|
|
Mobility of chromium and nickel in naturally contaminated soils
Kvapil, Jindřich ; Ettler, Vojtěch (advisor) ; Vaněk, Aleš (referee)
Soils developed on ultramafic rocks are relatively rich in trace elements, e.g. Cr, Co and Ni. Soils studied here and developed on serpentinites in the southern Bohemia exhibit high concentrations of these elements with up to several thousands mg/kg. Particularly soils with high Ni concentrations host specific vegetation and are are poor in nutrients. In this thesis we sampled two soil profiles located in the vicinity of closed Ni mining near Křemže in the southern Bohemia. Analyses of physicochemical parameters of soils, total concentrations of elements and their extractability using EDTA targeting "bioavailable" fraction were carried out. Concentrations of studied elements were the following: 27,1 - 423 mg Co/kg, 90,3 - 1190 mg Cr/kg, 170 - 4950 mg Ni/kg. Concentrations of Ni, Co and Cr significantly correlated with Fe (R2= 0.76-0.99) and were higher for agricultural soil profile with an increase as a function of depth. Maximum "bioavailable" concentrations were 47.6 mg Co/kg, 2.95 mg Cr/kg and 163 mg Ni/kg. Powered by TCPDF (www.tcpdf.org)
|
|
|
Leaching from slags and fly ashes from nickel metalurgy (Niquelandia and Barro Alto, Brasil)
Kvapil, Jindřich
Slag and fly ash originating from processing lateritic Ni-ore in the districts of Niquelândia and Barro Alto in Brazil are enriched with potentially toxic elements (PTEs). Higher contents of Ni and Co were observed in case of the fly ash (25 g/kg and 462 mg/kg, respectively), whereas higher concentration of Cr was observed in the slag (7, 58 g/kg). Mineralogical investigations indicate that slag mainly consists of olivine, pyroxene and glassy matrix. High content of glass corresponds to the product of quenching of slag melt in water basins during granulation. In contrast, the fly ash was mineralogically more complex with olivine, pyroxene, glassy phase and partly dehydrated serpentine phase, spinel, SiO2 and the furnace feed residues. Contaminant leaching was highly pH-dependent with the highest releases of PTEs from the fly ash at pH 3: up to 5, 42 g/kg Ni, 112 mg/kg Co and 4, 3 mg/kg Zn. Slag was significantly more stabile; only 47,9 mg/kg Ni was released at pH 3, but compared to the fly ash higher release of Cr was reported (up to 25.6 mg/kg). Towards alkaline conditions, the leachability of PTEs significantly decreases. Based on physic-chemical parameters of leachates, theoretical speciation of elements and saturation indices for selected solubility-controlling phases were calculated by...
|
|
|
Leaching from slags and fly ashes from nickel metalurgy (Niquelandia and Barro Alto, Brasil)
Kvapil, Jindřich ; Ettler, Vojtěch (advisor) ; Vítková, Martina (referee)
Slag and fly ash originating from processing lateritic Ni-ore in the districts of Niquelândia and Barro Alto in Brazil are enriched with potentially toxic elements (PTEs). Higher contents of Ni and Co were observed in case of the fly ash (25 g/kg and 462 mg/kg, respectively), whereas higher concentration of Cr was observed in the slag (7, 58 g/kg). Mineralogical investigations indicate that slag mainly consists of olivine, pyroxene and glassy matrix. High content of glass corresponds to the product of quenching of slag melt in water basins during granulation. In contrast, the fly ash was mineralogically more complex with olivine, pyroxene, glassy phase and partly dehydrated serpentine phase, spinel, SiO2 and the furnace feed residues. Contaminant leaching was highly pH-dependent with the highest releases of PTEs from the fly ash at pH 3: up to 5, 42 g/kg Ni, 112 mg/kg Co and 4, 3 mg/kg Zn. Slag was significantly more stabile; only 47,9 mg/kg Ni was released at pH 3, but compared to the fly ash higher release of Cr was reported (up to 25.6 mg/kg). Towards alkaline conditions, the leachability of PTEs significantly decreases. Based on physic-chemical parameters of leachates, theoretical speciation of elements and saturation indices for selected solubility-controlling phases were calculated by...
|
|
|
Leaching from slags and fly ashes from nickel metalurgy (Niquelandia and Barro Alto, Brasil)
Kvapil, Jindřich
Slag and fly ash originating from processing lateritic Ni-ore in the districts of Niquelândia and Barro Alto in Brazil are enriched with potentially toxic elements (PTEs). Higher contents of Ni and Co were observed in case of the fly ash (25 g/kg and 462 mg/kg, respectively), whereas higher concentration of Cr was observed in the slag (7, 58 g/kg). Mineralogical investigations indicate that slag mainly consists of olivine, pyroxene and glassy matrix. High content of glass corresponds to the product of quenching of slag melt in water basins during granulation. In contrast, the fly ash was mineralogically more complex with olivine, pyroxene, glassy phase and partly dehydrated serpentine phase, spinel, SiO2 and the furnace feed residues. Contaminant leaching was highly pH-dependent with the highest releases of PTEs from the fly ash at pH 3: up to 5, 42 g/kg Ni, 112 mg/kg Co and 4, 3 mg/kg Zn. Slag was significantly more stabile; only 47,9 mg/kg Ni was released at pH 3, but compared to the fly ash higher release of Cr was reported (up to 25.6 mg/kg). Towards alkaline conditions, the leachability of PTEs significantly decreases. Based on physic-chemical parameters of leachates, theoretical speciation of elements and saturation indices for selected solubility-controlling phases were calculated by...
|
|
|
Mobility of chromium and nickel in naturally contaminated soils
Kvapil, Jindřich ; Ettler, Vojtěch (advisor) ; Vaněk, Aleš (referee)
Soils developed on ultramafic rocks are relatively rich in trace elements, e.g. Cr, Co and Ni. Soils studied here and developed on serpentinites in the southern Bohemia exhibit high concentrations of these elements with up to several thousands mg/kg. Particularly soils with high Ni concentrations host specific vegetation and are are poor in nutrients. In this thesis we sampled two soil profiles located in the vicinity of closed Ni mining near Křemže in the southern Bohemia. Analyses of physicochemical parameters of soils, total concentrations of elements and their extractability using EDTA targeting "bioavailable" fraction were carried out. Concentrations of studied elements were the following: 27,1 - 423 mg Co/kg, 90,3 - 1190 mg Cr/kg, 170 - 4950 mg Ni/kg. Concentrations of Ni, Co and Cr significantly correlated with Fe (R2= 0.76-0.99) and were higher for agricultural soil profile with an increase as a function of depth. Maximum "bioavailable" concentrations were 47.6 mg Co/kg, 2.95 mg Cr/kg and 163 mg Ni/kg. Powered by TCPDF (www.tcpdf.org)
|
guest ::
RSS feed.