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By Jean Howard, E. V. Walker

ManY papers have been published during the last few years on the formation of cube texture in 3 1/4 pct Si-Fe, e.g., those of Assmus, Detert, Dunn, and Walter.1,5 All are concerned with the formation of the texture by a process involving secondary re-crystallization and the relative surface energies of (100) and other planes under certain conditions of annealing. The authors have found that cube texture can also be produced by heavily cold rolling strip in which the cube-on-edge texture has first been formed. Cube texture develops on annealing, but in this case it is not accompanied by secondary recrystallization. The starting material is a sintered compact, the preparation of which has been described elsewhere. Using a conventional processing schedule employed for producing commercial silicon-iron with the cube-on-edge texture, the sintered compact is cold rolled to such a thickness that, after annealing in pure hydrogen for 24 hr at 1350'~ to produce the cube-on-edge texture, the final thickness required can be obtained by giving a further cold reduction of 85 pct. Cube texture is developed by annealing at -900~~ in pure hydrogen: it has been produced in strip up to 0.024 in. thick. The microstructure of the strip consists of a mass of small primary grains within the boundaries of the much larger secondary grains which ex- hibited cube-on-edge texture before the final cold roll. If the strip is annealed at -1000 after the 85pct reduction, secondary recrystallization begins to take place, provided a strong cube texture is present. On raising the temperature more secondaries grow, complete secondary recrystallization being obtained on annealing at -1150'. From this it is concluded that the secondary crystals are produced by the texture inhibition mechanism: they show (110) and (111) planes in the surface of the strip, the former being the more numerous. It has been observed that the more perfect is the (110) [001] texture prior to cold rolling by 85 pct, the further from the ideal is the (100) [oo].] texture. A similar treatment applied to high quality commercial grain-oriented silicon-iron strip failed to produce cube texture. The tilt and rotation of the [loo] from the rolling direction was less than 10deg, but (to within a few degrees) the planes (130), (450) and (210) lay in the surface of the strip. Acknowledgment is made to the Engineer-in-Chief of the British Post Office for permission to use the information contained in this note.

Jan 1, 1962

By George P. Hulst

Prior to 1914, there was little demand for antimony in this country; its use was limited almost entirely to the manufacture of type and bearing metals. Practically no antimony ore was mined here, the market being supplied principally from China, and the alloy was produced by a direct mixing of lead and antimony. The great world war, with its demand for shrapnel in hitherto undreamed of quantities, precipitated a great boom in the price of antimony. Nominally quoted at 6 c. to 7 c. in 1914, the price increased by leaps and bounds to 45 c. in March, 1916. Under the stimulus of high prices many small mines were opened, for it became profitable to work ores containing as low as 20 per cent. antimony. High-grade sulfide ores (stibnite), containing 55 per cent. to 60 per cent. antimony, were received from Bolivia, China, and Alaska. Low-grade sulfide ores, running from 20 per cent. to 45 per cent., were produced in Nevada, California, Idaho, Utah, and Mexico; much of this ore was fairly rich in silver. The principal oxide ores came from Mexico and Oregon. The following analyses are representative of various types of antimony ore: Sb Pb Cu AG AU SIO2 Be S CaO Zn As Oxide ore.......... 25.09 46.02 0.95 0.40 10.98 0.30 0.22 Sulfide ore......... 55.20 15.12 1.05 19.87 0.40 0.25 Sulfide ore......... 37.16 11.30 0.10 34.0 7.60 0.50 17.05 7.40 0.36 0.10 Sulfide ore......... 41.55 18.00 0.20 76.0 0.04 5.60 0.25 18.17 0.85 0.25 0.10 The International Lead Refining Co. fortunately was equipped to handle these ores through residue and blast furnaces. The charge consisted of a variety of sulfide ores containing Sb 20 to 60 per cent. and SiO2 6 to 45 per cent., oxide ores containing Sb 20 to 40 per cent. and SiO2 10 to 45 per cent. Secondary materials, such as battery plates, battery mud, lead oxide, paint, etc., together with refinery skims, softener skims, and other refinery byproducts, were treated along with the antimony ore to furnish the lead required. All silver-bearing antimony ores were treated in the residue furnace, the sulfur, iron, and copper forming matte that carried part of the silver, the balance going into lead bullion. The antimony slag produced was sufficiently low in silver to warrant being smelted in the blast furnace to antimonial lead.

