Fundamental Study on New Zinc Distillation Process Utilizing Zinc Sulfide Reaction with Metallic Copper

(1)Materials Transactions, Vol. 48, No. 5 (2007) pp. 1007 to 1011 #2007 The Mining and Materials Processing Institute of Japan. Fundamental Study on New Zinc Distillation Process Utilizing Zinc Sulfide Reaction with Metallic Copper Satoshi Itoh and Atsushi Kikuchi* Department of Environmental Studies, Graduate School of Environmental Studies, Tohoku University, Sendai 980-8579, Japan Phase relations of copper-zinc-sulfur ternary system have been investigated at temperatures of 1100 and 1200 K by equilibrating synthetic samples in evacuated sealed quartz tubes. Using the activities of copper and zinc in the copper-zinc binary system reported in literatures, the activities of the components in the copper-zinc-sulfur ternary system have been then calculated by applying the Gibbs-Duhem equations to the phase relation of metal-sulfide equilibrium. The reaction path of a new zinc distillation process, in which zinc sulfide is directly reduced to zinc vapor with metallic copper, and sulfur in zinc sulfide is fixed as copper sulfide, has been discussed in terms of the activities of the components in the copper-zinc-sulfur ternary system. [doi:10.2320/matertrans.48.1007] (Received November 10, 2006; Accepted February 27, 2007; Published April 25, 2007) Keywords: copper-zinc-sulfur ternary system, zinc sulfide, phase equilibria, activity, extractive metallurgy of zinc, zinc distillation process. 1.. Introduction. A new zinc distillation process with environmental consciousness has been proposed previously by the authors,1–4) in which zinc sulfide concentrate ore that is a raw material in conventional zinc extraction process is directly reduced to zinc vapor with metallic iron, and sulfur in ore is fixed as iron sulfide, that is, sulfur fixation with sulfur dioxide free. Roasting and sintering of zinc sulfide to zinc oxide calcine or sinter are not required. Utilization of an iron scrap as reducing agent, instead of high quality of coke that is usually expensive, leads to the reduction both of energy consumption and environmental burdens in the current zinc extraction process. As well as an iron scrap, a copper scrap would be used as a reducing agent of zinc sulfide. With respect to a reduction and distillation process of zinc sulfide by metallic copper, Warner proposed a new process,5,6) in which zinc sulfide concentrate ore is melted first in a Cu2 S-FeS matte to make Cu2 S-ZnS-FeS matte (melting stage) and then zinc sulfide in the matte is reduced by molten copper to form zinc vapor (reduction stage). The Cu2 S-FeS matte is oxidized with air to produce molten copper, iron oxide slag and sulfur dioxide (oxidation stage). The Warner process has basically three stages as mentioned above and seems to have a problem at a point of energy efficiency due to the circulation of large amounts of high temperature molten matte and copper, while the process proposed by the present work has a single stage of direct zinc sulfide reduction at lower temperatures without sulfur dioxide generation, namely, sulfur fixation as copper sulfide, as expressed by eq. (1). ZnS(s) þ 2Cu(s) ¼ Zn(g) þ Cu2 S(s). ð1Þ. In order to discuss the process feasibility, the thermodynamics of copper-zinc-sulfur ternary system is of fundamental importance. Azuma et al.7) and Surapunt et al.8) investigated near Cu-Cu2 S in copper-zinc-sulfur ternary system at 1473 K. Their data are inappropriate for discussing the *Professor. Emeritus, Tohoku University. process expressed by eq. (1) at lower temperatures around 1200 K where the condensed phases are solid-state, since their reports have dealt with molten copper matte. The objective of the present work is to investigate the phase equilibria in the copper-zinc-sulfur ternary system at temperatures of 1100 and 1200 K, and also to discuss the zinc distillation process utilizing zinc sulfide reaction with metallic copper. First, the phase relations in the copper-zincsulfur ternary system were investigated by equilibrating synthetic samples in evacuated sealed quartz tubes. The activities of the components in the ternary system were then calculated by applying the Gibbs-Duhem equations to the phase relation of metal-sulfide equilibrium. 2.. Experimental. The primary starting materials were copper powder (99.9 mass% purity), doubly distilled zinc (99.999 mass% purity), analytical reagent grade ZnS (99.99 mass% purity) and block sulfur (99.5 mass% purity). Copper sulfide Cu2 S was synthesized by reacting the stoichiometric mixture of copper and sulfur with molar ratio of 2 : 1 in an evacuated sealed quartz tube. The sample for the determination of the phase relations of Cu-Zn-ZnS-Cu2 S system in the copperzinc-sulfur ternary system was prepared as follows: metallic copper, zinc, ZnS and Cu2 S were mixed at the desired compositions which were represented by open circles in Fig. 1. Then the sample was pressed to the 10 mm diam., 1.5 g briquette under about 400 MPa. The briquette sample was put in a quartz tube of 13 mm i.d., and the quartz tube was then evacuated to about 0.4 Pa and sealed. The quartz capsule was held to heat for a desired holding time at temperatures of 1100 and 1200 K, and then quenched in water. The composition of all phases in the samples was determined by electron probe X-ray microanalysis (EPMA) using atomic-number (Z), absorption and fluorescence corrections, that is, the ZAF method, and the phases were identified using X-ray diffraction (XRD)..

