Filtering the unfilterable: tuning the mesostructure of precipitating silica gels to improve the filterability of acidic lixiviation slurries
Silica precipitation is a ubiquitous but deleterious phenomenon occurring in many hydrometallurgical processes. Indeed, silicon is often released during the dissolution of minerals under acidic leaching conditions. Eventually, it precipitates into a hard-to-filter silica gel, which has prompted some...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Académie des sciences
2024-12-01
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| Series: | Comptes Rendus. Chimie |
| Subjects: | |
| Online Access: | https://comptes-rendus.academie-sciences.fr/chimie/articles/10.5802/crchim.347/ |
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| Summary: | Silica precipitation is a ubiquitous but deleterious phenomenon occurring in many hydrometallurgical processes. Indeed, silicon is often released during the dissolution of minerals under acidic leaching conditions. Eventually, it precipitates into a hard-to-filter silica gel, which has prompted some efforts to hinder silica precipitation through pretreatment or extra dilution. However, these approaches are usually either mineral-specific or costly. Here, we propose a disruptive strategy based on controlling the gel’s mesostructure and therefore its filterability. We designed an alternative precipitation pathway consisting of adding extra silicate ions but at basic pH. Using small-angle X-ray scattering, we show that this pathway transforms the network of polymeric silica (“polymer gel”) obtained under highly acidic leaching conditions into a network of dense silica particles (“particle gel”). This structural compaction at the mesoscopic length scale cascades to the macroscale and leads to a drastic improvement in filterability by two orders of magnitude. Furthermore, we demonstrate that this method is generic by applying it successfully to both a model and real ore systems. |
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| ISSN: | 1878-1543 |