Effect of post-precipitation conditions on surface properties of colloidal metal sulphide precipitates
| dc.contributor.author | Mokone, T P | |
| dc.contributor.author | Lewis, A E | |
| dc.contributor.author | van Hille, R P | |
| dc.date.accessioned | 2016-07-28T11:28:33Z | |
| dc.date.available | 2016-07-28T11:28:33Z | |
| dc.date.issued | 2012 | |
| dc.date.updated | 2016-07-12T13:16:52Z | |
| dc.description.abstract | Metal sulphide precipitation is important in several hydrometallurgical processes. However, challenges exist in solid–liquid separation and recovery of the colloidal precipitates produced in some systems. This study presents the effect of downstream processing options on the surface properties of colloidal particles produced during copper and zinc sulphide precipitation. XRD and EDAX characterisation indicated the copper precipitate was a mixture of covellite (63%) and copper hydroxysulphate (37%), while the zinc sulphide was more pure, but less crystalline. The effect on surface charge and aggregation tendency of different concentrations of background electrolyte (1–100 mM KCl), suspension pH, aqueous sulphide, a divalent (Ca2+) and trivalent (Al3+) cation were studied. The magnitude of the negative surface charge increased with increasing suspension pH (pH 6 to pH 11) for both copper and zinc precipitates. The addition of aqueous sulphide (0.84 mM) to the zinc precipitate resulted in a significant decrease in the zeta potential and suppressed aggregation, due to adsorption of the negatively charged sulphide ions. This effect was reduced at high ionic strength. A higher sulphide concentration was required to replicate the phenomenon with the copper precipitate due to sulphidisation of the copper hydroxysulphate initially. Addition of a divalent cation (Ca2+) to the suspension had little effect on the surface charge of the particles and did not promote aggregation. However, addition of a small amount (0.5 mM) of Al3+ ions resulted in a significant change in surface charge (−30 to −10 mV for copper and −23 mV to −5 mV for zinc) and subsequent aggregation. The results of this study show that downstream processing of colloidal metal sulphide precipitates, produced where supersaturation cannot be managed, can lead to effective solid–liquid separation, by changing the surface properties of the precipitate. | en_ZA |
| dc.identifier | http://dx.doi.org/10.1016/j.hydromet.2012.02.015 | |
| dc.identifier.apacitation | Mokone, T. P., Lewis, A. E., & van Hille, R. P. (2012). Effect of post-precipitation conditions on surface properties of colloidal metal sulphide precipitates. <i>Hydrometallurgy</i>, http://hdl.handle.net/11427/20935 | en_ZA |
| dc.identifier.chicagocitation | Mokone, T P, A E Lewis, and R P van Hille "Effect of post-precipitation conditions on surface properties of colloidal metal sulphide precipitates." <i>Hydrometallurgy</i> (2012) http://hdl.handle.net/11427/20935 | en_ZA |
| dc.identifier.citation | Mokone, T. P., Lewis, A. E., & van Hille, R. P. (2012). Effect of post-precipitation conditions on surface properties of colloidal metal sulphide precipitates. Hydrometallurgy, 119, 55-66. | en_ZA |
| dc.identifier.issn | 0304-386X | en_ZA |
| dc.identifier.ris | TY - Journal Article AU - Mokone, T P AU - Lewis, A E AU - van Hille, R P AB - Metal sulphide precipitation is important in several hydrometallurgical processes. However, challenges exist in solid–liquid separation and recovery of the colloidal precipitates produced in some systems. This study presents the effect of downstream processing options on the surface properties of colloidal particles produced during copper and zinc sulphide precipitation. XRD and EDAX characterisation indicated the copper precipitate was a mixture of covellite (63%) and copper hydroxysulphate (37%), while the zinc sulphide was more pure, but less crystalline. The effect on surface charge and aggregation tendency of different concentrations of background electrolyte (1–100 mM KCl), suspension pH, aqueous sulphide, a divalent (Ca2+) and trivalent (Al3+) cation were studied. The magnitude of the negative surface charge increased with increasing suspension pH (pH 6 to pH 11) for both copper and zinc precipitates. The addition of aqueous sulphide (0.84 mM) to the zinc precipitate resulted in a significant decrease in the zeta potential and suppressed aggregation, due to adsorption of the negatively charged sulphide ions. This effect was reduced at high ionic strength. A higher sulphide concentration was required to replicate the phenomenon with the copper precipitate due to sulphidisation of the copper hydroxysulphate initially. Addition of a divalent cation (Ca2+) to the suspension had little effect on the surface charge of the particles and did not promote aggregation. However, addition of a small amount (0.5 mM) of Al3+ ions resulted in a significant change in surface charge (−30 to −10 mV for copper and −23 mV to −5 mV for zinc) and subsequent aggregation. The results of this study show that downstream processing of colloidal metal sulphide precipitates, produced where supersaturation cannot be managed, can lead to effective solid–liquid separation, by changing the surface properties of the precipitate. DA - 2012 DB - OpenUCT DP - University of Cape Town J1 - Hydrometallurgy LK - https://open.uct.ac.za PB - University of Cape Town PY - 2012 SM - 0304-386X T1 - Effect of post-precipitation conditions on surface properties of colloidal metal sulphide precipitates TI - Effect of post-precipitation conditions on surface properties of colloidal metal sulphide precipitates UR - http://hdl.handle.net/11427/20935 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/20935 | |
| dc.identifier.vancouvercitation | Mokone TP, Lewis AE, van Hille RP. Effect of post-precipitation conditions on surface properties of colloidal metal sulphide precipitates. Hydrometallurgy. 2012; http://hdl.handle.net/11427/20935. | en_ZA |
| dc.language | eng | en_ZA |
| dc.publisher | Elsevier | en_ZA |
| dc.publisher.institution | University of Cape Town | |
| dc.rights | Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) | * |
| dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/4.0/ | en_ZA |
| dc.source | Hydrometallurgy | en_ZA |
| dc.source.uri | http://www.sciencedirect.com/science/journal/0304386X | |
| dc.subject.other | Metal sulphide precipitation Colloidal particles Surface charge Colloid–surface chemistry Solid–liqu | |
| dc.title | Effect of post-precipitation conditions on surface properties of colloidal metal sulphide precipitates | en_ZA |
| dc.type | Journal Article | en_ZA |
| uct.type.filetype | Text | |
| uct.type.filetype | Image | |
| uct.type.publication | Research | en_ZA |
| uct.type.resource | Article | en_ZA |