INHIBITION OF THE RELEASE OF ALKALI METALS FROM COAL DURING HEAT TREATMENT WITH THE ADDITION OF CLAY MINERAL

摘要

We attempt to prevent the release of sodium and potassium during pyrolysis and CO_2 gasification of low-rank coals using clay minerals. Although the release behaviors of alkali metals were almost the same for different coal species, the amounts of alkali metals released differed. The release extent of alkali species from Yallourn coal was higher than that from Barau coal during heat treatments. With the addition of clay minerals, the release of alkali metals was inhibited. In particular, alkali metal release was effectively inhibited during gasification. The inhibition of both the releases of sodium and potassium could be sufficient with the addition of 10 wt% kaolinite sample during the heat treatment, while the inhibition of the release of alkali metals with the addition of 10 wt% pyrophyllite sample was not confirmed. As a result, kaolinite could be used to inhibit alkali metal release from coal during coal conversion.