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By S. W. Zehr, G. S. Murty, W. A. Backofen

AN observation by Squires, Weiner, and phillipsl has stimulated interest in a mechanism of deformation at high temperature (above -0.5 of the absolute melting point) that is not usually thought to be involved in the creep of metals. They found precipitate-free or "denuded" zones along grain boundaries normal to the stress axis in tensile specimens of a hydrided Mg-1/2 wt pct Zr alloy after slow straining at 450° and 500°C. Their suggestion that the zones were a result of directional diffusion of magnesium atoms was supported with calculations from Harris and Jones2 which also tended to identify the process as Nabarro-Herring (N-H) creep3,4—a process that is characterized by Newtonian viscosity, with stress (o) directly proportional to strain rate (C), and one that proceeds by lattice diffusion. Material transport by diffusion along grain boundaries is an alternative basis for Newtonian viscosity, as demonstrated by Coble,5 and is favored over N-H creep for fine grain size and lower temperature.6 In either case, the strain rate sensitivity of flow stress, defined as m = d log o/d log E (which commonly appears in the empirical a = KEW), is unity. The experiments to be described here gave metallo-graphic indications of diffusional creep which were no less clear than those just cited, but the associated m (as measured by the method of Ref. 7) was much more like that of a Bingham material. For true Bingham behavior, (a — ao) E, where oo is an initial yield stress. Therefore, even if flow after yielding should occur by diffusional transport, m must increase from 0 as < is raised to reach unity only in the limit as One result is that the resistance to tensile necking conferred by Newtonian viscosity is lost, which would become increasingly apparent through the formation of more sharply defined necks as 6 is lowered. That trend appeared in these experiments. Most of the work was done on an extremely finegrained alloy of magnesium with -6 wt pct Zn and ½ wt pct Zr (Mg ZK60); the initial mean-intercept grain diameter, L, was 0.55 µ. Shown in Fig. l(a) is a germanium-shadowed carbon replica of the surface of a specimen that was coated with silicone oil,* heated to 270°C under a helium atmosphere, and then stretched locally -200 pct at an initial E = 3.3 x 10-5 sec-1. Under

Jan 1, 1969

By W. F. Hergert, L. H. Banning

Experimental production of Al-Si alloys, containing from 33 to 55 pct Al, by direct reduction of aluminum silicates in a three-phase arc furnace is described. Advantages of a smelting technique utilizing hogged wood waste as part of the reductant and for temperature control are discussed. WORK on the problem of producing aluminum by smelting has been in progress since the middle of the eighteenth century. Early work met with little success and in 1782 Lavoisier, an eminent French chemist, expressed the belief that alumina could not be reduced by carbon. It was almost a century later when the Cowles brothers developed a process for the production of aluminum alloys by reducing alumina coincident with the reduction of other metal oxides. In practice, the other metal oxide was usually copper. In 1907 it was first shown that alumina alone could be reduced by carbon at a temperature of 2200°C. The metal produced was volatilized and lost or recombined with the oxides of carbon formed in the reaction.&apos; For a number of years after the Cowles brothers abandoned production of Cu-A1 alloys because their product was not commercially competitive with the aluminum produced by the Hall process, there was little interest in thermal reduction processes. After World War I interest in such processes was renewed and a number of patents were issued on processes for the production of A1-Si alloys.&apos; , "he function of the silicon in these processes was the same as the function of the copper in the Cowles brothers process, namely, to prevent the reduced aluminum from recombining with the oxides of carbon and to promote absorption of the aluminum vapors set free at the high temperature required for the reduction reaction. The advantage of using silicon in place of copper for this function is that silicon has a higher boiling point (2600"C) than copper (2310"C) and its oxides, combined with aluminum oxides, occur in nature in almost unlimited quantities. No A1-Si alloys have been produced commercially in the United States, as far as is known. However, considerable experimental smelting of aluminum silicate materials has been done by the TVA at Wilson Dam, Ala.&apos; The most extensive development and commercialization of the electrothermal production of A1-Si alloys took place in Germany before and during World War II.V he furnaces used in the

