Characteristic Analysis of Acid Mine Drainage Precipitates for the Optimization of Rare Earth Extraction Processes

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.

Name thesis:degree_name

MS

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Mining Engineering

Department dc:contributor.department

Mining Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2018

Author dc:creator

• Saber, Scott William

Chair dc:contributor.committeechair

• Noble, Christopher Aaron

Committee members dc:contributor.committeemember

• Ziemkiewicz, Paul F.
• Sarver, Emily A.

• Acid Mine Drainage
• Rare Earth Extraction
• pH Adjustment
• X-ray Fluorescence

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

vt_gsexam:17487

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/97826