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By Rush Sill

THE processes of superficial alteration depend on physical conditions, environment, geologic history and chemical and mineralogical composition. Superficial alteration is confined particularly to the zone of shallow circulation, as this is the zone of solution; its rocks are open and the circulation within it is compara-tively rapid. The enrichment of ore deposits in this zone, therefore, is of special interest. The depth of the vadose, or zone of shallow circula-tion, is variable, because its lower limit depends on the variable level of ground water. In moist, hilly countries its depth varies from a few feet to several hundred feet. In arid regions where the rainfall is low and evaporation great, this zone may extend to much greater depths. Permeability of the deposits . is essential to the downward migration of metals. In rocks, that have been fractured since the primary ore was deposited, there is generally more extensive and deeper enrichment than in ore deposits that have been but slightly fractured. A warm climate increases chemical action and abundant rain fall is favorable to enrichment. Low relief and slow erosion give long periods of weathering and thorough leaching.

Jan 9, 1922

By Robert S. Shoemaker

Receiving the Richards Award is undoubtedly the most memorable event in my entire life. There should, however, be more names engraved on it. These are the names of men who were my teachers (but not all of the academic variety) and my friends, each of whom had a part in my ever continuing education and thus have a part of this award. There was Bill Caldwell who made me into a chemist, and Will Shorey who added a lot of ore dressing. There was Rush Spedden who put me to work in his minerals research lab, Joe Brennan who made me turn my research into plant practice, and Tom Meek who sent me all over the world on metallurgical jobs. Bob Cheatham and Abe Dor taught me to try to give the client what he needs rather than what he wants, while Ed Malouf and Casey Davis always gave their particular brand of advice at exactly the right time. And, lastly, there was Leo Abell and Frank McQuiston, both fine metallurgists and the best friends a man could have. In addition to those I have mentioned, there are literally scores of others I would like to acknowledge with my sincere appreciation.

Jan 6, 1974

By Robert C. Edmiston

The measurement of temperatures in exploratory drill holes yields information on regional and local geothermal gradients and mean surface temperatures. This data may be beneficial to the mining geologist interested in the occurrence and oxidation of metallic sulfide minerals or to the mining engineer interested in subsurface temperatures or water movement. Additionally, the estimation of mean surface temperatures by the projection of thermal gradients to the ground surface provides data on which to evaluate infrared imagery as an exploration tool. Temperature measurements in 30 diamond drill holes in the Silver Bell mining district of Arizona show that a regional geothermal gradient of 2.45°C per 100 m increases to 3.03°C per 100 m near the ground surface. It is also found that an anomaly in the mean annual surface temperature of 0.5°C is associated with the shallow occurrence of disseminated sulfides. Changes in the geothermal gradient due to topography, water circulation, and formation changes also occur.

Jan 1, 1976

By T. A. Rickard

The lodes of Cripple Creek, Colo., partake of the composition of the geological formation which they traverse. The prevailing rocks are andesitic breccia, lying upon granite, and also bodies of phonolite, trachytic phonolite, nepheline-basalt, etc., penetrating both the granite and the breccia. At Kalgoorlie, in West Australia, the prevailing rock is schistose, and has not been certainly identified, though microscopic sections indicate the probability that it was originally an acid eruptive. The lodes are essentially bands, more highly schistose than the encasing rock, and impregnated to a notable degree with disseminated pyrites and secondary calcite. During 1899 Cripple Creek produced 425,590 tons of ore, having a gross value of $15,658,254; during the same period the output of Kalgoorlie was 467,048 tons, valued at $17,724,587. In chemical composition, the ores at Cripple Creek and Kalgoorlie, respectively, present differences equally interesting to the petrographer and the metallurgist. In both cases we have to deal with altered eruptives as the matrix of the ore; but the much older rock of Kalgoorlie has undergone more decompo-

Jan 1, 1901

By Henry D. Hibbard

Henry D. HibbaRd, Pittsburgh, Pa,: This is a most interesting and instructive paper, some of whose lessons should find immediate application. It points out how fuel-consumption is to be decreased in open-hearth practice, by changes in the plan of the furnace. To look first at the greatest item of loss, radiation, it is seen that thicker brick-work is advisable to lessen this. Especially is this true of the roof, made at present, almost universally, only 9 inches thick to prevent cutting. Now that high roofs, well above the course of the flame, are becoming general, and the average melter is better able to judge the temperature of his furnace, that reason has less force; and we may build roofs 18 inches thick, or perhaps better cover the usual 9 inches with an equivalent layer of sand, which has the advantage of following the arch as it rises and falls with the different degrees of heat. The side-walls of the hearth, usually 131/2 inches thick, may also he thickened up to 18 inches, and the door-linings to 7 inches; and the heat thereby saved will be valuable, while its absence from the working-platform will be much appreciated by the workmen.

