|
|
Arsenic speciation in mining wastes - case studies in systems dominated by ferric sulfoarsenates
Jelenová, Helena ; Drahota, Petr (advisor) ; Filippi, Michal (referee) ; Jurkovič, Ľubomír (referee)
The aim of the thesis is to study behavior and mineralogy of arsenic in mine wastes with high levels of FeIII and SVI . Three methodological studies are related to (i) identification and characterization of secondary arsenic phases using a Raman spectrometry, (ii) chemical fractionation of arsenic in mine waste materials as observed by optimized sequential extraction, (ii) and investigation of thermodynamic properties of zýkaite. The mineralogy and mobility of arsenic was studied in mine waste material of five dumps located at three sites (Kaňk near Kutná Hora, Jedová jáma near Vejprty, and Dlouhá Ves) and in stalactite samples from two abandoned underground mines (Plavno and Mikulov near Teplice). Mineralogical and geochemical characterization of samples included standard methods and techniques. Chemical composition of solid and liquid (pore water, leachates) samples was performed using a XRF, ICP OES, ICP MS, etc. X-ray diffraction, Raman spectrometry and electron microscope equipped with microanalysis were the most frequent techniques used for mineralogical characterization of the solids. The results showed that the speciation of arsenic in the solid phase significantly varied among the studied sites and was a function of total concentration as well as proportion of the major components of...
|
|
|
Evaluation of sequential extraction for speciation of arsenic in mining wastes
Grösslová, Zuzana ; Drahota, Petr (advisor) ; Vaněk, Aleš (referee)
ii SUMMARY This master thesis deals with selectivity assessment of an arsenic sequential extraction procedure for evaluating mobility in mine wastes. A modified sequential extraction procedure was designed on the basis of preliminary tests of extraction efficiency and selectivity for the synthetic As mineral phases (scorodite, amorphous iron arsenate, schwertmannite, goethite, jarosite) and five natural samples (Kaňk, Dlouhá Ves, Giftkies, Roudný) that were previously characterized for As concentration and speciation. The modified sequential extraction has five steps. The first leaching step was performed in nitrogen-purged deionized H2O for 10 hours; next step involved 0.01M NH4H2PO4 leaching for 16 hours. Phases in the third step were dissolved with 0.2M Tamm`s reagent in darkness for 2 hours. The fourth step was represented by 0.2M of Tamm`s reagent heated in water bath at 80řC for 4 hours. Strong acid solutions HCl/KClO3/HNO3 were used to leach sulphide phases in the last step. The testing of the sequential extraction procedure using model mixtures showed a good discrimination of several fractions: adsorbed arsenic, arsenic associated with poorly crystalline oxyhydroxide, hydroxosulfate and arsenate phases (amorphous iron arsenate, schwertmannite, ferrihydrite), arsenic associated with crystalline...
|
|
|
Evaluation of sequential extraction for speciation of arsenic in mining wastes
Grösslová, Zuzana ; Drahota, Petr (advisor) ; Vaněk, Aleš (referee)
ii SUMMARY This master thesis deals with selectivity assessment of an arsenic sequential extraction procedure for evaluating mobility in mine wastes. A modified sequential extraction procedure was designed on the basis of preliminary tests of extraction efficiency and selectivity for the synthetic As mineral phases (scorodite, amorphous iron arsenate, schwertmannite, goethite, jarosite) and five natural samples (Kaňk, Dlouhá Ves, Giftkies, Roudný) that were previously characterized for As concentration and speciation. The modified sequential extraction has five steps. The first leaching step was performed in nitrogen-purged deionized H2O for 10 hours; next step involved 0.01M NH4H2PO4 leaching for 16 hours. Phases in the third step were dissolved with 0.2M Tamm`s reagent in darkness for 2 hours. The fourth step was represented by 0.2M of Tamm`s reagent heated in water bath at 80řC for 4 hours. Strong acid solutions HCl/KClO3/HNO3 were used to leach sulphide phases in the last step. The testing of the sequential extraction procedure using model mixtures showed a good discrimination of several fractions: adsorbed arsenic, arsenic associated with poorly crystalline oxyhydroxide, hydroxosulfate and arsenate phases (amorphous iron arsenate, schwertmannite, ferrihydrite), arsenic associated with crystalline...
|
guest ::
