Search Documents

By H. I. Najarian

This paper is a companion piece to the description of the electrothermic process that begins on page 141. It will be confined to a brief story of the development. of the Weaton-Najarian vacuum condenserf at this plant, together with up-to-date design and operating data. The Josephtown smelter was designed primarily for production of zinc oxide. However, the development of a method for production of zinc metal had always been under consideration, and accordingly one of the original eight units of the elcctro-thermic furnaces built in 1930 was set up to produce metal. The design of this furnace was identical with that of the oxide furnaces except that in place of oxide tewels opening into oxide manifolds, conventional conical clay condensers—similar to condensers used in horizontal retort smelting—were installed around the periphery of the furnace and in several tiers vertically for condensing the zinc vapors. The early experimental work in trying to condense zinc out of the mixtures of zinc vapor and carbon monoxide gas from the electrothermic furnaces indicated that, while the gases from electrothermic smelting would condense in surface-type condensers, the formation of blue powder was excessive and condenser efficiency low. Furthermore, operating a large unit of electric furnace with several hundred small condensers, with attendant high labor cost and unfavorable operating conditions, did not appeal to us. We also realized that a single unit of surface condenser capable of condensing 12 torg tons of metal per day would be of huge dimensions and possibly difficult of control. So we took as our aim the development of a method whereby a single condenser unit of reasonable dimensions would condense zinc, in one step, from the large volume of gases that the electric furnaces produced. We set about searching for knowledge on zinc metallurgy and design of zinc condensers in particular. Our study of the prior art focused our attention on the oft-repeated statement by earlier experimenters, that the most efficient way to condense metallic vapors, such as zinc vapors, was to bring the vapors into "intimate contact" with molten metal; but the methods offered for securing this "intimate contact" in any practical manner left much to the imagination. We were handicapped by not having some-one on the Josephtown smelter staff who could lay claim to being an expert zinc metallurgist and could give guidance from actual experience on the practicability of various schemes that haunted our imagination. Laboratory Experiments However, we had an expert ex-steam engineer in the person of George I?. Weaton, manager of the Josephtown smelter, who had had long experience with steam-jet condensers and would reiterate his belief at every opportunity that the logical and the most efficient way to condense zinc would be with a jet-type condenser. We became intrigued by the possibilities of a zinc con-

Jan 1, 1944

By N. H. Fisher

GEOGRAPHICAL DISTRIBUTION THE most important known deposits in Australia of what are commonly referred to as the beach-sand minerals are along the most easterly part of the Australian coast, between Southport, 17 miles north of the Queensland-New South Wales border, and Ballina, 50 miles south of the border, and most of the production has come from this area (Fig 1). Smaller deposits are known to occur farther to the south at intervals for several hundred miles, and beaches have been worked at Yamba, 96 miles south and Woolgoolga, 150 miles south of the border and at Swansea, 60 miles north of Sydney. Important deposits have been shown to exist on north Stradbroke Island and others have been located farther to the north, as far as Tin Can Bay at the south end of Frazer Island. (Fig 2). Table I gives the list of operators with the location of their deposits and workings, their approximate maximum monthly capacity expressed in tons of heavy mineral produced by their concentrating plants before separation into individual mineral concentrates, their methods of mining and concentrating the minerals, and the products obtained. This table applies as of June 1948, but all the operators are remodeling or improving their plants and plant practices will be modified accordingly. In addition, active boring campaigns have been carried out by Alluvial Gold, Ltd., of Sydney, in the Cudgen-Cudgera area, and by Zinc Corporation. Ltd., of Melbourne, on Stradbroke Island, and in other places. PHYSIOGRAPHY Submergence of the order of 100 to 200 ft at the close of the Pleistocene period left the pre-existing hills as promontories and the valleys as deep inlets. Wave action has built bay-bars and sandspits in a northerly direction from the headlands, and lakes and marshes have formed between these bars and the initial post-submergence coast line. These lakes and swamps have been or are being filled in by river-borne sediments or wind-blown sand. Beasley1 has presented evidence that suggests a recent emergence of the coast line of about 10 ft. The evidence for this belief is the presence of a black sand seam 1/3 mile inland and 17 ft above sea level (Fig 3), and although it is not entirely certain that this seam is of beach formation and owes nothing to windblown concentration, other evidence supports the suggestion of recent emergence. Such emergence would undoubtedly aid the formation of bars and sandspits and the easterly progress of the beach front, leaving a series of parallel dunes (Fig 4). This belt of north-south coastal dunes ranges up to 1/2 mile in width and as many as 15 lines of dune have been counted (Fig 3). The foredune is generally the highest, up to 25 ft high, and there is in many places a flat platform in front of the dune known as the berm. The dunes behind the foredune are lower and less well defined

Jan 1, 1947

By N. H. Fisher

Geographical Distribution 'he most important known deposits in Australia of what are commonly referred to as the beach-sand minerals are along the most easterly part of the Australian coast, between Southport, 17 miles north of the Queensland-New South Wales border, and Ballina, 50 miles south of the border, and most of the production has come from this area (Fig I). Smaller deposits are known to occur farther to the south at intervals for several hundred miles, and beaches have been worked at Yamba, 96 miles south and Woolgoolga, 150 miles south of the border and at Swansea, 60 miles north of Sydney. Important deposits have been shown to exist on north Stradbroke Island and others have been located farther to the north, as far as Tin Can Bay at the south end of Frazer Island. (Fig 2). Table I gives the list of operators with the location of their deposits and workings, their approximate maximum monthly capacity expressed in tons of heavy mineral produced by their concentrating plants before separation into individual mineral concentrates, their methods of mining and concentrating the minerals, and the products obtained. This table applies as of June 1948, but all the operators are remodeling or improving their plants and plant practices will be modified accordingly. In addition, active boring campaigns have been carried out by Alluvial Gold, Ltd., of Sydney, in the Cudgen-Cudgera area, and by Zinc Corporation Ltd., of Melbourne, on Stradbroke Island, and in other places. Physiography Submergence of the order of 100 to 200 ft at the close of the Pleistocene period left the pre-existing hills as promontories and the valleys as deep inlets. Wave action has built bay-bars and sandspits in a northerly direction from the headlands, and lakes and marshes have formed between these bars and the initial post-submergence coast line. These lakes and swamps have been or are being filled in by river-borne sediments or wind-blown sand. Beasley1 has presented evidence that suggests a recent emergence of the coast line of about 10 ft. The evidence for this belief is the presence of a black sand seam 1/3 mile inland and 17 ft above sea level (Fig 3), and although it is not entirely certain that this seam is of beach formation and owes nothing to windblown concentration, other evidence supports the suggestion of recent emergence. Such emergence would undoubtedly aid the formation of bars and sandspits and the easterly progress of the beach front, leaving a series of parallel dunes (Fig 4). This belt of north-south coastal dunes ranges up to 56 mile in width and as many as 15 lines of dune have been counted (Fig 3). The foredune is generally the highest, upto 25 ft high, and there is in many places a flat platform in front of the dune known as the berm. The dunes behind the foredune are lower and less well defined