Jan 1, 1956

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

ACTIVITY values for sulphur dissolved in liquid iron and slags as functions of composition and temperature are needed in applying thermodynamics to sulphur-control problems in iron- and &apos; steel-making. The purpose of this investigation was to determine the effect of carbon on the activity of sulphur in the metal phase. The method employed was the same as that used in an earlier investigation&apos; concerning the effect of silicon on sulphur activity in liquid iron. A study was made of the conditions of equilibrium in the reaction between hydrogen gas and sulphur dissolved in iron-carbon alloys. The chemical equation for this reaction can be written as follows: S (in liquid Fe-C alloy) + H2 (gas) = H2S (gas). It was found that the activity coefficient of sulphur in liquid iron increases as the carbon content increases. At 2.3 pct carbon and 1600 °C, the activity coefficient of sulphur is twice its value in carbon-free iron, and at carbon saturation it is more than six times as great. The effect of temperature on sulphur activity was found to be small. Previous work on the reaction between hydrogen gas and sulphur dissolved in liquid iron has been reported by several investigators2,³,4 but only recently have studies been made of the effect of alloying elements. Silicon1 is known to have a pronounced influence on the activity of sulphur in iron, its effect being similar to that shown by carbon as described in the present report. Kitchener, Bockris, and Liber-man5 recently have published a preliminary report of their work on the effect of carbon on sulphur activity in iron. Their experiments were made at 1570°C and carbon saturation in the melt. Under these conditions they found that the activity coefficient of sulphur was approximately doubled by the presence of carbon. This is a much smaller effect than that found in the present work. Experimental Method: The apparatus and procedure were essentially the same as those used in the earlier investigation of the effect of silicon on sulphur activity.&apos; Briefly, the method was as follows: A molten iron-carbon alloy was brought to equilibrium at constant temperature with a mixture of H2 and H2S of constant composition by bubbling the gas through the metal. Samples of the melt were

Jan 1, 1951

By J. T. Jones, H. V. Winchell

In the history of mining in this country there has been nothing exactly similar to the Mesabi iron-range in Minnesota, and the conditions there prevalent. Soft-ore mines are found in many parts of the country. In some the deposits are vertical, and are worked in open pits, or have been so worked, until it was found cheaper to go under ground. In other localities, the ore is scattered through clay beds in the form of hard lumps. These clay beds are sometimes excavated in open pits, and the ore separated by washing. On the Mesabi, the ore itself occurs in strata, and these strata appear quite flat to one standing upon the ground. The ore is soft in the main, and does not require much sorting to free it from foreign or deleterious substances. It is usually covered by the glacial drift-mantle, but occasionally passes beneath a capping of jasperoid rock called " taconite." The ore is twice or three times the thickness of the layer of drift lying upon it. This drift consists of clay, sand, and gravel, with occasional beds of large boulders. There is great difference of opinion among competent miners as to the cheapest methods of mining this ore. It is admitted that local conditions will govern largely ; but there is such a similarity among many of the mines that it seems possible to arrive at some general conclusions on the subject. A typical example of a Mesabi mine is found in the Biwabik. It is one of the largest, and is the most advanced in development. Not a single ton of ore has yet been shipped from this mine, but the expense of the explorations upon which the following description is based has exceeded $60,000. It is seldom that such accurate and complete exploration of a deposit of this magnitude has been possible in the space of time which has elapsed since the discovery of this ore-body. It lies in a new. region, and was remote from railroads until last August, yet, not only the width and length but the depth and quality of the ore-deposit have been learned, and the probable expense of&apos; mining its 20,000,000 tons of ore has been closely figured. After careful consideration, the method of stripping and

