Selective Leaching Trace Elements from Bauxite Residue (Red Mud) without and with Adding Solid NH<sub>4</sub>Cl Using Microwave Heating
Bauxite residue (red mud), which is an industrial byproduct, contains valuable trace elements. Solid NH<sub>4</sub>Cl was used as a chlorinating agent during the microwave heating of red mud to convert trace elements into soluble metal chloride. Red mud was heated using microwave ovens u...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2021-08-01
|
| Series: | Metals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2075-4701/11/8/1281 |
| _version_ | 1797522906138279936 |
|---|---|
| author | Jin-Seok Kim Nag-Choul Choi Ho Young Jo |
| author_facet | Jin-Seok Kim Nag-Choul Choi Ho Young Jo |
| author_sort | Jin-Seok Kim |
| collection | DOAJ |
| description | Bauxite residue (red mud), which is an industrial byproduct, contains valuable trace elements. Solid NH<sub>4</sub>Cl was used as a chlorinating agent during the microwave heating of red mud to convert trace elements into soluble metal chloride. Red mud was heated using microwave ovens under various conditions (i.e., with the addition of solid NH<sub>4</sub>Cl and with a range of microwave output powers and microwave heating times). Leaching tests were then conducted using deionized (DI) water on the microwave-heated red mud to leach trace elements from red mud. V, Cr, and As were selectively leached from the microwave heated red mud slurry (30% water content), whereas Mn, Cu, Co, Ni, Zn, and Pb were selectively leached from the microwave-heated red mud with the addition of solid NH<sub>4</sub>Cl. The oxides of V, Cr, and As in red mud could be transformed into metal chlorides by chlorination, which are insoluble in water, or could be easily volatilized when red mud was microwave-heated in the presence of solid NH<sub>4</sub>Cl. On the other hand, the oxides of Mn, Cu, Co, Zn, Ni, and Pb in red mud could be heated rapidly by microwave irradiating, resulting in metal chlorides in the presence of solid NH<sub>4</sub>Cl. Those metal chlorides are relatively soluble in water, leading to higher leaching efficiency for microwave-heated red mud with the addition of solid NH<sub>4</sub>Cl. Experimental results suggest that trace elements from red mud can be selectively leached by microwave heating of red mud without or with the addition of solid NH<sub>4</sub>Cl. |
| first_indexed | 2024-03-10T08:35:59Z |
| format | Article |
| id | doaj.art-3339a548c91043fb9ceca3c11024c238 |
| institution | Directory Open Access Journal |
| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-03-10T08:35:59Z |
| publishDate | 2021-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Metals |
| spelling | doaj.art-3339a548c91043fb9ceca3c11024c2382023-11-22T08:42:15ZengMDPI AGMetals2075-47012021-08-01118128110.3390/met11081281Selective Leaching Trace Elements from Bauxite Residue (Red Mud) without and with Adding Solid NH<sub>4</sub>Cl Using Microwave HeatingJin-Seok Kim0Nag-Choul Choi1Ho Young Jo2Radioactive Waste Disposal Research Division, Korea Atomic Energy Research Institute, Daejeon 34057, KoreaDepartment of Rural Systems Engineering, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, KoreaDepartment of Earth and Environmental Sciences, College of Science, Korea University, Seoul 02841, KoreaBauxite residue (red mud), which is an industrial byproduct, contains valuable trace elements. Solid NH<sub>4</sub>Cl was used as a chlorinating agent during the microwave heating of red mud to convert trace elements into soluble metal chloride. Red mud was heated using microwave ovens under various conditions (i.e., with the addition of solid NH<sub>4</sub>Cl and with a range of microwave output powers and microwave heating times). Leaching tests were then conducted using deionized (DI) water on the microwave-heated red mud to leach trace elements from red mud. V, Cr, and As were selectively leached from the microwave heated red mud slurry (30% water content), whereas Mn, Cu, Co, Ni, Zn, and Pb were selectively leached from the microwave-heated red mud with the addition of solid NH<sub>4</sub>Cl. The oxides of V, Cr, and As in red mud could be transformed into metal chlorides by chlorination, which are insoluble in water, or could be easily volatilized when red mud was microwave-heated in the presence of solid NH<sub>4</sub>Cl. On the other hand, the oxides of Mn, Cu, Co, Zn, Ni, and Pb in red mud could be heated rapidly by microwave irradiating, resulting in metal chlorides in the presence of solid NH<sub>4</sub>Cl. Those metal chlorides are relatively soluble in water, leading to higher leaching efficiency for microwave-heated red mud with the addition of solid NH<sub>4</sub>Cl. Experimental results suggest that trace elements from red mud can be selectively leached by microwave heating of red mud without or with the addition of solid NH<sub>4</sub>Cl.https://www.mdpi.com/2075-4701/11/8/1281red mudtrace elementsmicrowave heatingammonium chlorideleaching |
| spellingShingle | Jin-Seok Kim Nag-Choul Choi Ho Young Jo Selective Leaching Trace Elements from Bauxite Residue (Red Mud) without and with Adding Solid NH<sub>4</sub>Cl Using Microwave Heating Metals red mud trace elements microwave heating ammonium chloride leaching |
| title | Selective Leaching Trace Elements from Bauxite Residue (Red Mud) without and with Adding Solid NH<sub>4</sub>Cl Using Microwave Heating |
| title_full | Selective Leaching Trace Elements from Bauxite Residue (Red Mud) without and with Adding Solid NH<sub>4</sub>Cl Using Microwave Heating |
| title_fullStr | Selective Leaching Trace Elements from Bauxite Residue (Red Mud) without and with Adding Solid NH<sub>4</sub>Cl Using Microwave Heating |
| title_full_unstemmed | Selective Leaching Trace Elements from Bauxite Residue (Red Mud) without and with Adding Solid NH<sub>4</sub>Cl Using Microwave Heating |
| title_short | Selective Leaching Trace Elements from Bauxite Residue (Red Mud) without and with Adding Solid NH<sub>4</sub>Cl Using Microwave Heating |
| title_sort | selective leaching trace elements from bauxite residue red mud without and with adding solid nh sub 4 sub cl using microwave heating |
| topic | red mud trace elements microwave heating ammonium chloride leaching |
| url | https://www.mdpi.com/2075-4701/11/8/1281 |
| work_keys_str_mv | AT jinseokkim selectiveleachingtraceelementsfrombauxiteresidueredmudwithoutandwithaddingsolidnhsub4subclusingmicrowaveheating AT nagchoulchoi selectiveleachingtraceelementsfrombauxiteresidueredmudwithoutandwithaddingsolidnhsub4subclusingmicrowaveheating AT hoyoungjo selectiveleachingtraceelementsfrombauxiteresidueredmudwithoutandwithaddingsolidnhsub4subclusingmicrowaveheating |