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By P. L. De Bruyn

The adsorption density of dodecylammonium ions at the quartz-solution interface has been Theadsorptiondensitydetermined as a function of collector concentration and pH. A ten thoushasbeenandfold range of amine salt concentration was covered at neutral pH. Experimental results show that over a thousandfold concentration range at neutral pH, the adsorption density (I) is proportional to the square root of collector concentration. Except at high concentrations, I increases with increases with increasing pH, but in general this effect is surprisingly small. . , . . A critical pH curve has been established for the flotation of quartz with dodecylammonium acetate. The conditions along the flotation curve are correlated with the adsorption measurements. THE behavior of collectors at the mineral-solution interfaces is usually explained in terms of an ionic adsorption process. Through the distribution of collector ions between the solid surface and the- co-existing solution phase the mineral is believed to acquire a water-repellent surface coating. Quantitative adsorption studies have been made on simple flotation systems1-4 only within the last few years. Such investigations were made possible by the adoption of the radiotracer method of analysis. As a consequence of these studies a new parameter has been added to aid the understanding of the flotation process. The research investigation to be discussed in this paper was undertaken to obtain a better understanding of the behavior of a cationic-type collector. This objective was approached through the determination of the distribution of dodecylammonium acetate between the quartz-solution interface and the solution as a function of the collector salt concentration and pH. To bring this investigation to focus on the more practical aspect of flotation research, an attempt was also made to correlate the adsorption results with actual flotation tests. Quartz: A —100 mesh ground crystalline quartz was infrasized; the products of the third and fourth cones were mixed together and reserved for experimental purposes. This stock material was cleaned by leaching in boiling concentrated HC1. After leaching the quartz was rinsed with distilled water until the filtrate showed no trace of chloride ian. It was then washed several times and dried. The qwrtz had a specific surface of 1400 cma per g as deterhined by the krypton gas adsorption method. Collector: The distribution of dodecylammonium acetate between the quartz surface and the solution phase was determined by the radiotracer method of analysis with carbon 14 as the tracer element. The radioactive amine salt with C" synthesized into the hydrocarbon chain5 was supplied by Armour and Co. The tracer element was located adjacent to the polar group. The radioactive salt as received had a specific activity of about 0.14 mc per g. When desired, dilution of this activity was effected by addition of non-radioactive dodecylammonium acetate also supplied by Armour and Co. ........ All other inorganic reagents used in this research were of reagent grade. Conductivity water was used for making up all solutions. Adsorption Tests: Two different experimental methods were used. In the first, to be designated as the agitation method, a weighed amount of quartz and a measured volume of amine salt solution were agitated in a 100-ml or 50-ml glass-stoppered pyrex graduated cylinder. The cylinder was filled with solution up to the stopper, since erratic results were obtained when an air space was left over the suspension. Time of agitation varied from 1 to 2 hr. Preliminary tests at different agitation times showed that the amount adsorbed remained constant for all agitation times exceeding 1/2 hr. After this conditioning period, the solids were separated from the solution by filtration through a Buechner fritted-disk funnel. The solution was re-circulated 10 times or more to allow the fused silica disk to come to equilibrium with it. Determinations of the amount of amine adsorbed on the frit itself indicated that this amount was less than 10 pct by weight of the amine acetate abstracted by 10 g of quartz. The funnel with quartz covered by a thin layer of solution was then centrifuged for approximately 5 min, at which time the moisture content of the solids was reduced to about 5 pct by weight. The wet quartz was blown into a tared beaker, re-weighed and allowed to dry at room temperature. A final weighing was then made to determine the moisture content. The second experimental method, similar to the procedure adopted by Gaudinand Bloecher,' will be referred to as the column method. Two liters of solution were passed through a bed of quartz contained in a Buechner funnel attached to a pyrex separatory funnel by means of a ball and socket joint. Preliminary tests showed that increasing the volume of solution above 2 liters does not give a measurable increase in adsorption. From 4 to 4 1/2 hr were required for 2 liters of solution to pass through the column. The moisture content of the quartz was again reduced to a minimum by centrifuging. A slightly modified column apparatus was used for experimenting with alkaline amine solutions. The same basic unit was used, but the underflow from the Buechner funnel was again fed into a Separafory

