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By E. C. Carris

THE loading of bituminous coal mechan¬ically was recognized about the year 1900, but during the following 28 years less than 5 per cent of the bituminous pro¬duction in the United States was loaded by mechanical means. During the past i6 years, however, the usage of some form of mechanical loader has had a very rapid and accelerated growth, until at present production of bituminous coal by mechanical means has reached an all¬time high of approximately 46 per cent, and is still increasing. This rapid growth in the use of the mechanical loader has been supplemented by an increase in mechanical cleaning. The importance of mechanical cleaning of coal was recognized many years before the mechanical loader was introduced, because of the impossibility of cleaning manually the sizes below 2 in., and the increasing competition from other fuels. Utilization of mechanical loaders without mechanical cleaning on the surface for at least one or more sizes is the exception, rather than the rule. One exception is a mine that employs caterpillar-mounted mobile loaders exclusively, and mines the entire seam without any selectivity, and yet loads and ships six grades of coal of the very highest quality without mechanical cleaning. Such a fortunate situation can exist only where mining conditions are ideal, where top and bottom are exceptional and there are no impurity partings, and where there is loader height. The conversion from hand loading to mechanical loading has definitely intro¬duced many problems in the preparation plant of yesterday and in the modern streamline plant as well. Many of these problems have been solved by good, sound, conscientious initiative on the part of the plant personnel, with minor expendi¬tures; the solution taking the pattern of rearranging and improving the equipment at hand. Other problems have caused, and are causing, considerable concern and difficulty. LARGE IMPURITIES The removal of large quantities of large impurities from the lump coal, and their handling and disposal, is definitely a troublesome and costly problem. The cost of manually removing the impurities from the picking table alone, based on the actual recovered lump coal, can reach a cost of 42 cents per ton or more. In the design of future plants it would be wise to give this phase of preparation considerably more time and thought, particularly if the seam of coal contains one or more heavy partings and the mining procedure is all seam. This same caution applies to seams that may not contain heavy partings but have poor and heavy draw-slate top, which falls with the coal during the mining cycle. One of the more recent of the modern preparation plants has answered this problem by installing a rock crusher under the picking table in such a manner that the impurities can be diverted by gravity directly to the crusher. This reduces the

Jan 1, 1946

By J. Offeringa, C. van der Poel

The report describes scaled model experiments on the recovery of oil from porous sands by the injection of miscible liquids [solvents] and the subsequent recovery of the solvents by water flooding. Special attention has been paid to the scaling problem. Scaling rules are deduced and their correctness is checked by carrying out experiments in tubes of various sizes. Data are submitted on the effect of the viscosity ratio oil-solvent on the efficiency of the displacement process, the viscosity ratio varying from 1.5 to 5,000. Breakthrough recoveries obtained when flooding with kerosene as a solvent, are equal to those obtained in water flooding at the same viscosity ratio, indicating that he phenomenon of viscous fingering is decisive. After breakthrough, however, flooding with a miscible liquid becomes much more efficient than a water flood and this is more pronounced as the viscosity ratio oil-solvent is higher. Although high oil recoveries are obtained and most of the solvent in the sand can be recovered by a subsequent waterdrive, a straight flood with miscible liquids does not appear economically attractive because of the large quantities of solvent required. Therefore, a circulation process is introduced, the features of which are described in this paper. Though by means of this circulation process the amount of solvent required can be drastically reduced, the process is not yet economic. SCOPE OF THE INVESTIGATION The recovery efficiency by water flood of oils of viscosities exceeding 50 cp is low. As interest in production of these highly viscous oils is growing at the moment, it was considered worthwhile to gain basic information on the feasibility of first flooding such oils with a low viscous miscible liquid [solvent] and subsequently producing the latter in a conventional way, e.g. by water flooding. The method has the obvious drawbacks that return on the investment is delayed until water flooding has begun and that it requires the investment of a more valuable product to produce a less valuable one. On the other hand, it may be expected that the displacement of one liquid by another is more efficient when the two liquids are miscible than when they are immiscible. As laboratory data on this point are scanty, the present investigation seemed justified. Another argument for carrying out these experiments is that they present a valuable contribution to our concepts of the scaling problem in reservoir engineering studies. Some major difficulties which are encountered in the scaling of the waterflooding process such as the scaling of the capillary forces and the difficulty of obtaining the same permeability characteristics in the model do not present themselves in this case. As the fluids are miscible capillary forces do not play a role and as there is only one fluid phase, Darcy's law is valid in its original form. Consequently it is felt that the scaling rules can be deduced with a greater amount of certainty. An essential feature of the experiments is that they are scaled model ones, which are, however, somewhat

Jan 1, 1955

By V. R. Garfias

EVEN before the arrival of Cortes in 1519, the history of Mexico was closely linked to that of its mineral production; the mining activities of the Aztecs being thus described by Clavigero, one of the early historians: In the mountains of Anahuac there abound in veins all kinds of metals, and infinite variety of other fossiliferous products. The Aztecs obtained gold from the countries of the Cohuijques, of the Mixtecas, of the Zapotecas and from various other places. They gathered that precious metal usually in grain, from the sands of the rivers, keeping a certain portion for the crown. They obtained silver from the mines of Taxco, of Tzumpango and others; however, this metal was not as esteemed by them as by other neighboring nations. They had two kinds of copper; one hard, which they used instead of iron to make sickles, lances and all kinds of rural and military instruments and another, soft, with which they made kettles, goblets and other receptacles. This metal abounds mainly in the province of Zacatula and in that of Cohuijques, which at present is in the kingdom of Michoacan. They obtained tin from the mines of Taxco and lead from those of Izmiquilpan, located in the country of the Otomiea. From the tin they made money, and the lead, we know they sold in the market places, but we ignore the uses to which they applied it. They also had mines of iron in Tlaxcala, in Taxco and in other places; but they either had not discovered them, or did not know how to make use of the metal they contained. In Chilapa there were mines of mercury, and in other places there were mines of sulphur, alum, vitriol, cinnabar, cohre and of a white earth which they esteemed highly. As regards mercury and vitriol, we do not know of what use they were to them; the other metals they used in paintings and dyes. There were then great abundance of amber and asphalt-bitu- men of Judea--on the coast of the seas and many cities of that territory paid tribute of one and the other to the kingdom of Mexico. They mounted the amber in gold, and it was only used as ornament and display by them. With the asphalt they made certain perfumes. The following extracts dealing with pre-Colonial gold are taken from the famous "Cartas de Relación" to Charles V, in which Cortea described the progress of the Conquest: . . . here there came two chiefs who owned lands in the valley; one four leagues down the valley and the other two leagues up the valley and they gave me some gold necklaces of little value and seven or eight girls. . . . . . . that day I left the City of Churultecal and traveled four leagues to some villages of the City of Cuasucingo where the natives received me very well and gave me women and pieces of gold. . . .