(2) 1008. S. Itoh and A. Kikuchi. 3.. ZnS 0.6. 0.4. Cu. 2. N. 3. 5. 10 11. 12 13. 7. 15. 0.8. 9. 19. 17. 14. 20. 3.1 Determination of holding time for equilibrium The relation between the sample composition and holding time at the temperature 1200 K is shown in Fig. 2 as an example, where the sample number 2 corresponds to the number in Fig. 1. The sample was two-condensed-phase combination, namely, the metal phase (Cu s.s.) coexisted with the sulfide phase (ZnS s.s.) where s.s. denotes a solid solution. The sample appears to be attained to equilibrium within one day. However, a microscope observed segregation for the one- and three-days holding samples. Thus, the sample was heated for five days at 1200 K in order to establish the equilibrium. Similarly, at 1100 K the sample was heated for seven days followed by quenching in water.. NS. Cu2S. 21. 0.2. 18 1. Cu. 0.2. 0.4. 0.6. NZn. 0.8. Zn. Fig. 1 Starting sample compositions in schematic diagram of Cu-Zn-S ternary system. : compositions of starting samples.. 0.6 N S in sulfide. Ni in metal and sulfide. 0.5. 3.2 Phase relations in copper-zinc-sulfur ternary system The results of EPMA of the equilibrated samples are shown in Tables 1 and 2. The phases identified by XRD are listed in Tables 3 and 4. From these results, the phase diagrams of the Cu-Zn-ZnS-Cu2 S system at 1100 and 1200 K are illustrated in Fig. 3(a) and (b), where open circles ( ) and triangles ( ) denote the compositions in the two-condensedphase and three-condensed-phase combinations, respectively. The solid lines connecting the open circles are tie lines which represent the conjugate solutions. At the temperature of 1200 K the dotted areas surrounded by the triangles indicate the three-condensed-phase fields of Cu2 S + ZnS + Cu s.s. and ZnS + Cu s.s. + liquid Zn. At 1100 K the phase relation is relatively complicated compared to that at 1200 K, since - and -solid solutions are stable at lower. ZnS. 1200 K. 0.4. Cu2S. 0.3 Zn. Cu. 0.2 0.1. NS in metal. NCu in sulfide. N Zn in metal. 0 0. 1. 2. 3. 4. 5. 6. 7. 8. Time, t / d Fig. 2 Relation between the sample composition and time at 1200 K for sample No. 2.. Table 1. 14 15 3, 5 2 19 10 11 20 21 13. Results of electron probe X-ray microanalysis (EPMA) of the equilibrated samples at 1100 K. Cu2 S s.s.. Cu s.s.. No.. Results. ZnS s.s.. . NCu. NZn. NS. NCu. NZn. NS. NCu. NZn. NS. 0.9946 0.9919 0.9790 0.9694 0.7654 0.6951 — — — —. 0.0034 0.0067 0.0195 0.0293 0.2336 0.3039 — — — —. 0.0020 0.0014 0.0015 0.0014 0.0010 0.0010 — — — —. 0.6617 0.6670 0.6555 — — — — — — —. 0.0022 0.0019 0.0067 — — — — — — —. 0.3361 0.3312 0.3378 — — — — — — —. — — 0.0195 0.0166 0.0173 0.0095 0.0066 0.0083 0.0041 0.0032. — — 0.4805 0.4809 0.4812 0.4891 0.4915 0.4888 0.4930 0.4905. — — 0.5001 0.5025 0.5015 0.5014 0.5020 0.5030 0.5029 0.5063. NCu. NZn.  NS. — — — — — — — — — — — — — — — — — — 0.5162 0.4826 0.0012 0.4567 0.5424 0.0009 — — — — — —. Zn(l). NCu. NZn. NS. NCu. NZn. NS. — — — — — — — 0.4156 — —. — — — — — — — 0.5838 — —. — — — — — — — 0.0006 — —. — — — — — — — — 0.2558 0.1833. — — — — — — — — 0.7440 0.8157. — — — — — — — — 0.0002 0.0010. where Ni : mole fraction,  : balance.. Table 2 No. 14 15 3, 5, 7 1 2 17 9 10, 18 11 12 13. Results of electron probe X-ray microanalysis (EPMA) of the equilibrated samples at 1200 K.. Cu s.s.. Cu2 S s.s.. ZnS s.s.. Zn(l). NCu. NZn. NS. NCu. NZn. NS. NCu. NZn. NS. NCu. NZn. NS. 0.9963 0.9901 0.9608 0.9557 0.9555 0.9356 0.9039 0.7056 — — —. 0.0029 0.0093 0.0382 0.0431 0.0435 0.0633 0.0949 0.2932 — — —. 0.0008 0.0006 0.0011 0.0012 0.0010 0.0012 0.0012 0.0012 — — —. 0.6615 0.6692 0.6520 — — — — — — — —. 0.0008 0.0011 0.0126 — — — — — — — —. 0.3376 0.3296 0.3353 — — — — — — — —. — — 0.0159 0.0209 0.0120 0.0121 0.0120 0.0099 0.0042 0.0027 0.0016. — — 0.4774 0.4854 0.4829 0.4854 0.4846 0.4851 0.4963 0.4929 0.4962. — — 0.5068 0.4937 0.5052 0.5026 0.5034 0.5050 0.4995 0.5044 0.5021. — — — — — — — 0.6734 0.5612 0.3871 0.1699. — — — — — — — 0.3258 0.4380 0.6121 0.8293. — — — — — — — 0.0008 0.0008 0.0008 0.0008. where Ni : mole fraction,  : balance..

