Quality Сontrol of Metakaolin by the Method of Spectroscopy in the Near Infrared Region of the Spectrum

The express-method for control of kaolin calcination in terms of spectra of diffusion reflection in UV-VIS-NIR-field is proposed. The stages and temperature ranges of the heat treatment within the range of 600–1000оC of the transformation of kaolinite to metakaolinite in terms of changes in the spectrum profile and the square of the characteristic bands of OH and AI-OH centers in the NIR field are determined. It is established that the greatest decrease in the absorption area of the OH center and the disappearance of structuring of OH and AI-OH centers is connected with almost complete dehydroxylation of kaolinite. Structural disordering of metakaolinite is most clearly interconnected with the reduction of the band square of AI-OH center. The advantage of measuring the spectra of diffusion reflection in the near infrared area comparing with infrared transmission spectra is shown: there is no need for sample preparation, the measurement is performed in situ and in on-line regime.

V.A. RASSULOV¹, Candidate of Sciences (Geology and Mineralogy);
R.A. PLATOVA², Candidate of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.),
Yu.T. PLATOV², Doctor of Sciences (Engineering) 

¹ All-Russian Scientific-Research Institute of Mineral Resources named after N.M. Fedorovsky (31, Staromonetny per., 119017, Moscow, Russian Federation) 
² Plekhanov Russian University of Economics (36, Stremyanny Lane, 119017, Moscow, Russian Federation)

1. Rakhimov R.Z., Rakhimova N.R., Gayfullin A.R., Stoyanov O.V. Influence of additive in a portlandtsement of the calcinated and ground polymineral clay containing kaolinite on durability of a cement stone. Vestnik tekhnologicheskogo universiteta. 2015. Vol. 18. No. 5, pp. 80–83. (In Russian). 

2. Platova R.A., Argynbaev T.M., Stafeeva Z.V. Influence of Dispersion of Kaolin from Zhuravliny Log Deposit on Pozzolan Activity of Metakaolin. Stroitel’nye Materialy [Construction Materials]. 2012. No. 2, pp. 75–80. (In Russian). 

3. Platova R.A., Platov Yu.T., Argynbaev T.M., Stafeeva Z.V. White Metakaolin: Factors Influencing on Coloring and Evaluating Methods. Stroitel’nye Materialy [Construction Materials]. 2015. No. 6, pp. 55–60. (In Russian). 

4. Platova R.A., Rassulov V.A., Platov Yu.T., Argynbaev T.M., Stafeeva Z.V. Luminescence Control of Pozzolanic Activity of Metakaolin. Stroitel’nye Materialy [Construction Materials]. 2016. No. 6, pp. 67–72. (In Russian). 

5. Guatame-Garcia L.А., Buxton М. Visible and infrared reflectance spectroscopy for characterization of iron impurities in calcined kaolin clays. Proceeding of the 2nd International conference on optical characterization of materials. Karlsruhe. 2015, pp. 215–226. 

6. Crowley J.K., Vergo N. Near-infrared reflectance spectra of mixtures of kaolin-group minerals: use in clay mineral studies. Clays and Clay Minerals. 1988. Vol. 36. No. 4 pp. 310–316. 

7. Hunt G.R. Spectral signatures of particulate minerals in the visible and near infrared. Geophysics. 1977. Vol. 42. No. 3, pp. 501–513. 

8. Bergaya F., Dion P., Alcover J.F., Clinard C., Tchoubar D. TEM study of kaolinite thermal decomposition by controlled-rate thermal analysis. Journal of Materials Science. 1996. Vol. 31. No. 19, pp. 5069–5075.