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By Harry V. Welch

This paper presents a brief discussion of numerous devices and processes which have been utilized for the recovery of values from gases in copper reduction works and describes in greater detail the development and application in recent years of electrical precipitation, more familiarly known as the Cottrell process, to the problems of dust losses with furnace gases in copper-smelting and refining plants. The field for collection of suspended particles in gases is widely extended in our modern complex, congested .and industrialized mode of living, and its satisfactory solution is required by our increasing appreciation of the extravagant waste, unhealthful effects and nuisance which such uncontrolled emission of solid suspensions represents. Much of the special dust-recovery equipment in use today has been developed in one industry and carried over to many others. The early work of Cottrell was with sulfuric acid mists, aimed at the purification problem in contact acid manufacture, but the present uses of Cottrell equipment cover a diversified field—carbon black, combustible gas, oil mists, iron blastfurnace fumes and dusts, cement-kiln gases, as well as the purification of gases in contact and chamber acid plants and its wide and extended use in the nonferrous metallurgical field of copper, zinc and lead, and their associated metals. Dust and fume collection from furnace gases became a problem only with the modern development of large and amply powered auxiliary furnace equipment, which in turn permitted large furnace units, fast driving and large outputs of finished product per unit of furnace capacity. The ancient metallurgist with his small clay pot and hand-operated bellows had too little gas velocity to cause a real dust loss. As furnaces grew in size, flues and stacks were added, and undoubtedly the first observable dust losses were indicated by the deposits in the flue and stack base. Large flues, it was noted, collected more than smaller ones, and the expansion of a portion of the flue into a chamber represented the first serious attempt at recovery of furnace dust losses. For a century or more the settling chamber represented the best of skilled metallurgical practice in recovery of furnace dust, and it may be said to have reached

Jan 1, 1934

By R. P. Heuer

In recent years an increasing amount of research work has been done on refractory materials for use in copper-smelting furnaces. A few of the larger refractories manufacturers have erected special research laboratories which are fully equipped to study the refractory problems of the smelter. A typical laboratory of this type was described in the January, 1929, issue of Mining and Metallurgy, in an article entitled "Methods of Research Newly Applied to Refractories," by W. F. Boericke. This particular laboratory is equipped for the manufacture of full-size refractory brick. It aims to study on a fairly large scale the behavior of various refractory raw materials and the effect of improved methods of manufacture. The refractories manufacturer has at his disposal the naturally occurring refractory oxides in various degrees of purity, mixed or combined with other oxides. In order to supply the copper smelter with a refractory brick that will permit the most economical operation of the smelting furnaces, it is necessary to have the optimum combination of a number of both physical and chemical properties in the brick. Unfortunately, nature has not provided any raw materials in which the perfect combination of these properties exists. It is, therefore, a problem for man's ingenuity to seek out the most desirable raw materials and develop methods of manufacture that give, in the resultant product, the necessary combination of properties in as full a measure as is possible. In the laboratory it is possible to carry out fairly broad experiments with this objective. It is first necessary to obtain and process the raw materials, then to manufacture them into brick and finally, to test these bricks under conditions designed to interpret or simulate in the laboratory the actual conditions in the smelting furnace. It is necessary for the research engineers to determine certain fundamental properties in the brick which may be subjected to laboratory measurements and to interpret these measurements in terms of brick performance in smelting-plant practice. Such procedure is not what might be called an exact, scientific one but it has been found that great progress can be made when these principles are applied. For example, the resistance of refractory brick to spalling and thermal change can be related to the thermal expansion of the refractory, its thermal conductivity and heat capacity and its

