Abstract
Sodium chloride has been proved that it is an effective promoter for the reduction of high-magnesium, low-nickel oxide ore. The aim of current work is to clarify the promotion behavior of sodium chloride in the roasting reduction process. The influence of moisture on the reduction of ore in the presence of sodium chloride is studied to get clear comprehension of promotion process. In the presence of moisture, the HCl is produced by pyrohydrolysis of sodium chloride for chlorinating nickel and iron oxides, moreover, interactions between metallic oxides and sodium chloride are also a way for chlorination at high temperature (>802 °C); subsequently, the metal chloride would be reduced by reductant. In the absence of moisture, the magnetic separation results show that the recoveries of iron and nickel have a significant increase; moreover, olivine structure would be destroyed gradually with the increase of roasting temperature in the action of sodium chloride, and the sodium chloride existed in high-magnesium, low-nickel oxide ore could make the NiO isolate from NiO-bearing minerals. The NiO reacts with Fe2O3 at high temperature to form NiFe2O4, which is conductive to the formation of Ni-Fe alloy during the reduction process.
Highlights
CaO S Mn 0.033 0.01 0.083 desulfurization process and the formation of a low-melting-point sulfur compound (FeS) in the steel contributed to their difficult development
The experimental results indicate that a ferronickel concentrate with 7.09% Ni and 67.90% Fe can be obtained from the high-magnesium low-nickel (HL) oxide ore containing 0.82% Ni and 9.67% Fe via chloridization and reduction roasting at 1200 °C for 20 min in the presence of 10 wt.% sodium chloride and 8 wt.% coal, and the corresponding recoveries of nickel and iron were 98.31 and 72.08%, respectively
Compared with the results of aforementioned studies, as an effective accelerator to promote the reduction of low grade nickel laterite ore (
Summary
Effect of moisture on beneficiation of Ni and Fe. Figure 1 shows the magnetic separation results of HL oxide ore roasted with 10 wt.% NaCl and 8 wt.% anthracite at 1200 °C for 20 min as a function of drying temperature (TD) of raw ore. The XRD result of the volatile matter (Fig. 4) shows that the main phases are rokuhnite [FeCl2·2H2O], iron chloride hydrate [FeCl2·4H2O] and iron nickel chloride hydrate [Ni0.5Fe0.5Cl2·4H2O] The formation of large ferronickel particles is beneficial for exacting them from gangue by magnetic separation In the absence of moisture, the sodium chloride existed in ore could make the nickel oxide isolate from serpentine, the structure of olivine is destroyed lead to aggregation of iron oxides. Due to the change of the occurrence state of iron and nickel, the NiFe2O4 would be generated more with the action of sodium chloride at high temperature
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