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By John T. Norton, V.G. Mooradian

The diffusion of metal atoms into the crystal lattice of another metal and the assumption of regular positions to form a homogeneous alloy are some of the most fundamental phenomena of structural metallurgy. The mechanism of this process has been the subject of a great deal of study from many viewpoints, but the picture is still far from complete. It is generally believed that if one metal is to diffuse into another, the first must have some solubility in the second1. This means that the solvent must be able to accommodate the stranger atoms, either on points of its own lattice or in the interstices between, without losing its own crystal-lographic identity. It is also a general observation that cold-working is a distinct aid in the diffusion process, causing it to take place with greater rapidity at the same temperature or with the same speed at a lower temperature. There is considerable doubt, however, as to the real significance of the deformation in its effect on the diffusion mechanism. Several factors associated with the cold-working may be responsible for the increased diffusion rate. The plastic deformation causes a distortion of the solvent lattice, which may be an aid in the assimulation of atoms of another kind. There are many references2 in the literature that suggest that some distortion or "loosening" of the lattice is necessary for atomic migration and that diffusion cannot take place in the undis-torted lattice. On the other hand, it may be that the cold-working causes an increase in surface of contact between the two metals through fragmentation or provides a more intimate contact that is necessary for diffusion. If it is true that lattice distortion is an important factor in diffusion, it seems as if there should be some particular relation between

Jan 1, 1935

By J. B. Morrow, D. H. Davis

THERE are two general approaches to the problem of increasing profits from an operation. One is to lower expense; the other is to raise income. Mechanical preparation of coal may be used for either purpose but a prudent consideration of many details must precede any decision lest the results be negative instead of positive. It is quite possible that any net gain will result from a combination of the two. Since mechanically prepared coal invariably is a better product qualitatively than a hand-picked coal from the same mine, it is a reasonable expectation that the customer will be willing to increase the producer's income by paying a higher price. Or there may be the possibility that a combination of mechanical mining plus mechanical cleaning will give a lower over-all production cost for the coal in the railroad car. More likely, there will be found a combination of these two factors. From the customer's point of view, the competitive delivered cost per B.t.u. considered in relation to such incidental factors as dust nuisance, handling properties, ash disposal, and ash fusibility determines what he will pay. In-a bulk tonnage such as coal, freight is a very considerable part of the delivered fuel cost, and obviously freight paid on incombustible ash has no economic attractions. INCENTIVE FOR CLEANING Coal is prepared in four major ways: l (1) by screening or sizing, (2) by mixing or blending, (3) by cleaning, including hand picking and mechanical cleaning, (4) by dustless treatment. By a combination of any or all of these methods, coal can be prepared to standard specifications. It is easily possible to have good cleaning and still get a poor final product because of faulty screening or mixing, while it is possible to produce a very acceptable product from mediocre cleaning if the coal is well screened and mixed.

Jan 1, 1950

By K. A. Johnson, H. F. Yancey

Physical properties have been used for a long time in characterizing different kinds of coal, and such physical properties as friability and slacking have been included along with chemical properties in grouping coals according to the widely used system of classification adopted by the U. S. Geological Survey. Nevertheless, the usefulness of physical properties for classifying the different ranks or kinds of coal has been limited because it has not been possible to express these properties in definite form as numerical values. Because of the present wide interest in the formulation and adoption of a satisfactory system of coal classification, the Northwest Experiment Station of the U. S. Bureau of Mines, in cooperation with the College of Mines of the University of Washington, has recently completed a study of the physical and chemical properties of approximately 100 different coals ranging in rank from lignite to anthracite. Purpose and Scope For this investigation samples were collected in approximately 45 mines and prospects in Washington and 23 mines in other states. The following studies, in addition to proximate and ultimate analyses, were made of the samples: Determination of (1) friability, (2) slacking or weathering characteristics, (3) yield of products by low-temperature carbonization in a laboratory retort, and (4) agglutinating value. Most of the coals examined were subjected to each of the tests enumerated, but with coal of some ranks this was unnecessary in some instances, and in others it was not feasible to do the work involved. A report which includes the analyses of the coals and the details of the methods of examination used in the investigation is being published by the Bureau of Mines.' It is the purpose of the present report to show the results of the friability, slacking, low-temperature and agglu-

