As early as 1918 the preparation of Electrolytic Manganese Dioxide (EMD), by electrolysing a manganese sulphate solution, was reported. However, a few decades passed before production on an industrial scale was initiated.
The Takehara Plant of Mitsui Mining & Smelting Co. Ltd., (MMS), was the first to produce EMD in Japan on the scale of 5 ton/month in 1948. Since that time production has grown rapidly, particularly in the last decade. The Takehara Plant has been one of the largest producers of high quality EMD with top level technology.
In March, 1973, after many years of study and investigation, MMS decided to build a new overseas plant to meet with increasing demand at the site in Little Island, 5 miles south-east of Cork city and port. A basic agreement with the Industrial Development Authority of Ireland was signed.
The construction of the site started in February, 1974, and was completed in May, 1976. Plant operation began immediately and has successfully continued to date.
Inflation started by the oil crisis in 1973 caused a substantial increase of initial investment and delay of construction. However, due to the efforts of everyone concerned in the construction, the effects were kept at the minimum.
This is the first electrolysis plant to be built and operated in Ireland.
Outline of the Plant: 1. Products: EMD, called MITSUI DENMAN (raw material for Dry Batteries).
2. Capacity: 12, 000t per annum approximately 13% equivalent of world production.
3. Material Ore: Rhodochrosite imported from Ghana, Africa (Mn 30%).
4. Ore Consumption: 36, 000t per annum.

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Kosaka smelter, located at Akita prefecture in Japan, has treated the copper concentrates which come from “Black ore” mines with the flash smelting furnace since 1967.
The copper concentrates contain various impurities such as lead, zinc, arsenic, antimony, bismuth and cadmium which are concentrated in the dusts of flash smelting system.
These impurities had been recycled to the system and caused some problems on the practical operation, the quality of final products and the environmental control.
In 1975, new hydrometallurgical dust treatment plant started up its operation and made it possible to solve these problems and to increase profit by recovering valuable metals from the dusts and the zinc residues which were stored at the smelter.
The basic steps of this hydrometallurgical process are as follows:
1) Leaching of the dusts by waste sulfuric acid from acid plant and next by ferric solution which is prepared by hot acid leaching of zinc residues.
2) Filtration and drying of lead sulfate which contains bismuth, antimony and precious metals followed by the lead smelting with one short rotary furnace.
3) Copper precipitation by hydrogen sulfide gas and iron powder.
4) Coprecipitation of arsenic with iron as ferric arsenate.
5) Zinc and cadmium precipitation by ammonia and hydrogen sulfide gas, respectively.

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Blast noise is now under public discussion as one of the most troublesome problem. For reducing of a blast noise, it is necessary to make the emissive mechanism clear. Then, in this paper, the emissive mechanism is discussed. The results obtained are itemized below. We conclude the blast noise caused by a quarry blasting is ascribed to a refraction wave which is emitted into the air from a bench surface near the burden by the arrival of a strong stress wave caused by an explosion. By measuring the maximum particle velocity at the intersection of a burden and a bench surface, the value of 165 dB is obtained as the peak pressure level of a blast noise at the bench surface near the burden. By taking a picture of a fragmentation and measuring the pressure level of the blast noise, it is concluded that the particular area in the blasted bench surface may be regarded as a surface sound source where the noise having pressure level of 165 dB is projected. The size of the sound source of which shape is almost rectangle can be regarded as follows for the case of an instantaneous blasting of a single row. Vertical length: the length between the lower level of the bench and the upper end of a charge. Horizontal length: the spacing of charge hole times number of holes those are fired instantaneously.
Furthermore, comparison of a peak pressure level and a root mean square pressure level is made, and the following ratio is obtained.
dB (Peak): dB (Impulse): dB (Fast) =1.08: 1.04: 1.0

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In the 1st and 2nd reports, by an experimental reappearance of the crooked-hole phenomenon of a deep boring the mechanism of the crook and the influences of the circulating rate of water, the wearland of tips of the bit and the thrust on the bit were described, by means of the inclined angle of 30° of th e boundary of layers.
In this paper, the relation between the crook of the borehole and the inclined angle of the boundary of layers were investigated, by the artificial rock samples changing the inclined angles as 15°, 30°, 45°, 60°, 75°.
Then, the followings were obtained within this experiment.
(1) In consequence of change of the inclined angle the drift angles showed different values at the larger wearland of tips. And, at the inclined angle of 45 the drift angle reached even the value of 10°.
(2) The direction of the crook of borehole was recognized towards the up-dip side even if the large inclined angle of 75°.
(3) The twisted angle as the value of the clock-wise deflection of the orientationwas considerable in any cases of inclinations in this experiment, and at the angle of 75° this value was shown up to 112°.
(4) Then, the larger the inclined angle was, the larger the horizontal shift of borehole was, and at the inclination of 75° the horizontal shift was amounted up to 28mm.
(5) Here, an index for the phenomenon of a dogleg was proposed and this was large at the smaller angle of the inclination in this experiment.

