The Uchinotai are deposits were discovered in 1959 by drilling prospecting. They are typical “Kuroko” deposits and cosist of Eastern and Western Deposit.
The development began in January, 1960 and the mining operation was started in July, 1962.
Since the begining of development, a systematic and detailed underground geological survey was carried out and it has been made clear the features of geological and mineralogical occurrence, mainly the evidence of volcanic activity.
These geological and mineralogical informations are very useful in the future prospecting and also the operation planning for more stabilized form.

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The present report is a continuation of a previous paper on the mechanical behaviours of rocks under various loading-rates, which ranged from 1.0×10^-1kg/cm²/sec to 8.0×10⁷kg/cm² isec.
The main results obtained in this investigation have been summarized as follows.
The impulse, which gives the energy of the rock breakage, decreases as the strain-rate increases, and this relation is approximately expressed by
I=αενβ
where
I: impulse (kg·sec/cm²)
εν: strain-rate (cm/cm/sec)
α, β: constants.
Moreover it is shown that the value of the constant β in the above equation is approximately -1, and there may be some correlation between the constant a and the Protodyakonov's strength coefficient f₄ obtained by the crushing method.
Further, the compliance of rocks decreases with the increase of the strain-rate, and there may be some correlation between the decrement of the compliance and the porosity of rocks.

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After the World War II, the Mitsubishi Mining Company has introduced “Bergschadenkunde” from Germany to make clear the behavior of surface subsidence caused by underground mining.
This study has been done in some coal mines in Kyushu belonging to the company.
As a result of analyzing surveies, followings were made clear.
1) The critical angle (Genkaikaku) near the corner of mined area is about ten degree larger than that of the center of dipend of mined area.
2) Subsidence ratio (Chinkaritsu) changes in accordance with influence ratio.(Eikyokeisu)
3) The time which needs to be stabilized the subsidence differs in accordance withmining depth. And in the case of our long wall mining, it is about 24 months in maximum.

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One of the most important factors in testing the performances of flame-proof enclosures is a pressure piling phenomenon.
This paper describes some experimental results pertinent to the pressure piling phenomena. The significant results obtained are as follows
(1) With the gas concentration of approximately 10%, the maximum piling pressure is recorded.(2) When the gas concentration as low as 6.5%, the piling pressure rises up to such a high value that can not be reached in enclosures with no partition.(3) In many caces, both the piling pressure and the pre-pressure trend to increase with the distance between the ignition position and the partition plate.(4) The piling pressure rises as the opening diameter decreases. The maximum pressure in chamber V1 is in contrast with the piling pressure.(5) The piling pressure may be influenced by the diameter ratio of the opening to the enclosure.(6) When the flame-proof enclosure is divided into three or more compartments by partition plate, the accumulated pressure piling phenomena of higher explosion pressure can be observed.

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The depression of galena by chromate ion was investigated by means of the measurements of the amounts of adsorption, electron diffractions and flotation tests.
The results were summarized as follows;
The depression of galena by chromate ion occured in both alkaline and neutral or weak acid solutions.
In alkaline solution, the clean galena-was hardly depressed by the addition of the chromate ion, but the oxidized galena was depressed remarkably. Chromate ion reacted with lead sulfate, which was a oxidation product of galena, to deposit lead chromate on the surface. Chromate ion did not prevent the adsorption of xanthate ion bounded to galena surface. Accordingly, the depression of chromate ion against galena in alkaline solution might be caused not by the prevention of xanthate adsorption, but by the deposition of hydrophillic lead chromate on galena surface.
In neutral or weak acid solution, galena was depressed remarkably by the chromate ion irrespective of the oxidation state of galena surface. In this case, lead sulfate and chromic oxide were formed on the galena surface by the oxidizing action of the chromate ion, while xanthate reacted with lead sulfate to precipitate lead xanthate On galena surface. From the fact that heavily oxidized galena easily floated with xanthate in neutral solution, it was concluded that the depressing action of chromate ion in neutral or weak acid solution was closely related to the formation of hydrophillic chromic oxide on galena surface.

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In mine water, a small amount of cadmium ion is sometimes contained together with appreciable amounts of ferrous and zinc ion.
The removal of cadmium ion from mine water has been studied by using xanthates as the selective precipitant.
The solubility product of cadmium xanthate reduces with increasing the chain length of an alkyl group. It is found that the amount of methyl, ethyl, butyl and amyl xanthate necessary for precipitating 90% of cadmiumion is about 120, 10, 1.5 and 1 equivalent to cadmium ion involved in the solution, in the case of cadmiumion concentration of solution is 1mg/l.
The formation of the precipitate of cadmium xanthate depends very much on the condition of agitation of the solution in a Denver-type flotator used as reaction cell and the precipitate is effectively formed by vigorous agitation. Owing to the strong hydrophobic property of cadmium xanthate, it is possible to remove the precipitate of cadmium xanthate from the solution by the flotation technique. The romoval of cadmium as cadmium xanthate from the solution is prevented to some extent by the coexistence of zinc and ferrous ions.
When ferric ion is contained in mine water, it is necessary to remove the ferric ion before xanthation by leading it into ferric hydroxide with the addition of calcium carbonate, because xanthate ion is oxidized by ferricion.
It is possible to reduce cadmium ion concentration below 0.1mg/l from an artificial mine water containing 1mg/l of cadmium, 100mg/l of zinc and 500mg/l of ferrous ion, by the addition of 2-3 equivalent of butyl and amyl xanthate, or 5-6 equivalent of propyl xanthate to cadmium ion involved.
This result is proved by the actual mine water, too.

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We tried to shape and bake an electrode consisted of intimate mixture of titaniferous slag, pitch coke and pitch and to apply it to 20 amp. cell for extraction of magnesium metal, containing fused mixture of magnesium chloride, sodium chloride and fluorite.
The results obtained are summarized as follows.
1) Such an electrode showed high electric conductivity and mechanical strength enough to utilize as an anode instead of graphite anode in our experiment.
2) During the electrolysis, free chloride was scarcely detected in the gas collected from the anode room and titanium tetra-chloride was condensed in the water-cooled glass condenser, while magnesium metal was formed at the iron cathode. These facts show that titanium tetra-chloride formed by reaction of free chlorine with anode constituents is insufficiently dissolved into the bath.
3) The cathode current efficiency was lower than that in I. G. cell and the yield of titanium tetrachloride did not reach 60% of theoretical value. It may be due to various kinds of impurities, which come from falling of a part of anode constituents and dissolution of chlorides generated by chlorination of various oxides in slag into the bath. Therefore it will be necessary to find out suitable means to lessen harmful influences of these impurities on the electrolytic operation.
4) It will be possible to combine such an electrolytic extraction process of magnesium with titanium extraction metallurgy.

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