| 摘要 |
<p>PURPOSE:To reduce density by heating a pulverized and/or classified volcanic vitreous deposit in hydrochloric acid or sulfuric acid to make the compsn. of the surfaces layers of the grains different from that of the interiors, heat-treating the deposit under specified conditions and carrying out separation or classification. CONSTITUTION:A volcanic vitreous deposit is pulverized and classified into powder of about 5-10mum grain size and powder of about 10-20mum grain size. These powders and an about 2% hydrochloric acid soln. are sealed in a pressure vessel in 1:about 10 ratio, held at about 200 deg.C for about 120hr, cooled, filtered, washed and dried to form surface-treated powder. This powder is heat-treated by heating from room temp. to 900-1,100 deg.C within 1min and holding at 900-1,100 deg.C for several sec and the heat-treated powder is subjected to sink and float separation in water. Floating hyperfine hollow glass spheres of about 5-15mum grain size are obtd. from the powder of about 5-10mum grain size and those of about 10-30mum grain size from the powder of about 10-20mum grain size.</p> |
