The recovery of critical elements in recycling processes of complex high-tech products is often limited when applying only mechanical separation methods. A possible route is the pyrometallurgical processing that allows transferring of important critical elements into an alloy melt. Chemical rather ignoble elements will report in slag or dust. Valuable ignoble elements such as lithium should be recovered out of that material stream. A novel approach to accomplish this is enrichment in engineered artificial minerals (EnAM). An application with a high potential for resource efficient solutions is the pyrometallurgical processing of Li ion batteries. Starting from comparatively simple slag compositions such as the Li-Al-Si-Ca-O system, the next level of complexity is reached when adding Mg, derived from slag builders or other sources. Every additional component will change the distribution of Li between the compounds generated in the slag. Investigations with powder X-Ray diffraction (PXRD) and electron probe microanalysis (EPMA) of solidified melt of the five-compound system Li2O-MgO-Al2O3- SiO2-CaO reveal that Li can occur in various compounds from beginning to the end of the crystallization. Among these compounds are Li1−x(Al1−xSix)O2, Li1−xMgy(Al)(Al3/2y+xSi2−x−3/2y)O6, solid solutions of Mg1−(3/2y)Al2+yO4/LiAl5O8 and Ca-alumosilicate (melilite). There are indications of segregation processes of Al-rich and Si(Ca)-rich melts. The experimental results were compared with solidification curves via thermodynamic calculations of the systems MgO-Al2O3 and Li2O-SiO2-Al2O3.
Chain architecture and degree of
crystallinity of polymers strongly
influence the solid–liquid equilibrium of binary polymer solvent
systems. Especially, for explaining the principle of common polymer
separation techniques a fair prediction of solid–liquid equilibria
of polymer solvent systems is of crucial importance. Herein, based
on the framework of lattice cluster theory, a theory is developed
considering additional configurational entropy contributions due to
the semicrystalline nature and molecular architecture of polymers.
For calculating solid–liquid equilibria of semicrystalline
polymer solvent systems an analytical equation is derived. Model calculations
are performed to study the impact of molecular mass, molecular architecture,
degree of crystallinity, and solvent size and structure on solid–liquid
equilibria of polymer solvent systems. The model calculation results
are discussed qualitatively in terms of experimental observations
in thermal fractionation techniques. The theory is further applied
to calculate solid–liquid equilibria of fractions of ethylene/α-olefins
with different amounts of comonomers dissolved in 1,2,4-trichlorobenzene
and compared with experimental CRYSTAF data. We could show that the
theory enables the calculation of solid–liquid equilibria of
polymer solvent systems, where chain architecture of both polymer
and solvent and the semicrystallinity are incorporated. The work contributes
to the understanding of polymer solubility. Hence, valuable clues
are offered about the principal mechanism of thermal polymer separation
techniques, and further a solid base to suggest improvements for experimental
separation methods is provided.
The
solvent uptake in equilibrium of a highly cross-linked epoxy o-cresol novolac resin in water, isopropanol, and heptane
was experimentally measured and modeled with the perturbed-chain statistical
association fluid theory (PC-SAFT) equation of state. As suggested
in the literature, PC-SAFT was combined with a network term, which
takes additional elastic forces into account. The model parameters
of the epoxy resin were generated by fitting them to the measured
solvent uptake in pure substances and to the density of the epoxy
resin, which provided a very good agreement with the experimental
data. Furthermore, the solvent uptake in the mixtures isopropanol/water
and isopropanol/heptane was predicted in very good agreement to the
experimental data. For the first time, a thermodynamic model was developed
to calculate the solvent uptake in an epoxy resin.
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