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By Matthew J. Hrebar

SINCE the first installation in 1936, the use of rubber-tired equipment for secondary mine haulage has increased rapidly. From August 1936 to January 1944, approximately 750 rubber-tired units were placed in operation. Of these, 650 units were installed after January 1940. During the year 1941, it per cent of the mobile loaded bituminous tonnage was hauled by rubber-tired equipment. This percentage increased to about 20 per cent during 1943. The first rubber-tired units were battery-powered tractor-trailer types. In the year 1938 the battery-powered self-contained car was introduced. In 1939, the cable-powered self-contained car made its appearance. These self-contained units are our modern "shuttle cars." By the end of 1941, approximately 15 per cent of the shuttle cars in operation were cable-powered. Installations made during 1942 and 1943 increased the proportion of cable-powered cars to about 40 per cent of the total number of shuttle cars in use. There is a marked trend toward cable-powered cars, although one need not make many trips to mines where both types are used to discover that opinions are highly controversial as to the relative advantages and field of use of each type. It is natural for mining engineers in the coal-mining industry to have diversified opinions regarding the use and application of coal-mining machinery. Coal mining is not a standardized industry; natural conditions vary from mine to mine. However, it is surprising how many operations in scattered fields arrive at the same conclusions and adopt similar methods. This happens not so much through cooperation and exchange of ideas as through hard, costly experimentation, involving months of low production and relatively high costs. What then, are the reasons for increased use of cable cars? Could it be that present scarcity of materials is forcing their use? True, battery cars require considerably more auxiliary equipment, but during 1942 it was no more difficult to obtain than shuttle-car cable. Furthermore, the trend toward cable cars started before curtailments on mining equipment took effect. Undoubtedly, cable-reel shuttle cars were introduced to produce coal at a lower cost by simplifying trackless mining through the elimination of auxiliary equipment, and by reducing the first cost on equipment. The theory of cable-powered shuttle cars is well based, as can be proved by successful operations. Many operators have weighed the advantages and disadvantages of each type carefully before choosing the type most suitable to their operation. Others have taken much for granted and accepted one or the other without much thought. At many small operations, low first cost is apt to be the deciding factor. One large company, with considerable experience in the use of battery locomotives, preferred to use cable cars even though it was neces¬sary to reduce the section voltage from

Jan 1, 1944

By A. A. Collins

OF widespread interest to all lead metallurgists is a dross smelting process that will consistently give mattes and speiss of low lead and high copper contents. It is a problem that has intrigued operators through the years. In the past few years, with increased amounts of copper and overcrowded metallurgical furnaces, it has been almost imperative to evolve some method. Experience at El Paso has shown that high copper-to-lead ratios can be consistently attained by use of the new soda process. † Older Methods Three older methods, i.e., 1. Dross plus siliceous ore and limestone. 2. Dross plus one fourth blast-furnace speiss and siliceous ore, 3. Dross plus sulphides and siliceous ore and scrap iron, do not give consistent results and the products are higher in lead and lower in copper than those produced with the soda process. Any radical changes in the blast-furnace drosses will throw any of these older methods into a tailspin. For almost ten years, El Paso used the third method, with varying results. It was noted that as the arsenic and anti- mony contents of the dross increased, the speiss and matte steadily increased in lead and decreased in copper. A dross containing four parts of copper to one part of arsenic was considered to be ideal. At times this balance of copper to arsenic was almost impossible to obtain, especially when handling copper Cottrell dusts, which vary so greatly in copper and arsenic. Custom smelters like El Paso, handling a great variety of dusts, concentrates and ores, are apt to have anywhere from I to 15 pct copper on charge, with a variable in arsenic of from 0.5 to 2 pct. With such conditions, and drosses varying from 12 to 40 pct copper, an operator using the older dross reverberatory practices would find it just about impossible to control the reverberatory operations and to produce a good product low in lead and high in copper. These conditions prevailed at El Paso from the year 1940 to the present. In May 1942 it was decided to experiment with the soda process. The Soda Process After considerable work the soda method was finally evolved to the present state. It has never failed to produce a good product even under the most adverse conditions. It might be well to remember that many men of thought in the smelting industry have at one time or other sugge~ted the removal of all copper, arsenic and antimony from the lead blast-furnace charge as an aid to better metallurgy.

Jan 1, 1949

By George D. Roberts

INTRODUCTION CIVIL engineers are primarily interested in maximum core recovery. This is even more important in foundation work than in mining investigations where sludge samples are of some value. The soft materials, such as clay, gouge, or partially decomposed seams that are most readily ground up or washed away, are the materials that usually have the greatest influence on foundation and leakage conditions. Undisturbed samples of such materials should be obtained for detailed geological examination and laboratory tests. Therefore the attainable goal of sampling in connection with foundation investigations is the recovery of 99.9 pct of undisturbed core. FACTORS CAUSING CORE LOSSES The principal factors contributing to core losses are: (I) coring badly fractured or very soft material; (2) use of improperly designed coring equipment, including the use of bits of too small a diameter; (3) lack of the proper training and attitude on the part of the drillers and pertinent technical information on the part of the supervising personnel. Little can be done about the character of the material being cored but the other two factors contributing to unsatisfactory performance can be corrected. Although the title of this paper is the improvement and standardization of core barrels, it is believed that the drillers' shortcomings and the lack of pertinent technical literature are more detrimental to good core recovery than either of the other factors. USES FOR LARGE DIAMETER CORE BARRELS It is well known that the use of larger diameter bits and core barrels generally produce better cores, particularly when sampling soft or broken material. The use of larger and larger bit diameters and the insistence on better core recovery is well demonstrated by the change in practices of the various districts of the Corps of Engineers. Today NX core is the smallest diameter commonly permitted for investigational work and the more active districts are using coring bits up to 6 in. in diameter, as well as 36 and 40-in. calyx rigs. The latter size has proved to be just as economical because it provides more room for core removal and cleanup operations. The use of large diameter cores to replace the driving and jacking methods of obtaining soil samples is also increasing. The 5 7/8-in. Denison sampler, developed by H. L. Johnson to obtain samples from soft formations, is one example. The principal uses for bits larger than NX are: sampling soils and semi-consolidated rock; sampling decomposed rock or rock with soft seams; sampling concrete; obtaining samples for laboratory tests; drilling drainage holes, and other miscellaneous work. CORE DRILLING PRACTICES OF SEVERAL ENGINEER DISTRICTS Little Rock District The writer was employed in the Little Rock District from 1938 until 1942. Prior

