Search Documents

By E. I. Larsen

Powder metallurgy has been described as being "as old as the pyramids and yet as new as the latest bomber." While this may be true literally, it has been only in the last Io or 1 5 years that widespread use has been made of this method of fabricating various articles One of the first items fabricated by powder metallurgical methods on a commercial scale was electrical contacts, which were fabricated from metal powders as early as 1920. The reason why these contacts have been made for so many years by powder metallurgy is because the compositions of most of these materials arc such that they could not be made by the conventional methods of melting, casting, rolling, drawing, etc. Classes of Contacts In general, electrical contacts fabricated from metal powders fall into two classes, both from the point of view of the method of fabrication and the components that make up the chemical composition. One class is composed of silver or copper and a refractory metal such as tungsten, molybdenum, or compounds thereof such as carbides. The second class contains a predominant amount of silver and a semi-refractory material such as cadmium oxide, nickel, cobalt, or graphite. Electrical contacts of the first class have been developed primarily as facing materials for heavy-duty circuit-interrupting devices. This class of material unites the high melting point, high boiling point, great resistance to electrical erosion, and the refractory characteristics of molybdenum, tungsten, or their carbides with the high thermal and electrical conductivities and low contact resistance properties of silver or copper. The second class of material is used for lighter duty or specialized applications such as heavy-duty, direct-current aircraft relays. Varieties Electrical contacts fabricated from metal powders are made in a wide variety of compositions, shapes, and sizes. In general, the sizes of electrical contacts fabricated from powders vary from contacts weighing approximately 0.001 oz. up to those weighing 3 to 4 Ib., the contacting face being as small as 0.001 sq. in. up to approximately 6 sq. in. in area. The shapes consist of: sound or rectangular buttons, some of which have radii or bevels on the contacting faces; rings, cups, rectangular bars, the contact face of which may have a radius across the width and/or at one end; and form-pressed pieces of a wide variety such as angles, both acute and obtuse, irregular shapes comprising a radius blended into a flat, which in turn may have steps. The size or shape of the contact is dictated principally by the mechanical design of the manufacturer, who in turn may have problems to be met such as: (I) size, weight, or space limitations; (2) electrical conditions such as blowout coils arc chutes, baffies, gas passages.

Jan 1, 1945

By H. W. Turner

THE axis of the middle portion of the Ural mountains is made up chiefly of highly compressed igneous and sedimentary schists, considered of Devonian age by the Russian geologists, with large areas of serpentine (peridotite originally) gabbro, etc., intrusive in the schist series. In addition there are large areas of probably older granitic and gneissic .rocks. The nickel deposits referred to in this paper are found in the Devonian schists and their associated igneous rocks. The gabbro-peridotite intrusions probably took place in late Devonian or early Permian time, inasmuch as the Permian and Carboniferous beds lie at gentle angles on the Devonian series on the west slope of the Urals. Perhaps the first attempt to work a nickel deposit in the Urals was made about 1866 in the Revdinsk district, which is situated southwest of Ekaterinburg. I was informed by a Russian that a wet method of extracting the nickel was tried but was not a commercial success. This deposit has been described by Müller,1 Foullon,2 and Karpinski.3 Beck4 gives an abstract of these papers.

Jan 2, 1914

By Hadyn W. J. Wren

The practical experience obtained from designing and commissioning of fully controlled coal preparation plants, using centralised mini computers is discussed. The importance of defining a workable operating philosophy is highlighted with particular reference to the problems associated with trying to achieve a total 'hands off' concept. These experiences with a centralised computer controlled system have led to a deeper understanding of the interaction between the operation and the control system and the role of local control and management information within the overall control philosophy of a highly automated process plant. The utilisation of an extensive fully distributed microprocessor control system with over 6500 digital and analogue signals split into six autonomous areas with a supervisory system to provide operator interface is described. The important aspects of project definition and design needs are outlined with particular regard for achieving maximum efficiency with minimum complexity. Views of future trends are offered, based on the experience of both centralised computer and distributed processor systems.

