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By Frank C. Appleyard

The two calcium sulfate minerals-gypsum and anhydrite-occur in many parts of the world, and gypsum has long been of economic importance in the family of industrial minerals. Gypsum, the dihydrate form of calcium sulfate (CaS042H20) and anhydrite, the anhydrous form (CaSO4) are frequently found in close association, and it is seldom that a calcium sulfate deposit will consist exclusively of one mineral or the other. Although known gypsum deposits are extensive, anhydrite makes up the largest part of total calcium sulfate reserves. However, it has very minor economic use, and most of the following discussion will be devoted to gypsum. Calcium sulfate is one of the principal con- stituents of evaporite deposits, and when pure, has the following composition: [ ] Deposits of pure gypsum or of pure anhydrite which are large enough to be considered commercial have never been found because of both the metastable relationship between the two minerals, and the presence of impurities such as calcium or magnesium carbonates, chlorides, other sulfate minerals, clay minerals, or silica. As a result most mine production of gypsum will range between 85 and 95% pure. Often it is used as mined, although in certain cases, one or more forms of mineral beneficiation are employed to upgrade the product.

Jan 1, 1975

By K. M. Goldman, Lo-Ching Chang

The kinetics and mechanism of transfer of a constituent across a slag-metal interface are fundamentally important because many metallurgical processes involve the existence of a slag phase and a metal phase. Industrial processes seldom proceed to equilibrium, and information of the rates and modes of reactions are therefore often of greater practical importance than equilibrium data. A study of the kinetics of sulphur transfer across a slag-metal interface under reducing conditions will contribute a great deal toward a better understanding of desulphurization in the blast furnace process. The general principles existing in the transfer of a constituent, such as sulphur, across a slag-metal interface can be extended to similar transfer phenomena in other metallurgical processes. The present paper will demonstrate how such studies will lead to fruitful results from both the practical and theoretical standpoints. EXPERIMENTAL METHOD The apparatus used was, simple. A graphite crucible 15/8-in. id, a wall 1/8-in. thick, and a depth of 4 in., was packed in an outer fused silica tube with powdered magnesia. The crucible assembly was rotated at a speed of 235 rpm inside an in- duction coil. A charge of 250 g of Armco ingot iron was introduced into the graphite crucible and melted by induction heating. The melt was held at a desired temperature for 3-5 "'in., aftcr which 7.5 g of granular ferrous sulphide was added and the bath was held for another 3-5 mi11. A metal sample was then taken by means of a fused silica tube and a rubber suction bulb. Immediately after the metal sample was taken, 30 g of a prefused and crushed slag were introduced. The slag reached the ternperature of the furnace in 1 to 1 1/2 min. Slag

Jan 1, 1949

By Waldemar Lindgren

Fifteen years ago, in his presidential address before the Washington Academy of Sciences,' Alfred H. Brooks said: "Applied geology can only maintain its present high position by continuing the researches which advance the knowledge of basic principles. Future progress in applied geology depends on progress in pure geology. Early in 1927, Dr. David White, then chairman of the Division of Geology and Geography of the National Research Council, appointed a committee "On the Processes of Ore Deposition," which was the first recognition by the Council of this branch of applied geology. This committee will not be able to solve the many complex problems involved; it can only clear the way, survey the field, state the problems and encourage systematic research. This short paper aims to outline and to analyze the present status of this kind of geological research, to ascertain the quality of the work and to suggest lines that might profitably be followed. Increasing Demand for Geologists Economic geology, or the art of geology, could develop only after the principles of geology and mineralogy had been established. Before that time it was merely a collection of trade rules accompanied by more or less wild speculations. Thus we observe the beginnings of economic geology in the period 1770-1820. Soon afterwards, the State Surveys were established in this country, with the realization that the natural resources should be investigated and described. Geology was hardly yet equal to the task of scientific research in relationships and genesis, however, and there followed a period of discouragement and stagnation. In the meanwhile, pure geology had again registered progress, and, based on its principles and also on the rapid mining development in the Cordilleran region, the present phase of the study of ore deposits began to take form. Raphael Pumpelly, S. F. Emmons and G. F. Becker were among the pioneers in this movement. The United States Geological Survey was organized. Ore deposits were scientifically described and studied along lines of structure and mineralogy; theories of genesis were advanced, not always permanent but based on sound induction.