Jan 1, 1934

By John E. Lanning

During the last decade, since most smelters have included Cottrell plants as standard equipment for the removal of dust from furnace gases, it has become apparent that smeltermen have had a new problem slowly developing. This problem has manifested itself in accelerated destruction of, or serious injury to, the masonry of flues and chimneys. The masonry either spalls, if the material is of low strength, or acquires large major cracks, either of which conditions attains such proportions that renewals or reinforcing become necessary to maintain the structure in satisfactory condition. This paper describes the failure of a large modern brick chimney to such an extent that its safety was vitally impaired; the investigation of its condition; the methods of restoring satisfactory strength to the structure; and the installation of an acidproof lining. Plant History The Clarkdale smelter of the United Verde Copper Co., which was put in operation in 1915, was primarily a blast-furnace plant. The smelter at Jerome had utilized blast furnaces exclusively, and in the design of the new (1915) plant, blast-furnace smelting evidently was considered of major importance, the smelting equipment consisting of four blast furnaces 48 in. by 26 ft. 8 in. and three reverberatories, each 19 by 101 ft. The latter, supplemented by roasters, were intended mainly for handling dust and fine ore resulting from the crushing operations. The original roasting equipment consisted of six six-hearth Wedge roasters, six more being added in 1917. All gases from blast furnaces, reverberatories, roasters and converters were conducted by means of suitable flues and dust chambers to one central chimney. This chimney, 30 ft. inside diameter by 400 ft. high, is a self-supporting steel structure, lined with 4-in. brick supported on steel shelf angles, riveted to the shell, spaced about 15 ft. vertically. The bricks were of local manufacture, not particularly hard-burned, and were laid in ordinary cement-fireclay-sand mortar. No record is available to indicate that any particular effort was made to secure an acidproof mortar. The same materials were employed in the construction of the reverberatory and roaster flues, and the roaster dust chamber. Parenthetically, it may

Jan 1, 1934

By Fredrick Laist, J. P. Cooper

In the spring of 1931 an experiment was made at Anaconda with a small reverberatory furnace, with which was combined a roasting shaft. The arrangement is shown in the accompanying drawing (Fig. 1) and requires but little explanation. The general idea was to roast flotation concentrates, mixed with the proper fluxing materials, by dropping them down a heated shaft, from which the calcines would enter the smelting zone of the reverberatory furnace through an opening in the roof. The hearth of the reverberatory was 3 ft. wide by 21 ft. long. The roasting shaft was 3 ft. square inside and had an effective height of about 20 ft. The reverberatory furnace was arranged so that it could be charged either directly through the roof with regular hot calcines, in the usual manner, or by means of the shaft, at the top of which were a feeding arrangement by which cold flotation concentrates, suitably fluxed, could be fed continuously and a pipe through which cold air was blown in. Means were provided for distributing the feed over the cross-section of the roasting shaft. At first a mechanical arrangement was used but later it was found that a simple cone served the purpose equally well and gave less operating trouble. On account of the small size of the equipment, it was realized that absolute capacity and fuel consumption figures would mean but little. It was not to be expected that ratios comparable to those obtained in large furnaces could be gotten, and the only way in which any idea could be obtained as to the possibilities of the combination furnace was to run it in parallel with the reverberatory furnace charged in the usual manner and operating without the shaft. The results of such parallel runs are given in Table 1. The amount of oil burned in the reverberatory was purposely maintained at substantially the same rate during both runs in order that the benefits resulting from the shaft might be gaged. It was expected that the shaft would considerably increase the capacity of the reverberatory and that a better fuel ratio would be obtained on account of the high temperature at which the calcines would enter the

Jan 1, 1934

By R. A. Wagstaff

The method of charging a reverberatory furnace has changed many times since smelting was introduced in this country from the old smelters of Swansea, England. The cause of the latest change at the Garfield plant has been the excessive fineness of the charge due to fine grinding in the concentration of the crude copper ores. The many desirable features of deep-bath smelting as now used at Garfield have been proved. The old method of dropping the charge through holes in the arch (known as center-feed method) causes excessive dusting which makes heavy slag and flue-dust losses, also rapid deterioration of the silica brickwork of the furnace through fusion with the iron oxides from the dust. The purpose of this paper is to describe a gun feeder that was designed to overcome the disadvantages of the older methods of center feeding and still maintain the good features of deep-bath smelting with the hot finer charge. A gun feeder was designed to introduce the finely divided hot calcines under the moving gas stream of the combustion zone and still have them spread in a uniform blanket over the highly heated matte bath. The temperature of the furnace was so great that it was impossible to maintain a stationary feeder, so a movable feeder was designed that could be introduced into the highly heated zone and be withdrawn after the charge had been dropped. It was necessary to protect the nozzle of the gun with a water-cooled coil. Many different types of protected nozzles were tried, such as air jackets, water jackets and heat-resisting steel alloys, but none proved satisfactory. The angle of inclination of the feeder was found to be an important factor in spreading the charge evenly over the surface of the bath. An angle of 34" to 37" was found to be the most advantageous. To allow a continuous flow of ore from the charge car to the point of discharge inside the furnace, the feeder was made with telescopic connections. The pipe leading from the car is stationary and forms the inside part of the telescope. The outside section of the telescope is movable, and is

