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By James M. Barker

Sulfur is a nonmetallic element of great physical and economic importance to the world. It is widely but sparingly distributed throughout the hydrosphere, lithosphere, and biosphere. Sulfur is the tenth most abundant element in the universe and eighth most abundant in the sun. In the earth's crust, which is mainly igneous, it ranks 14th, but is eighth or ninth in sediments (Kaplan, 1972; Stanton, 1972). It apparently is very abundant in the core of the earth, because it is a strong chalcophile, and it is fifth in abundance in stony and iron meteorites (Field, 1972) where it occurs as trolite (FeS). In ancient times sulfur was called brimstone, literally "burning stone." Today the term brimstone is used interchangeably with the term elemental sulfur. Shelton (1979) summarized most of the common definitions of terms, grades, and specifications for the sulfur industry as follows (with minor additions): Sources of Sulfur: Combined sulfur-Sulfur that occurs in nature combined with other elements. Cupriferous pyrites-Pyrite containing relatively minor amounts of copper sulfide minerals. Hydrogen sulfide-A toxic gas (H2S) occurring in natural gas and petroleum. Involuntary sulfur-Sulfur produced primarily as a result of legislative or process mandates. Native sulfur-Sulfur that occurs in nature in the elemental (uncombined) form. Nonferrous metal sulfides-Copper, lead, zinc, nickel, and molybdenum sulfides that are processed for their metal content. Organic sulfurs-Complex organic sulfur compounds occurring in petroleum, coal, oil shale, and tar sands. Pyrites-Iron sulfide minerals that include pyrite, marcasite, and pyrrhotite. Sulfate sulfurs-Sulfur in anhydrite and gypsum. Voluntary sulfur-Sulfur produced in response to market forces. Basic Sulfur Products Produced and Marketed: Acid sludge-Contaminated sulfuric acid usually returned to acid plants for reconstitution. Brimstone-Synonymous with crude sulfur. Bright sulfur-Crude sulfur free of discoloring impurities and bright yellow in color. Broken sulfur-Solid crude sulfur crushed to -8 in. Byproduct sulfuric acid--Sulfuric acid produced as a byproduct of a metallurgical or industrial process, generally relating to combined sulfur sources. Crude sulfur-Commercial nomenclature for elemental sulfur. Dark sulfur-Crude sulfur discolored by minor quantities of hydrocarbons ranging up to 0.3 % carbon content. Elemental sulfur-Processed sulfur in the elemental form produced from native sulfur or combined sulfur sources, generally with a minimum sulfur content of 99.5%. Formed sulfur-Elemental sulfur cast or pressed into particular shapes to enhance handling and to suppress dust generation and moisture retention. Frasch sulfur-Elemental sulfur produced from native sulfur sources by the Frasch mining process. Hydrogen sulfide-Associated with natural gas or petroleum and produced at refineries and coke oven plants; used to make sulfuric acid or recovered sulfur. Liquid sulfur-Synonymous with molten sulfur. Liquid sulfur dioxide-Purified sulfur dioxide compressed to the liquid phase. Molten sulfur-Crude sulfur in the molten phase.

Jan 1, 1983

By D. F. Hewett

ALTHOUGH most persons will agree that an individual or a nation can profit from the experience of other individuals or nations, there is always room for debate over the degree of similarity of their past and present conditions and of their future problems. Noting the increasing interest that Americans are showing in our mineral problems, I have felt that we could profit from reviews of the experiences in mineral exploitation acquired by the industrial nations of Europe. Whether we can learn much from Europe's experience in exploiting such minerals as petroleum may be debatable, but certainly, with a record of metal production extending back nearly 3000 years, Europe should hold much of value for America. A trip to Europe in 1926 permitted me to visit 28 mining districts, of which about half are now or have been in times past outstanding sources of several metals. The districts range from England to Greece and from Spain to Poland. To summarize briefly my impressions of these mining districts, as well as such reactions to the thought and life of Europe as so short a visit permits, I shall only venture the opinion that Americans can review with great profit the ideas and actions of Europeans, with regard not only to the production of metals but to many expressions of life. I believe that America has made and is making new contributions to the art of living, as well as to the arts of mining and metallurgy, but in so far as Europe is and has been a laboratory of economic, social and political experiments, the results she has attained deserve the thoughtful attention of America. I have come to believe that many of the problems that harass Europe lie in our path not far ahead. I have therefore hoped that a review of metal production in Europe in the light of its geologic, economic and political background may -serve to clear our vision with regard to our own metal production.

Jan 1, 1929

By M. J. Salkind

In order for fiber composite materials to find extensive use in structures, it is necessary to develop techniques for joining these materials. Riveting and adhesive bonding are two possible techniques which have been investigated although the former is less desirable because the low shear strength of most matrices makes this type of joint subject to bearing failure. Welding is an effective means of joining, especially for high-temperature applications where ad-hesives are weak; however, there are significant limitations placed on welding composite materials. The commonly used fusion welding techniques will find less use for joining composites because the two phases are often unable to stand exposure to such a stringent environment. In the case of eutectic composites, fusion welding will completely destroy the controlled microstructure. Solid-state techniques such as diffusion bonding offer potential success with certain design requirements placed on such joints. Since the primary mechanism of load transfer from matrix to fiber is shear parallel to the fibers, little load can be transferred across a butt-welded interface perpendicular to the aligned fibers. Successful joint designs must have a component parallel to the fibers to allow a shear area for load transfer. Configurations such as lap and scarf welds are likely to be successful. This note describes some results of experiments with diffusion-bonded joints in A13Ni whisker-reinforced aluminum. The composite material, prepared by unidirectional solidification of the A1-A13Ni eutectic, is described elsewhere.'-' It consists of aligned micron size whiskers in a matrix of aluminum. Since it has been shown that the microstructure of