Jan 1, 1956

By C. W. Spencer, F. N. Rhines, R. J. Knight

Ametallographic study has been made of the peritectoid transformation as it occurs in two Ag-A1 alloys, containing 6.0 and 6.9 wt pct Al, respectively. After equilibrating at 475°C, these alloys were transformed isothermally just below the peritectoid temperature which lies at about 450°C.1-3 Peritectoid transformation in this alloy system consists in the reaction of a and 5 to form µ. The crystal structures of the a, µ, and 5 phases have been determined as face-centered-cubic, 6 manganese, and hexagonal-close-packed, respectively. At the peritectoid temperature their equilibrium compositions are approximately 5.85, 7.02, and 7.24 wt pct (19.92, 23.2, and 23.8 atomic pct) aluminum."" The transformation might be expected to occur principally at the interface between the a and 5, but such is not the case. Instead, the major part of the transformation occurs by the direct (and perhaps initially diffusionless) conversion of 5 to µ. The composition range of the forming µ nearly overlaps that of the parent at the temperature of transformation" so that little, if any, composition change is required. Transformation proceeds by the nucleation of µ at points upon the external surface of the sample and sweeps through the 5 phase, leaving the a initially almost undisturbed. Subsequently, the a phase participates in the transformation by being partly or totally converted to µ. Specimens approximately 1/4 x 1/4 x 1/16 in. were cut from cast ingots, previously equilibrated 68 hr at 588°C. The specimens were held for 3 hr at

Jan 1, 1958

By Joseph G. Mravec

ALL manufacturers of high-quality steel are conscious of the detrimental effects of nonmetallic inclusions in steel. Entrapped refractory inclusions are particularly troublesome when encountered during machining operations. Modern cutters used for machining such parts as gears and pinions arc costly tools, which are readily nicked and damaged by hard inclusions. A single hard inclusion can so nick and damage a delicate finishing tool as to necessitate its regrinding. Frequent exposure of hard inclusions during machining, therefore, decreases cutter life, lowers production, and increases rejections of defective parts. The importance of cleanliness of the steel, therefore, is obvious and the production of the cleanest possible steel is a continual challenge to the steelmaker. Inclusions in steel may be classified in two general groups: (i) deoxidation-type inclusions, and (2) refractory-type inclusions. The latter consist of entrapped material eroded from the refractories used in melting and conveying of the steel from the melting furnace to the ingot molds. It is the purpose of this paper to dwell mainly on steel cleanliness as it is affected by various refractories used in the melting furnaces, the ladles, and the ingot molds.

Jan 1, 1947

By Abdel Kadir Attia, Haydn H. Murray, Adel Abdel Azin, Sabah N. Boulis

An extensive reconnaissance survey of bentonitic clays in Egypt was carried out from 1982 to 1984. X-ray diffraction, differential thermal analysis, electron microscopy, and physical property evaluations were used to identify the mineralogy and assess their industrial potential. Samples were collected from a number of localities, namely Qasr El-Sagha (Fayum), Cairo-Alexandria Desert Road (Western Desert), and Qattamia area (Eastern Desert). This paper reviews the geological occurrence, the mineralogical and chemical characteristics, and the potential utilization of these deposits.

Jan 1, 1985

By C. E. Webber

THE economical recovery of the valuable constituents from the effluent of gas-con-densate wells has developed into a problem of balancing the cost of recovery against the cost of compressing the residual gas back into the formation. A possible method of extracting the gasoline and distillate from the natural gas is by oil absorption at high pressures. In order to design and evaluate an absorption plant, fundamental data on the composition of the coexisting hydro-carbon vapor and liquid phases at various temperatures and pressures are essential. A review of the literature indicated that the necessary data for the design of such plants are lacking. The nearest approach to desired published data is that of Katz and Hackmuth,5 who experimentally deter-mined the composition of the coexisting vapor and liquid phases in a natural gas-crude oil system at pressures up to 3000 lb. per sq. in. and at temperatures from 40° to 200°F. This paper presents the results of the experimental determination of the equilib-rium distribution of the hydrocarbons methane through hexane between natural gas and a typical absorber oil. The ranges of temperature and pressure chosen were from 33° to 180°F. and from 100 to 5000 lb. per sq. inch.

