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By W. M. Johns

The geological mapping of Lincoln and Flathead Counties was a five-year project undertaken by the Montana Bureau of Mines and Geology. This paper, written by the Project Geologist of the survey, is primarily concerned with the stratigraphy of the Belt rocks encountered in mapping. Lincoln and Flathead Counties of northwestern Montana are underlain by sedimentary rocks of the Belt Series of Precambrian age. In only a very small part of the area, near Libby and Troy, have economic mineral deposits been worked with any success. Most of the area has been inadequately mapped as to geology. The region is crossed by the Great Northern Railway and served by the Pacific Power and Light Co.; officials of these two companies believed that with better geologic maps, prospecting might be stimulated and lead to the discovery of mineral resources that would contribute to new economic development within the area. A cooperative mapping agreement was proposed jointly by the two companies to the Montana Bureau of Mines and Geology in May 1958, and thus was born the Kootenai-Flathead five-year project. The dual objectives of this project are: 1) the possible location of mineral deposits of economic value, and 2) the ''stimulation of prospecting exploration" by others. This was to be achieved by geologic mapping of some 6800 sq miles and by establishing a field office in Kalispell where prospectors could come to have their rocks and minerals identified and receive geological advice on their problems. This writer has finished four field seasons as Project Geologist and thus became familiar with the Belt section in the Libby, Yaak River, Ural, Thompson Lakes, Pleasant Valley, and Stryker quadrangles (see Fig. 1). Progress on the project is given in annual reports issued by the Bureau.* This *Montana Bureau of Mines and Geology, Bulletins 12 (1959), 17 (1960), and 23 (1961). paper is concerned essentially with the stratigraphy of the Belt rocks so far encountered in mapping. PREVIOUS WORK IN THE AREA Willis28 made the first study of the stratigraphy and structure in the Lewis and Livingston Ranges of Glacier Park just east of the project area. In 1904, Daly made a study of the Belt rocks of the 49th parallel, using the names from bottom up, Creston, Kitchener, Moyie, and Gateway, for rocks ranging in age from that of Prichard to that of basal Missoula group. Walcott26 studied the Belt rocks exposed in the Mission Range (see Fig. 1) and other areas to the south of the area under discussion. Calkins and McDonald made a reconnaissance of northern Idaho and northwestern Montana in 1905. Calkins was the first to use Walcott's term 'Ravalli' as a group name for the strata equivalent to the Burke, Revett, and St. Regis formations (see Table I). Clapp worked on the Belt of western Montana (including Lincoln and Flathead Counties) throughout his lifetime. The Fentons9 studied the Belt of Glacier Park and

Jan 1, 1962

By Schneider, W. G.

IT is not my purpose to burden you with many statistics. The charts herewith should be considered merely as indicating the trend. I believe' that is what is really of interest to us. It is difficult, if not impossible to forecast with any assurance future developments, because of possible new mines, competitive materials, curtailment' or increase in the use of the metal in certain markets, and many other factors that have a vital bearing on any industry. Fig. 1 shows United States smeltet output of copper, starting with 1845. It is estimated that in 1928 the smelter output of copper will be about 1,010,000 tons. Between 1895 and 1905 it increased about 200,000 tons, and between 1905 and 1915 about 240,000 tons. Between 1915 and 1925 the increase was about 140,000 tons. This is an average increase over 30 years of about 190,00Q tons per ten-year period. At the present time the indications are that this demand for increased production will continue. As to whether or not we have the supplies or facilities to maintain this increase or a greater one, remains to be seen. Provided it is possible for United States smelters to increase their production, they should be producing at the rate of about 1,210,000 tons or more per year by 1935.

Jan 1, 1928

By D. W. Smith, C. H. Mathewson

In a series of papers published recently,' R. F. Mehl and associates have studied the characteristics of form and orientation of many segregate structures and have found diversified conditions which can be explained only by postulating some specific kind of cooperative mechanism permitting the matrix lattice in some favorable region to transform into the segregate lattice in an adaptable region presenting a geometrically similar arrangement of atoms. We have collected the published data on crystallographic relationships of this sort, chiefly derived from Mehl's work, in Table 1. It is evident at once that the crystal structure of the matrix does not uniquely determine the location of the plate structures or other forms assumed by the segregate. Thus, the first seven items in the table represent precipitation of platelike forms from a matrix of face-centered cubic structure, but these plates are found stratified along planes of form {1111, {loo), {110) or another unidentified form, depending upon specific conditions involving the nature and concentration of the segregating substance. Again, in a matrix of body-centered cubic structure, plates, needles or stars have been found and the favored inner surface of segregation may be a plane of form (110), (112), {210), or indeed a surface without crystallographic indices defining a bundle of close-packed lattice lines (strings of atoms) taken more or less at random. Such a surface might be formed ideally by revolving one of these parallel strings of atoms around another as an axis. Hanemann and Schroder2 recently discussed these questions, principally with relation to original conceptions concerning the process of

