In this paper, the author desires to make brief descriptions regarding the general aspect of the resources in the Netherland East Indies, especially those minerals such as Nickel, Iron, Tin and Aluminium having close connection with the industrial development of this country and intends to, -
(1) Correct the general cognition on the actual situation of these resources to be utilized for the future expansion of industrial enterprises of Japan, and
(2) Provide all data and informations collected from his investigations into the actual sites particularly on low grade ores existing in abundance and recommend the use of these ores to the benefit of those interested playing important part for the rapid advance of the economic structure and production of this country.

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With the rapid progress and wide spread of flotation process, the proportion occupied by flotation concentrate among are and concentrate carried into copper smelters has much increased. Flotation concentrate, its size being generally under 200 mesh is very difficult to sinter by blast roasting process which is the general process of treating fines in Japanese Copper Smelters.
The writer and his comrades investigated about the briquetting process and found to get strong briquette by curing with 8.5 kecm² pressure saturated steam for 8 hours, after briquetted with 6% slaked lime as the binder, and also found the strength of the briquette is about doubled by reheating in the current of flue gas of boiler for 1.5 hours. Several properties of the briquette at high temperature are also investigated and proved to resist high temperature till melting, unless the briquette contains more than 20% of sulphur as pyrite or less than 20% of silica. Thus the new briquetting factory of 10, 000 ton capacity per month was elected and has successfully been operated since 1939 at Hitachi Mine.

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By a standard method which is proposed by the auther, the frothing characteristics of 46 liquid flotation reagents on the market are studied. The frothing characteristics are determined by the change of the height of the bubble column from its standard state in the standard flotation test tube of all glass. It is experimented; (1) with the liquid reagent only, (2) with one of the xanthates and the liquid reagent, (3) with one of the xanthates, the liquid reagent and pure galena (-100 mesh).

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