Jan 1, 1940

By T. W. Smoot

Bentonites are composed chiefly of montmorillonites which are clay minerals generally distinguished from other clay minerals by their surface activity and extremely fine particle sizes. The uses of bentonite are many and varied, depending principally on one or more of the following characteristics: 1) Thixotropy, 2) Dispersion, 3) Plasticity, 4) Swelling, 5) Surface area, activity, ab- and adsorbtive properties. Some of the major uses of bentonite are briefly reviewed as are the mineralogical and physical properties. The uses of X-ray diffraction, differential thermal analysis and other tests for physical properties are reviewed as to their uses in evaluation. In the past 40 years, the industrial uses of bentonite have grown to include many applications. The physical and chemical properties of bentonites are such that they can be used as catalysts, adsorbants, plasticizers, binders, drilling muds, and pelletizers. Not all bentonites, however, can be used for all of these purposes and some are probably of little or no value for any use. The purpose of this paper is to briefly review the mineralogical, physical, and chemical characteristics and variations of bentonites. The determination of these characteristics and their uses in industry are also reviewed so that these determinations can be used as guides for evaluation. DEFINITION OF BENTONITE The word bentonite, as used in this paper, refers to a clay material, usually (but not necessarily) the result of the in-place-weathering of volcanic ash. Its mineralogical composition is dominated by the clay mineral montmorillonite and generally carries other clay minerals and silica minerals as the major 'impurities'. For this discussion, such a definition is justified since most of the economic uses of bentonite~ depend upon the physical and chemical characteristics of the montmorillonite minerals involved. The terms montmorillonite and bentonite have been used almost interchangeably in industry although the latter is much more commonly used. Therefore, where montmorillonite is discussed, it should be understood that the major feature of a bentonite is the subject. STRUCTIJRE OF MONTMORILLONlTE The economic importance of bentonites is generally based on one or more of the following characteristics of montmorillonite: 1) high-thixotropy and easy dispersion in water, 2) high-plasticity, 3) swelling properties, 4) large surface area/unit mass, 5) high surface activity, and 6) adsorptive properties. To understand these properties, an appreciation of the structural scheme of montmorillonite is helpful. Montmorillonite IS one of the three-layer clay minerals composed essentially of hydrous aluminum silicates. The essential building blocks of these layered silicate:; are: 1) silica tetrahedron composed of a silicon atom surrounded by four oxygen atoms, and 2) aluminun (iron, magnesium, etc.) octahedral unit that, ideally, has one of these atoms surrounded by six hydroxal units. Fig. 1 is a diagrammatic sketch of the montmorillonite structure. In the montmorillonite structure, the tetrahedron are pointed inward and attached to the octahedral units so that the O= atoms replace the hydroxal units where they are bonded; hence two-thirds of the hydroxal units