Jan 1, 1937

By V. R. Garfias

Even before the arrival of Cortes in 1519, the history of Mexico was closely linked to that of its mineral production; the mining activities of the Aztecs being thus described by Clavigero, one of the early historians: In the mountains of Anahuac there abound in veins all kinds of metals, and infinite variety of other fossiliferous products. The Aztecs obtained gold from the countries of the Cohuijques, of the Mixtecas, of the Zapotecas and from various other places. They gathered that precious metal usually in gain, from the sands of the rivers, keeping a certain portion for the crown. They obtained silver from the mines of Taxco, of Tzumpango and others; however, this metal was not as esteemed by them as by other neighboring nations. They had two kinds of copper; one hard, which they used instead of iron to make sickles, lancea and all kinds of rural and military instruments and another, soft, with which they made kettles, goblets and other receptacles. This metal abounds mainly in the province of Zacatula and in that of Cohuijques, which at present is in the kingdom of Michoacan. They obtained tin from the mines of Taxco and lead from those of Izmiquilpan, located in the country of the Otomies. From the tin they made money, and the lead, we know they sold in the market places, but we ignore the uses to which they applied it. They also had mines of iron in Tlaxcala, in Taxco and in other places; but they either had not discovered them, or did not know how to make use of the metal they contained. In Chilapa there were mines of mercury, and in other places there were mines of sulphur, alum, vitriol, cinnabar, cohre and of a white earth which they esteemed highly. As regards mercury and vitriol, we do not know of what use they were to them; the other metals they used in paintings and dyes. There were then great abundance of amber and asphalt—bitumen of Judea—on the coast of the seas and many cities of that territory paid tribute of one and the other to the kingdom of Mexico. They mounted the amber in gold, and it was only used as ornament and display by them. With the asphalt they made certain perfumes. The following extracts dealing with pre-Colonial gold are taken from the famous " Cartas de RelaciÓn " to Charles V, in which Cortes described the progress of the Conquest: . . . here there came two chiefs who owned lands in the valley; one four leagues down the valley and the other two leagues up the valley and they gave me some gold necklaces of little value and seven or eight girls. . . . . . . that day I left the City of Churultecal and traveled four leagues to some villages of the City of Cuasucingo where the natives received me very well and gave me women and pieces of gold. . . .

Jan 1, 1937

By Kendall E. Born

Production of crude oil in Tennessee during 1944 was slightly more than 9500 bbl., about 1300 bbl. more than 1943. Approximately 8000 bbl. was produced from the "Mississippi lime" in Scott and Morgan Counties. Some half dozen wells in Clay, Pickett, and Fentress Counties, pumped intermittently, produced about 1500 bbl. This production is from rocks of Ordovician age ranging in depth from less than 500 ft. to approximately 1000 ft. Natural gas was marketed from wells in Morgan and Fentress Counties for consumption in the Sunbright and Jamestown areas, respectively. The production of oil by counties is shown in Table I. Developments There were 20 completions during 1944 totaling 19,615 ft., nearly twice as much as in 1943. One well was drilling on Dec. 31, 1944. Of the 20 completions, one was a small oil well soon abandoned. Three gas wells were completed which are used locally. The completions are listed in Table 2. The distribution of tests according to physiographic divisions is given in Table 3. Cumberland Plateau There were five completions in the northern part of Cumberland Plateau. One was a small gas well in the Cooper pool 3 miles west of Oneida, but an attempt to extend the pool to the south resulted in a dry hole. The most active area in the state during 1944 was the northern Cumherland Plateau, especially in Cumberland, Morgan, and Scott Counties. Several blocks, aggregating more than 500,000 acres, were assembled and leasing was continuing in the early part of 1945. Surface work has been, or is being, carried on by at least four companies. While in an area of past oil and gas production from the "Mississippi lime," the principal interest appears to be in the essentially unexplored pre-Mississippian possibilities. The Knox dolomite group of Cambro-Ordovician age is receiving some attention as a possible reservoir. As the year closed one well was drilling on a surface structure near Lantana, 6 miles southwest of Cross-ville. This test will be drilled into the upper part of the Knox. Late in 1944, it was planned to lay a gas line from northern Morgan County to Oneida in Scott County, a distance of approximately 20 miles. Middle Tennessee Fifteen wells were drilled in Middle Tennessee. In the northeastern Highland Rim area there were 11 completions, one