Jan 1, 1928

By R. J. Schilthuis, T. V. Moore

In a previous paper,' the results of some experimental work on the measurement of slippage in the flow of oil and gas mixtures through vertical pipes were presented. The data obtained were correlated and equations were deduced from which the performance of the experimental gas-lift could be predicted with reasonable accuracy. However, attempts to apply the equations to the calculation of pressure drops in actual flowing wells yielded erroneous results. At the time the results of the experimental work were published, no satisfactory explanation could be offered for the failure of the empirical equations to express properly the performance of wells. However, recent work has led to the development of a new hypothesis which presupposes certain conditions affecting the flow of oil and gas in wells. When the proposed equations are corrected to allow for these conditions, an agreement between the observed and calculated performance of the actual wells is obtained which in most cases is quite satisfactory, although it is subject to certain limitations. In this paper, the method of calculating the pressure drop in actual wells is considered, and the application of the method to the design of tubing is discussed. (For nomenclature used in this discussion, see Table 1.) Factors Affecting Slippage and Efficiency At the outset, a few of the principle factors affecting slippage and efficiency in the gas-lift discussed in the previous paper will be reviewed. In the flow of the mixture of oil and gas in a vertical pipe, slippage is the phenomenon of gas moving upward with a. linear velocity greater than that of the oil. Under steady conditions, if given quantities of oil and gas enter the tubing per unit of time, the same quantities of oil and gas per unit time must, on the average, pass every section of the tubing; otherwise, there would be accumulation or depletion of the oil or gas at some sections, and the flow would be unsteady. Therefore, if the gas is to flow at a greater linear velocity than that of the liquid,

Jan 1, 1933

By John L. Schroder

INTRODUCTION-SYSTEM DESIGN The design of an underground mining operation requires the integration of transportation, ventilation, ground control, and mining methods to form a system which provides the highest possible degree of safety for mine personnel; the lowest cost per ton of product ; the most suitable quality of final product, considering its intended use; the maximum percent recovery of the reserve, consistent with cost and subsidence rights ; and the minimum disturbance to the environment. The selection of mining method is generally the controlling factor in overall mine design. Some important considerations in the choice of mining method are: 1) Depth of cover over the coal seam. 2) Strength and thickness of rock strata in the overburden. 3) Characteristics of the coal seam, including thickness, nature and location of impurities or irregularities, dip (or pitch), nature and direction of cleavage, hardness, and structural strength of the coal. 4) Nature and strength of the immediate roof (top) over the coal seam. 5) Nature and strength of the floor (bottom) under the coal seam. 6) Presence and amount of explosive gas (methane). 7) Quantity of water likely to be encountered in the mining operation. 8) Any previous or concurrent mining in seams above or below the coal seam to be worked. 9) Any restrictions on recovery required for subsidence control. Topographical and geological reports and maps of the area are usually available from state and federal geological surveys, and contain excellent general information to guide more detailed investigations. Exploratory drilling, and the plotting and analysis of the information thus obtained, are essential steps in any development program, and aid in the correlation and evaluation of information gained by other means. Other good sources of information are operating coal mines that may be in the same

Jan 1, 1981

Jan 1, 1926

By P. J. G. duToit

The continually growing shortage of skilled underground miners, the escalating costs of labor, supplies and equipment, and the indisputable example of "what can be done" by our friends in the space-travel field, seem to be catalysts that are accelerating improvements in underground mining technology. The search for an economic, automated continuous excavation method that would produce rock at the mining face in sizes suitable for automated transportation directly into the rod-, ball-, or autogenous grinding mills is continuing. New mining methods and techniques were devised and many improvements on old methods and techniques came forth at an increasing pace that reflected a widely spreading policy among mining men to shun the shackles of conservatism and to forge ahead and venture into newer ideas.

