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By J. E. Elliott, K. O. Miller

Solubility studies were carried out to establish the phase distributions for various Fe-Ni-Pb-C alloys at temperatures where the metallic components exist as liquid solutions. Temperature us composition diagrams for the Ni-Pb, Fe-Pb, Fe-Ni-Pb, and Ni-Pb-C systems are derived by employing various approximations in conjunction with the data. Results are summarized for 1550°C in a quaternary phase diagram of the Fe-Ni-Pb-C system. BECAUSE surprisingly little information has been published on the phase diagrams of the Ni-Pb, Fe-Pb, Fe-Pb-Ni, and Fe-Ni-Pb-C systems, a study of these systems was undertaken to ascertain the important phase relationships in the temperature range of 1300" to 1550°C. Measurements were also made on the carbon-saturated systems in the hope that they would assist in the interpretation of the systems without carbon. This paper reports the results obtained from the simple equilibration of the various liquid and solid phases. EXPERIMENTAL PROCEDURE The experimental technique involved holding appropriati quantities of the metals in an alumina crucible, or in a graphite crucible when saturation of the melt with carbon was desired, for sufficient time at the desired temperature to ensure equilibrium. Then a sample of each liquid phase presen was drawn into a small-bore silica tube. This sample was withdrawn quickly from the furnace, cooled, and sent to the chemical laboratory for analysis. The cell assembly used is shown in Fig. 1. Durin the work on the Fe-Pb-Ni system, it was placed in a furnace wound with 20 pct Rh-80 pct Pt wire. This furnace eventually failed and subsequent studies were carried out between 1350" and 1475°C in a tube furnace heated by silicon-carbide resistance elements. A protective atmosphere of argon with approximately 10 pct hydrogen was supplied to the cell assembly at a gage pressure of 1 in. of water. Hydrogen was passed over palladized alumina and then anhydrous calcium chloride for purification. Argon was purified of oxygen and water vapor by passing it over copper gauze at 550°C and then through a calcium chloride drying column. The gases were mixed and redried before they entered the equilibration cell. Temperature was measured by calibrated Pt/Pt-10 pct Rh thermocouples and a Rubicon Type B potentiometer. The thermocouples were standardized against the melting points of pure nickel

Jan 1, 1961

By W. N. Tanner

THE wire-rope hoisting conditions at the mines of the Anaconda Copper Mining Co. in Butte, Mont., are very severe because of the conditions under which it is necessary to operate. A study was made, in the fall of 1919, for the purpose of changing these conditions in order to obtain longer rope and sheave life. There are at present in Butte, hoisting engines equipped with wire rope as follows: 9 main hoists using flat ropes. 7 main hoists using 1 ½ in. rope. 5 main hoists using 1 ¼ in. rope. 6 shafts using 1 1/8 in. rope. 2 chippy hoists using 1 ¼ in. rope. 9 chippy hoists using 1 1/8 in. rope. 15 shafts using 1 in. rope. 7 shafts using 7/8 in. rope. 1 shaft using ¾ in. rope. In addition, there are a number of sinking engines using 5/8 in., ¾ in., 7/8 in., and 1 in. (15.9, 19, 22, and 25 mm. rope.) The flat ropes run from ½ by 7 ½ in. (12.7 by 190.5 mm.) to ½ by 4 ½ in. (9.5 by 114 mm.) and are used on the older hoisting-engines, which are set comparatively close to the shaft. Because of swelling and moving ground at some of the shafts, these ropes present certain difficulties in operation that are more pronounced than with round ropes; they are, therefore, being superseded by round ropes as newer engines are being installed. They are, however, much more easily inspected and repaired than round ropes.