Jan 1, 1949

By C. W. Allen, L. C. Moore

THE Mather mine, of the Negaunee Mine Co., is within the limits of the City of Ishpeming, on the Marquette iron- range in Michigan's Upper Peninsula. It is named for William G. Mather, who has served as President, and Chairman of the Board, of The Cleveland-Cliffs Iron Co. for well over 50 years. The property comprises nearly the square mile of section 2, T.47 N. R.27 W., which, except for 20 acres in the northeast corner, was leased by The Cleveland-Cliffs Iron Co. to the Negaunee company. The latter is a partnership of Cleveland-Cliffs and the Bethlehem Steel Co., organized to equip the property, retaining Cliffs in charge as operator. Shipments of ore from this area are mainly through Marquette, which is 16 miles to the northeast on Lake Superior, or through Escanaba, a Lake Michigan port, 65 miles to the south. Cleveland-Cliffs, in 1943, operated 12 mines in the Lake Superior district, with shipments of 6,635,576 tons for the year. GEOLOGY The north footwall of the Marquette Range synclinorium outcrops near the north line of sec. 2, the iron formation dipping to the south at an angle of about 40º. The south side of the trough reappears at a distance of 4 ½ miles on sec. 26 and the surface geology between shows iron formation or intrusive diorites. The latter are harder than most phases of the iron formation and, as a result of glacial action, appear as buttes or low-lying hills. The general elevation of sec. 2 is about 1450 ft. above sea level, or 850ft. above Lake Superior, and the higher diorite outcroppings about 1600 ft. above sea level. The geological structure has been complicated by a series of major and minor faults, one of which may be illustrated by the diorite sheet, which tilts south with the iron formation in the north half of the section and then reappears near the center to repeat this sequence. Sectionally the geological series includes a nearly eroded capping of Goodrich quartzite followed by the considerable thickness of Negaunee iron formation, which is cut by intrusive dikes or diorite sheets, and underlain by the Siamo slates grading into quartzites. The ore deposits occur mainly in troughs formed by the intersection of impervious dikes and the footwall slate, but include locally enriched lenses or bands in the iron formation and also interbedded with the Siamo slate. The ore is a soft red hematite with an indicated dried analysis from the surface drilling to date of 61.50 per cent Fe, 0.134 per cent P, 5.40 per cent Si, 2.87 per cent Al and 0.015 per cent S. EXPLORATION A diamond-drilling campaign started in 1937 actually had its inception in 1917, when a number of shallow test holes were put down for the purpose of locating ore that might be quickly developed and mined

Jan 1, 1945

By E. Clarence Peterson, Rip V. Thompson

ALTHOUGH the metallurgical treatment for the Ophir Hill tailings was developed more than 20 years ago and in the interim a vast amount of experimental work was done with later-developed flotation reagents, it was found necessary to revert to the original oil reagents and their combinations with specific chemical reagents in order to obtain results of economic value. This is of especial interest because in present ore-treatment investigations later-developed flotation reagents are used almost exclusively and the coal-tar derivatives, except in certain patented reagents, are virtually neglected. These coal-tar oils and derivatives still have a definite field of application, especially in the treatment of some oxidized ores when modified sulphidization is desirable. The Ophir Hill tailings deposit is in Ophir Canyon, Tooele County, Utah, about 55 miles southwest of Salt Lake City and 25 miles south of the Tooele smelter of the International Smelting and Refining Co. A road good for trucks leads directly from the Ophir mill to the smelter. TAILINGS These tailings were produced in the old Ophir Hill gravity concentrator previous to 1921. The original mill ore was a heavy lead-zinc-copper-silver-iron sulphide ore formed by limestone replacement. The gangue is a highly siliceous lime. An assay of the original milling ore would approximate 1.0 per cent Cu, 6 to 8 per cent Pb, 6 to 8 per cent Zn, 8 to 12 oz. Ag, 18 to 25 per cent Fe, 2.0 per cent CaO, 20 to 5o per cent insoluble. The gold content was 0.005 oz. or less. Tailing was impounded in a fairly wide area in a canyon about ½ mile below the mill. A number of dirt embankments were thrown up to form settling ponds and the tailing was allowed to flow through them in series. Coarser sand deposited at the upper end of the ponds and the finer slimes settled gradually as they passed through the successive settling ponds. As soon as the coarser tailings filled a pond, the tailings were by-passed to the next pond and teams and scrapers were used to haul the deposited sand onto the banks to make them higher. The final dump was approximately 2500 ft. long and 250 ft. wide at the bottoms, with banks sloping up at 45°. The coarser sands predominated at the upper ends and sides of the ponds while the proportion of slimes increased steadily at the lower ends. The lower end of the pond contained over 50,000 tons of slime tailings, 90 per cent of which passed through a 200mesh screen. SAMPLING The entire tailings deposit was sampled by drilling vertical holes so placed as to give data concerning size segregation and the contour of the underlying ground as well as to secure an assay sample. Different types of auger and post-hole drills were tried. None was found satisfactory because the stratified layers of

