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By Lloyd Jones

THE strip industry made rapid strides in regard to both width and gage until about 1922, when the maximum width was about 20 in. In the hot mills, strips of thin gages in wide widths could be pro-duced, but only at a sacrifice of length of coil, con-siderable increase in power, and decreased tonnage out-put on the min. Hot mills, like the Bray sheet mill and the modern strip and skelp mills, demonstrated that . wider strip could readily be rolled, if such a product was desired. The strip manufacturers were really limited in width, not by the hot strip, but by the cold rolling of wide strip. This factor was roll pressure. The diameter of rolls increased as the width of strip increased. For cold rolling strip 20 in. wide, cold rolls were approximately 20 in. diameter. As the rolls became larger, the arc of contact between the rolls and the strip increased approximately, according to the formula, b=\/Rd where b = the width of contact R = roll radius d = total reduction Now the crushing strength of cold steel of low carbon varies from 70,000 to 100,000 lb. per sq. in. With each succeeding pass the crushing strength increases and may approach 250,000 lb., according to the total reduction. The total reduction in cold rolling of low-carbon steel will range from 40 to 70 per cent of the original thickness, usually in about three or four passes. On this basis, assuming a reduction of 20 per cent in one pass, the crushing strength of steel assumed at 120,000 lb., we have a total pressure between rolls, which (assuming that the rolls do not deform) equals: Roll Strip Strip Diameter, Width, Thickness, In. In. In. Pounds 10 10 0.100 380,000 20 20 0.100 1,080,000 30 36 0.100 2,375,000 42 50 0.100 3,900,000 These figures are approximate, but you will note that in increasing the width five times, or 50 in., the total pressure between the rolls increased approximately ten times. In other words, the pressure per inch of width increased from 38,000 to 78,000 lb. for the same per-centage of reduction.

Jan 3, 1928

By Dr. O’Neil Thomas J., Donald W. Gentry

"We should be concerned about the future be- cause we will have to spend the rest of our lives there. " -Charles Kettering INTRODUCTION Since the early 1970s, there has been no economic phenomenon that has been more widely discussed or experienced in the United States than inflation. Al- though its precise definition and measurement are elusive, inflation has had pro- found and extensive impacts on the manner in which nearly everyone lives. It is painfully obvious to consumers that inflation is characterized by a continuing up- ward spiral of prices. In a capital-intensive industry like mining, those increases can be positively breathtaking. An interesting example is shown in Table 1. Table I shows that on a unit basis, the equivalent 1980 capital cost of Cuajone was over six times the cost of the adjacent and quite similar Toquepala operation completed in 1959. Such sobering statistics weigh heavily on the minds of executives who are contemplating major investments in new mining facilities. In spite of its monumental presence, inflation has usually been either inadequately covered or totally ignored in textbooks on engineering economy. The reasons for this are not entirely clear, but a contributing factor is the inherent difficulty in accurately predicting inflation. However, under certain conditions, inflation may become the most important factor in a mining investment, and it can rarely be safely ignored in capital investment analyses. DEFINING AND MEASURING INFLATION Defining inflation and related terms is relatively easy. Its measurement, how- ever, is the source of almost endless debate in economic and political circles. How- ever, much of that debate is not relevant to the scope of this book, so that only those issues which impact directly on the capital investment decision are covered in this section. Inflation is the general decline in the value of money as measured by what it will buy. It is clear, then, that the rate of inflation varies with the particular currency under consideration as well as the type of goods and services being purchased. One would find, for example, that the general rate of inflation relative to German marks

