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By J. H. Bechtold

Tensile properties of annealed molybdenum were investigated from 1000" to—200°C. In the vicinity of room temperature a well-defined transition in tensile properties occurs. Reduction in area decreases from over 80 pct to 0 pct and, simultaneously, the yield strength increases about 60,000 psi. MOLYBDENUM, tungsten, iron, and many other metals and alloys with the body-centered cubic and hexagonal close-packed crystal structures change from ductile to brittle behavior over some relatively narrow temperature range. The temperature at which this transition in ductility occurs depends on chemical composition, microstructure, and method of testing. When fine grained, completely recrystallized molybdenum of commercial purity is tested in uniaxial tension at a slow strain rate, the transition occurs at slightly below room temperature.' Iron2 and tungsten3 tested under similar conditions become brittle at temperatures close to the boiling point of nitrogen, — 195°C and at about 200°C, respectively. A sharp change in ductility is uncommon in metals with the face-centered cubic crystal structure, however, a relatively sharp transi- tion in notched bar impact properties has been observed below room temperature in a face-centered cubic copper-antimony alloy.4 A transition from ductile to brittle behavior is usually explained by the concepts originally developed by Ludwik,5 and discussed and elaborated on by others including Orowan,6 Hollomon and Jaffe,7 and Gensamer8 In brief, there are two aspects to strength, first the resistance to flow and second the resistance to fracture. Both are functions of temperature, strain, strain rate, stress system, composition, and microstructure. With decreased test temperature the flow stress required to initiate plastic deformation increases more rapidly than the fracture strength and brittle fracture occurs at that temperature where the yield strength equals or exceeds a brittle fracture strength. This investigation was conducted to determine the effects of temperature, strain, and rate of straining on the flow and fracture strengths of molybdenum above, through, and below the ductile-to-brittle transition. Other variables were held constant during testing. This information is believed to show

Jan 1, 1954

By CHARLES F. DEISS

The total pipe-line runs of petroleum in Indiana during 1945 were 4,114,000 bbl., a decline of nearly 17 per cent below the estimated 4,950,000 bbl. produced in 1944. Drilling activity during the year was centered in Posey and Gibson Counties, where seven new pools were discovered in the state. Four of the pools are in Posey County-Crunk, Farmersville, Jeffries and St. Wendells East-and the other three are in Gibson County-Johnson West, Lysle and Mt. Carmel East.

Jan 1, 1946

By P. S. Rudman

Crystal-structure occurrences in binary phase diagrams of fifth- and sixth-period elements, zirconium through palladium and hafniun through platinum, are surveyed with the conclusion that average .group number GN is the dominant correlative. This is interpreted in terms of curves of enthalpy differences between competitiue structures that are continuous func -tions of GN. It is further reasoned that the absolute formation energies may also be continuous functions of GN and if so can be simply obtained from the regatives of the heats of sublimation of the elements. It is shown that from such a heat of formation-GN plot the heats of mixing of alloy systems can be quantitatively predicted. For example, for sixth-period alloys very large exothermic heats of mixing are predicted for systems that span GN = 6 (i.e., Hf-Pt, Ta-Os, ...). Thermodynamic data with which to test these predictions do not appear to be available. If in the latter transition (A subgroup) elements we eliminate from consideration the fourth period where magnetic terms contribute to crystal-structure stability, as shown in Table I, there is a very regular sequence of structures. Using the group number (GN) assignments of Table I, which differ from the usual assignments of 8 to the elements listed as 8 through 10, it is perhaps trivial to say that the phase occurrence is a unique function of GN. However, the interesting aspect of alloys from among these elements is that the alloy structures also appear to correlate with GN. The GN for an alloy is given as GN = SixiGNi, where xi and GNi = atomic fraction and GN of component i, respectively. It is difficult to credit anyone in particular with having discovered this correlation, so many people have implicitly or explicitly employed it in the last 10 years. However, Bloom and Grant' in their correlation of s-phase occurrence with total number of d + s electrons were certainly one of the first to appreciate the correlation and Hume -Rothery2 appears to be responsible for the use of average GN as defined above. Only in the last few years have the phase diagrams of enough alloy systems been determined for this correlation to be surveyed with any degree of completeness. We shall here, in an abbreviated format, summarize the available phase-diagram literature and discuss some consequences of the GN correlation. BINARY DIAGRAM SURVEY In Figs. 1 to 3 the phase occurrences are summarized. In Fig. 4 the occurrence limits for the more common structures are summarized. That the GN of an alloy falls within the occurrence limits of a particular structure is a necessary but not a sufficient condition for the appearance of that structure. The preceding figures certainly illustrate that GN is a dominant correlative for structures of these elements. Many of the diagrams have complications, with ordering and other phase changes occurring in intermediate phases, that cannot be clearly accommodated in such a schematic survey and have hence been left out. Such omissions cannot, however, negate the GN correlations discussed here. Relative atomic size is also an important crystal-structure determinant and since atomic size varies quite regularly with GN for these elements it is possible that the apparent GN correlation is basically a size correlation. In Fig. 5 relative size occurrence limits are given for intermediate phases and extended terminal solutions. The relative volume, ?v/(v) - 2(vA - vB)/(vA + uB), has been taken as the measure

