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By P. Barnes

It cannot be said that this whole subject is a new one in respect to its presentation to the Institute, but the minute discussion of it has been looked upon as lying more strictly within the field of study of the societies which have to do chiefly with the construction and management of machinery as such. It must be true that the importance of close limits in steam-economy is as fully recognized among the members of this Institute as by any body of men who have to do with steam-machinery. In all directions, nevertheless, among manufacturers as well as among metallurgists, there may still be found those who do not give the same attention to exact methods in fuel-consumption as devoted to steam, as to other technical uses which, to say the least, are not more important. The study of the most efficient methods of use of fuel in operations which are more strictly metallurgical has been long-continued, and in some directions nearly or quite exhaustive. This has led to a rather close bringing-up, in those particulars, all along the line of technical work, of the establishments (and their managers) which had lagged behind. Yet, in the steam-departments of those works, there are too many reasons for believing that the name may still be legion of those whose methods and results are far from the best. If there be room in any given case to suspect any imperfect working or waste of fuel in the steam-supply, the search for the evil, the clear fixing of its cause, and the application of the remedy are, or certainly ought to be, too obvious in their pressure for attention upon a manager to call for even so scanty a mention of them as can be accorded in this paper. It is natural that men should be incredulous as to imperfections which may be noted as existing in their machinery or methods. Still more are they likely to be altogether disinclined to admit that there may be thus an actual and palpable leakage in the compartment of their money-drawer devoted to coalsupplies. But the laws which govern the combustion of fuel, the

Jan 1, 1885

By J. Brian Eby

CONTACT metamorphism of coals is any physical or chemical change in the character of a coal directly attributable to heat of surface or intrusive igneous rocks. Coal beds so affected are found in the United States, England, Alaska, Mexico, New Zealand, Greenland, and other countries. Particularly in the United States, there is a wide occurrence of contact altered coals; conspicuous examples are found in Colorado, Utah, New Mexico, Illinois, and North Carolina. During a recent examination of coal beds on Yampa River, in north-western Colorado, the author had an opportunity to make some detailed observations on the contact metamorphism of coals. In this field, coals over an area of 20 sq. mi. have been affected by dikes, sheets, and sills;1 samples of the coals were systematically collected and analyzed,2 with the view of obtaining more specific data on the character of these alterations. The investigation was threefold in purpose: to secure information on the lateral effects of a dike cutting a coal bed, on the range in vertical effects on coal beds overlying sheets or sills, and on the range in the vertical effects on coal beds underlying sheets and sills. Favorable field conditions, such as fresh outcrops and newly dug prospects, made possible many of the field observations and collections. The coals studied in this field belong chiefly to the Mesaverde and Laramie formations. The Mesaverde coals, on the average, are blocky low-rank bituminous coals; the "Laramie coals," which are considerably younger, are of subbituminous rank. The coals of both formations, in the northeastern part of the Yampa field, have been greatly affected by basalt intrusives, yielding all variations of carbonized coal from natural coke to the unaffected material.

Jan 1, 1925

By Paul M. Tyler

YEAR after year, the kaolin industry of the United States has been setting new production records and making better products. High-grade paper, pottery, and rubber clays are produced in this country mostly in the South. Georgia alone contributes over 70 pct and South Carolina almost 20 pct of the total domestic output. Residual kaolin is mined in North Carolina, highly plastic but naturally sandy Tertiary (Eocene) potting clays are worked in north central Florida, and good white clays are produced in several other states, but the main sources of kaolin or china clay have been numerous deposits in the Tuscaloosa (Upper Cretaceous) formation. This formation of generally sandy sediments is called the Middendorf member in older geologic reports and corresponds in age with some of the New Jersey clays. As shown in fig. 1, it crops out almost continuously in a generally southwesterly direction across South Carolina and Georgia and into Alabama. Clay is mined from this formation in all three states but the principal producing centers lie within about 10 miles of a straight line drawn between Aiken, S. C., and a point about 10 miles south of Macon, Ga. The white kaolins of the South were recognized and used prior to the Civil War but suitable treatment processes were not introduced until World War I when imports, chiefly from England, were curtailed. Although imports of high-grade clays were resumed after 1918, the domestic industry managed to treble its prewar production record during the early 1920's and has continued to grow. Whereas the 1909 to 1913 average total production in the United States was only 132,104 short tons valued at $705,352 f.o.b. mines, the output in 1948 was 1,568,848 tons worth $19,756,738.

