For primary crushing of very hard, lumpy materials in mineral processing, which crusher is most appropriate to handle the duty at high capacity and large feed sizes?

Introduction / Context:
Primary crushers must accept large lumps of hard ores and deliver a manageable product for secondary crushing or grinding. Selecting the appropriate crusher impacts throughput and downstream energy consumption.

Given Data / Assumptions:

• Material: very hard and lumpy.
• Duty: primary (first-stage) crushing.
• Need: high capacity with large feed opening.

Concept / Approach:
Gyratory crushers provide continuous crushing action with a large gape, ideal for primary reduction of hard rock at high capacities. Toothed rolls are better for moderately hard, friable materials and smaller top sizes. Ball and tube mills are grinders, not primary crushers. Hammer mills suit softer to medium-hard materials and are not preferred for the hardest, very large lumps at primary stage.

Step-by-Step Solution:
Determine duty (primary) and material (very hard, large lumps).Match to equipment with large feed opening and continuous compressive action.Select gyratory crusher.

Verification / Alternative check:
Plant design manuals specify jaw or gyratory for primary hard rock; for very large capacities and consistent feed, gyratory is standard.

Why Other Options Are Wrong:
Toothed roll: limited top size and hardness range.Ball/Tube mill: downstream grinding units.Hammer mill: wear and size constraints for very hard primary lumps.

Common Pitfalls:
Confusing primary and secondary equipment roles.

Final Answer:
Gyratory crusher