Jan 1, 1940

By S. D. Thompson

An AIME transaction by P.L. Allsman (1960), "Analysis of Explosive Action in Breaking Rock," contains many useful concepts applicable to blast design. Of special interest was the derivation of a heave blasting burden formula, which is important in establishing the maximum burden. Unfortunately, its derivation contains a fundamental error and then a compensating one. This formula was: [bImpulse _P d At max =nwuwu where: bmax = maximum burden in m (ft). P= average detonation pressure in N/m2 (lb per ft2). A= duration of the average detonation pressure in sec. n= 3.1416. w= specific weight of rock in N/m3 (lb per ft3). u= minimum velocity that must be imparted to the rock in m/sec (ft per sec). d= borehole diameter in m (ft).] The derivation used the impulse-momentum principle, with a 0.3 m thick (1 ft thick) radius of rock mass being acted on by an explosive impulse. However, the rock weight was not converted to mass by dividing by the gravitational constant. This mistake can be verified by checking the units in the formula, which resolve into m1/2-sec instead of meters. Adding the gravitational constant corrects this: [P d Atbmax =gu g = gravitational constant equal to 9.81 m/sect (32.2 ft per sec2).] If the minimum velocity is now taken as 0.3 m/sec (1 ft per sec), as was recommended, excessively large burdens result. Any appropriate rock velocity should be capable of throwing the rock mass a minimum distance so that the swell needed for breakage can occur. Unless the burden is extremely small and the bench height is very high, it is unlikely that a velocity of only 0.3 m/sec (1 ft per sec) will be sufficient. A review of the literature indicates that average rock velocities observed by camera studies typically range from 15 to 30 m/sec (50 to 100 ft per sec) (duPont deNemours and Co., 1977; Tansey, 1979). On this basis, a minimum rock velocity of about 15 m/sec (49 ft per sec) would be expected and not 0.3 m/sec (1 ft per see). When a velocity of 15 m/sec (49 ft per sec) is inserted into the corrected formula, the results approximate those of the original formula with a velocity of 0.3 m/sec (1 ft per sec). The errors were approximately self-compensating [(9 = 1.24)]. ? References Allsman, P.L., 1960, "Analysis of Explosive Action in Breaking Rock," Transactions, AIME, Vol. 217, pp. 475-476. E. I. duPont deNemours and Co., 1977, Blasters' Handbook, 175th Anniversary Edition, Dupont, Wilmington, DE, pp. 233. Tansey, D.O., 1979, "The DuPont Sequential Blasting System," CIM Bulletin, Vol. 72, July, p. 80. Thompson, S.D., 1981, "Critical Review and Revision of Surface Blasting Practice," MS thesis, West Virginia University, pp. 308-316.

Jan 1, 1986

By Frank A. Herald

Through the generous cooperation of the authors of the papers in this chapter, a great wealth of fundamental data is being made available. The same plan of securing and submitting data will be carried forward next year, with the hope of making a nearer approach to complete presentation of the data contemplated in the plan. In order to conserve space, we are printing below such footnotes as have general application to Table 1 in the papers in this chapter: Footnotes to Column Headings Table I In areas where both oil and gas are produced, unless gas is marketed outside the field, such areas are included in column headed "Oil." Manufacture of casinghead gasoline and carbon black is interpreted as outside marketing of gas. Production per acre is determined by dividing into the number of barrels of oil the sum of the number of acres assigned to "Oil" plus such number of acres of the total assigned to "Oil and gas" as represents the portion thereof occupied by oil. Wells producing both oil and gas are classified as "Poducing oil only" unless gas from them is marketed off the lease. W. water; G. gas; A, air. Bottom-hole pressures are preceded by "e." All other figures represent pressures at casinghead with well closed. P, paraffin; A, asphalt; M, mixed. 0 Cam, Cambrian; Ord, Ordovician; Sil, Silurian; Dev, Devonian; Mis, Mississippian; MisL, Lower Mississippian; MisU, Upper Mississippian: Pen. Pennsylvanian; Per. Permian; Tri, Triassic; Jur. Jurassic; CreL, Lower Cretaceous; CreU. Upper Cretaceous; Eoc, Eocene; Olig, Oligocene; Mio. Miocene; Pli. Pliocene. 6, sandstone: SH, sandstone, shaly; Ss, soft sand; H, shale; L, limestone; LS, limestone. sandy; C, chalk; A, anhydrite; D, dolomite; Da. arkosic dolomite; GW, granite wash; P, serpentine. Figures are entered only for fields where the reservoir rock is of pore type. Figures represent, ratio of pore space to total volume of net reservoir rock expressed in per cent. "Par" indicates that the reservoir rock is of pore type but said ratio is not known by the author. "Cav" indicates that the reservoir rock is of cavernous type; "Fis," fissure type. A, anticline; AF, anticline with faulting as important feature; Af, anticline with faulting as minor feature; AM, accumulation due to both anticlinal and monoclinal structure; H, strata are horizontal or near horizontal; MF, monocline-fault; MU, monocline-unconformity; ML, monocline-lens; MC, monocline with accumulation due to change in character of stratum; MI, monocline with accumulation against igneous barrier; MUP, monocline with accumulation due to sealing at outcrop by asphalt; D, dome; Ds, salt dome; T, terrace; TF, terrace with faulting as important feature; N, nose; 9, syncline. Information will be found in text as indicated by symbols: A, name of author, other than above. who has compiled the data on the particular field; C, chemical treatment of wells; G, gas-oil ratios; P, proration; U, unit operation; R, references; W, water; 0. other information.

