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By O. C. Ralston

The use of copper sulfate for improving the flotation behavior of sphalerite is probably at least 15 years old. The original discovery of its activating influence is somewhat obscure. The story goes that in the mill at Mascot, Tenn., its favorable action was discovered by accident, early in 1914, as follows: The original laboratory test work on a sphalerite ore gave favorable flotation results, but after a mill had been built the flotation concentration of the ore was very unsatisfactory. In diagnosing the probable reasons, one fact pointed out was that the laboratory test machine had been constructed of bronze whereas the commercial machine allowed pulp to come in contact only with wood and iron. A plate of sheet copper was hung in the flotation machine and results immediately improved. At first fanciful explanations of electrolytic and electrostatic behavior were given credence, but when the copper plate was removed and a small amount of copper sulfate substituted in the pulp an even more favorable result was obtained. Toward the end of 1914 copper sulfate was also adopted in the acid flotation circuit of the Butte and Superior Copper Co. Just who is responsible for the original discovery the present writers do not know. It seems strange that in that era of flotation litigation this discovery was not patented. While for pragmatic purposes it [nay be sufficient to know that the mere addition of copper compounds to a flotation pulp is sufficient to activate the flotation of the sphalerite, for scientific purposes it is quite desirable to know more about how the action takes place. It is the purpose of this paper to present certain evidence dealing with the mechanism of the beneficial effect. The description of the effect as activation in contradistinction to depression is now common in both the English and German languages. It makes no assumptions as to whether the zinc sulfide surfaces have been filmed with copper compounds. In fact, the principal differences of opinion expressed in the literature deal with whether there is an actual formation of CuS (or even Cu2S) on the surface of the sphalerite. Activation of sphalerite takes place in alkaline, neutral or weakly acid solutions and whereas the present day flotation of sphalerite is usually in ah alkaline solution, the early use of copper sulfate was in a sulfate solution.

Jan 1, 1930

By Willard R. Jillson

Within the last ten years Kentucky has become celebrated for its low-sulfur bituminous coals. Prior to this time, many investigators had discnvered the abundance of this coal but the fact was unknown to the general public until the last extension of Kentucky's mountain railroads' was completed. The coals of. Kentucky are, broadly, separated into two geographic units—the eastern and the western coal fields. On a basis of their sulfur content these coal fields fall into three units, which are indicated on the accompanying map, by numbers, 1, 2, and 3. The area marked 1, the very southeastern part of the state, shows the lowest sulfur, all coals being averaged. In this field the maximum is 1.04 per cent. and the minimum as low as 0.68 per cent.—both averages and not individual analyses, which would of course show much greater variation. Included in this group are the following counties: Lawrence, 0.87 per cent.; Martin, 0.75 per cent.; Johnson, 0.73 per cent.; Magoffin, 0.87 per cent.; Floyd, 0.88 per cent.; Pike, 0.68 per cent.; Knott, 1.04 per cent.; Perry, 0.77 per cent.; Letcher, 0.80 per cent.; Leslie, 0.70 per cent.; Harlan, 0.79 per cent.; Knox, 0.86 per cent.; and Bell, 0.92 per cent. The total average sulfur content for these thirteen counties is 0.82 per cent. Bordering the restricted low-sulfur field of eastern Kentucky is the No. 2 belt (slightly darker), 'which is commonly known as the western border of the eastern coal field. Here the maximum sulfur is 2.91 per cent. and the minimum 1.05 per cent. Again these are averages and not individual analyses. The counties in this group are: Greenup, 2.60 per • cent.; Boyd, 1.67 per cent.; Carter, 1.07 per cent.; Morgan, 1.40 per cent.; Wolfe, 1.83 per cent.; Lee, 2.93 per cent.; Breathitt, 1.85 per cent.; Owsley, 1.09 per cent.; Jackson, 1.06 per cent.; Rockcastle, 2.30 per cent.; Clay, 1.09 per cent.; Laurel, 1.08 per cent.; Pulaski, 2.24 per cent.; Whitley, 1.05 per cent.; McCreary, 1.50 per cent.; and Wayne. The sulfur percentage average for this area including fifteen important counties is 1.65 per cent. In the western Kentucky field, the great increase in the percentage of sulfur is at once apparent. Ohio County with 3.78 per cent. is the highest and Hancock with 2.87 per cent. is the lowest. The percentages by counties is as follows: Hancock, 2.87 per cent.; Henderson, 3.22 per cent.; McLean, 3.27 per cent.; Muhlenberg, 3.31 per cent.; Hopkins,

