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"Copper was first made in Butte by the use of iron for its precipitation from mine water in 1890. In consequence of a fire breaking out in the St. Lawrence mine of the Anaconda Copper Mining Company in November, 1889, a large quantity of water was poured into the workings, with the intention of flooding the mine and extinguishing the fire. This proved to be impracticable, but this water, on being pumped to the surface, was found to be high in copper sulphate,—tradition says 75/100 of 1 per cent. The Anaconda Copper Mining Company gave Wm. Ledford a lease on this water. He first (lug holes into the ground, filled them with scrap iron and allowed the water to flow through them. Later he built an open-top flume which he partially filled with iron and passed the water through the by the iron precipitation method. An assay in- the year 1890 from Gagnon mine water, showed .0016 per cent or 28 lbs. copper per day. The mine was then opened to the 1,000 level.None of the mine waters encountered in the solid rock in the mines of Butte contained copper in sufficient quantity to produce the metal profitably by the iron precipitation method. An assay in the year 1890 from Gagnon mine water, showed .0016 per cent or 28 lbs. copper per day. The mine was then opened to the 1,000 level."

Jan 1, 1913

By J. J. Brown

Wilkes-Barre Meeting, Julie, runs., THE ore-hearth was the earliest type of furnace used in smelting Mississippi Valley lead-ores, which are very pure, and low in silver-content. The first smelters made no attempts to recover lead from the smoke; and since about 15 per cent. of the lead -in the charge escaped in this manner, early practice with the hearth was decidedly wasteful. At most of the large smelting-plants blast-furnaces with auxiliary roasters were substituted for the hearths long ago. But, upon the introduction of the Lewis and Bartlett bag-process for collecting fume, the ore-hearth was used by companies engaged in the manufacture -of pigments, simply on account of the large percentage of fume made by it. In fact, the extraction of lead was kept down by the use of hot blast and other devices. During recent years, however, several smelting companies have realized that the preliminary roasting of galena for the blast-furnace is not economical, and have, therefore, replaced the roasting-furnace with a modification. of the old Scotch hearth, in which a large percentage of the lead in a charge is recovered directly as pig-lead, while the remainder passes partly into fume and partly into slag low enough in sulphur to be charged into the blast-furnace without further treatment. The results obtained have proved so satisfactory, both As to recovery and operating-expense, that one eminent metallurgist has predicted the universal use of the ore-hearth on non-argentiferous ores. The-ore-hearth, thus employed as an adjunct to a blast-furnace plant, is rather a desulphurizer than a smelting-furnace proper,-the chief object being to make a blue slag suitable for the cupola-furnace. Hence, no special care is taken to obtain from it a large lead-extraction. * Head of Department of Ore Dressing and Metallurgy, Oklahoma School of Mines and Metallurgy, Wilburton, Okla.

May 1, 1911

By W. J. PRIESTLEY

WHEN during the war the Navy Department decided to build an armor-plate and gun-forging plant of its own at South Charleston, W. Va., one of the most important units of the equipment proposed was a 14,000 gross ton forging-press to be used for forging, bending, and rectifying battleship armor-plate and making hol¬low forgings for large caliber guns. A press suitable for doing this kind of work was put into operation in the fall of 1921 and was operated successfully on armor-plate and large forgings until the closing down of the ordnance plant following the Limitation of Armament Conference held in Washington, February, 1922. PURPOSE OF THE PRESS There are three methods by which armor-plate can be made, namely, hammering, forging, and rolling the ingot. Each method produces a different result in the mechanical working of the steel. The hammer was eliminated as impractical from an operating standpoint. The first armor-plate made in this country was worked under a hammer at the Bethlehem Steel Co., between the years 1891 and 1893, but was superseded by forging when the large press was completed in 1893. Harry T. Morris of the Bethlehem Steel Co. informs me that the 1.25-ton steam hammer began operations in 1891 and was in operation for about two years. The Carnegie Steel Co. and the Midvale Steel and Ordnance Steel Co. also forged armor-plate. Certain European manufacturers rolled the plates from large slab ingots, after removing the sink-head and giving the body of the ingot a light pass under a hydraulic press. While rolling accomplished more mechanical work on the surface of an armor plate, forging, on the other hand, resulted in a greater amount of work in the interior of the plate. Either type of equipment involved an enormous expendi¬ture, so it was deemed advisable to adopt the method which would make it possible to use the equipment for more than one purpose. Since g large rolling-mill could be used only for the single operation of rolling armor-plate, a press was decided on, for the reason that it might be designed so as to forge armor, as well as bend and rectify it, and also be used in the forging of ingots for large caliber guns, both in the form of hollow forgings and also solid shafts.

