The present invention relates to a process for preparing novel, monodisperse ion exchangers having chelating functional groups, and their use for adsorbing metal compounds, in particular, heavy metal compounds and noble metal compounds, and also for extracting alkaline-earth metals from saline solutions from alkali metal chloride electrolysis. A second folding portion includes a second folding roller pair consisting of the common roller and a second roller, thereby forming a second fold on the sheet in a second nip. The imagoes of Musca Domestica lay eggs in the environment. A leading-side portion of the slider is movable relative to the first tongue portion. The first and second ports are coupled by the first polarization plane, and the first and third ports are coupled by the second polarization plane. The casting mold is formed by baking the mulled sand in such a manner that at least part of the sulfate compound retains water of crystallization therein and the borate compound is once fused and then cured.