Using turbulent pipe flow to study the factors affecting polymer-bridging flocculation of mineral systems

Characterization of Multiple Hindered Settling Regimes in Aggregated Mineral Suspensions

“…The scale of the challenge is further complicated by the fact that the size, shape and effective density of these aggregates in many industrial effluents are often poorly characterised 16 and can be highly dependent on the chemistry of the continuous phase 10 and on the shear environment of the suspension [17][18][19] . There is also evidence that larger aggregates are more fractal and less dense than smaller aggregates, due to the incorporation of large ratios of intra-aggregate fluid 20,21 , with the largest aggregates (>100 µm) often only marginally denser than the continuous phase [21][22][23] .…”

Bridging Flocculation by Polymers

“…In general, the results of these investigations are consistent with those of batch tests with continuous or incremental addition to a stirred tank. In particular, tests where multistage polymer injection was used, i.e., incremental addition, showed enhanced performance both with 22,49) and without 48) mixer elements.…”

“…Sufficiently high turbulence to ensure high polymer-particle and particle-particle collision frequencies can readily be achieved while its role in floc degradation may be less severe than that of the impeller in a stirred tank. Experimental studies of flocculation in turbulent pipe flow [46][47][48] have shown that rapid floc growth to a maximum size took place over a short time (less than 10 seconds, (corresponding to 50 -100 pipe diameters, for the system investigated) and was followed by a continuous decrease in size with continued flow. The initial growth rate and the subsequent reduction in size were found to increase while the maximum floc size decreased with increasing Reynolds number.…”

Aggregation and breakup of acrylic latex particles inside millimetric scale reactors

“…[20] applied the concept of turbulent diffusion and obtained an aggregation kernel similar in structure (i.e. proportional to G av · (r i + r j ) 3 ) to the previous ones, however the constant was somewhat higher (13.8 compared with 4/3). Delichatchos and Probstein [21] proposed an approach by using the concept of mean free path in analogy with the kinetic theory of gases.…”

“…As mentioned by Owen et al [3], coagulation/flocculation is frequently studied in batch vessels, and extensive experimental results in stirred tanks can easily be found [4][5][6][7][8][9][10]. However, in stirred tanks, dead volumes, inhomogeneous mixing and poor control of the local hydrodynamics can lead to unexpected coagulation issues such as fouling and broad cluster size distributions.…”