Kinetic aspects of hindered sedimentation of Ocher suspension in the presence of binary compositions of ionic polyacrylamide flocculants

Kinetics of hindered sedimentation of an ocher suspension is studied in the presence of binary polyacrylamide flocculants, anionic (A) and cationic (C ). The use of two types of measuring cylinders with working volumes of 100 and 2000 cm(3) allowed us to reliably control both the kinetics of floccula tion and sediment compaction. The dependence of flocculation parameters on procedure of addition of A and C components was found, the principle of add itivity of A and C contributions to a total effect is thus violated. It is noted that the addition of very small amounts of polyacrylamide flocculants leads to marked changes in both structural parameters of sediments and com pression constant. The dependences of viscosity on the concentration and co mposition of a mixture and electrokinetic potential on polyacrylamide flocc ulant concentration are examined to explain the specific features of floccu lation and sediment compression in the presence of binary A + C composition s. Upon the addition of cationic polyacrylamide flocculants to the system, the reversal of charge at ocher particles occurs within the particular conc entration range of the cationic flocculant.