The Torigatayama limestone quarry is the most up to date and large scale quarry in Japan, located in Shikoku island, Kouchi prefecture. However the annual production capacity has been increased successively to 10Mt, 1983's annual production rate fell sharply than its capacity due to the depressed state of the Japan economy.
The operation is separated into two locations, Niyodo village and Susaki city. The quarry and the primary crushing facilities are in Niyodo village, and the processing plant and the ship loading facilities are in Susaki city. Both processing plant and primary crushing facilities are connected by the long distant belt conveyor of 23km long with the belt speed of 300m/min, of which 92% is installed in the underground.
The Torigatayama quarry has adopted the bench cut with vertical shafts system. The quarrying area has been getting wider to 0.8km
2 now and the elevation of the top bench is 1340m above sea level.
The production has started on May of 1970 after two years development work. Since then the accumulated production of 100Mt was achieved on Nov. of 1983. Roughly speaking, 50% of the products are sent to the steel makers, 30% to the cement makers, 10% to the construction works and the rest of them are shipped abroad.
The limestone are deposit is occurred in the Chichibu formation and it is covered by thin top soil of less than 1 m and has intercalation of the schalstein along the strike in the northern part of the are deposit. The minable are reserves are estimated around 1500Mt.
The climatic conditions at the quarry site may be characterized by the thick fog in the spring and the early summer, the heavy rain fall of around 1500mm monthly in the summer and the early autumn, and the cold weather of which temperature goes down sometimes 20°C below zero and the snow fall of more than 1m deep in the winter.
The detailed description of the operations are given as follows.
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