Jan 1, 1984

By E. S. Machlin

THE function of this paper is to present certain results based on the fact that the strain energy arising from the solution of out-of-size solute atoms into the solid matrix is free energy and not internal energy, and that this strain energy is almost wholly shear strain energy as Zener1 pointed out. One natural consequence of this fact is an expression for the excess entropy of mixing due to the strain energy. Also, a derivation of the integral molar free energy of mixing partitioned to strain energy will be made using the model of Lawson2 and thermodynamics. This derivation has the advantage of showing in a simple way the assumptions involved in Lawson's treatment. The excess entropy of mixing partitioned to strain energy can be derived in two ways. The first way makes use of the fact that the strain energy is almost wholly in the form of shear strain energy. In this case, as Zener1 pointed out, the change in entropy due to the addition of shear strain energy is to a first approximation given by ?S/?? p,T = - ?lnµ/?T p,? Hence, the excess entropy of mixing partitioned to strain energy will be given by Sx ? = ?S/?? p,T Gx ? = - ?lnµ/?T p,? Gx ? where, Gx ? is the relative integral molar free en- ergy partitioned to strain energy; S is the entropy; is the shear strain energy; µ is the shear modulus; T is the absolute temperature; p is the pressure; and ? is the shear strain. Zener,1 as well as others, has pointed out that the shear strain energy stored in a compressible isotropic solid due to the insertion of an off-size incompres-sible sphere into a spherical hole in the solid, is approximately given by 2/3 µ/O (O°I - O)2 where a is the volume of spherical hole and no , is the volume of sphere. If we now consider the introduction of one mol of such spheres into an infinite volume of solid, then the relative partial molar free energy excess due to strain energy alone is GM ? = 2/3 µ/v (v ° 1 - v)2 where v is the molar volume of solvent and v°1, is the molar volume of pure solute type 1. Let us consider that these spheres are the two types of atoms in a binary solution, then there will be a similar relation for solute 2. The total relative integral molar free energy excess due to strain is then, to the approximations stated above GM ? = GM ? x1 + GM2 ? x2 = 2/3 µ/v [(v ° 1 - v)2 x1 + (v ° 1 - v)2 x2]. Lawson's relation for the strain energy can be de-

Jan 1, 1955

FRED TURRELL GREENE Fred Turrell Greene was born in Brooklyn, N. Y., Nov. 22, 1872. His father, William A. Greene, was born in Providence, R. I., and his mother, Angenora Semlear, was born in Brooklyn, N. Y. Fred's early school clays were spent in Boston, whence his father moved to Canada in 1882. Attending first the Collegiate Institute in Toronto, .then the High School at Berlin (now Kitchener), Ontario, where he graduated, Fred progressed to the Toronto University and the Michigan College of Mines, at Houghton, where lie graduated in 1897. He secured employment almost immediately at Butte with the engineering force of the Boston & Montana Consolidated Silver Mining Co., under Chas. S. Batterman. In 1899 he went to Rossland, B. C., where he spent more than a year as mining engineer and assistant superintendent of the War Eagle Consolidated Mining and Development Co. and the Center Star Mining Company Ltd. Returning to Butte in 1900, he acted as assistant geologist for the Anaconda Copper Mining Co. until 1906, when he filled a similar position in St. Paul with the Great Northern Railway for about two years. From 1908 until his tragic death on Christmas day, 1917, his headquarters were in Butte, where he enjoyed an excellent reputation -as consulting mining engineer, with a rapidly widening circle of clients. During the past four years he had been consulting engineer for the Elm Orlu and other mines controlled by Hon. W. A. Clark, and was in charge of underground developments and law-suit preparations for the celebrated apex case between the Elm Orlu and the Butte & Superior companies. At the time of his death he was in charge of similar work for the Utah Metals Co., in connection with their mines at Bingham, Utah. He was also for some years active in the Coeur d'Alenes, as consulting geologist for the Federal and other companies there, and was considered an authority on this as well as the Butte district. Mr. Greene was unmarried, and is survived by his parents, a younger brother, who is in the army, and one sister, Mrs. James A. Hatch, of New York. Some of the most important and valuable ideas regarding the nature and origin of copper ores have originated in Butte, since that district is not only one of the greatest examples of mineralization known in any land, but has gone through a long course of mining litigation, and was, one of the first to be studied intensively by geologists. In connection with the early investigations, as well as with the most recent in that camp, Mr. Greene played an important part. His conscientious devotion to his duties and his intelligent handling of the problems presented for solution sufficiently explain the esteem in which he was held by his employers and his professional associates.