Jan 1, 1921

By Henry N. McCarl

[The Construction Materials section contains the following Chapters: Aggregates Cement and Cement Raw Materials Crushed Stone Dimension and Cut Stone Lightweight Aggregates Gypsum and Anhydrite Sand and Gravel Insulating Materials-Thermal and Sound Slag Roofing Granules] Mineral aggregates are those natural and manufactured industrial mineral and rock materials that provide bulk and strength in portland cement concrete, bituminous concrete mixes, and plaster or stucco surfaces. They may also provide special characteristics such as thermal and acoustical insulation, weight, surface textures, abrasion resistance, and impermeability to various concrete products and mixes. Most aggregates are relatively inexpensive materials, but despite their low unit value, the tonnages consumed each year in the United States and throughout the" world make mineral aggregates by far the leading industrial mineral and rock materials both in terms of volume (tonnage) produced and value consumed. The major use of mineral aggregates is in concrete. The low cost, high bulk aggregates tend to keep concrete construction costs at levels competitive with other building materials. Other major uses of aggregates include highway and railroad base or ballast materials, graded fill, and various industrial uses such as metallurgical and chemical fluxes and raw materials-these latter uses are often considered nonaggregate uses of mineral aggregate materials. The per-ton value of mineral aggregate materials at the production plant in 1980 and 1981 varied from $2 to $5 for most sand and gravel and crushed stone, $3 to $6 for air-cooled slag, $7 to $20 for expanded slag and expanded clay or shale aggregate, to as much as $165 to $320 for expanded perlite or vermiculite. The expanded lightweight aggregates have been dramatically affected by increasing fuel costs. It is ironic that the specialized aggregates used as insulating materials to conserve energy cost so much more to produce due to the high proportion of energy consumed in their production. The first four parts of "Construction Materials" deal with the utilization of four major mineral aggregate types: Crushed Stone, Lightweight Aggregates, Sand and Gravel, and Slag. While the focus will be on the use of these industrial minerals and rocks, there will also be some coverage of sources, mining and production, especially in those cases where they are not discussed in the Commodity section of this book.

Jan 1, 1983

By David Scott

THE MOGOLLON mining district, New Mexico, has received little public attention, although for 15 years it has been the leading silver producer of the state; it is situated in a region remote from the principal lines of travel, and its activities have usually been limited to the operations of two or three companies. The value of the total production of the district in the 44 years of its history has been estimated at $15,000,000. For the years 1904 to 1917, inclusive, the output was: gold, $4,370,000; silver, 10,042,000 oz.; copper, 874,862 lb.; total value, approximately. $10,500,000. In 1913 the district contributed 80 per cent. of the total silver production of New Mexico, but in 1917 only 41 per cent., due to serious interruption in the operations of the leading producer. Since 1914 the silver output has diminished one-half, and the present high value of silver is nearly offset by the increase in cost of production. The output of gold has rarely exceeded 35 per cent, of the total for New Mexico. The ratio of silver to gold, by weight, has averaged 46:1 based on the whole output of the district. LOCATION AND TOPOGRAPHY The town of Mogollon is 75 mi. (121 km.) by a poorly located highway from the nearest railroad terminals, at Silver City and Tyrone. All supplies are transported by motor trucks and teams. The area, sometimes called the Cooney Mining District, lies on the western flank of the Mogollon Mountains, which occupy the western part of Socorro County. The elevations drop steeply on the west to the valley of the San Francisco River, adjacent to the Arizona boundary. The topography is very rugged, the whole area being sharply dissected; deep canyons with steep gradients and rugged walls are characteristic of the whole western-slope of the Mogollon Range. The main canyons run east and west, and usually maintain a flow of water during the entire year. As would be expected in a region of such deep dissection, the

Jan 2, 1920

By Benjamin C. Craft, Frank Perkins

The wall-building properties of salt-water muds can be maintained at high temperatures by additions of gum karaya, gum ghatti, gelatinized starch, or commercially prepared starch. A germicide should be used to prevent fermentation. Introduction The behavior of drilling mud has received special attention from the petroleum industry within the past few years in numerous research projects dealing with such subjects as chemical treatment, gelation, and filtration characteristics. The importance and control of filtration, or water loss, is readily apparent* It affects the analysis of side-wall cores and interpretation of electric logs; it controls to a large extent the work of primary cementing, reduces the amount of expensive fishing, and permits the running of long strings of casing. It has been found that among the many factors that have an adverse effect on filtration, the presence of electrolytes, in general, and of salt, in particular, is outstanding. The effect is one of flocculation of the colloids due to neutralization of the negative charges on the clay particles. This reaction is further increased on the Gulf Coast because high temperatures reduce dispersion, to a minimum, causing increased flocculation in both fresh-water and saltwater muds. The problem of reducing water loss in salt-water muds by the addition of gums and starch at atmospheric temperature has been investigated,' and many successful field tests in West Texas indicate its solution. From the work of Byck2 it is concluded that no existing method will permit an approximate determination of the filtration rate at high temperatures from data taken at room temperatures. Filtration should be measured at the ternperature actually anticipated in the well, or at least at a number of lower temperatures and extrapolated over a small range. A laboratory study has been made of the chemicals available for the filtration characteristics of salt-water muds at high temperatures, and the use of germicides to prevent fermentation. Laboratory Investigations Procedure Since the purpose of this investigation was to compare several different gums and starches at elevated temperatures, mud from the same source was used for all the tests. Viscosity was measured in a Stormer viscosimeter at 600 r.p.m. and water loss was determined with a Baroid High-pressure and High-temperature Wall-building Tester3 at temperatures from 80' to 250°F. and at a pressure of 500 lb. per sq. in. for 30 minutes. The samples tested consisted of 150 grams of commercial Louisiana mud, 50

