In order to make a simple analysis for the lateral vibration of an off-shore structure constructed with multilegs and a platform, more simplified method than the one used in the 1st or 2nd report was applied to the structure by replacing it with the new analytical model, evaluating its flexural rigidity and then by transforming the structure into the equivalent lumped mass method. The new model proposed in this study was the vertical cantilever beam, the lower end of which was fixed, and the upper end of which was loaded by the axial load and constrained not to rotate, even if it could be displaced horizontally by the small amount of displacement.
Furthermore, the validity of this model was examined by the model experiments carried out on three kinds of multi-leg-structures which had 8, 10 and 12 legs.
The main results obtained are as follows:(1) The values of natural frequency and displacement for each structure vibrating in water are independent of the direction of vibration within the ranges of the leg-intervals and the dimensions of legs used in this study.
(2) The natural frequency obtained by the proposed method, which utilizes the Theory (II) or Theory (IV) defined in this paper, coincides very well with the experimental frequency within the error range that is about 0.00-1.36%. The value of this range is a little lower than the value (0.07-3.57%) estimated by the Theory (2) or Theory (4) defined in the 2nd report, and so the proposed method in this study gives a little more precise natural frequency than the other methods.
(3) Furthermore, the method in this study gives the fairly well estimation with respect to the amplitude of the lateral vibration of the multi-leg-structures, since the error involved in the estimation is only about 9-14% until the fifth period of vibration.
(4) The value of the frequency or displacement estimated by the Theory (II) gives the same degree of the error range as one by the Theory (IV).
(5) Finally, it can be realized that the simple method proposed in this paper could be satisfactorily available for analyzing the lateral vibration of the practical off-shore structure with multi-legs.

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Leaching behavior of a chalcopyrite concentrate by Thiobacillus ferrooxidansstrain, isolated from an acid mine water, was considered on the basis of the results of batch shake flask experiments. Then, its leaching mechanism and rate controlling factors were also considered.
It was found that under the same pulp density, there was a linear relation between the initial specific surface area and the upper limit of copper concentration attainable with a high leaching rate (Fig. 3).
Leaching proceeded in two stages (Fig. 6-9). The first stage was characterized by a high growth rate, a high demand of hydrogen ion and a high leaching rate of copper. The second stage was characterized by a generation of hydrogen ion, a low leaching rate of copper and a low growth rate. It was observed that the second stage of leaching was followed by a leaching behavior similar to the first stage, then by another second stage behavior.
The leaching mechanism of the first stage is mainly indirect (Eq. 6 and Eq. 9), and the reactions proceed by depositing elemental sulphur on the mineral surface (Eq. 11-15) until reaching a particular thickness. In the second stage, the deposited elemental sulfur is dissolved by bacterial catalytic action and sulfuric acid is produced.
The main factor affecting the rate in the leaching of a chalcopyrite concentrate by Thiobacillus ferrooxidans is the oxidation of sulfide to sulfate. Accordingly, for improvement of the leaching rate, it is necessary to accelerate this oxidation reaction.

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A new-type of lead dioxide electrode was tried as an anode for electrowinning of zinc from sulfate bath in place of the conventional lead alloy electrode which contains about 1% of silver. The new-type electrode gave electrolytic zinc with a lower level of lead contamination, more effective removal of chlorine from electrolyte solution, higher current efficiency, and a higher anodic overpotential than the alloy electrode. Furthermore, the new-type electrode had a high resistance to corrosion and showed relatively low overpotential even at a high cu rrent density without any crust on it.
The use of the new-type electrode may somewhat increase the costs of zinc production compared to the present electrowinning process with an alloy electrode. However, it is believed that the new-type electrode may be more suitable for use in the zinc electrowinning process when the alloy electrode can not be used, e.g., electrowinning of pure zinc which is scarcely contaminated by lead, electrowinning of zinc from a bath with a large amount of chlorine, or electrowinning of zinc at a high current density.

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The scrap of used tantalum capacitor is now an important secondary resource of tantalum and the composition of those scraps is simply identical to Ta-Ta₂0₅-Mn0₂ ternary mixture (Ta is above 90%, Mn and oxygen content are a few percent, respectively). In this work, recovery of tantalum metal from tantalum capacitor scraps has been examined by plasma melting process and hydrogen plasma melting was available to obtain ductile pure tantalum (0 < 100, Mn < 20 mass ppm, Hv =90-100) with effective deoxidation and demanganese directly from those scraps.
Manganese was removed rapidly with vaporization of manganese from melt by Ar, H2 -Ar plasma melting and reduced to under 20 mass ppm. Also deoxidation proceeded by H2 -Ar plasma melting and oxygen content reduced to under 100 mass ppm. But oxygen was scarcely removed by Ar plasma. Since the deoxidation rate increased in proportional to the square root of hydrogen content of plasma gas, deoxidation is considered to be caused by dissociated and activated hydrogen atoms in hydrogen plasma. And the addition of carbon within equivalent of oxygen content in the scraps enhanced the deoxidation procedure.
Furthermore the other minor impurities such as nitrogen, iron, nickel in tantalum capacitor scraps were eliminated as much as possible by hydrogen plasma melting.

