Sieving of Rubber Crumb

Once the rubber has been granulated, the next step is usually to sieve it into products that have well-defined particle sizes and particle size distributions. This operation confers the dual benefit of enabling a producer to deliver consistent high-quality material to a customer who has developed and optimised a process (e.g., a devulcanisation process), and enabling the provision of different grades of material, helping to ensure that the potential number of end-uses is not restricted. 

Sieved material will normally be sold by specifying a property such as the amount of material (in weight percent) that is retained on a particular set of sieves. For example, a rubber crumb product that had been produced from truck tyre treads could be sold as a 40 mesh material , in which nothing had been retained on a 25 mesh sieve (0.60 mm) and no more than 3% had been retained on a 35 mesh sieve (0.425 mm). In other words, at least 97% of the product had a particle size of less than 35 mesh (0.425 mm). 

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