Abstract

Membrane filtration, particularly MF-UF, has previously been assessed as an attractive process for clarifying and recovering valuable metals from metal sulfide precipitation. Previous results of the high transmembrane flux achieved have shown to be promising. However, those studies were primarily focused on demonstrating the method's feasibility and estimating its performance under different operational conditions. Based on that, this study represents a significant advancement in the field, assessing the fouling behavior and its impact on process performance during the microfiltration of metal sulfide precipitates. Different operational conditions were evaluated using commercial microfiltration membranes operating in batch and continuous regimes, varying Cu concentration in the feed solution (200 and 1800 mg/L), and cross-flow velocities (0.2 - 0.16 m/s). Batch recirculation tests had over 80 % better flux results than the long-term continuous-mode operation tests, mainly due to a progressive decline in the membrane flux observed at longer operation times. Moreover, the cross-flow velocity evaluation indicated that elevated tangential flow rates might result in a decline in the performance of particles with high aggregation behavior. Analyses with modified Hermia's models and with SEM-EDX image characterizations demonstrated that cake filtration represents the primary fouling mechanism in this process under long-term operation. The present study offers crucial insights that will inform the further development of MF for the treatment of metal sulfide precipitates.