Jan 1, 1934

By Benjamin L. Miller

The essential differences expressed by the different speakers participating in this symposium concern merely the relative emphasis placed on the subjects that are commonly included under the term "geophysics" and the branches of science that form the basis for investigations in this field. In order to appreciate the present situation it may be profitable to briefly refer to a few historical matters. One can find almost countless descriptions of geological phenomena long antedating the introduction of the title of "geology," which has been credited to Richard de Bury in the fourteenth century. Interpretations, when they were offered, were generally pure speculation. Only toward the close of the eighteenth century do we find theories developed as the result of observations and tested by additional observations. It is difficult to select and give proper credit to the individual who was particularly responsible for turning geology into a distinctly observational science. william Smith, who has been called the "Father of English Geology," certainly represents the period when observation was the only method used. As he traveled through the British Isles, "sometimes 10,000 miles in a year," he was continually making notes of his observations. Geikie says: "His plain, solid, matter of fact intellect never branched into theory or speculation, but occupied itself wholly in the observation of facts." William Smith, with others of his time, definitely laid firmly the foundations on which modern geology has been built. Field and laboratory observations can no longer be said to constitute the sole basis for geologic contributions but we have not laid aside the methods of Smith and his followers. It is folly to underestimate the fundamental value of the observational part of geology in the present. The objection to purely observational geology is that it is mainly qualitative and not quantitative, general and not specific. No one can deny this charge and probably there are few who do not welcome every method or process whereby we can put aside generalities for definite established values. Physics is the science that has particularly come to the aid of the geologist in this respect. Contributions of PhYsics It is not the intent of the writer to enumerate or to evaluate all of the contributions to geologic advance in the field of. physics. A few only are used for the purpose of illustration, When Clarence King, Director of the United States Geological Exploration of the Fortieth Parallel, invited Ferdinand Zirkel to study 2500 thin sections of rocks collected from the western United States, the use of the microscope came into general use. Zirkel's report was published in 1876. He was not the first to use transmitted light for microscopic rock determination, some work having been done by Henry Clifton Sorby and others some years earlier, but he was the first to put into general use this method. We may well daim that this

Jan 1, 1946

By K. L. Moazed, G. M. Pound

An investigation was made of the deposition of silver from a thermal beam onto tungsten field-emitter tips at 300°K. "Island"-type nuclei were observed to form and grow. The nucleation of silver crystals occurs preferentially on non-close -packed planes of a tungsten tip at a critical volume free-energy change of about —2900 cal per cc. The adatom population which is critical for appreciable nucleation rate of silver crystals is about 0.2 of a monolayer and is essentially independent of beam flux, time, and source temperature. This result is strong evidence that a metastable equilibrium exists between adatoms and critical nuclei, as assumed in the present theory. SOME of the more significant studies of nucleation in deposition of metals from vapor beams have been conducted by measuring the thermal beam flux which is critical for appreciable rate of nucleation on a substrate surface held at a given temperature.'2 The observed critical supersaturations may be described in terms of Eq. [7] which was derived3'3a on the model of an adsorption, surface migration, and statistical fluctuation mechanism. However there usually made with a low-power optical microscope, a fairly insensitive method of detection. The object of the present study was to overcome some of these difficulties by measuring the critical supersaturation for condensation of a thermal beam of silver onto a tungsten field-emitter tip. Such a tip may be cleaned by electrically heating it to a high temperature in situ, and the high vacuum obtainable in a field-emission tube (10-10 torr) precludes adsorption of residual gases for convenient periods of time. Furthermore, the degree of cleanliness, the orientation, and the state of imperfection of the tip may be ascertained from the field-emission pattern. Detailed explanations of theoretical considerations and experimental procedures relating to the field-emission microscope may be found in a number of excellent review articles12'13 and thus only a brief description will be given here. The electronic work function of a metal is defined as the energy that an electron needs to escape from the potential field of the solid. By applying a large field between the surface of the solid and a suitable collector, it is possible to free the electrons by the tunnel effect. Fields of approximately 30 million v per cm are needed to produce this effect, and such fields are obtained in practice by using microscopic surfaces of high curvature (tips). Because the work function of a metal is a function of surface orientation, the emission from the various planes is different, and thus it is possible to obtain a representation of the surface in the emission microscope. In general, the work function is higher for the more densely packed planes. Fig. 1 shows a pattern for "clean" tungsten in which the central dark region represents the (110)

Jan 1, 1964

By Benjamin L. Miller

The essential differences expressed by the different speakers participating in this symposium concern merely the relative emphasis placed on the subjects that are commonly included under the term "geophysics" and the branches of science that form the basis for investigations in this field. In order to appreciate the present situation it may be profitable to briefly refer to a few historical matters. One can find almost countless descriptions of geological phenomena long antedating the introduction of the title of "geology," which has been credited to Richard de Bury in the fourteenth century. Interpretations, when they were offered, were generally pure speculation. Only toward the close of the eighteenth century do we find theories developed as the result of observations and tested by additional observations. It is difficult to select and give proper credit to the individual who was particularly responsible for turning geology into a distinctly observational science. william Smith, who has been called the "Father of English Geology," certainly represents the period when observation was the only method used. As he traveled through the British Isles, "sometimes 10,000 miles in a year," he was continually making notes of his observations. Geikie says: "His plain, solid, matter of fact intellect never branched into theory or speculation, but occupied itself wholly in the observation of facts." William Smith, with others of his time, definitely laid firmly the foundations on which modern geology has been built. Field and laboratory observations can no longer be said to constitute the sole basis for geologic contributions but we have not laid aside the methods of Smith and his followers. It is folly to underestimate the fundamental value of the observational part of geology in the present. The objection to purely observational geology is that it is mainly qualitative and not quantitative, general and not specific. No one can deny this charge and probably there are few who do not welcome every method or process whereby we can put aside generalities for definite established values. Physics is the science that has particularly come to the aid of the geologist in this respect. Contributions of PhYsics It is not the intent of the writer to enumerate or to evaluate all of the contributions to geologic advance in the field of. physics. A few only are used for the purpose of illustration, When Clarence King, Director of the United States Geological Exploration of the Fortieth Parallel, invited Ferdinand Zirkel to study 2500 thin sections of rocks collected from the western United States, the use of the microscope came into general use. Zirkel's report was published in 1876. He was not the first to use transmitted light for microscopic rock determination, some work having been done by Henry Clifton Sorby and others some years earlier, but he was the first to put into general use this method. We may well daim that this

