dc.contributor.author | Mwakio, P. Tole | |
dc.date.accessioned | 2014-07-10T08:11:31Z | |
dc.date.available | 2014-07-10T08:11:31Z | |
dc.date.issued | 1987 | |
dc.identifier.citation | Tole, M. P. (1987). Thermodynamic and kinetic aspects of formation of bauxites. Chemical geology, 60(1), 95-100. | en_US |
dc.identifier.uri | http://www.sciencedirect.com/science/article/pii/0009254187901148 | |
dc.identifier.uri | http://hdl.handle.net/11295/72421 | |
dc.description.abstract | Experiments in which cleavage nepheline samples were reacted with aqueous solutions at fixed pH's and temperature were carried out in the laboratory. The chemistry of the solution as a function of time was monitored, as well as the chemistry of the nepheline surfaces.
At 25°C, Al derived from the nepheline stays in solution due to slow precipitation kinetics of Al(OH)3. At 60° and 80°C, precipitation of Al(OH)3 is so rapid that Al concentration in solution is below 0.05 ppm. This indicates that precipitation kinetics favour the formation of bauxite deposits in tropical regions (i.e. T⩾25°C), but not in temperate regions.
Precipitation products on the surface of the nepheline fragments at 60° and 80°C depend on the pH. At pH 3.0, an amorphous aluminium silicate (proto-kaolinite?) is formed. At pH>7.0, the precipitated phase contains, in addition to Al and Si, high amounts of Na and K (proto-muscovite?). The optimum pH for the formation of bauxite is in the range 5–7. These results are in agreement with thermodynamic calculations. | en_US |
dc.language.iso | en | en_US |
dc.publisher | University of Nairobi | en_US |
dc.title | Thermodynamic and kinetic aspects of formation of bauxites | en_US |
dc.type | Article | en_US |
dc.type.material | en_US | en_US |