Search Documents

By R. L. Mauger, P. E. Damon

Potassium-argon dating of the late Mesozoic and Cenozoic intermediate to acidic plutons and volcanic rocks of Arizona and northern Sonora demonstrates the existence of two distinct magmatic episodes. The earlier episode begins in late Campanian time and dies out before the middle Eocene. Following a quiescent period in middle and late Eocene time, magmatism increases in Oligocene time, becomes most intense at the Oligocene-Miocene boundary and dies out as the Pliocene is approached. Pliocene magmatism is primarily confined to extrusion of post-orogenic basalts. The late Mesozoic-early Cenozoic magmatic pulse is essentially confined within the limits of the classical Laramide orogeny (Laramie through Wasatch time). The mid-Tertiary pulse is contemporaneous with the mid-Tertiary Basin and Range orogeny. The Laramide provides an excellent specific example of Umbgrove's concept of the pulse of the earth and in general his concept appears to be meaningful. Copper porphyry mineralization is time-congruent with Laramide magmatism and there seems to be no doubt as to the existence of a genetic relationship between the two phenomena. Two origins are tenable: direct accumulation of the copper sulfides in the copper porphyry liquid magmatic environment; or, introduction of the mineral constituents entirely from a larger source magma when the host rock is already crystalline. Transgression and regression of the epicontinental seas provide an excellent indicator of orogeny and epeirogeny. There was an overall transgression of the epicontinental seas from early Triassic time through the Turonian epoch in early late-Cretaceous time. Thereafter, there is a relatively continuous regression of the seas until the present time. Both the earlier transgressive episode and the later retreat are intermpted by temporary but distinct reversals. These interruptions can be correlated with classical orogenies. There are six distinct orogenies so indicated in the Mesozoic-Cenozoic eras. These occur at approximately 35 to 40 m.y. intervals. The regression of the epicontinental seas following the Turonian epoch was contemporaneous with the deepening of the Pacific ocean basin over the Darwin Rise. As the Darwin Rise was collapsing the East Pacific Rise was being elevated. The Western United States, situated on the eastern flank of the East Pacific Rise, was upwarped and tilted toward the east. Epeirogeny is the primary consequence of processes that operate on a global scale. Orogeny is an exothennic process that is limited in space and is treated here as a secondary consequence of epeirogenic-initiated warping. The off-campus buildings of the University of Arizona Geochronology Laboratories rest on the volcanic rocks of Tumamoc Hill. From this hill, the observer may obtain a beautiful view of typical Basin and Range topography. The city of Tucson lies below, contained within the broad Santa Cruz basin and surrounded on all sides by characteristic NW-SE trending ranges towering as much as 7000 ft above the valley floor. Since the senior author arrived in Tucson eight years ago, a great deal more has been learned about the geochronology of this and neighboring basins and ranges. For example, the volcanic rocks underlying the laboratory at Tumamoc Hill were shown on the state geologic map as Quaternary basalt. A student of the senior author has demonstrated that the so-called basalts are in fact alkali-andesites (Halva, 1961), and we now know that these alkali-andesites or doreites (Mielke, 1965) are of early Miocene age rather than Quaternary age (Bikerman and Damon, 1965). Is it any wonder then that geologists disagree on the nature and time of Basin and Range volcanism, plutonism and tec-tonism? The plain fact is that few definitive Cenozoic fossil sites were available upon which to base a chronology and geologists were forced to guess the ages of rocks in order to achieve the semblance of a time classification. We have now made considerable progress in developing a K-Ar chronology for the volcanic and plutonic rocks of the Basin and Range (Bikerman, 1965; Damon and Bikerman, 1965; Damon et al, 1964 and 1965; Mauger et al, 1965). It is the purpose of this paper to point out the main features of this chronology and to discuss the relationship of magma-tism to orogeny-epeirogeny during post-Turonian time. We will also discuss probable relationships during

Jan 1, 1967

By Leslie G. McMillion

A field project to develop and demonstrate a method for alleviating problems of highly mineralized ground water where they occur as isolated zones or pockets in fresh-water aquifers is being conducted in the Ogallala aquifer of eastern New Mexico by the Robert S. Kerr Water Research Center. Removal of contaminated water is by a large-capacity well and the pumped poor-quality water is used locally for secondary recovery of oil. Benefits of the operation are threefold in that the aquifer is being reclaimed for future fresh-water production, contaminated water is being used beneficially, and fresh water which otherwise would have been used for waterflooding is available for other purposes. Ground-water quality in the site has improved markedly after two years of operation. Use of water in the arid and semiarid Southwest has grown so rapidly that demands in many localities far exceed available supplies. In the High Plains region of New Mexico, Oklahoma, and Texas, the only large sources of water are underground reservoirs, being depleted at an alarming rate. In some parts of this region, the aquifers contain pockets of highly mineralized waters; and the mineralized waters in some of them have started spreading in response to the drawdown effects of pumping wells. The aquifers of this region are primarily composed of sand and gravel beds; any cleanup by natural processes will require many tens or even hundreds of years. Most of these pockets of highly mineralized water were caused by oil-field brines seeping downward from earthen disposal pits. Thousands of these pits were in use in the region until only a few years ago when they were prohibited by the oil regulatory agencies of the respective states. The resulting areas of poor quality water are serious enough to warrant much corrective attention. Correction will involve one or more of three approaches: 1) Restrict the pumping of fresh water in the zones where the drawdown of the pumping well will significantly influence the movement of the contaminant. 2) Remove the highly mineralized water entirely from the affected area. 3) Develop and pump the poor-quality water in such a manner that its movement is held in check, even though only a part of the contaminant is actually removed. The principal hurdle to overcome in applying methods 2 or 3 is financing of the operations, since there are very

