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By D. C. Bard

THESE notes are based on the megascopic study of a suite of 2,400 specimens of minerals and ores from the Butte mines, combined with field observations at intervals over a period of several years. The estimate of average vein composition is based on field acquaintance with the veins. It is probably correct in its broader proportions, and should be of use for comparison. Chemical and Mineral Composition of Butte Sulphide Vein. Matter. Per Cent. Oxygen 43.00-Quartz, rhodonite, rhodochrosite, barite, calcite, and hübnerite. Silicon 36.00-Quartz, rhodonite, and willemite (very rare). Sulphur 5.00-Sulphides of. iron, zinc, copper, lead,. and sulphates of barium and rarely calcium. Iron 5.00-Ferric sulphides (pyrite, bornite, chalcopyrite), also in sphalerite, tetrahedrite, and rarely hematite and siderite. Manganese, . . . . 2.00-Rhodonite, rhodochrosite, and hübnerite. Zinc, . . . . 1.00-Spha erite, very rare wurtzite and willemite, and tetrahedrite and tennantite.

Jan 8, 1913

By Hugh Henton

THIS paper is the result of an investigation made in association with Dr. Charles H. Fulton. Early in 1918 a search was started for methods of utilizing, in the manufacture of basic refractories, certain domestic resources in magnesites, dolomites, and magnesian limestones. Much information was collected during that year and during 1919 regarding magnesite and dolomite deposits. During 1920 and 1921 a research was made into methods of calcining dolomite and separating magnesia therefrom. Some success was attained and many new ideas were brought out in connection with the preparation and utilization of magnesia in the form of "caustic" or light-burned material as well as in the form of refractory or "dead-burned" material. Stimulated by this success, much advance has been made in manufacturing processes for the "plastic magnesia," so called, used for magnesia cement, stucco, flooring and otherwise in the structural industries.

Jan 3, 1926

At 8 o'clock on the evening of Thursday, July 25th, the special train chartered by the Provincial Government for the Institute's use, pulled out of Toronto. Ten parlor cars and two dining cars made up the train. The culinary arrangements were under the personal supervision of Mr. McConkey, of Toronto. [ ] The Hon. Frank Cochrane, Minister of Mines, Lands and Forests, was the efficient host of the party. He was assisted by the Hon. Dr. Pyne, Minister of Education, and by Mr. T. W. Gibson and Dr. W. G. Miller. On arriving at Cobalt, the delegates were met by the following Committee Mr. A. A. Cole, representing the T. & N. 0. Railway; Messrs. R. W. Leonard and D. B. Rochester, deputies from the Cobalt Chamber of Mines ; Messrs. Run¬ning and Martin, from the Cobalt City Council; Messrs. McLeod and Ferland,

Jan 1, 1907

By Reinhardt Thiessen

UNDER sulfur in coal, is usually understood that form of sulfur which is combined with iron and known as pyrite. It occurs in the form of halls, lenses, nodules, continuous layers, thin sheets, or flakes, both in horizontal planes and vertical cleavage fissures. But pyrites also occur as very fine microscopic particles, or nodules, disseminated through the compact coal. This form has had but very little consideration. Finally, there is sulfur in coal in an amicroscopic form (not visible with an ordinary microscope), probably combined with the organic matter that exists -in tile coal. This form has had considerable attention from a scientific standpoint, but has probably not been recognized enough on the economic side. One or the other, or both, of these two latter forms may comprise the larger part of the sulfur content of coal, especially after it has been washed or otherwise prepared for use.

