Materials Transactions, Vol. 45, No. 8 (2004) pp. 2489 to 2495 #2004 The Japan Institute of Metals OVERVIEW
Metallurgical Chemistry in My Life*
Noboru Masuko
Metallurgical chemistry’s principle is that ‘‘the chemical process is governed by chemical potential.’’ Successful chemical process technology follows a route that does not go against the governance of chemical potential. In order to realize the technological objective, raw materials and a reactor are necessary, and after the principle is established, the method is supported by the reactor and advances in the materials that comprise such apparatus. Therefore, the technology is a fusion of material, apparatus, experience, and science, all of which are parts of the foundation of a technological method. The author’s involvement is described as an academician from the postwar recovery to the technological rearmament period. In the postwar recovery period, a systematic point-of-view was introduced to a technological principle using phase diagrams that clarified chemical potential, which was a new concept in the field of thermodynamics. In the technological rearmament period, technological evaluation was conducted from a philosophical standpoint.
(Received April 26, 2004; Accepted June 2, 2004) Keywords: chemical potential, reactor, Eh-pH diagram, Eh-pH-pL diagram, potential diagram
1. Introduction 2. Chemical Potential Diagrams
Ever since graduation from the university in 1957, I have 2.1 Eh-pH-pL diagram resided at the university and worked on joint research with Gibbs defined the intensive quantity of chemical potential metallurgical chemistry industries. Metallurgical chemistry in 1875. As appreciation increased that the concept of phase is a technology, and it has a principle and a method. The rule provided an important foundation of the phase diagram, principle is that ‘‘the chemical process is governed by numerous binary system diagrams for metals were developed chemical potential.’’ That is, successful chemical process from 1900 to 1920. While phase diagrams were measured in technology follows a route that does not go against the many systems and data were accumulated, the measurements governance of chemical potential. In order to realize the of chemical potential were also made, so that actual technological objective, raw materials and a reactor are measurements were available in a database by around necessary, and after the principle is established, the method is 1940. For example, Latimer’s Oxidation Potentials1) was supported by the reactor and advances in the materials that published in 1938, and the second edition in 1952. comprise such apparatus. Therefore, the technology is a With the availability of these actual measurements, fusion of material, apparatus, experience, and science, all of diagrams which presented chemical potential explicitly which are parts of the foundation of a technological method. began to acquire practical meaning. The primer was The process of metallurgical chemistry in Japan has gone Pourbaix’s ‘‘Eh-pH diagram.’’ However, Pourbaix’s 1937 through various developmental stages in its 60-year history thesis was not accepted by corrosion researchers at the time, from recovery after World War II to the present. I call these and, as he himself noted, ‘‘Corrosion is kinetics, so it has stages: the postwar recovery period (1945 1965), the high nothing to do with thermodynamic equilibrium.’’ With the development period ( 1975), the technological rearmament support of U.R. Evans, the English translation of the thesis2) period ( 1985), the exotic materials period ( 1995), and the was published in 1949. It took time before the clarity of global environment period (1995 present). The efforts of ‘‘building a kinetic theory based on the difference of university researchers took several forms in response to the chemical potential as the driving force’’ could be appreciated, needs of each period. however, and it was not until 1960 that this method became This paper describes my involvement as an academician the new stream of thermodynamic application to the hetero- from the postwar recovery to the technological rearmament geneous system. Through my exposure to this ‘‘Eh-pH period. In the postwar recovery period, a systematic