Thickeners design

There are three types of thickener designs cylindrical, lameUa, and deep cone. The cylindrical design is the most common (Fig. 20). It is also continuous. It comprises a large (up to 200 m dia, 1—7 m deep) cylindrical tank, a shallow conical base (80—140 mm/m), and a central stmeture carrying... 

These unit area values, plotted as a function of the feed concentration, will describe a maximum value that can be used to specify the thickener design unit area for the particular underflow concentration... 

Total reflection X-ray fluorescence spectrometry, 26 435-437 Total sideband suppression (TOSS) technique, 23 741 Total site pinch analysis, 20 751 Total solids flux, in thickener design and scale-up, 22 58... 

ALCOGUM 9639-N is a new sodium polyacrylate thickener designed for use in textile coatings for upholstery. 

Water soluble thickeners, designed specifically for the water based adhesive and latex compounding industries, supplied as frost stable low viscosity high solids dispersions. 

In the screen tests, each coagulant or flocculant is added to the beaker samples of representative slurry or hquor in a dropwise fashion, while the sample is mixed with a spatula, stirrer, or 3-6 jar stirrer mechanism. The amount of coagulant or flocculant required to initiate floe particle formation is noted along with relevant notes as to the size of the floe, capture of fines, resultant liquor clarity, and stabihty of the floe structure. The dosage is typically noted in g/t solids if the sample is primarily solids (thickener design), or in mg/L liquor if the sample is primarily for clarification and the solids concentration is low. 

Eor even higher solid concentrations where the particles are in contact with each other, free settling phenomena is replaced by compression or consolidation. The Coe and Clevenger-type design methods are not sufficient. Sediment height and consolidation effect need to be included in the thickener design (Tiller and Tamg 1995). 

If a thickener designed for a certain capacity and underflow concentration is operated at lower capacity, the underflow concentration could be increased by using a less steep operating line, and the critical concentration would be slightly increased. 

All the data to produce a batch flux curve, i.e. G-C, which is inqjortant design information for continuous thickener design procedures, can be obtained in the following... 

Fitch, B. 1975. Current theory and thickening design. Parts 1-3. Filtration and Separation 12 355 59,480-i88,636-638. 

Fitch E.B., 1975. Current theory and thickener design 3 - Design procedures, Fibr. Sep., 12,... 

Hasset N.J., 1965. Mechanisms of thickening and thickener design, Trans IMM, 74, 627-656. 

Moncrieff A.G., 1964. Theory of thickener design based on batch sedimentation tests, Trans IMM, 73, 729-759. 

Two American thickener designs are based on feeding the slurry under the settling sohds interface in a way similar to the sludge blanket clarifiers described in the previous section. They also have other features, all designed to accelerate the flocculation and increase the capacity. 

As shown in Fig. 10, there are four zones existing in a thickener a clarifieation zone, a feed zone, a transition zone, and a compression zone. As solids thicken, a critical concentration will be reached. This concentration would affect the passage of solids to the underflow, causing a buildup in the compression zone thickness. The thickener design and operation must prevent the solid concentration from reaching the critical value. 

Three key parameters are required for thickener design the thickener basin area (or unit area), the thickener basin depth, and the torque for the rake. These are discussed here. 

A wide variety of thickener designs [ 17,18] are available to suit specific criteria such as high rate, or to maximise underflow solids (e.g. paste thickeners), a typical example is illustrated in Figure 6.13. 

CYCLONE SEPARATORS, ELECTROSTATIC PRECIPITATORS, OTHER DEVICES 385 Table 14-3 Estimated Heights for Thickener Design... 

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