Copolymer mineral fines stabilizers

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. 

TABLE VI. EFFECTIVENESS OF COPOLYMERS AS MINERAL FINES STABILIZERS... 

The observation that the quaternary ammonium monomer content of MDTHD.-DMAEMA and DMAEMA CH3C1 DMAEMA copolymers had little effect on their silica fines stabilization properties of prompted an investigation of nonionic polymers as mineral fines stabilizers (17,18). A series of N-vinylpyrrolidinone (NVP) copolymers with DMAEMA have been studied. Results are summarized in Table VII. 

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. 

Monomer reactivity ratios and thus comonomer sequence distributions in copolymers can vary with copolymerization reaction conditions. The comonomer distribution could affect the geometry of the adsorbed polymer - mineral complex and the fines stabilization properties. 

Nonionic copolymers of N-vinylpyrrolidinone also functioned as mineral fine particle stabilizers. 

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