(3) Fundamental Study on New Zinc Distillation Process Utilizing Zinc Sulfide Reaction with Metallic Copper Table 3 Phases of the quenched sample after equilibrium at 1100 K, identified by X-ray diffraction (XRD).. Cu2 S + Cu s.s.. 3, 5 2, 19, 10. Cu2 S + ZnS + Cu s.s. ZnS + Cu s.s.. 11. ZnS + . 20. ZnS +  + . 21, 13. ZnS + Zn(l). Cu2S. Cu. Cu2S + ZnS + Cu s.s. ZnS + Cu s.s.. 0.2. 0.4. (b) 1200 K. ZnS + Cu s.s.. 10, 18. ZnS + Cu s.s. + Zn(l). 11, 12, 13. ZnS + Zn(l). Cu. 1, 2, 17, 9. 0.6. Cu2S + Cu s.s.. temperatures.9) The system has four kinds of three-condensed-phase combination of Cu2 S + ZnS + Cu s.s., ZnS + Cu s.s. + , ZnS +  +  and ZnS +  + liquid Zn. The phase boundaries in the copper-zinc binary phase diagram9) at 1100 and 1200 K are shown with the crosses () in Fig. 3(a) and (b). These metal compositions are compatible with the present result at 1200 K. Since the sulfur content in the Cu-Zn metal is as small as 0.1 mol%, the solid solubility of the sulfide in the Cu-Zn metal is considered to be significantly small. The important observations are as follows: Sulfide phases lie on the Cu2 S-ZnS pseudo-binary system as shown in Fig. 3, and the sulfur solubility in metal coexisting with the sulfide is about 0.1 mol% sulfur and is negligibly small both at 1100 and 1200 K. The mutual solid solubility between Cu2 S and ZnS is small both at 1100 and 1200 K, however, at 1200 K it is larger than that at 1100 K as shown in Fig. 3(a) and (b). 3.3. Partial pressures of sulfur and activities in copperzinc-sulfur ternary system In the case of a metal being equilibrated with sulfide, by applying the Gibbs-Duhem equations to the phase relation between the metal and sulfide phases in the copper-zincsulfur ternary system, the following two equations are given: NCu d log aCu þ NZn d log aZn þ NS d logðPS2 =105 PaÞ1=2 ¼ 0 0 0 NCu d log aCu þ NZn d log aZn. ð2Þ. þ NS0 d logðPS2 =105 PaÞ1=2 ¼ 0. ð3Þ. where aCu and aZn are the activities of copper and zinc in the condensed phase, respectively. PS2 is the partial pressure of sulfur. Ni and Ni0 denote the mole fraction in metal and sulfide, respectively. When the metal is equilibrated with sulfide, the activities of components of both phases have identical values. Equation (4) is derived from eqs. (2) and (3), and then the partial pressure of sulfur PS2 can be calculated.. Cu. Zn. 0.8 ZnS+. ZnS. 0.6. Cu2S. 0.4 Cu2S + ZnS + Cu s.s.. N. Cu2 S + Cu s.s. Cu2 S + ZnS + Cu s.s.. NZn. 0.8. 