Varta Batterie Aktiengesellschaft

Varta Batterie Aktiengesellshaft

Klaus Kleinsorgen

Uwe Kohler

Alexander Bouvier

Andreas Folzer

Frank Lichtenberg

Gerhard Simon

Gunter Hofmann

Erich Munch

The invention relates to a process for recovering metals from used nickel/hydride storage batteries, in which storage battery scrap has been mechanically comminuted and divided into at least a coarse fraction and a fine fraction capable of being treated separately from one another. The process comprises the steps of digesting and dissolving the fine fraction with a mixture of sulfuric acid and hydrogen peroxide, performing a double sulfate precipitation of the rare earths by raising the pH, performing a precipitation of the iron and of the aluminum by further raising the pH, performing a solvent extraction of other metals to separate nickel and cobalt which remain in the aqueous phase from the other metals which are extracted into the organic phase. Optionally, the nickel and the cobalt can be separated from each other and, if desired, the mixed-metal rare earth component which has been recovered can be melted together with cobalt and nickel alloy for the fabrication of new batteries.

Process for the recovery of metals from used nickel/metal/rare earth

In the recycling of used nickel/metal hydride storage batteries, the battery scrap is dissolved in sulphuric acid after mechanical separation of the coarse constituents by magnetic and air separation. A solvent extraction is performed with the digestion solution, from which the rare earths (from the hydrogen-storage alloys in the negative electrodes) and iron and aluminum have been selected by precipitation, under conditions pH, choice of solvent, volumetric ratio of the phases) which are such that the aqueous phase contains nickel and cobalt in the same atomic ratio as that in which they were present in the scrap. This makes possible a joint recovery by simultaneous electrolysis, in which process the deposition product forms a master alloy which can be used, together with the precipitated rare earths which have been electrometallurgically reprocessed as misch metal, for the production of fresh hydrogen-storage alloys.

Process for the recovery of metals from used nickel/metal hydride

As an active material for its negative electrode, a hydrogen storage alloy for a Ni/H battery has the composition

Alkaline metal oxide/metal hydride battery

The positive electrode of a Ni/metal hydride accumulator is formed from a mass mixture of Ni(OH).sub.2 and an oxidation-resistant graphite. The stable graphite is notable for a high degree of crystallinity and a low ash content. In conventional Ni/metal hydride accumulators, cobalt compounds play an essential part in developing a conductive matrix within their positive nickel hydroxide electrodes, leading to reductive destruction of the matrix by severe high temperature short circuit testing. In contrast, the same accumulators, with positive electrodes produced according to the present invention, survive the test with only a temporary and slight decline in capacity.

Ni/metal hydride accumulator

An auxiliary electrode for improving the consumption of oxygen in a gas-tight, sealed alkaline secondary cell is comprised of a synthetic nonwoven fabric and a film rolled onto the fabric. The film is a PTFE-bound activated carbon, and the side of the nonwoven fabric receiving the film is first impregnated with an aqueous cellulose ether mixture to develop a three layer structure including a highly porous, hydrophobic layer made of the nonwoven material, left in its original state and facing the electrolyte or a gas supply, a hydrophilic impregnated layer, and a catalytically active hydrophobic consumption layer electrically connected with the cell's negative electrode and constituting the preferred location for oxygen reduction, at the resulting hydrophobic/hydrophilic transition layer. The auxiliary electrode is located outside of the ionic path between electrodes of opposite polarity, but in electron-conducting contact with the negative electrode, excluding the auxiliary electrode from unwanted interaction with the NO.sub.2 /NH.sub.3 --auto-discharge path.

Gas-tight, sealed alkaline secondary cell

In metering viscous paste from a paste pot onto a carrier tape using a scraper, uniform coating thickness is obtained by causing the scraper to oscillate relative to the paste in a plane parallel to the carrier tape, with a speed which equals at least the tear velocity between scraper and paste. The scraper projects into the paste to a depth at which the paste does not yet firmly adhere to the carrier, and holds back the excess paste free of torn-off portions even at high tape speeds. An important application of this method is in the production of raw sinter tape in connection with the manufacture of electrodes for galvanic elements.

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Kelkheim, Germany

Klaus Kleinsorgen