Jan 2, 1922

Lake Superior Meeting . PAGE Gathmann, Emil.-Casting and Molding Steel Ingots. Discussed by J. W. Richards.. 2 McCaffery, R. S.-The Acid Bessemer Process. Discussed by Bradley Stoughton, J. W. Richards 3 Elliott, S. R.-Athens System of Mining. Discussed by F. W. Sperr, Lucien Eaton 4 Mercer, H. T. and Paulson, A. C.-Handling and Treatment of Rock-drill Steel at Copper Range Mines. Discussed by Harrison Souder, H. T. Mercer, W. H. Schacht, C. M. Haight 5 Hayden, J. E. and Eaton, Lucien.-Building Reinforced-concrete Shaft Houses. Discussed by William Kelly, T. L. Condron, Lucien Eaton 7 Eaton, Lucien.-Mechanical Ventilation at Lake Mine. Discussed by C. A. Mitke 8 Schacht, W. H.-Steam Regenerators Reduce Coal Consumption. Discussed by 0. P. Hood, W. H. Schacht ? 9 Linton, Robert.-Standardizing at North Butte Mining Co. Discussed by Grant H. Tod, C. A. Mitke 10 Smith, H. DeWitt and Sirdevan, W. H.-Mining Methods and Costs at United Verde Mine. Discussed by C. A. Mitke 12 Davy, Myron A.-Reflecting Microscope for the Mining Engineer. Discussed by C. P. Berkey, W. A. Rukeyser 14 , Norden, J. A. and Willson, A. R.-Hoisting Equipment at Utah-Apex Mining Co. Discussed by E. M. Norris 17 Aldrich, H. R.-The Dip Needle in Stratigraphy. Discussed by H. R. Aldrich, W. 0. Hotchkiss, Carl Zapffe, E. A. Kronquist 18

Jan 1, 1921

By D. M. Metcalf

MOST PEOPLE think of peat as an inferior substitute for coal as a fuel, and will be surprised to learn that it is extensively mined in this country for use as fertilizer rather than as a fuel. Some years ago the Florida Humus Co. began producing it at Zellwood, Orange County, Fla., in a small way for local use. When, however, the company secured an Institute member, M. H. Cuise, to apply his wide experience in mining to the problems here it was found possible to decrease production costs 70 per cent and increase output tenfold. The obvious way in which to decrease costs was to replace shovel-and- horse methods with machinery, much of which, in order to keep down-invested capital, was improvised by remodeling second-hand equipment, changing the design where necessary to meet the special conditions involved.

Jan 1, 1932

By D. J. Hawthorn

The widespread interest shown during the past year in the study of subsurface pressures warrants brief reference to its early development. Though it is impossible to set an exact date when constructive thinking on the subject first began, nevertheless, evidence is available that thought was given to the problem as far back as 16 or 1.7 years ago. There is record in one of the foreign journals of actual subsurface tests made by crude methods in one of the Rumanian fields in 1918 and 1919.' These tests were performed in conjunction with studies made on wells produced by bailing and, incidentally, the final outcome of the work led to the development of the so-called "duplex bailer" which is reputed to have trebled volumetric bailing efficiency. From this time on to 1927 a few scattered bottom-hole pressure determinations were made with makeshift instruments of one form or another, but probably not until 1927 was any great amount of concerted effort directed to the subject. At this fall meeting of the Petroleum Division four years ago was presented one of the first papers2 to appear in this country written for the express intent of advocating the value and importance of subsurface pressure determinations. It is thought to have been the first to present direct data on subsurface pressures obtained through the use of a specially designed recording instrument. As might be expected, the instrument had its limitations, but reasonably accurate results were obtained and, to say the least, it constituted a progressive step in the right direction. During the period from 1927 to 1931, many noteworthy improvements were made in the design and perfection of subsurface pressure instruments suitable to meet all conditions. Because of the magnitude of this task much credit is due the men who pioneered this work. They should feel a keen sense of satisfaction in the thought that their efforts have paved the way for the continuation of this most valuable study. At the present time more than a dozen companies are operating subsurface pressure instruments in the Mid-Continent field. Engineers in

Jan 1, 1933

By R. E. Phelan

WHILE 1931 was a most important year in the history of Canadian copper smelting and refining, nevertheless, due to the low price of copper and the in- ability of the International Nickel Co. to market its full capacity of nickel. the production of both copper and nickel was considerably less than the total installed capacity for the production of these metals. IIY the nor- mal course of events, 1931 should have seen a great increase in the production. of both copper and nickel in Canada, because the large extensions to both the copper smelting plants and the copper and nickel refinery capacity, which had largely been completed in the year 1930, should be showing their effect.