point-of- diagram,’’ I was able to work in the vanguard of this stream in view was introduced to a technological principle using phase the field of metallurgical chemistry including the field of diagrams that clarified chemical potential, which was a new hydrometallurgy. I am grateful to have come along at the concept in the field of thermodynamics. In the technological right moment in history. rearmament period, technological evaluation was conducted In 1958, I began research in uranium metallurgy at the from a philosophical standpoint. Institute of Mineral Dressing and Metallurgy of Tohoku University. The carbonate leaching method was applied to uranium ore which was contained in an alkaline based rock. In order to understand the principle of this method, I devised the Eh-pH-pL diagram, where the pL axis, which represents an inverse logarithm of ligand activity that composes the * This Paper was Presented at the Spring Meeting of the Japan Institute of 3) Metals, held in Tokyo, on March 30, 2004, and originally published in complex, is added to Pourbaix’s Eh-pH diagram. Figure 1 Japanese in Materia Japan 43 (2004). shows the conditions of formation of a uranyl carbonate 4 The Forty-Ninth Gold Medalist of the Japan Institute of Metals, 2004 complex [UO2(CO3)3 ] in the stable region of CaCO3 in the 2490 N. Masuko
8 0
7
++ 6 Fe 2 2- Mn++ 4 5 Zn++ Zn (OH)2 Fe(OH)2 -0.5 2+ ++ FeCO 4 Cu 3 Zn ZnCO3 Zn(CN) Mn(OH)2 Zn(CN) 3 Cu(OH) 2 2-
3 CuCO3 MnCO3 Ca++ 2 pCO Ca(OH)2 ++ 2 Ni Ni(OH)2 2 CaCO3 ZnO 1 -1.0 Zn(OH) Eh / V Eh /
0 NiCO3 Mg++ Zn -1 Mg(OH)2 MgCO3 -2 -1.5
-3 5 6789101112 13 14 15 16 17 pH
Fig. 1 Stability domain for uranyl-carbonate complex ion. -2.0 0 5 10 15 pH
Fig. 3 Eh-pH diagram of zinc cyanide complex ion.
1 4- [UO2(CO3)3] Eh / V Eh / -0.5 0.5 ++ Cu(NH3) 4 UO3H2O UO3H2O 2+ Zn 2 Zn(OH)2 Eh / V Eh / + Cu(NH3) 2 0 -1.0 Zn(CN) 2 4 1.3 2 468101214 -0.5 8 pH UO2 Zn(CN)
6 -1 4 5 6 7 8 9 10 11 12 13 14 15 CN 4 p pH 2 - + MnO4 + 4H + 3e = MnO2 + 2H2O + 0 O2 + 4H + 4e = 2H2O ++ + Cu(NH3)4 + e = Cu(NH3) 2 + 2NH3
Fig. 2 Eh-pH diagram showing oxidation of UO2 in alkaline solution. Fig. 4 Eh-pH-pCN three-dimensional diagram.
rock. Figure 2 shows the Eh-pH diagram representing the categorized into three basic reactions according to the form principle of the use of the cupric amine complex to uranyl of sulfur. Taking the example of sphalerite (ZnS), the carbonate for air oxidation of UO2 in ore. following are the categories: The principle of hydrometallurgy using complex produc- ZnS þ 2Hþ ¼ Zn2þ þ H S tion can be explained clearly by expanding the Eh-pH 2 diagram to a system containing this complex. To collect gold ðhydrogen sulfide generating typeÞ and silver by zinc cementation from pregnant cyanide ZnS ¼ Zn2þ þ S þ 2e solution, it is useful to prepare potential-pH diagrams for gold, silver, and zinc in cyanide solution. Figure 3 shows that ðelemental sulfur forming typeÞ 2þ þ principle, and Fig. 4 shows the ternary phase diagram using ZnS þ 4H2O ¼ Zn þ HSO4 þ 7H þ 8e 4) zinc as an example. ðsulfuric acid forming typeÞ 2.2 Direct acid leach for sphalerite The potential-pH diagram in Fig. 5 clearly shows the In the beginning of the 1960s, those in the field of conditions under which these reactions occur.5) Experimental nonferrous metallurgy sought possible ways to introduce investigations were conducted for each reaction category, hydrometallurgy to the process of Kuroko (a complex sulfide and processing conditions were identified. Also, an experi- mineral), which is a resource unique to Japan. Hydro- ment using platinum electrode potential as a monitor is metallurgical processing of the sulfide mineral can be shown in Fig. 6. This method of process control employing Metallurgical Chemistry in My Life 2491
E / V 0.4 1.0
Zn++ Pu4+ - Zn++ 10 0.3 HSO4 A PO2 = 1 ++ 2- 0.5 Zn SO4 S PuO2 11 12 = ϕ 0.2 -50 2.5 5 pO -
PCl2 = 1 3+ Pu -2 PCl2 = 10 1 Eh / V Eh / 3 -4 0.1 ++ PCl = 10 UO2 2 Zn++
H S U3O3 2 2 U4+ 0 ZnS 5 (ppt) -1.0 4 (Pu) = 10-4 -0.1 UO2 -2 -1 0 123 (U) = 10-2 } -1.5 pH
- 2- ++ (HSO4 ) 1, (SO4 ) 1, (Zn ) 1, -1 -1 ++ (H2S) 10 [PH2S 1], (H2S) 10 , (Zn ) 1, -3 -3 ++ ¼ (H2S) 10 , (H2S) 10 , (Zn ) 1, Fig. 7 E-pO diagram of U-Pu separation in NaCl-KCl equimolar solu- -1 ++ ++ -3 (H2S) 10 , (Zn ) 1, (Zn ) 10 tion.
