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.