Jan 1, 1947

By H. S. Rankin, E. C. Houston

OLIVINE is considered a valuable potential source of metallic magnesium in the chloride electrolytic process. Treatment of olivine with hydrochloric acid can be carried out under conditions that prevent the formation of gelatinous silicic acid, which would inhibit the reaction by forming a covering around the ore particles. It is our hypothesis that the formation of gelatinous silicic acid is avoided by the dehydrating action of the magnesium chloride, which takes up water to form a series of hydrates and leaves the silicic acid in granular condition. Leaching serves to separate the magnesium chloride from the silicic acid and unattacked ore, which can be treated with fresh acid in successive steps until extraction is essentially complete. The leach solution can be purified by the addition of caustic magnesia and the precipitated impurities removed by decantation or filtration. The resulting magnesium chloride contains: Fe, less than 0.001 per cent; Mn, 0.012 per cent; Ni, none. Chlorination[f] of olivine has two major defects: (1) a large part of the chlorine goes to form silicon and iron chlorides, (2) the anhydrous magnesium chloride is held by absorption in the finely divided silica. SUPPLY It is well known that olivine, a silicate of magnesium and iron, is present in large amounts in several localities in the United States. The largest deposits occur in the southeast and on the Pacific Coast.1 The southeastern deposits were surveyed by Lewis2 in 1896 and by Hunter3 in the period 1933-1940. It is estimated that high-grade olivine, conveniently located with regard to transportation and power, is present in excess of 230 million tons above local drainage level in western North Carolina and north Georgia. PREVIOUS TECHNICAL WORK In the past few years, olivine has attracted considerable attention in the refractory field. In the chemical processing industry, however, it has long been thought axiomatic that the cost of processing silicates is an economic barrier to their utilization, especially where more reactive minerals, such as carbonates, oxides or salts, are available. This attitude is not entirely justified in connection with olivine. Unlike most silicates, olivine is readily attacked by acids, chlorine and other reagents without resorting to fusion to break down the silicate structure. Olivine has been suggested as a raw material for making epsom salt by roasting with pyrites.4 Other processes include acid treatment5 and digestion with calcium chloride.6 Recently a small plant was built near Webster, N. C., for making epsom salt from olivine by treatment with sulphuric acid. This plant is now in commercial operation, producing approximately two tons per day. Olivine is also receiving attention from the fertilizer industry as an inexpensive source of soluble magnesium.

Jan 1, 1942

By W. Julian Patron

TREATMENT of the breaker wash-water discharges to remove the suspended particles of finely divided material is usually most efficiently and economically accomplished in settling or thickening tanks. The purpose of these tanks is to separate the excess water from the solids by sedimentation whereby the solid particles suspended in the water are thickened by the force of gravity. The water overflowing these tanks is either reused for coal cleaning or discharged directly to the streams. The settled solids, which are in a relatively concentrated condition, forming a sludge or thick pulp, can be disposed of by pumping to a storage dam, by slushing into mine workings, by processing for recovery of coal, or filtering by vacuum or centrifugal means and discharging with the breaker refuse. The scope of this paper will be limited to the discussion of settling and thickening equipment, the factors that influence the settlement of solids, and a brief description of tests that can be made to determine the size of settling facilities required for any particular condition. The practical application of sedimentation to the treatment of coal falls into two groups, one of classification or hydro- separation, and the other of clarification and thickening. Classification may be employed to prepare a relatively low- grade fuel, which can be used as is or can be further processed separately. Clarification and thickening is employed where the primary objective is to recover a relatively dewatered solid and return a satisfactorily clear water to breaker or streams. When a stream of water flows across a tank, the time required for a particle to travel from the feed inlet to the overflow must be a little greater than that required for the finest particles or flocs in the feed to settle out of the stream. OPERATION AND TYPES OF SETTLING EQUIPMENT Theoretically, the liquid in a settling tank should rise at a more or less constant rate throughout the area of the tank Under these conditions the rising velocity of the water must be less than the settling rate of the finest particles if clarification is to be obtained. When classification of particles is to be made in the tank, the overflow velocity must be greater than the settling velocity of the particles that are to be removed with the tank overflow. The performance of a settling tank, then, depends on the settling rate of the solids and the current velocities in the tank. The oldest types of sedimentation employ intermittent types of settling tanks of any convenient shape. Means are provided for filling the tank with pulp and allowing it to settle until quiet, for moving the clean liquor and for removing the thickened sludge. The operation is necessarily intermittent but a sufficient number of tanks is employed so that a continuous flow of clear water is maintained. Continuous methods for the sedimentation of slurries were developed in the metallurgical industry. Cones from which settled solids were discharged by gravity