Jan 1, 1968

By L. F. Mondolfo

An aluminum-copper 4 pct Cu alloy aged at room temperature for times increasing up to 78,000 hr was annealed at 170°C and the hardness and electrolytic potential determined during retrogression and subsequent aging. It was found that there is a change of behavior with increasing time of aging at room temperature which indicates that, given sufficient time, retrogression disappears and the room-temperature aging tends to progress directly into the high-temperature aging. WHEN an age-hardenable alloy is aged at low temperature after proper quench, changes of properties and structure take place. If this material is then heated to a temperature higher than the previous one, but still well below the solution-treatment temperature, the properties and structure changes produced by the low-temperature aging disappear and the material apparently reverts to the as-quenched condition, ready to undergo aging from the start. This phenomenon is termed reversion or retrogression. First discovered by Cayler3l it has been extensively investigated, as shown by the number of publications listed in the bibliography. From all the information available the following facts emerge: 1) All aeg hardenable alloys can be retrogressed.9 13, 19) 24, 33, 41, 42, 44, 47, 53, 54, 61, 63, 64, 66, 73, 78 2) All the properties changes that take place during aging at low temperature can be retrogressed to a smaller or larger extent.4,5,7,12,19,32,49,50,57,58,60,67,75,76 67, 75, 76 3) Retrogression requires that the temperature be well above the preliminary aging temperature. If the difference between the two temperatures is small, Little or no retrogression takes place.7,20,32,33,41,49 57. 65 4) The larger the difference between the preliminary aging and the retrogression temperature, the faster and more complete is the retrogression.20, 33, 41, 48, 65, 67 5) Retrogression can be produced several times in the same alloy.23, 35,41,57,59 6) The amount of retrogression that can be obtained depends on the aging temperature. Alloys aged at the lower temperatures can be retrogressed the most. The higher the preliminary aging temperature the less retrogression can be produced.20,25,33,37,44,49,54,58 7) Appreciable retrogression after aging at elevated temperatures is possible only if the preliminary aging has lasted a short time. After a certain time of aging at high temerature retrogression does not take place any more,:5,6,9,10,11,21,40,58 8) During retrogression the Guinier-Preston zones redissolve and disappear. The other precipitate

Jan 1, 1960

By G. R. Frank, R. E. Willett, E. H. Hollingsworth

The most generally accepted equilibrium diagram for A1-Fe alloys has a eutectic system on the aluminum side with an essentially insoluble constituent of the formula, FeAl,, as the second phase. In 1938, Bradley and Taylor1 did report a phase change of FeAl,, but this change has never been confirmed. According to them, FeA1, is the stable phase only at higher temperatures; at lower temperatures, it is converted into Fe2Al7 and aluminum. It has now been found that there is, in fact, a phase change of the Al-Fe constituent on the aluminum side of the equilibrium diagram. This change, however, is not the one reported by Bradley and Taylor. The alloys used were cast by continuous processes and had these analyses: Fe - 1.98 to 2.02 pct, Cu-0.01 pct, Si - 0.01 pct, Mn - 0.01 pct, Mg - 0.00 pct, Zn - 0.00 to 0.01 pct, Cr - 0.00 pet, Ti - 0.00 to 0.04 pct. The constituent in these alloys was identified by X-ray analysis with a Guinier camera and by chemical and X-ray powder diffraction analyses. Two procedures were used to separate constituent for the last two analyses. In one procedure, it was separated by treating a sample with a solution of methanol saturated with iodine. And in the other procedure, it was separated by first applying, at 12 amp per sq ft in 15 pct sulfuric acid at 70°F, an oxide coating to a sample, and then dissolving this coating in a solution of 35 ml of 85 pct H3PO4 and 20 g of CrO3 per liter. Several observations directed attention to a phase change of the A1-Fe constituent. Differences that appeared too great to be accounted for by micro-structure alone were found in the voltages required to apply the same thickness of an oxide coating to products from rapidly and slowly chilled ingot. Even more striking was the difference in appearance of the coatings themselves. One applied to a product from a rapidly chilled ingot was dark gray in appearance, in fact, almost black, while one applied to a product from a slowly chilled ingot was essentially white. Also, even a short period of thermal treatment at an elevated temperature of products from rapidly chilled ingot led to the same anodizing behavior as that of products from slowly chilled in-

