Outotec Oyj

Outotec (finland) Oy

Marko Lahtinen

Leena Lehtinen

Heikki Takala

Bror G Nyman

Sigmund P Fugleberg

Mikko Ruonala

Timo Haakana

Aimo Järvinen

Jari Tiihonen

Kurt Svens

Marika Jyrälä

Stig-Göran Huldén

Matti Vuokko

Sigmund Fugleberg

A method and apparatus for converting an iron-bearing residue generated in a hydrometallurgical process that contains small amounts of soluble heavy metals into a stable form by means of a neutralizing agent. The residue is elutriated and the elutriated residue is fed into at least one stabilization or homogenization reactor, into which a neutralizing agent is also routed, and the homogenous mixing together of the residue and neutralizing agent takes place by means of a helix mixer, where the ratio of the diameter of the mixer to the diameter of the reactor is 0.75-0.99.

Method and apparatus for homogenizing and stabilizing an iron-bearing residue

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 purpose of the invention is to remove copper selectively from a concentrated zinc sulphate solution by ion exchange. The method enables a significant reduction in the use of zinc powder during the solution purification of zinc sulphate solution and makes possible to avoid usage of arsenic or antimony trioxides as a precipitation chemical. The method is to be combined with the chloride removal that occurs as a sub-stage of solution purification.

Method for the removal of copper from a zinc sulphate solution

The invention relates to method for leaching zinc-containing materials in connection with the electrolytic recovery of zinc. According to this method, the feed materials i.e. zinc calcine and zinc sulphide, are leached in three stages, in which he sulphuric acid content of the stages rises in accordance with the direction in which the solids are moving. The solids and solution formed in the leaching stages are routed throughout the process countercurrently in relation to each other.

Method for recovery of zinc by countercurrent leaching

This invention relates to a method for the removal of iron as hematite from a zinc sulphate solution in atmospheric conditions during the electrolytic preparation of zinc. According to the method, the pH of the iron-containing solution is adjusted to a value of at least 2.7, oxygen-containing gas is fed into the solution and part of the hematite thus formed is recirculated to the precipitation stage.

Method for precipitating iron from a zinc sulphate solution as hematite

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