The discovery of Konomai mine was in. 1815 and after subsequent development many vein deposits were discovered. Among many veins the fth vein of Kuchannai zone is the largest of all and it is, so called, the champion vein of Konomai gold mine. The Fifth vein is geologically divided distinctly into two parts with east part being called “Foot wall vein” and west part being called “Hanging wall vein”.
The occurrence of ore deposits differs in nature that we are forced to adopt different types of stoping methods to meet different wall rock conditions. Some of the stoping methods practiced are shrinkage stoping and square-set caving method.

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Segoshi mine lies on the west side of Izu peninsula. The deposits of this mine is fissure fil1ing gold-silver quartz vein in the Tertiary Yugashima beds.
The horizontal cut-andrfill method is being used here. In development drifts are not driven along the vein due to high water flow. The haulage levels are driven along footwall parallel to the vein with short crosscut driven at interval of 30 meters to the vein in order to mine and draw ore.
Waste filling are dropped through waste raise in the stope.

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Kushikino mine deposit is epithermal type deposit composed of more than twenty parallel gold bearing quartz veins with twopyroxene andesite intrusions.
Among them No.1 vein is the main producer and its general strike is between N 50°E to N 70°E and, dip between. 30°to 70°SE.
The average assay value of ore reserve of gold and silver are 3.4g/t, and 46 g/t, respectively. This typical low grade ore with huge ore body is mostly mined by cut-and-fill and crosscut mining methods.
In cut-and-fill method scraper hoist is used to mechanize haulage of ore and back-fill and square-set mining method is replaced by cross-cut method to raise both mining efficiency and ore grade of run-of-mine.

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Shimokawa Mine is one of the youngest and most mechanized mine in Mitsubishi Metal Mining Co., Ltd., producing 8, 500 tons per month of cupriferous pyrite are with grade of 2.3% Cu at present.
Since 1941, when it was first being developed, the production has been increased with successive years to present production level.
The deposit is the cupriferous pyrite, which belongs to the contact metamorphic type. Although the foot wall is hard diabase, the hanging wall is weak and friable phyllite. The dips of the are bodies are about 50° and the are body itself is blocky as it has many longitudinal and crosswise faults and fissures, furthermore, its width has great tendency to expand and pinche in vertical and horizontal directions.
Accordingly, the mining method adopted is timbered back-fill transverce flat back stoping. The dimentions of a mining block is 30 meters in span, 2 meters to 30 meters in width, and the level intervals at 30 meter in height. In standard mining face of 4 meters by 2 meters air leg drills, portable air slushers, waste filling machines, and baby-conveyors are operated by three-man crew.
The output of one block per month is about 500 ton an average and one miner produces about 47 metric tons per month.

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The deposit of Taro mine belongs to cupriferous pyrite type ore or, so called, Kieslager type in paleozoic phyllite.
The two different types of mining method adopted here are the caving method and the timbered horizontal cut-and-fill method.
The caving method has been used ever since Taro mine was first developed, but recently it is used only in the old stopes where it was previously mined by caving method, to recover pillars.
In some of the small deposits with less older stopes in the lower levels, timbered horizontal cut-and-fill method is carried out.

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The ore deposits of Hitachi Mine are cupriferous pyrite ore, belonging to the “Kieslager type”. The veins extend over two thousand meters along the strike from east to west. The country rock of these ore deposits are chiefly chlorite schist, sericite schist and biotite schist with hardness varying in various degrees.
This necessitates the use of mine timbers not only in the stopes but also in the drifts. For this reason overhand horizontal cut-and-fill method has been, adopted in most of the stopes.
In 1952, we have succeeded in filling the stopes with sand slime from the milling plant. Since then, we have introduced under-hand horizontal cut.and-fill method with sand slime as back filling on top of the top slicing method and thereby, greatly improved the method of mining. This method has been adopted together with the overhand horizontal cut-and-fill method in our mine, but the production of the former method alone amounts to about half of the whole production at present.

