Xu, Yi
(2014)
Investigation of Environmental Impacts of Beneficial Reuse of Bauxite Residue in Coal-Refuse Area Based on a Hydro-Thermal-Geochemical Model.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The waste of coal mining results in numerous piles, which produce acid mine drainage (AMD) and deteriorate water quality. Also ions from the refuse piles, including sulfate, ferric and ferrous iron are continuously leached from these coal-refuse piles. Bauxite residue, a byproduct from alumina refining process, has a relatively high pH. If bauxite residue is innovatively mixed with the coal refuse, the issues associated with these two wastes (e.g., high and low pH values) may be solved. Also, the concentrations of leached ions will be reduced significantly.
This study investigates the impacts of bauxite residue + coal refuse on the environment through a hydro-thermal-geochemical model (HTGCM) in combination with field measurements and laboratory analysis. This dynamic model accounts for the processes of water cycle, pyrite oxidation, oxygen diffusion, solute transport, thermal transport, pH calculation and other secondary reactions. The Distributed Hydrology Soil and Vegetation Model (DHSVM) is the basic framework based on which the HTGCM model is developed. The HTGCM model developments include three main stages: (1) improving the DHSVM hydrological model and coupling the algorithm of pyrite oxidation to DHSVM, (2) developing thermal transport and including the heat transport from the oxidation process, and (3) coupling a geochemical model and calculating more chemical reactions.
The modeling studies and the field observations lead to the following main findings: (1) the chemical concentrations in the amended zone are reduced while the pH value is ameliorated to be less acidic; (2) the chemical concentrations in the non-amended zone also decrease but not as significantly as in the amended zone in the short-term period; (3) it appears that there may be a range of preferred depth for the amended zone to be more effective; (4) heat released from the pyrite oxidation increases the soil temperature; (5) the effect of plants on soil temperature is restricted to a vegetation-impact depth; and (6) impacts of the amended zone on the deep non-amended zone can be seen through a long-term simulation.
This work provides new insights into the remediation studies and may lead to a paradigm shift in the AMD treatment strategy in the future.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
13 March 2014 |
| Date Type: |
Publication |
| Defense Date: |
17 October 2013 |
| Approval Date: |
13 March 2014 |
| Submission Date: |
18 November 2013 |
| Access Restriction: |
5 year -- Restrict access to University of Pittsburgh for a period of 5 years. |
| Number of Pages: |
163 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Civil and Environmental Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Hydro-thermal-geochemical model,
Acid mine drainage,
Coal refuse,
Bauxite residue,
Modeling |
| Date Deposited: |
13 Mar 2015 05:00 |
| Last Modified: |
13 Mar 2019 05:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/20014 |
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