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By Claiborne C. Van Zandt

THE heavy postwar demand for Portland Cement has created shortages that are gradually being overcome by increases in plant capacity. In the post-war period, the Lone Star Cement Corp. has expanded several of its existing 15 plants and has built 2 new plants, now in operation, with a third new plant under construction in Brazil, of design somewhat different from that of the two preceding ones. The new domestic plants are located at Lone Star, Va., near Roanoke, and at Maryneal, Tex., near Sweetwater, and went into operation during 1951. Each plant is equipped with two rotary kilns and has an initial capacity of 1,500,000 bbl per year, or 6,000,000 sacks. The total cost of each plant was about $10,500,000, and on this basis $7.00 in 1951 money are required per bbl of annual capacity; at 376 lb per bbl, this corresponds to $37.00 per ton of output. The investment corresponds to approximately $80,000 per hourly-wage earner employed. The purpose of this paper is to describe the most interesting design features of the two new and almost identical Lone Star plants. Why the Dry Process Was Chosen The two new domestic Lone Star mills employ the dry process because: 1-The raw materials at both properties are particularly suitable and can be dried very, readily. 2-The Maryneal, Tex., plant does not have water available for slurry. 3-Very substantial kiln fuel savings can be obtained. 4-Dry raw grinding reduces ball and liner wear and- general maintenance, without any sacrifice in power. Operating costs to date have more than justified the choice of the dry process for these two plants. Raw Materials The chemical composition of Portland Cement raw material after crushing, grinding, and mixing, but before burning, is about as follows: [ ] sometimes tailings from an iron ore concentrating plant. Certain objectionable materials occur in raw mix: magnesia, limited in cement to 5 pct, in excessive amounts; alkalies, as sodium and potassium; phosphorous; and sulphur, generally present in coal and oil. The Roanoke raw, materials are dense limestone and shale. The Maryneal materials are soft limestone and a hard brittle clay that can be handled much like shale. Sand and iron ore are required in small quantities. General Plant Layout and Construction The two plants are so similar that one joint description will cover both, with such exceptions as will be especially indicated. The crushing plant is located in the quarry, and raw material is conveyed by belt to the storage building, where all materials are stored and handled. Fig. 1 identifies the various structures of the Roanoke plant. The large storage building is used for the storing and handling of all materials, including limestone, shale, sand, iron ore, coal, clinker, and gypsum. Directly adjoining the storage building is a structure under a similar arched roof, containing the raw and clinker grinding departments and the electrical substation. The discharge ends of kilns and coolers, and coal or gas burning equipment are also placed at one end of the mill building. The 340ft long kilns extend away from the main buildings to form the long leg of an L, at the end of which is the feeding and kiln dust collecting equipment, and the raw blending silos are conveniently located adjacent to the feed end of the kilns. The machine shop, storeroom, electrical shop, foremen's office, service rooms, and meeting hall are combined in one structure in the center of the plant, and the office and laboratory are close by. The cement silos and packhouse do not have to be tied directly into the manufacturing process and are therefore located at a point convenient to the railroad tracks.

Jan 1, 1952

By Robert W. Thomas

LEACHING of mined-out areas at the Arizona property of the Ray Mines Division, Kennecott Copper Corp., was started on Jan. 20, 1.937, and by July 1, 1938, 10,000,000 lb. of copper had been produced by this method. Leaching operations at present are confined to the western portion of the ore body and over an area of approximately ten acres. The ore in this area was extremely high in pyrite and the copper content, which averaged slightly in excess of 1 per cent, was the result of incomplete secondary enrichment by solutions which apparently worked laterally from the main ore body. Above the ore was an unaltered zone of primary or protore averaging 125 ft. in thickness and containing approximately 0.6 per cent copper. Above this was the capping or leached zone averaging 50 ft. thick.

