Self-sealing isolation and immobilization: a geochemical approach to solve the environmental problem of waste acidic jarosite
| Autor: | R.D. Schuiling, H.A.van der Sloot, Mei Ding |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
business.industry
Precipitation (chemistry) Diffusion fungi technology industry and agriculture Mineralogy Lessivage engineering.material complex mixtures Pollution Chemical engineering Geochemistry and Petrology Fly ash Jarosite engineering Environmental Chemistry Coal Leaching (metallurgy) business Porosity Geology |
| Zdroj: | Applied Geochemistry. 17:93-103 |
| ISSN: | 0883-2927 |
| DOI: | 10.1016/s0883-2927(01)00099-3 |
| Popis: | Mimicking geochemical processes to solve environmental problems was implemented in dealing with waste acidic jarosite and alkaline coal fly ash. By placing these two chemically different materials adjacent to one another, a self-sealing layer was formed at the interface between both wastes, isolating and immobilizing chemical constituents in the process. A series of leaching experiments were performed on each material separately to study the release behavior of the principal constituents. Radiotracer experiments were conducted to explore diffusion and reaction of constituents such as Fe 3+ in a combined jarosite/fly ash system. A model has been developed to simulate the coupled processes of diffusion and precipitation taking into account porosity change due to pore filling by precipitates. The formation of a self-sealing isolation layer in a hypothetical jarosite/fly ash disposal site was modelled. Leaching results indicate that the release of elements from jarosite is much larger than that from fly ash, and that the highly pH dependent release of Fe, Al, and Zn was controlled by the solubility of their hydroxides. Leaching results also suggest that precipitation reactions can be expected to occur at the interface between jarosite and alkaline coal fly ash where a large pH gradient exists. Radiotracer experiments showed that accumulation of constituents occurred at the interface. Modeled Fe 3+ profiles in layered jarosite/fly ash were well validated by experiments. Modeling results also showed that with the accumulation of constituents at the interface, a new layer with low porosity was formed. Application of this model suggests that there is a potential use to form a self-sealing layer in jarosite/fly ash co-disposal sites. |
| Databáze: | OpenAIRE |
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