Jan 1, 1945

By J. R. Long, T. R. Graham, C. W. Matthews, R. S. Dean

IN a previous paper§ the authors reported on the mechanical properties of a 65 per cent copper, 10 per cent manganese, 25 per cent zinc alloy as compared with similarly processed cartridge brass. Additional investigations by these laboratories, on higher copper alloys, have demonstrated that at lower zinc concentrations even larger amounts of pure manganese may be added to copper-zinc alloys without exceeding the single-phase solid solution limits, and that similar increases in tensile strength, yield strength, and hardness may be obtained without excessive decreases in ductility. Several compositions in this range showed also a decided color change with increasing manganese. The normal "brassy" color was considerably lightened and reduced to a faint yellow cast at 15 per cent manganese. With higher manganese contents the alloys were essentially white and similar in appearance to the nickel-silver alloys. From this work it appeared that it would be desirable to determine more completely the properties of the wrought and annealed white alloys. Accordingly, a more detailed study was planned of an alloy having the composition 70 per cent copper, 20 per cent manganese, and 10 per cent zinc. This alloy remained single-phase throughout the working and annealing cycles of the preliminary tests and appeared to be about the strongest of the white single-phase alloys. The project included also an investigation of additional alloys, deviating from this composition by 5 per cent of each of the three components to evaluate the effects of variation in composition; also a study of the properties of the central alloy made with silicothermic manganese. MATERIAL PREPARATION Electrolytic manganese, wirebar copper, and electrolytic zinc were used for the preparation of the alloys. Representative analysis of the electrolytic manganese seldom exceeds 0.01 per cent iron, 0.02 per cent sulphur and 0.02 per cent lead, with no silicon or aluminum. A typical sample of the silicothermic manganese metal contained 2 per cent iron, 0.81 per cent silicon, 0.i6 per cent carbon, and 0.36 per cent aluminum. Melting and alloying were performed in a high-frequency furnace with magnesia crucibles. Melts were deoxidized with small aluminum additions and cast into 25-lb. slab ingots. Care was exercised in deoxidation to avoid excessive amounts of residual aluminum, which has been found to have significant effects on alloys in this system. All ingots were hot-rolled at 1200° to 1300°F. and then cold-rolled with intermediate anneal-

Jan 1, 1945

By J. R. Long, T. R. Graham, C. W. Matthews, R. S. Dean

In a previous paper! the authors reported on the mechanical properties of a 65 per cent copper, 10 per cent manganese, 25 per cent zinc alloy as compared with, similarly processed cartridge brass. Additional investigations by these laboratories, on higher copper alloys, have demonstrated that at lower zinc concentrations even larger amounts of pure manganese may be added to copper-zinc alloys without exceeding the single-phase solid solution limits, and that similar increases in tensile strength, yield strength, and hardness may be obtained without excessive decreases in ductility. Several compositions in this range showed also a decided color change with increasing manganese. The normal "brassy" color was considerably lightcncd and reduced to a faint yellow cast at 15 per cent manganese. With higher manganese contents the alloys were essentially white and similar in appearance to the nickel-silver alloys. From this work it appeared that it would be desirable to determine more completely the properties of the wrought and annealed white alloys. Accordingly, a more detailed study was planned of an alloy having the composition 70 per cent copper, 20 per cent manganese, and 10 per cent zinc. This alloy remained single-phase throughout the working and annealing cycles of the preliminary tests and appeared to be' about the strongest of the white single-phase alloys. The project included also an investigation of additional alloys, deviating from this composition by 5 per cent of each of the three components to evaluate the effects of variation in composition and a study of the propertics of the central alloy made with silicothermic manganese. Material Preparation Electrolytic manganese, wirebar copper, and electrolytic zinc were used for the preparation of the alloys. Representative analysis of the electrolytic manganese seldom exceeds 0.01 per cent iron, 0.02 per cent sulphur and 0.02 per cent lead, with no silicon or aluminum. A typical sample of the silicothermic manganese metal contained 2 per cent iron, 0.81 per cent silicon, 0.16 per cent carbon, and 0.36 per cent aluminum. Melting and alloying were performed in a high-frequency furnace with magnesia crucibles. Melts were deoxidized with small aluminum additions and cast into 25-lb. slab ingots. Care was exercised in deoxidation to avoid excessive amounts of residual aluminum, which has been found to have significant effects on alloys in this system. All ingots were hot-rolled at 1200' to I300°F. and then cold-rolled with intermediate anneal-

Jan 1, 1945

By Richard H. Willey

EFFICIENT handling of large tonnages in open-pit mining demands, primarily, an abundance of well fragmented rock. To accomplish this, a drilling and blasting department composed of a well-knit, versatile group of workers and supervisors must be established. Some costs will remain relatively on the same level over a period of years, while others can be greatly lowered as will be shown. The Utah Copper Division, Kennecott Copper Corp., Bingham Canyon, Utah, has been ever alert for improvements in operating methods and equipment to gain increased efficiency and lower costs. BINGHAM CANYON MINE The greatest dimension of the mine is 8000 ft northeast-southwest with a width of 5000 ft southeast-northwest. From the lowest level, at an elevation of 6040 ft above sea-level, the mountain rises in 27 benches on the west side to W level (elevation 7800 ft) and 21 benches on the east side to Q level (elevation 7460 ft). At the inception of open-pit mining in 1906, the overcapping of leached porphyry had to be removed to reach a commercial grade of sulphide ore. The overcapping or waste now remaining is quartzite with intercalated limestone beds. The limestones are usually soft in nature except in the south-middle portion of the mine where they have been metamorphized along the contact zone. This area usually gives drilling and blasting operations a great deal of trouble. Here occurs the greatest amount of secondary blasting, as the well-established fracture planes cause the altered beds to break into large boulders. Several massive quartzite "ribs" occur in the overburden, and as a result, the uniform breakage is difficult to obtain. The major quartzite areas have been subjected to complex folding, fracturing and faulting because of the intrusion of the underlying stock. The monzonite porphyry, which carries the commercial values, presents no serious drilling problem because of its softness and extensive minute fracturing throughout the mass. A series of major slips or faults pass through the ore body which, although of considerable advantage to the drilling and blasting department, sometimes works to the disadvantage of the track department. Drilling and blasting of the porphyry apparently becomes easier as depth is attained, but highly siliceous streaks throughout the pit still present difficulties. At no place is the rock of such character as to allow excavation without preparations. On certain higher elevations or levels, old fill material can be dug by the shovels, but only at some risk to equipment because of bank slippage. PAST METHODS At the outset of shovel operations in 1906, drilling was done with the Ingersoll-Rand F-24 piston drill mounted on an un-

