Study On Preparing Flocculants Used In Red Mud Settling With Inverse Emulsion Method And Modification

Flocculant settling separation of red mud in alumina industry is an indispensable material, this article through graft polymerization and polymer modified two directions to improve flocculant sedimentation of red mud separation ability.In the first part of this thesis, sodium polyacrylate optimized synthetic by inverse emulsion method. Through the determination of inverse emulsion conductivity changes, using Isopar M as the oil phase, we investigated the stability of the emulsion and studied the effect of compound emulsifier ratio, the oil-water mass ratio, redox initiator and regulation of additives on sodium polyacrylate conversion rate and emulsion stability. Experimental results show that the Isopar M inverse emulsion stability optimum conditions:the amount of emulsifier is6%(w) in oil phase, m(Span60):m(Tween80)=15:1, the oil phase and water phase mass ratio is1.74:1; When the mass ratio of K2S2O8and ethanediamine in redox initiator is2,45℃pH≥10, the sodium acrylate conversion is97%. The appropriate amount of adjustment additives such as emulsifying additives, anti-crosslinking agentand and deoxidant etc. are helpful to get a more stable inverse emulsion and higher molecular weight of sodium polyacrylate product.In the second part of this thesis, we adopt the method of starch graft acrylamide on modified copolymerization, graft polymerization reaction mechanism is discussed and surveyed the state of starch granule size, pasting, reaction temperature and pH value of medium graft polymer was efficiency and the influence of molecular weight, the experimental results show that under50℃, the aggregate smaller rice starch grafting rate is highest, about71%, the molecular weight of branch chain is7.68X106. As completely gelatinized, the starch grafting efficiency is high, the grafted polymer molecular is weight. Starch graft acrylamide copolymer from its homopolymer in pH has a wide range of conditions, and which can effectively reduce the effect of H+to the baking products of the water-soluble, the conversion rate is more than95%.Finally, we compared the flocculants of laboratory and the homopolymerization flocculants by measuring cylinder experiment, and the performance of red mud sedimentation experiment results show that two kinds of flocculants from its homopolymer of laboratory, the red mud sedimentation rate are increased, and the dosage of the flocculating agent has a great influence on the red mud settlement process, and less excess flocculant can reduce red mud sedimentation effect, which is not conducive to clarity of supernatant fluid. Modified flocculants is fastest sedimentation rate when addition amount of0.1g,8℃, the turbidity of the supernatant fluid is lowest,about266NTU.