Jan 1, 1943

By Benjamin C. Craft, Frank Perkins

The wall-building properties of salt-water muds can be maintained at high temperatures by additions of gum karaya, gum ghatti, gelatinized starch, or commercially prepared starch. A germicide should be used to prevent fermentation. Introduction The behavior of drilling mud has received special attention from the petroleum industry within the past few years in numerous research projects dealing with such subjects as chemical treatment, gelation, and filtration characteristics. The importance and control of filtration, or water loss, is readily apparent* It affects the analysis of side-wall cores and interpretation of electric logs; it controls to a large extent the work of primary cementing, reduces the amount of expensive fishing, and permits the running of long strings of casing. It has been found that among the many factors that have an adverse effect on filtration, the presence of electrolytes, in general, and of salt, in particular, is outstanding. The effect is one of flocculation of the colloids due to neutralization of the negative charges on the clay particles. This reaction is further increased on the Gulf Coast because high temperatures reduce dispersion, to a minimum, causing increased flocculation in both fresh-water and saltwater muds. The problem of reducing water loss in salt-water muds by the addition of gums and starch at atmospheric temperature has been investigated,' and many successful field tests in West Texas indicate its solution. From the work of Byck2 it is concluded that no existing method will permit an approximate determination of the filtration rate at high temperatures from data taken at room temperatures. Filtration should be measured at the ternperature actually anticipated in the well, or at least at a number of lower temperatures and extrapolated over a small range. A laboratory study has been made of the chemicals available for the filtration characteristics of salt-water muds at high temperatures, and the use of germicides to prevent fermentation. Laboratory Investigations Procedure Since the purpose of this investigation was to compare several different gums and starches at elevated temperatures, mud from the same source was used for all the tests. Viscosity was measured in a Stormer viscosimeter at 600 r.p.m. and water loss was determined with a Baroid High-pressure and High-temperature Wall-building Tester3 at temperatures from 80' to 250°F. and at a pressure of 500 lb. per sq. in. for 30 minutes. The samples tested consisted of 150 grams of commercial Louisiana mud, 50

Jan 1, 1943

By H. D. Outmans

In steady vertical flow, the interface of an immiscible liquid-liquid displacement is horizontal for any flow rate below the critical. In nonvertical flow, however, the shape of the interface in the steady state does depend on the flow rate, and the purpose of this paper is to calculate the unsteady interfaces during the transition of one steady state of flow to another. A knowledge of these transient interfaces is of considerable importance in reservoir engineering where the calculation of breakthrough recovery depends on the instant the interface reaches the producing wells and on the shape of the interface at that time. Although the emphasis is put on transient interlaces, which eventually approach stable equilibrium, it is shown that if the displacement exceeds a critical rate no equilibrium is possible. The interface is then unstable and viscous fingers are formed during the displacement. The critical rate and the shape of the transient and equilibrium interfaces are affected by the effective interfacial tension; but since this effective interfacial tension appears in the calculations only in combination with the inverse square of the thickness of the medium, its effect in the reservoir would appear to be negligible compared to its significance in model experiments. INTRODUCTION Stability criteria and the early growth of interfacial disturbances in a plane parallel to the boundaries of a dipping formation in which oil is displaced by an incompressible fluid were described in a previous paper.l This type of instability is significant in thin reservoirs. However, if the reservoir has appreciable thickness, then interfacial stability in vertical planes, normal to the upper and lower boundaries, also becomes important (the displacement is supposed to be parallel to these vertical planes). The difference between the two stability problems is that, in the first case, the intersections of the interface with planes parallel to the boundaries are normal to the direction of the displacement; in the second case, the intersections, this time with vertical planes, are not normal to the displacement. Instead, they are tilted at an angle which depends on the displacement rate. The tilt of steady interfaces was calculated by Dietz2 who also determined the critical rate of displacement for stability in the vertical plane by assuming that this rate would coincide with an interfacial tilt equal to the dip of the formation. The critical rate thus calculated is the same as has been found for thin reservoirs (see Eq. 1.1 of Ref. 1 and of the present paper). Dietz's calculation of the stable tilt was verified by laboratory experiments and the agreement was found to be fairly good.3 It is doubtful, however, that stable tilts actually exist in the reservoir because a change in production rate is not followed by an instantaneous adjustment of the interface to the new rate but, rather, by a transition period during which the interface changes from one equilibrium tilt to the other. The principal objective of this paper has been to describe these transient interfaces without putting any restrictions on the flow conditions or the shape of the interface, as had been done previously. The second objective was to compute the critical velocity, taking into account capillary effects, and the third was to evaluate, at least qualitatively, the shape of the front at rates above the critical, again without making the simplifying assumptions introduced by previous investigators.2,3 In the following sections two examples are given of the calculation of interfacial motion. The first describes this motion for an initially horizontal interface in a dipping layer, and the second for a vertical interface in a horizontal layer. The mathematical formulation of the problem is nonlinear in the boundary conditions, and this prohibits its solution in closed form. Instead, the solution is obtained in the form of higher-order approximations. 1 Before proceeding to a description of the mathematical model, however, we define two quantities

