Cryogenic Fine Grinding of Rubber from Used Tires
Superfine powdered rubber can be manufactured efficiently using a cryogenic process. Liquid nitrogen is employed to cool the feed granules below their glass transition temperature before they are pulverized with counter-rotating pin mills. The fineness and throughput are determined by the impact speed from the pin mill and nitrogen metering unit as shown below. A complex product and nitrogen feeder in combination with specially designed screw cooler are of high importance for the efficiency of the system.
Other prerequisites are the right choice of screening technology and the use of suitable screening aids. The amount of coarse material to be returned for final grinding can thus be minimized, helping to increase the grinding performance and reduce the LN2 consumption. Selection of the construction materials plays a decisive role not only because of the abrasive fillers contained in the product, but also because of the extremely low temperature. We have been delivering cryogenic grinding systems with continually optimized process and control technology for many decades now.
Communition of old tires
Alpine Universal shredders make short work of entire car and truck tires in one pass with no preliminary comminution and no debeading necessary. Cost intensive pretreatment of the tires before being fed to the UZ is not needed. Even with heavy-duty truck tires, no de-beading or separation into tire segments is necessary. Both the 40/125 UZ and the 50/200 UZ are capable of processing entire tires, it is does not matter whether the tires are old and bald or production rejects still containing a large amount of rubber.
The UZ shredder is usually used to produce tire chips approximately the size of the palm of the hand. In this form, the shredded tire chips are easy to handle and are suitable for use as additional or substitute fuel or as feed material that can be metered to a downstream recycling system for further recycling into rubber powder.