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By S. C. Sun

This article by Spokes and Mitchell de- serves high commendation. For many years mineral dressers have been at a loss to explain the variation in magnetic susceptibility of the same mineral species obtained from different localities. In fact, they do not even have a list of accurately measured data on the specific magnetic susceptibility of weakly magnetic minerals to consult. Experience as a university teacher has firmly convinced me that the average student has more difficulty in acquiring a satisfactory knowledge of magnetism than of any other branch of mineral dressing. This is almost entirely because the subject has been treated far too much from a strict practical standpoint and far too little from a fundamental one. It is no exaggeration to state that almost all the published theoretical discussions are based on the experimental results of manufactured chemicals and alloys, but not of naturally occurring minerals. In an attempt to remedy this state of affairs, the author of this article not only set up a new magnetic balance in the Department of Mineral Preparation of The Pennsylvania State University, but also performed work of fundamental value, thus pointing the way to further research. This is evidenced by the fact that an investigation of the magnetic susceptibilities of manganese minerals was recently completed by S. G. Watt under the direction of David R. Mitchell, now acting dean of the College of Mineral Industries of the Pennsylvania State University. D. J. Cook is studying the magnetic susceptibility of titanium minerals under my supervision. It is hoped that our research program can be continued for several years and that similar investigations will be Initiated at other universities and research institutions.

Jan 4, 1958

Molybdenum was first discovered on the Continental Divide in Colorado in 19 11; and in 1918 two companies, one of which was the Climax Molybdenum 250 stpd operation, were producing. In 1919 both mines were shut down, but in 1924 the Climax mine reopened and has been producing ever since. Over the years mine production has been increased until today the mill capacity is 48,000 stpd (43,500 mtpd). From 1935 to 1973 all ore was mined underground by block caving with scraper slushing. Since 1973 ore production has been supplemented by open pit mining. As demand for molybdenum increased, upper levels of the mine became worked-out and new lower levels were opened. In late 1972 production began on the 600 level with the mined ore being primary and secondary crushed in the new No. 4 crushing station. Ore is hauled to the primary in 10 st (9. 1 mt) capacity Granby side-dump cars. The trains, carrying 200 st (181 mt), pass throug.h a dump block and discharge directly into a 54 in. by 84 in. Traylor TC gyratory crusher set at an 8 in. (203 mm) open side setting. Since the ore has already been broken to a size which will pass the finger raises in the mining areas, there are only rare oversize boulders to block the crusher opening. Selection of the crusher was based more on its capacity than its receiving opening, as is often the case with gyratories used in open pit operations. Nominal and maximum capacities for this unit are 1250 and 1800 stph (1 135 and 1635 mtph). The ore is often wet and sticky, so a mechanical car cleaning device is utilized. Under the crusher is a 300 st (270 mt) ore pocket equipped with a 60 in. (1.52 m) wide inclined conveyor which delivers the ore to a 2,000 st (1800 mt) surge bin. Near the head pulley of this conveyor is a wood picking station whe re tramp wood and steel are put into cars for removal. Two more apron feeders remove the primary crushed ore from the surge bin, and impact belts and conveyor belts transport the ore to the crushing station for screening ahead of two 7 ft (2. 13 m) standard crushers. Secondary crushed ore is then conveyed to the surface for tertiary crushing. The entire underground crushing room containing the primary, two secondaries, screens and related equipment is serviced by a 100 st (90 mt) crane with a smaller capacity fast hook. A control room is situated so the operator can observe all the crushing operations. Rotoclone collectors remove dust from the entire operation (including the fumes from the zinc pots) and discharge it to the final product belt. The Rotoclones are vented through drifts and raises to the surface. Shop facilities, electrical gear, and lubrication equipment are located