Jan 1, 1934

By Royal B. Jackman, Carle R. Hayward

Two comprehensive papers have appeared regarding the forms of copper that occur in smelter slags, one by Frank E. Lathe1 and the other by C. G. Maier and G. D. Van Arsdale.2 These authors comment on other published results and draw conclusions from their own investigations. The development of X-ray examination of minerals and improvement in high-power microscopic methods make it possible today to get additional evidence by means that were not available to earlier investigators. The present work was confined to reverberatory slags obtained from five different plants. Some definite conclusions were reached regarding the forms of copper present in these slags. In most cases these agree with some of the findings of Maier and Van Arsdale but new methods of attack were used in the investigation. Conclusions of Previous Investigators Various important conclusions reached by previous investigators are summarized in the following paragraphs, arranged chronologically. William A. Heywood:3 Slag losses increase with grade of matte but with the same grade of matte losses decrease as the acidity of the slag increases. Lewis T. Wright:' Slag losses are only partly due to prills of matte. It is suggested that part of the copper is dissolved in the slag. J. Parke Channing9 A considerable part of the copper enters the slag as silicate or oxide and not as sulfide. C. A. Grabill:6 Slag losses are both physical and chemical. Physical losses, due to poor settling, gas flotation and slight differences in specific gravity, are small under normal conditions. Chemical losses may- be due to formation of oxides or to solution of metals and sulfides. The last is considered the most important. John W. James:' The copper in converter slag is largely the oxide and as such enters the reverberatory slag when converter slag is added to the charge.

Jan 1, 1934

By Frederick Laist

This paper is a review of Montana reverberatory smelting practice covering a period of approximately fifty years, during which time the small furnaces that had been in use elsewhere for a century or more, without much change in size or method of operation, were revolutionized and were developed into the huge, continuously operating furnaces of today. A study of Montana practice is particularly instructive, since reverberatory furnace smelting for the production of copper matte received more attention there than in other smelting centers and many of the improvements that finally resulted in establishing the preeminence of this type of furnace over the blast furnace originated in Butte and Anaconda. The material in this paper was gathered from original sources, wherever possible, and all of the illustrations were made from original drawings, some of which have been simplified and worked over so as to be better adapted for reproduction. The aim has been to trace the modifications in design and operation which took place during the period in question—the reasons for the changes and the results achieved through them. For developments during the first twenty years, the technical literature of the period was freely drawn upon, but I am particularly indebted to W. M. Kelly, general foreman at the Anaconda Works, whose recollections and personal experience extend back to the early days. I wish to acknowledge the use made of publications of E. P. Mathewson, William Wraith and L. V. Bender, as well as information obtained here and there from friends and associates. The resume of Great Falls practice was compiled from correspondence, notes and drawings found in the files of the old Boston & Montana Co. and the tabulations showing the performance of furnaces at Butte and Anaconda are adapted from plant records and correspondence in the files of the Anaconda Copper Mining Company. The paper deals with some interesting comparisons that were made between furnaces operated under various conditions in connection with the Carson Case, and results obtained when using natural gas as fuel. This part of the paper may be considered original to the extent that these results have not previously been published.

