Search Documents

By AIME AIME

THE second session on geophysical prospecting at the February meeting of the Institute was a discussion of the mining law and the bearing of the new method of search on location of claims and assessment work thereon. Allen H. Rogers was chairman of the meeting, which he opened by reviewing the present law and the proposed changes. W. R. Ingalls commented (by letter) on the Arentz bill, as introduced into the House of Representatives in 1921 and the need for revision of the present mining law. L. W. Douglas explained (by letter) the bill that he introduced and which has been passed by the House. SAMUEL S. ARENTZ, Nevada: It is my opinion that if the American Institute of Mining and Metallurgical Engineers is to sell this proposition to the people in the West, they have to sell it to the lawyers, because, after all, they are heard loudly when it comes to speaking in Congress. One man tells the other, "This thing is a vicious piece of legislation"; it might not be, but they will pass it on if it affects them. If the Institute would impress on the people affected that we need a re-codification of the mining law and that such is necessary along certain lines; that things have changed during the past decade or two, so today instead of doing our prospecting alone through the sinking of a shaft, through a discovery that may be seen, we are now moving on to more modern means of discovery through geophysics, through the churn-drill, through geology, through geological inference, I think we could get somewhere.

Jan 1, 1929

By Frederick Laist

The ores received at the Washoe Smelter come almost entirely from the mines in Butte and contain the following minerals : Chalcocite, Cu2S; covellite, CuS; chalcopyrite, CuFeS2, (trace); bornite, Cu3FeS3; enargite, Cu3AsS4; malachite, Cu2CO4 + H2O (trace); pyrite, FeS2; sphalerite, ZnS; rhodo-chrosite, MnCO3, (less than 1 per cent.); rhodonite, MnSiO3, (less than I per cent.). The country-rock of Butte is of the granite family and is a quartz-monzonite containing a little less silica than typical granite. It is made up of the following rock-minerals in approximately the proportions indicated: Minerals. Composition. Per Cent. Quartz SiO2 20 Andesine 1/2 NaAlSi3O8; 4 CaAI2Si2O8 42 Orthoclase KA1Si308 23 Hornblende 1/2 Ca(MgFe)3Si4O12; & (MgFe)2(AlFe)4Si2O12 6 Biotite (HK)2(MgFe)2A12Si3O12 9 Titanite CaTiSiO5 0.1 Apatite (CaF)Ca4(PO4)3 0.05 Magnetite (FeO)(Fe2O3 0.15 Pyrite FeS2 0.02 99.32 The main country-rock (quartz-monzonite) is cut by dikes of aplite, a granite having the following composition: Quartz, 30; andesine, 20; orthoclase, 45; ferro-rnagnesian minerals, 3; pyrite, 0.1; total, 98.1 per cent. Closely associated with the copper-deposits are dikes and bodies of " Modoe" porphyry, technically known as quartz-

