The considerable rationalization of the operation at Nakatatsu Mine, Fukui Prefecture, has been accomplished by the Japan Zinc Mining Co., Ltd., since its reopening in 1951. Principal improvements are given as follows:
1) Selective mining by the cut-and-fill method was widely adopted underground in order to maintain a grade of run-of-mine ore to a certain extent.
2) The cost of transportation was appreciably cut down by concentrating working, faces and using scrapers as a means of face conveying.
3) Low-cost non-core boring method was successfully employed as a prospecting tool.
4) In order to increase the capacity of the concentrator materially, it was decided to apply a hand-picking powerfully to reject tailings prior to milling and flotation.
By these improvements the saving of about 20 percent in the total mining costs has been attained.
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