Characteristic Analysis of Acid Mine Drainage Precipitates for the Optimization of Rare Earth Extraction Processes
| dc.contributor.author | Saber, Scott William | en |
| dc.contributor.committeechair | Noble, Christopher Aaron | en |
| dc.contributor.committeemember | Ziemkiewicz, Paul F. | en |
| dc.contributor.committeemember | Sarver, Emily A. | en |
| dc.contributor.department | Mining Engineering | en |
| dc.date.accessioned | 2020-04-18T06:00:21Z | en |
| dc.date.available | 2020-04-18T06:00:21Z | en |
| dc.date.issued | 2018-10-25 | en |
| dc.description.abstract | Acid mine drainage (AMD) forms when sulfur bearing rocks such as pyrite, are exposed to air and water. The oxidation of these minerals leads to the generation of sulfuric acid, which in turn mobilizes metals such as iron, aluminum, manganese, and others. If left untreated, AMD can cause severe harm to the surrounding ecosystem. By law, mining companies are required to treat AMD, often by oxidizing the contaminated water, raising the pH with a chemical additive, and precipitating the metals out of solution. Recent studies at West Virginia University and Virginia Tech have shown that AMD and the treatment precipitates (AMDp) are enriched in rare earth elements (REEs). Given the importance of REEs to modern technology, as well as potential supply restrictions, subsequent research has attempted to identify promising methods to extract and recovery REEs from AMD and AMDp. Prior studies have shown that the physical characteristics of AMDp can vary considerably from site to site, and a robust processes scheme must account for any site-specific disparities. To better understand the inherent variability of AMDp, a scientific study was commissioned to investigate a standard method of characterizing AMDp for the optimization of rare earth extraction processes. The tests developed in this work define the total acid dose needed to dissolve AMDp at various target pH points. Through the course of the study, over 150 unique AMDp samples were evaluated, and comparative analyses were conducted on samples from different sites as well as replicate samples from the same sites. The resultant dataset was analyzed using an empirical model, and a statistical analysis was conducted to correlate the model parameters and other AMDp physical properties. Relationships between elemental assays, moisture, and fitting parameters of the empirical models were found. These results ultimately led to a recommendation for future treatment of AMD and prospective sites. | en |
| dc.description.abstractgeneral | Acid mine drainage (AMD) is a longstanding environmental issue that is caused when sulfur-bearing rocks are exposed to the environment during the mining process. By law, companies are required to treat AMD prior to discharging the water back into the environment. This treatment process creates a waste byproduct, AMD precipitate, that largely consists of metal hydroxides, including iron, aluminum, manganese, and others. Historically, AMD precipitate has been considered an undesirable waste that must be carefully disposed either in old mine workings or in permanent storage cells. However, recent research has shown that AMD precipitate contains elevated concentrations of rare earth elements (REEs). REEs are a group of chemically similar elements that are well known for their use in several modern technologies, including magnets, catalysts, glasses, light-weight metal alloys, and other high-tech uses. REEs are often sparsely concentrated in nature and rarely form ore deposits of a commercial grade. As a result, several private companies and government agencies have sought alternative sources of REEs. Prior research has shown that AMD precipitate may be a suitable alternative source; however, the chemical and physical nature of AMD varies considerably between different sites. This research seeks to utilize a standard characterization test to identify the characteristics of AMD precipitate that ultimately dictate process amenability. Throughout the course of the study, over 150 unique AMD precipitate samples were analyzed, and the cumulative results show which class of sites constitute the most promising prospecting targets. | en |
| dc.description.degree | MS | en |
| dc.format.medium | ETD | en |
| dc.identifier.other | vt_gsexam:17487 | en |
| dc.identifier.uri | http://hdl.handle.net/10919/97826 | en |
| dc.language.iso | en | en |
| dc.publisher | Virginia Tech | en |
| dc.rights | In Copyright | en |
| dc.rights.uri | http://rightsstatements.org/vocab/InC/1.0/ | en |
| dc.subject | Acid Mine Drainage | en |
| dc.subject | Rare Earth Extraction | en |
| dc.subject | pH Adjustment | en |
| dc.subject | X-ray Fluorescence | en |
| dc.title | Characteristic Analysis of Acid Mine Drainage Precipitates for the Optimization of Rare Earth Extraction Processes | en |
| dc.type | Thesis | en |
| thesis.degree.discipline | Mining Engineering | en |
| thesis.degree.grantor | Virginia Polytechnic Institute and State University | en |
| thesis.degree.level | masters | en |
| thesis.degree.name | MS | en |
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