Jan 1, 1946

The Climax Molybdenum Company' s newest operation is the Henderson project, which is located on the east side of the Continental Divide. Ore reserves are estimated at more than 300 million tons at a grade of 0.49% MoS2. For mining the ore a modified panel caving system is used. The ore is transported to the Henderson mill on the west side of the Continental Divide on a 42 in. (1.07 m) gauge railroad through 9.6 miles (15.4 km) of tunnel and 4. 8 miles (7.7 km) of surface track, a total distance of 14.4 miles (23. 2 km). Each train consists of 30 ore cars with capacity of 22 st (20 mt) of ore or 660 st (599 mt) per train. The unmanned trains operate completely automatically. At the 54 in. by 84 in. primary gyratory crusher, the bottom dump ore cars pass over a dump scroll to discharge at a maximum rate of 100 st (91 mt) per minute. Dumped ore falls onto a rock box before passing over a 17 ft long by 46 ft wide (5. 2 m by 14 m) grizzly set at a 40° angle with bar spacings of 7 ½ and 8 ½ in. (191 mm and 216 mm) openings. An estimated 30 to 50% of the ore (which at times is wet and sticky) passes through the grizzly. The operators report that a shallower angle on the grizzly, perhaps 35º to 37º, would have been sufficient and would have prevented impact on the back of the crusher pocket by large boulders. This pocket as well as the crushed ore pocket under the crusher is lined with AR plate. The accompanying drawings show a "future splitter" and the operators are planning the installation of this unit to prevent impact and subsequent damage to the crusher spider. Crushed ore at an 8 to 9 in. (203 mm to 229 mm) size joins the grizzly undersize in the pocket beneath the crusher. This pocket is sized at 660 live st (599 mt) so that it will accept an entire trainload of ore. Crushed ore is removed from the pocket by a four-speed, 84 in. (2. 1 m) apron feeder operating at 9.6 to 29. 3 fpm (2.9 to 8.9 mpm). A 60 in. (1.5 m) takeaway conveyor operating at 480 fpm (146 mpm) delivers the crushed ore to a 58,000 st live and 193,000 st total (52,600 and 175, 100 mt) open stockpile under an A -frame supported tripper gallery. Impact idlers on the takeaway conveyor under the apron feeder discharge are mounted on wood blocks for a cushioning effect and ripped belt detecting bars are located behind each impact idler. The conveyor tunnel is of corrugated and galvanized steel construction rather than concrete. The concrete crusher enclosure is circular in design from its lowest level at elevation minus 110 ft 4 in. (minus 33. 6 m) to elevation

Jan 1, 1978

By Orville R. Lyons

THE continuous vacuum filter, whether it be a vertical or horizontal disk, inside or outside drum, when properly applied is a very effective device for dewatering fine solids. Because of the number of variables that affect its performance, however, it is not possible to obtain consistently maximum moisture reduction in an operating plant. This paper presents a method for determining the average cake moisture and the variations in cake moisture to be anticipated when dewatering fine solids by continuous vacuum filters under normal operating conditions. Previous investigators1,2 have found that certain factors influence filter performance, drum or disk diameter, speed of rotation, percentage of immersion, and the percentage of solids in the feed influence capacity. Blinding of the filter cloth reduces effective vacuum, produces a wetter cake, and may decrease capacity. Reduced vacuum or improper adjustment between vacuum and blowing portions of the cycle will produce a wetter cake and also may decrease capacity. Widely fluctuating feed tonnages will adversely affect cake moisture and capacity. Flocculation, when properly applied, increases capacity and reduces cake moisture. Without flocculation, the slimes are the first particles sucked to the filter medium, which becomes partially blinded in consequence. With flocculation, the flocs act as coarse particles and the filter medium is not blinded. Overflocculated pulps, although filtering well, may yield wet cakes. Average Particle Size and Cake Moisture A method for predetermining the surface moisture content of coal filter cakes was published in 1949; but this method could not be applied to coals deficient in —200 mesh material or to fine mineral concentrates. Test data obtained for geared-weight types of vibrating screens4 and for centrifuges5 used to de-water coal provided definite correlations between the average particle size of a dewatered cake and the surface moisture content of the cake. It was thought that this same method of correlation should be applicable to filters, whether dewatering fine coal or fine mineral concentrates. To develop a correlation or correlations between average size of cake and cake moisture, the author collected data for filtration operations from as many sources as possible. In a considerable number of instances the information was provided by plant preparation engineers,"-" a few of the tests were on a laboratory scale: and the remainder of the data was obtained from published articles.10-17 Table I contains size-consist and miscellaneous data for coal filter cakes, and Table II contains the same data for mineral concentrate filter cakes. Fig. 1 shows the relationships existing between the average particle size of the cake and cake moisture (surface moisture for coal and total moisture for minerals) when dewatering fine solids by a variety of makes and types of filters. Average particle size is calculated by averaging the linear openings of the various pairs of screens used in the screening test, weighted in accordance with the percentages of material in the various fractions.