Jan 1, 1962

Asarco's Sacaton unit, located near Casa Grande 45 miles southeast of Phoenix, Arizona, was brought into production in February 1974. Ore reserves are estimated at about 48 million tons at 0. 95% copper. Mineralization of the orebody comprises both sulfides and oxides, with minor amounts of gold and silver. Preproduction stripping of 40 million tons of overburden was accomplished in less than two years. Mining is done at the rate of 9,000 stpd ore with a waste-to-ore ratio of 4.6 to 1. 0. The mine is developed on 40 ft benches, and by 1979 underground block caving methods will be phased into the operation at a depth of 1900 ft. Ore is mined in the pit two shifts per day, seven days per week, and is hauled with 85 ton trucks to the primary crushing plant. Trucks dump their loads into a 165 st capacity pocket equipped with a chain curtain which controls the ore flow to the 6 ft 6 in. wide by 24 ft long (2. 0 m by 7.3 m) vibrating feeder grizzly. Grizzly bars are inclined at a 5º slope on the first half of the 0 feeder and 10 on the last half. Grizzly bars have 6 in. (13 mm) spacings which pass 60 to 70% of the mine-run ore. Grizzly oversize drops into a 48 in. by 60 in. (1. 22 m by 1.52 m) primary jaw crusher. Both the grizzly undersize and crusher discharge are collected on a 42 in. (1.07 m) conveyor belt operating 398 fpm (121 mpm) for transport to the 4,750 live st intermediate storage area ahead of the fine crushing plant. Capacity of the Sacaton primary crushing plant is a nominal 1150 stph (1043 mtph). It operates fourteen shifts per week with an effective crushing time of four hours per shift. An economical open-air design was used, but an enclosed operator control room is located on the upper level where the dump truck, feeder, and crusher can be observed. Oversize rocks are removed from the feeder or crusher by the 10-ton bridge crane. Direct operating costs for this well-designed primary crushing plant, including labor, power, supplies, and maintenance, are only 3.5 cents per short ton. An interesting feature of the Sacaton orebody is that the non-sulfide copper minerals, which are less prevalent than the sulfides, occur intimately with the sulfide minerals; for this reason, all ores as mined are treated in a flotation circuit using sulfidizing methods for oxide recovery.

Jan 1, 1978

By W. H. HOWARD

Discussion of the paper of W. H. HOWARD, presented at the Salt Lake meeting, August, 1914, and printed in Bulletin No. 92, August, 1914, pp. 2029 to 2046. EDGAR M. DUNN, Anaconda, Mont.-Mr. Howard's contribution to the literature on the Cottrell, method. of electrostatic precipitation of flue dust and fume at Garfield has been read by us with peculiar interest for the reason that we have been experimenting with the same process at Anaconda for the past eight or nine months, with a view to adapting it, under the direction of Dr. Cottrell and the supervision of J. 0. Elton. and D. R. Kellogg, representing the Anaconda Smelter Commission, to the treatment of very large volumes of gases, using large pipe treaters and various forms of electrodes, with about 150,000 volts rectified current. For the amount of gas to be treated here the 5-in. pipe means a cost for installation that is practically prohibitive, clue to the tremendous number of pipes required, and we have been trying to cut installation costs by increasing the size of the pipes. All of our work is still in the experimental stage, but we have obtained good clearance on our mixed roaster and converter gases with a 3-ft. pipe treater 20 ft. long, and with 5 ft. velocity therein; and with a discharge electrode of a single No. 29 nichrome wire set in the middle of the 3-ft. pipe, with. a consequent electrode spacing of 18 in. The current used has been 150,000 to -160,000 volts, .and of course there have been troubles galore, relating particularly to insulation and rectifying. Blast-furnace gases did not give so good clearance, probably due to relative poverty in moisture and S03 content of blast gases to roaster-converter gases; making the blast gases the poorer in conductivity. Our experience has been so satisfactory that in our next experimental plant-built on a somewhat larger scale-we shall attempt a 4-ft. treater with greater electrode spacing, and a somewhat higher voltage-up to 220,000. As to fractional precipitation, mentioned by Mr. Howard, this idea was tried out at Anaconda last year (1913). Formerly our furnaces (Bruntons) roasting flue dust for the recovery of white arsenic, passed so great an, amount of dust to the settling kitchens that refining of this arsenical product was necessary to eliminate the 5 to 20 per cent. dust contained therein. Consequently the manufacture of As203 was effected in two stages, with a reverberatory roast of the first .product to obtain the final 99.5 per cent. As203. -