Jan 2, 1967

By Theodore Simons

The rapid and comparatively recent development of flotation has opened so fascinating a field for study and research that the older processes of gravity concentration no longer receive the attention they deserve. The early work of Munroel and Richards12 and the more recent contributions by Clevenger and Coe,3 Laist and Wiggin,4 Ammon,5 Bardwell,6 Crowfoot,' and Hayden8 (to mention only some which have appeared in our own Transactions) and by Schu1z,9 have furnished so much data that to offer something new seems a difficult task. It is still possible, however, to present known facts from a different point of view, and, with this in mind, the writer has undertaken to express basic principles of gravity concentration in terms of simple mathematics and mechanics; the conclusions thus reached will be found to correspond, in general, with those obtained by experimental methods. Rittinger, in his classic Aufbereitungskunde (1867)) reached analogous conclusions by way of intricate higher mathematics, for which reason his interesting investigations have remained a sealed book to most of us. The writer hopes that a more elementary treatment of the subject, based in part on Rittinger's metheds, may arouse new interest in the study of basic principles.

Jan 1, 1923

By Toshihisa Adachi, Shosei Serata, Shunsuke Sakurai

Many different methods of measuring the in-situ stress field have been developed in recent years. They are all based on the assumption of elasticity without allowing any viscoelastic deformation. By using the high resolution strain-measuring technique recently developed in the laboratory at Serata Geomechanics, many rocks were found to be viscoelastic. The viscoelasticity of rock media was found to be dependent upon the resolution of the strain measurement. The higher the resolution of the strain measurement, the greater number of rocks could be identified as viscoelastic. All rocks eventually exhibit viscoelastic deformation under high stresses relative to the strength of the material. Therefore, the conventional methods of elasticity become less reliable with increase of ground stress. In deep underground formations, even hard rocks become viscoelastic. At the same time, many ground formations near the surface are actually viscoelastic. A new method was developed in the laboratory to determine the in-situ stress field in viscoelastic rock media. Rocks in general exhibit a small amount of viscoelastic creep whenever mean stress and octahedral shearing stress are changed substantially from their initial states. Such changes take place around a borehole immediately following the drilling although they are short-lived. We developed a viscoelastic method of determining the in-situ stress field by relating the time-dependent behavior of the borehole with the tensor properties and stress field of the underground. In developing the viscoelastic relation, only isotropic and homogeneous

Jan 1, 1970

By Wallace E. Pratt

IRon-oRe deposits in the Philippine Islands became the subject of official record as early as 1664. Undoubtedly iron ore was known and recognized by the Filipinos long before the earliest Spanish records. It is even possible that the Filipino practice of smelting iron ore is, like the native copper smelting, older than the Spanish conquest of the islands. The first records have to do with the magnetite-hematite ores near the towns of Santa Inez and Bosoboso in Rizal Province, from 15 to 20 miles east of Manila. The magnetite-hematite ores of Bulacan were exploited in 1783. Similar ores near the town of Mambulao in Camarines Province yielded a number of specimens to be exhibited in Spain in 1834. With the exception, then, of the lateritic iron ores on the eastern coast of northern Surigao, the true nature of which was not recognized until 1914, the important iron-ore deposits of the Philippines had all been discovered before the islands came under the dominion of the United States. Indeed, in the Spanish documents relating to the history of iron mining are statements which, if their accuracy be not questioned, leave us in the Philippines today with much less iron ore than the Spaniards found. To quote, for example, a report submitted to the Superior Government in Spain in 1835 by one of its emissaries, Don Lorenzo Calvo: "The Philippine Islands, most excellent Sir, possess iron and exhibit it in nearly every known mineralogical combination, and in such abundance that the cordillera of the island of Luzon, from Montufar Point in San Bernardino Straits to Cape Bojeador, is composed of no other mineral than iron, its ranges, of the third order, being in content and structure totally iron of the best quality, the more valuable in that its combinations are such as to facilitate its fusion and to render its redaction to metal simple." Today, however, it is recognized that the iron-ore deposits in the Eastern Cordillera of Luzon constitute, not a continuous belt, but a series of widely separated deposits, including a half dozen orebodies within a distance of 10 miles in Bulacan Province, a single outcrop at Santa Inez, Rizal Province, farther south, and three deposits around