Jan 1, 1920

By William L. Fink, Kent R. Van Horn

Aluminum forms not only binary compounds with most of the metallic elements but also forms many ternary or more complex constituents. Several of those occurring in the more important alloy systems have been identified under the microscope and the action of various etching reagents has been carefully studied.' The determination of the structure and composition of these complex constituents is a matter of some difficulty and little information is available. X-ray crystal analysis offers a promising method for the study of such constituents. First, and of considerable importance, is the possibility of recognizing the presence of a given constituent by means more positive than microscopic observation. Evidence can also be obtained concerning the nature and composition of the constituent in question and ultimately it should be possible, at least in some cases, to describe the structure including the relative locations of the various atoms. In this paper some results of an uncompleted study of the constituents of the aluminum-iron-silicon system are given and the methods employed are described. Inasmuch as iron and silicon are the chief impurities in aluminum, the constitutional relations of this system are of fundamental importance in the metallurgy of pure aluminum and its alloys; the system has been studied by several investigators and the more important contributions have been reviewed recently.² Fig. 1 shows the structure of the aluminum-rich alloys after prolonged annealing at 560" C., in accord with one of the most recent investigations.3 The ternary alloys examined in the course of the present investigation were all annealed at 550" or 560' C.; in fact, some of the specimens were the identical ones used by nix and Heath, who kindly supplied them for this work. Since the results

Jan 1, 1931

By Luis Elek

DEVELOPMENT of the cement industry in Mexico began some 40 years ago. It has gradually reached great importance in the economic life of the country and has contributed greatly to the technical and economical advances which have been so noteworthy, particularly during the last 15 years. From a modest start, the industry now comprises 18 cement-producing plants having a potential annual capacity of approximately 14 million bbl. About half the plants were built and equipped with second-hand machinery during the last world war when no new machinery could be procured. They will hardly attain full production before being modernized and reconditioned, a job now under way in several of the plants. At present, the yearly consumption is only about 8 to 9 million bbl but is steadily increasing. This is only a fraction of the cement consumed in the U.S.A., which is about 250 million bbl per year, although on the basis of consumption per capita per year, the figure is 1/3 bbl for Mexico and 1 2/3 bbl for the U.S.A. Cement consumption in Mexico is well above the average of all other Latin American countries, with the exception of the Argentine, and considering the potentialities and undeveloped riches of Mexico, the road construction and irrigation works, it is fair to assume that the Mexican cement industry will still prosper and expand in spite of temporary setbacks in the future caused by-local events of economic or political nature. Portland cement is manufactured by burning a mixture of raw materials, one of which is mainly composed of calcium carbonates and the other of aluminum silicates. The most typical materials answering this description are limestone and clay, both of which occur in Mexico in many varieties. To be usable for cement manufacture limestone should contain at least 77 to 80 pct calcium carbonate. Lower grade limestone can be used for cement manufacture only if the lime content is increased by the beneficiation process, which has not yet been adopted by the Mexican cement industry. Most of the limestone used by Mexican cement plants has a calcium carbonate content of 90 to 95 pct and therefore requires addition of one or several correction materials. A typical composition of raw mix for cement manufacture is 85 pct limestone and 15 pct shale, clay or volcanic materials. Occasionally it is necessary to add a smaller amount of sand or other siliceous material to increase the silica ratio in the raw mix. Likewise, it is sometimes necessary to add 1 or 2 pct iron ore to facilitate fusion in the kiln and to obtain proper relation between alumina and iron oxide. After calcining and

Jan 1, 1952

THE following letter from the Rector of Louvain University, addressed to Mr. Adams and the other delegates of the Founder Societies, will be of interest to members of the Institute. It is my duty, in the name of the University of Louvain and in my own personal name, to thank you and the representatives of the Founder Societies of the "United Engineering Society" for the very kind letter of congratulations which you sent to me from Brussels on the 5th of July.