Jan 1, 1932

By V. G. Mooradian, John T. Norton

The diffusion of metal atoms into the crystal lattice of another metal and the assumption of regular positions to form a homogeneous alloy are some of the most fundamental phenomena of structural metallurgy. The mechanism of this process has been the subject of a great deal of study from many viewpoints, but the picture is still far from complete. It is generally believed that if one metal is to diffuse into another, the first must have some solubility in the second1. This means that the solvent must be able to accommodate the stranger atoms, either on points of its own lattice or in the interstices between, without losing its own crystal-lographic identity. It is also a general observation that cold-working is a distinct aid in the diffusion process, causing it to take place with greater rapidity at the same temperature or with the same speed at a lower temperature. There is considerable doubt, however, as to the real significance of the deformation in its effect on the diffusion mechanism. Several factors associated with the cold-working may be responsible for the increased diffusion rate. The plastic deformation causes a distortion of the solvent lattice, which may be an aid in the assimulation of atoms of another kind. There are many references2 in the literature that suggest that some distortion or "loosening" of the lattice is necessary for atomic migration and that diffusion cannot take place in the undis-torted lattice. On the other hand, it may be that the cold-working causes an increase in surface of contact between the two metals through fragmentation or provides a more intimate contact that is necessary for diffusion. If it is true that lattice distortion is an important factor in diffusion, it seems as if there should be some particular relation between

Jan 1, 1935

By C. A. Mitke

In the Southwest, mcchanical ventilation of metal mines has been receiving consideration for many years. The United Verde Copper Co., in Jerome, has used large mine fans for ventilation and fire-fighting purposes for at lcast 15 years, while the Copper Qucen Branch of the Phelps Dodge Corpn. commenced installing mechanical ventilation in its various divisions 10 years ago.' Since then, with few exceptions, every large mine in this part of the country has installed and put in operation a mechanical ventilating system. The properties of some of these companies consist of from two to six divisions, or separate mines, each of which requires an independent ventilating system. In other words, thirteen copper mining companies, with an aggregate tonnage, when operating at capacity, of approximately 50,000 tons a day, have installed mechanical ventilating systems in their mines. All these mines are within a radius of approximately 200 miles, which constitutes the largest copper-producing area in the world. The capacities of mechanical ventilating installations in these mines range from 100,000 to 300,000 cu. ft. of air per minute, depending on the size of the mine, character of the workings, tonnage produced, etc. The latter varies from 300 to 20,000 tons per day. The mines include both high- and low-grade deposits, the greatest depth of the former, at present, being approximately 2500 ft.; and of the latter, 1200 ft. The volumes of air at present being coursed through the mines are from 60,000 up to 225,000 cu. ft. of air per minute,which, in their relation to the undcrground working force, range from 200 to 800 cu. ft. of air per man, per minute. While not to be taken as criteria, these figures are indicative of the character of the ventilation furnished.

Jan 1, 1923

By E. H. Jr. Dix

THE success of the Charpy impact test in the steel industry has led those interested in aluminum alloys to investigate the possible applica¬tion of this test to aluminum and its alloys. In this paper are set forth the results of a few preliminary tests made at the Lynite Laboratories of the Aluminum Manufactures, Inc. In order to study more thor-oughly the significance of the Charpy test, slow-bending tests have been made duplicating the arrangement of the impact machine. Tests have been made on both notched and unnotched specimens of a series of copper-aluminum alloys. APPARATUS The standard American-made Charpy impact machine delivering a blow of over 200 ft.-lb. was- much too large to test aluminum-alloy specimens of the same type used for steel, so that it was necessary either to adopt a larger specimen or to have a special light-weight hammer made. Since there is no known relation between specimens of different sizes, even though geometrically similar, it was decided to adhere to the 10 by 10 mm. specimen. Accordingly, Sauveur and Boylston, the American makers of the machine, were asked to construct a special light-weight pendulum adapted to their standard machine, this pendulum to have one-tenth the capacity of the standard. The writer wishes here to acknowledge his indebtedness to Mr. H. M. Boylston for the personal interest and care exercised in constructing this pendulum. The machine with, the light-weight hammer in place is shown in Fig. 1. It is mounted on a concrete foundation with the concrete covering the flange on the base of the machine. Vibration is further prevented by four 5/8 -in. (15.8 mm.) foundation bolts. The large standard hammer shown against the wall was also used for some of the unnotched bars that requited more than 20 ft.-lb. to rupture.

