Eventos Anais de eventos
COBEM 2019
25th International Congress of Mechanical Engineering
THE INFLUENCE OF STORAGE TIME ON THE RHEOLOGY AND PH OF BENTONITE SUSPENSIONS
Submission Author:
Elis Marina Schvan Wendt , PR
Co-Authors:
Elis Marina Schvan Wendt, Leonardo Banaszevski Gomes, Rubens Rosario Fernandes, Admilson Franco
Presenter: Elis Marina Schvan Wendt
doi://10.26678/ABCM.COBEM2019.COB2019-1252
Abstract
Bentonite clay particles swell due to adsorption of water, forming a colloidal suspension and exhibiting thixotropic and yield stress characteristics. The American Petroleum Institute (API Specification 13A 2007) recommends storing formulated bentonite suspensions for at least 16 h before performing rheology experiments, which is not sufficient for complete stabilization of the material. The steady-state shear stress at constant shear rate ranging from 100 to 0.1 s-1 were evaluated for 7.42 and 9.11 wt% suspensions over 6 weeks after sample preparation. Different homogenization procedures were also evaluated. The steady-state shear stress considerably changed over the first week due to swelling of the particles. However, full stabilization of the shear stresses was only observed after four weeks. This indicates that the ageing time suggested by the American Petroleum Institute is not sufficient to obtain stable samples. The intense changes in viscosity over the first week after sample preparation should be further investigated. In addition, the stability of the samples for longer storage times should also be assessed. The pH of the samples decreased from approximately 9.8 to approximately 8.8 over six weeks. The most intense variation of the pH occurs in the first week, indicating that the pH can be used as an indicator of sample stability.
Keywords
bentonite suspensions, storage time, Rheology, pH, preparation methodology