Jan 9, 1919

By Joseph Zwierzycki

By an extension of drilling activities in 1938, the Polish oil industry succeeded not only in maintaining production but even in increasing it slightly. This increase, however, was from present oil reserves and not due to the discovery of any new fields. Most of the new wells were drilled in the Jaslo district, particularly in the Lipinki-Libuszal oil field, because of the shallow depth of the producing sands. At the Boryslaw field the 12,332 meters drilled could not compensate for the steady drop in production. A drilling campaign similar to that of the previous year in the Stanislawow district resulted in a slight decline of production. A number of the new wells have been subsidized by the Fund for the Advancement of Drilling2 in Poland. As the present sums at the disposal of this fund are insufficient for a great exploration program, they are chiefly used for the maintenance of the actual production. New wells on known folds, but more than 1000 m. outside the present productive areas, are entitled to a subsidy. Applications for wildcats outside the known productive areas have not been received in 1938. Even when the Polish oil industry was prosperous, wildcatting was not frequent and in their present impoverished condition the oil companies are no longer able to bear such financial burdens. The only way to start a large-scale drilling campaign on the still existing promising areas seems to depend on the granting of new substantial subsidies from the Treasury. Such measures are being considered by the Polish Government. It has been suggested that a fund for wildcatting might be raised by a small increase in the price of benzine. An advance of one grosz per liter of benzine would raise, on present home consumption of 108,000 kilogram-tons, about 1.3 million zloty, an advance of 5 grosze more than 6 million zloty.3 This small increase in price would hardly be felt by the motor-car owners, as it would mean an extra expense of 80 to 400 zloty in a year.

Jan 1, 1939

By Joseph Zwierzycki

By an extension of drilling activities in 1938, the Polish oil industry succeeded not only in maintaining production but even in increasing it slightly. This increase, however, was from present oil reserves and not due to the discovery of any new fields. Most of the new wells were drilled in the Jaslo district, particularly in the Lipinki-Libuszal oil field, because of the shallow depth of the producing sands. At the Boryslaw field the 12,332 meters drilled could not compensate for the steady drop in production. A drilling campaign similar to that of the previous year in the Stanislawow district resulted in a slight decline of production. A number of the new wells have been subsidized by the Fund for the Advancement of Drilling2 in Poland. As the present sums at the disposal of this fund are insufficient for a great exploration program, they are chiefly used for the maintenance of the actual production. New wells on known folds, but more than 1000 m. outside the present productive areas, are entitled to a subsidy. Applications for wildcats outside the known productive areas have not been received in 1938. Even when the Polish oil industry was prosperous, wildcatting was not frequent and in their present impoverished condition the oil companies are no longer able to bear such financial burdens. The only way to start a large-scale drilling campaign on the still existing promising areas seems to depend on the granting of new substantial subsidies from the Treasury. Such measures are being considered by the Polish Government. It has been suggested that a fund for wildcatting might be raised by a small increase in the price of benzine. An advance of one grosz per liter of benzine would raise, on present home consumption of 108,000 kilogram-tons, about 1.3 million zloty, an advance of 5 grosze more than 6 million zloty.3 This small increase in price would hardly be felt by the motor-car owners, as it would mean an extra expense of 80 to 400 zloty in a year.

Jan 1, 1939

By E. W. Parker

Anthracite, as sent to market, comes under three general terms of description: characteristics, source and size. Anthracite is generally classified as white ash, red ash, or Lykens Valley. The white ash coals are sometimes further described as "hard" or "free-burning." Lehigh white ash would come under the former description and Shamokin white ash under the latter. As a rule, it may be said that the nearer the origin of the coal to the western extremity of the anthracite region, the softer and more free-burning it is. Indeed, for many years the coal from Trevorton, at the western tip of the Middle Western field, was classified as "semianthracite" in the shipment reports. Lykens Valley coal is always a red ash coal, with a higher volatile content than the general run of anthracite, and consequently free-burning. The name does not exclusively indicate the neighborhood in which the coal is dug, but rather refers to the beds from which it is obtained. These beds lie, not above the Pottsville conglomerate, as is the rule, but encased in it. The extreme eastern limit of the Lykens Valley beds would seem to be about Tremont, in Schuylkill County, and the Natalie mine, near Mount Carmel. There are, of course, traces of these beds farther to the east, but they do not seem to be workable. There are as many as six of the Lykens Valley measures found in the conglomerate at some points, but to a large extent they are unworkable. Whether this coal is obtained in the Lykens Valley proper, where the beds were first identified, or from the Shamokin Valley, it is always Lykens Valley coal, and it has long been considered a premium coal, especially desirable for domestic use, particularly when a quick, hot kitchen fire is desired. Coals are, of course, frequently marketed under special names—Jeddo, Scranton, Kingston, Old Company Lehigh, Famous Reading, Lacka-wanna, etc.—which, of course, have the trade significance which their producers and vendors have built up. General Description of the Various Coals, with Name of Seam and Producing District This is partly covered in the paragraphs above. Lykens Valley coal is produced from one or another of the six Lykens Valley beds lying within