Jan 1, 1934

By P. D. I. Honeyman

Changing trends in concentration, involving regrinding with the subsequent production of a finely divided, high-grade flotation product, presents a real problem to the modern copper smelter. In the treatment of such a material, handling difficulties are numerous and potential possible losses may be very great. In many plants, of course, preliminary roasting of the furnace charge remains an economical necessity. Under such circumstances, the operator has no alternative except to follow orthodox roaster reverberatory practice, though taking all possible precautions to avoid excessive dust losses and bad working conditions. In other plants, roasting is not only unnecessary but would be highly undesirable, and at best the charge would be merely dried before entering the reverberatory furnace. In the latter case the possibilities of raw charging loom large. The Miami plant of the International Smelting Co. handles the entire output of concentrates of the several mining companies operating in the Globe-Miami district. All of these companies produce a flotation concentrate which, at the Miami Copper Co. particularly, is all reground and is high in grade. In addition, the Inspiration Copper Co. ships a substantial tonnage of high-grade cement copper to the smelter from its leaching plant. Following the flow sheet of the original plant, all such material received was bedded, dried in Wedge furnaces and smelted in reverberatory furnaces. At times during the history of the plant it has been necessary to carry the drying operation further, to a partial roast, before reverberatory smelting. Since the charge contained over 80 per cent flotation concentrates, the handling of which in a dried condition was at best a dusty job, unusual precautions were taken to cut down dust losses. The Wedge furnace plant was equipped with a Cottrell treater and all hoppers and calcine cars were carefully designed to cut down dust loss in transferring the so-called calcine from hoppers to car and from car to furnace. In the furnace itself the dusting problem was a severe one. Arch erosion was very rapid and flues and waste-heat boilers rapidly filled up with a partly smelted flue dust.

Jan 1, 1934

By E. S. Bardwell

Each of the three refining furnaces in use at Great Falls is provided with a waste-heat boiler. The general arrangement of furnace and boiler is as shown in Fig. 1. Two of the furnaces have hearths 45 ft. 7 in. by 14 ft. 6 in.; the third has a hearth 46 ft. 101/2 in. long and of the same width as the other two. The furnaces at present are equipped for firing with natural gas. As originally constructed two of the furnaces had hearths 36 by 14 ft., and were designed to use coal on grates, but these furnaces were lengthened and fired successively with pulverized coal and oil. The third furnace was added in 1926 and was oil-fired until 1928. Since that year natural gas has been in use on all of the furnaces. The changes that have occurred in connection with furnace design and the comparative performance of the furnaces with various fuels were described1 by the author in 1932. Two of the furnaces are provided with Stirling class A-30 boiler. rated at 400 hp. and having 4008 sq. ft. of heating surface. The thir furnace has a class A-21 Stirling waste-heat boiler rated at 300 hp. with 2805 sq. ft. of heating surface. The boilers are not baffled. The waste-heat boilers are placed on a platform 17 ft. 3 in. above the level of the furnace charge floor. The waste gases from the furnace pass by a vertical uptake flue, 4 by 3 ft. inside at the point where it enters the chamber, to a brick chamber from which the gases pass over a bridge wall and into the boiler setting. The uptake flue and chamber are constructed of silica brick. Each furnace has a steel stack 125 ft. high, measured from the boiler floor. The stacks have a 41/2-in. firebrick lining and are 5 ft. in diameter

Jan 1, 1934

By P. D. I. Honeyman, P. A. Faust

At the Miami plant of the International Smelting Co., Inspiration, Ariz., there are four reverberatory furnaces, all 120 ft. long. At present only one of these furnaces is in operation. It is operated as a wet-charge furnace, the charge being distributed for about 65 ft. down the furnace length. Usually this charge contains about 12 per cent moisture and runs 25 per cent sulfur, of which there is eliminated in the furnace from 25 to 30 per cent. The furnace is oil-fired, the fuel being burned in a battery of Cananea-type, low-pressure burners. The flame is kept short and conditions so adjusted as to obtain complete combustion within the furnace. The average furnace draft, taken through the verb arch, amounts to only 0.02 in. of H2O. Draft is purposely kept low to cut down infiltration through the flues and boiler settings, and control dampers are regulated to maintain this uniform condition throughout the charging as well as the smelting period. Hot gases discharge from the furnace uptake through a common header flue to the waste-heat boilers. The general layout and dimensions of the plant are shown in Fig. 1. Four Stirling boilers, two of class M-26 (713 hp.) and two class M-31 (850 hp.), serve the furnace. Three usually are sufficient to take care of normal operation, the fourth boiler being used as a spare when necessary. The distribution of hot gases to the various boilers is regulated by the dampers in the boiler exit flues. Normally the boilers closest to the furnace uptake would evaporate more water than do those farther away, but dampers are regulated so as to distribute fairly well the load between the several boilers. Steam from the waste-heat plant is delivered to the adjoining power house of the Inspiration company, where it is used both in the Nordberg blowing engines and for electrical generation. Steam pressures and temperatures recorded are those in the main power-plant header and are thus inclusive of all losses in about 500 ft. of 10-in. line. Steam for smelter heating and auxiliary use is taken from the main waste-heat header, is reduced to 125 lb. and distributed through separate lines. Boiler feed water is supplied by the power plant and consists of returned condensate, augmented to a large extent by make-up water