Jan 6, 1950

By Milton E. Wadsworth, W. Martin Fassell, William H. Dresher

A study of the rate of dissolution of molybdenite (MoS2) in alkaline solution was carried out under carefully controlled conditions. Effects of temperature, oxygen over-pressure, and KOH concentration were evaluated. Studies were made in the temperature range 100°C to 175°C and in the pressure range 0 to 700 psia of oxygen. Under these conditions molybdenite was found to leach according to a linear mechanism. Both oxygen over-pressure and KOH concentration were found to control the rate of leaching. The mechanism has been explained in terms of adsorption of oxygen at the molybdenite surface followed by configurational rearrangement of the adsorbed molecules. The hydroxyl ion dependency is believed to be diffusion-controlled. Laboratory batch studies have shown that molybdenite can be readily dissolved in alkaline solutions under moderate conditions of temperature and pressure. Commercial application of this process to the production of ferro-molybdenum and molybdenum chemicals is promising in view of the ease of dissolution of molybdenite and the relatively noncorrosive conditions involved in the process. HIGH temperature-high pressure techniques have long been used to great advantage in the organic chemical industry, the petroleum industry, and the paper industry. Only recently, however, have these methods been used to extract metals from their ores on a commercial scale. The Chemical Construction Corp., together with interested producers of nickel and cobalt, has done much to develop methods of producing nickel and cobalt powders by the use of high temperature-high pressure techniques.' The Howe Sound Co. is currently operating a plant near Salt Lake City in which the new Chemical Construction Corp. technique is applied to cobalt-arsenic sulfide concentrates. In this method the concentrates are leached in a dilute solution of sulfuric acid under air pressure at a high temperature. Near Edmonton, in Alberta, Canada, the Sherritt Gordon Co. is also using the new method in conjunction with its ammoniacal leach process.' National Lead Co., at Fredricktown, Mo., is operating a process similar to that of Howe Sound. In spite of the rapid growth of high temperature-high pressure hydrometallurgical processes, there has been very little work done on fundamental principles involved in this type of process. Conse- quently the literature lacks any significant data in this field. Oxidation of pyrite,3 phalerite,4 galena,5 and recently molybdenite" in alkaline solutions has been reported to some extent. This investigation was initiated, therefore, to broaden the application of high temperature-high pressure hydrometallurgy and also to contribute some insight into the basic mechanisms of oxidation in an aqueous medium under these conditions. In addition to the immediate consequences of these processes much valuable information remains to be learned about fundamental reactions when they are carried out at temperatures and pressures slightly higher than those normally encountered. Leaching of molybdenite by alkaline solutions under oxygen pressure has recently been reported in the Russian literature by E. S. Usataya,8 who found that leaching rate increased with an increase in the pH of the solution—the strongest effects being observed at a pH of 10—and also with an increase in temperature. Usataya also has reported the formation of a protective film on the surface of the molybdenite when the leaching solution was weakly alkaline, neutral, or acidic. He believes that this oxidation process explains the migration of Mo+ + in the oxidation zones of molybdenite ore deposits and the subsequent impoverishment of the ores. Equipment: The high temperature-high pressure reaction unit used in this work was especially designed for kinetic studies of this nature, emphasis being placed on accuracy of measurement and precision of control. As details of the unit's construction and operation have been discussed elsewhere,7 Only basic features and principles of operation will be discussed at this point.

Jan 1, 1957

By AIME AIME

THE session* on Non-ferrous Metallurgy held Monday morning was conducted in a most satisfactory manner with F. F. Colcord, vice-president, U. S. Smelting Co., in the chair. In spite of the early hour and the fact that members desired to register first, the meeting started quite promptly, with almost every chair in the room occupied. About 65 men were present and during the morning many more came but, not being able to find room, drifted away to other fields of activity. The first paper presented, "Lead Refining Practice of the Bunker Hill Smelter of the Bunker Hill & Sullivan Mining & Concentrating Co.," by Alfred F. Beasley (T. P. 303), was read in abstract by Edward H. Robie, and an animated discussion followed in which Messrs. Johnson (written discussion), Brewer and Jones and Professor Hayward participated. The discussion hinged principally on the liquation of the zinc crusts, but Professor Hayward called attention to the fact that the practice of keeping the gold and silver crusts separate was not new and the present scheme illustrated the axiom that processes based on fundamental principles should not be considered as extinct; one can never tell when it may be found advantageous to make use of them again.

Jan 1, 1930

By Harrison Souder

THE object of this paper is to bring to. the notice of engineers a safety detonating fuse by the use of which misfires in blasting may be eliminated and safety in blasting operations promoted. This new detonator is a French invention and is known as Cordeau detonant or detonating fuse and is sold under the name of Cordeau-Bickford. It consists of a lead tube 5 to 6 mm. in diameter, filled with trinitro-toluene. While applicable to all classes of mining it will appeal especially to those who have to do with deep-hole blasting in open-cut clines or quarries, or any operations where a large number of holes are to be shot at one time. Since the introduction of the deep-hole blasting in the Cornwall iron mines, much trouble has been experienced from misfires and many experiments were made to determine the best and safest method of blasting. Before the introduction of the detonating fuse it was found that to insure the best results, two or more high-power electric exploders, not less than No. 6, with specially insulated conductors, should be placed in each hole; the holes wired in parallel, and for a large number of holes the current to be supplied by a live wire to the bus or lead wires at about the middle of the bench. The voltage in general use is 110 to 220, but as our material is a magnetic iron ore and the holes are generally damp, we found it advisable to reduce this to about 30 volts to prevent short circuits. A No. 7 or No. 8 special insulated detonator was adopted. But with the best of care and attention to the minutest detail, we were not able to eliminate occasional misfires and the consequent ever present danger of accidents.

