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Incorporation of zinc in ferrous sulfate monohydrate
Abstract
Continuous crystallization experiments on FeSO4 · H2O in aqueous solutions containing Zn2+ were carried out, at temperatures of 140–165°C, in a stainless steel/glass autoclave. The incorporation of Zn2+ in FeSO4 · H2O as a function of process parameters such as the temperature and the residence time was determined. Additionally, the solubility of FeSO4 · H2O in this temperature region in the presence of ZnSO4 was determined. The crystallization of FeSO4 · H2O yielded a product which contained between 2 and 3 wt% Zn2+, depending on the process conditions. The incorporation of Zn2+ was also quantified using a partition coefficient which, together with the calculated results for the supersaturation in the various experiments, revealed that the incorporation of Zn2+ in FeSO4 · H2O increased with the supersaturation, but was mainly influenced by the thermodynamic value of the partition coefficient; that is, a value equal to 0.3 at zero supersaturation.The separation of Fe2+ and Zn2+ from aqueous solutions by crystallization of FeSO4 · H2O has too low a selectivity to justify its use in an integrated hydrometallurgical jarosite treatment process.
... Majuste et al. (2013) also pointed out that FeSO 4 •H 2 O crystals were detected on chalcopyrite (CuFeS 2 ) particle surface during the oxidative leaching of chalcopyrite in the temperature range of 100 • C to 200 • C by using in situ synchrotron X-ray diffraction techniques. Our results are in accordance with studies on solubility of the ferrous sulphate at elevated temperature (Cheng, 2002;Elgersma et al., 1993;Hasegawa et al., 1996;Kobylin et al., 2011). Elgersma et al. (1993) reported the solubility of pure FeSO 4 •H 2 O crystals as a function of temperature, indicating that FeSO 4 •H 2 O readily dissolved during cooling, although it was formed propitiously at high temperature. ...
... Our results are in accordance with studies on solubility of the ferrous sulphate at elevated temperature (Cheng, 2002;Elgersma et al., 1993;Hasegawa et al., 1996;Kobylin et al., 2011). Elgersma et al. (1993) reported the solubility of pure FeSO 4 •H 2 O crystals as a function of temperature, indicating that FeSO 4 •H 2 O readily dissolved during cooling, although it was formed propitiously at high temperature. The FeSO 4 •H 2 O could be the stable phase at 160-220 • C (Hasegawa et al., 1996) and 90% of Fe(II) crystallized as ferrous sulphate at 200 • C preceding initiation of oxydrolysis (Cheng, 2002). ...
... Most hydrometallurgical Zinc plants remove iron from leaching liquor by precipitating ammonium jarosite NH 4 Fe 3 (SO4) 2 (OH) 6 at a controlled pH and temperature [24] [25]. ...
Zinc containing flue dusts generated during a copper matte smelting process in a water-jacket furnace was leached in a zinc electrowinning return solution at 55 °C. Ninety percent of the metal was dissolved after 2 h of treatment. The leaching residues contained near 43 wt.% PbSO4.Iron was removed from leaching solutions by precipitation using a saturated lime solution at pH 3–4. The precipitate formed mainly consisted of gypsum CaSO4.2H2O. Iron and magnesium co-precipitated into a chloro-hydroxide compound. No zinc compound had co-precipitated during iron removal. Copper and germanium contents lower than 10 mg/l were achieved by solvent extraction using 10% LIX 64N and cementation. Cobalt contents lower than 1 mg/l in the solution were achieved by cementation on zinc granules for 2 h at 72 to 82 °C in presence of antimony. Cadmium contents of solutions were reduced to 10 mg/l by cementation on zinc granules at room temperature.Electrons transfer regime was identified as a limiting step during zinc electrolysis in a symmetric electrolysis current–continuous circulating system, SEC-CCS. Electrolysis current efficiency higher than 94% and 3.5 kWh/kg of specific energy consumption was achieved under 500–600 A/m2 at 35 to 40 °C in the presence of gelatine.
