中国産α型セピオライト中の炭酸塩不純物の酸処理

概要

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To purify the α-type sepiolite from Hunan, China with calcite as an impurity mineral, two types of HCl treatments were compared by their chemical composition, BET surface area, crystallite size estimated by Scherrer equation etc. Rheological properties were also measured for the purified sepiolite treated in bench scale. 1) By the simple addition of HCl (treatment-A) without pH control, the calcite content was decreased from 29.5% to 1.7%, whereas the excess silica formed by the damaging of the sepiolite increased from 0% to 4.4%. 2) By the controlled HCl addition at pH 5 (treatment-B), the calcite content was decreased from 29.5% to 2.4%, and the excess silica was increased from 0% to 4.2%. The little differences between the results of the treatment A and B indicated that the thickfibrous α-sepiolite has relatively high resistance against acid and the dissolution of calcite buffered the solution pH. 3) By the pH controlled HCl addition in bench scale (treatment-C), the calcite content was decreased from 36% to 2.9% and the excess silica was increased from 3.2% to 4.0%. An increase in viscocity at low share rate and thixotropy were observed for the slurry with the purified sepiolite, which indicates the applicability of the purified materials for the thixotropic additives.
日本粘土学会の論文
2000-08-10