Q1: Which of the following is used for primary crushing of very hard lumpy materials ?

ANS:B - Gyratory crusher

The gyratory crusher is typically used for the primary crushing of very hard lumpy materials.

Explanation:

• Gyratory Crusher: This type of crusher consists of a concave surface and a conical head, usually lined with manganese steel, and operates by gyrating within a stationary bowl-like cavity. It is designed to handle large feed sizes and is ideal for crushing hard and abrasive materials.
• Primary Crushing: Gyratory crushers are commonly used for primary crushing operations where large rocks and hard lumps of material need to be reduced to manageable sizes.
• Toothed Roll Crusher: Used for secondary or tertiary crushing, especially for softer materials or when a finer product size is required.
• Ball Mill and Tube Mill: These are grinding equipment used for reducing particle size through impact and attrition, respectively, rather than for primary crushing of lumpy materials.