Jan 10, 1914

By R. T. Hukki

John F. Myers (Consulting Engineer, Greenwich, Corm.)—Since the art of comminution has lain practically dormant for many years, it is very interesting that R. T. Hukki approaches the subject with a new concept. One is reminded of the research carried on by A. W. Fahrenwald of Moscow, Idaho, a few years ago. Fahrenwald mounted a steel bowl on a vertical shaft. The balls and ore placed in the bowl were rotated at fast speeds, thus simulating the supercritical speeds used by Hukki. The rolling action of the balls against the smooth shell liner has pretty much the same effect. The action is horizontal in one case and vertical in the other. Both researchers report good grinding activity. It is also constructive that such able investigators give to the students of comminution their interpretation of their laboratory results in terms of large-scale operation. History shows that it takes a lot of time for such radically new ideas to be absorbed by the industry. Typical of this is the present-day activity of cyclone classification in primary grinding circuits. The idea of cyclone classification has been kicking around for 30 or 40 years. Certainly we all suspect that the ponderous grinding mills of today, and their accessory apparatus, large buildings, etc., will ultimately give way to small fast units, just as this has occurred in other industries over the past 50 years. At the moment there is no evidence that ball and liner wear is prohibitively high. In fact, at the time Fahrenwald was demonstrating his high-speed horizontal machine at the meeting of the American Mining Congress, several years ago, he assured this writer that the balls retained their shape much longer than they do in conventional tumbling mills. Rods and balls that slide (as some operators in uranium plants are experiencing) get flat. Apparently the balls have a rolling action. Mr. Hukki's references to the processing capacity of the Tennessee Copper Co. mills is adequate. Those studying this subject will be greatly interested in the paper presented by Richard Smith of the Cleveland-Cliffs Iron Co. at the annual meeting of the Canadian Institute of Mining and Metallurgy in Vancouver April 24, 1958. This paper will be published during the latter part of 1958 in the Canadian Institute of Mining and Metallurgy Bulletin. Hukki's pioneering spirit is to be commended. R. T. Hukki (author's reply)—It has been heartening to read the objective discussion by J. F. Myers. The sincerity of his opinions is further strengthened by the fact that the article he has discussed contradicts in a major way the parallel achievements of his life work. Myers is right in his opinion that in general it takes a long time before new ideas are accepted by the industry. On the other hand, revolutions usually take place at supercritical speeds. There are many indications at present that both the unit operation of grinding and the related subject of size control are now just about ripe for a revolution. In grinding, brute force must ultimately give way to science. Rapid progress can be anticipated in the following fields: 1) Autogenous fine grinding at supercritical speeds will be the first advance and the one that will gain recognition most easily on industrial scale. At this moment, little Finland appears to be leading the world. Crocker recently made a statement that in nine cases out of ten, your own ore can be used as grinding medium more effectively and far more economically than steel balls. This is true. The present author would like to introduce a supplementary idea: In eight cases out of the nine cited above, it can be done at the highest overall efficiency in the supercritical speed range. Fine grinding must be based on attrition, not impact. The path of attrition may be vertical, horizontal, even inclined. 2) In coarse grinding, the conventional use of rods is sound practice. However, even the rods can be replaced by autogenous chunks large enough to offer the same impact momentum as the rods. To obtain the momentum, the chunks must be provided with a free fall through a sufficient height in horizontal mills operated at supercritical speeds. Coarse grinding must be based on impact. Detailed analysis of the subject may be found in a paper entitled "All-autogenous Grinding at Supercritical Speeds" in Mine and Quarry Engineering, July 1958. 3) All conventional methods of classification, including wet and dry cyclones, are inefficient in sharpness of separation. Continuous return of huge tonnages of finished material to the grinding unit with the circulating load is senseless practice. In the near future the present methods will be either replaced or supplemented by precision sizing. These three fields are also the ones to which J. F. Myers has so admirably contributed in the past. Fine Grinding at Supercritical Speeds. By R. T. Hukki (Mining EnGineERInG, May 1958). Eq. 9, page 588, should be as follows: T , c, (a — 6') n D Ltph On page 584 of the article the captions for Figs. 4 and 5 have been placed under the wrong illustrations and should be interchanged.

Jan 1, 1959

By Frederic H. Lahee

The purpose of this paper is to demonstrate the similarity of the oil-producing structures in the Mexial fault zone, and to show how the apparently very irregular well logs in these fields may be use? for the practical interpretation of subsurface conditions. The Mexia oil field, in Limestone County, Tex. (Fig. 1) is closely associated with a fault that trends about 30" east of north and has a displacement of between 200 and 400 ft., with downthrow on the west. Minor slips accompany this major fault, some being roughly parallel to the main break while others are transverse to it. These faults belong to the so-called Mexia fault zone, a belt of fracturing that has been traced in its characteristic features southward to near Kosse, 15 miles south of Groesbeck, in southern Limestone County, and northward at least as far as the Trinity River at the eastern border of Navarro County, and possibly as far north as Hunt and Hopkins counties.2 The Balcones fauil zone, from 30 to 40 miles west of the Mexia fault zone, differs from the latter in that its principal displacement is a downthrow on the east. In this respect, it is exactly the opposite of the Mexia displacement. Between these two zones of major faulting lies a great down-dropped block, or graben, which is broken by numerous minor faults. Oil Fields Associated with Mexia Fault Zone When speaking of oil fields associated with the Mexia fault zone, we refer only to those now producing from the Woodbine sand. In this category belong the Mexia, Currie, Old Richland or Seay-Cranfill, Powell, and New Richland fields, named in the order of their discovery (see Fig. 1). Subsequent development may prove that the gas found in the Boyd Oil Co.'s Connor well, north of Kerens, is coming from another pool in the same fault zone.