Jan 1, 1969

By Elmer A. Jones

Like the caboose on the end of a long freight train L made up of mineral and metal processing and consuming industries, the mining industry progresses according to the movement of the train to which it is coupled. Sometimes the caboose rolls smoothly; occasionally it bumps along on the ties; almost always it is under criticism from someone for being too small, too large, too expensive, foolishly progressive, or hopelessly out of date. We who ride in the caboose are used to the rough by now, but it is nice now and then to have a bit of the smooth. Last year the train of industrial production rolled ahead swiftly and smoothly, and, except for a hot-box caused by strikes in copper mines, so did the caboose. As is brought out elsewhere in this issue, the outlook for 1956 is for more of the same.

Feb 1, 1956

By R. M. Rose, D. P. Ferriss, J. Wulff

The effect of orientation on the stresses, nctivation energies, and activation volumes for yielding and plastic flow of tungsten single crystals was investigated. Tensile tests showed the proportional limit to be a function of orientation: crystals whose tensile axes were near the [I10} direction were roughly three times as strong as [loo] crystals. The [ 1101 crystals showed low strain hardening and displayed yield phenomena, whereas the other orientations yielded smoothly and showed considerable strain hardening. The fracture mode was cleavage, except for crystals near the [1101 , many of which gave "chisel" fractures at 300°and 373°K. The activation energy for yielding was approximately one- half an electron; volt at all orientations, and the volume of activation was (12 to 14)b3, except near the [1101, where it was 7b3. Activation volumes generally increased after yielding. The most common theoretical models for yielding and strain hardening of bcc metals were. found to be insufficient to the intepretation of the observations here in. An explanation is proposed, based on the dislocation reaction dislocation networks and jogs, md jogs formed during plus tic flow. PRECLSE knowledge of the Drocesses involved in the yielding and plastic flow of the refractory metals is essential to the formulation of models for their flow and fracture. Despite this need, the single -crystal investigations, especially of tungsten, have been sparse. Slip occurs at low temperature, according to schadler,i in <111> directions on {110) planes; as the temperature rises to room tempera-

Jan 1, 1962

By R. A. Wolfe, H. W. Paxton

Self-diffilsion coefficients for cr51 and Fe55 in 12 pct Cr-Fe and 17 pct Cr-Fe for Fe55 in chromium, and for Cr51 in vanadium have been measured. The results are compared with other values for the Fe-Cr system, and with the various theories of diffusion in hcc metals. Some empirical correlations are discussed between Do and Q in hcc systems, or, expressed differently, the constancy of ?G*/T solidus for seveval bcc metals and alloys is noted. It appears very probable that a vacancy mechanism is operative in bcc metals, hut this cannot he stated with certainty. THE great bulk of work on diffusion in metals, both experimental and theoretical, was for many years concentrated on those with close-packed and, in particular, fcc lattices.1,2 There appears to be little doubt that the mechanism of diffusion in these solids is vacancy migration, leading to mass transfer and in substitutional solid solutions to a Kirken-dall effect.3,4 For bcc metals, the picture is much less clear. The Kirkendall effect certainly occurs in several alloys.5-10 However, attempts to understand the factors contributing to the pre-exponential in the usual expression for the diffusion coefficient D =D, exp {-Q/RT) by extension of ideas useful in close-packed lattices have not always been successful. Zener,11 Leclaire,12 and Pound, Paxton, and Bitlerl3 have suggested that various forms of ring diffusion may be important in some bcc metals. For close-packed metals, Do is usually about 1 sq cm per sec and Q - 35Tm kcal per mole (Tm = melting temperature in OK). The theory of Pound et al. suggests for ring diffusion that Do may be about 10-4 and Q, although difficult to calculate with any precision, would be significantly less than 35 T,. The experimental results on self and solute diffusion in ? uranium14,15 and ß zirconium,10 and for solutes in 0 titanium,17 and possibly for self-diffu- sion in chromium below about 0.75 T,," gave some credence to this theory. However, not all bcc materials display low values of DO and Q, and the exceptions were not predicted by any theory. Furthermore, it has recently become apparent that, in bcc materials, log D is not always linear with T-l if a sufficiently wide range of temperature is studied.16,18 This variation may be such that Q may increase18,19 or decrease20 with increasing temperature. The present work was undertaken in an attempt to provide further diffusion data on bcc metals, and to try to understand the factors which contribute to differences in behavior between the various elements. For part of this work, the Fe-Cr system was chosen since it is of considerable technological importance, and data on 12 pct Cr and 17 pct Cr alloys appeared well worthwhile to supplement that existing for the remainder of the stern.18,22 The diffusion of Fe55 in chromium was studied as an example of a more or less "normal" tracer element in a possibly abnormal host lattice. Finally, no data were available for vanadium, the neighbor of chromium in the periodic table, because of lack of a suitable isotope so cr55 was used as a tracer in a few preliminary experiments. For convenience, we shall refer to elements whose Do and Q are low compared to those predicted by Zener&apos;s theory as "anomalous". PROCEDURE This investigation determined self-diffusion rates by means of radioactive tracers and the integral-activity method first utilized by Gruzin.23 In this method a thin layer of radioisotope of the diffusing element is plated or coated onto a planar surface of the diffusion sample, which is then given an isothermal-diffusion annealing treatment. The determination of an activity-penetration curve involves measuring the residual activity of the specimen after each successive layer or section has been removed parallel to the original planar surface. The method used here is essentially the same as that used by Gondolf18 and Kunitake.21 Two radioactive tracers, cr51 and Fe55, were used in this investigation. Diffusion coefficients were determined for the diffusion of one or both of these tracers in four different materials, viz., Fe-12 wt pct Cr alloy, Fe-17 wt pct Cr alloy, chromium, and vanadium. The diffusion samples had nominal dimensions of 1.5 cm diameter and 0.5 cm thickness. The grain size was several millimeters for the Fe-Cr alloys and at least 1 mm for the chromium and vanadium samples. Accurately planar surfaces

