Mineral processing terminology:\nThe crushed material sent to a separation unit is called the feed or ________.

Introduction / Context:
In ore dressing and coal preparation, standard terms describe material streams: feed, concentrate, tailings, and middlings. Familiarity with this vocabulary is necessary to read flowsheets, material balance tables, and plant reports without ambiguity.

Given Data / Assumptions:

• We refer to classic mineral processing nomenclature.
• The stream in question is the incoming material to a separator.

Concept / Approach:
The incoming stream is “feed,” often also called “heads” or “heading” in some texts. “Concentrate” denotes the valuable product with enriched mineral content; “tailings” are the waste fraction; “middlings” are intermediate-grade streams that may require recycle. Therefore, the term that pairs with feed in this context is heads/heading.

Step-by-Step Solution:

Verification / Alternative check:
Historical flotation and gravity separation literature commonly uses “heads” analysis to denote the feed assay, in contrast to concentrate and tailings assays.

Why Other Options Are Wrong:

• Tailing: waste output.
• Concentrate: valuable product.
• Middling: intermediate grade requiring retreatment.
• Refuse: generic waste, not the feed stream.

Common Pitfalls:
Mixing up “head grade” (feed assay) with “concentrate grade,” leading to incorrect recovery calculations.

Final Answer:
Heading (heads)