Jan 1, 1928

By L. K. Welch, C.W. Macgregor

The past 20 years has seen a revolutionary change in the testing of materials at elevated temperatures. This has largely been brought about by the practical importance of the creep problem in the design of equipment for operation at high temperatures. The short-time tension test carried out at elevated temperatures has consequently assumed in many cases only a secondary role compared with the longtime creep test. In many problems, however, a knowledge of the short-time high-temperature properties of a metal is essential. To mention a few cases in which this is so, we might include all hot-forming operations such as rolling, forging, etc., the welding problem if residual stresses are to be computed, the development of new alloys for high-temperature service where, in the initial stages, time does not permit of long duration creep tests, and others. Usually a knowledge of the short-time properties is desired, if only to serve as a background against which to compare creep behavior. In conducting short-time high-temperature tests, it has been almost the universal practice to determine stresses based on the original area and strains referred to the original gauge length which is usually chosen as 2 in. It has been pointed out1,2 that one of the reasons that the true significance of certain tensile properties is not understood, which perhaps curtails their usefulness, especially when the material is applied under conditions differing considerably from the test conditions, is that true physical stresses and strains are not determined. It is essential to have a knowledge of true stresses and strains in order to correlate the values present in the tension test with those existing, for example, in hot metal-forming operations and in the general problem of the yielding and failure of metals under combined stress conditions. Stress and strain values based on the original dimensions of the test piece do not exist physically except in the early stages of the test. Since at the present time there is very little information in the literature on true stress-strain relations in the short-time high-temperature tension test it is proposed in the following pages to describe a

Jan 1, 1943

By Shiou-Chuan Sun, R. E. Zimmerman

An evaluation of the mechanism surrounding the froth flotation of coarse coal and mineral particles as a result of experiments conducted at The Pennsylvania State College. Maximum size ranges for both bituminous and anthracite coals were established as well as the factors affecting the floating of coarse particles. CONSIDERABLE interest is developing in the froth flotation of coal and the maximum particle sizes which can be treated by such method. The economic necessity of recovering extreme coal fines and slurries plus the restrictions being placed upon stream pollution have brought about many new and prospective installations of flotation plants. Most coal slurries or silts have a wide size range, some sizes of which may be unsuitable for effective froth flotation. This fact also enters into the froth flotation of other minerals and the principles that SHIOU-CHUAN SUN and R. E. ZIMMERMAN, Members AIME, are Assistant Professor and Division Chief, respectively, Division of Mineral Preparation, The Pennsylvania State College, State College, Pa. Joint AIME-ASME Fuels Conference, French Lick, October 1949. TP 2843 F. Disccussion (2 copies) may be sent to Transactions AIME before June 30, 1950. Manuscript received Sept. 12, 1949. apply to coal would also apply to minerals in general. A series of experiments were made by the authors for the purpose of investigating factors influencing the froth flotation of coarse mineral particles and an attempt has been made to evaluate those factors. This paper presents the results of a study of the froth flotation of coal particles in the size range greater than 35 mesh. During the study a "multi-bubble" hypothesis has been developed to explain the various phenomena observed in the behavior of coarse particles in froth flotation of coal. The terms coarse, intermediate, and fine particles as used in this paper are arbitrary and differ for various minerals. For coal alone the term intermediate particles means that the particle size is within the range of 35 and 200 mesh of Tyler sieve sizes. Sizes of coal particles coarser and finer than this size range are termed respectively as coarse and fine particles. Methods of Conducting Flotation Experiments: All of the flotation tests, except those shown in table 1, were carried out in a laboratory Fagergren flotation machine, using 300-a samples of solids for each test. All mineral samples we; prepared from selected lumps of high purity by crushing, grinding, and screening to the desired sizes. Except coals, all the other samples were cleaned through magnetic

Jan 1, 1951

By D. B. Williams

For the first time in the history of the Venezuelan petroleum industry production exceeded 200 million barrels. The total production for all fields amounted to 205,430,869 bbl., which is more than 9 per cent of the world's 1939 total. This is an increase of over 15 million barrels or 8.0 per cent above the 1938 figure, which, compared with the slightly less than 2 per cent increase of the 1938 figure over 1937, shows the marked activity in Venezuela during the past year. The Maracaibo Lake fields are still the predominating factor in Venezuelan production, showing an increase of approximately 9½ million barrels over last year's figure and accounting for 71.8 per cent of Venezuela's total. Lagunillas continues to hold precedence as a single field, having yielded 47.1 per cent of the accumulative total and 39.4 per cent of 1939's total. This field showed an increase of slightly more than 3½ million barrels over 1938. Tia Juana, the second largest field, attained a record production, increasing its percentage of the Venezuelan total from 23.4 in 1938 to 23.7 in 1939. The La Rosa field, which includes Punta Benitez and Ambrosio, declined from 13.7 to 12.0 per cent; Bachaquero, the southernmost Lake field, which came into regular production at the end of 1938, contributed over 31/3 million barrels. Quiriquire, in eastern Venezuela, ousted La Rosa as the third largest producing field, and, although production increased by 11/3 milliorl barrels, percentage of the total declined from 13.2 to 12.9. Mene Grande, the oldest field, declined from 6.6 per cent in 1938 to 5.9 in 1939. Tem-blador produced for a whole year for the first time and yielded 3,647,867 bbl. The Colon district, in the Maracaibo Lake area, comprising the Tarra-Los Manueles fields, showed slight increases, as also did Cumarebo and Pedernales. Construction of the 16-in. pipe line from Oficina to Puerto La Cruz (Guanta), the longest line of this size in the world, was completed toward the end of the year and this new field in eastern Venezuela started shipping oil in December. This field is operated by the Mene Grande Oil Co. and was credited with a production of 2,347,625 bbl. in 1939. Jusepin field, some 25 miles southwest of Quiriquire in eastern Venezuela,