Jan 1, 1926

By Charles Clayton

IN connection with certain coöperative work carried on between the Ordnance Department of the U. S. Army, the U. S. Bureau of Mines, and the U. S. Geological Survey during the year 1918, it was the writers' privilege to make metallographic examinations of a great many test bars and other pieces of nickel-steel gun forgings. The material studied came from many different steel plants throughout the country and consisted both of forgings that had been accepted by the Ordnance Department and those that had failed to pass the specified physical tests. In general, these tests require a minimum tensile strength of 95,000 lb. (42,091 kg.), an elastic limit of 65,000 lb. (29,483 kg.), an 18 per cent. elongation, and a 30 per cent. reduction in area. An average chemical composition of the steel studied is 0.38 per cent. carbon and 2.9 per cent. nickel. The steel was of both basic electric and basic open-hearth manufacture. The object of the metallographic work was two-fold: to assist in detecting defects in the steel and, if possible, to suggest remedies for the same; and to obtain as much information as possible in regard to the relation of the microstructure of the metal to its physical properties. The greater part of the investigation was devoted to defective metal that failed to pass the ordnance specifications. Many types and kinds of more or less serious defects thus came under observation, but most of these were due to the attempts by the manufacturer to meet the enormous demand for ordnance steel with more or less inadequate equipment, and were soon remedied. Two defects, the so-called "flakes" or "snowflakes" and a certain "fibrous" or "woody" fracture, were encountered so frequently and were so disastrous to the steel that the greater part of the study was devoted to them. As a result much information as to their nature and their effects

Jan 2, 1919

APPLICATIONS for loan contracts for the exploration, development and mining of strategic and critical metals and minerals are now being accepted by the Department of the Interior. The RFC is authorized and directed by Executive Order 10161 to make such loans but the Secretary of the Interior must pass on the necessity for the loan. Applications should be addressed to James Boyd, acting deputy administrator, Defense Minerals Administration, Department of the Interior, Washington, D.C. rather than to the Field Offices of the Bureau of Mines as was first planned. Application forms are not yet available but it has been learned that data accompanying the application should include the known quantity and grade of reserves, the anticipated rate of production, the equipment, supplies, and man power required for the additional production, etc.

Jan 12, 1950

By R. B. Schluter, M. M. Fine

The Bureau of Mines' Twin Cities Metallurgy Research Center has of late concerned itself with reduction-induration of iron ore. One development provided a flowsheet for the agglomeration of green concentrate pellets in a reducing atmosphere created by a solid reductant external to the agglomerate. The product pellets were well metallized and physically competent. Maximum recommended operating temperature was 2100º F. In these studies, it was observed that unflred iron ore pellets indurated in a bed of anthracite or certain lignite chars frequently acquired exceptional crushing strength. A diagnosis of the phenomenon revealed that sulfur in the fuel was the probable cause. Accordingly, a research program was established to test this premise and to put it to practical use. Gaseous reductants were employed initially because of the ease and accuracy with which they could be metered.