Jan 1, 1934

By George Tryon, E. A. Barnard

The importance of the conservation of the waste heat contained in copper reverberatory furnace gases was realized very early by those in charge of operation at Anaconda. The first attempt to utilize it was in preheating the air used for combustion of the coal. This was done by forcing the air through ducts surrounding the flue-gas downtake and continued down beneath the furnace hearth to the firebox. Any small advantage gained by the heat transferred from the flue gases was more than offset by the losses sustained in cooling the hearth, therefore this process, after several trials, was soon discarded. It was first used at the Old Works as early as 1893 and again for a comparatively short time on the original furnaces at the Washoe smelter, or present works. Water-tube boilers came into general use very rapidly after 1890. Their adaptability for waste-heat steam generation, as well as the saving to be effected by the production of cheap steam from this source, was soon recognized. The first waste-heat boiler to be used in connection with a matte furnace at Anaconda was installed in September, 1900, at the "Old Lower Works." It consisted of a 100-hp. "Cook," vertical water-tube boiler. This boiler had 65 small perpendicular tubes arranged in concentric circles around a 10-in. tube in the center. These tubes were expanded into 4 ft. 4 in. inside diameter cylindrical steel top and bottom drums which served as the steam and mud drums respectively. This boiler was set in a cylindrical brick housing into which the furnace gases entered just above the mud drum and thence circulated upward around the tubes and steam drum to the stack. This installation proved unsatisfactory, presumably on account of difficulty with dust, and was soon abandoned. However, the possibilities for steam generation were undoubtedly encouraging for shortly afterwards (December, 1900) a 300-hp. Stirling boiler was installed, to be followed by two more in the spring of 1901. The choice of the Stirling type of boiler for application to copper reverberatory furnaces was particularly fortunate, as the arrangement of the tubes appears to combine to a great extent the maximum contact of the gases with the heating surfaces of the boiler and at the same time

Jan 1, 1934

By R. A. Marriot

The steam-generating plant at the Garfield smelter of The American Smelting and Refining Co. consists of two divisions in which the boilers are classed as direct-fired or waste-heat. The direct-fired boiler plant consists of eight 330-boiler hp. type K-19 and S-I 7 Stirling boilers located in the boiler room adjacent to the power house, and two 330-boiler hp. Stirling type K-19 boilers in the reverberatory building, which formerly were connected to a reverberatory furnace but now are arranged for direct firing. All direct-fired boilers are now fired with natural gas. The waste-heat boiler plant consists of all units connected to reverberatory furnaces, and receiving heat from the exit gases therefrom. In this classification there are two 490-boiler hp. Erie City vertical water-tube boilers, and six 330-boiler hp. type K-19 Stirling water-tube waste-heat boilers. Each furnace has boilers arranged in battery setting. The boilers are directly in front of the furnace and connection is made through a short uptake and flue (Fig. 1). The Stirling boiler settings rest on concrete foundations at ground level, with the furnace uptake and flue at a low elevation. The Erie boilers are carried on steelwork some 15 ft. above ground level, and stand against the face of the uptake with no connecting flue. The constructional requirements of a larger furnace dictated this type of setting.