Jan 1, 1940

By Suresh P. Babu, Joseph W. Leonard

The ultimate objectives of comminution should be to reduce material to some specified size while producing a minimum of undersize or fines, with less power, higher throughputs, and with more compact machinery. Attempts to achieve these objectives have been only partially successful, since gains in some areas are achieved at the cost of concessions in other areas. An example of some of these trade-offs can be found in the closed circuit crushing operations of the anthracite and crushed stone industry where, in order to produce a minimum of unprofitable fines, unfavorable concessions must be made in the size of the crushing facility where 2 or more crushing stages are interphased by 2 or more screening operations. This paper discusses experiments with a new process which attempts to achieve some, if not all, of the comminution objectives in a single pass operation without undesirable concessions; or, at the very least, to achieve more than is possible with systems in use today. These objectives are sought by use of water-flushing to enhance comminution. The crushing of coal and other minerals is a mature technology that is long overdue for a careful re-examination. Crushing of coal is generally achieved through the use of rotary breakers and roll crushers. Water-flushing, as envisioned here, appears to have potential application in the following areas: 1) For primary raw coal crushing or for secondary crushing of rotary breaker products. 2) For use as a size reduction and/or concentrating step for crushing coal mine refuse from present production or from existing refuse dumps. 3) For possible future application in underground preparation interphased with continuous mining machinery. Size reduction with conventional methods is known to be an inefficient operation when the increase in surface energy of the material crushed is compared with the input energy. A simple breakdown of the energy consumption in size reduction, given by Orr, is shown in [Fig. 1]. It is believed that most of the energy supplied is lost in the form of interparticle friction.2 Hence, the removal of fines immediately after their formation or the implementation of steps to prevent their formation, based on reduced friction, will reduce the energy requirements of the communition operation.3 A detailed discussion of the mechanism of size reduction is available in other literature.3-5 Even though the closed circuit crushing operation is designed to carry the fines away from the crushing zone, it is still inadequate for instantaneous removal of fines. The present investigation advocates the use of a flowing liquid medium to remove the crushed product immediately after size reduction. Unlike the wet-grinding methods, no constraints are required for the liquid flow rate, and, also, the liquid medium can be used in primary crushers like jaw crushers, hammer mills,

Jan 1, 1978

By C. E. Berry

Natural stone or manufactured porcelain pebbles are used as the grinding elements in pebble mills and the mills are lined with stone or porcelain blocks. Steel balls usually form the grinding medium in ball mills, and the mills may be lined with steel. Pebble mills are used to avoid contamination by metal of the material being ground, to avoid rapid wear due to corrosion, and for other specialized reasons. Belgian silex (silica) blocks formerly were used widely for lining pebble mills, because of their good resistance to wear, light color, and low cost, but the importation of these blocks was suspended early in the war. The stocks of Belgian silex diminished so rapidly that it was found desirable to compare the properties of a number of domestic substitutes for use in critical operations. Accordingly, a study was made to determine the best substitutes for fine grinding of white pigment and for certain heavy-chemical process work such as the disintegration of phosphate rock in weak phosphoric acid solution. A comprehensive survey of substitute lining materials was not contemplated. It was stipulated at the beginning of the investigation that only materials on the market, available in large quantities, would be tested and that these should be reasonable substitutes from a a ance viewpoint as determined from known physical characteristics. Marble and limestone, for example, could be eliminated immediately. Quartzite, granite and porcelain were selected as likely substitutes for Belgian silex and were subjected to quality tests. Materials Tested 1. Belgian Si1ex.—Sample blocks of a standard grade were taken from crates in which they had been imported. The stone was light gray in color and contained inclusions of small clusters of quartz crystals as well as light colored portions that might be calcite. This was a siliceous rock which appeared to be of igneous origin. 2. Quartzite.—Samples of quartzite were obtained from a quarry in Minnesota. The blocks exhibited a crystalline fracture. The stone was pink in color and composed of fine quartz crystals bound together with a siliceous cement. 3. Granite A was a fine-grained granite quarried in South Carolina. 4. Granite B was coarse-grained granite quarried in South Carolina. 5. Granite C was a coarse-grained granite quarried in North Carolina. 6. Porcelain A.—Sample blocks of the pebble-mill lining material were obtained direct from the manufacturer. It was white in color and of lower specific gravity than the natural materials. It did not have a crystalline structure. 7. Porcelain B.—Sample pebble-mill lining blocks of the porcelain were received direct from the manufacturer. It was white