Jan 1, 1893

By Ray W. Arms

The combination wet and dry coal-cleaning process is not an attempt at a compromise between the wets and the drys nor is its merit confined entirely to the limitation of moisture in the smaller sizes. It is more correctly, and more broadly, an application of the sized-coal cleaning principle adapting itself in an ideal fashion to present day multiple-size preparation practice. The purpose of this paper, therefore, is to call attention to the broader significance of the term "combination wet and dry process" and to mention some of the factors that govern its application. In the narrow sense, when considered apart from the sized-coal cleaning principle, the combination process finds its justification chiefly in the ability to limit the moisture in cleaned coal. Larger sizes of coal offer less superficial area compared with their bulk for the attraction of moisture films. They drain more readily in bins or railroad cars, having more interstitial space for the free flow of water. Therefore, they neither attract nor hold objectionable moisture percentages. In fact, there is so keen a demand for certain washed sizes containing some moisture that hygroscopic salts such as calcium chloride are applied to attract and retain it. When coal deliveries are made on a guaranteed moisture percentage the coarser sizes may be washed and mixed back with the fines without adding greatly to the original moisture but the fines must be dry cleaned or dried to control moisture. Thus in all respects moisture in the coarser sizes is less objectionable than in the fines. The implication of this statement, that moisture is always more or less objectionable, is true. It is safe to say that if dry-cleaning apparatus could be perfected to a point at which its technical results, cost and other aspects would be equal to wet washing, water would no longer be used. As it is, we find that good technical results are more difficult to obtain by dry cleaning than by water. Obviously the use of air tables for coarse coal is not ideal, for it involves the attempt to stratify material in a thin bed on a table surface when the load is only one particle deep. Furthermore, the various air cleaning tables on large sizes require a large volume of air for separation, more power to operate, more dust-collecting apparatus and involve more coal breakage.

Jan 1, 1931

By Jerome Alexander

It is an outstanding fact of Nature that many of the practical properties of substances are dependent, not on their ultimate chemical composition, but on the kind and degree of aggregation of their constituent particles. Thus, a granite boulder is unmoved by wind or water, but if reduced to a fine dust it will be blown about by the wind and washed away by the rain. Carbon in one crystalline state of aggregation (diamond) is the hardest known substance, whereas in another crystalline state (graphite) it is so soft that it is used as a lubricant. Laying too much stress on the mere chemical analysis of substances is apt to obscure the fact that the nature of the aggregation of their particles is always a factor of importance, and sometimes the most important factor. Colloid chemistry deals with matter in a very fine state of subdivision; its sphere begins with particles just a little smaller than a wave length of light and extends down until they blend into molecular dimensions. With particles of this size, such phenomena as surface tension and adsorption, which depend on the development of free surface, become enormously magnified. Thus a cube of 1 cm. edge has a surface of only 6 sq. cm.; but if it is reduced to colloidal dimensions by being cut up into cubes each having an edge of 0.01 µ (0.00003 mm.), it will yield one million, million, million (1,000,000,000,000,000,O~) such cubes, having a combined area of 600 sq. m., or 21,274 sq. ft. The tiny force with which a drop of rain clings to the window pane becomes a factor to be reckoned with, if the surface involved is increased millions of times. From the colloid-chemical viewpoint, metals and alloys may be regarded as jellies or sponge-like structures,. the viscosity or stiffness of which at ordinary temperatures is exceedingly great; and like all jellies their properties are dependent on the composition and degree of dispersion of their constituent phases. These, in turn, depend on chemical composition, mutual solubility, speed of chilling, subsequent mechanical and heat treatment, etc. In fact, in preparing metals and alloys for practical use, we remove undesirable constituents (as in the conversion of pig iron into steel), add desirable constituents (as in

Jan 1, 1919

By John J. Porter

The requirements of the standard specifications under which Portland cement is sold have materially increased within the past 10 years, but practically all companies are now furnishing cement better than these requirements; in some cases exceeding them by nearly 100 per cent. From a sales standpoint, it is desirable to have a product that is uniform to a high degree and free from occasional quality troubles. A failure in quality, even if it affects only a few hundred barrels out of a yearly output of a million or more, is apt to be talked about in the trade and to affect the salability of the entire output. For these reasons, there has recently been great activity along the lines of quality control and improvement; and some of the most interesting problems of the industry are in this field. From the manufacturing standpoint, the quality of cement is chiefly a matter of uniform and proper chemical composition of the raw mix fed to the kilns plus proper burning in the kilns; the fineness to which the cement is ground, the proportions of gypsum, the method of seasoning, and the like are contributory factors. Uniform chemical composition of the raw mix has been one of the most difficult problems to solve. Most plants will use from 1000 to 3000 tons of rock per day and in but few cases is this material as it lies in the quarry even approximately uniform in composition. The problem, then, is to quarry and mix this raw material in such a manner that every handful passing through the kilns will have practically the same analysis as every other handful. To accomplish this purpose there are two methods of preparation: the wet and the dry. In each process, a stone storage is the first requisite of a successful plant. This storage place may handle the stone before or after crushing; its capacity may vary from two to three days&apos; up to several months&apos; supply, but it should be so designed that it can be filled as desired by the chemist and drawn at such points as will give a mixture of the various kinds of stone coming from the quarry and a reasonably uniform material going to the mill. The size of the storage place and the method of handling should be varied according to the nature of the material.

