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Zircomum is one of the important rare metals for advanced technology. The caldasite, a mixture of zircon and baddeleyite, from Brazil, can be an additional source of zirconium if it is suitably processed. High temperature chlorination of such an ore has many advamages in process development. In this paper, studies have been made to extract zirconium from caldasite through a chloride process. This process consists of chlormation of the ore and the selective condensation of volatile chlorides containing zirconium. The salient features of the chlormation studies are given below. 1) Caldasite ore reacts with Cl_2 gas at about 1000K producing metal chlorides enriched ZrCl_4. 2) 96% of the ore can be chlorinated with a recovery of 95% of zirconium. 3) By selective condensation of the mixture of volatile chlorides consisting of ZrCl_4-FeCl_3-AlCl_3,it has been possible to obtain ZrCl_4 of 97 mole% purity. 4) The same principle has been applied to the chlorinated products of caldasite to obatain zirconium chloride. 5) A process flowsheet for chlorination of caldasite to extract zirconium has been proposed.

Mossbauer spectroscopic study was performed on the ^Co-doped Ti_Ni_ and Ti_ Ni_ alloys in order to obtain additional informations on the martensitic transformation. The spectra consists of two singlet absorption lines which are due to the Fe(Co) impurities substituted at the Ti and Ni sites, respectively. The temperature variations of isomer shifts and effective halfwidths can be interpreted only by postulating two kinds of premartensitic phase. The one exists together with the martensitic phase in the temperature range between A_s and A_f, and the other between A_f and A_f+40K. Thermal scans of the resonant γ-ray transmission rate were measured at the Doppler velocities between ±1.9mm/sec and the zero-velocity, in order to observe the temperatuture variation of recoilless fraction. The anomalous decreases of recoilless fraction originated from lattice softening were found around two temperature regions which are M_s+85K~M_s+135K and M_s+45~M_s+55K. The results are discussed by bringing a comparison with the charge-density wave (CDW) model and the modulated lattice relaxation (MLR) model.

Low oxygen partial pressures in gas mixtures controlling with the H_2O-H_2 ratios have been measured by a ZrO_2 (+CaO) solid electrolyte cell. The measured P_/P_ ratios obtained by the sulfuric acid solution were found to be greater than the theoretical values by log P_/P_=0.5 in the range of P_/P_. Flow rate dependence of emf values becomes significant with the increase of the difference in oxygen partial pressures between reference and working electrodes. The flow rate greater than 1000ml/min was required for the measurement of oxygen partial pressures of P_/P_ at 800℃. The measured P_/P_ ratios was found to deviate at temperatures above 1200℃. These results have been discussed based on the electrochemical oxygen permeability across the solid electrolyte.

Volatility and relative volatility have been newly introduced to explain the volatilization bahaviour of pure Sb_2S_3 and that in its mixtures. Activity of Sb_2S_3 in the mixture can be calculated from the corresponding value of relative volatility, V_r, provided that the summation of mole amounts of gas species for the congruent volatilization of Sb_2S_3,α, is known, as given by α_=(V_r)^α. The volatility and relative volatility of Sb_2S_3 in the Sb_2S_3-FeS, Sb_2S_3-Cu_2S and Sb_2S_3-PbS mixtures at 973 and 1173K and in the Sb_2S_3-Ag_2S mixture at 1123K were measured by transportation method, and the activities of Sb_2S_3 were calculated based on the above equation with α=1.2. Activity coefficients, γ°_, at infinite dilution of SbS_-FeS, SbS_-CuS_ and SbS_-PbS systems (973 and 1173K) and that of SbS_-AgS_ (1123K), which were estimated by extrapolating the plots of log γ_ versus (1-N_>)^2,are found to be γ°_ (7.9,6.6); γ°_> (0.22,0.36); γ°_ (0.04,0.16); γ°_> (0.10), respectively.

Sintered alumina ceramics were joined without applying pressure by 3 kinds of SiO_2-CaO-Al_2O_3 glass solders having a similar expansivity as alumina. Wetting of glass/Al_2O_3 was examined by sessile drop method. The observation of interface and bending strength related to Al_2O_3/glass/Al_2O_3 systems were investigated by means of SEM/EDX and 4-point bending test. The results are summarized as follows : (1) Wetting of glass solders on alumina substrate was good at temperatures higher than 1450℃. (2) When the joining temperature was high, diffusion and/or reactions between solder and alumina took place at the interface. These diffusion and reactions occurring at the interface greatly affected the bending strength of the joined body. (3) Highest strength corresponding to 80% that of alumina was obtained by the solder of 35SiO_2-35CaO-30Al_2O_3 (mass%) glass.

A potentiostatic method was applied to the separation of gamma prime phase by anodic dissolution of the matrix of the nickel-base superalloys, which were prepared by hot isostatic pressing and mechanical alloying processes, in the solution of ammonium sulfide-citric acid and in the methyl alcohol solution of nitric-perchloric acid. The chemical analysis was made of the extracted gamma prime phase. The compositions of the gamma prime phases were determined without contamination of gamma phase in the methyl alcohol solution in the superalloys. The representative formulas were calculated for the separated gamma prime phases and the lattice parameters were determined. The atomic ratio of the concentration of aluminum to that of titanium in the gamma prime phase was approximately the same in the superalloys.

A prototype outer cylinder rotating viscometer with a direct measurement of torque exerting on the inner cylinder, was built and tested at room as well as at high temperatures. The following results are obtained : (1) Absolute value of torque exerted by viscous flow can be measured by means of a load cell or an electronic balance. (2) Measurement mechnism is quite simple and more stable than the other rotating viscometer for high temperature application. (3) There is a possibility of measuring the absolute value if the exact evaluation of torque including the end effect can be derived. (4) The viscometer is suitable for the measurement of the viscosity range from 10^0 to 10^3 dPas and at a temperature up to 1500℃.

