What are the different colors in a fire. Yellow is sulfur and orange is........?

Question

I am burning off waste methane and I read somewhere that the different colors in a blue flame are different elements that reside in the digester. If anyone has an idea please advise.

Answer 1

Wikipedia has a list of elements and their flame colors.  

But be careful that you are working with a non-luminous flame.   A luminous flame will produce yellow, red, and orange light through blackbody radiation that is independent of elemental composition.  If you are burning any sooty compound or burning with not enough oxygen, then you will get soot and it will glow yellow and orange and have nothing to do with sulfur or potassium or whatever.  I would say that's likely if you're burning a methane flame.  You have to mix air in with the gas (like in a torch or bunsen burner) to get the classic blue flame, which is a nonluminous hydrocarbon flame color.  Then, any additional colors may be due to other elements.