カオリン中のアルミニウムの迅速分析法

概要

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Aluminum in kaolin was successfully determined by chelatometric method. Following procedure was proposed. Kaolin is decomposed by heatiag in a Pt crucible with a mixture of hydrofluoric and sulfuric acids. The residue is heated with a saturated boric acid solution to dryness to expel fluoride as boron trifluoride and then it is heated with methyl alcohol to dryness again on a water bath to drive off boron as methyl borate. The residue is dissolved in sulfuric acid(1+5) and then the solvent extraction is carried out with chloroform and DDC for iron and manganese, and with chloroform and cupferron for titanium, respectively. Aluminum in the residual solution is successessfully determined by chelatometric method. An excess amount of 0.01 M CyDTA is added to the solution and the solution is back-titrated by 0.01 M lead solution using XO as an indicator. The end point is indicated by the color change from yellow to red-violet. By this method, the analysis is carried out successfully for about half the time of it needed in the gravimetric method. This method offers sufficient accuracy and precision. An example of the analysis was as follows; H_2O : 10.8%, SiO_2 : 45.8%. Al_2O_3 : 38.9%. Fe_2O_3 : 0.65%, TiO_2 : 0.07%, MnO : 0.02%, CaO : 0.02%, MgO : 0.08%, Na_2O : 2.0%; K_2O : 2.3%.
1977-02-10