The Red Mud Settling A New Type Of Flocculant And Its Performance Study

Red mud generated from Chinese diaspore bauxite has a poor settling performance, so that red mud settlement requires excellent polymeric flocculants. At present, the settling performance of domestic commodity flocculants are poor, while the imports are expensive. Moreover, red mud generated from Chinese diaspore bauxite is different from foreign products in composition and physical and chemical properties, which may result in ineffective. Preparation of a new effective polymeric flocculant suitable for red mud generated from Chinese diaspore bauxite is one of the problems urgent to be solved in the production of aluminum oxide.This paper was aimed to prepare a new flocculant suitable to red mud generated from Chinese diasporic bauxite better. The dissertation mainly focused on:(1) A new functional monomerβ-methylhydrogen itaconate was prepared.(2) A series of different molecular mass polyacrylamide flocculants ( abbreviated as ASAM ) were synthesized first via solution copolymerization of acryamide , sodium acrylate andβ-methylhydrogen itaconate. The effects of purification method, activated carbon adsorption pH and molecular weight regulator on copolymer intrinsic viscosity were studied. The optimum process conditions of copolymer were obtained as follows: acrylic acid was purified by activated carbon adsorption (pH 7.37, 10% based on AA mass, 30℃stirring adsorption 30min) , ammonium persulfate was used as initiator at 30℃, initiator concentration was 0.1‰(based on AA mass), the concentration of metal-shelter agent EDTA-2Na was 0.7‰(based on AA mass), the concentration of molecular weight regulator was 0.8‰(based on AA mass). The monomer concentration was 38-39%, and the intrinsic visicosity of the obtained copolymer was 1400 mL/g, which was also easily soluble. The flocculating performances of ASAM to settle red mud which was the diaspore residue from bayer process was superior to most commercial flocculants.(3) Then the inverse emulsion copolymerization of acryamide and sodium acrylate andβ-methylhydrogen itaconate was studied. Conductivity method, still-setting method and low temperature storage method was used to seclect the reasonable chemical structure emulsifier which had better matching ability with white oil. On the material ratio of solution copolymerization, the composition of inverse emulsion were as follows: white oil was used as continuous phase, Span-60 and PBA-OP (6/4) was used as emulsufier, the concentration of emulsufier was 8%, the mass ratio of organic phase to aqueous phase decreased to 0.3, and the monomer content in emulsion was 46.3%. The ASAM inverse emulsions Pre and Post added reversed-phase agent were employed in the settling of the red mud. The flocculating performance of ASAM inverse emulsions added reversed-phase agent is almost equal to that of imported products.