Jan 1, 1947

By W. H. McFarland

The mechanical properties have been determined for a large number of alloy-free martensitic steels with carbon contents ranging from 0.08 to 0.20 pct and with manganese contents of about 0.4 to 0.5 pet. These steels were tested 1) as water-quenched, 2) after quenching, temper rolling, and tinning, and 3) after tempering treatments which involved temperatures from 400o to 1300oF and times from 1 min to 8 hr. The majority of these tests represent steel from commercial-size coils, i.e., strip 32 in. wide, coil weights up to 20,000 16, and steel thicknesses from 0.0055 to 0.024 in. As a result of these treatments, it has been shown that as-quenched low-carbon alloy-free steels can be produced with tensile strengths ranging from 140,000 to 220,000 psi and tensile elongations from 3.0 to 4.0 pet in 2 in. The tensile strength of the as-quenched martensites can be represented by the equation, tensile strength (ksi) = 119 + 560 (wt pet C). The response to tempering of these steels is related to previous work by Muir, Averbach, and Cohen and by Grange and Baughman. Strain aging of low-carbon martensite has also been investigated. If low-carbon steels are defined as those steels with a maximum carbon content of 0.2 pet, it is found that the literature on low-carbon, alloy-free martensites contains little data on the mechanical properties of these steels. However, the following facts concerning low-carbon alloy-free martensites seem firmly established:'-' 1) The major factors in controlling the strength of the martensite appear to be a) fine structure, b) the internal strain resulting from the transformation, and, particularly, c) the amount of carbon in solid solution. 2) In low-carbon steels, the martensite is auto-tempered and is in the form of needles with only minor amounts of internal twinning, whereas the martensite in high-carbon steels forms as plates which are internally twinned on a fine scale. 3) Care must be taken in comparing the results of work that has been done on low-carbon steels with varying amounts of alloying elements to data on plain carbon steels. As has been noted by Irvine, Pickering, and Garstone,6 alloying elements generally lower the martensite start temperature and, thereby, decrease the amount of auto tempering obtained during the quench. This makes it difficult to

Jan 1, 1965

By R. C. Mahon

The Homer iron-ore mine is at Iron River, Mich. Because it covers a large area, 400 acres, and because there was a considerable depth of water in the glacial drift above most of the ore bodies, this mine has presented a number of unusual and often difficult operational problems. The purpose of this paper is to discuss a few of the most important problems encountered. Surface Water Mining on this property was started on one 40-acre tract. The ledge in this area was the highest on the property and, although it was a real problem, water could be handled by underground pumping. During the first period of mining, drifts were driven just under the ledge and holes were drilled through to the surface material. In later years these drifts have been extended wherever possible. Although these drifts assisted in the drainage problem, it was evident they would not be sufficient alone. Before mining on a large scale could be started on this property, the water problem had to be solved. A number of test holes were put down to the ledge, and showed that there was an average 150 ft. of water-saturated glacial drift above the ledge over the rest of the mine. The upper 70 ft. was gravel and sand and the lower 80 ft. clay and hard pan, with some narrow seams of sand and gravel. It was evident that the water above the clay seam could not be drained off through openings in the ledge and for that reason it was decided to install surface drainage wells. This method of drainage was entirely new at that time and was pioneered at the Homer mine. The sinking of the first well was started in June 1929. Immediately following the first well a number of wells were sunk, but only to the top of the clay seam. This was done with the idea that a greater capacity could be obtained in a shorter time from gravel seams where the water flowed more freely and that the cost of pumping the water above the clay seam would be considerably less than if the wells had all been sunk to the ledge at once. Before the drainage of surface water was started, 1200 gal. per min. against a head of 800 ft. was being pumped from the mine. By March of 1932, with five surface wells in operation, the mine pumping had been reduced to 150 gal. per min. At this time we were pumping 5000 gal. per min., under an average head of 110 ft. from the surface wells. The total pumping costs were 30 per cent less than in 1929 because the greater capacity was being pumped at a much lower head. From 1932 to 1936 the mine was idle and all surface pumping was stopped. Since 1936, 10 new wells have been added with a total pumping capacity of 8000 gal. per min. at the present time. The water level has been lowered 70 ft. since surface pumping was started in 1929, and it is now approximately at the top of the clay. To remove the water below the clay seam, 11 of the 15 wells were sunk to the ledge.