Jan 1, 1892

By I. Iwasaki, R. H. Heerema

The presence of calcium and magnesium ions in iron ore pulps that are upgraded by selective desliming can result in indiscriminate flocculation of both iron oxide and siliceous gangue slimes. The removal of these alkaline earth cations in pulp solutions by chemical precipitation was ineffective as a means of deflocculation of quartz. It was shown by using various techniques (electron micrographs, abstraction, and streaming potential measurements, and cationic flotation tests) that heterocoagulation between the precipitates [Mg(OH)2, hydroxyapatite, and CaCO3] and quartz particles was the reason behind that observation. In addition, the precipitates adversely affected the recovery of quartz by cationic flotation, due to slime coating, a case of heterocoagulation. Magnesium hydroxide produced a uniform layer of coating across the quartz surface, while hydroxyapatite and calcite produced discrete, localized deposits dotting the surface.

Jan 1, 1981

By Warren Weaver

SOME of the advantages of the inductive method of electrical prospecting were emphasized in a paper by Dr. Max Mason.1 Since this emphasis was misunderstood by some to indicate a too exclusive interest in inductive methods, we are especially happy to help correct this impression by reporting on some of our work on surface potential methods. EARTH CURRENTS AND SURFACE POTENTIALS When two electrodes, A and B, are placed on the surface of the ground a distance d apart, and a 100-volt battery is connected across the elec- FIG. 1.-LINES OF CURRENT FLOW AND SURFACE POTENTIAL IN MILLIVOLTS IN THE CASE OF A HOMOGENEOUS EARTH. trodes, current flows from the positive electrode A to the negative electrode B. The current does not pass directly from A to B along the straight line joining these two points. In fact, a negligible amount of the

Jan 1, 1928

By Charles E. Nelson

In considering the types of scrap that are processed into secondary magnesium, it is important to point out that the greatest proportion of this material is fabrication, foundry and machine shop scrap that is generated during the conversion of magnesium products into the finished article. This material, then, is largely of the same composition and quality as the original ingot or heat of metal except as it may be mixed with other compositions or metals in the fabricating process. Insofar as such materials can be processed back into secondary ingots or final products which meet the composition and property standards required of the original virgin stocks, then it seems reasonable that such products are fully equivalent to the primary products. With these premises then, it is the intent of the present discussion to consider briefly some of the methods whereby scrap may be generated, segregated, shipped, and processed in such a manner that the final products will be equivalent to virgin materials. Some information on the effects of impurities will be given in order to aid in the evaluation of these products. SCRAP GENERATION The method by which scrap is generated serves in a rough way to classify the resulting materials in terms of how they may be handled and recovered. These methods will be dealt with briefly. Machining operations such as milling and turning undoubtedly provide the great-

Jan 1, 1943

By Wilson Blake

As a part of a USBM-ASARCO cooperative rock-burst research program, a burstprone stope pillar at the Galena mine was successfully destressed. Destressing was accomplished by blasting a single line of long holes in the footwall of the vein. As a result of destressing, the pillar was fractured and softened; hence it yielded, releasing a large amount of stored elastic strain energy nonviolently. In addition, the high stress in the pillar was shifted out around the stope walls and in the sandfill. Both broad-band microseismic monitoring and seismic velocity surveys were used to evaluate the destressing test. The mechanics of destressing were determined by finite element computer model studies of destressing. Results of the field destressing test agreed remarkably well with the predicted results from the computer model.

Jan 1, 1973

By I. N. Zavarine

THE present paper is a continuation of the work on the relationship between the magnetic and the phase transformations in carbon steels during quenching. An account was given by the author in a previous paper It of an investigation of this relationship during a continuous quench. The experimental difficulties then encountered prevented a conclusive proof of the existence or absence of such a relationship. The conclusions of the previous paper were derived indirectly. The present paper deals with the same problem, but the method of attack is modified. The technique developed by Davenport and Bain2 in their well-known study of austenite transformation at subcritical temperature was adopted in the present investigation. They have shown that the austenite to martensite transformation can be caused to proceed at a relatively slow rate by quenching steels into a hot metal bath. Slowing down of the rate of transformation, together with an observation by Lewis3 that a eutectoid steel can be preserved in the nonmagnetic state by such quench-ing, pointed out a possibility of a study of both transformations under more favorable conditions than previously described. The preliminary steps were connected with the technique of the hot bath quench. To study this phase of the present work a modification of the apparatus previously describe1 was used. The modification con-sisted in the use of a hot quenching bath instead of brine, and in fixing the secondary and the primary coils of the apparatus in a stationary position in and around the bath. Tubular specimens, as in the previous investiga-tion, were heated in a suitable furnace to a temperature in the austenitic.