Jan 1, 1952

By B. L. Averbach, M. Cohen, G. P. Conard

IT has been frequently observed that, when metal crystals are bent and annealed or when they are bent at elevated temperatures, the asterism of the Laue spots is split discontinuously into tiny intensity maxima. This finding indicates that segmented crystallites or subgrains are produced, which are relatively undistorted within themselves but which differ slightly in orientation from their neighbors. The following viewpoints have been put forward concerning the nature of this segmentation process: 1—Crussard' has described the phenomenon as "re-crystallization in situ." According to this mechanism, the deformed lattice recrystallizes on heating into an aggregate of comparatively strain-free subgrains separated from one another by low-angle boundaries and having nearly the same orientation as the original crystal. This process differs from the classical type of recrystallization in that the latter involves the formation of grains having quite different orientations from that of the mother crystal. 2—A similar but more detailed picture has been advanced by Cahn' who adopted the term "polygonization." In this interpretation, the plastic bending of lattice planes results in an excess of dislocations of one sign, but at suitable temperatures these dislocations migrate along slip planes and collect in localized regions to form an array of low-angle boundaries. Concurrently, the lattice segments between the boundaries lose their curvature and elastic strain. 3—The "cell formation" concept of Wood and co-workers: unlike the two hypotheses cited, postulates that the segmentation of the lattice is basically a mode of deformation and is not an annealing phenomenon. Cell formation appears to compete more effectively with respect to the normal slip process as the deformation temperature is increased and as the strain rate is decreased. The present work was performed on 3.2 mm diameter 99.99' pct Zn single crystals, grown from the melt in a gradient furnace. The major impurity was 0.003 pct Fe. The crystal orientations ranged from those with basal plane parallel to the rod axis to those with the basal plane almost perpendicular to the rod axis. The specimens were bent on templates to effective radii varying from 14.2 to 1.3 cm at the temperatures from —196" to 100°C. In each case, the axis of bending was parallel to the basal plane. Subsequent annealing was carried out at temperatures from —196" to 400°C. Back-reflection Laue pictures were taken on the convex surface of the bent specimens, before and after annealing. This procedure was found to yield better resolution of the detail in the diffraction spots than did the previously used Laue transmission technique. Some X-ray pictures of rods bent at —196" and —78°C were taken at these respective temperatures without intermediate warming to room temperature. In addition, bent crystals were acid cut" parallel to the basal plane, and double-crystal spectrometer rocking-curves were obtained from the etched (0001) face before and after increment an-

Jan 1, 1954

By A. J. Hatch

Recent disclosures concerning strengthening of anisotropic sheet materials under biaxial stresses are reviewed. This biaxial strengthening has been termed "texture hardening" by Backofen and is related to the normal anisotropy parameter, R. Measurements of R made on three annealed titanium alloys indicate a Ti-4Al alloy will have the greatest potential for texture hardening, followed in order by Ti-5Al-2.5Sn and Ti-6Al-4V. Relative to sheet texture, a review of the deformation mechanisms in titanium alloys would indicate that a preferred orientation for "texture hardening" is where the (0001) pole is normal to the sheet plane. This was confirmed by determination oj (0001) pole figures for the above three alloys. High R values are related to pole figures with (0001) normal to the sheet plane, whereas low R values are related to pole figures with (0001) split in the transverse direction from the sheet normal. PUBLISHED work by Backofen et al. 1 and Hosford and Backofen2 based on hill's' mathematical theory of yielding in anisotropic metals has indicated that significant strength advantages under biaxial stresses are possible in hcp alloys, provided an ideal (0001) [1010] sheet texture exists. This tendency to strengthen under biaxial stresses has been termed "texture hardening".1 It can be quantita- tively characterized by a strain-ratio parameter, R, where R may be determined from the ratio of natural width strain to natural thickness strain as measured on a uniaxial test specimen cut parallel to the rolling direction. If R is greater than 1.0, then strengthening under biaxial tension would be predicted. Considering the a titanium alloys which have an hcp crystal structure, Williams and Eppelsheimer4 have reported that commercial-purity grades deviate from the ideal (0001) sheet texture mainly in an approximate 30-deg rotation of the basal plane, toward the transverse sheet direction. However, McHargue et a1.5 have shown that the angle of rotation of the basal plane is sensitive to alloy content. In particular, a titanium alloy with 3.8 pct Al was reported to have the ideal (0001) [1010] texture after cold rolling. Additionally, Backofen et a1.1 using plane-strain compression tests have reported R values greater than 5.0 for the commercial 0 alloy Ti-5A1-2.Sn (110-AT). In view of these findings, a program was initiated to further determine the potential of commercial Ti-5A1-2.5Sn and an experimental Ti-4A1 alloy with respect to "texture hardening". Also, because of its wide commercial use, Ti-6A1-4V was included in the investigation. BIAXIAL-STRESS THEORY FOR ANISOTROPIC MATERIALS Backofen ef al.,1 based on the mathematical theory of Hi11,3 has introduced the concept of "texture hardening". In this work, it was shown that possi-

Jan 1, 1965

By C. B. Dudley

bas shown us that the railroads of this country can save several milt liohs a par by adopting uniform rail sections, and as unfortunately for him, he cannot patent his idea, it only remains for the railroads to adopt it, and to thank him for his payer. Dr. C. B. Dudley, Altoona, Pa. : 111 rising to close this interestin~ discussion, I want, in the first place, to thank every one who has contributed to it for his full and open criticism. The work tvhich has been done on steel rails, and which has been diwu&e,l here Juring thee two days, was not done to establish any pet theories, nor to make out that any person was great or any person small, but with a sincere desire to get at what is the truth in regard to the wedring capacity of steel rails. There are enormous commercial coneiderations invoIved in this question, and, as I look at the matter, the more honest criticism and fair discussion there is, the Inore likely it is that the truth will appear. Ad first I would like to say that it seems to me very little has been said here upon the main conclusion of the paper, namely, that the softer rails give the better wear. All sorts of side issues have been discussed; but this poiat, which is really the principal one at issue, has been largely ignored, aid I cannot But feel that it still remains unshaken. Witb regard to ohemists end chemical work, there has been considerable said tending to throw discredib on chemists and their work; and while I believe that there have been in the past, are now, and may be in the futnre, a good many poor chemical analyses made, X also believe that chemists are, as a rule, as honest and competent as gentlemen who belong to other professiomc. There are chemisb who are chemists, and who are not chemists. The determination of -manganese has bee* called in question. Now I think the chemist at almost every steel works in the country will tell you that, in his experience, the manganese diffe1.s in different parts of the same ingot. Mr. T. T. Morrell, chemist of the Camhria Iron Company, whom I believe to be s thoroughly competent and hone6t chemist, tells me that he has often found different amounts of manganese in different parts of the same ingot. Come with me to Altoona, and I will take you into the machine shop where steel is king cut aud shaped, and I will show you that it is often necessary to stop the lathe or planer and take a cold chisel to cut oat a hard spot, or else ntn the risk of breaking the tool. This hard spot is simply a pttrt of the syiegel which was not thoraughiy mixed with the ma

