水熱処理による風化花こう岩微粒物の精製

Abstract

The fine particles in weathered granite were refined by hydrothermal method in order to utilize them as pottery clay.Feldspar and vermiculite included in weathered granite were altered into kaolin mineral using 0.14mol/l hydrochloric acid adding aluminum chloride under the hydrothermal condition at 200°C. However, the values of pyrometric cone number and the whiteness of the refined samples were lower than that of the common pottery clay.The concentration by HGMS (high gradient magnetic separator) using the fine particles are hydrothermally altered. The whiteness of the treated samples were improved, however, total yield of the refined products from the fine particles in weathered granite were low in the range of 27.8 to 48.7 wt%. Then two stages of hydrothermal treatment were performed. The first stage is to extract ferrous ions from the fine particles using 6 mol/l hydrochloric acid, and the second stage is that the treated fine particles is altered into kaolin mineral under the previous hydrothermal conditions. In addition to increasing the total yield of the refined products more than 60 wt%, the values of pyrometric cone number and the whiteness of the treated samples were improved similar to those of the common pottery clay.