Abstract
The Colombian nickeliferous laterites are minerals used for the nickel extraction by hydrometallurgical and pyrometallurgical processes. In this work the thermodynamic behaviour of three Colombian lateritic mineral samples are described, with contents of 1.42%, 1.78% y 2.04% of nickel, when they are subjected to the calcination and reduction processes. The mineral was characterized using X Rays Diffraction and X Rays Fluorescence, giving evidence of the presence of mineralogical species such as nepouite (Ni3Si2O5(OH)4), goethite (Fe2O3.H2O), silica (SiO2), antigorite (Mg3Si2O5(OH)4) and fosferite (Mg2SiO4). The thermodynamic analysis was conducted using the software HSC Chemistry for Windows 5.1 and was focused in the quantitative determination of the chemical evolution of the mixture of these minerals with variable quantities of coal, in function of temperature. The results produced by the program showed, in the equilibrium, the feasibility of complete reduction of the nickel, and additionally, a considerable high percentage of reduction of iron oxides (up to 99%) using ratio C/O ≈1 at temperatures close to 1100 °C.
Highlights
Nickel is a strategic metal used in metallurgical industry as raw material in the production of stainless steel
The thermodynamic behavior of the nickeliferous laterites with low contents, carried to a pyrometallurgical process has been studied. There are works such as the of Pickles et al, (2013), they making a thermodynamic analysis based on the system Fe–Ni–Co–Mg–Si–O–H–S–C–Cl in order to establish the effect of variables such as the temperature, sulphur and coal quantity, as well as chlorine additions for the nickel recovery (Pickles et al, 2013)
The current study is focused in the thermodynamic analysis of three lateritic mineral samples basically compound by iron oxide, nickel oxide and magnesium silicates, in form of nepouite (Ni3Si2O5(OH)4), goethite (Fe2O3.H2O), silica (SiO2), antigorite (Mg3Si2O5(OH)4) and fosferite (Mg2SiO4)
Summary
The thermodynamic analysis of the reduction process of the nickel lateritic minerals mixed with coal was conducted using the “Equilibrium compositions” module, which it is useful to calculate, in this study in particular, the evolution of the composition to the system equilibrium based on the variation of the coal concentration and temperature. Thermodynamic analysis of the reduction process of Colombian lateritic nickel ore 3. The different systems analyzed consist on a mixture of laterite of nickel with coal, this last one is a component in the range from 3.75 to 7.59% in weight, such range of coal concentrations corresponds to a C/O relation in the range of 0.66 to 1, the oxygen was considered as the one contained in the iron and nickel oxides. A first approximation of the behavior expected from the system under study is obtained from the making of Ellingham diagrams (ΔG vs T), and using the mentioned software
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