Jan 1, 1964

By L. B. Herring, Harold Decker

The South Texas area, discussed herein, represents districts 2 and 4 of the Texas Railroad Cominission and extends from Jackson, Lavaca, and Gonzales Counties on the northeast to the Rio Grande River, comprising a total of 26 counties.$ The present boundaries of this district do not coincide with those of earlier reports published in the annual volumes of Petroleum Development and Technology. The war, in its various ramifications, determined and controlled all the phases of the oil and gas industry. Priorities for material and governmental subsidies determined all new operations. New Pools In our opinion, the combine&apos; quantity of crude and distillate reserves added in &apos;943 approached Or possibly exceeded the amount produced. Thirty-five new pools were added to the area&apos; Of these, five have significant reserves and ten offer possibilities of containing consequential reserves. The largest proven reserve discovered during the year was the Slick pool, on the DeWitt-Goliad County line. This is also the most important Wilcox discovery to date in the area. The most significant extension was at Willimar, Willacy County. Other important extensions were developed at Agua Dulce, Seeligson, and Odem. Except for the Porter field, in Karnes County, the Laredo trend, which produces lrom the Jackson and Yegua, proved very disappointing, and this pool is o:C secondary importance. The Scott and Hopper pool, Brooks County, has only orie well, but offers excellent possibilities of becoming an important discovery. It represents at this time the major Frio discovery of the year. The Hobson pool, Karnes County, is not a major reserve, but can be classed as important in that it produces at a shallow depth from the Wilcox. This proves that the potential area of production for this zone occupies a broad trend. Gas and Condensate During the year construction was begun on only one recycling plant, this being in the Sejita field, Duval County. Several others were colltemplated, but no actual operations were begun. The most important development in recycling was the rebuilding of old plants to allow for the fractiona-tion of isopentane, n-butane, isobutane, and propane. Heretofore all pentanes plus have been marketed as cLdistillate,n only a minor portion of the butanes being isolated and sold for fuel purposes. All these new the except propane, are considered vital to the war effort and propane is being marketed as fuel gas. In other instances propane is being isolated and then pumped back into the gas reservoirs for storage. It is anticipated that the demands for this product will increase in the future. Drilling in the Wilcox trend during the year showed the existence of valuable gas

Jan 1, 1944

By L. B. Herring, Harold Decker

The South Texas area, discussed herein, represents districts 2 and 4 of the Texas Railroad Cominission and extends from Jackson, Lavaca, and Gonzales Counties on the northeast to the Rio Grande River, comprising a total of 26 counties.$ The present boundaries of this district do not coincide with those of earlier reports published in the annual volumes of Petroleum Development and Technology. The war, in its various ramifications, determined and controlled all the phases of the oil and gas industry. Priorities for material and governmental subsidies determined all new operations. New Pools In our opinion, the combine&apos; quantity of crude and distillate reserves added in &apos;943 approached Or possibly exceeded the amount produced. Thirty-five new pools were added to the area&apos; Of these, five have significant reserves and ten offer possibilities of containing consequential reserves. The largest proven reserve discovered during the year was the Slick pool, on the DeWitt-Goliad County line. This is also the most important Wilcox discovery to date in the area. The most significant extension was at Willimar, Willacy County. Other important extensions were developed at Agua Dulce, Seeligson, and Odem. Except for the Porter field, in Karnes County, the Laredo trend, which produces lrom the Jackson and Yegua, proved very disappointing, and this pool is o:C secondary importance. The Scott and Hopper pool, Brooks County, has only orie well, but offers excellent possibilities of becoming an important discovery. It represents at this time the major Frio discovery of the year. The Hobson pool, Karnes County, is not a major reserve, but can be classed as important in that it produces at a shallow depth from the Wilcox. This proves that the potential area of production for this zone occupies a broad trend. Gas and Condensate During the year construction was begun on only one recycling plant, this being in the Sejita field, Duval County. Several others were colltemplated, but no actual operations were begun. The most important development in recycling was the rebuilding of old plants to allow for the fractiona-tion of isopentane, n-butane, isobutane, and propane. Heretofore all pentanes plus have been marketed as cLdistillate,n only a minor portion of the butanes being isolated and sold for fuel purposes. All these new the except propane, are considered vital to the war effort and propane is being marketed as fuel gas. In other instances propane is being isolated and then pumped back into the gas reservoirs for storage. It is anticipated that the demands for this product will increase in the future. Drilling in the Wilcox trend during the year showed the existence of valuable gas