Jan 1, 1962

By Walton J. Greer, System By John E. Owen

The guard electrode system measures the resistivity of formations by employing a thin disk of current which is caused to flow perpendicular to the bore hole. The control of this current disk is obtained in a brute force manner through the use of relatively long equipotential electrodes above and below the measuring electrode. The log obtained from the system is free of "lag," "plateau," "shadow," "reflection" and other distortions evident on conventional logs. The proportionate contributions of the hole size and invaded zone resistivity to the apparent resistivity reading are reduced when the mud and filtrate resistivities are lower. Thus, the guard system favors the use of conductive muds. The mathematical development of the theory is given in an appendix. Equations are derived to evaluate the effects of mud resistivity, hole size, invaded zone resistivity and depth, and the true formation resistivity. Sample logs from several provinces are reproduced and compared with conventional electric logs to illsutrate the much greater detailed lithology that can be presented by the guard electrode system. INTRODUCTION With increased ability of those in the petroleum industry to analyze formation characteristics from electrical resistivity data, there has become apparent the need for more precise measures of that parameter. The measurement of the resistivity of a homogeneous and isotropic material can be made simply when the body of the material is infinite in all dimensions and the measuring electrodes can be placed within the body. In such a case, the current leaving an electrode follows a spherical distribution and the mathematical expression for the potential level at any distance from that electrode can readily be derived.'.' If it is considered that the active electrodes are within a bore hole filled with mud of a resistivity different from that of the formation. the current does not flow in a spherical pattern near the current source or sink, and the calculations of potential levels become more difficult. The additional consideration of a section of formation invaded by mud filtrates, and thus having resistivity different from either that of the mud, the adjacent formations or of the undisturbed formation, makes the mathematical problem extremely complex. Should the vertical dimensions of the formations be considered as finite. the problem becomes so complex as to preclude reasonable solution. Yet, even these considerations have not described adequately the conditions encountered in a large proportion of the wells to be studied. In efforts to evaluate the effects of the various conditions. combinations of twn, three. and four electrode logging con- figurations of the conventional types have been used. The resulting logs have left much to be desired in some provinces. It has become apparent that the use of such configurations will not result in adequate measurements being made, particularly in cases where the formation is composed of thin sections. If all the current of a resistivity measuring circuit is made to flow through the formation opposite the exploring electrode, many of the shortcomings of the conventional measuring system are eliminated. In the guard electrode method of electrical well logging to be discussed in this paper, the current is so controlled by causing it to flow in a thin disk normal to the axis of the logging tool. EARLY HISTORY The guard electrode method of electrical well logging in its early years was a joint development by the Geophysical Research Corp. and the Amerada Petroleum Corp. The method was first experimentally investigated by means of model studies. The results of these studies indicated that current focusing systems properly applied to electrical well logging

Jan 1, 1951

By System By John E. Owen, Walton J. Greer

The guard electrode system measures the resistivity of formations by employing a thin disk of current which is caused to flow perpendicular to the bore hole. The control of this current disk is obtained in a brute force manner through the use of relatively long equipotential electrodes above and below the measuring electrode. The log obtained from the system is free of "lag," "plateau," "shadow," "reflection" and other distortions evident on conventional logs. The proportionate contributions of the hole size and invaded zone resistivity to the apparent resistivity reading are reduced when the mud and filtrate resistivities are lower. Thus, the guard system favors the use of conductive muds. The mathematical development of the theory is given in an appendix. Equations are derived to evaluate the effects of mud resistivity, hole size, invaded zone resistivity and depth, and the true formation resistivity. Sample logs from several provinces are reproduced and compared with conventional electric logs to illsutrate the much greater detailed lithology that can be presented by the guard electrode system. INTRODUCTION With increased ability of those in the petroleum industry to analyze formation characteristics from electrical resistivity data, there has become apparent the need for more precise measures of that parameter. The measurement of the resistivity of a homogeneous and isotropic material can be made simply when the body of the material is infinite in all dimensions and the measuring electrodes can be placed within the body. In such a case, the current leaving an electrode follows a spherical distribution and the mathematical expression for the potential level at any distance from that electrode can readily be derived.'.' If it is considered that the active electrodes are within a bore hole filled with mud of a resistivity different from that of the formation. the current does not flow in a spherical pattern near the current source or sink, and the calculations of potential levels become more difficult. The additional consideration of a section of formation invaded by mud filtrates, and thus having resistivity different from either that of the mud, the adjacent formations or of the undisturbed formation, makes the mathematical problem extremely complex. Should the vertical dimensions of the formations be considered as finite. the problem becomes so complex as to preclude reasonable solution. Yet, even these considerations have not described adequately the conditions encountered in a large proportion of the wells to be studied. In efforts to evaluate the effects of the various conditions. combinations of twn, three. and four electrode logging con- figurations of the conventional types have been used. The resulting logs have left much to be desired in some provinces. It has become apparent that the use of such configurations will not result in adequate measurements being made, particularly in cases where the formation is composed of thin sections. If all the current of a resistivity measuring circuit is made to flow through the formation opposite the exploring electrode, many of the shortcomings of the conventional measuring system are eliminated. In the guard electrode method of electrical well logging to be discussed in this paper, the current is so controlled by causing it to flow in a thin disk normal to the axis of the logging tool. EARLY HISTORY The guard electrode method of electrical well logging in its early years was a joint development by the Geophysical Research Corp. and the Amerada Petroleum Corp. The method was first experimentally investigated by means of model studies. The results of these studies indicated that current focusing systems properly applied to electrical well logging