Jan 1, 1972

By Immo H. Redeker

Through close cooperation with geophysical and geological test work by Texas Gulf Sulphur Co. in Beaufort County, the Asheville Minerals Research Laboratory assisted in the evaluation of North Carolina's most valuable mineral resource, the Pungo River phosphate deposit. After a core evaluation study, the flotation process for the concentration of North Carolina phosphate was demonstrated in a 500-lb per hr pilot plant in Asheville. Tonnage samples of phosphate concentrate were produced for customer evaluation in the United States, Europe, and the Far East. Plans for a larger pilot plant to be erected at the plant site at Lee Creek were prepared for TGS. The larger pilot plant was operated by TGS in conjunction with a test dredging operation which led to the adoption of a dragline dry mining method to move 90,000 tpd of material for the production of 10,000 tpd of phosphate concentrate in the all-flotation phosphate concentrator. Calcining, dry grinding, and byproduct studies complimented the construction of one of the world's largest and most modern fertilizer raw-feed complexes on the eastern North Carolina seaboard.

Jan 1, 1972

By AIME AIME

UNDER the auspices of the Institute's Committee on Industrial Preparedness, a symposium was arranged for the Annual Meeting on the subject "Ores, Metals, and the War," with many well-known Government men and industrialists participating. Wilfred Sykes, president of the Inland Steel Co., of Chicago, presided, with C. K. Leith and Clyde Williams as vice-chairmen, Mr. Williams presiding over the latter part of the meeting. On the Auditorium stage in the Engineering Societies Building was a formidable corps of "experts," with an audience of several hundred to hear what they had to say and to ask questions.

Jan 1, 1942

By M. A. Meyers, P. P. Meyers

The analysis of the phenomena involved in determining the compressive strength of iron-ore agglomerates leads to the identification of important parameters. It is shown mathematically that the pellet rupture strength is proportional to the cross-sectional area. Fracture is initiated at the center of the pellets by the tensile stresses developed by the compressive loads normally to the compressive axis. The variation in strength between individual pellets of identical composition and subjected to identical treatments u due to internal voids of varying sixes that act as stress-concentration sites. Two novel testing procedures are proposed. The first consults of testing the pellets between two plates having three steel spheres each. This configuration simulates much better the environment actually encountered by the pellets. The second procedure consists of a thick-walled cylinder in which a piston penetrates; a large group of pellets is tested simultaneously, as the stress versus strain plot is being recorded. This latter test presents vacant advantages over the conventional testing procedure; the main one is that one single test is sufficient to characterize the mechanical response of the pellets.

Jan 1, 1984

By J. C. Trantham, J. W. Marx

From 1955 to 1958 the Phillips Petroleum Co. conducted a series of small scale counterflow combustion field tests in a tar sand about 60-ft deep and 6 to 12-ft thick near Bellamy, Mo. A total of seven different well patterns, including conventional five-spots and seven-spots plus a 15-well line drive pattern and a 10-well radial pattern, were employed. Electric heaters, gas burners and wellbore fuel packs were tested as counterflow ignition devices. Direct drive ignition followed by reversal to counterflow operation was not possible in this case because of formation plugging by the semi-solid tar during the direct drive phase. Sustained counterflow burning was achieved with wellbore fuel packs under conirolled conditions which permitted close correlation of fire front velocity, air velocity, air-oil ratios and yields for a wide variation in process parameters. The tar in place was about 10' APl with a reservoir viscosity greater than 500,000 cp. The composite oil prodlcct was 26' API with a viscosity in the range of 5 to 15 cp. Vertical sweep efficiency in the line drive pattern was essentially 100 per cent, with no evidence of gravity segregation. Original tar in place ranged between 800 and 1,000 bbllacre-ft, specific rock permeability averaged about 800 md before burning and effective air pemeability with residual oil and water in place (at the time of ignition) averaged 250 md. The volume of oil recovered during stabilized line drive counterflow burning represented about 67 per cent of the volume of tar originally in place in the burned out zones. A minimum was found when air-oil ratios were plotted against formation air velocities, and a limiting air velocity existed below which the counterflow fire front reversed and burned back over its own trajectory, using the residual coke left behind. INTRODUCTION Early in 1955 the Phillips Petroleum Co. began preparations to field test counterflow underground combustion as a method for producing oil from high viscosity hydrocarbon deposits, such as bituminous (tar) sands. At that time all published information on the use of underground burning io increase oil recovery was based on the direct drive process, in which the fire front moved through the formatim in the same direction as the injected air stream. Such direct burning is not applicable to many heavy oil sands or to most tar sands because the heat-thinned native hydrocarbon congeals in the cold rock ahead of the fire front forming a gas permeability block which smothers the combustion. Laboratory experiments first demonstrated that this permeability blocking would not occur if the fire front and the air stream moved in opposite directions. In this counterflow (reverse) burning process the heated heavy oil or tar is driven back through the combustion zone. Here thermal cracking produces relatively light hydrocarbon products which pass through the heated rock behind the fire front (largely in the vapor phase) and are incapable of causing a gas permeability block.' Exploratory wring revealed that consolidated bituminous sandstones with a combination of tar saturation, permeability, thickness and depth favorable for experimental field testing existed at several points in western Missouri. By the fall of 1955, a test site for determining technical feasibility of the counterflow process under field conditions had been selected near Bellamy, Vernon County, Mo. — about fifty miles north of Joplin. The pay zone was too thin and too shallow to constitute a commercial prospect, but these same factors permitted controlled experimental operation with a small compressor installation and with a large number of monitor wells. These were needed for adequate observation of the underground phenomena at reasonable cost. RESERVOIR CHARACTERISTICS The reservoir chosen for the experimental field tests was a 124 thick section of tar sand extending from 49 to 61 ft subsurface, with shale and siltstone laminations sealing the top and bottom. This section was part of a larger 30-ft thick tar sand deposit which extended both above and below the test zone. Core analyses showed that the 12-ft sand was effectively subdivided into two approximately equal sections, with the lower zone being consistently more permeable than the upper zone. The most significant laboratory core data are summarized in Table 1. The line drive test which is the principal subject of this report utilized only the lower 6-ft thick zone, with the upper zone regarded as part of the 55-ft overburden. WELL PATTERNS The over-all field test program involved a total of seven different well patterns, including conventional five-spots and seven-spots plus a 15-well line drive pattern and a 10-well radial pattern. In some of the tests the full 12-ft zone was employed; in other cases only the more perme-

