In this paper is described the results of analytical study on the. stress in a circular shaft lining caused by the earth pressure distribu ted uniformly or irregularly. By employing the results obtained, the stress distributions on the inner and the outer surfaces of shaft linings subjected to nine states of earth pressure are calculated.
The authors have presented a method to estimate the possible maximum stresses in a shaft lining for the purpose of contributing to the proper design of a shaft lining.

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In this paper, the term “dimensions of valve” means the valve weight and clearance between valve and valve seat. Two kinds of valve, which were same in size and made of duralmin (light) and steel (heavy), were used for this experiment under changing the valve clearance. In this study, following results were obtained.
In the case of the light valve, valve starts more quickly, shifting time is shorter, cushioning in the back room of the cylinder happens more quickly, and then, number of blows is more many and air consumption is fewer than the case of heavy valve. Consequently, on the whole, thermal efficiency is higher in the light valve.
The blow energy of piston and thermal efficiency become to lower when the clearance is too large. Then, it is considerd most suitable that the valve clearance would be selected so as to the air inlet area at the valve clearance is nearly equal to the area of air port opened to the cylinder.

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It is declaired by our documents already described up to date that any sorts of coal more pulverizedare generally capable to form a danger zone as to the outbursts of gas and coal, and therefore, the authors manufactured for trial a simple apparatus for assessing the in-situ strength of coal in dangerous seams.
This one, 40cm long and 1.5kg weighty, has a mechanism of spring to indicate the resistance of coal to the drive-in of a cone bit and is capable to be worked easily and rapidly by hand. The authors made experiments on the characteristics of resistance of plastic materials to the drive-in of cone bits, and on thismeasuring apparatus for accuracy and informating ability of the rate of pulverizations of coal in seams.
As a result of these studies both in laboratory and fields, this simple predicting apparatus manufactured for trial was recognized to be of use and found something to be desired in it's construction.

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In froth flotation if mineral particles attached on bubble surface are arranged in monolayer packing, . the particles more than that of their arrangement becomes closest packing can not be attached to definite bubble surface. Hence it is thinkable that this specific number of mineral particles corresponds to maximum bubble. load. In order to calculate the maximum bubble load the authors theoretically introduced the equation represe nting the numbers of closely packed small spheres on large spherical surface assuming that particles and bubble. respectively having spherical form.
By using the equation variations of numbers of closely packed mineral particles and of maximum bubble, loads of galena, chalcopyrite and coal against their particle sizes were calculated. These results were elucidated by Fig. 9, 10 and 12. From these relations the following facts were ascertained that the numbers of closely packed mineral particles are increased with the decrease of particle size, while the maximum bubble: loads remarkably diminish with the decrease of particle size. This is caused by the considerable weight re duction of mineral particle due to the decrease of particle size.
The above size dependency of maximum bubble load have an important meanings to solve the flotation, of fine mineral particles. Hitherto it have been considered that the less floatabilities of fine particles are dueto the change of their surface properties, however, even though their surfaces are unchanged as shown in Fig. 9, 10 and 12 since the weight of virtually floated minerals is remarkably diminished with the decrease of particle size, it should seem that as if finer particles substantially have weak floatabilities.
Concerning the maximum bubble load of coal flotation the approximation between calculated results. and Sun and Zimmerman's experimental values was ascertained. Moreover the relation between ibuoyancy and gravity of armored bubble was discussed.

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Flotation reactions at mercury surfaces were studied by the measurements of electrode potential and contact angle in mercury-electrolyte solution and mercury-xanthate solution systems. The results are summarized as follows:-
1) In a solution of NaCN, KCN, or Na₂S, the value of the mercury electrode potential and themagnitude of the contact angle on mercury are much affected decreasingly with increasing of the electrolyteconcentration. Conversely, in a solution of NaCI, or KCI, the increase in electrolyte concentration makes a, slight change of the electrode potential and gives no effect on the contact angle.
2) In the solution of xanthate, the value of the mercury electrode potential varies its sign from positive to negative and at concentrations less than 100mg/l, the potential-concentration curve is similar to the-Freundl ich's adsortion isotherm and at concentrations more than about 100mg/l, it is like to the line according; to the Nernst equation, the expression as to the potential of an electrode. From the above results the relation between the adsorption and the potential is obtained.
3) In the mercury-xanthate solution system the electrode potential and the contact angle are affected by, pH value at xanthate concentrations less than about 30mg/l, while at the concentrations more than about 30mg/l being scarecely affected by pH value. Above these results show the relation between xanthate concentration and pH value on the reaction of xanthate for the mercury. Perhaps, these results may be recognized, as a rule, for various sulphide minerals. Accordingly, it may be said that the depressant action by the pH value, in sulpide flotation using xanthate depends upon the xanthate concentration and is effective only in the much. dilute xanthate concentration.
4) From the critical points where the mercury electrode potential in the xanthate solution starts, being governed by the pH value, the magnitude of contact angle on mercury for xanthate solution decreases with increasing the pH value. Along this critical curve, the following relation between xanthate ion concent ration and pH value is derived;
d [X-] n/4 [pH] =d [X^-] n/d [pH-] =d [x^-] n/dlog [OH^-] =constant.

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This investigation was undertaken to observe the reducing speed between Fe and Ni, and condition of Ni preferential reduction. We have experimented on reduction of nickel ores by a rotary kiln and measured composition of materials, atomosphere, and its temperature at several points in the kiln.
(Fe Ni Mg) Silicate was reduced slowly and its reduction was done just: before melting point, but neither M. Fe nor M. Ni was produced below about 1, 000°C.
Assuming the ratio of M. Fe to M. Ni between 1, 100°C. and 1, 400°C., we obtained as follows
k_Fe-Ni=0.0324e^0.00295T
therefore we have been able to conjecture condition of Ni preferential reduction in the kiln.

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One of the applications of the fluidized bed chlorination process is described. Using high titanium slag, the preferential chlorination of impurities (especially FeO) and the chlorination of major constituent-TiO₂ were studied.
In the preferential chlorination, to prevent the bed from sintering, the addition of charcoal powder was effective. As reducing agent, charcoal producer gas was recommended, and optimum conditions were as follows; temperature 750-850°C, particle size 65-200mesh, Cl₂ concentration 10%, u=, 0.2, mean residence time 30miuntes, and under these conditions, the Fe removal was over 90% and that of the other impurities. was about 70%.
After this treatment, the slag could be chlorinated in fluidized bed with CO-Cl₂ gas mixture at 1, 000°C or hlgher. But in these conditions, the construction materials were damaged quickly, so we studied the lower temperature chlorination using solid C as reductant. In this method, samples were prepared from slag. and pretreated slag, finely ground, mixed with charcoal powder, agglomerated with syrup binder and sized 35-150mesh.
These two samples were chlorinated easily in fluidized bed. The optimum conditions were temperature-650-750°C Cl₂ concentration 50%, (diluted with CO₂ or N₂), and u=0.1, and under these conditions, the reactions was concluded in 15 minutes with 80% or better chlorination ratios.

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