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Kune mine is composed of two mines, namely; old Honzan and new Nako mines.
Honzan mine had been coorked for a long time. There-fore, the lower parts of the ore deposits are chief underground workings with ore production of about 4, 500 tons per month. The prospecting is mainly conducted on the outskirts of the know deposits at present.
Nako mine was discovered some 40 years ago and operated for 7 years. However, the depression had forced the mine to be shut down until. it was reopened about 20 years ago. Since that time the development work has been continued in this mine and the production of the mine is 9, 000 tons per month at present.
As for the mining method, the horizontal cut-and-fill method is used at both mines with some modification in practice between them.
In this paper details of this mining method is chiefly described.

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The are deposit of Minenosawa Mine is a typical cupriferous pyritic are bodies deposited in Sanbagawa crystalline schists.
The mine was reopened in 1941, but prior to this date, portions rich in copper had been mined out.
The weakness of wall rock and the existence of many cracks and fissures in the are itself make stoping difficult and, naturally, the timbered cut-and-fill method has been adopted. However, from September last, we began introducing sand filling system to all stopes, and the results are proving satisfactory. Furthermore, in the stopes we are making use of steel posts and caps in place of timber that the consumption of timber has been decreased considerably

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The dip of Emori are deposit is so low that it is impossible to move broken are by gravity. Only means to overcome this battleneck is to use scraper, but, unfortunately, the timbering used to support the hanging wall, which is very weak, interferred with the scraper.
In 1952 with timbering being replaced with roof bolt and adoption of milisecond blasting delays the scrapers were first tried out. Since then the mining method has been improved and now the scrapers are gradually being used in cut-and-fill stoping.

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At present the Besshi Mine is producing ores at a rate of 200% more than that of 1951. This increase was attained not by the increase of number of workers but mostly by increased efficiency realized as a result of rationalizations, such as, development of lower and middle sections of are deposit, improvements of transportation, ventilation and cooling of air etc. and also concentration of working stopes and technical improvements by mechanization.

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At Sazare Mine overhand stoping, shrinkage stoping and, in rare cases, underhand stoping methods are adopted.
Sazare Mine has increased its production at a rapid pace year after year.
In order to obtain this result it was necessary to make efforts for the improve the complicated underground transportation system and also to experiment on the most economical and safetest stoping method. Recently, we are devoting great deal of our time in solving our problems.

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The deposits of Okuki mine are geologically classified as cupriferous pyritic bedded deposits, and are formed by many deposits of different magnetude, such as, from 10 to more than 10 thousand tons (in the area), which has the strike length of 1.3 km and width of 0.3 km.
Many high grade portion of this large deposits in the area were mined out in the past.
All that was discovered among them were so small that thay are now mined unsystematically. The southern deposits, 0.1 km. south of the main area, and some places around the above mentioned mined parts, they are both mined systematically. In some goafs filled with old waste (0.8-3% Cu), which is taken out as ore by systematic method at present.

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The ore body of this mine is flat with an average dip of 12°and its thickness is large running as thick as 4 meters on the average and with a maximum of 25m. However, its inclination is highly variable not only in the dip side but also in the strikeside. Moreover, pyrrhotite which forms the principal component of the ore is extremely unstable and, naturally, we have to make use of a large number of scrapers to mine the ore in a short space of time. Mining is done by room and pillar method but in certain faces, tests are being made with sand mortar filling.with band pillar system in order to stope out ore pillars.

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The ore deposits of Makimine mine is cupriferous pyrite ore emplaced in thefissures, parallel to fissility of phyllite in form of “blade of bamboo”.
The dips of the deposits ranges from 20°to 55°witch length along the strike is about 10 to 60m with maximum of 150m. The thickness is about 0.10 to 1.0m and the length along the, dip being several times the length along the strike.
The intervals between main levels are 50 meters vertically, 100-120meters along the dip, and there are two sub-levels between them.
In the past the room and pillar method without filling were used, and when the pillars starts to crush under ground pressure, they are mined out by hand, which is, so called, “timbered stripping”. Even at present many pillars are still left under similar conditions, which are mining by hand. The ore produced by this method amounts to about 38% of the total mine' production.
At present different filling methods are adopted, according to the thickness of the ore deposit as follows;
1. thickness over 50cm cut-and-fill stoping
2. thickness under 50cm stripping method.

