Abstract: In silicon wafer manufacturing for solar cells, the hazardous sawing waste results in serious environmental problems. In this paper, a novel approach for the recycling and reusing of slurry waste is reported. The results show that slurry waste is recycled and reused completely, and composite material of Si3N4-Si2N2O-SiC is prepared. The residual gas from oxygen enrich gas production is used, which reduced cost effectively. In addition, the reaction is exothermic, which is also energy saving and ensure the production to be continuous without external heat source. The mechanism was also discussed in this paper.
Abstract: The accelerated carbonation with different pressure steaming conditions was used to process the steel slag, so the slag could turn into a primary cementitious product with carbonation activity. XRD, FTIR, TG, N2 absorption BET surface area analyzer and SEM were used to characterize the mineral and chemical compositions and microstructure of each sample before and after the carbonation. The results show that: the carbonation products with different morphologies are formed under different temperature conditions. The optimum temperature for the accelerated carbonation for processing the steel slag is selected to be 90 °C, which results in the compressive strength of 32.8 MPa. The BET specific surface area of the steel slag reduces after carbonation, the sample density increased after carbonation.
Abstract: Deoiled asphalt (DOA) and slurry are by-products of petroleum refining process. In this paper, blending asphalt (DST) based on DOA, slurry and vacuum gas oil and SBS modified DST (SMDST) were prepared. The aging resistance of SMDST was investigated by thermal aging (TA) and ultraviolet (UV) aging. Meanwhile, the chemical structure and microstructure of SMDST before and after aging were characterized by Fourier transform infrared spectroscopy (FTIR) and fluorescence microscopy. The results showed that the softening point, ductility at 5 °C and low temperature flexibility of SMDST increased gradually with the increase of SBS content. When SBS content was 12 wt%, the softening point, ductility at 5 °C and low temperature flexibility of SMDST were 105 °C, 55 cm and -25 °C, respectively. After TA and UV, the low temperature flexible reductions of SMDST with 12 wt% SBS were 3 °C and 2 °C, respectively, which demonstrated that aged SMDST still had good crack resistance in low temperature. FTIR analysis indicated that the carbonyl (C=O) and the sulfoxide (S=O) characteristic peaks of SMDST were enhanced after aging to a certain extent. However, the fluorescence microscope observation showed the network structure of SMDSB was not damaged significantly, which implies that SMDST has a favourable anti-aging performance.
Abstract: Indium is widely used in some important fields due to its semiconductor and optoelectronic performance. While the reduction of indium minerals, as one of secondary resources, the amount of indium–tin oxide (ITO) waste target has been accumulated considerably. ITO film is the main functional fraction of LCD has consumed more than 60% of the indium production worldwide. Therefore, it is necessary to recycle indium from ITO waste. Some researchers have been done for proper treatment to recycle indium from ITO waste. In this paper, the extraction methods of indium from ITO waste target are introduced, and the advantages and disadvantages of each method are compared.
Abstract: The pyrolysis experiment was carried out on the waste printed circuit boards (WPCBs) of mobile phones to obtain the mixed metals which contains more than ten valuable metals. The main components in the mixed metals are elements Fe, Cu, Pb, Sn. The liquid-liquid phase separation behavior of (Fe0.4Cu0.6)100-xPbx ternary alloy has been studied. The introduction of Pb into the metastable immiscible Fe-Cu alloy can result in a stable liquid-liquid phase separation into L(Fe) and L(Cu,Pb) liquids. With the increasing of Pb content, the second phase separation in the residual L(Cu,Pb) liquid was detected, resulting in the formation of three-zone-separation structure. On this basis, a hierarchical separation system was designed to recycle mixed metals in super gravity field. The results show that the metals Cr, Co, Ni, Si are mainly enriched in the Fe-rich zone, the precious metals Au, Ag and a small amount of Zn are concentrated in the Cu-rich zone, while the low-melting-point metals Sn, Bi, Cd, and In are collected in the Pb-rich zone.