Jan 1, 1925

By C. F. Austin

lined-cavity shaped charge is an explosive mass with a cavity at one end and the detonator at the opposite end. The cavity is lined with a dense material, such as metal, glass, or a ceramic. Such an explosive device can be a useful drilling tool. Lined-cavity shaped charges are constructed to do just one thing — create a high-velocity jet of liner particles that can bore a hole in a target. The liner must be smooth and symmetrical, and high-velocity, high-brisance explosive must be used rather than ordinary commercial dynamites. Since the depth of target penetration is related to jet length, a standoff distance should be provided to hold the charge a short distance from the target. This allows the jet to lengthen prior to target impact. The best results are obtained when the jet is perpendicular to the target surface. Charges can be positioned for firing by taping them to a stake or simply laying them on a flat surface at the proper distance and angle with respect to the target. EFFECTS ON THE TARGET When a jet strikes a rock target, the jet and target particles at the jet-target interface move outward radially with respect to the jet axis to create a tremendous compressive load on the target material immediately below the target surface. The result is a shallow crater formed by spalling at the point of target entry. After cratering ceases, the steadily deepening hole continues to form as a result of the jet&apos;s imparting radial motion to the target particles at the jet-target interface. These radially moving particles collide with one another and with the hole walls, the net motion of the spent jet particles and target particles being back out of the hole in an axial direction (the backblast). The backblast keeps the penetration free of debris during penetration, al- though loose surface rock often falls into the hole after penetration ceases. The sudden stress relief after penetration ceases sometimes results in minor hole-wall rebound, which can partially fill the hole. The hole bottom will taper as the jet velocity decreases, until the jet velocity is too low to maintain the backblast. At this point the remaining jet and the following slug material are simply packed into the hole bottom. HAZARDS INHERENT IN USE Air blast from the highly brisant explosives used in shaped charges can damage nearby structures

Jan 1, 1961

By Robert Pike

THE first authentic description of an iron bath for the deposition of iron is probably that of Bottger in 1846, who used a bath containing ferrous sulfate and ammonium chloride. In 1861, Kramer deposited iron from ferrous chloride solution. Electrolytic iron was produced in 1.869 by Bietz, who used it for making some magnetic tests. In the same year, Klein is said to have worked out his process. Jacobi1 in 1869 described the results obtained in electroplating with iron on copper for making dies and plates for bank notes, by Klein&apos;s process. A letter from Klein to Jacobi describes the bath more fully. It consisted of FeSO4 + (NH4)2S04. Lenz2 described ?some properties of electrolytically precipitated iron. He used Klein&apos;s bath, FeSO4 + MgSO4 + MgCO3, to neutralize and obtained fine-grained and hard iron. His conclusions were as follows: 1. Electrolytic iron and copper contain gases, notably hydrogen. 2. The volume of gas absorbed by iron varies within wide limits, but it is easy for iron to take up very considerable quantities of gas. 3. The absorption of gas is principally in the first formed layers of iron. 4. When iron is heated, gas begins to come off below 100°, principally hydrogen. 5. Heated to redness, reduced iron oxidizes in water, in part at least at the expense of the oxygen of the water, decomposing it and setting free hydrogen, which is partly or wholly absorbed. Siemens,3 in 1889, was the first to propose a general process embodying a step for leaching a sulfide mineral with ferric chloride or sulfate and a step for regenerating the leach and depositing iron on a cathode in a diaphragm cell. So far as is known, Siemens did not carry out his patent