Jan 1, 1932

Jan 1, 1961

By P. A. Tucker, C. R. Hudgens, D. E. Etter, D. L. Roesch, D. B. Martin

The equilibrium phase diagram of the Pu-Cd system is presented based on data obtained by differential thermal analysis, metallography, and electron-microprobe X-ray analysis. Liquidus temperatures range from 320° to 934°C. The system contains one congruently melting compound, PuCd, (945°C), and three incongruently melting compounds, PuCd, (800°C), PuCd, (730°C), and PuCd11 (410°C). A liquid-miscibility gap extends from 2 to 60 at. pet Cd with the monotectic reaction isotherm at 910°C. INTEREST in the potential use of plutonium alloys as reactor-fuel materials has prompted investigation of the phase equilibria in plutonium binary systems. A cursory investigation of the phase equilibria in the Pu-Cd binary system was conducted by differential thermal analysis (DTA), metallography, and electron-microprobe X-ray analysis (EMX). Extensive solid solubility of cadmium in both e and 6 plutonium was predicted1 based on atomic radii and electronegativities. Liquid immiscibility between these two elements was also predicted based on Mott's extension of Hildebrand's method. In the only previous investigation of the Pu-Cd system,2 two intermetallic compounds, PuCd11 (incon-gruent melting point 406°C) and PuCd8, were identified. EXPERIMENTAL The plutonium metal used in this work had a total impurity content of 500 ppm; the major impurities were: carbon (215 pprn), silicon (75 ppm), iron (60 ppm), nickel (40 ppm), and aluminum (25 ppm). The cadmium was reagent grade with a purity of 99.99 pet. The DTA technique for the study of plutonium alloys was previously described in detail.3 The alloys to be studied were prepared in tantalum DTA specimen capsules which were sealed by inert-gas welding. The alloys were homogenized in the liquid state in these sealed capsules which prevented the loss of cadmium by vaporization. Only the thermal arrests in the DTA heating curves were used to define the transformation temperatures of the system since supercooling affected many of the results during cooling. After the alloys were analyzed by DTA, the same alloys were used for the metallographic studies. Metallographic examinations were conducted in the manner described for plutonium alloys., No reaction was detected between the alloys and the tantalum capsules. Alloys for EMX analysis were placed in metallographic mounts together with specimens of unalloyed plutonium and cadmium which served as standards. The samples were highly polished but unetched. No protective coatings were applied to the surfaces of these radioactive specimens. Such coatings are detrimental to the excitation conditions and have been found to be unnecessary for the control of radioactive contamination. RESULTS The results of the DTA studies are presented in Table I. The phase diagram, constructed from these data plus the metallographic and EMX results, is presented in Fig. 1. The congruently melting compound, PuCd2, was identified by the occurrence of a maximum melting point (945°C) at 33.3 at. pet Pu-66.7 at. pet Cd and by the presence of a single phase in this composition.

