Selection, Modification, and Purification of Natural and Solidified Clays by a Patented Process: Analysis using ICP-MS and Rietveld

Background: The applications of the clay minerals in the various process industries are still relevant and closely related to their structure and composition. Objective: To study ways of selection, purification and subsequent modification of mineral clays to ensure a specific industrial use, being proposed, developed and applied a separation method of clay fractions called elutriation. Method: A granted process was based on the principle of Stokes' law (BR Patent 102013016298). For this we used four glass columns in series in which were applied a high flow of deionized water, associated with a Venturi device to obtain purified in natura clays. We repeated this procedure adding NaCl to previous solution considering a fixed flux rate. This process enabled selective separation of clays and impurities by size and density. Results: The efficient separation of crystalline phases has been verified qualitatively by both X-Ray Diffraction and Fluorescence. The main phases observed were montmorillonite, kaolinite and quartz. We also applied a quantitative analysis by means of the Rietveld refinement method of clay minerals, elutriated column by column, and also comparing elutriated and non-elutriated in natura samples. Conclusions: Results showed that there was a purification process with increasing montmorillonite phase up to 96% in mass at the same time that was noted the decrease content of the kaolinite and quartz phases. ICP-MS results showed that there was sodium incorporation, especially in the last columns, when using NaCl added to water solution.