Jan 1, 1946

By Clarence Zener

IT is customary to regard the stress-strain relation as consisting of two parts, the elastic region and the plastic region. The essential attribute of the plastic region is the presence of a permanent set, which remains upon removal of all stresses. The essential attribute of the elastic region is the absence of such a permanent set. Absence of a permanent set does not imply a linear relation between stress and strain, nor even a single valued relation. In fact, in no real metal is stress a single valued function of strain in the elastic region. The property of a solid in virtue of which stress and strain are not uniquely related in the elastic range will be called "anelasticity." The purpose of the present article is to review and correlate the past work upon the anelasticity of metals. The following paper by W. A. West124 describes investigations upon anelastic properties of iron. Many manifestations of anelasticity have been observed, the first as early as 1835 by Weber.1,2 In his experiments Weber subjected a specimen to a constant load (or deformation) for a given time, and then suddenly removed the load. He observed that most of the deformation suddenly disappeared, but that there remained a residual deformation, which disappeared only gradually with time, as is illustrated in Fig. I. The occurrence of a residual deformation which only gradually disappeared, Weber called the elastic after-effect (Elastische Nackwirkung). An extensive review of the early work upon elastic after-effects has been given by Auerbach.3 Another manifestation of anelasticity is the dependence of the elastic constants-e.g., Young's modulus upon the method of measurement. Thus, if dynamic methods are used, the measured value will depend upon the frequency of oscillation. Still another manifestation is dissipation of energy attending vibration, called damping or internal friction. One objective of metallurgical science is the understanding of the plastic and fracture properties of metals in terms of their microstructure. Through such an understanding will come the ability to design microstructure to give the desired mechanical properties. A study of an elasticity will furnish an invaluable aid in the attainment of this objective. Such studies, when properly guided, yield information regarding the relation between stress and strain in the individual components of the microstructure. In order, however, that this type of information may be obtained, it is necessary that the experimental studies of anelasticity be interpreted by the appropriate mathematical analysis. This article, therefore, starts with the mathematical formulation of anelasticity.

Jan 1, 1946

By C. Perez-Rosales

A statistical method for determining simultaneously some of the basic geometrical characteristics of porous media such as porsity, specific surface* mean pore width, mean grain thickness and absolute permeability is presented. The proposed method is characterized by its simplicity and the minimum amount of laboratory equipment that it requires. The experimental procedure used to evaluate the various geometrical characteristics is based 'pan the 'surface analysis Of a a In view of this fact the app1icability Of the method is limited to homogeneous and isotropic materials. INTRODUCTION The behavior of a fluid flowing through a porous medium depends, among other things, upon the internal geometry of the medium; hence the importance of developing efficient methods to determine the geometrical properties of porous materials. This paper describes a statistical method to determine simultaneously some of the basic geometrical properties of porous materials such as porosity, specific surface, mean pore width, mean grain thickness and absolute permeability. The mathematical formulation has been developed that the data required to calculate the various geometrical characteristics of a sample can be easily measured by analyzing a section of the sample with an evenly spaced grid. THEORY A simple way of obtaining information about the internal geometry of a porous material is to throw a point at random over a cross-section of a sample. l-Through this procedure the porosity can be detemined.l,2 By considering that the material is homogeneous and isotropic, and that the point is dropped many times, the porosity 4 is given by where N is the total number of times the point is thrown and n is he number of times the point falls within pore areas. Another simple manner of analyzing the structural characteristics of a porous material is to superimpose an arbitrarily long line on a cross-section so that its length is evenly distributed over the surface area. Through this procedure the porosity can also be determined. If L is the total length of the line, and 1 is the sum of the lengths of the line segments within void spaces, the porosity is given by 4 = —.1.............. (2) The advantage of this type of analysis is that geometrical characteristics other than porosity can be obtained. Thus, if c represents the number of intersections between the line and the perimeter of pores, it can be shown3 that the specific surface, defined as he surface area of pores per unit bulk volume, is given by To give a proper description of the internal geometry of a porous medium, it is necessary to define quantities that characterize the notions of pore size and grain size. Unfortunately, because of the complexity of porous materials, it is difficult to give exact geometrical definitions of what is meant by the ConCePtS of "poresl' and "grains", especially when dealing with consolidated materials. Never theless, one often talks about the "size of pores" and the "size of grains" without defining accurately the terms. A possible solution to this problem follows. Assume that an arbitrarily long line is placed on a section of a sample so that the line is evenly distributed over the surface area (see Fig. 1). 1n a system like this, each line segment within a void space will be, by definition, the pore width in a given location and direction. Consequently, if the

Jan 1, 1970

By Carl Lemke

SOME of the principal metallurgical difficulties en-countered in the differential flotation of lead-zinc-iron sulfide ores arise from the following causes: The oxidized, or partly-oxidized, condition of one or more of the minerals ; impurities in the minerals them-selves; composition and character of the gangue miner-als; soluble salts in the ore; and unfavorable metal ratios. In many of the ores received at a custom mill there are present appreciable amounts of oxidized' or partly-oxidized minerals, although the ores may be substantially sulfides. Often the ores are not oxidized at all when received but on account of operating condi-tions at the mill it is necessary to stock them for several months before they can be milled, and considerable oxi-dation takes place while they are lying in stock. In most ores received at Midvale, when oxidation is pres-ent, the lead and iron sulfides have been more affected than the zinc sulfide, but with some ores the zinc mineral has also become partly oxidized. Some ores, such as those taken from old mine-dumps or from old stopes, may show very little total oxidation, but the greater part of the valuable minerals has been sufficiently acted upon by oxidation to make the minerals very difficult to float. Ores of this character are among the most difficult the flotation operator has to contend with, be-cause the galena, sphalerite, and pyrite are all sluggish in their behavior in the flotation cells. Only a part of the lead mineral will float in the lead circuit. The re-mainder will lag badly and tend to come up with the zinc or, if badly oxidized, will go -through all the flota-tion circuits into the tailing. The zinc mineral, if it has also been affected by oxidation, will act in a man-ner similar to the lead mineral. A hard pull will be required to float a reasonable percentage of it, and this is likely to bring up so much pyrite that it will be difficult to make a zinc concentrate of commercial grade. If it happens that the zinc mineral has not been no-ticeably affected by oxidation it will tend to float in the lead circuit because a hard pull is also required in that circuit in order to bring up the sluggish galena. When only a fraction of the sulfide minerals has become partly altered, or completely oxidized mineral is present in relatively small quantity, it is usually possible to make reasonably clean concentrates of all three sulfides, that is, lead, zinc and iron concentrates. Most of the oxi-dized and semi-oxidized minerals will go into the tailing and the losses will be proportional to the oxidation.

