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     An additional comment to John Monaghan's excellent reply to Paul
     Walker.

     Routine maintenance of the anode baskets definitely improves plating
     consistency. It avoids changes in the copper surface area distribution
     as the older (smaller) nuggets settle to the bottom of the basket. It
     also keeps sludge choked bags from being a problem.

     We made a sieve by drilling holes in a polypropylene plate that fit
     half way down into a large bucket. This allowed us to dump the basket
     out, rinse off the sludge and sort out the too small anode fragments.
     Nuggets large enough to not pass through the sieve were reused. Never
     reuse old anode bags, and leach out the new ones before putting them
     on the basket.

     We found that when we used enough baskets to get good current
     distribution in our tanks the copper concentration would rise because
     of all the surface area. Our trick was to place a length of small
     plastic pipe in the baskets before filling them with copper. This
     reduced the available volume in the baskets uniformly top to bottom
     while providing the same effective current distribution.

     A length of larger diam. plastic pipe is useful to slide copper
     nuggets into the top of the baskets on-line without much chance of
     them ending up in the bottom of the tank. It's also handy for knocking
     the copper down into a tightly consolidated mass in the basket.


     Andy Magee - Applications Engineer
     Rogers - Circuit Materials Unit
     Tel: (602) 917-5237
     Fax: (602) 917-5256
     E-Mail: [log in to unmask]