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Wyszukujesz frazę "zinc carbonate" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Leaching behaviour of zinc from a smithsonite ore in sodium hydroxide solutions
Autorzy:
Ehsani, Ilhan
Ucyildiz, Ayse
Obut, Abdullah
Powiązania:
https://bibliotekanauki.pl/articles/110552.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
alkaline leaching
calcium zincate
nonsulfide zinc ore
smithsonite
zinc carbonate
Opis:
In this study, the leaching behaviour of zinc from a smithsonite ore sample (23.43% Zn) having goethite and calcite as main gangue minerals was investigated in sodium hydroxide solutions using Xray diffraction and chemical analyses. Within the studied NaOH concentration range (1-4 mole/dm3), higher leaching ratio values for Zn were obtained by leaching at 298 K because of the decreased stability of soluble zincate species in solution at higher temperatures. When the concentration of NaOH solution was increased from 1 to 3 mole/dm3 at 298 K, leaching ratio value of Zn increased from 3.8 to 70.1%. At 4 mole/dm3 NaOH concentration, Zn leaching ratio value (70.9%) levelled off due to the formation of solid hydrated calcium zincate phase in leaching solution. On the other hand, very low leaching ratio values of Zn were obtained by leaching in 1 mole/dm3 NaOH solution at 298 K (3.8%) and 363 K (1.4%) due to the formation of solid zinc hydroxide and solid zinc oxide phases, respectively. It was observed that increasing leaching time from 1800 to 14400 s at 3 mole/dm3 NaOH concentration, favoured the formation of hydrated calcium zincate phase and so decreased the leaching ratio of Zn to a lower value (60.6%). The effect of solid/liquid ratio was also investigated and it was found that when solid/liquid ratio was decreased, Zn leaching ratio values decreased at constant OH/Zn mole ratio and increased at constant NaOH concentration conditions. Besides, for some of the experiments, leaching ratio values of lead were also given.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 2; 407-416
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of heating on structure and leaching characteristics of a zinc carbonate ore
Autorzy:
Kumas, Cavit
Obut, Abdullah
Powiązania:
https://bibliotekanauki.pl/articles/1446908.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
calcium zincate
smithsonite
sodium hydroxide leaching
zinc carbonate ore
zinc oxide
Opis:
In this work, the structural changes occurred in a zinc carbonate (smithsonite) ore sample following heating at temperatures between 523 K and 1173 K were investigated in detail using X-ray diffraction (XRD), thermal (TG/DTA) and Fourier-transform infrared (FT-IR) spectroscopy analyses. Afterwards, the leaching characteristics of zinc from the ore sample and the heated ore samples in sodium hydroxide solutions were determined. While heating at 523 K did not cause any structural change in the ore sample, heating at 723 K completely converted smithsonite $(ZnCO_3)$ in the ore sample to zinc oxide $(ZnO)$, which resulted lower zinc leaching efficiencies of 40.6% and 62.0% for 3 and 4 mol/dm3 NaOH concentrations, respectively, in comparison to zinc leaching efficiencies (67.2% and 70.7%) obtained for the unheated ore sample. On the other hand, due to neoformation of dissolution resistant $ZnFe_2O_4$, $Ca_2ZnSi2O_7$ and $Zn_2SiO_4$ phases during heating and formation of $CaZn_2(OH)_6∙2H_2O$ phase during leaching, the leaching efficiency of zinc further decreased to 22.2% and 31.3%, respectively, in 3 and 4 $mol$ / $dm^3$ NaOH solutions for the ore sample heated at 1173 K. The formation of zinc-containing dissolution resistant phases by high-temperature heating was observed to be the only reason for the reduction in the zinc leaching efficiency (49.4% at 1173 K) at the highest NaOH concentration (8 mol/dm3) studied. In this work, the comparative precipitation studies were also conducted and crystalline zinc oxides with different morphologies could be precipitated at considerably high efficiencies from the selected pregnant solutions obtained following leaching.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 5; 23-32
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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