Jan 4, 1920

By J. T. Eash, W. S. Crowell, E. M. Wise

The practice of dentistry, particularly the construction of artificial dentures and "bridges," involves a unique and difficult application of the precious-metal alloys. Appliances used in the mouth are continuously exposed to corrosive agencies which can hardly be described as mild, and must remain free from tarnish and be substantially immune to corrosion. Limitations with respect to space and weight demand high physical properties, while complexity of form requires ease of working. The high corrosion resistance required necessitates the use of alloys of high precious metal content. The usual expedient of resorting to mechanical working to produce the requisite strength and stiffness cannot be utilized because of the frequency of annealing and soldering operations. To meet these difficult conditions manufacturers of dental goods were early led, unknowingly perhaps, to the production of precipitation-hardening or temperable alloys. The excellent properties of iridium-platinum may have suggested the addition of platinum metals to the conventional gold-silver-copper alloys to produce greater strength and hardness. It was found that such quarternary alloys retained their high physical properties after passing through the usual soldering process; i. e., heating to 750° to 800" C. and cooling naturally in the air. Later it was discovered that they could be softened and rendered more ductile by heating to the same temperature and quenching in water. These early examples of precipitation hardening, for years the common knowledge of dental practitioners and laboratory technicians, escaped the attention of the scientific world and discovery of the transformation which was responsible for this hardening was disclosed by the Russian investigators of the system Au-Cu, Kurnakow, Schemtschushny and Zasedatelev~,(~)$ although the optimum conditions for securing good properties in aged alloys were not given attention.

Jan 1, 1932

By Paul Weaver

OF the four papers that comprise this TECHNICAL PUBLICATION, three are case histories of individual geophysical prospects, subsequently tested by drilling. The bibliography of Dr. Barton's published scientific papers† includes investigaions in physiography and surface geological mapping, as well as his geophysical papers, and from this list it is to be observed that he early recognized the place of different types of geophysical prospecting methods in the search for geological structures of economic importance. Moreover, his viewpoint was not merely that the structures should be found, but that the geophysical data should be examined quantitatively to determine the geometry of the structures. In other words, that although these data are insufficient to deduce a unique form for the structure that caused the effects measured in the data, the engineering computations should be carried-out to give as much of a definite configuration to he structure as the data permitted, in order that the testing of the structures could be conducted in the most economical manner and with the idea that the experience so gained could be later incorporated in the study of structures subsequently found. Dr. Barton continually emphasized the quantitative use of geophysical observations, whereas at the time that he began his specialization in geophysics it was considered sufficient to use observations only qualitatively. He, more than any one else, was responsible for -the first volume on geophysical prospecting issued by the Institute in 1929, and his three articles in that volume stressed the quantitative use of geophysical prospecting. The fourth article in this present TECHNICAL PUBLICATION is a further contribution to this branch of geophysical interpretation, and is a supplement to the paper in the 1929 volume, "Calculations in the Interpretation of Observations with .the Eötvös Torsion Balance." From the successful' demonstration by Dr. Barton of the usefulness of quan-