Jan 11, 1914

By K. L. Fetters, F. M. Walters

ALL previous records were broken by the Iron and Steel Division, in the number of sessions, the number of papers, and the attendance. In addition to ten papers (all preprinted) on properties, structure, aid hardenability of, carbon and alloy steels, eight formal papers were presented on one or more phases of steelmaklng, and a symposium on the determination of hydrogen and nitrogen in steel. This last started at 2 p.m. and was going strong with more than a third of the audience still present at 6 p.m.

Jan 1, 1944

By G. F. LOUCHLIN

A FEATURE of the International Geological Congress to be held at Pretoria, South Africa, in the summer of 1929,. will be a symposium on the gold resources of the world. In this connection the U. S. Geological Survey and Bureau of Mines have been asked to prepare a report, showing production in the United States, describing the geology of its principal gold- producing districts, and estimating reserves (a) assuming a continuation of presen6economic conditions, and (b) assuming lower costs. This report will not be completed before April 1, but data thus far assembled are here presented with the hope of profiting by discussion and by information from those well informed on any of the important gold-producing districts. Gold production in the United States rose to a maximum exceeding $100,000,000 in 1915 and then rapidly declined to about $52,000,000 in 1920. Since then it has fluctuated, but on the whole slightly declined. Reviews of the eight leading states afford the following tentative conclusions :

Jan 1, 1929

For the year ending February, 1919 PRESIDENT SIDNEY J. JENNINGS NEW YORK, N. Y. PAST PRESIDENTS L. D. RICKETTS NEW YORK, N. Y. PHILIP N. MOORE ST. Louis, Mo. FIRST VICE-PRESIDENT C. W. GOODALE BUTTE, MONT. TREASURER GEORGE D. BARRON NEW YORK, N. Y. SECRETARY EMERITUS ROSSITER W. RAYMOND, NEW YORK, N. Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 1, 1919

At Asarco's Mission mill. located near Sahuarita, Ariz., the 20 500-t/d (22,500-stpd) throughput of highly abrasive and corrosive copper ore can play havoc on equipment wear parts. To minimize frequent replacement work and extend life on key components, Asarco engineers have over the past five years utilized liners made of "Towniprene" in the secondary grinding and flotation area of the plant. Results to date have indicated that these liners last between three and five times longer than those made of metal or ordinary rubber.

Jan 8, 1978

By Oliver Bowles

ALTHOUGH Oliver Bowles retired as chief of the nonmetal economics division of the Bureau of Mines last year, that retirement has not lessened his active interest in the field of nonmetallic minerals, in writing, nor in his hobby, cultivation of African violets. Excellent co-ordination of the timing of a professional meeting and a flower show permitted him on at least one occasion to attend technical sessions and take in the African violet exhibition which happily arrived simultaneously in one city. Dr. Bowles celebrated his seventieth birthday on Jan. 10, 1947, and