By R. J. Lloyd

INTRODUCTION The Mount Isa Mine is a large modern underground mine located in North-Western Queensland, Australia. Two ore types are mined and treated separately. Currently silver-lead-zinc ore is mined at the rate of 2.6 million tonnes per annum and copper ore at the rate of 4.6 million tonnes per annum. The silver-lead-zinc orebodies are mined by sub level open stoping and cut and fill methods whilst all copper ore is extracted by various forms of sub level open stoping. The mining operations are highly mechanised and utilise diesel powered load-haul-dump units of various sizes, two and three boom face drilling jumbos, electric-hydraulic rotary-percussive ring drills, in-the-hole hammer drills, rotary blasthole drills, raiseborers, battery/trolley locomotives, a large fleet of rubber tyred service and supply vehicles plus light rockdrills mounted on airlegs, rail mounted overshot shovels and battery and diesel powered locomotives. All stoping production ore is extracted with diesel powered load-haul-dump units. The ore is tipped into orepasses which connect to the main rail haulage levels. On the haulage levels electric battery/trolley locomotives are used to pull rakes of bottom dump or side dump trucks which feed the ore into primary crushers. Following two stage crushing the ore is conveyed to the shaft and hoistod to surface in bottom dump skips. Each ore stream has its own rail transport system, crushing stations and hoisting shaft feeding separate concentrators. This paper will consider some aspects of the role of equipment and machinery in the growth of the mine, will discuss in some detail the machinery and equipment in use today and will conclude with a look at some possible developments in mining equipment for the future, with particular reference to the Mount Isa Mine. A summary of mining equipment in use at Mount Isa is given in the Appendix. THE PAST Silver-lead-zinc ore was discovered at Mount Isa in 1923 and within a very short time many small mines were being developed. However the rich surface ore traces did not continue and by 1928 Mount Isa Mines Limited had acquired sufficient leases to plan for a large scale mine to exploit the low grade orebodies. At this early stage it was recognised that the mine would need to adopt the most mechanised mining techniques then available in order to overcome its twin disadvantages of low graaes and extreme remoteness. The Company introduced bar mounted drifters and overshot shovels to replace hammer and tap and hand shovelling in development work and by 1930 headings were advancing at the rate of 30 metres per week. In keeping with the concept of mechanisation the early engineers designed the Man and Supply shaft with a very large, for those days, cage compartment measuring 3.8 m x 3.4 m. This shaft was the main means of access into the mine for 36 years until the K57 shaft (now R62 shaft) was commissioned in 1966. Man and Supply is still in regular use. Production commenced in 1931 at an annual rate of approximately 660 000 tonnes of silver-lead-zinc ore. The mine was mechanised to an extent which was previously unknown in Australia; whilst the concentrator, smelter and power house utilised the most modern and efficient equipment available. Even so, the mine was very near to closure on several occasions and did not return a dividend to its shareholders for many years. Production levels remained at or slightly below 660 000 tonnes until a separate copper ore streani and mill was commissioned in 1953, doubling the existing production levels. The first underground crushers were installed at this time. Production rates expanded in the years between 1953 and 1973. By 1960 production reached 2740 000 tonnes of ore. In 1965-66 total production was 3650 000 tonnes and in 1973 the production rate plateaued at the current level.

Jan 1, 1981

By W. Crafts, J. L. Lamont

Secondary hardening in tempering has long been recognized as a typical characteristic of steels containing large amounts of carbide-forming alloys. These steels, when quenched and tempered, tend to soften somewhat after tempering at low temperatures, and to reharden at intermediate tempering temperatures before finally softening to low hardness. This behavior in tempering has been studied by many investigators, chiefly with respect to thc secondary hardening of high-speed steels. The initial softening has usually been ascribed to decomposition of martensite and growth of iron carbide particles. The secondary hardening has been explained by formation of fresh martensite from residual austenite, formation of very fine alloy carbide particles and by precipitation hardening of metallic compounds in the ferritic matrix. However, factors derived for the calculation of tempered hardness in low-alloy steels1 indicated only a tendency toward retarded softening rather than a discontinuous rehardening. A study was, therefore, made to determine whether fresh martensite from residual austenite and precipitation hardening are essential to rehardening and the degree to which tempered martensite could be rehardened by precipitation of alloy carbides. The mechanism of carbide rehardening was also investigated to determine the nature of the process. The causes of secondary hardening in high-speed steel have received serious consideration for about thirty years. Among the earlier workers Bain and Jeffries2 in 1923 recognized residual austenite as a significant factor, but in addition, emphasized the effect of the formation of alloy carbide particles of "critical" size. They conceived that freshly quenched martensite forms low-alloy iron carbide at low tempering temperatures; with further tempering the iron carbide is then modified by alloying elements that can diffuse most readily at intermediate temperatures (850°F); and that the iron carbides grow in size by coalescence so that the steel tends to lose hardness. At higher tempering temperatures carbide stability rather than alloy availability becomes the controlling influence and in high-speed steel "iron-tungsten carbide is the most stable one and forms to the elimination of the earlier formed carbides. . . . The iron-tungsten carbide particles reach approximately the size for critical dispersion after a short reheat at II00 F." This concept, the formation of alloy carbide nuclei, redissolving of the iron carbide, and diffusion of carbon to the alloy carbide, was restated for vanadium steel in 1932 by Houdremont, Bennek, and Schrader. Subsequent studies have confirmed that iron carbide changes to alloy carbide at 1000 to IIOOOF, but the mechanism of the process has received little consideration.

