Netzsch Trockenmahltechnik, Hanau, Germany – continuing with the theme of cryogenic grinding (see previous news item) – has optimised the cryogenic grinding process, also known as cold grinding, based on its well-known CONDUX® impact mill. This novel patent-pending method combines all processes, from cooling of the raw material to grinding and inline screening in an inert gas loop system.

 

After the grinding process, nitrogen enters the screening plant with the input of the material being ground. In this way an inert, dry atmosphere is created within a short period by the circulation of the process gas in the screen loop. This helps ensure efficient, trouble-free inline screening and inline packing without delaying the process, as the freshly ground product can be fed directly into the screening machine directly after the separating unit (filter and/or cyclone). For this purpose, screening machines with air jet cleaning are used. The screening decks of these machines are pneumatically cleaned using the process gas of the integrated gas circulating blower. The process gas is fed below the screen inserts where it causes a fluidisation of the grinding product, similar to that caused by an air jet screen. The target temperature of the ground product is around 15- 25°C, depending on the season and the atmospheric conditions, in order to eliminate any condensation. www.netzsch-grinding.com 

 

 

CONDUX impack mill with connected screening machine for cryogenic grinding in an inert closed-loop gas system