Jan 1, 1951

By W. J. Taylor

SOME eight years ago I became interested to a considerable extent in one of the well-known deposits of sulphury iron ore in New Jersey, and, as a consequence, soon became interested in the subject of the elimination of the sulphur. On investigation I found that no department of pig-iron manufacture had received less attention than that of roasting or calcining ores for the elimination of sulphur, carbonic acid, water, etc. My first devices to eliminate sulphur were naturally in the lime-kiln line, with solid fuel mixed with the ore, in the same way as common lime is burnt with small coal. While this process will succeed tolerably well for carbonates or calcareous ores, even though they contain sulphur as sulphates, I soon found it would not answer for our magnetites, which are very hard and dense, carrying from 2 to 5 per cent. of sulphur as pyrites, and become very sticky as soon as any attempt is made to roast them at a high heat. Some laboratory experiments developed the fact that the nearer the gaseous current surrounding the hot ore approached in composition pure atmospheric air the more rapidly the sulphur was oxidized, while in an atmosphere composed largely of carbonic oxide, carbonic acid, and nitrogen, it seemed almost impossible to reduce the sulphur more than one-half, which was a confirmation of the well-known fact that just one-half of the sulphur in pyrites volatilizes very easily, and that the trouble is mainly to remove the remainder. It was thus apparent that the atmosphere surrounding the ore was of as much importance as the temperature. This led to the trial of a kiln to heat the ore by conduction through the brick. It was divided into ore-chambers, which were surrounded with flues, through which the products of combustion of gaseous fuel passed without coming in contact with the ore. We did not, however, succeed by this arrangement in getting more than a cherry-red heat, which, of course, was too low to accomplish anything. I had at this point become convinced – 1st. That gaseous fuel only would accomplish the work successfully. 2d. That since a high temperature was required to insure a rapid oxidation of the sulphur, and also to make the ore open and porous,

Jan 1, 1881

By A. J. Erickson, W. W. Atkinson

Concepts developed in a geologic data recording system at the Victoria, Nevada breccia pipe-skarn copper mine, are not fundamentally new, but represents expansion of earlier ideas. The basic philosophy is that a high quality geologic data base is necessary and should be complete, clear, standardized, neat, quantitative, and readily useable. It may be multi-colored or simply black and white. Graphic, descriptive and quantitative recording of data is essential. A format for core logging is presented and discussed, as well as a mu1tiple overlay system for recording data gathered in surface mapping.

Jan 1, 1984

By Raphael Titi-Manyaka, I. Iwasaki

Chlorination and chloridization behaviors of pyrite, pyrrhotite, chalcocite, covellite, chalcopyrite, bornite, heazlewoodite, millerite, and pentlandite in chlorine, gaseous ferric and sulfur chlorides were investigated by thermogravimetric analysis. The reaction mechanisms are discussed in terms of theoretical weight changes, thermodynamic calculations, and X-ray analyses of reaction products. The experimental findings are in direct application to the development of a scheme for producing nonferrous metal chlorides, elemental sulfur, and ferric oxide from complex sulfide flotation concentrates.