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The stoping methods applying now at Osarizawa mine are classified as follws;
1. Shrinkage stoping method
This method has been adopted at stopes where the walls of the vein are strong and the widths are wide.
2. Back filled stoping method
Where the factors of safety and the dilution of ore demand prompt support of walls, we are gradually changing from the shrinkage method to the filled stoping, where sand slime filling is successflly put into practice.
According to availability of filling materials and ground conditions, the filled stoping methods are further classified as follows:
(1) Horizontal cut-and-sand slime filling method
(2) Horizontal cut-and-waste filling method
(3) Stripping method

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The Washiaimori mine is located about 12km south of Oishi-station on Okoku Railway line.
The main features of the veins are indicated by their narrowness in width (about 20-40cm), and considerably high in grade (7-10%).
The stripping method is mostly adopted for these types of veins with a success.
The output of ore driller per shift is 7-10 tons of crude ore with grade of about 4% Cu. About 80% of total production comes from this method.
From our experience it is found that for the vein width under 50cm, stripping yields larger profit than any other methods.
For wider portions of “Hompi” vein, which ranges from 0.3m to 2.0m, filled flat-back stoping is adopted, but on account of the weakness of both walls and vein matters itself some difficulties are encountered for complete extraction.
The underhand filled fiat-back stoping (Slices taken in descending order) is now under trial as an alternative method.

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Stripping method, which was used for high grade ore before the mill plant was installed, has been replaced by the shrinkage method (filled with waste after ore is drawn out) when the mill plant was built and started operation.
In this mine, both the foot-wall and the hanging wall are fragile and the ore itself is so badly fractured that the shrinkage method had to be changed gradually to the filled stoping method.
At present, filled flat-back, underhand and shrinkage methods are used. However, we are faced with several problems with filling and it seems necessary to reconcider the stoping method.

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Ashio mine is one of the largest copper mine in our country, discovered by a farmer about three hundred and fifty years ago.
Since 1875, Furukawa Mining Co. has been operating this mine. In early days Mining status of this mine was not so bright, but positive work on development was maintained to produce good results, that is to say, many copper rich veins, especially, the “Kajika” deposits were discovered. Since then, the production has been increased to present day level to become one of the largest copper mine.
During the World WarII, unfortunately, the prospecting work was far behind the exploitation work. Therefore, production was greatly decreased when the warwas ended. Now production has been recovered to produce 320 tons-350 tons of copper per month by rationalization of operations and prospecting works. The principal stoping method used here is the shrinkage method.

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当山は石川県小松市にあり, 北陸線小松駅の南東約17km, 尾小屋鉄道(小松駅一尾小屋駅)の起点尾小屋駅の南東約1kmに鉱山事務所, 製錬場がある。
採鉱現場は本山と大谷, 岩淵, 白山の3支山にわかれ, 本山は鉱山事務所の東北約2kmで, 選鉱場, 工作諸施設がある。大谷, 岩淵, 白山支山はそれぞれ鉱山事務所の東北約8km, 北約11km, 北東約16kmにある。
鉱種は金, 銀, 銅, 鉛, 亜鉛鉱及び硫化鉱である。
本山3支山とも開発時代に差異があり, それぞれの規模に応じ独自の開坑及び採鉱の過程を経て来たが現在では通洞地並以上に賦存する鉱量には見るべきものが無く稼行の主体は各山共かなり深部に在る。
出鉱された粗鉱は本山においては“エンドレス”(全第1表 (昭和31年下期1ヵ月平均実績)長300m)により各支山は全長11kmの索道により本山に在る選鉱場に送られ, 白山のみは簡単な手選を経た後一部を当山の製錬所に他を選鉱場にトラックにより運搬している。

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The Kishu Mine in the district of Kishu (Wakayama Pref.) was established by the amalgamation of a number of mines located in the near vicinity.
The deposits comprise of fissure-filling veins in the Tertiary sedimentary rocks. The width of the veins varies from 10cm to 4meters, with an average width of approximately 40cm. The dip is 70°to 80°. The country rock cousists of comparatively hard sandstone sandy shale, shale and their alternation and, consequently, the walls hold up satisfactory. The principal vein runs about 1, 500meters.
Since Shrinkage Stoping Method is suitable for working on such vein structures, this method has been adopted from the beginning. Up to now quite a number of improvements in drilling, blasting, underground transportation, rock drills, bits and so on have been made with the results that today the crude ore mined per month has been doubled and the production efficiency per miner per day about 1.5 times more than that of 1947.
We are presently trying to solve the problems of handling and treating broken ores which tend to harden to a mass.

