Dear Friends
I am bringing to mind that these high temperatures and the presence of at least two fluxes were discussed when we were looking at making ceramic stove components. The same principles apply: if there are fluxes (CL, K) in the clay (ash) Si melts at a lower temperature. Alex found to his dismay this is pretty easy to do with a large scale grass burner. Roger Samson, to his credit, found out how to get the Cl and K out of the grass and dramatically reduce the problem. When we speak of 'char' and at the same time 'biomass' and 'wood', it would do us well to keep in mind the very different result obtained when heating them to 900-950 C. One is going to produce fused ash immediately and the other is hardly going to produce any at all. With ceramics, it is common to add K to reduce the melting temperature. It seems that with combustion, we want it out because of the problems caused. Regards Crispin +++++ Paul, Attached is minimalist, two points, graph showing potassium volatility beginning at 400C with a ~37% loss at 800C. Courtesy of Preto and Hrbek; <http://www.biochar.ca/files/Can%20Biochar%20Initiative%20Preto%20Dec08.pdf> http://www.biochar.ca/files/Can%20Biochar%20Initiative%20Preto%20Dec08.pdf Alex
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