0.2. NS. 14, 15. ZnS + Zn(l). ZnS +. ZnS + Cu s.s. + Zn(l). Phase present. 3, 5, 7. ZnS + + Zn(l). 0.4. 0.8. Cu2S + Cu s.s.. Table 4 Phases of the quenched sample after equilibrium at 1200 K, identified by X-ray diffraction (XRD). Sample No.. ZnS. 0.6 Cu. 14, 15. N. Phase present. NS. Sample No.. ZnS + +. ZnS + Cu s.s. +. (a) 1100 K. 1009. ZnS + Zn(l). ZnS + Cu s.s.. 0.2. 0.4. NZn. 0.6. 0.2. 0.8. Zn. Fig. 3 Phase diagram of the copper-zinc-sulfur ternary system at 1100 and 1200 K. where Ni : mole fraction (—), : Massalski et al.,9) : Present work (three-phase combinations), : Present work (two-phase combinations).. logðPS2 =105 PaÞ ¼ logðPS2 =105 PaÞNCu¼1 Z NCu þ2 yd log aCu. ð4Þ. NCu¼1. where ðPS2 =105 PaÞNCu¼1 is the equilibrium partial pressure of sulfur in the system Cu-Cu2 S at the temperature T and the following relation defines y: y¼. 0 0 NCu NZn  NZn NCu 0 NZn NS0  NS NZn. ð5Þ. The equilibrium partial pressure of sulfur in the system CuCu2 S was substituted using the standard Gibbs energy of Cu2 S formation reaction described as eq. (6) in the present work. The standard Gibbs energy of Cu2 S formation is given as eq. (7).10) 2Cu(s) þ 1/2S2 (101325 Pa, g) ¼ Cu2 S(s) ð6Þ G0 =kJmol1 ¼ 132650 þ 31:28T=K ð1074{1283 KÞ. ð7Þ. For the activity of copper in eq. (4), the value of copperzinc binary alloys11,12) was employed, since the sulfur solubilities in metal were negligibly small as mentioned above. The relations between the partial pressure of sulfur and the composition of condensed phase at 1100 and 1200 K are illustrated in Fig. 4(a) and (b), where XZn ¼ NZn =ðNCu þ 0 0 0 0 NZn Þ and XZn ¼ NZn =ðNCu þ NZn Þ denote the molar ratio in metal and sulfide phase, respectively. The triangles ( ) and circles ( ) correspond to the three-condensed-phase and two-condensed-phase combinations, respectively. The small solid circles are literature data.10,13) Since the system has two three-condensed-phase fields at 1200 K, there are two.

