赤泥の2, 3の表面特性

抄録

Seven red mud samples were studied and characterized to elucidate their surface state using extensive chemical and spectroscopic techniques. The result obtained are summarized as follows:
1) Liquid: solid ratio of red mud varied between 30-70 weight%.
2) pH values of supernatant solutions varies between pH=12-13. Acid-base titration of the supernatant solutions gave end point of pH=9.
3) Cyclosizer classifications showed that red mud is made of super fine particles, 70% of which were smaller than 11.3 micrometers.
4) Emission spectrographic analysis indicates the presence of the following elements in red muds: Fe, Al, Si, Ca, Mg, Na, and Ti as major elements; Cr, Mn, V, and Zr as minor elements.
5) X-ray diffraction analysis allows the following mineral species to be “definitely identified” in red muds: Hematite, Boehmite, Calcite. Tentatively identified mineral species are: Rutile (or Anatase), Jarosite, Christobalite, Siderite, Kroehnkite, Goethite, Azurite, Graphite, Hydrogrossilarite, Perovskite, Tridymite, Ulvospinel, and Concrinite.
6) EPMA shows that Titanium is almost homogenenously distributed in simple grains and also Titanium occurs together with Fe and Ca in all red muds.
7) X-ray and EPMA data confirm the universal presence of Ti, Ca, and Al while Fe is conspicuously absent from one sample out of seven.
8) It is established that Ti is associated with Fe and Ca rather than Al and exists in structures, such as simple Rutile (or Anatase) and Ilmenite, or complex grains of Perovskite or Ulvospinel.
9) IR spectra of red muds identified the existence of the vibration of adsorbed water, Si-O and OH of Boehmite, Calcite and metal-oxide.
10) DTA-Tg analysis showed dehydration of adsorbed water, dehydroxylation of red muds, and decomposition of Calcite in the endothermic pattern.
11) Titanium on red muds was also identified by the binding energy of 2p_1/2 and 2p_3/2 of Ti by ESCA.
12) The isoelectric point of red muds is located at about pH=9, being influenced by Hematite or Calcite.