Coldstream process

Typical examples, which will be discussed in more detail below, are the zinc process, or the Coldstream process for reclamation of cemented carbide scrap, and the oxidation and subsequent reduction of tungsten heavy metal turnings or thoriated tungsten (see Table 11.3). 

Coldstream Process [11.7] (see the flow sheet Fig. 11.5). This process is a mechanical comminution and employs air blasts to accelerate particles against a target with sufficient energy to cause fracture (particle velocities near Mach 2). The air is cooled by expansion from the nozzles, protecting the scrap from oxidation. After screening or air classification, oversize material is recycled. 

Coldstream A process for recycling cemented carbides by heating them to 1,700°C, cooling in nitrogen gas, and blowing them at high speed against a carbide plate. 

A method combining the two above-described processes is one in which zinc infiltration is followed by Coldstream crushing with a final zinc distillation step. 

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