Jan 1, 1978

By H. R. Deeth, C. J. Koenig

About ten years ago nepheline syenite was introduced to the ceramic industry and the material has now found application in the various branches of the industry, namely, as a vitrifying agent in white-wares and as a source of alumina and alkalies in glasses, glazes, and porcelain enamels. Spencel described the early mining and processing developments regarding this material. Since the time of his article many research papers have appeared relating to the usage of nepheline syenite but little has been published relative to subsequent mining and processing methods. A complete indexed review of the literature was issued recently by Ohio State University.2 Since "Lakefield" nepheline syenite from Blue Mountain, Ontario (Fig I); is the only commercial ceramic-grade nepheline syenite now being marketed on this continent, discussion is limited to this operation carried on by American Nepheline Limited, Lakefield, Ont., and its subsidiary in the United States, American Nepheline Cory. at Rochester, N. Y. The Deposit Blue Mountain is a long ridge rising to an elevation of about 350 ft at its highest point above the surrounding country and extending for about six miles in a northeasterly direction across Methuen township, Peterborough County. The rock of the Blue Mountain central alkaline intrusive is fine grained, light colored and of even granitic texture. The solidified mass consists predominately of the minerals albite, nepheline and microcline in order of abundance. The average mineralogical composition for the deposit obtained by a study of 112 samples taken regularly over the whole formation is as follows:3 Volumetric Mineral Per Cent Albite.................... 54 Microcline................ 20 Nepheline................ 22 Muscovite................ 2 Mafics.................... 2 (Biotite, hastingsite, magnetite) Total................... loo The mineral nepheline (or nephelite) belongs to the feldspathoid group but is lower in silica content than are the feldspars. It is a silicate of soda, potash, and alumina (NaKAl2O32SiO2). Its presence with albite (Na2oA12O3 6SiO2) and microcline (K2O A12O3 6SiO2) gives the Blue Mountain deposit an alkali content of 15 pct and an alumina content of approximately 24 pct. While this huge alkaline mass is somewhat variable mineralogically, it has a uniform chemical composition. When the iron, mostly in the form of magnetite, is removed during processing, a remarkably uniform finished product is obtained. Geological surveying has disclosed many million tons of nepheline syenite in the Blue Mountain deposit. Diamond drilling in the area where mining is now being carried out indicates a block of about one million tons.

Jan 1, 1949

By Kenneth M. Ritchie

Mineral wool is a term applied to man-made fibers of silicate glass with useful properties resulting from their fibrous nature. In contrast with crystalline fibrous minerals such as asbestos, mineral wool fibers are amorphous, solid filaments produced by drawing from molten liquid and subsequent cooling. Chemically they are silicate glass with varying percentages of metallic oxides, especially those of aluminum, calcium, magnesium, iron, and in glass wool, sodium, potassium and boron. Other elements such as manganese, titanium, sulfur, etc., result from their presence in the raw materials used and are not purposely added. In the United States, mineral wool is a generic term and may be applied to rock, slag or glass wool. In Europe, glass silk and silicate cotton are products in the same category, but the term mineral wool is less commonly used. Current usage is to ignore the actual source and to differentiate products on a composition basis; thus rock and slag wools have about 35-45 pct of silica, while glass wool has 54 to 60 pct. Much mineral wool of slag origin is called "rock wool," and this practice is increasing, although wool made of slag from lead or copper refining is often referred to as "lead slag wool." Its greenish-gray to greenish-black dark color, due to 5-25 pct Fe (reported as FeO), distinguishes it from "white" wools made from iron, blast furnace slag containing only 1-2 pct FeO or Fe203. Most mineral wool is used for thermal insulation against heat and cold; sound absorption and isolation are probably the next most important uses. Both its thermal and acoustic values result primarily from the physical structure of the heterogeneous mixture of fibers and air which is the form in which the fibers are first obtained and handled. For this reason, within fairly wide limits, differences in chemical composition are relatively unimportant, and for most conventional applications all types are competitive in properties and value. Mineral wool intended for extreme conditions of high temperature, acid resistance and special purposes must have a chemical composition which will insure the desired properties. This may differ greatly from that of ordinary wools; for example one product approximately 98 pct Si02 and another consisting of 50 pct A1203 and 50 pct Si02 are produced and sold for high temperature service up to 2000°F or more. These are considerably more expensive to manufacture and their cost limits their use. Historical The manufacture of mineral wool consists fundamentally of a process which subjects molten material to shear and/or tensile forces that draw them into fibers. The liquids are cooled at a rate which solidifies them quickly. As a solid glass they are technically super-cooled liquids since they have no true melting point. The drawing out of glass into thin rods, filaments and tubes was known from very early times, and present day continuous production of glass filament for textiles was evolved gradually by adapting hand methods to automatic machinery. Rock and slag wool manufacture had a somewhat different development. Early explorers reported finding filamentous material