Jan 1, 1913

By E. M. Cox, A. S. Skapski, N. H. Nachtrieb, M. C. Bachelder

As a result of using copper-containing scrap in the steelmaking process, the copper content of steels has been steadily increasing for years. Consequently the possible role copper may play in the steelmaking process and in the finished product begins to attract the metallurgists' attention. Some time ago one of the present authors forwarded the idea—based on the results of the analysis of nonmetallic inclusions extracted electrolytically from steels—that sulphur in plain carbon steels is distributed mainly between copper and manganese, the amount of iron sulphide being very small; and that, consequently, the problem of copper and that of sulphur in steel cannot be treated separately.' At the time of the publication of the quoted paper little was known about the relative affinities of copper and manganese for sulphur at high temperatures except that at moderate temperatures (below 1000°C) the affinity of manganese for sulphur is much greater. To gather more experimental data on this subject, the present authors undertook the investigation of the equilibrium constants of the reactions: 2Mn(8 or 1) + S2(g) = 2MnS(s) 4Cu(s or 1) + S2(g) = 2Cu2S (S or I)* 2Fe(s) + S2(g) = 2FeS (s or 1) over a range of temperatures wide enough to establish the dependence of these equilibrium constants on temperature. From the equilibrium constants (K = l/Ps2) the free energy of formation (affinity) can be calculated from F° = -RTln 1/PSt (1) where the standard conditions chosen are: 1 atm of sulphur pressure and the activities of condensed components equal one. The decomposition pressure, Ps2, of sulphur over the respective sulphides is too small to be measured directly, but there is a way of eliminating this difficulty by measuring the equilibrium constant of the reaction between the sulphide and hydrogen. From the latter and from the equilibrium constant of the thermal dissociation of H2S we then calculate Ps2 for the respective sulphide. 2Mn + 2H2S = 2MnS + 2H, 2H2 + S2 = 2H2S_________ 2Mn + S2 = 2MnS The numerical values of the equilibrium constant of the thermal dissociation of H2S at different temperatures were taken from Kelley's paper, "The Thermodynamic Properties of Sulfur and its Inorganic Compounds."² In previous experimental work published by Jellinek and Zakowski3 and by Britzke and Kapustinsky4 the equilibrium constants of the reactions Metal sulphide + H2 = H2S + metal were determined by passing hydrogen, at different rates of flow, over the sulphide, analyzing the resulting H2S + H2 mixture and then extrapolating the H2S/H2 ratio (which is a function of the rate of flow) to the zero speed of flow, a method necessarily involving considerable uncertainty. In the present work the equilibrium ratio was actually measured instead of being extrapolated. The apparatus is shown in Fig 1. Experimental Procedure The sulphides were prepared by the following methods: FeS Powdered iron which had been reduced with hydrogen (ferrum reduc-tum) was mixed in stoichiometric ratio with sublimed sulphur and carefully ground. The mixture was put into an alundum crucible, covered with pure sulphur, and the reaction started by touching the mixture with a glowing iron rod. After the reaction was completed the product (still containing some metallic iron) was again ground with sulphur, put into a Rose crucible, covered with sulphur, and heated in a strong current of pure hydrogen. Analysis of the final product showed 62.46 pct Fe and 36.59 pct S. Theoretical for FeS: 63.53 pct Fe and 36.47 pct S. MnS Manganese sulphide (precipitated and carefully washed with distilled water containing H2S) was dried in a Rose crucible in an atmosphere of H2S and heated in a current of hydrogen for 2 hr at red heat. The product was then ground and ignited for several hours at 1000°C in a current of hydrogen sulphide. Analysis showed 64.53 pct Mn and 36.63 pct S. Theoretical: 63.15 pct Mn and 36.85 pct S. Some MnS samples were prepared from metallic manganese and sublimed sulphur by mixing and grinding them and then heating in a current of hydrogen sulphide in an alundum tube.

Jan 1, 1950

By F. Habashi

Conclusive evidence is given showing that the dissolution of gold in cyanide solution follows mainly the over-all equation A similar equation can also be written for the dissolution of silver. Theoretical derivation of the velocity equation for this reaction has been obtained, which describes quantitatively the experimental facts. The equation is as follows: where [CN-] and [O2] = the concentrations (in moles/ml) of cyanide and dissolved oxygen, respectively. DcN- and Do2 = the diffusion coefficients of cyanide and dissolved oxygen; 1.83 x 10-5 and 2.76 x 10-5 cm2 sec-1, respectively. A = the surface area of the metal in contact with the aqueous phase, in cm S = the thickness of the boundary layer; varies between 2 and 9 x 10-3 cm, depending on the speed and method of agitation. Rate being expressed in g. equiv. sec-1. INTRODUCTION During recent years a number of papers have been published on the kinetics of dissolution of gold and silver in cyanide solution.1,6 The authors agree that the rate of dissolution is diffusion-controlled, but disagree regarding the mechanism of the reaction. Some authors'-3 support the Bodlander equations: The apparently conflicting results, when critically reviewed, are concordant and lead to the conclusion that the proper equation for the dissolution reaction should be only Eq. 1. This conclusion is based on the following facts: 1) For every 2.2 equivalents of metal dissolved one mole O2 was consumed. 2) For every 1 equivalent of metal dissolved, 2 moles of cyanide were consumed.' 3) Hydrogen peroxide is formed during the dissolution of gold or silver, and for every 2.2 equivalents of metal dissolved, one mole H2O2 was produced.1,2 The fact that Kudryk and Kellogg4 did not detect H2O2 during the dissolution of gold should not throw doubt on the many affirmative reports of other investigators. Lund2 has shown that depending on the crystalline nature of the silver surface, (e.g. method of etching the sample) H2O2 may undergo catalytic decomposition heterogeneously according to: Further Kudryk and Kellogg4 carried out their experiments in the presence of 0.5% KC1 to achieve a greater electrolytic conductivity, and Matsudaira7 has shown that H2O2 is catalytically decomposed (homogeneously) in the presence of C1- ion in alkaline solution. 4) Experiments carried out by Boonstra8 and Lund2 showed that the dissolution of gold and silver respectively in KCN + H2O2 in the absence of oxygen was a slow process. Thus the reaction takes place to a minor extent only. Further kinetic studies showed that: 1) The rate of dissolution depends on the surface area of the metal in contact with the liquid phase, thus indicating that the process of dissolution is a heterogeneous process. 2) The rate of dissolution depends on the speed of stirring,5,6 thus indicating that the process is controlled by a physical phenomenon.