Jan 1, 1967

By D. E. Marks, Arnold, C. W, R. J. Robinson, A. E. Hoffmann

The efficiency of operation of a fixed-bed adsorption unit is infEuenced both by the absolute adsorption capacity of the bed and by the rate of adsorption. This paper describer studies of adsorption rate which were conducted in an experimental unit designed such that conditions existing in the treatment of high-pressure natural-gas mixtures could be duplicated. Variables investigated included pressure, temperature, gas composition, adsorbent particle size, depth of packed bed and gas velocity. The adequacy of a simplified mathematical model for predicting the observed phenomena was tested. A correlation is preserited which relates adsorption rate to the process variables stlldied. This correlation is useful in combination with the matheinatical model. INTRODUCTION Of the techniques available for contacting adsorbent particles with fluid streams to be treated, fixed-bed adsorption columns offer definite advantages in simplicity and ease of operation. As a result, they are often used in preference to others for such petroleum industry applications as dehydration and purification of natural gas and hydrocarbon recovery. Fixed-bed adsorption units usually consist of two or more towers filled with a desired adsorbent and operated in a cyclic manner. While one is being used to process the main flow stream, the others are undergoing regeneration to remove the adsorbed phase. When the tower on stream becomes saturated with the preferentially adsorbed material, the roles of the towers are switched, and the freshly regenerated tower is placed on stream. Cacle duration is determined by the bed capacity under the process conditions and by the flow rate through the bed. The sharpness of separation which can be effected is a function of both the absolute capacity of the bed and the rate of adsorption in the bed. The effect of rate for a particular set of conditions is evidenced by the sharpness or diffuse-ness of the adsorption front as it advances through the bed. Since data needed for design of adsorption units to treat high-pressure natural-gas systems were not available, an experimental program was designed to investigate the effects of different variables upon adsorption rate in fixed beds. In the present paper, effects of gas composition, column length, temperature, pressure, adsorbent particle size and flow rate (actual linear flow rate of the gas) are shown, and utility of a simplified mathematical model for describing the process is discussed. As gas enters the top of a cool, clean bed of adsorbent, preferentially adsorbed materials are stripped from the main flow stream by the uppermost particle layers. As these layers become saturated with a particular component, new supplies of this component are carried further down the column until fresh adsorbent is encountered. An adsorption wave thus moves through the column as material is supplied to saturate succeeding elements of the bed. Adsorption from a Multicomponent gas stream occurs as a succession of such moving waves corresponding to the different components in the gas. The leading edge of an adsorption wave for a component of a natural-gas stream moving through a bed of a common commercial adsorbent such as silica gel would be sharp but for the influence of certain broadening fac tors. These factors include a nonuniform velocity profile in the bed, longitudinal dispersion or mixing in the main gas stream, and the time required for a molecule to migrate from the main gas stream and be adsorbed at a site within the body of an adsorbent particle. If packing is uniform and the ratio of column to particle diameter is greater than approximately 15:1, the first factor is relatively unimportant' Longitudinal mixing is of importance only for the case of moderately high mass transfer with extremely slow flow rates.' The sharpness of an adsorption front, therefore, is, primarily a function of the rate of adsorption or the time required to saturate a particle of zdsorbent. Two methods for defining adsorption rate are used in this work. The first is a normalized or relative rate which describes the rate of saturation of a differential element of the packed bed. This can be measured by observing the time required for the concentration of the preferentially adsorbed material in the effluent gas from the bed to rise from zero to a value equal to that in the inlet gas stream. The second definition describes the absolute rate of mass transfer from the gaseous to the adsorbed phase. This definition is used in a mathematical description of the adsorption process. If the concentration of a component in the gas strcam leaving an adsorption column is measured and plotted as a function of time, a curve such as that shown in Fig. I results. It is seen that for a period of time the effluent gas is devoid of the component under consideration. As the bed approaches saturation, a small percentage of this material will appear in the effluent gas. The concentration will then rise with time, or increasing cumulative gas flow, until it is equal to that in the inlet gas stream. If adsorp-