Fig. 5 Eh-pH diagram of ZnS. (i) Zone for H2S generation. (ii) Zone for elemental sulfur formation. (iii) Zone for oxidation to sulfate. salt solvent using chlorine as oxidizing agent, Pu dissolves as 3þ 2þ trivalent (Pu ) and U as hexavalent (UO2 ). When UO2 oxide is subject to electrolytic deposition, it can be separated from Pu (Condition IV of the diagram). When oxidation 100 ¼ A occurs with the coexistence of O donor such as SnO2, only U dissolves without dissolution of Pu, and Pu-U separation 80 B also becomes possible (Conditions I and II of the diagram). Several inorganic chemistry experiment results were described In the AEC Report [HW-62431 (1959)] at the 60 300 time, but to understand such multitudinous phenomenolog- S generated (%) S generated 2 ical explanations in a systematic manner, creation of a 40 200 diagram as Figure 7 was useful. The abscissa of the diagram is represented using constant (pO¼- ) which originates dissolved, H dissolved,
++ from the intrinsic term of chemical potential of oxide ion, and
Zn 20 C 100 only the relative positions of stable chemical species are D shown. However, when the chemical potential of chloride ion Electrode potential of Platinam (mV / AgCl) 0 0 0 10 20 30 40 50 60 is defined as being held constant as a standard against the Reaction time, t / min chemical potential of ions in the fused chloride bath, becomes a quantity which can be determined experimental- Fig. 6 Use of ORP potential to monitor acid leaching of ZnS. A: Znþþ ly.6) dissolved. B: H2S generated. C: Electrode potential of platinum electrode In the general theory for acid base reaction in fused salt,7) under an O stream. D: Electrode potential of platinum electrode under a 2 redox reactions were categorized as either O or R type. The N2 stream. system in which increase of oxygen partial pressure under a condition of constant solvent basicity and increase of basicity under a condition of constant oxygen partial pressure was the potential of platinum electrode is currently used widely in designated O type reaction. In another words, in O type various hydrometallurgy processes as ORP potential. reaction, the concentration of oxidants increased when the solvent became basic under a condition of constant oxygen 2.3 E-pO¼ diagram in fused salt solvent partial pressure. Conversely, in R type reaction, the concen- The Eh-pH diagram technique can be extended to the tration of reductant increased when the solvent became basic application of fused salt solvent as a process solvent. The under this same condition. When fused salt is generalized to phenomenon of precipitation of UO2 oxide from UO2Cl2 slag, dephosphorization is O type reaction while desulfur- dissolved in fused solvent (NaCl-KCl) by electrolytic ation in steelmaking reactions is R type; to understand reduction was discovered, and a reprocessing method called reactions where several elements separate between slag- the ‘‘salt cycle method’’ for spent nuclear fuel was aggres- metal as in steelmaking reactions, the use of electrochemistry sively researched at the Hanford National Laboratory. facilitates understanding. Figure 7 shows the potential-pO¼ diagram of U and Pu in the NaCl-KCl equimolar mixture solvent at 1000 K, which we published.6) When spent nuclear fuel is dissolved in fused 2492 N. Masuko
Cu Na Na2O Na2O2 1.0
a Na+Na2O +Na4FeO3 f b i' j' 0.8 Na FeO Cu S Cu O 4 3 2 2 Na FeO 868 K Na+Fe+Na4FeO3 h' 3 3 Na FeO CuS ab CuO 2 2 h" d 0.6 Na4FeO3 c + Fe + Na2FeO2 Fe+Na2FeO2 c Na2Fe2O4 CuO CuSO4 +Na2Fe2O4 Na / (Na+Fe)
CuSO4 0.4 Na2Fe2O4+ d Wus+ Mag+Hem Na2Fe2O4 Mag+ SO SO2 SO3 Fe+Na2Fe2O4 Hem + Wus
0.2 +Wus 4 O Fig. 8 Phase diagram of Cu-S-O system. Mag+ 2
Fe g e Wus 2 +Mag Wus+Fe Wus Na f
0.0 CuS (S) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 PS2 = 1 a Fe O / (Na+Fe) Fe2O3 g
Cu2S (S) -10 CuSO4 (S) Fig. 10 Phase diagram of Na-Fe-O system (868 K). b f h P -20 SO i 3 = 1 Na2O a c 0
2 j' i' Na4FeO3 S Na2O2 i b P
-30 = 1 2 h h' c O
log d
Cu (S) P CuO.CuSO Na3FeO3 Cu2O (S) -40 k' Na2FeO2 P SO h" 4 (S) 2 = 1 d j -50 CuO (S) -5
e Na2Fe2O4
(NaFeO2) e -60 Fe log a -20 -15 -10 -5 0 Na2O
log PO2 f