Jan 1, 1967

By N. A. Gokcen, M. Ohtani

Thermodynamic intevaction pararnetevs of elements E2(2), for dilute binary solutions of a component "2" in liquid iron, i.e., E(22) = 9 In f2/?N2 where f2 is the activity coefficient and N2 the mole fraction, and E(3) 2 = In f2/ N3 dilute ternary solutions of "2" and "3," and the carbon saturation parameter sc(3) (In f c/ N3) N c/N Fe for N3 - 0, are critically examined and correlated. It has been found that the interaction parameters and the atomic numbers of alloying elements follow regular periodic putterns. PHYSICO-chemical behavior of alloying elements in molten iron have become the subject of numerous investigations during the past 25 years. Consequently, the mutual effects of elements in the iron-rich solutions Fe-C-X, Fe-N-X, Fe-H-X, Fe-O-X, and Fe-S-X where X represents an alloying element, have gradually become better understood. These effects for a given temperature and pressure may be expressed by the interaction parameter of Wagner1, 2 derived briefly in the following manner. The complete differential of the Gibbs free-energy equation at constant temperature and pressure is dF = Fl dn, + F2 dn, + F3 dn3+ . . . [ 1] where F is the free energy; F 1, the partial molar free energy of "I"; and n,, the number of moles of "i." Cross-differentiation of this expression* *Cross-differentials are obtained as follows: Since the order of differentiation of F with n2 and n3 is immaterial, the left sides of the second differentials are equal, hence the derivation of Eq. [2] is obtained. For a dilute solution of components 2 and 3 in solvent 1, with the substitution of RT In f i = Fi xs for Fi where fi is the activity coefficient, and Fixs is the excess partial molar free energy, Eq. [2] becomes O) [3] where N2 and N, are the mole fractions. The interaction parameters are defined by

Jan 1, 1961

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Jan 1, 1919

AUGUST began with a reminder that warfare was still in progress in the world, in that the Greeks, still at war with Turkey, threatened Constantinople in spite of the small British and French forces of occupation and opened a vista of international dangers. There was in this, moreover, a recollection that religious questions in India had prevented the British from permitting a real settlement of the Turkish question, wherein the absence of Russia as a great power is missed. Civil warfare also continued in Ireland and China. Even in the military way the world is far from being at peace. Bloody fighting between the Fascisti (anti-communists) and the com-munists in Italy led to several provinces being put under martial law, but after a while these disturbances were quelled. In the latter part of the month the assassination of Michael Collins in Ireland produced a great shock. From China, however, there came rather favorable news, indicating the early reintegration of that country, which sooner or later ought to play an important part in world affairs. Economically, instead of there being any improve-ment, there grew a clearer perception of how bad things really are. Italian politics were in chaos through inability to find anyone to accept the premiership and assume the all but hopeless task of averting national bankruptcy. The French, too, began to see their own position in true colors, and especially to see how in reconstruction they had incurred debts on the strength of what they hoped to collect from Germany, with at last the understanding that the Germans could not pay and that France herself was thereby put in a desper-ate economic position. As for the Germans, them-selves their Reichsbank defaulted on ordinary bills early in August. As the month wore on the value of marks fell more and more and at the end it appeared that Germany was on the verge of economic collapse. On Aug. 7, another international conference (with America again absent) was assembled in London, this being the thirteenth since the war, and there was a general feeling that it would be the last. The prime question was what is to be done about the German reparations, but underlying was the whole subject of the entente. The conference opened like a meeting of importunate creditors, doubtful whether the debtor had any tangible assets. On Aug. 14 this conference broke up without coming to any useful conclusion. Indeed, the acrimony among the premiers was so sharp that even the entente between Great Britain and France was endangered. The international situation was saved only by the Reparations Commission excusing the Germans from the payment of 50,000,000 gold marks that come due on Aug. 15 But although the entente was nominally preserved there is no longer any illusion about the interests of Great Britain and France being different and that henceforth they will play their own hands. The London conference was really an effort to maintain the partnership, and it failed.

