| Records |
| Author |
Evangelou, V.P. |
Title  |
Pyrite microencapsulation technologies: Principles and potential field application |
Type |
Journal Article |
| Year |
2001 |
Publication |
Ecological Engineering |
Abbreviated Journal |
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| Volume |
17 |
Issue |
2-3 |
Pages |
165-178 |
| Keywords |
mine water treatment Acid mine drainage Acidity Alkalinity Amelioration Coating Oxidation Surface reactions |
| Abstract |
In nature, pyrite is initially oxidized by atmospheric O2, releasing acidity and Fe2+. At pH below 3.5, Fe2+ is rapidly oxidized by T. ferrooxidans to Fe3+, which oxidizes pyrite at a much faster rate than O2. Commonly, limestone is used to prevent pyrite oxidation. This approach, however, has a short span of effectiveness because after treatment the surfaces of pyrite particles remain exposed to atmospheric O2 and oxidation continuous abiotically. Currently, a proposed mechanism for explaining non-microbial pyrite oxidation in high pH environments is the involvement of OH- in an inner-sphere electron-OH exchange between pyrite/surface-exposed disulfide and pyrite/surface-Fe(III)(OH)n3-n complex and/or formation of a weak electrostatic pyrite/surface-CO3 complex which enhances the chemical oxidation of Fe2+. The above infer that limestone application to pyritic geologic material treats only the symptoms of pyrite oxidation through acid mine drainage neutralization but accelerates non-microbial pyrite oxidation. Therefore, only a pyrite/surface coating capable of inhibiting O2 diffusion is expected to control long-term oxidation and acid drainage production. The objective of this study was to examine the feasibility in controlling pyrite oxidation by creating, on pyrite surfaces, an impermeable phosphate or silica coating that would prevent either O2 or Fe3+ from further oxidizing pyrite. The mechanism underlying this coating approach involves leaching mine waste with a coating solution composed of H2O2 or hypochlorite, KH2PO4 or H4SiO4, and sodium acetate (NaAC) or limestone. During the leaching process, H2O2 or hypochlorite oxidizes pyrite and produces Fe3+ so that iron phosphate or iron silicate precipitates as a coating on pyrite surfaces. The purpose of NaAC or limestone is to eliminate the inhibitory effect of the protons (produced during pyrite oxidation) on the precipitation of iron phosphate or silicate and to generate iron-oxide pyrite coating, which is also expected to inhibit pyrite oxidation. The results showed that iron phosphate or silicate coating could be established on pyrite by leaching it with a solution composed of: (1) H2O2 0.018-0.16 M; (2) phosphate or silicate 10-3 to 10-2 M; (3) coating-solution pH [approximate]5-6; and (4) NaAC as low as 0.01 M. Leachates from column experiments also showed that silicate coatings produced the least amount of sulfate relative to the control, limestone and phosphate treatments. On the other hand, limestone maintained the leachate near neutral pH but produced more sulfate than the control. |
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0925-8574 |
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July 01; Pyrite microencapsulation technologies: Principles and potential field application; file:///C:/Dokumente%20und%20Einstellungen/Stefan/Eigene%20Dateien/Artikel/10063.pdf; Science Direct |
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CBU @ c.wolke @ 10063 |
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37 |
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| Author |
Rees, B.; Bowell, R.; Dey, M.; Williams, K. |
| Title |
Passive treatment; a walk away solution? |
Type |
Journal Article |
| Year |
2001 |
Publication |
Mining Environmental Management |
Abbreviated Journal |
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| Volume |
9 |
Issue |
2 |
Pages |
7-8 |
| Keywords |
acid mine drainage; acidification; alkalinity; bacteria; bioremediation; buffers; chemical reactions; cost; effluents; ferric iron; ferrous iron; filtration; ground water; hydrolysis; iron; metals; monitoring; oxidation; permeability; pH; pollution; remediation; substrates; sulfate ion; suspended materials; water management; water pollution; water quality; water treatment; wetlands 22, Environmental geology |
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0969-4218 |
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| Notes |
Passive treatment; a walk away solution?; 2001-050826; References: 3; illus. United Kingdom (GBR); GeoRef; English |
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no |
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CBU @ c.wolke @ 5722 |
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265 |
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| Author |
Jarvis, A.P.; Younger, P.L. |
| Title |
Passive treatment of ferruginous mine waters using high surface area media |
Type |
Journal Article |
| Year |
2001 |
Publication |
Water Res. |
Abbreviated Journal |
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| Volume |
35 |
Issue |
15 |
Pages |
3643-3648 |
| Keywords |
mine water treatment passive treatment mine water accretion oxidation iron manganese water treatment |
| Abstract |