Jan 1, 1946

By William Lodding

Muscovite was the crystalline material used in the experiments discussed in this paper. It was both wet and dry ground for various periods of time. The effects (physical and chemical changes) produced in grinding are analyzed by use of thermal analysis. That grinding may change a crystalline material both in a physical and in a chemical sense has been shown by a number of authors in recent years. Mackenziel and Bartha2 reported the effects of careful grinding on muscovite, quartz, gypsum, dolomite, etc. Increase in specific surface produced by grinding implies increase in total energy of a system. Newly produced surfaces are chemically more reactive; dislocations may be introduced during grinding and, on the other hand, existing strain may be released by the same process, as shown by Holt, et a1.3 All these changes are easily detected by thermal analysis, but it is not easy to separate the multiplicity of effects registered and to arrive at quantitative interpretations. This paper is an attempt to analyze, by the use of thermal analysis, some effects produced in grinding. In differential thermal analysis (DTA) one measures the sum of all thermal changes occurring in a substance during heating or cooling; e.g., chemical changes, such as decompositions, synthesis, oxidation, reduction, etc., and physical changes such as phase transformations, changes in specific surface and thermal conductivity, strain release, etc. By thermogravimetric analysis (TGA), on the other hand, only chemical changes involving weight loss or gain are recorded. Similarly, gas evolution analysis (GEA) will register only reactions involving gas evolution. By performing two or all three of these methods of thermal analysis simultaneously and on the same specimen, one can separate the different effects registered and, by difference, evaluate their magnitude. The results of TGA are usually plotted as percent weight against furnace temp. When one differentiates weight against furnace temp, a rate of weight-change curve is obtained, and the resulting differential thermogravimetric (DTG) plots are similar in appearance to DTA thermograms for the same reaction. While the integrated area under a DTA peak represents enthalpy and can be expressed in calories per gram the area under the corresponding DTG peak represents the weight change which took place during a reaction. The similarity of DTA and DTG thermograms obtained from one material can be seen in Figs. 1 and 2. EXPERIMENTAL A Fisher mortar grinder and a porcelain mill with burundum balls were used for both dry and wet grinding. Muscovite was first carefully hand-filed and screened on 20 and 100 mesh. The middle fraction was considered essentially unaltered muscovite.

Jan 1, 1968

By Harry W. Antes

The density changes that occurred on annealing cold-worked poly crystalline molybdenum, over the temperature range of 870" to 1630 SC, were determined. Increases in density were observed for recovery and the beginning of recrystallization. An initial decrease in density was observed during re-crystallization. A second decrease in density was observed after recrystallization was completed, as the microstructure changed from columnar grains to equiaxed gvains Both decreases in density were associated with an increase in gain boundary area to volume ratio. The second decrease in density was observed in the annealing range that immediately precedes secondary recrystallization as reported in the literature VARIOUS techniques have been used to identify the recovery, recrystallization, and grain growth processes that occur when cold-worked metals are annealed. As early as 1928 work was conducted that indicated measurable density changes occur when cold-worked single crystals of brass are annealed.' More recently, work by Murphy exhibited a corre- lation of density with microstructural changes observed on annealing cold-worked polycrystalline a brass.2 Other investigators have performed similar work on a brass and copper.324 In reviewing the literature, it was apparent that density work had been limited to fcc materials. Therefore, it was the purpose of this investigation to determine the density changes that accompany annealing the cold-worked bcc material, molybdenum. Two degrees of cold work, 30 and 90 pct reduction of cross-sectional area by rolling, were selected for this study. EXPERIMENTAL PROCEDURE High-purity vacuum arc-cast molybdenum was used in this study, the principal impurity being carbon in the amount of 80 ppm. The final rolling reductions were made at 1200°C in grooved rolls to provide 5/8-in.-diam rod. Density specimens 0.500 in. diam by 1.5 in. long were machined from the bar stock. The specimens were ground to the final dimensions to provide a smooth surface. Density measurements were made using a hydrostatic technique similar to that used by ~urphy.' This type of equipment permitted weighing in liquid immediately after the air weighing. During each weighing the temperature of the air and liquid was controlled to within 0.0l°C. This was accomplished by sealing the analytical balance in an air-tight brass chamber and surrounding it by an insulated wooden case. Preheated air was circulated in the air space between the brass chamber and wooden case by means of a blower. The temperature of the

Jan 1, 1964

By Sidney Powers, Alfred C. Lane

This paper aims to present the results of an investigation concerning gravitative differentiation in lava flows, based on a quantitative microscopic and chemical study of a Triassic basalt from Nova Scotia, and confirmed by data secured from a study of certain Keweenawan ophites. At Cape d'Or, Nova Scotia, near the head of the Bay of Bundy, marine erosion has exposed a series of Triassic basalt flows in which copper has been sought for a number of years. Studies of the thickest flow of the series with regard to volumetric composition, specific gravity, and grain have been made by the junior author, and measurements by students at Tufts College, together with confirmatory observations of the same nature on this and other flows by the senior writer, and chemical analyses made by the Division of Chemistry, Mines Branch, Ottawa,' all show differentiation in lava flows comparable to that in intrusive bodies. The work was made possible by the availability of the drill-cores, the property of Tufts College, and emphasizes the desirability of the study of drill-cores from other localities. Measurements of the specific gravities of certain Keweenawan lava flows of Michigan by the senior author, from material collected in 1915, will be given as a comparison to those of the Cape d'Or flow. It has been found that the specific gravity of drill-cores, or volume per cubic foot, can be readily obtained by measuring their dimensions. This can be done to an accuracy of within 1 per cent. in pieces of core over 100 mm. in length by using a micrometer gage for the diameter, and taking the average of six measurements of the diameter; and the average of four measurements of the length made with a finely graduated ruler. Then, after weighing them, the weight in grams per cubic centimeter, or what is practically the same thing, ounces per cubic foot, is obtained. System-