Jan 9, 1922

By J. F. Myers, F. M. Lewis

C. G. McLACHLAN*-I have read this paper with considerable interest and wish to congratulate the authors on the care with which they carried out their experiments and for the detailed sizing data they have presented. 011 the other hand I do not feel that these data establish their contention that "with other factors the same, the work accomplished in a fine crushing rod mill is directly proportional to the rotating speed." My reason for making this statement is that their conclusion is based on the percentage of minus 65 mesh material produced at each of the speeds at which their tests were run. The rod mill is, however, not a fine grinding machine and therefore figures based on minus 65 mesh production are figures outside the range at which it operates to best advantage. Further, if rod mill performance is to be judged on the production of such material it should have been established that a rod mill will produce it as effectively as a ball mill. To check this last point I have gone over some of the rod and ball mill grind-ing figures for our Waite-Atnulet operation and find that the ball mill at that property produces more minus 65 mesh material per horsepower than the rod mill. Moreover, this comparison is even more favorable to the ball mill if it is limited to minus 100 mesh production. It therefore seems to me that the most satisfactory basis on which to try to com-pare the performance of the rod mill in the present case is by taking a weighted average of all the new surface produced per horsepower. W. H. Coghill3 has published data which can be applied to the sizing figures presented by the authors, and if this is done the units of new surface per horsepower produced in the Tennessee tests are as follows: Admittedly the increment of increase in new surface per horsepower shown in the foregoing figures is not great, but its trend is nevertheless definitely in favor of slower speed operation, for the conditions under which these particular tests were run. I also feel that some information regarding liner contour should have been given as I think it will be found that a mill which is equipped with liners which lift the rod load can be run at a slower speed than a mill in which the liners are comparatively smooth. J. F. MYERS and F. M. LEWIS (authors' reply)—The position taken by Mr. McLachlan is to be respected even though we are all aware of the faults of surface considerations. As he points out. the increment of increase is very small. It is so small in fact that for all practical purposes it does not conflict with the conclusions of the paper. The authors appreciate Mr. McLachlan's comprehensive study of the data.

Jan 1, 1950

By J. Gross

G. H. Clevenger, Chairman of the Milling Methods Committee of the Institute, made the following introductory remarks: "Several years ago, a number of us felt that the time was ripe for a fundamental investigation of crushing and grinding. At the outset, it appeared that the first thing we needed was a yardstick whereby grinding efficiency could be measured. "The U. S. Bureau of Mines has been most generous in cooperating with the Milling Methods Committee in getting this work well under way. John Gross, who served the committee for a year as secretary, was placed in charge of the investigation and has been ably assisted by S. R. Zimmerley. "Messrs. Gross and Zimmerley will now present the Progress Report covering their work to date." PROGRESS REPORT J. Gross, Salt Lake City, Utah. -This has not been a simple problem, and when I tell you that we can give you a verbal report of what we have done during three years in five or ten minutes you will realize that we have necessarily done a great deal of work that does not appear in the final results. We have been in a virtually new field. Therefore, we have had to feel our way at each step so as to be fairly sure we were correct. The first thing that was realized in this problem was that unless we had some method of measuring what happened when we crushed an ore, we might as well quit and not go further. We realized that if we tried to measure the results of crushing or grinding by the ordinary sizing test we would not get anywhere. We could sieve down to say 200 mesh fairly accurately; we could even go one sieve size further with a little less accuracy, and then we were absolutely lost, unless we went into microscopic measurement. Even this latter method would not have been satisfactory. The question was: what were we going to measure? If we were going to measure size, we might measure one particular dimension of a particle and be off 200 per cent. or more. If we tried to measure surface, we would have something tangible; the surface of a particle, no matter how irregular, is something definite, far more definite than any linear dimension would be. Moreover, if we could measure surface, we would immediately have a method of checking the Rittinger law as to whether it was or was not correct. So the first thing that we sought was a method whereby we could measure surface on crushed particles or, we will say, on particles; it would not make any difference whether crushed or not. It then became a question of what kind of particles we were going to use in obtaining a method for surface measurement. We realized that it would be rather a com-