Jan 10, 1969

By T. H. Aldrich

(San Francisco Meeting, October, 1911.) THERE are two conditions generally prevailing upon the earth-those within atmospheric influence, tending towards oxidation, and those away from atmospheric influence, tending towards reduction. Practically all mineral substances from mines of any depth are in a reducing condition. Since the cyanide process, in order to dissolve silver or gold, requires that the prevailing conditions under which it operates shall be oxidizing, and the materials usually acted upon being of a reducing character, it becomes necessary to supply oxygen to the solution carrying the cyanide. This oxygen is usually supplied through the medium of dissolved air in the solution, or through the medium of various chemical compounds, which upon combining with the solution or the ore give off a part of their oxygen. Strange as it may seem, practically all mineral substances are partly soluble in water, especially water carrying alkali or cyanide. The greater the surface exposed and the finer the material is ground, the greater will be the rate of dissolving of the reducing agents from the ore into the cyanide solution. In most cases, if the solution carrying the ore particles is agitated with air, the air will dissolve into the solution faster than will the reducing-agents; but in some cases the reducing-agents will dissolve more rapidly on account of easy solubility or greater surface exposed. It is a dissolving race between the oxygen from the air and the reducing-agents from the ore, and if the reducing-agents predominate, cyanide will not dissolve the gold from the ore. In many cases it will dissolve some of the gold, because in a mass of irregular shape some of the gold particles might be exposed upon the outside surface of a particle of rock;' but if the solution had to penetrate through cracks, the side-walls of which were lined with reducing-agent-

Feb 1, 1912

Payloader The Frank G. Hough Co. has made available another four-wheel drive tractor-shovel. It has a 1 cu-yd bucket with 60 hp Diesel or 54 hp gasoline power optional. The use of large pneumatic tires, same size all around, and drive on all four wheels gives this new Payloader traction to work effectively in sand, mud and snow, and travel on pavements with- [ ] out injuring the surface. Rear wheel steer with power booster plus short wheel base makes it easy to operate and highly maneuverable. Four speeds in both directions insure fast travel speeds for transport and fast operating speeds on shuttle loading or similar operations. Bulldozer blade, crane hook, fork lift and snow plow attachments are available, quickly interchangeable with the bucket to further increase its multi-purpose usefulness. Circle No. 1

Jan 1, 1952

"In the mines producing over 500 tons per day, skips have replaced the old method of hoisting ore by cars run onto cages. In the car and cage method, two men (station tenders) trammed the loaded cars onto the one-deck cage, and as the production increased the one-deck cage was increased to two decks and later to four decks. Landing chairs at the underground stations were necessary in this method and were the cause of many serious accidents by being carelessly left in the shaft by the station-tenders when leaving one station for anotherabove. The labor and time occupied in loading the leaving cages were con¬siderable, and, at times of rapid hoisting, four men were necessary in taking off empty and caging loaded cars. This also required at the surface landing, as many as ten men on a shift to remove the loaded cars and replacing them with empties, and tram the loaded ones to the surface ore bins, where the railway cars were loaded.The skips used in Butte are generally of 100 cubic feet capacity and hold five tons of ore, and weigh 7,500 lbs. The cage above, to which the skip is attached, weighs 2,300 lbs. The skips dump automatically into a pocket of 50 tons capacity. Two men are with the skips underground and load them from 125 ton capacity ore-pockets, under each station, the bottoms of the pockets having an inclination of 50 degrees from the horizontal. At the bottom of these pockets a gate is operated by compressed air. The labor of loading the skips amounts only to the opening and closing of a valve in the air-line, the ore running by gravity into the skips.Besides the saving in labor, the use of the skips has removed the necessity of underground landing chairs in the shaft and the accidents which are inevitable where such chairs are used."