g Fig. 9 Chemical potential diagram of Cu-S-O system (800 K). -10
Fe O Wus 2.4 Correlation between phase diagram and chemical 3 4 Fe2O3 potential diagram The mutual relationship between the phase and chemical potential diagrams is illustrated using the roasting reaction of 10 0 -10 -20 -30 -40 copper sulfide as an example. Figure 8 is a phase diagram of log PO2 the Cu-S-O system, and when CuS is roasted oxidatively in air, reaction occurs in the order of CuS-Cu2S-Cu2O-CuSO4- Fig. 11 Chemical potential diagram of Na-Fe-O system (873 K). CuO CuSO4-CuO. Figure 9 is an illustration as a chemical potential diagram. It is characteristic that the region of coexistence of the three phases in Fig. 8 is expressed as one became useful to analyze the accident which occurred in the point in Fig. 9. Here, the pressure of SO2+O2 is constant and fast breeder reactor Monju. Converting it into the form of a the reaction proceeds along a certain line. This diagram is one chemical potential diagram allows information from other example in the general theory8–10) that addressed the fields to be used to understand new phenomena. application of gaseous-solid phase reaction to nonferrous metallurgy, and it was there that I used the term ‘‘chemical 3. Philosophy of Reactors potential diagram’’ for the first time. Figure 10 is a phase diagram of the Fe-Na-O system, and 3.1 Category Fig. 11 shows the chemical potential diagram of that system. Both principle and method are involved in chemical Figure 10 was originally based on basic research of alkali process technology that deals with quantity and produces circulation in a blast furnace, and by changing it to Fig. 11, it products. The main body of the method is the reactor and it is Metallurgical Chemistry in My Life 2493
Table 1 Features of Chemical Process Reactors. reactor passes 300 kA of electricity through a reactor with a 2 1. Three Elements cross section area of 38 m to produce 2.3 tons per day of Input (Material, Energy, Power) aluminum. The blast furnace for producing iron is a three- Control (Type, Route, Contact, Characteristics) dimensional reactor. This furnace is a kinetic reactor, has a 2 Output (Material, Energy, Power) cross section area of 165 m and produces 10000 tons of 2. Classification molten iron daily. If one wishes to produce 10000 tons of 2 Potential or Kinetic Reactor aluminum per day, a cross section of 170000 m or 1000 Inheat or Outheat Reactor times the size of a regular blast furnace is necessary because a Two-dimensional or Three-dimensional Reactor two dimensional reactor is used for aluminum. The basic Highly Endothermal or Highly Exothermal Reactor reason for this difference is the fact that the enthalpy of 3. Route formation of resource oxide for 1 gram of metal is four times of Material greater, that is, the enthalpy of formation of alumina (Al2O3) of Energy is 31 kJ/g-Al while that of hematite (Fel2O3) is 7.4 kJ/g-Fe. of Immovable Components This difference makes it impossible to reduce alumina with a 4. Contact three-dimensional thermal reactor. Refining of aluminum Stationary was thus not possible through adaptation of blast furnace Dynamic reduction technology, and was made possible only by the 5. Characteristics invention of a totally new reactor. All attempts for refining Reaction Density aluminum with a three-dimensional reactor with higher Material Flux efficiency failed. From the knowledge gained through this Space-time Yield failure, the technology of aluminum metallurgy was estab- lished, and the basic principle that mere fourfold (twofold in terms of mol) difference in enthalpy was resulted in basic difference of the reactor was recognized. through the reactor that the principle is realized. Although the The features shown in Table 1 reflect the strategic thinking university researcher may not be directly involved in an for the design of reactors that form the basis of the operation on site, he/she is required to have an integral technology. understanding of on-site technology of the research subject. I have been involved with reactors in two ways. The first was 3.2 Reaction density for large-scale continuous reactor handling them in a