Tetrahedrite--------"That's all well and good, you can use Ca2+ to remove carbonate from water and therefore CO2 from the air. But you have an enormous problem, where do you get the Ca2+ from? Nearly all the easily processable calcium used in industry is obtained from limestone. To obtain the Ca2+ from the limestone you need to release CO2, and thus you're back where you started."------
---------"Calcium carbonate minus carbon dioxide is either calcium oxide or lime water - where do you take them from?"
Borek-----------
i think you have an idea of how i transform CO2 to calcium carbonate. the question is the source of your calcium. double displacements could create CaOH in the labaratory. and the rest is highschool chemistry.
ps. u just need all the calcium in the world w/ a catch do not produce CaO or CaOH if ur by product is CO2 it just destroy the cause. After that the calcium carbonate is collected. And its all up to u to find some uses for that. Maybe bury them or build a your own pyramid. Well pyramids in egypt are built with limestone u know.