Jan 1, 1925

By Charles G. Yale

(San Francisco Meeting, October, 1911.) A FEW years ago somebody connected with one of those self-constituted bodies of unofficial character, like a Chamber of Commerce, Board of Trade, or State Development Board, started a catch-phrase referring to California as " The Land of Sunshine, Fruit, and Flowers," and the railroad magazines and folders keep it steadily in use, working day and night. Yet it altogether ignores the substance which brought the State into the Union, which peopled it, and which made it famous through-out the world. You ladies and gentlemen who have come from what we here call "the East," have in your own States, no matter which one, sunshine, fruit, and flowers. But your Eastern States, having these things as we do, have not the gold that we do. Therefore, the old designation of "The Golden State," applied to California, should be revived, as being the most distinctive term. It is worthy of remembrance, too, that during the dark days of the civil war this State handed over $172,000,000 in yellow gold, and saved the credit of the nation. Gold-mining has been carried on in California since " The days of old, The days of gold, The days of 49," and it still continues. Since that historic year, and up to the end of 1910, the State has produced, in gold alone, $1,530,214,468. Since 1792 the entire United States production of gold has been $8,261,573,500, so that the single State of California has, in that period, produced within $201,144,564 of one-half of all the gold from Alaska, Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, South Dakota, Utah, Washington, and the Southern and scattering States. In other words, all the other 25 gold-producing States of the United States combined

Mar 1, 1912

By K. Harms, T. D. Jones

TO unload large tonnages of lead bullion cast in 100-lb. bars is a problem which has confronted the lead refineries for many years. The bars, on arrival, must be restacked for unloading by truck or hand-charged to charging machines. Selected crews of labor, capable of working at sustained speeds for five- or six-hour periods, are required for this exhausting task. Due to the fatigue involved crew personnel changes rapidly. During the war it became increasingly difficult to maintain crews, especially in critical labor areas, so that the development of casting and shipping ten-ton lead blocks from the smelters to the refineries became a must in our operating program. For many years lead refineries, when making interdepartment or intradepartment transfers, have cast lead blocks weighing five or ten tons which are easily handled by crane by merely attaching the crane hook to a steel anchor embedded in the frozen lead blocks. In previous years, the practice was to use regular smelter slag pots which, due to their rounded shape, produced what were called "buttons" by the refinery personnel. The button-type blocks were unsafe as they rolled and tipped easily and were unsatisfactory for stacking since no piling pattern could be followed. To remedy this situation, flat-bottom molds came into general use and later the bottoms were made concave to prevent slipping.

Jan 1, 1946

By E. A. Nesbitt

The important permanent-magnet alloys 15 years ago contained carbon and depended upon it for their permanent-magnet properties. In recent years great advances have been made in a number of new alloys substantially free of carbon. These include Remalloy,' an alloy of iron, cobalt, and molybdenum, the various iron-nickel-aluminum alloys of the Mishima2 type, and the more recent Alnico V3 in which the best properties are developed by heat-treating in a magnetic field. The Mishima and the Alnico types of alloys are very brittle and after casting must be ground to size. This article describes a permanent-magnet material4 that can be machined as cast, and when handled with some care can be rolled to thin sheet and drawn to fine wire. Optimum magnetic properties are developed by a simple heat-treatment, and at this time the ductility of the alloy disappears. If the cast alloy is heat-treated without cold-working the mag netic energy product is about 1.0 X 106. This material is called Vicalloy I (pronounced vicalloy, V for vanadium, I for iron, and C for cobalt). When the alloy is first hot-worked and then considerably reduced in area by cold-swaging, drawing or grooved rolling, it is found that after heat-treatment the magnetic energy product measured in the direction of previous extension can be increased to 2.0 to 3.5 X 106. These higher values have been obtained only after reductions in area of 75 to 95 per cent, and since the material hardens considerably during working, the reduction ordinarily can be accomplished only in fine wires, although larger sizes can be reduced by the use of powerful machinery. When the material has been cold-worked in such a manner as to improve its energy product substantially, it is called Vicalloy 11. Commercial use of Vicalloy has been made in the recording of speech. Tape 0.002 by 0.050 in. has been found superior in quality to all others tried, and is now used in the Western Electric Mirrorphone 5 In a variety of forms Vicalloy I or I1 is useful in many laboratory instruments, and in experiments in which the sizes and shapes required cannot be obtained with the other more brittle permanent-magnet materials. In 1936, during a study of other age-hardening magnetic systems, it occurred to the author that some of the iron-cobalt-vanadium alloys might be suitable for permanent magnets. The proportions of iron, cobalt, and vanadium were varied and a range of alloys of particular interest was found, as shown by the indicated area in Fig. I. The limits of this range of composition are 30 to 52 per cent iron, 36 to 62 per cent cobalt, and 4 to 16 per cent vanadium. The compositions indicated by points outside this area were also tested. Preparation and Properties OF Vicalloy I The alloys were usually cast in graphite molds into bars 3/4 in. in diameter and