general and integrated manner to evaluate Makishima published an exceptional empirical rule that their category, features, and possibilities; this can be called ‘‘Reaction density for a large-scale continuous reactor does the philosophy of the reactor. The second was commitment not surpass 4 106 kJ/(m3 h).’’11) This quantity can be unit- from the standpoint of preventing degradation and corrosion converted to 1.1 kW/dm3. This is equivalent to a condition of materials that compose the reactor; this was a position where a 1.1 kW immersible heater is placed in 1 L of water, where I handled specific issues such as projection of the with a reaction density in which about five minutes are remaining lifespan of the reactor material. Here, I shall required for water at room temperature to boil. Suppose this describe some of my thoughts about the first type of quantity is given a tentative unit of 1 Mak. Currently, the involvement. Table 1 shows the categories used in analyzing space-time efficiency of a large-scale blast furnace that the philosophy of a reactor, and many are taken from produces 10000 tons of pig iron per day is about 0.3 Mak. In Makishima’s paper.2) This categorization was useful during comparison, the value for a small-scale, single shot reactor, the technological rearmament period, and is important in the for example, an explosion in a firearm cartridge, is 107 Mak current global environment period. which is greater by several orders of magnitude. In a large The chemical process is realized by input of raw material capacity reactor which is run continuously, heat must be and output from the reactor as product. The processing added when the temperature decreases and the reactor cooled principle can be understood by the chemical potential when the temperature increases. This control determines the diagram, while the structure of the reactor differs greatly upper limit of reaction density. In contrast, in a firearm that depending on mass of product, reaction density and material utilizes one-shot reaction, the original speed of chemical flux. reaction can be utilized without control. Fire has a character- For example, both electro-winning of zinc and electro- istic of running wild, and the technologist’s struggle is how to plating of zinc on a steel plate consist of the same chemical keep it under control. reaction of separating metal zinc using insoluble anode from By comparing totally different reactors, a blast furnace and an aqueous solution of sulfuric acid. However, while the a cartridge, using a new parameter Mak, the basic difference former is done under a current density of 500 A/m2 for the of each reactor becomes clear. The categories in Table 1 purpose of obtaining a pure zinc mass, the latter is done under generate various indices for such analysis. Establishing a a current density of 5000 A/m2 to apply a smooth, thin basic parameter to compare processes with different objec- coating on the steel sheet. The one-digit difference in current tives is important for stimulating new ideas. density makes the structure of the two reactors totally different. 3.3 Rearmament of process technology The electrolytic cell to produce aluminum is a two- When the high development period ended, the chemical dimensional reactor, and it is also a potential reactor. This process industry in Japan was faced with the ‘‘oil shock.’’ To 2494 N. Masuko respond to problems of antipollution and to conserve 10 Fe resources and energy, companies reviewed their conventional 9 I Chalcophile group production processes. During this period, the issue of II Siderophile group 8 strengthening of technological theories was considered due III Lithophile group S Cu Ca to the need to improve operations in the short-term to 7 Zn Mn Al Pb Cr Ti Mg improve facilities in the mid-term, and process conversion in 6 Ni Sn Zr the long-term. University researchers were asked to partic- Sb Mo 5 As W ipate in this review by industry technologists, and a new Cd Co Hg Nb V opportunity for an industry-university joint effort was born. 4 Au Bi Li New technology is often generated during a period of 3 Se Ta Te Y In Be technological