Though expanding shale is utilized for light weight aggregate, it has a large water absorption capacity. As it is partially melted and remained solid grains at bloated temperature, the aggregate has many open pores. As the open pore may behave like a crack, strength of the aggregate may not be enough, compared to the material which is mostly melted. It is therefore necessary to produce a aggregate which is mainly composed of glass and has closed pores. In west area of Ten-ei Village, Fukushima Prefecture, pumice tuff of the latest Tertiary to the early Quaternary in Age is distributed. This pumice tuff is mainly composed of volcannic glass, and of small amounts of quartz, pyroxine, etc. The results of the experimental studies to find out suitable firing temperature and additives, and to find appropriate density and low water absorption are presented. The collected tuff is ground to -200 meshes, mixed with additives and pelleted, and then heated at desired temperature. Since the foams in fired aggregate are almost sealed, it has low water absorption, and is expected to have higher strength than the expanded shale. The concrete cylinder block (50×100mm) in the aggregate mixed, showed higher compressive strength than that in which the expanding shale is used.

Thiourea leaching of silver sulfide was studied in weakly acidic sulfate solutions containing ferric sulfate as a moderate oxidant. In the presence of ferric ions, the sulfide sulfur was converted into elemental sulfur and the silver was extracted as its thiourea complex ion, Ag(NH_2CSNH_2)_3^+. In the leaching without oxidant, silver sulfide was leached according to the H_2S forming reaction, where the elimination of H_2S from the leach liquor, for instance by nitrogen gas flow, significantly favored the leaching. In the both cases, the presence of thiourea was necessary for the extraction of silver from the sulfide. The moderate leaching conditions such as fairly low acid concentration at a level around 0.06mol/l and the operation temperature not higher than 50℃, and a high concentration of thiourea promoted the silver extraction mainly due to the increased stability of the thiourea complex ion of silver. It was also observed that silver sulfide was easily extracted in the oxidative thiourea leaching where sulfide ore consisting mainly of pyrite, arsenopyrite, stibnite and chalcopyrite coexisted.

Foam glass may soon be used as an important insulator of buildings to decrease the energy consumption. It is assumed that, large volumes of glass-rich volcanic products available in Tohoku Province, Northeast Japan are available to produce foam glass. Experimental studies on bloating of Towada vocanic materials are presented. Samples are ground to -200 mesh, and are mixed with CaSO_4,CaCO_3 and char, and then formed into pellets. The pellets are put into electric furnace at desired temperature, and kept for 20 minutes. In some case, samples are heated at 1000℃, for 10 minutes, and then heated to desired temperature. The chemical compositions of bloated samples are mostly plotted in the "area of bloating" on diagram by Riley (1951). The detritus which contain higher amount of glass and ferric iron is found to have tendency of well bloating. Addition of varying amount of char depress or elevate the dissociation temperatures of SO_x from CaSO_4 or SO_x from CaCO_3,in order to bloat at appropriate viscosity. Some additives are found to be effective to decrease bloating temperature and to control the bulk density. As the foams of the fired samples are found to be completely sealed and discrete, utilization of glass-rich volcanic product in foam glass is to be promising.

The stability and solubility of two zinc arsenites and four zinc arsenates have been determined as a function of pH by equilibrating mixtures of zinc oxide with arsenious or arsenic acid solution at 25℃. The standard free energies of formation (kcal/mol) have been calculated from the solubility data to be -219.6 for Zn (AsO_2)_2,-375.8 for 3ZnO・As_2O_3,-271.5 for ZnHAsO_4・H_2O, -1226.6 for Zn_5H_2 (AsO_4)_4・6H_2O, -908.7 for Zn_3 (AsO_4)_2・8H_2O and -297.7 for Zn_2AsO_4OH. The equilibrium log [As]-pH diagrams have been constructed for the Zn (II)-As (III)-H_2O and Zn (II)-As (V)-H_2O systems by using the thermodynamic data obtained in this study, and they show the relative solubility of arsenic from zinc arsenites and arsenates.

A new pyrometric technique for temperature measurement has been developed by processing the radiation spectrum on the basis of two-color pyrometry. The technique has the capability to measure the surface temperature of materials without the need to know the surface optical properties as required in the conventional two-color pyrometry. An important characteristic of this technique is that, one can examine the radiation spectra emitted from the surface of the material and select, by visual inspection, the wavelength range of the spectra suitable for the temperature estimation. The present technique was applied to measure the surface temperatures of oxidized stainless steel specimens which were kept at a constant temperature and pulverised coal particles which were subjected to heating. The results of these tests proved that the technique is effective for surface temperature measurements.

Breakthrough properties of uranium have been studied using columns packed with various zeolites. Breakthrough behavior in the acidic region was characterized by S-shaped curves for either A, X or Y zeolite columns, whereas the uranium readily flowed out of mordenite (M) or L zeolite columns. The amount of uranium adsorbed decreased in the order, Y>X>A≫M>L. In the acidic region, uranium was adsorbed inside the zeolite particles through an ion exchange reaction. More than 90% of the adsorbed UO_2^ could be eluted with 0.1M Na_2CO_3. In the neutral region, no uranium flowed out owing to adsorption of its hydroxides on the surface of the particles and the wall of the column. The breakthrough ratio increased with the effluent volume in the alkaline region resulting from adsorption of hydroxides and effluence of carbonate complexes. The mutual separation was accomplished by passing the solution containing uranium and americium through the column packed with M or L zeolites; uranium was removed by the effluent and americium was retained in the column.

Since rare metals have many advantages in high advanced technology fields, a stable supply of these metals is very important in a highly industrialized country like Japan. Developing an urban mine in which these metals are condensed is a possible solution to this problem. In this report, we discuss the recycling of tantalum from capacitor scrap via a chloride process. The results are as follows : 1) Capacitor scraps reacted with Cl_2 gas at about 623K producing TaCl_5,while Ta_2O_5 and MnO_2 did not react with Cl_2 and remained as residues. 2) Mn content in recovered TaCl_5 was decreased to 0.007%, but that in the residue was enriched to 13.2%. 3) In the case of capacitor chlorination, a low reaction rate of 55% was obtained. Some pretreatment like crushing must be considered. 4) Chlorination of ground capacitor scrap powder after reductive leaching gave a high reaction rate of 95% and a low Mn content in TaCl_5 of less than 1ppm. 5) The probable process for recycling of Ta capacitor scrap corresponding to advanced material production was proposed based on the above results.

