Quantitative spectrochemical analyses have been carried out in this study on common ore minerals such as sphalerite, chalcopyrite, pyrite, and galena collected from many mines in the Inner Northeast Japan. They were separated purified to study geochemical behaviors of minor elements in these minerals and their relation with ore deposits.
Many arguments have been raised as to what extent the contents of minor elements in these sulfide minerals from ore deposits were controlled by the conditions of formation of deposits.
366 sphalerites, 579 chalcopyrites, 432 pyrites and 146 galenas were analysed.The result was examined statistically to show the characteristics of minor elements distributing in sulfide minerals.
The distribution of minor elements in sulfide minerals in the ore deposits in the province is statistically characterized by extremely low contents of Ni, Co, high content of Bi, and show different distributions according to either massive (Kuroko and Kuroko type stockwork deposit) or vein type deposits.
Generally speaking, in xenothermal veins such as Ashio and pizumi mines, Bi, In, Sn and Co show high contents, in epithermal veins the contents of these elements decrease, and in massive. deposits they show extremely low contents. As, Sb, Ge, Ga, TI, Ag and Mo which are rarely detected in vein deposits are, however, concentrated in massive deposits, especially in Kuroko deposits. This fact is considered to suggest a peculiarity of the forming condition of the Kuroko deposits. The origin of minor elements in massive deposits (Kuroko), is discussed.
These conclusions clearly show that the distribution of minor elements in sulfide minerals has a close connection with the condition of ore formation.

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The stress state in virgin ground is, in general, three-dimensional. In order to clarify strictly the earth pressure phenomena, it is necessary, therefore, to analyze the stresses around underground openings as a problem of three-dimensional stresses. Accordingly, the authors have analyzed theoretically the stresses around a shaft, vertical or inclined, or a horizontal drift, circular in cross section, excavated in ground in three-dimentional stress states, and obtained a general solution.
From this solution it is shown that the stresses around those openings are statically indeterminate. To show the influence of the inclination of the principal stresses in virgin ground upon the stresses around a circular opening, the stress concentrations have been illustrated for several stress states in undisturbed ground.

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An important process in underground gasification of coal is reduction from CO₂ gas to CO. In process of underground gasification of coal, the heat loss to the peripheral rocks is verg great. For that reason, the reducting reaction of CO₂ gas can not occur sufficiently. The author took β(=CO/CO+CO₂) as an index of reduction, and found the relations between β and many other factors.
The author concluded in our laboratory experiments as follows:
(1) It is desirable to get β=1.0 in process of gasification ideally. But it's notpossible in actnall underground gasification, for the heat loss is very great.
(2) In our experiments, when we used the oxygen gas, which quantity is 4l/min, we got the temperature 1300-1400°C at burning zone. In these case, the value of β showed only 0.4. Therefore, we can suppose, the reducing temperature is not so high and about 650°C. This shows how the heat loss is great.
(3) In order to increase the value of β, it's necessary to feed much more quantity of oxygen gas in channel.
(4) When β=0.4, we got the gas, which calorific value was about 1600kcal/Nm³.
(5) On the one side, it's desirable to feed a lot of oxygen gas in channel, but the other side, that is not desirable for the ecconomics of underground gasification of coal.

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Experiments have been made in the laboratory, in a ventilated small model rodyway, to explore the factors controlling the proportion of sprayed liquid converted into foam, the filling of the model roadway with foam and the back-pressure exerted on the ventilation by the net and foam-plug. The following conclusions are reached.
1) It is shown by experiments that there is an upper airspeed limit for adequate filling of the model roadway with foam, the limit being about 50m/min for one net design.
2) The degree of filling a model roadway with foam has been characterized by the “Leak ratio”.
3) The back-pressure of the net is comprised of two components. The first component (h₁) is independent of airspeed. The second component (h₂) is due to the aerodynamic resistance of the net and increases linearly with airspeed.
4) If the air speed through the roadway is constant, the degree of filling a roadway with foam is effected by the characteristces of the foam agents solusion.

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The formation of zinc-ferrite, from a stoichiometric mixture of ferric oxide and zinc oxide, and the dissolution of zinc-ferrite in dilute sulfuric acid have been investigated, with special reference to the ignition temperature of ferric oxide.
The ferric oxide, which was ignited at higher temperature, showed the lower reactivity with zinc oxide, and the rate of formation of ferrite decreased with the increase in ignition temperature. The effect of ignition temperature was more apparent when the ferrite was formed at low temperature. The activation energies of formation of ferrite increased from 39 to 62 kcal/mol gradually, according to the increase in ignition temperature.
The rate of dissolution of zinc-ferrite in sulfuric acid was lowered by raising the ignition temperature of ferric oxide and the formation temperature of zinc-ferrite.The dissolution rate was proportional to the surface area of ferrie particles and the activation energies of dissolution were 15-18kcal/mol in calculation.

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The reacting materials in the thermal production of magnesium-dolomite, ferrosilicon and reduction residue-were investigated by X-ray diffraction method. The following results were obtained.
1) The thermal decomposition of dolomite takes place according to the following formula.
CaMg (CO₃) ₂→CaCO₃+MgCO₃→CaCO₃+MgO+CO₂↑CaO+MgO+CO₂↑
2) The reduction of MgO is influenced by the growth of MgO and CaO crystals caused by the excess heating of dolomite
3) The reduction of MgO is influenced by the growth of MgO and CaO crystals caused by the excess heating of dolomite
Si 98% and 85%...Si only
Si 75%...Si and FeSi₂
Si 45%...FeSi₂ and FeSi
Si 25%...FeSi only
4) The reduction residue consists of 2CaO·SiO₂, CaO and MgO. Therefore, the reacting formula is as follows.
2CaO+2MgO+Si (Fe) =2CaO·SiO₂+2Mg↑+(Fe)

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In this article are described and reviewed the following items concerning the subject.
1) Difficulties on mineral separation of complex sulphide ores are caused by the difficulty in achieving mutual isolation of their component minerals andresembrance of physical and surface chemical properties of each minerals.
2) Fundamental concepts and several experimental results on activation and depression of mineralsparticularly sphalerite-in flotation.
3) Technical review on selective flotation of complex sulphide ores.
4) Some examples of metallurgical processes on complex sulphide ores.

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A Preliminary Note on Carbon Dioxide in Flotationと題してノルウエーTrondheimの工科大学選鉱学教授M. Mortenson氏から“Det Kongelige Norske Videnskabers Selskabs Forhandlinger Bind 33 1960 Nr.12”所載の報文別刷が訳者に寄贈された。短い報文ではあるが実操業への応用面などで興味ある報文と考えられ, これを飜訳して日本に紹介したい旨依頼したところ, 同教授から喜んで許可するとの承諾を受けたので, 全文を日本語に訳し紹介する次第である。

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