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Erwin S. SperRy, Bridgeport, Conn.: The analysis of refined copper is a subject of great importance, and has not received the attention it deserves. Copper metallurgists, therefore, will welcome the paper of Mr. Heath with satisfaction. The state of the art of the chemical analysis of copper has been such that consumers, if they could not afford to run any risk, have been obliged to buy copper from the smelter having the best reputation, and a specification for copper to meet certain requirements could not be drawn up by the mere giving of the chemical constituents. Mr. Heath has brought the analysis of the copper to such a state that when a specification calls for copper " equal to Lake copper " one will know immediately what percentage of the pure metal to expect. It seems to be a pretty well established fact that the copper of Lake Superior is practically free from antimony and bitmuth ; and, with the exception of arsenic, the other elements are easily separated from copper by electro-deposition in an acid solution. The authorities differ in regard to the question whether antimony is deposited with the copper in an acid solution. Classen* recommends the employment of a solution containing 10 per cent. of free nitric acid, sp.gr.1.21, and the strength of the current from 0.3 to 0.4 ampere, in order to prevent the other metals from being deposited with the copper; and for this reason, I presume, the method has been generally used. I, myself, have been accustomed to use such a solution for the analysis of copper-alloys, but have found that for such alloys only a small quantity of nitric acid is necessary, if sulphuric acid is present in sufficient amount to give the solution the required conductivity.

Jan 1, 1898

By Thomas T., Read

IT is difficult to judge how much influence the success attained during its first year, 1864-65, by the School of Mines at Columbia had on developments in education for the mineral industry elsewhere in the immediately subsequent years. The facts are as follows: 1. The Massachusetts Institute of Technology began giving instruction in February 1865, with a mining course included in its curriculum. 2. Early in 1865 the faculty of the Department of Science, Literature and the Arts of the University of Michigan requested permission from the Regents to establish "a course of study to be called the School of Mines . . . Also that the degree of Mining Engineering, be conferred on students who should complete the course of study prescribed in the same." A resolution authorizing this was adopted by the Regents on March 28, 1865. 3. Samuel Hooper endowed a Sturgis-Hooper professorship of geology at Harvard in 1865 with the intention of making it a nucleus of a new School of Practical Mining and Geology. 4. Yale appointed Alfred P. Rockwell professor of mining in 1865. 5. Lafayette College appointed Henry S. Osborn professor of mining and metallurgy in 1865. 6. Washington College (as Washington and Lee was then known), rising out of the ashes of Civil War destruction, made a fresh start in 1865, with Generalized as its president, and offered a mining course in the first catalogue thereafter published. 7. Lehigh University, founded in 1866, had a mining curriculum from its beginning. 8. Rensselaer Polytechnic began offering a curriculum in mining and metallurgical engineering in 1867. It would be natural to suppose that these events were a reaction, to the success of the school at Columbia, - and possibly they

Jan 1, 1941

By AIME AIME

A DOCUMENT of progress and of great interest to engineers is the report of the Military Affairs Committee of 'the Engineering Council, which has just been accepted and sent to the secretary of War. It provides .a plan whereby civilian engineers holding commissions in the Reserve Corps may; with their con- sent, be called into service of the army during peace at any time, either with troops in the field or in a consulting capacity on any government engineering work. The Military Affairs Committee finds ample authority in the military bill passed by Congress on June 4, 1920, for this arrangement and also for extending the privilege to military engineer, officer-s of the regular army to engage in civilian work during times of peace. It is hoped that the Secretary of War will adopt the suggestions and put the program outlined into effect. This is a constructive piece of work comparable to the efforts of the military Committee before the war which developed so much in the way of preparedness, particularly in the program of military lectures which, held in the auditorium in the Engineering Societies Building, became so popular that each lecture had

Jan 1, 1920

By E. P. Pfleider

Important economic planning by industries, companies, financial firms and governments is predicated on estimates of future growth potential. Prior to the passage of the Taconite Amendment by the people of the State in November 1964, various admittedly conservative forecasts were made of the future of Minnesota's iron ore industry. Since that date, 3 new taconite plants are under construction, 2 are being expanded, one has just gone "on stream," and a seventh is in the design stage. These plants have a total capacity of about 35 million tons of pellets annually. The pessimism of 1964 today is being replaced by unbounded optimism. In the light of such recent developments, it becomes essential to update forecasts related to production, employment and capital investments. New projections show 50 to 58 million tons of pellet production from Minnesota by 1975. This tonnage, together with some 6 to 8 million of natural ores, should provide an annual full-time employment of 15,000 by the mining companies, plus 700 in related railroad and power producing activities and 1000 in plant construction. Total capital investment in new plants should reach $1.5 billion by 1975 and $2 billion by 1990. These current estimates indicate that the conservative goals as set in 1964 for the year 1990 should actually be achieved by 1975 or 1980. BACKGROUND Various forecasts1,2,3 have been made of the future consumption and production of iron ores within the United States. The most recent of these is by Harrison,1 delivered at the American Mining Congress meeting in Las Vegas in October. His estimates reflect the latest iron ore developments on a world wide front as well as the accelerating trend toward pellets. Minnesota's Natural Resources council prepared a detailed report in 1964 outlining the various factors that affect the future of Minnesota's iron ore industry. It presented estimates predicated on the

