A great amount of red mud generated from alumina production by Bayer process not only threatens the environment but also causes waste of secondary resources.High-iron-content red mud from Bayer process was employed to...A great amount of red mud generated from alumina production by Bayer process not only threatens the environment but also causes waste of secondary resources.High-iron-content red mud from Bayer process was employed to recover alumina and ferric oxide by the process of reduction-sintering,leaching and then magnetic beneficiation.Results of thermodynamic analyses show that ferric oxide should be reduced to Fe if reduction of ferric oxide and formation of sodium aluminate and calcium silicate happen simultaneously.Experimental results indicate that alumina recovery of Bayer red mud can reach 89.71%,and Fe recovery rate and the grade of magnetite concentrate are 60.67%and 61.78%,respectively,under the optimized sintering conditions.展开更多
Red mud is a type of highly alkaline waste residue produced in the process of alumina smelting by the Bayer process.Based on the idea of medium calcium content,solid wastes such as red mud and fly ash were used to pre...Red mud is a type of highly alkaline waste residue produced in the process of alumina smelting by the Bayer process.Based on the idea of medium calcium content,solid wastes such as red mud and fly ash were used to prepare non-burnt bricks;and the mass ratio of CaO/SiO2 was selected in the range of 0.88–1.42.Mechanical properties and durability were investigated with a compressive strength test.X-ray diffractometry(XRD),scanning electron microscope(SEM),and Fourier transform infrared spectroscopy(FTIR)techniques were used to characterize the hydration characteristic.The environmental performance was analyzed by Inductively Coupled Plasma Mass Spectrometry(ICP).The results indicated that the mechanical properties and the durability were optimal when the mass ratio of CaO/SiO2 was 1.23.The hydration products were mostly C–S–H gel,ettringite,Na4Ca(Si10All6)O32·12H2O and Ca3Al2(SiO4)(OH)8.They were responsible for the strength development,and the CaO/SiO2 mass ratio of 1.23 had the best polymerized structure.The results of an environmental performance test showed that the heavy metals in the raw materials were well-solidified in the brick.Therefore,this paper provides an effective solution for use of solid wastes in building material.展开更多
在工程建设中,废弃泥浆含水率极高,且对环境的影响极大,解决其脱水问题成为当前面临的主要难题。针对高含水率泥浆泥水分离问题,选择3种絮凝剂:氯化钙(CaCl_(2))、阴离子型聚丙烯酰胺(APAM)和聚合氯化铝(PAC),设计3因素4水平正交试验,...在工程建设中,废弃泥浆含水率极高,且对环境的影响极大,解决其脱水问题成为当前面临的主要难题。针对高含水率泥浆泥水分离问题,选择3种絮凝剂:氯化钙(CaCl_(2))、阴离子型聚丙烯酰胺(APAM)和聚合氯化铝(PAC),设计3因素4水平正交试验,采用综合平衡法,选取48 h脱水量和上清液pH值等指标,进行极差分析和方差分析,着重找出最佳复合絮凝剂组合。通过正交试验结果和SEM微观分析等对絮凝机理进行讨论。结果表明,将脱水量随时间变化曲线划分为高、中、低脱水区和快速脱水、慢速脱水阶段,则泥浆脱水速率整体呈减小趋势,其中高脱水区组在12 h时也具有较高的脱水量,即满足快速脱水的要求;3种絮凝剂存在一定的协同作用效果。通过正交试验的极差分析和方差分析发现,复合絮凝剂的最优组合为每100 g泥浆掺量为0.25 g CaCl_(2)+0.12 g APAM+0.17 g PAC;根据机理分析,可将复合絮凝剂絮凝过程分为5个阶段:电中和阶段、架桥阶段、吸附成团阶段、网络沉降阶段和固化增强阶段。展开更多
基金Project(2005CB623702)supported by the National Basic Research Program of China
文摘A great amount of red mud generated from alumina production by Bayer process not only threatens the environment but also causes waste of secondary resources.High-iron-content red mud from Bayer process was employed to recover alumina and ferric oxide by the process of reduction-sintering,leaching and then magnetic beneficiation.Results of thermodynamic analyses show that ferric oxide should be reduced to Fe if reduction of ferric oxide and formation of sodium aluminate and calcium silicate happen simultaneously.Experimental results indicate that alumina recovery of Bayer red mud can reach 89.71%,and Fe recovery rate and the grade of magnetite concentrate are 60.67%and 61.78%,respectively,under the optimized sintering conditions.
基金the financial support from the National Natural Science Foundation of China (No.51574024)Fundamental Research Funds for the Central Universities (FRF-TP-18-005B1)Technological Research and Development Programs of China Railways Corporation (No.2017G006-J)
文摘Red mud is a type of highly alkaline waste residue produced in the process of alumina smelting by the Bayer process.Based on the idea of medium calcium content,solid wastes such as red mud and fly ash were used to prepare non-burnt bricks;and the mass ratio of CaO/SiO2 was selected in the range of 0.88–1.42.Mechanical properties and durability were investigated with a compressive strength test.X-ray diffractometry(XRD),scanning electron microscope(SEM),and Fourier transform infrared spectroscopy(FTIR)techniques were used to characterize the hydration characteristic.The environmental performance was analyzed by Inductively Coupled Plasma Mass Spectrometry(ICP).The results indicated that the mechanical properties and the durability were optimal when the mass ratio of CaO/SiO2 was 1.23.The hydration products were mostly C–S–H gel,ettringite,Na4Ca(Si10All6)O32·12H2O and Ca3Al2(SiO4)(OH)8.They were responsible for the strength development,and the CaO/SiO2 mass ratio of 1.23 had the best polymerized structure.The results of an environmental performance test showed that the heavy metals in the raw materials were well-solidified in the brick.Therefore,this paper provides an effective solution for use of solid wastes in building material.
文摘在工程建设中,废弃泥浆含水率极高,且对环境的影响极大,解决其脱水问题成为当前面临的主要难题。针对高含水率泥浆泥水分离问题,选择3种絮凝剂:氯化钙(CaCl_(2))、阴离子型聚丙烯酰胺(APAM)和聚合氯化铝(PAC),设计3因素4水平正交试验,采用综合平衡法,选取48 h脱水量和上清液pH值等指标,进行极差分析和方差分析,着重找出最佳复合絮凝剂组合。通过正交试验结果和SEM微观分析等对絮凝机理进行讨论。结果表明,将脱水量随时间变化曲线划分为高、中、低脱水区和快速脱水、慢速脱水阶段,则泥浆脱水速率整体呈减小趋势,其中高脱水区组在12 h时也具有较高的脱水量,即满足快速脱水的要求;3种絮凝剂存在一定的协同作用效果。通过正交试验的极差分析和方差分析发现,复合絮凝剂的最优组合为每100 g泥浆掺量为0.25 g CaCl_(2)+0.12 g APAM+0.17 g PAC;根据机理分析,可将复合絮凝剂絮凝过程分为5个阶段:电中和阶段、架桥阶段、吸附成团阶段、网络沉降阶段和固化增强阶段。