Jan 1, 1984

AT THE beginning of February the British Government announced acceptance of the American terms for funding the war debt, the main features-being as follows: Interest rate of 3 per cent. for the first 10 years and then 3 ½ per cent. up to the final extinguishment of the debt at the end of 62 years. The interest from the time since the loans were made to the actual beginning of the funding arrangement to be recomputed at 4 1/4 per cent. instead of the 5 per cent. rate now in effect. Congress ratified the contract respecting the British debt. The ship subsidy bill was relegated to the rear, which is indeed an end to the project. The natural consequence of this will be a liquidation of the Govern-ment's shipping business. The joint committee on the reorganization of Govern-ment departments made its report to the President. In general this seems to offer a well-considered plan for the coordination of Government service. The pro-posals respecting the bureaus that are particularly associated with the mining industry may be subject to criticism. According to the committee's plan, the Geological Survey remains in the Department of the Interior, but the Bureau of Mines and the compilation of the statistics of mineral production are transferred to the Department of Commerce. The Lausanne conference among the European powers came to an end early in February, without any treaty having been signed, owing to the refusal of the Turks to accept the ultimatum of the Allies. Theoreti-cally this left conditions in a state-of war between the Allies and Turkey. However, no actual movements have resulted. The French and Belgians continued to hold the Ruhr district of Westphalia, extending their lines and administration of the region. The Germans adhered to the policy of passive resistance. In the Parliament of Great Britain the French and Belgian policy was plainly declared to be unwise and dangerous. French and Belgian industries, moreover, were troubled by strikes among their own coal miners for higher wages. The Poles and Lithuanians engaged in border war-fare;. the civil war in Ireland continued. The rest of the world was quiet insofar as military operations are concerned.

Jan 2, 1923

By Rossiter Raymond

This regiment, originally known as the First Engineer Reserve, will be remembered as the one recruited in New York City through the efforts of the Joint Military Committee of the National Engineering Societies. It was sent to England in August, 1917, and, after a few clays, forwarded to France and attached for immediate service to the British Expeditionary Force, without any opportunity for further field-training. This circumstance has led in some quarters to the impression that the regiment was one of engineers and mechanics merely, and had never been drilled under arms; whereas, in fact, it had received such instruction at Fort Totten for some time previous to its embarkation. It is true that in the famous affair of the German counter-attack after Byng's victory near Cambrai, the men of the Eleventh Engineers fought with pick-axes and tools, as well as with rifles borrowed from dead or wounded soldiers; but that was because they had left their own arms in camp, while doing the railroad-building work to which they had been detailed. The accomplishment of that work is really more remarkable than the behavior of the men under a German surprise-attack. It was before that counter-attack, and immediately after Byng's advance, that Field-Marshal Haig issued his despatch, announcing that the engineers deserved as much credit for that victory as the infantry, having performed miracles in keeping the railway transportation up to the fighting line. Indeed, the subsequent scrimmage, of which so much has been said, was ?Date possible only by the extraordinary position of the engineers at the very front, instead of in the rear, as might have been expected of them. A letter recently received from an officer of the regiment says: We have only recently been receiving the New York papers of early December, in which our regiment seems to have received much favorable mention. The stories were, in the main, true. Our men behaved themselves creditably, and certain of the officers received special mention for valor. Two of our 2d lieutenants were pro-moted to 1st lieutenant rank by special orders of General Pershing for "gallant con-duct in action," and about four others would have been decorated by the British,

Jan 4, 1918

By P. Gobin, J. Perez, P. Peguin

The strain-amplitude- dependent part of the internal friction of alluminum after several ther momechanical treatments has been measured in the I-cycle range and at the ambient temperature. The internal friction in the outer layer of the torsional specimen us stress is computed from the experimental data. The curues obtained are analyzed in tevnzs of u coirzbinntion of AH and p, which aye, respectively, due to the vecersible unpinning from weak pills and to the plastic strain. Considerirlg the notion of thermally activated unpinning and repinning, it is shown that in our experimental conditions tlze dislocation lines acl as in the H model of Granato and Liiclze. It is also seen that the internal friction p which appears at higher- strains call be described by a simple expression which is in good agreement with our results. A qualitative interpretatiorz is proposed by combining these new types of intelpnal fviction. We define the internal friction 6 as half the ratio of the dissipated energy aW during one cycle to the maximum supplied strain energy W of a material submitted to a periodic stress. Experiment and theory show that internal friction varies with stress above a critical value.' Below this value the internal friction is strain-amplitude-independent and is often masked by an experimental background; so we shall call it AB. ~bove this critical value, the internal friction is strain-amplitude-dependent. This quantity is usually called aH:' and it can be explained as a thermal unpinning of dislocations.3-6 Furthermore, at higher stresses, a rapid increase of internal friction appears. This phenomenon could be caused by the plastic strain,' so we shall call it Ap. It seems interesting to us to study the influence of several t her momechanical treatments on the curve internal friction 6 vs strain E, in order to study the variation of AH and p with the concentration and the repartition of linear and point defects. In order to try to explain the results obtained, we shall propose and discuss models for H and hp and shall show that we obtain a combination of these two types of internal friction. 1) EXPERIMENTAL PROCEDURE 1) Preparation and Treatment of Specimens. We