Jan 1, 1967

By D. P. Pope, T. Vreeland

Observations of dislocations in zinc using Berg-Barrett X-ray micrography confirm the validity of a dislocation etch for (1010) surfaces. A technique for measurement of the depth in which dislocations can be imaged in X-ray micrographs is given. This depth on (0001) surfaces of zinc was found to be 2.5 µ using a (1013) reflection and CoKa radiation. BUCHANAN and Reed-Hill (B & RH) have recently questioned the ability of a dislocation etch to reveal all of the basal dislocations which intersect (1010) surfaces in annealed zinc crystals.' This etch was developed by Brandt, Adams, and Vreeland who conducted a number of different experiments to check its ability to reveal dislocations.2,3 B & RH prepared (0001) foil specimens for transmission electron microscopy from annealed crystals and observed dislocation densities of about l08 cm per cu cm in the foils, while the etch indicated densities of the order of l04 cm per cu cm in their annealed crystals. As this etch has been used in a number of studies of dislocations in zinc, it is of considerable importance to reassess its validity in the light of the B & RH results. The X-ray work reported here was undertaken to check the ability of the etch to reveal dislocation intersections on (1070) surfaces of zinc. The X-ray technique was chosen for this check because it could be applied to the as-grown crystals with a relatively small amount of specimen preparation. We believe that the possibility of accidental deformation in preparation of the bulk specimens is considerably less than that for thin foil specimens suitable for transmission electron microscopy. Unfortunately, basal dislocations are not visible on Berg-Barrett topo-graphs of (1010) surfaces, which are the surfaces on which the etch is most effective. Therefore, a one-to-one correspondence between the etch and X-ray observations could not be made. Basal dislocations near (0001) surfaces have been observed by Schultz and Armstrong4 using the Berg-Barrett technique, but they did not report the as-grown dislocation density observed in their crystals. We have applied the X-ray technique in this study to surfaces oriented from 1 to 2 deg of the (0001) to determine the basal dislocation density, and have compared this density with that observed using the etch on a (1070) plane of the same crystal. The X-ray observations permit determination of the depth in which basal dislocations can be observed under the diffracting conditions used. SPECIMEN PREPARATION High purity zinc crystals are very soft, so a good deal of care must be exercised in the preparation of observation surfaces. As-grown crystals approximately 2.5 cm in diam and 20 cm long were acid cut into 1.25 cm cubes. A thin slab was cleaved from an (0001) surface to produce an accurately oriented reference surface on the specimen. Some of the cubes were examined in the as-machined condition while some were annealed in argon at 410°C for 2 hr. Heating and cooling rates were less than 2°C per min. Some of the specimens were scratched on a (0001) surface with a razor blade to produce fresh dislocations. Approximately 2 mm of material was acid lapped from one face of a cube to produce a surface oriented between 1 and 2 deg from the basal plane and parallel to the [1210] direction. A (1070) surface was also acid lapped. The lap used a 1 to 3 pct solution of HN03 in water to saturate a soft cloth which was backed by a stainless steel plate. The cloth was moved over the crystal surface at a rate of 20 cm per sec while a normal force of about 4 g was maintained between the cloth and the specimen. As-lapped surfaces were examined as were surfaces which were chemically and electrolytically polished after lapping. The small angle between a lapped surface and the (0001) plane was measured to 0.1 deg using a Unitron microgoniometer microscope (the cleaved surface was used as a reference in this measurement). The microscope was modified so that the intensity of reflected light could be continuously monitored on a meter. This modification produced nearly a ten-fold increase in the reproduceability of orientation readings. OBSERVATIONS The Unitron Microgoniometer observations indicated that the lapped surfaces had a terraced structure with the terraces quite rounded and spaced about 0.1 mm in the [1010] direction. The maximum change in slope between terraces was 0.25 deg, indicating a terrace height of about 0.1 µ. A Unitron measurement of the average angle between (0001) and a lapped surface was checked by micrometer measurement of the specimen and found to agree within 0.1 deg. The Berg-Barrett micrographs using (1013) reflections and CoKa radiation5 revealed subboundaries, short dislocation segments, spirals, and loops near the surfaces which were oriented from 1 to 2 deg of the (0001). Micrographs of surfaces prepared by lapping appeared very similar to those of the chemically and electrolytically polished surfaces. The loops and spirals were not extinct in (1013) or (0002) reflections, indicating that they have a nonbasal Burgers vector. Extinctions of the short, straight dislocations indicated that they belonged to an (0001)(1210) system. Fig. 1 is an example of a micrograph which shows a subboundary, and dislocation segments which are pre-

Jan 1, 1970

By AIME AIME

PURSUANT to a recommendation made by the Section delegates at their conference at the Annual Meeting of the A.I.M.E. last February, the Directors, at their meeting on March 15, 1944, appointed a committee charged with the duty of investigating the present status of licensing and registration of engineers, and to make a report on the whole subject for the information of the mining fraternity. The committee consisted of E. W. Ellis, chairman, H. D. Keiser, Henry T. Mudd, J. J. Croston, and Simon Strauss. Messrs. Keiser and Strauss were unable to assist in the work of the committee, and Mr. Mudd was forced to resign in July, his place being taken by A. F. Greaves-Walker. Able assistance was given the committee by T. Keith Legare, executive secretary of the National Council of State Boards of Engineering Examiners, and by Ed. ward Larson, executive secretary of the National Society of Professional Engineers. The accompanying somewhat condensed version of the report of Mr. Ellis's committee, dated Oct. 15, 1944, is confined to facts rather than to recommendations. The "Model Law" to which reference is made was first drafted by repre¬sentatives of six national engineering societies in 1911. It has since been amended many times, the latest version dated June 1943 is recommended to the State Licensing Boards as a pattern for formulating or amending state laws. A copy of the "Model Law" in pamphlet form will be sent to any member on request from A.I.M.E. headquarters while the supply lasts. The report:

Jan 1, 1945

By S. Sumski, M. B. Panish, R. T. Lynch

The liquidus isotherms in the gallium-rich corner of the Ga-Al-P phase diagram have been determined from 1000" to 1200°C and at I100°C the corresponding solidus isotherm was obtained. A simple thermody-namic treatment which permits calculation of the solidus and liquidus isotherms is discussed. A technique which was previously used for the growth of GaxAl1-xAs was used for the preparation of solution epitaxial layers of GaxAl1-xP and ALP. An approximate value of 2.49 i 0.05 ev for the band gap of Alp at 300°K was obtained and the ternary phase data were used to estimate a value of 36 kcal per mole for the heat of formation 0f Alp at that temperature. The Gap-A1P crystalline solid solution is one in which there exists the possibility of obtaining crystals with selected energy gaps, within the limits imposed by the energy gaps of Gap and Alp. Such crystals are of considerable interest because of their potential value for optoelectronic and other solid-state devices. Furthermore, it has been amply demonstrated for GaAs and GaP,'-7 that device, or bulk materials grown from gallium solution generally have more efficient radiative recombination than materials prepared in other ways. This presumably due to the lower gallium vacancy concentration in such material.= Small crystals of GaXAl1-xP and A1P have been grown from solution,8-10 and A1P has been grown from the vapor," but neither have previously been grown by liquid epitaxy. In this paper we present the ternary liquidus-solidus phase diagram of the Ga-A1-P system in the region of primary interest for solution epitaxy, and discuss the thermodynamic implications of that phase diagram with particular reference to the liquidus and solidus isotherms in the gallium-rich corner of the GaxAl1-xP primary phase field and to the A1-P system. Several measurements of the absorption edge of GaxAl1-xP crystals have been made and the width of the forbidden gap of A1P has been estimated from these measurements. EXPERIMENTAL The differential thermal analysis technique used to determine the liquidus isotherms and the optical measurements used in this work are similar to those described previously12 for the Ga-Al-As system, ex- thermocouples in the thermopile for added sensitivity. The materials used were semiconductor grade Ga, Gap, and Al+ The composition and temperature range at which DTA studies could be done was quite restricted. The upper temperature was limited by the chrome l-alumel thermopile to about 1200°C, and the highest aluminum concentration to about 5 at. pct by low sensitivity caused by the reduced solubility of Gap with increasing aluminum concentration in the liquid. DTA studies were not possible at 1000°C and below because of the low sensitivity caused by low solubility of Gap in the Ga-A1-P system. The cooling rate for these studies was about 1°C per min. No heating studies were done because of limited sensitivity. Supercooling probably does occur, but our experience with other 111-V systems indicates that it is no greater than about 10 to 15.c. Solid solubilities were determined by analyzing epitaxial layers of GaxAl1-xP grown from the liquid, with an electron beam microprobe. The layers were grown on Gap seeds by a tipping technique in which the layer is grown over a short-temperature range (20" to 50°C) on the seed from a solution of known composition. The tipping technique reported by Nelsson1 for GaAs could not be used, particularly for solutions containing appreciable amounts of aluminum, because of the formation of an A1203 scum on the liquid surface. A system was therefore designed, which would effectively remove the oxides mechanically, so that uniform wetting and crystal growth could occur. This tipping technique has already been described in detail." The best control over the composition of the re-grown layer was obtained when the tipping was done at a temperature which corresponded to the temperature of first formation of solid for the solution being used. Generally, therefore, a solution was prepared by adding the amounts of Ga, Gap, and A1 required to yield a solution which would be completely liquid above the tipping temperature with solid precipitating below that temperature. For most of the work reported here, the 1100°C isotherm of the ternary was used. It was generally necessary to heat the solution to 50" to l00. C above the tipping temperature to dissolve all of the Gap in a reasonable length of time. The epitaxially grown layers were used both for optical transmission measurements to aid in the estimation of the way in which the absorption edge changed with aluminum concentration, and for the electron beam microprobe analyses to provide data for the determination of the solid solubility isotherm. RESULTS AND DISCUSSION Liquidus Isotherms in the Ga-A1-P Ternary Phase Diagram: Thermodynamic properties of the system. The only thermal effect studied in this work was that

Jan 1, 1970

By Russell B. Cornell, William B. Plank

AT the close of the academic year 1940-'41 the largest number of students ever recorded received their first or bachelor degree in the mineral technology schools of the United States. The total of men thus prepared to enter their professional careers in the mineral industries was 1601, a number nearly 12 per cent larger than two years ago and nearly 75 per cent larger than four years ago. Notwithstanding this increase in the number of graduates and as had been predicted in the preliminary report in February, there was a slight decrease in the total student population of the schools in both the United States and Canada. During the college year 1940-'41, 9133 students were enrolled in the 54 schools of the United States and 764 in six of the seven schools of Canada.

Jan 1, 1941

By JOHN A. FULTON

THE Comstock Lode is in Storey County, Nevada, and extends in a north and south direction through the towns of Virginia City and Gold Hill, with a total length of 4.27 miles. Its mines have produced silver and gold to a known value exceeding $400,- 000,000 since 1859, when the work first began. More than $126.000,000 was paid in dividends by the mining companies, although much more than this was probably realized from the ore, because many milling companies were independent companies owned by the directors and superintendents of the mines. The milling companies' contracts called for an extraction of only 65 per cent and, as much of the ore was worth $100 a ton and up- ward, they must have recovered substantial amounts for their own accounts over and above this guarantee. Gold was discovered in the spring of 1850 by a party of Normons bound for California. The discovery was made at the mouth of Gold canyon near Dayton, on the Carson River, about 10 miles south of Virginia City.

Jan 1, 1929

By A. W. Fahrenwald

Cell depth has been for many years a controversial question in a flotation-machine performance. In the impeller type of machine, we are really talking about impeller submergence—i.e., the depth in the pulp at which the impeller is required to produce aeration. The Flotation Machine a Compressor A flotation machine can be considered as an air compressor or blower in which the aeration mechanism takes in air under atmospheric pressure† (14.7 Ib. per sq. in.) and blows it into the pulp (the pulp being the receiver) against a head of 14.7 plus cell depth in feet times 0.4333 lb. per sq. inch. In commercial machines the impeller is submerged in the pulp to depths ranging from about 2 ft. in the smaller machines to as much as 5 ft. in some of the larger ones. In the 2-ft. cell, the hydrostatic head on the impeller is (2 X 1.25 =) 2.50 ft. (assuming a pulp density of 1.25), equal to (2.50 X 0.4333 =) 1.078 Ib. per sq. in. For the 5-ft. cell, the hydrostatic head against which the impeller must make air is (5 X 1.25 X 0.4333 =) 2.708 Ib. per sq. inch. In the small 2-ft. machine, the volume reduction is (1.078 ÷ 0.147 + 0.01078 =) 6.85 per cent and in the large, 5-ft. machine, the volume reduction is (2.708 0.147 + 0.02708 =) 15.5 per cent. It is obvious that for unit volume of free air intake the larger machine receives a lesser (8.65 per cent less) volume of aeration* than the smaller machine. The bubbles in escaping from the pulp expand and are greater in volume at the surface than at the moment of their formation in the pulp; 7.33 and 18.4 per cent larger, respectively, in the small and large machines. Just how this situation affects flotation is not known. It is interesting to note, however, that the bubbles are smaller in the zone of the coarsest particles and largest in the upper zones of the her, more easily suspended mineral particles. It would seem that the relationship might be reversed advantageously. The deep cell is at a greater disadvantage in this respect than the shallow cell. Nothing, however, presumably can be done about this situation. The shallow cell is a partial corrective. Not only does the compression ratio of aeration increase with impeller submergence but the hydrostatic head against which the impeller must operate also increases. The Flotation Machine as a Pump Since, in impeller machines that rely upon their own operation to produce aeration, pulp Passes through the im-