Jan 1, 1944

By Henry S. Mackay

The interesting paper recently submitted by Messrs. Tobelmann and Potter1 shows that chemical problems have developed which are of great interest in this new and important branch of metallurgy. Those who realize what a process of this kind really involves will agree that it deserves a better name than &apos;(leaching process." The word leaching conveys the idea that the copper is simply leached out of the ore with acid and then precipitated on iron; the chemistry of such a process would be of little interest. As, however, during the first year&apos;s operation of this plant 24,400,532 lb. (11,067,837 kg.) or about two-thirds of the produce, was electrolytic copper, while 7,992,033 lb., or about one-third, was cement copper, it would seem more appropriate to term the process electrochemical. It further appears, from the particulars given, that efforts have been made to have the entire production in the form of electrolytic copper. This could be done if the chemistry of the problem were kept in balance, so that it would not be necessary to discard any solutions that carried copper and acid of commercial value. A process, such as that under consideration, in which the copper is precipitated from solution by electrolysis, the solvent being at the same time regenerated, is one that requires special chemical and electrochemical knowledge and experience if all the copper in solution that has been extracted from the ore is to be successfully and economically produced as electrolytic copper. The object of this paper is to discuss, from the practical and theoretical standpoints, the chemical and electrochemical problems involved in the working of a process of this kind, and which must be solved to keep it in chemical and electrochemical equilibrium. In such a process, if the chemical balance is maintained, a solution can be used alternately as a solvent for the copper in the ore and as an electrolyte of high efficiency for the precipitation of the copper. To maintain the chemical equilibrium and so attain this result, the process must be so controlled that the solu-

Jan 1, 1921

By H. J. Ramey

The wellbore acts as a storage tank during drawdown and build-up testing and causes the sand-face flow rate to approach the constant surface flow rate as a function of time. This effect is compounded if non-Darcy flow (turbulent flow) exists near a gas wellbore. Non-Darcy flow can be interpreted as a flow-rate dependent skin effect. A method for determining the non-Darcy flow constant using this concept and the usual skin effect equation is described. Field tests of this method have identified several cases where non-Darcy flow was severe enough that gas wells in a fractured region appeared to be moderately damaged. The combination of wellbore storage and non-Darcy flow can result in erroneous estimates of formation flow capacity for short-time gas well tests. Fortunately, the presence of the wellbore storage eflect permits a new analysis which can provide a reasonable estimate of formation flow capacity and the non-Darcy flow constant from a single short-time test. The basis of the Gladfelter, Tracy and Wilsey correction for wellbore storage in pressure build-up was investigated. Results led to extension of the method to drawdown testing. If non-Darcy flow is not important, the method can be used to correct short-time gas well drawdown or build-up data. A method for estimation of the duration of wellbore storage effects was developed. INTRODUCTION In 1953, van Everdingen and Hurst generalized results published in their previous paper3 concerning wellbore storage effects to include a "skin effect", or a region of altered permeability adjacent to the wellbore. Later, Gladfelter. Tracy and Wilsey4 presented a method for correcting observed oilwell pressure build-up data for wellbore storage in the presence of a skin effect. The method depended upon measuring the change in the fluid storage in the wellbore by measuring the rise in liquid level. To the author&apos;s knowledge, application of the Gladfelter, Tracy and Wilsey storage correction to gas-well build-up has not been discussed in the literature. It is, however, a rather obvious application. Gas storage in the wellbore is a conlpressibility effect and can be estimated easily from the measured wellbore pressure as a function of time. Several approaches to the wellbore storage problem have been suggested. As summarized by Matthews, it is possible to minimize annulus storage volume by using a packer, and to obtain a near sand-face shut-in by use of down-hole tubing plug devices. Matthews and Perrine have suggested criteiia for determining the time when storage effects become negligible. In 1962, Swift and Kiel&apos; presented a method for determination of the effect of non-Darcy flow (often called turbulent flow) upon gas-well behavior. This paper provided a theoretical basis for peculiar gas-well behavior described previously by Smith. Recently, Carter, Miller and Riley observed disagreement among flow capacity k,,h data determined from gas-well drawdown tests conducted at different flow rates for short periods of time (less than six hours flowing time). In the original preprint of their paper, Carter et al. proposed that the discrepancy in flow capacity was possibly a result of wellbore storage effects. Results of an analytical study of unloading of the wellbore and non-Darcy flow were recorded by carter.14 In the final text of their paper, Carter et al.!&apos; stated that they no longer believed wellbore storage was the reason for discrepancy in their kgh estimates. In view of the preceding, this study was performed to establish the importance of non-Darcy flow and well-bore storage for gas-well testing. In the course of the study. a reinspection of the previous work by van Everdingen&apos; and Hurst&apos; was made, and the basis for the Gladfelter, Tracy and Wilsey&apos; wellbore storage correction was investigated and extended to flow testing. WELLBORE STORAGE THEORY As has been shown by Aronofsky and Jenkins,11-12 Matthews," and others, flow of gas can often be approximated by an equivalent liquid flow system. The following developnlent will use liquid flow nomenclature to simplify the presentation. Application to gas-well cases will be illustrated later. First, we will use the van Everdingen-HursP treatment of wellbore storage in transient flow to establish (1) the duration of wellbore storage effects, and (2) a method to correct flow data for wellbore storage. DURATION OF WELLHORE STORAGE EFFECTS When an oil well is opened to flow. the bottom-hole pressure drops and causes a resulting drop in the liquid level in the annulus. If V. represents the annular volume in cu ft/ft of depth, and p represents the average density of the fluid in the wellbore, the volume of fluid at reservoir conditions produced from the annulus per unit bottom-hole pressure drop is approximately: res bbl-- (V, cu ft/ft) (144 sqin./sq ft) psi -(5.615 cu ft/bbl)(pIb/cuft) ........(I)