Jan 1, 1913

By E. C. Bain

THE more familiar compositions of iron-carbon-chromium1 and the iron-carbon-tungsten2 systems have been investigated with a degree of thoroughness which has permitted the construction of their three-dimensional equilibrium diagrams; and it is probable that these equilibrium diagrams are sufficiently accurate for the present metallographic needs. Strangely enough, in spite of their importance, the alloys of iron, carbon and manganese apparently have not been investigated in the same systematic manner, and so far as is known, no three-component equilibrium diagram for this system is available. Even iron-carbon-nickel alloys3 have been studied rather more thoroughly; for these the solidus and liquidus surfaces have already been determined, but the solid transformations in this, as in the manganese system, have not been reported systematically. The present paper deals with the constitution at equilibrium of a series of 36 iron-carbon-manganese alloys of commercial purity limited by 1.5 per cent carbon and 15 per cent manganese, a range of compositions including most of the manganese steels. The temperature range of melting has not been determined, nor has the high-temperature (delta iron) ferrite equilibrium been included in the study, it being considered that the more important characteristics of the manganese steels are their ordinary transformations in the solid state. The delta iron region is almost certain to be a small tetrahedron not very different in magnitude or contour from that in the iron-carbon-nickel diagram. It is probably true

Jan 1, 1932

"Mining as an industry of Utah had its inception in the activities of United States soldiers who came to the Salt Lake valley under the command of Gen. P. E. Connor, founder of Fort Douglas, in October, 1862. Many of these soldiers were from California and naturally employed their spare time in the search for minerals. Although their military status did not permit them to make locations in their own names, they assiduously prospected the region in accordance with their own knowledge and with information conveyed to them by Indians and others. Their efforts were encouraged by their commander, who thereby fairly earned the title of father of the industry here, and by their other officers, and many discoveries that subsequently proved of great value were made by the soldiers.No systematic prospecting or mining had been done in the Territory previously, although early Mormon settlers in the southern portion had mined a little ore from time to time in order to provide supplies of lead for bullets. The Mormon leaders at that time did not encourage mining. They held that agriculture was more important and profitable for their followers.Coal was discovered and produced in 1850. Iron was discovered in 1850 and the first iron plant was in operation in 1852 in Iron County. The first non-ferrous metal production was in 1854, in Beaver County, when Isaac Grundy treated ore from the Rollins mine in what is said to have been the first lead furnace west of the Rocky Mountains. The first mineral location was the West Jordan claim in Bingham canyon, located September 17, 1863, now owned by the United States Smelting, Refining & Mining Co., and still productive. The first district organized in the state was the West Mountain (Bingham), December I 7, 1863. Other important districts of early organization are: Little Cottonwood, December 20, 1869; Big Cottonwood, July 11, 1870; American Fork, July 21, 1870; Uintah (Park City), July 8, 1871; Tintic, December 13, 1896; Ophir, August 6, 1870. The first silver-lead smelting was by J. W. Gibson at Stockton in 1866. Lieut. James Finnerty had previously erected two small trial furnaces there, but made no quantity production."

Jan 1, 1925

"The mines of Butte, in addition to the square timber used, consume each year large quantities of round timber, which are called stulls. The Stull business is an important industry, as will be seen from a brief description of the operations of the Mines Timber Co., which institution furnishes most of the stulls and lagging poles used in the Butte mines.Timber produced by the Mines' Timber Co. is mostly cut on the government forest reserve, on California gulch, American gulch and French gulch. To bring the timber to market, a flume 16 miles long has been constructed from Big American gulch to Mill creek. The flume, which heads on Big American gulch, on the Atlantic slope, crosses the Continental Divide at an elevation of 6,525 ft., and delivers timber at Mill creek on the Butte, Anaconda & Pacific railway, which is on the Pacific slope. Timber is loaded on cars at Mill creek and shipped to the Butte mines, a distance of twenty-six miles. There are 29 trestles on the flume line over 25 ft. high. The highest trestle is 78 ft. and the longest is 775 ft. The longest tunnel on the line of the flume is 565 ft. from portal to portal."

Jan 1, 1913

By D. M. Metcalf

MOST PEOPLE think of peat as an inferior substitute for coal as a fuel, and will be surprised to learn that it is extensively mined in this country for use as fertilizer rather than as a fuel. Some years ago the Florida Humus Co. began producing it at Zellwood, Orange County, Fla., in a small way for local use. When, however, the company secured an Institute member, M. H. Cuise, to apply his wide experience in mining to the problems here it was found possible to decrease production costs 70 per cent and increase output tenfold. The obvious way in which to decrease costs was to replace shovel-and- horse methods with machinery, much of which, in order to keep down-invested capital, was improvised by remodeling second-hand equipment, changing the design where necessary to meet the special conditions involved.

