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By F. W. Jessen

The Mechanism of solution of salt and mixed halites of sodium and potassium is reviewed. The variation in the rate of salt removal under both laminar and turbulent flow conditions is discussed. Many changes are possible in the development of solution cavities whether used for production of salts or for storage of hydrocarbons. The parameters influencing the type and shape of cavity formed with single well or multiple well systems are examined and information presented regarding field application of techniques developed and the means of controlling overall configuration of solution cavities.

Jan 1, 1972

By Donald W. Jenkinson

Many types of gravity concentration equipment have been employed throughout the years since beneficiation of materials has been practiced. These include jigs, concentrating tables, vanners, sluice boxes, heavy media cyclones, and static heavy media separators or sink-float separators. In the beneficiation of coarse aggregate for concrete mixes, static heavy media separation employs the same principles of gravity concentration involved in separating lead-zinc ore, dolomite, limestone, diamonds, manganese, iron, and many other minerals. In aggregate beneficiation, as in most metallurgical operations, sink or heavy fraction is the product. The undesirable portion of coarse gravel is usually much lighter than the desirable particles, allowing most aggregates to be amenable to gravity concentration methods.

Jan 7, 1960

As REVISED IN CONFERENCE FEB. 17, 1931 REPORT OF SUBCOMMITTEE ON MINE VENTILATION CODE OF A, I. M. E. COMMITTEE ON VENTILATION ALFRED W. HESSE, Chairman THOMAS G. FEAR GEORGE S. RICE E. A. HOLBROOK WILLIAM A. ROWE HOWARD ECKFELDT R. V. NORRIS CADWALLADER EVANS, JR. H..1. SMITH, Secretary REALIZING, from the safety and health standpoint, the need of furnishing air of good quality to workers underground and of diluting and carrying away dangerous and noxious gases, the following code is offered to unify regulatory measures in coal mine ventilation, so far as is practicable, in the United States of America.

Jan 1, 1931

By Z. T. Bieniawski

The efficient and safe design of room-and-pillar coal mines still remains as one of the pressing problems facing the mining industry in the United States. Present day design is a trial-and-error approach based mostly on experience. Although much research has been directed to stability of mine roofs and coal pillars, no generally-accepted design method has been formulated. This paper reports on a three-year research effort directed to an improved design of room-and-pillar coal mining in the U.S.A. Essentially the study consisted of three aspects: (i) determination of stable roof spans; (ii) determination of the strength of coal pillars; and (iii) determination of safety factors for room-and-pillar coal mining in the United States. Furthermore, three novel approaches were utilized during this research: i) the "petite sismique" technique was assessed for possible determination of coal pillar deformability ii) the "Geomechanics Classification" was extended for determination of safe roof spans in room-and-pillar coal mining. iii) a national survey of the current design practice and mining dimensions was performed with the aim of assessing factors of safety for room-and-pillar coal mining The outcome of this work, which is summarized in this paper, is a design code for room-and-pillar mining in the United States.

Jan 1, 1983

Although the meeting of the Institute in St. Louis Will not occur until September, 1917, the committee in charge is already making attractive plans, and we append hereto a tentative skeleton program which will give some notion of the opportunities that will be offered: St. Louis is situated in the midst of. a district which contains not only a great many interesting examples of mining, but also all types of industrial manufacture of interest to members of the Institute, and it affords abundant opportunities to visit and see these plants. Further announcement will be made from time to time as the committee's plans take more permanent shape. .