OF no less importance nor less terrifying to consider than the marvelous effects of guns are those produced with fire by powder in underground mines. These are truly not only similar to fearful natural earthquakes, but it can perhaps be said that these made by art surpass the wrath of the earth with greater effect. For if the latter shakes it happens that it causes the things on the surface to shake and sometimes to fall into ruins, but the former not only shakes but always functions and destroys-surely a marvelous effect which is almost incomprehensible, and if experience did not demonstrate it, it could scarcely be believed. Who would say that the mountains, things of such great hardness, would yield to men, easily opening their bowels? Likewise, one who had not seen it would say that it was impossible for men to have a way of administering at will fearful and destructive thunderbolts which are of such a kind that, although men make them, they cannot protect themselves against them; indeed they cannot call themselves safe from the evilness of gunpowder even in mountains composed of very hard stones or in budded structures. For, as is seen, there is no seemingly impregnable fortress that does not yield when guns are brought near it. If it happens, indeed, that guns can- not be brought near to some place because of the harshness of the site,

Jan 1, 1942

By Frederick F. Frick

SPONGE iron as produced at Anaconda is a fine, -35 mesh, impure product, about 50 pct metallic iron, obtained from the reduction of iron calcine at a temperature of 1850°F by use of coke resulting from slack coal. The metallic iron particles are bulky and spongey and precipitate copper readily and rapidly from a copper sulphate solution. Investigation of the treatment of Greater Butte Project, Kelley, ore at Anaconda early showed the desirability of using sponge iron as a precipitant for the copper in solution resulting from desliming of the ore in a dilute sulphuric acid solution. Anaconda had done considerable work on the production of sponge iron in 1914 for use as a precipitant of copper from leach solutions. Some success and considerable experilence were attained at the time. indicating that, sponge iron might be successfully made by a modification of the process used in 1914, a batch process in which an iron calcine was reduced by means of soft coke, resulting from noncoking coal, in a Bruckner-type revolving horizontal cylindrical furnace widely used 50 years ago. The coke and calcide formed the bed in the Bruckner furnace, which was rotated at about 1 rpm. The bed was brought to a temperature of about 1800°F by means of an oil flame over the surface. Although results were reasonably satisfactory, they did not warrant full development of the process at that time. A good deal of work has been done in the last 50 years on the production of sponge iron. The objective in some cases has been the production of a precipitant for copper from solution, but the bulk of the work has been done for the production of open-hearth steel furnace stock. The production of an open-hearth stock presents two problems rather than one: first, producticon of the sponge iron, and second, what is perhaps of equal difficulty and importance, conversion of the sponge iron into a form suitable for use in the open-hearth furnace. So far as is known to the writer, none of the sponge iron processes tried in the past have proved to be economically feasible. However, Anaconda had a combination of conditions appearing to justify an attempt to produce sponge iron which would serve for the leach-precipitation-float process. It was thought that the process used in 1914, if changed to a continuous one, might work out satisfactorily. The following favorable conditions at Anaconda justified the investigation: 1—A sufficient tonnage of good grade iron calcine resulting from the roasting of a pyrite concentrate in one of the acid plants, at substantially no cost. 2—Reasonably cheap natural gas. 3-—The fact that there was no need for production of a high grade product. 4— The fact that there was no need for obtaining a consistently high reduction of' the iron in calcine. A small revolving Bruckner-type furnace about 2 ft ID by 4 ft long was set up for early pilot work at the research building. This pilot furnace showed that a satisfactory product could be obtained at reasonable cost. It also indicated a marked advantage in preceding the reduction furnace with a furnace of similar size and capacity for preheating and roasting out any residual sulphur from the feed. The small furnace was operated for several months, various details of the process were worked out. and sponge iron was produced to supply a pilot LPF plant which treated 300 lb of Kelley ore pel- hr. Later a second pilot furnace 5 ft in diam and 12 ft long inside was set up at our reverberatory furnace building. This furnace confirmed the data of the small furnace and gave a basis for design of the final plant. At Anaconda a pyrite concentrate, running about 48 pct S, is recovered from copper concentrator tailings by flotation. This concentrate is roasted to sulphur of 3 pct or less at the Chamber acid plant. The iron calcine contains about 57 pct Fe and 18 pct insoluble. The iron calcine feed, as mentioned before, is re-roasted and preheated in a reroast furnace preceding the reduction furnace. Both are of the Bruckner type. The reroasted calcine is fed into the reduction furnace at 800" to 1000°F along with 30 pct slack coal. In the feed end of the furnace the volatile is burned from the slack, giving a soft coke which readily serves for reduction of the iron. Hard metallurgical coke will not serve the purpose. since it does not reduce CO readily at a temperature of 1850°F. All indications are that the actual reduction of the iron is accomplished by carbon monoxide below the surface of the bed, which is 30 in. deep at its center. Apparently there is a constant interchange: Fe²O³ + 3CO = 2Fe - 3CO², CO² + C = 2CO Actually iron oxide is reduced by CO at somewhat lower temperature than the 1850 °F used in the process. but this temperature is necessary to obtain a satisfactory rate of furnace production. The furnace atmosphere is generally reducing, and typical blue carbon monoxide flames satisfactorily cover the bed. Gas flames from four 3-in. Denver Fire Clay Inspirator burners are played directly on the bed, which is slowly cascaded by the 1 rpm of the furnace. An excess of coke is necessary to assure maintenance of good reducing conditions in the furnace bed. Part of this coke is recovered for re-use.