Jan 1, 1968

By E. J. Rapperport, E. D. Levine

The boundaries of the (a +ß) field in the Al-Li system were determined between 150°and 550°C utilizing quantitative metallography and lattice-parameter measurements. The solubility of lithium in aluminum decreases from 12.0at. pct Li at 550°C to 5.5 at. pct Li at 150°C. P Al-Li is saturated with aluminum at 45.8 at. pct Li and has this boundary value constant over the temperature range 150°to 550°C. THE solid solubility of lithium in aluminum has been determined by several investigators, 1-6 but, as shown in Fig. 1, there is little agreement among the various determinations. The earliest investiga-tions'-' are suspect because of the use of impure materials. Although high-purity materials were employed in more recent work,4'5 the experimental techniques may have led to contamination of the specimens. Probably the best work has been that of Costas and Marshall,6 who obtained close agreement between results obtained by two independent phase-boundary techniques: electrical resistivity and mi-crohardness. No detailed studies of the solubility of aluminum in the bcc ß phase, Al-Li, have been reported. Cursory investigations1,2,6 have indicated only that the (a+ß) -p boundary lies between 40 and 50 at. pct Li and is relatively independent of temperature. The present work was undertaken in order to provide an independent check on Costas and Marshall's determination of the solubility of lithium in aluminum, to extend knowledge of this solubility limit to temperatures below 225°C, and to make an accurate determination of the solubility of aluminum in Al-Li. EXPEFUMENTAL Alloy Preparation. In view of the difficulties encountered in previous investigations of the A1-Li system, close attention was paid to the use of methods of alloy preparation and treatment that would minimize contamination. Aluminum sheet (99.99 + pct Al) was vacuum-induction melted in a beryllia crucible to remove hydrogen. Lithium (99.9 pct Li) was charged with pre-melted aluminum into a beryllia crucible, in a helium-filled drybox. The crucible was sealed in a Vycor tube and transferred from the drybox to an induction furnace. Melting of alloys was performed by induction heating in a helium atmosphere. Solidification was accomplished by means of a suction apparatus, shown in Fig. 2, in which the alloy was forced by changes of pressure into a 3/16-in. inside diam closed-end beryllia tube. This technique produced rapid solidification of a small portion of the melt, resulting in alloys with a high degree of homogeneity. Typical lithium distributions are presented in Table I. Transverse sections 1/8 in. long were cut from the alloy rods, and each section was split in half longitudinally. One half of each section was analyzed for lithium, and the opposing halves were employed for phase-boundary determinations. Lithium contents were determined by flame photometry with an accuracy of 1 pct of the amount of lithium present. Thermal Treatments. Homogenization and equilibration heat treatments were performed in electrical-resistance furnaces with temperatures controlled to ± 2OC. Calibrated chromel-alumel thermocouples were employed to measure temperature. Homogenization was performed in helium-filled l?yrex tubes for 1 hr at 565°C. The encapsulated specimens were then transferred directly to furnaces maintained at lower temperatures for equilibration. Equilibration times were 2 hr at 550°C, 8 hr at 450°C, 27 hr at 350°c, 90 hr at 250°c, and 285 hr at 150"~. These times were chosen on the basis of conditions employed by previous investigators. Alloys were quenched from the equilibration temperatures by breaking the capsules into a silicone oil bath. By performing all possible operations either in sealed capsules or in a helium-filled drybox, the specimens were given minimum exposure to the atmosphere. Quantitative Metallography. Metallography of Al-Li alloys is difficult because of the atmospheric reactivity of the ß phase. It was found possible, however, to prepare surfaces of good metallographic quality by preventing contact with moisture during preparation. Grinding through 4/0 paper was performed in the drybox. The specimens were then transferred under kerosene to the polishing wheel. Three polishing stages were employed: 25-p alundum with kerosene lubricant on billiard cloth, 1-µ diamond paste on Microcloth, and 1/4-p diamond paste on Microcloth. Between stages the samples were cleaned by rinsing in trichloroethylene and buffing

