Effect of polyacrylamide on the process of removing impurities in the rare earth leachate

Abstract

The removal of impurities of the rare earth (RE) leachate from the RE-containing ore is usually accompanied by the formation of flocs, and a certain amount of polyacrylamide (PAM) flocculant needs to be added in this process. However, few studies have investigated the effect of the flocculant on the impurity removal process of the RE leachate. Therefore, this study aimed to investigate the flocculation process for removing impurities from the RE leachate in the absence and presence of PAM. The results showed that the addition of PAM showed little effect on the removal efficiencies of impurities, but it could increase the recovery of RE. And cationic PAM was more suitable for this impurity removal process than anionic PAM. When ammonium bicarbonate was firstly adopted to regulate the solution pH to 5.0, and then sodium sulfide was used to adjust the pH to 5.2, and 2 mg/L of cationic PAM was added to the solution, 96% Al 3+ and 98% Zn 2+ were removed from the solution, while 96% RE was maintained. Also, cationic PAM could accelerate the settlement of flocs, the settling time of the flocs shortened from 60 min to 20 min. This work may provide a promising way to shorten the production cycle and increase the recovery of RE.

The intensified effect of nitrogen removal properties using Pseudomonas fulva K3 and MgBC for the weathered crust rare earth wastewater treatment

“…The rare earth elements are existed as hydroxyl aqueous ions adsorbed on the clay minerals, resulting in the ion-exchange method as its recovery technology in industry (Zhou et al, 2019). And ammonium salts are widely used as leaching agents for the extraction of rare earth elements by in-site leaching process (Feng et al, 2018;Wu et al, 2020;Zhao et al, 2017). Quite amounts of ammonia nitrogen (NH4 + -N) is still remained in the ore body after the extraction process and it can be easily eluted by the rain, flowing into surface water and causing eutrophication (Li et al, 2017).…”