Jan 5, 1918

By R. M. Briney

A RETURN to nonwar conditions characterized the year 1946. The acquisition and forced use, under Government auspices, of low-grade and uneconomic ores, both foreign and domestic, ceased in 1945, but there was some carry-over into the early months of 1946. The world shipping situation delayed the procurement of some foreign ores, but conditions were improving by the end of the year. No actual shortage of any important alloy was experienced, hence the industry was able to make prompt shipment of orders placed. Price levels of ferroalloys, which had remained virtually constant through the war years, were forced upward, with increases on specific products as conditions necessitated. Standard ferroman-ganese and low-carbon ferrochrome were notable exceptions in that their price did not change. No new ferroalloy smelting plants were constructed. The Defense Plant Corp.. sold the works at Ashtabula, Ohio, to the Electro Metallurgical Co. A new type of ferroalloy furnace was described at the Birmingham meeting of the Electrochemical Society. Known as the "Elkem Rotary Furnace" it is distinguished by a rotating shell. The whole furnace, including shell, refrac-

Jan 1, 1947

By Paul C. Ragland, P. Geoffrey Feiss

The Piedmont province of the southern Appalachians is the focus of interest for many exploration geologists. In the past, only those deposits with significant surface exposure were exploited. Thus, few deposits have been found and relatively little exploration has been conducted in recent years. Modern geochemical and geophysical techniques can alleviate this problem of concentrating on exposed ore bodies by allowing us to "look through" the soil and saprolite to detect the presence of significant mineralization at depth. This paper will attempt to evaluate the feasibility and effectiveness of several geochemical exploration techniques in the Piedmont province of Cabarrus and Stanly counties, N.C. The area chosen for study is shown in Fig. 1, lying almost wholly within the Mt. Pleasant quadrangle, N.C. The area is on the eastern boundary between the Charlotte belt, a zone of plutonic and intermediate grade metamorphic rocks, and the Carolina Slate belt, a series of complexly interbedded volcanic and sedimentary rocks of predominantly low metamorphic grade. The area is considered to be an early Paleozoic active, continental margin. 1 As is typical of most of the piedmont, outcrop is sparse. Figure 2 is a sketch map of the general geology of the area under study, showing the Charlotte belt rocks in the north-western quadrant and slate belt rocks to the east. Within the area are a number of old mines and prospects, the most famous of which are the Furniss and Phoenix mines in Cabarrus County. All are reported to have contained Au and Cu. Ag and Pb were reported from some. A summary of the deposits is given in Table 1.

Jan 6, 1979

By Philip Henry

THERE is a difference of opinion among engineers on the subject of depreciation in general, and still more on its application to any given case. The committee which was appointed by the American Society of Civil Engineers to make a report on Valuation of Public Utilities, states "There is no subject connected with valuation about which there are more diverse views than those relating to depreciation;" and in the discussion which took place upon the presentation of the preliminary report of this committee in January, 1914, that part of the report dealing with depreciation called forth more discussion than any other. From this discussion it was evident that the word " depreciation" was not always used in the same sense, so it is quite important that some definition be adopted. As this paper relates to the proper method of treating depreciation by corporations or individuals operating oil properties, both of which must make a return of annual net income to the government in connection with the income tax, it will be in order to adopt the definition of the Internal Revenue Bureau. Under date of Mar. 29, 1910, the Commissioner of Internal Revenue of the Treasury Department stated "Deduction on account of depreciation of property must be based on lifetime of property, its cost, value and use." Again, on Form 1035, "Return of Annual Net Income" for miscellaneous corporations (Section 2, Act of Congress approved Oct. 3, 1913), a deduction from gross income is allowed for "Total amount of depreciation for the year." This item is defined more particularly as follows: "The amount claimed under Item No. 5 (b) for depreciation should be such an amount as measures the loss which the corporation actually sustains during the year in the value of buildings, machinery, and such other property as is subject to depreciation on account of wear and tear, exhaustion, or obsolescence. The amount taken credit for on this account in order to be allowable should be so entered on the books as to constitute a liability against the assets of the corporation. The amount claimed under this item should not cover losses in the value of stocks and bonds. Decrease in the book value of securities owned, so far as such decrease represents a decline in the actual value of such securities, should be deducted under item 5 (a) of the return.

