No abstract

No abstract

To efficiently extract nickel from low grade limonitic laterite ore, a separation method of iron-nickel alloy nugget by selfreduction of coal composite limonitic laterite ore briquette was investigated. In this investigation, in order to decrease the separation temperature of iron-nickel alloy nugget, the selective reduction by control of C/O ratio was introduced and reductant added in the briquette was inadequate for the reduction of nickel and iron. Nickel was preferentially reduced in the reduction process, while iron was partially reduced due to the lack of reductant. After reduction, a certain amount of FeO existed in the reduced product. This residual FeO had a great role in the formation of low melting point slag, which could promote the formation and the separation of iron-nickel alloy nugget at relatively low temperature. In this investigation, the reduction experiments were all conducted at 1300°C. To evaluate the formation and the separation of iron-nickel alloy nugget in the reduction process, we observed the patterns of reduced products under different C/O ratio, CaO addition ratio and holding time conditions. And then the effect of C/O ratio and CaO addition ratio on nickel content of nugget and nickel recovery ratio were investigated. The results showed that 0.7 of C/O ratio, 8% of CaO addition ratio and 40min of holding time were suitable for the separation of iron-nickel alloy nugget from limonitic laterite ore. Nickel and iron content of the nugget and the nickel recovery ratio were 4.75%, 89.51% and 85%, respectively. Nuggets were easily separated from slag by crushing and screening. This separation method could be applied to any limonitic laterite ore by adjusting C/O ratio and CaO addition ratio.

No abstract

Since their development in the 1970s ZrO2 ceramics have been shown to be promising alternative materials for total hip arthroplasty (THA) and total knee arthroplasty (TKA). However, ZrO2 is so brittle that in vivo failure can result from fracture of the ceramic femoral head and fracture of the ceramic acetabular liner due to the low toughness of the ceramics. To improve its fracture toughness, the approach commonly utilized has been the addition of a second phase to form a composite and produce nanostructured materials. The purpose of this study was to produce a mechanical synthesis of CoZr and ZrO2 nanopowders from CoO and Zr powders, and fabricate dense nanocrystalline 2CoZr-ZrO2 composites within two minutes using this pulsed current activated sintering method. Their mechanical properties, biocompatibility and microstructure were then evaluated. Nanopowders of CoZr and ZrO2 were synthesized mechanochemically according to the reaction (2 CoO + 3 Zr → 2CoZr + ZrO2) from CoO and Zr powders by high-energy ball milling. The synthesized powders were consolidated by the pulsed current activated sintering method within two minutes under 80Mpa pressure. CoZr and ZrO2 composite was sintered by the rapid heating of the nanophase. The hardness and fracture toughness of the 2 CoZr-ZrO2 composite in this study were better than the hardness of monolithic CoZr and the fracture toughness of a monolithic ZrO2. Additionally, the 2 CoZr-ZrO2 composite exhibited good biocompatibility. † (