Jan 1, 1965

Committee on Reduction and Refining of Copper............ 3 A.I.M.E. Officers and Directors.................... 4 Preface. By C. R. Kuzell....................... 7 Career and Achievements of James Douglas. By Arthur L. Walker. . 9 PAPERS Smelting 1. Reverberatory Smelting Practice History of Reverberatory Smelting in Montana, 1879-1933. By Frederick Laist..............................23 Reverberatory Smelting of Raw Concentrates at the International Smelter, Miami, Arizona. By P. D. I. Honeyman (With Discussion)...... 88 Development of Gun-feed Reverberatory Furnaces at Garfield Plant of American Smelting and Refining Company. By R. A. Wagstaff (With Discussion)........................99 An Experimental Combination of Shaft Roasting and Reverberatory Smelting. By Frederick Laist and J. P. Cooper (With Discussion).... 104 Forms of Copper Found in Reverberatory Slags. By Royal B. Jackman and Carle R. Hayward (With Discussion).............111 2. Converting Practice Development of Copper Converting at Butte and Anaconda. By William Kelly and Frederick Laist...................122 Developments in Converting Lead and Copper Matte at Tooele. By B. L. Sackett.............................132 Messina Stationary Basic Copper Converter. By R. G. Knickerbocker (With Discussion)........................140 Smelting Copper Concentrates in a Converter. By George E. Beavers. 149 Sulfuric Acid from Converter Gases. By George E. Beavers......151 Development of Monolithic Tamped Periclase Converter Linings at United Verde Copper Company Smelter. By F. H. Parsons (With Discussion) . 153 3. Descriptions of Plants The Noranda Smelter. By W. B. Boggs and J. N. Anderson......165 Smelting Operations at Roan Antelope Copper Mines, Limited. By Charles R. Wraith.......................202 4. Waste-heat Boiler Practice Copper-refinery Waste-heat Boilers at Great Falls Reduction Department, Anaconda Copper Mining Company. By E. S. Bardwell......225

Jan 1, 1934

SAN FRANCISCO SECTION Roy H. ELLIOTT, Chairman - T. A. RICKARD, Vice-chairman W. H. SHOCKLEY, Secretary-Treasurer, 959 Waverley St., Palo Alto, Cal. D. A4. RIORDAN C. F. TOLMAN, JR. A joint meeting of the local sections of the several national engineering societies represented in San Francisco was held at the Engineers'. Club on Thursday evening, Sept. 26, 1918. The subject for the evening, "Fuel Conservation," was ably discussed by a-number of representatives of the Federal Administration and by engineers interested in the generation and utilization of all kinds of power on the Pacific Coast. The following extracts from papers presented at this meeting have been selected as being of the greatest interest and value to members of this Institute. Problems of the Fuel Administration ALBERT E. SCHWABACHER.-America's war needs call for 100,000,000 more tons of coal this year than in 1917, and 200,000,000 tons more than in 1914, when the war started, and this increase must come from a weaker man-power than that of 1917. It must be transported by a railroad system that has not been improved since the war started, and has been burdened with inconceivably greater demands than were made upon it before the war. This tremendous increased demand must be met by most intensive work in three directions; increased production, efficient conservation, and a distribution system which will insure against lost motion. While every European country has decreased its coal production since the war began, the United States has mined 50,000,000 tons more coal, during the first year of the war, and will increase this by another 50,000,000 the present year. Every 8 days there are being mined and transported as great a weight of coal as of the entire wheat crop of the United States. Of the 735,000,000 tons of coal which must be made available for consumption by our railroads, ships, war industries and people, 100,000,000 tons will come from the anthracite fields, the remainder from the bituminous fields. In 1917 there were produced about 330,000,000 bbl. of oil, and this year an additional amount over last year's production, of approximately 23,000,000 bbl. will be required. Water power developed 5,000,000 hp., the demand greatly exceeding the available supply.