Jan 1, 1966

By John A. Church

Early in the month of Angust, 1877, a miner in Gold Hill, Nevada, made the unlucky remark that, according to his observation, that month was usually quite free from accidents in the mines. Never was presage wider from the truth. When the month closed twelve mishaps had occurred, killing six and wounding nine persons, and for the rest of that year the Comstock mining communities were kept in a ferment by the frequent occurrence of appalling disasters. There was a real tidal wave of calamity sweeping over the mines, which has not been repeated since, and according to cornmoll report was never known before on the Comstock. I was much interested in studying the character of these misfortunes, which also aroused concerted action on the part of the miners, and I have collected a list of the accidents which took place from July, 1877, to May, 1879. The number in this period of twenty-two mouths

Jan 1, 1880

By M. E. Wadsworth, K. C. Bowles, H. E. Flanders, R. M. Nadkarni, C. E. Jelden

The kinetics of precipitation of copper on iron of various purity were carried out under controlled conditions. The rate of reduction has been correlated with such parameters as copper and hydrogen ion concentration, geometric factors, flow rate, and temperature. The character of the precipitated copper as a function of flow conditions and rate of PreciPitation has been observed under a variety of conditions. ThE precipitation of copper in solution by cementation on a more electropositive metal has been known for many years. Basile valentine&apos; who wrote Currus Triumphalis Antimonii about 1500, refers to this method for extraction of copper. Paracelsus the Great2 who was born about 1493 cites the use of iron to prepare Venus (copper) by the "rustics of Hungary" in the "Book Concerning the Tincture of the Philosophers". Agricola3 in his work on minerals (1546) tells of a peculiar water which is drawn from a shaft near Schmölnitz in Hungary, that erodes iron and turns it into copper. In 1670, a concession is recorded4 as having been granted for the recovery of copper from the mine waters at Rio Tinto in Spain, presumably by precipitation with iron. Much has been published in recent literature on the recovery of copper by cementation, the majority of the articles being on plant practice.5-24 The rest include articles on investigation of the variables involved25-28 and a review of hydrometallurgical copper extraction methods." This literature has established: a) The three principal reactions in the cementation of copper are Cu + Fe — Fe+4 +Cu [ 11 One pound of copper is precipitated by 0.88 lb of iron stoichiometrically. In actual practice about 1.5 to 2.5 lb of iron are consumed. 2Fe+3 + Fe — 3Fe+2 [21 Fe +2H&apos;-Fe+2 + H2 [3] Reactions [2] and [3] are responsible for the consumption of excess iron. Wartman and Roberson&apos;28 have established that Reactions [ I] and [2] are concurrent and much faster than Reaction [3]. b) Acidity control is important in the control of hydrolysis and the excessive consumption of iron. he commercial workable range is approximately from pH = 1.8 to 3." c) Iron consumption is closely related to the amount of ferric iron in solution. Jacobi" reports that, by leaving the pregnant mine waters in contact wi th lump pyrrhotite (Fe7S8) for 3 hr, all the iron was reduced to the bivalent condition and scrap iron consumption was cut to 1.25 lb scrap per pound of copper precipitated. He also reported that SO2 has been used successfully to reduce ferric iron to the ferrous state. d) The ideal precipitant is one that offers a large exposed area and is relatively free of rust. e) High velocities and agitation show a beneficial effect upon the rate of precipitation, as it tends to displace the layer of barren solution adjacent to the iron and also dislodges hydrogen bubbles and precipitated copper to expose new surfaces. Little work, however, has been published on the reaction kinetics of copper precipitation on iron. Cent-nerszwer and Heller20 investigated the precipitation of metallic cations in solutions on zinc plates. They found the cementation reaction to be a first-order reaction. The rate constant was independent of stirring for high stirring rates and they concluded that the rate is governed by a diffusional process at low stirring speeds and by a "chemical" process at higher stirring speeds where the rate reaches a constant value. This conclusion has been challenged by King and Burger30 who could not find any region where the rate was independent of the stirring speed, although the rate constant they had obtained for high stirring speed was greater than the maximum value of the rate constant reported by Centnerszwer and Heller (by a factor of six). King and Burger, therefore, concluded that the rate of displacement of copper was controlled only by diffusion. Cementation of various cations on zinc has been summarized by Engfelder.31 APPARATUS A three-necked distillation flask of 2 000-mm capacity was used as a reaction vessel. A pipet of 10-mm capacity was introduced through one of- the side necks, the sample of sheet iron, mounted in a rigid sample holder, through the other, the stirrer being in the middle as shown in Fig. 1. The whole assembly was immersed in a constant-temperature bath. The stirrer was always placed at the same depth in the solution. EXPERIMENTAL PROCEDURE Reagent-grade cupric sulfate (J. T. Baker Chemical Co., N.J.) was used to make up a stock solution containing 10 g of copper per liter which was then diluted to various concentrations as required. Experimental data were obtained by measuring the amount of copper and iron ions in solution at successive time intervals. The initial volume of the solution was always 2000 ml, 10-ml aliquots being removed each time for chemical analysis. Because the total volume change of the solution was less than 10 pct, no correction was used for solution volume change. Nitrogen was bubbled through the solution before and

