Slurries flocculated clay

Originally designed for the continuous filtration of conditioned sewage sludges, as were most of the filter belt presses available, the Manor Tower press is increa singly used for the treatment of paper mill sludge, coal, or flocculated clay slurries. 

In particular, with fluids such as flocculated clay slurries, which may have very high apparent viscosity at low shear rates, the fact that they are shear thinning enables us to pump them and convey them relatively easily by pipeline because of the high rates of shear applied by the fast spinning impeller of a centrifugal pump and the shear that they experience at the pipe wall (and another phenomena known as wall slip that also reduces the viscosity at the pipe wall). 

Polyacrylamide, whether charged or not, can be detected by reactions of the amide group (67,68) however, a number of substances can interfere with the determination. If the molecular weight is high enough, flocculation of a standard slurry of clay or other substrate is a sensitive method for detecting low levels of polyacrylamide (69). Once polymers are adsorbed on a surface, many of these methods caimot be used. One exception is the use of a labeled polymer. 

Some product is sold in slurry which is a convenient form since it eliminates dust, saves energy, and lowers the cost. The industries which are frequent users of such product are paper and paints. Many other applications require material to be in a powder form, therefore the sluny is flocculated, concentrated (filter presses), and dried. Several dryer types are used such as rotary, tray, fluidized bed process or spray. The clay may be pulverized after some of these drying process depending requirements. Figure 2.34 shows the morphology of kaolin. A typical platy structure is clearly displayed on this photograph. 

To quantify the effect of adding a flocculant to a slurry of inorganic sUty clay soil (in this case a clay of low plasticity with a CL-designation), the pillow test method was... 

Figure 21.6 Effect of flocculant additives on silty clay (CL) soil slurry top of pillow was at 30 cm (authors).

It has been reported previously that coagulation and flocculation have been employed with various degree of success in treating slimes or slurries left behind by mining activities 11,2). Both inorganic electrolyte and synthetic polymer are used Jointly to effect destabilization of these slurries. Natural products such as corn starch and hydrolysed Cassava have also been successfully empolyed in the flocculation of tar sand tailings [31. However in our search for an effective flocculant for tin tailings sluny, essentially a stable dispersion of clay minerals, we have not had much success with any of the commercial... 

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