“Physicochemical processing of low grade ferruginous manganese ores”

Green and Efficient Utilization of Ferruginous Gibbsite Ore and Ferruginous Manganese Ore by Synergetic Carbothermic Co-Reduction–Magnetic Separation Process

The synergetic utilization of ferruginous gibbsite ores (Al-Fe ores) and ferruginous manganese ores (Mn-Fe ores) by the carbothermic co-reduction roasting–magnetic separation process was proposed as an innovative and green process for the separation and recovery of the valuable metal elements of Mn, Fe and Al from these ores. In this paper, a ferromanganese crude alloy with 72.47% Fe and 10.19% Mn and a high recovery of 85.89% Fe was prepared, which produces an acceptable feed to produce manganese steels with an electric arc furnace. The synergistic co-reduction of the two kinds of complex and refractory minerals was favored to separate Fe, Mn and Al from these ores. The influence of the operating variables on the recovery and separation of valuable metals from Mn-Fe ores and Al-Fe ores is initially studied. Then, the stepwise reduction behaviors of a composite oxide Mn1-xFexO (0 ≤ x ≤ 1) and hercynite (Mn1−yFeyAl2O4, 0 ≤ y ≤ 1) were investigated to clarify that Mn-Fe ores have a positive impact on the reduction of fayalite and hercynite in Al-Fe ores. This study reported a simple green route, the carbothermic co-reduction–magnetic separation process, to economically and effectively treat Al-Fe ores and Mn-Fe ores.

Physicochemical Aspects of Oxidative Consolidation Behavior of Manganese Ore Powders with Various Mn/Fe Mass Ratios for Pellet Preparation

With the depletion of rich manganese ore resources, plentiful manganese ore powders with various Mn/Fe mass ratios are produced. The physicochemical aspects of oxidative consolidation behavior of manganese ores with various Mn/Fe mass ratios were investigated in this work to determine whether manganese ore powders with high iron content (Fe-Mn ore) can be prepared as high-quality pellets. Physicochemical properties of the pellets were investigated, including cold compression strength (CCS), phase transformation, microstructural evolution, Vickers hardness (HV), porosity, and lattice parameter. CCS testing indicated that the strength of roasted Fe-Mn ore pellets was observably lower than that of pure hematite or manganese ore pellets. Phase and morphology results showed that in Fe-Mn ore pellets, an Mn ferrite phase was generated between hematite and pyrolusite particles. However, newborn Mn ferrites and hematite had an obvious crystal boundary in the crystallographic particles. Moreover, poorly crystallized Mn ferrite particles were evident, along with Mn and Fe element concentration gradients, due to the inadequate diffusion of metal ions. This resulted in poor mechanical properties of the Fe-Mn ore pellets. A temperature over 1275 °C and a roasting time of 15 min is required for the oxidative consolidation of Fe-Mn ores. In such optimized cases, Mn, Fe, O, and Al elements were uniformly distributed in the well-crystallized Mn ferrite grains, which provided favorable mineralogy for the consolidation of Fe-Mn ore powders.

A critical review on approaches for electrolytic manganese residue treatment and disposal technology: Reduction, pretreatment, and reuse

Electrolytic manganese residue (EMR) has become a barrier to the sustainable development of the electrolytic metallic manganese (EMM) industry. EMR has a great potential to harm local ecosystems and human health, due to it contains high concentrations of soluble pollutant, especially NH₄⁺ and Mn²⁺, and also the possible dam break risk because of its huge storage. There seems to be not a mature and stable industrial solution for EMR, though a lot of researches have been done in this area. Hence, by fully considering the EMM ecosystem, we analyzed the characteristics and eco-environmental impact of EMR, highlighted state-of-the-art technologies for EMR reduction, pretreatment, and reuse; indicated the factors that block EMR treatment and disposal; and proposed plausible and feasible suggestions to solve this problem. We hope that the results of this review could help solve the problem of EMR and thus promote the sustainable development of EMM industry.

A global life cycle assessment of manganese mining processes based on EcoInvent database

This paper presents the life cycle assessment (LCA) carried out on the manganese beneficiation and refining process. This cradle-to-gate analysis is carried out using SimaPro software version 8.5. The considered case is the manganese beneficiation and refining process, and the final product is 1 kg of refined manganese. The global average dataset is collected from the EcoInvent and AusLCI database, which are originated from literature source. The analysis methodologies considered in this study are the International Life Cycle Reference Data System (ILCD) method and Cumulative Energy Demand (CED) method. A comparative analysis is also presented which compared among ILCD, Australian Indicator, and Tool for Reduction and Assessment of Chemicals and Other Environmental Impacts (TRACI) methods to identify the best practice method for global analysis of mining processes. A detailed sensitivity analysis has been carried out considering different scenarios, to suggest possible solutions to reduce the environmental impacts associated with manganese beneficiation and refining processes. The analysis results reveal that particulate matter, climate change, categories of eutrophication, human toxicity (cancer and non-cancer effects), and acidification are some of the noteworthy impact categories. The analysis results also showed that coal consumption is significantly higher than other types of renewables and non-renewable energy consumption in manganese beneficiation and refining processes. The analysis results further reveal that using the chromium steel in manganese beneficiation process and ferromanganese consumption in the refining process has a significant effect over other materials involved in manganese beneficiation and refining operations. The obvious reason behind this result is ferromanganese utilization as an energy-intensive process, which in turn increases the environmental emissions. The analysis results also showed that, between the beneficiation and refining process, manganese refining has a much greater impact on the environment rather than the beneficiation process due to the fossil fuel and electricity consumption in refining operations.

Simultaneous Selective Chlorination and Carbothermic Reduction of High-Iron Manganese Ore for the Recovery of Manganese Chloride and Metallic Iron

Metallurgical processing of low-grade manganese ore with high iron content is gaining increasing attention due to the gradual depletion of high-grade Mn ores, amid the difficulties in its efficient extraction for both Mn and Fe values in an environmentally-friendly manner. Attempting to tackle the difficulties, this paper describes an innovative process for selectively chlorinating and reducing the high-Fe manganese ore in a simultaneous manner, aiming to produce water-soluble MnCl2 and metallic Fe. After pre-mixing with carbonaceous reductant, CaCl2 and MgCl2 as the chlorinating agent, the Mn ore was heated at 1000 °C. As much as 89.4% Mn can be chlorinated in its water-soluble form, with dissolution of only 3.0% Fe. The presence of CaCl2 during carbothermic reduction resulted in significant promotion in both the Fe reduction rate and formation of large metallic Fe particles due to the segregation effect, facilitating subsequent separation. Selective Mn chlorination by MgCl2 took place with or without the involvement of SiO2, forming MgSiO4 or MgO, respectively.