The gas outbursts in Japanese coal mines increase with a increment of working depth. The cause and mechanism of gas outburst are not always clarified. The author described and examined on this problem with a practical experience and tried to find some suitable methods to protect it in Japan. Some views on the cause and mechanism, pressure and quantity of gas outburst etc. are described on this first report.

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This is the report of the Construction of the Ferro-Nickel Smelting Plant in Pomalaa, Indonesia wnzcn is me project or P.T. Aneka Tambang.
Pacific Metals Co., Ltd. took up the role of General Consultant and proceeded the Performance Guarantee Test followed by the Technical Assistant after the Commercial Operation.
This Ferro-Nickel Smelting Plant is the first Ferro-Alloy Smelting Plant in Indonesia, and is considered as the first step of industrialization of Indonesia as the national project.
In August 1970, Basic Memorandum to cooperate to this project was signed and basic agreement was signed in Sept. 1971 together with Technical Assistant Agreement.
The construction at site started from Oct. 1973, and construction was completed in Nov. 1975 just as scheduled in the original project plan. On that date electric furnace was started operation and Performance Guarantee Test was completed in April 1976.
1. The outline of the project is as follows;
(1) Smelting Process Rotary Kiln electric furnace process.
(2) Ore low grade garnilite nickel ore.
(3) Products low carbon Ferro-Nickel.
(4) Production Capacity 4, 000ton Ni+Co metal equivalent per year.
(5) Main Equipment
Ore treatment equipment screening, crushing, mixing plant.
Ore calcining plant rotary kiln 4.0^mφ×90^m
Smelting furnace 20, 000kVA electric furnace 5.6^m×15^m
Refining furnace oxidizing shaking converter 15t/charge desulphurizing ladle 15t/charge
Oxygen plant 300^Nm3/hour
Power plant diesel generator 5, 700kW×5
2. The characteristics of the project.
The design of the equipment is based on the 25, 000kVA plant in Hachinohe and has been modified based on the operation of 40, 000kVA plant which is the most modern Ferro-Nickel electric furnace smelting plant in Japan, and the equipment are all supplied by Japanese machineries manufacturers.
3. The result
The Performance Guarantee Test was succeeded in April 1976, and the project was completed exactly according to the schedule and design.

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Undersea coal mine, Ikeshima operated by Matsushima Coal Mining Co., Ltd. is located in the western part of Nagasaki Prefecture.
It was a necessary conditionto develop a new low sulfurous coal field for the regulation of SOx.
The geological survey and development started in 1971 and the removal of the faces to Hikishima was performed within 1974.
It is now producing 1.2 million tons bituminous coal a year successfully.
New field is the area of the isle of Hikishima, 0.22km² and its circumference.
This paper describes on the following points.
(1) Geological survey
a) geophysical prospecting
b) deep boring on the sea
c) coal reserves
(2) Progress of the development
a) mining and transport system
b) mine ventilation, cooling and drainage system
c) shaftsinking by the short step and grouting method
(3) Questions in the future
a) confirmation of the proved coal reserves
b) rationalization of the transport system

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Mitsubishi Metal Corporation has successfully developed and commercialized, withcooperation of Ishikawajima-Harima Heavy Industries Ltd., a new continuous copper smelting and converting process (MI Process). After more than 15 years of basic research works and pilot plant tests, the first commercial plant applying thisnew system was completed and put into operation in March, 1974 at the Naoshima Smelter of Mitsubishi Metal Corporation.
The distinct features of the MI Process are summarized below:
(1) The process is of multi-furnace system, in which the continuously-operated furnaces, respectively performing each essential metallurgical function, are interconnected by launders.
(2) Top-blowing lancesare used to feed oxygen-enriched air, copper concentrates and fluxes.
(3) The shape of the furnaces and other auxiliary facilities is rather simple and compact, thus saving costs for investment.
(4) The function of each individual furnace is simple and conventional labor-intensive operations, such as furnace tappings and crane operations, are eliminated. Together with successful application of the computer control, the labor requirement has been greatly reduced.
(5) Continuous stream of furnace gases rich in SO₂ is generated, thus permitting economical production of sulfuric acid.S pill gases, which are inevitable in conventional processes, have been also eliminated.
(6) The process consumes less energy than conventional methods.Due to these unique features, the MI Process have overcome many difficult problems now facing the copper extraction technology.

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In this report, the authors discuss on the fracture around a borehole under the biaxial compression and hydrostatic internal pressure.
The theory of linear fracture mechanics is applied to the shear fracture of borehole-wall, which is sometimes observed in the borehole drilled in the high stressed rockmass.
Then, the authors discuss on the application of hydrofracturing method to the measurement of in-situ rock stress, from the point of view of linear fracture mechanics. Theoretical analysis revealed some problems to be verified by some field and laboratory tests.

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The wear of the cutting tool is one of the most important factors in the cuttingpractice.
We, firstly, have studied the tool wear in rock cutting under a condition of the orthogonal cutting with a small depth of cut so that the chips flowed out in the form of shear type.
In case of this cutting, the wear on the rake face did not almost be found, but only a round wear of the tool edge or a flat wear of the tool flank took place. Generally, in case of cutting of hard rocks such as granite, the flank wear largely developed, not likely as for soft rocks in which the tip wore roundly. When the thrust component of the ploughing force was larger than the cutting component, the flank wear was dominant, and for aninverted relation between both components, the round wear of the tool edge took place.
The calculated values of the ploughing force components at the bluntedtool edge with various types of wear, using some stress distribution models, agreed with the measured values.

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