Jan 1, 1949

By W. R. McMillan, E. A. Gulbransen, K. F. Andrew

Annealed and electrolytically polished pure iron was oxidized between 650° and 850°C at oxygen pressures of 0.1 to 2 microns Hg. Electron optical studies showed that oxidation occurs discontinuously over the surface and orients crystallographically with the substructure of the metal grains. IN previous papers', " the authors described the formation of oxide films on high purity iron at norrnal pressures and at temperatures below 300°C. Electron optical studies showed that the oxide film consisted of many individual oxide crystallites having nearly random orientation on each metal grain. The size of the oxide crystallites depended upon the temperature and upon the extent of oxidation. In these studies the crystallite size varied from 250 to 1800Å. Recently, Bardolle and Benard3 studied the crystal habit of the oxide crystallites formed on Armco iron between 650" and 850°C in what might be defined as a "poor vacuum" atmosphere in which the pressure could be varied between 10-1 to 10-3 mm of Hg. Their results showed that, at 850°C and a vacuum of l0-2 to 10-3 mm of Hg, a few well oriented nuclei of oxide were formed on the metal grains. At pressures between l0-1 to 10-2 mm of Hg, many oriented nuclei of oxide were formed. At 750°C the metal surface was bright although an oxide was present. Unfortunately, the extent of oxidation, the oxygen pressure, and the influence of carbon in the metal were not determined, and it was, therefore, impossible to give a theoretical interpretation to the very beautiful light micrographs. Bardolle and Benard used the light microscope to determine the crystal habit of the oxide and X-ray diffraction to determine the orientation relationships. It was believed that the use of controlled amounts of oxidation at high temperature is an important method for the study of the initial stages of oxidation of metals at high temperatures. This paper presents the first results of an electron optical study of this problem for iron. Since the electron microscope and electron-diffraction methods using stripped oxide films and surface replicas yielded finer details of the crystal habit and structure of oxide film, these methods were used in this study. Two types of iron having different carbon contents were used: Puron and Armco* iron. A com- parison of the results for these materials made possible a study of the influence of the surface oxide-carbon reaction on the initial stages of oxidation. Before discussing the experimental results, the thermodynamic equilibria of 1—the oxidation reaction, 2—the surface oxide-carbon reaction, and 3—the solubility of oxygen in iron, will be considered. In addition, it is important to consider the kinetic-theory predictions on the rate of collision of oxygen with the iron surface. Thermodynamic and Kinetic-Theory Calculations Only one type of reaction is usually considered in the oxidation of iron at normal pressures at high temperatures: Fe(a) + 1/2O2(g) = FeO(s) 3Fe(a) + 2O2(g) = Fe3O4(s) 2Fe(a) +3/2O2(g) = a-Fe2O3(s). [11 However, two other reactions may occur: FeO(s) + C (solid solution in Fe) + Fe(a) + CO(g) [2] and Fe(a) + O2(g) e Fe(a) (solid solution of 0,). [ 3 ] In addition, iron will react with the higher oxide at certain temperatures to form FeO. For a complete interpretation of the oxidation of iron at low pres-

Jan 1, 1955

Jan 1, 1967

By D. F. Hewett

[In an increasing degree in recent years, especially since the war, men in many parts of the world are turning their attention to the problems of the future, attempting to appraise the basis and extent of man's progress and interpret the problem that he faces in the near future. The war made clear to ma persons the degree to which modern industry depends upon t continuous flow of enormous quantities of raw materials, a especially of the minerals. In many circles throughout t world, the question of adequate supplies of the mine especially the fuels and metals, for near as well as more remo needs is receiving serious consideration. As a result, persons representing the state as well as industry are looking to geologists and engineers for all the data that throw light on the distribution, extent and availability of the minerals that must serve coming generations.] Obviously, in a brief research I have been able to consider only a few sources of the metals in Europe, perhaps fifty out of a total of many hundreds. In order that the conclusions may have value, however, I have chosen districts which have been important sources during some epoch of the last three hundred years or more.