Jan 1, 1938

By R. W. Raymond

THIS meeting was held in the new home of the Institute, the United Engineering Society Building, 29 West 39th Street, New York City, directly following the Dedication ceremonies. The first session was held in the large Auditorium, Thursday, April 18. The meeting was called to order by Mr. John Hays Hammond, President of the Council, who said Before taking up the reading and discussion of papers, I will call upon Dr. Rossiter W. Raymond, the oldest living past-President of the Institute, who has been in harness almost continuously for thirty-six years, and who has contributed more than any one else to bring this society to its present great success and to establish the reputation of the American mining engineer the world over, for a few words supplementary to those which were uttered to engineers generally, during the sessions of yesterday and the day before. ADDRESS BY R. W. RAYMOND. The generally accepted Darwinian doctrine of the survival of the fittest is sometimes illustrated by persons who are supposed to be the fittest because they have simply survived. I fear that I come under that category. Almost all of my contemporaries in the early history of this Institute have passed away. Only one or two of the original founders remain, and I may fairly say that scarcely any remain who were active at that : time in shaping the organization and the future career of the Institute. In May, 1871, I was thirty-one years old. Next week I shall be sixty-seven years old. All the intervening years have been devoted to the service of this Institute almost continuously, either as President or Vice-President or Secretary. You may easily imagine, therefore, with what pleasure I greet you on this occasion. I am not here to extend to you the welcome of the City - of

May 1, 1907

Note by the Secretary.-—In the preceding communication of Mr. Rickard, in the present discussion, as printed in Trans., xxiii., the loss of quicksilver at Pestarena, reported on p. 569, as 230 and 234 grammes per metric ton, is stated as equivalent to about 74 pounds per short ton avoirdupois—an obvious error, which escaped correction in my reading of the proofs, and was not discovered until after Vol. XXIII. had left the press. The true equivalent is 0.46 pound or about 7 1/2 ounces (instead of pounds) per short ton.— R. w. R. Philip Argall, Denver, Colo. (communication to the Secretary) : Mr. Rickard's last contribution to this discussion* calls for some reply from me, if only by way of defending myself against the charge (p. 569) that my criticisms of his paper were "unnecessarily hypercritical and occasionally unfair." At the same time I am fully aware that our Transactions are not the place for mere personal controversy, and that the sole object of discussion is to define differences of opinion, and defend opposing views as a means of eliciting the truth. Mr. Rickard disclaims the statement, which he says I attributed to him, that in the slow-crushing Gilpin county mills the pyrites remain longer in the mortar than the other portions of the ore. My understanding of his statement was based on the following passages in his paper: " Particles of ore, which have heen pulverized to a fineness which would permit of their exit through the screen, are enabled to settle towards the bottom of the mortar. It would he expected that the heavy metallic minerals occurring in the ore would, because of their greater specific gravity, be most affected by this feature of the treatment. In practice this is found to be so. The fine slimes contain a large proportion of metallic sulphides, generally valuable on account of their close association with the precious metals, while the coarsest particles to be found in the tailings usually consist of quartz and other minerals forming the less heavy gangue (Trans., xxiii., 139).

Jan 1, 1895

By T. A. Rickard

The dictionary defines 'jargon' as "barbarous or debased language". This description does not suffice. Quiller-Couch has said, it is "a kind of writing which, from a superficial likeness, commonly passes for prose in these days, and by lazy folk is commonly written for prose, yet actually is not prose at all ". The two main vices of jargon, he says, are "that it uses circumlocution rather than short straight speech", like the Babu who reported his mother's death by saying: "Regret to inform you, the hand that rocked the cradle has kicked the bucket ". Its other chief' vice is that "it habitually chooses vague woolly abstract nouns rather than concrete ones", like the newspaper statement; "He was conveyed to his place of residence in an intoxicated condition", instead of saying, "He was carried home drunk ". Jargon is "an infirmity of speech", it is not journalese, but akin to it. "Like respect- ability in Chicago, jargo4 stalks unchecked in our midst" and renders much technical writing ridiculous. It deals in periphrasis instead of going straight to the point, it loves the abstract rather than the concrete, it dabbles in words of sound rather than of meaning. Avoid it, despise it., if you purpose earnestly to write well. "III literature as in life he makes himself felt who not only calls 4 spade a spade but has the pluck to double spades and re-double." * Jargon is rampant in technical publications. Catalogues and other advertisements are conspicuous offenders, but with these the critic is not concerned, except in so far as such 'write-

