Hydrometallurgical processes for Waelz oxide valorisation – An overview

2019 ◽  
Vol 129 ◽  
pp. 308-320 ◽  
Author(s):  
N. Antuñano ◽  
J.F. Cambra ◽  
P.L. Arias
Keyword(s):  
Waelz Oxide

The Study of the Melting of Waelz Oxide with an Increase in the Temperature of the Calcination Process

2021 ◽  
Vol 316 ◽  
pp. 705-710
Author(s):  
A.G. Ryazanov ◽  
A.V. Senin ◽  
V.D. Nasonov
Keyword(s):  
Partial Melting ◽  
Gas Phase ◽  
Lead Oxide ◽  
Elevated Temperatures ◽  
Lead Sulfate ◽  
Raw Material ◽  
Chemical Transformations ◽  
Calcination Process ◽  
Waelz Oxide ◽  
Negative Effect

Waelz-oxide is a raw material for the production of metallic zinc. Waelz-oxide contains impurities of zinc and lead chlorides and fluorides. Halides have a negative effect on the process of zinc electrolysis. Halides have a relatively low boiling point; therefore, they are removed into the gas phase by calcining Waelz-oxide at 800–850 °С. To intensify the process, calcination is sometimes carried out at elevated temperatures of 1100–1250 °С. However, an increase in temperature leads to partial melting and granulation of the calcined product. In the present work, the chemical and phase composition of the initial and calcined Waelz-oxide was studied. Thermodynamic modeling of phase and chemical transformations of Waelz-oxide components during heating has been performed. Experiments on calcination of Waelz-oxide in laboratory conditions at temperatures of 600–1250 °C were carried out. It was found that partial melting and granulation of Waelz-oxide is the result of the formation of fusible eutectics containing lead oxide. Lead oxide is formed as a result of decomposition of lead sulfate when heated above 1100 °C. A similar effect is not observed at a standard calcination temperature of 850 °C.

scholarly journals Experimental Study on the Dissolution Behavior of Calcium Fluoride

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 988
Author(s):  
Suchandra Sar ◽  
Caisa Samuelsson ◽  
Fredrik Engström ◽  
Lena Sundqvist Ökvist
Keyword(s):  
Calcium Fluoride ◽  
Raw Materials ◽  
Extraction Process ◽  
Thermodynamic Calculations ◽  
Dissolution Behavior ◽  
Zinc Extraction ◽  
Solubility Behavior ◽  
Dissolution Tests ◽  
Waelz Oxide ◽  
Co Precipitation

The presence of halogens has an adverse effect on the zinc extraction process through electrowinning, the last phase of the RLE (Roasting, Leaching and Electrowinning) zinc extraction route. Fluoride (F−) may be present as calcium fluoride (CaF2) and this is, for example, the case in double leached Waelz oxide (DLWO). Efficient removal of F− from primary and secondary raw materials for zinc extraction results in a simplified process and increases flexibility in the selection of raw materials. Understanding of the solubility behavior of pure CaF2 can give valuable information on treatment for maximized halogen removal. Dissolution of CaF2 was studied with the addition of sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3). Dissolution studies were combined with thermodynamic calculations to understand the solubility behavior of CaF2 under different conditions. Results from the experiments and the thermodynamic calculations show that Na2CO3 and NaHCO3 have similar behavior if the pH is controlled at the same value. The available carbonate (CO32−) ion in the system limits the concentration of calcium (Ca2+) ion by precipitation of CaCO3, which enhances the dissolution of CaF2. At higher temperatures and pH, calcite, vaterite, and aragonite were formed and co-precipitation of CaF2 along with calcium carbonate (CaCO3) was observed. At lower temperatures and lower pH levels, only calcite and vaterite were formed and a coating by CaCO3 on CaF2 was found to hinder complete dissolution reaction. The results of this study indicate that the temperature along with the reagents used for the dissolution tests have a significant impact on the CaCO3 polymorph mixture (calcite, vaterite and aragonite) formation.

scholarly journals Characterization of Double Leached Waelz Oxide for Identification of Fluoride Mineral

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 361 ◽  
Author(s):  
Suchandra Sar ◽  
Lena Sundqvist Ökvist ◽  
Tobias Sparrman ◽  
Fredrik Engström ◽  
Caisa Samuelsson
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Inductively Coupled Plasma ◽  
Raw Materials ◽  
Analytical Techniques ◽  
Optical Emission ◽  
Sem Analysis ◽  
Waelz Oxide ◽  
Production Knowledge ◽  
Nuclear Magnetic

Double leached Waelz oxide (DLWO), with 76% zinc, is a secondary zinc containing raw materials obtained by the treatment of electric arc furnace dust. The content of fluoride in DLWO is still too high for direct leaching, as fluoride has a detrimental effect on electrowinning for zinc production. Knowledge of the characteristics of DLWO, and especially on how a fluoride mineral might exist, can contribute to further improvement of the selective leaching for the removal of fluoride. In this study, DLWO was characterized using analytical techniques, such as inductively coupled plasma-optical emission spectroscopy (ICP-OES), 19F liquid-state nuclear magnetic resonance (19F LS NMR), X-ray powder diffraction analysis (XRD), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) and 19F solid-state nuclear magnetic resonance (19F SS NMR). This study showed that DLWO mainly consisted of zincite (ZnO), cerussite (PbCO3) and a spinel containing zinc, iron and manganese. The fluoride mineral identified was calcium fluoride (CaF2). In SEM analysis, fluorine was found in larger grains together with calcium and oxygen, which was possibly calcium carbonate.

Waelz oxide calcination process adopted by Chelyabinsk Zinc Plant

2020 ◽  
pp. 43-50
Author(s):  
R. R. Asadulin ◽  
◽  
A. E. Pavlyuk ◽  
O. V. Belyakov ◽  
◽  
...  
Keyword(s):  
Calcination Process ◽  
Zinc Plant ◽  
Waelz Oxide

Mastering of leaching technology of calcined waelz-oxide

2015 ◽  
pp. 36-40
Author(s):  
Yu. V. Reshetnikov ◽  
◽  
O. V. Belyakov ◽  
K. M. Kozlov ◽  
M. S. Varganov ◽  
...  
Keyword(s):  
Waelz Oxide

Hydrometallurgical Processes Development for Zinc Oxide Production from Waelz Oxide

2010 ◽  
Vol 1 (3) ◽  
pp. 329-337 ◽  
Author(s):  
D. Herrero ◽  
P. L. Arias ◽  
J. F. Cambra ◽  
N. Antuñano
Keyword(s):  
Zinc Oxide ◽  
Oxide Production ◽  
Waelz Oxide
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