2 research outputs found
Reductive roasting of nickel laterite ore with sodium sulfate for Fe-Ni production. Part I: Reduction/sulfidation characteristics
<p>The selective reduction of nickel and adequate growth of ferronickel grains are imperative for efficient preparation of ferronickel from nickeliferous laterite ore via the process of direct reduction followed by magnetic separation. In Part I, reduction/sulfidation behaviors of a saprolitic laterite ore in the presence of sodium sulfate were investigated, with an emphasis on thermodynamic analysis, selective reduction/sulfidation ratios and kinetics. To separate the interactions between Ni and Fe, chemical titration analysis was adopted to determine the contents of various Ni and Fe species in the roasted pellets, and a modified equation to assay metallic iron content was proposed.</p
Facile Route for Preparing Refractory Materials from Ferronickel Slag with Addition of Magnesia
The
feasibility of a facile technological route to preparation of refractory
materials from a ferronickel slag with the addition of sintered magnesia
was verified in this study based on the thermodynamics analysis and
the experimental exploration of the effect of the sintered magnesia
addition on the phase transformation of ferronickel slag during the
sintering process. For the first time, the results of thermodynamics
calculation, X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analyses revealed that the original phase of the slag can be transformed to high melting point phases by addition of MgO during the sintering process at high temperatures (e.g., 1350 °C). Specifically, the olivine in ferronickel slag
decomposed initially, generating a low-iron olivine phase and an enstatite
phase. With increasing addition of sintered magnesia, the enstatite
phase changed to forsterite, and the iron, aluminum, and chromium
components in the ferronickel slag converted to high melting point
spinel phases, including magnesium aluminate spinel and magnesium chromate
spinel via a low-magnesium transient phase. The experimental results
showed that a good refractory material with refractoriness of 1660 °C,
bulk density of 2.92 g/cm<sup>3</sup>, apparent porosity of 1.82%,
and compressive strength of 100.61 MPa could be obtained when the
slag was sintered with addition of 20 wt % sintered magnesia at 1350
°C for 3 h. Due to the low production cost and property superiority
of the prepared refractory material over commercial counterparts,
the method proposed in this study is expected to have widespread applications
in recycling of ferronickel slag