Jan 1, 1930

(SECRETARY'S NOTE.) The following discussion of the papers of Van Hise, Emmons, Lindgren and Weed, read at the Washington meeting, February, 1900, and printed on pp. 282 to 498 of this volume, comprises communications to the Secretary, received at various times before the Richmond meeting, February, 1901, and, for the most part, presented at that meeting. These communications are introduced at this point in the present volume, in order that they may precede the papers of Vogt, hemp, Lindgren, Rickard, etc., presented at Richmond, and therefore not forming part of the material considered in them. Since many of the contributors have mentioned in one communication several of the papers referred to, no attempt is here made to divide their remarks and distribute the fragments under separate headings. In each contribution, however, the several topics are indicated by subtitles. R. BECK,* Freiberg, Saxony : Prof. Veal Hise's Paper.-The paper of Prof. Van use (p. 282) represents a great step of scientific progress, in that the circulation of underground waters has never before been presented with such clearness, ill the light of modern chemical and physical knowledge. The theories of the formation of ore-deposits which follow the author's general survey of the currents and solvent power of atmospheric waters in the earth's crust do not, indeed, seem to be novel, being essentially an amplification of Le Conte's views; but the proofs adduced in their support are in many particulars so original that no one can read without profit this portion of the paper. Entirely new (though largely in agreement with the papers of Emmons and Weed, presented at the same meeting of the Institute) are the sections dealing with the formation of the rich sulphides of the precious metals, and especially the regeneration of normal sulphides, such as galena, etc., in vein-zones immediately beneath the ground-water level. Nevertheless, it appears to me that Prof. Van Hise, in the course of his most instructive exposition of unquestionable, yet still locally limited, phenomena, has been too much biased in favor of the " descensionists." This is indicated by the small importance which he attaches to the intimate genetic relation between epigenetic deposits and the plutonic hearths of the earth's interior.

Jan 1, 1902

By G. W. Toop

In a recent publication,31 Darken has derived an equation to describe thermodynamic behavior in ternary metallic solutions with compositions near pure component 1: Eq. [I] is understood to be a general equation, consistent with the ternary Gibbs-Duhem equation, which is proposed as a logical formalism in view of observed behavior in some binary metallic solutions31'32 rich In Eq. and am are constants obtainable from the 1-2 and 1-3 binaries. The parameter 023 may be determined from measurements on the ternary The purpose of this discussion is to compare Eq. [I) or [3] with other ternary formulations involving binary terms, within the regions of validity of Eqs. [I], [2], and [3]. First, the ternary point is considered to be at the intersection of two composition paths, one with constant N1 and another with constant N2/N3 as shown in Fig. 10. The terms in Eq. [3] may be related to the binary points shown by multiplying the first term on the right-hand side of Eq. [3] by N2 (1) /l -N1, the second term by the third term by and the fourth term by each multiplier being unity: It should be noted here that no suggestion has been made that either the binary or the ternary systems form regular solutions. However, Eq. [5] and hence Eq. [3] shows that the contribution made to the ternary excess free energy from the 1-2 and 1-3 binaries has the same form as for a regular ternary system.1 Before considering the term a23 for the above case, a second geometrical relationship is examined with the ternary point at the intersect ion of three composition paths with constant N1/N2, N2/N3, and Nl/N3, respectively, as shown in Fig. 11. For this geometry, ternary values of NZ and N3 in terms of the binary values shown may be substituted into Eq. [I]. Then by making use of identities of the form Eq. [6] contains terms that are similar to those in a ternary regular solution formulation34 based on the geometry shown in Fig. 11. Although at finite concentrations, unless the 1-2 and 1-3 binaries form