Jan 1, 1947

By A. W. Fahrenwald

Cell depth has been for many years a controversial question in a flotation-machine performance. In the impeller type of machine, we are really talking about impeller submergence—i.e., the depth in the pulp at which the impeller is required to produce aeration. The Flotation Machine a Compressor A flotation machine can be considered as an air compressor or blower in which the aeration mechanism takes in air under atmospheric pressure† (14.7 Ib. per sq. in.) and blows it into the pulp (the pulp being the receiver) against a head of 14.7 plus cell depth in feet times 0.4333 lb. per sq. inch. In commercial machines the impeller is submerged in the pulp to depths ranging from about 2 ft. in the smaller machines to as much as 5 ft. in some of the larger ones. In the 2-ft. cell, the hydrostatic head on the impeller is (2 X 1.25 =) 2.50 ft. (assuming a pulp density of 1.25), equal to (2.50 X 0.4333 =) 1.078 Ib. per sq. in. For the 5-ft. cell, the hydrostatic head against which the impeller must make air is (5 X 1.25 X 0.4333 =) 2.708 Ib. per sq. inch. In the small 2-ft. machine, the volume reduction is (1.078 ÷ 0.147 + 0.01078 =) 6.85 per cent and in the large, 5-ft. machine, the volume reduction is (2.708 0.147 + 0.02708 =) 15.5 per cent. It is obvious that for unit volume of free air intake the larger machine receives a lesser (8.65 per cent less) volume of aeration* than the smaller machine. The bubbles in escaping from the pulp expand and are greater in volume at the surface than at the moment of their formation in the pulp; 7.33 and 18.4 per cent larger, respectively, in the small and large machines. Just how this situation affects flotation is not known. It is interesting to note, however, that the bubbles are smaller in the zone of the coarsest particles and largest in the upper zones of the her, more easily suspended mineral particles. It would seem that the relationship might be reversed advantageously. The deep cell is at a greater disadvantage in this respect than the shallow cell. Nothing, however, presumably can be done about this situation. The shallow cell is a partial corrective. Not only does the compression ratio of aeration increase with impeller submergence but the hydrostatic head against which the impeller must operate also increases. The Flotation Machine as a Pump Since, in impeller machines that rely upon their own operation to produce aeration, pulp Passes through the im-

Jan 1, 1947

By A. W. Fahrenwald

CELL depth has been for many years a controversial question in a flotation-machine performance. In the impeller type of machine, we are really talking about impeller submergence-i.e., the depth in the pulp at which the impeller is required to produce aeration. THE FLOTATION MACHINE A COMPRESSOR A flotation machine can be considered as an air compressor or blower in which the aeration mechanism takes in air under atmospheric pressure[t] (14.7 lb. per sq. in.) and blows it into the pulp (the pulp being the receiver) against a head of 14.7 plus cell depth in feet times 0.4333 lb. per sq. inch. In commercial machines the impeller is submerged in the pulp to depths ranging from about 2 ft. in the smaller machines to as much as 5 ft. in some of the larger ones. In the 2-ft. cell, the hydrostatic head on the impeller is (2 X 1.25 =) 2.50 ft. (assuming a pulp density of 1.25), equal to (2.50 X 0.4333 =) 1.078 lb. per sq. in. For the 5-ft. cell, the hydrostatic head against which the impeller must make air is (5 X 1.25 X 0.4333 =) 2.708 lb. per sq. inch. In the small 2-ft. machine, the volume reduction is (1.078 [-] 0.147 + 0.01078 =) 6.85 per cent and in the large, 5-ft. machine, the volume reduction is (2.708 [=] 0.147 + 0.02708 =) 15.5 per cent. It is obvious that for unit volume of free air intake the larger machine receives a lesser (8.65 per cent less) volume of aeration* than the smaller machine. The bubbles in escaping from the pulp expand and are greater in volume at the surface than at the moment of their formation in the pulp; 7.33 and 18.4 per cent larger, respectively, in the small and large machines. Just how this situation affects flotation is not known. It is interesting to note, however, that the bubbles are smaller in the zone of the coarsest particles and largest in the upper zones of the finer, more easily suspended mineral particles. It would seem that the relationship might be reversed advantageously. The deep cell is at a greater disadvantage in this respect than the shallow cell. Nothing, however, presumably can be done about this situation. The shallow cell is a partial corrective. Not only does the compression ratio of aeration increase with impeller submergence but the hydrostatic head against which the impeller must operate also increases. THE FLOTATION MACHINE AS A PUMP Since, in impeller machines that rely upon their own operation to produce aeration, pulp passes through the im-

Jan 1, 1946

By Joklik, G. F.

Most publicity about the copper industry nowadays is focused on the adequacy of ore reserves and on excessive mining capacity. These concerns, stemming from public awareness of actual and potential shortages and oversupplies, relate to production rather than consumption. Perhaps the reason for this one-sided view is that copper is thought of as a commodity which is conspicuously traded in world markets, rather than as one of many industrial materials that serve today's rapidly changing technology. Copper differs from other widely traded commodities in that its real cost of production has progressively increased since World War 11. The reasons for the increase are identifiable by analyzing operations in one of the world's large producing centres, the copper province of Arizona. Another respect in which copper differs from some other commodities is that increases in demand occur less automatically in the case of copper than they tend to in commodities whose consumption is more directly related to population growth. The copper industry's current inability to generate and attract needed investment capital is attributable to these differences between copper and other commodities; it suggests that the concept of copper purely as a commodity is outdated. The key to the problem is better integration between the activities of copper producers and users. Depending on circumstances, integration takes various forms- for example, investment tied to long-term sales con- tracts between producers in developing countries and consumers overseas; common ownership of producing and manufacturing facilities in industrialized nations like the U.S.; and consumer-oriented research and marketing by the copper producers.