maturation and the joint cooperation of T (production.ton / year) log 2 Pt university and industries during this era yielded results. I Ga 1 Tl was involved in industrial electrolysis, and participated in 0 reviews of aluminum electrolysis, zinc electrolysis, and -4 -3 -2 -1 0 1 2 3 4 5 6 chlor-alkali electrolysis. In such investigations, the philo- log K / ppm sophical method based on the features shown in Table 1 5 group T = 10 K S = M/T = 30 years 4 formed the foundation for university research. group T = 10 K S = M/T = 300 years 2 4 Based on the discussions during this period, I published the group T = 2.5×10 K S = M/T = 1.5 × 10 years Chemistry of Industrial Electrolysis jointly with Professor M. Takahashi.12) In this book, we introduced the new Inner Fig. 12 Relationship between annual production of metals and their Potential Convention for the Nernst equation where electrode Clarke’s number. potential E was explained using potential . In addition to explaining the electrochemical equilibrium theory in terms of electrochemical potential, this provided an integrated sys- 4. Extractive Metallurgy in the Global Environmental tematic method for handling ohmic drop analysis, which is Period vital in industrial electrolysis. Aluminum electrolysis was soon abandoned in Japan since Metallurgy is basically the technology of extracting the a power of 15000 kWh/ton was needed, but the difference in target metal out of naturally occurring ore. The ore body in the 10 yen per 1 kWh price of electricity could not be which target elements are concentrated is particularly used as resolved with technology. metallurgical material. Metal elements tend to deposit in To reduce the electrolytic energy in zinc electrolysis, similar groups in the earth’s crust, and Goldschmidt’s earth several measures were taken on site, including reduction of chemistry categorization is well known for elements that zinc concentration, increase of sulfuric acid concentration, accompany target metal;14) they are chalcophile, siderophile, raising temperature, and shortening of the distance between and lithophile groups. Figure 12 is obtained when the electrodes. How such measures taken on site helped to logarithm of average concentration in the crust known as conserve energy and under what ‘‘principles’’ were clarified Clarke’s number is plotted against the logarithm of annual and the limits of each measure have been shown.13) production volume of metal elements.15) This figure shows an According to this estimate, 3110 kWh was set as standard interesting trend for the average concentration in the crust to for producing 1 ton of zinc, and it was shown that 2730 kWh be positioned on each line of the elements belonging to and about 12% reduction were the limits. Currently, Goldschmidt’s category. Considering the fact that the electricity conservation technology has advanced by the element reserve is proportional to Clarke’s number, the guidance provided here, and operations are carried out at less volatility of metal elements is shortest for the chalcophile than 2900 kWh. For electrolytic power to be less than group which faces danger of depletion, while the lithophile 2000 kWh per ton of zinc, the electrolytic method, which group does not face depletion as a resource, although it incorporates fuel cell reaction in the form of burning requires a large amount of metallurgical energy. methanol at an anode, is necessary. Attempting power Currently, our greatest concern is recycling spent elements conservation over a certain limit in the current process as resources. Metallurgy in the global environment period requires a detour production route involving consumption of entered a phase of utilizing technology for artificial resour- a secondary material such as methanol. Therefore, power ces. One of the difficulties with the technology used to conservation and resource conservation are not compatible, process artificial resources is that these resources are and the tradeoff between the prices of electricity and accompanied by elements that are not present in natural methanol governs the technological feasibility. resources. We must