Jan 1, 1944

By E. C. Carris

THE particular field of application of machines utilizing air currents as the primary separating medium is in the cleaning of the fine sizes of bituminous coal. Approximately 12,000,000 tons of bituminous coal were cleaned by air machines during 1940.They have not found any application for cleaning anthracite. Since the development and introduction of the first successful commercial pneumatic oscillating machine for cleaning bituminous coal in 1916, by the Sutton, Steele and Steele Co., Dallas, Texas, and the American Coal Cleaning Corporation, formerly of Welch, W. Va., four other successful pneumatic coal-cleaning machines have been developed and introduced to the American coal-mining industry: 1. Peale Davis: "Pneumo-Gravity" machine, 1924. 2. Arms "Concentrator," oscillating table, 1924. 3. Hey1 and Patterson oscillating table, 1927. 4. "Stump Air-Flow," pulsating air jig, 1932. Out of these five developments only the Sutton, Steele and Steele, or American Oscillating, and the Stump Air-Flow Jig remain on the market. They are the predominating pneumatic coal-cleaning machines in use in the United States. HISTORY OF AMERICAX TYPE SEPARATOR The first successful American machine, the CJ table (Fig. 1) was developed by the Sutton, Steele and Steele Co. The SJ table was the first standard model designed specifically for the cleaning of coal. It was installed in the original Crane Creek plant, owned and operated by the American Coal Co. at McComas, West Virginia. This plant was designed by The Roberts and Schaefer Co., Chicago, Ill., working in cooperation with the American Coal Cleaning Corporation, which had taken over the patent rights and sale of the pneumatic separators. Eight machines were installed in this plant. They were known as the type SJ. They were 60 by 84 in., the short dimension being the width of

Jan 1, 1943

By Joseph B. Perry, G. M. Kirwan

MAGNESITE is found in 22 California counties, but many of the deposits are too small or too impure to be of commercial value. Several of substantial size and quality were entirely exhausted by wartime operation. At present, three properties comprise the only known workable deposits in the state. Of these, the Western mine and the Patterson mine have been known and worked for many years, and have been described in considerable detail in various publications, therefore need only brief mention here, because of their proximity to the Bald Eagle mine. The latter, recently developed, is unusual in type of ore deposit, plant design and operation, as well as products made, and very little has been written concerning it. WESTERN MINE The Western mine, 32 miles south of Livermore, Calif., was formerly operated by C. S. Maltby. It has been a consistent producer for many years.1 The ore is of amorphous variety, occurring along fracture zones in serpentine. The veins vary greatly in width, the average being perhaps 8 ft., with the maximum indicated in one early stope of 40 ft.; 2 ft. is considered the minimum for economical mining. The strike of the veins is predominantly north and south, with dip to the west varying from 40º to 75 º. Walls are well defined and as a rule firm and easily supported. Veins range in length from a few hundred feet to 1000 or more. Their maximum vertical extent is about 350 ft., but many run less. Early mining consisted of open-cut and glory-hole work on the larger outcrops. This was followed underground by a modified shrinkage system, the waste and low-grade horses being removed by hand sorting on the tramming levels and transported to surface dumps. Filled-stope mining is used now, in order to eliminate the handling of waste, which has

Jan 1, 1938

By S. Usui, I. Iwasaki

The adsorption mechanism of dodecylammonium acetate (DAA) on mercury in potassium fluoride solutions at natural, near neutral pH was investigated. Difler-ential capacity combined with electrocapillary measurements on a dropping mercury electrode were found to provide a sensitive and reliable approach. A shift in the electro capillary maximum (or the point-of-zero-charge) towards positive polarization of the surface due to the adsorption of amine indicated a specific affinity of dodecylammonium ion for mercury surfaces. The amine was shown to adsorb competitively with potassium ion on mercury. Through correlation of the adsorption density of the amine, calculated from the thermodynamic analyses of the electrocapillary curves, and of the diflerential capacity curves, the adsorbed state and the orientation of the amine at the interface were considered. The similarities and the differences in the adsorption behavior of the amine on mercury and on such ionic solids as quartz, silver sulfide, and silver iodide were evaluated. With the promise of flotation providing a cheap and large-scale process for the upgrading of low-grade ores and magnetic concentrates, the iron ore industry has made a sustained search over the years for a flotation reagent of general applicability and high selectivity. Having shelves full of commercial reagents already on hand and anticipating more, both the users and the suppliers are in need of an experimental approach sensitive enough to differentiate the individual characteristics in each group of reagents. Therefore, the adsorption behavior of various flotation reagents on mineral surfaces from aqueous solutions has been a subject of much investigation. The current view of adsorption based on the electrical double-layer theory is formulated on the assumption that certain ions in solution act as potential-determining ions. Their concentrations fix the potential drop across the double layer and their adsorptions govern the surface charge.' Two methods used to study the adsorption