Jan 1, 1916

By Charles S. Barrett, F. W. Steadman

DEFORMATION bands of surprising regularity are found in large-grained polycrystalline copper after cold-rolling (Fig. I). Individual bands frequently are large enough to permit a determination of their orientation by means of etch pits and an optical goniometer. Measurements have been made on 21 areas in seven different grains, and these, combined with X-ray studies of nine single crystals that had been cold-rolled after mounting in a polycrystal-line block, have contributed to a better understanding of the preferred orientations in rolled copper just as similar studies have for rolled iron' and brass.2.3 Particular attention was given to determining orientations that are stable during rolling and to the manner of fragmentation and rotation of unstable grains. The possible role of twinning was also carefully investigated. The texture of polycrystalline copper after cold-rolling is well established by the pole figures that have been plotted by Schmid and Staffelbach,4 Iweronowa and Schdanow,5 and Brick and Williamson,3 all of which are in substantial agreement. There has been some divergence in the list of individual "ideal" orientations that have been used to describe the texture by these observers and others,6 although the orientation (110) [112]-that is, (110) parallel to the rolling plane and [112] parallel to the rolling direction-is generally recognized as the most prominent orientation and (I12) [111] one of the lesser orientations. Other orientations have been given by some observers as (236) [533], (100) [001], and (I 10) [001]. The texture of copper has also been described as (135) [533].6.1 The sum of these orientations provides a reasonable approximation to the complete pole figure, but it does not follow that these specific orientations are necessarily of fundamental significance, for the choice of indices is arbitrary, within limits. Furthermore, a detailed investigation of the ideal orientations in cold-rolled iron discloses continuous ranges of equally favored positions rather than definite positions of high stability,1 and similarly Brick's observations in a single crystal of a brass2 suggest that all orientations in the range between (110) [113] and (110) [117] are about equally stable. MATERIALS AND METHODS The material used was vacuum-cast electrolytic copper kindly supplied by L. L. Wyman, of the General Electric Co.* Slices 1/2 in. thick and 2 1/2 in. square, cut from the ingot, were rolled with 50 per cent reduction per pass to final thicknesses between 0.02 and 0.04 in., and etched to develop cube-face etch pits suitable for goniometric work.8 The etch was light on some strips and deep in others.

Jan 1, 1942

By Martin Coryell, Eckley Coxe, R. P. Rothwell

WILKES-BARRE, PA., April, 1871. THE great development of the mines and metallurgical works of this country during the last few years, accompanied as it has been by the investment of enor¬mous sums of money in purchasing lands, and in the erection of improvements, requires that advantage should be taken of the accumulated knowledge of engi¬neers, superintendents, and others, in mastering the problems which are con¬stantly presenting themselves for our action. Among those may be mentioned the consideration of more economical systems of mining in our coal and metal¬liferous mines, improved methods of transportation above and below ground, unwatering and ventilating mines, the mechanical preparation of coal and other minerals, the various metallurgical processes, and, in fact, every question tending to the attainment of two great objects 1st. The more economical production of the useful minerals and metals. 2d. The greater safety and welfare of those employed in these industries. In European countries, where the arts of mining and metallurgy have long been the subject of the most careful study, no means have been found so effectual in attaining the end above proposed as the free interchange of experience among those actually engaged in these industries, and this object has been accomplished, mainly, through the medium of institutes, associations or societies, composed of those engaged in these occupations, and by the- periodical publication of essays or papers, communicated to such societies by their members. It must be evident to all practical men that the interchange of the varied experience of those engaged in such occupations in this country could not fail to advance very materially the desired objects; it is, therefore, proposed to establish an American Institute of Mining Engineers, which will hold its meetings periodically in the great mining and metallurgical centres, where works of interest, such as mines, machine shops, furnaces, and other metallurgical works, can be inspected, and the members exchange their views, and consult for mutual advantage upon the difficulties encountered by each; these transactions or proceedings, when published, would form a most valuable and greatly-needed addition to our professional literature. It is proposed that a meeting of those sympathizing with the object above men¬tioned shall be called for the purpose of organizing such an association, the place and time of meeting being Wilkes-Barre, Pa., and the month of April or May. Communications indicating the opinion and wishes of all, both as to these points, and also as to the organization and objects of the Institute, will be gladly received by any of the undersigned, and a notice of the date of meeting, which will be arranged to suit the greater number, will be duly communicated. Any

