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The paper presents a study of the pozzolanic reaction kinetics between calcium hydroxide and sugar cane bagasse ash (SCBAB) from the boiler of a sugar factory. A pozzolanic activity method (conductometric method) based on measurement of the electrical conductivity of the SCBAB/calcium hydroxide solution as the reaction proceeds is applied and the kinetic parameters are then quantified by applying a kinetic-diffusive model to the process. The kinetic parameters that characterise the process (in particular, the reaction rate constant and the free energy of activation) were determined with relative accuracy in the fitting process of the model. The pozzolanic activity is quantitatively evaluated according to the obtained values of the kinetic parameters. Other experimental techniques, such as X-ray diffraction and scanning electron microscopy, are also employed. Comparison with another bagasse ash calcined under controlled conditions in the laboratory is carried out. The results show the good pozzolanic properties of the SCBAB from the boiler of the sugar factory. [ABSTRACT FROM AUTHOR]

In Cuba important chromium mineral reserves exist. Within the Cuban chromites deposits Merceditas for its levels and exploitation stands out. In this work the mineralogical characterization of chromite concentrated belonging to the deposit previously mentioned is presented and its possible use as carrying silicon and chromium source in diffusive process is valued. The determination of the chemical composition of the concentrate was carried out by means of the gravimetric and volumetric methods, whereas for the identification of its phases techniques of Infrared and Mössbauer Spectroscopies, and X-Rays diffraction were used. Additionally the statistical parameters of the grain sized distribution from a sifted process were determined. It is established from its chemical composition, that the concentrate is refractory and that the chromium, iron, aluminum, magnesium, silicon and calcium appear in different proportions. The chromium and silicon content in the concentrate and its relation are similar to the previous reports for the application from diffusive processes of simultaneous saturation with both elements, whereas the levels of aluminum and magnesium combined with oxygen guarantee the refractivity of mixtures. Also, it was corroborated that the mineralogical phases were chromopicotite, antigorite and chlorite and it was concluded that its main phase is the chromopicotite. Finally, it was established that it has an average diameter of 513 µm, obliquity of a 0.93 and a dispersion of 1.83. [ABSTRACT FROM AUTHOR]