Application of Nanotechnology in Mining Processes. Группа авторов
Arsenic (As)
Table 1.3 Different types of applications and the uses of REEs.
| Types of applications | REEs used and their functions | Reference |
| 1. Medical (La, Ce, Pr, Gd, Nd, Tb, Dy, Ho, Er, Tm, and Yb) | Lanthanum oxide nanoparticles can be used for magnetic resonance imaging (MRI).Cerium-doped lutetium orthosilicate is used to convert high-energy radiation to visible light for positron emission tomography (PET) imaging. This test is used to reveal tissue and organ function. Praseodymium oxide nanoparticles have been synthesized and used for cancer treatment as a radiotherapy technique.The treatment of skin cancer, as well as hair removal using a laser beam, was achieved by using Neodymium as crystals.The magnetic properties of Gadolinium are used to enhance MRI images of tumors and intravenous radio-contrast agents in MRI scans.A radioisotope Dy-165 has been employed in the treatment of rheumatoid knee effusions.Holmium-based solid-state lasers have been used for non-invasive medical procedures for treating cancers and kidney stones.Erbium-based lasers have been used in medical and dental practice.A radioisotope Tm-167 has been used as a power source in portable X-ray devices.A radioisotope Yb-176 can be used to produce Lu-177, which is known to be a promising radioisotope for medical applications. | [41] |
| 2. Telecommunication | Neodymium, terbium, and dysprosium are used in smart cell phones to enable them to vibrate. | [42] |
| 3. Electronics | Scandium (Sc) is used in electron-beam tubes in TV.Yttrium (Y) is used in the manufacture of capacitors, phosphors, microwave filters, glasses, oxygen sensors, radars, lasers and superconductors.Eu, Tb, Gd, and Ce are used in flat-screen displays. | [43] |
| 4. Automobile | La, Ce, Nd, and Pr are used as catalytic converters to efficiently control pollution in cars. | [44] |
| 5. Weaponry | Yttrium(Y) and Terbium (Tb) are used for laser targeting and weapons in combat vehicles. | [45] |
1.2.2 Rare-Earth Elements and Their Importance
Rare earth elements consist of the 15 lanthanide elements including yttrium (Y) and scandium (Sc) on the periodic table. These elements exhibit similarities in geochemical behavior because of their identical stable trivalent oxidation state (except Ce and Eu), systematic decrease in ionic radius and increasing atomic number [24]. Mineral deposits of REE typically occur in low concentrations as oxides or carbonates in a broad array of geologic formations in very few countries, and over 90% of REE production occurs in China [25]. This near-monopoly has created a conceivable handicap for other countries where REEs are not readily produced [10]. The demand for these REEs has increased tremendously over the years due to their extensive application in several scientific advancements (Table 1.3) owing to their unique magnetic, phosphorescent, and catalytic properties [26]. The extraction of these elements from their conventional ores is energy-intensive and alone is insufficient to satisfy the rising demand in the foreseeable future due to their strategic importance in modern technology [27, 28]. Consequently, it has prompted researchers, national governments, and private entities to develop possible techniques for recovering these elements from unconventional sources, such as AMD, to meet the rising demand. In the United States, a significant concentration of REE was found in precipitates formed during acid mine drainage treatment from coal tailings [10]. In Brazil, acid water generated in a uranium mine in the state of Minas Gerais was found to contain a total concentration of 126 ppm of REE significantly higher than acid waters generated from different mines worldwide [29]. Also, in the Guizhou province in southwestern China, the Xingren coalfield mine is reported to contain REE concentrations varying between 0.1 and 0.9 ppm [30]. Although the recovery of rare earth metals from AMD remains a great challenge as it is several orders of magnitude lower in this product than the conventional REE ores, it can be recovered using a low-cost nano-adsorbent if concentrated out of the liquid solution during the neutralization processes [31]. The emergence of nanotechnology has contributed tremendously to economic prosperity by providing solutions to some challenges facing modern-day technology [32]. In this chapter, a state-of-the-art technique will be presented using modified magnetic dendrimer nanoparticles to effectively recover REE from AMD after alkaline treatment. First, the generation of AMD and its environmental effect are highlighted, and then in the following sections the shortcomings of various remediation methods for AMD as background motivation for this method design are discussed.
1.2.3 Classical AMD Remediation and Treatment Methods
The effects of AMD on the environment are enormous, and several remediation technologies have been implemented (Figure