Jan 1, 1873

By C. H. Bushell, M. Malnarich

REAGENT control in flotation is more an art than a science. Operators vary the amount of reagents used according to the metallurgy obtained. The amount of collector may be increased, for example, if tailings losses are high and decreased if concentrate grades are low. Often control decisions are based on only one assay, such as the tailings analysis by microscopic or quick assaying techniques. This method of control has given reasonably satisfactory results but is clearly far from perfect. No adjustment in reagent addition can be made until information is received that metallurgy has deteriorated, that is, until the optimum time for adjustment has already passed. The first adjustment probably will be an overcorrection or an undercor-rection, and time will be required to establish the best new addition rates. The seriousness of the problem depends on variability of the ore. In ore of continually shifting composition and complexity, mill results will shift back and forth from excessively high concentrate grades and high tailings losses to excessively low concentrate grades and low tailings losses. Economic incentive for improved control also increases with increasing size of mill. Even a small improvement in percentage recovery in a large mill pays for expensive control equipment. The Sullivan concentrator of The Consolidated Mining & Smelting Co. of Canada Ltd. at Kimberley, B. C., treats 11,000 tpd of complex lead-zinc ore, a scale of operations which justifies an extensive research program on automatic control. Work has followed two separate lines: 1) development of faster analytical methods for pulps, and 2) study of metallurgical control by measurement and control of reagent concentrations in flotation solutions. Although work is incomplete in both phases, a progress report can be given on the development of reagent control. The primary requirement in flotation is selective attachment of particles of one mineral to air bubbles while the other minerals remain detached. Hydrophobicity of mineral surfaces is established by the collector, which coats the minerals by adsorption. The requirement of selective affinity for air bubbles is therefore equivalent to requiring selective adsorption of a collector. Adsorption theory, supported by abundant experimental evidence, shows that the amount of a reagent adsorbed at a surface must be a function of its residual concentration in solution. As the concentration in solution rises, the amount adsorbed increases, usually following some type of logarithmic curve. Selective adsorption must depend on a natural difference in the minerals, but ordinarily the differences in affinity are not great enough to obtain complete coverage of one mineral while the others are completely uncoated. An optimum concentration will exist, below which coverage will not be great enough to float enough of the valuable mineral, and above which too much unwanted mineral will float. All other reagents, except some frothers, affect the amount of collector adsorbing at constant residual collector concentration in solution, either by adsorbing competitively with the collector, or by a

Jan 1, 1957

By H. B. Goodrich

Anthony I?. Lucas died suddenly at his home in Washington, D. C., on Sept. 2, 1921. Captain Lucas, as he was known to us, was born in Dalmatia, Austria, in 1855, of Montenegrin ancestry. He was graduated as an engineer at the Polytechnic of Grate and served in the Austrian Navy as second lieutenant. In 1879, he obtained leave of absence and visited an uncle in the United States. After an extension of this leave of absence, in order to undertake an engineering engagement in the lumber district of Michigan, where he resided, he decided to become an American citizen. He was naturalized in May, 1885. His name was Luchich, but as his uncle had adopted the name of Lucas, which was more easily pronounced by Americans, from his entrance to this country, he used this Anglo-Saxon form. Without knowing this fact, upon first meeting him a person was sometimes surprised to note the rather Germanic pronunciation of the Captain. Although he subsequently revisited Austria with Mrs. Lucas, he made his permanent home at Washington, D. C. His son served with distinction in the A. E. F. during the World War. His activities in this country as a mining engineer were at first in Colorado and later in salt mining at Petit Anse and Belle Isle, La. During his salt investigations, his attention was directed toward the possibility of oil in the Gulf Coast region and in January, 1901, his well, the "Lucas Gusher," on Spindle Top, Tex., started a new era in the oil business and his reputation as discoverer made him famous throughout the world. Captain Lucas became a member of the A. I. M. E. in 1895. During 1914, 1915, 1918, and 1919, he was chairman of the Petroleum and Gas Committee of the Institute and was at all times prominent in Institute affairs. As to the personality of Captain Lucas, the lasting impression is of a courteous hospitable gentleman, genial, affable, obliging, and helpful with his advice br assistance to any colleague. He was sincere, honest, firm against all obstacles, backing his judgment with his own hard work along any course which he had determined to be correct. His value in the engineering world lies mainly in the petroleum industry. In the oil business all wild-catters are pioneers that deserve credit and gratitude upon their success. There are, however, names that particularly stand out in our history. Drake conquered such obstacles as ridicule, lack of finances, and started the oil business. In 1901, Captain Lucas had the conviction that Spindle Top, a dome rising about 12 ft. above the coastal prairie south of Beaumont, Tex., contained commercial oil. He was scoffed at by practical oil men of the East. Noted geologists

Jan 1, 1921

By H. H

This paper describes the milling practice and operating results of the recently installed heavy-media separation plant of Barton Mines Corporation, the world's largest producer of garnet. This pioneer application of heavy-media separation (sink-float) processes for the beneficiation of a nonmetallic ore is unique in many respects, the details of which will be apparent from the following presentation. Characteristics of the Ore The property is on Gore Mountain, 5 miles west of the village of North Creek, New York, and 11 miles by road. The altitude of the mine is approximately 2800 feet. The valuable mineral, garnet, occurs in a surface deposit, the ore body being about ¾, mile long and varying in width from 50 to 300 ft. The garnet, principally almandite, Fe3Al2 (SiO4)3, occurs in a metamorphic rock of uncertain origin. The gangue mineral is principally hornblende, which constitutes from 40 to 80 per cent of the rock. The remainder of the gangue is divided between plagioclase feldspars and hypersthene, with smaller amounts of biotite, apatite and pyrite. The garnet content of the ore body varies from 5 to 20 per cent of the mass and averages about 10 to I2 per cent. The garnet occurs as crystals, mostly imperfectly developed, known locally as "pockets." These crys- tals vary in size from a fraction of an inch to a foot or more in diameter. Occasionally crystals have been found up to 30 and 36 in. in diameter but they average 4 to 6 inches. Nearly every crystal of garnet is surrounded by a rim of coarsely crystalline hornblende. The quarry faces are striking in appearance, showing crimson-red garnet crystals with their coal black rims scattered over a grayish black background. The specific gravity of the garnet is 3.8 to 4.1 while that of the hornblende ordinarily is 3-07 to 3.24. Some specimens of very dense hornblende have been found with a specific gravity as high as 3.40. The garnet crystals are laminated in structure, and readily cleave into flat, tabular pieces with sharp, chisel-like edges. Even when crushed to a very fine size, the garnet retains this flat, sharp, slivery grain shape. This characteristic, together with its hardness and toughness, gives it its value as an abrasive- Former Operations Mining operations have been carried on for 60 years. Until 1923, only the oxidized (soft rock) section of the ore body was mined. The oxidation, which affected the garnet only slightly, made possible the removal of the garnet from the rock by hand after it was blasted down, using small hand picks. In 1923 a mill was erected on the property, and was rebuilt and redesigned in 1928. Before the adoption of heavy-media separation, concentration was effected by

Jan 1, 1943

By Stewart. J. W.