Jan 2, 1917

By J. M. Karpinski

The need for standard test methods in the minerals beneficiation industry is growing with the increasing complexity of our processes and the more stringent requirements imposed on the quality and uniformity of our products. Although solutions of our problems have never been easy, they will become increasingly difficult to achieve unless we can develop a reliable and reproducible set of test methods. Historically speaking, our need was greatest for methods of chemical analysis. As these methods developed, they improved our ability to determine the grade of ore and measure the effect of our beneficiation attempts. The entire concept of grade and recovery is only as old as chemical analysis. Then came physical measurements. Each new concept in minerals beneficiation was related to certain properties and required corresponding test methods: specific density for jigging, magnetic susceptibility for magnetic separation, and tumbler strength for pellets. And associated with each process was the need for size determination. Size measurement is probably the first physical test ever conceived, and yet we are still improving on it. Dry sieving was quite acceptable for direct-shipping ores, but we had to go to wet sieving to control pelletizing and flotation. Subsieve analyzers have extended our routine measurements to the subsieve sizes, hut not below a few microns. As we all know, the solution of slimes- beneficiation and pollution-abatement problems is hampered by the lack of reliable and reproducible test methods in the fine-particle size range.

Jan 1, 1971

By William R. Barton

Iron and steel slag represent man's most successful attempt to date to profitably utilize a solid waste. Its consumption represents a solution to a solid waste problem and also represents tonnage of natural aggregates that will not have to be mined with concomitant disturbance of the land. Slag has been produced as long as iron has been made; but until a little more than 50 years ago, it was mostly a waste product to be disposed of with as little effort and cost as possible. Huge piles of waste slag were generated over the years of iron and steelmaking. Sporadic use was found for small amounts starting with slag (from Catalan forges) used for road bases by the Roman Empire. The first recorded sustained commercial use was, as is often the case in man's history, for making war. Some profit- conscious munitions maker in the 16th century realized that he could make cannon balls of slag instead of the more precious iron. Other small-volume uses gradually developed: cast building blocks, slag-lime mortars and cements, slag wool, ballast, road base, and, finally, in concrete. But it was not until after World War II that the true potential of blast-furnace slag as a construction aggregate was really recognized. Now nearly all blast-furnace slag produced is used, and much of the earlier stock- piles in the U. S. have been reduced or entirely consumed. Steel slag for aggregate use has been in commerce for only the past 10 years, and use has increased rapidly (10-50% per year) during the past 5 years as blast-furnace slag supplies became depleted. However, much remains to be accomplished in determining character and optimum conditions of use for various types of steel slags before such slags will realize their full use potential. Although slag represents only 2% of construction aggregate materials used in the U.S., its production involves certain features that make its production record far more important than national tonnage figures would indicate. Its source is in iron and steel production and concomitantly slag availability is restricted to those areas where iron or steel is produced. In such areas, it often represents one of the principal aggregates marketed and, because of special properties that make slag a selected aggregate for certain uses, the tonnage imbalance may be overcome by the importance of its contribution to quality or special characteristics of end products. The location and number (Fig. 1) of slag plants handling this annual production is governed by the geographic makeup of the iron producing industry. Prior to the period marked by World War 11, most blast furnaces were in the Great Lakes area-Pittsburgh, Cleveland, Chicago, Gary, Buffalo, Detroit, Youngstown, and Toledo, with exceptions at Baltimore, Bethlehem, and Birmingham. Since that time, iron and steel facilities have been established in Texas, Utah, and California. Today 85 slag plants in 15 states provide employment for almost 2000 persons. The slag plants also recover almost 4 million tons of slag-encrusted iron each year for return to the blast furnaces. Much of the success in developing uses for slag can be attributed to the efforts of the National Slag Association founded in 1918. Since then, it has conducted numerous field and laboratory investigations to demonstrate the properties and uses for slag and slag products. These investigations have resulted in total recognition of blast-furnace slag as a construction material of consequence. The American Society for Testing & Materials Designation C125 recognizes blast-furnace slag as "the nonmetallic product consisting essentially of silicates and aluminosilicates of

Jan 1, 1975

By D. V. Fites

The ripper is not a new tool. In fact, it dates back as far as the Roman Empire. The Roman's ripper-mounted on wheels and shaped something like a plow-was pulled by oxen and was used to loosen the earth for the shovelers and basket carriers building the Appian Way. There are records of rippers being used in this country in railroad construction between 1860 and 1880. The tractor-mounted ripper, introduced a little over ten years ago, extended the capability of the ripper because of greatly improved maneuverability and the additional weight which could be brought to bear upon the ripper tooth. Increases through the last ten years in tractor weight and horsepower further increased ripper capability until now, in some geographic areas, hardly any rock is unchallenged by them.

