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Address : A.P. Karpinsky Russian Geological Research Institute (VSEGEI), Russian Federation
Celebration date : 29 Monday September 2008
Author name : Mordberg, Leonid

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  • Article title : Nickel laterites of Russia and Kazakhstan
    Article type : Mineral processing
    Location : International Geological Congress,oslo 2008

    Fulltext :

    Ancient nickel lateritic deposits related to weathering of ultrabasiters are known in Baltic Shield, Urals, salair and a few regions of Kazakhstan. Ni laterites of the SE slope of the Baltic Shield are the oldest known in the world: their age is referred to Carboniferous. They are confined to multiple small massifs and eroded in high degree so, thet they represent an interest rather scientific than industrial. The main ore minerals are montmorillonite and goethite, that is unusual for younger profiles.
    Ni deposits of the Urals long from Serov in the North to Kimpersay in the South forming a belt wich is accompanied by deposits of Turgay depression from SE. All the deposits of Urals have been forming during the Late Triassic - Early Jurassic and Early to Late Cretaceous. Remobilisation and redistribution of Ni is related to Tertiary processes.
    Ni lateritic deposits of Salair are poorly studied, although one can believe their resources are comparable with those of Urals. The most well-known is Belininsk deposit of typical lateritic appearance. The deposits of Kazakhstan are disseminated among a few regions; besides Kimpersay and Turgay, the deposits related to Gornostay and Charsk massifs are of industrial interest.
    Blanket-like, linear and combined types of deposits have tradidionally been distinguishing by Russian geologists. All listed types represent a result of the same geochemical process. Ni has a dual nature of concentration during lateritic weathering. Within laterite and saprolite, Ni concentrates in situ due to removal of alcaline and alcaline earth elements as well as Si. Ni accommofdates in oxides and hydroxides (goethite, haematite, maggemite, magnetite) within laterite zone and in layered silicates (smectites) within saprolite zone.
    Infiltration of partly dissolved by weathering Ni and its following precipitation leads to formation of rich quartz-garnierite ore in the zones of faults and deep karst cavities along the contacts of serpentinites and carbonate rocks. Two described mechanisms cannot exist without each other: lateritic profile cannot develop without developing intensive drainage system which provides downward solution movement and leaching primary minerals; zones of foults and contacts with carbonate rocks play the role of such systems also being geochemical barriers for Ni presipitation.
    It should be noted, that within the Urals and Kazakhstan, redeposited Ni deposits of Karstic origin similar to those of Attica are not known yet, although high degree of erosion level has been traced in several regions. Possibly, perspectives of new discoveries can be related with this type of Ni deposits, for instance, in the Eastern slope of the Urals.

     
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