title: Analytical and mineralogical study of a Ghana manganese ore: Quantification of Mn speciation and effect of mechanical activation.
abstract: 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 Mn(4+)(35.5%), Mn(3+)(35.9%), Mn(2+)(28.6%) were detected by XPS, though XRD only revealed the presence of Mn(2+)-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 ΔGT(θ) and Kp(θ). 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.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Hongping
authors.initials: H
authors.lastname: He
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Jianglin
authors.initials: J
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092, PR China; Technology Center for Heavy Metal Cleaner Production Engineering, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China. Electronic address: ningduan@craes.org.cn.
authors.forename: Ning
authors.initials: N
authors.lastname: Duan
mesh_terms: D002254:Carbonates / Q000032:analysis; D005869:Ghana; D008345:Manganese / Q000032:analysis / Q000737:chemistry*; D008903:Minerals; D008906:Mining; D008956:Models, Chemical; D010087:Oxides / Q000032:analysis; D012822:Silicon Dioxide; D013816:Thermodynamics
chemical_list: D002254:Carbonates; D008903:Minerals; D010087:Oxides; D008345:Manganese; D012822:Silicon Dioxide
keywords: Characterization; Manganese ore; Mechanical activation; TG-DSC/FTIR; Thermodynamics