Carbon-reduction smelting of a mixture of Nb_2O_5 and TiO_2 at nearly 2800K under 0.1 MPa has been examined to investigate the feasibility of direct preparation of Nb-Ti alloys (Ti=45-50 mass%). A laboratory-scale plasma reactor and a 10%H_2-Ar plasma arc as heating source were used. The sum of oxygen and carbon contents in the alloy products obtained after 60min of reduction for the charge with 0.98 to 1.02 of C/O mole ratio was reduced to less than 2 mass%, but it was difficult to get lower than that value. The loss of Ti by evaporation of Ti-oxycarbide (Ti-O-C) was found to be significant during reduction but Nb-loss was scarcely observed. Therefore, the composition of Ti in the products decreased to nearly 40 mass%. These results indicate that deoxidation and decarburization from the Nb-Ti-O-C melt proceeded by evaporation of Ti-oxycarbide besides CO-degassing. The products were composed of two phases which were an Nb-Ti alloy phase containing a small amount of oxygen and carbon and a Ti-C-O precipitate phase containing Nb. Superconducting transition temperatures of these products were 9 to 10K.

The anodic and cathodic reactions at Pt, Ti and carbon electrodes in Mn (NO_3)_2・6H_2O melt were studied at 60～100℃ by the potential sweep method, the potential step method, constant potential electrolysis and constant current electrolysis. The possibility of MnO_2 production in this melt was also discussed. MnO_2 deposition is observed as only one anodic reaction in this melt. Anodic current efficiencies are as high as about 95% under any electrolytic condition. Both carbon and Ti, which are popular anode materials for MnO_2 electrolysis in MnSO_4 solution, can be used as an anode even in this melt. Treating their surface by our procedure, the carbon anode shows less overpotential in comparison with the Ti anode. Cathodic reactions in this melt are more complicated than the anodic reaction. Four cathodic reactions exist at the Pt electrode and three reactions at the carbon electrode. Some of the peak current densities increase with added amounts of HNO_3. Effects of HNO_3 addition on a voltammogram show that hydrogen ion is involved in some cathodic reactions. It is important to keep the cell voltage low and stable for MnO_2 electrolysis in this melt. The results from this study suggest that carbon is better than Ti as an anode material and that addition of HNO_3 is necessary and effective with regard to the cathodic reactions.

Preparation of a stable aqueous dispersion of fine particles of hematite and magnetite was investigated utilizing an oil (n-decane)-in-water emulsion. The experiment involves (1) preparation of a stable suspension of oxide particles in n-decane (oxide decane suspension) and (2) preparation of oil-in-water (O/W) emulsion using the oxide decane suspension and water in the presence of sodium dodecyl sulfate (SDS) as an emulsifier. In process (1), the oxide decane suspension was prepared by two different methods. First, oxide particles were made hydrophobic with sodium oleate in an aqueous suspension at about pH 6. After dewatering and drying, the oxide particles were dispersed into n-decane. The alternative is dispersing the oxide particles into n-decane with the aid of an oil-soluble surfactant (Aerosol OT). In process (2), O/W emulsion was prepared ultrasonically from a mixture of a hematite decane suspension and water (about 1 : 10 by volume) in the presence of 1×10^ mol/l SDS, whereby the oxide particles were included in the oil particles. Oxide-included O/W emulsions prepared by the sodium oleate method revealed better stability than by the Aerosol OT method, while the more stable oxide decane suspension was available by the latter method. A similar experiment was undertaken in which the O/W emulsion was changed to a microemulsion by the addition of an appropriate amount of n-butanol. However, it was difficult to obtain a stable oxide dispersion, because the oxide fine particles were excluded from the aqueous phase upon the formation of the O/W microemulsion.

For the accumulation of a fundamental knowledge about the behavior of glass solder during the joining of ceramics, the wettability of glass on solid oxides has been measured by a sessile drop technique. Pyrex glass was selected as an example of glass while alumina, magnesia, and lime stabilized zirconia were used as substrates. At higher temperatures, a reaction took place between the solder and substrate. New phases appeared as a result of this reaction. These new phases were investigated by means of a microscope, XMA line analysis, SEM, and X-ray image analysis. The following results were obtained : 1) The apparent contact angles between glass and oxide substrates (Al_2O_3,MgO, ZrO_2 (+CaO), and SiO_2) ranged from 140 to 150°at temperatures between 1000 and 1100℃, but decreased rapidly beyond the temperature determined by the kind of oxide, such as 1100℃ for ZrO_2(+CaO), 1250℃ for MgO, and 1350℃ for Al_2O_3. For the silica substrate, such a rapid decrease in contact angle was not observed up to 1350℃. 2) Density and surface tension of pyrex glass are estimated as 2.22～2.20 g/(cm)^3 and 350～400 dyne/cm, respectively, at temperatures between 1100 and 1200℃. These dara are obtained by the experiment using alumina and silica substrates which are stable within this temperature range. 3) An alumina substrate reacts with the glass above 1300℃ and forms an alumina rich glass phase on the joining surface whose adhesion is good. 4) A magnesia substrate precipitates a crystal phase grown into the glass above 1350℃. Adhesion of the crystal to substrate is good but cracks was generated in the glass phase. 5) CaO dissolves into the glass from the zirconia substrate and glass permeates into the substrate through open pores in the zirconia above 1100℃. Thus, a four layer structure, glass/CaO rich glass/glass permeated substrate/zirconia substrate are formed. The joining of the glass and substrate is rather good, but a crack arose from the glass permeated layer into the substrate.

Metallic Ni ultrafine particles were prepared by the chemical reduction in a liquid-phase using LiAlH_4 or NaBH_4. The average particle size of these particles was below 100nm, which was also suggested by the observations using Transmission Electron Microscope. X-ray diffraction analysis of Ni ultrafine particles resulted in the formation of amorphous Ni metal. Ni ultrafine particles prepared with LiAlH_4 were found highly active for benzene hydrogenation to cyclohexane. It is also noted that the catalytic activity of amorphous metallic Co ultrafine particles obtained for the benzene hydrogenation exceeded that of Ni particles. α-Fe_2O_3 particles were converted into metallic Fe ultrafine particles with LiAlH_4 in nonaqueous media, having no catalytic activity for the hydrogenation reaction. Fe_3O_4 ultrafine particles were also obtained by the present method.

