Effect of Modified Additives on Process of Bayer Seeds Precipitation from Caustic Aluminate Solutions

摘要

By chemical reaction, polyacrylamide was modified by hydroxylamine hydrochloride, the effect of non-ionic polyacrylamide grafted by hydroxylamine group was attained to the maximum in the strong electrolyte solution of pH=l 1 under the temperature of 80°C, when the proportion of hydroxylamine to amide was 1:2. The precipitation experiment was that caustic aluminate solution was first added in stainless reactor, and after diluted and mixed with seeds, the mixed organic additives were also added in the reactor. It was found that the mixed additives of modified non-ionic polyacrylamide of relative molecular mass is 8×10~6, 1×10~7 and sodium polyacrylic acid of 1×10~7 increased precipitation ratios by 1.64% and 2.53% in comparison to reference experiment, the mixed additives of 35%, 50% modified positive polyacrylamide and sodium polyacrylic acid of 1×10~7 can increase precipitation ratios by 3.52% and 5.61%.