Jan 1, 1968

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

The studies of the mechanism of pre= cipitation and of the resulting property changes in aluminum-silver alloysl-3 have presented some new concepts of the aging reactioxl—concepts that may be fundamental in establishing a complete quantitative theory of age-hardening. With both aluminum-copper and aluminum-silver alloys, thin platelike aggregates form parallel to the Widmanstätten planes of precipitation.l,4 These platelets grow in lateral dimensions and in thickness with aging time until they arc thick enough to produce an X-ray diffraction line pattern. Their structure is that of a transition lattice which is coherent with the matrix, since the atomic spacings in the matrix and the precipitate are the same on each side of their common interface.2,4 The equilibrium precipitate forms later from and at the expense of the transition lattice. Since age-hardening occurs during the formation and growth of the transition lattice, the major contributor to the hardening no doubt is the stress condition in the matrix resulting from the matrix holding the precipitate in the coherent condition. The development of these stresses also appears to be responsible for an increase in the electrical resistance superimposed on the normal decrease resulting from a change in the concentration of the matrix during aging.3 The two consecutive reactions constituting the aging process are accompanied by characteristic microstructural alterations. The initial precipitation process results in the formation of a Widmanstatten figure, while the later transformation of the transition lattice to the equilibrium lattice is accompanied by a coalescence, in the case of aluminum-copper alloys,5 and by the appearance of light areas at the grain boundaries with aluminum-silver alloys showing a structural rearrangement of matrix and precipitate.3 This latter reaction is similar microscopically to the so-called "discontinuoils precipitation." Possibly discontinuous precipitation is a process that often if not always follows true precipitation of a coherent lattice and during which the transformation of the coherent transition lattice to the equilibrium lattice takes place accompanied by matrix recrystallization.3 Expermental Procedure The alloys were made using 99.97 per cent A1 or distilled magnesium, with

Jan 1, 1943

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

The studies of the mechanism of pre= cipitation and of the resulting property changes in aluminum-silver alloysl-3 have presented some new concepts of the aging reactioxl—concepts that may be fundamental in establishing a complete quantitative theory of age-hardening. With both aluminum-copper and aluminum-silver alloys, thin platelike aggregates form parallel to the Widmanstätten planes of precipitation.l,4 These platelets grow in lateral dimensions and in thickness with aging time until they arc thick enough to produce an X-ray diffraction line pattern. Their structure is that of a transition lattice which is coherent with the matrix, since the atomic spacings in the matrix and the precipitate are the same on each side of their common interface.2,4 The equilibrium precipitate forms later from and at the expense of the transition lattice. Since age-hardening occurs during the formation and growth of the transition lattice, the major contributor to the hardening no doubt is the stress condition in the matrix resulting from the matrix holding the precipitate in the coherent condition. The development of these stresses also appears to be responsible for an increase in the electrical resistance superimposed on the normal decrease resulting from a change in the concentration of the matrix during aging.3 The two consecutive reactions constituting the aging process are accompanied by characteristic microstructural alterations. The initial precipitation process results in the formation of a Widmanstatten figure, while the later transformation of the transition lattice to the equilibrium lattice is accompanied by a coalescence, in the case of aluminum-copper alloys,5 and by the appearance of light areas at the grain boundaries with aluminum-silver alloys showing a structural rearrangement of matrix and precipitate.3 This latter reaction is similar microscopically to the so-called "discontinuoils precipitation." Possibly discontinuous precipitation is a process that often if not always follows true precipitation of a coherent lattice and during which the transformation of the coherent transition lattice to the equilibrium lattice takes place accompanied by matrix recrystallization.3 Expermental Procedure The alloys were made using 99.97 per cent A1 or distilled magnesium, with