Jan 1, 1932

By E. H. Sellards

ON Oct. 9, 1929, a sink formed in the Sour Lake salt dome oil field in Texas, and on Oct. 12 a second smaller sink formed at the north margin of the first. The purpose of this paper is to give such observations as it has been possible to make on the earth movement incident to this subsidence. Sour Lake salt dome is typical of the salt domes of the Gulf Coastal Plain of Texas. Structurally the dome is a plug of salt which rises to within 900 ft. or less of the surface. Above the salt is a cap rock consisting of anhydrite with more or less calcium carbonate. The salt plug, as contoured on the cap rock, is circular in outline with, however, some appreciable irregularities. Overlying the cap rock are relatively uncompacted sediments consisting of sand, clay and gumbo.. At the crest of the dome these deposits are no more than 700 or 800 ft. thick. However, the sides of the dome are steep, and the sediments thicken rapidly away from the crest. The sink formed about 1500 ft. northeast of the crest of the dome where the sediments overlying the cap rock are from 1000 to 1200 ft. thick. The cavity permitting the subsidence was quite certainly either in the cap rock or in the salt below the cap rock, so that the sink was formed by the caving of as much as 1000 or 1200 ft. of earth.

Jan 1, 1930

By C. H. Keplinger

WARTIME factors have strengthened the production engineering consciousness of the petroleum industry. The basic principles of sound oil-production technology have been accepted as the standard by the industry and the governmental co-ordinating agencies. Every effort is being made to furnish larger quantities of petroleum with a minimum expenditure of materials and under strict conservation practices. The sphere of influence of production engineering extends from fundamental reservoir control of withdrawal rates and reservoir pressures to bolstering production from stripper wells. Serious transportation difficulties in moving oil to the East Coast have stimulated secondary recovery operations in the Appalachian and East Central oil-producing states. Diminishing discovery of new oil reserves by exploration activities increases the importance of promoting efficient oil-producing methods and practices throughout all productive areas in the United Nations.

Jan 1, 1943

BENEFICIATION AND CONCEN'TRATION; FROTH FLOTATION U.S. 4,069,144 - In the froth flotation beneficiation of phosphate rock using at least an acid flotation step and an amine flotation step, the crude ore is dried either during transport or storage or by air circulation immediately prior to classification, and the dried ore mixed with water and classified prior to flotation The preliminary drying substantially eliminates the usual problems with clay slimes G. C. Johnson and A. E. Schweizer, assigned to Mobil Oil Corp. Jan 17. 1978. 4 pp (209- 11) . Filed 1 1-19-75 (633,535).

Jan 1, 1979

By W. W. Little

At the United Verde mine the 9-2D stope on the 4050 ft level is located within the north sulphide mass lying some 800 ft north of the main sulphide ore body. In 1948 it was estimated that this block contained 85,000 tons of ore at 4% copper and 9.2% zinc. The north ore body is a lenticular replacement deposit in the black schist, extending from about 100 ft above the 3750 level to a distance below the 4500 level yet to be determined. Although the mineralized zone approaches 1000 ft in length, only 300 ft is of economic importance. In width it varies from a maximum of 60 ft to about 3 ft at the north end, and is characterized by pinching and swelling in the ore zone. One of these larger swells is being mined as the 9-2D stope. Mining costs at greater depth, together with the expected grade of ore after dilution, necessitated a low cost mining method to permit profitable stoping operations. Based on the results obtained in a number of Canadian mines, it was decided to develop the ore body for stoping by the Aldermac or bench method of diamond drill blastholes; however, this plan was subsequently changed and the radial or ring method adopted. Such a method seemed to offer the advantage of large tonnages at low cost, and obviate the necessity of waste fill. This latter point was of particular importance, since the present waste system does not extend below the 3000 level.