Jan 1, 1963

By R. L. Minckler

PETROLEUM industry forecasts are constantly made and revised but are not in the nature of predictions. Particularly in the field of demand, many of the factors are far beyond control by the producing industry. Supply reacts on demand and demand reacts on supply. Competent economists in the oil business forecasted a year ago, on the basis of experience, that demand would now be at a much lower level than it is. This increased demand increased the price of crude oil and products, and in turn those increased prices have brought forth increased supply. A reduction in demand would lead to a reduction in supply. Shortages are now world-wide, and costs of secondary importance, so if there were extra supplies in California they would be moved into what are termed "unnatural markets." For example, Argentina is in the market today for California gasoline; that is an unnatural market because of the greater transportation distances from California to Argentina than from normal sources.

Jan 1, 1947

Olof Venstrom (communication to the Secretary*):—In order to do justice to a property, once the largest producer of copper in the world, which is now being reopened, with a fair promise of again becoming important, I beg to add a few words in connection with Mr. Souder's remarks on the El Cobre copper-mines. The El Cobre copper-mines were worked by the old English

Jan 1, 1905

By F. S., Mc Nicholas

A practical discussion of the theory of A block caving is presented which applies particularly to the physical conditions of the Climax orebody although the conditions are sufficiently characteristic of caving ore-bodies to provide valuable information applicable elsewhere.

Jan 1, 1950

By William Vietti

WEST TEXAS and New Mexico has been overshadowed by the develop-ment in East Texas to such an extent that the area has been placed on a settled production basis by most of the operators. Considerable develop-ment work on both proven and unproven acreage remains to be carried on, but the incentive, a ready and profitable market, has been lacking. The main characteristics of the fields in this area are so well known that they are not described again in this paper, which thus resolves itself into a statistical review of the more important production features of the area. Proration has been in effect during the year and has been rigorously applied with the full cooperation of all producers. Proration in West Texas and New Mexico is based in the more pro-ductive fields on a potential and acreage distrbution of the allowance to the individual wells or acreage units. Potentials are determined generally by a short production test of from 1 to 4 hr.; and the hourly rate is multiplied by 24 to obtain the 24-hr. production or rated potential of the separate wells. The potential values thus set up have been questioned by many production men who are not willing to concede that the instantaneous (hourly) capacity of a well to produce is its potential capacity for a day with all other wells in the pool producing at their capacity. However, the potential of a well determined as above remains its chief rating as a measure of the permeability in place and as an indication of the possible reserve feeding that well. , The acreage factor has made it unnecessary to overdevelop properties in order to obtain an allowance proportionate to neighbors who are willing to drill an excessive number of wells on a piece of acreage in the hopes of a quick drainage and a corresponding profit. Proration has resulted in an orderly development of many of the pools in this area on the base as out-lined above, resulting in more reasonable spacing of wells and the more even withdrawal of oil and the ensuing expectation of high recoveries.

