The Experts below are selected from a list of 9 Experts worldwide ranked by ideXlab platform
Paul L. Brown - One of the best experts on this subject based on the ideXlab platform.
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Coupled chemistry and transport modelling of sulphidic waste rock dumps at the Aitik mine site, Sweden
Applied Geochemistry, 2005Co-Authors: Claire M. Linklater, Daniel J. Sinclair, Paul L. BrownAbstract:Abstract The recently developed geochemical modelling code, SULFIDOX, has been applied to simulate weathering of a waste rock dump at the Aitik mine site, Sweden. SULFIDOX models the key chemical and physical processes in the dump temporally and spatially (in two dimensions). The following processes are represented: gas and heat transport; water infiltration; aqueous speciation; mineral dissolution/oxidation and precipitation. Field observations at the site suggest that sulphide oxidation rates within the dump are variable. Although the major part of the dump is Oxidising slowly, there are pockets of more highly Oxidising Material, particularly toward the dump edges. Using SULFIDOX, several models of the dump were investigated: (i) a dump wholly comprised of slowly Oxidising Material (representing a case where water flow paths are such that no rapidly Oxidising regions are accessed); (ii) a dump wholly comprised of the more rapidly Oxidising Material (representing the opposite (and probably unlikely) extreme, where water flows only through rapidly Oxidising regions in the dump); and (iii) a dump comprising a mixture of both slowly and more rapidly Oxidising Material, that more closely represents the mix of Material in the dump. All the models studied gave O2 depth profiles consistent with those observed in probe holes at the site, and confirmed that only a minimal amount of heat production would be expected in the dump due to the role of exothermic sulphide oxidation reactions. The models suggested that a medium-term steady-state, with respect to effluent chemistry, would be achieved after 3–4 years. Based on sulphide consumption rates during this steady-state period, the time periods required to consume all the sulphide in the dump range from a few hundred to many thousands of years. Using the mixed model, and based on a mixture containing 86% slowly and 14% rapidly Oxidising Material, the calculated effluent chemistry was in good agreement with the observed effluent chemistry. Improvements with respect to the K concentrations were possible by including precipitation of a K-bearing secondary mineral such a K-jarosite in the model. Results from the more rapidly Oxidising model suggested that gypsum precipitation might be expected in those regions of the dump containing this Material. In summary, the SULFIDOX modelling code has been used successfully to reproduce observed data for the Aitik waste-rock dump. Using SULFIDOX, valuable insight was gained in relation to the temporal and spatial evolution of the dump.
Claire M. Linklater - One of the best experts on this subject based on the ideXlab platform.
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Coupled chemistry and transport modelling of sulphidic waste rock dumps at the Aitik mine site, Sweden
Applied Geochemistry, 2005Co-Authors: Claire M. Linklater, Daniel J. Sinclair, Paul L. BrownAbstract:Abstract The recently developed geochemical modelling code, SULFIDOX, has been applied to simulate weathering of a waste rock dump at the Aitik mine site, Sweden. SULFIDOX models the key chemical and physical processes in the dump temporally and spatially (in two dimensions). The following processes are represented: gas and heat transport; water infiltration; aqueous speciation; mineral dissolution/oxidation and precipitation. Field observations at the site suggest that sulphide oxidation rates within the dump are variable. Although the major part of the dump is Oxidising slowly, there are pockets of more highly Oxidising Material, particularly toward the dump edges. Using SULFIDOX, several models of the dump were investigated: (i) a dump wholly comprised of slowly Oxidising Material (representing a case where water flow paths are such that no rapidly Oxidising regions are accessed); (ii) a dump wholly comprised of the more rapidly Oxidising Material (representing the opposite (and probably unlikely) extreme, where water flows only through rapidly Oxidising regions in the dump); and (iii) a dump comprising a mixture of both slowly and more rapidly Oxidising Material, that more closely represents the mix of Material in the dump. All the models studied gave O2 depth profiles consistent with those observed in probe holes at the site, and confirmed that only a minimal amount of heat production would be expected in the dump due to the role of exothermic sulphide oxidation reactions. The models suggested that a medium-term steady-state, with respect to effluent chemistry, would be achieved after 3–4 years. Based on sulphide consumption rates during this steady-state period, the time periods required to consume all the sulphide in the dump range from a few hundred to many thousands of years. Using the mixed model, and based on a mixture containing 86% slowly and 14% rapidly Oxidising Material, the calculated effluent chemistry was in good agreement with the observed effluent chemistry. Improvements with respect to the K concentrations were possible by including precipitation of a K-bearing secondary mineral such a K-jarosite in the model. Results from the more rapidly Oxidising model suggested that gypsum precipitation might be expected in those regions of the dump containing this Material. In summary, the SULFIDOX modelling code has been used successfully to reproduce observed data for the Aitik waste-rock dump. Using SULFIDOX, valuable insight was gained in relation to the temporal and spatial evolution of the dump.
