[Cob] Making lime

[Mike Creedy]

I need lime to use on my dome. Having done some research, it seems that a high calcium lime is the way to go. Not to get into the lime in the market place, perhaps it would be useful to make some from sea shells. So I collected about a ton of clean oyster shells, washed and stored them.
I have a rocket heater under construction and can try keep the temp. around 860 degrees C. (Hopefully). Have a pyrometer to monitor.
In days gone by...... Back in the land of my fathers... They burned in "ricks" as you may well know. This burn lasted more than 24 hrs. ? My question is...
Using the smaller quantities (to start with, only 30 gal. drum), how long should I fire to drive off the CO2 and gasses and if it is under fired, can I re-fire the shells that are under fired?
Efficiency of the firing probably has a lot to do with the old time firing for many hours, so basically I would like to know about the re-firing really. Perhaps fire for say 4 hrs and check. If it under-fired it can be used for Tabby mortar? 
Hopefully there's some experience out there which will point in the right direction.
Best regards
Mike



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