Jan 1, 1968

By Sergio G. Jarpa

A mining project is, at one and the same time, capital intensive and highly risky. Besides, because of its usual long projected life, the operating cost is more difficult to predict and offtentimes exceed, during the life of the project, the first investment manifold. The objective of this study was to evaluate the applicability of cost-capacity relationships as used in the chemical industry to mining operations and, when necessary, to develop new ones. With the aid of a computer library program available at the Computation Center of the Pennsylvania State University, the total investment in mining equipment was determined to vary exponentially with production capacity, and the scaling exponents for each class of equipment, i.e., drills, shovels, trucks and earth moving equipment, as well as for the total operation were calculated. Since the scaling exponent for the whole mining operation happened to be equal to 0.94, it was concluded that more significant economies of scale are achievable in processing plants than in mining operations. From the operating cost point of view, unit material cost was found to decrease more rapidly than unit labor for the same increases in production capacity. The analysis of cost centers revealed that drilling and blasting, which are materials-intensive operational stages, were the most favorable in achieving significant economies of scale. Hauling unit cost, on the other hand, decreased only slightly when production capacity increased.

Jan 1, 1977

By Castle. J. E., J. L. Gillson

In this chapter there is a wide difference in the meaning of some words used for rock and mineral names as defined by scientists and tabulated in the "Glossary of Geology and Related Sciences," published in 1957 by the American Geological Institute, and the meaning as used by the commercial producers of feldspar. It is necessary, therefore, to define these terms giving both the "scientific" and the "practical" definitions. There is no ambiguity about the name feldspar itself. This is a general term for a group of related minerals which are silicates of aluminum, combined with sodium, potassium and calcium. The feldspars are the most abundant minerals of the igneous rocks, and since these rocks make up the largest proportion of the earth&apos;s crust by volume (although not of the actual surface area of the continental land masses) the feldspars are the most abundant minerals of all. The igneous rocks themselves are classified on the basis of the variety of the feldspar present. The potash feldspars, which are called orthoclase and microcline, are the dominant minerals of the granites and syenites, and of their fine grained equivalents, the rhyolites and trachites. The plagioclase feldspars form an isomorphic series, of which the sodic endmember is called albite, and the lime endmember, anorthite. The members near the sodic end, albite, oligoclase and andesine are the characteristic feldspars of the granodiorites and diorites, and of their fine grained equivalents, the dacites, and andesites. These feldspars-orthoclase, microcline, albite oligoclase and andesine-are the feldspars used commercially. Labradorite, a member of the plagioclase group, in which the lime exceeds the soda in the chemical composition, is the common feldspar of the gabbros, anorthosites, norites, basalts and other so-called "basic" rocks. Although some attempts have been made to use labradorite as a commercial feldspar, none is now used except as an ornamental stone. The mineral anorthite is very rare. Since the feldspar in most of the common igneous rocks is relatively fine grained, and mixed intimately with other minerals, from which it can be separated cleanly only with difficulty, most masses of the common rocks cannot be used as sources for the feldspar contained in them. It is only the rarer types of rocks in which the feldspar is very coarse-grained, or ones containing very little of the iron-bearing minerals which are objectionable impurities in commercial feldspar, that are quarried to yield an acceptable product. The most widespread type of such a rock from which commercial feldspar can be produced, is that called "pegmatite." These rocks are dikes and bodies of irregular shape and of a size measured in feet or yards in most cases, rather than in miles. They are more commonly associated with granites, rather than with other coarse-grained igneous rocks. Many of them contain crystals of various minerals, including the feldspars, that are much larger than are found in the host rock, the granite, and in many there are large masses of feldspar that are sufficiently free from iron-bearing silicates so that products acceptable to the ceramic industry can be produced, in some cases simply by hand sorting. Most of this feldspar in pegmatites, however, does contain intergrown quartz up to 25 pct. Pegmatites are so important, not only as commercial sources of feldspar, but also of other minerals which are produced com-

Jan 1, 1960

By J. Szekely, R. G. Carr

A method is presented which allows the extension of the Ergun equation for the description of gas flow through packed beds in a nonisothermal regime. The pressure profile in the packed bed is calculated by the establishment of a differential energy balance and the iterative integration of the integral equation thus obtained. The predicted values of the pressure distribution were found to be in excellent agreement with those measured experimentally, under carefully controlled conditions. MANY metallurgical processes are carried out in systems in which a gas stream and particular solids are contacted in a packed bed arrangement under strongly nonisothermal conditions. Ore sintering, the firing of pellets, the operation of regenerators, blast furnace technology may be quoted as examples. Although many aspects of these systems have been extensively studied, an important variable, the pressure distribution and the relationship between pressure head and flow rate, received only little attention to date. The purpose of the paper is to present a brief survey of relevant previous work, followed by a more rigorously formulated model, together with experimental results that afford ready comparison of theoretical prediction with measurement. PREVIOUS WORK A great deal of information is available in the chemical engineering literature on flow phenomena in porous media.&apos; The experimental results pertaining to gas flow were generally interpreted in terms of models based on the analogy with the flow through a pipe of an incompressible, isothermal fluid. Of the numerous, semiempirical correlations that have been proposed to relate pressure drop to the volumetric flow rate, the Ergun equation2 is generally regarded as the most satisfactory: The strong nonisothermality of the metallurgical systems previously mentioned would render the direct applicability of Eq. [I] rather doubtful as both density and viscosity are temperature-dependent. Ergun has used Eq. [I] for estimating the pressure drop in the stack region in the blast furnace by neglecting the viscous term and evaluating the gas density at the integral mean temperature.3 His calculations showed a rather variable agreement with measurements and it was uncertain whether the discrepancy found was attributable to the model or to the inaccuracies often inherent in measurements on an industrial scale. Other work on nonisothermal systems includes studies of the pressure distribution in sinter beds, notably by Voice et a1.4 and Mitchell.5 Mitchell developed a method involving the subdivision of the bed into several zones and assigning average property values (temperature, gas density, and so forth) to each zone. The pressure drop was then calculated for each zone by using an expression analogous to Eq. [I]. This method was an improvement over that described by Voice et al., but even here prediction and measurement differed by as much as 30 pct in certain cases. It would appear that no really satisfactory methods are available for the prediction of pressure drop in packed beds with a strongly nonisothermal regime. The method involving subdivision of the bed into small enough sections, that may be regarded as isothermal, would show promise; however its validity has to be tested by both a rigorous formulation and comparison with experimental data obtained under controlled conditions. In the following a formulation is presented together with experimental data allowing ready practical evaluation of the theory. FORMULATION The mechanical energy balance over an infinitesimal section of a packed bed may be written as follows:

