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Flocculation and Dewatering of Montmorillonite Modified by Ion Exchange.

Stanley-DA; Scheiner-BJ
MISSING :10 pages
The Bureau of Mines is investigating a method of dewatering flocculated fine-particle waste that involves treating the waste with a high-molecular-weight polymer such as polyethylene oxide (peo) followed by dewatering on a static screen and/or in a trommel. Dilution of the polymer solution used for dewatering and use of the ion-exchanged form of the montmorillonite clay were found to be major factors determining the amount of polymer required to dewater clay-containing slurries. The amount of polymer, a, required to dewater ion-exchanged montmorillonite can be described by the equation, an = kc + b, where n, k, and b are empirical constants and c is the concentration of the polymer solution used for dewatering. Clays that require large amounts of polymer for dewatering also dewater to a lower solids content. The concentration of the polymer solution is important because it affects the radius of the polymer coil in solution and hence its ease of transfer to a bridging configuration by shear. The constant, n, a function of the charge to hydrated radius of the exchange ion, relates to the strength of the bond between the polymer and the surface of the clay through a water bridge. The constant k is related to the hydrated radius for sodium or to the unhydrated radius for the other exchange ions. This report is based upon work done under an agreement between the University of Alabama and the Bureau of Mines.
Publication Date
Document Type
IH; Report of Investigations
Fiscal Year
Identifying No.
RI 9021
NIOSH Division
Source Name
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division