Incinerator residue from the incinerating of municipal solid wastes is, in most cases, disposed of by burying it underground. However, due to the difficulty of obtaining land for landfill disposal, it became extremely important to develop a treatment for reducing its volume and making it harmless. Melting treatment is expected to be available for solving these demands. In this work, plasma arc melting of the residue has been examined using a pilot-plant-scale 240kW DC plasma arc furnace developed for treating of the residue. Air was used as the plasma generating gas. With air-plasma-arc heating, the residue was perfectly melted above 1500℃ and resulted in two phases separated into molten slag and molten metal. As a result, power consumption was approximately 0.88 kWh/kg of the residue at a feed rate of 182 kg/h. Therefore, this melting process is considered to be useful for the practical melting of the residue. Also, the residue was reduced in volume by 1/2 and was made completely harmless. The slag produced by melting the residue is, therefore, expected to be reused as roadbase materials, etc.

The stability and solubility of four barium arsenites and three barium arsenates have been determined as a function of pH by equilibrating mixtures of barium hydroxide with arsenious or arsenic acid solution at 25℃. The standard free energies of formation (kcal/mol) have been calculated from the solubility data to be - 406.6 for BaH (AsO_2)_3,- 363.4 for Ba (AsO_2)_2・H_2O, - 624.2 for Ba_2 (AsO_2)_3OH・H_2O, - 1461.1 for Ba_5 (AsO_2)_6 (OH)_4・2H_2O, - 550.5 for Ba (H_2AsO_4)_2・H_2O, - 368.5 for BaHAsO_4・H_2O and - 739.8 for Ba_3 (AsO_4)_2. The equilibrium log [As] - pH diagrams have been constructed for the Ba (II)-As (III)-H_2O and Ba (II)-As (V)-H_2O systems by using the thermodynamic data obtained in this study. They show the relative solubility of arsenic from barium arsenites and arsenates.

Valleriite- (Mg, Fe) is found in heavily serpentinized Ni-Cu ore of the Jinchuan magmatic ore deposit in Gansu Province, China. It occurs as massive or vein-like aggregates of small prismatic crystals up to 0.01×0.1mm in size together with pyrrhotite, pentlandite and a small amount of chalcopyrite. Reflection pleochroism is distinct : reflected light changes from brownish yellow to brownish gray with a blue tint. Reflectance : 12.7-13.1 (481nm), 13.8-15.0 (547), 13.5-16.0 (591), 14.1-16.0 (647). Under crossed nicol, bright bronze yellow to dark. It contains Fe, instead of Al, in its hydroxide layer, and analysis with EPMA gives the formula [Cu_Fe_Ni_S_2]・1.47[Mg_Fe_(OH)_2]. Its X-ray diffraction pattern is well explained by a hexagonal system with the cell parameters, a=3.791A, and c=34.55A. Paragenetic texture suggests valleriite- (Mg, Fe) is an alteration product from chalcopyrite and/or cubanite at the serpentinization or later chloritization stage.

A mathematical formulation was proposed for the simulation of gas flow in the sludge furnace which was made of packed bed and free board. As for the equation of motion for the gas, Ergun's equation with the inertial term was used for the packed bed, while the k-ε turbulence model was used for the free board, The applied solution algorithm was an extension of the SIMPLE algorithm to make a general curvilinear coordinate formulation of the governing equations. For this purpose, a body fitted coordinate system was applied to the gas flow analysis. The system is a curvilinear coordinate system that generates the grid by solving a system of elliptic equations. The generated grid is coincident with each segment of the boundary of a region. By transforming the fundamental equations described in the form of partial differential equations into such a coordinate system, a finite-difference method was able to be applied for obtaining the three-dimensional numerical solution on gas flow. A staggered grid system was adopted for the scalar variables and velocity written in the general curvilinear coordinates. The convection terms in the governing equations was approximated by the hybrid scheme. The flow characteristics were obtained for the packed beds which had irregular shapes and for the sludge furnace consisted of complicated shapes of packed bed and free board. This procedure has many practical engineering applications.

Sulfide particles observed in the solidified copper slag are caused by both mechanically entrained and chemically dissolved sulfides in the molten slag. The microscopicstructure of suspended white metal in the converter slag which was gradually cooled is illustrated in Photo 1. The following crystallites are recognized : 1) Bluish-grey matrix containing high copper content-Cu_2S solid solution ; 2) Bluish-purple copper sulfide phase-bornite solid solution which is separated from copper sulfide solid solution by miscibility gap (see Fig.1) ; 3) Small alloy phase containing antimony and nickel, exhibiting similar color to metallic copper ; 4) White crystallite having such shape as linear or chain type-PbS ; 5) Dark-bluish-grey crystallite-ZnS. The results of EPMA analysis of the above crystallites are shown in Table 1. The microscopicstructure of the sulfide particles separated from the converter slag during the solidification is shown in Photo 2. These particles have been found and reported in our preceding paper (see its Photos 2 and 3). It is consisting of eutectic structure of Cu_2S and PbS (see Fig.2). Two kinds of sulfide particles separated from the flash smelting furnace slag have been reported and illustrated in our preceding paper (see its 4 and 5 of Table 2). Besides these sulfide particles originated to dissolved copper and zinc in the slag, mechanically entrained sulfide particles are often observed in the slag, and, as an example, the microscopicstructure of such complex sulfide particles is shown in Photo 4. The following crystallites are recognized and the results of EPMA analysis given in Table 2 : i) Reddish-purple homogeneous phase-bornite solid solution ; ii) Yellow homogeneous phase-chalcopyrite solid solution ; iii) Greyish-blue leaf-like crystallite-ZnS-FeS solid solution ; iv) Fine eutectic crystals consisting of bornite and white lead sulfide. It should be noticed that such structure is different substantially from that of the matte, and it seems to be molten material of complex copper concentrate itself. Photo 5 shows the microscopicstructure of the matte taken out of a flash furnace, and the following phases having the compositions shown in Table 3 are recognized : a) Light-blue matrix-bornite solid solution ; b) Yellow pyrrhotite solid solution ; c) Angular crystallite-magnetite ; d) Scattered small light-grey round crystallite-wustite ; e) Dark-grey fayalite-minor in amount ; f) Light-greyish crystallite contiguous to pyrrhotite-ZnS-FeS solid solution (see Fig.3) ; g) White metallic ultra fine crystallite containing lead. As have been clarified in our previous reports, a considerable amount of iron oxide and even silica of a small amount can be dissolved in the molten matte. Accordingly, the phases a) through e) above are common constitutents in the copper matte. Although zinc in the matte crystallizes as the solid solution of ZnS-FeS, most lead seems to be separated as the metallic form and sometimes containing antimony, arsenic, nickel and other metals.

