[in Japanese]

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Reactions between some refractories and copper matte-fayalite slag melts were directly observed at 1473 K by high temperature X-ray radiophotograph technique for the purpose of testing the refractories for protecting tube to Cu-slag with molten copper or matte.
Local corrosion was clearly observed at the surface of slag and the interface between copper matte and slag in high grade alumina crucible. The mechanism of local corrosion was discussed from the viewpoint of viogrous movement of slag film at the interface due to the Marangoni effect. The results of measuring the surface tensions of Cu-slag and the interfacial tensions of copper matte-slag systems confirmed the mechanism by the Marangoni effect.
High grade magnesia refractory was found to be stronger for the corrosion by copper matte-slag melts. Visible local corrosion of magnesia was hardly observed in the melts, especially in the copper-slag melt even after 24 hours. A cermet consisting of alumina and chromium showed a stronger ability of protection than the magnesia refractory from attack of copper matte-slag melts.
Since violent generation of gas was found in the oxidation reactions of silicon nitride (Si₃N₄) and silicon carbide (SC) with Cu slag, both non-oxide type ceramics were considered to be insufficient to protect tube from Cu slag.

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The concentration of oxygen in liquid copper has been investigated by the solid-electrolyte galvanic cell Pt|Ni-NiO|ZrO₂+11mol% CaO|O(in Cu liq.) |Mo at 1473 K under high vacuum for the concentration range of oxygen down to less than 1 ppm. Alumina and graphite, are used as crucibles for melting of copper. CuO addition into liquid copper and subsequent hydrogen reduction of it are carried out in alumina crucible. Oxygen concentrations determined by analysis and calculation were compared with each other. Results are as follows:
(1) Oxycell probe used in this work generates stable e.m.f. under high vacuum as well as under atomospheric pressure.
(2) Calculated values from e.m.f. values show precise oxygen concentration in the liquid copper down to about 1 ppm.
(3) The oxygen concentration of less than 1 ppm can be measured in the melt with stirring.

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In this research, dissolution of the synthesized copper ferrite in aqueous sulphuric acid was investigated where temperatures were varied from 323 K to 343 K, sulphuric acid concentration from 1 M to 3 M and experiment was done using a rotating disc system Effects of Fe³⁺, Fe²⁺ and SO₄^2-were also studied. The experimental results have shown that, in the initial period of dissolution, rate of copper was greater than one of iron, leaving Fe₂0₃layer outside, and therefore, non stoichiometric dissolution of copper and iron. After long time of dissolution period, the stoichiometric dissolution of copper and iron was shown to be attained as described as follows: CuFe₂O₄+8H⁺=Cu⁺+2Fe³⁺+4H₂O
Increases of temperature and acid concentration both lead to increase in dissolution rate of copper ferrite. However, increases in any of Fe³⁺, Fe²⁺ or SO₄^2-decreased the dissolution rate, that has been discussed due to the decrease of hydrogen ion activity.

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Dust suspension is a common phenomenon in and around mine sites, factories, construction areas, etc.
This research deals with the continuous measurement of the concentration of suspended particles by utilizing the light wave attenuation theory.
This consists of measuring and interpreting the attenuation of LASER beams propagated through an atmospheric space.
In previous works, the authors had confirmed the relationship between the degree of attenuation of He-Ne LASER (α) due to airborne dust and dust concentration (W).
And this relationship was examined by the numerical computation of the light wave attenuation theory.
Then, the numerical values were compared with the experimental results obtained by the measurements of α and W.
As a result, it has been confirmed that αis proportional to W for various kinds of airbone dust, and that the theoretical values of a are coincide with the experimental values.
Lately, based on the light wave attenuation theory, an in-situ measurement system was designed.
In-situ measurement experiments were performed and the results are included in this report.
Measurement results in the AOMORI-HAKODATE tunnel are shown for illustration.
Lastly, the practicability of this method was considered by comparing the capability with other instruments.

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