The Preparation Of Hydroxylamine Modified P(AM/SVS) And Its Floculation Performance

This paper first reviews the synthesis and development of polymeric flocculants used for red mud separation. On the basis of studying flocculation mechanism, we design and make a high molecular weight synthetic polymer flocculant containing many groups such as hydroxamate group, sulfo group, amide group and carboxyl group in order to aid solid-liquid separation of bauxite residue from pregnant liquor in the Bayer process. Copolymer of P(AM-SVS) was synthesized through inverse emulsion polymerization used acrylamide and Sodium vinylsulfonate as monomers. And then the copolymer was modified by hydroxylamine hydrochloride to introduce hydroxamate group. The effects of polymerization condition on viscosity-average molecular weight and stability of polymers were studied. Composition and structure of the modified copolymer was characterized by infrared spectroscopy, TG-DTA, particle size analysis and color reaction of FeCl3. It was used red mud slurry of Luo yang Heung Kong Aluminum Co.Ltd as studying object, systematically studied the effects of synthetic flocculant to red mud flocculation separation. Then hydroxylamine modified P(AM-SVS) was contrasted with each other for their flocculation properties. At last, the interaction of the flocculant and red mud particles was studied.The optimum synthesis technology of the copolymers is as follows: monomer concentration is 25wt%, the mass ratio of acrylamide to Sodium ethylenesulphonate is 9:1, concentration of initiator (ammonium persulfate and natrium Sulfite) is 0.3%, emulsifier(Span-60,Tween-80) is 6%, HLB is 6.5, the oil-water ratio is 1.5, reaction temperature is 40℃. In this condition, the viscosity-average molecular weight of polymer reached to 1020 million. Settlement experiment shows: The molecular weight of flocculant has obvious effect on red mud sedimentation. When adding amount of flocculant is 50g/t dry red mud, the mean setting rate of red mud is 13.4mm/min in 10 minutes, which is close to flocculants A665 and N85010. Overflow liquor clarity is prior to N85010, close to A665 and was the best of duplicate matched with sodium polyacrylate. All flocculation performance was better than the domestic product sodium polyacrylate (PAA). It is a good flocculant for red mud separation which full dissolved in 5 minutes, the dissolution rate was much faster than other products.