Hello, depends from future use, if you interested in volatile compounds too, so you cant use open air ashing or a kiln. If volatile compounds not in interest you can use both method that you mentioned.

I read that if one uses open air burning, what you get is carbonised ash (which is not completely burnt to real ash)?

And that if I want to get complete ash, then I must use a kiln which does not allow air inside?

Sir, what is your opinion please?

Regards.

You can get the RHA by first gasifying rice husk and then allow it the gasifier to be completely burnt to produce ash.

Thanks alot.