Jan 1, 1943

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

THE studies of the mechanism of precipitation and of the resulting property changes in aluminum-silver alloys1-3 have presented some new concepts of the aging reaction-concepts that may be fundamental in establishing a complete quantitative theory of age-hardening. With both aluminum-copper and aluminum-silver alloys, thin platelike aggregates form parallel to the Widmanstätten planes of precipitation.1,4 These platelets grow in lateral dimensions and in thickness with aging time until they are thick enough to produce an X-ray diffraction line pattern. Their structure is that of a transition lattice which is coherent with the matrix, since the atomic spacings in the matrix and the precipitate are the same on each side of their common interface.2,4 The equilibrium precipitate forms later from and at the expense of the transition lattice. Since age-hardening occurs during the formation and growth of the transition lattice, the major contributor to the hardening no doubt is the stress condition in the matrix resulting from the matrix holding the precipitate in the coherent condition. The development of these stresses also appears to be responsible for an increase in the electrical resistance superimposed on the normal decrease resulting from a change in the concentration of the matrix during aging.3 The two consecutive reactions constituting the aging process are accompanied by characteristic microstructural alterations. The initial precipitation process results in the formation of a Widmanstätten figure, while the later transformation of the transition lattice to the equilibrium lattice is accompanied by a coalescence, in the case of aluminum-copper alloys,5 and by the appearance of light areas at the grain boundaries with aluminum-silver alloys showing a structural rearrangement of matrix and precipitate.3 This latter reaction is similar microscopically to the so-called "discontinuous precipitation." Possibly discontinuous precipitation is a process that often if not always follows true precipitation of a coherent lattice and during which the transformation of the coherent transition lattice to the equilibrium lattice takes place accompanied by matrix recrystallization.3 EXPERIMENTAL PROCEDURE The alloys were made using 99.97 per cent Al or distilled magnesium, with

Jan 1, 1943

By William Hume-Rothery

I need not say how much I appreciate the honor of being asked to lecture to you, and how much I would thank you for your kind invitation. It is encouraging to feel that the abnormal restrictions of the war have been relaxed sufficiently to allow a free exchange of scientists between our two countries, and I hope that some of you will be persuaded to go to England, and to visit us at Oxford, so that I may repay a little of the kindness I have received from you. As this is one of the first lectures since the end of the war, I have thought it well to describe some of the advances in the theory of alloys which were made in the years between the two World Wars. From the point of view of theoretical science, these years have been of outstanding interest in the history of metallurgy. They have been years in which the development of new and more accurate experimental methods has led to the revelation of many new facts. At the same time, the theoretical developments have enabled some of these facts to be viewed as parts of a general scheme, and we may say that some of the foundations of metallurgical science have been laid. This work was naturally stopped by the Second World War, and it can therefore be reviewed as one definite stage in the development of our Science. To illustrate the new advances, I shall deal mainly with the alloys of copper and silver, since these have revealed many of the general principles. taken, and copper had been found to crystallize in the face-centered cubic structure (Fig I). The determination of this structure naturally was of immense importance in the understanding of our subject, because it meant that we were at last in a position to appreciate the underlying structure out of which the crystal of copper was built. The earlier science of metallography had shown that in many alloys of copper the addition of a second metal in not too large proportions resulted in the formation of a homogeneous alloy which was regarded as a solid solution of the one metal in copper. Fig 2, for example, shows the so-called equilibrium diagram of the copper-zinc alloys, and here you will see that there is a solid solution of zinc in copper extending to something of the order 35 to 40 at. pct zinc.

Jan 1, 1947

By William Hume-Rothery

I need not say how much I appreciate the honor of being asked to lecture to you, and how much I would thank you for your kind invitation. It is encouraging to feel that the abnormal restrictions of the war have been relaxed sufficiently to allow a free exchange of scientists between our two countries, and I hope that some of you will be persuaded to go to England, and to visit us at Oxford, so that I may repay a little of the kindness I have received from you. As this is one of the first lectures since the end of the war, I have thought it well to describe some of the advances in the theory of alloys which were made in the years between the two World Wars. From the point of view of theoretical science, these years have been of outstanding interest in the history of metallurgy. They have been years in which the development of new and more accurate experimental methods has led to the revelation of many new facts. At the same time, the theoretical developments have enabled some of these facts to be viewed as parts of a general scheme, and we may say that some of the foundations of metallurgical science have been laid. This work was naturally stopped by the Second World War, and it can therefore be reviewed as one definite stage in the development of our Science. To illustrate the new advances, I shall deal mainly with the alloys of copper and silver, since these have revealed many of the general principles. taken, and copper had been found to crystallize in the face-centered cubic structure (Fig I). The determination of this structure naturally was of immense importance in the understanding of our subject, because it meant that we were at last in a position to appreciate the underlying structure out of which the crystal of copper was built. The earlier science of metallography had shown that in many alloys of copper the addition of a second metal in not too large proportions resulted in the formation of a homogeneous alloy which was regarded as a solid solution of the one metal in copper. Fig 2, for example, shows the so-called equilibrium diagram of the copper-zinc alloys, and here you will see that there is a solid solution of zinc in copper extending to something of the order 35 to 40 at. pct zinc.