Jan 1, 1935

By H. N. Thomson

(Butte Meeting, August, 1913.) GENERAL. THE Tooele plant. off the International Smelting & Refining Co. is situated at the mouth of Pine canyon, Tooele county, Utah. It is connected with the main line of the San Pedro, Los Angeles & Salt Lake railroad by the Tooele Valley. railway, and is about 7 miles from Tooele Junction. Fig,. 1 is a general view of the plant. The copper plant has been in operation since July, 1910, and the first blast furnace it the lead plant was blown in on Feb. 29, 1912. The location of the plant was selected on sloping ground with the idea of using gravity to the fullest extent and thus keeping labor at a minimum. Practically the entire plant is constructed of steel, reinforced concrete, and. brick.

Jan 7, 1913

By Ernest Darby

IF the correct balance between fuel and air is maintained in an open-flame furnace,1 little chemical action may be expected between the products of combustion and the metal being melted. Physical changes in the metal are the object of the melting operation, and indirectly, under certain conditions, may be the cause of subsequent chemical actions. If sufficient heat has been introduced into the metal to bring about the change from the solid phase to the liquid phase, and still further from the liquid to the vapor phase, the metal vapor in all probability will be carried from the furnace by the exhaust and rapidly combined with the oxygen of the outside air. The charge being melted in the furnace may contain elements which are chemically inactive at normal temperatures but which will form compounds at the elevated temperatures of the metal bath, or even at a lower degree. Such indirect chemical actions are very confusing and often lead to incorrect conclusions regarding furnace atmospheres. In the open-flame furnaces used in the melting of bronze, the furnace atmosphere is spoken of as being either neutral, oxidizing or reducing in its effect upon the metal. A neutral atmosphere, as mentioned, is generally considered as the atmosphere of the furnace that will produce melted bronze, neither oxidized nor gassed. It is in effect an atmosphere which is not directly the cause of any chemical action. In such an atmosphere absolutely pure metals may be melted and poured without the absorption of gases or the formation of metallic oxide. The metal has undergone a simple, physical change.

Jan 1, 1930

By David J. Dunn, Richard G. Martin

Of many physical parameters critical to design of grinding processes, impact of grinding media is among the most difficult to measure or predict. Yet impact of falling grinding balls, pebbles, or rods accomplishes the fine grinding essential to metallurgical recovery of most important minerals. Unfortunately, the same impacts that break ore fragments deform or crack grinding mill liners. A project was undertaken at Climax Molybdenum Company to measure impact forces in operating ball mills so that they might be used to calculate stresses in liner materials and be correlated with service performance of mill liner alloys. Towards that end, a method of measuring impact forces on ball mill liners using an instrumented grinding ball has been developed. Preliminary tests show that impact forces and contact stresses imposed on bare mill liners are quite high but are greatly reduced by cushioning when coarse ore particles are crushed between balls and liners. Compressive and shear stresses induced in liners not protected by coarse ore are so severe that deformation or minute subsurface cracking are inevitable in all but the small production grinding mills, regardless of mill liner alloy strength or hardness.

Jan 1, 1979

By Richard Lee

SINCE the economics in the blast furnace resulting from enriching iron ores are so great, much attention, has been paid during the past few years to the various methods of concentrating lean ores, and, as the concentrated ore is usually of extreme fineness, various methods . of agglomeration and sintering, of more or less value, have been put 'into operation. The resulting agglomerated concentrates are generally obtained in the form of briquettes or nodules. The briquettes naturally divide themselves into two classes: (1) those made by the mixture of some binding agent, and then formed into briquettes under great pressure; and (2) those made by sintering the concentrates, the latter either being formed into bricks before exposure to heat or the sintered mass broken into fragments afterward. Of the first class I will not speak, as they are not used on an extensive scale in this country. The second class of briquettes, or those made by sintering, are simply masses of melted or fused silicate and oxide of iron mingled with more or less silicates of aluminum, lime, and magnesia. The fact that the material in a briquette is sintered is proof positive that there are no pores in the material. There are, however, quite a number of holes of greater or less diameter through the substance of the briquette. They are not pores in the common acceptance of that term as applied to ores by furnacemen, as the sides of the holes and channels are fused. In reality the material is simply mill cinder. It is practically untouched by the gases in the upper part of the furnace, and the iron has to be reduced by solid carbon in the boshes and hearth. Briquettes sometimes show a little saving in fuel in the furnace over an ore mixture of large lumps, but that saving is made simply because, owing to the numerous holes and channels through the mass, the briquette is practically composed of numerous small or fine lumps, and, as is well known, the finer the

