Influence of Mineralogy on the Dry Magnetic Separation of Ferruginous Manganese Ore—A Comparative Study

Magnetic separation is often considered pertinent for manganese ore beneficiation when the ore is abundant with siliceous rich gangue mineral phases. However, the process is deemed to be inapposite for the ferruginous type of ore, and remains a grey area of research. In the present investigation, two different types of manganese ore were studied in detail to understand the influence of mineralogy on their magnetic separation performance. Detailed experiments were performed by varying the critical variables of the dry magnetic separator, and the separation features were studied. The ore samples were thoroughly characterized by various techniques, including an automated advanced mineralogical tool. The mineralogical results revealed that primary manganese bearing minerals in both the ores are rich in cryptomelene, pyrolusite, psilomelane, and bixybyite. Similarly, the major gangue minerals were alumina-bearing minerals and iron-bearing phases (hematite and goethite). The optimum grade that could be obtained from single-stage dry magnetic separation was 35.52% Mn, and with a Mn:Fe ratio of 1.77, and 44% Mn recovery in the case of sample 1; whereas, a 33.75% Mn grade, with a Mn:Fe ratio of 1.66 at Mn recovery of 44% was reported for Sample 2. It was observed that both samples had a similar input chemistry (~28% Mn, ~1 Mn: Fe ratio) however, they had distinctive mineralogical assemblages. Furthermore, it was observed that the liberation of manganese mineral was in a course size range, i.e., 300 to 450 µm, while the association of iron and manganese bearing phases was lower in sample 1 when compared to sample 2.

Use of tailings in mn dissolution from marine nodule matrix

The nodules are spherical bodies that are scattered within the sedimentary zone of the seabed, and their growth is closely associated with the biogeochemical processes and water sediments. These nodules are mainly composed of Mn, Fe, SiO2, Ca, Ni, Cu, Co and Al. Manganese nodules are an excellent source of base metals and sought-after and rare elements and the fact that they are used as a base elements matrix will be in high demand in industry. Previous studies have shown that primary con-centrations of chemical such as Fe in the system are beneficial for increas-ing manganese extraction. However, it is necessary to optimize the opera-tional parameters so as to maximise Mn recovery. This work investigates the effect of using of tailings, obtained after slag flotation ata foundry plant on the dissolution of Mn from marine nodules, where statistical analysis was distributed using factorial experimental design ontime, MnO2/Fe2O3 ratio, and H2SO4 concentration.

Improving manganese circular economy from cellulose by chelation with siderophores immobilized to magnetic microbeads

Manganese (Mn) contained in cellulose is partially responsible for an increased consumption of paper bleaching chemicals (like O2, H2O2), consequently diminishing the efficiency in pulp processing, darkening the pulp and deteriorating pulp quality. Usually, Mn in the paper industry is removed employing the environmentally critical EDTA. A greener alternative constitutes, however, the use of siderophores, high-affinity metal-chelating organic compounds that are produced by microorganisms to acquire metals (Fe and Mn among others), like desferrioxamine B (DFOB) or desferrioxamine E (DFOE). The use of native Mn-transporter proteins, like PratA, constitutes another possibility for Mn removal. The evaluation of utilizing siderophores or PratA for Mn removal from cellulose in a circular economy scheme is therefore essential. Firstly, Mn removal from cellulose was performed by immobilizing siderophores or PratA on magnetic beads (M-PVA C22). Secondly, the beads were incubated overnight with a 2% cellulose suspension, allowing Mn-ligand complex formation. Finally, cellulose suspensions were submitted for Mn quantification, employing either the TCPP [Tetrakis(4-carboxyphenyl)porphyrin] method, the PAN [1-(2-pyridylazo)-2-naphthol] method or the Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). When non-immobilized ligands were employed, a 31% Mn removal was achieved; when using immobilized ligands, around 10% Mn removal was obtained. Treated and untreated cellulose was analyzed by SEM and the Mn distribution between the solid and liquid phase was parameterized using adsorption isotherm models. This novel greener method proved to be feasible and easy, leading to potential improvements in the paper industry. Next research steps are to optimize Mn removal and quantify Mn recovery after ligand decoupling before scaling-up.