Jan 1, 1947

By C. S. Corbett

EARLY in the development of every oil field, the operators of relatively large tracts of land must decide upon a spacing plan for the wells to be drilled upon their respective tracts. Usually it is desirable to have a system of regular spacing laid out over the entire tract, making such adjustments as may be necessary near land boundaries. Unless the dip of the producing formation is very steep, the equilateral triangular arrangement is the one most generally preferred, for the very good reason that it gives the maximum amount of drainage area for the wells up to the limit at which mutual drainage interference begins. Assuming that the equilateral triangular pattern is to be used, there still remains to he decided the matter of distance between wells. Many variable factors enter into the problem of proper spacing, some of which are physical and some economic. It is not the purpose of this paper to discuss these factors, as that has been done in several comprehensive articles during the past few years. In the end the decision must be based upon an estimate of the relative importance of various factors which apply to the field in question and to economic conditions in the oil industry at the time the development is getting under way. Even if the best possible spacing distance should be chosen when the problem arises, changing economic conditions and variation in physical conditions in different parts of the field may cause the original choice to become more or less unsatisfactory. Obviously, it is advantageous, once a spacing plan has been adopted, to avoid alteration of it as the field becomes better known or as conditions in the industry change, and yet be able to vary somewhat, the acreage per well in extending the area of development. Or, it may be desired to provide for an ultimate spacing considerably closer than conditions seem to warrant early in the development of the field. With these contingencies in mind, it is of interest to examine the possibilities which the equilateral triangular system affords. Orientation of Coordinate System In this system the well locations may be considered as the inersectionst of three sets of coordinate lines, the lines of each set intersecting those of the other two sets at 60. For convenience in placing such a system

Jan 1, 1930

By T. Yamasaki, S. Usu

Adsorption of potassium dodecyl xanthate from aqueous solutions on artificial and natural zinc sul-fides was studied by means of infrared absorption spectroscopy. The adsorption species and their stabilities varied depending upon the conditions of the surfaces of the zinc sulfides. Adsorption products were analyzed after they had been removed from the surface with pyridine. Zinc dodecyl xanthate was confirmed for surfaces covered with oxidized products while dodecyl alcohol and carbon disulfide were detected on purified or weakly oxidized surfaces. It is of great significance to study the adsorbed species of collectors on the surface of sulfide minerals with a view of increasing our understanding of the mechanism of flotation. Compared with other methods, infrared spectroscopy promises to be of particular value in determining the nature of the species adsorbed at the mineral/solution interface since it gives direct identification of the adsorption products; and, furthermore, it has an advantage over the electron diffraction technique which has been employed in similar problems in that infrared spectroscopy utilizes radiation of very low energy so that the probability of changing the unstable surface films during examination should be correspondingly decreased. Infrared spectroscopic studies concerned with sulfide mineral flotation have already been reported by several investigators on zinc sulfide-hexanthi01' and lead sulfide-xanthate2,3 systems. The purpose of the present study was to investigate the adsorption of potassium dodecyl xanthate (KDX) at the zinc sulfide-aqueous solution interface by means of infrared spectroscopy. Rarely is the pure zinc sulfide-xanthate system encountered in practical flotation since zinc sulfide is usually activated with small amounts of certain metallic ions, such as copper ion. However, investigation of the pure zinc sulfide-xanthate system appeared promising for studying the fundamental mechanism of the adsorption of xanthate on the sulfide minerals. Although there are few cases where xanthates having an alkyl radical higher than hexyl are employed in practical operations, KDX was used in this study since it was reported that the adsorbability of xanthate on zinc sulfide was increased with an increasing number of carbon atoms of the alkyl radicals.4 EXPERIMENTAL Samples: Experiments were made on artificial zinc sulfide and natural sphalerite. The artificial zinc sulfide was obtained commercially from Dainihon Toryo Co. as a fluorescent pigment of the purest grade A. Considering the fact that there are often cases where the surface of sulfide minerals are apt to be oxidized so that the adsorption of xanthate at sulfide mineral/solution interfaces may be substantially affected, two different procedures were employed in preparing the samples of the artificial zinc sulfide. 1) The zinc sulfide was washed with hot concentrated ammonium chloride solution (300 g per liter) to remove surface oxidation products and followed by washing with deoxygenated hot distilled water by centrifugation until the constant electric conductivity of the solution was reached (Sample I) (specific conductivity of the solution = 8.6 x l0-5 ohm-' cm-'). 2) Sample I in a suspension of 5% by weight was oxidized with a 1.5% aqueous hydrogen peroxide solution for about one hour, and then was washed with distilled water as mentioned in the preparation of Sample I (Sample 11) (specific conductivity of the solution = 1.0 x 10"4 ohm-' cm-'). Both Samples I and II were dried under vacuum and stored in a vacuum desiccator. The specific surface areas of the samples determined by the BET method using carbon dioxide gas were 19 x l04 cm2 per g for Sample I and 35 x l04 cm2 per g for Sample 11. In addition, a sample which was derived from Sample I was also prepared. In 40 ml of 3 x 10-2 M zinc sulfate solution was placed 2 g of Sample I for 2 hours, washed with distilled water by successive centrifugation until no sulfate ion could be detected and dried under vacuum (Sample 111). The purpose of this treatment will be described later. Natural sphalerite was carefully selected by hand, ground in a mechanical agate mortar for about 40