Jan 4, 1927

By Donald W. Scott, L. A. Roe, B. J. Sweo

INTRODUCTION THIS paper describes the application of ore-dressing methods to the reclamation of milled frit from over-spray, or waste, porcelain enamel. Frit is the name given by enamelers to a granulated glass produced by the smelting and subsequent water quenching of various ingredients capable of forming a glass, usually including a compound to produce opacity. It is the major component of porcelain enamel, and normally commands a price ranging from 7 to 12 cents a pound. In the preparation of a white enamel slip, usually 6 or 7 parts of clay, 2 parts of opacifier, small amounts of electrolytes, in some cases inorganic color stabilizers and organic dyes, and 35 parts of water are added to loo parts of frit; the mixture then is milled to a fineness of the order of 92 to 95 pct through a 200-mesh sieve. The frit forms the base of the enamel; the opacifier imparts opacity or reflectance; the clay suspends the frit while in slip form and serves as a binder' in bisque form (dry and unfired); and the electrolytes control the workability. Spraying is used commercially, in many cases, to apply the finish coat of enamel to the ware, prior to drying and firing. In the spraying operation, only about 50 pct, by dry weight, of the enamel slip adheres to the surface of the ware, the remainder forms the over-spray. From 1/2 to 2/3 of the overspray goes up the flue where it is lost or recovered, depending on whether the plant is equipped with a dust-collecting installation; the coarser portion of the overspray is collected in the spray booth. The former product is termed flue reclaim enamel, and the latter booth reclaim enamel. Although the spraying operation is done in specially constructed booths, which are partially or completely enclosed, it is extremely difficult to keep out contaminating dirt, which joins the reclaim. Some present-day large enameling plants use 20 tons of frit a day, of which 10 tons go into reclaim with a potential value of $1400 to $2400. When two-coat finish enamels were common, the reclaim was used satisfactorily for the undercoat, but the relatively recent advent of one-coat finish enamels prevented use of the reclaim because, even when blended with first-run enamels, it gave dirty finishes with poor gloss. It was thought that the pitting and specking encountered with reclaimed enamels were caused by the contaminating dirt, and that the poor gloss was caused, primarily, by the high clay content; more clay usually was added to give proper suspension properties to the slip when the reclaim was used. A clay content in excess of about 10 pct usually imparted refractoriness to porcelain enamels. Present-day one-coat porcelain enamels must combine high gloss and opacity with freedom from surface defects. Methods of beneficiating the over-spray,

Jan 1, 1947

By Alec M. Crowell, Thomas D. Bailey

Although natural gas was first discovered in Northwest Arkansas in 1887, . near Fort Smith, Sebastian County, the literature contains very little information on the region, which is separated distinctly from the oil area of Southern Arkansas. For that reason this brief and concise report is a summary of developments from discovery to the present time. Northwest Arkansas produced 5,736,-ooo,ooo cu. ft. of natural gas during 1942, the trend of production having been generally upward over the past five years, as is shown in Fig. I. Since 1904 a reserve of 237 billion cubic feet of natural gas has been discovered in Northwest Arkansas, of which approximately 162 billion cubic feet have been expended, leaving a reserve of approximately 75 billion cubic feet available as of Jan. 1, 1943. A prolific new field discovered in Pope County Oct. 23, 1942, will add to the reserve of the region materially. Per well reserves, over-all, are unusually high because of the practice of multiple completion. As yet no commercial deposits of oil have been discovered in Northwest Arkansas. but the gas deposits have proved of immense value industrially, principally in the processing of zinc ore mined in the local area as well as that imported from distant states. With the war, new interest in the exploitation of the metallic ores of the region lends new significance to the gas reserves tabulated herein. Geological Discussion The region covered in this report comprises the Arkansas Valley from Pope County weslward to the Arkansas-Oklahoma state line as shown in Fig. 2. This valley is a westward trending structural trough with sharp-topped ridges and mesa-like mountains rising above the valley's undulating surface. It is bounded on the north by the Ozark Highlands and on the south by the Ouachita Mountains. The sedimentary beds of the Arkansas Valley are composed mainly of noniossil-iferous shales and sandstones. The rocks contain a high content of carbonaceous material and many coal beds are found in the region. The Gxed carbon ratios (ratio of fixed carbon to volatile combustible matter of surface coals) are very high and average about 80 per cent over the region covered in this report. Little or no calcareous material is present. Rocks of the Arkansas Valley are sharply folded, and igneous intrusive rocks cut the sedimentary beds at a few places. The Arkansas Geological Survey' made a detailed reconnaissance survey of the Arkansas Valley province in 1927, the purpose being to delineate the major structural features (Fig. 3) and to point out the possibilities of discovering addi. tional gas deposits. More than fifty anticlines were mapped as a result of this survey. The information gained by this