Jan 1, 1916

Jan 1, 1907

By A. H. Jones

The Belmont mill at Tonopah, Nev., was designed and constructed by the Belmont staff. Ground was broken in August, 1911, and milling operation started July 25, 1912. The metallurgical flow sheet, and the machinery adapted 60 carrying out operations in accordance with this plan, were decided upon from experience gained in the treatment of Belmorlt mine ores at the old Belmont mill at Millers, Nev. The detail drawings were madc by the engineering staff of the Tonopah-Belmont Development Co., under the supervision of Otto Wartenweiler, who also had direct charge of the construction, consulting with the General Superintendent of the company, Frederick Bradshaw, and the writer.

Jan 1, 1916

An educated man is distinguished neither by his clothes nor by his knowledge; he is remarkable not for the things he says, but for the way he says them. You cannot even stand with him under an archway in the rain without finding him out. He may talk only of the weather. His words and his phrases alike my be simple. What distinguishes him is the arrangement of his words; however desultory his talk, it will be methodical; he has habituated himself to foreseeing the part to be played by each word he uses and the place to be taken by each sentence he utters. On the other hand, the uneducated man, though shrewd and well-informed, will relate facts and events as they recur to him, generally in disorder; in his effort to recollect and in his attempt to rectify forgetfulness he will pause irregularly, filling the intervals with meaningless phrases, such as "and then", "and so", or "said he to me", "said I to him"; and even the continuous parts of his story will be told confusedly-because he has not learned the proper use of words.* My own experience as an editor of technical manuscripts has taught me that the misuse of 'that' and 'which' is a fruitful cause of obscurity and confusion. The relative pronouns have distinct functions, and no writer can express himself clearly until he has learned to discriminate between these functions. For example : The engineers who refused to submit were discharged. The engineers, who refused to submit, were discharged. The engineers that refused to submit were discharged.

Jan 1, 1931

By Raymond M. Howe

Some time ago, a prominent engineer asked a representative of the firebrick industry to prepare a comprehensive paper on blast-furnace refractories. It was to have been the purpose of this paper to gather practical experiences from widely different sources, in the hope of determining what kind or kinds of firebrick were best adapted for certain uses. This engineer sent questionnaires to the large consumers of blast-furrace linings and stovebrick and received very detailed replies as to their experiences. These replies are conflicting, but, having been turned over to the writer, form the basis of this attempt to meet the request. Because of the impossibility of making final recommendations at this time, a few of the more interesting and commonly known methods of studying refractories are also discussed, as well as the more recent developments in this field. The first reply to the questionnaire stated that good service was being secured from the linings. This satisfactory condition was attributed to the use of a very good distributor. The writer believed that manufacturers try to and do produce a good product and that the proper handling of equipment is of the utmost importance, if good results are to be secured. The type of bricks used was not mentioned. The second reply stated that good life was secured from the furnace linings, but that the writer had had soft-fired stovebrick crumble and, for that reason, preferred a hard-fired product for use in this position. The type of bricks used was not mentioned. The third reply stated that firebrick had crumbled from the mantle up; the cause was not known. The fourth reply stated that the stove linings were satisfactory. Hand-made furnace linings failed after.4 years' service so a steam-pressed lining- was installed which was still good after 4 years of service. Consequently, a second steam-pressed lining was installed but this disintegrated at the top after the furnace had been in blast 7 months. The firebrick manufacturer attributed this failure to the expansion of iron blocks that had been installed at the stock line to prevent erosion. The fifth reply stated that the present "hard-burned" hand-made furnace lining had worn away very uniformly to the depth of only 5 in.