Jan 1, 1932

By R. G. Garlick, H. B. Probst

Tungsten single-crystal specimens of various orientations were deformed in tension at room temperature. Slip traces indicated both (112)(111) and (110) (111) slip; however, about 10 pct plastic dejormation was required bejore these traces could he seen. Resolzled shear-stress considerations indicated that at least some of the particular systems observed were not those on which slip initiated hut were secondary systems. This is highly probable, considering the high plastic strains involved. Analysis of the stress data with respect to possible slip systems indicated that slip must have been initiated at stresses below the proportional-limit stresses measured. ALTHOUGH there is general agreement that slip deformation in fcc and hep metals takes place on the plane of close packing and in the direction of close packing, there is no such agreement for slip in bcc metals. It is generally agreed that the close-packed direction (111) is the slip direction, but investigations have led to conflicting descriptions of the slip plane. As Hoke and Maddin1 point out, there are essentially four points of view. 1) Deformation in bcc metals is composite shear on (112) and (110) planes or on nonparallel (110) planes, and any apparent slip on other planes can be accounted for completely by slip on these planes. Chen and Maddin have reported this to be the possible case for molybdenum." 2) Slip occurs in the (111) direction and is limited to {110), {112), and (123) planes (the three closest packed planes of the lattice). 3) Slip occurs in a (111) direction, but not necessarily on planes of close packing (banal slip). 4) Slip occurs in those directions and on those planes for which ß, the ratio of Burgers vector to interplanar spacing, is a minimum. The slip systems of the bcc metal tungsten have never been fully determined, although several investigators have reported pertinent results.3"7 The present work was initiated to determine the active slip systems in tungsten at room temperature, the critical resolved shear stresses associ- ated with these systems, and the orientation dependency of operative systems. These features of tungsten deformation at room temperature have never been reported in the literature. The authors find this somewhat surprising, particularly in view of the availability of tungsten single crystals since the advent of electron-beam zone-melting techniques and the widespread interest in refractory metals. It would seem apparent that such work has been attempted but the results have not been reported, possibly due to the conflict with deformation theory. The results of the present work conflict with any straightforward description of deformation based on the proposed explanations of slip in bcc metals. Although these conflicts have not been resolved, a presentation of the problem seems in order and should be of value to others working in this field. MATERIALS AND PROCEDURE Single-crystal tungsten rods of 1/8-in. diameter were grown from undoped commercial rod by one-pass electron-beam zone melting in apparatus previously described by witzke.8 Representative analyses of the rod before and after melting are given in Table I. There was no detectable zoning of impurities during melting. Buttonhead tensile specimens, as shown in Fig. 1, were machined from single crystals. Two flats 90 deg apart were ground in the gage length of each specimen. These flat surfaces facilitated the analysis of slip traces. No attempt was made to position these flats with respect to the crystal orientation. The worked surface layer of the machined specimens was removed by electrolytic polishing in a NaOH solution. Tensile-axis orientations were determined by standard Laue back-reflection techniques. The sharpness of the Laue spots indicated that the crystals were free of strain.

