Outotec Oyj

Cutokumpo Oyj

Leo Lindroos

Henri K Virtanen

Olli Järvinen

Olli Hyvärinen

Pekka Taskinen

The invention relates to a hydrometallurgical method for separating the precious metals and impurities of anode sludge obtained from copper electrolysis. According to the method, anode sludge copper is separated in atmospheric leaching; calcinated in two steps for separating selenium and for sulfatizing silver; the sulfatized silver is separated by leaching into a neutral aqueous solution, from which it can be separated by reduction or by extraction.

Method for processing anode sludge

The method and furnace according to the invention enable a continuous processing of anode slime and are particularly suited to be connected to a process where anode slime is treated by hydrometallurgic methods after roasting. In the method according to the invention, the slime containing valuable metals and selenium is dried, roasted, sulfatized and cooled. The method includes steps to be carried out in succession, in continuous operation, so that the slime forms a slime layer on the conveyor and is conveyed to be treated in successive drying, roasting, sulfatizing and sulfuric acid removal and cooling units.

Method and device for treating anode slime

The object of this invention is a method by which arsenic is removed from sulfuric acid solution, in which the sulfuric add concentration is at least 300 g/l, at a temperature of 50-105&deg; C. by reducing the arsenic in the solution with the aid of sulfur dioxide. The arsenic trioxide produced is crystallized from the sulfuric acid solution by cooling. The method is particularly suitable for use in connection with the electrolytic refining of metals, as in copper refining.

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Pori, Finland

Leo Lindroos