Jan 1, 1977

By D. E. Pickett, E. G. Joe

In accordance with good industrial practice, Canadian metallic-ore concentration plants have always recycled a high proportion of process water to save reagents, save power, conserve water resources, and to protect the community water supplies, to give only a few reasons. In the last few years there has been awakened public concern for the environment and, consequently, government regulations have been added as additional reasons. Present recycling practices are summarized as a basis for improved plant design and operating procedures and for further research. In addition, an attempt is made to determine why plants do not recycle water in certain situations. Although not all Canadian mills are covered, the many examples given indicate the problems and the effort being made to solve them. Wherever available, the chemical quality of the water and the process requirements are indicated as well as the other parameters affecting water recycling at each operation.

Jan 1, 1975

By Robert H. Richards

(Read at the Wilkes-Barre Meeting, May. 1877.) THE Institute of Mining Engineers has shown so much interest in the educational problem of profitably combining theory and practice, that it seems especially appropriate to lay before its members the methods and aims of the mining laboratory of which I have charge, and in which one form of combination of hand with head work is now being tried. If anything may be contributed toward the solution of this problem by the discussion which follows, my purpose will be attained. Whether it was wise or not to establish a mining school so far from the principal mining centres, does not now enter into the question. Given, a mining school already begun, how shall it be made most efficient in developing engineers who are trained to think for themselves as well as versed in the works of others? This is the ques¬tion with which we have had to deal. In considering the bearing of this laboratory work upon the students' preparation, it will be convenient to take it up under five different heads 1. The methods and aims of the laboratory. 2. The advantage to students of having a part, at least, of their practical work in the curriculum of their school. 3. The advantage to be derived by mines and works. 4. Degree of accuracy which may be attained in working ores on a small scale. 5. Results of work in the laboratory. 1. The Methods and Aims of the Laboratory.-During the May meeting of 1873, held in Boston, I had the privilege of reading before you a paper stating the plans and aims of this laboratory. Since that time we have been constantly following out those plans, and are more than ever convinced that we are working in the right direction. We do not feel that the time we have spent has been in any sense thrown away. Perhaps the aims of the laboratory can be most clearly shown by illustration. Many young engineers leave school thinking that they know everything. They go to the works, and expect to teach the superintendent something and the men a good deal, regardless of the fact that it is this spirit that has prejudiced workmen against schoolmen. They are often more trouble than they

Jan 1, 1878

By Charles Parmelee

When Professor Silliman made his first examination of the newly-discovered Pennsylvania rock oil in 1859, he noted that different rates of heating produced different results in fractionation—longer heating produced larger percentages of light fractions. In 1862, it was found that when petroleum vapors are condensed in the still crown and dropped back into the hot liquid, the result of the distilling operation is materially modified. These early dates mark the beginning of what is called cracking petroleum and is explained as separating the component parts of the hydrocarbon molecules into more and smaller groups of the same elements. The phenomena were utilized for the next 30 years to increase the yield of burning oil. The procedure was that regularly practiced today in dry or destructive distillation. Considerable scientific study was given to the subject from 1862 to 1905, and a number of patents were obtained, but the work done was not continuous or intensive until about 1905, when the increasing demand for gasoline attracted attention of petroleum refiners to the possibilities of cracking. The first equipment built and operated essentially for cracking petroleum on a large scale was placed in successful operation in 1912. The commercial practice is, therefore, less than 15 years old. Comprehensive intense study of the controlling factors during this period has resulted in rapid increase in our knowledge, and material improvement has been made in the practice of the art. It is the purpose of this paper to outline briefly the state of our knowledge and to suggest some of the questions which are attracting attention of researchers at the present time. The major purposes for which petroleum hydrocarbons, including natural gas, are or have been cracked are: 1. To obtain products used to increase the heat value and illuminant content of artificial gas. 2. During the World War, to increase the supply of toluol. 3. To increase the amount of products capable of conversion into industrial chemicals. 4. To produce pure carbon.