devise a separation technology which is The chlor-alkali industry, which is the central technology different from the metallurgy for conventional natural and the mainstay of the acid alkali industry, produced an resources to deal with combinations which do not appear in innovative method called ion exchange membrane cells Goldschmidt’s categories. almost one century after the invention of mercury cells. This was developed by Japanese engineers, and our work12) was 5. Conclusion cited in each period of the steps of technological develop- ment: a design of a practical chamber, and factory operation. Each researcher has his/her own discipline and field. In my case, the discipline was electrochemistry, and my fields were Metallurgical Chemistry in My Life 2495 metallurgy, metal surface processes and corrosion. In each Application to Hydrometallurgical Processes (in Japanese), J. Electro- field, I was able to find issues that were of interest at the time chemical Soc. Japan 27 (1959) 365–374. 5) Y. Hisamatu and N. Masuko: Aqueous Oxidation of ZnS in Sulfuric and yielded good results. I have recorded here part of my Acid Solution (in Japanese), J. Electrochemical Soc. Japan 31 (1963) research on the principles and methods of chemical proc- 771–776. esses, focusing on industry-university joint research in the 6) N. Masuko, M. Okada and Y. Hisamatu: E-pO¼ Diagram in Fused nonferrous metallurgy field, and have described what I view Chloride Solution and its Application to UO2 Electrolysis (in as future prospects. Japanese), Yoyuen (Fused Salts) 6 (1963) 570–582. 7) N. Masuko: Acid and Base Reactions in Fused Salt Solutions (in The 49th Japan Institute of Metals Award is in appreciation Japanese), J. Electrochemical Soc. Japan 35 (1967) 508–513. of my long years of research in metallurgical chemistry and 8) N. Masuko: Chemical Potential Diagrams (in Japanese), J. Electro- my contribution to the development of metallurgy in chemical Soc. Japan 38 (1970) 153–158. academia and government. It is a great honor indeed. Given 9) N. Masuko: Chemical Potential Diagrams (in Japanese), J. Electro- the opportunity to present this address, I am grateful that I can chemical Soc. Japan 38 (1970) 226–231. 10) N. Masuko: Chemical Potential Diagrams (in Japanese), J. Electro- communicate to people of the next generation many of the chemical Soc. Japan 38 (1970) 307–314. insights and some of the guidance that I received in past years 11) S. Makishima: Thoughts on Chemical Process Reactors (in Japanese), from my seniors and friends. J. Chem. Soc. Japan, Ind. Chem. Section 64 (1961) 1719–1721. 12) M. Takahashi and N. Masuko: Chemistry of Industrial Electrolysis (in REFERENCES Japanese), AGNE (1979). 13) N. Masuko: Feasibility Study on Energy Saving of Zinc Electro- winning, MMIJ/Aus IMM Joint Symposium, Sendai, (Nov. 1984) JD- 1) W. M. Latimer: Oxidation Potentials, (Prentice-Hall, Inc., 1952). 3-5. Thermodynamics of Dilute Aqueous Solutions 2) M. J. N. Pourbaix: , 14) B. Mason: Chapter 3 in Principles of Geochemistry, 2nd Ed., John (Arnold & Co., 1949). Wiley & Sons (1958). 3) K. Sudo and N. Masuko: Thermodynamics of Uranium Ore Leaching 15) N. Masuko: ‘‘Metallurgy for Man-Made Resources’’ in Metallurgical (in Japanese), Proceedings of the 3rd Atomic Energy Symposium of Processes for Early Twenty-First Century, Ed. by H. Y. Sohn, Vol. II, Japan VI-7 (1960) 278–283. 21–30, TMS (1994). 4) N. Masuko: Eh-pH Diagrams of Complex Ion Systems and Their
. Born in Hukushima (1935). Graduated from The University of Tokyo (1957). Research Assistant, Tohoku University (1958 1961). Assistant Professor, The University of Tokyo (1965 1978), Professor, The University of Tokyo (1978 1995), Director, Institute of Industrial Science of The University of Tokyo (1986 1989), Member, The Science Council of Japan (1991 1997), Vice President, The Japan Institute of Metals (1994 1996), Professor Emeritus, The University of Tokyo (1995), Professor, Chiba Institute of Technology (1995 present), Honorable Member, The Japan Institute of Metals (2001). . Electrochemistry, Nonferrous Metallurgy, Corrosion and Protection of Metals, Metal Finishing.