Jan 4, 1950

By J. Jolly

THIS short note on the probable character of the organic sulfur compounds in coal can do no more than indicate lines of research. We have no new experimental work to describe, nothing comparable in value with the careful studies of American coals by Powell and Parr1 and Yancey and Frazer.2 A study of the manner in which sulfur compounds exist in British coals (and their behavior on heat treatment) is rendered increasingly necessary by the fact that the British reserves of good coking coals of reasonably low sulfur content are fast being depleted. We believe that it is essentially by a study of the modes of formation, occurrence, and decomposition of the various types of inorganic and organic sulfur compounds in coal that it will be possible, with hope of success, to attack the problem of purifying coals, otherwise eminently suitable for coking, from these objectionable ingredients. Sulfur, so far as is at present known, does not normally occur in the free state in the coal conglomerate, but is chiefly distributed, irregularly, in three forms: 1. As primary constituents of the coal conglomerate, organic in nature and probably associated with those molecular complexes that have resulted from the degradation of the proteins of the plant tissues responsible for the formation of the coal mass. These constituents can be classed as "organic sulfur." 2. As metallic sulfides, e.g., iron pyrites. 3. As metallic sulfates, e.g., calcium sulfate and ferrous sulfate. (The occurrence of these compounds varies with the occurrence and degree of degradation of class 2.)

Jan 3, 1925

By Oliver Bowles

THE inorganic non-metallic minerals, that is, the non-metallics exclusive of coal, oil, gas and related minerals, constitute the basic raw materials for a number of essential industries. It is estimated that the value of the raw materials in this group produced in 1919, together with certain of the primary products ordinarily manufactured at the mine, exceeded $800,000,000. They are employed chiefly in the building, agricultural, and chemical industries. It has been estimated, by the Bureau of Mines, that approximately 00,000,000 worth of non-metallic minerals and their products were used in the building trades during 1918; with the great increase in building since that date and the increased cost of materials, the value of non-metals used in such industries during 1920 probably exceeded $500,000,000. The chief of these materials are cement, building stone, crushed stone, sand and gravel, clay products, lime, gypsum, glass materials, slate, talc and soapstone. In many of the producing industries of this great group, the waste is so great that the expense of handling it is an important item in the production cost. The utilization of waste is receiving unusual attention in many of the non-metallic industries at present. The most obvious advantages of such utilization are: (1) Conservation of mineral resources, (2) the removal of waste heaps that in many places obstruct development, (3) manufacture of new and useful products, (4) reduced production costs through elimination of a large part of the item of waste-disposal expense. In many industries there is keen competition between producers of various products used for the same purpose, so that advantage will accrue to the manufacturer who is able to reduce his production costs.

Jan 1, 1921

By P. Pollard

A method has been developed for evaluating acid treatments in fractured limestone fields by breaking down pressure drawdown into three component parts: (I) pressure differcntial across "skin" near the borehole face, (2) pressure differential due to flow resistance in the coarse communicating fissures and (3) pressure differential between the fine voids and the coarse fissures. It is apparent that in most successful acid treatments the first term, skin resistance, has been reduced or eliminated. Further, it is often possible to estimate the volume of coarse fissures associated with the second term, coarse fissure flow resistance. In cases where this volume is comparable with practical acid volumes it seems likely that this resistance also may be attacked with a suitably retarded acid. INTROD UCTION Acid treatment has been successfully applied as a general practice in the limestone wells in the Mara/ Maracaibo districts of Venezuela for some 10 years. At the same time the need has been felt for a more precise method of: (1) evaluating the effect of an acid job and (2) selecting wells which should benefit from an acid treatment. The following method, based on an analysis of build-up curves for wells producing from fractured limestone, provides a means of forecasting the effect acid will have on a well and in many cases the probable order of production rate increase which may be expected. In certain cases it is also possible to calculate the fissure volume through which the acid has to be displaced for best results. Various approximations are introduced in the method, but within the limitations of these the analysis gives an indication of how a well, whether previously acidized or not, may be expected to respond to acid treatment. Suitable build-up curves cannot be obtained on "tight" wells which do not give sustained production and the method is not applicable to such wells. Figs. 1 through 7 illustrate various types of build-up curves obtained from limestone wells in Western Venezuela. Curves are included showing (1) both skin and coarse fissure resistance, (2) skin resistance only, (3 and 4) reduction of skin resistance by acidization, (5) fissure resistance only, (6) reduction of coarse fissure resistance by acidization, and (7) acidization failure. This theory has been successfully applied for over three years during which 22 acid treatments have been carried out specifically to reduce skin resistance and three treatments to reduce coarse fissure resistance. The method has been found to be a useful aid in the selection of wells for acidization.