Jan 1, 1965

By C. M. Young

Bituminous coal piled in heaps or bins frequently undergoes a process of spontaneous heating as the result of the absorption of oxygen. It seems probable that the first absorption of oxygen by coal which has not previously been exposed to the air may occur as a condensation or a combination of oxygen in some form which does not result in the production of carbon dioxide, but slow combustion soon begins. The absorption of oxygen is accompanied by an increase of temperature, and this by an increased rapidity of absorption; hence the dangerous condition proceeds from bad to worse, until the kindling point is reached, unless the process is interrupted. A dangerous rise of temperature can be prevented by excluding oxygen, by increasing the bulk of coal in proportion to its surface exposed, or by circulating enough air to dissipate the heat produced. The storage of coal, in practice, varies from almost complete exclusion of oxygen, by storing under water, to such freedom of access as exists when the coal is stored in open piles. Oxygen available for absorption by coal is supplied by the air in the interstices between lumps and by additional air which may enter the pile through circulation. The size of the coal largely affects both of these supplies; for if the fragments are small the spaces between them constitute a small percentage of the total volume, and little oxygen will be available unless the circulation of air brings in a fresh supply, while with large fragments the percentage is relatively large; circulation also is much easier through a pile of coarse lumps. In the case of lump coal, although a large amount of air may be present, the exposed surface is comparatively small and there is little opportunity for the absorption of oxygen to be so rapid as to cause dangerous heating. Attempts have been made to prevent heating by allowing a sufficient circulation of air to carry off the heat generated; obviously this method cannot be applied to fine sizes nor mixed sizes. When storing coal at the University of Illinois, an attempt has been made to use so much fine coal and to pack it so thoroughly as to prevent circulation of air, while also reducing the original air in the pile so as to prevent heating. This method has been fairly successful, but in some

Jan 1, 1918

By S. R. Elliott

The principles of the caving system, as they apply to mining soft iron-ore deposits, are well known, as this method has been in use for many years. It is, however, necessary to give a general description of it before describing the Athens method. The shaft and surface equipment should be placed at a sufficient distance from the orebody, so that the caving and pulling of the surface will not disturb the operations of the mine. Levels are started at the proper intervals, and when raises are completed, slicing commences at the top of the orebody and progresses downward. The necessary precautions are taken to avoid the occurrence of large open rooms and it is customary to break sufficient capping to form a mat to prevent heavy falls of ground from crushing through to the lower sublevels and endangering the lives of the workmen. Slicing is continued, and when sufficient width and length are undercut, the capping commences to cave, and in time a settlement occurs at the surface. As soon as this caving commences, the pressure on the timber increases; after it extends to the surface, the amount of pressure has a certain relation to the depth. In other words, the pressure increases with the depth, but not in direct proportion. At great depths, such as are found at the Athens, 2500 ft. (760 m.), the pressure might be so excessive that the cost of keeping working places open would be prohibitive. The actual caving of the surface in a deep mine, with a great thickness of capping, is slow and often takes years to accomplish. After sufficient width and depth have been undercut, the capping starts to break away, but, through arching, large masses of rock fill the opening, support the capping, and retard the continuation of caving. Caving to the surface is, therefore, retarded until either a sufficient thickness of the orebody is removed, or the width and length of the undercut part have been greatly increascd. I wish to emphasize this fact of slow caving, for it is on this principle that the success of the Athens system largely depends. Assuming that work is begun at the top, in this case at an elevation of about 1500 ft. (456 m.); that there is a thick bed of sand saturated with