Jan 1, 1933

By Henry G. Granger

A RESIDENCE of 14 years in the Republic of Colombia, spent in almost continuous traveling and prospecting-trips, has given me an intimate knowledge of the resources of that wonderful country. The man who best knows Colombia is unquestionably General Rafael Reyes, President of the Republic for the past three years, and with seven years more to serve in his present term. Such is the strength of his personality and the wisdom of his policies that his term of office will no doubt endure as long as he is willing to serve. The vastly improved economic situation and the brilliant outlook for Colombia are so directly due to the influence of President Reyes that a few lines concerning him. will not be amiss, if they serve towards a better understanding of his personality. Born of a distinguished ancestry in the mountains of Boyaca, he is now 57 years old, just the age of his friend Porfirio Diaz when be began the work which has placed Mexico in the rank of great modern nations. It was Reyes who came to Washington to protest against the action of the government of the United States of America in reference to the establishment of the Republic of Panama, and, without entering into a discussion of this affair, it can be fairly said that there was not an American in Colombia whose feelings of justice were. not outraged at the government action and subsequent refusal to submit the matter to the impartial judgment of the' Hague. President Reyes is an accomplished linguist, speaking English, French, German, Portuguese, Spanish, and Italian. He has a remarkably. powerful voice, which can readily be heard by a large assemblage. His height is about 6 ft., and his weight exceeds 200 lb. He has clear gray eyes. Reyes was the leader of those who favored the approval of

Sep 1, 1908

By F. L. Clerc

THE lead and zinc region of SW. Missouri is interesting, not only by reason of the value of its output, which ranges in the neighborhood of ten million dollars a year, but even more because of the facilities which it offers for the study of certain forms of ore-deposits, of which the loci and genesis are somewhat obscure. Although the mineral species found in the region are few and of common occurrence, crystallization has taken place on a generous scale, and unusual forms abound in many combinations, presenting examples of pseudomorphism, paragenesis, metasomatic replacement and the action of mineral-depositing and mineral-dissolving waters. For the mineralogist, lithologist, and specialist in certain lines of metamorphism, it has peculiar attractions, while the systematic geologist will perhaps find its chief claim to attention in the simplified problem it presents, in the study of ore-deposits. In addition to the phenomena above enumerated, it presents instances of well-developed comb-structure in the ores, fissures and faults, and slickensides-features usually associated with extensive movements in the earth's crust, and believed by some authorities to prove the deep-seated origin of the ores. In connection with these occurrences, the absence of all igneous rocks from this region is noteworthy and significant. For that reason, the simplified case presented by the Joplin region, from which these rocks have been eliminated as a factor, is specially valuable. Having had unusual opportunities to watch the development of this district, I have been deeply interested in the bearing of the revelations of the Joplin mines upon questions of universal importance to the science of ore-deposits ; and it was to my great regret that the project of a meeting of the American Institute of Mining Engineers at Joplin, proposed in 1892, was

Mar 1, 1907

By Henry J. Williams

The main difficulty in the determination of silicon in pig-irons containing very high percentages of that element, has been due to their almost complete insolubility in acids, or mixtures of acids. The object of the present paper, which presents no new principle, is to suggest a method of determination which has repeatedly given accurate results, and which obviates completely the tediousness and uncertainty of the usual slow solution in acids. This method has been tried with pig-irons containing from 7 to 14 per cent. of combined silicon, and properly called ferro-silicons. When reduced to an impalpable powder in the agate mortar, an 11 per cent. ferro-silicon was found to resist the action of all acids, or mixtures of acids, with the exception of sulphuric acid of about 1.25 specific gravity. But the action of this acid, even during long continued heating, was very slow, 72 hours being necessary to com pletely dissolve half a gramme of the metal. The complete decomposition of 1 gramme of the metal may, on the other hand, readily he effected in a few minutes by fusion with sodium carbonate in a covered platinum crucible over a blast-lamp —the idea being to dissolve the silicon, leaving the iron in condi tion to be readily attacked by acids. The silicon dissolves as soluble sodium silicate, and metallic iron remains in a very spongy and finely divided condition. The addition of a little hot water

Jan 1, 1889

By J. B. STEWART

T HE position of each hole of any series of holes was carefully located by the surveyor, plotted in plan and elevation, and numbers assigned to them. The second series was staggered halfway between the first and so on for each succeeding series. Two and a, half to three months was frequently required to grout a series of holes calculated to insure safety for sinking a distance of 10 meters or say 33 ft. Naturally the initial operation called for drilling and grouting two series of holes but thereafter each sinking campaign required only one series of holes as shown in Fig. 8. The pump handling about 75 gal. per minute corresponds to 46 tons of grout or 6 tons cement delivered as a fair over-all average for the 24 hours. Thus 600 to 800 tons of cement was used for a single section of 33 ft. depth of shaft. One campaign used nearly 1100 tons of cement. Some holes were effectually sealed with as low as 30 tons, while many required 60, and some 80 to 90 tons.