Jan 1, 1881

By Corliss R. Kinney

SINCE the first atomic bomb exploded over Japan, a great deal of speculation has been published about the use of atomic energy instead of coal for the production of power. Atomic energy, in time, may displace coal for this purpose, but atomic energy will not displace coal in supplying chemical raw materials to the rapidly expanding carbon-chemicals market. Modern civilization demands large quantities of carbon compounds and the logical source of many of these is coal. Consequently, many progressive operators are considering the possibilities of the utilization of coal as a chemical raw material as never before. Furthermore, the demand for clean, smokeless, and ashless fuels will continue to increase and the only way to handle coal under those conditions is to take it apart, just as crude petroleum is taken apart. One can readily imagine where the petroleum industry would be now if it had insisted on selling customers only crude oil, perhaps emulsified with a little salt water to correspond to the moisture and mineral matter in raw coal. The time seems to be coming at an accelerated pace when mine operators will find that competing for a highly selective fuel market by producing a larger tonnage at smaller cost will be less profitable than to increase the value of a smaller tonnage many fold by producing something more valuable to industry and civilization than raw coal. For example, about 750,000 tons of carbon black selling for $50 to $60 per ton was produced in the United States in 1945. This tonnage is insignificant compared with the total production of coal in the United States, but a very tidy tonnage, together with the coal necessary to operate the process, for any mine operator fortunate enough to obtain a method of producing a better carbon black from coal. From the point of view of tonnage, the manufacture of coke of various kinds and its by-products is at present the most important source of carbon chemicals from coal. Nearly 20 per cent of the coal mined in this country is used for this purpose. A large proportion of the coke is used for the production of iron and steel, but even in this operation a considerable part of the coke is used for a chemical purpose; that is, the reduction of the ore to metallic iron. In addition, large quantities of coke are used in manufacturing many important products that find their way into the market. POSSIBILITIES OF ACETYLENE One of the important chemicals manufactured from coke is calcium carbide, from which many products are made. One of these is acetylene. This hydrocarbon can also be manufactured from natural gas or from waste oil-refinery gas and' these industries will probably offer competition for the manufacture of acetylene. Coke-oven gas can be used for making acetylene and should receive consideration

Jan 1, 1946

By Benjamin L. Miller

THE essential differences expressed by the different speakers participating in this symposium concern merely the relative emphasis placed on the subjects that are commonly included under the term "geophysics" and the branches of science that form the basis for investigations in this field. In order to appreciate the present situation it may be profitable to briefly refer to a few historical matters. One can find almost countless descriptions of geological phenomena long antedating the introduction of the title of "geology," which has been credited to Richard de Bury in the fourteenth century. Interpretations, when they were offered, were generally pure speculation. Only toward the close of the eighteenth century do we find theories developed as the result of observations and tested by additional observations. It is difficult to select and give proper credit to the individual who was particularly responsible for turning geology into a distinctly observational science. William Smith, who has been called the "Father of English Geology," certainly represents the period when observation was the only method used. As he traveled through the British Isles, "sometimes 10,000 miles in a year," he was continually making notes of his observations. Geikie says: "His plain, solid, matter of fact intellect never branched into theory or speculation, but occupied itself wholly in the observation of facts." William Smith, with others of his time, definitely laid firmly the foundations on which modern geology has been built. Field and laboratory observations can no longer be said to constitute the sole basis for geologic contributions but we have not laid aside the methods of Smith and his followers. It is folly to underestimate the fundamental value of the observational part of geology in the present. The objection to purely observational geology is that it is mainly qualitative and not quantitative, general and not specific. No one can deny this charge and probably there are few who do not welcome every method or process whereby we can put aside generalities for definite established values. Physics is the science that has particularly come to the aid of the geologist in this respect. CONTRIBUTIONS OF PHYSICS It is not the intent of the writer to enumerate or to evaluate all of the contributions to geologic advance in the field of physics. A few only are used for the purpose of illustration. When Clarence King, Director of the United States Geological Exploration of the Fortieth Parallel, invited Ferdinand Zirkel to study 2500 thin sections of rocks collected from the western United States, the use of the microscope came into general use. Zirkel's report was published in 1876. He was not the first to use transmitted light for microscopic rock determination, some work having been done by Henry Clifton Sorby and others some years earlier, but he was the first to put into general use this method. We may well claim that this