Jan 1, 1930

By W. S. Keyes

The State of Nevada, known par excellence as " the Silver State," occupies the major portion of the wide plateau, or so-called Great Basin, lying between the Sierra Nevada range on the west and the Wahsatch range of the Rocky Mountains on the east. It extends from the 114th degree to the 120th degree of longitude, west of Greenwich. It is limited, on the north, by the 42d degree of latitude, and on the extreme south by the 35th degree of latitude. Its general shape is that of an irregular parallelogram, from which the lower or southwestern portion has been cut off by a diagonal southeasterly line; the missing portion forms a part of the State of California on the west. The Great Basin is made up of a succession of low hills, or minor mountain ranges, running very nearly north and south, with long valleys between them. All of these mountains are more or less metalliferous. On the westcrn rim, marking the eastern flank or foothills of the Sierra, we find granites, porphyries, and propylites. Here we note the great Comstock lode, with its free-milling gold and silver ores, and still further south the once prominent and the now reviving gold and silver-bearing districts of Esmeralda County, Nevada, and of Morro County, California. Next, at some distance to the east, we find the mining districts at and near Unionville, in Humboldt County. Still further to the east we find the Battle Mountain copper-silver district, north from the railroad, and southerly therefrom the Austin or Reese Ever, Belmont, and other districts. Still further east and north of the railroad, we find the Tuscarora, a new district of very

Jan 1, 1879

The writing that is effective is woven with a he texture into an agreeable pattern; it is free from knots, loose threads, and stray fluff. The instrument that weaves this literary fabric, whether it produce a homely sock or a lordly tapestry, a simple story or a learned treatise, is a disciplined intelligence, as sure as a steel needle, as precise as a swift loom. The simile breaks down at this point, for the product of the pen is instinct with the human spirit and therefore transcends in beauty anything made by a mere machine. If words are to be woven into eloquent meaning, they must be well knit. Upon the relation of words to each other and of groups of words to other groups, known as phrases, clauses, and sentences, depends the success of writing as a means of transmitting thought from man to man. To be understood beyond question, you should know not only what your words denote&apos; but how to build your sentences; you must not only choose your words aright but construct your sentences properly. A sentence is a combination of words that makes complete sense; it says something about something. A clause is a subordinate sentence or a sentence within a sentence. A phrase is a group of words without a predicate; it makes sense, but not complete sense. For example: I shall wait for a few minutes before I go home. The whole statement is a sentence; "I shall wait" and "before I go home" are clauses; "for a few minutes" is an adverbial phrase. The orderly arranging of words and of combinations of words is called &apos;syntax&apos;; and from the original Greek form, [s?ta???] (suntaxis), is derived the Greek name for an editor,

Jan 1, 1931

By Lawrie DC

Finely ground beryl was decomposed by mixing with ground limestone and soda ash andheating at 900¦C for,4-6, hours.The sintered material was then crushed and leached by boiling under reflux with 5N sulphuric acid for up to 4 hours. The liquor containing Be, ; Al, . Fe and, other elements as sulphates, was separated from the residue which consisted mainly of silica and gypsum, either&apos; by filtration or by decantation washing.The clarified leach liquor.was first treated to remove Fed}: , by contacting with a primary amine-kerosene solution in2 counter-current stages. The iron free liquor wa,s then passed to a 4-stage counter-current extraction unit where it was con-tacted with 0.5M di-(2 ethyl hexyl), phosphoric acid (EHPA) in kerosene. The&apos;operating conditions were such that at least 99 p&apos;br cent of the Be and only 7&apos; per&apos; cent of the Al- was, extracted The ,B6`= and. Al were ;stripped from the organic phase by sod-ium hydroxide solution of suitable concentration to form soluble "beryllate" and "aluminate" respectively. Most of the Be was subsequently precipTitated a&apos;s Bo(OH)2 by-hoating the alkaline solution to 90C, the Al remaining in solution. After filtra-tion and washing, the Bo(OH)2 could be ignited directly to BeO at about 1000 C or used as a feed to further purification stages aimed at producing "nuclear grade" BeO.A small coaAter-current extraction unit was operated con-tinuously using liquor derived from the sintering and leaching stages. Data obtained in batch laboratory tests were confirmed. A product obtained by ignition of the washed "beryllate" precip-itate contained more than&apos;99 per cent BeO.