Jan 1, 1960

By Loyd R. Kern

A procedure for determining the behavior of a reservoir under a gas or water injection program was reported by Buckley and Levertt in 1942.1 This method, which allowed the calculation of the phase saturation distribution behind the front of a displacing fluid, has been extended to apply to a more general situation. The reservoir may initially contain flowing quantities of the displacing fluid, or the fluid in the reservoir may be above saturation pressure SO that solution effects are present. Production may occur behind the front as in the case of a well which is produced after breakthrough of the displacing fluid. The calculating procedure is simplified in that the graphical integration necessary to determine breakthrough saturation is eliminated by performing a direct integration and the graphical differentiation necessary to determine saturation distribution is eliminated by representing the displacing phase fraction of the flowing stream by an empirical equation. This representation results in simple expressions for the producing gas or water/oil ratio and cumulative production. INTRODUCTION A method for the calculation of the saturation distribution behind the front (interface between the displaced and displacing phases in a gas injection or water flooding operation) was reported by Buckley and Leverett in 1942. The method leads to a curve for the saturation distribution which is double-valued; consequently, part of' the curve was interpreted to be physically meaningless. That part of the curve which has physical significance was determined by a graphical integra-tion (material balance). In this paper it is shown that the integration may be performed analytically with a resulting equation for the saturation of the displacing phase at the front. The case in which the displacing fluid is initially flowing and the case in which the reservoir is initially above the saturation pressure so that some injected gas goes into solution are included in the integration. The calculations are considerably simplified by representing the fraction of the flowing stream which is oil by an exponential function of saturation. The methods is extended to apply approximately to reservoirs in which wells located between the injection well and the front are produced. An illustrative example utilizing the methods presented is included. RESERVOIR BELOW SATURATION PRESSURE In the case of a water flooding operation or in the case of a gas injection operation in which no gas goes into solution in the displaced oil, the equation for saturation in a linear flow system as a function of time and position as given by Buckley and Leverett is where* q = total reservoir volume flow rate, rvb/day A = cross sectional area of system, sq ft / = porosity of formation x = distance from injection point, ft t = time, days Pj = saturation of the displacing phase /dx velocity of planes of constant saturation, ft/day *The nomenclature used here is not the same as that used by Buckley and Leverett A complete nomenclature is given in Appendix A.

Jan 1, 1952

By Arthur Dwight

WE NOT have to go so very far back, when measured in actual years, to what may be considered the beginning of the industrial era of the great West, the discovery of gold in California in 1848, just 74 years ago. By a strange coincidence, this event occurred within a few days of the signing of the treaty with Mexico which ceded California to the United States. Needless to describe the mighty wave of humanity that hurled itself toward the setting sun in response to that call. The single thought in every one's mind was gold. The gold as they found it in placers or ledges could be so easily worked, and the product was so readily transportable, and available immediately as money, that practically no attention was paid to deposits of the base metals, in the treatment of which cheap transportation was a paramount con-sideration; consequently little progress was made in anything but gold mining until after the Civil War. The next great step was accomplished when East and West were united by the successful construction of the Union Pacific Railroad from Omaha across the great plains and through the Rockies to meet the rails of the Central Pacific coming eastward across the Sierras. The industrial history of our great West really dates from the day when those two hands of steel were joined, on the shores of the Great Salt Lake at Prom-ontory Point,. May 10, 1869. That seems a long time ago when we think of the enormous changes that have been wrought since that day, and when we regard the rich empire that has sprung up in that western land. Into the new empire thus made accessible, by this first thread of steam transportation, flocked a new brood of adventurous spirits from the older communities of the East. This way walked Fate; and as she, went, flung far the line of destiny, That bound an untracked continent to brotherhood from sea to sea; That long gray trail of dream and hope, marked mile by mile with graves that keep On every barren hill and slope some stout heart lost in dreamless sleep. Patience and faith and fortitude were willed to it and justified; Stern, homely virtues, plain and rude, eternal as the sky and wide. Nor ever sea-king dared the sea in sterner mood than these who went Strong armed to wrest from Mystery their birthright, half a continent.

