JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II MINERAL PROCESSING Previous Question Paper (February - 2024 - R18)

The angle of nip is defined as the angle formed between the two crushing surfaces (such as the faces of two rolls or a jaw and a mantle) at the point where they first make contact with the feed material. It is a critical parameter in size reduction equipment, specifically in roll crushers and jaw crushers.

Mathematically, for a roll crusher, it is the angle between the tangents to the roll surfaces at the points of contact with the particle. If the angle of nip is too large, the particle will not be gripped by the crushing surfaces and will instead slip or be ejected upwards, a phenomenon known as slippage. To ensure the material is drawn into the crushing zone, the angle of nip must be less than twice the angle of friction between the material and the crushing surface.

• Rock: A rock is a naturally occurring, solid aggregate of one or more minerals or mineraloids that forms the Earth's crust. It does not necessarily contain valuable minerals in concentrations that are economically extractable. Example: Granite, which is composed primarily of quartz, feldspar, and mica.
• Ore: An ore is a naturally occurring solid material from which a metal or valuable mineral can be profitably extracted. The classification of a rock as an ore depends on the concentration of the valuable mineral, the cost of extraction, and current market prices. Example: Hematite (Fe₂O₃), which is the primary ore of iron, and Chalcopyrite (CuFeS₂), which is the primary ore of copper.