Jan 1, 1931

By H. E. Brauer

PART I INTRODUCTION Among the zinc base alloys used for casting in metal moulds, particularly die casting, those alloys containing aluminum usually together with copper, are probably the most widely used. The reason lies in their desirable mechanical properties and the fluidity and absence of hot shortness which facilitate casting. Objection to the use of these alloys may bee raised on account of the rather frequent instances of failure of a type variously described as disintegration, exfoliation and intercrystalline corrosion. In all cases which have come to our knowledge where the conditions of service were known, failure has occurred upon exposure to moisture and heat varying from a hot moist atmosphere to high pressure steam. Moreover, the alloys described in all such cases contain impurities or alloying metals which the present authors have found to have enormous accelerating effects on intercrystalline oxidation in zinc-aluminum alloys. Thus Williams1 experimented with an alloy containing a large percentage of tin exposed in Cuba. Bauer2 reports failure of a boiler plug containing over 1 per cent. of impurities, doubtless lead for the most part, and Rawdon's3 examinations were made on an alloy containing 0.4 per cent. lead also exposed to the Tropics. No thorough investigation of the nature and cause of this type of failure has been made heretofore, so far as the authors are aware, although Rawdon correctly classified it as internal oxidation. We have, therefore, carried out this investigation in order to determine the exact nature of this phenomenon and the effect of other metals present as impurities or intentional additions in accelerating or-retarding it. In the appendix we include a considerable amount of data which may be valuable in selecting an alloy combining good physical properties with high resistance to oxidation.

Jan 8, 1922

Jan 1, 1905

By George A. Hill

WE of the oil industry, devoted to freedom of initiative, free competitive enter- prise, and free American institutions, applaud, with one voice, affirmation by the President of the national will and purpose to preserve and to protect, against all aggressors, "our American way of life with our individual and national freedom." We subscribe utterly and completely to this guiding declaration and seek its further definition as applied to the oil industry. Fortunately for all, the policy of the Government, after adequate study and deliberation, has been given precise definition. The National Defense Advisory Commission, with its patriotic, highly qualified, and distinguished personnel, has unanimously agreed to and adopted twelve general principles governing national defense contracts and also fair labor standard requirements. The President of the

Jan 1, 1940

By Victor L. Stevens

The Oso tunnel is one of three tunnels located on the San Juan-Chama Project in south-central Colorado. The purpose of the tunnel is to carry water from the upper San Juan watershed through the Continental Divide into the Rio Grande watershed. The Oso tunnel contract was awarded by the U.S. Bureau of Reclamation to a joint venture of Boyles Brothers Drilling Co., Gibbons & Reed Co., and Cimco in February 1966. The Oso tunnel is 26,660 ft long and has a rock section of 10 ft, 2 in. with a lined diameter of 8 ft circular. The main portion of the rock formation was in the Lewis shale. This formation is quite consistent in hardness and texture with exception of localized limestone concretions and sandy siltstone inclusions. The job was bid on the basis of using a James S. Robbins mole of the P221 series. The decision for using a mole was predicated on the geology and the experience of the same joint venture on the adjoining Azotea tunnel where a mole was successfully used. The Robbins P221 series mole is capable of cutting from 9 ft, 11 in. to a 10 ft, 7 in. diam without any major change. It is 40 ft long and weighs 60 tons. The cutting head has 22 disk-type cutters and one center pilot (standard 9 7/8 -in.) tricone bit. The head is powered by four 75 hp electric motors. Gripper pads at about the midway point on each side of the machine are pushed into the tunnel ribs and thrust-cylinders in front of each gripper apply pressure to the face as the head rotates. The regripping cycle is 3 ft and then the grippers are retracted and advanced. Each cutter on the perimeter of the head is followed by a bucket which scoops up the cut material, almost in the same manner as a water wheel, and dumps it into a conveyor situated along the top of the mole. The muck from the mole conveyor is dumped into a gantry-type conveyor. The gantry conveyor is 350 ft long and is pulled