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The ore deposit of Myoho Mine is a fissure filling type in the country rocks of sandy shale sandstone and conglomerate which are interbeded, alternately. As the wall rocks are weak, the mining methods have changed from time to time, but at present the waste filling stoping method of several variations are being adopted. The veins, which are worked now, ranges in width from 0.30m to 9.60m with average of 1.09m and the dips varies from 45°to 85°.
The level intervals are at 20meters, vertically, and the block of ore is set up every 30 meters by raises.
The stoping method adopted are decided, according to the ground and vein conditions as follows:
1. Where the walls are hard...Horizontal cut-and-fill stoping without timbering.
2. Where the wall rocks are weak...Horizontal cut-and-fill with timbering.
3. Where vein width are wide and weak... Same as (2) or Crosscut methed.

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At Ikuno mine, the shrinkage method has been practiced in all stopes for a long time, but it has been gradually changed over to sand-slime fill stoping method from 1950.
Recently, the ratio of filling method and shrinkage method is 70% to 30%.
In comparing the shrinkage method to the filling method there are following advantages in the latter,
(a) High extraction of ores due to recovery of pillars.
(b) Prevention of hazard from caving in stopes and in heavy grounds.
(c) Prevention of dilution of ore.
(d) Improvement of Ventillation system.
As Ikuno mine is developed to depth close to 900meters from the surface, it is very difficult to transport the filling waste materials to stopes. Where as, this new method is very suitable for the workings, as the filling materials are transported rapidly and cheaply by pipe.
This paper discribes the details of operation of the sand slime fill stoping method, and the problems involved, which are still to be solved in future.

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The Akenobe mine consists of many narrow veins, with different conditions, having varied dips, vein widths and depths.
The stoping methods practiced are horizontal cut-and-fill, shrinkage and stripping methods, according to the vein conditions mentioned above.
In the past the shrinkage method was used for the entire mine, but from about 1951, as the workings moved out to the fringes of the main ore deposit, the walls became weaker, the dips of veins became lower and thevariation of the vein widths became more frequent that the modified shrinkage stope with cribbed chutes and the cut-and-fill stope with fillings hauled by wheelbarrow were adopted.
Recently, the portable air slushers are used widely in horizontal cut-and-fill stoping.
The ore production by this method amounts toabout 54% of the total mine production.

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The country rock of our mine conisists chiefly of tuff, belonging to Tertiary period. The are deposit is formed by replacement in this tuff. The are is mostly sulphide and is made up of lumps and fines in sandy form mixed with clay.
As the walls are soft and there is a tendency of sinking and crumbling, we are adopting sub-level caving and top slicing methods to mine the ore.

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1・1鉱種金, 銀, 銅, 鉛, 亜鉛, 硫化鉄, 鉄, 及び重晶石
1・2位置・交通当山は青森県上北郡天間林村地内. にあり, 東北本線乙供駅より青森営林署軌道により, 大坪川を遡ること約28kmで達する。特に冬季間は積雪多量のため, 雪上車を利用している。諸物資の輸送は鉱山～ 野内間の索道 (約20km) により行つている。最近田代トンネルを経て青森への自動車道路も完備した。

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The ore of Hanaoka Mine is complex one, which is typical of so called “Black Ore”. The products are copper, pyrite, lead, zinc, gypsum, barite. The geological features control in mining methods are:
1. The ore bodies lie under river level.
2. The alluvium contains water bearing gravel strata, acting like “quick rand”,
3. The ore bodies distributed in an area of several -kilometers are apparently in massive state and their diameters ranging from several tens to handreds meters and they are surrounded byclayish soap stone, soft green tuff, or cut acrossed by clayish crack and the ores are often powdery.
Accordingly, when the ore bodies have tendency to cave, so the stopes are always timbered. However, no timbering of small scale is needed _ in stoping in comparatively hard Cu-bearing pyrite or gypsum ore bodies.
Owing to the above mentioned conditions, the following mining methods had to be adopted:
1. Open-Cut mining.
2. Crosscut caving method for soft Cu-ore bodies,
3. Short-Wall top slicing method for Cu-ore bodies,
4. Under Cut Block Caving method for low grade pyrite ore bodies,
5. Underhand and Overhand Square-Set stoping with filling for high grade Cu-ore bodies,
6. Cut-and-fill stoping for pyrite ore bodies.