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Being founded on the field observation of the various gas outburst phenomena which have occurred at coal mines in Hokkaido, the author emphasizes that the origin of gas outburst could be nothing but the gas energy. Then they demonstrate referring to the actual examples that any gas outburst does not happen in reality unless the four conditions or mechanisms to facilitate its occurrence are satisfied.
As a verification of his opinion, he made experiments to cause gas outburst artificially by using ice charged with high pressure carbon dioxide.

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Separation of Polypropylene (PP) from Polyethylene (PE) was studied by making use of an air lift type flotator in which the former was recovered as a float and the latter as a sink, respectively. Separation between PP and PE was achieved satisfactorily by employing polyvinylalcohol (PVA) of relatively low degree of polymerization, i.e. n=500, as a depressant for PE.
Flotation results were well correlated with contact angle measurements and adsorption study. Greater decrease in contact angle, i.e. from 62° to 28°, was found for PE in contact with PVA aqueous solutions in a concentration range from zero to 100mg/l as compared with PP-PVA system where contact angle changed from 84° to 65° under corresponding conditions. Adsorption amount of PVA on PE was always greater than that on PP over the concentration range studied. The latter tended to increase with increasing the degree of polymerization of PVA, making the PP surface hydrophilic. Thus, it is essential to use PVA of appropriate degree of polymerization in order to separate PP from PE.

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Hydrogen as a secondary source of clean energy commands world-wide attention at present, regarding its indefinite supply in the form of water, its storage and transportation characteristic which are both superior to electric power, and its wide metallurgical and chemical usage.
The decomposition reaction of H₂S to produce H₂ and S⁰for recycle can be regarded as a main step reaction in many closed thermochemical water-splitting cycles based on sulfur chemistry. For this reason, the decomposition of H₂S with molten metals was studied.
As molten metals, Pb, Sn, and Bi were examined. Experiments were carried out in two ways. One is circulation and bubbling of H₂S gas into a molten metal. The other is soft blowing at the surface of the metal bath.
Conversion of H₂S to H₂ with Bi, Pb, and Sn increased in that order. In soft blowing of H₂S at the surface of molten metals, the formation of a dense film of the solid sulfide hindered the reaction. Such prevention was not found in the experiment with molten Bi, owing to much larger solubility of S in Bi (1).
Generation of H₂ was accelerated by the addition of Ni or Cu. This is due to the catalytic action of dissolved Ni or Cu in the melt. Addition of Cu to Pb accelerated the reaction even in the soft blowing of H₂S at the surface of molten Pb. It was found that crystal growth of PbS was affected by the presence of Cu and powdery PbS was formed in stead of a dense film. Although the addition of Ni to Sn accelerated the generation of H₂ there was a marked tendency to cause strong adhesion of the solid sulfide onto the inner wall of the lance.

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In this experiment, the authors studied the influence of the amounts of Pb and H₂SiF₆, and the influence of surface active agents in the lead electrolyte on the deposited potential, current density, dissolved potential and peak current density of the lead, and the following results were obtained.
1) The starting potential of the dissolution of the lead, E_O, increased with the amount of Pb in the electrolyte, but it decreased with the amount of H₂SiF₆. E_O did not vary with changes in the amount of surface active agents.
2) When the surface active agents were added in the electrolyte, the starting potential of the lead deposition, E_p, except for the addition of KSCN in the electrolyte, became lower than it had been in the case of non addition.
3) The starting current density of lead deposition, Ip, reached its highest level with the addition of KSCN to the electrolyte. But, with the addition of glue to the electrolyte, I_p decreased.
4) The peak potential, E_A, and the peak current density, I_A, of the lead dissolution were varied according to the concentration of Pb and H₂SiF₆
5) The peak potential of the lead dissolution, E_A, increased as KSCN was added and also as the surface active agents phenol and polypepton were added to the electrolyte. Especialy, when KSCN was added in the electrolyte, the potential variedl argely.
6) The peak current density, I_A, of the lead dissolution generally decreased as the surface active agents are added to the electrolyte.
7) From these results, it considered that the optimum for the electrolysis is Pb: 80g/l, H₂SiF₆: 80g/l and gelatin or glue: 1g/l-1.5g/l.

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