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Sigmund P Fugleberg

Stig-Erik Hultholm

Bror G Nyman

Jussi K Rastas

Jaakko T Poijarvi

Matti H&auml;m&auml;l&auml;inen

Pertti Pekkala

Mikko Ruonala

Seppo O Heimala

Marko Lahtinen

Timo T Koivunen

Markku T Saarela

Kurt Svens

Panu Talonen

Aimo E Jarvinen

Marja Riekkola-Vanhanen

Terry Holohan

Kari Knuuttila

Sitg-Erik Hultholm

Asko Parviainen

Kari Knuutila

Seppo I Blomquist

Kaj-Henrik Lindroos

Aimo J&auml;rvinen

Hannu J Pouru

Jaakko I Poijarvi

Stig-Göran Huldén

Sulphidic zinc concentrate usually also includes small amounts of rare metals such as indium and gallium. If the content of these metals in the raw material is sufficiently high, their recovery may be economically worthwhile. In the method according to the invention the recovery of indium and other desirable rare metals takes place in a zinc leaching process, in which at least part of the sulphidic concentrate is leached directly without roasting.

Method for recovering rare metals in zinc leaching process

The invention relates to a method for the leaching of oxidized ores and in particular zinc ores. The ore, wherein the valuable metals are at least partially in silicate form, are routed to an acidic leaching stage in conditions where the silicate decomposes and the valuable metal ion comes into the solution. During leaching the silicate ion first dissolves, but simultaneously decomposes and is precipitated as silica.

Method for the precipation of silica in connection with zinc ore leaching

The invention relates to a method for the hydrolytic precipitation of iron as jarosite from a sulphate-containing solution in connection with zinc recovery from zinc calcine. The recovey contains neutral leach, ferrite leach, zinc electrolysis and iron precipitation stages. The ferrite included in the calcine is leached with return acid of the electrolysis after which the iron present in ferrous form is neutralized and routed to an iron precipitation stage, where the iron is oxidised to the trivalent form using an oxygen-containing gas. Also present in the precipitation stage arc Na, K or NHions and jarosite nuclei.

Method for the hydrolytic precipitation of iron

The invention relates to a method for the precipitation of nickel from an aqueous solution containing its sulphate as a metallic powder suitable as an alloying element for refined steel. In this method, nickel reduction takes place continuously in one or several autoclaves at a temperature of 80-180&deg; C. and hydrogen pressure of 1-20 bar, whereby the production capacity can be raised significantly, compared to batch processes made in correspondingly dimensioned devices or equipment.

Method for the reduction of nickel from an aqueous solution

The invention relates to a method for the precipitation of nickel from its aqueous solution as a metal powder using hydrogen. The aqueous solution containing nickel compounds is neutralised first with an earth alkali or alkali compound so the nickel precipitates as nickel hydroxide or as an alkaline salt, after which reduction is performed in the presence of a catalyst in ion form in atmospheric or close to atmospheric conditions preferably as a continuous process.

Method for the reduction of nickel

The invention relates to a method for leaching zinc concentrate in atmospheric conditions in the presence of trivalent iron. It is essential that the zinc concentrate is fed into conditions where in addition to trivalent iron, there are also jarosite nuclei. The sulfuric acid content of the leaching step is maintained within the region 10-40 g/l, and the temperature within the region 80&deg; C.&mdash;the solution boiling point, and into the leaching step there is fed oxygen, so that the zinc concentrate is dissolved and the iron is precipitated as jarosite.

Method for leaching zinc concentrate in atmospheric conditions

The invention relates to a method for leaching sulfidic nickel matte and particularly copper rich nickel matte, as well as for leaching said matte together with a metallic copper and/or copper-nickel matte. The leach of nickel matte is carried out as pressure leach in one or several stages by means of copper sulfate.

Method for leaching nickel from nickel matte

Method for recovering nickel hydrometallurgically from two different

The invention relates to a process for leaching nickel and copper from nickel-copper matte formed in pyrometallurgical nickel production by means of a multi-stage process. It is essential of the invention that the leaching of nickel takes place in at least two stages in conditions where free sulfuric acid is essentially absent, and that in these stages, the leaching of the nickel content of the matte is mainly carried out with copper as the oxidizer.

Method for leaching nickel-copper matte employing substantially neutral

The invention relates to a method for recovering zinc from a zinc oxide bearing material containing silicates. According to the method, the leaching of zinc compounds is carried out in circumstances where the silicates remain undissolved and consequently do not cause filtering problems. The silicate bearing residue is treated in a Waelz process, so that the major part of the silicic acid contained in the silicates is combined in the iron silicate slag formed in the Waelz process, and the zinc is returned into leaching mainly in oxidic form.

Method for leaching material containing zinc oxide and zinc silicate

The present invention relates to a method for recovering valuable metals contained in various metallurgic waste precipitates and dusts, and also to a method for forming of the rest of the waste precipitate or dust a slightly soluble product suited for further processing. The recovery of valuable metals and the forming of slightly soluble products is carried out in a suspension smelting furnace, in which case the smelting of the precipitates and dusts is mainly reducing.

Method for recovering metal contents of metallurgic waste precipitates

According to the method of the invention, at least one or several of the metals nickel, cobalt and copper can be selectively precipitated as sulphide by aid of elemental sulphur from aqueous solutions containing other metals such as zinc. The temperature of the reaction is above the melting point of sulphur. The precipitation is carried out with a pH value below 2. The metals to be precipitated can be present in the solution either as oxides or sulphates. If the metals are sulphates, the sulphide of at least one of the metals is prepared to crystal seeds in the solution before precipitation.

Method for precipitating and separating metals

The invention relates to a method for recovering various valuable materials in connection with the hydrometallurgical production of zinc. The method is particularly suited for feeding different types of raw materials into the various stages of a process carried out in atmospheric conditions. Valuable materials such as lead, silver and gold are recovered by means of the said method.

Hydrometallurgic method for processing raw materials containing zinc

The purpose of the method is to remove chlorides and fluorides from a valuable metal raw material by leaching the raw material into sulphuric acid solution and by crystallizing the valuable metal sulphate selectively out of the solution. The valuable metal sulphate crystals are washed in sulphuric acid solution, and the recovered dechlorinated and defluorinated crystals are leached into water and conducted into electrolysis. The sulphuric acid solution employed in the raw material leaching and in the crystal washing is preferably the same as the return acid of the electrolysis. Chlorides and fluorides are removed from the mother liquor of crystallization in the bleed.

Hydrometallurgical method for treating valuable metal raw materials

The residual acid mixture containing metals which has been produced in the steel pickling process is regenerated to become new HF/HNO.sub.3 pickling acid by applying H.sub.2 SO.sub.4 addition and evaporation. The metal sulphate salt produced in evaporation is converted into scarcely soluble iron jarosite Na[Fe.sub.3 (SO.sub.4).sub.2 (OH).sub.6 ] and chrome and nickel hydroxide, the last mentioned metal hydroxide being obtained as a separately utilizable precipitate. The metal sulphate salt is separated from 60% H.sub.2 SO.sub.4 solution, wherein the main part of the salt is also crystallized. For promoting the crystallization, part of the salt is crystallized in a side line where 80% H.sub.2 SO.sub.4 concentration is used. The acid slurry produced is carried back to the crystallizing stage in the main line.

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Pori, Finland

Sigmund P Fugleberg