Selective recovery of rare earths from bauxite residue by combination of sulfation, roasting and leaching
| Autor: | Tom Van Gerven, Bart Blanpain, Koen Binnemans, Yiannis Pontikes, Chenna Rao Borra, Jasper Mermans |
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| Rok vydání: | 2016 |
| Předmět: |
inorganic chemicals
Inorganic chemistry chemistry.chemical_element 02 engineering and technology 010501 environmental sciences engineering.material complex mixtures 01 natural sciences 020501 mining & metallurgy chemistry.chemical_compound Residue (chemistry) Aluminium Sulfate Dissolution 0105 earth and related environmental sciences Roasting Mechanical Engineering Metallurgy food and beverages General Chemistry Geotechnical Engineering and Engineering Geology Red mud Bauxite 0205 materials engineering chemistry Control and Systems Engineering engineering Leaching (metallurgy) |
| Zdroj: | Minerals Engineering. 92:151-159 |
| ISSN: | 0892-6875 |
| DOI: | 10.1016/j.mineng.2016.03.002 |
| Popis: | Bauxite residue (red mud) that is generated from karst bauxite ores is rich in rare-earth elements (REEs). The REEs can be recovered from bauxite residue by direct acid leaching but the extraction yields are generally low. The extraction yields can be increased by increasing the acid concentration but this will increase the dissolution of iron as well. Large amounts of iron in the leach solution create problems in the further recovery processes. Therefore, a combined sulfation–roasting–leaching process was developed to selectively leach the REEs while leaving iron undissolved in the residue. In this process bauxite residue was mixed with water and concentrated H2SO4 followed by drying, roasting and then leaching of the roasted product with water. Most of the oxides were converted to their respective sulfates during the sulfation process. During subsequent roasting, unstable sulfates (mainly iron(III) sulfate) decompose to their respective oxides. Rare-earth sulfates, on the other hand, are stable during roasting and dissolve during water leaching, leaving the iron oxides in the residue. The effect of the roasting temperature, roasting time and amount of acid on leaching of the different elements was studied. Decreasing the roasting temperature increased the dissolution of the REEs, but also that of iron and aluminum. Increasing the amount of acid led to higher REEs extraction. Acid to bauxite residue mass ratio beyond 0.75 at 650 °C increases the iron and aluminum dissolution due to increase in the iron(III) and aluminum sulfate amounts. The extraction of REEs slightly increased ( |
| Databáze: | OpenAIRE |
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