nikkelilateriittimalmityyppejä

Nikkelilateriittimalmityypit (nickel laterite ore types) refer to a group of nickel-bearing mineral deposits that form in tropical and subtropical regions through the weathering of ultramafic rocks. These deposits are a major source of nickel globally, particularly for stainless steel production. They are classified into two main categories based on their mineralogy and nickel content: limonite-type and saprolite-type.

Limonite-type deposits, also known as oxide-laterites, are characterized by the presence of iron oxyhydroxides, such as goethite and limonite, which give them a reddish-brown color. Nickel in these deposits is primarily associated with these iron minerals and is often present in hydrous silicate structures or adsorbed onto iron surfaces. They typically have lower nickel grades but higher iron content compared to saprolite types. Extraction from limonite ores usually involves hydrometallurgical processes, such as acid leaching, due to the difficulty of smelting these high-iron, low-sulfur materials.

Saprolite-type deposits, also called silicate-laterites, are formed deeper within the weathering profile. They are richer in magnesium and silica and contain nickel primarily in silicate minerals, such as garnierite, which is a mix of serpentine and talc minerals containing nickel. Saprolite ores generally have higher nickel grades than limonite ores but lower iron content. These ores are more amenable to direct smelting processes, although hydrometallurgical routes are also employed. The formation of both limonite and saprolite ores involves complex geological processes of rock weathering, leaching of soluble elements, and concentration of insoluble metals.