Jan 1, 1946

By E. A. Nesbitt

The important permanent-magnet alloys 15 years ago contained carbon and depended upon it for their permanent-magnet properties. In recent years great advances have been made in a number of new alloys substantially free of carbon. These include Remalloy,' an alloy of iron, cobalt, and molybdenum, the various iron-nickel-aluminum alloys of the Mishima2 type, and the more recent Alnico V3 in which the best properties are developed by heat-treating in a magnetic field. The Mishima and the Alnico types of alloys are very brittle and after casting must be ground to size. This article describes a permanent-magnet material4 that can be machined as cast, and when handled with some care can be rolled to thin sheet and drawn to fine wire. Optimum magnetic properties are developed by a simple heat-treatment, and at this time the ductility of the alloy disappears. If the cast alloy is heat-treated without cold-working the mag netic energy product is about 1.0 X 106. This material is called Vicalloy I (pronounced vicalloy, V for vanadium, I for iron, and C for cobalt). When the alloy is first hot-worked and then considerably reduced in area by cold-swaging, drawing or grooved rolling, it is found that after heat-treatment the magnetic energy product measured in the direction of previous extension can be increased to 2.0 to 3.5 X 106. These higher values have been obtained only after reductions in area of 75 to 95 per cent, and since the material hardens considerably during working, the reduction ordinarily can be accomplished only in fine wires, although larger sizes can be reduced by the use of powerful machinery. When the material has been cold-worked in such a manner as to improve its energy product substantially, it is called Vicalloy 11. Commercial use of Vicalloy has been made in the recording of speech. Tape 0.002 by 0.050 in. has been found superior in quality to all others tried, and is now used in the Western Electric Mirrorphone 5 In a variety of forms Vicalloy I or I1 is useful in many laboratory instruments, and in experiments in which the sizes and shapes required cannot be obtained with the other more brittle permanent-magnet materials. In 1936, during a study of other age-hardening magnetic systems, it occurred to the author that some of the iron-cobalt-vanadium alloys might be suitable for permanent magnets. The proportions of iron, cobalt, and vanadium were varied and a range of alloys of particular interest was found, as shown by the indicated area in Fig. I. The limits of this range of composition are 30 to 52 per cent iron, 36 to 62 per cent cobalt, and 4 to 16 per cent vanadium. The compositions indicated by points outside this area were also tested. Preparation and Properties OF Vicalloy I The alloys were usually cast in graphite molds into bars 3/4 in. in diameter and

Jan 1, 1946

By J. F. Pierce, S. M. Enterline

Since January 1959 a zinc refiner of novel design has been in operation at Blackwell, Okla., producing 99.995+ zinc from the output of the Blackwell horizontal retort smelter. The refiner is a continuously operated, pyro-metallurgical unit with principal dimensions horizonhl permitting one floor operation. It is very ruggedly constructed. Furthermore it is not subjected to deterioration from high concentrations of iron in the feed metal because the boiling units are separate from the rectification columns and constructed with silicon carbide brick arches through which the heat is transferred radiantly to the zinc. A zinc refiner of novel design has been in operation since January 1959 at the Blackwell, Okla. plant of the Blackwell Zinc Co., Inc., a wholly owned subsidiary of American Metal Climax, Inc. Developed by the company's technical and operating staffs, the new refiner produces special high-grade zinc (nominally 99.995+ pct Zn) from the prime western1 slab output of the Blackwell horizontal retort smelter. The refiner is a continuously operated, pyromet-allurgical, high-capacity unit employing fractional distillation to separate zinc from its impurities, consisting principally of lead, cadmium, and iron. In prime western slab, these elements may vary in concentration from 0.005 to 1.6 pct. Table I shows the impurities usually encountered in the Blackwell prime western metal fed to the refiner together with their boiling points and vapor pressures at 907oC. The commercial pyrometallurgical smelting processes for extracting zinc from ore include distillation from retorts and a limited degree of refining can be accomplished by redistillation in similar retorts. To achieve special high-grade purity, an impractical number of batch redistillations would be required, however, with an accompanying loss of much metal. A continuously operated and integrated unit is required in which fractional vaporization and condensation can take place in a large number of stages. The first commercial continuously operated unit was developed by the New Jersey Zinc Co.4 In the separation of any two substances the degree of separation is limited if a mixture exists having a constant boiling point. The Zn-cd5 and Zn-pb6 systems contain no constant boiling points and hence these metals may be separated to any degree of purity. Basically, the pyrometallurgical refining of zinc involves three steps: a) iron, copper, and other metals having no appreciable vapor pressures at 907ºC concentrate in the bath when the impure zinc is boiled, b) lead, bismuth, antimony, and other metals having boiling points above but closer to that of zinc are selectively condensed from the vapor boiled from the bath, and c) cadmium and other metals having lower boiling points than zinc are fractionally distilled by reboiling and subsequent condensation of the zinc from the vapor. The boiling and condensation of zinc must be conducted in vessels constructed of materials which are refractory at the temperature involved (907 ºC) and it is highly desirable that they also be resistant to attack by the various metals. This requirement dictates construction from relatively small, simply shaped pieces which limits the pressures which may be employed to avoid leakage through the numerous joints. Stresses induced must be limited essentially to compressive ones and suitable provision must be made to permit thermal expansion of the components in order to minimize these stresses. Where heat is to be added for boiling or removed for condensation, refractory material through which the heat flows must have a high thermal conductivity. Silicon carbide is highly conductive but is subject to attack by iron and is expensive compared to other commonly employed refractories. A hard, dense aluminous fireclay is well suited to contain these metals where high thermal conductivity is not required. Zinc will penetrate the pores of fireclay brick but only to a limited depth in an exterior wall and has little effect other than an increase in weight and conductivity. The design objectives of the Amax refiner were: a) to achieve a long life by heavy, rugged construction and by employing silicon carbide refractories only where required for heat conductivity and not in contact with liquids of high iron concentrations, b) to simplify operation, manning and control by essentially horizontal construction, and c) to obtain high capacity in a single unit. DESCRIPTION Flow of metal through the Amax refiner is shown diagrammatically in Fig. 1 and schematically in Fig. 2.

