Abstract: In processes for removing ruthenium by distilling RuO4 from ruthenate-containing solutions with these steps of the treatment of the ruthenate-containing solution with an oxidising agent, distilling off of the RuO4 formed, absorbing the RuO4 from step II in hydrochloric acid, the oxidising agent is recycled into step I following step III. The processes can be carried out in reactor modules with A a reactor with a stirrer, gas inlet and gas outlet, B at least one scrubber connected in series downstream with the gas outlet via a line, C one or several gas absorbers connected in series downstream with the at least one scrubber via lines, E at least one line from the optionally last absorber for recycling into the gas inlet of the reactor or into a further module or into a facility for off-gas treatment.

Abstract: Process for removing the noble metal from noble metal-containing moulded catalyst bodies, comprising these steps of A leaching the noble metal from loosely heaped moulded catalyst bodies, B removing the mother liquor, C automated conveying of the moulded bodies into a centrifuge, D renewed leaching, E separating off of the residual mother liquor by centrifuging.

Abstract: Process for removing the noble metal from noble metal-containing moulded catalyst bodies, comprising these steps of A leaching the noble metal from loosely heaped moulded catalyst bodies, B removing the mother liquor, C automated conveying of the moulded bodies into a centrifuge, D renewed leaching, E separating off of the residual mother liquor by centrifuging.

Abstract: In processes for removing ruthenium by distilling RuO4 from ruthenate-containing solutions with these steps of the treatment of the ruthenate-containing solution with an oxidising agent, distilling off of the RuO4 formed, absorbing the RuO4 from step II in hydrochloric acid, the oxidising agent is recycled into step I following step III. The processes can be carried out in reactor modules with A a reactor with a stirrer, gas inlet and gas outlet, B at least one scrubber connected in series downstream with the gas outlet via a line, C one or several gas absorbers connected in series downstream with the at least one scrubber via lines, E at least one line from the optionally last absorber for recycling into the gas inlet of the reactor or into a further module or into a facility for off-gas treatment.

Abstract: The present invention relates to a method for coloring ceramic surfaces, wherein the surfaces are treated with an aqueous solution of alkali metal or ammonium dithiosulphatoaurate(I) with a gold concentration of 0.1-10% by weight, the water is evaporated and the dithiosulphatoaurate(I) is decomposed at temperatures of 300-1400.degree. C.