Charcoal stain removal from white duvet covet

Ella_fella

So the job I do involves coal dust being used in the process, annoyingly it seems at some point I've come home with some of this coal dust on my clothes and transferred it to my white duvet cover.
Have tried washing it as per the manufacturers guidelines however you can still see the coal dust stains but they are less pronounced (appear light grey instead of black but still noticeable)
Has anyone got any advice please how to get rid of them totally?

GDB2222

No idea, sorry, but if you work with other people perhaps they can suggest something. 

Scotch_Bonnet_

Have you tried soda crystals in the wash or spraying it with a solution called elbow grease? Its available in most pound shops.

koalakoala

Try vanish