Jan 1, 1963

By J. J. Lander, L. H. Germer

MOLYBDENUM and tungsten have desirable corrosion and temperature resistant properties, but the metals in bulk are expensive and their fabrication is difficult. Such considerations led to a search for a method of plating them upon base metals. This search was successful and led furthermore to a number of developments which could not have been foreseen. Neither pure tungsten nor pure molybdenum has been electroplated successfully, although the literature of electroplating is liberally sprinkled with the description of unsuccessful attempts. The process of plating these metals by thermal reduction of their halides has achieved only limited usefulness because of technical limitations and because of limited range of product quality. Plating by thermal decomposition of the carbonyls does not suffer from limitations of the same sort and the properties of the plate are readily controllable. This paper describes the plating of molybdenum and tungsten, and of compounds and alloys of these metals, by pyrolysis of their carbonyl vapors. Chromium also has been plated in this manner, but the experiments upon chromium have been less extensive and the results much less satisfactory. Probably the most important of the products which we have obtained are the alloys with carbon, and the carbides of the metals. Either molybdenum or tungsten can be deposited upon a base metal as a coherent and adherent coating. By adjusting the plating condition the carbon content of the coating can be made to have any value from substantially zero to about 35 atomic pct. The hardness is dependent primarily upon the amount of carbon in the plate and can be regulated over a very wide range, some coatings containing considerable carbon being harder than sapphire. In addition to products already known this method of plating has yielded new carbides of molybdenum and tungsten and alloys supersaturated with carbon. These new products are possible because, in the process of plating, carbonyl can be decomposed at temperatures as low as about 150'C, and thus in the presence of other substances reactions occur which could perhaps not be produced in any other way. In addition to carbides and alloys with carbon, sulphides and oxides of molybdenum and tungsten have been produced and studied. There are certain other advantages of the carbonyl method of plating. It is not required that the base have good electrical conductivity as in electrochemical processes, and the base need not have the temperature stability required in plating from a halide. Thus low melting glasses, as well as other ceramics, can be plated almost as readily as metals. In particular, the plating of glass with

Jan 1, 1947

By P. J. Clifford, A. B. Brown

The development of computerised mine planning has been hindered by the cost of processing the large data bases associated with mineral deposits and the inherent inconvenience of performing an interactive process on a time-shared computer. A dedicated computer is ideally suited for the purpose but reasonably priced micro/mini-computers have not had the capacity to store the volume of data or the processing capability required. Hardware development has cleared the way for the development of truly interactive mine planning software, covering the complete range of activities associated with mine planning, from geological assessment to short-term scheduling of operations, incorporating them into a single system using a common database. The integrated system, comprising software and dedicated hardware, adds previously unattainable speed, flexibility and clarity to the planning process because it has been tailored exclusively for that purpose.

Jan 1, 1983

By Richard P. Rothwell

The device to which I desire to call the attention of the members of the Institute consists of a water-tight caisson, which is connected By a stuffing-box with the tube to be laid, and the caisson is pushed forward with hydraulic jacks set against the end of the tube. The tube is of hard white iron, cast in chills in segments. These segments are carried from shore through the tube itself, in which a track is laid as the work progresses, and the segments are bolted together in the caisson, where there is ample room to work and proper appliances for handling heavy weights. As each segment is bolted on, the jacks are set against its forward end, and when the whole ring is complete, the caisson is pushed forward by the jacks, a trench having been dredged out in front of it, or, in very loose ground, jets of water under a heavy pressure can be thrown out to loosen the ground in front of the caisson. The direction in which the caisson is pushed is completely under control, and both the caisson and the tube are loaded to the amount necessary to overcome their buoyancy. I understand that Mr. H. H. Hall, of New York, the inventor, is negotiating for the construction of a 16-foot tunnel of this kind across the Straits of' Northumberland, between Prince Edward Island and the main-land, and for tunnels in several other places. 4 One of the most interesting uses of this system is in laying water mains out into lakes. The work can be carried on without inter-