Jan 12, 1918

By T. L. Joseph

IT is a distinct privilege to participate in this meeting convened to honor the memory of Henry Marion Howe, a distinguished scientist and metallurgist. Many have added to our rapidly growing fund of metallurgical knowledge but few have made the unique contribution of formulating basic concepts essential to an over-all comprehensive view of the subject of metallography. Of those previously selected to deliver this lecture, several have added a personal touch to their discourse because they were able to refer to their associations with Dr. Howe. It was not my good fortune to know him or to enjoy his inspiring influence. Like most of you, my contact has been with his published works, which are outstanding in that they provide lucid, detailed expositions of the nature and behavior of metals and alloys. His deep understanding and clarity of expression have greatly accelerated our progress in metallography and in the use of metals. The degree to which a man's thinking, experimentation and writing contribute toward an understanding of basic laws and phenomena determines whether his life's work is of transitory or permanent value. This occasion appropriately recognizes the fundamental importance of Dr. Howe's pioneer work in the field of metallurgy. On two former occasions, gray iron was selected as a subject for discussion. The fact that the production of pig iron has not been discussed before does not reflect any lack of interest on the part of Dr. Howe or former lecturers in the process that under- lies the production of steel. Although Dr. Howe's work in his later years centered around metallography, his earlier publications show a considerable interest in the production of iron and steel. He recognized that in the ascending spiral of metallurgical advancement we are not winding a single thread but are weaving a complex fabric. Specific evidence of his interest in the production of pig iron may be found in his book1 on The Metallography of Cast Iron and Steel. In explaining why blast furnaces have been in constant use for about 600 years, he says: "The process is economical because it utilizes with extraordinary completeness the calorific power of the coke due to the thorough transfer of heat from the gaseous products of combustion to the charge." This emphasis on heat transfer, overlooked in many more extended and more recent discussions of the blast-furnace process, illustrates Professor Howe's ability to see the essentials. Other distinct advantages of the blast furnace, such as the removal of much of the sulphur and practically all of the oxygen, were mentioned. It was also stated that although the blast- furnace process is complex in nature, its outward form is comparatively simple, thus permitting large-scale production at small labor costs. All who contemplate the production of metallic iron from its ores by any other process might well consider the

Jan 1, 1946

By Robert P. Koenig

FOR the first time other than on occasion of war the people of the United States are experiencing full-scale participation in world affairs. Public concern has seldom been so involved with conditions and events beyond our own continental limits. Our interest is not wholly of recent origin. Over the years the activity of the United States as a world power and an important trading nation brought about the widening of our political interests and the progressive interrelation of our economy with that of the rest of the world. Some may see in our present phase of world-wide activity the natural consequence of our continued growth. Such observers must also be aware that within recent years our importance in world affairs has been considerably increased. For within the space of an extremely short period events have occurred that have literally jet-propelled the United States into the role of a leading participant in the conduct of world affairs. Little of the choice of this role was left to us. The decline of power in western Europe, the ascendancy between the Elbe and the Pacific shore of an obviously antagonistic force, our earnest endeavor to secure international control of atomic energy, the necessity of providing relief and rehabilitation to war-ravaged areas, and the police work that must be done in occupied territories are problems which have risen in great measure without our help-but they cannot be solved without it.

Jan 1, 1948

By Frank G. Norris

Slag control is adjustment of the composition of the slag, especially with respect to the FeO content. The theoretical method of slag control would be to charge a mixture of pig iron and scrap of given composition into the furnace, to melt always at the same carbon, and, after a uniform ore addition, to tap with a constant slag composition. Such conditions are not even approximated. Both scrap and pig iron are of variable, and, in many cases, unknown composition. The charge is oxidized to a variable extent during melting. The result is that the FeO content of the slag, and consequently of the metal at tap, varies over a wide range. In order to make a nearly uniform product, this variation must be compensated for in some way. One way is to adapt the ladle deoxidation to the requirements of the metal. The other is to control the slag. In a general sense slag control may be considered as a method of compensating for variations in the composition of the charge and in oxidation during melting. The method of slag control for low-carbon steel was developed by Dr. Herty at our Butler plant3. Use of this method enables the furnace operator to tap heats at a more nearly constant FeO content and, therefore, to use a more nearly uniform deoxidation practice. The desired FeO and the accompanying deoxidation will depend on the application of the product. This statement implies that 0.10 carbon steel finished with a 15 FeO slag may be essentially different from a 0.10 carbon steel finished with a 30 FeO slag. In making low-carbon steel, the desired carbon places a lower limit on the FeO content of the slag, because the slag must be sufficiently oxidizing for proper carbon elimination. With this degree of oxidation, the phosphorus specification is met without difficulty, and there is little danger of phosphorus reversion. Thus a limiting factor in high-carbon heats is of slight importance in low-carbon heats. For heats of 0.05 to 0.07 per cent carbon, the FeO content of the slag may be controlled at