Jan 1, 1978

By J. G. Savins

Certain types of macromolecules added to water and salt solutions flowing in turbulent motion can reduce the pressure gradient. Alternatively, the volumetric capacity of a pipe for these fluids is increased by the presence of these materials. Examples presented show that the drag reduction can become significant. Thus, the presence of 0.28 per cent of a gum derivative in a solution of sodium chloride flowing at 200 gal/min in a 1.89-in. pipe yields a pressure drop which is 0.44 of the single-phase drop measured under the same conditions of turbulent flow; the addition of 0.1 per cent of a vinyl derivative to a I-in. water line yields a throughput capacity which is 1.78 of the single-phase capacity at the same pressure drop. It is further shown that these phenomena are distinctly different from previous observations with other classes of non-Newtonian systems. There a simple lowering of friction factors below the levels predicted from the resistance laws for Newtonian fluids is associated with a suppression of turbulent motion. A rational physical explanation for drag reduction is advanced. Briefly, the proposed mechanism is a storage by the molecular elastic elements of the macromolecules in solution of the kinetic energy of the turbulent motion. INTRODUCTION This study was inspired by a recent review of some paradoxical drag reduction phenomena in turbulent pipe f1ow.I Under very moderate conditions of turbulent flow, the pressure gradient necessary to pump solutions containing certain specific kinds of polymers, fibers and metallic soaps may become appreciably lower than that required* to pump the solvent, i.e., water or a low-viscosity hydrocarbon, under identical flow rates in the same conduit. As shown by our review, this phenomenon of drag reduction in turbulent duct flow was first noted during the second world war, apparently arising in connection with the development of flame warfare weapons. Since that time several papers illustrating this phenomenon have appeared: Toms, Oldroyd,3 Agoston et al., Bundrant and Matthews, Robertson and Mason,6 Ousterhout and Hall,7 Daily and Bugliarello~ Lummus, Anderson, and Fox. 9 That there are practical applications for techniques which increase discharge or decrease the pressure necessary to transport a liquid through a pipeline is illustrated in the patents which have issued which take advantage of this peculiar phenomenon, e.g., Mysels,l0 Dever, Harbour, and Seifert.11 One also finds fragmentary evidence of this effect in the data pertaining to a few of the polymeric solutions studied by Shaver12 and Dodge.13 However, these investigators were concerned with the development of friction factor vs Reynolds number correlations for a variety of non-Newtonian solutions and suspensions, rather than in a study of drag reduction-. A similar kind of drag reduction effect has been observed in gases. Sproull, for example, reports that adding dust to air flowing in turbulent motion through a pipe results in a lowering of the pressure gradient at identical flow rates. There are also military applications for reducing the drag on hydrodynamic vehicles. For example, the possibility of injecting a rheologically complex fluid into the boundary layers of bodies to reduce the skin friction has been investigated by Fabulal5 and Granville.16 Along somewhat different lines are the drag reduction studies of Kramer.17118 He has shown that skin friction can be reduced by covering the surface of a vehicle with a flexible skin. The effect is apparently due to the boundary layer being stabilized by the presence of the skin. Drag reduction by means of coexisting gas and liquid boundary layers, e.g., film boiling and continuous gas injection, has been proposed by Bradfield, Barkdoll, and Byrne,19 Cess and Sparrow,20'21 Sparrow, Jonsson, and Eckert.22 Here the skin friction occurs between a vapor and a surface rather than between a liquid and a surface. There are several references in the literature to friction-factor correlations for non-Newtonian solutions and suspensions: Shaver and Merri11,23 Dodge and Metzner, Clapp,25 and Thomas.26

Jan 1, 1965

By W. A. Tiller, W. C. Johnston

A high-temperature electromagnetic stirrer is described in which heating and stirring are accomplished by independently controlled power sources. The appavatus is suitable lor use at temperatures up to 1700°C in a variety of ambient atmospheres. Some typical examples of the homogenizatimz capabilities of the system are given. THERE are few processes in solidification that are not markedly affected by motion in the melt during freezing. In many instances, the mechanisms are diffusion-controlled, and the transport in the melt may be greatly accelerated by deliberately stirring the melt. In zone-refining, stirring1 assists the removal of rejected impurities from the interface, so the process proceeds at a faster rate. The transition from a planar to a cellular interface is caused by constitutional undercooling in the melt ahead of the interface: and stirring delays its onset. Stirring is valuable for homogenization of melts: and chemical reaction with sluggish kinetics may be accelerated. Finally, it has been observed that grain refinement is related to motion in the melt. Fine grain castings are usually produced by the addition of catalysts to the -melt,' catalysts which are thought to act simply as hetereogeneous nucleation centers. Even here motion is important. Richards and Rostoker 5 applied ultrasonic vibration to a solidifying A1-Cu alloy which had been innoculated with a catalyst and found that the grain diameter fell linearly with the amplitude, the peak acceleration and the power input to the melt from the transducer. Finally, mechanical and electrical stirring alone have been used to generate a fine-grained structure.6,7 Johnston ef a1.' have carried out a series of systematic investigations of grain refinement by electromagnetic stirring in a number of low melting point alloys. They found, for example, that the number of grains per unit volume in Pb-Sn alloys could be increased several orders of magnitude by stirring an undercooled melt at the moment of recalescence. In general, a relation AT .H = constant prevailed for a given grain size, where AT was the undercooling of the melt and H the field strength. In more recent work, deliberate homogeneous nucleation of slightly undercooled melts established that the mechanism of refinement must be one involving crystal fragmentation and subsequent multiplication, rather than a "shower" of nuclei effect.9 It is the purpose of this note to describe a stirring device suitable for use up to 1700°C. At low temperatures mechanical stirring and direct-current methods are feasible, but at high temperatures the problem of a protective atmosphere and of electrode corrosion rules out such procedures. The most convenient method for high temperatures is to use externally generated ac fields for both stirring and heating. With rf induction heating alone, considerable stirring and agitation can be achieved, but in general the penetration of field into the melt is small, and the stirring cannot be controlled independently of the heating. In the present experiments, separate power sources of different frequencies for heating and for stirring were used. A susceptor design was chosen so that the 450 kc rf heating field was completely absorbed in the susceptor. The stirring frequency, 400 cps, hereafter called the af field, was chosen so that a high penetration of the melt proper was achieved. EXPERIMENTAL APPARATUS The apparatus, Fig. 1, consists of a quartz tube and end plates, surrounded by an rf induction coil and six equally spaced af stirring coils, four of which are shown in full and a fifth in section. Each af stirring coil is a transformer of which the secondary is a single-turn water-cooled copper loop and the primary is composed of two 10 amp-117 v Variac cores as shown. These cores are cooled by forced air, as each of the six pairs will carry maximum currents of 15 amp for short periods. Each set of Variac windings are connected in series, but opposite sets are connected in parallel with a three-phase 400 cps 400-v source. By properly phasing the coils in this way, a rotating field is produced. Capacitors C1, C2, and C3 in Fig. 2 are used to match this inductive load to the generator. Fig. 3 shows a cutaway view of the quartz tube. The sample (1 in. diam by 1 in. high) is placed in a tapered alumina crucible. An axial W-26 pct Re thermocouple, enclosed by a protection tube, is provided. The cruci-

