The considerable rationalization of the beneficiation at Ôtani Mill has been accomplished by the Awamura Mining Co. Ltd, since it's reopening 1952. Principal improvements are given as follows:
1) The crushing capacity has been increased to 150% by the adoption of wet crushing.
2) It makes possible to be more effective for the heavy media separation process, by means of changing feed size range to-20+4mm from-25+6mm, and choosing optimum viscosity of heavy media. In order to get optimum viscosity, magnetite has mixed with ferro-silicon for heavy fluid.
3) To avoid over-grinding the closed-circuit operation (Ball mill and Dorr-F classifier) was changed to the open-circuit operation (Rod mill and Elliptex vibrating screen), so the mill capacity has increased to 230% with reduction of cost.
4) By the application of electro-static separation and differential-flotation methods, chief minerals such as scheelite, cassiterite, chalcopyrite and pyrites has been effectively separated, and mill recovery has increased.
5) The average grade and recovery of scheelite concentration has advanced by the adoption of fore table.
6) By the use of wet cyclone for classification of flotation tailing, the cost of tailing disposal has been a little or not.
By these improvements the saving of more than 57% in the total costs has been attained in 1959 as compared with in 1952.