Jan 1, 1928

By M. G., Corson

1. In addition to the alloys of copper with iron previously found by Hanson and Ford to show an increase in the concentration of the alpha range with increase in temperature the following binary and ternary systems have been found by the author to exhibit: the same feature: (a) Copper-chromium. (b) Copper-cobalt. (c) Copper-silicon. (d) Copper-nickel-silicon and its pseudo-binary section Cu-Ni2Si (formula of compound definitely established). (e) Copper-cobalt-silicon and its pseudo-binary section Cu-Co2Si (formula of compound established with some probability but not as definitely as for Ni2Si). (f) Copper-chromium-silicon; formation of a compound definitely established (compare Figs. 1 and 2). The formula of this compound may be either Cr2Si or Cr3Si. (g) Copper-iron-silicon; presence of a phase containing both iron and silicon established in an indirect way only. No definite microconstituents observed. 2. RANGES OF SOLID SOLUBILITY (percentage at various tempera¬tures). (a) For copper-chromium: 0.8 at 1000° C.; 0.5 at 900° C.; 0.25 at 800° C.; 0.05 to 0.1 at 500° C. (b) For copper-cobalt: 3.4 at 1000'C.; 2.4 at 900'C.; 1.7 at 800'C.; 0.9 at 600°C.; 0.35 at room temperature. (c) For copper-silicon (Fig. 3) : 6.8 ± 0.1. per cent. at 800° C.; 3 per cent. at 400° C. and probably below 2 per cent. at room temperature if sufficiently long annealed. (d) For copper-cobalt silicide: 3.3 at 1000° C.; 2.4 at 900° C.; 1.6 at 800° C.; 0.7 at 600° C.; 0.3 at 300° C. (e) For copper-nickel silicide (Fig. 4): 8.2 at 1000° C.; 5.5 at 900° C.; 3.6 at 800° C.; 1.6 at 600° C.; 0.7 at 300° C.

Jan 1, 1927

By A. Mitchell

An approximate phase diagram has been developed for the CaF2-CaC2 system, indicating a eutectic point at 1240°C, Ncac2 = 0.13, and no detectable solid solution in either phase. The liquidus line is shown to correspond to a simple c22- ion in solution. A thermo-chemical study of&apos; the reaction between carbon-saturated Ni-Ca alloys and CaC2-CaF2 liquids indicates that lhe Raoullian activity coefficient of CaC2 in dilute solution in Cap2 al 1500°C lies between 8 and 10. Some effects of the stabilily of Cap2-CaC2 solutions at high temperatures on electroslag remelting praclice are outlined. THE alkaline earth acetylides. MIIC2, have a reasonably high thermochemical stability at high temperature in the solid state,&apos; with the exception of magnesium, which forms an unstable acetylide at low temperatures (-500°C) and a carbide, Mg2C3, in the range 700&apos; to 1000°C. The acetylides of calcium and barium have been shown to have limited solubility in their respective chlorides,&apos; and further these solutions contain the acetylide as a C: ion.&apos; The equivalent magnesium solutions have not been studied. Although calcium "carbide" is used as a desulfuriz-ing reagent in steelmaking. and is possibly present as an acetylide-oxide phase in very basic electric arc practice slags, the acetylide ion appears to be substantially unstable in a silicate slag.* As a conse- *This instability arises from equilibria in the reaction: CaC2 + CO = (Ca0) + 3C where the low intrinsic solubility of CaC2 in silicate lattice, and the low activity of CaO in a silicate solution where CaO/Si02 < 1, combine to give a very small equilibrium concentration of CaC2 in solution in such silicate slags at temperatures in the region of I 500°c, even under carbon-saturated conditions. Under highly basic conditions, a liquid CaO-CaC2 phase may separate from the silicate system quence of this, the possibility that reactions involving CaC2 in silicate solutions are of importance to general steelmaking practice is remote. However, in operations involving a slag primarily based on a halide, or alkaline earth oxide, we must take into account the possibility that CaC2 will appear in quantities sufficient to significantly affect both the chemical and physical properties of the slag. The work outlined below presents a study of the CaF2-CaC2 system intended to provide sufficient data to allow an estimate of the importance of this system to electroslag remelting and welding practice. However, we should indicate at this point that there will be other processes, e.g., heat treatment, flux cleaning of castings, fused salt electrolysis, and so forth, where alkaline-earth halide fluxes are in contact with carbon, graphite, or carbides, and where halide-acetylide solutions must be taken into account. EXPERIMENTAL 1) Structural Studies. In view of the difficulty ex-perienced in handling CaC2 prepared from calcium turnings and propane gas at 700°C, it was decided to use solutions prepared directly in the equilibration apparatus, Fig. 1. The starting materials were: a) Ni-Ca-C alloy, prepared by adding calcium to liquid nickel held under calcium fluoride in an induction-heated graphite crucible; b) calcium fluoride, prepared by fusing calcium fluoride powder (British Drug House "EXTRA PURE") calcium fluoride in an induction-heated graphite crucible, in air, followed by electrolysis between graphite electrodes at 1 amp cm-2 density, for 10&apos; coulombs per g CaF2. This procedure decomposes the CaO produced by hydrolysis during the fusion step, replacing it by CaC2; Ca2+ + 2e-Ca*(l) Ca*(l) + 2C(gr)-(CaC2)caF2 O2- -2e-O*(g) O*(g) +C(gr)-CO(g) This results in a composition of between 2 and 5 wt pct CaC2 in CaF2. Fifty grams (in lumps) of this material were placed in a graphite crucible, together with Ni-Ca-C alloy (averaging 20 wt pct Ca), and the equilibration apparatus assembled. The alloy reacted with the crucible at high temperature to give CaC2, which dissolved in the calcium fluoride solution to give the desired composition. Cooling curves were plotted manually for these liquids, with rapid stirring and CaF2 seeding to minimize supercooling, and using a Pt/Pt 13 Rh thermocouple calibrated on the freezing points of nickel and copper. This gave a reproducibility of ±0.l°C. and an absolute accuracy of the thermocouple of ±l°C. An example curve is shown in Fig. 2, with the CaF2 end of the binary system in Fig. 3. The CaF2-CaC2 ingots were crushed, under dry nitrogen, and sampled for chemical analysis and X-ray examination. Analytical details are given in the Appendix. Powder diffraction data indicated that the only phases present in all samples examined were calcium fluoride and tetragonal (Types I and 111) calcium acetylide,4 with no evidence of solid solutions or compound formation. 2) Thermochemical Studies. The apparatus used to obtain activity data on CaC2 in these systems is shown in Fig. 4. It consists of an arrangement whereby the graphite crucible and its contents (CaF2-CaC2. Ni-Ca-C) can be rapidly cooled without exposure to air. Trial experiments to determine an equilibration time by ap-