THE aim of this paper is to point out the various ways in which design is taught in standard four-year mining engineering curricula in American colleges and universities; to discuss the reasons apparently justifying the great diversity of procedure that exists along this line; and to indicate possible solutions to the difficulties now attending the teaching of design. A study was made of typical four-year mining engineering curricula in 15 colleges and universities of the United States (Table I). Great diversity in content of the various design courses, if taught as described, became apparent immediately. It appeared that it might be both interesting and instructive if the cause for this colorful variety could be found. Was the cause local mining conditions, departmental individuality, or actual necessity? Study of the school catalogues revealed that the various design courses could be classified into two fairly distinct types; namely, (I) those dealing with mine equipment or structures, and (2) those dealing with underground layout of mine workings. It seemed reasonable to label the first type of course "mining design" and the second type "mine design." Some such distinction must have been in the minds of mining educators, for we find both names (i.e., mine design and mining design) used to designate the design courses included in the various mining curricula. Unhappily, the name and the apparent content of such courses do not, in all instances, conform to the classification made here, although in most instances such conformation does obtain (Table I). It is possible that in the exceptional case the method of teaching a design course, and consequently the content of it, may have been changed at some time without change in the name of the course. Apparently only. 3 of the 15 schools made an effort to cover both types of design in their curricula (Table I). Two other schools did not list or describe any course of study that could with certainty be taken as a design course. Of the remaining 10 schools, q gave a mining-design type of course and one gave a strictly mine-design type. Obviously, the preponderance of design courses afforded are of the mining-design type. Why? To answer this question, it is necessary to make a study of the prerequisites for the two types of design courses taught. In all schools the design courses were taught in the senior year; in eight, design was taught throughout both semesters; in two, it was taught during the first semester only; and in three it was taught during the second semester only. Consequently, excepting the last three cases noted, it is obvious that all prerequisites for a design course should be completed by the end of the junior year. PREREQUISITES What are the probable prerequisites for the different kinds of design courses as they appear to be taught? Let us take first the case of the mine-design type of course, having to do with layout of underground workings. Here it would seem that logical

Jan 1, 1941

By A. J. Shaler, J. Prieto Isaza, J. Wulff

Tantalum metal has a number of unique properties which give it widespread application in modern technology and in research. In electronic apparatus involwing high temperatures in vacuo some of the refractory metals 6ecome brittle. Tantalum retains its ductility at elevated temperatures, and this property, together with its low vapor pressure and its ability to absorb gases, make it important in this field. Its chemical inertness in the presence of acids, halogens, and other corrosive media, makes it useful in chemical apparatus and in neuro and orthopedic surgical applications. As an addition to tungsten carbide in steel-cutting grades of cemented-carbide tools, the carbides of tantalum and of its sister element colum-bium have found considerable use. The present-day method1 of manufacturing tantalum is to sinter a powder compact of the metal in vacuo. Because tantalum-columbium alloys are difficult to work and since tantalum ores almost always contain columbium, the two metals must be separated chemically, the products of the separation being generally in the form of potassium tantalum fluoride and potassium columbium oxyfluoride. These salts are used in fused-salt electrolytic baths from which coarse metallic powder is deposited as a sponge at the cathode. Finer powder can be made from the coarse product or from tantalum scrap by first submitting it to an embrittling heat treatment in hydrogen and then crushing it. The fine hydrogen-containing powder may subsequently be degassed in vacuo at a high temperature. Prompted by the success of others2,3 in the magnesium reduction of titanium and zirconium halides; one of the authors undertook4 an investigation of the thermochemistry of the reaction between solid magnesium and gaseous tantalum penta-chloride, a subject which had not previously been studied. He found that the heat of formation of tantalum pentachloride is approximately 364,250 cal per mol at temperatures lower than the melting point of magnesium. A value of 83 units was found for the standard entropy at these temperatures. With these values, it was shown that magnesium and tantalum pentachloride are capable of reacting exo-thermically at temperatures less than the melting point of magnesium, and that no great violence is to be expected when these substances are heated together. The exothermic nature of the reaction indicated that the Drocess should be efficient and should not require much externally applied energy. Tantalum pentachloride is not commonly made commercially, and any process using it therefore involves the subsidiary problem of producing and handling this substance. A series of experiments was carried out in which dried chlorine saturated with carbon tetrachloride was passed over heated tanta-