Jan 1, 1934

By J. H. Rose

The arrangement of the reverberatory furnace and the two waste-heat boilers at the Magma Copper Company's smelter at Superior, Ariz., is shown in Fig. 1. The inside dimensions of the furnace at the slag line are: length, 96 ft.; width, 22 ft. The boilers are Erie City vertical type with a rated capacity of 700 hp. The 3-in. boiler tubes are arranged in two banks with a vertical baffle between. The banks are 30 tubes wide by 9 tubes deep—a total of 540 tubes.

Jan 1, 1934

By J. R. Martson

The arrangement of the larger furnace at the United Verde smelter, together with the boiler layout and connecting flues, is shown in Fig. 1. The important dimensions are given in the figure, and cross-sectional areas of combustion space, flues, etc., are recorded. The location and extent of the baffling in the boilers also are shown because of their importance in the interpretation of the data. Two boilers serve each reverberatory furnace. They are of the class M-26 Stirling type (rated at 713 boiler hp. each). Steam is generated at 178-lb. gage pressure at a total temperature of 528" F., from feed water at a temperature of 113" F. The feed water is condensate from turbogenerators plus make-up softened by the lime-soda process. The make-up is rather large in amount as it must match the amount of steam consumed in reciprocating blowing engines and the like, which are not served by surface condensers. As a result the boiler feed water has a hardness of 1.5 to 3.0 grains per gallon, but this results in the formation, during six months to one year of boiler operation, of scale only of "eggshell " thickness or less. The boilers are set at the same elevation as the tapping floor of the furnace, which results in the introduction of the waste-heat gases at the top of the front bank of tubes and necessitates the inversion of the usual baffling arrangements. The boilers are equipped with valve-in-the-head soot blowers, which keep most of the dust blown off the surface of the tubes, but it is necessary to supplement the soot blowers by high-pressure air lances, inserted by an attendant through side doors in the boiler setting. Deposits of coal ash and of dust from the furnace charge accumulate in the flues between the reverberatory furnaces and the boilers and this necessitates cleaning of these connecting flues by hand during the greater part of one of the three 8-hr. shifts during each 24 hr. This cleaning operation requires the opening of clean-out doors, which, of course, has some effect on the yield of steam. Revebberatory Furnace Practice The United Verde furnaces are fired with pulverized coal of sub-bituminous type of which the screen and chemical analyses are given in Table 1.

Jan 1, 1934

By N. W. Sager, H. W. Mossman

The arrangement and general dimensions of the reverberatory furnaces and waste-heat boilers for the Nos. 2 and 3 smelting units at the McGill plant of the Nevada Consolidated Copper Corporation are shown in Fig. 1. Each of the two reverberatory furnaces has its own set of waste-heat boilers, and before February, 1932, each furnace, when it was in operation, delivered waste-heat gases to its own boilers only. In January, 1933, the idea was suggested of using some of the waste-heat boilers as economizers to operate in conjunction with the waste-heat boilers that were generating steam. The execution of this idea gave rise to the gas-flow scheme depicted in Fig. 1, the advantages of which were obvious, particularly so in view of the fact that for some months prior to the adoption of this scheme the smelting had been confined to No. 2 furnace, with No. 3 furnace and its boilers idle. The waste-heat gases from No. 2 furnace pass through the boilers serving this furnace as steam-generating units, thence through the original exit duct to a point where a bulkhead diverts the gases in a reverse direction through two of the boilers of No. 3 furnace. After the gases have traversed these two boilers, another bulkhead placed in the duct between No. 3 furnace and its boilers causes them to traverse still one more boiler, from which the gas path leads to the stack. In this scheme the last three boilers traversed by the gases, i.e., the boilers behind No. 3 furnace, function as economizers and preheat the feed water for the two steam-generating units directly serving No. 2 furnace. This discussion will give consideration to the results obtained in waste-heat recovery by the scheme shown in Fig. 1, and, further, will compare these results with those obtained before the boilers of No. 3 furnace were set up to act as economizers, but before going into the detail of heat generation, distribution and recovery, will present some additional details of the equipment. All boilers in this waste-heat plant are of the Stirling type. The two behind No. 2 furnace, acting as steam-generating units, of class 13, are 40 tubes wide and rated at 1112 boiler hp., while the three boilers behind No. 3 furnace, acting as economizers, are also of class 13, but 28 tubes

