釜石鉱業所における山口鉱山産灰重石鉱の浮選について (第1報)

抄録

The valuable minerals of our plant (started since October, 1968) are scheelite, chalcopyrite and magnetite. The ore is ground to all minus 48 mesh by one-stage ball mill-classifier circuit. Copper concentrate is, first, floated by xanthate, iron concentrate is' next, separated- by magnetic separator and finally scheelite is floated by all-flotation method after intermediate thickening.
The 20% WO₃ concentrate from rougher flotator using caustic soda, water glass and fatty acid contains scheelite, apatite, calcite, sulfides (chalcopyrite and pyrite) and silicate gangue minerals. From this concentrate, first, sulfides are fejected by sulfide-reverse-flotation in batch flotator. At this stage by hydrochloric acid pH 0.1-1, calcite and apatite are changed to water-soluble state (Ca⁺⁺, Cl^-, PO₄4^---, etc.) and fatty acid adsorbs to sulfide mineral surfaces preferentially, so only sulfides float. Sinks (scheelite and silicate gangue minerals) after centrifugal dewatering and washing are repulped in the batch flotator and aerated at pH 2-7. This flotation pH must be selected by the quantity of residual adsorbed fatty acid. Generally speaking the more fatty acid adsorbs, the lower the flotation pH must be set.
At this stage fatty acid adsorbs to scheelite mineral surface preferentially, so only scheelite floats and 60-70% WO₃ high grade concentrate is able to be separated from silicate gangues by pH and batch flotation time control.
In this plant these flotation processes are called “Dephosphorization and Grade Up Process”.