Jan 12, 1967

By Edward A. Sayre

In shaft sinking for cod mines, the cost item greatly influences the method adopted. This holds true especially when soft material must be traversed. The average life of a coal mine is short. This is due either to the limited area of the coal basin or to the great expense of maintenance and haulage underground when the entries are extended a considerable distance from the hoisting shaft. Therefore, the engineer in opening a coal mine is confronted with the fact that the cost must be kept within certain bounds else the venture will prove unprofitable. For this reason he may be prohibited from adopting certain safe, but expensive, methods that are used in sinking caissons for foundations, driving transportation tunnels, or other work of permanent construction. A common method of sinking through difficult ground employs the aid of a steel shoe pushed ahead of the shaft timbers. Another is the drop-shaft method. These two methods were used in sinking the main shaft and the air shaft of the Eagle No. 3 mine, at Des Moines, Ia., and the following data show the relative success and cost of the two methods of sinking under the same conditions. A drill log of the material to be penetrated was as follows (see Plate 1, Fig. 1): Thickness, Total Depth, Ft. In. Ft. In. Drift................................... 38 38 Sand..................................... 2 40 Drift.................................... 2 6 42 6 Jointed clay.............................. 5 6 48 Drift, firm............................... 10 6 58 6 Clay, with sand streaks.................... 3 61 6 Sand.................................... 12 73 6 Shale, with two thin beds of coal and thin strata of rock......................... 86 6 160 Rock.................................... 5 165 Coal..................................... 3 9 168 9 Main Shaft Sunk by Steel-Shoe Method This record shows the first 73 ft. to bc of drift material, the lower 12 or 15 ft. of which was sand. The remaining 92 ft. to the coal was shale and rock, and offered no trouble in sinking.

Jan 1, 1917

OUTSTANDING symbol of the machine age, the steam shovel needs no introduction. Few individuals there are, in the United States at least, that have not watched with fascination the almost human motion, the more than human strength, the rhythm of the whole steam-shovel cycle of crowding, digging, swinging, dumping, swinging, and crowding again. A mass of steel with some copper and other metals, fed with water and coal, guided by a single alert and dexterous operator, or perhaps two, does the work that would require 50 to 500 men or even more. The largest shovels working in the copper mines have loaded into waiting railway cars as much as 10,000 tons of ore in a single 8-hour shift. With no equipment but hand shovels, it would, in fact, be impossible to duplicate the work with any number of men; first, because they would be in each other's way, and second, because the steam shovel can lift single pieces of rock weighing 5 or 10 tons with effortless ease. Of recent years, internal-combustion engines and electric motors have displaced steam as a motive power in many instances; and of course the detailed design of the shovels has been improved immensely. Whereas the largest dippers used 30 years ago had a capacity of 3 ½ to 4 cu. yd., today the 350-ton shovel used at Chino has an 8-yd. dipper, as has the 320-ton shovel at Chuquicamata. Incidentally, for stripping at coal mines a shovel having an 18-yd. dipper is in use. However, the principle of operation of the modern shovel, regardless of the size and type of motive power, is essentially the same as that of the earlier shovels. It is fair to say that the indispensable of open-cut mining is the steam shovel, or, to be more precise, if perhaps less picturesque, the power shovel. Somehow the electric shovel seems to lack the glamour that