Jan 1, 1970

By D. F. Kaufman, H. R. Spedden, A. M. Gaudin

MANY studies of comminution have been made to ascertain the size distribution of the product and to evaluate the work of comminution in the light of the size distributions of the feed and product. Up to now, these studies have been essentially statistical in character, that is, a certain lot of feed was subjected to comminution in some specified way, and the aggregate product was fractionated into sizes, thereby losing all knowledge of individual relationship of feed to product pieces. Radioactive tracers offer a means to do something in this respect which could not be done before, namely, to follow the rupturing of some particular piece in its normal environment of other pieces. That is, it permits going beyond the usual statistical limitations of size distribution studies to what may be termed a personalized or individualized study. The purpose of this paper is to present some preliminary experiments conducted with this tool. The method employed was to mark radioactively some constituent of a feed. It is possible, of course, to consider the preparation of two lots of material of which one is radioactive and the other is not, and to blend the two ahead of the comminuting step; but to do so is open to the objection that the two preparations may not be identical. Therefore a technique has been chosen that removes this objection by merely taking out a size fraction of a comminution feed, rendering that fraction radioactive by exposure to a neutron flux, and then by returning it to Table I. Size Distribution of Offspring Albite Particles Originally 28/35 Mesh and in Admixture with Other Sizes After Grinding 2 min in a Steel Ball Mill Specific Activity ' Cumu- Corrected Distrl- latlve Size for Back- butlon In Distri- Fractlon ground, Weight, Product, button, of Product, cpm/gm g Pctb Pct Mesh (A). (W) (P) (ZP) + 28 0 56.0 0 100.1 28/35 62.6 54.0 24.8 75.3 35/48 62.8 59.4 27.7 47.6 48/65 41.1 53.0 16.2 31.4 65/100 29.6 45.7 10.2 21.2 100/150 23.7 37.0 6.6 14.6 150/200 23.3 25.1 4.4 10.2 200/270 20.1 19.0 2.9 7.3 270/400 17.8 21.2 2.9 4.4 -400 22.9 25.2 4.4 — 100.1 a These activity determinations were made in rapid succession in the order given. The specific activity (Ao) of the active 28/35 mesh fraction of the feed was measured at the beginning, after the measurement on the 65/100 mesh size fraction of the product, and; The end. The decay-corrected activities at those times were 246.7, 241.0. and 236.9 cpm per gm. The weight (W0) of the active 28/35 mesh fraction in the feed was 55.0. b Example of calculation for P in the 65/100 mesh oroduct frac- A W tion; A = 29.6, W = 45.7, Ao = 242.7, Wo = 55.0: P = — x — Ao Wo = 0.102 = 10.2 pet. the remainder of the charge for the comminution experiment. A relatively simple procedure was developed by which albite, containing sodium, was activated in the M.I.T. cyclotron. The cyclotron makes highspeed deuterons which impinge on a beryllium target, thereby producing a concentrated neutron flux. The mineral was exposed to this flux for 2 hr. This treatment changed enough of the sodium to sodium 24 (14.8 hr half-life, 1.4 mev ß) as to make detection and measurement easy. The nuclear reactions taking place were: 11Na23 (n,?) 11Na24 (irradiation) 11Na24 ß,?,? 12Mg24 (decay) The detailed technique of the experimentation was as follows: 40 kg of hand-sorted, lump albite were crushed to pass 10 mesh. After careful mixing of the lot, a screen analysis was made. The whole lot of material was fractionated on standard Tyler screens from 14 down to 200 mesh. Samples for experiments were compounded from these fractions in accordance with the screen analysis. When it was desired to make an experiment in which, for example, the 28/35 mesh size fraction was to be studied, the blend of size fractions was made as indicated above, except that the 28/35 mesh size fraction was added only after irradiation in the cyclotron. The blended charge containing the activated albite was ground for 2 min in a laboratory ball mill with a steel ball charge of controlled size distribution. The ground product was carefully sized on a set of Tyler screens in a Ro-tap. Each size was analyzed for radioactivity by the use of an end-window Geiger-Mueller counter and standard scaling circuit. This analysis was carried out in detail as follows: a 20-g sample was placed in a Petri dish, packed carefully to obtain reproducible geometric distribution with reference to the Geiger-Mueller tube, and the activity was counted for a 2-min period. Several determinations of the activity of the active size fraction in the feed were made at various times to establish the decay in activity with time. Linear interpolation was used to evaluate the activity that the active size fraction in the feed would have had at any given instant. The ratio of the observed activity in a size fraction of the product to the activity that the active size fraction in the feed would have had at the same time gives the fraction in the product size that came from the irradiated size in the feed. The general formula for finding the distribution, P, of a specific individual size fraction in the feed

