You may find useful to check my posts on calcination of calcium carbonate based materials containing iron, elsewhere at this forum: https://www.researchgate.net/post/How_would_the_addition_of_metallic_iron_to_a_sample_of_CaCO3_effect_the_TGA_and_DSC_curves_of_CaCO3
About pelletizing CaO powder; cf. my post at: https://www.researchgate.net/post/which_binder_can_be_used_for_making_pellets_of_snail_shell_based_CaO_powder_and_what_will_b_ethe_method_of_it