Regenerated Mg O–Ca O brick samples containing 80wt%, 70wt%, and 60wt% Mg O were prepared using spent Mg O–Ca O bricks and fused magnesia as raw materials and paraffin as a binder. The bricks were sintered at 1873 K...Regenerated Mg O–Ca O brick samples containing 80wt%, 70wt%, and 60wt% Mg O were prepared using spent Mg O–Ca O bricks and fused magnesia as raw materials and paraffin as a binder. The bricks were sintered at 1873 K for 2 h under an air atmosphere and under an isolating system. The microstructure, mechanical properties at room temperature, and hydration resistance of the regenerated samples were measured and compared. The results indicated that the isolating sintering generated a strongly reducing atmosphere as a result of the incomplete combustion of paraffin, and the partial oxygen pressure was approximately 6.68 × 10–7 Pa. The properties of the regenerated bricks sintered under air conditions were all higher than those of the bricks sintered under a reducing atmosphere. The deterioration of the bricks was a result of Mg O reduction and a decrease in the amount of liquid phase formed during sintering under a reducing atmosphere.展开更多
The stabilization of severely As-polluted soil has been a challenge, especially for the extremely toxic As(Ⅲ) contaminants. In this study, soil with a high As concentration(26084 mg/kg) was availably stabilized by a ...The stabilization of severely As-polluted soil has been a challenge, especially for the extremely toxic As(Ⅲ) contaminants. In this study, soil with a high As concentration(26084 mg/kg) was availably stabilized by a H2O2 pre-oxidation assisted TMT-15(Na3S3C3N3 solution with a mass fraction of 15%) and FeCl3·6 H2O stabilization method. The results showed that the combination of the two stabilizers(i.e., TMT-15 and FeCl3·6 H2O) presented a better stabilization behavior than either stabilizer used individually. The use of the H2O2 pre-oxidation assisted TMT-15 and FeCl3·6 H2O stabilization approach not only converted the As(Ⅲ) to As(Ⅴ) but also reduced the toxic leaching concentration of As to 1.61 mg/L, which is a safe level, when the additions of TMT-15 and FeCl3·6 H2O were 2 mL and 0.20 g, respectively. Thus, using only a simple H2O2 pre-oxidation to combine clean stabilization with non-toxic stabilizers TMT-15 and FeCl3·6 H2O could render the severely As-contaminated soil safe for disposal in a landfill.展开更多
The oxidation behavior of different SiAlON phases(β-SiAlON,X-phase SiAlON and 12H powders) synthesized from coal gangue in air atmosphere was investigated using isothermal thermogravimetry(TG) and field-emission scan...The oxidation behavior of different SiAlON phases(β-SiAlON,X-phase SiAlON and 12H powders) synthesized from coal gangue in air atmosphere was investigated using isothermal thermogravimetry(TG) and field-emission scanning electron microscopy(FE-SEM).The effect of ferric oxide impurities in coal gangue was studied.The results show that ferric oxide contributes to the growth of SiAlON crystalline during the synthesis process.In the oxidation experiment,the existence of ferric oxide decreases the oxidation resistance of SiAlON.The reason is that the impurity causes the formation of a liquid phase at a higher temperature.At 1423-1623 K,the oxidation of SiAlON powders is diffusion controlled and it can be described by Chou's model.A fair agreement is found between theoretical calculations and the experimental data.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51372019, 51074009, and 50874013)the National Science and Technology Supporting Program (No. 2011BAB03B02)
文摘Regenerated Mg O–Ca O brick samples containing 80wt%, 70wt%, and 60wt% Mg O were prepared using spent Mg O–Ca O bricks and fused magnesia as raw materials and paraffin as a binder. The bricks were sintered at 1873 K for 2 h under an air atmosphere and under an isolating system. The microstructure, mechanical properties at room temperature, and hydration resistance of the regenerated samples were measured and compared. The results indicated that the isolating sintering generated a strongly reducing atmosphere as a result of the incomplete combustion of paraffin, and the partial oxygen pressure was approximately 6.68 × 10–7 Pa. The properties of the regenerated bricks sintered under air conditions were all higher than those of the bricks sintered under a reducing atmosphere. The deterioration of the bricks was a result of Mg O reduction and a decrease in the amount of liquid phase formed during sintering under a reducing atmosphere.
基金financially supported by the National Key R&D Program of China (No. 2018YFC1802400)the National Natural Science Foundation of China (No. 51604310)+1 种基金the Major Project of Central Research Institute of Building and Construction (No. XAC2017Ky03)the Opening Foundation of State Key Laboratory for Environmental Protection of Iron and Steel Industry (No. 2016YZC02)
文摘The stabilization of severely As-polluted soil has been a challenge, especially for the extremely toxic As(Ⅲ) contaminants. In this study, soil with a high As concentration(26084 mg/kg) was availably stabilized by a H2O2 pre-oxidation assisted TMT-15(Na3S3C3N3 solution with a mass fraction of 15%) and FeCl3·6 H2O stabilization method. The results showed that the combination of the two stabilizers(i.e., TMT-15 and FeCl3·6 H2O) presented a better stabilization behavior than either stabilizer used individually. The use of the H2O2 pre-oxidation assisted TMT-15 and FeCl3·6 H2O stabilization approach not only converted the As(Ⅲ) to As(Ⅴ) but also reduced the toxic leaching concentration of As to 1.61 mg/L, which is a safe level, when the additions of TMT-15 and FeCl3·6 H2O were 2 mL and 0.20 g, respectively. Thus, using only a simple H2O2 pre-oxidation to combine clean stabilization with non-toxic stabilizers TMT-15 and FeCl3·6 H2O could render the severely As-contaminated soil safe for disposal in a landfill.
基金supported by the National Natural Science Foundation of China(No.50874013)the support from the Key Lab. of the Ministry of Education of China for Ecologic & Recycle Metallurgy,University of Science and Technology Beijing
文摘The oxidation behavior of different SiAlON phases(β-SiAlON,X-phase SiAlON and 12H powders) synthesized from coal gangue in air atmosphere was investigated using isothermal thermogravimetry(TG) and field-emission scanning electron microscopy(FE-SEM).The effect of ferric oxide impurities in coal gangue was studied.The results show that ferric oxide contributes to the growth of SiAlON crystalline during the synthesis process.In the oxidation experiment,the existence of ferric oxide decreases the oxidation resistance of SiAlON.The reason is that the impurity causes the formation of a liquid phase at a higher temperature.At 1423-1623 K,the oxidation of SiAlON powders is diffusion controlled and it can be described by Chou's model.A fair agreement is found between theoretical calculations and the experimental data.