Jan 1, 1952

By Albert L. Toenges

COAL mining technique progressed slowly until the advent of mechanized mining. The cutting machine was a forward step, but had only a limited effect upon improving the percentage of coal recovery. Previously, the physical fitness of the loaders and the total output of the miners fixed mine production. The miner was an independent contractor and supervision over his working place was superficial. Rising costs and the inroads of substitute fuels demanded increased output per man to lower the unit production cost. Therefore, the amount of coal loaded mechanically in underground bituminous mines has risen from 0.3 per-cent in 1923 to 7.4 in 1929, to 20.2 in 1937, and to 48.9 percent in 1943. When loading devices were introduced it became necessary to adapt them to existing systems of mining, or to alter the mining system to fit the machine. An increased amount of supervision was required as output depended upon proper operation of the machine rather than on the physical fitness of the individual.

Jan 1, 1946

By A. E. Dwight, A. F. Berndt

ThE published U-Ru equilibrium diagram indicates the existence of six intermetallic compounds in this system.' The structure of only two of the compounds, u2Ru2,3 and URU3,4 have been identified. This communication reports on the crystal structure and density of Uau3, which is formed by a peritectoid transformation at 1025° ± 5°C: U3Ru4 + U3Ru5 = U2Ru3. An alloy with the stoichiometric formula U2Ru3 was prepared by arc melting electrolytic uranium and ruthenium of 99.9 pct purity on a water-cooled copper hearth under an argon atmosphere. After homo-genization at 1000°C for 3 days, a metallographic examination revealed that the peritectoid transformation was complete and less than 5 pct of a second phase was present. A powdered sample, obtained by crushing the brittle compound, was annealed for 1 hr at 1000°C and air-cooled. Debye-Scherrer patterns were obtained with filtered CrKa, FeKa, CoKa, or CuKa radiation. The X-ray patterns of U2Ru3 weFe indexed as an fcc structure with a. = 12.895 0.00lA. The unit-cell constant and its standard deviation were calculated by a computer program described by Mueller, Heaton, and Miller.5 The density, measured by an immersion method, was 14.45 g cm-3. A calculated density of 14.48 g cm-3 was obtained on the assumption that twenty-four formula units (120 atoms) comprise a unit cell. The space group is either oh7 Fd3m, or the less symmetric, T4h, Fd3, since reflections indexed as hk0 with h + k + 4n are absent. All values of h2 + k2 + 12 permitted by both space groups are listed in Table I together with dc, do, and I. values. The calculated d spacings were obtained by the computer program of Mueller, Meyer, and simonsen.6 The observed d spacings above 0.77A were obtained from X-ray" patterns prepared with CuKa radiation, above 0.90A with CoKa radiaaion, above 0.98A with FeKa radiation, and above 1.16A with CrKa radiation. An attempt was made to identify the crystal structure of U2Ru3 by comparison with published data on other A2B3 compounds. A recent compilation7 of intermetallic compounds lists thirty-two structure types with the A2B3 stoichiometry. Only two of the structure types are fcc and they are Sb2O3(r), senarmontite, with 16 Sb2O3 per unit cell, and In2Te3 for which several structures have been proposed.8 However, the two cases cited do not have twenty-four formula units in the unit cell. We therefore, cannot identify UPRU3 with any of the other known A2B3 compounds. Ternary alloys were made in which 5 at. pct Os, Rh, or A1 were substituted for 5 pct of the Ru in U2Ru3. The osmium substitution increased the unit cell constant to 12.899 * .001A, which is to be expected since the atomic volume of osmium is slightly larger than