Jan 1, 1920

By B. Ladanyi

The problem of rock behavior under concentrated loadings has been the subject of a number of studies in the past and has been receiving increasing attention by rock mechanics investigators in recent years. Its application covers various fields, but main interest in its solution has arisen in connection with the problems of drilling, bearing capacity, and rock testing. These widely different purposes and fields of interest probably have been one of the reasons why, in spite of the large amount of published experimental data and several theoretical studies, there are still many points which need further clarification. Another reason for this situation undoubtedly is due to the fact that the rock behavior in indentation is complicated by a great number of influencing factors. Experimental evidence shows that, depending on the rock type (mechanical properties, porosity), environment (ambient effective pressure, pore fluid, temperature), and the type of loading (indenter shape, initial embedment, load level, loading rate), the rock response to indentation may vary within very large limits. The widely different rock behavior has made it impossible up to now to treat the problem with a consistent single mathematical theory, but has required instead a series of simplified models covering only certain most important events in the failure sequence. As far as the theory of rock indentation is concerned, this chapter does not add much new information. Its main purpose is, however, to state the indentation problem in a general manner and to indicate which points need to be studied in more detail before its definite solution is attempted. Also, since excellent reviews of the state-of-art of rock indentation in drilling have recently been given,1-4 this will not be repeated here, and only references pertinent to the points of the problem under study will be quoted. The theoretical part of this study attempts to give a quantitative evalu-

Jan 1, 1972

By Harry A. Lipsitt, Attwell M. Adair

A number of papers have appeared in the past several years concerning the nature of the fatigue limit. The hypotheses presented in those papers fall into three groups. Some authors attribute the fatigue limit to the distribution of interstitials prior to testing (static group). Others consider the fatigue limit to be due to dislocation-interstitial reactions during testing (dynamic group). Still other propose that the fatigue limit results from a characteristic peculiar to the iron (bee) lattice (inherent group). This communication is an attempt to digest the salient features of each of the hypotheses, discuss them, and present some constructive criticism. It is shown that each of the extant ideas has some merit, and that each of the mechanisms thus far proposed is necessary, but individually insufficient, to provide the desired level of understanding of the fatigue-limit behavior of metals. Static Group. The data of Oates and wilson1 on finegrained (=0.022 mm diam) low-carbon steel indicate that the fatigue limit exists in the absence of sufficient plastic deformation for any dynamic strain-aging mechanism to be operative. Specimens tested just below the fatigue limit showed yield-point behavior typical for unstrained material when removed from the fatigue machine and tested in tension. These results led them to the conclusion that initial dislocation locking controls the fatigue limit in this material, which has a yield stress higher than the fatigue-limit stress. Prestraining this material just prior to fatigue testing would be expected to lower the fatigue-limit stress; this they observed experimentally. Yoshikawa and sugeno2 are of the opinion that the sharp fatigue limit in fine-grained iron is caused by

Jan 1, 1967

By Fred B. Brost

In 1976, a decision was made to install a conveying system to transport ore 10.3 km (6.4 miles) from the new Eisenhower mine to Twin Buttes. The system, supplied and installed by Cable Belt Ltd., of England, represents a radical departure from conventional conveyor systems. The driving tension is applied through two endless wire ropes while the belt acts only as the carrying medium. Features of the system are a single 2240-kW (3000-hp) drive and a 60° angle bend. Construction was completed in two years and full production was attained alter several mouths operation.

Jan 12, 1979

By J. E. Jopling, J. R. Chenneour, E. L. Derby, S. R. Elliott

The Marquette range, on which are situated the iron mines of Mar-quette County, together with a few in Baraga County, Mich., extends from a point 10 miles southwest of Marquette westward for 30 miles. The tracts are usually a multiple of the standard 40-acre parcel, which is the smallest government subdivision of a square mile or section. About half of the mines are held in fee, these being owned by the older mining companies. Some of them date back to about 1880, and a few are as early as 1850. During the past 40 years most of the mines opened have been on leased lands, the royalty being either for a stated amount per ton or a percentage of the selling price of the ore at the lower lake ports, or the selling price on board of cars at the mine. The first merchantable body of ore discovered in the Lake Superior district was found, in 1845, at what is known as the Jackson mine, near Negaunee. This ore was hard hematite. After unprofitable attempts had been made, in 1848, to smelt it in forges, shipments were begun to lower lake ports, which increased rapidly upon the completion of the locks at Sault Ste. Marie, in 1855, and the railroad from the mines to Marquette, in 1857. Beginning with the Pioneer, in 1858, a number of small charcoal furnaces were built to smelt a part of the product. At various points in the upper and lower peninsulas, large charcoal furnaces are still making iron from the ores of the Marquette range. In connection with these furnaces are byproduct plants. As the deposits were opened up, soft ore was encountered, but for a few years this was disregaided, as only the hard ore was used. Underground mining was begun about 1880 and during the next few years the open-pit mines producing high-grade ore were exhausted. The first mines in the district were owned by the Jackson, Cleveland, Lake Superior, Lake Angeline, Champion, Iron Cliffs, Humboldt, Republic, and Michigamme companies. Many of these companies have been merged in the holdings of The Cleveland-Cliffs Iron Co., which controls most of the tonnage of the district.