Jan 1, 1964

By V. M. Dobrynin

Experimental data demonstrate that physical properties of porous rocks change under pressure. In this paper an assumption is made and proved that under pressure the changes of physical properties such as porosity, density, permeability, resistivity and velocity of elastic waves are controlled to a large extent by the pore compressibility of rocks. It is also shown that the pore compressibility of rocks can be determined, within the range of pressures from 0 to 20,000 psi, by knowing the maximum pore compressibility and the magnitude of the pressure. Mathematical equations were developed which permit one to define changes in physical properties of porous rocks under pressure. These equations were verified by experimental data obtained from the study of sandstones. INTRODUCTION In studying the behavior of porous rocks under pressure in the field of petroleum technology, the most interesting aspect is the observation of those properties which characterize the rocks as possible reservoirs — for example, porosity, permeability, resistivity, density and the velocity of elastic waves. The literature dealing with this problem mainly contains data concerning the study of only one or at most two of these parameters, but not of the group as a whole. An attempt is made in this paper to find general equations involving each of these parameters, which will permit the study of the behavior of rocks under pressure. All experimental data used here were obtained from the investigation of consolidated sandstones. EXPERIMENTAL In addition to the use of published experimental data, an experiment was carried out which studied the main physical properties of sandstones under pressure. Two homogeneous quartz sandstones were chosen for this purpose: (1) the Torpedo sandstone from Kansas, and (2) the Medina sandstone from Ohio. The porosity of the Torpedo sandstone was 20.2 per cent, and that of the Medina 8.7 per cent. Permeabilities were 45 md and less than 1 md, respectively. Each sandstone contained about 5 per cent clay minerals, consisting mostly of kaolinite and chlorite, which were distributed quite evenly throughout the samples. One cylindrical sample 2 in. in diameter and 5 in. in length was cut from each sandstone and then saturated in a vacuum with a 3N solution of NaC1. This high concentration was used in order to obtain true formation factors and to decrease the swelling of the clay minerals. The methods of mounting the samples and measuring the changes in porosity and resistivity were practically the same as those described by Fatt and Mann.1,2 Changes of resistivity under pressure were studied for sandstones with 100 per cent water saturation, and for sandstones with the irreducible water saturation. The irreducible saturation was obtained by enclosing the saturated rock samples in relatively fine silicate powder so as to remove the water by capillary action. This procedure is described by Orkin and Kuchinski.3 Changes of permeability with pressure were determined at room temperature using nitrogen as the flowing medium. In studying the effects of pressure, one series of measurements was made using an internal pore pressure Pi equal to the atmospheric pressure, while the overburden pressure Pe ranged from 0 to 20,000 psi. A second series of measurements was used over the same range of overburden pressure, but with an internal pore pressure of 1,800 psi. When the results were compared on the basis of net overburden pressure (Pe — 0.85 Pi ), there was practically no difference for these two sandstones. The origin of the factor 0.85 in the expression for net overburden pressure is given by Brandt,4 Fatt5 and Geertsma.6 The relatively large bulk volumes of the sample (about 15 cu in.) made it possible to observe a