The physical chemistry of surface and interface at various temperatures has relatively advanced, and the mechanism of the process has been introduced in the field of the engineering as an information that will predict and control many present conditions, especially such as mineral flotation and the penetration between slag and metal or matte, which well illustrated by the surface phenomena. In the same manner the surface phenomena are probably important in the explanation of the extraction of sulfur from ores, but at present, they are incompletely understood. In the distillation method and the autoclave method concerning the most elementary surface properties-the system of liquid sulfur-gas (L-G), liquid sulfur-gangue-gas (L-S-G), liquid sulfur-superheated water (L_1-L_2), and liquid sulfur-superheated water-gangue (L_1-L_2-S), the existing data are limited to the surface tension of liquid sulfur. Furthermore, considerable discrepancy in values of the surface tension of the temperature of the viscous range of the liquid sulfur, which has been found by many workers, is presented. Great difficulty in measurement, as the temperature rises from 160 to 300℃, may be due to the extremely high viscosity of liquid sulfur which has been often described as the formation of poly-sulfur chains of varying length. Therfore, in the first place, it is necessary to fundamentally redetermine the values of the surface tension of liquid sulfur for the illustration of the above phenomena connected with the extraction of sulfur from ores, although the range of temperature applied to the autoclave method is below 160℃ and it is higher than the boiling point of sulfur in the distillation method. The experimental work in this paper represents a work in which interfacial tension of liquid sulfur with nitrogen, and the effects of the impurities such as selenium and arsenic which are often contained in the volcanic sulfur ores in this country were studied on the surface tension of liquid sulfur. Two methods of the maximum bubble pressure and the pendant drop are accepted on the measurement. However, in the first method the constant values were not given at any temperatures in the viscous range, because it is assumed to be the effect of the extremely high viscosity of poly-sulfur. But in the latter method, it successfully gave the values in this range from the determination of the equilibrium point, which indicates the stationary hanging state of the drop, by the cinematographic analysis of the slowly moving and falling drop of the liquid sulfur. This experimental technique and results are given in this paper. The results of the measurements show that the surface tension of pure liquid sulfur decreases linearly as the temperature rises, but the change of the temperature dependence of it exists at about 160℃. The following equations representing the change of the surface tension of the temperature are calculated from the experimental results : [numerical formula] where γ is the surface tension of pure sulfur with nitrogen atmosphere in Dynes・cm^ and t is the temperature in ℃. The effect of selenium and arsenic in pure sulfur caused the increasing of the surface tension of pure sulfur. These results are found in Figs. 12 to 14 of this paper.

The research described in this paper was carried out with a view to obtaining information about the effect of solution pH on the mechanism of precipitation, the rate of precipitation and the appearance of reduced copper. The rates of precipitation were determined over a wide range of ammonia and ammonium sulphate concentration. The results are described and discussed on the basis of equillibrium potential-pH diagram of Cu-SO_4^-NH_3-H_2O system in the present paper.

Mechanical working of a TiNi shape memory alloy by machining was discussed as well as attempts to fabricate pipe connectors. The results obtained so far are satisfactory. Although the process of machinability is difficult and complex, the working method presented in this paper offers a new possibility.

The ARSME is found to be obtained by constrained aging in Ti-51at% Ni alloy. ARSME belongs to reversible shape memory effect, so the spontaneous, reversible and repeatable shape change occurs according to heating and cooling, and the curvature of the specimen turns upside down between Af and Mf temperature. This paper represents the nature of ARSME, its optimum generating conditions, shape changes under applied stress and the electron microscopy of aging samples. The results are summarized as follows : 1) ARSME is associated with two-step transformation and strain fields between matrix and precipitations. 2) The two-step transformations appear by aging below 773K. 3) Optimum aging temperatures of ARSME are 773K and 673K. 4) The reversal of curvature does not take place by aging at 773K for more than 32.4ks. This phenomenon occurs in the case of aging at 673K for more than 3.6×10^2ks. 5) Shape changes with intermediate phase transformation have nearly perfect reversibility with thermal cycle. 6) On cooling, the opposite load at which the shape changes with intermediate phase transformations can be suppressed is about one half of that of reverse transformations on heating. 7) The morphology of intermediate and martensite phases coexisting with particles of the precipitate is very different from that of the single phase.

The dissolution behavior of chromium into iron-silicate melt is important in considering metallurgical processes or the disposal of solid waste material. However, little is known about the phase diagram of the iron oxide-chromium oxide-silica system. In this paper, the equilibrium phase relation of the FeO-Cr_2O_3-SiO_2 system when in contact with metallic iron has been clarified at temperatures of 1230 to 1400℃ under a nitrogen atmosphere. Through microscopic and EPMA examinations of samples prepared after melting and quenching in an ice-bath, the following facts have been presented : (l) An isothermal section at 1300℃ is drawn for a region containing the melt. Chromium is found in the melt and wustite or the spinel phase as a solid solution. (2) The temperature dependence of the liquidus surface is confirmed. The homogeneous liquid region becomes greater with increasing temperature, and the solubilities of Cr_2O_3 in iron-silicate melt at 1230,1300 and 1400℃ are 1.5,3 and 5% respectively. On the basis of the above results, the applicability of melting treatment of waste materials and the interaction between fire brick and slag are discussed.

