The Study Of Preparing Polyacrylamide Flocculants Used In Red Mud Settling With Inverse Microemulsion Method

Based on the summary and analysis of existed studies of polymer flocculant, series of researches were conducted to synthesis polyacrylamide inverse microemulsion., which is used in the red mud settling of the bayer process.By measuring the electrical conductivity, observing the appearance and Tyndall phenomena of the microemulsion, effects of varieties of alkanes, emulsion systems and monomer aqueous solution on the stability of AM microemulsion were studied, best matching microemulsion system of Isopar M/Span80-Tween60/AM/H2O was obtained, optimum conditions were as followed:HLB was8-8.5, minimum amount of emulsifier was18.52wt.%, maximum water phase amount was22.22wt.%, best oil/water ratio was2.67.Utilizing a single factor variable method to study the effects of intitation system, intitator consumption, polymerization temperature, reaction time and additives on the polymerization rate, conversion rate and polymer molecular weight of AM inverse micromulsion, optimum polymerization conditions were determined as:using water-soluble azo V50as intitator under nitrogen atmosphere at constant temperature, intitator consumption was0.3wt.%of monomer, EDTA consumption was0.2wt.%of monomer, reaction temperature was50℃, reaction time was5h. Under the optimum conditions, solid content of obtained PAM inverse microemulsion was10.68%, conversion rate was96.10%, relative molecular weight was3.52million, condutivity was0.023μS·cm-1, the microemulsion was uniform and stable, did not turn into two layers after long-term placement.By analysing the intrinsic vicosity and red mud flucculation performance of the product,infrared spectroscopy was also used to study the hydrolysis process, results showed that:using NaOH as the hydrolysis agent, a stable inverse microemulsion polymer can be obtained with the maximun hydrolysis degree was20%. If the hydrolysis degree was higher than20%, obtained system was a gel-like solid form without mobility, it can no longer be a microemulsion. The intrinsic vicosity of hydrolysis product HPAM was higher than PAM, the red mud flucculation performance of HPAM was significantly improved compared with PAM. With the increase of hydrolysis degree, the characteristic absorption peak intensity of carboxylic functional group was also enhanced in HPAM IR spectra.