By H. Majima, E. Peters

The oxidation rates of pyrite, pyrrhotite, chalcopy-rite, chalcocite, covellite, bortzite, galem, sphalerite, and stibnite have beet2 carefully compared at 120 oC, using aqueous phosphate solutions buffered at pH 2.7, 7.1, and 11.2 as zvell as in 1.0 M NaOH and in am~onia-containing solutions. Under conditions of these studies, variations in rates of more than a factor of two per unit of mineral surface area were not observed for different minerals in phosphate buffered solutions, except that pyrrhotite showed unusually rapid oxidation rates In acid solutions, and stibnite showed very rapid oxidation rates in basic solutions. In caustic solutions, oxidation vates varied considerably, the most rapid being for pyrite and the slowest for sphalerite. In the presence of ammonia, only copper minerals showed more vapid oxidation rates in neutral solutions. Oxidation rates were measured on the basis of oxygen-consunzption rates per unit surface area of exposed mineral, using equivalent surface areas, mineral mesh sizes, pulp densities, agitation, and oxygen pressure. OXIDIZING pressure leaching of sulfide minerals has been a commercial method of treating concentrates of nickel, cobalt, and copper for over a decade, and recently the treatment of lead and zinc concentrates,' and even the recovery of sulfur from pyrrhotite by such processes, have been shown to be technically feasible.' Furthermore, the leaching of uranium ores by solutions acidified through the oxidation of pyrite and other sulfides present in the ore is commercially practicable.3 5 The mechanisms by which sulfide minerals oxidize in aqueous environments are not yet understood. However, certain generalities can be made for systems containing no unusual reagents, in which oxygen is the oxidizing agent. In acid solutions the oxidation of many sulfide minerals leads to the formation of elemental sulfur.8'7 The attack of some sulfides, notably galena (PbS), sphalerite (ZnS), and pyrrhotite (FeS), at temperatures below about 110°C leads to an almost quantitative conversion of the sulfide mineral to elemental sulfur according to the equation: On the other hand pyrite (FeS2) and copper minerals do not yield elemental sulfur quantitatively. Not more than 50 pct of the sulfur in pyrite is converted to the elemental form in acid oxidation, and this percentage is lowered by higher temperatures and possibly higher oxygen pressures.8'9 Copper minerals sometimes yield elemental sulfurlo'" but, since sulfur can reduce cupric ions with the precipitation of CuS or Cu2S, it is not likely that elemental sulfur is obtained in good yield. In acid solutions sulfur that is not converted to the elemental form always appears as sulfate salts or sulfuric acid. Sulfide minerals that yield elemental sulfur nearly quantitatively on oxidation in acid solutions tend to generate H2S when the conditions are not oxidizing. However, although it has been suggested that H2S is an essential intermediate in the mechanism of oxidation," this is doubtful because it is oxidized very slowly by oxygen. In basic solutions elemental sulfur is never formed, as predicted by thermodynamical considerations, summarized in the form of a potential-pH diagram in Fig. 1. However in neutral and basic solutions, unstable forms of sulfur not shown in the diagram appear during oxidation, notably thiosulfate (SOT-) and polythi-onates (S,O;-, x = 2 to 6).l3,l4 On prolonged oxidation only hexavalent sulfur as sulfate (SOi-) or sulfamate (NHzSO;) is found to remain, the latter appearing only in the presence of ammonia. The oxidation kinetics for thiosulfate by oxygen are the subject of a separate paper,'5 and were studied on the presumption that thiosulfate may, in fact, be a primary oxidation product for sulfide minerals, at least in neutral and basic solutions. A survey of the literature indicated that comparative oxidation rates for different sulfide minerals were needed to establish the role of the mineral structure and its thermodynamic properties on the oxidation rates and mechanisms.