Jan 1, 1934

By Hans Neuberger

In our everyday life, visual perception plays perhaps a more important role than any of the other senses with which we are equipped by nature. It is, therefore, quite understandable that the average person associates with the term ''atmospheric pollution," clouds of dust, palls of smoke or deposits of soot, phenomena which are so familiar to the residents of industrial cities. On the other hand, "air" is usually considered the prototype of the invisible, of the intangible, and any suspensions in the air which do not conform to this concept, are regarded as foreign to the atmosphere and thus as "pollution." According to Webster, the term "pollution" implies uncleanness, impurity, in short, something undesirable. Although the scientist often accepts popular concepts, he is generally inclined to suspect that apparently "obvious" phenomena imply, literally, "more than meets the eye." To show that this suspicion is also justified with regard to atmospheric pollution, is the objective of this discussion. It will be shown that what seems foreign to the air at first sight, is by nature an integral part of it, and that the more important aspects of pollution generally escape attention. The Atmospheric Constituents We can distinguish two classes of atmos-pheric constituents: the Permanent gases, chiefly nitrogen, oxygen, traces of argon, neon, and others, and the variable constituents which include water in its different states, carbon dioxide, ozone, and various suspensions, either in gaseous, liquid or solid form. These suspensions, known by the collective term "Aerosol,"20 will be considered in detail. Dust There are two general types of aerosols: the first type is represented by the socalled "neutral" particles,3 commonly known as dust and experienced by everyone, as it is the more conspicuous type of suspensions. It often represents a special problem to the mining engineer, the mechanical engineer, the industrial engineer, and many other professional men. Dust consists of finely divided solids derived from weathering, drilling, handling and preparation of rocks and coal. Dust may also consist of organic or inorganic particles resulting from manufacture of a variety of products such as flour, rubber, lime and steel, from traffic on land be it on the highways, on rails or in city streets, from decomposed vegetation or from volcanic eruptions. Perhaps the most reviled member of this class of suspensions is the soot and fly ashes from coal fires and other combustion processes. The cosmic source of dust, namely the injection of meteoric matter into the atmos-,,here, is of minor significance because the concentration of particles is exceedingly small despite the relatively large mass of material which invades the earth's atmos-phere from space.

Jan 1, 1949

By Henry F. Heblby

HOW often has the thoughtful observer pondered the apparent contradictions experienced in the weather? One can take records of two days, one in the winter and one in the summer. The "degree days1' indicate that space heating and domestic load were present in one case and not in the other. The Business Index may be about the same, indicating that the industrial activity of the area and its concomitant use of fuel were about the same. Thus the volume of the products of combustion released to the atmosphere varied only as related to the space heating demand. Yet on one day in winter the atmosphere may be clear and bracing, while on a summer's day the air is thick and murky and the visibility sharply reduced. The situation may be reversed. What are some of the factors that contribute to the creation of these conditions? These few notes have been prepared to indicate some of the influences that are exerted on the problem. The Sources of Atmospheric PolLution The industrial area of Pittsburgh, Pa., has been a dominant center for the production of iron and steel for over one hundred years. In fact, with the growth of the numerous auxiliary processes Allegheny County which contains Pittsburgh is prob- ably the most industrialized county in the world. In addition, the type of manufacture carried out in this area is predominantly dependent on thermal energy (heat). That energy is supplied from coke and coal produced in the vicinity of Pittsburgh Indicative of the stupendous quantities of fuel that are employed in this industrial area's economy, the following (Table I) taken from the U. S. Census (1940) may be of interest. In tonnage consumed in the area, the figures are equally impressive: Annual Tons oF Coal Metallurgical Industries.... 35,000,000 to 40,000,000 Commercial Installations (Pgh.)................. 1,500,000 Domestic hand-fired) (Pgh.)................. 750,000 An influence that has never been fully appreciated by many individuals is the fact that no matter what adventures the gases of combustion experience as they pass through the various processes, uti-mately the spent gases are discharged through chimneys to the atmosphere.