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The main “black ore” body of the Takara mine is massive and crumbly, so cross cut caving method has been used. Seven sublevels were driven in the wall rocks around the ore body at about 10 meters intervals vertically. From each level cross cuts were driven radially to the ore body at about 10 meters intervals horizontally. Then the mining drifts of 6-7ft. wide and 7-8ft. high with timber and laggings on the roof and sides were driven from the crosscuts to mine the ore. When the crosscut mining is completed the ore above isallowed to cave-in for the next crosscutting.
Steel supports are recently used in a fewstopes, in place of timbers. In other small lenticular ore bodies shrinkage and square-set methods are used.
In recently developed new ore body waste filling method will be used.

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Since the general shape of Yanahara ore deposit became clear, it has been worked by over hand stoping with natural pillars.
However, from the experiences cave-in and rock falls on a large scale, it was found that the height of those pillars could not be over thirty metres, and later extraction of pillars would be quite difficult and costly.
Therfore, at present, non-pillar mining methods are studied by arranging sometest faces.
Meanwhile, square-set method, “kappe” mining method, etc. are being adopted for trial.

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当豊羽鉱山は北海道石狩国札幌郡豊平町に位置し, 金, 銀, 銅, 鉛, 亜鉛, 硫化鉄, マンガン鉱を産する。当山発見の年代は明らかでない。明治末葉から大正初めにかけて, 探鉱の傍ら地質調査が実施された。大正3年久原鉱業が買収開発し, 翌年には銀を対象とした乾式製錬所を水松沢に設置して操業を始めたが, 欧州大戦後の不況のため, 大正11年操業を中止した。昭和10年久原鉱業の後身である日本鉱業が再開し, 逐年操業規模を拡大, ことに第2次大戦による非常増産の要請に応えて昭和17年には選鉱場の処理能力を月25,000tに増強したが, 同19年9月白井川河床が陥没, 浸水のため, 坑内水没し, 操業中止のやむなきに至つた。昭和25年6月豊羽鉱山株式会社が設立され, 日本鉱業より事業の一切を継承しで今日に到つている。

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At Oppu mine cut-and-fill method is applied to veins dipping at 20 to 30.
The rationalization has been mainly accomlished by speeding up production at fewer working stopes by using slushers for waste filling and are slushing.

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The Hosokura mine, Miyagi Prefecture, is the second largest zinc and lead mine in Japan next to the Kamioka mine. There are many narrow veins which belong to epithermal vein type deposit in propylite and tuff, genetically related to propylite or liparite.
For a long time, only shrinkage stopes with delayed filling or without filling to allow cave in, havebeen successfully applied here, because the greater part of these veins are narrow and steep-dipping deposits with considerably, strong walls. But recently, in order to attain higher and cleaner extraction at the richer orebodies by preventing dilution of ore, and to make mining safer, we have adopted partly flat-back filled stoping, so called, HORIZONTAL CUT-ANDFILL STOPES, in some veins, where the vein walls are weak or veins are low-dipping.

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The ore deposits of Chichibu mine consist of several deposits, but the main ore body is Daikoku, which is formed by contact replacement. The shape of the deposits are very irregular, forming massive, vein and chimney type deposits with varying size from 2, 000t to 200, 000t.
The minerals of the ore are composed of magnetite, pyrite, chalcopyrite, marmatite, galena and native gold, creating a very complex ore.
With ore body being very irregular in shape it is difficult to block out stopes schematically and break ore to regular sizes. But we are fortunate in having a very hard and stable hanging and foot walls, that shrinkage stoping is most suited for the mine.

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