Voest-alpine Aktiengesellschaft

Gerhard Lazar

Ernst Eichberger

Walter Hans

Hans D Reiterer

The process for recovering metals of the 1.sup.st, 2.sup.nd, 4.sup.th, 5.sup.th, 6.sup.th, 7.sup.th and 8.sup.th sub-group of the periodic law from solutions of their salts, particularly from solutions containing hydrochloric acid contemplates as the first process step a neutralization (1) for precipitating the metals from their acid metal salt solutions in the form of hydroxides or carbonates. The precipitate is pressed (4), and via conduits (9, 10) finally divided metal of the metal having been present as a salt as well as a carbon source originating of waste materials, particularly in form of ground heat setting synthetic plastics materials such as phenolic resins, amine formaldehyde resins, epoxide resins, polyesters, and also CaCO.sub.3 is added. All components of this mixture must be used in a fine-grained state and preferably with a maximum particle size of 0.5 mm. Subsequently, the mixture is via a conduit (11) introduced into a reduction reactor (12) in which this mixture is mechanically agitated and heated to a temperature above the melting point of the metal in consideration for reducing the metal being present as a salt. For recovering the heat content of the effluent gasses as well as for purifying the effluent gasses, the effluent gasses formed during the reduction and containing CO and CO.sub.2 are subjected to a post-combustion (15) and used for drying the pressed metal precipitate. The effluent gasses coming from the drying zone are washed (18), the washed water being preferably used for heating the metal salt solutions to be neutralized.

Process for recovering of metals from solutions of metal salts

In a method of recovering heavy metals from filter residues containing metal oxides, metal hydroxides or metal carbonates, the residues are dried and reduced during heat supply in the presence of carbon-containing reducing agents. The metal-containing filter residues having a water content of 30 to 80% are dried in a three-compartment rotary drier (triplex drier), wherein a product having a grain size of 0.1 to 5 mm and a packing density of 0.4 to 1.2 kg/l results, which, after the addition of the carbon-containing reducing agents, is introduced into a crucible furnace at a filling height of 0.4 to 1.5 m. It is heated to a temperature above the melting point of the metal to be recovered. The filling height is kept approximately constant during the volume reduction of the material to be reduced occurring at an increased temperature by refilling the batch.

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Linz, Austria

Gerhard Lazar