The mass transfer coefficient surrounding the iron oxide pellet in the gaseous reduction under a low flow rate of reducing gas was examined. It has been reported qualitatively by other researchers that the overall reduction rate was influenced by the product gas of reaction. However, its effect has not been evaluated quantitatively. In this paper, in order to obtain a useful information on the quantitative evaluation of the effect, the reduction rates of iron oxide pellet with hydrogen were measured under various flow rates of reducing gas and different flowing conditions of the gas. Two different experimental methods were used for the flowing conditions of the gas. That is, the reduction of a single pellet in the empty tube and in the packed bed composed of alumina balls. By applying the rate equation derived on the basis of the unreacted core model to the experimental reduction curves, the mass transfer coefficient through gaseous phase were evaluated. The mass transfer coefficient surrounding the pellet can be expressed by the following empirical equations : Sh=0.12 (Re_p)^ (Sc=0.35,0.5 (Sc=0.35,0.5

Blank values accompanied with the measurements of diffusion in molten state were examined with respect to diffusion of Si and Mn in molten Fe-C alloys. Diffusion coefficients of Si and Mn reported in the previous papers were recomputed by using an appropriate correction method with the following results. i) Diffusion coefficients of Si in Fe-C (saturated)-Si(1.5%) alloys can be expressed as follows : logD(cm^2/sec)=-3.62-0.179×10^4/ T, or D(cm^2/sec)=2.40×10^e^/T. Activation energy Q≒8,200 cal/g・atom That is, diffusion coefficient D between 1,400-1,600℃ was 2.0-2.7×10^cm^2/sec. ii) Those of Mn in Fe-C (saturated)-Mn(2.5%) alloys can be expressed as follows : logD(cm^2/sec)=-3.71-0.127×10^4/T, or D(cm^2/sec)=1.93×10^e^/T, Activation energy Q≒5,800 cal/g・atom That is, diffusion coefficient D between 1,300-1,600℃ was 3.0-4.1×10^ cm^2/sec.

In this paper a method for producing niobium from columbite was proposed by the authors. The columbite used contained 51.20 Nb_2O_5,16.53 Ta_2O_5,6.06 TiO_2,2.50 WO_3,2.62 SnO_2,1.08 SiO_2,14.79 FeO, and 5.21 wt. % MnO. Before producing the metal niobium, it was necessary to extract pure niobium compound from ore. The first step of decomposing the ore to prepare a mixture of niobium and tantalum pentaoxide was attempted by means of the fusion with alkali fluxes. The second step of separating niobium from tantalum was proposed for the solvent extraction. Niobium pentaoxide obtained was converted to pure compound such as K_2NbF_7. The last step of producing of niobium was carried out by electrolysis of the fused salt mixture. The conditions to be preferred for the above step are given as follows : (1) Fusion with sodium hydroxide and sodium peroxide. It was preferred to use a mixture of sodium hydroxide and sodium peroxide as flux for columbite. The optimum fusion mixture was found to be 1 part of-100 mesh ground ore, 2 parts of NaOH, and 0.5 part of Na_2O_2. The alkali mixture was preliminarily heated in a nickel crucible to above the melting temperature and the ground ore was added in small portions so that a gentle reaction might proceed. After the addition of the ore the temperature was kept at 600℃ for 40 to 60 minutes. The solidified melt was digested with hot water. The insoluble sodium niobate and tantalate were separated from most of soluble impurities, particularly, tungusten and tin. The niobate and tantalate were decomposed by hydrochloric acid which dissolved manganese and iron eventually. It was relatively difficult to remove titanium. The yield of the mixture of niobium and tantalum pentaoxide from columbite was about 90%.(2) Solvent extraction with MIBK-HF-H_2SO_4. The preparation of the pregnant solution was made by dissolving the mixture of both pentaoxides in 56% HF solution. The pregnant solution composed of 20.40 Nb_2O_5,5.48 Ta_2O_5,1.20 TiO_2,0.42 SnO_2,0.45 FeO+MnO, and 22.89g HF per 100g of solution. This solution was adjusted to contain 100g of total pentaoxides with various acidities of HF and H_2SO_4. The equilibrated MIBK phase with 6.8N HF-7 N H_2SO_4 solution was capable of extracting 62.81g Nb_2O_5,and 22.28g Ta_2O_5 per liter. The stripping solution adjusted to 0～2 N HF and 0～2 N H_2SO_4 was used for recovering niobium and tantalum in the usual manner. The niobium pentaoxide extracted contained 8～9% Ta_2O_5,and tantalum pentaoxide 20～40% Nb_2O_5. Therefore it was necessary to repeat the extraction for preparing pure niobium compound.(3) Electrolysis of K_2NbF_7 with alkali halides. Pure niobium metal was prepared by the electrolysis of fused salts of K_2NbF_7 and NaCl, and the eutectic mixture of NaCl and KCl. Before the electrolysis, the liquidus curves of pseudo-binary system of K_2NbF_7 and KCl, and that of K_2NbF_7 and NaCl were determined. Thereafter the electrolysis was performed on the composition of 20% K_2NbF_7 in NaCl at 800℃, and in NaCl-KCl eutectic mixture at 750℃. In a run of NaCl mixture the dendritic cathode deposit was obtained for 450-600A/dm^2 of the cathode current densities. On the other hand a coarse deposit was obtained from the eutectic mixture of NaCl and KCl on the same condition as above. The general trend in the electrolysis showed that the current efficiency was about 20% for 20% K_2NbF_7 in NaCl at 800℃, and 10% for 20% K_2NbF_7 in NaCl-KCl eutectic mixture at 750℃.

φ-σ analysis for the chloride, fluoride and bromide systems was carried out in the manner already described in the previous paper. The φ-σ relations of the each inorganic halogen compound systems show φ-σ circles and the central points of φ-σ circles are arranged on the several center circles, which are related to valency. The consideration based on the results of Δ-δ analysis for azeotropic systems of the orgrnic compounds was given for the centre circles of the inorganic halogen.

