems. Such, for example, are petrographic peculiarities that will help determine structure, aspects of strata or formations favorable or unfavorable to structural deformation or mineralization, and renewed studies of chert and dolomite. This broadening attack is not necessarily being directed to the study of large areas, but rather by doing extremely detailed work in three dimensions in relatively small critical areas to find the key to the structure, reasons for the manner of rock deformation, composition and texture of the rock, and other con¬trolling factors in the larger areas.

Jan 1, 1935

By Arthur Mackwell

The role of the precious metals is changing rapidly. They are becoming primarily materials of modern industry, and their decorative and monetary functions are diminishing in relative importance. Certainly gold is still the premier metal for jewelry, as silver is for silverware. But these uses are not growing nearly so fast as are the uses of these metals in a variety of industries. This is even more true of the platinum metals. Moreover, this is true despite the fact that the precious metals are highly expensive and liable to substitution by the base metals in cases where this is feasible. For the fact is that the physical and chemical properties of the precious metals make them relatively invulnerable to substitution; where they can be replaced by the base metals, they have been, and the opportunity for further substitution is, therefore, limited. SILVER In November 1969 the United States Treasury stopped minting the only remaining coin with any silver content. That was the silver-clad Kennedy half dollar, which had a silver content of approximately 40%. The step was taken out of necessity, because of the rising shortfall between world mine production and consumption. It was important to divert the 35 to 40 million oz of silver per year used for the minting of this coin into the open market, where it would be available for industrial consumption. This decision was important, not only for its practical effect but also for what it symbolized. Only four years earlier, in 1965, the Treasury had used 320 million oz of silver" for the full range of coinage. Now not an ounce of silver goes into the United States coinage. The reason is simple and yet complicated. For many years the U.S. Treasury had purchased silver at prices which provided a subsidy to domestic producers. As a result, silver producers were eager to sell to the Treasury, and that agency built up a huge supply of the metal -almost 2 billion oz by- 1961. But, as the free-market price neared $1.29, the basic melt value of the coinage, the Treasury became a seller of silver, not a buyer, and its stock was depleted rapidly. The Treasury lost more :than a billion ounces of silver in the years 1962 through 1965, and it continued to lose silver, both through coinage and through sales to consumers, through 1969. The Government continued to sell silver to consumers at the rate of 1.5 million oz a week, even after terminating the 40% silver Kennedy half dollar. But it was apparent that the Government stocks could last no more

Jan 1, 1976

By Sherwin Kelly

The prime objective of geophysical exploration is to promote the economical and rapid dis-covery of mineral or oil deposits of commercial value. To a few this concept as applied in min-ing may signify the direct discovery of ore-bodies, but to the geophysical engineer this latter Idea is one of the most insidious and detrimental misapprehensions which he has to combat. The destruction of this annoying obstacle to the progress of geophysical exploration reveals the kernel of truth behind it, that the exploration geophysicist has for the better part of two decades been concerned primarily with the discovery of mineral formations favorable to the occur-rence of commercial ore. There is a very real distinction here, since geophysical methods are capable of discovering certain mineral formations such as sulphide bodies or quartz veins, but are totally incompetent to predict whether or not they constitute ore; that is. whether or not they contain minerals of economic value in the amounts requisite to repay extraction. The art of geophysical exploration is now, however, rapidly outgrowing these early limita-tions. The rate of this growth will in large measure depend on the recognition by the mining industry of the fact that geophysics can play a role far wider and more important than it usual-ly does now, in guiding the future exploration and development of mineral deposits. It is my own firm conviction that as time marches on we will see the methods of applied geophysics turned more and more to the delineation of both minor and major structural features. The outlining of such features having a bearing on the probable loci of mineral deposition will be of inestimable value in guiding the development of a mining district. It is in this field that there will In-evitably occur a meeting and overlapping of the activities of the exploration geophysicists and

Jan 1, 1940

By Oliver Bowles

THE inorganic non-metallic minerals, that is, the non-metallics exclusive of coal, oil, gas and related minerals, constitute the basic raw materials for a number of essential industries. It is estimated that the value of the raw materials in this group produced in 1919, together with certain of the primary products ordinarily manufactured at the mine, exceeded $800,000,000. They are employed chiefly in the building, agricultural, and chemical industries. It has been estimated, by the Bureau of Mines, that approximately 00,000,000 worth of non-metallic minerals and their products were used in the building trades during 1918; with the great increase in building since that date and the increased cost of materials, the value of non-metals used in such industries during 1920 probably exceeded $500,000,000. The chief of these materials are cement, building stone, crushed stone, sand and gravel, clay products, lime, gypsum, glass materials, slate, talc and soapstone. In many of the producing industries of this great group, the waste is so great that the expense of handling it is an important item in the production cost. The utilization of waste is receiving unusual attention in many of the non-metallic industries at present. The most obvious advantages of such utilization are: (1) Conservation of mineral resources, (2) the removal of waste heaps that in many places obstruct development, (3) manufacture of new and useful products, (4) reduced production costs through elimination of a large part of the item of waste-disposal expense. In many industries there is keen competition between producers of various products used for the same purpose, so that advantage will accrue to the manufacturer who is able to reduce his production costs.