Jan 1, 1935

By Frank G. Norris

Slag control is adjustment of the composition of the slag, especially with respect to the FeO content. The theoretical method of slag control would be to charge a mixture of pig iron and scrap of given composition into the furnace, to melt always at the same carbon, and, after a uniform ore addition, to tap with a constant slag composition. Such conditions are not even approximated. Both scrap and pig iron are of variable, and, in many cases, unknown composition. The charge is oxidized to a variable extent during melting. The result is that the FeO content of the slag, and consequently of the metal at tap, varies over a wide range. In order to make a nearly uniform product, this variation must be compensated for in some way. One way is to adapt the ladle deoxidation to the requirements of the metal. The other is to control the slag. In a general sense slag control may be considered as a method of compensating for variations in the composition of the charge and in oxidation during melting. The method of slag control for low-carbon steel was developed by Dr. Herty at our Butler plant3. Use of this method enables the furnace operator to tap heats at a more nearly constant FeO content and, therefore, to use a more nearly uniform deoxidation practice. The desired FeO and the accompanying deoxidation will depend on the application of the product. This statement implies that 0.10 carbon steel finished with a 15 FeO slag may be essentially different from a 0.10 carbon steel finished with a 30 FeO slag. In making low-carbon steel, the desired carbon places a lower limit on the FeO content of the slag, because the slag must be sufficiently oxidizing for proper carbon elimination. With this degree of oxidation, the phosphorus specification is met without difficulty, and there is little danger of phosphorus reversion. Thus a limiting factor in high-carbon heats is of slight importance in low-carbon heats. For heats of 0.05 to 0.07 per cent carbon, the FeO content of the slag may be controlled at

Jan 1, 1935

By G. C. Trevorrow

STRIP mining during 1943 increased considerably with further extension of mechanical loading in mines already partly mechanized; with the considerable introduction of mechanical loading into hand-loading mines; and with improvements in the use of loading equipment. Extension of the use of machinery both in strip mining and underground is due to reduction in labor supply and increased cost of labor, together with the increased demand for coal during the period of labor shortage.

Jan 1, 1944

By William B. Plank

A NEW record-a quarter million students in the engineering schools of the United States and Canada-has resulted from the great demand for engineers following World War II. The figures released by the American Society for Engineering Education and which appeared in detail in the Journal of Engineering Education for January 1948, show that, on Nov. 1, 1947, 252,250 students were studying engineering in 149 engineering schools of both countries. There are 244,390 in the 143 schools canvassed in the United States, and 7860 in six schools in Canada. These figures include both undergraduate and graduate students and are therefore comparable with the figures in previous presentations on this subject. This unprecedented engineering student body