Jan 4, 1922

By H. D. Kessler, M. Hansen, R. J. Van Thyne

The phase diagram of the titanium-rich portion of the system Ti-Cr-Fe to 70 pct Ti was established by means of isothermal sections at 900°, 800°, 750°, 700°, 650°, 600°, and 550°C, using arc-cast alloys. An isotherm at 800°C was determined for the section bounded by Ti, TiFe2, and TiCr2. Micrographic analysis was employed as the principal method of investigation, supplemented by X-ray diffraction and incipient melting studies. A ternary eutectoid, ß ? a+ TiCr2 + TiFe, occurs at approximately 8 wt pct Cr, 13 wt pct Fe, and about 540°C. AMONG the first titanium-base alloys in commercial production were the Ti-Cr-Fe alloys. For this reason, the Materials Laboratory, Wright Air Development Center, sponsored an investigation of the system. No information on the constitution of the titanium-rich corner was available. Vogel and Wenderott studied titanium-poor ternary alloys.' As part of this program, the binary systems Ti-Cr and Ti-Fe have been determined previously by the authors.' Other investigators have also studied the binary systems Ti-Cr,3-7' Ti-Fe.³,8-10 Both of the binary systems are characterized by the eutectoid decomposition of the ß phase. Most of the effort of the present work has been concentrated on the titanium-rich corner with compositions of less than 30 pct total chromium and iron content. The determination of isothermal sections was the experimental approach used to obtain the ternary phase diagram. Vertical sections were used to check the consistency of the isothermal sections. While this investigation was in progress, a study of the Ti-Mo-Cr system at Armour Research Foundation disclosed the existence of a high temperature modification of TiCr2 above 1300 °C.11 This allotrope has a hexagonal structure of the MgZn2 type, iso-morphous with TiFe2, whereas the low temperature modification of TiCr2 is cubic," of the MgCu2 type. The existence of allotropy in TiCr2 of course means a more complicated set of phase relationships in this general region than if the phase were monomorphic, as was first assumed. Additional studies were made late in the investigation in order to clarify the part that the hexagonal TiCr2 phase plays in the ternary phase relationships. These will be discussed in a separate section. Because they are of greatest practical significance, the phase relationships in the titanium-rich corner will be presented first, omitting the equilibria involving the hexagonal modification of TiCr2 in an effort to simplify the presentation somewhat. Experimental Procedure Materials: The titanium used in the preparation of the alloys was iodide crystal bar (99.9 pct pure) produced by the New Jersey Zinc Co. High purity chromium and iron were obtained from the National Research Corp. Table I gives the analyses of these materials. Melting Practice: Over 100 alloy ingots weighing 10 to 20 g were melted in a nonconsumable electrode arc-melting furnace. As the techniques are identical to those reported previously,12,13 they will not be detailed here. The ingots were melted in the cavity of a copper melting block insert under a slight positive pressure of helium. No measurable hardness

Jan 1, 1954

By George Hallerman, R. J. Gray

In the customary method of studying age hardening, the process of aging is interrupted by cooling the specimen and measuring its room-temperature hardness. However, the aging process may be conveniently measured while it is occurring at an elevated temperature by a series of hardness measurements at suitable time intervals. The latter method gives data void of complications that might result from processes occurring during the quench, and the data may be more indicative of the alloy's properties at elevated temperatures. The elevated-temperature hardness tester1 used in the present study employed a dead-weight loading system with a synthetic sapphire Vickers-type in-denter mounted in a molybdenum holder. The tests were performed in a vacuum of l0 to 10 torr. Hardness impressions were made by applying a 2-kg load for 15 sec. Although the hardness impressions made in the tester at elevated temperatures were measured at room temperature, the correction for thermal contraction during cooling was insignificant and therefore neglected. The two methods of obtaining age-hardening data were compared using eighteen samples of Haynes alloy No. 25* which had been annealed for 2 hr at 2250°F (1232°C). The test surfaces of the 1 by 1 by 1/4-in. samples were ground and then polished on vibratory polishers2 prior to testing. Three groups of five samples were aged at 1400°, 1650°, and 1800°F (760°, 899", and 982°C) for 4, 16, 32, 64, and 100 hr and then water-quenched. Room-temperature hardness as a function of aging time for these samples is shown in the broken lines of Fig. 1. Only one sample for each of the three temperatures was necessary to determine the hardness of the alloy at the aging temperatures with the elevated hardness tester. The specimens were heated isothermally and hardness impressions were made after various time intervals up to 100 hr. The results of these determinations were represented by solid lines in Fig. 1. Comparison of the two sets of curves shows, as expected, the hardness values determined at the aging temperatures are lower than the room-temperature hardness of the quenched specimens and the hot-hardness values reflect a strong tempera-