Jan 1, 1933

By M. Gensamer

ALTHOUGH a large number of X-ray photograms of cold-rolled steel have been published, two circumstances have led to the experimental work reported in this paper. The first is that no complete study, making use of the pole-figure method of Wever1, has been made of cold-rolled low-carbon steel. Wever has published pole figures of mild steel sub-jected to plane parallel deformation1,2 and undoubtedly he has applied the method to cold-rolled mild steel, but the authors have not found these data published. Kurdjumow and Sachs3 have applied the method to the study of rolling and recrystallization textures in electrolytic iron; their results will be referred to later. The reason for this dearth of papers using the pole-figure method is obvious; a greater number of photograms and more analytical work (although this work is quite simple and straight-forward) are required to construct a pole figure than most investigators have felt worth while, despite the fact that no other method of which the authors are aware will satisfactorily depict the orientations of the crystal-lites in a polycrystalline aggregate. The second circumstance that led to the work reported in this paper was the appearance of a paper by Wayne A. Sisson4 on the same subject. In his valuable study of the factors influencing the development of pre-ferred orientations in cold-rolled mild steel, Sisson made one observation that required confirmation; that is, that at some stage of the rolling proc-ess the type of preferred orientation changed from the type that gives a photogram characterized as a "six-point" X-ray pattern to that known as a "four-point" pattern. A similar observation had been made by Tam-mann and Heinzel5, who studied the orientations developed in the rolling of steel by the specular reflection of light from the etched surface of rolled samples. These workers also found that the type of preferred orientation

Jan 1, 1936

By R. P. King

The two-phase distributed-parameter kinetic model for flotation has been wed as the basis for a digital simulation of flotation plants of arbitrary configuration. Ores that contain any number of minerals can be handled. The effects of incomplete liberation and particle-size distribution are specifically allowed for. The simulator allows the investigation of variations in throughput and in the slurry density of the feed, and of variations in stage volumes and aeration rates. It can handle cell behavior even under conditions of hindered flotation. The requirements for data preparation are completely documented so that the computer program is suitable for general-purpose use. The program is written in Fortran. The output from the simulator consists of the complete material flows in the plant, as well as the grade, recovery, and particle-size distribution in each stream.

Jan 1, 1976

By Frank C. Appleyard

Gypsum, the dihydrate form of calcium sulfate, has a history of usefulness to man dating back several thousand years, and a worldwide industry has been built on the mining and processing of this versatile industrial mineral. However, anhydrite, the other principal calcium sulfate mineral has very limited use, so much so that separate statistics for it are not always kept, but are usually included with those for gypsum. Although often found in close association, the two minerals have important chemical differences in that anhydrite is the anhydrous form of calcium sulfate (CaSO,) whereas gypsum is the dihydrate (CAS0;2H20). These two molecules of combined water result in significant differences in hardness, density, and solubility of the two minerals. However, of most importance is the difference in thermal properties wherein gypsum, upon the application of a modest amount of heat, can be converted to the hemihydrate of calcium sulfate (CaS0;Vi H,O) or plaster of paris, an intermediate product upon which is based over 90% of the value of all calcium sulfate end products. Anhydrite, on the other hand, is inert at these temperatures and its uses have been limited to only those few cases where calcium sulfate in the anhydrous form may have an advantage. The earliest known use of gypsum plaster dates back some 5000 years to the time of the Pharaohs of Egypt who had discovered that gypsum rock, when exposed to fire, broke down into a powder which when mixed with water would form a putty that could be "plastered" on a rough mud brick or stone wall to make a smooth finish. It was used down through the centuries in a limited way for ornamental purposes, but did not achieve wide acceptance because of its quick (25 to 30 min) setting or hardening time which made it difficult to use. The first real understanding of gypsum chemistry was developed in France about 1755, and the gradual growth of its present utilization dates from that time. In the United States, the first utilization of gypsum was to grind it to a fine material for use as a soil conditioner at about the time of the Revolutionary War, and the term "land plaster" for ground gypsum has remained in use. Another cementituous material-lime or calcium oxide-had become the usual plastering material, but by about 1870 a method for retarding the set of gypsum plaster was discovered and it has today almost completely replaced lime as a plastering material. In recent years, gypsum products sold in the United States have reached a total valuation of approximately $500 million per year as illustrated in [Table 1].