Jan 1, 1971

By Edmund S. Davenport

The production of thorium of high purity by the Ca-CaCl2 reduction has been described by Marden and Rentschler,1 who also reported some of the properties of the coherent, ductile metal obtained from this pure thorium powder. The present paper describes the properties of thorium produced by the Ca-CaCl2 process modified in some details to meet commercial conditions. The principal effect of these changes in process has been an unavoidable increase in the oxide content of the thorium. Materials and Methods The thorium employed in this investigation was made from pure thorium oxide (ThO2) by the Ca-CaCl2 reduction. The washed and dried metal powder was pressed into bars approximately 0.160 in. dia. and 10 in. long, at a pressure of 75,000 Ib. per sq. in. The bars were heat-treated in vacuum at 1175' C. for 1 hr. This treatment yielded ingots sufficiently dense and coherent for mechanical working. Thorium has been successfully worked without a protective metallic covering, but for the purposes of this investigation it was more convenient to inclose the ingots in soft iron tubes and swage or roll cold to the desired sizes. The iron sheath was dissolved with nitric acid, leaving the cold-worked thorium exposed. Chemical Analyses Analyses of typical samples of the material used in this work arc given in Table 1. Thorium powder oxidizes in moist air, even at room temperature; no unusual precautions were taken to prevent such oxidation of the material used in this investigation. A certain amount of oxidation probably takes place during pressing; certainly during heat-treating unless a very slow heating schedule is employed. These factors account

Jan 1, 1930

By Henry Rawdon

Cold-working is generally considered as a process of hardening metals. Diamet-rically opposite statements concerning the applicability of the scratch-hardness method in the testing of cold-worked metals, particularly after severe deformation, which exist in the technical literature led to the study of the results which are summarized in this paper. A series of metals, of which copper, iron and tin are used as illustrations here, were cold rolled to a definite degree without any intermediate annealing and the hardness determined by both the scratch and Brinell methods. The results indicate that the metal hardens rapidly during the initial stages of deformation; however, after a certain stage, which corresponds to a rather definite microstructure, the metal becomes softer and in its final form may be softer than the metal in its initial stage. As part of the study of the scratch-hardness method for metals and alloys in cooperation with one of the technical committees of the American Society for Testing Materials, the authors devoted considerable time to the study of the changes in hardness of metals when cold rolled. Various seemingly contradictory statements in the technical literature concerning the applicability of the scratch-hardness method to such cold-rolled materials were among the principal reasons for the investigation, the results of which are in part presented here. The effect of cold deformation, at least in moderate degrees, on the hardness as measured by the Brinell and other common methods is so well known that further reference is unnecessary. Concerning the scratch hardness of cold-worked metals, Martens and Heyn state' that hardness, whether measured by the ball-pressure method (Kugeldruck) or by the scratch method (Ritzverfahren), will be increased by cold deformation. Jeffries and Archer give a seemingly diametrically opposite view. They state,2 that "the sclerometer (indicating scratch

Jan 1, 1924

By Phillip B. Bucky, R. S. Taborelli

The term "longwall mining" is best known to coal men, although modifications of the method are continually being used in other fields. Longwall mining is of interest today because it makes for greater inechanization and better supervision at the working face, and therefore lower production costs and increased safety. It is an approach to the factory system of production, the high efficiency of which as compared to that in mines is well known. There is available an accumulation of experience regarding this work but coordination of experience is lacking and this series of experiments was undertaken to help serve this purpose. Model experiments were used for reasons of safety, cost and time, and because it has been previously shown1,2,3 that a scalar inodel built of the same material as the prototype will behave in a manner similar to that of the prototype, with time effects the same, if the effective weight of the model is increased in the same proportion as its linear dimenbions are decreased. This is accomplished by substituting a centrifugal for the gravitational field; i.e., placing the model in a centrifuge and controlling the strength of the centrifugal field by varying the rate of rotation. Many factors affect the behavior of the geologic material overlying a bed, therefore results and conclusions contained in this paper apply only to the conditions presented herein. Longwall Mining What Is Longwall Mining?—Agreement should be reached as to what constitutes longwall mining and therefore what constitutes a longwall face. Let longwall mining be defined as the mining procedure in which the roof and overlying bed breaks tend to parallel the working face. In the ordinary stope or room-and-pillar mining the roof breaks tend to