Jan 1, 1949

By J. C. Mertz, C. H. Mathewson

Accurate knowledge of the solid solubilities of the elements that dissolve in the important base metals is needed for guidance in the preparation and heat-treatment of the alloys derived from these components. While there is still difference of opinion concerning the merits of the X-ray and microscopic methods of determining such solubilities, it is certainly true that the recent extensive use of X-ray diffraction to review the existing constitutional data has revealed many glaring inaccuracies and has brought about a much improved knowledge of phase-boundary locations, which will inevitably come to include all of the important alloy systems. When the work is done with all necessary precautions it appears that in the majority of cases where the solubilities extend beyond a few tenths of a per cent the X-ray back-reflection technique is capable of furnishing the best of information in this field. For the most prolonged and thorough studies it is obviously advisable to combine the results of several methods, in particular, to obtain an agreement between X-ray and microscopic data. This paper reviews the work previously done on the solubilities of phosphorus, arsenic, antimony and bismuth in copper and, in consideration of the uncertainties thus made apparent, presents new X-ray data obtained with the first three members of this group. Copper-phosphorus System Heyn and Baurl found that in slowly cooled alloys phosphorus forms a solid solution with copper up to about 0.175 per cent. Huntington

Jan 1, 1937

By C. H. Mathewson, H. M. Day

The constitution of the system silver-mercury has attracted the attention of many investigators during the last two decades, but since their results are for the most part in poor agreement, there is little need for a review of their individual contributions. It remained for the very careful thermal and microscopic investigation of Murphy1 in 1931 to give the constitutional diagram in its present and unquestioned form, which is shown in Fig. 1. He devised methods for taking cooling curves on alloys under high pressures and for the microscopic observation of alloys which contained liquid mercury as a structural constituent at ordinary temperatures. The compositions of the intermediate phases were confirmed and supplemented through X-ray analyses by Preston2 and Stenbeck.3 According to Murphy, at 2760 C. silver is able to dissolve 44 to 45 weight per cent of mercury, which may increase at lower temperatures to about 50 per cent. Preston concluded that the saturation boundary occurred at 46 ± 2 per cent at 100° C. From the values reported in the literature, these are the only ones that may be accepted as lying even in the right region. Preparation of Alloys The silver used in the present investigation was supplied by the United States Metals Refining Co. through the courtesy of the Committee on Industrial Uses of Silver and, since a complete spectrographic and chemical analysis was furnished, no attempt was made to purify it or to further establish the impurities present. The analyses reported by the company are shown in Table 1. Milligan4 has found that the magnesium content is probably less than 0.0005 per cent.

Jan 1, 1938

By H. M. Day, C. H. Mathewson

The constitution of the system silver-mercury has attracted the attention of many investigators during the last two decades, but since their results are for the most part in poor agreement, there is little need for a review of their individual contributions. It remained for the very careful thermal and microscopic investigation of Murphy1 in 1931 to give the constitutional diagram in its present and unquestioned form, which is shown in Fig. 1. He devised methods for taking cooling curves on alloys under high pressures and for the microscopic observation of alloys which contained liquid mercury as a structural constituent at ordinary temperatures. The compositions of the intermediate phases were confirmed and supplemented through X-ray analyses by Preston2 and Stenbeck.3 According to Murphy, at 2760 C. silver is able to dissolve 44 to 45 weight per cent of mercury, which may increase at lower temperatures to about 50 per cent. Preston concluded that the saturation boundary occurred at 46 ± 2 per cent at 100° C. From the values reported in the literature, these are the only ones that may be accepted as lying even in the right region. Preparation of Alloys The silver used in the present investigation was supplied by the United States Metals Refining Co. through the courtesy of the Committee on Industrial Uses of Silver and, since a complete spectrographic and chemical analysis was furnished, no attempt was made to purify it or to further establish the impurities present. The analyses reported by the company are shown in Table 1. Milligan4 has found that the magnesium content is probably less than 0.0005 per cent.

Jan 1, 1938