Acid pressure oxidation (POX) is a cost-efficient pre-treatment method for releasing refractory gold from arsenopyrite and pyrite prior to cyanidation. However, ongoing debate surrounds the mechanism of the dissolution, crystallization, and phase transformation during POX, in part due to the lack of thermodynamic data and in situ studies of the acid POX. In this study, we developed Eh-pH diagrams and used in situ powder X-ray diffraction (PXRD) to investigate mineralogical phase changes during acid POX of arsenopyrite. Based on the existing thermodynamic data, we established the Eh-pH diagrams for the Fe-As-S-H2O systems at 225 °C and 100 °C, which correctly predicted the predominant solid phases precipitating during POX of arsenopyrite at a pH range of 0 to 0.5, such as basic ferric sulphate (BFS: Fe(OH)SO4), szomolnokite (FeSO4·H2O), hydronium jarosite ((H3O)Fe3(SO4)2(OH)6) and angelellite (Fe4O3(AsO4)2). FeSO4·H2O solid is the stable phase during annealing stages as predicted by the Eh-pH diagram, which is in line with the observed solid phases using in situ PXRD. The influence of initial concentration of ferric ions and the presence of pyrite on mineral phase change was revealed. Our results confirmed the formation of FeSO4·H2O, BFS and hydronium jarosite during annealing stages, while BFS and/or hydronium jarosite dissolved during curing and cooling process. Especially, the formation of angelellite was observed in the presence of pyrite during cooling process, which is well-agreed with thermodynamic analysis.
Single crystals of synthetic nickel sulfate monohydrate, α-NiSO4·H2O (space-group symmetry C2/c at ambient conditions), were subject to high-pressure behavior investigations in a diamond-anvil cell up to 10.8 GPa. By means of subtle spectral changes in Raman spectra recorded at 298 K on isothermal compression, two discontinuities were identified at 2.47(1) and 6.5(5) GPa. Both transitions turn out to be apparently second order in character, as deduced from the continuous evolution of unit-cell volumes determined from single-crystal X-ray diffraction. The first structural transition from α- to β-NiSO4·H2O is an obvious ferroelastic C2/c–P1̅ transition. It is purely displacive from a structural point of view, accompanied by symmetry changes in the hydrogen-bonding scheme. The second β- to γ-NiSO4·H2O transition, further splitting the O2 (hydrogen bridge acceptor) position and violating the P1̅ space-group symmetry, is also evident from the splitting of individual bands in the Raman spectra. It can be attributed to symmetry reduction through local violation of local centrosymmetry. Lattice elasticities were obtained by fitting second-order Birch–Murnaghan equations of state to the p-V data points yielding the following zero-pressure bulk moduli values: K0 = 63.4 ± 1.0 GPa for α-NiSO4·H2O, K0 = 61.3 ± 1.9 GPa for β-NiSO4·H2O, and K0 = 68.8 ± 2.5 GPa for γ-NiSO4·H2O.
Blast furnace flue dust is a mixture of oxides expelled from the top of the blast furnace, whose major components are iron oxides. They also contain zinc, silicon, magnesium and other minor element oxides in a lesser amount. The direct recycling of flue dust is not usually possible since it contains some undesirable elements (zinc and alkaline metals) that can cause operational difficulties in the blast furnace. Furthermore, in some cases, the dust contains toxic elements (zinc, cadmium, chromium, and arsenic) that make it hazardous and unacceptable for landfill. The fact that it is not possible to recycle this dust directly or to reject it as landfill, makes it necessary to consider the recovery of the valuable elements contained in it and to obtain a non-hazardous residue that can be stored without problem or can be used in agglomeration units in iron-making industries. To reach this objective a sequence of unit operations which consists of leaching, filtration, purification, extraction, stripping and electrolysis processes is required. In this research, a blast furnace flue dust which principally consists of iron, with some zinc and other elements oxides has been examined. The preliminary results show that it is possible to leach selectively the valuable elements of the dust by sulphuric acid at low acid concentration and room temperature, giving high recovery using zinc (about 80%). The pregnant solution obtained is subjected to purification and extraction for eliminating its contaminants, and increasing its zinc concentration before electrowinning the zinc.
©1997 Elsevier Science B.V.
This paper gives a short overview of the importance of solvent extraction in the production and recycling of strategic metals. Both the present situation and possible developments are considered. The use of solvent extraction in the processing of powdered metal-containing materials with tailor-made characteristics is also discussed as it is attracting increasing attention.
The metallurgical industry faces challenges in the development and production of new products in response to rapidly changing technologies that demand materials with widely different properties and increasingly stringent quality control. Such materials include semiconductors, ultrahigh-purity metals, chemical-vapor-deposited metallic films, high-performance intermetallics, metallic superconductors, and metal-based composites. In view of this, the author propounded the establishment of value-addition metallurgy as a subdiscipline of extractive and process metallurgy. Such a subdiscipline would cover the principles and practice involved in the production of these value-added advanced materials based on metals. In this respect, this annual review article now includes a section covering papers concerned with these topics.