Jan 1, 1963

By D. J. Jr. McAdam

PART I.-OUTLINE OF INVESTIGATION, DESCRIPTION OF METHODS AND MATERIAL Previous Investigation of the Influence of Stress on Corrosion IN 1917 Haigh1 presented evidence that under simultaneous corrosion and cyclic stress metals may fail at lower stresses than if the corrosion is prior to the cyclic stress. In 1926 the author, while investigating the cooling effect of water on the fatigue resistance of metals, found that under these conditions steel specimens fail at stresses far below the endurance limit.2 (By "endurance limit" is here meant the fatigue limit obtained with specimens as free as possible from stress concentration and corrosive influences.) This led to an investigation (at the Naval Engineering Experiment Station, Annapolis, Md.) of the influence of cyclic stress on corrosion. This investigation maybe divided into three parts. The first part was a general survey of the conditions necessary to cause complete failure under corrosion and cyclic stress of relatively high frequency. The entire process by which metals fail under these conditions was-called "corrosion-fatigue." "Corrosion-fatigue limits" for a large number of metals were determined and the relationships of these limits to chemical composition, heat treatment and physical properties were established. The conclusion was reached that corrosion-fatigue is due to the accelerating influence of cyclic stress on corrosion. Results of this part of the investigation were presented in five papers.2-6 The second part of the investigation was a preliminary study of the influence of cyclic stress on corrosion. Each experiment was conducted in two stages. The first was a corrosion stage in which the specimen was corroded under cyclic stress; the second was a fatigue stage, in which the previously corroded specimen was tested (without further corrosion) to determine its fatigue limit. The difference between this fatigue limit and the endurance limit was used as a criterion of the "damage" due to

Jan 1, 1931

By Leo J. Miller

Sulphur deposits occur within the upper Salado and Rustler gypsum beds. The formation of a sulphur ore deposit requires large quantities of oil and /or gas, which must find a permeable pathway into the gypsum beds. The Permian beds weathered for 90 million years in an arid environment prior to the advent of a more humid climate at the beginning of the Cretaceous Period. The first Cretaceous rivers enlarged the sinkholes and caverns of the Karstified Permian terrain and deposited coarse conglomerates and sands into the subsurface gypsum beds. The resulting network of caverns and sinkholes, filled with permeable sediments, permitted the free flow of hydrocarbons through gypsum. All sinkholes and caverns infilled with Cretaceous sediments that have penetrated beds of gypsum are associated with sulphur deposits. The Castile gypsum lies directly upon the oil bearing Bell Canyon formation. Sinkholes and caverns filled with Cretaceous sediments occur in the lower Castile. Biogenic calcite and sulphur are adjacent to these sediments. However, faults assume the major role in generating the initial permeability, allowing hydrocarbons to penetrate the lower Castile gypsum. The largest faults are associated with biogenic calcite and sulphur for a distance of 250 meters up from the bottom of the Castile gypsum. It is apparent that two dynamic geological processes are generating permeability within the gypsum beds: (1) the Cretaceous sands decending with difficulty into gypsum and (2) the faults creating permeability in the lower Castile but losing energy through soft bed deformation in the overlying gypsum. Both of these sulphur ore controls are mappable, but another large sulphur deposit of the magnitude of the Culberson Sulphur Mine has yet to be discovered. It appears that massive sulphur deposits are associated with the largest scale examples of each system, that is (1) high densities of deep sinkholes and separately