Jan 1, 1915

By E. T. Knight, John D. Gill

Much has been written and said concerning the alleged wasteful and uneconomic use of natural gas and petroleum. Espccially condemned has been the use of natural gas for the production of carbon black and the use of heavy fuel oil under steam boilers.' The critics of these usages of gas and oil have sought to make effective their verbal attacks on the industry by the repetitive expression of the words "inferior" and "superior" uses2 of petroleum. Thus, to employ natural gas for residential heating was to use it in a superior way; to use it for the production of carbon black was to use it in a wasteful and uneconomic way. To use petroleum for the production of automotive fuel was to use it in a superior way; to employ it as a residential fuel and as the prime source of power in an industrial plant was to use it in an inferior and uneconomic way. No doubt the objections to such employment of gaseous and liquid natural hydrocarbons originated in the belief that natural gas and petroleum are limited, nonregenerative mineral resources, and that the functions they perform can be just as well performed by other natural resources like coal13 of which practically unlimited reserves are known. The generations that have dominated each of the last four decades have counted reserves4 of petroleum in terms of a few years supply. Meanwhile, domestic demand for motor fuel rose spectacularly from a few million barrels in 1900 to more than 500,000,000 bbl. last year.5 The more imaginative and vocal critics drew startling word pictures of the catastrophe of 25,000,000 motor vehicles made useless and of the great automotive manufacturing and allied industries brought to an untimely end, and millions of workers left hopelessly unemployed by what they called the deplorably rapid depletion of the petroleum reserve. Many of the critics have been sincere advocates of the conservation of natural resources; many others, and in recent years probably the majority, have espoused the doctrine of conservation to promote their own self-interest rather than that of the public. The latest advocate of severe restriction in the use of petroleum for the alleged purpose of conserving the petroleum resource proposes to achieve that end by a bill,6 now before

Jan 1, 1938

By Harold H. Haman

In view of Twentieth Century advances in mineral dressing technology, most modern metallurgists would be inclined to class jigging as an early, somewhat primitive, representation of their art. The practice of metallic sulfide concentration by jigging is becoming rare. This is so, in part, because the type of ore amenable to the process is becoming rare. It is appropriate, however, that this symposium recognize that a significant contribution of domestic zinc remains dependent upon coarse preconcentration by jigging, and that the state of the art be described even though the theory and applications are already well delineated in technical literature. One of the few areas still using jigging as a major concentrating process is The Upper Mississippi Valley. AREA HISTORY AND JIGGING The Upper Mississippi Valley (UMV) has produced one billion dollars worth of zinc and lead at current prices. The district includes the southwest part of Wisconsin, the northwest corner of Illinois and an adjoining narrow strip of Iowa. Within a total area of 4,000 square miles, important sub-districts cover about 400 square miles. As is widely known, early mining in this district involved shallow lead---crevice deposits of galena that were very selectively mined, hand sorted and cleaned, and then smelted at or near the site. The district has produced almost a million short tons of metallic lead, a very large part of this during the fifty- year period following 1830. Zinc mining began at the end of the civil war, but at a very low rate until about 1905.

Jan 1, 1970

By N. H. Mannakee

[Secretary's Note.—At the Spokane meeting of the Institute, in discussion of President Brunton's address on "Modern Progress in Mining and Metallurgy in the Western United States," and at the request of members present, Mr. Ayres gave an oral account of his new separator, which is here published as an independent paper, partly because of its inherent importance and partly because it describes an improvement which did not originate in the Western United States, and therefore does not fall, strictly speaking, under the title of President Urunton's address.—R. W. R.] A brief history of the growth of the anthracite-coal preparation will give a better view-point from which to judge the present problem of separating slate from coal. At the beginning of the commercial value of anthracite, 70 years ago, only the pure portions, or " splits," of the veins were mined and shipped to market, and without any preparation or screening other than the selection, while loading, of the glassy lumps, and the rejection of the fine material and the slate that had strayed accidentally into the coal. The next step was the crushing or breaking of the coal (hence the name "breaker" as applied to the preparation-building), and the sizing of it by means of bars or revolving screens. This stage of its development marked the advent of the " breaker-boy " as a slate-picker, with his ever-increasing capriciousness. As the richer veins or a splits " became exhausted and the market demanded a still greater output, the less-pure " splits " and the thinner veins were utilized to produce the coal. Carrying as they do a far greater percentage of impurities, particularly when removing the pillars, it became necessary to build new and better equipped preparation-plants. Finally, we are now at the highest stage of complicatioii yet known to the art of coal-preparation. We are dealing with varying specific gravities, frictional difference, hardness, structure, and form in the pieces of coal and slate coming from many different veins, and

