Changes in precipitate mineralogy, morphology, and major and trace elemental concentrations and associations throughout five coal mine drainage remediation systems in Pennsylvania and Maryland that treat discharges of varying chemistries were investigated. The precipitates are dominantly (>70%) goethite with minor amounts of other iron and/or manganese oxides and quartz. Crystallinity varies throughout an individual system and is a function of the treatment system and how rapidly ferrous iron oxidizes, precipitates, and settles. Precipitates formed earlier in the systems have the highest crystallinity; less crystalline precipitates are associated with enhanced sorption of trace metals. High surface area and vacancies within the goethite structure enable incorporation of metals from mine drainage polluted waters. Sorption affinities follow the order Al>Zn>Co=Ni>Mn. As pH increases in the individual treatment systems toward the pHpzc, arsenic sorption decreases and aluminum and transition metal sorption increases. Sulfate, sodium and ferrous iron potentially influence the sorption of trace metals.
A sequential extraction procedure was developed to determine how trace elements are associated with the precipitates. Arsenic, cobalt, manganese, nickel and zinc are not released until the iron hydroxide phase is dissolved, indicating these metals are either tightly sorbed to the surface or incorporated into the hydroxide structure. Cobalt and nickel preferentially partition into a manganese oxide/hydroxide phase (if present), over the iron hydroxide phase. The stability of the precipitate controls the long-term mobility of trace metals. Associated trace metals will remain unavailable to the environment as long as the precipitate is not altered.
Additionally, spatial and temporal variations between precipitates formed from a net-alkaline coal mine discharge were examined. The precipitates are all moderately crystalline goethite with minor variations in morphology and composition. They contain 20 30% more iron than the natural mined iron oxides examined in this study, and concentrations of manganese, nickel and zinc are up to three orders of magnitude lower than the natural iron oxides. Geochemical analysis indicates that mine drainage precipitates formed from net-alkaline waters are of a higher purity than natural iron oxides. Results of this study have implications for disposal, resource recovery, and the optimization of mine drainage passive remediation systems.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-05062003-143445 |
| Date | 28 May 2003 |
| Creators | Kairies, Candace Lianne |
| Contributors | Dr. Rosemary C. Capo, Dr. Robert S. Hedin, Dr. Harold B. Rollins, Dr. Edward G. Lidiak, Dr. Brian W. Stewart |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu:80/ETD/available/etd-05062003-143445/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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