Jan 1, 1948

By H. W. Page

Petroleum requirements since V-J day have been appreciably higher than predicted. Foreign operations now exceed maximum wartime levels by about 14 per cent. Domestic operations since V-J day have averaged 92 Per cent of the wartime peak. In spite of maximum foreign refinery runs, large exports of all products, except residual fuel oil, are necessary to meet foreign demand. During the next few years it is expected that foreign operations will continue at capacity, including new installations, but that, because of increases in foreign demand, exports will continue at about their present level. Domestic operations will increase during this period and crude production probably will exceed maximum efficient rates. Even after 10 years some exports probably will be required, but eventually these will be supplanted by increased output of foreign refineries, except for small tributary exports. The increase in domestic requirements will exceed the decline in exports. Unless findings of crude oil exceed present expectations, the increasing demand will be met by increased imports and synthetic methods-—such as the Hydrocarbon Synthesis Process for conversion of natural gas and coal to gasoline and distillates. Catalytic cracking installations will increase as crude availability decreases. This will help to meet the increasing demand for gasoline but will intensify the domestic shortage of residual fuel oil. Eventually larger imports will be required to satisfy the demand for this product. Introduction Under the pressure of the wartime period, there was time only occasionaly to look ahead in anticipation of what the postwar era held for the petroleum industry. Perhaps the general expectation was that a rather pronounced decline in the level of industry petroleum operations would take place shortly after the end of the war, with the impact felt mainly on the economy of the United States- It is of interest now, nine months after V-J day, to take inventory of the near-term situation and see what significant forces are at work. With this as a starting point, it should be possible to engage in something more satisfactory than pure speculation concerning trends in the immediate future and 10 to 20 years ahead. Present and Near-term Situation During the nine-month period following V-J day, foreign crude oil production and rebery operations have actually increased the These activities were at maximum capacity on V-J day but the continuation of drilling programs, the completion of new and rehabilitated refineries and of transportation facilities during the Past nine months have increased the foreign capacity. This added capacity has been fully utilized. Foreign crude oil production in May 1946 is about 14 per cent higher than during July 1945 and refining operations some 12 per cent higher' During the same period there has been a falling off in similar activities within the

Jan 1, 1947

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 L. K. Welch, C. W. MacGregor

The past 20 years has seen a revolutionary change in the testing of materials at elevated temperatures. This has largely been brought about by the practical importance of the creep problem in the design of equipment for operation at high temperatures. The short-time tension test carried out at elevated temperatures has consequently assumed in many cases only a secondary role compared with the longtime creep test. In many problems, however, a knowledge of the short-time high-temperature properties of a metal is essential. To mention a few cases in which this is so, we might include all hot-forming operations such as rolling, forging, etc., the welding problem if residual stresses are to be computed, the development of new alloys for high-temperature service where, in the initial stages, time does not permit of long duration creep tests, and others. Usually a knowledge of the short-time properties is desired, if only to serve as a background against which to compare creep behavior. In conducting short-time high-temperature tests, it has been almost the universal practice to determine stresses based on the original area and strains referred to the original gauge length which is usually chosen as 2 in. It has been pointed out1,2 that one of the reasons that the true significance of certain tensile properties is not understood, which perhaps curtails their usefulness, especially when the material is applied under conditions differing considerably from the test conditions, is that true physical stresses and strains are not determined. It is essential to have a knowledge of true stresses and strains in order to correlate the values present in the tension test with those existing, for example, in hot metal-forming operations and in the general problem of the yielding and failure of metals under combined stress conditions. Stress and strain values based on the original dimensions of the test piece do not exist physically except in the early stages of the test. Since at the present time there is very little information in the literature on true stress-strain relations in the short-time high-temperature tension test it is proposed in the following pages to describe a