Jan 1, 1975

By L. R. Budrow, R. T. Mishler

The Lucky-Tiger mine is a silver-gold property, situated at El Tigre, in the northeastern part of Sonora, Mexico, at an elevation of 6000 ft. in the Sierra Madre Mountains. It is 30 miles by wagon road from the Esqueda station on the Nacozari railroad. Since its discovery in 1903, the mine has produced forty million ounces of silver. The ore has averaged 40 oz. silver and 0.25 oz. gold per ton. Copper, lead and zinc have been of minor importance, having averaged 0.4 per cent., 1.1 per cent., and 1.5 per cent., respectively. The richness of the ore, combined with its occurrence in narrow veins, required the use of the more expensive methods. of mining. Geology Wall Rock The wall rock is rhyolite and rhyolite tuff, both of Tertiary age. In rare instances, post-mineral andesite dikes have been intruded along the veins. In the upper part of the mine, the walls were fairly solid. On the lower levels, the walls are usually cither kaolinized and soft or silicified and fractured, both conditions requiring closely filled stopes or much timber. Veins The veins have been deposited along fracture planes in the volcanics. There are three principal veins, about 600 ft. apart, all striking nearly north-south and dipping steeply to the west. Table 1 records the approximate dimensions and assay of the veins. Although the average

Jan 1, 1925

By L. F. Elkins

In 1946 Littlefield, Gray and Godbold published a thorough geologic description of the West Edmond Hunton Lime reservoir, located in Central Oklahoma, and discussion of its early performance.l They stressed implications of the nature of the reservoir rock on performance to be expected with production both by natural means and by pressure maintenance with gas injection. The essence of their analysis was that presence of an extensive interconnected system of fractures and solution channels constituting about 10 percent of the total reservoir void space in otherwise very low permeability reservoir rock would result in severe channeling of naturally encroaching water or injected gas through the fractures with little or no benefit to ultimate recovery of oil. Considerations were in progress to unitize the reservoir for pressure maintenance by gas injection. Some other engineers involved in the project had considerably different opinions at the time regarding continuity of fractures and regarding effects of such fractures on performance. The field was unitized Oct. 1, 1947. Subsequently, pilot gas injection tests were conducted in four areas of the field; large scale waterflooding was conducted in two parts of the field in the Bois d'Arc or Upper Hunton; and pilot waterflooding was conducted in the Chimney Hill or Lower Hunton. Full scale water-flooding is now in progress in the Chimney Hill section where it is oil productive. The primary purpose of this paper is to divine some of the secrets of this reservoir through analysis of all aspects of its performance, with the hope that it will be of help to engineers and operators in developing and operating other low permeability fractured reservoirs. In part, this considers variance of actual performance from some widely used conventional reservoir engineering assumptions. For brevity, other aspects of unit operation and its benefits to the owners are not discussed. Oil and Gas in Place For unit participation, net pay in the Bois #Arc defined by the gross SP anomaly on electric logs totalled 2,100,000 acre-ft in the 30,000-acre reservoir. Development of West Edmond predated modem logging techniques that now would be used to determine "net" or "productive" pay. In Fig. 1 this log pick is compared with detailed core analysis and core descripfion by Littlefield et a1.l for one well identified as A on the index map in Fig. 2. Not all of the gross Bois #Arc section had oil staining, but all cores with measureable intergranular permeability were stained. (The committee selection of the Bois d'Arc SP interval also includes the Frisco section as identified from cores by Littlefield.) The Bois d'Arc is oil productive throughout the entire 600-ft monoclinal accumulation from the eastern upstructure erosional pinchout to the west-side oil-water contact. (See Littlefield et al.l and McGee and Jenkins for geologic detail.)