Jan 1, 1932

By Persifor Frazer

A classification of natural objects is usually based either upon some fundamental and permanent attribute of the thing itself (as in the case of scientific classifications), or it embraces one or more generalizations convenient for use in ordinary life. Thus, it suffices for the statistician to know that so many tons of fish are annually taken by our fishermen, and that they realize so many thousands of dollars, whereas to the student of natural history the anatomy, habits, and relationships of the animals are of chief interest, as settling their respective places in the scale of animate nature. Many different classifications of coals have been attempted, as one would naturally anticipate from the immense extent of the coal trade, and the different localities whence the supply was derived. The English divisions were prevalent up to the date of the publication of the last geological survey of the State, except so far as they were modified by local designations. Indeed, Rogers' classifications made very little alteration in the English nomenclature, as may be seen by comparing the tables given below. To commence with the different kinds mentioned in Ure's Dictionary of Arts, Manufactures and Mines of 1845 : " 1. Cubical Coal.—Black, shining, compact, moderately hard and easily frangible. Comes out in rectangular masses, of which the

Jan 1, 1879

By Alberto J. Terrones L.

THE classical papers on contact metasomatic deposits by Lindgren on the Clifton-Morenci district,1 by Barrel1 on Marysville, Mont.,2 and by Goldschmitt on the Oslo district, Norway,3 laid the foundation for understanding of the importance of separating the metamorphic process from the subsequent metasomatic stage. Knopf4 made a big step forward by recognizing that sulfide ore minerals are invariably younger than silicates and by further stressing the importance of structural control5 ore finding. Some years later Harrison Schmitt6 fought the idea that contact metasomatic deposits are erratic, irregular, bunchy, economically marginal, and of small size, concluding that these descriptions have little factual basis. He emphasized the importance of detail mapping and careful geological study as fundamental requirements for a better understanding of these deposits. This article presents a comparative description of the structural features at the Magistral, Antamina, Morococha, Vilca, Ferrobamba, Katanga (Quibio), Tintaya, and Huarca contact deposits (Fig. 1). Further, it will describe how these structural features controlled the emplacement of the intrusives, their shape, distribution of metamorphic and metasomatic halos, and sulfide deposition in post-skarn structural channelways. Finally, the modifications introduced by a superimposed hydrothermal stage recognized at some localities will be discussed.

Jan 3, 1958

By D. R. Miller

Internal friction and elastic modulus variations in electrorefined titanium, iodide refined titanium, and alloys of the latter material with oxygen, nitrogen, aluminum, and zirconium were investigated. No oxygen peak was detected with electrorefined titanium but, provided precautions were taken to prevent increases in background damping, an oxygen peak at about 410°C could be resolved with each of the other materials. An additional partially resolved peak was observed at 500°C in a Ti-N alloy. An anomaly in the variation of rigidity modulus with temperature was observed. Possible mechanisms for the formation of any oxygen peak have been discussed. PRATT, Bratina, and Chalmersl investigated the internal friction of commercial purity titanium and alloys of this material containing 1.5, 3.5, and 4.5 at. pct O. With commercial titanium the internal friction curve consisted of two components, a background which increased steadily with temperature and a peak at about 600" C which was due to grain boundary relaxation. In the Ti-O alloys, however, an additional internal friction peak was observed at 430" to 450°C and, since this peak increased in height as the oxygen content was increased, it was thought to be associated with the presence of oxygen. The diffusion of oxygen in titanium at temperatures between 300" and 500° C is believed to have marked effects in its tensile properties2'3 and the present internal friction measurements were undertaken to obtain further information on this diffusion, using material of higher purity than that of Pratt et d. and an apparatus of very much greater sensitivity. In the course of the investigation a number of important limitations on the work of Pratt et al. were revealed and results have been obtained which emphasize the need for ensuring that in this type of experiment, internal friction is independent of strain amplitude and that the values obtained are reproducible. 1) MATERIALS AND APPARATUS The basis material from which the majority of the specimens was prepared was iodide-refined titanium, the major impurities in which were oxygen and nitrogen—the metallic impurities being present at concentrations less than 0.001 at. pct. The hardness of this material after arc melting, forging, and swaging to rods 1/4 in. diameter was Dph = 110. Specimens 10 in. long and 0.020 in. (0.51 mm) diameter were prepared from these rods by further swaging and wire drawing and were finally annealed in vacuo (5 x 10-6 mmHg) for 24 hr at 800°C. The oxygen alloys were prepared from iodide-