Jan 1, 1943

By E. Rudy, St. Windisch

The only complete phase diagram investigation of the Ti-W system is by Maykuth and coworkers,&apos; Fig. 1. Although previous work by Gonser2 indicated complete miscibility, later investigations3°5 essentially confirmed the diagram depicted in Fig. 1. The present study was undertaken because preliminary results on metal-rich ternary Ti-W-C alloys indicated complete solid solubility between 0 titanium and tungsten at temperatures above 1300°C—in contradiction to the presently accepted diagram. The powdered elements, as well as crystal bar titanium and tungsten sheet, were used in the preparation of the experimental alloys. The iodide titanium, obtained from Foote Mineral Co., Exton, Pa., had a total impurity content of less than 410 ppm, of which 150 ppm were interstitials (H, O, N, C). The overall purity of the titanium powder (Var-Lac-Oid Chemical Co., New York) was better than 99.7 pct. Major contaminants, in ppm, included: 0, 800; N, 10; H, 1500; Fe + Co + Ni + Cu + Zn, 50; C1, 200. The measured lattice parameters of the titanium were a = 2.94A and c = 4.68,A. The tungsten sheet and the tungsten powder (Wah Chang Corp., Albany, Ore.) contained the following impurities (in ppm, values in parentheses refer to the sheet tungsten): Mo, 50 (70); 0, 140 (110); Fe, 20 (60); Ni, 20 (not determined); N, 110 (not determined); sum of other impurities, <60 (<100). Samples from the iodide titanium bar stock and from tungsten sheet were prepared by repeated melting of the chipped materials in a nonconsumable electrode arc furnace under high-purity helium. The melted alloys were heavily cored, and homogeneity of the alloys could only be achieved after prolonged heat treatments at subsolidus temperatures. The majority of the alloys were therefore prepared by cold compacting the well-mixed powders in steel dies and pre-homogenizing the compacts for 6 hr at 1300°C in a tungsten-element furnace. The vacuum was better than 10"6 Torr, but for additional protection the sample container was wrapped in zirconium foil. Both preparation methods led to identical results. The measurements of the solidus temperatures were carried oat in the Pirani-type furnace described in a previous paper.6 Incipient melting in alloys containing between 20 and 90 at. pct W was rather difficult to detect visually, and therefore a photoelectric transducer system7 was employed to indicate the phase change. For the investigation of the solid-state equilibria, the specimens were first homogenized for 2 hr at slightly subsolidus temperatures in the Pirani fur- nace and then reequilibrated at, and rapidly cooled (-100°C per sec) from, the selected equilibrium temperatures. After the runs, the alloys were analyzed microscopically and by X-ray diffraction. With the exception of spot checks for oxygen and nitrogen in processed alloys, no other chemical analyses were performed. However, as the weight changes of the alloys during processing were within 0.05 pct and the lattice parameters of indeqendently prepared alloy series agreed within 0.0015A, it is reasonable to assume that no significant concentration shifts with respect to the nominal compositions had occurred. The measured solidus temperatures, shown together with literature data in Fig. 2, ascend smoothly from

Jan 1, 1969

By M. E. Wadsworth, I. B. Cutler, R. W. Bartlett

The oxidation kinetics of ZrC was studied between 450" and 580°C in oxygen pressures from 6.5 x 10-to 1 atm using a ther mogravimetric apparatus and sized powder samples. Two parallel rate controlling processes were observed. A surface reaction occurring at the ZrC-ZrO2 phase boundary accounted for most of the oxidation and had an activation enthalpy of 46 kcal per mole. The other process, believed to be diffusion of oxygen into the ZrC lattice partially replacing carbon, had an activation enthalpy of 53 kcal per mole. The enthalpy for chemisorption of O2 on ZrC was determined to be —13 kcal per mole. Water vapor in the presence of oxygen accelerated the surface reaction rate. THERE has been little reporting of formal rate studies or attempts to ascertain the mechanism of oxidation of carbides. MacDonald and Ransley1 studied the oxidation of titanium carbide which has the same structure as zirconium carbide, fcc. They observed an initial increase in rate with increasing temperature followed by a rapid decrease through a rate minimum and a subsequent second increase at higher temperatures. The discontinuity in the rate rise was attributed to a phase change in the oxide which changed the rate determining step from the surface reaction at the carbide-oxide interface to diffusion through the oxide layer. Samsonov and Golybera 2 studied titanium carbide and reported that during the initial period of oxidation a dense film of Tic-TiO was formed followed by the formation of less adhering layers of higher oxides. The purpose of this investigation was to study the kinetics of oxidation of zirconium carbide and to attempt to gain some knowledge of the mechanism by which oxidation occurs. EXPERIMENTAL PROCEDURE Measurement of the weight gain associated with the oxidation of ZrC was used to determine oxidation rates. The principal experimental parameters were surface area, temperature, and oxygen pressure. Although moderately sized crystals of ZrC can be grown by the Van Arkel method, the only commercially available ZrC is a powder. In using powders, the surface area must be controlled either by fabricating the powder into a sintered pellet with a measurable surface area, relatively fixed during oxidation, or by using sized unconsolidated powder and applying appropriate geometric considerations to the shape of the grains to correct for their diminishing surface areas as they oxidize. Both techniques involve some difficulties. pellets of binder-free zirconium carbide can be made by hot pressing, but it is difficult to obtain densities greater than 90 pct of

