A FIND OF CO IN THE GASES RELEASED FROM “YOSHIKAWAITE” AND HYDROMAGNESITE DURING THERMAL DECOMPOSITION

Unusually high content of CO gas was detected by gas chromatography, non-dispersive infrared absorption and Kitagawa's gas detector-tube in the gases released during thermal decomposition from “yoshikawaite” and hydromagnesite of Yoshikawa, Aichi Prefecture, Japan. Release of CO was proved to start already around 230°C for “yoshikawaite” and 280°C for hydromagnesite, accompanying CO2, from the results of gas analyses at various temperatures. The maximum values of CO were found around 520 and 505°C, respectively. The DTA-TG patterns indicate that only about 65% of the whole amount of water for “yoshikawaite” are released by 230°C and 40% of that for hydromagnesite by 280°C. Judging from the gas-releasing patterns and the DTA-TG patterns for these minerals, CO2 is released by two steps: one is assigned to the endotherm around 430°C and the other to the coupled endotherm around 520°C accompanying a large amount of CO.