Underground working place in coal mine in Japan became dipper and dipper, and we can not product coal so efficiently with our mining system, so called “inclined sys em.”
In order to more efficiently product coal, many people recognized, it is necessary to adapt the mining system in Europe, for instance in Germany and France, namelly so called “horizontal system”.
It is said, the translation from the inclined system to horizontal system is for our coal mine in Japan very urgent and important problem.
After War, many shafts were already excavated for the above mentioned purpose. As we know in Japan, many superior shaft sinking technic in Europe especially in Germany was introduced and technic in Japan was also very improved. But it is not yet so gut as in Europe. Till today many mechanization and rationalization was achieved, for instance, mechanization of loading (Adaption of Greifer) and rationalization of working system etc. Sinking speed in Japan is about 40-50m, in Europe. about 50-70m per month. In U. S. S. R, it is said, they excavated per month 241.1m.
From now ono we must force to achieve the mechanization of not only loading, but bohring, walling as in U. S. S. R. and also the rationalization of working-system and cycle.

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The aim of this report is to describe the present condition of heading in Japanese coal mines, whose performance is fairly inferior to that of forein coal mines.
The mechanical loading, although some improvement of which was made soon after the 2nd World War, has been standstill these three years, and handloading stills plays the leading part. The results of heading which were achieved by the use of various loaders shown in this item are representative of Japanese coal mines. I expect that all the coal mines of our country will quickly attain the level of such results, by strongly promoting the mechanimtion thereof.

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As in about ten years the new mining machines and technics were imported, the mining method in Japan were changed remarkably.
Natural condition of coal seam in Japan (1956)
Working depth (Average) 334.7m
(Maximum) 836m
Average thickness of seam 1.71m
Average thickness of coal 1.31m
Output from coal face 48.281Mill. t.
About 65% of output is worked by longwall method. About 36% of output is gotten by blasting, and 36% by coal picks in coal face, but coal cutters are used pretly well. Hobels are used in Emukae, Takashima, Kogayama and Mitsubishi-Bibai. 55% of output is conveyed Panzer conveyor at coal face.
Hydraulic stowing is carried out at Onoura and pneumatic stowing is used at Yamano, Akabira and Sakito coal mines. Slicing method for thick seam is carried out at Hojo and Takashima coal mines.
We must decrease the number of coal faces in one pit and increase the output per one coal face, and use the practical working time effectively.

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In this section, the recent technical progresses of underground supports are described. Topics specially interested are as follows.:
Result of antiseptic timber, use of movable casing for ease working of concrete block support, concrete yielding prop, results of roof-bolting and floor-bolting and measurements of load acting on underground support and of earth-pressure around coal face.

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One of the essential problems of the Japanese coal mining industry is how to elevate its productivity. This is why we have been exerting ourselves to proceed concentration of working places.
places. It goes without saying that the most important way to concentrate working places is to improve transportation services.
This report was intended to show recent development of transportation equipment in and out of Japnanese coal mines. It will also give a forcast what type of development in future.
All the transportation equipment which are refferrel to in this report show the top level techniques of this country.
As a whole, it may be said that the Japanese transportation devices have been taking and will eakea straight way toward larger scale and automation running.

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Underground ventilation of coal mines in Japan has made remarkable development in last 20 years.
1. Measuring method. Measurement of air flow and prevention of air leakage has been improved remarkablly, but measurement of ventilation pressure is still made light.
2. Ventilation method. Main fans have been largier and vinyl airduct are used remarkablly, but ausciliary fan is alone used at Ube coal mine. Warming of air at Mojiri and cooling of air at Iwaki must be attentioned.
3. The use of electric model for ventilation network. Electric models for ventilation network is used in Miike, Nishiki and other 2 or 3 coal mines.

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It is generally calls mine water that flow into working place from underground strata, and its flow characters depend upon local condition of measures and waterlevel change by opening.Large amount of inflow chiefly appears in domestic coal mine at coast regions, for instance, pumping up volumes are 30m³/min in Miike Coal Mine and 25m³/min in Joban Coal Mine. In these flows of water through porous measures, Darcy's formula is successfully applied to caluculation of mine water and its principle is modified for local condition. If inflow is quickly admited large qunatities of ground water through fissures, cracks, faults of overlying strata, it cause serious dangers such as mine flood. However, it may be possible to decrease in mining cost when it use for energy sources of hydraulic transportation, excavation, preparation etc. in underground, which has high pressure as latent energy.

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1. The present status on the coal mine safety in Japan
The number of fatals for the year 1956-613-was the lowest record ever had in this country. The average for the three years (1955-1957) was 644.0 compared with an average of 694.7 for the three preceding years. The average fatality rate per million tons of coal for the three years was. 13.83, and 15.11 for the three preceding years. Death due to falls of roof and face is the most among the coal mine accidents and is more than 40% of total death.
2. The recent progress in safety engineering.
The mining engineers in Japan have been interest on the follwing subjects: protection of mines against influxes of water, prevention of spontaneous combustion underground, prevention of falls of roof and face, improvement of supports, firedamp drainage from coal seams, prevention of gas outburst, prevention of pneumoconiosis, rock-dusting and water infusion in coal seams, prevention of surface subsidnece and landslide of waste heap and so on. These subjects are the chief problems on coal mine safety in Japan. The engineers in mines in cooperation with the investigators in laboratories are now investigating to solve them in order to improve the mine safety.
In this section some papers on the present techniques for the prevention of falls of roof and face, spontaneous combustion, gas outburst, and for water infusion in coal seams are contained. They are all representative techiniques at each field.

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In Japan, systematic.gas drainage in coal field began in 1952. At the end of 1957, it was adopted in 24 mines, inducing gas as much as 180 million m³/year, in pure methane equivalent, 100 million m³/year of which was effectively consumed.
The great proportion of the gas was for fuel for boilers.But, in some coal mines, the gas was utilized for producing Urea, Ammonium Sulphate, Carbon Black etc.
It is a remarkable fact that we are going to have a plant producing Methanole from coal field gas, which is the first plant of this kind in the world.
We have several methods for gas drainage; boring method, Mansfeld method, Hirch-Bach method, and induction method from sealed goaf.
For the purpose of exploiting the deeper deposit and of modernizing the coal mine, gas drainage is a quite effective technic.
In order to keep supply of coal field gas steady and constant for a long time, it is necessary to survey the condition of gas deposit, and to apply the most suitable method to it.However, we must remember that the prime aim of gas drainage is the “Mine Safety”.

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In order to save lamp room space and labour, self-service system of electric lamps has been adopted at several coal mines, such as Yubari, Mitsubishi-Bibai etc. There are comparatively a few permanent lightings in use in. Japanese coal mines, but in future permanent lightings must be installed to ensure the comfort and safety of workers. At Meiji-Saga coal mine, the bottom of a incline, main roads and underground rooms have been lighted by the installations of 85 fluorescent lamps.
Mechanization at underground areas results in greatly increased noise and it is consequently necessary to introduce some form of speech reinforcement. At Meiji-Saga coal mine, the conventional underground telephone and signaling systems have been installed at working faces, and brought about good results. At Ube coal mine, the ordinary telephones are installed so as to be used in case of emergency.
The underground power consumption increases with the progress of mechanization. And to economize in power is a serious problem of coal mines. A strict economy in compressed.air is practised at Ôyubari coal mine.

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