Jan 1, 1962

By Will Mitchell, T. G. Kirkland, C. L. Sollenberger

BENEFICIATION of a Korean scheelite ore has been studied during the past year in the Basic Industries Laboratory at Allis-Chalmers Manufacturing Co. A flowsheet has been recommended including flotation, gravity separation, and a final cleaning by a magnetic separator. The investigation was continued in the field of flotation in order to establish the effect of certain variables on recovery and grade of rougher concentrates. The results of this investigation are recorded here. Mineralogy The scheelite ore was obtained from Korea and was mined from the Sang Dong deposit. This deposit is described as lying in gently dipping metamorphosed sedimentary beds of Cambrian age.' The metamorphism was probably either metasomatic replacement or recrystallization, or both, with subsequent hydrothermal deposition. Igneous bodies in the form of granite porphyry have been found within 7 km of the main shaft and are considered to be a possible source of the mineralizing solutions. The Myobong formation, the host for the Sang Dong deposit, was laid down in middle Cambrian times and consists of series of mudstone, siltstone, shale, and marl, with local stratification of mica schists, hornfels, and tactites. The scheelite is found in quartz bands in the tactites. Although there are six of these bands, only one, the "main bed" averaging 1.75 pct WOs, has been mined to any extent. The ore sample as received in the laboratory was the product of a cone crusher and was all —2 in. The rock appeared to be even textured, medium to fine grained, and gray green in color. No scheelite could be recognized by the unaided eye. However, under ultraviolet light of 2537 A, the scheelite fluoresced and could be distinguished from the gangue. Under the black light, the scheelite showed no definite vein structure but was disseminated throughout the specimen. The raw ore had a specific gravity of 2.96 and weighed about 125 lb per cu ft at —20-mesh Tyler. The —2-in. material was stage crushed through 20-mesh, and samples were cut for mineralogical, chemical, and spectrochemical analyses. Several polished sections were cut from hand specimens. Figs. 1 and 2 show quartz to be the matrix for scheelite. It was reported by Kim2 that the greatest scheelite concentration in the mine is found with a high concentration of quartz and a decrease in the abundance of garnet. Diameters of scheelite particles ranged from 1.2 mm down to less than 50 microns. Spectrochemical analysis showed the ore to be high in aluminum, bismuth, calcium, iron, magnesium, manganese, silicon, tungsten, and with lesser amounts of beryllium, chromium, lithium, sodium, and titanium. Chemical assays showed the —20-

Jan 1, 1952

By W. R. Johnson, M. Hansen, John M. Parks

AS part of a research project sponsored by the Signal Corps Engineering Laboratories, which had the objective of obtaining a magnet wire of good conductivity and low temperature coefficient of resistance, a comprehensive literature survey, supplemented by experimental work, revealed that a linear relationship exists for solid-solution alloys between the electrical conductivity, K, and the temperature coefficient, a, as expressed by the equation: k = a/ß where ß is constant for the solvent metal and a - per°C. tR0 It has long been known that the electrical conductivity at a given temperature and the temperature coefficient of resistance of binary alloys are related to their constitution by the LeChatelier-Guertler rules, as illustrated by Figs. 1 and 2: Rule 1—In alloy systems consisting of a heterogeneous mixture of two phases, the electrical conductivity and temperature coefficient vary as a straight line, if the composition of the alloys is given in volume percentage, Fig. 1. Rule 2—In solid solutions, the electrical conductivity and temperature coefficient are always lower than those of the solvent metal, and usually a considerable decrease occurs with the first small percentage additions of the solute metal, Fig. 2b. If the two components form a continuous series of solid solutions, the electrical conductivity and temperature coefficient curves take the form of a U-curve, Fig. 2a. That some kind of proportionality exists between electrical conductivity and temperature coefficient of resistance is implied by the LeChatelier-Guertler rules and by study of data such as those given by Smith and Palmer,' Fig. 3. Dellinger2 in 1910 first recognized this relationship in a number of commercial copper wires, ranging in conductivity from 94 to 100.7 pct I.A.C.S. He gave the ratio of temperature coefficient to the percentage of conductivity as a constant, C = 0.003939. A year later, Lindeck observed that the linear relationship was valid for a wider range of conductivity in "various sorts of copper," and concluded that the product of resistivity and temperature coefficient was 6.78x10-5 1.5 pct. Since then, this relationship seems to have been entirely ignored. Conductivity-Temperature Coefficient Relationship If the electrical conductivity of copper solid-solution alloys with phosphorus, silicon, arsenic, antimony, aluminum, nickel, manganese, and iron is plotted against the temperature coefficient of these alloys, the diagrams in Figs. 4 and 5 are obtained. Similar data were found with copper-rich solid solutions containing magnesium, cobalt, and titanium,'" as shown in Fig. 6. In all cases, a linear relationship exists. The point representing the highest

Jan 1, 1952

By W. J. Reagan

IN a study of the life of ingot molds, it is essential to eliminate all of the variables. In the commercial manufacture of steel this is almost an impossibility. In this study many of the variables have been eliminated, and because of the unusually consistent furnace practice, with small variations in the type of steel manufactured, and a similar type of mold design for all ingot sizes, it is possible to determine with some degree of accuracy the cause of variations in ingot-mold life. All of the ingot molds in this study were used in the production of basic open-hearth killed steel with chemical analyses within the following range: C, 0.50-0.85 per cent; Mn, 0.60-0.80; Si, 0.20-0.30; S, 0.04 max.; P, 0.04 max. All ingot molds were of the closed-bottom type and used for bottom casting only. None of the molds in the study failed from cutting of the sides due to top casting; in fact, on only rare occasions are any molds used for top casting. The general type of this mold is shown in Fig. 1. All sizes have rather a heavy band of metal, about 6 in. wide, at the top to give mechanical strength at this point, and all have cast lugs. Cross sections of the vari-ous sizes from top and bottom sections are shown in Fig. 2. Ratios of wall thickness to ingot weight, ratio of ingot diameter to ingot length, and other figures of interest are shown in Table 1. In. the majority of cases, the cause of failure in this type of mold is due to heavy fire cracking on the "flats" at a point from 3 to 6 in. from the bottom radius of the mold. Fig. 3 pictures this type of failure. The start of failure at these points usually begins with a very small section of the interior surface becoming involved. As a rule, a section of 1 or 2 sq. in. is the first noticeable 'indication that mold failure is taking place. Gradually the small section increases until a sizable cavity develops, causing a protuberance on the bottom of the ingot, which eventually becomes too large to be stripped. The mold is then removed from service. At the time of failure, this cavity often reaches a size of about 5 sq. in. and about 1/2 in. deep. Sometimes cavities are found on only two or three sides and at other times all twelve sides appear to be involved.

