The hydrolysis of iron(III) from sulphate bearing aqueous solutions was investigated to significantly improve the neutralization of acidic mineral effluents. Both theoretical and experimental studies were undertaken. A literature review and a thermodynamic analysis of the Fe(III)-SO$ sb4$-H$ sb2$O system were performed. / The thermodynamic analysis determined that Fe(III)-sulphato complexes dominate in the acidic pH range (pH $<$ 4) while at neutral to mild alkaline pH range Fe(OH)$ sb3 sp circ sb{ rm (aq)}$ is the dominant species. It was found that a relationship exists between the precipitation pH and the sulphate content of the precipitate (17% at pH 3, 7-9% at pH 6 and 1-2% at pH 9) and it was attributed in part to the existence of the precursor Fe(III)-sulphato complexes and in part to SO$ sb4 sp{2-}$ adsorption on the Fe(III) oxyhydroxide solid phase. / Several variables were examined for their influence on the properties of the iron(III) hydrolysis products, such as: pH, neutralization rate, temperature, agitation rate, sulphate concentration and ionic strength. Tests were performed in a batch reactor and NaOH was selected as the most effective neutralizing reagent. Treatment sludges were characterized physically (e.g., solids content, settling rate, etc.), chemically and morphologically, while the treated effluent was examined for residual iron(III) content. These tests proved only partially successful as the precipitates produced were highly amorphous with low solids content (${<8 %}$) and poor settling (${<3}$ m/hr). However, exceptionally good precipitates were produced when the hydrolysis tests were performed under supersaturation control. This work led to the development of a novel approach to neutralization of effluents involving sludge recycling and staged neutralization in order to maintain a low and controlled supersaturation level. Via this novel method partially crystallized precipitates of excellent properties were produced at 50$ sp circ$C after eight recycles. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.68062 |
| Date | January 1993 |
| Creators | Zinck, Janice M. |
| Contributors | Demopoulos, George P. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Engineering (Department of Mining and Metallurgical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001401622, proquestno: AAIMM94308, Theses scanned by UMI/ProQuest. |
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