%0 Journal Article
%A Schneider, A.
%A Schmidt, H.
%A Meven, M.
%A Brendler, E.
%A Kirchner, J.
%A Martin, G.
%A Bertau, M.
%A Voigt, W.
%T Lithium extraction from the mineral zinnwaldite: Part I: Effect of thermal treatment on properties and structure of zinnwaldite
%J Minerals engineering
%V 111
%@ 0892-6875
%C Amsterdam [u.a.]
%I Elsevier Science
%M FZJ-2017-08126
%P 55 - 67
%D 2017
%X Lithium has become an energy critical element and thus the security of supply is of great importance. As a local German resource, attention was directed towards the mica-type mineral zinnwaldite. It represents a lithium-rich siderophyllite and corresponds to an intermediate polylithionite–siderophyllite solid solution with high contents of fluoride. Mineral samples from the deposit Zinnwald/Cínovec at the German/Czech border were analyzed and characterized by a variety of methods, particularly concerning its thermal behavior. Understanding the thermal behavior of the mica gives the opportunity to develop new and cost-efficient methods for lithium extraction.Investigations with different spectroscopic methods revealed the decomposition mechanisms. Starting at 300 °C, oxidation of Fe2+ catalyzed the dehydroxylation of the mica by dehydrogenation. This is followed by a dehydroxylation similar to the mechanism of dioctahedral micas. At higher temperatures, the release of HF was detected. At about 800 °C the precipitation of hematite was observed. The complete decomposition of Zinnwaldite takes place at 900 °C, it is accompanied by the liberation of SiF4 and leads to the formation of several solid decomposition products. By means of single-crystal diffraction using X-rays and neutrons the structural changes could be identified after annealing at 700 °C. The results point to a transformation into a polylithionite-like structure, the end member of the solid solution series.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000406729800006
%R 10.1016/j.mineng.2017.05.006
%U https://juser.fz-juelich.de/record/840621