Outotec Oyj

Seppo Heimala

Mikko Ruonala

Stig-Erik Hultholm

Olli Hyvärinen

Jaakko Leppinen

Matti Hämäläinen

Teemu Ritasalo

Heikki Laurila

Veikko Palosaari

Tuula Hämäläinen, Legal Representative

The invention relates to a method for leaching a material containing a valuable metal and precipitating the valuable metal as a fine-grained powder by changing the electrochemical potential of an intermediary metal in the solution. In the leaching stage the intermediary metal or substance of the electrolyte solution is at a high degree of oxidation and in the precipitation stage another electrolyte solution is routed into the solution, in which the intermediary metal or substance is at a low degree of oxidation. After the precipitation stage the solution containing the intermediary is routed to electrolytic regeneration, in which part of the intermediary is oxidised in the anode space back to a high potential value and part is reduced in the cathode space to its low value.

Method for the production of metal powder

The present invention relates to a method for the treatment of copper-bearing materials, such as copper concentrates, so that the impurities and gangue minerals in the materials, such as silicates, are in effect removed completely.

Method for the treatment of copper-bearing materials

The invention relates to a method for controlling the partial pressure of oxygen when mutually separating minerals in the different process steps of the separation process. In order to control the partial pressure of oxygen, the gases fed in the different process steps are recirculated in an essentially closed gas circulation created around the equipment used in the different process steps, so that the gas recirculation is controlled by measuring the potential of the slurry containing valuable minerals.

Method for controlling oxygen when separating minerals from a slurry

The invention relates to a method for recovering gold from a sulphidic concentrate, particularly one containing arsenopyrite and/or pyrite, hydro-metallurgically. The concentrate is first subjected to leaching with a concentrated solution of alkali chloride and copper (II) chloride, by means of which the copper minerals and some of the gold in the concentrate are made to dissolve. Elemental sulphur and precipitated iron and arsenic compounds are separated from the leaching residue using physical separation methods, whereby the first intermediate is obtained, which contains gold-bearing sulphide minerals and gangue minerals as well as the gold that remains undissolved. The free gold that remains undissolved is separated by means of gravity separation methods. After gravity separation, additional comminution is carried out, after which the sulphide minerals are decomposed and the gold-containing solution or residue is routed to the concentrate leaching circuit.

Method for the recovery of gold from sulphide concentrate

The invention relates to a method for processing concentrates, particularly concentrates produced from copper sulfide-based ores. According to the method, the concentrate () to be processed, obtained from ore concentration, is divided into two parts, to a concentrate () mainly containing poorly soluble components, and to a concentrate () mainly containing well soluble components. The concentrate () containing well soluble components is conducted to a leaching step (), and the solution () obtained from said leaching step is conducted to at least one conversion step (), and to the conversion step () that is located first in the flowing direction, there is fed the concentrate () containing poorly soluble components. In the conversion step () that is located first in the flowing direction, at least the copper contained in the solution is converted into sulfidic form by means of the sulfide-form iron of the concentrate () containing poorly soluble components, and at least part of the solution () obtained from the conversion step () is returned to the leaching step ().

Method for producing concentrates

The invention relates to a method for smelting sulfidic copper concentrates, in which method copper sulfide bearing material is smelted in a smelting furnace () for creating blister copper and slag. According to the method, at least part () of the feed of the smelting furnace () is copper sulfide bearing () material obtained by means of sulfide bearing material () that is fed into the hydrometallurgic further processing () of slag () created in the smelting process.

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Pori, Finland

Seppo Heimala