Rheological behavior of calcite slurries: Effect of deflocculant addition

In the present work the influence of the addition of some dispersing agents employed for maximizing the solid loading of calcium carbonate concentrated suspensions was investigated. Three commercial deflocculants were used-a sodium stilt of a benzenedisulfonic acid (Tiron), a sodium polyphosphate, and an aurintricarboxylic acid, triamino nium salt (Aluminon). Calcium carbonate aqueolis suspensions were prepared at various solid volume-actions (0.270 to 0.382). Rheological tests were carried out at 25 degrees C by using the rate-controlled coaxial cylinder viscometer Rotovisko-Haake 20, system M5-oscillatory, measuring device SV2P with serrated surfaces. The tests were performed under both continuous and oscillatory flow conditions. The application of rheological techniques permitted highly accurate evalluation of the optimum dosage of the deflocculants, i.e., the critical concentration at which the maximum reduction in viscosity is detected. Generally, Aluminon and sodium polyphosphate behaved as the best dispersing agents for the calcite suspensions studied. i.e.. the showed their optimum dosage at a concentration lower than that of Tiron and provided low viscosity values for the entire concentration range explored.