Jan 1, 1969

BECAUSE of the impetus given to placer mining since the price of gold was advanced to $35, several types of small dredges have made their appearance, especially in the Lincoln and Oroville areas of California. Some of these are known as "doodle bugs," and have been given considerable publicity, though many believe their performance has been overrated and that complete costs of construction and operation, if known would not put them in so favorable a light. Fig. 1 is a doodle bug owned by E. M. Clark and operated near Lincoln, Calif. It is understood that it was abandoned because of inability to handle deep ground. A similar machine that has been operated-profitably by Comstock Placers is shown in Fig. 2.

Jan 1, 1938

By H. A. Doerner

PROPOSALS to use hydrocarbon or natural gases for the reduction of zinc from oxide materials may be traced back through Patent Office files to the early years of the present century. Natural gas at rates cheap enough to compete with solid fuels has been available at or near one major zinc district for more than a decade. That the seemingly meritorious and economically interesting applications of these proposals have not devel-oped into workable processes for direct production of zinc by natural gas cannot be completely ascribed to the proverbial conservatism of the zinc industry. It is possible to produce spelter commercially in normal times from zinc oxide and carbonaceous reducing agents without having a very precise understanding of the chemistry of the process. The reduc-tion by hydrocarbons is not, however, in this class, and the technical complexity of this reduction metallurgy and chemistry prohibits solution of the inherent difficulties by the "hit and miss" methods that are some-times thought to be practical. In a thermodynamic study of the chemistry of zinc smelting, Maier1 made a preliminary study of the chemistry of the use of methane for reducing zinc oxide by thermodynamic means, pointing out that the following reactions, the limits of which could be theoretically predicted, were important: ZnO + CH4 = Zn(gas) + CO + 2H2 [1] CH4 = C -I- 2H2 [2] ZnO + CO = Zn(gas) + CO2 [3] ZnO + H2 = Zn(gas) + H2O [4] Other possible reactions, not discussed in the reference quoted, are: CO2 + CH4 = 2CO + 2H2 [5] H2O + CH4 = CO + 3H2 [6]

