Cyprus Pima has two concentrators, one with a conventional crushing-grinding circuit and the other using semiautogenous grinding followed by ball mills.
Old Mill Flowsheet
The original mill was constructed in 1956 but has been expanded three times so that by 1967 there were ten sections having a total capacity of 36,000 tpd. Subsequent revisions have increased this capacity to about 40,000 tpd. Mine ore is fed to a conventional three-stage crushing plant with final product, averaging about 25% – ½ inch, being conveyed to fine ore bins
New Mill Flowsheet
A completely new and separate primary crusher was constructed for the new mill which was put on stream late in 1971. Present capacity of the new mill is about 19,000 tpd. The new primary is identical with the existing one except that the crusher discharge is fed to a Barber-Greene radial stacker conveyor that can serve both the old mill stockpile and the new mill stockpile.
One unique feature of the grinding circuit is a provision to use the cyclone feed sump as a sump common to both ball mills or as individual sumps to allow the ball mill circuits to be operated separately. Another advantage is that when one semiautogenous mill