Jan 1, 1954

By R. A. Pallanch

IN his recent paper, "The Controversial Art of Flotation," (Mining Technology, March, 1944) E. H. Rose states that "flotation is a science in so many variables that only art can blend them." This statement is apt. It contains meat. In other words, a valid scientific reason is behind every flotative effect. Some of these reasons we understand, but much the greater number of them still escape us. This does not prevent us from "going places," as familiarity and experience with the problems result in an increasingly intelligent and artful handling of these effects. Hypotheses are built up by the individuals concerned to explain certain happenings. Many of these hypotheses have to be abandoned when placed under the glaring scrutiny of actual trial. A few survive the severest of tests, come through unscathed, and are elevated to the rank of theories, something susceptible of certain chemical and physical explanation, under the conditions of the particular plant concerned. If these theories continue to hold water under all the variations existing in most milling plants, they gradually become accepted as facts in the minds of the plant operators. But-and here is a big BUT-these so-called facts may fall down completely in another plant working under an entirely different set of conditions. In other words, each plant tends gradually to build up its own facts, which may or may not be facts at another operation.

Jan 1, 1945

By HAROLD A. TITCOMB

TOWARD the close of 1925, a British geologist, T. Landell Mills, brought to the notice of .A. Chester Beatty and selection Trust Ltd. certain mineral areas in southern Yugoslavia. Mills' data, which included rough maps and preliminary reports by' a Yugoslav engineer, Jules Draskocy, appeared interesting to Reatty, and early in 1926, I, with three British assistants, proceeded to Serbiaand commenced the investigation of several groups of ancient mine workings. They were found to be extensive and the geological conditions-schists, limestones, and andesitic intrusive-favorable for mineral deposits. At Stan Trg, on the Trepca Concession, five rniles east of Kosovska Mitrovica, an ancient filled adit was found, a shelter-hut erected, and work started in reopening this adit.

Jan 1, 1936

By Shiro Ban-ya, John Chipman

The effects of many alloying eletnents on the acticity coefficient of sulfur in liquid iron have-been studied by the equilibriutn in the reaction Sfin Fe) + Hz = HzS at 1550°C'. Results are expressed in terms of a concentration variable for a nonmetallic or for a substitutional metallic solute. Activity coefficient of sulfur, defined as increased by B, Al, C, Si, Ge, Sn, P, As, Sb, Mo, W, Co, and PI. It is decreased by Cu,Au, Ti. Zr, V, h'b, Ta, Cr, ,23n, and Ni. Irulues oj. the interaction coejficient 0i = 6 In are labulated. The same interactions are expressed also in terms of atom fraction and of weight percent. The thermodynamic properties of sulfur in liquid iron have been fairly well established. Our recent paper1 reported new determinations of activity coefficient up an atom fraction of 0.12 and equations based on a careful review of all published data. The effects of alloying elements on the activity of sulfur have been studied by several investigators,2"11 especially by Morris and Williams for silicon,' by Morris and Buehl for carbon,~ and by Sherman and Chipman for manganese. phosphorus, and al~minum.~ However, the effects of some important alloying elements remain to be determined. The purpose of this investigation was to determine the effects of many alloying elements on the activity of sulfur in Fe-S-j ternary systems. EXPERIMENTAL METHOD This study was based on experimental determination of equilibrium in the reaction at 1550°C: The same apparatus and procedure as described in our previous paper have been retained, and the same corrections were applied for dissociation of H2S. The alumina crucibles used in the experiments consisted of four separate compartments. In a given experimental run. kach of three alumina crucibles held four different samples of about 3 g each which reached equilibrium in the same gas atmosphere and temperature. The charges were made up of electrolytic iron, pure iron sulfide, and desired alloying elements, which were pure metal or master alloys made in the laboratory. The weighed samples were held for 4 to 12 hr in the prepared atmosphere at 1550°C. They were then low- ered to be cooled as quickly as possible. The quenched metal beads were crushed to avoid the errors of segregation in the ingot. The sulfur content was determined gravimetrically and alloy content by appropriate chemical analysis. CALCULATIONS The apparent equilibrium constants of Eq. [I] are expressed as follows from the corrected gas ratios and sulfur concentrations: The term K" is the observed equilibrium constant in any given ternary solution, K' is the value for the Fe-S binary solution. and the limiting value of K' in the infinitely dilute solution is designated by K, which is the true equilibrium constant in Eq. [I]. In the thermodynamic treatment of nonmetallic elements in a metallic solution, it has been suggested1' that the lattice ratio has certain advantages over other variables to express the concentration of solute. In interstitial solid solutions the lattice ratio zj is proportional to the ratio of filled interstitial sites to those which remain unfilled. The equations derived for the activity of the solute using zj as the concentration variable are found also to be applicable to liquid solutions containing nonmetallic solutes when the nonmetal is treated as if it were interstitial. For this purpose we adopt the following definitions: The quantity vj which is negative for interstitial solutes is taken as -1 for nonmetallic and +1 for metallic solutes. For purposes of calculation however ; j may be assigned a value which results in a linear relation such as shown in Figs. 1 to 15. The activity coefficient of sulfur, Qs, and equilibrium constant. K(z). are defined as follows: According to a Taylor series expansion. the logarithm of the activity coefficient of sulfur in Fe-S-j ternary system is: However, the value of 6 In */6zi remains constant through a broad range of dilute solutions and the terms of higher order are negligibly small. As a consequence, Eq. [6] is simplified as follows:

Jan 1, 1970

By B. F. Tillson

ALTHOUGH most accidents occur through the A carelessness or misfortune of the workmen; that is no reason why we should not take all physical precautions practicable. The best way to approach the problem of mine safety is to acquire a personal feeling of responsibility for the accident and then plan how it might have been prevented had we known that it was to occur. A statistical analysis of the physical conditions contributory to accidents will give an indication of some of the methods or mechanisms that should be revised or safeguarded. The handling of rock or ore is a common source of minor injuries. Freedom from accident when mucking largely depends on the skill and care of the workman; this also is true, to a certain degree, to loading cars from chutes, but much can be done in the layout of chutes and their equipment to provide equal safety with less skill. Permanent stagings, or rigid units that may be easily assembled, should be provided so that the men handling the chute boards or gates and barring the jammed chunks will have a convenient safe footing for their operations. A stance to the side of the chute mouth is to one in front, because a man will not be liable to be struck by flying lumps or his bar, should it he caught in the mass, yet in many mines the workmen face the chute when loading a car. Fig. 1 shows the operation of a plank chute having special latches which support the chute boards in such manner that they may be conveniently dropped into place to stop the flow of ore.

Jan 1, 1926

By J. A. Ede

THE object of the writer is to call attention to a rather unique aggregation of economic products distributed over a line of succeeding formations about 3 mi. long, to be seen within a few miles of La Salle, Ill. Fig. 1 is an ideal section of the stratification exposed and exploited along a distance of 3 1/5 mi. in a southwesterly direction from the quarry of the Utica Hydraulic Cement Co. located near the historic site of Kaskaskia village to the Oglesby, shaft at Oglesby. No attempt has been made to cover the whole field, special mention only being made (with the exception of two places) of the operations found along the course or parallel to the direction assumed in the ideal section. I have used Fig. 2, after J. H. Bent and De Witt Kelly, to locate the relation of the La Salle anticline to the coal mines of this district and to show the operation of No. 1 and 3 mines of the Illinois Zinc Co.

Jan 9, 1919

By N. Plint, E. T. Pinkney

Copper segregation developments within the Anglo American Group are described with particular reference to the work of the TORCO Project Team. Some radical differences have been adopted in the mechan-ical approach as compared with methods used by previous workers. Most important among these are the following: (1) The heating unit is a fluidized-bed roaster. (2) A moving bed segregation chamber is used in which a packed bed of heated ore, to which reagents have been added, moves slowly downwards under gravity and is discharged at a controlled rate by means of a suitable valve mechanism. (3) The quantities of reagents used (sodium chloride and some form of carbon) are only a small fraction of those recommended by other investigators. (4) Retention times of only 2 min have been satisfactory for the complete segregation of many types of ore. Project TORCO is the code name given by Anglo American Corp. of South Africa, Ltd., to the investigation undertaken in Zambia to develop a plant capable of treating large tonnages of refractory copper-bearing ores by the segregation process. The process has now been under investigation for six years (1960-66) and during that period work has progressed from bench-scale laboratory tests through small-scale pilot-plant work to a 500-tpd commercial pilot unit. Test work has been carried out mainly on the ores of the Zambian Copperbelt and results have been encouraging. Recoveries on the order of 90% have been obtained on all Copperbelt ores tested with high concentrate grades. PRELIMINARY INVESTIGATION Laboratory scale segregation test work on Nchanga banded sandstone ore and oxidized ore from Kansan-shi was originally conducted by Professor Maurice Rey. SociCtC Miniere et Mktallurgique de Pefiarroya, in 1957. Both ores responded favorably to the process. In November, 1960, the consulting engineers of Anglo American Corp. of South Africa, Ltd., initiated preliminary investigations on the application of the segregation process to Copperbelt ores. In early laboratory work, samples were heated in a closed, externally heated tube furnace for one hour at temperatures ranging from 800 to 830°C. The free moisture content of the ore feed was 4% and reagent additions were 0.5% salt and 1.0% coal. Both salt and coal were pre-crushed to -48 mesh Tyler.* All samples except an ore from the Bancroft mine responded well to the process and recoveries of over 90% were obtained. The presence of dolomite was responsible for the relatively poor recoveries from the Bancroft ore, as tests on one of the other ores with additions of calcite or dolomite confirmed. Recoveries dropped from 94 to 45% Grades of all the rougher flotation concentrates produced were low at 10-15% copper. The laboratory investigation was then followed up on a pilot-plant scale. An attempt was made to carry out the segregation process in a coal-fired 5-ft-diam fluidized-bed roaster. The feed consisted of a banded sandstone from Nchanga to which 0.5% sodium chloride had been added. Reducing conditions were maintained in the roaster by the addition of coal in excess of that required for heating the feed. The excess coal and added salt constituted the segregation reagents and the temperature of the bed was held at approximately 750°C. Recoveries of copper and grades of concentrates were low. The reasons for lack of success were: (1) The reaction is a gaseous one and a fluidized-bed roaster is therefore unsuitable as a segregation unit. (2) Coal in excess of that required for heating was introduced into the fluidized bed and under these conditions some of the copper would be reduced in situ. The term "reduced in situ" is used here to describe any copper mineral reduced to the metallic state in its original site within the ore particles. If this copper is to be recovered by subsequent froth flotation it must first be liberated from the gangue by grinding or some other method which, in practice, is usually not feasible on ores of this type.