Daniel J. Sinclair - One of the best experts on this subject based on the ideXlab platform.
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Coupled chemistry and transport modelling of sulphidic waste rock dumps at the Aitik mine site, Sweden
Applied Geochemistry, 2005Co-Authors: Claire M. Linklater, Daniel J. Sinclair, Paul L. BrownAbstract:Abstract The recently developed geochemical modelling code, SULFIDOX, has been applied to simulate weathering of a waste rock dump at the Aitik mine site, Sweden. SULFIDOX models the key chemical and physical processes in the dump temporally and spatially (in two dimensions). The following processes are represented: gas and heat transport; water infiltration; aqueous speciation; mineral dissolution/oxidation and precipitation. Field observations at the site suggest that sulphide oxidation rates within the dump are variable. Although the major part of the dump is Oxidising slowly, there are pockets of more highly Oxidising Material, particularly toward the dump edges. Using SULFIDOX, several models of the dump were investigated: (i) a dump wholly comprised of slowly Oxidising Material (representing a case where water flow paths are such that no rapidly Oxidising regions are accessed); (ii) a dump wholly comprised of the more rapidly Oxidising Material (representing the opposite (and probably unlikely) extreme, where water flows only through rapidly Oxidising regions in the dump); and (iii) a dump comprising a mixture of both slowly and more rapidly Oxidising Material, that more closely represents the mix of Material in the dump. All the models studied gave O2 depth profiles consistent with those observed in probe holes at the site, and confirmed that only a minimal amount of heat production would be expected in the dump due to the role of exothermic sulphide oxidation reactions. The models suggested that a medium-term steady-state, with respect to effluent chemistry, would be achieved after 3–4 years. Based on sulphide consumption rates during this steady-state period, the time periods required to consume all the sulphide in the dump range from a few hundred to many thousands of years. Using the mixed model, and based on a mixture containing 86% slowly and 14% rapidly Oxidising Material, the calculated effluent chemistry was in good agreement with the observed effluent chemistry. Improvements with respect to the K concentrations were possible by including precipitation of a K-bearing secondary mineral such a K-jarosite in the model. Results from the more rapidly Oxidising model suggested that gypsum precipitation might be expected in those regions of the dump containing this Material. In summary, the SULFIDOX modelling code has been used successfully to reproduce observed data for the Aitik waste-rock dump. Using SULFIDOX, valuable insight was gained in relation to the temporal and spatial evolution of the dump.
Kenneth Möller - One of the best experts on this subject based on the ideXlab platform.
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Thermo-oxidative stability of PP waste films studied by imaging chemiluminescence
Polymer Degradation and Stability, 2001Co-Authors: Gustav Ahlblad, P. Gijsman, Björn Terselius, Anna Jansson, Kenneth MöllerAbstract:Imaging chemiluminescence (ICL) was used to study the oxidative stability of PP waste films and of unstabilised PP particles for comparison. It was found that the unstabilised particles oxidised homogeneously with no induction period, whereas stabilised PP waste films showed a considerable distribution of induction times sometimes affected by the presence of threadlike defects. Individual specimens of a population of PP films all showed a sigmoidal increase of the CL intensity after the induction period. A sequence of chemiluminescence images showed a propagating oxidation front and a perfect match of the fraction of Oxidising Material covered by the front and the increase in chemiluminescence intensity. The role of physical spreading in the oxidation of stabilised PP Material was clearly demonstrated. On artificial recycling of these films ICL showed a significant change in the oxidative stability (residual lifetime) much earlier than FTIR (carbonyl index) and DSC (oxidation induction temperature).
Gustav Ahlblad - One of the best experts on this subject based on the ideXlab platform.
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Thermo-oxidative stability of PP waste films studied by imaging chemiluminescence
Polymer Degradation and Stability, 2001Co-Authors: Gustav Ahlblad, P. Gijsman, Björn Terselius, Anna Jansson, Kenneth MöllerAbstract:Imaging chemiluminescence (ICL) was used to study the oxidative stability of PP waste films and of unstabilised PP particles for comparison. It was found that the unstabilised particles oxidised homogeneously with no induction period, whereas stabilised PP waste films showed a considerable distribution of induction times sometimes affected by the presence of threadlike defects. Individual specimens of a population of PP films all showed a sigmoidal increase of the CL intensity after the induction period. A sequence of chemiluminescence images showed a propagating oxidation front and a perfect match of the fraction of Oxidising Material covered by the front and the increase in chemiluminescence intensity. The role of physical spreading in the oxidation of stabilised PP Material was clearly demonstrated. On artificial recycling of these films ICL showed a significant change in the oxidative stability (residual lifetime) much earlier than FTIR (carbonyl index) and DSC (oxidation induction temperature).
