Dealing with leaking Mill Shell bolts is common enough an occurrence in most concentrator plants. All that an operator can really do about it is to keep the problem to a minimum.  The cause of the bolts leaking is running the mill with a density that is to light or feed that requires a high impact to grind.  This could either be due to hard or large ore.  “Leakers” are common on SAG and AG Mills as well as Rod and Ball Mills.

This extra impact on the liners will come from the rods because there isn’t enough fine ore to form a cushion between the rods and the liners.  By keeping shut down times to a bare minimum and making sure that the mill has ore in it as soon as possible when starting up goes a long way in protecting the liners.