STUDIES OF THE WHITE CLAY IN THE SOUTH KYUSHU : REPORT 10. THE CHANGE OF THE STRUCTURE OF HIWAKI DIATOMACEOUS EARTH BY CALCINATION

THE STUDY OF HIWAKI DIATOMACEOUS EARTH. Diatomaceous earth is used in many ways in the field of industry important resources. Much diatomaoeous earth is found in Kagoshima prefecture and Hiwaki diatomaceous earth is especially of great value industrially as its Purity is high and its colour is white. The author examined its character by adding NaCl, Na_2CO_3, and NH_4Cl to it as additive and calcinating it up to 700°C, 900°C 1000°C and 1100°C. At 700°C, ferrate which in contained as impurity in it can not be removed, but at 1100°C this ferrate tends to be removed. But this removal is not complete. The growth of particle is most considerable when NaCl is added, put in case of the particle of more than 10μ the growth is not observed. The resistibility aginst acid, a1kali and water is greater in proportion to the temperature when diatomaceaus earth is calcinated. When the clay is used as filter matenial, it must be calcinated up to over 1200°C. In the study of X-ray the growth of quartz is also observed, and in propartion to the raising up of the temperature for calcinating quartz is observed to be change into cristobalite