In the previous paper, the authors reported the solubility of TiO_2 in fused K_2TiF_6-alkalihalide systems. In order to study the behavior of fused salt during the electrolysis the authors employed the measurments of the decomposition voltage of these fused salts by neutral electrode method. In the current vs. voltage curve the authors obtained two break points. To explain the electrode reactions concerning these two points, the reversible decomposition voltage was calculated on the data of thermodynamics, and it was estimated from the reaction taking place at the electrode that the first point was the formation of titanium suboxide and that the second point depended upon the formation of titanium metal from TiO_2.

Various amounts of barium sulfate of constant specific activity were collected uniformly on filter papers and their radioactive intensities were measured by the Geiger-Muller counter of end-window type. Self-absorption curve now obtained was well expressed by the following equation and as the value of self-absorption coefficient (μ), 0.22 (cm^2/mg) was obtained : [numerical formula] where I is the intensity of sample whose thickness is d and I_∞ is the intensity of sample of infinite thickness.

The present paper deals with a series of experiments in applicability of the low-intensity, high-intensity and roast-magnetic separations for laterite ores. Three samples of gravity concentrates from different localities were used in tests. It was identified by means of microscope, Vickers hardness tester, electron probe X-ray microanalyser and X-ray diffractometer that most of chromium minerals in laterite ores were magnesiochromite, about 20～30% of spinel being present in chromium iron oxide. It was defined that the limit for the grade of the chromite concentrate to be obtained from these types of ores was about 45～51% of Cr_2O_3,the grade of chromite concentrate obtained by means of roast-magnetic separation being about 39～44% of Cr_2O_3. The low-intensity magnetic concentrate was mainly composed of magnetite, containing about 60～63% of Fe and the roasted magnetic one of goethite, hematite, etc. contained about 55% of Fe and appreciable amounts of chromium, nickel and aluminium.

Using a CaO crucible, the equilibrium of the following reaction was studied under the conditions of 2CaO・SiO_2,3CaO・SiO_2,or CaO saturation in the temperature range from 1,550° to 1,600℃. [chemical formula] The equilibrium constant of the reaction (1) becomes as follows : [chemical formula] As was already published in the previous papers, which reported on the SiO_2-CaO binary system saturated with SiO_2 or CaO, the activity of pure SiO_2 was taken at unity as a standard state of aSiO_2. In this case, K_ and K^S_ were equal at a given temperature. Thus, aSiO_2 in the molten SiO_2-CaO-Al_2O_3 ternary slag was calculated from the following equation : [chemical formula] Finally, the authors determined the liquidus line of 1,550° and 1,600℃ on the CaO side of SiO_2-CaO-Al_2O_3 ternary diagram from the equilibrium compositions of slags.

Some fun lamental experiments on the removal of arsenic from the speiss resulting from lead smelting were carried out. The composition of the speiss was Ni 32.6 Co 6.4,Cu 11.0,S 4.0,Fe 1.4,Pb 1.5,and As 40.0%. The results of the oxidizing roasting by air are reported in this paper. The change in weight of the speiss heated slowly in air was measured with a thermo-balance, and it was found that a preliminary roasting at lower temperature was unnecessary. Therefore experiments were carried out at constant temperature. The optimum roasting condition was as follows : Grain size of the charge -200 mesh ; temperature 750℃ ; blast amount 1.37 liter/hour/g. of charge ; time 60 min. It was found that only about 50% (apparent value) of arsenic in the original speiss could be removed under the above condition by one operation and the repetition of operations was without any effect.

In the Institute, a joint investigation of "Selective Sulphatization-Flotation Process" was carried out by way of a treatment of complex sulphide ores. The present paper is a part of the work concerning the degree of liberation of the ores. Eleven kinds of ores mentioned in Table 1 were crushed and sized particles were conglomerated with bakelite, polished and then observed under reflecting microscope to determine the degree of liberation. The results are shown in Tables 2 to 12 and Figs.1 to 11. As a whole, the most difficult ores to liberate were so-called "Black ore" type, the most easy ones were vein type and the ores of contact mentasomatic type were moderate. The relation between particle size and degree of liberation is shown in Figs.13,14 and may be illustrated as equation, L=b-aS, where L is degree of liberation, S is size of particle, a and b are constants. The constants a, b and integrated value I_L of the measured ores are given in Table 13. The grade of the difficulty with which ore liberate monomineral grains may be shown by these constants.

Most of the ore-forming sulphide and oxide minerals occur in mutual solid solutions at high temperatures. After cooling, however, some of them appear as minute spots, parallel or lattice-shaped lamellae, skeleton crystals, cell-formed membranes or small grains. Lattice intergrowth of ilmenite in magnetite, chalcocite or chalcopyrite in bornite, etc., minute spots of chalcopyrite in sphalerite, star-shaped skeleton crystals of sphalerite in chalcopyrite and many others are of very common occurrence. When such mixtures are heated up to certain temperatures, they dissolve one another to form homogeneous solid solutions, which remains as such after quenching at room temperatures. When gradually cooled, however, such artificial solid solutions separate into more than one minerals, intergrowing with one another. Some of the experimental results on these changes are stated and their significance in dressing and smelting is considered in this paper.

Many domestic pyrite concentrates contain small amounts of copper, cobalt and zinc. Owing to the inability to maintain proper temperature and atmosphere by the past furnacing equipment, selective sulfatizing of the individual components in these ores has hardly been realized in actual practice. In the past few years a new type of equipment, the fluidized-bed roaster, has become available. It has revived interest in selective sulfatizing because of the ease with which the roasting conditions in the furnace can be uniformed. This paper describes the results of experiments carried out by the fluidized-bed reactor which has the capacity of 5 kg ore per day, and shows that it is useful in treating copper, cobalt and zinc bearing pyrite to produce water soluble sulfates of these metals while retaining most of iron in insoluble oxide form. The theoretical considerations on the gas composition and its distribution in the furnace, the reacting temperature and the holdup time of the solids in the furnace are also discussed.

Kuhn's method was found to be the most effective of the distillating process, but there are few experimental results published on the Kuhn's distillation processing of silicon tetrachloride as a raw material for semiconductor grade silicon. The present authors designed and built an experimental Kuhn's distillating equipment and determined its operating conidtions. Spectroscopic analysis of silicon tetrachloride purified by this process was carried out, and as a result it was found that the kuhn's process can be applied effectively to the purification of silicon tetrachloride. These results are given in four figures and three tables in the following paper.