Jan 1, 1936

By W. B. Humes

The use of high vacuum on a large industrial scale in the ferrosilicon process for the production of magnesium marks the coming of age of an important new metallurgical technique. The economical production of reactive metals, such as magnesium, which combine with all the well-known furnace atmospheres, has until recently been successfully carried out only by electrolytic methods. It is now apparent that, through the use of high vacuum, the distillation or sublimation of many metals can be done industrially at much lower temperatures, and hence in much simpler equipment, than heretofore has been thought possible. At the beginning of the present emergency, when the ferrosilicon process of producing magnesium was brought to the fore, little was generally known about vacuum engineering, practices, and techniques. In a comparatively short time, the available equipment has been adapted, new equipment designed and built, and a fund of know-how evolved to make possible the production of thousands of pounds of magnesium per day at pressures less than 1/ r0,000 of an atmosphere. Pilot-plant operations have been consistently maintained at pressures even as low 2s one micron (0.001 mm.). These low pressures, which previously were regarded as prohibitively costly or impossible to attain, have been demonstrated as economically feasible on an industrial scale. Necessity for Vacuum The main function of vacuum in the ferrosilicon process, and hence in most vacuum smelting processes, is to lower the temperature at which the metal may be distilled or sublimed from the reduction mixture. A secondary function is to protect the distilled metal from attack by the furnace atmosphere and to permit the formation of a dense condensate. In the ferrosilicon process, magnesium is formed by the reaction between dolomite and ferrosilicon: 2(Mg0-Ca0) -\- HFeSU / t=> aMg + MFe + (CaO)2-SiO2 The metal is distilled from the pelleted charge at a free air pressure of about 0.100 mm. of mercury (100 microns). This low pressure is not needed for the reaction, but rather serves to protect the metal vapor from the oxygen or nitrogen of the atmosphere and permits the formation of a condensate free of pyrophoric material. The reaction proceeds at air pressures as high as several millimeters of mercury, and evidence has been offered to show that the actual equilibrium pressure of magnesium at operating temperatures of 2I50°F. is somewhat higher. Experimentation indicates that the yield begins to decrease at pressures above 500 microns. While no real operating data are yet available on the relationship between

Jan 1, 1944

By John T. Thorndyke

MOST important of the naturalcalcium silicates is the meta¬silicate, CaSi03, known as wollastonite, after W. H. Wollaston. A large deposit of this mineral was dis¬covered some seven years ago near Code Siding, Rademacher mining dis¬trict, Kern County, Calif., the deposit being some 7500 ft. long and of an average width of 300 ft. It consists of a series of small domes striking north¬erly and southerly and with a dip of 81 ° to the south. This deposit was opened up by a series of small quarries showing a potential tonnage of 12,000,¬000 tons, allowing of cheap mining and transportation, the Southern Pa¬cific R.R. spur track being one mile north of the workings. Numerous sam¬ples taken from different points on the deposit, tested by Mr. Brinker, of the California Testing Laboratories, Los Angeles, showed an average as fol¬lows: Per Cent Silica (SiO2) 47.12 Lime (CaO) 41.72 Magnesia (MgO) 2.72 Alkalies (R,0) Trace Iron (Fe.,O,) 1.60 whereas the theoretical composition of of wollastonite, as given by William Shirley Bayley, is as follows: Silica 51.75 Lime 45.25 The tonnage and purity of this de¬posit led to investigations into its com¬mercial development. Early work es¬tablished the fact that wollastonite was ideal for the manufacture of a tough, almost unbreakable, glass similar to Pyrex. It also established the fact that wollastonite was particularly adapted for use in the manufacture of mineral wool, towards which further research was then directed. Briefly, the prin¬cipal advantages were the substantially unvarying chemical composition of the naturally occurring mineral and its characteristic of being relatively flexi¬ble and highly resilient when fused into a glass. A mineral wool produced therefrom is thus not only of highly uniform composition and color but is most desirable because of the high mechanical strength and length of the individual fibers constituting the wool. It is well known that mineral wool may be prepared by melting a suitable charge of raw material and then intro¬ducing a stream of a suitable fluid, such as air or steam, into a stream of the molten raw material. By this means the molten material is blown into threads or fibers, which are collected in a suitable chamber similar to a tun¬nel, from which they are removed from time to time or continuously. Com¬mercial manufacture of mineral wool has been carried on for only about 50 years, but volcanoes, specifically Kilauea in the Hawaiian Islands, have

Jan 1, 1936