Black particles

I aboseved in Black particle in blend after blending . In whole ipc then what should be action to be taken

find route wet granulation usually black particles r produced by oscillating granulator if seals r worn out.
Action depend on size n qty of particles if some r present then visually can be picked.

If the no.of particles is in large nos.what will we do? And what is the impact of the black particles on product.

Appearance is a critical quality attribute. If the appearance of the product is deviant from that mentioned in dossier, it might be reason for rejection.
Impact of particles on product (product safety/product efficacy) depends also on the nature of the particles and is a question for the QP and/or Pharmacovigilance department.

If you can, I would suggest taking a sample of the black specs and see what they are. Then you can look at why the appeared. From there you can see if the batch can be saved.

Which type of materials can cause black particle? Is there any specific type of material like magnesium etc.?