Rapid oxidation and accretion of iron onto high surface area media has been investigated as a potential passive treatment option for ferruginous, net-alkaline minewaters. Two pilot-scale reactors were installed at a site in County Durham, UK. Each 2.0m high cylinder contained different high surface area plastic trickling filter media. Ferruginous minewater was fed downwards over the media at various flow-rates with the objective of establishing the efficiency of iron removal at different loading rates. Residence time of water within the reactors was between 70 and 360s depending on the flow-rate (1 and 12l/min, respectively). Average influent total iron concentration for the duration of these experiments was 1.43mg/l (range 1.08-1.84mg/l; n=16), whilst effluent iron concentrations averaged 0.41mg/l (range 0.20-1.04mg/l; n=15) for Reactor A and 0.38mg/l (range 0.11-0.93mg/l; n=16) for Reactor B. There is a strong correlation between influent iron load and iron removal rate. Even at the highest loading rates (approximately 31.6g/day) 43% and 49% of the total iron load was removed in Reactors A and B, respectively. At low manganese loading rates (approximately 0.50-0.90g/day) over 50% of the manganese was removed in Reactor B. Iron removal rate (g/m3/d) increases linearly with loading rate (g/day) up to 14g/d and the slope of the line indicates that a mean of 85% of the iron is removed. In conclusion, it appears that the oxidation and accretion of ochre on high surface area media may be a promising alternative passive technology to constructed wetlands at certain sites. |
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0043-1354 |
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Oct; Passive treatment of ferruginous mine waters using high surface area media; 9; file:///C:/Dokumente%20und%20Einstellungen/Stefan/Eigene%20Dateien/Artikel/9698.pdf; AMD ISI | Wolkersdorfer |
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no |
| Call Number |
CBU @ c.wolke @ 9698 |
Serial |
27 |
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| Author |
Sottnik, P.; Sucha, V. |
| Title |
Moznosti upravy kysleho banskeho vytoku loziska Banska Stiavnica-Sobov. Remediation of acid mine drainage from Sobov Mine, Banska Stiavnica |
Type |
Journal Article |
| Year |
2001 |
Publication |
Mineralia Slovaca |
Abbreviated Journal |
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| Volume |
33 |
Issue |
1 |
Pages |
53-60 |
| Keywords |
acid mine drainage aluminum Banska Stiavnica Slovakia Central Europe copper Eh Europe gangue heavy metals iron manganese metals metamorphic rocks oxidation pH pollution precipitation pyrite quartzites reduction remediation Slovakia Sobov Mine sulfides vegetation waste disposal wetlands 22, Environmental geology |
| Abstract |
A waste dump formed during the exploitation of quartzite deposit in Sobov mine (Slovakia) produces large quantity of acid mine drainage (AMD) which is mainly a product of pyrite oxidation. Sulphuric acid--the most aggressive oxidation product--attacks gangue minerals, mainly clays, as well. This process lead to a sharp decrease of the pH values (2-2.5) and increase of Fe, Al and SO (super 2-) (sub 4) contents (TDS = 20-30 mg/1). Passive treatment system was designed to remediate AMD. Chemical redox reactions along with microbial activity cause a precipitation of mobile contamination into a more stable forms. The sulphides are formed in the anaerobic cell, under reducing conditions. Fe-, Al- oxyhydroxides are precipitated in the aerobic part of the system. Precipitation decreases the Fe and Al contents along with immobilization of some heavy metal closely related to oxyhydroxides. Besides oxidation, the wetland vegetation is an active part of on aerobic cell. The system has been working effectively since September 1999. The pH values of outflowing water are apparently higher (6.2-6.8) and contents of dissolved elements (Fe from 2.260 to 4.1; Al from 900 to 0.18; Mn from 51 to 23; Cu from 4.95 to 0.03 mg/l) is significantly lowers. |
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0369-2086 |
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Moznosti upravy kysleho banskeho vytoku loziska Banska Stiavnica-Sobov. Remediation of acid mine drainage from Sobov Mine, Banska Stiavnica; 2004-084366; References: 21; illus. incl. sects. Slovak Republic (SVK); GeoRef; Slovakian |
Approved |
no |
| Call Number |
CBU @ c.wolke @ 16534 |
Serial |
235 |
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| Author |
Rajaram, V. |
| Title |
Methodology for estimating the costs of treatment of mine drainage |
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Journal Article |
| Year |
2001 |
Publication |
Proceedings of the Seventeenth International Mining Congress and Exhibition of Turkey |
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Issue |
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Pages |
191-201 |
| Keywords |
mine water treatment |
| Abstract |
Tetra Tech developed worksheets for the U.S. Department of the Interior, Office of Surface Mining (OSM) to allow a consistent, accurate, and rapid method of estimating the costs of long-term treatment of mine drainage at coal mines, in accordance with the Surface Mining Control and Reclamation Act (SMCRA) of 1977. This paper describes the rationale for the worksheets and how they can be used to calculate costs for site-specific conditions. Decision trees for selection of alternative treatments for acidic or alkaline mine drainage are presented. |
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Methodology for estimating the costs of treatment of mine drainage; Isip:000171428500021; Times Cited: 0; ISI Web of Science |
Approved |
no |
| Call Number |
CBU @ c.wolke @ 17065 |
Serial |
163 |
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