Process Simulation for Li-MnO2 Primary Battery Recycling: Cryo-Mechanical and Hydrometallurgical Treatments at Pilot Scale

Li primary batteries are currently treated along with other Li batteries in several big pyro- metallurgical plants in Northern EU countries. Nevertheless, pyro-metallurgical processes do not allow for Mn and Li recycling and present negative environmental impacts, on the other hand hydrometallurgical processing can potentially ensure the integral recovery of all materials in Li primary batteries. In this work, preliminary experimental findings obtained in the LIFE-LIBAT project (LIFE16 ENV/IT/000389) are reported. In this project, end of life Li(0)-MnO2 batteries were cryo-mechanically treated and then the metals were recovered by a hydrometallurgical process. Representative samples of end of life Li(0) batteries were characterized by type and composition. Batteries were stabilized in an N2 bath and then crushed, sieved, and magnetically separated in the SEVal pilot units. Separated fractions (fine fraction, magnetic coarse fraction, and non-magnetic coarse fraction) were chemically characterized for target metal content (Li and Mn). Fractions were first treated for Li extraction and recovery, then the fine fraction was also leached for Mn recovery. Mass balances evidenced a 55% recycling rate and process simulations outlined profitability in the potentiality range in agreement with battery collection fluxes.

Recovery of High-Purity MnO2 from the Acid Leaching Solution of Spent Li-Ion Batteries

Hydrometallurgical recycling processes for spent Li-ion batteries (LIBs) often produce pregnant leach solutions (PLS) that contain metals like Co, Ni, Mn, Li, Al, etc. Although significant research has focused on the recovery of the most valuable materials (e.g., Co, Ni, Li), the reclamation of Mn from PLS is often neglected. In this study, recovery of Mn via a multi-step process based on solvent extraction with di-2-ethylhexyl phosphoric acid, scrubbing, stripping and oxidative Mn precipitation has been undertaken. The results demonstrate that more than 99% of Mn can be successfully recovered as a high-purity MnO2 product (purity > 99.5%) with almost no loss of Co, Ni and Li. In addition, the behavior of other metal elements present in the PLS were also studied in detail. Overall, this study investigates the fundamentals of Mn recovery from the complicated PLS of LIBs waste and outlines industrial process feasibility based on known unit process steps.

Development of an Analytical Model for the Extraction of Manganese from Marine Nodules

Multivariable analytical models provide a descriptive (albeit approximate) mathematical relationship between a set of independent variables and one or more dependent variables. The current work develops an analytical model that extends a design of experiments for the leaching of manganese from marine nodules, using sulfuric acid (H2SO4) in the presence of iron-containing tailings, which are both by-products of conventional copper extraction. The experiments are configured to address the effect of time, particle size, acid concentration, Fe2O3/MnO2 ratio, stirring speed and temperature, under typical industrial conditions. The recovery of manganese has been modeled using a first order differential equation that accurately fits experimental results, noting that Fe2O3/MnO2 and temperature are the most critical independent variables, while the particle size is the least influential (under typical conditions). This study obtains representative fitting parameters, that can be used to explore the incorporation of Mn recovery from marine nodules, as part of the extended value chain of copper sulfide processing.

Optimization of Parameters for the Dissolution of Mn from Manganese Nodules with the Use of Tailings in An Acid Medium

Manganese nodules are an attractive source of base metals and critical and rare elements and are required to meet a high demand of today’s industry. In previous studies, it has been shown that high concentrations of reducing agent (Fe) in the system are beneficial for the rapid extraction of manganese. However, it is necessary to optimize the operational parameters in order to maximize Mn recovery. In this study, a statistical analysis was carried out using factorial experimental design for the main parameters, including time, MnO2/Fe2O3 ratio, and H2SO4 concentration. After this, Mn recovery tests were carried out over time at different ratios of MnO2/Fe2O3 and H2SO4 concentrations, where the potential and pH of the system were measured. Finally, it is concluded that high concentrations of FeSO4 in the system allow operating in potential and pH ranges (−0.2 to 1.2 V and −1.8 to 0.1) that favor the formation of Fe2+ and Fe3+, which enable high extractions of Mn (73%) in short periods of time (5 to 20 min) operating with an optimum MnO2/Fe2O3 ratio of 1:3 and a concentration of 0.1 mol/L of H2SO4.