Jan 1, 1967

By H. R. Page, A. E. Jr Lee

From the inception of zinc retorting on a commercial scale in the United States in 1890,' the retort employed has undergone wide variations in its composition and manufacture, facilitating in part equally remarkable improvements in furnace capacities. The early day hand made clay retort was charged with carbonates or silicates or with coarse dead roasted concentrates mixed with a large proportion of charge fuel resulting in a relatively low zinc burden and fired 24 hr in direct coal fired furnaces. Its modern counterpart is fabricated in hydraulic presses from clay mixtures containing sizeable amounts of either silicon carbide or silica flour, charged with sintered flotation concentrates to more than three times the early day zinc burden and fired 24 to 48 hr in gas fired furnaces. This paper does not attempt to describe in detail the early day clay retort practice as it is well outlined in treatises by Ingalls,2 Lodin,3 Liehig,4 Hofman5 and others. A brief review of clay retort practice is presented together with a description of the major developments since 1912. Clay Retorts The Belgian type retort, both in the circular and elliptical forms, has been used almost exclusively. Typical dimensions of press made clay retorts around 1910 are shown in Table 1. Variations in these dimensions were used at different plants according to local conditions to a maximum inside diameter of 9 in. and inside length of 54 in. However, the effective heat penetration in a 24 hr firing cycle and the tendency of the retort to bend limited the retort size. Use of the elliptical vessel was an attempt to present a stronger cross-section resisting the tendency to bend and to increase the burden without increasing the depth of heat penetration. One exception to the 48-54 in. length was the 60 in. retort used as early as 1905 at Palmerton by means of supporting the last 12 in. at the butt end with a specially designed furnace back-wall. This backwall construction with the 60 in. retort had been developed and used at Bethlehem by G. G. Con-vers and A. B. DeSaulles. An attempt was made at Blende, Colo. to use even larger retorts of the Rhenish type based on European practice and requiring much higher furnace temperatures. Satisfactory plastic clays capable of withstanding these temperatures were not available, and the plant never operated successfully. PREPARATION OF BATCH Composition of the clay retort by weight was 40 to 50 pct raw clay and the balance "grog." Generally speaking the mix consisted of 7 parts plastic clay to 9 parts grog by volume. Principal source of the clay used was the Cheltenham vein—sometimes referred to as "St. Louis city clay." A typical analysis was A12O3-31.0 pct, SiO2-50.0 pct, Fe2O3-2.5 pct, MgO-0.3 pct, CaO-1.5 pct and loss on ignition 14.0 pct. At the smelter the clay was weathered whenever possible and then crushed to 0.08 in. or finer. Grog consisted of calcined adobies, cleaned retort scrap and cleaned refuse fire brick such as old furnace brick, blast furnace linings, and others. Saggers from ceramic plants and calcined flint clay were later used. The grog materials were ground to 0.12 m. or finer. Occasionally coke dust up to 10 pct of the mix was substituted for a part of the grog following European practice.² Particle size of the grog has a major influence on the retort properties—the larger the grain, the better can the retort withstand thermal shocks, resist bending at furnace temperatures and resist corrosion from slag; the smaller the grain, the lower the loss of zinc vapor through the retort walls. Grog forms the skeleton of the retort, and the clay shrinks around its grains to act as a binder. In the drying process, the grog has a stabilizing effect on the drying rate, decreasing shrinkage and giving up previously absorbed water to the surrounding clay to minimize the danger of cracking or checking.² Grog and clay were mixed through a horizontal pug mill with 10 to 20 pct water added, depending on whether the retort was to be formed by hand or mechanically, more water being required for the hand process. The batch or "mud" extruded from the pug mill was cut in convenient lengths for handling, stacked in piles or in special rooms, covered with wet burlap and allowed to "rot" or age from 1 to 8 weeks to increase plasticity. HAND MOLDING If the retort was to be molded by hand, the mud was repugged after the rotting period and given to the molders. Their molds consisted of 3 sheet iron or wood cylinders, each one third the retort length and defining the outer shape of the retort. Beginning with the bottom section, mud was placed in the form and tamped with a rammer

Jan 1, 1950

By PAUL DYER MERICA

PAUL DYER MERICA, who has been awarded the James Douglas Gold Medal for his achievements in non-ferrous metallurgy, is a Hoosier, having been born at Warsaw, Ind., in 1889. His father, a clergyman and educator, was president of the University of Wyoming from 1908 to 1913. After graduating from the University of Wisconsin in 1908, young Merica (not yet twenty years of age) went to China, where he was professor of chemistry in Chekiang Provincial College, Hangchow, until 1911. He then went to Germany to s t u d y and was fortunate enough to receive his Ph.D. from the University of Berlin just a few months before the outbreak of the World War in 1914. Returning to America, his first position was as special investigator at the En¬gineering Experiment Station of the University of Illinois, but before the year was out he joined the staff of the U. S. Bureau of Standards as associate physicist. Since 1918, he has been superintendent of research for the International Nickel Co. His work during those years is excellently summarized in the following quotation from the statement of Zay Jeffries recommending him for the award.

Jan 1, 1929

By R. E. Crockett

MAGNETITE mining and milling in the Eastern States was at capacity during 1940, owing to the heavy industrial, defense, and war demand, coupled temporarily with the almost total stoppage of imports of foreign ores other than those under American ownership. In New York State the active mines were those operated by the Republic Steel Corp. at Mineville and Lyon Mountain. Republic's new concentrating mill at Port Henry, handling the Mineville ores, went into production about the first of April. Other large magnetite deposits in New York are currently being prospected and studied and may be under development in the near future. In New Jersey the Mt. Hope and

Jan 1, 1941

David T. Day, Washington, D. C.: The paper of Mr. Adams is chiefly valuable because it emphasizes the ease with which petroleum can migrate in the earth's crust. Concerning this migration, I have little faith in the rôle of water as a carrier of gaseous or liquid hydrocarbon, suspended or mixed in the water in any way. My lack of faith is due to observation of

Jan 1, 1903