Low Temperature Experimental Investigation of the Effect of High pH Naoh Solutions on the Opalinus Shale, Switzerland

Abstract

Abstract--Batch reactor experiments were performed at 150~ 175~ and 200~ to determine the effect of high pH NaOH solutions on the mineralogy of the Opalinus shale. In these experiments, the change in solution quench pH at 25~ solution composition, and mineralogy were monitored as a function of time for up to ~40 days. Runs were performed in 50 ml titanium hydrothermal reactor vessels. Each reactor was charged with 0.5-5.0 g of the 80-200 mesh size fraction of Opalinus shale, and 25 ml of solution (0. l and 0.01 M NaOH). The general sequence of reaction products observed under these high pH conditions include first the formation of analcime, followed by vermiculite, and finally Na-rectorite formation.

Low Temperature Experimental Investigation of the Effect of High pH Koh Solutions on the Opalinus Shale, Switzerland

“…In the 150~ and 175~ experiments after ~ 42 and ~ 30 days, respectively, phillipsite, rectorite, and K-feldspar were observed in reaction products. Quench pH values were similar to the results in the 0.1 m Na system (Chermak, 1992).…”

“…The values of siderite and pyrite were derived by estimates using optical mineralogy. The chemical composition of the starting Opalinus shale as determined by XRF is given in Chermak (1992). SEM was used to examine crystal habit and morphology and to aid in confirming reaction products.…”

“…The occurrence and types of these high pH-mineral reactions are discussed in detail in Chermak (1992). Particularly applicable to the present study is the interaction of high pH K dominated cement pore fluids with shales.…”

Impact of a 70 °C temperature on an ordinary Portland cement paste/claystone interface: An in situ experiment

“…noticed in batch tests at high temperature (> 60°C) or under extreme conditions [4,5,8,9]. The same comment applies to tobermorite.…”

“…1, 2, 3] or kaolinite and smectite [e.g. 1]) or claystone [4][5][6][7][8][9] were exposed to an alkaline fluid showed mainly a clay mineral transformation and formation of Calcium Silicate Hydrates (C-S-H) and, at temperatures higher than 80°C, also zeolites [e.g. 2,5,8,9].…”