Jan 1, 1970

By Albert Sauveur

The following propositions and corollaries are intended to present, as concisely as possible, some of the evidences gathered while studying the microstructure of steel. Each proposition is accompanied by photo-micrographs showing the structure of illustrative samples. But it must be understood that the special instances thus chosen for illustration are by no means the only ones on the examination of which the propositions are based. On the contrary, they have been taken almost at random among a great many, in some instances more than a hundred, similar cases. Proposition I. A slow and undisturbed cooling from a temperature x or higher produces crystallization. Plate L, Plate II., Fig. 1, and Plate V., Figs. 1, 2, 3 and 4 show the crystalline structure of several pieces of steel. Plate I. reveals this structure in the center of a slowly-cooled Bessemer ingot, 1.5 feet from the top. Plate II., Pig. 1, is from a small 2-in, square testingot of the same heat, slowly cooled. Plate V., Figs. 1, 2, 3 and 4 show the structure of different parts of steel rails. The original photographs were all magnified 70 diameters, and have been reduced in engraving to 63, or to 55 diameters, as shown in the plates. Proposition 11. Undisturbed cooling from an initial temperature lower than x is not accompanied by crystallization. Plate III., Fig. 5, shows the structure of a piece of rail-steel forged from a white heat until it had fallen to dull-red. The structure is almost amorphous. Practically no crystallization has taken place during the subsequent cooling. Corollary.—Pieces of steel finished at a temperature lower than x do not take a crystalline structure.

Jan 1, 1894

By F. Osmond

When a metal (whether a simple substance, an alloy, or a compound) presents, in each of the smallest parts to which it can be redueed by mechanical division, a constant chemical composition, it is defined as chemically homogeneous. But chemical hombgeneity by no means necessitates mechanical homogeneity. There are no perfectly amorphous metals. Crystalline forces, on the one hand, and tensions or compressions, on the other band, determined by icequalities of temperature in the mass during heating or cooling, give rise in every metal to the formation of geometric elements of structure. These elements may, moreover, assume perfect crystalline forms, with their planes of cleavage; or embryonic crystalline forms, segregated in the midst of. a paste of confused organization; or pseudo-crystalline forms of expansion and contraction, like those produced in the drying of gelatinous precipitates or (most frequently) these different forms associated. 111 either case the adhesions between two adjoining structural elements, respectively homogeneous, may be very different from the interior cohesion of each of these elements. The mechanical properties of this complex aggregate cannot be simple, and, when it is submitted to strains sufficient to produce deformation, the results may be very different according to the type of structure or the manner in which it is affected by the strains. It may be fairly said that a metal does not present a single resistance to tension, or a single resistance to compression, etc., but in fact, at least theoretically, as many resistances to tension, compression, etc., as it may possess coexistent features of structure; only, in any single test, it is the weakest of the resistances involved which makes itself evident. For further explanation, let us imagine a cylinder A B (Fig. I), formed of two similar halves A and B, placed together upon their common base x y. Such a system evidently presents no resistance to axial tension, while it would resist axial compression like a single

Jan 1, 1894

By L. F. Mondolfo

An investigation of the relationship between properties of the elements and type of binary diagram formed was conducted. It was found that, for each type of equilibrium diagram, the factors for the size, valence, electronegativity, period, melting point, entropies of fusion, and sublimation calculated for each pair of elements cover a range of values. However, these factors show sufficient relationship to the equilibrium diagram so that the correlation of several of them can be used to predict the type of diagram formed, or at least limit the choice to only a few types. ThE goal of the metallurgist concerned with alloy development has always been to find a method that predicts the properties that can be obtained when a certain metal is added to another one. In most cases a qualitative predictiton of properties can be made if the equilibrium diagram is known. However, this means that for new metals the alloy development has to start with the experimental determination of the equilibrium diagrams. Because this determination is at least as complicated and time-consuming as the determination of the properties themselves, most alloy development has taken place by trial and error, and the study of the equilibrium diagrams has followed rather than preceded the creation of new alloys. Alloy structures and properties depend on the interaction between electrons and a complete knowledge of these interactions would permit prediction of structure and properties of alloys. Unfortunately direct measurement of these interactions is extremely difficult and somewhat doubtful and only properties that depend on them can be measured easily and with certainty. Study of the relationship between properties of the elements and equilibrium diagrams is not new. Besides the well known Hume-Rothery rule of the necessity of an atomic diameter fit within 15 pct for extensive miscibility in the solid, and the wide knowledge of the effect of such factors as size, electronegativity, electron-atom ratio on solid state features,"' work relating to liquid state and liquid-solid reactions can be found in the literature. Of particular interest is the work by Axon,3 who investigated the effect of size and melting point on a selected number of eutectic and monotectic dia-