Jan 1, 1927

By Francis L. Sperry

Up to within a few years, the consumption of nickel has been more directly dependent upon the available supply than that of any of the other useful metals. The Gap mine, in Lancaster county, Pennsylvania,* has been, for the last quarter of a century, the only property in this country furnishing nickel in paying quantities. Its yearly output was about 300,000 pounds of metallic nickel, or nearly half the amount used annually in the United States. Foreign nickel from mines on the New Caledonia islands, in the South Pacific, found entrance into our markets as the production of the Gap mine fell off. The price of nickel was constantly maintained, and no special effort was made to extend its use. Over-production was cautiously guarded against, and all surplus metal was held by the banking-houses of the Rothschilds, who assumed the bonded indebtedness of the Sociètè le Nickel. The opening of the Ontario nickel-mines has, however, brought about a radical change; and nickel from the Sudbury district can be delivered in New York within four days, and in European markets within two weeks, as against two months consumed in transporting South Pacific ores. Former prices have been irretrievably smashed, and European trade-journals comment favorably on the influence which Canadian nickel has had in making lower prices, and breaking the backbone of the " nickel trust." Production and Costs. The quantity of nickel produced and the prices which it commanded may be briefly summarized as follows: The total production of the world from 1840 to 1860 was about 100 to 250 tons yearly of metallic nickel; from 1860 to

Jan 1, 1896

By Constantine Michalopoulos, Roger C. Van Tassel

Commercial demand for gold in the United States is important. It has a large impact on the total world commercial and overall non-monetary demand. Given the present free market price and our need to import gold, it has a substantial adverse effect upon our international payments position. But, according to most recent estimates, the United States demand is perhaps no more than 20% of the world as a whole. In 1971, United States consumption was estimated at 215.6 tons out of a total of 1,412.1 tons 1. This figure is very close to the 16% figure developed by Consolidated Gold Fields as the average for the years 1968-1970.2 Surveys of both production and use of gold on a world-wide basis are not new. With the bulk of gold production in only a few countries, it has been possible to develop fairly reliable series on gold output. Estimates have been developed on the known reserves of gold and probable output at various prices.3 On the demand side, figures have been somewhat less complete and reliable. The Bank for International Settlements and the Director of the United States Mint have regularly published estimates of commercial use in major industrial countries. The IMF has issued an increasingly comprehensive survey in its Annual Reports. The IMF has attempted to cover all nations-not restricting its efforts to major industrial nations-and has tried to estimate both gold taken for commercial uses (Estimated Industrial and Artistic Use) and for private hoarding. Their method is to begin with data on free world output plus any net sales by the Soviet Union, subtract any additions to world monetary stocks (or add to available supply for any net reductions in world monetary stocks), subtract estimates for commercial demand and have left as a residual an estimate for private hoarding. The method is straightforward and simple but the quality of the data is suspect. Industry sources tend to believe the figures as biased on the low side because of a persistent tendency to underreport gold movements.4

Jan 3, 1974

By S. Epstein

THE new low-alloy high-strength steels are obviously here to stay. With 75 per cent higher yield strength and 50 per cent higher tensile strength than plain carbon structural steel, they permit 20 to 40 per cent weight savings and 10 per cent or more increase in pay load in the con-struction of railroad cars, buses, trucks, and a great variety of material-handling equipment. Their cost is low enough so that the extra cost of the new lighter construction over that with carbon steel offers an attrac-tive self-liquidating investment; in some instances new construction with these low-alloy steels may even be as cheap as with plain carbon steel. A considerable and rapidly growing demand for the low-alloy steels has already sprung up. The many steel compositions that have appeared on the market lately 18,27,28,29,30 to meet this demand would seem to indicate that no single composition is uniquely fitted for the purpose. However, no doubt some compositions are more suitable than others. The purpose of this study was, therefore, to compare the effects of the various alloying elements that might be used in the low-alloy steels in order to choose the metallurgically most logical composition, paying due regard, of course, to the economic aspects involved.

