Dust on the bottom after adding SMB

[beneq1]

wow, thank you very much for explanation of what's going on. I never would have thought that it is so complex.

I was heating it for about 3h and after it has cooled down, I did that what Geo told me and it went black instantly.
During the heating process, in better the light I noticed that the solution not only dark yellow but (I dont know how to explain it) inside it is brawn. grey/purple was only suspension on the walls of the beaker and dust on the bottom.

Now I need to filter it, collect and dry dust from filter and de-NOx solution?

 

[beneq1]

Thanks you very much for help guys. I got 0,27g gold from it ;/. But next time it will be better I hope.