Jan 1, 1938

By Phillip B. Bucky, R. S. Taborelli

The term "longwall mining" is best known to coal men, although modifications of the method are continually being used in other fields. Longwall mining is of interest today because it makes for greater inechanization and better supervision at the working face, and therefore lower production costs and increased safety. It is an approach to the factory system of production, the high efficiency of which as compared to that in mines is well known. There is available an accumulation of experience regarding this work but coordination of experience is lacking and this series of experiments was undertaken to help serve this purpose. Model experiments were used for reasons of safety, cost and time, and because it has been previously shown1,2,3 that a scalar inodel built of the same material as the prototype will behave in a manner similar to that of the prototype, with time effects the same, if the effective weight of the model is increased in the same proportion as its linear dimenbions are decreased. This is accomplished by substituting a centrifugal for the gravitational field; i.e., placing the model in a centrifuge and controlling the strength of the centrifugal field by varying the rate of rotation. Many factors affect the behavior of the geologic material overlying a bed, therefore results and conclusions contained in this paper apply only to the conditions presented herein. Longwall Mining What Is Longwall Mining?—Agreement should be reached as to what constitutes longwall mining and therefore what constitutes a longwall face. Let longwall mining be defined as the mining procedure in which the roof and overlying bed breaks tend to parallel the working face. In the ordinary stope or room-and-pillar mining the roof breaks tend to

Jan 1, 1938

By D. E. Wolfson, H. J. Gluskoter, M. R. Geer, John A. Harrison, H. F. Yancey, I. S. Latimer

When this chapter was prepared for the kst edition in 1942, continuous mining machines virtually were unknown, and hand loading in underground mines, which gave an opportunity to discard impurities, accounted for 55 percent of the production of bituminous coal and lignite as compared with the 1965 figure of 11 percent. Only 24 percent of the total production was cleaned mechanically, compared with the present (1965) figure of 65 percent. The amount of refuse discarded during preparation for the same period increased from 13 to 21 percent. Changes in the equipment used in the cleaning process were as follows: [ ] Unclassified nearly 8 percent. Data on the amount cleaned by flotation was not collected until 1960 when 1.8 million net tons was so treated. In 1965 this figure increased to 6.9 million tons. Although the great increase in mechanization and full seam mining has resulted in substantial increases in the impurity content of the raw coal as well as in a finer size consist, some phases of face preparation are still important, particularly the variability of the distribution and thickness of the interbedded impurities and the changes in the character of the roof and floor from place to place in the mine. Knowledge of these factors in relation to all phases of the mining operation, particularly selective mining, are still of importance to the treatment of raw coal in the preparation plant. The major characteristics of coal and impurities from the standpoint of mechanical cleaning are particle size composition, generally called size consist, density differences, the relative friability of the coal and of its associated impurities, hardness, and strength. Some of the other factors related to preparation are petrographic composition and rank. COAL PROPERTIES Rank Perhaps 95 percent or more of the coal cleaned mechanically is of bituminous rank. Only a very small tonnage is subbituminous and prac-

Jan 1, 1968

By O. H. Eschholz

The electrostatic process of fume precipitation is an excellent example of the successful application of scientific knowledge to an industrial operation. Originally proposed for the precipitation of sulfuric acid mists, it has been extended until at present there is practically no fume-carrying gas to which the method cannot be applied. Among the more common applications are: the recovery of non-ferrous smelter flue-dust, iron blast-furnace dust, cement dust, and potash fume. It should be borne in mind that the process is restricted to the precipitation of suspended particles, either liquid or solid, and does not separate gaseous constituents. However, by proper temperature control, mixtures of vapors having different temperatures of condensation to either solids or liquids may be selectively precipitated. The process consists essentially of subjecting suspended particles, including those too minute to be effectively acted upon by centrifugal or gravitational forces, to such an electrical force that they are driven from the gas stream, acting as a conveyer, and deposited upon a suitable receiving surface. This directional impulse is obtained from the interaction of charged particles and an electrostatic field of definite intensity gradient existing between two dissimilar electrodes, known as discharge and receiving electrodes. In principle, the equipment is equally simple. As shown diagrammatically in Fig. 1, it consists of: (1) A source of high-potential direct, current,, requiring: (a) Source of alternating-current energy. (b) Means of transforming from low voltage to high voltage. (c) Means of converting alternating to direct current. (2) Precipitation chamber having: (a) Transmission tubes for fume-laden gases. (b) Suitably designed and disposed electrodes. (c) Means for affecting removal of deposited solids. Although Hohlfeld demonstrated, in 1824, that a smoke-laden atmosphere could be cleared by applying an electrostatic field, and while Sir