Jan 1, 1921

By J. E. Johnson

It is the purpose of the present paper, while not excluding chemical considerations, to deal more extensively with some of the physical and mechanical aspects of the blast-furnace process, and to point out its dependence, in these respects, on well-known laws. The quantity and cost of ore and flux required to make a ton of iron being determined by circumstances over which the furnace-man, under given conditions as to quality and quantity of product, has commonly little control, the principal item of cost, apart from the saving of labor, which he can aspire to reduce, is that of fuel. To determine the limits of possibility in this direction is clearly the first step in a practical inquiry; and this step is represented herewith in Fig. 1, a diagram showing the total useful effect obtained from a pound of fuel under various conditions, and thus permitting direct comparison, under any given conditions, between actual results and the maximum possible results. The following statements will explain the basis upon which this diagram has been constructed. One pound of fuel, containing 90 per cent. of fixed carbon (which represents average conditions), is taken as the unit. The degree of oxidation of the carbon is measured by the ratio of the two oxides of carbon contained in the top-gases. It is necessary to remember that a considerable quantity of carbon is brought in as carbon dioxide by the flux, and to take account of it and of its condition. It is here considered that the carbon dioxide liberated by the limestone does not affect the analysis of the top-gases, and that the ratio of CO to CO2 will remain unchanged by the addition of limestone; enough CO, being reduced by the solution

Jan 1, 1906

AN extremely successful meeting, under the joint auspices of the Ohio Section and the Iron and Steel Committee, was held at Cleveland on April 19 and 20, about one-half of those in attendance being from the Cleveland district and the other half from a distance. The morning session on April 19, C. K. Leith presiding, was opened by the presentation of the ad-dress of which an excerpt is printed on the opposite page. In the subsequent discussion R. A. Allen pointed out that the meeting had not been called "to blow the lid off the tariff" since that is only one of the many problems connected with the wisest utilization of man-ganese, and it was the purpose of this meeting to con-sider all those interdependent problems. The purpose of the tariff was to develop an adequate domestic sup-ply, and that result had not been accomplished. An-other important problem, linked with the tariff, is the need for assuring, while we are at peace, an adequate war supply of manganese, and at present this country has no such policy. D. F. Hewett said that his 3-months' trip in Europe last summer had impressed him with the fact that England had once been in the position United States now is in, of being the principal world's producer of all the more important minerals and with a declining reserve had gone on a free-trade basis. No one pointed out that, with the exception of tin, the present relative position of England is due more to an increase in pro-duction in other countries, rather than to a decrease of domestic production. J. Sharshall Grasty referred to recent development work-in Virginia where of 30 per cent easily concen-trated manganese ore about 300,000 tons has been blocked out and possible and probable ore amounting to 700,000 tons more is indicated.