Jan 1, 1964

By Marcel R. Daly

In a preceding paper1 the writer has pointed out some apparent relationship between the distribution, on the surface of the globe,, of the known hydrocarbon deposits and the disposition of the principal zones of deformation of the earth's body (geosynclines). He wishes to present some further remarks on this subject. Petroleum deposits, or their derivatives or descendants, are found through the whole range of sedimentary strata, from the pre-Cambrian to the Quaternary. For instance, the prc-Beltian (Shuswap) series of the Canadian Cordillera are interbedded with limestones which are sometimes rich in carbonaceous matter (Sicamous limcstone); and the Beltian system of the same region contains layers of argillitcs and dolomitic limestones which are equally high in carbon content.2 This carbon may be interpreted as the last remnant of hydrocarbons previously contained in the rocks. On the other hand, the actual formation of hydrocarbons under conditions that would eventually permit their deposition in modern sediments is conceded by some geologists.3 Between these two extreme limits, bitumens are found indifferently in all sedimentaries. Thcy constitute a continuous series, some kind of a large family, whose individual members may be entitled to a community of origin and probably represent the different stages of evolution of the primitive, parent matter. The kinship between petroleum and such substances as asphalt, ozocerite, manjak, grahamite, albertite, etc., is well known; and E. H. Cunning-gam-Craig has recently shown how intimately shale fields and oil fields are connectcd.4 For this reason, no distinction is made in the present

Jan 1, 1918

By Marcel Daly

IN a preceding paper 1 the writer has pointed out some apparent relationship between the distribution, on the Surface of the globe, of the known hydrocarbon deposits and the disposition of the principal zones of deformation of the earth's body (geosynclines). He wishes to present some further remarks on this subject. Petroleum deposits, or their derivatives or descendants, are found through the whole range of sedimentary strata, from the pre-Cambrian to the Quaternary. For instance, the pre-Beltian (Shuswap) series of the Canadian Cordillera are interbedded with limestones which are sometimes rich in carbonaceous matter (Sicamous limestone) ; and the Beltian system of the same region contains layers of argillites and dolomitic limestones which are equally high in carbon content.2 This carbon may be interpreted as the last remnant of hydrocarbons previously contained in the rocks. On the other hand, the actual formation of hydrocarbons wider conditions that would eventually permit their deposition in modern sediments is conceded by some geologists.3 Between these two extreme limits, bitumens are found indifferently in all sedimentaries. They constitute a continuous series, some kind of a large family, whose individual members may be entitled to a community of origin and probably represent the differentt stages of evolution of the primitive, parent matter. . The kinship between petroleum and such substances as asphalt, ozocerite, manjak, grahamite, albertite, etc., is well known; and E. H. Cunninggam-Craig has recently shown how intimately shale fields and oil fields are connected. For this reason, no distinction is made in the present

Jan 8, 1917

By T. R. Young, S. A. Scott

9.5-1. Introduction. The use of pipelines to transport solids has been successfully accomplished with many different materials. One of the oldest applications is the dredging and placing of hydraulic fill. Many installations have been made and operated for long periods of time with excellent dependability, low operating cost, and low maintenance. It is not the aim of this chapter to give the engineer the answers from which to design a pipeline, but rather to supply helpful information from which to start the project. There are several phases of solids pipelining which as yet have not lent themselves to quick engineering answers. Investigations have been carried on by many, with several theories advanced by the various investigators. In recent years certain notable theoretical advances in hydraulic transportation have been achieved. Vertical transport, using balanced "leg" operation, now appears competitive with other forms of vertical transportation. In addition, horizontal transport utilizing capsules has been proven experimentally to be attractive because of lower pressure drop than the conventional methods of solid transport in fluid media. With the aid of the computer, the laborious calculations associated with pumping calculations have been greatly simplified; and with this tool the pipeline engineers of the future will undoubtedly be able to develop a more comprehensive understanding of solids-fluid transport. 9.5-2. Theory. There have been many excellent studies made and information is available in the literature, but a general comprehensive theory of pipeline transportation of solids has not been advanced. The existing flow theories will give approximations for minimum and optimum flow velocities, friction head losses, energy requirements, and pump and pipe size The principles of dynamic similarity and scaling laws are well understood for the flow of pure liquids. There are no firm methods of scaling slurry pipelines of small diameter to larger diameters except for a few empirical.