(4) 1010. S. Itoh and A. Kikuchi. -4. -6. (a) 1100 K -6. Cu2S s.s. + ZnS s.s.. -10. log (P S2 / 10 5 Pa). log (P S2 / 10 5 Pa). Cu2S s.s.-8. (b) 1200 K. ZnS s.s. Cu s.s. + ZnS s.s.. -12 Cu s.s.. + ZnS s.s.. -14. Cu2S s.s. Cu2S s.s. + ZnS s.s.. -8. Cu s.s. + ZnS s.s.. -10 Cu s.s.. ZnS s.s.. Zn(l)+ZnS s.s.. -12. + ZnS s.s.. Zn(l). -16 -18. 0. 0.2. 0.4. 0.6. 0.8. Zn(l) +ZnS s.s.. -16. 1. Zn(l) Cu s.s. + Zn(l). -14. 0. 0.2. 0.4. XZn , X'Zn. 0.6. 0.8. 1. XZn , X'Zn. Fig. 4 Relation between the partial pressure of sulfur and the composition of condensed phase at 1100 and 1200 K, where 0 0 0 0 XZn ¼ NZn =ðNCu þ NZn Þ and XZn ¼ NZn =ðNCu þ NZn Þ, : three-phase combinations, : two-phase combinations, : literature.10,13). 2Cu(s) þ 1/2S2 (105 Pa, g) ¼ Cu2 S(s) Zn(l) þ 1/2S2 (105 Pa, g) ¼ ZnS(s). ð8Þ ð9Þ. The activities of Cu2 S and ZnS in the CuS0:5 (Cu2 S)-ZnS solid solutions coexisting with Cu-Zn metals at 1200 K are 0 0 0 0 illustrated against XZn ¼ NZn =ðNCu þ NZn Þ in Fig. 5. The activities of Cu2 S and ZnS in the Cu s.s. + Cu2 S s.s. + ZnS s.s. three-condensed-phase field are 0.97 and almost unity at 1200 K, respectively. Incidentally, at 1100 K both the sulfide activities are almost the same as those at 1200 K.. ZnS(s) þ 2Cu(s) ¼ Zn (101325 Pa, g) þ Cu2 S(s) G =kJmol. a Cu2S. aZnS. 0.4 Raoult's law. 0.2 0. 0 0.2 CuS0.5(Cu2S). 0.4. 0.6. 0.8. 1 ZnS. X'Zn. ¼ 257900  171:03T=K. ð10Þ ð11Þ. The relation between the activities of components in the copper-zinc-sulfur ternary system at 1200 K and the reaction path of the new zinc distillation process is illustrated in Fig. 6, where the reaction path is drawn as the thick arrow. With reacting zinc sulfide with metallic copper from a starting composition, for example, the mixture of zinc sulfide and metallic copper powder with molar ratio of Cu/ZnS ¼. =1 Cu. 0.8. aZnS aCu 1. 0.4. aCu S 2. 1. 1 0.2. N. u. ZnS. 0.6 Cu2S. ,a. Cu 2S. =1. 1200 K. NS. The reaction path of the zinc distillation process utilizing zinc sulfide reaction with metallic copper is discussed in terms of the activities of the components. In the process, zinc sulfide is directly reduced to zinc vapor with metallic copper, and sulfur in zinc sulfide is fixed as copper sulfide corresponding to the reaction described as eq. (10), where the standard Gibbs energy of the reaction is expressed by eq. (11).10,13) 1. 0.6. Fig. 5 Activities of Cu2 S and ZnS in the CuS0:5 -ZnS solid solutions 0 0 0 0 coexisting with the Cu-Zn metals, where XZn ¼ NZn =ðNCu þ NZn Þ.. Discussions. 0. 1200 K. 0.8. aC. 4.. 1. a Cu2S, aZnS. horizontal lines in Fig. 4(b). The partial pressure of sulfur is constant in the Cu s.s. + Cu2 S s.s. + ZnS s.s. three-con0 densed-phase field and it drastically decreases as XZn and XZn approach unity. The activities of Cu2 S and ZnS were then obtained by using the equilibrium constants10,13) of the Cu2 S and ZnS formation reactions described as eqs. (8), (9), the activities of copper and zinc in copper-zinc binary alloys11,12) and the partial pressure of sulfur obtained.. Cu. 0.2. 0.4. NZn. 0.6. 0.8. Zn. Fig. 6 Relation between the activities of components in the copper-zincsulfur ternary system at 1200 K and the reaction path of the new zinc distillation process with environmental consciousness.. 2:0 (aZnS ¼ 1, aCu ¼ 1) under vacuum or nitrogen gas stream, the sample composition changes along the thick arrow through the Cu2 S s.s. + ZnS s.s. + Cu s.s. three-.