Jan 5, 1927

By Ray Hammond Misener

THE purpose of this paper is to describe the installation of the pumping station on the 3314-ft. level of the Carlos Francisco mine of the Sociedad Minera Backus y Johnston del Peru, at Casapalca, Peru. However, so much preliminary work was necessary before the actual installation could be started that some of that work will be described briefly, in order to clarify the discussion of the main subject. The Sociedad Minera Backus y Johnston del Peru, a subsidiary of the Cerro de Pasco Copper Corporation, owns and operates a group of mines in the Casapalca district, of which the most important are the Carlos Francisco and the Aguas Calientes. These two mines, one mile apart, are connected on their 2100 and 2700-ft. levels. These are motor-haulage levels, equipped with 3 ½ -ton Baldwin-Westinghouse locomotives operating from a 260-volt d.c. overhead trolley. A 38-cu. ft. hopper-bottom car is used. Each mine has a 2 ½ -compartment, inclined (70°) winze shaft. The Aguas Calientes shaft, operating between its 2100 and 2900-ft. levels, is used only for men and materials; whereas the Carlos Francisco shaft, between the 1700 and 2700-ft. levels of that mine, is the main operating shaft for the district. All the ore from the Carlos Francisco and the Aguas Calientes mines is hoisted through the Carlos Francisco shaft. The ore produced in these mines is by-passed to the 2700-ft. level, where it is gathered by the electric trains, taken to the Carlos Francisco shaft and dumped into an ore pocket in front of the shaft. The ore is hoisted to the 1700-ft. level in 2-ton self-dumping skips and emptied into a 150-ton loading pocket. There it is loaded into electric trains and despatched to the concentrator through the Backus and Johnston tunnel, which is the main entry from Casapalca to all the mines in the Backus and Johnston group. DEVELOPMENT PROGRAM In 1934 the following development program was outlined for the Carlos Francisco and the Aguas Calientes mines: (1) to deepen the Carlos Francisco shaft from the 2700 to the 3400-ft. level, (2) to deepen the Aguas Calientes shaft from the 2900 to the 3300-ft. level, and (3) to connect the two shafts on the 3300-ft. level with a motor-haulage crosscut. Each mine was to be developed also on intermediate levels (2900 and 3100). The three levels were to be spaced 54 meters (177 ft.) floor to floor, measuring from the 2700-ft. level along the incline of the shaft. The Carlos Francisco mine, together with the section between it and the Aguas Calientes mine, produces 10,000 gal. of water per minute. A fault to the north

Jan 1, 1943

By R. W. Raymond

This name is applied to the present mining law, as enacted in 1872 and since, to indicate its leading characteristic—in which it differs from all previous mining laws of this or any other country. The earlier act, passed in 1866, was practically the first attempt of Congress to deal with the question of mining titles upon the public domain. It was framed after nearly twenty years of acquiescence on the part of the Government in the self-constituted tribunals, officials, rules, and customs of the mining districts. In its recognition of these, and in several other particulars, the act of 1866 was open to serious criticisms. It is the purpose of this paper, not to trace the history of legislation on this subject, or show in detail what were the faults of the earlier law, but rather, by a discussion of certain aspects of the present law, to point out how great a revoluition it has effected in the rights of mining locators, and to indicate some of the difficulties attending its application. In the attempt to correct the vagueness of the act of 1866 an entirely new elernent was introduced into the law, bringing with it a new set of difficulties. Under the act of 1866 and the miners' customs which it followed, the lode was the thing claimed and subsequently acquired by patent. And the claim to a given number of feet on the longitudinal course of the lode was rooted in 'a discovery of any part of the lode in any part of the claim. ("Extensions" could in many districts—perhaps universally—be located and claimed on the strength of the discovery in the principal claim to which they referred; but this is a point not essential to the present discussion.) It was not necessary to find the outcrop or the upper edge of a lode in order to lay a valid location upon it. An explorer, sinking a shaft and intersecting a lode not already discovered and claimed by another, could claim by that discovery the number of feet along that lode which the local laws might permit (not exceeding the maximum set by the United States statute) whether his sur-

Jan 1, 1884

By Edgar Trask

EACH branch of engineering seems to depend on the cooperation and contribution of some other branches to enable it to produce more efficient methods and appliances for man to use. The purpose of this paper is to show approximately the gain in efficiency of self-propelled merchant ships when steel of greater elasticity is substituted for mild steel in some of the strength members and alu-minum alloy is substituted in some of the parts where strength is not essential. The new steel will have some greater strength and a much greater elastic limit in the as-rolled condition, and must be readily weld-able under ordinary conditions of shipbuilding. Naturally, its cost may be more than mild steel, but if the demand is great that excess cost may be reduced to an amount that will make its use more economical than that of the present mild steel. There appears to be a well defined axiom in engineering today that to use the least power to carry a given load the weight of the carrier must be reduced to a minimum. This minimum must be, of course, consistent with the necessary strength, rigidity and durability and it must not be attained at an excessive cost where the fixed charges of the carrier will exceed the savings in, operating the motive power. Recent railroad equipment is a notable example of this, and in these trains alloy steels and aluminum together with less weight per horsepower of the power plant are reducing the weight of the carrier and hence the total power required for moving the paying load. Before considering the application of these metals to shipbuilding, it is well to explain some of the fundamentals of ship design.

