Stage identification from size range:\nFeed size 300–1500 mm reduced to product 100–300 mm corresponds to which crushing stage?

Introduction / Context:
Crushing stages are often identified by the characteristic size ranges handled. Correctly naming the stage helps with equipment selection, liner choice, and downstream sizing of screens and conveyors.

Given Data / Assumptions:

• Feed lump size: 300–1500 mm (run-of-mine scale).
• Product size: 100–300 mm (coarse fragments for secondary crushers).

Concept / Approach:
Primary crushing accepts very large run-of-mine rock and reduces it to sizes suitable for secondary crushing. Typical primary crushers (jaw or gyratory) produce products in the 100–300 mm range, exactly matching the stated output. Secondary crushers then reduce further to tens of millimetres; fine/tertiary stages and grinding produce even smaller sizes.

Step-by-Step Solution:

Verification / Alternative check:
Flowsheets in quarry/mining texts show ROM → primary jaw/gyratory → 100–300 mm → secondary cone.

Why Other Options Are Wrong:

• Secondary/fine/tertiary/ultrafine: handle much smaller feeds and deliver finer products.

Common Pitfalls:
Judging by reduction ratio alone; absolute size ranges are more informative for stage naming.

Final Answer:
Primary