Jan 1, 1968

Jan 1, 1928

By Victor Formanek, Paul Chataignon, Maurice Rey

IT is found when floating oxidized lead ores by sulphidization, that the presence of calcium salts in the water, is usually detrimental and lowers the recovery. This effect is particularly marked in dry countries such as North Africa, where the waters often carry large amounts of calcium sulphate and where the ore may even contain gypsum. The effect of calcium salts is readily visible. Whereas in their absence cerussite is quickly stained brown and then black by sodium sulphide, in their presence the mineral remains very light in color. A similar effect is produced when barium sulphide is used as a sulphidizing agent instead of sodium sulphide. Magnesium salts have little or no effect and even tend to reduce the detrimental effect of calcium salts. A study of this phenomenon indicates that it is due to the precipitation of calcium or barium carbonate in contact with the mineral simultaneously with the formation of lead sulphide. The chemical reactions can be interpreted as: PbCO3 + Na2S = PbS + Na2CO3 CaSO4 + Na2CO3 = CaCO3 + Na2 SO4 They might also be written: PbCO3 + S = + Ca++ = PbS + CaCO3 The precipitation of calcium carbonate can be followed by the lowering of the pH with which it is accompanied. Magnesium carbonate is more soluble than calcium carbonate and usually does not precipitate under the conditions prevailing. It is interesting to note that calcium salts have no effect on anglesite (lead sulphate) because calcium sulphate is soluble, but barium salts hinder the sulphidization of anglesite because of the precipitation of barium sulphate. Remedies When calcium sulphate is present in large amounts, the softening of the water with soda ash is usually too expensive to be considered, but the precipitation of the objectionable calcium carbonate can be prevented in two different ways. One is the use of sodium hydrosulphide instead of sodium sulphide. This salt gives a lower pH than sodium sulphide and does not bring about the immediate precipitation of the calcium which remains in solution as calcium bicarbonate. The other procedure is to add ammonium salts such as the sulphate or chloride which have the property of increasing markedly the solubility of calcium carbonate. Ammonium salts have other effects such as cutting down conditioning time and accelerating flotation. They should be added to the flotation cells rather than to the ball mills. Table I. Effect of Sodium Hydrosulphide and/or Ammonium Sulphate on the Flotation of Two Oxidized Lead Ores Mibladen Ore4 La Plagne Ored Con- Tall- Con- Tail-centrate ing centrate ing Reagents Pb, Pct Pb, Pct Pb, Pct Pb, Pot Without addition of CaSO, NaS 56.0 0.68 43.4 0.65 NaSH 56.2 0.60 40.4 0.50 Na2S + (NH4)2SO4d 54.6 0.56 NaSH + (NH4)2SO4d 43.0 0.66 With addition of 40 lb/ton CaSO4 Na2S 39.4 3.85 34.0 3.21 NaSH 49.1 0.70 49.6 0.88 Na2S + (NH4)2SO4d 53.9 0.85 NaSH + (NH4)2SO4d 51.0 0.45 41.1 0.78 In table I are given the results of representative tests on two different oxidized ores. They show that the strongly detrimental effects of calcium sulphate can be offset by the two procedures outlined above. Sodium hydrosulphide is now used regularly on a mill scale on certain ores. Tests are being carried out with ammonium salts. It should be noted that malachite is subject to influences similar to cerussite. One final word of caution—when the ore is rich in primary slime, which is flocculated by the calcium salts, it may be indispensable to remove these by washing or precipitation with sodium carbonate instead of keeping them in solution by the above methods. Acknowledgment We wish to thank Socibtk Miniere & Metallurgique de Penarroya and Minerais et Metaux, for permission to publish these results.