Jan 1, 1886

By G. F. Comstock

These notes should be considered as a further discussion of Mr. S. W. Miller's paper on "Some Structures in Steel Fusion Welds."l In that paper and the resulting discussion, several conflicting opinions were expressed as to the identity of the needles or small crystals present in oxyacetylene and electric welds. An interesting specimen of an electric weld examined by the writer seems to afford new evidence regarding the needles, that may be worth presenting at this time. The specimen consisted of a piece of 3/8-in. (9.5-mm.) steel plate, about 21/4 by 13/4 in. (5.7 by 4.5 cm.) in size, on which some iron had been deposited by arc-welding to a depth of about 3/16 in. (4.7 mm.). The weld appeared to be a very good one, with no noticeable break or boundary between the plate and the deposited iron. Sections for microscopic examination were cut in three planes at right angles to each other through the deposited metal, two of these sections also extended through the steel base. After polishing in the usual way, the microscope showed that the deposited metal was full of very small, round, gray, oxide spots, while the steel plate contained quite a number of alumina inclusions and a little slag. The sections were etched with nitric acid in ordinary alcohol, and structures similar to those described by Mr. Miller were then displayed. Fig. 1 shows the typical appearance of the deposited metal, which was quite uniform in all three of the planes examined. The round dark-gray spots are oxides, and the pale angular crystals are evidently what Mr. Miller called cem-entite and Mr. Jeffries martensite, while Mr. Ruder and Professor Boyls-ton think that they might be nitride. The boundary between this structure and the steel base was sharply defined under the microscope. Fig. 2 shows the structure of the plate just under the weld; this is almost martensitic and resembles a coarse-grained casting. This coarse cast structure soon became finer as the distance from the weld increased, finally becoming very fine, with numerous small particles of sorbite. This very fine structure, shown in Pig. 3, became coarser in turn and finally merged into the original normal structure of the steel plate, shown

Jan 1, 1920

By H. M. Chance

The recent discoveries of important new gold-districts in limestone, granite, sandstone and porphyry have awakened the more intelligent class of prospectors to a realization of the fact that ally rock may be gold-bearing; that from the appearance of a rock it is impossible to judge whether it carries gold or not; and that gold-ores may occur in any geological formation. As a rule, the professional prospector limits his search to ores and conditions with which he is more or less familiar, and to formations which he regards as favorable to the occurrence of such ores. Hence it often happens that while the very thing he is searching for is in plain sight, he fails to recognize it, and some other individual, possibly less intelligent but more lucky, stumbles blindly upon it. Beginning with the discovery of the California placers by the finding of gold in the tail-race of Sutter's saw-mill—a tale so often told that nearly all have read it in some form—and following the discovery of district after district down to the present time, one is forcibly impressed by the fact that many of the important districts have been discovered by accident; that many such discoveries have been made by unskilled or inexperienced prospectors, and some by persons having no knowledge whatever of prospecting. Thus, the recent Klondike discoveries are said to have been made by a poor salmon-fisherman, who, with his Indian wife, was hunting, not for gold, but for good fishing-grounds; the Comstock lode is said to have been accidentally discovered, and the Ragged Top district in the Black Hills and the Pearce mine in Arizona* are recent notable instances of the same kind.

Jan 1, 1900

By William A. Kapp

INTRODUCTION Coal is being mined from beneath residential areas, structures, bodies of water and other surface features in the coalfields to the north, south and west of Sydney. The particular problems faced by mine operators in these areas vary considerably due to differences in the overlying strata, the variation in the depths of cover and also depend on the number of seams being mined. Detailed subsidence work first commenced in the Southern Coalfield in 1965 and is now being carried out over areas of extraction at roost collieries. The analysis of the results of the early investigations and of the work which continues in other areas has shown that there is a consistent relationship between subsidence and mine geometry and has led to a reliable empirical method for the prediction of subsidence. In addition, particular aspects of each of the studies in the Southern Coalfield results in a clearer understanding of strata movements and of the resulting subsidence. The features of a subsidence trough apply generally to all areas but the magnitudes of specific features vary according to the stratigraphy of the particular coalfield. The aim of the subsidence work is to quantify the effects of subsidence for a range of mining geometries and mining conditions to enable the maximum safe recovery of coal from beneath surface features. The importance of local subsidence investigations is becoming more evident to mine operators and to authorities or organisations with surface interests. The subsidence work also provides important information on the stabilities of pillars of coal which remain unmined between panels of extracted coal. These pillars are not extracted either because of poor mining or geological conditions, or because pillar extraction is not part of the particular mining operation. Subsidence studies over these coal pillars clearly establish whether the pillars have remained stable or have failed to support the overlying strata. With subsidence studies continuing over several years, it is possible to assess the stabilities of these pillars on a long term basis. BACKGROUND TO THE STUDY OF SUBSIDENCE Geographical setting Most of the black coal production in Australia comes from the Sydney Basin. The coal seams extend for approximately 350 km along the coast of New South Wales and inland for distances up to 150 km. The City of Sydney is located near the centre of the coastal extent of the Basin where coal has been mined at a depth of 900 m. The Sydney Basin is part of the Main Coal Province of NSW and is divided into several coal- fields. The Southern Coalfield to the south of Sydney contained 15 operating mines and produced 12.7 million tonnes of raw coal during the 12 months to June 1981. The collieries discussed later are shown in Fig. 1. The prominent topographical feature of the area is the Illawarra Escarpment which rises to 400 m above sea level, or 300 m above the coastal strip along the South Pacific Ocean. The escarpment is mainly sand- stone and the weathering of the cliff line has resulted in a covering of talus material at its base. Several collieries are located near the seams which outcrop along the escarpment. The city of Wollongong is located in a scenically attractive area on the coastal plain. The suburbs of Wollongong extend north along the coastline, south to beyond Lake Illawarra and west to the lower slopes of the escarpment. The Illawarra Escarpment forms the eastern boundary of the Woronora Plateau. On a regional scale the surface dips gently to the west and thus forms a watershed for the rivers, most of which flow in a general north westerly direction, sometimes forming steep gorges in the sandstone. These rivers join the Nepean and Hawkesbury River system and flow into the Pacific Ocean north of Sydney. Seven dam have been constructed over the Southern Coalfield (Fig. 1) and with one large dam further to the west, their stored waters provide the needs of the Cities of Sydney and Wollongong and the surrounding districts. A large part of the area affected by mining is the undeveloped bushland of the associated catchment areas. In general no special precautions have been required with respect to subsidence with the exception of the dam structures and stored waters. With the increase in coal mining activities and the expanding residential development south of the City of Campbelltown in the outer Sydney Metropolitan area, subsidence is becoming an increasingly important area of research. Structures which have been affected or considered are townships and extensive residential areas, buildings of historical importance, major tollways, and a high pressure natural gas pipeline. The subsidence effects of mining beneath natural features within national parks is coming under study as mining approaches these areas. Geological setting The coal seams of the Southern Coalfield lie within the Illawarra Coal Measures. They contain high rank coking coal used in the local steel industry and for export. The Bulli Seam is mined extensively through- out the Southern Coalfield with the lower Wongawilli Seam being second in importance with regard to coal production. The top of the Bulli Seam is taken to be the marker horizon between the Permian Coal Measures