Jan 1, 1910

By George Kenzy, Charles B. Manula

This paper introduces a philosophy of dynamic modeling. Here, the development of a simulation model of a coal mining system is described for the purposes of: (a) system design and selection of equipment for a new operation; (b) analysis of existing operation' for possible alterations, additions, or general improvements.

Jan 1, 1976

By Edward Halse

The occasional occurrence in metalliferous veins of rounded fragments of rock, matrix or ore, lying loose, embedded in clay, or enclosed in some kind of cement, may be attributed to four causes:— I. They have been washed in from the surface, or from an upper portion of the vein.. II. They are of concretionary origin. III. They have been produced by movements in the country-rock or in the walls of the vein. TV. They have been formed in situ, by the upward, downward or lateral flow of water in the vein itself. In this paper the word " conglomerate " is confined to a rock composed of rounded fragments or pebbles cemented together, as distinguished from a " breccia," in which the rock-fragments are angular. * I. Boulders and Pebbles which have been Washed in from the Surface, or from an Upper Portion of the Vein. In this type it is presupposed that the vein at one time communicated by a fissure or open space with the surface, or with the upper portion from whence the fragments have been washed. One well-authenticated occurrence was described long ago by Fournet. Owing, no doubt, to later dislocations in the lode, pebbles from an old alluvium and sands containing titaniferous iron, as well as fragments of wood, were found in a vein at Huelgoet, in France. " Toutes les parties tendres du filon de Pranal ou ces phenome'nes sont les plus prononces ont 6th excaves jusqu'a d'aasez grandes profondeurs par I' impetuosite des torrents, qui out depose la matiere alluviale.'"

Jan 1, 1906

By Robert Greenwood

The advent of the space age and its promise of interplanetary flight has prompted new ideas for propulsion systems that will allow maximum energy with minimum fuel weight. The use of cesium as the source of energy for such rocket flights has been found desirable. Theoretical efficiency of a rocket fuel is measured in terms of specific impulse, defined as the number of pounds of thrust per pound of propellant consumed per second. Specific impulse is usually expressed in seconds (the number of seconds for which one pound of fuel would produce one pound of thrust) although it is really a measure of total energy, not of power. The most sophisticated chemical fuels have a specific impulse of 300 to 400 sec; liquid hydrogen heated by nuclear reactor has a specific impulse of 1000 to 1200 sec. Specific impulses as high as 20,000 sec, however, are theoretically attainable with the ion rocket, in which free cesium ions are accelerated across a voltage drop and ejected at high velocity.' Characteristics of the system have been sketched by Boden. The desirable properties of an ion propellant are: 1) low ionization potential, 2) low boiling point, and 3) high atomic weight. Alkali metals best fulfill these requirements, and Table I indicates the superiority of cesium. The use of heavy complex ions such as UCl; is ruled out by their instability and other disadvantages.

Jan 5, 1960

By I. J. Corrans

Wet high-intensity magnetic separation (WHIMS) has been successfully applied to the recovery of gold and uranium from the residues of Witwatersrand ores. Good overall recoveries have been achieved for particles as small as 12µ, and finer particles of uranium minerals are recovered when present as inclusions. The best results were obtained with a matrix of soft-iron balls 6 mm in diameter. However, pilot-plant tests drew attention to a major defect of the machine: the matrix could be blocked by wood chips and ferromagnetic particles. This problem was overcome by the incorporation of a modification that allows the balls to be discharged from the rotating annulus. Two full-scale units that incorporate the modification have been installed.

