Shaykh Ibn Uthaymeen was asked the following question:
Question: There are machines that shred papers. Is it allowed to shred a mushaf using it?
If the letters do not remain after shredding, the that is allowed.
[Kanz uth-Thameen Fi Su’alaat Ibn Saneed no. 773 pg. 177]
Faisal Ibn Abdul Qaadir Ibn Hassan