Jan 1, 1936

By H. F. Dawes

In China all minerals are, theoretically at least, the property of the Emperor, and the Imperial permission must be got from him for the privilege of working them. A direct tax is levied on this privilege, and by simple command, the Emperor can close a mine at any time. Occult geomantic influences are a large factor in determining the opening or the arbitrary closing of a mine. The location with reference to points of the compass, graves and natural objects, may be really or professedly considered as indicating that those influences are favorable or unfavorable. The consequence, is, of course, that for the authorization and encouragement of any considerable enterprise, friends' at court, practical politics, and more or less bribery, are required. As a result, most Chinese mining is illicit, and is carried on in a small way only. Often along a single vein, or over a small section of mining country, a few individuals obtain rights over all the openings, most probably by loaning money to the head-men of the operators and holding the mines as security for the debt. In such cases, perhaps, for better security, all the ore is reduced in the works established by the creditors, who also handle all silver produced..As the head-men are, for the most part, improvident, and the laws and customs for the collection of' debts are stringent and peculiar, the " officemen" or creditors acquire in time what is practically an ownership of

Jan 1, 1892

By Blamey Stevens

(Butte Meeting, August, 1913.) THE following paper aims to make a full explanation of the phenomena of rock jointing. It may be unnecessary to give any general description of what are termed joints in rocks, but. Professor Geikie's clear and faithful generalizations are so illuminating that no excuse need be given for introducing the following and other quotations into this paper: "Almost all rocks are traversed-by vertical or highly inclined divisional planes termed joints. These have been regarded as clue in some way to contraction during consolidation (fissures of retreat) ; and this is no doubt their origin in innumerable cases. But, on the other hand, their frequent regularity and persistence across materials of very varying texture suggest rather the effects of internal pressure-and-movement within the crust."1 General Explanation.-In this paper I show that the phenomenon of jointing may to a large extent be accounted for by the pressure of the water contained in the pores of the rock. To understand this, each constituent grain of. the porous material may be considered to be separately compressed by the 'water which submerges it. As all the grains are held together by cohesion, the whole mass is contracted by this pressure. In an indefinitely extended mass, however, there must be a limit to the possible contraction without rupture, because the material is restrained from. moving freely by other material around its boundaries. The mass of rock thus becomes broken up. This phenomenon is known as " shrinkage " jointing. The terra "shrinkage" is an apt one, if it be understood that the shrinkage of the rock is often brought about by change of stress. Stresses.-The compressive component of water stress on the individual grains is evidently the same as that of the water with which it is in contact. This is so, both. before and after the jointing is formed. Before the jointing is formed there is, however, a tensile stress in one or more directions which keeps the material from contracting.

Jan 7, 1913

By N. J. Themelis, P. Spira

The efficiency of the reverberatory furnace operation in producing. slags of 1020 copper content depends on the mixing and flow conditions in the bath. Radioactize-tmcer tests have indicated the jkaction of bath volume engaged inflow and the mixing conditions in the bath. The factors controlling the flow pattern of slag have been classified as laminar transfer flow, natrsral convection, and flou, due to the rapid addition or removal of slag.. Similarity criteria for model studies have been developed. The pyrometallurgical processing of copper begins with the smelting of either flotation concentrates, or direct-smelting ores which have been partially roasted to calcines. These materials are generally smelted in a reverberatory furnace, Fig. 1, and separate into two liquid phases, a sulfide matte and an iron silicate slag. he matte is tapped and subsequently reduced to metallic copper in a converter, while the reverberatory slag is usually discarded without any further treatment. Molten slag from the converting operation is returned intermittently to the reverberatory in order to recover its high copper content (1 to 3 pct Cu). The reverberatory furnace is about 115 ft long by 30 ft wide. In general, the solid charge is fed at intervals through openings along the sides of the roof and forms sloping banks from which the molten materials trickle down into the bath; the charge banks extend over a length of about 70 ft from the firing wall. The depth of the slag and matte layers varies from smelter to smelter; in the Noranda furnaces, the slag depth is 24 to 30 in., while the depth of matte at the taphole is about 20 in. Apart from smelting, the functions of the reverberatory are to recover most of the copper content in the converter slag by physical and chemical interaction with the furnace bath, and to provide adequate time for optimum separation between matte and slag. The efficiency of these operations depends on the mixing and flow conditions in the bath and is reflected on the copper losses in the slag. In the present study, the reverberatory furnace is considered as an open-channel chemical reactor and the driving forces for material transport through the bath are examined by means of flow and mathematical models. FLOW CONDITIONS IN THE REVERBERATORY FURNACE To facilitate the study of mixing conditions in continuous-flow reactors, two idealized patterns of flow have been accepted by workers in this field.' The term "backmix" flow is used to describe complete and instantaneous mixing in the reactor (perfect mixing); all particles have the same chance of leaving the system, independently of their time of entrance, and the fluid is uniform in composition throughout the vessel. On the other hand, "plug" flow, or "piston" flow, assumes that a fluid element moves through the reactor without overtaking or mixing with fluid entering at an earlier or later time. In addition to the two idealized patterns of flow, "deadwater" flow accounts for that portion of the fluid which is moving so slowly that it may be assumed to be stagnant. According to the definition by evensppiel,' the cut-off point between active and stagnant fluid may be taken as material which stays in the vessel for a period twice the mean residence time. The flow patterns in real vessels may be approximated by a combination of the above flows. Thus, the vessel is assumed to consist of interconnected flow regions with various modes of flow existing between them. The flow pattern may be determined directly from the flow paths of fluid through the essel. -However, the difficulty of obtaining and interpreting such information has led to the alternate approach of determining the residence time distribution of fluid elements by means of stimulus-response studies. The stimulus is provided by introducing a tracer in the inlet stream and the response by the record of the change in tracer concentration in the exit stream from the reactor. Such tests have been conducted in glass tank furnaces using either chemical7"9 or radioactive tracers1'-'' and, in one case, experiments have been reported for a metallurgical furnace.'"