Jan 1, 1992

By W. S. Keyes

(Read at the Amenia Meeting, October, 1877.) EASTERN NEVADA. THE State of Nevada, known par excellence as "the Silver State," occupies the major portion of the wide plateau, or so-called Great Basin, lying between the Sierra Nevada range on the west and the Wahsatch range of the Rocky Mountains on the east. It extends from the 114th degree to the 120th degree of longitude, west of Greenwich. It is limited, on the north, by the 42d degree of latitude, and on the extreme south by the 35th degree of latitude. Its general shape is that of an irregular parallelogram, from which the lower or southwestern portion has been cut off by a diagonal southeasterly line; the missing portion forms a part of the State of California on the west. The Great Basin is made up of a succession of low hills, or minor mountain ranges, running very nearly north and south, with long valleys between them. All of these mountains are more or less metalliferous. On the western rim, marking the eastern flank or foothills of the Sierra, we find granites, porphyries, and propylites. Here we note the great Comstock lode, with its free-milling gold and silver ores, and still further south the once prominent and the now reviving gold and silver-bearing districts of Esmeralda County, Nevada, and of Morro County, California. Next, at some distance to the east, we find the mining districts at and near Unionville, in Humboldt County. Still further to the east we find the Battle Mountain copper-silver district, north from the railroad, and southerly therefrom the Austin or Reese River, Belmont, and other districts. Still further east and north of the railroad, we find the Tuscarora, a new district of very

Jan 1, 1878

By Robert B. Parsons

"This article is based on a paper presented by Jim Scott at the 1988 annual convention of the Prospectors and Developers Association of Canada. The paper suggests a number of factors that might be taken into account in negotiating royalty terms.IntroductionRoyal ties are a part of mining life in Canada. They are used by many kinds of individuals in many kind s of situations. Prospectors commonly take royalty interests back when they transfer claims to development companies. Mining companies disposing of undeveloped (or sometimes even developed) properties are often paid at least in part by royalties. Royalties are even used by institutional investors with no other connection with the resource industry.Such different royalty holders have different investment goals, different cash flow requirements, and different risk / return preferences. These differences have given rise to a number of different royalty type s. These types range from the simplest cents-per-ton royalty (where the operator pays a royalty at a fixed rate per ton milled) to net smelter return or ""NSR"" royalties (where the royalty is based on a percentage of the operator&apos;s NSR) all the way to net profit interest or ""NPI"" royalties (where the royalty is based on the operator&apos;s bottom-line net profit),The fundamental difference between the many royalty types is in the risk/ return relationship. The cents-per-ton royalty, for example, is relatively risk-free. Of the many economic factors which affect a mine, the only one which will affect the royalty holder is the amount of ore physically milled. On the other hand, the potential for significant gains under a cents-per-ton royalty is also very limited. The royalty holder will not share in any increases in the market price of the end product or any cost reductions achieved by the producer."

Jan 1, 1988

By J. Chipman, T. P. Floridis

The equilibrium of gaseous H2O-H2, mixtures with liquid iron is used to establish the activity coefficient of dissolved oxygen as log f o = — 0.20 [%O]. Discrepancies in earlier work are explained or eliminated. Additions of cobalt, molybdenum, tungsten, and platinum increase the activity coefficient of oxygen whereas copper and gold decrease it. THE importance of dissolved oxygen as a refining agent in liquid steel has led to a number of studies of its thermodynamic properties. It is the purpose of this paper to examine the effects of a number of alloying elements on the activity of oxygen in the steel bath. As a preliminary to the study of the effects of alloying elements, it seemed desirable to examine certain minor discrepancies in the published data on the properties of oxygen in simple iron-oxygen solutions. The activity and free energy of oxygen in liquid iron were studied by chipman1 in 1933 by means of the reaction h2(g)+-o = H2O (g);K; = PH2O/PH2[% O] [1] The data were in fairly good agreement with calculations from results on the similar reaction CO (g) + O- = CO2 (g); K2 =P CO2/P CO [% O] [2] which had been obtained by Vacher and Hamilton2 as an incidental part of their study of the reaction of carbon with oxygen dissolved in the melt. It was found that the equilibrium ratio k1 was not a true constant but varied with the oxygen concentration in the manner shown in Fig. 1, which is copied from the original paper. This early observation has been refuted in subsequent work but is confirmed in the present paper, and an explanation of the discrepancy can now be presented. In Fig. 1, the two points on the extreme right were disregarded in drawing the