Jan 1, 1980

By Strathmore R. B. Cooke, Marcus Digre

That calcium will activate quartz for flotation with anionic collectors such as soaps has been known for a number of years,12'3 and the method has been applied to the concentration of various iron ores4 5 6 as well as to other materials. Clemmer gives the permissible pH range for the activation of quartz by calcium as between 9.5 and 12.5 with an optimum value of 11.0, and Hertzog7 has determined the calcium abstraction of iron ores and of Ottawa sand, but otherwise little quantitative data are available. The purpose of the present investigation was to determine those conditions under which dilute solutions of calcium chloride will activate quartz for anionic flotation and to determine the amount of calcium ion adsorbed by quartz. Those variables, the influence of which was primary, such as calcium, sodium, and hydrogen ion concentrations, were studied. Other factors which influenced the results are discussed in the description of the experiments. Three different experimental methods were used to determine the activation of the quartz. The first method was to treat a sample of ground, deslimed quartz with solutions of calcium chloride and sodium hydroxide, and to determine the calcium adsorbed by chemical analysis of the solution. Advantages are that a direct value for the amount of calcium adsorbed is obtained, and introduction of a collector which may affect the adsorption is avoided. The difficulty is to determine the extremely small differences in the calcium concentrations before and after the abstraction. The second method was to determine the activation of the quartz by observing the contact angle obtained on pressing an air bubble against the polished surface of a piece of quartz immersed in a solution of calcium chloride, sodium hydroxide, and sodium oleate. This is the well-known "contact angle" method. The third method was to determine those conditions under which an air bubble will pick up quartz particles immersed in a solution of the desired reagents. Disadvantages common to the sec- ond and third methods are that introduction of a collector is necessary to obtain bubble contact with the mineral; very small quantities of contaminant can give erroneous results; and no information is obtainable concerning the amount of calcium adsorbed. Advantages are that tedious analyses, which at best give approximate results, are avoided, and the conditions, especially for the third method, closely simulate those of actual flotation. Although the most consistent results were obtained with the third method, this paper describes the techniques used and the results obtained from each of the three methods. Distilled water and analytical grade reagents were used throughout except where otherwise stated. Between tests all glass articles were cleaned with a chromic-sulphuric acid mixture and sodium hydroxide. Abstraction Method The raw material for the tests was Ottawa sand sized between 14 and 28 mesh. Batches of 500 g of this sand were dry ground for 1 hr in an Abbe porcelain mill with 2700 g of quartz pebbles. The batches were split down to samples weighing approximately 30 g, and the weight of each sample was adjusted to exactly this value.

Jan 1, 1950

By S. Floreen, H. W. Hayden

The effects of additions of iridium, rhodium, ruthenium, and platinum on the mechanical properties of Fe-C alloys were determined. Each alloying element significantly improved the toughness. The results support the general correlation that substitutional alloying elements that stabilize austenite are beneficial to toughness, but the reason for this improvement is not obvious at this time. The effects of substitutional alloying elements on the toughness of steel has long been a subject of both practical and theoretical interest. Despite the obvious importance of this subject, there has been little progress toward understanding the mechanisms by which alloying elements influence the fracture behavior. In some cases the deleterious effects of alloying elements have been shown to be due to mechanisms such as embrit-tlement of prior austenite grain boundaries or inhibition of cross slip in the ferrite lattice. In other cases, however, the reasons for the change in properties are not clear. This is particularly true for elements, such as nickel, that improve the resistance to brittle fracture. Several investigators'-3 have pointed out that there is a correlation between an alloying element's phase diagram with iron and its effect on toughness. Those substitutional alloying elements that stabilize austenite generally are beneficial to toughness, while ferrite-stabilizing elements generally are detrimental to toughness. The word "generally" should be emphasized, because exceptions to this rule can be found. Nevertheless, this correlation does offer a starting point at which to try to understand the effects of alloying elements on toughness. Thus far only two austenite-stabilizing elements, manganese and nickel, have been considered. In order to test the validity of this correlation several other austenite-stabilizing elements were evaluated. The noble metals, iridium, rhodium, ruthenium, and platinum, have binary phase diagrams with iron similar to the Fe-Ni and Fe-Mn diagrams. That is, each element expands the austenite field, and also higher concentrations of each element produce martensitic transformations at low temperatures. Presumably then, each of these elements should improve the toughness of steel. The present study was conducted to determine if this were so. EXPERIMENTAL PROCEDURE The alloys were made as l-lb air-induction melts using electrolytic iron and commercially pure noble metals. Each heat was initially deoxidized by a carbon boil, and further carbon was added to attempt to produce a 0.05 wt pct C content in each alloy. Before pouring, a final refining addition of 0.2 wt pct A1 and 0.1 wt pct Ti was made to each heat. The alloys were cast in a copper mold to produce ingots approximately 1 in. in diam and 5 in. long. The chemical compositions of the alloys tested are given in Table I. The residual nitrogen, aluminum, and titanium contents were all relatively constant at 0.003, 0.03, and 0.02 pct, respectively. The carbon