Jan 1, 1936

By C. M. Marquardt

The minerals industry in general should bow in homage to the uranium milling industry. Those in the uranium milling industry have "spark- plugged" more progress in the application of instrumentation and control in the last 5 years than has been made in 50 years by the industry in general. Part of this real progress in the application of instrumentation and control has been born of necessity because milling processes are more complex. A lot of the impetus for instrumentation and control has come from the fact that the industry is new, the processes are new, and there are no hide-bound conventions to overcome. Part of it comes from the fact that much of processing is more chemical than metallurgical and the thinking of the process chemist has carried over into the plants. One need not elaborate on what instrumentation has done for the process chemical industries. Each new mill that is constructed, if of appreciable size, seems to employ more instrumentation than the previously completed plant. Plant A makes a break-through in the application of instrumentation to a particular part of the process and Plant B accepts this and goes one step farther, while Plant C, anticipating Plant B, makes two or three more steps before Plant B is entirely leveled out.

Jan 9, 1958

By Leonard C. Grimshaw

Diffusion of carbon from gases into iron has been the object of much research, because of its long recognized importance in carburizing processes, but the direct diffusion of carbon from steel into iron has received relatively little attention. Because of the increasing use of clad metals in industry, direct diffusion from steel into iron is becoming of practical importance. Therefore, the object of this investigation was to study the diffusion of carbon from several different kinds of steel directly into relatively pure iron, realizing that elements in the steels other than carbon might influence the rate of carbon diffusion. The previous work on diffusion of carbon into iron has been considerable, and includes many reports in foreign languages. This work has recently been well reviewed by Mehll and Krynitsky12 and the reader is referred to their excellent bibliographies. Methods of Study There are two main methods by which the direct diffusion of carbon from steel into iron may be studied. In one method, steel is first decar-burized in part, and diffusion of carbon then allowed to take place from the steel into the decarburized steel. This method is open to two serious objections: (1) the decarburized steel is not iron, but contains elements such as manganese, silicon, chromium or tungsten, which may be an essential part of the steel under study, and which may seriously influence the diffusion of carbon into the decarburized area; (2) there is from the start of diffusion an unknown carbon-concentration gradient between the steel and the decarburized area. Another method, which possesses neither of these disadvantages, is to study diffusion from steel into a thick plating of electrolytic iron. Herc the chief difficulty is to secure an electrolytic deposit of iron upon steel without introducing an oxide film at the interface that will interfere with diffusion. The author is able to deposit iron upon any kind of steel without introducing an oxide film at the interface, so that diffusion of elements from the steel into the iron is free to proceed unhindered.

Jan 1, 1938

By Leonard C. Grimshaw

Diffusion of carbon from gases into iron has been the object of much research, because of its long recognized importance in carburizing processes, but the direct diffusion of carbon from steel into iron has received relatively little attention. Because of the increasing use of clad metals in industry, direct diffusion from steel into iron is becoming of practical importance. Therefore, the object of this investigation was to study the diffusion of carbon from several different kinds of steel directly into relatively pure iron, realizing that elements in the steels other than carbon might influence the rate of carbon diffusion. The previous work on diffusion of carbon into iron has been considerable, and includes many reports in foreign languages. This work has recently been well reviewed by Mehll and Krynitsky12 and the reader is referred to their excellent bibliographies. Methods of Study There are two main methods by which the direct diffusion of carbon from steel into iron may be studied. In one method, steel is first decar-burized in part, and diffusion of carbon then allowed to take place from the steel into the decarburized steel. This method is open to two serious objections: (1) the decarburized steel is not iron, but contains elements such as manganese, silicon, chromium or tungsten, which may be an essential part of the steel under study, and which may seriously influence the diffusion of carbon into the decarburized area; (2) there is from the start of diffusion an unknown carbon-concentration gradient between the steel and the decarburized area. Another method, which possesses neither of these disadvantages, is to study diffusion from steel into a thick plating of electrolytic iron. Herc the chief difficulty is to secure an electrolytic deposit of iron upon steel without introducing an oxide film at the interface that will interfere with diffusion. The author is able to deposit iron upon any kind of steel without introducing an oxide film at the interface, so that diffusion of elements from the steel into the iron is free to proceed unhindered.

Jan 1, 1938