Jan 1, 1948

By H. Herman, M. E. Fine

Kinetics of reversion and reformation of GP I were studied resistometrically in Al-1.7 at. pct Cu. The reversion process is over in roughly 1/2 minute at 205 "C irrespective of the amount of primary aging. After reversion the occurrence of an incubation time before reaging begins has been substantiated. The reaging kinetics is drastically accelerated by plastic deformation to the specimen. An incubation time is observed only if the specimen is aged before reversion. The incubation time and the effect of plastic deformation indicate that nucleation of GP I is heterogeneous. Simple clusters of copper atoms apparently do not act as nuclei for GP I. AFTER quenching aluminum-rich copper from the solid solution range, Guinier-Preston zones of the first kind, GP I, form very rapidly at room temperature. The rate, largely controlled by the concentration of vacancies, is initially most rapid1 (that is, at the time of the first measurement: 1/2 min) and decreases with time. The nucleation is thought to be athermal. If after aging for several days the GP I is dissolved by reversion at 205°C, according to measurement of Young's modulus an incubation period is observed before GP I begins to form on subsequent aging.2 Yet if the reversion is carried out immediately after quenching, both resistivity3 and modulus changes2 show no incubation effect. The zones which form after reversion have the same structure as those which form after the quench.4 Because of entropy considerations and also the short diffusion time, the solid solution after reversion, 2 min at 205°C, is probably more highly clustered than at the original solution treating temperature, 520" to 550°C. It appears most reasonable to associate with nucleation the incubation time observed on reaging after reversion. A simple cluster of copper atoms, many of which are presumed to be present after reversion, is then not a sufficient nucleus for GP I; a GP I nucleus must contain something in addition to a cluster of copper atoms. The purpose of the present note is to give some additional experimental information concerning the incubation time and rates of reaging after reversion. The existence of the incubation time has been verified by measurement of another property, the electrical resistivity. Acceleration of reaging after reversion by plastic deformation has also been investigated. In acl.dition, the kinetics of the reversion process itself was studied. EXPERIMENTAL Electrical resistance was measured by the poten-tiometric four probe method. The 1.7 at. pct Cu alloy was furnished by the Aluminum Co. of America in the form of 1/2 in. rod. The major impurities reported by Alcoa were Fe (0.002 wt pct), Si (0.003 wt pct), and Mg (0.001 wt pct). Specimens for measuremenl of resistance were prepared by rolling to 0.010 in., cutting 2 by 0.2 in. pieces, rolling the middle pclrtions of these to 0.005 in., and splitting the 0.010 in. sections up to the reduced central section to form current and potential leads. Aluminum extension wires insulated with ceramic tubes were spot welded to the leads. The specimen was supported by the lead wires. The whole specimen assembly was annealed at 500" C in an air furnace for more than 12 hr and then aged at room temperature. This was done to assure quick and complete resolution during subsequent solution treatments. These were carried out in Houghton's "430 Temper Salt" at 520'C for 1 hr. Unless otherwise specified, quenching was accomplished by quickly transferring the specimen from a salt pot to 25°C water. Aging was carried out in a 3 liter dewar of distilled water, rotated and stirred. The temperature was controlled to +0.01°C with a thermomercurial regulator in conjunction with a transistorized relay

Jan 1, 1962

By Ronald J. McGregor, Anton R. Hendriksz

INTRODUCTION The NIMCIX contactor was developed in the late sixties at the National Institute for Metallurgy in South Africa, for the main purpose of extracting uraniuy from relatively low-grade uranium solutions. ' The concept was sufficiently developed by 1974 to permit the operation of a 1500 litre per minute column to treat unclarified urgnium-bearing solution under industrial conditions. The plant operated so successfully that several large-scale units have subsequent18 teen constructed and are operating efficiently. ' Total resin consumption figures as210w as 3 per cent per annum have been reported, and the extraction efficiencies of the installations have been exceptionally good. All the solutions treated have been acidic in nature and in every case have been of such a nature as to significantly depress the maximum uranium loading on the resin beads. The chemical constituents of the leach solution fed to the loading column determines the ease with which the soluble uranium can be absorbed by an ion exchange resin. The concentration of competing ions and various resin foulants define the nature of the continuous ion exchange equipment required for efficient extraction performance. The basic NIMCIX concept is retained in these various alternate designs, but batch or continuous elution methods with fully automated or manual control systems may be selected for the different process solution conditions. BRIEF DESCRIPTION OF THE NIMCIX CONTACTOR The NIMCIX ion exchange column is a multi-stage fluidized bed contactor which is designed to permit a counter-current flow of solution and resin in order to maximize extraction efficiency. The flow o resin is periodic, based on the Cloete and Streat 5 principle of reverse flow. The basic operating cycle can be divided into five periods, as illustrated in Figure 1. For the purposes of describing the cycle, the loading column is considered; how- ever, a similar sequence may be applied to the operation of a NIMCIX continuous elution column. S'I'EP 1: During the forward flow period, Solution flows up through the column and fluidizes the resin contained in each stage. The uranium depleted solution overflows the upper flared-section of the column as the tail solution. Step 2: The flow of solution to the column is temporarily stopped and the resin is allowed to Settle onto the plates in the column. STEP 3: During the reverse flow period, a fixed volume of solution is drained from the column to the transfer vessel. This flow causes resin transfer to occur from stage to stage and also out of the bottom stage. At the end of this period, which expires when the low level switch (LS) is actuated, some of the resin is left in the conical section of the column and the pipe interconnecting the column and the vessel. STEP 4: The cone flush period ensures that all the resin left in the cone of the column and the pipe is transferred to the transfer vessel before forward flow commences. STEP 5: The loaded resin in the transfer vessel, which has been isolated from the column, can either be hydraulically transferred to the top of the elution column or eluted in the vessel before being transferred to the top of the loading column. The major advantages associated with the NIMCIX concept are: (i) Simple method of operation (ii) Contactor can readily be scaled up to large diameters. (iii) Because the resin does not pass through pumps or airlifts, and valves cannot be closed on resin beads at any time, the resin losses are exceptionally low. (iv) Operating costs are low. (v) Relatively few valves in the system. (vi) Stable operation is achieved over a wide range of feed rates and concentrations.