Jan 1, 1926

By W. F. Dietrich

Mineral fillers are relatively inert chemically under the conditions of use but have physical properties* that modify those of the materials • The properties. uses, and other data on 15 classes of important *The pro listed in the second edition of Industrial Minerals and Rocks.l A third edition of this reference is in preparation. in which they are incorporated. The mineral fillers considered in this article are asbestos, barite, clays, diatomite, crushed limestone, limestone whiting and lime, mica, silica, talc and soapstone, and pyrophyllite. Slate and stone, other than limestone and its derivatives, are excluded because, even though used in large quantities, they are exceptionally low-cost materials generally produced close to the area where they are used. Carbon black is excluded because it is manufactured from natural gas and more than 90 pct of the output is used in rubber; hence the factors for estimating requirements are easily evaluated. OVERALL GROWTH FACTORS Table I gives the population, retail sales, and value added by manufactures in the U. S. and in the eleven western states in 1954. These data are rough guides to the proportionate part of total U. S. markets for products containing mineral fillers that may be expected in a given area. For example, the population of the eight Mountain states in 1954 was 3.6 pct, and retail sales in these states were 3.8 pct of the U. S. total, but the value added by manufactures was only 1.3 pct of the U. S. total. On the other hand, the three Pacific Coast states, with 10.3 pct of the total population, had 12.0 pct of the retail sales and produced 9.6 pct of the value added by manufactures. On an industry-by-industry basis the correlation between the three guideposts will not be as close as shown in the 1954 data for the Pacific Coast states, but in the long-term view the continuing rapid population growth in the western states is certain to result in expanded industrial production at an even more accelerated pace, which will shorten the gap between local consumption and production in most major groups of manufactured consumer goods. Of course, there will always remain favorable areas for production of specific products. Such special situations must be individually analyzed. Fig. 1 compares the population trends in the U. S., the western states, and California with Real Gross National Product from 1910 to 1957, with forecasts to 1970. It is estimated' that the U. S. Real Gross National Product, as measured by the value of goods and

Jan 1, 1960

By Paul Queneau

FROM the first days on the Norman beaches to the last days on the Elbe the Army Engineers of World War II lived off the countryside for the great bulk of the construction supplies needed for the fulfillment of their ultimate mission-to keep the army moving. To accomplish this end, vast tonnages of rock, timber, and steel were required in the construction of roads, railroads, and bridges. Combat Engineer battalions operated quarries under shell fire as a routine matter. An Engineer forestry company was decimated while cutting bridge timber on the Siegfried line. Oneof the more spectacular feats of the Army Engineers in obtaining construction materials was the operation of the Hadir Steel Works during the fall and winter o f 1944.

