Middlings

The product described in the earlier contract is: 'All the zinc sulphide crude ore, zinc sulphide concentrates and zinc sulphide middlings, shipped from Midvale, Utah, Kennett, Cal., or any other point by or under the control of the seller during the period of this agreement.'

The bitumen floats to the top of the separation cell and is largely recovered in this top-layer froth[…], while sand is discarded at the bottom and the middlings of intermediate density are partly returned to the separator for recycling and partly forwarded to a scavenger separation cell […] for separate treatment in a froth settler[…].

Buckwheat middlings is a fairly good feed for dairy cows, being far superior to buckwheat bran.

More or lesser amounts of middlings are always formed, and must be reprocessed to salvage the good seed it contains. The middlings fraction can be re-separated over the gravity separator to salvage the good seed. […] To salvage its good seed, middlings are re-separated over the gravity. This spreads the middlings out further over the deck, and produces a closer separation of good seed from the undesirable material.