Jan 1, 1980

With over one year experience, Western Deep Levels Ltd., reports satisfactory operation with new features of its 200,000 ton per month gold reduction plant. Western Deep is Anglo American group's newest gold mine. It is situated 43 miles west of Johannesburg on the West Wits Line and will ultimately be extracting ore from a depth of 13,000 ft. Although the plant was put in production in March 1962, after a three month break-in period, construction of the fifth milling section was not completed until last month.

Jan 7, 1963

By D. B. Reger

DAVID B. REGER.-T Want to 'add that since this paper was prepared a well is now being; drilled it the location recommended do the last page. It was not, however, done at my instance; it was done at the instance of Dr. White, the State- Geologist of West Virginia, who has been trying for several years to induce the large oil and gas companies to make a test of some of these, deep sands in West Virginia and a well is now just being started in Wood County, right at this immediate

Jan 4, 1917

By Oswald J. Heinrich

In conclusion of a series of deep exploration-borings with the diamond drill, I beg to submit the following statements, supplementary to those in my former papers on this subject: Since my communications read at the St. Louis Meeting, in May last, I have finished two more borings, one terminating at the depth of 922 feet 7 inches, the other at the depth of 715 feet 6 inches. The results in regard to time and expenditure have been highly favorable and fully confirmatory of my opinion stated in previous

By Freeman Bishop

The Bureau of Mines, beset by political woes not of its own making, is struggling to maintain equilibrium as Congress is being made the focal point for repeated charges that the Bureau has "not done a very good job" of setting up and supervising coal mine health and safety standards approved last year by the Congress. Senator Harrison Williams (D- N.J.) is the latest to enter the arena. A crusading legislator, he is now calling for "legislative overview" hearings to judge Bureau competency in matters of coal safety legislation enforcement

Jan 1, 1970

By S. Robinson Brainard

In 1957 the pay of chief executives in the nonferrous metals industry was well above average when compared with other major industries. Furthermore, it continued to rise last year while sales declined 8.2 pct and profits plummeted 32.7 pct on the average. Compensation of Chief Executives: One of the primary objectives of the survey is to measure year-to-year changes in top-management total compensation as it relates to company size and industry characteristics. Total compensation includes salary, bonuses, and the value of deferred contingent compensation awards.

Jan 10, 1958

By R. M. Foley, Hidesaburo Kurushima

About 25 pct of all Japanese pyrite comes from the Yanahara mine on Honchu Island. For the past 40 years lack of an economical recovery process forced the operator, Dowa Mining Co., to sell the pyrite for its contained sulfur only, leaving 7 million tons of high grade iron ore waste. Introduction of the Dorrco FluoSolids roasting system enabled the company to make use of its iron sulfides and also to find a market for the mine's considerable pyrrhotite production. The success of this project is of great importance to Japan's economy since it points the way toward material increase in her natural resources. Prior to use of the present process, no practical method was available for commercial exploitation of known large tonnages of pyrrhotite, while the copper content of the even larger deposits of pyrite made the roasted residue unacceptable for the iron and steel industry. In Europe, large amounts of copper-bearing pyrite cinder are given a chloridizing roast for separation of the copper and iron but this treatment is not economical in Japan where salt is imported from as far away as Egypt.

Jan 10, 1958