Chemistry of soil minerals. Part XIV. Action of some basic solutions on metakaolinite and kaolinite

Some reactions have been studied at 80 °C between aqueous alkaline media and metakaolinite with and without added silica. The bases employed were TlOH, Ba(OH)2+ TlOH, Ba(OH)2+ LiOH, and Ba(OH)2+ NaOH. A similar study was made of kaolinite with aqueous Ba(OH)2+ LiOH. Kaolinite was less reactive than metakaolinite and yielded different reaction products. Non-zeolites formed included a barium silicate hydrate, barium aluminate, and a phase similar to cymrite. Three unidentified Tl-bearing species were also formed in minor yields. Zeolites of the following kinds were grown: those of edingtonite type containing Ba2++ Tl+ or Ba2++ Li+; variants of zeolite L, containing Ba2++ Tl+, Ba2++ Li+, or Ba2++ Na+; harmotome- or phillipsite-types containing Ba2++ Li+ or Ba2++ Na+; and zeolites like gismondite with Ba2++ Na+, like gmelinite and containing Ba2++ Na+, and like yugawaralite containing Ba2++ Li+. A lithium-bearing zeolite with no natural counterpart and in which the cations were Ba2++ Li+ was also grown.Properties of a number of these phases have been examined. From the present and earlier work, it appears that an important factor in promoting growth of chabazite-, edingtonite-, and phillipsite-type zeolites and of zeolite L is the presence of a sufficient amount of at least one of the cations K+ or Ba2+. On the other hand a sodic environment favours gismondite-, gmelinite-, and faujasite-type zeolites, and Linde A.