A. EXPORT & IMPORT NICKEL
Nickel ore host rock is period rock. According to Vinogradov ultra alkaline rocks have an average nickel content of 0.2%. The element nickel is present in the crystal lattice of minerals olivine and prosing, as a result of the substitution of Fe and Mg atoms. The process of substitution between Ni, Fe and Mg ions can be explained as radius and ion charge almost the same among these elements. Serpentinization process that occurs in period rocks due to the influence of hydrothermal solutions, will transform into rock serpentines rock period or serpentines rocks period. While the chemical and physical processes of air, water and turn heat to cool the working continuously, causing disintegration and decomposition of the host rock.
In the particular chemical weathering, water-rich soil CO2 from the air and decaying plants decompose minerals that are unstable (olivine and prosing) on ultra basic rocks, producing Mg, Fe, Ni-soluble; Si tends to form colloids of silica particles are very fine. In solution, Fe is oxidized and precipitated as ferric-hydroxide, eventually forming minerals such as geothit, limonite, and hematite near the surface. Together these minerals are participating element cobalt in small quantities.
Solution containing Mg, Ni, and Si continuously downwards during acidic solution, up to a condition where the atmosphere is quite neutral as a result of contact with the soil and rocks, there is a tendency to form deposits hydrosilikat. Contained nickel in silicate chains or hydrosilikat with the varying composition which may be deposited in crevices or cracks are known as veins garnierite and onyx. While the solution of the residue to form a compound called coprolite yellow reddish brown. Other elements such as Ca and Mg are dissolved as bicarbonate will be brought down to the extent of weathering and will be precipitated as dolomite, magnetite commonly fill in the gaps or cracks in the host rock. Field veins is known as the boundary between the zone of weathering instructions with fresh rock zone called weathering root (root of weathering).
Factors that affect the formation of nickel literate ores are:
a. Rock origin. Outcrop of origin is a key condition for the formation of deposits of nickel literate, wide ultra origin is rock base. In this case the ultra-alkaline rocks are: - there are elements of the most widely Ni among other rocks - minerals that have most easily weathered or unstable, such as olivine and prosing - have components that easily dissolves and gives the depositional environment good for nickel.
b. Climate. The change of the dry season and the rainy season where there is an increase and decrease in ground water level can also cause separation and accumulation process elements. Substantial differences in temperatures will help the mechanical weathering, which will happen cracks in rocks that will ease the process or chemical reaction in the rocks.
c. Chemical reagents and vegetation. What is meant by chemical reagents are the elements and compounds that help speed up the process of weathering. Ground water containing CO2 plays an important role in the process of chemical weathering. Humus acids cause the decomposition of rocks and can change the pH of the solution. Humus acids is closely related to vegetation. In this case, the vegetation will result in: • Water penetration can be deeper and more easily by following the path of the tree roots • accumulation of rain water will be much thicker basalts • This situation is an indication, where the forest was dense in a good environment will there are deposits of nickel that is thicker with higher levels. In addition, vegetation may serve to keep the results of mechanical weathering erosion.
d. Structure. Structure is dominant that there are areas Plasma are stocky structures (joint) compared to the structure of the fracture. As is known, igneous rocks have porosity and permeability are so small that water penetration is very difficult, so the presence of these cracks will further facilitate the entry of water and means the process will be more intense weathering.
e. Topography. Local topography will greatly affect the water circulation along with other reagents. For a sloping area, then the water will move slowly so it will have the opportunity to have a deeper penetration through cracks or pores of the rock.
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