Our Sorachi Mine situated in the northern part of the Ishikari Coal-Field in Hokkaido was opened for mining in 1890. Since then, we applied many systems of mine opening...such as drift from outcrop, the gallery entry, the shallow shaft, the steep shaft, and the incline method, Up to 1957, both three inclines let out only 800-900 tons per day, and then the coal reserves available, had only three years in a life of exploitation.
The output production plan was decided in the maximan of 1600tons per day withoutincreasing the capacity of the washing plant and the National Railway. Due to the housing and water ways problems, it was impossible to increase the number of workers.
In order to double the output total, it was either to increase the output per man shift at the face. cut (1), or decrease the number of indirect workers and transfer them to the face cut (2). In these two ways, the latter was decided by the reason that geological conditions were too complex and difficult to adapt the first way.
Then a plan with a capital investment of 1600 millions yens was carried out. A speedy opening by a new field was struggled by means of:
(1) Reconstruction of mine structure (Horizontal mining system)
(2) Adoption of permanent spports
(3) Synchronized rationalization of transportation (by automation and remote control)
(4) As well as modernization and intensification of pitmouth equipment installations In three years time, from May 15, 1957 to. May 13, 1960 and with 390, 000 workers, the construction works were completed according to a plans.
As a result, the output per day was increased from 839 tons average in 1959 to 1154 tons in January 1961, just 8 months after the completion. And the output per man-month was increased from 18.4 tons to 28.6 tons.
And the man-powers per 100 tons of output in the face working was reduced to 38. 0 M. S, . in the indirect working 23.9 M.S.and in the under ground working 61.9 M. S. after all. While, the man-powers in the surface working was reduced to 17.4 M. S. These productivities of labour are already near the levels in the Wester Europe.

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At the Yanahara Mine, systematic prospecting for the deeper district was started in 1951. In 1954 huge are deposit was discovered, It's are reserve is as much as seventeen million tons at present.
Those days, other are bodies were of ten suffered from spontaneous combustion and rock falls etc., and the mining condition was growing worse gradually. Under such a situation rapid developement of the new are body came to be the only way to prevent the decrease of production and rise of mining cost.
The developing construction contains many works such as Kabu-shaft sinking, Kabu-skip-shaft sinking, Central shaft sinking, application of new mining method, establishment of new ventilation system, reinforcement of drainage, modification of transportation system for filling materials, reinforcement of man and material shaft etc. They were devided into two periods as follows, that were performed steadily and positively.
1. Prospecting and developing period
2. Mining preparation and the construction to isolate the new deposit from others.
Among them, sinking of Central shaft.was started on 29 th April 1959, and was accomplished on 3rd March next year. During this period, 483m of sinking and 147m of level-driving were performed, and so 63m of average driving speed per month was obtained as the result, and that, no accident happened through all the time.
As regards mining method, combination of overhand stoping and sub-level stoping was arranged into new type in order to obtain perfect safety, high mechanization, and intensive mining.
As the collective effect, the attitude of monthly production of 40, 000 tons from new are body wasestablished within three yeors after the discovery. Further more, in 1960 monthly production of 100, 000 tons came to be possible from whole mine.
During those days, production from new deposit increased ten times as much, and at the same time whole mine production and its' mining cost could be maintained in normal situatior.
At present, considerable amount of production-increase is possible, and we have further got the clear indication of the newer are deposit by dint of those successful constructions.

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The reduction of SiCl₄ with hydrogen in the electric field was studied. Using heated tantalum filament at 1, 150°C with A. C. as cathode, high voltage up to 3kV was maintained between the cathode and the cylindrical tantalum anode. These were set in the reaction tube of quartz. The mixed gases of SiCl₄ and hydrogen were introduced into the tube, and the deposition of silicon was carried at about 1, 150°C on the cathode. The higher the voltage, the more the yield of silicon increased. The effect of the concentration of SiCI4 in the gas mixture on the yield was studied.
The appearances of the deposition on the filament were observed microscopically and with naked eye. The tantalum was entirely removed from the deposits with leaching in hydrofluoric acid.

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The extraction of lead by direct electrolysis of lead sulfide using lead silicofluoride, lead borofluogide, lead acetate, lead nitrate, and lead perchlorate solution as electrolytes has been studied.
The results were as follows:
The sulfide anodes revealed passivity in a short time with lead silicofluoride electrolyte. Their dissolution was not smooth. with lead borofluoride, lead acetate and lead nitrate solution, while in the perchlolate solution, they dissolved successfully.
The prolonged electrolysis was then carried out with some lead concentrates as anode using lead perchlorate solution.
It was fot.md that the richer the concentration become, the better the anodic dissolution proceeded.

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This is a report of studes on the extraction of potassium in Kali-rhyolite by the thermal treatment with the chlorides, obtained in the chlorination of titanium-containing ores (ex. titanium-slag, ilmenite).
The chlorides that contains FeCl₂, MgCl₂, AlCl₃, etc. occurs as the by-product in the chlorination pro cess.
To make potassium in Kali-rhyolite water-soluble, Kali-rhyolite was mixed with the chlorides and heated for several hours.
The potassium in the ores was almost completely (max. 95%) extracted when the mixture of the chlorides and ores (ratio 1: 2 in weight) was heated for 5 hrs at 800°C. The product was further treated with air at 800°C for 3 hrs to change the chlorides except potassium salt to unsoluble oxides. The product may be used as the fertilizer containing water-soluble potassium.

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In extracting sulfur from ore by means of the autoclave method with superheated water under pressure the yield of sulfur differs materially in accordance with ores used. For improving this method, the author made an examination on molten sulfur- and water-wettability of each sample of component minerals found in sulfur ores and classified which kinds of minerals were improper for extraction.
The results of sealed glass tube tests are summarized as follows:
1) Quartz, opal and many silicate rock minerals were hydrophilic and harmless for extraction.
2) As for clay minerals, some were harmful and some were not, viz., kaolinite, halloysite, fire clays; pyrophyllite, talc etc. were amphiphilic and harmful; while montmorillonite, muscovite, illite, saponite, allophone, diatomite etc. were hydrophilic and harmless accordingly.
3) Alunite, calcite, limestone, limonite, iron and aluminium hydroxides were amphiphilic, while gypsum, iron and aluminium oxides were hydrophilic.
4) Sulfide ores such as iron pyrite had affinity for sulfur and intermixed with sulfur, but did not hinder its agglomeration.
In further observation, there was a good coincidence between the results of the examination on samples whose components were known and those expected from these components.

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