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Norilsk Nickel Harjavalta Oy

Promeca-consulting Oy

Jussi Rastas

Pekka J Saikkonen

Lars SNÅRE

Pekka Saikkonen

The invention relates to a method for recovering non-ferrous metals, particularly nickel, cobalt, copper, zinc, manganese and magnesium, from materials containing said metals by converting said non-ferrous metals into sulphates by means of melt and melt coating sulphation, i.e. by a thermal treatment under oxidizing conditions within a temperature range of 400 to 800&deg; C., during which a reaction mixture is formed containing at least one said non-ferrous metal, iron(III)sulphate and alkali metal sulphate, and appropriate reaction conditions are selected to substantially prevent iron(III)sulphate from thermally decomposing to hematite, and finally, said non-ferrous metals are recovered as metallic compounds. In the method of the invention, a process is formed around the melt and melt coating sulphation, which comprises nine steps. The invention is particularly characterized by the manner of pelletizing the material to be fed into step 2 with an alkali metal (Na, K) sulphate&mdash;sulphuric acid&mdash;water solution, during which the hematite (Fe,O,) contained in the feed material will at a suitable temperature react with sulphuric acid and form hydrous iron(III)sulphate which together with sodium sulphate also acts as the bonding agent required in the pelletizing.

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Fin-02700 Kauniainen, Finland

Jussi Rastas