Jan 1, 1968

By L. W. Rowe, S. S. Cole

A laboratory bench scale unit is described whereby finely divided chlorinatable residues are held for a short period by a restraining bed of a coarse-grained ore of comparable composition to permit 'flash' chlorination of the high surface area powder. Results on chlorinating a finely divicled titania residue using rutile sand as the restraining bed showed that 92 pct utilization of chlorine and equivalent conversion of TiO2 in the fine residue to Ticl4 were attained with a dust loss of about 3 to 4 pct and an equivalent amount of ch1om'nation of the titanium values in the restraining bed. THE chlorination of coarse grain titaniferous ores; i.e., 20 to 150 mesh sizes in fluidized beds is practiced commercially.' One effective method found for the chlorination of a very fine material in a fluidized bed is the "flash" chlorination technique.' By charging the finely divided charge material into the bottom of an established bed of optimum sized rutile, ilmenite, titanium beneficiate, or even an inert material such as sand, chlorination occurs before the dust can pass through the bed. The major requirement is that the bed be less chlorinatable than the charge. In this process, the charge consists of a finely divided (between one and 50 µ) titania residue obtained from a titaniferous ore beneficiation process. The charge is blended with a 20 pct wt basis addition of 20 to 60 .mesh size low volatile coke (to minimize hydrogen chloride formation) and fed to the bottom of the bed with the chlorine gas stream. A ball check device is used to permit entry of the charge and prevent the bed from discharging when the gas flow is cut off. The coarse pieces of coke serve to reduce compaction in the charge mixture and permit sat]sfactory feeding without plugging or jamming. Feed and gas rates are adjusted to provide for complete reaction of the charge material, with 90 to 95 pct chlorine efficiency, and maintain a gas flow in the range of 0.4 to 0.6 ft per sec. The equipment consisted of a 3-in. diam mullite tube enclosed in an electric furnace. A bow-shaped 3/4 in. Saran tube fed the charge from an air lock type of feed hopper (to prevent the escape of the chlorine gas into feed bin) to the bottom of the bed. The charge rate was set by providing a small awiliary hopper below the feed hopper where a weighed portion of the charge could be discharged in a specified time interval into the main chlorine stream. The chlorine rate was measured by a flowmeter. The reaction tube was filled with a bed of Australian rutile ore, this restraining bed serving two purposes; i.e., it rapidly heated the fresh charge to the reaction temperature and retained the particles in the bed for a sufficient time for selective chlorination to proceed. Due to the fine particle size and open, porous structure of the charge, this reaction was almost instantaneous, and, with proper adjustment of feed and gas rates, very little fine material passed through the bed without reacting and only a very small fraction of the restraining bed was chlorinated. A typical reaction procedure was to fill the bench scale fluidized bed unit with a 1 kg charge of Australian rutile ore analyzing 95.5 pct TiO2, 0.6 pct FeO, a beach sand deposit 40 to 150 mesh size. When fluidized, the bed was approximately 2 ft in depth. The ore was fluidized with a 1:l mixture of chlorine and nitrogen at a rate of 0.40 ft per sec. This gas mixture was necessitated by the comparatively short bed depth; a larger unit, with a deeper bed, could be fluidized with chlorine alone without significant free chlorine loss. Feed rate was 8.0 g per min of beneficiated ilmenite analyzing 85.0 pct TiO2, 2.6 pct FeO plus 1.6 g per min of 20 to 60 mesh petroleum coke. The