Jan 1, 1925

By Henry Howe

W. E. RUDER, Schenectady, N. Y.-In 1913 I presented a paper before this society on Grain Growth, and at that time it seemed to me that the only explanation for grain growth was that of critical strain. I do not think I published the photographs at the time, but I made some experiments on the effect of stretching sheets of metal. This allowed for fairly accurate determinations of the amount of cold deformation, At the time I worked-with silicon steel because one could see the change in grain growth with the naked eye. I stretched about 10-samples from 0.5 per cent. to 10 per cent., and, after heating to 1,050° C., I found that the maximum grain growth occurred at about 2 ½ per cent. cold deformation. This I designated "the critical strain" for maximum grain growth. About a year ago I talked with Prof. Jeffries, who explained to me his ideas of grain growth. It occurred to me that it would be a very easy thing to check the strain hypothesis against the strain and temperature hypothesis, if we took a certain number of these strips, strained exactly alike and heated to different temperatures; in that case the maximum grain growth ought to appear at a different percentage of deformation for each temperature. These experiments showed that there was, as Mr. Jeffries shows in his present paper, a decrease in germinative temperature with increased cold deformation. The samples were stretched from ½ to 8 per cent. and heated for 10 hr. in hydrogen. Samples were introduced into a furnace previously heated to temperature. A maximum grain growth was obtained at 5 per cent. deformation, when heated to 750° C.; at 2 ½ per cent. when heated to 800' C.; at 1 1/4 per cent., if heated at 950°C.; and at 5/8 per cent.. when heated at 1,100° C. This shows very clearly that the germinative temperature decreases with the increase in cold deformation. The growth was very much more marked, however, at the high temperature, i.e., the grain grew more rapidly and attained a much larger size than at lower temperature. In considering the photographs (Fig. A) those along the lateral edges should be ignored because.

Jan 4, 1917

By Joseph E. Pogue

In 1920, 531 million barrels of crude petroleum were coi~sumed in the United States. As imposing as this figure is, the fact that the domestic consumption of crude petroleum has increased at an average rate of 10 per cent. a year for the past decade is more striking. Will this rate of increase in demand continue? If so, the year 1930 will call for 1260 million barrels of petroleum—a staggering volume. On the other hand, may we expect the demand for petroleum to grow as rapidly as it did when the automotive industry was having its most phenomenal expansion? If not, to what extent will the growth of oil requirements decrease? When and to what degree will the petroleum industry become affected by the economic law of diminishing returns? Obviously, this matter requires careful analysis, especially as both national and industrial planning must be predicated upon present estimates of the requirements of the future. The purpose of this paper, accordingly, is to project, as closely as present limitations of knowledge permit, the course of the demand for petroleum in the United States over the next ten years. At first, the problem of estimating the future of a demand as complex as that for petroleum might appear insoluble. Fortunately, hon~ever, therc are several scientific methods of approaching the problem, centering around a study of rates of industrial growth, which lend considerable hope that the requirements of the immediate future in this field may be approximated with sufficient closeness to have practical value as a basis of action. Growth oF Petroleum Demand The demand for crude petroleum is the resultant of the demands for the products made jointly from this substance—gasoline, kerosene, gas and fuel oil, and lubricating oils. The demands for these have grown at

Jan 1, 1923