(5) Fundamental Study on New Zinc Distillation Process Utilizing Zinc Sulfide Reaction with Metallic Copper Table 5 Calculated zinc partial pressures in the reaction: ZnS(s) + 2Cu(s) = Zn(g) + Cu2 S(s) at various temperatures. T/K. PZn /kPa. 1100. 0.049. 1200. 0.52. 1180. 0.33. 1210. 0.64. 1240. 1.2. condensed-phase field (aCu2 S ¼ 0:97, aZnS ¼ 1:0, aCu ¼ 0:96) then reaching the Cu2 S composition (aCu2 S ¼ 1). By assuming the activities of Cu2 S, ZnS and copper to be almost unity in the temperature range of 1100 to 1240 K, the zinc partial pressure in the reaction of eq. (10) was calculated as shown in Table 5. The equilibrium partial pressure of zinc is 1.2 kPa at the temperature of 1240 K, indicating that the process is practicable under inert gas stream as well as vacuum. The activity of Cu2 S in the copper sulfide that will be formed in the process can be regarded as unity. Zinc content in the copper sulfide is expected to be small, and the copper sulfide can be sent to conventional copper smelter, especially, copper converter. Roasting and sintering of zinc sulfide to zinc oxide calcine or sinter are not required. Therefore, utilization of a copper scrap as reducing agent leads to the reduction of the energy consumption and sulfur fixation with sulfide dioxide free in the zinc extraction process. This process enables cyclical use of resources and reduction of environmental burdens. The kinetic experiments were conducted to confirm the possibility of zinc sulfide reaction with metallic copper under vacuum (about 1 Pa) in the temperature range of 1180 to 1240 K.14) The reaction rate increased with increasing temperature. As a result, the zinc distillation process utilizing zinc sulfide reaction with metallic copper is considered to be practicable. 5.. Conclusions. The phase relations and the activities of components in the copper-zinc-sulfur ternary system, which are fundamental data on the new zinc distillation process where zinc sulfide is directly reduced to zinc vapor with metallic copper, and sulfur in zinc sulfide is fixed as copper sulfide, have been determined at temperatures of 1100 and 1200 K. The results are summarized as follows: (1) Sulfur solubility in metal coexisting with sulfide is. 1011. negligibly small, and sulfide phases lie on the Cu2 SZnS pseudo-binary system. The mutual solid solubility between Cu2 S and ZnS is small. (2) Relation between the partial pressure of sulfur and the composition of the condensed phase was determined. The activities of Cu2 S and ZnS were obtained using the equilibrium partial pressure of sulfur and the activities of copper and zinc in copper-zinc binary alloys. (3) The activity of Cu2 S in the copper sulfide that will be formed in the process can be regarded as unity. Zinc content in the copper sulfide formed in the process is expected to be small, and the copper sulfide can be sent to conventional copper smelter, especially, copper converter. Acknowledgments The authors would like to express appreciations to Messrs. H. Goto and K. Nakamura (Tohoku University) for their assistance in part of experiments and also to Mr. K. Suda (Tohoku University) in analyses by EPMA.. REFERENCES 1) S. Itoh and T. Azakami: Metallurgical Review of MMIJ 13 (1996) 37– 51. 2) S. Itoh and A. Kikuchi: Shigen-to-Sozai (Journal of MMIJ) 114 (1998) 733–738. 3) S. Itoh: Mater. Trans. JIM 40 (1999) 618–626. 4) S. Itoh and A. Kikuchi: Proc. James M. Toguri Symposium, Fundamentals of Metallurgical Processing, ed. by G. Kaiura, C. Pickles, T. Utigard and A. Vahed, (Can. Inst. Min. Met. and Petroleum, 2000) pp. 123–134. 5) N. A. Warner: Trans. IMM 92 (1983) C147–152. 6) N. A. Warner: Minerals Industry International, July (1992) 5–11. 7) K. Azuma, S. Goto and N. Takebe: Journal of MMIJ 84 (1968) 1082– 1088. 8) S. Surapunt, C. M. Nyamai, M. Hino and K. Itagaki: Shigen-to-Sozai (Journal of MMIJ) 112 (1996) 56–60. 9) T. B. Massalski, H. Okamoto, P. R. Subramanian and L. Kacprzak, Eds.: Binary Alloy Phase Diagrams, 2nd ed. (ASM, 2, 1986) p. 1509. 10) Y. Omori: Measurement of Standard Gibbs Energy of Formation of Copper Sulfide by Electromotive Force Method, (Bachelor Thesis, Tohoku University, Japan, 1981). 11) A. Hibino: Activity Measurements of Primary Solid Solutions in Some Alloys by Isopiestic Method, (Master Thesis, Tohoku University, Japan, 1985). 12) T. Azakami and A. Yazawa: Journal of MMIJ 84 (1968) 1663–1668. 13) O. Knacke, O. Kubaschewski and K. Hesselmann, Eds.: Thermochemical Properties of Inorganic Substances, 2nd ed., (Springer-Verlag, 1991) p. 1709, 2337, 2349. 14) S. Itoh and A. Kikuchi: Proc. MMIJ Annual Meeting, (2001) Vol. II, pp. 51–52..