Jan 1, 1962

By John D. Price

R. W. Campbell (Jones and Laughlin Steel Carp., Pittsburgh)—As usual John Price has presented an excellent paper. I know of no one who has devoted more time and conscientious thought to this subject than he has, and his efforts have produced scientific data and conclusions of real value. Results of similar studies made by the Jones and Laughlin Steel Corp. on the blending of Pennsylvania coals may be of interest. During 1935 the late F. W. Wagner and the present writer developed an empirical physical fuel value formula for evaluating the combined physical tests of metallurgical coke, see Table IV. In the development of the formula, the tumbler test, shatter test, screen test, and porosity of coke have been taken into consideration. Each of these tests brings out some physical property not expressed by the others, and in estimation of the importance of these tests as a medium for evaluating coke for the blast furnace, their worth has been graded as follows: It was thought that some additional penalty should be applied to cokes that do not show a uniform screen size, assuming that coke larger than 4 in. was not desirable and that this size was an indication of irregular size. Therefore the screen test factor is further corrected by applying a penalty of 1 pct for each 1 pct material greater than 4-in. size as shown by the screen test. The physical fitness of coke for blast furnace use depends upon four fundamental characteristics: l—gen-era1 strength, as indicated by the shatter test; 2— abradability, or the resistance of cell walls to reduction in size by attrition, as indicated by the tumbler test; 3—porosity; and 4—size and uniformity. Each of these characteristics is not of equal importance, but surely, in an attempt to determine an accurate physical value, the individual value of each should be taken into consideration. The formula is used as a yardstick, so to speak, in determining variations in the normal production of metallurgical coke and in making comparisons between normal coke and experimental blends with other coals. Table IV gives results of coking tests on raw and washed high volatile coals and these same coals with blends of coke breeze, anthracite coal, char and low volatile coals, all from Pennsylvania. The table also gives the source of the coals and coke breeze, as well as their proximate analyses. It will be noted that the washing of the raw high volatile coal increased the physical fuel value from 26.17 to 39.16, showing the effect of removing shale and slate which produces a detrimental fracturing and weakening of the coke. It is a well known fact that many Pennsylvania high volatile coals contain an excess of resinous material or binder which has a tendency to weaken the coke, owing to its high evolution of gases during carbonization. Tests were therefore made with coke breeze, an inert material, in an attempt to alleviate this condition. Blends of washed coal with 5 pct and 7.5 pct coke breeze collected from the coke plant quenching sump (82.9 pct through 1/8-in. screen) resulted in cokes with a physical fuel value of 20.75 and 16.73 respectively, lower than results obtained from 100 pct raw high volatile coal. It will be noted that the percentage of + 4-in. coke increased but that the tumbler test was very low. Undoubtedly better results could have been obtained if the coke breeze could have been crushed extremely fine. During World War II the government asked the coking industry to consider the use of anthracite coal as a substitute for high quality low volatile coal, which was extremely scarce at the time. The next series of tests was made with blends of raw and washed high volatile coals and 5, 10, and 15 pct Pennsylvania No. 5 buckwheat anthracite (100 pct through l/8-in. screen). It was necessary to use some raw high volatile coal in these blends because of insufficient washer capacity at the time. It will be noted that the physical fuel values

Jan 1, 1954

By R. I. Jaffee, F. C. Holden, H. R. Ogden

ECENT papers dealing with the properties of unalloyed iodide titanium have been directed primarily at the determination of base-line properties for alloy investigations. Early work was limited to a few tests because of the limited availability of iodide titanium at the time. In the results of papers by Campbell et al.,1 Gonser and Litton,2 Jaffee and Campbell,3 inlay and Snyder,4 and Jaffee, Ogden, and Maykuth, data on mechanical properties are presented for unalloyed iodide titanium in the annealed and cold-worked conditions. Data are presented in this paper which show the effects of heat treatment on the structure and mechanical properties of commercially produced iodide titanium. Correlation is made between microstruc-tural variables and the mechanical properties. Experimental Procedures Melting Stock: The melting stock used was as-deposited iodide titanium, produced by New Jersey Zinc Co. The furnished analysis showed the following range of impurities: N, 0.004 to 0.008 pct; Mn, 0.005 to 0.013; Fe, 0.0035 to 0.025; Al, 0.013 to 0.015; Mo, 0.0015; Pb, 0.0045 to 0.0065; Cu, 0.0015 to 0.002; Sn, 0.001 to 0.01; Mg, 0.0015 to 0.002; and Ni, 0.003. Hydrogen content as determined by vacuum-fusion analysis was 0.0091 wt pct (0.44 atomic pct) after arc melting and fabrication. Nitrogen analysis on the arc-melted and fabricated titanium showed a content of less than 0.002 pct N. The average hardness of the furnished stock was Rf 70, or approximately 85 VHN. Melting Procedure: The as-deposited rods were rolled, sheared, and degreased in preparation for arc melting. The charge was arc-melted with a tungsten electrode in a water-cooled copper crucible under a positive pressure of high purity (99.96 pct) argon. The final ingot was approximately 2 in. in diameter and showed no increase in hardness over that of the initial stock. Fabrication: Heating for fabrication was done in air. It was begun by forging the ingot into a 3/4 in. diam rod, at an initial temperature of 1600°F. Scale was removed by sandblasting. The rod was then swaged to 1/4 in. diam at room temperature through a series of 20 dies, with approximately 10 pct reduction in area between each die. An anneal of 1 hr at 850 °C in air was given after the 1/2 in. die, such that the final cold reduction was 75 pct. Sections cut from this rod were used for test and microstructure specimens. Heat Treatment: Heat treatments were carried out in resistance tube furnaces with stainless-steel linings, under an atmosphere of gettered argon. As further protection against contamination, the specimens were packed in titanium turnings in a titanium sleeve. Control experiments have shown negligible hardness increases with this method, indicating that contamination from oxygen and nitrogen is slight. Three cooling rates were employed in this work; these have been designated as water quenching, argon cooling (to simulate air cooling under a controlled atmosphere), and furnace cooling. The cooling rate for an argon cool is 100°C per min for the first minute, with an average cooling rate of 35°C per min over a 15-min period. A furnace cool requires about 10 hr, with an average cooling rate of 3.6oC per min during the first hour, and an average cooling rate of 1.2°C per min over the 10-hr period. Microimpact Test: The specimen adopted was based on the cylindrical Izod Type Y specimen (ASTM, E23-41T). All dimensions were reduced to half scale, including the notch radius. Specifications are shown in Fig. 1. The specimen is held vertically in an adapter and broken as a cantilever beam. Impact tests were run on a constant-velocity (11.34 ft per sec) Tinius Olsen impact testing machine with a total available energy of 100 in.-lb. Tests were made to determine the correlation between this microimpact and the standard V-notch Charpy impact test. Curves showing impact energy as a function of temperature for both impact tests are plotted in Fig. 2. Transition temperatures, when they occur, are about the same for both impact tests. All three titanium-rich materials have the same conversion factor, 10. Tensile Testing: Tensile tests were conducted on Baldwin-Southwark testing machines using the 600, 2400, or 3000 1b range. Specifications for the test specimen were taken from the 1948 edition of the ASM Metals Handbook, and are shown in Fig. 1. Strain measurements were made using an SR-4 resistance gage (Type A-7) cemented to the reduced section in conjunction with a lever-type extenso-meter. Readings on the SR-4 strain indicator were