Jan 1, 1943

By Thomas D. Bailey, Alec M. Crowell

Although natural gas was first discovered in Northwest Arkansas in 1887, . near Fort Smith, Sebastian County, the literature contains very little information on the region, which is separated distinctly from the oil area of Southern Arkansas. For that reason this brief and concise report is a summary of developments from discovery to the present time. Northwest Arkansas produced 5,736,-ooo,ooo cu. ft. of natural gas during 1942, the trend of production having been generally upward over the past five years, as is shown in Fig. I. Since 1904 a reserve of 237 billion cubic feet of natural gas has been discovered in Northwest Arkansas, of which approximately 162 billion cubic feet have been expended, leaving a reserve of approximately 75 billion cubic feet available as of Jan. 1, 1943. A prolific new field discovered in Pope County Oct. 23, 1942, will add to the reserve of the region materially. Per well reserves, over-all, are unusually high because of the practice of multiple completion. As yet no commercial deposits of oil have been discovered in Northwest Arkansas. but the gas deposits have proved of immense value industrially, principally in the processing of zinc ore mined in the local area as well as that imported from distant states. With the war, new interest in the exploitation of the metallic ores of the region lends new significance to the gas reserves tabulated herein. Geological Discussion The region covered in this report comprises the Arkansas Valley from Pope County weslward to the Arkansas-Oklahoma state line as shown in Fig. 2. This valley is a westward trending structural trough with sharp-topped ridges and mesa-like mountains rising above the valley's undulating surface. It is bounded on the north by the Ozark Highlands and on the south by the Ouachita Mountains. The sedimentary beds of the Arkansas Valley are composed mainly of noniossil-iferous shales and sandstones. The rocks contain a high content of carbonaceous material and many coal beds are found in the region. The Gxed carbon ratios (ratio of fixed carbon to volatile combustible matter of surface coals) are very high and average about 80 per cent over the region covered in this report. Little or no calcareous material is present. Rocks of the Arkansas Valley are sharply folded, and igneous intrusive rocks cut the sedimentary beds at a few places. The Arkansas Geological Survey' made a detailed reconnaissance survey of the Arkansas Valley province in 1927, the purpose being to delineate the major structural features (Fig. 3) and to point out the possibilities of discovering addi. tional gas deposits. More than fifty anticlines were mapped as a result of this survey. The information gained by this

Jan 1, 1943

By R. J. Stevens

The Roan Antelope Smelter commenced operations in October, 1931. As originally designed, its equipment consisted of one reverberatory furnace, 120 X 25 ft, two Peirce-Smith converters 12 X 20 ft, and one straight line casting machine. Since that time the following additions have been made: One reverberatory furnace 120 ft X 28 ft ('934) One reverberatory furnace 95 ft X 28 ft (1943) Two 12 X 20 ft Peirce-Smith converters (1934 and 1938) One 13 X 30 ft holding furnace (1938) One straight line casting machine and 2 ladle tilting quadrants (1934) The metallurgy of the smelting process is comparatively simple. However, there are several features of operation which are uncommon to most copper smelters: (I) The high grade of concentrate treated; this has always been about 50 pct copper. (2) The high flux burden on the charge. This is necessary because of the deficiency of bases in the concentrate and the high alumina content of the concentrate. (3) The frequent necessity of adding coal to the furnace charge to control the matte grade. (4) The high grade of matte produced. This has led to unusual converter problems. From the commencement of operations, the ore mined has come from the Roan Basin orebody. The concentrate produced from this ore consists mainly of chalcocite and shale with small proportions of other copper minerals. As mining operations extend to the Roan Extension orebody, the proportions of bornite and chalcopyrite in the concentrate will increase with a corresponding decrease in the copper content of the concentrate. Because of the concentrate grade the capacity of the reverberatory furnaces in terms of tons of copper produced per ton of coal burned is high. This ratio is usually over 2.2, and on especially favourable runs has reached 2.6. Reference to Table I shows that the iron content of the concentrate is unusually low. Only part of this iron is available for slag formation, the balance going to the matte. To make up this deficiency in bases, limerock is added to the furnace charge. This flux ensures a slag that is of the correct silicate degree, is suficiently fluid, of low specific gravity, and it counteracts the thickening effect of the alumina present. An ample supply of flux is obtainable from Ndola, 22 miles distant by rail. Although the reverberatory slag has a high copper content, the slag fall is low and the copper loss in the slag now rarely exceeds 1.0 pct of the total copper charged. The blister copper shipped is of such purity that only one fire refining operation has been necessary to produce a wirebar with properties comparable to electrolytic copper. Bismuth has always been the most troublesome impurity and consequently the problem of its control in the finished product has been of prime importance. Practically none is removed in the reverberatory furnace. The bulk of the elimina-

Jan 1, 1949

By J. Chipman, N. J. Grant, J. C. Fulton

This paper contains data on the distribution of silicon between liquid iron-silicon-carbon alloys saturated with respect to graphite and CaO-SiO2-Al2O3 slags under 1 atm of CO at 1600°C. The ranges of slag compositions studied were extended from the dicalcium silicate saturated liquidus composition up to silica concentrations at which Sic appeared as a stable phase. IN blast furnace operation it is not to be expected that slag and metal reach equilibrium with one another. Nevertheless, the silicon content of the metal varies with slag composition and with temperature in a manner which would be predicted from equilibrium considerations. Similarly, the distribution of sulphur between slag and metal does not attain an equilibrium state, yet the influence of slag composition is strongly analogous to its effect on the distribution equilibrium. The desulphurizing power of metallurgical slags has been shown to be highly dependent upon the FeO content of the slag. Moreover, the rate of removal of sulphur from slags is influenced by the oxygen potential of the slag-metal system. Thus it was shown by Grant, Kalling, and Chipman1 that the presence of MnO in slags which are low in FeO causes a marked slowing down of the transfer of sulphur from metal to slag. This led to the hypothesis that the slow removal of sulphur by blast furnace slags of more acid composition might be due in part to the effect of SiO2 on the oxygen potential of the system. This was verified in the work of Grant, Troili, and Chipman,' who found that the desulphurizing power of the more acid blast furnace slags could be markedly improved by an increase in the silicon content of the underlying metal. Their explanation of this improvement was that the higher silicon content of the metal decreased the rate of transfer of more silicon and, along with it, of oxygen from the slag to the metal. The slowness of the transfer of sulphur from metal to slag was the result of the slow reduction of SiO2 from slag to metal. Attempts to study the rate of sulphur removal had in the past resulted in very slow rates corresponding to the rates of silica reduction. It has become evident on the basis of these studies that further experimental studies on the rate of removal of sulphur must take these factors into consideration if there is to be a clear understanding of the rate of sulphur transfer under conditions simulating those existing in the blast furnace. It will be necessary, at least in a part of such study, to employ combinations of slag and metal in which the disturbing effect of silica reduction has been eliminated; in other words, to employ slag-metal combinations which are already in equilibrium with respect to the transfer of silicon. In preparation for such studies of desulphuriza-tion, a preliminary program of research on the distribution of silicon between slag and metal has been undertaken. This will ultimately include a comprehensive survey of the effects of temperature and slag composition on the equilibrium distribution of silicon between slag and metal. The present paper is a report on experimental methods employed and on