Jan 1, 1959

By R. A. Sharma, F. D. Richardson

Manganese oxide acitivities and sulfide capacities have been measured at 1650°C in mixtures of MnO + A1203 and MnO + SiO2 - Al2O3. Sulfide capacities have also been measured at 165O0C for melts of MnO + SiO2, MgO + SiO2, MgO + SiO2 + Al2O3, MgO + MnO + SiO2, and SiO2 + Al2O3 and for crystalline CaO. The activity coefficients of the sulfides of manganese and magnesium have been derived where possible. It looks as though the activity coefficients of sulfides are greatest at compositions where the free energies of formation of the silicate mixtures have their maximum negative values. The amphoteric nature of alumina is reflected in the results for the binaries and ternaries in which it is present with silica. The limiting solubility of CaS in CaO at 1650°C is 6.3 x 10-4 mole fraction. THE activities of manganese oxide have been measured in a variety of silicate and aluminate melts by use of the equilibrium (MnO)slag = [Mn]pt .½O2 [l] and the experimental techniques described previously.&apos; Sulfide capacities (CS = wt pct S (PO2/PS2)½) have also been determined in a series of melts, by use of an established method2 which exploits the equilibrium (O°) + ½S2 = (S") . ½O2 [2] If CS and the activity of a metal oxide are known in a melt, the activity coefficient of the metal sulfide can be calculated by use of the equilibrium constant K, for the pure phase reaction MO i ½S2 = MS + ½O2 [3] The activity coefficient of the sulfide is then given by the equation

Jan 1, 1965

By Robert B. Parsons

"This article is based on a paper presented by Jim Scott at the 1988 annual convention of the Prospectors and Developers Association of Canada. The paper suggests a number of factors that might be taken into account in negotiating royalty terms.IntroductionRoyal ties are a part of mining life in Canada. They are used by many kinds of individuals in many kind s of situations. Prospectors commonly take royalty interests back when they transfer claims to development companies. Mining companies disposing of undeveloped (or sometimes even developed) properties are often paid at least in part by royalties. Royalties are even used by institutional investors with no other connection with the resource industry.Such different royalty holders have different investment goals, different cash flow requirements, and different risk / return preferences. These differences have given rise to a number of different royalty types. These types range from the simplest cents-per-ton royalty (where the operator pays a royalty at a fixed rate per ton milled) to net smelter return or ""NSR"" royalties (where the royalty is based on a percentage of the operator&apos;s NSR) all the way to net profit interest or ""NPI"" royalties (where the royalty is based on the operator&apos;s bottom-line net profit),The fundamental difference between the many royalty types is in the risk / return relationship. The cents-per-ton royalty, for example, is relatively risk-free. Of the many economic factors which affect a mine, the only one which will affect the royalty holder is the amount of ore physically milled. On the other hand, the potential for significant gains under a cents-per-ton royalty is also very limited. The royalty holder will not share in any increases in the market price of the end product or any cost reductions achieved by the producer."

Jan 1, 1989

In dealing with the pulverization and treatment of auriferous ores, it may be stated that there is not one system of treatment applicable to all classes. In the southern portion of New Zealand the ores generally contain free gold, with scarcely any impurity that is, it is found in an almost pure state, without any alloy, and its dissemination amongst the matrix is generally in tolerably coarse particles. The only difficulties the mill man has to contend with, are the economical concentration of pyrites, which in some of the lodes are rich in gold, and the extraction of the gold the pyrites contain. In some of the lodes there is what may be termed float gold, that is, the particles of the precious metal are so finely divided that it passes over the quicksilver tables, and, unless there are other appliances for saving it, this class of gold is entirely lost.Indeed it is only within the last five years that any attention has been given, in the southern portion of the colony, to saving the fine gold that has passed the amalgamating tables. In the North Island the ores are very complex there are scarcely two mines, although they may be adjoining each other, where the bullion is of the same character. On every field the gold is alloyed with silver&apos;, and in combination with other metals and mineral substances, such as copper, zinc, antimony, galenfl, iron, sulphur, arsenic, etc., and, in some instaaces, cinnabar, as in the case of the Champion lode at Tui Creek, Te Aroha. Ores of this class are extremly difficult to treat satisfactorily.

Jan 1, 1903