Blast furnace flue dusts are a mixture of oxides expelled from the top of the blast furnace, whose major components are iron oxides. They also contain zinc, silicon, magnesium and other minor element oxides in lesser amounts. The direct recycling of flue dust is not usually possible since it contains some undesirable elements (zinc and alkaline metals) that can cause operational difficulties in the blast furnace. Furthermore, in some cases the dust contains toxic elements (zinc, cadmium, chromium and arsenic) that make it hazardous and unacceptable for landfill. The fact that it is not possible to recycle this dust directly or to reject it as landfill, makes it necessary to consider the recovery of the valuable elements contained in it and to obtain a non-hazardous residue that can be stored without problem or can be used in agglomeration units in iron-making industries. To reach this objective a sequence of unit operations which consists of leaching, filtration, purification, extraction, stripping and electrolysis processes is required. In this research a blast furnace flue dust which principally consists of iron, with some zinc and other elements oxides has been examined. The preliminary results show that it is possible to leach selectively the valuable elements of the dust by sulphuric acid at low acid concentration and room temperature, giving high recovery using zinc (about 80%). The pregnant solution obtained is subjected to purification and extraction for eliminating its contaminants, and increasing its zinc concentration before electrowinning the zinc.
Proefschrift Technische Universiteit Delft. Met lit. opg. - Met samenvatting in het Nederlands.
Isomorphous salts are those of the same chemical type, crystallize in similar space groups and have closed crystal lattice parameters so as to form a continuous series of mixed crystals. Admixed salts, which in the crystalline state are isomorphous with the host crystal, are called isomorphous admixtures. The isomorphous mixed crystals are characterized by the free energy of the isomorphous mixing DELTA Gim. If the stable crystal form of the admixed salt is not isomorphous with the host crystal under the experimental conditions, the very existence of mixed crystals may be interpreted as an indication of the existence of the polymorphous form of the admixed salt, which is metastable under the corresponding conditions and which is isomorphous with the host crystal. In this case the terms iso-dimorphism or iso-dimorphous admixtures are used. The free energy of the iso-dimorphous mixing DELTA Gidm will be the sum of the free energy of the isomorphous mixing and the free energy of the phase transition DELTA GIIrt arrow I. For sulphates the ability of the ions of zero crystal field stabilization energy (Zn²⁺, Mg²⁺) to adopt the coordination environment of the substituted ion in monoclinic crystal hydrate salts is larger; such a process occurs with a lower expense of energy than for the open-shell ions (Co²⁺, Fe²⁺, Ni²⁺) which have to adopt the coordination environment of the substituted ion in orthorhombic crystal hydrate salts. For CdSO4.7H2O the orthorhombic structure is energetically more stable than the monoclinic one, whereas for CuSO4.7H2O the reverse is true.-J.M.H.
The theoretical bases for prediction of solubilities are provided by thermodynamics and statistical mechanics. In many cases statistical mechanics yields the chemical potential as an equation including several terms. While one or more terms may be fully determined theoretically, the parameters in other terms must be evaluated empirically at present. Then the solubility is obtained by equating the chemical potential for each species in different phases or by minimizing the total Gibbs energy at constant pressure and temperature. As an example of a recent major advance, the problem of the solubility of salts, including complex minerals, in multicomponent aqueous solutions is discussed in some detail. The status of predictive calculations for 25°C is described and new results for higher temperatures are reported. Brief comments are added concerning theories for other types of solubility systems. 47 refs., 2 figs., 6 tabs.
Die Löslichkeit der zweiwertigen Sulfate von Eisen, Kupfer, Kobalt, Nickel und Zink in Wasser wurde in Abhängigkeit von der Temperatur bestimmt. Die erhaltenen Löslichkeitskurven werden diskutiert.
Im zweiten Teil der Arbeit wird über Messungen der Löslichkeit von Sauerstoff und Wasserstoff in wäßrigen Lösungen von H 2 SO 4 , NaOH, KOH, NH 4 OH, (NH 4 ) 2 SO 4 , CuSO 4 , CoSO 4 und NiSO 4 bei erhöhten Temperaturen berichtet. Die geannten Stoffe bewirken eine Minderung Gaslöslichkeit gegenüber der Löslichkeit in reinem Wasser.
Integrating jarosite residue processing in hydrometallurgical zinc refining—comparison of five potential processes
- Elgersma
Solubilities of salts and gases in water
- Bruhn
Solubility experiments of FeSO4 in ZnSO4 containing solutions
- Kammel