A novel approach for an automated liquid/liquid extraction system—principle and application for the determination of several trace contaminants in highly alloyed steels and base alloys
AbstractA novel automated liquid/liquid extraction system was developed for the determination of trace contaminants in unalloyed, alloyed and highly alloyed steels and super alloys. In the presented batch extraction system the aqueous phase and the non-water miscible organic phase were brought into close phase contact by high-speed stirring with a magnetic stir bar. Iodide complexes of Ag, Bi, Cd, Pb, Sb, Sn, Tl, and Zn were extracted from aqueous steel digests into 4-methylpentan-2-one (MIBK) containing 20 g L−1 trioctylphosphine oxide. Ag, Bi, Cd, Pb, and Tl were extracted quantitatively whereas the extraction yields of Sb, Sn, and Zn were 83%, 61% and 75% respectively. Using high resolution continuum source flame AAS (HR-CS-FAAS) for analyte quantification the method was validated using 21 certified steel reference materials (CRMs).
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Science and technology of tributyl phosphate
Volume 3 is primarily devoted to the PUREX process, with special emphasis on its chemistry. Chapter 1 describes the general process layout and special flowsheets applied in various plants, together with the chemistry of both the product elements and the process reagents. Two more chapters deal with the details of fission product and neptunium behavior in the process. Another nuclear application of tributyl phosphate (TBP) solvent extraction is the recovery of plutonium values from fuel fabrication scrap and similar wastes, which is treated in Chapter 4. Computer modeling of extraction processes is an exciting and most useful area where great progress has been made in recent years, and this is dealt with in Chapter 5. Finally, there are extraction procedures where TBP does not primarily act as an extractant by itself, but instead is used as a phase modifier to improve the compatibility of reactants in a different extractant-diluent system.
Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 mol/L H2SO4 at 90°C for 2 h. After the sample is roasted at 900°C for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900°C, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000°C. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.