By C. McDermid

At the request of Mr. C. McDermid, Secretary of the Institution of Mining and Metallurgy, Salisbury House, London, E. C., England, the following reports of standardization committees are here republished. Mr. McDermid invites members of-the American Institute of Mining Engineers to write him and express their opinion of the various proposals made by the committees. COPY OF THE REPORT OF THE WEIGHTS AND MEASURES STANDARDIZATION COMMITTEE OF THE INSTITUTION OF MINING AND METALLURGY, as adopted by the Central Standardization Committee; Dec. 20, 1906, and submitted to the Council, Jan. 16, 1907.

Mar 1, 1907

By William D. Klopp

A study was conducted of the tensile and creep properties of are-melted and electron-beam-melted tungsten over the temperature range 2250° to 4140°F. The tensile and creep strengths vary with pain size, the finer -grained materials being stronger. The activation energy for transient creep at 2250° to 3500°F is 95,000 cal per (g)(mole), while that for steady creep at 3300o to 4000°F is 141,000 cal per (g)(mole). At 2875o to 3300°F the apparent activation energy for steady creep decreased with decreasing temperature. It is suggested that cross slip is rate controlling during transient creep, while dislocation climb is rate controlling during steady creep above 3300° F. ALTHOUGH considerable data have been generated on the high-temperature tensile properties of powder-metallurgy tungsten,1 relative few data have been published on the properties of are-melted2 or electron-beam melted tungsten.3 Furthermore, the available data show a fairly large amount of scatter at high temperatures. The effects of structure and purity have not yet been defined, aside from observations that high-purity electron-beam (EB)-melted tungsten3 and single-crystal-plasma-flame tungsten4 are weaker than less pure powder-metallurgy tungsten. The creep behavior of powder-metallurgy tungsten has been studied, but no data are available on the creep behavior of tungsten consolidated by melting. Green5 found that powder-metallurgy tungsten exhibited linear creep at 4082° to 5072°F with an activation energy of 160,000 cal per (g) (mole). The similarity of this activation energy to that of 153,000 cal per (g)(mole) for volume self-diffusion6 suggests that recovery of strain hardening by dislocation climb is rate controlling in this temperature range. In studies at 4800°F, Sutherland and Klopp7 concluded that grain size significantly affected the creep behavior of commercial powder-metallurgy materials. This grain-size effect was suggested by sherby,8 although the opposite relation had been reported for aluminum.' The purpose of the present study was twofold: first, to provide baseline data on high-temperature tensile and creep properties of are-melted and EB-melted tungsten for concurrent tungsten alloy studies, and, second, to determine the phenomenolo-gical effects of structural and purity variables on the high - temperature mechanical properties of tungsten. EXPERIMENTAL The are-melted tungsten materials were prepared by melting sintered 1-1/4-in.-diam electrodes into 2-1/2-in.-diam by 5-in.-long ingots. The are-melting facility has been described previously.' Eight ingots were melted, machined, and hot-extruded at

Jan 1, 1965

By A. M. Gaudin

CHANGES in industrial practice, in plant design, and in research methods which are so clearly to be seen on every hand, have affected the mineral industry as well as others. In particular, ore dressing has passed through a revolution in practice brought about by the introduction of flotation and other quasi-chemical methods, until it has ceased to be solely the mechanical preparation of ores. In fact, the term "ore dressing" itself is obsolescent, and "mineral dressing" has been growing in popularity. This assures adequate recognition of the fact that mineral substances other than ores, e.g. coals, clays, and cement rock, are treated by the same general methods. As a result of these industrial changes it was felt that a complete rearrangement of the curriculum and laboratories at the Massachusetts Institute of Technology would be ad-vantageous. Such a rearrangement would allow instruction and research to proceed in wider accord with industrial evolution and the needs of our times.