The recovery of sulphur from copper smelter gases is an important subject that has been given much consideration. In this paper a physico-chemical study on the method, "Orkla process", which recovers sulphur as elemental form, is described. First, some theoretical calculations based on the known thermodynamical data concerning the forms of gaseous sulphur, metallurgically the most important and interesting of all the elements, have been carried out at various temperatures and it has been found that at lower temperature the vapor consists mainly of S_8 and S_6,with increasing temperature, S_8 dissociate to S_6 and S_6 to S_2 and above 900℃, it consists almost of S_2. Second, various oxidation and reduction reactions with respect to the equilibrium between sulphur, carbon and oxygen at high temperature have been investigated thermodynamically and it has been found that among the reactions as to the reduction of SO_2,the one by CO gas is predominent at lower temperature and with increasing temperature, the reduction by carbon, especially at higher temperature the following reaction becomes remarkable : SO_2(g)+2C(graphite)=1/2S_2(g)+2CO.

In the previous paper, mineralogical changes of chalcopyrite heated in the open air was described. In the present report, same mineralogical studies of heated chalcopyrite grains was carried out in the nitrogen atmosphere, and the process of the changes of Cu-Fe-S components in the copper blasting furnace was considered. Changes of the desulphuration amount heated between 100°-950℃ are shown in Fig.2. In the quenched experiments, all samples are observed in one phase but in the slow cooling samples, bornite, metallic copper, chalcocite and pyrrhotite are unmixed successively as shown in Table 1. Some part of the chalcopyrite is resolved into Cu_2S, FeS and S by heating as seen in equation [1]. FeS is included in chalcopyrite as solid solution and above 900℃ separated as pyrrhotite. Bornite is formed by the reaction of Cu_2S and chalcopyrite as shown in equation [2] but excess CuFeS_2 or Cu_2S composition is included as solid solution. At lower temperature it shows nearly chalcopyrite characters but at higher temperature it indicates chalcocite natures. In this experimental condition, metallic copper is crystallized by a reaction shown in equation [7].

The present paper represents an investigation of the micro-structure of some iron-bearing materials which were specially made for this investigation and some practical sinters. As the reducibility of some of these iron-bearing meterials had been determined in the previous work, in this work, the relation of the structure to the reducibility was considered from a microscopic study. Moreover, in order to investigate the formation of iron oxide crystals and their intergrowth, further series of experiments were carried out at the higher range of sintering temperatures. The briquetted samples containing various amount of FeO, SiO_2 and CaO or Fe_3O_4,SiO_2 and CaO which were prepared in the room, were heated at the temperature range between 1,200℃ and 1,400℃ in the atmosphere of mixed gas of 40% CO and 60% CO_2,or 5～10% CO and 95～90% CO_2. Then the structure of these samples and some practical sinters were compared with one another, and studied with the microscopic photographs.

Using the apparatus utilized in the second report, the density of molten alloys of Sb-Sn and Sb-Pb systems and some type alloys was measured, and these results are shown in the relation of density-temperature and density-composition of alloys. Also utilizing the torsional oscillation method reported in the first paper, the viscosity coefficients of molten alloys of Sb-Sn, Sb-Pb and Al-Cu systems were measured. Al alloys containing small amount of Mg, Si or Mn separately were subjected to measuring their viscosity coefficient in molten state. Mn was most effective in rising this coefficient of molten Al, followed by Si. Kinetic viscosity coefficients (η/ρ) of Zn, Cd, Pb, Sn, Al and Sb were calculated.

The present paper describes the experiments on microstructure, X-ray diffraction, microhardness and reduction test of three calcium ferrites existed in the CaO-Fe_2O_3 binary system. The results obtained are as follows : 1) In the identification of three calcium ferrites, dicalcium ferrite can be identified microscopically by using some etchants. Mono- and hemi-calcium ferrites can be distinguished by the use microvickers at the same time. 2) Based on the result of X-ray diffraction, the peak intensity of hemi-calcium ferrite line lies at d_0 value of 2.612A. 3) In the reduction test, Mckewan's equation can be applied to mono- and hemi- calcium ferrites but not to dicalcium ferrite.

The present paper deals with the general rule for pelletizng of the different types of fine iron ores, namely Indian hematite, Kamaishi magnetic concentrates and Kutchian limonite. The results obtained are summarized as follows : (1) The grinding characteristics of ores can be represented by the size modulus, k and by the size distribution function, m through Gaudin-Schuhmann equation. The value of m is determined by the type of ores and that of k decreases with the increase in the grinding time.(2) The compressive strength of green pellets increases linearly with the increase in the specific surface area of the raw materials as measured by the air permeability method and it is independent of the type of the raw materials studied. The compressive strength of both the green and dry pellets increases with the decrease in the values of the size distribution parameters, k and m and such effects are more remarkable in the case of dry pellets.(3) There are optimum values of moisture content for green balling for the specific ores and the range of the optimum moisture content becomes narrow for the green pellets of higher compressive strength, resulting in the difficulty in balling operation.(4) The compressive strength of the burnt pellets produced from the same ore is mainly determined by the porosity of the pellets. The effect of the reduction in particle size of ores is compatible to that of the rise in the firing temperature.

This paper discusses the preparation of mercaptans, phosphorus polysulfides and trithiometaphosphates in the reaction between alcohols and phosphorus pentasulfide.

The present paper deals with the growing process of pores in metallic iron phase formed in synthetic wustite during the reduction with hydrogen. The results obtained are summarized as follows : (1) The microscopic examination shows that the metallic iron formed in wustite contains both porous and dense phase. It is considered that the dense phase appears as a result of the small pores being embedded by the polishing for microscopic observations. In reality, many small pores were observed in this phase by the scanning electron microscope image. (2) Oxide phase was also detected in this "dense" metallic phase. (3) The growing process of pores is considered as follows : Metallic iron phase with small pores and oxides precipitates from wustite. Pores grow continuously after the precipitation of metallic phase. Consequently, porosity and pore size change from inner part of sample to the outer surface, corresponding to the growing process of pores.