Jan 1, 1954

By R. E. Carter, C. Wagner, F. D. Richardson

By means of inert markers of radio-platinum, it has been shown that cobalt metal oxidizes by out-ward diffusion of cobalt atoms through the oxide. Oxidation rates have been measured at various temperatures and oxygen pressures and have been found to agree with the rates calculated from the Wagner equation and the authors' values for the diffusion coefficient of cobalt in the oxide. The distribution of radio-cobalt in growing oxide loyers has been accurately measured and found to be different from that predicted from the Wagner oxidation theory. Attempts have been made to measure the change of lattice parameter of the oxide with composition. SEVERAL investigators have shown that cobalt metal oxidizes according to the parabolic law,1-3 but no detailed study has been made of the oxidation mechanism. Cobaltous oxide has a metal-deficient lattice, but the defect concentration which is dependent on the oxygen pressure is only approximately known.' From the similarities in the structures of "CoO" and "FeO" and the rate laws governing the oxidation of cobalt and iron, Gulbransen- as suggested that cobalt, like iron," oxidizes by diffusion of cobaltous ions through the oxide layer. To substantiate this hypothesis, he has attempted to measure the oxidation rate of cobalt as a function of the oxygen pressure but has been able to report only that the rate depends on a "small" power of the pressure. On the other hand, Preece," Valensi,' and Arkharov' all have suggested from indirect evidence that oxygen diffuses through the COO to the metal-oxide interface. The present authors, in a previous paper,' have shown that the rate of diffusion of cobalt in cobaltous oxide is dependent on the oxygen pressure. In that investigation, they also found that cobaltous oxide disks made by complete oxidation of cobalt metal were porous at their centers (Fig. 5L, ref. 4). Both these facts strongly suggest that oxidation of the metal proceeds via outward diffusion of cations. In order to establish the mechanism unequivocally, oxidation experiments were made with inert radioactive platinum markers, and the dependence of oxidation rate on oxygen pressure was measured. In addition, an attempt was made to determine the form of the cation vacancy gradient, which the marker experiment showed must exist across a growing oxide layer. This was done by depositing radioactive Co on the surface of a cobalt disk and then measuring the tracer distribution across the oxide layer produced by partial oxidation of the metal. Finally, an X-ray examination was made in an attempt to find the expected change of lattice parameter of COO with oxygen pressure. Experimental The apparatus and materials used were substantially the same as those previously described by the authors.4 Marker Studies: The use of inert markers to follow oxidation reactions was first attempted by Pfeil" in 1929, and radioactive markers have recently been used by Davies et al.' In the investigation reported here, the markers were applied as an (NH4)2PtCI6 slurry in several thin streaks across both faces of four disks of cobalt metal 1 mm thick and 14 mm in diameter. The disks were then oxidized almost to completion at 1200°C in pure oxygen. After oxidation, they were mounted and sectioned and auto-radiographs were taken to locate the markers. Oxidation Rate: The oxidation rate of cobalt was measured at 1148°C at oxygen pressures ranging from 0.0055 to 1.0 atm and at 1000°, 1148", and 1350°C under 1 atm of oxygen. The rate was deter-

Jan 1, 1956

C. M. Bishop (Aircraft Div., A. V. Roe Cnnada Ltd., Toronto)—Reference is made to the coherency hardening of ß due to ß' and also to the hardening of ß due to a coherent precipitation of the a phase. What is meant by the term "ß'?" Would not the coherency hardening of ß during cooling be due to precipitation of a sub-microscopic dispersion of a, as is the case during reheating a ß-quenched alloy? I feel that these two phenomena are essentially the same mechanism, i.e., precipitation of a from unstable or supersaturated ß. From the text, it would appear that Tables III and IV are intended to show the effect of the martensite transformation on the properties of Ti-Mn alloys. Referring to Table 111, the ß-quenched alloys would contain a greater proportion of retained ß than would the equilibrated alloy. Could not the increase in properties be attributed to this, along with possible coherency hardening of the ß? In the same way, the structures referred to in Table IV contain ß from which they could derive their hardness. It would appear to be difficult, if not impossible, to assess the role of the martensite transformation from the data contained in these tables. F. C. Holden, H. R. Ogden, and R. I. Jaffee (authors' reply)—In reply to the first question raised by Mr. Bishop, the term "ß"' designates an apparent retained-p structure which is harder than it is after the most rapid cooling from the ß field. It is thought to be the result of a coherent precipitation of a. The mechanism by which hardening takes place is undoubtedly the same as that involved in the early stages of aging of a re-tained-p structure, and we are in agreement with Mr. Bishop on this point. The term "ß'" to designate the anomalously hard retained-ß structure was agreed upon at a symposium in 1953." The authors do not agree that the quantity of retained ß and/or ß' in the ß-quenched specimens of Table III is necessarily greater than that of the 600°C equilibrated specimens. The ß-quenched specimen has a structure which appears to be completely a' formed by the martensite reaction. It is recognized that there could be some retained ß (or ß') between the a plates if the M, temperature is below room temperature. This is unlikely for the 3.4 pct Mn alloy where the M, is known to be at about 640°C. Therefore, the increase in strength cannot be attributed to the presence of a greater quantity of coherency-hardened ß, but, rather, the increase in strength must be attributed to the transformation products formed, e.g., a' (martensiti-cally formed a). Concerning the data in Table IV, we agree that it is difficult to estimate the role of the martensite reaction, since the 6.4 pct Mn alloy was retained ß in the quenched condition.

Jan 1, 1955