A PVC dry-blend, consisting of powdery raw material and additives, is cooled in a combined heating/cooling process by injecting liquid nitrogen. Cooling is more rapid. The N2 withdrawn can be released to the atmos. The liquid N2 can be injected directly into the cooler/mixer in contact with the dry-blend, or may be injected outside the appts., with evapn. of the N2 mist only within the cooler/mixer. The N2 withdrawn from the dry-blend may be at least partly recirculated.
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