Jan 1, 1949

By Cuppam Dasarathy

THE object of this note is to report briefly certain results of investigations on the Fe-In phase diagram. BISRA-high purity H-iron and 99.9 pct pure indium were used to prepare the alloys. The experimental techniques consisted of thermal analysis, optical metallography, and X-ray diffraction. A phase diagram based on the present results as well as those reported earlier by the author' is shown in Fig. 1. It is seen that the liquidus points fall on a smooth line which meets the monotectic isotherm at 1470°C. The liquidus extends up to 3.4 at. pct In. The phase boundary separating the two liquidus L1 and L2 is shown dotted. The experimental solidus meets the monotectic isotherm at -0.9 at. pct In. The 6/6 + L2 boundary drops steeply to the 6 + La/y + L2 boundary at -1350°C. In this region, it is impossible to detect satisfactory thermal arrests because of the steep phase boundary. The present diagram shows that indium lowers the temperature of the d/y transforma-tion and raises the temperature of the y/a transfor-mation. The y +d region is found to be very narrow. Indium gives rise to a restricted y field when alloyed with iron. The width of this field is between 0.4 and 0.5 at. pct In. Details of the alloys containing 40 and 50 at. pct In have already been reported by the author' and the transformation temperatures of these alloys are included in Fig. 1. It appeared from optical metallography and X-ray diffraction that the room temperature solubility of indium in a iron is less than 0.28 at. pct since alloys of 0.28 at. pct In and above, slow cooled to room temperature, contained dark etching second phase particles situated both in the matrix and grain boundaries of the a-grains, see Figs. 2 and 3. These particles were identified to be unalloyed indium by X-ray diffraction. The lattice parameter of the a phase reached a maximum of 2.8672A at the indium level of -0.28 at. pct. The present diagram, Fig. 1, is in substantial agreement with that of Stadelmaier and Fiedler' except for certain differences in detail. For example, they found the monotectic composition and temperature to be 7.0 at. pct In and 1443oC, respectively, while the present work indicates them to be 3.4 at. pct In and 1470°C. The 6 + L2/y + L2 transformation is indicated in the present work to occur at -1350°C, whereas Stadelmaier and Fiedler find this to occur at -1320°C. They also claim that the width of the y field is 0.2 at. pct In while the present work shows the width to be between 0.4 and 0.5 at. pct In. 1) Indium, when alloyed with iron, gives rise to a restricted y field, the width being >0.5 at. pct In.

Jan 1, 1970

By Benjamin N. Webber

THE peninsula of Nicoya contains virtually all of the known manganese deposits of Costa Rica. These are south and west of the Tempisque River, which flows across the peninsula near its juncture with the mainland. This peninsula forms the westernmost part of the province of Guana¬caste, which is the northern of the two Pacific Coast provinces of Costa Rica. The larger villages are connected by ox-cart roads and trails. The area may be covered on horseback without difficulty except during the rainy season, when rivers are in flood and difficult to ford. This is particularly true of the Rio Seco-Guayjiniquil area, where there are no inhabitants and few open trails through the tropical jungle. Santa Cruz and Sardinal are served by the Taca Airlines, two planes a week from San Jose and Puntarenas. The port of Puntarenas has excellent loading facilities but none are available nearer the manganese districts; there ore must be lightered to vessels standing offshore. PHYSIOGRAPHY In Costa Rica there are three physiographic divisions: (I) the central plateau (Mesa Central), a somewhat dissected lava platform upon which are superimposed volcanic peaks, some of which are still active; (2) the Atlantic lowlands and (3) the Pacific lowlands. The peninsula of Nicoya and the larger part of the province of Guanacaste lie within the Pacific low lands. The term "lowland" indicates relation to the central plateau, as the peninsula of Nicoya is largely mountainous. The mountains of Nicoya form the southern extremity of a range of low hills, which are almost continuous along the Costa Rican coast to the Nicaraguan border. The coast line shows evidence of subsidence. The Gulf of Nicoya obviously is the drowned valley of the Tempisque River. The west coast of Nicoya shows many rocks, shoals, bays, inlets and small islands as evidence of a sea encroachment. The altitude of the manganese deposits ranges from 0 to 800 ft. Topography is of the mature type of wide valleys and low ,hills, often with abrupt slopes. The climate is tropical and humid; rainfall of 125 in. falls largely between Sept. I and Jan. I. Vegetation often is very dense, the Rio Seco-Guayjiniquil area being truly tropical jungle, containing many hardwoods. HISTORY AND PRODUCTION The production of manganese ore in Costa Rica apparently dates from the first World War. It reached a peak of about 10,000 tons in the year 1919, then declined rapidly. Evidence of this period of prospecting has rotted away or been swallowed by the jungle. The war now in progress apparently revived the interest in Costa Rican manganese and has encouraged further prospecting. Deposits long known have been redenounced and trails have been cut through the jungle to them. Many new deposits have been discovered in the last

Jan 1, 1942

By Thomas T. Read

MINING, which is at least twenty centuries old, was at first, and long, wholly a practical art. Little more than two centuries have elapsed since the inception of the idea that general education and a knowledge of natural science would be of advantage to those engaged in the mining industry. Though schools of mining began to develop in Europe early in the eighteenth century the concept of educational preparation for technical conduct of the industry was slow in winning general acceptance in the industry itself. John Hays Hammond, in his autobiography,1 recalls that when he sought employment with a mining company after he had graduated from Yale and Freiberg he had to assure its executive, before being even considered for employment, that he did not consider that he had learned anything about mining. This was as late as 1880. Existence in the industry of a prejudice against education of the academic type is perhaps an explanation why inadequate provision has been made by the mining industry for the continuing education of technical employees after they enter employment, although engineering education prior to engaging in industry has now won general acceptance. I am familiar with the existence of "loop" courses for engineering graduates in metallurgical plants, of schemes for giving mining graduates "practical experience," and of the interest in vocational courses for workmen which sprang up in the period of labor shortage during and immediately following World War I (but which quickly died when the depression of 1921 again made experienced workmen available in sufficient supply), having been chairman of a committee appointed by the Mineral Industry Education Division to make a survey of existing provisions for post-employment training for engineers in our industry. The results of that survey, reported elsewhere, clearly indicate that it is inadequate as to amount; the aim of this paper is to present evidence for belief that it is also inadequate in quality. To avoid becoming too involved, no reference will be made here to post-employment vocational training for workmen, which is a subject differing so much from post-employment education for engineers as to require separate treatment. Neither will postgraduate education for metallurgical engineers be discussed, because a distinction must then be made between training for research work and for plant operation, whereas mining engineers engage almost exclusively in operations. Since the situation in the coal-mining industry has been discussed at several recent meetings, that also will be passed over, and what follows should be taken as a discussion applying exclusively to the metal-mining industry. PROFESSIONAL DEVELOPMENT In the operations field (both in mining and metallurgy) the work to which a beginner is assigned is seldom closely related to previous academic education. The contrast is almost as great as between

