The investigations were carried with aluminous materials in nature, such as bauxite, diasporic bauxite, aluminous shale, nepheline-syenite, and sericite-schist, etc. regarding the relations between the range of clinkering temperature or the extraction percentage of Al2O3 or Na2O and the proportioning ratio of the raw materials, while in the previous paper with the various artificial ores having different ratio SiO2 or Fe2O3 to Al2O3. It was recognized that the range of clinkering temperature and extraction percentage, being indifferent of the states of the oxids in the ores, depended only on the proportions of the oxides in the raw mixes which were influenced only by the SiO2 content, not by Fe2O3 in the ore and the following proportions were best adapted to treatment of every ore;
i) Na2O to be added is 1 mol for each mol of Fe2O2, and 0.7-0.8 mol for each mol of Al2O3.
ii) CaO to be added varies from 1 to 2 mols for each mol of the sum of SiO2 and uncombined Al2O3 (with Na2O) as the content of SiO2 in the ore, that is, higher the SiO2 content, higher molecular ratio necessary.
In chapter II, various calcium-compounds such as calcium-silicates, calcium-alumino silicates and calcium-ferrites were synthesized and their behaviors with Na2CO3 and NaAlO2 solutions examined for the purpose of using them to solve the mechanism of the reaction in the leaching process and to suppose what kinds of calcium-compounds would be formed in the clinker.
The results of tests indicated that low basic calcium-silicates (CaOSiO2, 3CaO2SiO2), calcium-ferrite (CaOFe2O3), anorthite and gehlenite were very stable in those solutions, but high basic calcium-silicates (3CaOSiO2, 2CaOSiO2) and calcium-ferrite (2CaOFe2O3) easily decomposed by them.
It was found that dicalcium-silicate (2CaOSiO2), contained more or less in the clinker without exception, being decomposed by NaAlO2 solution, carried down the dissolved Al2O3 into the insoluble compounds, to which I ascribed the formula 3CaOAl2O3xH2O, CaOxAl2O3ySiO2nH2O. This behavior of dicalcium-silicate with NaAlO2 solution is important for explanation of the loss of Al2O3 caused during leaching process.
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