Jan 1, 1942

By J. S. Aronofsky, H. J. Ramey

Potentiometric model studies of the five-spot water flood to determine the influence of mobility ratio upon injection or production histories are described. The results suggest a method for the correlation of data from field pilot tests for the estimation of an effective mobility ratio and its effect upon field water floods. The effect of the well spacing-to-well radius ratio upon production histories is presented. A method of accounting for this factor is suggested. The influence of injection (or production) rates and injection and production well pressures upon production histories is shown. The five-spot well pattern was investigated for water-to-oil mobility ratios of 0.1 to infinity. INTRODUCTION It has been well established that mobility ratio has an important effect upon flood patterns.1,2,3,4,5 It should be equally apparent that injection and production histories must also be influenced by mobility ratio. However, none of the articles referred to above mention the importance of being able to predict the effect of well pressures (or injection rates) during the entire time history of a waterflood operation. A complete description of production histories (the terms "injection" and "production" are synonymous for the steady-state model under consideration) would provide values for well pressures and interface positions at any time for a specified injection rate. conversely, if the waterflood problem is specified in terms of a constant injection well pressure, then it would be desirable to know the injection rate and interface positions at any time. This paper describes the results of potentiometric model studies which were used to analyze the influence of mobility ratio on injection or production histories. A method is presented for calculating production histories over a range of ratios of well spacing-to-well radius. The basic method described in this paper to evaluate production histories is to: (1) determine interface position as given in Ref. 1, and (2) measure electrical current and voltage drop for each interface position. It should be mentioned that the current state of knowledge on flood patterns as affected by mobility ratio shows that significant discrepancies exist between the results of various investigators2,3,4,5. It is beyond the scope of this paper to discuss the reasons for such discrepancies. However, the method of determining production histories presented in this paper could be applied to any of the swept-area patterns presented in the literature. All results given in this paper are based on a set of swept areas obtained by the potentiometric method. Potentiometric analyzer technique is adequately described in the literature, but the basic assumptions involved in work of this nature bear repetition. It is assumed that: 1. A distinct oil-water interface exists in the reservoir; only water is mobile in the region behind the interface (water zone) and only oil is mobile in the region ahead of the interface (oil zone). 2. There is a fixed mobility value, (k/µ) w associated

Jan 1, 1957

By F. William Bloecher, William B. Plank

CURRENTLY 12,892 students are enrolled in the mineral engineering schools of the United States and Canada, marking an all-time record high for these schools. It shows a remarkably rapid recovery from the effects of World War II. Enrollment in all the other engineering branches has also increased but not so rapidly as in the mineral engineering branch. Almost all the data in this report are from the eighth questionnaire study of the mineral engineering schools made, as formerly, under the auspices of the Mineral Industry Education Division of the AIME. Every school is represented in the data, for which the authors thank the deans and professors who supplied the information. For this reason, the data of all the studies are comparable, an achievement not always possible in endeavors of this kind. For comparison with the general engineering enrollment situation, data are included from the January 1947 issue of the Journal of Engineering Education.

Jan 1, 1947

By R. M. Douthwaite, G. Birkbeck

The effect of grain size and specimen dimensions on the occurrence and magnitude of a yield point drop in pure iron has been examined. The tests were done at room temperature. The results indicate that gain size is the critical factor determining whether a yield drop occurs. The specimen diameter:gain size ratio does not influence the magnitude of the yield drop for the range of gain size and specimen diameters investigated. HUTCHINSON,' petchY2 and worthington3 have investigated the grain size dependence of the upper yield stress (uUYP) and the yield point drop, ouyp - aLYP, in Armco iron, mild steel, and Si-Fe, respectively. These authors used center-annealed wires to avoid stress concentration from specimen shoulders and to ensure uniformity of the applied stress. Coarsegrained specimens show no yield point drop; the yield point drop then increases as d-'I2 increases (where d is the grain diameter). These results can be understood in terms of Petch's analysis2 in which the magnitude of amp depends on the strain rate in the (limited) number of grains deforming plastically at the upper yield point. If N grains per unit volume are undergoing plastic deformation, the strain rate in the deforming grains is l/Nd3 times higher at the upper yield stress than when the whole specimen deforms homogeneously. If N is constant and independent of grain size at uUyp, then all the grains are deforming when ~d~ = 1, so there is no yield point drop. At finer grain sizes, the yield point drop is given by: where AU, is the friction stress increase corresponding to a tenfold strain rate increase. Christ, Smith, and Burton studied the upper yield point in 0.050-in.-diam wire specimens prepared from zone-refined iron. Each end of the 2; -in. specimens was soldered to a & -in. diam steel ball and the load applied through the two balls. There was a yield point drop in specimens with grain diameters less than 0.1 mm; no drop was observed in specimens of grain diameter greater than 0.1 mm that were free from veining substructure, but specimens of grain diameter 0.129 mm, annealed in the y range, showed an upper yield point. and this was associated with the presence of a veining substructure in these specimens. Christ et al. suggested the upper yield point occurs when more than a specific number of grains fill the specimen cross section so a multiplicity of slip is required to initiate plastic deformation. Table I summarizes the published data on the grain size at which the yield drop disappears. On the basis of this data the ratio of specimen diameter:grain diameter = 5 to 27 appears to be the critical value for the occurrence of a yield point drop. Thus, petch2 interprets the appearance and magnitude of the yield point drop in terms of the limited number of grains deforming plastically at uuyp, whereas Christ et a1. consider that the occurrence of the yield drop depends on the ratio specimen diame-ter:grain diameter. The published data cover a wide variety of materials so some variation between the results is to be expected, but the size range covered in the data of Table I is rather limited. In an attempt to discover whether the specimen diameter:grain size ratio or the grain diameter is critical in determining