Jan 1, 1982

By R. C. Buehl, J. P. Morris

F. D. Richardson—The authors are to be congratulated on this further contribution to our knowledge of the thermodynamics of the interaction between sulphur and carbon and silicon in liquid iron. As the authors state, the influence of carbon and silicon on the activity coefficient of sulphur in liquid iron is clearly of great importance in the blast furnace, since it must cause a three to fourfold improvement in the partition of sulphur between slag and metal. The influence of increasing temperature in further increasing the activity coefficient of the sulphur in the metal in the blast furnace by increasing the carbon content is also of interest. This effect, however, is probably only part of the reason for the general observation in blast furnace practice, that the sulphur content of the metal is lowered by increasing temperature. Other contributing factors are the lowering of the oxygen potential in the presence of carbon by increasing temperature and the probable increase in the activity coefficient of the lime in the slag for the same reason. The former of these effects, which works via the (CaO) + [S] = (CaS) + [O] equilibrium, might possibly account for a 70 pct improvement in the sulphur partition and the latter might give a further 50 pct improvement. C. Sherman—I would like to compliment the authors on their very careful research. If I may, I would like to show results of calculations on the carbon-sulphur-iron system similar to the ones that were shown in our paper for the silicon-sulphur-iron system. For Fe-S-C ternary system k=PHgs/PH2 x 1/(f1°) (f2°) (%S) where fs = sulphur activity coefficient fs' = fs for Fe-S system of equal pct S f3° = f2/f2 for Fe-S-C ternary system This same analysis has been used on other systems, but the results shown in fie.- 7 are for carbon and silicon. L. S. Darken—I would like to make two brief comments in addition to complimenting the authors on an apparently very precise and accurate investigation. The first is that the present work is in agreement with a calculation by Larsen and myself." Our calculation (much less precise than the present work) was based on: (1) Unpublished work on the sulphur content of molten iron (1.5 pct at 1500°C) in equilibrium with graphite and an iron sulphide slag; (2) the distribution coefficient of sulphur between slag and carbon-free liquid iron. We expressed the result in a form equivalent to log 7. = 0.18 [%C] which gives an activity coefficient (?s.) of sulphur only slightly higher than the authors find and certainly within the precision of the earlier work. My second comment concerns the correlation of the thermodynamic findings with atomistics. A rough pic- ture of the atomic arrangement in the liquid solution is rather easily conceived for this particular liquid solution containing iron, carbon, and sulphur. Carbon has a very much stronger affinity for iron than for sulphur. Hence we may conclude that a sulphur atom will but seldom be adjacent to a carbon atom—since this would be a position of high energy. From the metallic radii of iron and carbon we know that six iron atoms pack neatly around one carbon atom. Thus each carbon atom in retaining this shell of iron atoms (which latter may not be replaced by sulphur on account of the high energy requirement) decreases the available positions for each sulphur atom by six. Hence each atomic percent of carbon decreases the equilibrium sulphur content by 6 pct (of itself). Or, at low concentration each atomic percent of carbon increases the activity coefficient of sulphur by 6 pct. This is in good agreement with the observed increase (6 or 7 pct at low carbon content). It is indeed gratifying to find a case where, by such simple reasoning, quantitative agreement is found between precise data and the modern picture of the atomistics of the metallic state. J. P. Morris (authors' reply)—We would like to point out that there is an error in the equation on p. 322 of the paper. The third equation should read: ½S2 (gas) + H2 (gas) = H2S (gas) The authors wish to thank everyone for the interest they have shown in the paper. In regard to the general observation in blast furnace practice, that the sulphur content of the metal is lowered by increasing the temperature, Dr. Richardson is correct in stating that the cause can be attributed only in part to the increase in activity coefficient of sulphur resulting from the rise in carbon plus silicon content of the metal with rise in temperature. However, this factor is probably an important one. The results of one experiment, performed since this report was written, indicate that at a constant temperature the addition of silicon to a melt saturated with carbon causes an increase in the activity coefficient of sulphur even though the carbon solubility is lowered. In this test, 2.5 pct silicon was added to a melt saturated with carbon and maintained at 1400°C. Although the carbon content dropped from 4.85 to 4.1 pct, the activity coefficient of sulphur was increased by about 20 pct.

Jan 1, 1951