TY - THES

T1 - Selective chlorination and extraction of valuable elements from thermally treated iron precipitation residues of the zinc and nickel industry

AU - Witt, Kerrin

N1 - no embargo

PY - 2023

Y1 - 2023

N2 - Iron precipitation residues are amongst the most commonly generated residues of the nonferrous metal production, that arise, inter alia, in the hydrometallurgical processing of zinc and nickel. Despite of their potential as secondary resource for the recovery of numerous contained valuable metals, they are primarily disposed in tailing ponds. To use natural resources more efficiently and impede the strains on our environment and climate, sustainable processing strategies for such residues are necessary. A novel concept has been proposed at Montanuniversität Leoben, targeting the CO2-optimized extraction of valuable elements out of iron precipitation residues. In the course of this work, a thermal pretreatment, and the selective chlorination of valuable metals with their subsequent extraction through the gaseous phase have been investigated experimentally as well as theoretically using three different residues from the zinc and nickel industry. Simultaneous thermal analyses enabled the determination of the materials¿ thermal decomposition. Additionally, the enrichment of metals and the minimum energy demand of the thermal treatment were calculated for each of them. In a test series of 54 experiments in total, the extraction behavior of valuable metals from the calcined iron precipitation residues was evaluated for different chlorinating agents, mixture ratios and temperatures. Furthermore, thermodynamic simulations of the selective chlorination were conducted using the Equilib module of the software FactSage, the results were compared to those of the real experiments. The thermal treatment yielded good results in respect to enrichment and the decomposition of complex phases. Its minimum energy demand of about 1-2 GJ per ton of iron precipitation residue is an important parameter for the assessment of its economic feasibility. The extraction of the valuable metals Ag, Bi, In, Pb and Zn out of calcined precipitation residues from the zinc industry is viable with the chlorinating agents FeCl3·6H2O und MgCl2·6H2O, partially even at a lower temperature of 900 °C. In contrast, the recovery of the metals Co and Ni from calcined precipitation residues of the nickel production, occurred only to small extents under the given conditions. The results of the simulations differed from the observed tendencies in the real experiments and is therefore only applicable for rough estimations.

AB - Iron precipitation residues are amongst the most commonly generated residues of the nonferrous metal production, that arise, inter alia, in the hydrometallurgical processing of zinc and nickel. Despite of their potential as secondary resource for the recovery of numerous contained valuable metals, they are primarily disposed in tailing ponds. To use natural resources more efficiently and impede the strains on our environment and climate, sustainable processing strategies for such residues are necessary. A novel concept has been proposed at Montanuniversität Leoben, targeting the CO2-optimized extraction of valuable elements out of iron precipitation residues. In the course of this work, a thermal pretreatment, and the selective chlorination of valuable metals with their subsequent extraction through the gaseous phase have been investigated experimentally as well as theoretically using three different residues from the zinc and nickel industry. Simultaneous thermal analyses enabled the determination of the materials¿ thermal decomposition. Additionally, the enrichment of metals and the minimum energy demand of the thermal treatment were calculated for each of them. In a test series of 54 experiments in total, the extraction behavior of valuable metals from the calcined iron precipitation residues was evaluated for different chlorinating agents, mixture ratios and temperatures. Furthermore, thermodynamic simulations of the selective chlorination were conducted using the Equilib module of the software FactSage, the results were compared to those of the real experiments. The thermal treatment yielded good results in respect to enrichment and the decomposition of complex phases. Its minimum energy demand of about 1-2 GJ per ton of iron precipitation residue is an important parameter for the assessment of its economic feasibility. The extraction of the valuable metals Ag, Bi, In, Pb and Zn out of calcined precipitation residues from the zinc industry is viable with the chlorinating agents FeCl3·6H2O und MgCl2·6H2O, partially even at a lower temperature of 900 °C. In contrast, the recovery of the metals Co and Ni from calcined precipitation residues of the nickel production, occurred only to small extents under the given conditions. The results of the simulations differed from the observed tendencies in the real experiments and is therefore only applicable for rough estimations.

KW - Eisenfällungsrückstand

KW - Metallrückgewinnung

KW - Reststoffrecycling

KW - Thermische Behandlung

KW - Chlorierung

KW - iron precipitation residues

KW - metal recovery

KW - residue recycling

KW - thermal treatment

KW - chlorination

M3 - Master's Thesis

ER -