Jan 1, 1946

By D. A. Elgillani, M. C. Fuerstenau

In this paper, oxidation potentials measured in the presence of various concentrations of cyanide, ferro-cyanide, and ferricyanide and ethyl xanthate at various values of pH are related to flotation response. Eh-pH diagrams are presented to show that the formation of surface ferric ferrocyanide is probably responsible for depression when cyanide is added. The influence of cyanide on the depression of pyrite with xanthates as collector has been the subject of a number of investigations,'-6 and several theories on the mechanism of depression have evolved from these studies. Wark and Cox7 and Gaudin8 have suggested that the depressing effect is due to a competition of cyanide ion with xanthate ion for the surface. Cook and his colleagues9-11 have explained this phenomenon in terms of competition between hydrocyanic acid and xanthic acid. Sutherland 12 has shown that although both of these theories accurately describe the relation between pH value and cyanide addition at constant collector addition, they fail to describe the relation between pH value and the amount of collector required to cause flotation. Taggart 13 suggested that depression in these systems is due to the formation of a reaction product between ferric ion at the pyrite surface and ferrocyanide ion derived from solution. Majumdar4,6 has attempted to prove this hypothesis by measuring the contact angles of pyrite in the presence of 25 mg per liter ethyl xanthate and different concentrations of potassium ferrocyanide and ferricyanide. In all cases the contact angles were quite high up to pH 10. These results indicate that pyrite should not be depressed by either potassium ferrocyanide or ferricyanide. In view of these facts, Majumdar has assumed that the compound Fe(CN)2 forms at the surface. Gründer and Bornl4 have stated that depression may be due to the formation of the compound K2Fe(II)Fe(CN)6 at the pyrite-solution interface. This compound is thought to be an interaction product between the K2Fe(CN)6-2 ion from solution and the Fe++ ion at the pyrite surface and, accordingly, K4Fe(CN)6 should depress pyrite at least as effectively as KCN. This was proven experimentally, but there was no simple relation between the depression of pyrite and the concentration of either KCN or K4Fe(CN)6 in solution. In view of the many mechanisms that have been proposed for pyrite depression by cyanide, it is apparent that a clear understanding of the phenomena occurring in these systems is lacking. One reason for this may be the fact that the species responsible for pyrite flotation in the presence of xanthate is not the xan-thate ion but rather dixanthogen.15 Since the oxidation of xanthate to dixanthogen is dependent on the oxidation potential of the solution, it would seem that knowledge of these potentials would be a requisite to understanding the pyrite-xanthate-cyanide system. It is the object of this paper to measure both the oxidation potential and pH of the pyrite systems in the presence of various concentrations of cyanide, ferrocyanide, and ferricyanide and xanthate and to relate these values to flotation response. EXPERIMENTAL MATERIALS AND 'TECHNIQUES In the experiments discussed here, pure potassium ethyl xanthate was used as collector, and reagent grade potassium cyanide, potassium ferrocyanide, and potassium ferricyanide were used as depressants. Reagent grade HC1 and KOH were added for pH adjustment. Conductivity water, made by passing distilled water through an ion exchange column, was used in all experimental work. Two natural samples of pyrite were used in the investigation. Sample preparation for flotation included dry grinding with a mortar and pestle and sizing the product to 100 x 200 mesh. Prior to flotation, a 0.75-gm sample of pyrite was added to a solution containing a known amount of depressant at the desired pH value, and the system was conditioned for 4 min. Following this, a known amount of collector was added and the system was conditioned for another 4 min. The pH — termed flotation pH - was measured; the pulp was transferred to a Hallimond cell, and flo-

Jan 1, 1969

Temperatures in the Open-hearth Furnace. By Robert B. Sosman. (Metals Tech. Aug. 1948, T.P. 2435) Steelmaking Direct Oxidation in the Basic Open Hearth Process. By E. R. Hughes and F. G. Norris. (Metals Tech., June 1948, T.P. 2380) With discussion Operation of Oxygen-enriched Open-hearth Furnaces. By J. S. Marsh. (Metals Tech., Aug. 1948, T. P. 2416) With discussion Role of Thermochemical Factors in Basic Open Hearth Production Rate. By T. E. Brower and B. M. Larsen. (Metals Tech., Oct. 1948, T.P. 2451) Structure, Segregation and Solidihcation of Semikilled Steel Ingots. By M. Tenenbaum. (Metals Tech., Sept. 1947, T.P. 2273) With discussion The Origin of Silicate Inclusions in Basic Electric-arc-furnace Steel of Higher Carbon Contents. By Axel Hultgren. (Metals Tech., Aug. 1948, T.P. 2418) A Method for Determining the Origin of Surface Defects in Rolled Steel Products. By C. L. Meyette and V. L. Elliott. (Metals Terh., June 1948, T.P. 2368) With discussion Gases in Steel The Sampling and Analysis of Steel for Hydrogen. By G. Derge, W. Peifer and J. H. Richards. (Metals Tech., June 1948, T.P. 2362) With discussion Apparatus for the Hot-extraction Analysis for Hydrogen in Steel. By C E. Sims and G. .I. Moore. (Metals Tech., June 1948, T.P. 2369) With discussion A Quantitative Experimental Investigation of the Hydrogen and Nitrogen Contents of Steel during Commercial Melting. By C. E. Sims, G. A. Moore and D. W. Williams. (Metals Tech., Feb. 1948, T.P. 2347) With discussion The Effect of Hydrogen on the Ductility of Cast Steels. By C. E. Sims, G. A. Moore and D. W. Williams. (Metals Tech., Sept. 1948, T.P. 2454) Sulphur in Ironmaking Kinetics of the Transfer of Sulphur across a Slag-metal Interface. By Lo-ching Chang and K. Goldman. (Metals Tech., June 1948, T.P. 2367) With discussion Some Correlations between Variables Affecting Sulphur in Blast Furnace Iron. By T. E. Brower and B. M. Larsen. (Metals Tech., Sept. 1948, T.P. 2465) Tracer Study of Sulphur in the Coke Oven. By S. E. Eaton, R. W. Hyde and 11. S. Old. (Metals Tech., Sept. 1948, T.P. 2453) Transformation of Austenite Anisothermal Formation of Bainite and Proeutectoid Constituents in Steels. By Leonard D. Jaffe. (Metals Tech., Dec. 1947, T.P. 2290) With discussion Austenite Transformation Above and Within the Martensite Range. By R. T. Howard, Jr. and M. Cohen. (Metals Tech., Oct. 1947, T.P. 2283) With discussion

