To: Elizabeth Andrews who wrote (523 ) 9/12/1998 11:58:00 AM From: Shaun M. Dykes Read Replies (1) | Respond to
One important point we are dealing with a single flotation concentrate containing all the metals Cu, Ni, Co, Pt,Pd, Au, Ag, Fe, and S plus a few other minor elements. The past work by Lakefield attempting to produce separate Cu and Ni concentrates was a mess. Lakefield working with Fleck(polymet) was able to produce a single reasonable flotation concentrate. The values of the recovered metals used to date are economic today. Currently metals recovered include Cu, Ni,Co, Au, Ag,Pt,Pd,S. The preliminary test were carried out on a couple of kgs of concentrate. The results gave extremely high recoveries of Cu, Ni, and Co from the concentrate(>95%). Precious metals are recovered by any of several processes avaliable *e.g. pressure leaching, acid wash. Pt and Pd Recoveries used have been conservative around 50%, metallurgists have indicated that these will be higher. High purity elemental sulphur can also be recovered. In addition an ilmenite concentrate may also be produced. In economic valuation Cu, Ni, Co, Au, Pt and Pd only have been used. The detailed information regarding the tests are in the reports from RPC and Lakefield. It may not be necessary to produce saleable concentrates, several options are being investigated ranging from concentrates to producing metal. The concentrate is clean, nickel one of the harder elements is measured as sulphide nickel and not total nickel (part of the total nickel is tied up in silicates and is not included in any calculations). Sulphide nickel is mainly pentlandite. No special grinding, handling or other unusual techniques were performed on the concentrate. It was a standard flotation derived concentrate directly from the cells. As said before the next stage is to take a larger sample to perform the continuous leach tests and also to test other hydrometallurgical methods recommended by the team of metallurgists currently assisting polymet.