Jan 10, 1913

By M. J. McPherson

Having worked on the thermodynamics of air/liquid-water mixtures passing through the surface fans of deep mines, I find this paper of great interest and congratulate the authors on producing it. There are two matters, however, deserving discussion. First, the authors have described the classical theory of fog formation with fogging occurring at "supersaturation." In fact, the process of fog formation begins well below 100% humidity. The more strongly hygroscopic nuclei in the atmosphere will attract water molecules and begin to grow at a relative humidity perhaps as low as 70%. The process is a dynamic one with both condensation and evaporation taking place throughout the mixture on microscopic liquid surfaces. As saturation is approached, the rate of condensation accelerates rapidly producing the familiar reduction in visibility. Hygroscopic nuclei are present in all natural atmospheres and under the appropriate conditions of pressure and temperature, will produce clean fogs. However, if the air is polluted by particulates from combustion or other processes then the resultant coagulation with growing liquid particles may produce dense (and sometimes photochemical) smogs. It is this process that is likely to occur in underground mines when moist air is cooled below dew point. Second, the authors have summarized very well the individual measures that might alleviate the problem. In particular, I agree that neither heating nor refrigerating the air, by themselves, provides a satisfactory solution. However, there is a combination of these that provides a neat and effective control of fog formation. This involves a small, self-contained refrigeration unit within a duct but without the usual external heat rejection facility. The air is cooled below dew point and, hence, dehumidified on passing over the cold evaporator coils. The heat from the condenser is rejected back into the air down-stream from the water eliminator, as shown in [Fig. 1]. The duct configuration can be designed to create good mixing at the outlet.

Jan 1, 1984

By Leonard P. Skolnick

PROPERTIES of materials containing a hard con-stituent dispersed in a metallic matrix are dependent on the distribution of the hard phase.'-' The grain growth of titanium carbide in liquid nickel was studied in order to understand microstructural development in this and similar systems. Smith" has examined the influence of surface energy on the distribution of phases in alloys. The grain growth of tungsten carbide in cobalt has been the subject of many conflicting theories. Those prior to 1950 have been summarized by Goetzel.' Recently, Gurland and Norton3 and Gurland8 have indicated that growth occurs primarily by diffusion through the liquid phase in order to lower the inter-facial energy between the carbide and the liquid metal. In the development of the Ti-C-Ni ternary phase diagram, Stover and Wulff9 have shown that both eutectiferous dendritic titanium carbide, and primary titanium carbide which had developed crystals of cubic symmetry, were rounded by heating below the solidus, and that if primary carbide was already present the typical eutectic decomposition products were not formed. Experimental Procedure The infiltration technique was used to study the grain growth of titanium carbide in nickel. In contrast to sintering, infiltration more readily assures uniform dispersion of the two phases, and the problems associated with mixing by milling; i.e., mill contamination, breakdown of original carbide size in the operation, development of interfering surface films, etc., are avoided. In addition, the complicating effect of densification by shrinkage is eliminated. The titanium carbides used were commercial grades. Their chemical analyses, size distributions and shapes are summarized in Table I. Size analysis was conducted by microscopic count on a minimum

Jan 1, 1958

By L. S. Panyity

The State of Ohio is among the pioneers in the production of oil and gas. Numerous anticlinals, such as the Macksburg, Cow Run and Newport, have been thoroughly developed, and the pools found in connection with them are quite in accord with the structural theory. Numerous oil and gas pools found in the Berea sand, however, demand a different explanation. The study of these pools belongs to the sub-surface geologist, as it is possible to understand the factors controlling "off-structure" accumulations only after a careful study of well records. By carefully analyzing the various conditions over a large territory, it is possible to understand the otherwise meaningless mass of data that one may have at hand, and put it into tangible shape, from which various conclusions may be drawn. The territory here discussed includes Belmont, Guernsey, Muskingum, Noble, Monroe, Morgan, Washington, Athens and Meigs counties, containing the majority of the prolific oil and gas pools of the Carboniferous system in southeastern Ohio. The general dip of the strata is to the southeast, the entire territory lying on the northwestern flank of the Appalachian geosyncline. The best known oil- and gas-producing horizon in the territory is the Berea sand, which lies near the lower part of the Mississippian, with the Sun-burry shales (the coffee-shales of the driller) above, and the Bedford shales below it. The Bedford is underlain by the thick Ohio shales. The Ohio and Bedford contact is considered to be the dividing line between the Carboniferous and Devonian systems. The Berea is one of the most persistent of recognizable oil and gas horizons; its outcrop has always been found in its expected place, and it has always been penetrated whenever the drill went deep enough. It is not expected, however, even of the most uniform formations, that no lithological variations should occur, and the Berea is no exception. Nevertheless, there appears to be a certain regularity in its variation, the main features of which directly affect the accumulation of petroleum.

