The work studied on characteristics and processing of deep-sea manganese nodules by members of the Research Committee for Processing Techniques of Manganese Nodules is summarized.
The Committee established in August, 1982 has been in activity for these three years, and studied on processing techniques for extracting valuable metal components such as Cu, Ni, Co and Mn from the nodules, aiming specifically at comprehensive discussions of the processing, exchange of technical information, promotion and enlightenment of studies at universities or research organizations in Japan.
The paper consists of two parts: Part I introduces research activities, showing position and background in the processing of the nodules, significance and characteristics of the individual research, and Part II summarizes the results.
This paper follows after two papers entitled “Processing of Manganese Nodules, No.1” and No.2; which were already published by the Mining and Metallurgical Institute of Japan, therefore all these papers may lead to better understanding of research activities in the field of nodule processing in Japan.

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The purpose of this report is to discuss the diametral displacement behaviors by impermeable pressurization of borehole using flat jacks for in-situ stress measurement. Some laboratory pressurizing tests were conducted for various stress condition in Inada granite and Kofu andesite. Diametral displacement behaviors under confining pressure up to 40 kgf/cm² were recognized to be depended on rock anisotropy. The results of impermeable pressurizing tests show that the breakdown behavior is not clear in the relationship between borehole pressure and diametral displacement because of the smaller fracture created.
The another purpose of this report is to discuss the method of stress analysis on the basis of the experimental studies on the mechanism of hydraulic fracturing (1st-3rd reports). The author suggests the method of stress determination in consideration of the orientation dependence of hydro-fracture in anisotropic rocks and the influence of permeation.

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In recent years, span of bridges has become longer and machine generating vibration has become larger as in Honshu-Shikoku bridge and dynamos in power station. Moreover, so-called soft rock mass must frequently be selected as foundations of such as bridges and power stations. In these cases, rock mass is subjected to severe cyclic loading in comparison to its strength.F or the safe design of these rock foundations, it is prerequisite to clarify the cyclic fatigue charactericstics of unsaturated rocks including soft rocks under confining pressure.
In this work, cyclic fatigue tests using 1 Hz sinusoidal wave of load were conducted under confining pressure for two kinds of unsaturated rocks; Kimachi sandstone and Hirono sandy mudstone. Their uniaxial compressive strengths are 420 and 40kg/cm², respectively.
From these tests, following results were mainly obtained.
(1) Endurance limit was found only for sandstone, but not for sandy mudstone within the maximum cycle of 10⁶ in this study as shown in Fig. 3. Endurance limit of sandstone increases with confining pressure.
(2) Number of cycles to failure increases with confining pressure for both rocks. However, for sandy mudstone, rate of increase in number of cycles to failure with confining pressure decreases with confining pressure.
(3) Main failure mechanism is so different between two rocks in respect to volumetric strain in cyclic fatigue process. Namely, fatigue process proceeds with dilatancy in sandstone, but with contractancy in sandy mudstone especially under larger confining pressure as shown in Figs. 6 and 8. This difference could explain the facts described in (1) and (2). As confining pressure suppresses dilatancy in sandstone, endurance limit of sandstone increases with confining pressure. On the other hand, number of cycles to failure of sandy mudstone does not increase with confining pressure as compared to sandstone because contractancy causes excess pore pressure which lowers the effective confining pressure.

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Mechanical performance of rock drills or breakers of a percussion type should be evaluated for percussion energy of a piston. Therefore, it is important to measure the displacement of the piston. As the force of a percussion is large and the length of the piston stroke is long, the measurement of the displacement is difficult by use of convension meters.
A new displacement meter developed for the performance test of a hydraulic breaker is described in this paper. The meter consists of a photoelectric sensor and a lamp. A calibration curve between the output signal to the displacement based on the characteristic of the phototransistor can be obtained. By use of the displacement meter we can measure the displacement of the piston without the influence of vibration and percussions. Performance test of the actual hydraulic breaker was performed with th displacement meter and the availability of the meter is shown in the test. Moreover, the results obtained in the test of the hydraulic breaker are illustrated in graphs.

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Acid water containing considerable amounts of zinc and sulfate ions is effluented from some process in zinc hydrometalllurgy. Such water is neutralized with slaked lime and the precipitates formed, which mainly consist of zinc hydroxide a dgypsum, are dumped into dam. In order to utilize these precipitates selective flotation of zinc hydroxide from gypsum has been investigated.
As a fundamental study, floatability of zinc hydroxide was examined using dodecylammonium acetate (DAA) or sodium dodecylsulfate (SDS) as a collector. It was found that zinc hydroxide was relatively floatable with DAA or SDS at wide pH range in alkaline medium. Then the effects of soluble starch and sodium silicate on the floatability of zinc hydroxide and gypsum were examined. It was shown that sodium silicate tended to depress zinc hydroxide effectively when SDS was used as a collector. Then, selective flotation was made for the mixture of zinc hydroxide and gypsum, and it was shown that satisfactory separation of the mixture could be achieved only when SDS was used as a collector and sodium silicate as a depressant for zinc hydroxide.
Synthetic mine water containing 1000mg/1 of zinc ions, 7328mg/1 of sulfate ions and 603mg/I of calcium ions was neutralized with slaked lime until pH 8.5. The flotation tests were conducted for the precipitates thus formed. It was touiid that zinc hydroxide was effectively separated from gypsum with SDS collector when sodium silicate was aaaea in Dotn procelss of neutralization and flotation, and that some 90% of gypsum was recovered in the froth and 87% of zinc hydroxide in te tailing solution.

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An experimental study was carried out to examine the grindability of a wet ball mill grinding. Samples used were quartz glass, quartz, feldspar, marble and talc. The feed size of sample was 14-20mesh (0.119-0.084cm).
The measurement of size distribution and specific surface area, the classification by electroformed sieve of opening size 5μm, and the settling test were conducted respectively to compare the grindability of wet ball mill grinding with the dry grinding.
The experimental results are summarized as follows:
1) A dry grinding was available for primary grinding.
2) A wet grinding was available for fine grinding and it was confirmed to be more effective under hydrophilic condition than in hydrophobic.
3) Wear of balls in wet grinding was larger than dry in grinding.

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Production of fine metal and metal oxide powders through the liquid phase chemical reaction which applied solvent extraction was investigated in order to develop a new production method of fine powders. Crystallization-stripping of C_oCO₃from C_o-Versatic Acid 10 extracts was carried out under CO₂pressure by using water or sodium hydrogen carbonate solution as a stripping agent. In addition, the powder characteristics of crystallized products roasted in air or hydrogen gas were measured.
C_o-Versatic Acid 10 extracts were stripped into the aqueous solution and crystallized fairly easily under CO₂pressure of 3-20Kg/cm². It was recognized that crystallization-stripping of C_oCO₃was dependent upon CO₂pressure, extractant concentration, C_oconcentration in organic phase and stripping agent concentration, and that the reaction was accelerated with an increase in operation temperatures. Crystallized products caused thermal decomposition over the temperature range from 200°to 300°Cto form metal oxide. The particle size of crystallized products and metal oxide was less than several micrometers.
The application of this process makes it possible to produce high purity fine powders under a closed circuit system and at a low cost.

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