Jan 1, 1969

By W. H. Geis

The following pages summarize the causes that led to the suggestion of unit operation of the paloma field, the organization of com-mittees, preparation of the Paloma Operators Agreement and the reasons for rejection of the plan. Introduction Long ago an Austrian physicist observed that under certain conditions the condensation of a liquid from gaseous mixtures resulted from pressure reduction. Some 50 years later he would have known that his research was not in vain. He would have seen a group of serious operators and engineers seeking to apply that principle to a conservation . program for unitized production in the Paloma gas field—but he would also have been saddened to see that forces unsympathetic to the application of science in oil production, with little or no appreciation of modern methods and the advantages of cooperation, so far have prevented the adoption of that program. Soon after the Paloma field was discovered it was realized that all the hydrocarbons in the reservoir existed in the gaseous phase. This condition was confirmed over a large area. Therefore, if the field was to be properly exploited with the greatest ultimate recovery of condensate, the hydrocarbons in the reservoir must be produced in the single or gas phase. They must be cautiously extracted with the least possible reduction of the natural pressure. If this could be accomplished, or if artificial pressure control were utilized, the condensation and underground loss of the valuable distillate would be preventable—otherwise it would not be. Wholehearted cooperation of all oper-ators was required in order to accomplish the conservation purposes of the program. To this end the production engineers of the several companies concerned lent their time and talents. They fully investigated the physical relationships of the products within the complicated gaseous mixture, prepared extensive reports on the subject and drew up a reasonably efficient plan of operations, which now is commonly called the "Paloma Unit Plan" but actually was entitled "The Paloma Operators Agreement." All of the engineers were not in perfect agreement on all the features of the plan, or even on all the engineering principles. However, it is safe to say that on all the important or essential factors there was a unanimity of opinion, particularly as to the objectives. These were fairly simple and reduce to one controlling item, "pressure control" by cycling or recycling. Organization The principal operators initiated the program by calling a meeting of all the lessees in the area, at which an organization was perfected, known as the "Paloma Operators Committee." Various subcommittees were appointed to expedite the work, including an "Engineering Committee." These func-tioned in a businesslike manner, frequently reported to the superior committee and

Jan 1, 1942

By W. H. Geis

The following pages summarize the causes that led to the suggestion of unit operation of the paloma field, the organization of com-mittees, preparation of the Paloma Operators Agreement and the reasons for rejection of the plan. Introduction Long ago an Austrian physicist observed that under certain conditions the condensation of a liquid from gaseous mixtures resulted from pressure reduction. Some 50 years later he would have known that his research was not in vain. He would have seen a group of serious operators and engineers seeking to apply that principle to a conservation . program for unitized production in the Paloma gas field—but he would also have been saddened to see that forces unsympathetic to the application of science in oil production, with little or no appreciation of modern methods and the advantages of cooperation, so far have prevented the adoption of that program. Soon after the Paloma field was discovered it was realized that all the hydrocarbons in the reservoir existed in the gaseous phase. This condition was confirmed over a large area. Therefore, if the field was to be properly exploited with the greatest ultimate recovery of condensate, the hydrocarbons in the reservoir must be produced in the single or gas phase. They must be cautiously extracted with the least possible reduction of the natural pressure. If this could be accomplished, or if artificial pressure control were utilized, the condensation and underground loss of the valuable distillate would be preventable—otherwise it would not be. Wholehearted cooperation of all oper-ators was required in order to accomplish the conservation purposes of the program. To this end the production engineers of the several companies concerned lent their time and talents. They fully investigated the physical relationships of the products within the complicated gaseous mixture, prepared extensive reports on the subject and drew up a reasonably efficient plan of operations, which now is commonly called the "Paloma Unit Plan" but actually was entitled "The Paloma Operators Agreement." All of the engineers were not in perfect agreement on all the features of the plan, or even on all the engineering principles. However, it is safe to say that on all the important or essential factors there was a unanimity of opinion, particularly as to the objectives. These were fairly simple and reduce to one controlling item, "pressure control" by cycling or recycling. Organization The principal operators initiated the program by calling a meeting of all the lessees in the area, at which an organization was perfected, known as the "Paloma Operators Committee." Various subcommittees were appointed to expedite the work, including an "Engineering Committee." These func-tioned in a businesslike manner, frequently reported to the superior committee and