Jan 1, 1949

By W. L., Yerkes

AN interesting study of the application of air-, conditioning to the problem of mine ventilation and cooling can be found on the Witwatersrand in South Africa. Here there are a large number of deep mines in a relatively small area. Due to the nature of the reef, many mines are working at a depth of 6000 ft. and some have gone down to 8000 and 9000 ft. below the surface. At such depths, even in a country geologically as old as Africa, the virgin rock temperature approaches 110°F. The flow of heat from the- rock to the ventilation air is tremendous though the shaft or drift may have been open to ventilation for some years. In addition, there is the heat produced by machinery, lights, and men at work and the heat of adiabatic compression of air introduced into the mine. The difference in atmosphere pressure between the collar of a shaft and a level 6000 ft. below is nearly 3lb. per sq. in., resulting in an increase in heat content of nearly four B.T.U. per pound of air delivered to the mine at surface. Further the exclusive use of wet mining to reduce the incidence of miner?s phthisis increases the latent- heat content of the air.

Jan 1, 1941

By Lucius W. Mayer

The iron-mines of the Ilsede Hütte Co. are at a town called Peine, about 20 miles east of the city of Hanover, on the railroad to Brunswick (Braunschweig). Hanover, the capital of the province, is a military city, of approximately 250,000 inhabitants, and Brunswick, 33 miles to the westward, has half this number. The mines here described are located in a hamlet called Bülten. The Ilsede Hütte Co. operates two mines, 1.5 miles apart, in this district, Gruber Bülten Adenstadt and Gruber Lengede Bodenstadt. It also operates an iron-mine north of Hanover, known as Eiserhaven, and one in the Harz mountains, the Georg Friedrich, at Grauhof. At Bülten a coarse conglomerate, a, Figs. 1 and 2, contains nodules of limonite, cemented together by calcium phosphate. The ore contains Fe, 25 to 45; Mn, 3 to 4; P, 0.6 to 1.4; S, 0.02 to 0.09; and CaCO3, 40 per cent. Directly above the conglomerate is limestone, b, followed by a mixture of clay and sand, c. Below the conglomerate is a hard clay floor, d. The ore-body, from 10 to, 12 km. long, and from 3 to 4 km. wide, has a maximum thickness of 20 m. It clips approximately 10° S.E., and strikes N. 45° E. Diamond-drill prospecting shows that the thickness diminishes to 1 m. as the end of the deposit is approached to the northward. At this point the deposit is 250 m. below the surface. In Fig. 2, the arrow, A, indicates the general direction of the work along the face, a, which is carried forward in a straight line for its entire length. At B, a train is approaching, which has come from the bench-track, shown at G, by a circuitous route, and is dumping the overburden behind the face, in the space left by the excavated rock. Formerly the work at this mine was essentially open-cut, the deposit having a very strong outcrop. Figs. 1 and 2 show also

Sep 1, 1908