Jan 1, 1948

By Larry Kaufman

A useful method for estimating the entropy of NaCl type compounds has been developed by combining the Debye theory of specific heat with the Lindemann formula. This method pemnits calculation of the entropy from a knowledge of the atomic weight, atomic volume, and melting point of the compound. Comparison of the calculated and observed entropies of 35 NaCl type compounds over a wide temperature range yields good agreement thus establishing the usefulness of the method. Application of the method to other crystal types is also discussed. KUBASCHEWSKI~ has suggested a useful method of estimating the enthalpy of formation of inter-metallic compounds from a knowledge of the crystal structure, lattice parameter, and heats of sublimation of the component elements. This method is quite valuable in predicting the tendency for compound formation in a given system and is of particular value in considering systems for which no experimental data are available. In order to supplement the enthalpy calculation afforded by Kubschewski's method, it would be of value to be able to estimate the entropy of compounds so that the entropy and free energy of formation could be evaluated. Although a considerable body of such data determined by calorimetric and equilibration techniques exists at present, the difficulty of making such measurements (particularly at high temperatures) and the ever increasing number of new compounds which are of interest make the desirability of such a computational method clear. This paper deals with a method for calculating the entropy of a compound from a knowledge of the atomic weight, atomic volume, and melting point. Since these data are generally easier to determine and therefore more readily available than thermo-dynamic data, they should provide an additional tool in estimating the stability and reactivity of compounds at high temperatures. I) THE ENTROPY OF PURE METALS As a first approximation, the specific heat of a pure metal can be represented by a sum of terms where C,($/tI is the vibrational specific heat calculated on the basis of the Debye theory, lo4 TC, (0/T) is an approximation to the Cp - C, correction. T is the electronic specific heat, and Cp (p) is the magnetic specific heat. Although the Debye theory does not provide a complete description of the vibrational specific heat, i.e., the Debye temperature 0 is not a constant, it does provide a good approximation when used properly. Blackman6'7 has written several reviews on this subject discussing the different values of 0 determined by various methods (specific heat, X-rays, elastic constants, electrical resistivity, and so forth), as well as the observed temperature dependence of 0 with T. In the present case the 0 in Eq. [I] naturally refers to the specific heat 0. The variation of Debye 0 (as determined from specific heat measurements) with temperature is observed to exhibit its most radical behavior at very low temperatures. At higher temperatures the 8 values are observed to become more nearly constant. Blackman6'7 has presented the variation of 0 with temperature for several metals. His tabulation is reproduced in Table I. Reference to Table I shows that above a certain temperature level, 0 remains fairly constant. The value of 0 which is most useful in computing the specific heat, and hence the entropy, is the value of 0 in the range 0/6 « T « 0. In 1910, Lindemann' suggested a relation for estimating Debye 0 values. According to this formula, where V is the atomic volume, T is the melting point in 'K, M is the atomic weight, and CL is a constant. Mott and Jones9 present this formula and state that there is at present no satisfactory theoretical explanation, but that it does have an empirical basis. By using the valuesof 0 in Table I along with known1' values of M, T, and the molar volume VM, where the Lindemann constant can be evaluated. This

Jan 1, 1962

By Herbert W. Huse

Nitrogen, and its compounds, unique among the materials described in this volume, is absolutely essential to the existence of the human race. Almost all minerals are important and the absence of any one of them would be sorely felt; but nitrogen is an integral part of the cycle of life itself. Man cannot live without nitrogen which, as an inert gas, composes the major part of the air he breathes; as compounds, nourishes the vegetation which he eats; and, as protein, forms a part of his very flesh and blood. Nature originally provided man with a vast reserve of usable nitrogen compounds in the form of fertile soil. She constantly replenishes the supply by "fixing" nitrogen in the air at the estimated rate of 400,000,000 tons per year (an insignificant 6 lb per acre) during electrical storms. She has also placed certain microorganisms in the soil which are able to "fix" nitrogen and convert it into forms which plants can use. Legumes like cow peas, soy beans, clover, and alfalfa have extraordinary roots which serve as stimulating hosts to these bacteria which, in turn, nourish the plant. By plowing in all or part of such crops, their above-average nitrogen content can be returned to the soil for other more useful crops. The mechanism for this recycle is supplied by "denitrifying" bacteria which attack the dead plant tissue and liberate nitrogen and ammonia. However, since one crop of grain, sugar beets, potatoes, tomatoes, etc., takes out a major portion of the nitrogen which a plowed-in legume crop can supply, this method of fertilization is obviously inadequate. Drastic intervention by man has become necessary to support the ever-growing population of the world.9,15,20 Old civilizations with a high population density, such as the Chinese, were able to exist for centuries by carefully tilling the soil, rotating crops, and returning to the soil all the nitrogen in vegetable wastes plus human and animal excreta. But the lack of a means for augmenting their supply of nitrogen placed a ceiling on further development and kept the mass of the population in a chronic state of undernourishment, frequently punctuated by famine. Nitrogen plays another important role in the life of mankind. In the form of explosives, nitrogen helps to wrest from the earth many materials needed for our material well-being. Also, in the form of explosives and propellants, nitrogen increased the destructiveness of wars to a point only exceeded by the fantastic power of atomic energy. Man's first really effective efforts to improve his position with respect to nitrogen began in the 18th Century with the mining of sodium nitrate. By the late 1880's this had become a big industry serving a large part of the world. In the late 1890's nitrogen, in the form of ammonia, was being recovered from coke-oven operations. In 1900 nitrogen, in the form of nitric oxide, was being obtained from the air by an electric-arc process. About 1904 another "fixation" process based on the reaction of nitrogen with calcium carbide to form cyanamide was commercialized. By 1913 the Haber-Bosch process of "fixing" atmospheric nitrogen by reacting it with hydrogen to produce synthetic ammonia was successfully applied on a large scale, first in Germany and then throughout the industrial areas of the world.9 All the above methods of obtaining nitrogen compounds are still in use and, between them, they assure mankind of adequate supplies for all time. While this fortunate situation is not unique amongst industrial raw materials, all too few of man's needs are so well in hand.