Jan 1, 1969

By R. V. Ramani, C. J. Bise

The potential of deep-mineable coal reserves in the western United States for meeting future energy needs has been recognized for quite some time. However, two of the major constraints tending to limit the development of these underground reserves are the great thicknesses of the coal seams encountered and their high pitch. Although new mining methods may need to be developed to recover these reserves, at least in the short-term the industry has to incorporate presently available equipment not originally designed for thick-seam mining. The purpose of this paper is to present an analysis of the various equipment in use today and their possible application to thick-seam mining. The paper also addresses various ground control and safety considerations unique to thick-seam extraction.

Jan 1, 1984

By Irving Cadoff, Jack Medoff

THE linear thermal expansions of oriented single crystals of zinc were measured in the range from 20" to 416°C using a Leitz HTV optical lever differential dilatometer. The single crystals, supplied by Dr. J. J. Gilman, General Electric Research Laboratory, Schenectady, N.Y., were prepared from 99.999 pct-purity zinc, and were in the form of rods approximately 2 in. long by 0.15 in. in diameter having the following orientations: x = 1.5, 12, 20, 30, 37.5, 49, 60, 73, and 82 deg where x is the angle between the specimen axis and the (0001) plane of the crystal. From the family of expansion vs temperature curves, the instantaneous expansion coefficients were calculated at 100°C intervals, and Fig. 1 shows a plot of these derived coefficients for each orientation. Coefficients were obtained from the raw data using the chord-slope method. The curves in Fig. 1 indicate a positive temperature coefficient for low x, a negative temperature coefficient for high X, and an expansion coefficient invariant with temperature, amounting to about 43 x 106, for a crystal orientation of approximately 52 deg. From the available data, it is possible to arrive at the values for the axial thermal-expansion coef- ficients a, and a, by extrapolating the curve of the expansion coefficient vs orientation to zero and 90 deg orientations. More precise values for a, and a, are obtained if the instantaneous coefficients are plotted against the square of the cosine of the orientation angle, as shown in Fig. 2. The extrapolated terminal points of the best straight line through the data points of such a plot define the axial coefficients at that temperature. The theoretical justification for the linearity of this curve comes from inspection of a rearranged form of the general anisotropic equation for expansion: ax=a, + (a, -a,)cosZx [1I in which a, is the expansion coefficient in the "c" or [0001] direction and a, the expansion coefficient in the "a" or [ll50] direction. From Fig. 2, the axial coefficients at 100°C, for example, were found to be a, = 13.9 x 10'6 and a, = 62.4 x 10"6 per "C. In the same way, the coefficients were determined for 20", 200°, 300°, and 400°C. This data is summarized in Fig. 3. It is of interest to observe the common intersection of the curves in Fig. 3, which seems to bear out the earlier observation, from Fig. 1, of a