Jan 1, 1962

By M. E. Fine

IN the apparatus for measuring internal friction shown in fig. 1, a modification of that described by Kê,1,2 the parasitic energy loss or background is equivalent to a Q-1 of approximately 4x10-5. This low value of background was obtained by using a jeweler's collet of appropriate size for the upper support, eliminating lateral motion without immersing the bob in oil, and designing the bob to reduce air resistance. The pendulum is supported on the frame through a snug fitting, sliding rotary joint (fig. I-B). A slight twist of the top imparts essentially pure torsional motion to the pendulum. No evidence of energy loss in the sliding joint has been observed. In the bob (E) steel balls are used in the torsion arm, and the bottom is filled with lead giving a total weight of 94 g. A lighter bob may be used for small diameter specimens. Another bob was a solid disc with provision for adding discs to change the frequency. The oscillating image of the filament is recorded on a revolving drum camera (fig. 1-3) driven by a synchronous motor. This allows use of frequencies higher than can be measured visually on a glass scale. Samples varying in diameter from 0.020 to 0.075 in. have been measured, the frequencies have ranged from 1 to 12 cps, and the maximum strain varied from 0.5 to 10x10-5. With appropriate modification the sample may be placed in a thermostat. The apparatus may also be used to measure the shear modulus. In the examples of measurement given in table I the internal friction of Permendur and the 46.8 Ni-Fe alloy are due, for the most part, to magneto-mechanical hysteresis8 (elastic hysteresis accompanying stress-induced magnetostriction) which depends on strain amplitude and increases with annealing. The internal friction of most materials decreases with annealing. References IT. S. K6: Physics Review (1947) 71, 533. 2 T. S. Kê: Transactions AIME (1948) 176, 448; Metals Technology (June 1948) TP 23703. 3 R. Becker and W. Döring: Ferromagnetismus. 365 (1939). J. Springer.

Jan 1, 1951

By Henry D. Hibbard, Edward L. Ford

The process of making washed metal now followed is in principle that described by Holley before this Institute in 1879, as the Krupp washing process. Sir Lowthian Bell also experimented extensively in England during 1877 and 1878 on refining iron and joined his interest with Krupp, the process being often referred to as the Bell-Krupp process. The only plant in this country now operating this process is that of the Brier Hill Steel Co., Youngstown, Ohio. This process may be considered as the sole survivor of the numerous methods conceived for refining crude iron, when the removal of phosphorus from steel-making material was the great desideratum affecting large districts. The east coast of England and all northern Germany, the homes of Bell and Krupp, respectively, could at that time make steel only from imported ores. These processes were in use or in various stages of development 40 years ago and all except the Bell-Krupp received their quietus from the development of the basic steel processes, both pneumatic and open hearth. The aim of the early refining processes was, first, the removal of the silicon, which could be done on a sand bottom, and later, the removal of the phosphorus, requiring a bottom which would give or permit a basic slag. The incidental advantages of increased yield and small fuel consumption were not generally recognized or considered; the aim of the later operations was the saving of the difference in value between low and high phosphorus irons, as well as hastening the removal of the metalloids. The chemistry of the washing process follows in part that of the puddling process, and indeed washing might be considered as the first half of puddling, since all the non-ferrous elements of the crude iron, except the carbon, are eliminated and the iron is maintained molten until cast. In puddling, the iron loses its carbon as well, and because of that, its fusion point rises above the hearth temperature; it freezes into a pasty malleable form, and is worked at once by squeezer, hammer, or rolls. Since Holley's paper, important improvements have been made from time to time in both plants and methods for washing iron, and the

Jan 1, 1916