Jan 1, 1967

By Merton C. Flemings, Harold D. Brody

Analyses that include diffusion of solute in the solid phase are formulated to describe solute redistribution in dendritic solidification of metallic alloys. The analyses are based on conditions that include negligible undercooling before nucleation of solid phases, negligible increase of solute in advance of the tips of growing dendrites, complete diffusion within the liquid over distances the order of dendrite spacings, and a plate-like dendrite morphology. The classical nonequilibrium freezing equation, Cs = kCo(I - fS)k-l accurately describes solute redistribution between dendrite arms for the solidification processes considered, provided diffusion in the solid is negligible. To account for the effect of diffusion in the solid, an analytic expression is given which is similar inform to the classical expression. 172 addition, a numerical-analysis procedure is etnployed to examine in more detail the effect of diffusion both during and after solidification. The analyses are intended for application to solidification of castings and ingots to describe a) final solute distribution after solidification and cooling to room temperature (microsegregation) and b) local fraction solid as a function of ternperatcre within the solidifying casting or ingol. SOLUTE redistribution in cellular and dendritic solidification has been discussed quantitatively in recent papers'-3 and in a series of earlier work.4-6 However, none of the analyses developed have permitted close correlation of theory with final solute distribution (microsegregation) observed in castings and ingots. In this paper, discussion is given of approximations which may reasonably be made in mathematical treatment of microsegregation, and analyses are presented based on these approximations. Numerical results are given for Al-Cu alloys. In a second paper the analyses will be compared with exeriment.7 CLASSICAL ANALYSIS The classical quantitative treatment of solute redistribution within a closed "volume element" has been derived repeatedly, for example by Gulliver,4 Scheil,' and Pfann.' This "classical nonequilibrium solidification equation" is written for constant partition ratio: where Cs = interface composition of the solid when the weight-fraction solid within the "volume element" is fs (weight fraction, wt pct); k = equilibrium partition ratio; Co = initial alloy composition within the volume element (weight fraction, wt pct). Assumptions of Eq. [11 are: 1) There is negligible undercooling before nuclea-tion, or from curvature or kinetic effects. 2) There is no mass flow in or out of the volume

Jan 1, 1967

By D. Foster Hewett

The scope of this paper is the description of two districts in Peru in which deposits of vanadium have been found, and the consideration of much laboratory-work that I and others have done to determine the nature of these deposits. It is with regret that I present some of the data in a state of evident incompletion, particularly the analyses of a few of the minerals, which leaves some doubt as to whether the true nature of the migerals is understood. I make no apology, however, since in this case, as in many others referring to ore-deposits, conclusive opinions cannot be stated until a great amount of work has been done, and the deposit has been thoroughly exploited. I believe that the data and the tentative conclusions here presented indicate a unique and interesting condition which may assist others in work along similar lines; arid further, what is of more practical importance, stimulate a search for a metal which, though long considered rare, is probably so merely because proper care has not been taken to recognize it. An excellent bibliography on the occurrence of vanadium in nature is given by I?. W. Clarke in his paper, Data of Geochemistry;' and in the preparation of this paper 1 have consulted many of the references contained in the Bibliography of the Chemistry of Vanadium, by M. Moisan.2 A brief review of the subject having special reference to the metallurgy of vanadium is contained in the small book by P. Nicolardot.3 One of these vanadium-deposits has already been briefly. 1 Bulletin No. 330, U. S. Geological Survey (1908). 2 Chimie Minerale, vol. iii. (1905). 3 Le Vanadium (1905).

Jan 1, 1910