Jan 1, 1969

By L. S. Darken

IT has been known for sometime that in an ionic lattice, such as that of Ag2S or FeO, the migration velocity of the anion may differ markedly from that of the cation, the cation being usually the more mobile. It has been shown, for example, that during the formation of silver sulfide tarnish on silver, the tarnish layer grows principally by the motion of silver cations through an essentially stationary silver sulfide lattice. Similarly, the growth of wüstite scale on iron proceeds principally by motion of iron ions, this being accomplished with the aid of vacant iron lattice sites into which the iron may readily move. Likewise investigations of solid solutions of various salts show that there is usually considerable difference in the mobility of the different cations. Measurements of the mobility of various metals in liquid mercury indicate that the various metals move at different rates relative to the mercury. In view of the foregoing it seems reasonable to suppose that when any single phase solution is acted upon by a field, the atoms of different elements respond in different ways; in particular, that the force arising from a particular concentration gradient in a binary alloy would cause the atoms of one component to move with a drift velocity which is in general different from that of the atoms of the other component. The recent experiments of Smigelskas and Kirkendall1 support this viewpoint, since they found, in essence, that during diffusion in alpha brass zinc moves appreciably faster than copper. This was evidenced by the relative motion of inert molybdenum wires. Such a phenomenon is incompatible with the place interchange theory of diffusion proposed by several authors, most recently by Birchenall and Mehl.2 This theory has, however, also been questioned3.4 for other reasons, principally because of the high energy required for direct atomic interchange. The rather large difference between self-diffusivity, as determined by tracer technique, and mutual diffusivity, as determined with the aid of another element at low concentration, might also be interpreted as favoring the above idea; however, Birchenall and Mehl have pointed out that there is another possible interpretation of this difference; this is discussed later. A rather interesting and pertinent observation was made by Schwartz,5 who noticed that tungsten lamp filaments, heated by direct current, commonly fail by necking down in the region at the temperature gradient near the positive end, with a concomitant swelling at the corresponding position near the negative end. He introduces considerable auxiliary evidence to show that this phenomenon is occasioned by the motion of tungsten cations which migrate in the high temperature region from the positive end toward the negative end. The mechanism of this migration is not clearly understood. If, however, this experimental evidence be accepted, we are forced to conclude that alloying elements in the tungsten may migrate by the same or a similar mechanism, whatever it may be, at a greater or lesser rate, thus giving rise

Jan 1, 1948

By Clarence Zener

The heat-treatment of steels will not pass from the stage of an art into that of a science until the mechanism of the phase transformations associated therewith is thoroughly understood. Such an understanding will involve two distinct types of inquiry: (I) the direction of the transformation, (2) the speed of the transformation. The first type of inquiry, which involves only the equilibrium relations between the various phases in steel, is the subject of the present and of a succeeding article; the second type, which involves the kinetics of transformations, will be the subject of a later article. In order that a theory of equilibrium relations may give useful information, certain experimental data must be put into the theory. It is customary for these data to be of a thermal nature. In the system discussed herein—steel—such thermal data are very scarce. In medium-alloy steels another type of data might possibly be used. In these steels the concentration of solute is so low that it may be possible to use the approximation of dilute solutions, an approximation that leads to linear relationships. The unknown functions, or constants, may then be determined in some cases from the binary iron-alloy system and in other cases from the ternary iron-carbon-alloy system. From the functions, or constants, so determined may then be computed the equilibrium relations in more complex medium-alloy steels. In the present article this second approach is used, the necessary experimental data 'being obtained from the simple binary and ternary equilibrium diagrams. Fundamental Equations In this article are derived the equilibrium relations between the gamma, alpha and cementite phases. In these three phases all important alloying elements except carbon form substitutional solutions, each alloying atom occupying a potential site for an iron atom. Carbon, on the other hand, forms an interstitial solution. In the face-centered cubic gamma phase, the interstitial positions are at the center of the unit cube and at the centers of the cube edges. There are therefore four interstitial positions per unit cell, or one per iron atom. In the body-centered cubic alpha phase, the interstitial positions are probably at the face centers, and also at the centers of the edges, which are crystallographically equivalent to the face centers. There are therefore six interstitial positions per unit cube, or three per iron atom. In cementite, (Fe, Alloy)3C, the carbon atoms may. be regarded as filling all the lattice positions of a given type. The introduction of the fundamental the of equilibrium has presented the author with a quandary. These equations are formally so similar to other equations that have been derived1,2 for related systems that they may appear to some readers