Jan 1, 1954

In the special number of the magazine Ocl und Kohle (Oct. 22, 1940) dedicated to the petroleum industry of southeastern Europe, there appeared several articles relating to Yugos1avia.t In the first article the author calls attention to the fact that there are two fields in Yugoslavia that have been explored and exploited by more than 100 wells at variable depths during the last 50 years. These are on the Island of Mura, at the confluence of the Mura and the Drave. Additional exploration drilling in various other parts of the country has been without result, but certain ones of these explorations have revealed the existence of gas horizons that have some value, which are being used for industrial purposes. Table I shows the production of oil and gas between the years 1900 and 1939. TaBle —Production of Oil ad Gas in Yugoslavia . n,i Natural Natural Years oil Years Gas, Cu. Years Gas, Cu. Meters Meters T900-1929 10,000 1923 507,000 1934 1,388,000 1930 277 1924 567,000 1935 1,401,000 1931 202 I92S 691,000 I936 1,483,000 t932 289 19261 1.472,000 1937 1,841,000 1933 629 1927! 1,732,000 193s 2,431,000 1934 324 1928 2,515,000 1939 2,628,000 1935 260 1929 4,700,000 1936 137 I93O 5.345,200 1937 463 1931 6,376,153 1938 1,091 1932 1,661,737 1939 1,114 1933 959,574 The number of wells drilled from 1884 to the present time was in the neighborhood of zoo and the total footage drilled was 65,000 m. up to July I940 They may be divided roughly as follows: 12 wells in the region produce natural gas; 134 wells in the two old fields of the Island of Mura and about zo wells for the exploration of the zone of the Flysch, in Bosnia. The depths of 50 of these wells was roo to 200 m.; the depths of 50 wells oil the Island of Mura ran from zoo to 500 m.; of 2 ; wells, 500 to I000 m.; of ro wells from rooo to 2000 meters. The deepest well drilling in Yugoslavia has reached 2000 in. In the Valley of Morave, in the region of Selnica, I00 km. south of Nish, there have been discovered asphalt-bearing limestones, which contain about 15 per cent asphalt and are associated with bituminous clays. Later, at Paclenica, important deposits of natural gas were found. A zone rich in gas and oil seepages runs through Pracec, Miklenska, Bujavica, etc. The author studied these regions from the point of view of stratigraphy and tectonics. The anticlines and gas-bearing domes are concentrated in two zones: the region of the Drave (Island of Mura) and the region of the Save, southeast of zagreb, which contains the gas field in exploitation in the region of Bujavica. A full description of the productive region of the Island of Mura has been given by Egon Bohm, a geologist, in the second article mentioned. This includes a history of the exploration and exploitation that took place under Hungarian rule in this region. The most important exploration was effected between 1884 and 1885 by Stavenov and Stinger, of Vienna. In 1927 work was done in the same region by Anton Raky, a well-known explorer who makes work of this kind his specialty.

Jan 1, 1941

In the special number of the magazine Ocl und Kohle (Oct. 22, 1940) dedicated to the petroleum industry of southeastern Europe, there appeared several articles relating to Yugos1avia.t In the first article the author calls attention to the fact that there are two fields in Yugoslavia that have been explored and exploited by more than 100 wells at variable depths during the last 50 years. These are on the Island of Mura, at the confluence of the Mura and the Drave. Additional exploration drilling in various other parts of the country has been without result, but certain ones of these explorations have revealed the existence of gas horizons that have some value, which are being used for industrial purposes. Table I shows the production of oil and gas between the years 1900 and 1939. TaBle —Production of Oil ad Gas in Yugoslavia . n,i Natural Natural Years oil Years Gas, Cu. Years Gas, Cu. Meters Meters T900-1929 10,000 1923 507,000 1934 1,388,000 1930 277 1924 567,000 1935 1,401,000 1931 202 I92S 691,000 I936 1,483,000 t932 289 19261 1.472,000 1937 1,841,000 1933 629 1927! 1,732,000 193s 2,431,000 1934 324 1928 2,515,000 1939 2,628,000 1935 260 1929 4,700,000 1936 137 I93O 5.345,200 1937 463 1931 6,376,153 1938 1,091 1932 1,661,737 1939 1,114 1933 959,574 The number of wells drilled from 1884 to the present time was in the neighborhood of zoo and the total footage drilled was 65,000 m. up to July I940 They may be divided roughly as follows: 12 wells in the region produce natural gas; 134 wells in the two old fields of the Island of Mura and about zo wells for the exploration of the zone of the Flysch, in Bosnia. The depths of 50 of these wells was roo to 200 m.; the depths of 50 wells oil the Island of Mura ran from zoo to 500 m.; of 2 ; wells, 500 to I000 m.; of ro wells from rooo to 2000 meters. The deepest well drilling in Yugoslavia has reached 2000 in. In the Valley of Morave, in the region of Selnica, I00 km. south of Nish, there have been discovered asphalt-bearing limestones, which contain about 15 per cent asphalt and are associated with bituminous clays. Later, at Paclenica, important deposits of natural gas were found. A zone rich in gas and oil seepages runs through Pracec, Miklenska, Bujavica, etc. The author studied these regions from the point of view of stratigraphy and tectonics. The anticlines and gas-bearing domes are concentrated in two zones: the region of the Drave (Island of Mura) and the region of the Save, southeast of zagreb, which contains the gas field in exploitation in the region of Bujavica. A full description of the productive region of the Island of Mura has been given by Egon Bohm, a geologist, in the second article mentioned. This includes a history of the exploration and exploitation that took place under Hungarian rule in this region. The most important exploration was effected between 1884 and 1885 by Stavenov and Stinger, of Vienna. In 1927 work was done in the same region by Anton Raky, a well-known explorer who makes work of this kind his specialty.

Jan 1, 1941