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The decomposition pressure of zinc sulphate in the absence or presence of ferric oxide or silica has been measured by e.m.f. method, using calcia stabilized zirconia solid electrolyte, and thermogravimetry in the temperature range 806 to 1088K.
The results obtained are as follows;1) In the absence of ferric oxide or silica, zinc sulphate decompose to form zinc oxide through basic zinc sulphate, with the increase of temperature. These decomposition pressure measured well agree with those of other investigators.
2) In the presence of ferric oxide, zinc sulphate directly decompose to form zinc ferrite, ZnFe₂0₄, without the formation of basic sulphate. The decomposition pressure and standard free energy change were obtained as follows;
log (p_SO3 /atm) =(12717 ± 106)/T+ 11.070 ± 0.18 (882 to 1015K)
log (p_SO3 /atm) =-(9499 ± 79)/T + 7.886 ± 0.13 (1015 to 1076K)
Δ°/cal =58180 + 480 (50.64 ± 0.83) T (882 to 1015K)
ΔG°/cal =43460 + 360 (36.08 ± 0.59) T (1015 to 1076K)
3) In the presence of silica, zinc sulphate directly decompose to form zinc silicate, Zn₂SiO₄, without the formation of basic zinc sulphate. The decomposition pressure and standard free energy change were obtained as follows;
log (p_SO3 /atm) =-(10832 ± 105)/T+ 9.088 ± 0.15 (903 to 1015K)
log (p_SO3 /atm) =-(8968 ± 92)/T+7.266 ± 0.13 (1015 to 1088K)
ΔG°/cal =49560 ± 480 -(41.58 ± 0.68) T (903 to 1015K)
ΔG°/cal =41030 ± 420-(33.24 ± 0.59) T (1015 to 1088K)

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The behaviour of selenium in anode during electrolysis was investigated in terms of the impurity level in anode, the concentration of dissolved oxygen and the condition of heat treatment of anode. The spherical and ellipsoidal Cu₂Se particles surrounded by films of Cu₂Se and Cu₂O mixture were found in the anode before electrolysis, regardless of the concentration of selenium and oxygen in the anode. These Cu₂Se particle did not dissolve, forming the anode slime during electrolysis.
The passivation was not observed at a current density of less than 2 A/dm², but occured at a current density of 3 A/dm². On the way of this passivation, part of the slime is decopperized and changes to compounds of Cu₂ -xSe (100 mV), Cu₃Se₂ (440 mV) and CuSe (740 mV), successively, according to the anode potential.
The heat treatment of anode makes Cu₂O particles in the Cu₂Se-Cu₂O mixture film coarsen and separate from the mixture. The slimes formed on the anode with longer-time heating treatment adhered to it strongly and thus, the passivation was accelerated.

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The extraction of nickel, cobalt and copper from manganese nodules was carried out by using ammonium carbonate solution containing ammonium sulfite. The manganese nodules which were dredged from the deep sea floors of the Central Pacific Basin were used grinding below 100 mesh. The leaching test was done under the following conditions; the range of ammonium carbonate concentration from 0 to 200 g/l, the range of ammonium sulfite concentration from 0 to 200 g/l, leaching temperature range from 25 to 80°C and the range of leaching time from 5 to 120 minutes. In the leaching using only ammonium carbonate solution, the extraction of metallic components was low. On the other hand, the addition of ammonium sulfite as the reducing agent to ammonium carbonate solution increased the extraction of nickel, cobalt and copper considerably. For instance, the extraction rates of the metallic components on leaching at 80 for 120 minutes in the mixed solution of 120 g/l (NH₄) ₂CO₃ and 50 g/l (NH₄) ₂S0₃ were 93.2% for Ni, 98.7% for Co, 97.2% for Cu, 0.65% for Mn and 1.2% for Fe, respectively. Concequently, nickel, cobalt and copper were selectively extracted from the manganese nodules with the mixed solution of ammonium carbonate and ammonium sulfite.

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