Jan 1, 1947

By George H. Cunningham, Allen C. Jephson

The plant for production of electrolytic zinc recently erected by the American Smelting and Rcfining Co. is situated along Nueces Bay, on the Gulf Coast, some 5 miles west by rail and highway from the city and port of Corpus Christi. A ship channel from the port now approaches to within 2 miles of the site. It is expected that this will be extended at some future date and so provide direct water shipment from the plant. In addition to Gulf shipping, an intercoastal waterway connects Corpus Christi with Houston and New Orleans. Factors leading to the establishment oi this plant in the area were: ample supplies of natural gas for the generation of electric power, advantageous shipping lanes, favorable market for acid, adequate supply of labor, and moderate climate. General Description The plant was erected primarily to assist with the production of high-grade zinc much needed for war purposes. Production started during October 1942. The purity of the slab-zinc output meets the American Society for Testing Materials' special high-grade spccifications. Other products of the plant are electrolytic cadmium and sulphuric acid. Residues containing lead, copper and silvcr are sent for treatment to the Company's smelter at El Paso, Texas. The design of the plant includes the use of Trail suspension roasting equipment, contact acid equipment, also batch leaching in mechanically agitated tanks, pressure filtering and washing of leach pulp, batch purification in mechanically agitated tanks followed by clarification in filter presses and cooling of purified solution by evaporation. Electrolysis is performed in cells using Tainton alloy anodes and aluminum cathodes. Cathode current density is 60 amp. per square foot. Except for the portion returned to the leaching division, the cell solution is continuously flowing in closed circuit through the cells to cooling towers, which hold cell temperatures within desired limits. Direct current for electrolysis, is supplied by generators driven by steam turbines. The cathode zinc is melted in a gas-fired furnace and cast in the usual way into slabs for shipment. The plant divides into five major divisions: Concentrates Storage, Roasting and Acid, Leaching, Electrolysis, Melting and Casting. No attempt is made to give many tabulated data in this paper; it is mainly a general description of the divisions and methods employed for operation. A plan is shown in Fig. I and a general flowsheet in Fig. 3. Concentrates Storage The original plan for inward shipments was to receive zinc concentrates by steamer at the port of Corpus Christi, there to unload into open railroad cars and move into the plant by rail. Up to the present, however, concentrates have been received mainly in box cars from mines in Mexico.

Jan 1, 1944

By Clarence Zener

The heat-treatment of steels will not pass from the stage of an art into that of a science until the mechanism of the phase transformations associated therewith is thoroughly understood. Such an understanding will involve two distinct types of inquiry: (I) the direction of the transformation, (2) the speed of the transformation. The first type of inquiry, which involves only the equilibrium relations between the various phases in steel, is the subject of the present and of a succeeding article; the second type, which involves the kinetics of transformations, will be the subject of a later article. In order that a theory of equilibrium relations may give useful information, certain experimental data must be put into the theory. It is customary for these data to be of a thermal nature. In the system discussed herein—steel—such thermal data are very scarce. In medium-alloy steels another type of data might possibly be used. In these steels the concentration of solute is so low that it may be possible to use the approximation of dilute solutions, an approximation that leads to linear relationships. The unknown functions, or constants, may then be determined in some cases from the binary iron-alloy system and in other cases from the ternary iron-carbon-alloy system. From the functions, or constants, so determined may then be computed the equilibrium relations in more complex medium-alloy steels. In the present article this second approach is used, the necessary experimental data 'being obtained from the simple binary and ternary equilibrium diagrams. Fundamental Equations In this article are derived the equilibrium relations between the gamma, alpha and cementite phases. In these three phases all important alloying elements except carbon form substitutional solutions, each alloying atom occupying a potential site for an iron atom. Carbon, on the other hand, forms an interstitial solution. In the face-centered cubic gamma phase, the interstitial positions are at the center of the unit cube and at the centers of the cube edges. There are therefore four interstitial positions per unit cell, or one per iron atom. In the body-centered cubic alpha phase, the interstitial positions are probably at the face centers, and also at the centers of the edges, which are crystallographically equivalent to the face centers. There are therefore six interstitial positions per unit cube, or three per iron atom. In cementite, (Fe, Alloy)3C, the carbon atoms may. be regarded as filling all the lattice positions of a given type. The introduction of the fundamental the of equilibrium has presented the author with a quandary. These equations are formally so similar to other equations that have been derived1,2 for related systems that they may appear to some readers

Jan 1, 1947

By Francis S. Kendorski

INTRODUCTION Nuclear waste has been generated since the time of the Curie's and continues to be generated worldwide at an ever-increasing rate as the world will (and should) rely more and more upon fission (and hopefully fusion) for power. Also, the needs for strategic weapons will also generate so-called defense wastes. The largest class of high level nuclear waste (HLW) is spent fuel, the tail end of the nuclear reactor fuel cycle. At present, spent fuel is stored at the reactors producing it or at a few accepting places for away-from-reactor storage. All such storage facilities, as presently constructed, will begin to run out of usable storage space during the next decade or so. Congress enacted and President Reagan signed into law in early 1983 the National Nuclear Waste Policy Act of 1982. This law provides for the permanent isolation of nuclear waste in deep geologic repositories. The Act sets 1998 as the date at which the first repository should be operational. This date is extremely ambitious, and the Department of Energy (DOE), which is charged with the responsibility of constructing and operating repositories, admits that this date will slip by at least a few years. The Act also provides for licensing of repositories by the Nuclear Regulatory Commission (NRC) in a fashion very similar to nuclear power generating reactors. This requirement imposes a very special rigor on the analyses, investigations, designs, construction, and operation of repositories so as to assure the protection of the public and the environment from radioactive contamination. In addition the states and affected Indian Tribes must be consulted, especially concerning siting, and, needless to say, no one wants a HLW repository in their back yard.

Jan 1, 1984