Analytical and mineralogical study of a Ghana manganese ore: Quantification of Mn speciation and effect of mechanical activation

• Published in: Chemosphere (Oxford) Vol. 162; pp. 8 - 15
• Main Authors: He, Hongping, Cao, Jianglin, Duan, Ning
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2016
• Subjects: Carbonates - analysis; Characterization; Ghana; Manganese - analysis; Manganese - chemistry; Manganese ore; Mechanical activation; Minerals; Mining; Models, Chemical; Oxides - analysis; Silicon Dioxide; TG-DSC/FTIR; Thermodynamics; Ghana; Characterization; Thermodynamics; Manganese ore; TG-DSC/FTIR; Mechanical activation
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2016.07.061

In-depth understanding of the manganese ore would be beneficial to make the best use more environmental-friendly. A Ghana manganese ore before/after mechanical activation (MA) was therefore extensively characterized in our investigation. Surface Mn4+(35.5%), Mn3+(35.9%), Mn2+(28.6%) were detected by XPS, though XRD only revealed the presence of Mn2+-containing minerals. Thermal decomposition curve of manganese ore obtained by TG-DSC was divided into four stages from 373.15 K to 1273.15 K, which were quite consistent with the pattern of generated gases obtained by TG-FTIR and the theoretical thermodynamics analysis of the incorporated components involving ΔGTθ and Kpθ. Mn species distribution showed no difference for manganese ores before/after MA, but quantitative analysis showed the decrease of residual Mn content (cannot be extracted effectively by acid, from about 12% to 1%), and thereby the increased contents of other four Mn species (exchangeables, carbonates, oxides, organics), which was suggested to be correlated with the dissociation of Mn-containing flocs and SiO2 particles witnessed by SEM-EDS. It was also found that MA could obviously promote the Mn dissolution kinetics in acid condition, though the dissolution of manganese ore before/after MA were both diffusion controlled. This investigation gives benignant inspiration for the resource utilization of manganese ore, taking the increasingly severer situation of Mn resource supply into consideration. •Extensive characterization was conducted to understand the manganese ore.•TG-DSC curve was quite consistent with that of TG-FTIR and thermodynamics analysis.•It was found that mechanical activation could change the distribution of Mn speciation.•Mn speciation distribution variation was correlated with the dissociation of Mn-containing flocs and SiO2 particles.