Jan 1, 1969

By Glenn C. Waterman

THE diamond drill is a very important tool in exploration and development testing and its use is increasing. In almost all cases results of diamond drilling are analyzed on the basis of grade and tons. A proper evaluation of core and sludge assays is important if drilling results are to be acceptable as a basis for geologic and engineering appraisal. The relatively wide variation in assay averages as calculated by various well-known combining methods indicates that the engineering choice of a method may affect the outcome of the drilling in terms of ore and waste. The problem of combining assay results from core and sludge samples has been discussed many times in conference and in the literature.&apos;" Most writers agree that the field of disagreement in methods is large and that the engineer on the job must consider features unique to his drilling, pick one of several combining methods, and depart from the rules when abnormal results come in. All the discussion to date can be summed up by the admission that as yet there is no fairly simple, generally acceptable combining method that is practicable over a wide range of drilling conditions, ground conditions, and ore occurrence.

Jan 1, 1955

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&apos;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 L. R. Raymond, G. G. Binder

One primary purpose of hydraulic fracturing as a well stimulation technique is to overcome formation damage. The literature provides ways of designing fracture treatments and evaluating their results but not of incorporating formation damage in vertically fractured wells. Results of an investigation of this problem are presented in this paper. Prediction of stimulation ratios in vertically fractured, damaged wells is accomplished with a mathematical model relating stimulation ratio to relative conductivity of fractures whose lengths are not more than about half the drainage radius of the well. Comparison of results from the new model to results in published predictions verify its utility; these results also show that the range of stimulation ratios that can be predicted for undamaged wells is extended to include relative conductivities of less than 300. This extension is important when using fracturing to stimulate wells with high production rates and high native formation permeabilities. For example, large increases in daily oil production rate can be obtained with stimulation ratio increases as low as 1.25. The importance of complete fracture fill-up (uniform proppant packing) is shown through use of the mathematical model. If, at the mouth of a fracture, only a small fraction (1/2 percent) of the total fracture length is not packed with proppant, nearly all the polential stimulation increase is lost. Proppant crushing, compaction and embedment have been shown in laboratory studies to be responsible for low fracture conductivities in wells producing from highly stressed formations. Equipment and methods for testing the effect of stress (overburden) on conductivity of fructures in consolidated and unconsolidated sands are discussed in this paper. Laboratory tests with simlilated fractures in cores from both types of formations showed that crushing, compaction and embedment seriously affect conductivity. Results indicate that similar laboratory tests should be made when accurate knowledge of fracture conductivity is needed to assure good stimulation results for important wells. The chief factor in stimulation ratio reduction was found to be overburden pressure, but the size and type of proppant and the hardness of the formation have significant effects. Fracture conductivity reductions of up to 50 percent were observed with sand propping fractures in consolidated cores; a reduction of 83 percent was measured for an unconsolidated core. The range of effective overburden pressures for which conductivities were measured was from 100 to 5,000 psi. An example fracture design and evaluation problem indicates the usefulness of considering formation damage in planning well stimulation jobs. When damage exists, but its extent and the degree of permeability reduction are not estimated from diagnostic tests, the formation permeability used in planning the job may lead to under-designing. As the example shows, too low a target stimulation ratio can lead to much lower production rates (by half) than could be attained otherwise. Solutions of equations representing several special cases of the mathematical model are presented in graphical form and details of the derivations of the equations are given in the Appendix. INTRODUCTION Since its inception in 1947, hydraulic fracturing has proven to be an effective and widely accepted stimulation technique. In the past 18 years the ability to execute a successful hydraulic fracturing treatment has been substantially increased. The development of design and evaluation procedures1,2 has been one of the major contributions to this increased skill. However, as the art of hydraulic fracturing has moved closer to a science, new problems concerning the design and evaluation of the optimal hydraulic fracturing treatment have arisen. Three questions are pertinent to these problems. I. How is a fracturing job evaluated in a damaged well? 2. What is the effect on the stimulation ratio of not filling the fracture in the vicinity of the wellbore? 3. What is the effect of overburden pressure on fracture conductivity and, consequently, the stimulation ratio? A primary objective of fracturing a well is to stimulate production by overcoming wellbore damage. Presently. however, there is no rational basis for designing or evaluating the optimal fracturing treatment in a damaged well. All present fracture design and evaluation techniques assume that proppants can be uniformly placed in fractures. This assumption may be in serious error, particularly for the portion of a fracture directly adjacent to the wellbore. In this area, turbulence of the injected fluid can cause the proppant to be swept farther into the fracture. Also, loss of fluid from the fracture to the