Jan 1, 1951

By Maurice Rey, Victor Formanek, Paul Chataignon

IT is found when floating oxidized lead ores by sulphidization, that the presence of calcium salts in the water, is usually detrimental and lowers the recovery. This effect is particularly marked in dry countries such as North Africa, where the waters often carry large amounts of calcium sulphate and where the ore may even contain gypsum. The effect of calcium salts is readily visible. Whereas in their absence cerussite is quickly stained brown and then black by sodium sulphide, in their presence the mineral remains very light in color. A similar effect is produced when barium sulphide is used as a sulphidizing agent instead of sodium sulphide. Magnesium salts have little or no effect and even tend to reduce the detrimental effect of calcium salts. A study of this phenomenon indicates that it is due to the precipitation of calcium or barium carbonate in contact with the mineral simultaneously with the formation of lead sulphide. The chemical reactions can be interpreted as: PbCO3 + Na2S = PbS + Na2CO3 CaSO4 + Na2CO3 = CaCO3 + Na2 SO4 They might also be written: PbCO3 + S = + Ca++ = PbS + CaCO3 The precipitation of calcium carbonate can be followed by the lowering of the pH with which it is accompanied. Magnesium carbonate is more soluble than calcium carbonate and usually does not precipitate under the conditions prevailing. It is interesting to note that calcium salts have no effect on anglesite (lead sulphate) because calcium sulphate is soluble, but barium salts hinder the sulphidization of anglesite because of the precipitation of barium sulphate. Remedies When calcium sulphate is present in large amounts, the softening of the water with soda ash is usually too expensive to be considered, but the precipitation of the objectionable calcium carbonate can be prevented in two different ways. One is the use of sodium hydrosulphide instead of sodium sulphide. This salt gives a lower pH than sodium sulphide and does not bring about the immediate precipitation of the calcium which remains in solution as calcium bicarbonate. The other procedure is to add ammonium salts such as the sulphate or chloride which have the property of increasing markedly the solubility of calcium carbonate. Ammonium salts have other effects such as cutting down conditioning time and accelerating flotation. They should be added to the flotation cells rather than to the ball mills. Table I. Effect of Sodium Hydrosulphide and/or Ammonium Sulphate on the Flotation of Two Oxidized Lead Ores Mibladen Ore4 La Plagne Ored Con- Tall- Con- Tail-centrate ing centrate ing Reagents Pb, Pct Pb, Pct Pb, Pct Pb, Pot Without addition of CaSO, NaS 56.0 0.68 43.4 0.65 NaSH 56.2 0.60 40.4 0.50 Na2S + (NH4)2SO4d 54.6 0.56 NaSH + (NH4)2SO4d 43.0 0.66 With addition of 40 lb/ton CaSO4 Na2S 39.4 3.85 34.0 3.21 NaSH 49.1 0.70 49.6 0.88 Na2S + (NH4)2SO4d 53.9 0.85 NaSH + (NH4)2SO4d 51.0 0.45 41.1 0.78 In table I are given the results of representative tests on two different oxidized ores. They show that the strongly detrimental effects of calcium sulphate can be offset by the two procedures outlined above. Sodium hydrosulphide is now used regularly on a mill scale on certain ores. Tests are being carried out with ammonium salts. It should be noted that malachite is subject to influences similar to cerussite. One final word of caution—when the ore is rich in primary slime, which is flocculated by the calcium salts, it may be indispensable to remove these by washing or precipitation with sodium carbonate instead of keeping them in solution by the above methods. Acknowledgment We wish to thank Socibtk Miniere & Metallurgique de Penarroya and Minerais et Metaux, for permission to publish these results.

Jan 1, 1951

By Ralph Arnold

LESS than eight months ago at the annual meeting of the American Institute of Mining and Metallurgical Engineers, attention was called to the demoralizing effect of the abnormal oil production of Mexico on the oil situation in the United States, and it was predicted that this unstabilizing influence would probably become impotent in 18 to 24 months through ' the exhaustion of the principal producing fields of Mexico, unless new fields were found in- the meantime. When this statement was made, the daily production of Mexico was about 600,000 bbl. of crude oil; now it is about 350,000 bbl. No new pools of consequence have been opened, although extensions have been made to two old pools. Over 200,000 bbl., or more than half of the present daily production, comes from Los Naranjos, Amatlan and North Zacamixtle fields, in which practically every well is so affected by salt water that the potential production dropped 50 per cent. in the month of September, clearly indicating that these fields are moving rapidly toward extinction. How much longer the one remaining important pool will last is a matter of conjecture.

Jan 1, 1921

By Robert Anderson

ROUGHLY, a crack in a casting may be considered, for the moment, to be due to fracture of the alloy resulting from the stress set up by the contraction in volume on passing from the liquid to the solid state. Cracks may be external or surface, internal or deep-seated, or incipient or so-called strain cracks. Draws may appear as depressions, unevenness, and "pinching in" of the surface of a casting. Roughly, draws are due to contraction in volume and are governed largely by the same factors as cracks. A casting may be cracked, however, without being drawn. Shrinkage is a foundry term; it connotes the contraction in volume of a metal or alloy on passing from the liquid to the solid state. Pattern-makers' shrinkage is the total contraction in volume (including liquid, solidification, and solid shrinkage) that occurs when an alloy is poured into a mold. The contraction in volume of aluminum is one of the principal factors affecting the occurrence of cracks, as will be shown later, and the question of shrinkage and its control requires careful study in any treatment of cracking in castings. In the case of, sand and die castings, cracks have been attributed to a number of causes, but in the case of most light aluminum alloys, they are due to the large contraction in volume on freezing and the lack of its regulation or control. The most important factors are: (1) Contraction in volume; (2) composition of alloy; (3) quality of melting charge; (4) design of casting; (5) method of molding; (6) hardness of ramming; (7) method of gating; (8) hardness and characteristics of cores; (9) chills; (10) risers; (11) melting temperatures; (12) furnace used for melting; (13) pouring tempera-tures; (14) inclusions in alloys; (15) hot shortness of alloys; and (16) physical properties of alloys at high temperatures. Of these, the first, second, third, and eleventh to sixteenth involve ascertainable metallurgical facts; the remainder are largely matters of opinion, judgment and technical knowledge of men experienced in the production of castings.