Jan 1, 1941

By C. M. Marquardt

Tramp iron and steel moving on a conveyor belt cause small currents to be generated in a coil situated in a strong magnetic field, which are converted to an alternating current and are amplified. The output voltage from the amplifier fires a thyratron with a relay in its anode circuit, which actuates a howler and simultaneously drops a spot of marker material on the belt. THE problem of tramp iron removal from moving ore belts is a long standing one. When heavy ore streams are carried on a belt, magnetic pulleys and strong surface magnets fail to remove tramp buried in the ore stream. Tramp iron buried in the ore stream cannot be pulled from the bed by surface magnets and is carried past the magnetic pulley by the falling ore stream. With the increased use of detachable bits the problem of the detection and removal of tramp has become more necessary and difficult. Several types of tramp detectors have been developed. It would serve no practical purpose here to review exhaustively the literature on the subject. Methods of tramp detection used are: (1) The magnetic method, wherein the small current generated by the magnetized tramp passing a Coil is used. (2) The unbalanced oscillator method wherein the tank circuit of a stable radio- or audio-frequency oscillator is unbalanced causing a change of frequency or a change in plate current due to changes in eddy currents, hysteresis, or dielectric because of the presence of tramp. (3) The bridge methods wherein the impedance of one leg of an alternating current inductive bridge is changed due to the presence of conducting tramp. Each of these methods of tramp detection has its field of usefulness. The second and third methods are excellent for oxide iron ores, coal, sand and gravel, grain, etc. However, these latter methods are not suitable for use on ores that contain rich conducting sulphides, since a large piece of pyrite or galena will cause the same detector response as a piece of tramp iron. At the Caselton, Nevada, plant of the Combined Metals Reduction Co., sulphide ores are treated; therefore, it was necessary that a tramp detector operating on only the magnetic properties of the tramp iron be used. Tramp iron detectors of this type operate on the principle that if a piece of tramp iron moves near a coil in a high intensity, steady magnetic field, the presence of the moving tramp iron causes the magnetic flux lines through the coil to change. This induces a mall current in the Coil. In series with the Coil is generally placed a relay sensitive to currents of 1 to 3 microamp. When the tramp iron passes near the coil the flux linkages change, causing this very sensitive relay to actuate. Since the contacts of such a relay are very small it must actuate a second relay capable of breaking a larger current

Jan 1, 1951

By R. A. Nadler and

Specimens of Ti-155A (Ti-5Al-1.3Fe-1.3Cr-1.2Mo), Ti-6Al-4V and Ti-4Al-3Mo-1V were hydrogenated, aged to high strength levels, and subjected to notched stress-rupture tests and tensile tests at two strain rates. Both Ti-6Al-4V and Ti-155A were relatively unaffected by hydrogen in amounts exceeding those found in commercially -produced material. Inconsistencies in the data and a relatively low initial level of ductility prevented an accurate determination of the hydrogen tolerance for aged Ti-4Al-3Mo-1V, but there was no evidence that this alloy was any more susceptible to hydrogen embrittlement than Ti-155A and Ti-6A1-4V. THE metallurgical literature has been considerably enriched in the past five years by the publication of the results of many investigations which were concerned with the effects of hydrogen on titanium and its alloys. Although it is not the authors' intention to provide a complete literature survey of this vast field, it is worthwhile to summarize briefly some of the important factors which influence the embrittling phenomenon in a - B alloys. Some of the influencing factors are those of strain rate, temperature, and composition. Hydrogen embrittlement in a - B titanium alloys is now believed to be a strain-induced phenomenon, and whether or not embrittlement occurs at high hydrogen levels depends largely upon whether sufficient time is available for hydride precipitation. This condition is fulfilled by tensile testing at very slow strain rates or by rupture testing smooth or, preferably, notched specimens over relatively long periods. Conveniently, maximum embrittlement occurs at or near room temperature. The presence B - stabilizing elements, in amounts sufficiently small to prevent an all -B or nearly all -P condition, promotes hydrogen embrittlement and this tendency is believed to be related to the amount of a - B interfacial area present. Aluminum, by increasing the solubility of hydrogen in A titanium, greatly reduces the danger of hydrogen embrittlement, while oxygen has been shown to have detrimental effects.' The preceding discussion is based on experimental work performed on annealed a - P alloys. This early work has shown that annealed Ti-6A1-4V and Ti-155A are relatively insensitive to the embrittling effects of hydrogen.' Although no work has been reported on annealed Ti-4A1-3Mo-lV, the alloy would be expected to exhibit somewhat the same insensitiv-ity as Ti-155A. In sharp contrast to the voluminous literature on annealed titanium alloys is the paucity of reported investigations on materials receiving commercial heat-treatment cycles. To date, the most notable contributions in this field have arisen from two separate investigations on Ti-3Mn-1Fe-1Cr-1V-lMo, the so-called 3Mn comple~. These investigations

Jan 1, 1961

By Corliss R. Kinney

Since the first atomic bomb exploded over Japan, a great deal of speculation has been published about the use of atomic energy instead of coal for the production of power. Atomic energy, in time, may displace coal for this purpose, but atomic energy will not displace coal in supplying chemical raw materials to the rapidly expanding carbon-chemicals market. Modern civilization demands large quantities of carbon compounds and the logical source of many of these is coal. Consequently, many progressive operators are considering the possibilities of the utilization of coal as a chemical raw material as never before. Furthermore, the demand for clean, smokeless, and ashless fuels will continue to increase and the only way to handle coal under those conditions is to take it apart, just as crude petroleum is taken apart. One can readily imagine where the petroleum industry would be now if it had insisted on selling customers only crude oil, perhaps emulsified with a little salt water to correspond to the moisture and mineral matter in raw coal. The time seems to be coming at an accelerated Dace when mine operators will find that competing for a highly selective fuel market by producing a larger tonnage at smaller cost will be less profitable than to increase the value of a smaller tonnage many fold by producing something more valuable to industry and civilization than raw coal. For example, about 750,000 tons of carbon black selling for $50 to $60 per ton was produced in the United States in 1945. This tonnage is insignificant compared with the total production of coal in the United States, but a very tidy tonnage, together with the coal necessary to operate the process, for any mine operator fortunate enough to obtain a method of producing a better carbon black from coal. From the point of view of tonnage, the manufacture of coke of various kinds and its by-products is at present the most important source of carbon chemicals from coal. Nearly 20 per cent of the coal mined in this country is used for this purpose. A large proportion of the coke is used for the production of iron and steel, but even in this operation a considerable part of the coke is used for a chemical purpose; that is, the reduction of the ore to metallic iron. In addition, large quantities of coke are used in manufacturing many important products that find their way into the market. Possibilities of Acetylene One of the important chemicals manufactured from coke is calcium carbide, from which many products are made. One of these is acetylene. This hydrocarbon can also be manufactured from natural gas or from waste oil-refinery gas and these industries will probably offer competition for the manufacture of acetylene. Coke-oven gas can be used for making acetylene and should receive consideration

Jan 1, 1947