(6)

New documents

Within the entrepreneurial city vision an unbroken trajectory between the past, present and future is articulated that denies urban spatial and temporal multiplicity and exerts a weight

To take advantage of both large a pool of training samples and sparse related semantic features for a subclass of queries, we could modify the loss function as follows.. 3 whereC̄ is

Recently, various cells have been investigated to treat liver disease, including HSCs, mesen- chymal stem cells MSCs, fetal liver stem cells, embryonic stem cells ESCs, endothelial pro-

In fact dark or bright smoke seems to be everywhere in the early part of the film,.. both in Faust’s study, in the streets of the plague-stricken town, and high up in

7 Conclusion and Future Work We introduced a new approach to verb cluster- ing which involves the use of i rich lexical, SCF and GR data produced by a recent SCF system, ii novel

Details and advantages of different biopsy needles and biopsy techniques Category Menghini needle Tru-cut needle** Needle puncture One-man right hand By operator Ultrasound probe

Then, by using evaluations similar to those described in Baroni et al., 2008 and by Rapp 2002, we show that the best distance-based measures correlate better overall with human

The aim was to link 1 the city centre to Tallaght, an expanding area in the south west of Dublin 2 the city centre to Ballymun, in the north of the city near the airport, and 3 to

Struma ovarii means ovarian goiter which originates from a single germ cell after the first meiotic division [1, 2] and is the most common type of mono- dermal teratoma in 3% of mature

Using the conservation area of Owenduff/Nephin Beg Complex as a case study, this paper examines the potential for ecological effects arising from artificial night light in an Irish