The Red Mud Settling Efficient Polyacrylamide Flocculant Preparation And Performance

In this paper, preparation of nonionic polyacrylamide with highmolecular weight were studied by the means of constant-temperaturepolymerization and adiabatic polymerization respectively, using novelinitiator system with high initiating efficiency in the polymerization. Andthe aim of the research was to enhance the separation effect of thered-mud in Zhongzhou aluminum factory requiring high settlement speed,high degree of overflow clarity, low proportion of liquid to solid inunderset during the settlement process. Meanwhile, anionic and cationicpolyacrylamide showing excellent flocculation property and wideapplicability were also synthesized by the means of hydrolization ofnonionic polyacrylamide with alkali added in later process andcopolymerization of acrylamide with cationic monomer. The optimumreaction condition of each polymerization and modification were asfollows:For the synthesis of nonionic polyacrylamide by the means ofconstant-temperature polymerization, the monomer concentration was30%, reaction temperature was 30℃, and the dosage of K₂S₂O₈, NaHSO₃,V50, urea, EDTA-2Na were 0.025‰, 0.025‰, 0.1‰, 40‰, 0.5‰respectively. For the adiabatic synthesis, the monomer concentration was30%, reaction temperature was 7.5℃, and the dosage of K₂S₂O₈, NaHSO₃,V50, urea, EDTA-2Na were 0.025‰, 0.025‰, 0.1‰, 5‰, 0.5‰respectively. For hydrolization of nonionic polyacrylamide, theappropriate temperature, reaction time and theoretical degree of hydro-lization were respectively 80℃, 4 hours and 20%～30%. For thesynthesis of cationic polyacrylamide, the cationic degree was 5%, themonomer concentration was 30%, reaction temperature was 30℃, thedosage of K₂S₂O₈, NaHSO₃, V50, urea, EDTA-2Na were 0.05‰, 0.05‰,0.025‰, 40‰, 0.5‰respectively.Excellent flocculation property of anionic polyacrylamide was foundbeing better than nonionic and cationic polyacrylamide, when the productsynthesized were adopted in the settlement of red-mud. In addition, betterfloculation effect and stability as well as wider applicability of anionic polyacrylamide were fbund when the molecular weight and thehydrolization degree were 1.1×10⁷ and 15% respectively. Theperformance of product synthesized arrived at or exceeded the standard ofthe domestic ones and meet the requirement of flocculation reagent forthe settlement of red-mud.