Jan 10, 1921

[Queensland :-(Continued.) petrography of the Mount Morgan mine, LV, 263. Queensland tin mine and mill, Santa Barbara, Guanajuato, Mex., XXXVI, 227. Quenner disintegrator, XLI, 801; XLII, 15011. Quenstedt, F.: petroleum deposits, Suabia, XLVIII, 14881. Queretaro, Mex., silver mines, XXXIX, 360. Quicksilver: mining and reduction, LI, 110. Oceanic mine, Cambria, Cal., LI, 110. Quicksilver and iron decompose silver sulphide, XL, 872. Quicksilver deposits: China, -XL111, 49. Pacific slope, XXXVI, 1311.. Siberia, Vhdivostok district, XLIV, 16001.]

Jan 1, 1918

By H. H. Pentz

This paper gives the derivation of a practical formula for the calculation of slopes in seismic reflection prospecting. The derived formula is an approximation and can be used where the slope of the reflecting horizon is less than 250 ft. per 1000 and the depth to the reflecting horizon is greater than 2500 ft. The slope of sediments in oil regions is generally considerably less than 250 ft. per 1000. This is particularly true of the Gulf Coast, with the exception of the salt domes, which usually have the sediments at a greater slope than 260 ft. per 1000. Derivation In Fig. 1, o represents the image of the shot point a. Then the length of the path acb is equal to ob and ae'd is equal to od. In the triangle aob, p is equal to ob, x is equal to , and c is equal to ao. The angle u is the apparent dip of the reflecting horizon. Angle oab is equal to (90" - u). The quantity m is the slope of a line tangent to the curve, defined by equation 1, at the point (p, x). The quantity m' is the slope of the line tangent to the curve at the point (p', 2').

Jan 1, 1940

By H. H. Pentz

This paper gives the derivation of a practical formula for the calculation of slopes in seismic reflection prospecting. The derived formula is an approximation and can be used where the slope of the reflecting horizon is less than 250 ft. per 1000 and the depth to the reflecting horizon is greater than 2500 ft. The slope of sediments in oil regions is generally considerably less than 250 ft. per 1000. This is particularly true of the Gulf Coast, with the exception of the salt domes, which usually have the sediments at a greater slope than 260 ft. per 1000. Derivation In Fig. 1, o represents the image of the shot point a. Then the length of the path acb is equal to ob and ae'd is equal to od. In the triangle aob, p is equal to ob, x is equal to , and c is equal to ao. The angle u is the apparent dip of the reflecting horizon. Angle oab is equal to (90" - u). The quantity m is the slope of a line tangent to the curve, defined by equation 1, at the point (p, x). The quantity m' is the slope of the line tangent to the curve at the point (p', 2').

Jan 1, 1940

The American Petroleum Institute, 250 Park Ave., New York, N. Y. Lacey Walker, Secretary. A complete price list of publications will be sent upon application. The American Petroleum Institute issues a variety of publications; in addition to the Daily Oil Digest ($25 per year) and a weekly Statistical Bulletin ($12.50 per year to nonmembers), a Quarterly is published ($4 per year to nonmembers). Books published by the Institute: American petroleum supply and demand, $3; A series of "Petroleum facts and figures" for each of the years 1928, 1929, 1930 and 1931, $2 for each copy; Function of natural gas in the production of oil, $1; Bibliography of organic sulphur compounds, $4; and "Oil" (Oil Industry Series in one volume), 50 cents per copy. Volumes of the first six annual Meeting Proceedings are out of print, but the Proceedings for the 7th annual meeting in 1926

Jan 1, 1933