Jan 1, 1960

By Louis D. Huntoon

SHORTLY after publication of the article in the July, 1924, issue Of MINING AND METALLURGY, entitled "Canada as a Gold Producer," requests were received to determine the ownership of production. Advices have also been received that considerable discussion has taken place on the same questions both in Canada and Great Britain. The author is indebted to R. H. Coates, Dominion Statistician, and George C. Bateman, Secretary, Ontario Mining Association, for the following figures and takes this opportunity of expressing his appreciation. There have been no statistics compiled as to ownership of production. Statistics were compiled as of Dec. 31, 1921 relative to the distribution of stocks, bonds and "other securi¬ties" in industrials, agriculture excepted, throughout the Dominion, and "distribution of ownership of securities issued by mining companies incorporated and operating in Ontario" for the same year. Stock registration does not necessarily represent actual ownership' as large blocks may be endorsed and not transferred; neither does registration actually represent production. When the charts are studied individually and collectively one cannot help but be impressed with the fact .that in the mineral industry of Ontario and the Dominion at large, Canadian registration predominates, the United States registration is about half that of Canada, and Great Britain is about half that of the United States. When the nickel-copper industry is excepted the British registration falls to a very low percentage. Since Dec. 31, 1921, British capital has commenced to flow into mining enterprises in Ontario and it has been already rewarded by the discovery of valuable ore deposits.

Jan 1, 1925

By H. H. Dreissen, F. J. Fontein

The operating principle of the classifying cyclone has been described often but some special aspects of the cyclone receive further clarification here. In addition, several uses of the classifiers are summarized and made clear by means of practical examples. In coal and ore washeries, the washing cyclone is widely used for the separation by specific gravity of sizes up to about 12 mm. This application has lately been extended to the separation by specific gravity of particles up to about 50 mm. This use makes special demands on the construction and wear resistance of the cyclone. The sieve bend, a development of the Dutch State Mines which is less well known than the hydrocy-clone, is dealt with at some length. The sieve bend is an apparatus designed for wet screening. Attention is given to the variables influencing the performance of the sieve bend. Hydrocyclones are now so widely applied that it would be difficult to find an industry not, directly or indirectly, using them or knowing how to use them since publications on this subject abound.1-3,5,9-11,13-15 However, because of the large number of variables influencing the operation of classifying cyclones, it is not entirely possible to calculate the results of this type of cyclone. Therefore, a number of lesser known variables will be discussed here along with some special applications of the classifying cyclone. FACTORS INFLUENCING CYCLONE CLASSIFICATION Shape of Particles: The shape of particles may cause a much coarser classification than the one expected, considering the sieve analysis and the cyclone dimensions chosen. This was clearly shown by feeding a mixture of spheres and disks in water into a cyclone. The spheres were 0.36 mm diam and the disks, 3 mm diam and 0.03 mm thick. These dimensions were chosen in order that the disks and spheres might have the same rates of fall under gravity. Both spheres and disks had a specific gravity of 1.05. The results obtained with these particles in a cyclone are summarized in Table I. Test No. 2 shows that the catch of spheres was

Jan 1, 1963