Jan 1, 1942

By F. B. Richards

THERE has been much interest recently in the iron ore supply of the Lake Superior district. It may be of interest to this meeting to give some thought to this situation, dealing more particularly with the present great iron ore deposits of this section. Ores from its various iron ranges are the foundation of the tremendous tonnage of steel and iron of all kinds produced in the territory along and adjacent to the Great Lakes, drawing the bulk of its supply from this northwestern ore country. For a number of years estimates have been made of the quantity of available ore. The latest study, by M. C. Lake, chief geologist of the M. A. Hanna Co., is of great interest and brings the estimated tonnage to Jan. 1. 1929.

Jan 1, 1930

By Robert L. Russell, Henry W. Zimmerman

The Bunker Hill mine in the Coeur d'Alene mining district at Kellogg, Idaho, has been a major producer of Pb-Ag-Zn ores since its discovery in 1887. The mine has produced over 29 million tons of ore from some 20 to 25 veins and ore zones and now covers an area approximately 1 mi long by 0.5 mi wide. The active section of the mine extends from 2500 ft above sea level to 1600 ft below sea level. Ore production is presently at the rate of about 1700 tpd. A 2-mi adit, the Kellogg tunnel, at the 2500 elevation provides access to the main shaft area. Ore is hoisted to the adit level through a 5000-ft. 50º-inclined shaft extending to the lowermost haulage level 1200 ft below sea level. Primary shaft service for men and materials is supplied by three major internal inclined shafts equipped with double-drum hoists. Present production requires ten levels to serve for main line track haulage. These range up to 5000 ft in length and are either 200 or 400 vertical ft apart. Also, many intermediate levels exist throughout the mine.

Jan 1, 1971

By G. A. Parks, C. Kovacs

The xanthate flotation of chrysocolla can be improved by preheating the ore to 500° to 600°C. Addition of water vapor reduces the preheating temperature required. The temperature range of flotation improvement correlates well with the range over which dehydroxylation occurs. This observation is consistent with changes in the structure and properties of the mineral as detected by measurement of solubility, D.T.A., T.G.A., X-ray diffraction, and infrared absorption and with recently proposed explanations of chrysocolla flotation. A brief experiment by one of the authors several years ago showed that exposure of chrysocolla to high temperature water vapor resulted in increased recovery by subsequent xanthate flotation. Recently renewed interest in flotation and thermal properties of chrysocolla1-5 prompted further study of this effect and more detailed reporting.6 This paper explores the response of pure chrysocolla recovery in Hallimond tube flotation tests to the time and temperature of exposure and to changes in the water vapor pressure. Brief attention is paid to the effects of such treatment on accessory minerals. A single experiment with flotation of chrysocolla from an ore is reported. MATERIALS Chysocolla from Inspiration, Gila County, Ariz. was crushed in a porcelain mortar, cleaned of visible and magnetic impurities, and screened to obtain -48 +65 mesh (Tyler) material for flotation test work. The clean material contained 28.5% Cu and was identified as chrysocolla by comparison of X-ray diffraction, D.T.A., and infrared absorption data with that reported for similar materials by others.4,5,7 Samples of malachite and chalcopyrite, prepared in a similar way, were also identified by X-ray diffraction. The sources of these materials are unknown. A sample of chysocolla-bearing oxidized copper ore from Pima, Ariz. was crushed and dry ground for thermal activation and subsequent flotation. PROCEDURES Activation: The apparatus used for exposure of materials to high temperature water vapor is illustrated in Fig. 1. The furnace temperature was controlled to ±5°C Water vapor pressure was controlled by pre-saturating a nitrogen carrier stream with water in an adjustable thermostatted saturator (multiple bubbler). A water manometer and capillary orifice flow meter were used to measure nitrogen flow rates for activation and for subsequent Hallimond tube tests. Gas flow rate and temperature were adjusted prior to introduction of samples. Exposure time was measured from the moment of introduction of the sample to the furnace, hence includes an initial drop below the control temperature. After heating, the samples were removed from the furnace and stored at room temperature in air. Representative samples of activated materials were examined by X-ray diffraction and infrared absorption.