Jan 1, 1968

By Alan Stanley

THE MacIntyre Development of National Lead Co. is located at Tahawus, N. Y., in the heart of the Adirondack Mountains. Operations involve the mining and concentrating of a titaniferous iron ore to produce ilmenite and magnetite concentrates. A general description of the operation and metallurgy has been given by Frank R. Milliken.' Pigment plant production demands that the MacIntyre mill produce a 44.7 pct TiO, ilmenite concentrate. To achieve the required ilmenite grade and tonnage it is important that the table concentrate grade be closely controlled. Unfortunately, however, the titaniferous orebody which feeds the MacIntyre mill is not uniform. Ore dressing characteristics vary from one end of the orebody to the other, and from • one level to the next. The changeable nature of the mill feed precludes a single adjustment of the equipment for long periods of time. Thus the operators must constantly watch the equipment to insure a uniform concentrate from the fine and coarse tables and Wetherills, or dry magnetic separators. Chemical assaying of mill products requires about 4 hr from the time the sample is taken until assay results are obtained, and this is available only on a two-shift basis. The ore may change rapidly, even several times during a shift, so that assay results lose most of their control value by the time they are reported to the mill operating crew. Members of the crew have therefore tried to evaluate the table and Wetherill concentrate by visual inspection, since through long experience the shift operators, under most circumstances, can gage closely the grade of the mill products. However, there are times when the physical nature of the ore is radically different from normal. Under these conditions visual inspection is of no value, and at such times final ilmenite as low as 43 pct TiO, has been produced and shipped before the assay results have been received. The specific gravity method of assaying for TiO, has been attempted to eliminate the shipping of ilmenite below normal grade as well as to help control day to day and hour to hour mill production. Table I shows the minerals found in the MacIntyre ore along with their average weight proportions and specific gravities. The first two products considered for the specific gravity method were fine and coarse table concentrates. It was reasoned that these products were essentially ilmenite with the higher specific gravity gangue minerals. Since they were always produced the same way, and the desired grade of TiO, was always constant, the specific gravity of these materials would increase or decrease as the amount of ilmenite increased or decreased. Thus for table concentrates which assayed 40 pct TiOz a constant gravity would invariably be obtained, and as the TiO, value changed the specific gravity would change in direct proportion. The third product considered was Wetherill ilmenite. It was assumed that a desired grade of 44.7 pct Ti02 would also always contain the same amount and type of gangue minerals along with the ilmenite, and thus would always have the same specific gravity. As the TiO, value of the ilmenite concentrate changed so would its specific gravity. Dr. Kenneth Vincent, chief metallurgist of the Baroid Division of National Lead Co. at Magnet Grove, Ark., ran specific gravity tests on 17 samples of the desired products. The lowest specific gravity reading assayed the lowest in TiO, and as the specific gravity increased the trend was for the TiO, assay to increase, see Fig. 1. Since these results warranted further investigation, a 500-g capacity Torsion balance and 250 ml Le Chatelier specific gravity bottles were obtained. Shift samples of fine table concentrate, coarse table concentrate, and final ilmenite were tested. Each sample was split and 85 g weighed on the Torsion balance. The Le Chatelier bottle was filled with water to a zero mark. To avoid wetting the neck of the bottle it was found necessary to do this

