Clays, dewatering

Apphcations include ka olin clay dewatering, separation of fish oils from press Hquor, starch and gluten concentration, clarification of wet-process phosphoric acid, tar sands, and concentrations of yeast, bacteria, and fungi from growth media in protein synthesis (14). 

Deason, D.M. and Onoda, GY. (1984). Controlled dispersion of clays and its effects on phosphate clay dewatering. Min. Metall. Proc., 1(2) 149-152. 

Important applications include kaohn clay dewatering, tar dehydration and clarification of wet process phosphoric acid. 

Washing and dewatering by air displacement of cakes are possible. AppHcations are in the treatment of minerals, in the sugar industry, and in the treatment of municipal sewage sludge and fillers like talc, clay, whiting, etc. 

The vertical recessed plate automatic press, shown schematically in Figure 15 and described previously, is another example of a horizontal belt pressure filter. Cycle times ate short, typically between 10 and 30 minutes, and the operation is fully automated. The maximum cake thickness is about 35 mm washing and dewatering (by air displacement) of cakes is possible. Apphcations include treatment of mineral slurries, sugar, sewage sludge, and fillers like talc, clay, and whiting. 

Additions of new flocculants after conventional thickening produce further dewatering of mineral slimes. A clay flocculated with polyacrylamides and rotated in a dmm can produce a growth of compact kaolin pellets (84), which can easily be wet-screened and dewatered. A device called a Dehydmm, which flocculates and pelletizes thickened sludges into round, 3-mm pellets, was developed for this purpose. Several units reported in commercial operation in Japan thicken fine refuse from coal-preparation plants. The product contains 50% moisture, compared with 3% soflds fed into the Dehydmm from the thickener underflow (85). In Poland, commercial use of the process to treat coal fines has been reported (86), and is said to compare favorably both economically and technically to thickening and vacuum filtration. 

In most applications, far less current and lower voltages are used. For example, in dewatering clay soils to stabilize dams, foundations, or dredged spoil, 20—100 V/m are commonly applied (130,131). In soil stabilization (qv), power is applied for weeks to months. 

B. J. Schemer and A. G. SmeUey, Dewatering of Thickened Phosphate Clay Wastefrom Disposal Ponds, Paper A81-6, The Metallurgical Society of AIME, Warrendale, Pa., 1981 J. R. Pederson, ed., U.S. Bureau of Mines Research 81, U.S. Government Printing Office, Washington, D.C., 1981, p. 83. 

Vijh, A. K. Electro-Osmotic Dewatering of Clays, Soils, and Suspensions 32... 

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