Jan 1, 1967

Z. W. Bartlett, J. C. Carrington, H. C. Petersen and K. T. Price were elected vice-presidents of the Freeport Sulphur Co. Blandford C. Burgess was transferred on January 1 to the new Defense Materials Procurement Agency as strategic materials specialist. In May the Region III headquarters of this organization was moved to London. L. C. Campbell was elected president of National Coal Assn. Mr. Campbell, who has been a member of the National's Board of Directors and Executive Committee for many years, is vice-president of the Coal Div. of the Eastern Gas & Fuel Associates and in charge of their extensive mining operations in West Virginia, Pennsylvania and Kentucky. Vern H. Christoph has been transferred to Panama Canal Co., Marine Bureau, Navigation Division, Port Captains Office, as an admeasurer at Cristobal, Canal Zone. Eugene Cline, recently graduated from the University of Kentucky, has been employed by Pond Creek Pocahontas Coal Co., at Evanston, Ky. Sanford S. Cole, assistant manager of research at the Titanium div. of National Lead Co., received the Alumni Citation from his alma mater, Alfred University, Alfred, N. Y. This was in recognition of outstanding achievements and services in the field of ceramics which have brought honor to the institution. U. K. Custred, recently graduated from University of Kentucky, and may be reached now at Box 87, Monterey, Tenn. Robert E. Dwyer, executive vice-president of Anaconda since 1940, was recently elected president of this company and its subsidiaries, Chile Copper Co., Chile Exploration Co., and Andes Copper Mining Co. As president, Mr. Dwyer succeeds the late William H. Hoover who died in Butte, Mont.

Jan 1, 1952

By Frank Milliken

IN September 1937, the Ohio Copper Co. inaugurated the treatment of its copper-bearing mill tailings at Lark, Utah. These tailings had been accumulated during the regular operation of the Ohio Copper mine and mill over the period 1007 to 1019. Gravity concentration had been employed except for a comparatively short period in 1919, when flotation was used. The ore milled during that period assayed about I per cent Cu. The chief copper mineral, chalcocite, was dissemi-nated in a shattered quartzite, mainly along fracture or cleavage planes. The quartzite gangue was extremely hard and grinding to liberation resulted in excessive sliming of the "sooty" chalcocite, with consequent high tailings losses. Recovery on the seven million tons treated was prob-ably less than 6o per cent of the total copper content. As early as 1918, attempts had been made to sample the dump. In 1928, a com-plete sampling program was undertaken. The sampling consisted of seventy-four 5-in. post auger holes drilled to the full depth of the dump at regular intervals of 250 ft. Each 10-ft. portion thereof com-prised a sample for analysis. Each sample was screened, rolled, divided into three parts, dried and assayed. The reject was retained for testing purposes. From the depth of the auger holes a contour map of the dump was plotted, Fig. 1, which gives percentages of tonnage and copper content.

Jan 1, 1940

By Simon D. Strauss

Production and consumption of nonferrous metals in the United States during 1950 were at peak levels for the postwar period, as is shown in Tables I, II, and III. The trend of production was upward through most of the year. At the year end, with the possible exception of the Tri-State zinc-lead district, the large mining operations in the country were running at capacity. The absence of serious labor interruptions during the year was an important contributing factor in the increased out-put of metals, since in each of the previous postwar years there had been a number of major strikes which affected production adversely.

Jan 2, 1951