Jan 1, 1933

By Earle C. Waite

THE Industrial Minerals Division this year held no individual sessions of its own except the business meeting Tuesday afternoon. One session was held jointly with the Society of Economic Geologists, one with the Milling Methods Committee, and two with the Society of Economic Geologists and the Mining Geology Committee. At all of these meetings the attendance was better than usual and the Tuesday afternoon session, with nearly 400 present, probably set a new record for the Division. Joint sessions seem extremely popular when papers of mutual interest are presented. On Monday afternoon, mica was the predominating subject. The North Carolina mines provided most of the information presented, although the discussion brought out similarities with the New England mines. B. C. Burgess particularly stressed the fact that with the existing curtailment of mica from India it is necessary to get the most mica in the shortest time from the mines in this country. He said that the Colonial Mica Corp. hopes to have 1000 mines operating in the near future. This seems a great number, but when one considers that these mines employ from 3 to 28 men, mostly nearer the low figure, the output of each mine is relatively small. Although the price of mica is from six to ten times the prewar price, the yield of 8 to 150 lb. of mica per ton of raw ore does not provide high returns to the producer.

Jan 1, 1943

By D. R. George

Preliminary research has identified several organic and aqueous solutions that are effective absorbents for SO, from simulated smelter gas containing 0.3 to 2% SO2. These SO2 loaded solutions are also compatible to the reaction of H2S and SO2 to precipitate a readily filtered elemental sulfur. The economic removal of SO2 and production of elemental sulfur from stack gases discharged by base- metal smelters is a challenging goal. The magnitude of this task is illustrated by the estimate that about 3.5 million tons of SO2 are discharged to the atmosphere by smelters annually in the U.S. The SO2 concentration of the gases ranges from about 0.5 to more than 3%. As the sulfur content of SO2 is 50% a potential production of 1,750,000 tons of sulfur per year is indicated.

Jan 1, 1970

By Robert Linton

SPECIFICATIONS for clays serving raw materials in the ceramic industry usually contain the following items: (1) Chemical analysis, sometimes with mineralogical structure determined by microscopic investigation. (2) Maturing temperature and firing range, usually expressed in terms of pyrometric cone equivalent. (3) Shrinkage (drying and firing shrinkage separately). (4) Degree of plasticity. (5) Color after firing. Clays may be classified, according to the purpose of the classification, in several different ways, based on (1) Geological occurrence-transported, altered An place, indurated (shales). (2) Physical properties-plastic (bonding clays, ball clays) and nonplastic (flint clays, kaolins or china clays, bone clays). (3) Color. (4) Use. A common classification of clays for commercial designation, and one fol-

Jan 1, 1936

By D. C. Sisti

A technical evaluation of actual performance of the preparation facilities at Beaver Consolidated Coal Co.&apos;s Stinson plant is presented, with special emphasis on sulfur reduction in 1-1/2 x 3/8 in., 3/8 in. x 28 mesh, and 28 mesh x 0 size fractions. Evaluation of the heavy medium section of the plant and the treatment of the 28 mesh x 0 coal is included. Design criteria considered for sizing and selection of equipment required to process 1-3/4 million tpy of raw coal on coals of divergent washability characteristics are summarized.

