Hematite fines, stabilization

Copolymers of MDTHD and DMAPMA appeared to be the most effective silica, calcite, and hematite mineral fines stabilizers. Increasing the copolymer MDTHD content had little effect on polymer performance. Similar results were observed for a series of MDTHD -DMAEMA copolymers and a series of DMAEMA CH-C1 salt - DMAEMA copolymers (Table VI). In contrast, increasing the MDTHD content of MDTHD - NNDMAm copolymers from 67% to 90% improved copolymer performance as a silica fines and hematite fines stabilizer. 

When the DMAEMA content of NVP - DMAEMA copolymers was reduced from 20% to 8%, the silica fines stabilization effectiveness appeared to improve slightly. When the 80/20 NVP - DMAEMA copolymer was converted to a terpolymer containing 8% DMAEMA (CH SO, silica fines stabilization was substantially unaffected. However, stabilization of silica/kaolinite fines was greatly improved. This suggested that the interaction of polymer quaternary nitrogen atoms with anionic sites on mineral surfaces was important for the stabilization of migrating clays but a different interaction was important for the stabilization of silica fines. Calcite fines stabilization improved while hematite fines stabilization effectiveness decreased. This also indicated the nature of the adsorbed polymer - fine particle complex varied for different minerals. 

Limited silica fines stabilization data indicated that increasing copolymer molecular weight from 100,000 to 1,000,000 daltons had, if anything, a negative effect on silica fines stabilization. At a molecular weight of 1,000,000 daltons, this copolymer appeared to be more effective in stabilizing silica fines than silica/kaolinite, calcite, or hematite fines. However, the results may be due in part to the larger particle size and lower surface area of the silica fines (see Table II). 

Murad, E. Schwertmann, U. (1984) The influence of crystallinity on the Mdssbauer spectrum of lepidocrocite. Min. Mag. 48 507-511 Murad, E. Schwertmann, U. (1986) Influence of Al substitution and crystal size on the room-temperature Mdssbauer spectrum of hematite. Clays Clay Min. 34 1-6 Murad, E. Schwertmann, U. (1988) Iron oxide mineralogy of some deep-sea ferromanganese crusts. Am. Min. 73 1395-1400 Murad, E. Schwertmann, U. (1993) Temporal stability of a fine-grained magnetite. Clays Clay Min. 41 111-113... 

Another area of practical importance is in controlling (or altering) the stability of colloid dispersions by organic acids. In analogy to hydrolyzed cations, polyprotic acids that react with the particles may either promote coagulation or inhibit it. The effect that prevails depends on the charge and the adsorptivity of anions in question. As example, the stability domain for finely dispersed hematite as a... 

---