Jan 1, 1963

By J. Visman

A simplified method of assessing the characteristics of a cleaning unit, including washability curves, yield figures, ash error, separating gravities, and error curve. FOR more than 25 years evaluations of coal cleaning units have appeared in many publications, and during this time considerable progress has been made in developing the theory and techniques of calculating washery results. A variety of characteristics have been defined over the years, many receiving general recognition during the first post-war Coal Preparation Conference in Paris in 1950. Coal preparation has become a science, and the approach to preparation problems is being revolutionized. Formerly, for example, if a coal operator wanted to know the performance of a given cleaning unit for a particular grade of his run-of-mine, he either shipped a carload to the manufacturer for a test run or relied on a report of a test carried out on a coal similar to the one he intended to clean. In modern practice the expensive, time-consuming test work generally can be avoided if the washability curves of the coal in question and the error curve of the cleaner are known. Normally a guarantee can be given on the strength of this information. General acceptance of modern standards has thus reduced the need for pilot-scale models of existing types of coal cleaners. Needless to say, the method requires exhaustive and accurate information on the cleaning unit and on all the additional circumstances affecting its results, information that ultimately can be secured only from actual tests made in the laboratory or in the washery. It is not the purpose of the present discussion to compare the merits of various characteristics, but to describe the general method of calculation, including a method of obtaining data with a minimum of laboratory work. All data presented here were derived from tests made at the plant with portable field equipment, using small quantities of varsol, carbon tetrachloride, and bromoform. It will be explained later that the use of standard fractional ash contents designated normalized ash contents aids considerably in reducing the routine testing of coal cleaners. Like any other statistical procedure, this method has limitations, and it is not recommended for any work in connection with guarantees. Even a varying commodity such as coal, however, will follow the law of large numbers, which is the basic law of statistics, thus allowing simplification of test work without appreciable loss of accuracy. The characteristics needed for evaluating cleaner performance are normally derived from a float-sink analysis of samples of the clean coal and the refuse, followed by ash determinations of the various fractions. Usually a sample of feed is also collected to find its ash content and to make a single specific gravity cut, both in connection with determination

Jan 1, 1955

By A. J. Carlson, G. M. Marincel, M. L. Hovland, J. H. Healy

Research personnel of Erie Mining Co., a pioneer taconite mining firm on the Mesabi Range, have invented a new method to make an effective 325 mesh separation at high tonnage rates over stationary screens. The company regards this development as historically significant in that it represents the first successful method to commercially screen large tonnages of ore at fine sizes. Erie, which is now completing an expansion program at its plant site near Hoyt Lakes, Minn., has incorporated this screening method as part of that expansion. When completed, the concentration plant will produce 10.3 million tons of iron concentrate, all of which will have been efficiently screened at 325 mesh.

Jan 4, 1967

By W. T. Bishop

FOR many years pine oil has been used extensively as a frother for the flotation of minerals, particularly sulphides, yet the published information available to the average user on its composition, chemical and physical properties, has been rather meager. It is the purpose of this paper to discuss these points and their relationship to the frothing properties of pine oil used in flotation processes. Pine oil, as the name implies, is a liquid obtained from the processing of wood of the longleaf and other southern pines. It is a complex mixture of naturally occurring terpene derivatives, primarily alcohols, and a smaller amount of terpenes, which has found many uses in various industries. Its use as a frother in flotation processes was the first large-scale application in industry and today the mining industry still consumes large quantities of pine oil but the textile and disinfectant industries consume comparable volumes. Much is used in soap manufacture and laundry operations. The surface-active properties of pine oil are in a large degree responsible for this versatility. HISTORY The name "Naval Stores" goes back to the days when pine tar and pitch were used to caulk leaky ships and coat their ropes and rigging. Today this term is still used to include not only the oleoresinous products of the pine tree-rosin and turpentine-but other products such as pine oil, pine tar, and the many terpene and resinous compounds obtained by extracting the pine wood or tapping the tree. That part of the industry known as "wood naval stores" dates from about the beginning of this century and today produces a large part of the country&apos;s rosin and turpentine by processing pine wood. In addition, all of our natural pine oil is, supplied by the wood naval stores industry, as tapping of the live tree gives only rosin and turpentine. This latter phase is known as the "gum naval stores" industry. The first successful commercial operation of the steam and solvent process of the wood naval stores in industry was carried out by Yaryan at Cadillac, Mich., in 1909.1 This operation did not prove profitable, so Yaryan went south to utilize the longleaf pine, and built a plant at Gulfport, Miss.2 Soon after, another plant was built at Brunswick, Ga., which is still in operation, and in 1914 was reported to have processed about 500 tons of wood per day.1 In 1921 Hercules Powder Co. acquired the Yaryan interests, at which time the production of pine oil was only 3 to 5 million pounds per year and flotation was the largest customer. As time went on, technological advances were made, other companies entered the field, and the production of pine oil increased many fold. The growth of the industry was especially marked during the past 10 years, and in