By G. F. Tagg

EARTH-REISTIVITY measurements are often of service in obtaining information regarding geological formations, particularly when applied to structural problems. In such problems the masses of the various bodies are large, and have a corresponding effect on the average resistivity of the soil. Much work has been done using such measurements, but in general the method of interpretation employed is empirical. Since certain simple cases can be investigated mathematically, it appears to be quite sound to endeavor to apply the mathematical solutions to the practical results, in order to deduce from the latter such unknown quantities as depth. This paper deals with such a method of interpretation for the simple case of a single horizontal stratum. SURFACE Of EARTH In the method described by FIG. 1.-WENNER&apos;S METHOD OT MEASURING Wenner1 for measuring earth resis- EARTH RESISTIVITY. tivity, four stake electrodes are driven into the earth in a straight line as shown in Fig. 1. A current I amperes is passed between the two outer stakes and the potential difference . V volts between the two inner stakes is measured. Then if a is the electrode separation, the specific resistance of the soil, which is assumed to be homogeneous, is given by the formula

Jan 1, 1932

By J. W. Spretnak, J. N. Cordea

The gain boundary relaxation in high-purity aluminum, nickel, copper, and silver was studied by means of a low-frequency torsion pendulum. Both internal friction and creep at constant stress tests were conducted. A lognormal distribution in relaxation times was found to account for the relatively wide experimental internal friction peaks and the gradual relaxation behavior during the creep tests. This distribution was separated further into a lognormal distribution of relaxation time constants and a normal distribution in activation energies. A spread of up to ±6 kcal per mole in the activation energies accounted for the major part of the distribution. A "double-peak" internal friction phenomenon was observed in silver. The activation energies in kcal per mole derived from the grain boundary relaxation phenomena are 34.5 for aluminum, 73.5 for nickel, 31.5 for copper, and 41.5 for silver. It was found that the rain boundary relaxation strength in these metals increases with the reported stacking-fault energy. GRAIN boundary relaxation phenomena have been observed in a large number of polycrystalline metals and alloys. Numerous investigations have been conducted to study the structure of the grain boundary through this relaxation process. One of the first investigators was Ke1-4 who observed that the activation energy for grain boundary relaxation in aluminum, a brass, and a iron was about the same as that for volume diffusion. He concluded that the grain boundary behaved as if it were a thin liquid layer with neighboring grains sliding over one another. Leak5 conducted experiments on iron of a higher purity and observed that the grain boundary activation energy is comparable with that of grain boundary diffusion. He suggested that, in metals where this relationship holds, the damping may be caused by a reversible migration of grain boundaries into adjoining grains. Nowick6 has presented an interesting view of inter-facial relaxation with his "sphere of relaxation" model. A relaxed interface is represented as one where the shear stress is greater than the normal value along the edges and zero in the interior of the interface. The region of the stress relaxation is pictured as a sphere surrounding the interface. From his calculations Nowick concluded that the slip along an interface is directly proportional to its length. Therefore, the time of relaxation, T, depends on the size of the relaxation interface. This means that in the Arrhenius relationship, t = TO exp[H/RT], valid for atom movements, the relaxation time T is predicted to be proportional to the grain diameter through the pre-exponential term, TO. Since the internal friction can be given as Q-1 = ?j wt/(1 + w2r2), where ?J is the relaxation strength and w is the angular frequency, an increase in grain size at a constant frequency will shift the peak to a higher temperature. A great deal of work has been done to determine the exact relationship between the internal friction and grain size.1,5,7,8 In metals, the grain boundary peaks are found to be lower and broader than predicted theoretically.&apos; The above model can explain this by a distribution in the size of the interface areas, represented by a distribution in the parameter tO, and an overlap of spheres of relaxation, represented by a distribution in activation energies. Both these phenomena result in an over-all distribution in the relaxation time, which could affect the internal friction peak height, breadth, and also position. This relationship between the experimental data and theoretical calculations appears very promising in the study of interfacial relaxation mechanisms. THEORY A lognormal distribution in t can sometimes be used to adequately describe the spectrum of relaxation times governing an anelastic relaxation. wiechert9 originally suggested such a distribution to explain the elastic after-effect in solids. This choice is particularly applicable to grain boundary relaxation when considering Saltykov&apos;s work.&apos;&apos; He found a lognormal distribution in the grain sizes within a metal. Recently Nowick and Berry11 have introduced a log-normal distribution in T into the theoretical internal friction equations. The form of the distribution function is where z = In(r/rm), and Tm is the mean value of t. The parameter ß is a measure of the distribution and is the half-width of the distribution when is l/e of its maximum, IC/(O). Nowick and Berry have described the methods to obtain the parameters Tm, ß, and ?,J from experimental internal friction and creep test data. In the idealized case, where only one relaxation event occurs with one relaxation time, only ?J and T are necessary to completely describe the event, and 0 = 0. For the broader internal friction curves 6 is some positive number greater than zero. The larger the 6, the greater is the half-width of the distribution in In t.

Jan 1, 1967