Jan 1, 1920

By J. C. Bartlett

(Read at the Wilkes-Barre Meeting, May, 1877.) THE following discussion was suggested by an experiment of Mr. Krom, the manufacturer of air-jigs, to illustrate the superiority of air over water as a medium of concentration. The paper is written in the interest of no system of concentration, but simply to test the experiment, and, perchance, to add something to the general fund of information on the subject. To speak of testing an experiment by a theoretical discussion, may seem a misuse of terms, but the theories concerning falling bodies and the resistance of fluids are pretty well crystallized into laws, which may properly be used to show where experiments which seem to refute them were improperly performed, and that instead of refitting they only corroborate. It is well known that a sphere of galena 1/8 inch in diameter, and a sphere of quartz 1/2 inch in diameter, are equal falling in water ; that is, these two spheres, being placed together in a column of water at rest or in motion, will practically remain together, falling or rising together, or remaining in suspension. Mr. Krom, to show that these

Jan 1, 1878

By C. L. Colburn

THE statutory requirements of the States and the district rules are, broadly speaking, similar. There is just enough difference to make it tantalizing. DIFFERENCES IN STATE LEGISLATION GOVERNING THE LOCATION OF MINING CLAIMS Discovery Discovery is the first step in the location of the claim. The provision of the Revised Statutes (2320) is, "No location of a mining claim shall be made until the discovery of the vein or lode within the limits of the claim located." Strictly speaking, discovery may be defined as the finding of ore or metalliferous rock in place in a well-defined vein. This definition was too strict, so discovery extended later to cover such indications of the presence of ore, within rock in place, as would justify an experienced miner in spending his time and money with a reasonable expectation of finding ore in paying quantities. According to Colorado statutes a discovery must show a well-defined crevice; in Arizona, a lode, deposit, or mineral in place; in Montana, a well-defined crevice or valuable deposit; in Nevada, a lode or deposit of mineral in place. It is wrong to require a discovery. An honest prospector, wishing to obey the law, finds himself compelled, in most cases, to evade this point. In Clear Creek district, Colorado, a quartz seam will constitute a discovery; in Butte, a red capping; in Leadville or Ely, it is any place where a man can find a piece of vacant ground big enough upon which to sink a 10-ft. hole. If the vein or deposit outcrops a man can show a discovery, but if it does not outcrop it is foolish to compel him to show one; and this point has been gently side-stepped. Any hole 10 ft. deep now constitutes a discovery. It is no use having laws that the people cannot consistently obey. No sane man will dig unless he expects to find mineral, and he should be protected while digging. He should be required to show that he has mineral ground only when he comes to patent.

Jan 6, 1914

By Herbert Ives

THE incandescent gas mantle is of considerable interest from the standpoint of temperature measurement because it presents a series of apparent contradictions to the established laws of radiation on which are based some of our best methods of temperature determination. One of these contradictions is that the mantle of least brightness (of the commercial thoria-ceria group) is the one having the highest temperature; this, though explicable without any violation of radiation laws, was long a stumbling block to the understanding of the performance of the mantle. Another anomaly is that the energy radiated by the mantle decreases with the rise of temperature, thus apparently invalidating total radiation methods of pyrometry, based on the fourth-power law. The discussion of methods of measuring mantle temperature which follows, is largely taken from an extensive study of the physics of the Welsbach mantle. 1 The incandescent gas mantle consists of a skeleton of refractory oxide of very light weight and open structure, formed by the ignition of a cotton or silk "stocking" previously thoroughly impregnated with salts of certain rare earths. The mantle of commerce is a mixture of approximately 99 parts of thorium oxide with 1 part of cerium oxide. This mixture, discovered largely by accident, gives luminous radiation many times greater than that from either of the constituents taken alone. It is customary to speak of the thoria as the "base" and the ceria as the "colorant," and the commercial mantle represents one of a family in which an oxide of low emissive power is employed as a base, which will assume a high temperature, while a small amount of some other oxide of high visible emissive power is added, which will reduce the temperature of the mantle but little. This is, in general, the most efficient- way, from the standpoint of visible emission, to utilize a substance of high emissive power in the visible spectrum. But it is not necessary. that two substances should be employed to produce a radiator

Jan 9, 1919