Jan 1, 1953

By Alan Stanley

THE MacIntyre Development of National Lead Co. is located at Tahawus, N. Y., in the heart of the Adirondack Mountains. Operations involve the mining and concentrating of a titaniferous iron ore to produce ilmenite and magnetite concentrates. A general description of the operation and metallurgy has been given by Frank R. Milliken.' Pigment plant production demands that the MacIntyre mill produce a 44.7 pct TiO, ilmenite concentrate. To achieve the required ilmenite grade and tonnage it is important that the table concentrate grade be closely controlled. Unfortunately, however, the titaniferous orebody which feeds the MacIntyre mill is not uniform. Ore dressing characteristics vary from one end of the orebody to the other, and from • one level to the next. The changeable nature of the mill feed precludes a single adjustment of the equipment for long periods of time. Thus the operators must constantly watch the equipment to insure a uniform concentrate from the fine and coarse tables and Wetherills, or dry magnetic separators. Chemical assaying of mill products requires about 4 hr from the time the sample is taken until assay results are obtained, and this is available only on a two-shift basis. The ore may change rapidly, even several times during a shift, so that assay results lose most of their control value by the time they are reported to the mill operating crew. Members of the crew have therefore tried to evaluate the table and Wetherill concentrate by visual inspection, since through long experience the shift operators, under most circumstances, can gage closely the grade of the mill products. However, there are times when the physical nature of the ore is radically different from normal. Under these conditions visual inspection is of no value, and at such times final ilmenite as low as 43 pct TiO, has been produced and shipped before the assay results have been received. The specific gravity method of assaying for TiO, has been attempted to eliminate the shipping of ilmenite below normal grade as well as to help control day to day and hour to hour mill production. Table I shows the minerals found in the MacIntyre ore along with their average weight proportions and specific gravities. The first two products considered for the specific gravity method were fine and coarse table concentrates. It was reasoned that these products were essentially ilmenite with the higher specific gravity gangue minerals. Since they were always produced the same way, and the desired grade of TiO, was always constant, the specific gravity of these materials would increase or decrease as the amount of ilmenite increased or decreased. Thus for table concentrates which assayed 40 pct TiOz a constant gravity would invariably be obtained, and as the TiO, value changed the specific gravity would change in direct proportion. The third product considered was Wetherill ilmenite. It was assumed that a desired grade of 44.7 pct Ti02 would also always contain the same amount and type of gangue minerals along with the ilmenite, and thus would always have the same specific gravity. As the TiO, value of the ilmenite concentrate changed so would its specific gravity. Dr. Kenneth Vincent, chief metallurgist of the Baroid Division of National Lead Co. at Magnet Grove, Ark., ran specific gravity tests on 17 samples of the desired products. The lowest specific gravity reading assayed the lowest in TiO, and as the specific gravity increased the trend was for the TiO, assay to increase, see Fig. 1. Since these results warranted further investigation, a 500-g capacity Torsion balance and 250 ml Le Chatelier specific gravity bottles were obtained. Shift samples of fine table concentrate, coarse table concentrate, and final ilmenite were tested. Each sample was split and 85 g weighed on the Torsion balance. The Le Chatelier bottle was filled with water to a zero mark. To avoid wetting the neck of the bottle it was found necessary to do this

Jan 1, 1953

Beyond the industrial suburbs of Melbourne to the southeast are brown coal deposits just under the fertile soil of the Latrobe Valley. These deposits rank as one of the wonders of the world. The manner in which this resource is put to use is one of the great engineering accomplishments of our time and also a prime example of Australian elan. The brown coal, with over 60% water content, occurs in beds from 200 to 400 ft thick, under 50 ft of cover. Fifty thousand tons of coal per day move in a nearly continuous stream from mining face to boilers. The power plants supply two thirds of the State of Victoria's requirements, about 800 megawatts. Surge capacity between mine and power plant is sufficient for 12 hr steaming time! Victorian brown coals have been known since the middle of the 19th century. However, it took a strike of bituminous coal miners in 1915 to bring brown coal permanently into the picture as a fuel for power generation. In Australia, power generation is a State function. The great development of brown coals has been under the State Electricity Commission of Victoria.

Jan 10, 1964