Jan 1, 1976

By J. H. Swisher

The solubility of sulfur and rate of solution of sulfur in pure Lron were measured in H2S + H2 and H2S + H2 H2O gas mixtures. The solubility and diffusivity of sulfur at 1410°Care 0.13 pet S and 1.0 x 10-5 sq cm per sec, respectively. The solubility iS the same, but the rate of sulfurization is slower in the presence of H2O in the reacting gas. Under these conditions, the over-all rate is controlled jointly by a slow surface reaction and by solid-state diffusion; the mechanism for the surface reaction has not been identified. KNOWLEDGE of the behavior of sulfur in solid iron is desirable for the metallurgy of such products as free machining steel, where a high sulfur level is required, and inclusion-free high-strength steels, where the sulfur specifications are very low. The present investigation was undertaken to check previously reported values for sulfur solubility and diffusivity in 6 iron, and to study the poisoning effect of chemisorbed oxygen on sulfurization kinetics in H2-H2S-H2O gas mixtures. All of the experiments were performed at 1410°C. The thermodynamic behavior of sulfur in 6 iron was the subject of a paper by Rosenqvist and Dunicz.&apos; The sulfur solubility at 1400" and 1500°C was determined by equilibrating pure iron specimens with H2-H2S gas mixtures. The maximum solubility of sulfur in 6 iron was alsc determined by Barloga, Bock, and parlee2 by reacting iron wires with sulfur in sealed capsules. In another investigation, the diffusion coefficient of sulfur in 6 iron at temperatures up to 1450°C was measured by Seibel.3 The method used was to measure sulfur concentration profiles in diffusion couples containing radioactive sulfur EXPERIMENTAL Apparatus. A vertical resistance furnace wound with molybdenum wire and containing a recrystallized alumina reaction rube was used for the experiments. The hot zone in the furnace was approximately 2 in. long with a temperature variation of ±3oC. The hot zone temperature was automatically controlled to within ±2°C, and the test temperature was measured with a pt/Pt-10 pet Rh thermocouple before and after each experiment. Flow rates of the reacting gases were obtained using capillary flow meters. Materials. The source of H2S in the gas train was a premixed cylinder containing 5 pet H2S in H2. This mixture then was diluted with additional hydrogen and argon. In some experiments, water vapor was introduced by passing hydrogen and argon through a column containing 10 pet anhydrous oxalic acid and 90 pet oxalic acid dihydrate. The vapor pressure of water above this mixture is well-known.4 Argon was used as a diluent to minimize thermal segregation of H2S in the furnace5 and to reach higher H2O:H2 ratios than could be obtained in mixtures of H2 and H2S alone. Argon was purified by passage over copper chips at 350°C and subsequently over anhydrone. Hydrogen was purified by passage over platinized asbestos at 450°C and then over anhydrone. The H2-H2S mixture was purified by passage over platinized asbestos and then over P2O5. The specimen stock was made by melting and vacuum-carbon deoxidizing electrolytic "Plastiron" in a zirconia crucible. The principal impurities are listed in Table I. In some of the equilibrium experiments, six-pass zone-refined iron was used to minimize impurity side effects. This zone-refined iron had a total impurity level of about 25 ppm. Procedure. Specimens were annealed in hydrogen for a period of at least 2 hr at the beginning of each experiment. The specimens were held in the reacting gas for times varying between 10 min and 17 hr, and cooled to room temperature in a water-cooled stainless-steel block at the bottom of the furnace. The pH2S/pH2 ratios reported are those for gas equilibrium at 1410°C. Calculations based on available thermodynamic data8 showed that the only other gaseous8 species that formed in significant amounts in the furnace were S2 and S. Even when water vapor was introduced into the gas mixture, the concentrations of SO2, SO, and so forth, were negligible. The initial partial pressure of H2S was therefore corrected for its partial dissociation to S2 and S in determining the equi-

Jan 1, 1968

By I. R. Taylor

Union Carbide has recently developed two open- pit vanadium mines in the Wilson Srpings area of central Arkansas about five miles southeast of Hot Springs. The ores from these mines, together with those from a larger vanadium deposit at nearby Magnet Cove, are processed at a new 1600- tpd plant built by the company in the immediate vicinity (Fig. 1). The Wilson Springs vanadium deposits are associated with the Potash Sulfur Springs intrusive, a circular igneous complex which is exposed over an area that is somewhat less than a mile in diameter.1 The complex has a crude ring structure similar to that of the larger Magnet Cove instrusive six miles to the east.2

Jan 4, 1969

By J. R. Linney

THE Eastern magnetite industry has not failed in its contribution to the war program during the past year. Man-power shortage was the critical problem in maintaining production and for the last half of the year, owing to lack of man power, it was necessary for some mines to change from seven to six days per week schedule. At Cornwall, Pa., the mine operated by the Bethlehem Steel Co. produced approximately 2,000,000 tons of crude ore and 1,200,000 tons of iron ore concentrates, a decrease of about 10 per-cent compared with the previous year. Railroad haulage in the open-pit at this mine was discontinued, being replaced by Mack trucks of approximately 30 tons&apos; capacity. At the Mt. Hope mine in New Jersey, the Warren Foundry and Pipe Corp. produced about 195,000 long tons of crude ore obtaining 70.000 long tons of lump ore and 35,800 long tons of concentrates. An additional 24,500 long tons of concentrates was produced from a stock pile of 47.000 long tons of crude ore accumulated during the latter half of 1943, following the fire in their old dry mill. All of this material was handled through their Brown

Jan 1, 1945