The carboniferous component of slimes in the electrolytic production of alkali metals (in our case, lithium) is studied for the first time with the aim to find nanostructures in it. The content of nanostructures in this component, which accounts for 10% of the slimes and can be separated by mild chemical treatment, is shown to be 2-4%. These structures are multiwall nanotubes or bundles of multiwall nanotubes, most of which are open. No twisted or single-wall nanotubes have been detected.