Question

How is liquid nitrogen used for recovery of steel from old cars?

Answer 1

Nitrogen is the main constituent of air. It is chemically inert under normal conditions. It is colorless, odorless and tasteless gas. It is not flammable. Liquid nitrogen is a liquefied form of the nitrogen gas. It has the same chemical formula as nitrogen gas- ${N_2}$.

Complete step by step answer:
We know steel is an alloy made up of iron and carbon and other such elements as copper, manganese or chromium. It is used in making parts of cars. So when old cars are brought to recycle the steel used in the making of parts is recovered from it.
The steel is made up of metals and we know that metals are brittle and hard at low temperature. Liquid nitrogen has following properties-
It has a cold temperature and has low reactivity.
It boils at$77K$.
It is stored in special insulated containers that are vented for preventing the pressure buildup.
Liquid nitrogen is sprayed over the parts and it breaks the steel as steel is brittle and hard. It breaks and then it is recovered from old cars.

Note:
Liquid nitrogen is used in following ways-
-In freezing and transporting the food products.
-In cryopreservation of eggs and genetic samples.
-As a coolant for superconductors, vacuum pumps and other materials.
-In cryotherapy for removing the skin abnormalities.
-In shielding materials from oxygen exposure.
-In cooling materials for easier machining and fracturing.