Waste materials can be separated by exploiting the coldness of liquid nitrogen. Cryogenic grinding can achieve a very fine level of grind as most hardy materials tend to become brittle when cooled with liquid nitrogen.
To produce crumb rubber, it is necessary to reduce the size of the tire shred or chip. This is accomplished by techniques called cryogenic grinding. Cryogenic processing refers to the use of liquid nitrogen (−196°C) to freeze tire chips prior to size reduction. The rubber is immersed in liquid nitrogen to reduce the temperature of the tire chip. The cooled rubber is then ground in an impact-type reduction device.