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NEW POLYMERS FOR THE BAYER PROCESS

Spitzer, D.P., Rothenberg, A.S., Heitner, H.I. and Lewellyn, M.E.

American Cyanamid Company has developed two new classes of polymers for the Bayer process, one for reduction of iron and another for reduction of suspended solids. The iron removal polymer is now commercially available as S-6370. This material was designed with functional groups that specifically complex iron, and it operates by agglomerating colloidal iron-containing particles, which normally pass through the filters, into aggregates that are large enough to be retained by the filters. This allows plants treating low iron bauxite ores to reduce the iron content of alumina product. The settling agent polymers are still under development, and represent a new class of polymers, very different from existing red mud flocculants. These settling agents replace both the polyacrylate and starch in primary settling, giving far better clarities (lower suspended solids) than are possible with polyacrylates. Alternatively, these polymers can be modified to give far higher settling rates than polyacrylates, with comparable clarities. Most work with these new settling agents has been on primary settling, but they may also be effective in washer train operations.