Jan 1, 1964

By Charles C. Hawes

DETERMINATION OF SILICA OXIDE iron ores usually are found in intimate association with silica and phosphorus compounds. Their quantitative separation and purification sometimes present difficult problems to the chemist. Silicic acids may represent various degrees of dehydration. They are exeedingly weak, but combine with metallic oxides and form some of the most stable oxides in nature, the silicates. When iron ores are treated with hydrochloric acid, they yield practically all their iron. However, apart from rare exceptions, varying amounts of insoluble residues of silica, alumina, lime, magnesia and compounds of phosphorus, sulphur, titanium, chromium and others will be left. If the oxides of silicon, aluminum and titanium are present in small quantities, the insoluble residue is generally very small, but the presence of these oxides is more usual in larger quantities. Therefore, only a special treatment can break the bond between these elements. Ore Residues Acids remove the soluble constituent of the ore, leaving the insoluble residue, which chemically is rock or gangue and must be treated accordingly. Alkali carbonates are used frequently to break up the residue, but other fluxes have also been recommended, such as a number of lead and boron salts. The introduction 0f these salts, which offers certain advantages, requires, however, their removal before the other constituents can be analyzed, and this elimination is sometimes difficult. Usually in quantitative analysis silicates are dissociated by fusing them in a platinum crucible with sodium carbonate, thereby forming sodium silicate, Na2SiO3, sodium aluminate, Na2Al204, sodium titanate, Na2TiO3, and carbonates of other elements. All the carbonates are soluble in hydrochloric acid, but also some silicic acid is formed that must be rendered insoluble. To this end the solution is evaporated several times, as the first evaporation still leaves as much as 5 per cent of the silica soluble. Even after a number of evaporations, minute quantities of silica may be found with the iron and alumina present. Perchloric Acid as an Agent for Dehydrating Silicic Acid Perchloric acid, HC104, (60 per cent), has been used for years as a solvent, but few chemists have used it to dehydrate silica. It is derived from anhydrous perchloric C1207, which is most unstable and dangerous. Perchloric acid is a strong oxidizing agent, which boils at 203°C. It is more effective in rendering silica insoluble than any other known agent, and most rapid in action. After perchloric acid is added to a mixture containing silicic acid, the resultant solution is

Jan 1, 1945

By P. W. Barton, A. A. Johnson, E. J. Hughes

THE only systematic work on the effect of carbon on the recovery and recrystallization kinetics of iron so far reported in the literature is that of Venturello et al.1 These workers found that doping high-purity iron so that it contained up to 86 ppm C caused a marked retardation of recovery but had little or no effect on the recrystallization kinetics. Such evidence for an effect as was obtained was inconclusive. In the course of a study of electron-beam zone-refined iron the authors have recently examined the effect of added carbon on the recrystallization kinetics of this material. The amount of carbon added was about 50 pct more than was used by Venturello et 01. and definite evidence was obtained that carbon at this level retards recrystallization. The starting material was taken from a batch of 0.2-in.-diameter Johnson-Matthey spectroscopically pure iron rods which had been further purified by being given three passes at 4 in. hr-1 in a standard MRC electron-beam zone-refining unit. The purity of this material. which was used in two other investigations of the properties of high-purity iron,2,3 was established by an extensive series of analyses. Four laboratories, the National Research Corp., Newton, Mass., the Naval Research Laboratory, Washington, D.C.. the Battelle Memorial Institute, Columbus, Ohio, and the National Physical Laboratory. Teddington. Middlesex, England. carried out analyses for carbon. oxygen. and nitrogen. and in addition a complete mass-spectrograph analysis was carried out at Battelle. In all, twelve analyses were carried out for carbon, seventeen for oxygen and twelve for nitrogen. The amounts of these elements found to be present were 10 * 7, 8 i 5, and 0.9 i 0.1 ppm, respectively. The limits given are rms deviations. Two results, one of 46 ppm of oxygen and another of 31 ppm of nitrogen, were rejected as anomalous. The mass-spectrograph analysis revealed the major impurity to be 25 ppm of tungsten. All of the other elements detected were present in amounts less than 0.5 ppm. Some of the rods were doped with carbon by being immersed in a suspension of carbon in oil, heated in a vacuum at 400°C, and then zone-leveled to make the distribution of carbon uniform. Carbon analyses carried out on three of the doped rods gave a mean value of 130 ± 45 ppm. Some of the doped and undoped rods were deformed 58 pct by swaging and cut into specimens 1/2 in. in length. Isothermal recrystallization experiments were then carried out on them at 575", 600°, 615", 630°, and 650°C, the volume fraction of each specimen recrystallized being measured by a point-counting method described by Hilliard and Cahn.4 The results for the two types of specimens are shown separately in Figs. 1 and 2. In Fig. 3 the pairs of recrystallization curves for each temper-

Jan 1, 1965