Jan 1, 1946

By E. S. Bardwell

The reverberatory copper-refining furnaces at the Great Falls Reduction Dept. of the Anaconda Copper Mining Co. have used successively as fuel, lump coal on grates, pulverized coal, oil and natural gas. In no other plant, so far as can be ascertained, has such a variety of fuels been used. This fact affords a unique opportunity for comparing the relative efficiency obtained with these several fuels under nearly identical conditions. Furnaces The present furnace refinery at Great Falls was placed in operation in April, 1916. The original installation consisted of two furnaces, each with hearths 36 by 14 ft. and provided with fireboxes 10 by 12 ft. for firing lump coal on grates. These furnaces had air-cooled sand bottoms and chrome-brick side walls both above and below the metal line. The roofs were of 12-in. silica brick. Each furnace was provided with a waste-heat boiler of approximately 400 boiler-hp. capacity. We soon found that chrome brick was very unsatisfactory as side-wall material because of its excessive spalling. At the first opportunity the furnaces were rebuilt, using magnesite brick below the metal line and silica brick from the metal line to the roof. At the same time the thickness of the side walls was increased, thus decreasing the width of the hearth to 13 ft. At about this time also, the thickness of the furnace roofs was increased from 12 to 15 in. No further changes occurred in furnace design until 1922, when the use of lump coal on grates was abandoned in favor of pulverized coal. The first charge to be melted and refined with pulverized coal was cast on March 30, 1922. When pulverized coal first was used the burner pipes were introduced directly into the firebox as it was felt that some kind of a combustion chamber might prove necessary, but this was not needed. The fireboxes were dismantled and the burners introduced through openings directly over the bridge wall. During the summer of 1922 one of the furnaces was completely rebuilt, lengthened 10 ft. and provided with a silica-brick bottom in the form of an inverted arch. At

Jan 1, 1934

By David R. Mitchell, R. B. Hewes

MANY processes for cleaning coal that are in use depend primarily on physical properties of coal and refuse other than specific gravity and surface conditions relating to froth flotation. These properties are shape, coefficient of sliding friction, resilience, friability, magnetic susceptibility, and electrical conductivity. In many of these processes specific gravity does have some effect and many separators are designed to utilize more than one of the physical properties cited. Although the processes described herein do not have a widespread application, yet for specific coals and specific conditions, they are economically important. A problem confronting many coal-mining districts is the marketing of the slacks or screenings and dust passing the final sizing screens. Processes in commercial use installed primarily to increase the form value, and hence the market value, of these slacks and dusts include briquetting, packaging, and low-temperature carbonization. MECHANICAL PICKERS Machines utilizing shape, frictional resistance, and differences in resilience of coal and impurities are usually called mechanical pickers. They require a closely sized feed, therefore their use is confined to the pea, nut, and egg sizes. Various types of these devices are described by Berrisford, 1, 2 Taggart,3 and Peele.4 Shape In general, coal differs in shape from its accompanying dirt throughout the range of commercial sizes. Coal, breaking into roughly cubical particles, contains a greater number of axes that are approximately the same length than does the dirt. The latter, consisting of pieces of slate and shale and lenses of pyrite, is flatter in nature. Further, flat coal often has a dirty, slaty appearance, even though of high quality. Mechanical pickers known as flat pickers, or "flatters," are widely used in the Pennsylvania anthracite region to remove flat coal .from the final clean coal. This practice greatly improves the appearance of the final market product. Flat pickers for removing impurities or flat coal ("flats") are usually installed on shaker screens, shaking conveyors, and chutes. In Fig. 1 three

Jan 1, 1950