Both the consumption and production of crude stainless steel in China rank first in the world. In 2011, the nickel production in China amounted to 446 kilotons, with the proportion of electrolytic nickel and nickel pig iron (NPI) registering 41.5% and 56.5%, respectively. NPI is a low-cost feedstock for stainless steel production when used as a substitute for electrolytic nickel. The existing commercial NPI production processes such as blast furnace smelting, rotary kiln-electric furnace smelting, and Krupp-Renn (Nipon Yakin Oheyama) processes are discussed. As low-temperature (below 1300°C) reduction of nickeliferous laterite ores followed by magnetic separation could provide an alternative avenue without smelting at high temperature (~1500°C) for producing ferronickel with low cost, the fundamentals and recent developments of the low-temperature reduction of nickeliferous laterite ores are reviewed.

Carbothermic Reduction of Nickeliferous Laterite Ores for Nickel Pig Iron Production in China: A Review

Abstract Moisture absorption into ultrathin poly(vinyl pyrrolidone) (PVP) films with varying thickness was examined using X-ray reflectivity (XR) and quartz crystal microbalance (QCM) measurements. Two different surfaces were used for the substrate: a hydrophilic silicon oxide (SiO x ) and a hydrophobic hexamethyldisilazane (HMDS) treated silicon oxide surface. The total equilibrium moisture absorption (solubility) was insensitive to the surface treatment in the thickest films (≈150 nm). However, strong reductions in the equilibrium uptake with decreasing PVP film thickness were observed on the HMDS surfaces, while the SiO x surface exhibited thickness independent equilibrium absorption. The decreased absorption with decreasing film thickness is attributed a depletion layer of water near the polymer/HMDS interface, arising from hydrophobic interactions between the surface and water. The diffusivity of water decreased when the film thickness was less than 60 nm, independent of the surface treatment. Changes in the properties of ultrathin polymer films occur even in plasticized films containing nearly 50% water.

Moisture Absorption into Ultrathin Hydrophilic Polymer Films on Different Substrate Surfaces

Effect of calcium ions on adsorption of sodium oleate onto cassiterite and quartz surfaces and implications for their flotation separation

Dealkalization processes of bauxite residue: A comprehensive review

A semi-industrial experiment of suspension magnetization roasting technology for separation of iron minerals from red mud.

Mechanism of sodium sulfate in promoting selective reduction of nickel laterite ore during reduction roasting process

A process with coal-based direct reduction followed by magnetic separation is presented for recovering metallic iron from high-phosphorus oolitic hematite in this study. Ca(OH)2 and Na2CO3 were used as additives in the reduction roasting. A Direct Reduction Iron (DRI) with 93.28 mass% Fe, and 0.07 mass% P can be obtained at a recovery percentage of 92.30 mass% under optimal conditions. The mechanisms of Ca(OH)2 and Na2CO3 were investigated by XRD and SEM with EDS. It showed that fluorapatite was reduced to P smelt into metallic iron without additives while the hematite was reduced. The addition of Ca(OH)2 can not only inhibit the reduction of fluorapatite but also promote the reduction of hematite. Na2CO3 can promote the separation of iron from slag, meanwhile it may also inhibit the reduction of fluorapatite at the presence of 15 mass% Ca(OH)2. Under optimal conditions, phosphorus remained as fluorapatite in the slag and can be removed by grinding and magnetic separation.

The Function of Ca(OH)2 and Na2CO3 as Additive on the Reduction of High-Phosphorus Oolitic Hematite-coal Mixed Pellets

A study of sodium oleate adsorption on Ca2 + activated quartz surface using quartz crystal microbalance with dissipation

A novel utilization of Bayer red mud through co-reduction with a limonitic laterite ore to prepare ferronickel

In this article, mineralogical phase changes and structural changes of iron oxides and phosphorus-bearing minerals during the direct reduction roasting process were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM) It has been found that the reduction of hematite follows the following general pathway: Fe2O3 → Fe3O4 → FeO → Fe The last step of the reduction process contains two side reactions: either FeO → Fe2SiO4 → Fe or FeO → FeAl2O4 → Fe depending on the micro mineralogical makeup of the ore In the reduction process of FeO → Fe, oolitic structure was destroyed completely and fluorapatite was diffused into gangue while metallic phase is coarsening at temperatures below 1200°C Therefore, the separation of phosphorus-bearing gangue and metallic iron can be achieved by wet grinding and magnetic separation, and low phosphorus content metallic iron powder can be obtained However, when the temperature reached 1250°C and beyond, some of the fluorapatite was reduced to elemental

Jue Kou

Papers

Mechanism of sodium sulfate in promoting selective reduction of nickel laterite ore during reduction roasting process

The Function of Ca(OH)2 and Na2CO3 as Additive on the Reduction of High-Phosphorus Oolitic Hematite-coal Mixed Pellets

A study of sodium oleate adsorption on Ca2 + activated quartz surface using quartz crystal microbalance with dissipation

A novel utilization of Bayer red mud through co-reduction with a limonitic laterite ore to prepare ferronickel

Study on Phosphorus Removal of High-Phosphorus Oolitic Hematite by Coal-Based Direct Reduction and Magnetic Separation