The oxide minerals belonging to FeO-Fe₂O₃-TiO₂ system are studied by means of reflection microscope and electron probe microanalyzer. The studied samples are placer iron ores, iron are minerals in gabbro and iron ores from some pyrometasomatic deposits. Iron, titanium, vanadium, manganesein the iron are minerals are analyzed quantitatively by electron probe microanalyzer. Iron placer in the Ariake Bay (Western Japan) derived from the decomposition of andesites and their pyroclastics is mainly composed of titaniferous magnetite, magnetite, titaniferous hematite and ilmenite. Exsolution textures of magnetite (titaniferous magnetite) ilmenite and of magnetite-hematite (titaniferous hematite) are recognized. It is noticeable that in the above exsolution texture of magnetite-hematite the titanium is detected in hematite, and not in magnetite. Refering the results of analyses of titanium in magnetite and hematite to the phase diagrams, it is inferred that these minerals would be formed under the unequlibrium condition of rapid cooling. This interpretation may be verified by the fact that these minerals were derived from the decomposition of andesites and their pyroclastics.
A little or no titanium and vanadium are detected in magnetite or hematite genetically related to granitic rocks.

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The limestone resources in Akiyoshi district are biggest in Japan, and the quality of limestones is very high. We are now exploitating the biggest mine (300, 000t per month) in Japon. The principalproblem, therefore, is how to transport the limestones from mine to port economically. According to our study, the continuous transportation by conveyors is adopted. The total length of these comreyers is 16.5kms andwirll be a record in the world.

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In this paper the auther analysed the relation between rate of combustion zone movement and distance from the center of borehole.
The increase of distance from the center of borehole brings to the decrease of rate of combustion zone movement very rapidly, that is to say, the combustible zone around borehole is restricted. The author examined the suitable methods-increase of blast quantity and blast of oxygen gas-to enlarge the combustion zone in gasification.
In accordance with results obtained, the author proposed one nuderground gasification system considered to be suitable in Japan.

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The flotation characteristics of artificial goethite were investigated with sodium dodecyl benzen sulfonate (S. D. B. S.) or sodium oleate and then the flotation test has been made on a mixture of artificial goethite and kaolinite.
In the flotation of artificial goethite using S. D. B. S., a high floatability is gained in the acidic or neutral region, but this anionic collector is not effective in the alkaline region. Since the isoelectric point of artificial goethite is approximately at pH 6.4, the surface of the mineral is positively charged at pH values lower than 6.4 and negatively charged at higher pH values. Therefore, it may be considered that artificial goethite is floated with the aerophilic film formed by the electrostatic adsorption of dodecyl benzen sulfonate ion on the surface of the mineral.
On the other hand, in the flotation using sodium oleate, despite of anionic collector, artificial goethite shows a, high floatability in the alkaline region where the surface of. the mineral is negatively charged. Its floatability, however, is diminished in the acidic region, where the concentration of oleate ion is decreased by hydrolysis of sodium oleate.
A high selectivity can not be attained using S. D. B. S. in the flotation of goethite from a mixture of artificial goethite and kaolinite. It may be mainly ascribed to the so-called slime coating.
Optimum flotation of goethite from the mixture above remarked using sodium oleate occurs in the weak alkaline, region where the slime coating is almost inhibited.
Furthermore, according to the infra-red spectroscopic observation or the settling test in the organic solvent, oleate ion may be adsorbed chemically on the surface of artificial goethite.

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Nb₂O₅ and Ta₂O₅ are both hydrated precipitates from aqueous solutions. When heated at various temperatures, however, they liberate combined water and become crystalline. Their X-ray powder diffraction data were investigated, which indicated the existence of three modifications for Nb₂O₅, as follows: L formbelow 780°C L+M form from 780°C to 980°C M formfrom 980°C to 1150°C M+H from from 1150°C to 1300°C H formabove 1300°C
These transformations are function of temperature and time. There are two modifications for Ta₂0₅. The structure below 1200°C is isomorphous, coinciding with the low temperature modification (L-form) of Nb₂0₅. Above 1200°C it is transformed slowly into the high temperature form.
In Nb₂0₅-Ta₂0₅ system, solid solution is formed, whose ranges were shown in the diagram.

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Some questionable problems on the chloride volatilization process of pyrite cinder were mainly discussed in terms of thermodynomic properties of the redctions and several series of experiment were also carried out in order to clarify these problems. Calcium chloride was selected as the chloridizing reagent, because the pellets obtained by this process are commonly used in the iron making blast furnace. The results obtained can be summarized as follows.
(1) To remove the metal impurities from pyrite cinder as much as possible, the sample should be rapidly heated, especially in the temperature range from 600 to 1000°C.(2) Decreasing in elimination efficiency by slow heating might mainly be due to the decomposition of calcium chloride at low temperature by the sulfur coexisted in the pyrite cinder.(3) The pyrite cinder containing comparatively low sulfur and arsenic is more suitable for this process as the raw material.(4) The existence of moisture and sulfur dioxide in the furnace gas is extremely harmful for the elimination of impurities.(5) The best results concerning the elimination of impurities were obtained at the heating temperature of 1100°C.(6) In order to obtain the pellets having enough mechanical strength and to eliminate the sulfur coexisted, the pellets are desirable to heat at about 1200°C.

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