Jan 1, 1922

By J. S. Wakeman

INTRODUCTION The primary purpose of comminution circuits in the mineral industry is to reduce an ore to a particle size that will permit separation of the valuable minerals from its gangue constituents. Wide variations in the mineral content and physical characteristics can and do occur throughout a given mineral deposit From the standpoint of their effects on the comminution characteristics of an orebody, these variations may not be identified by the normal sampling and analysis procedures utilized to delimit an orebody and to characterize its grade distribution. The proper design of a comminution circuit for a mineral deposit is very important to the success of that enterprise. It is also an expensive unit process both from the standpoint of capital and operating costs. It is, therefore, essential that any sampling program be designed to identify the variations that may occur that will affect this circuit. Because of the variety of comminution systems that are available, it is also essential that the sampling and subsequent evaluation program be sufficiently comprehensive to identify potentially inappropriate systems or flowsheets. It would be impossible to describe in a single chapter the techniques and approaches that should be utilized for sampling every type of orebody. Each orebody is unique and requires a sampling and testing program designed to its specific requirements for exploration, characterization and circuit design. The following is a general discussion of the guidelines to be used and considerations to be made in establishing such a program. SAMPLE SELECTION When sampling an ore deposit for the purposes of equipment and flowsheet selection for comminution, it is important that the sample composites for grind testing be chosen on the basis of how they will affect the comminution circuit rather than just how they might affect the subsequent metallurgical operations. For example, grindability, classification and liberation size characteristics are more important to the comminution circuit than ore grade. Mineral deposits may contain a multiplicity of ore types that can vary extensively in the dissemination of minerals and optimum liberation size requirements; and may also vary as much as 100% in ore hardness. The accumulation of samples for grind characterization should be done in such a way as to allow the identification of this variation. A proper mineralogical evaluation of the samples obtained to characterize an ore deposit can be a great aid in identifying the individual ore types within the deposit

Jan 1, 1982

By P. E. Demmler

PHOSPHORUS combines with copper in various proportions, forming true alloys, some of which are of commercial importance. These materials find wide application as deoxidizers and as a means of introducing phosphorus into other alloys, as in phosphor-bronze. Phosphor-coppers containing 10 and 15 per cent. of phosphorus are the commercial grades that are most generally offered. Each has certain advantages when used in making other alloys. The 10 per cent. grade of phosphor-copper has an advantage over the 15 per cent. in that it has a much lower melting point and can be prepared by certain methods with a much lower loss in phosphorus. The 15 per cent. grade has the advantage of lower freight rates per unit of phosphorus and, by the method to be described, a uniform product can be prepared with practically no loss of phosphorus. Alloys of copper and phosphorus containing any desired percentage of phosphorus lower than 15 per cent. can be prepared by melting together the requisite amounts of copper and 15 per cent. phosphor-copper. Processes for making phosphor-copper may be divided into two classes as follows: (1) Those depending on the smelting of phosphate rock or superphosphate of calcium with copper or copper-bearing materials, and coal or other carbonaceous material; (2) those depending on the direct combination of metallic copper and elemental phosphorus. A number of formulas for preparing phosphor-copper according to the first method have been published. The Metal, Industry' gives-the following: Superphosphate of calcium, 60 lb.; granulated copper, 301b.; finely powdered coal, 10 lb. Similar formulas are given by Brannt2 and others, and detail 'variations are covered by patents, such as those of L A Jeffs3 and H A Webster.4

Jan 8, 1920