Jan 1, 1941

By Arthur Tauber, Horst Kedesdy

FERRITES are sintered metallic oxides of the spinel structure type1 and belong to the class of soft ferromagnetic materials. Similar to a ceramic, they can be formed and fired to a dense body, exhibiting a high electrical volume resistivity ranging from 10 90 10' ohm-cm as compared with 10-6 hm-cm for some of the metallic magnetic materials. This high resistivity, with resulting low eddy current losses, finds special application at high frequencies. The dispersive susceptibility of ferrites at microwave frequencies has also led to many applications in this field. Where high resistivity with high permeability is desirable, ferrites are used in low frequency applications. During the last few years ferrites exhibiting rectangular hysteresis loops have been developed for computer and magnetic memory systems. The general formula for ferrites is MeFe2O4 where Me is a divalent metal ion such as Ni, Zn, Mg, Mn, Cu, Cd, and Fe. Only two of these ferrites are nonferromagnetic, namely, those with Zn and Cd. Solid solutions can be formed between different ferrites, and it is of interest to note that solid solutions of a ferromagnetic ferrite with a nonferromagnetic ferrite yield much better magnetic materials than the basic ferrite body. In general, it can be said that the solid solution formation between ferrites has widened the field of ferrite synthesis and has led to methods of preparing materials with a large variety of magnetic properties. During the last two decades the synthesis of ferromagnetic oxides has been the object of extensive research, but commercial production has been started only within the last ten years. Along with more fundamental studies, there remains the never- ending task of developing ways to realize the optimum characteristics of materials in large-scale production. Ordinarily, to produce a ferrite material it is necessary for the constituent oxides to be mixed intimately, pressed, and then fired at temperatures above 1000°C. Ferrite Synthesis: Formation of a basic ferrite by solid state reaction from Fe,O, and a monoxide such as NiO, under normal atmospheric conditions, is governed by a progressive diffusion of cations between adjacent particles of the constituents. Firing temperature, furnace atmosphere, and cooling can vary the magnetic properties, however. If, for example, a dioxide, a sesquioxide, or an oxide of the Me0 type is substituted for the monoxide, the reaction mechanism becomes more complex and extremely dependent on atmospheric conditions and firing cycles. For this reason reproduction often

Jan 1, 1958

By E. H. Burdick

THE difficulties inherent in table concentration operations as applied to gold, silver, lead and zinc ores, are accentuated in the scheelite mill, which has a flowsheet that is similar in general principles. The narrow "spread" in the specific gravity between scheelite and the usual gangue in which it occurs often makes its clean separation extremely difficult and in some cases impracticable. The problem is further complicated by the extreme friability of the mineral and its inordinate tendency to "slime," particularly where fine grinding is necessary and wet grinding methods are employed. The physical aspect of the occurrence of scheelite in the ores, the kind and character of the rock in which the mineral is present, its hardness, friability and the specific gravity of its constituents, as well as like characteristics of the associated minerals-pyrite, pyrrhotite, sphalerite, and others, all have a bearing on the successful milling of crude ores and the production of a concentrate that is marketable with minimum price penalty or none at all. Most tungsten deposits are considered low grade when the limiting factor of low percentage recovery by gravity methods is borne in mind. The great majority of deposits developed or in process of development carry from 0.4 to 1.0 per cent tungstic oxide. Ore carrying I per cent is considered good grade; 0.7 to 0.8 per cent, fair, and below that figure, low grade. Steady mill feed averaging upward of 1.0 per cent W03 is exceptional. Inasmuch as buying specifications demand a 60 per cent W03 content, the mineral content of the ores as mined must be concentrated to at least that degree. A few companies have constructed chemical plants for the treatment of their complex concentrates and low-grade flotation product, but the smaller operator must rely on table concentration, borrowing the tools and to a large extent the methods of his predecessors in the gold, silver, lead and zinc mills. Whether these are the best tools and methods that can be devised is an open question. Except in rare instances, table concentration, however carefully conducted, does not yield a satisfactory final recovery of the mineral content in headings as indicated by chemical determinations of tungstic oxide content. A saving of 60 to 65 per cent is considered fair, and an average 80 per cent recovery, exceptional. Each scheelite ore body is a separate problem. Details of handling that give best results in one case may not be successfully operative at a property on the same contact zone and but a short distance removed. Supplementary treatment of tailings by flotation may be successful in producing a low-grade concentrate of around 15 per cent WO3, which is adapted to further treatment chemically at a given property and entirely unsuccessful at another. This problem constitutes another of the unanswered questions. The following paragraphs relate solely to the beneficiation of scheelite ores by table concentration and supplementary methods.

Jan 1, 1942