Abstract
Solubilities of nitrogen and carbon in molten CaO-Al2O3 slags were measured to discuss the form of nitrogen. Samples were melted in graphite crucibles and N2-CO gas mixtures were equilibrated with nitrogen and carbon in molten slags. The results obtained are summarized as follows:
(1) It is considered that in the presence of graphite, nitrogen and carbon dissolve in molten slag electrochemically.
(2) The solubilities of nitrogen and carbon decrease with decreasing PN2.
(3) The temperature dependences of solubilities of nitrogen and carbon are represented as follows: log(wt%N)=−23300⁄T+12.9, log(wt%C)=−14000⁄T+0.17(50 wt%CaO-50 wt%Al2O3, PN2=0.92).
(4) The carbon content increases in proportion to the CaO content in the CaO-Al2O3 binary system, while the maximum content of nitrogen was obtained at the composition with nearly 50 wt%CaO.
(5) The correlation was observed between nitrogen and carbon contents in molten slags.
(6) Nitrogen in the CaO-Al2O3 melt exists as CN− and N3− annions, although it remains unclear whether CN22− annion exists in the melt or not.