Jan 1, 1919

By W. C. Snow

The plant of the Electrolytic Zinc Company of Australasia Limited, situated at Risdon on the estuary of the River Derwent, near Hobart, was designed and erected primarily to produce high-grade zinc from zinc concentrates produced by the mines of Broken Hill, N. S. W. Consequently the metallurgy of the process has been influenced in its development by the peculiar characteristics of the Broken Hill concentrate, which on treatment gives into solution relatively large amounts of cobalt, manganese and silica. The Risdon works (Fig. 1) produces high-grade electrolytic zinc, leaded electrolytic zinc, zinc dust, cadmium, sulphuric acid and superphosphate. This paper, however, is concerned only with the zinc plant and process. Roasting The roasting of raw concentrate is not a major feature of Risdon's process, and in this respect practice is unlike that of most zinc plants. The roasting is mostly done on the Australian mainland at centers where the sulphuric acid made from the roaster gases can be used for superphosphate manufacture. A small amount, approximately 40 tons per day, is roasted at Risdon, acid being manufactured from the gases. The amount that can be roasted there is limited by the acid requirements of the zinc plant and of the superphosphate plant. Roasting is not carried to completion at the mainland plants, and the product, known as preroast calcine, largely constitutes the raw material for the Risdon zinc plant. It contains about 6 per cent of sulphur as sulphide. Roasting is completed at Risdon for reasons that are set out later in this paper. The zinc plant proper is divided into four main divisions: (1) final roasting division, (2) leaching and purification division, (3) electrolytic division, (4) melting and casting division. There are two subsidiary divisions—the cadmium division and the preroast, acid and superphosphate division.

Jan 1, 1937

By R. B. Woodworth

INTRODUCTION IN the sinking of bore holes, there are but two fundamental operations -drilling and hoisting,-which determine in the main the character of drilling mechanism and structures. There are endless ramifications, however, in the execution of these fundamental operations, according to the purposes for which the bore holes are drilled, their maintenance after completion, the protection and convenience of workmen, etc. The three main lines of use for bore holes are in mineral exploration, the sinking of water and salt wells, and the exploitation of petroleum and natural gas. This paper has to do more especially with the last. Here again there are many divergences. Wells may be drilled by either the percussive, the hydraulic, or the abrasive method. Finally, each of these methods, as applied by drillers of diverse nationalities, has followed somewhat different lines of development. The American system of cable-tool drilling has perhaps had the widest application; the hydraulic rotary is also in extensive use; but the Canadian system, the Galician system, and the Russian free-fall system all have their points of recognized merit and are preferred by operators accustomed to their use. These differences in drilling procedure, which rest ultimately on essential variations in geological conditions, are reflected in the chilling structures as well as in the drilling mechanism. The purpose of the present paper is to record those stages in the development of the application of steel to the construction of drilling mechanism and structures with which the writer has been intimately associated, and to contribute to the history of the art of drilling other data acquired in the course of his personal investigations. It is necessarily limited by reason of space to American practice, with especial reference, therefore, to the cable-tool system and the hydraulic rotary method of drilling wells for oil and gas.

Jan 11, 1915

A Little Book on the Assaying of Gold, Silver, Copper, and Lead. Also on How to Assay and Work profitably All Minds of Metal. Complied with great care for the benefit of all mintmasters, assay masters, gold= smiths, miners, and dealers in metals.

Jan 1, 1949