Fabrication and Analysis of β-Sialon Whiskers from Fly Ash by Carbon Thermal Reduction-Nitridation

2015 ◽  
Vol 723 ◽  
pp. 610-614
Author(s):  
Jing Zhang ◽  
Jiang Long Yu ◽  
Huan Zhao ◽  
Jun Shuai Liu
Keyword(s):  
Fly Ash ◽  
Reaction Time ◽  
Carbon Content ◽  
Reaction Temperature ◽  
Carbothermal Reduction ◽  
Thermal Reduction ◽  
Optimal Temperature ◽  
Nitridation Process ◽  
Best Parameter ◽  
Sialon Powder

β-Sialonwhiskers which the molecular structuralformula of β-Sialonis Si3Al3O3N5(z = 3) were synthesized from fly ash and graphite under appropriate technological conditions by carbothermal reduction–nitridation process. The effects of carbon content, reaction temperature and reaction time on synthesis ofβ-Sialonwere analysed by XRD, SEM techniques. The results proved that, the condition of the carbon content over 80% is the best parameter to promote theβ-Sialon powder production. Compared to other kinds of temperature, 1430 °C is the optimal temperature to promoteβ-Sialon powder generation. Compared to 3h, holding time of 6h is promoting theβ-Sialon powder generation.The main morphology of β-Sialon was rod-like whisker.

scholarly journals Feasibility of fly ash as fluxing agent in mid- and low-grade phosphate rock carbothermal reduction and its reaction kinetics

2021 ◽  
Vol 10 (1) ◽  
pp. 157-168
Author(s):  
Biwei Luo ◽  
Pengfei Li ◽  
Yan Li ◽  
Jun Ji ◽  
Dongsheng He ◽  
...  
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Reaction Time ◽  
Carbothermal Reduction ◽  
Industrial Waste ◽  
Phosphate Rock ◽  
Molar Ratio ◽  
Low Grade ◽  
Carbon Excess ◽  
Fluxing Agent

Abstract The feasibility of industrial waste fly ash as an alternative fluxing agent for silica in carbothermal reduction of medium-low-grade phosphate ore was studied in this paper. With a series of single-factor experiments, the reduction rate of phosphate rock under different reaction temperature, reaction time, particle size, carbon excess coefficient, and silicon–calcium molar ratio was investigated with silica and fly ash as fluxing agents. Higher reduction rates were obtained with fly ash fluxing instead of silica. The optimal conditions were derived as: reaction temperature 1,300°C, reaction time 75 min, particle size 48–75 µm, carbon excess coefficient 1.2, and silicon–calcium molar ratio 1.2. The optimized process condition was verified with other two different phosphate rocks and it was proved universally. The apparent kinetics analyses demonstrated that the activation energy of fly ash fluxing is reduced by 31.57 kJ/mol as compared with that of silica. The mechanism of better fluxing effect by fly ash may be ascribed to the fact that the products formed within fly ash increase the amount of liquid phase in the reaction system and promote reduction reaction. Preliminary feasibility about the recycling of industrial waste fly ash in thermal phosphoric acid industry was elucidated in the paper.

Preparation of β-Sialon from Fly Ash by Carbothermal Reduction-Nitridation Reaction

2008 ◽  
Vol 368-372 ◽  
pp. 910-912 ◽  
Author(s):  
Jun Tong Huang ◽  
Ming Hao Fang ◽  
Yan Gai Liu ◽  
Zhao Hui Huang
Keyword(s):  
Fly Ash ◽  
Carbon Black ◽  
Carbon Content ◽  
Carbothermal Reduction ◽  
Single Phase ◽  
Raw Materials ◽  
Synthesis Mechanism ◽  
Nitridation Reaction

Single phase Sialon was synthesized successfully from fly ash by carbothermal reductionnitridation reaction in this paper. The effects of synthesizing temperature (1200°C, 1300°C, 1400°C and 1450°C) and carbon content (stoichiometric content, exceeding 10%, 50% and 100%) on the final production were studied by XRD and SEM. Synthesis mechanism of β-Sialon was also analysized. The results indicated that single phase β-Sialon with z=3 was obtained using fly ash as raw materials and carbon black of stoichiometric content as reducer by carbothermal reduction- nitridation reaction in flow nitrogen at 1450°C for 3h. Temperature and content of carbon had significant effect on the synthesis of β-Sialon.

Resource recovery of waste incineration fly ash: Synthesis of tobermorite as ion exchanger

1999 ◽  
Vol 14 (11) ◽  
pp. 4437-4442 ◽  
Author(s):  
Zhidong Yao ◽  
Chikashi Tamura ◽  
Motohide Matsuda ◽  
Michihiro Miyake
Keyword(s):  
Fly Ash ◽  
Reaction Time ◽  
Sodium Hydroxide ◽  
Hydrothermal Treatment ◽  
Reaction Temperature ◽  
Sodium Hydroxide Solution ◽  
Waste Incineration ◽  
Naoh Solution ◽  
Temperature Time ◽  
Waste Incineration Fly Ash

Tobermorite was synthesized successfully from waste incineration fly ash by hydrothermal treatment in the presence of sodium hydroxide solution. The tobermorite synthesis was examined as a function of reaction temperature, time, and NaOH concentration. The formation of tobermorite was identified in all of the fly ash treated with NaOH at 180 °C, followed by the minor generations of sodalite and cancrinite phases with increasing NaOH concentration and extending reaction time. The NaOH-treated fly ash revealed the uptake behaviors for Cs+ and NH4+, whereas the fly ash untreated with NaOH solution did not show that. The uptake amounts of resulting products were also determined: 0.40 mmol/g for Cs+ and 0.35 mmol/g for NH4+ in the fly ash treated with 2.0 M NaOH at 180 °C for 20 h.

scholarly journals Optimization of medium–low-grade phosphorus rock carbothermal reduction process by response surface methodology

2020 ◽  
Vol 9 (1) ◽  
pp. 349-358
Author(s):  
Biwei Luo ◽  
Pengfei Li ◽  
Yan Li ◽  
Pengpeng He ◽  
Jun Ji ◽  
...  
Keyword(s):  
Particle Size ◽  
Response Surface Methodology ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Carbothermal Reduction ◽  
Reduction Rate ◽  
Molar Ratio ◽  
Temperature Reaction ◽  
Rock Particle ◽  
Phosphorus Reduction

AbstractPhosphorus extraction from phosphorus rock was conducted by carbothermal reduction with silica and coke. The effects of reaction temperature, reaction time, coke excess coefficient, molar ratio of silicon–calcium, and phosphorus rock particle size on the phosphorus reduction rate were investigated by the response surface methodology (RSM). The central composite design (CCD) with five factors and five levels was used to explore the effects of variables’ interactions on the phosphorus reduction rate. The results showed that there are significant interactions between reaction time and temperature; reaction temperature and molar ratio of silicon–calcium; reaction temperature and phosphorus rock particle size; coke excess coefficient and molar ratio of silicon–calcium; and coke excess coefficient and phosphorus rock particle size. The optimum conditions in the experimental range are reaction time 92 min, reaction temperature 1340°C, coke excess coefficient 1.27, molar ratio of silicon–calcium 1.28, and phosphorus rock particle size 75–106 µm, which were derived from the quadratic statistic model. Under these conditions, the phosphorus reduction rate can reach 96.88%, which is close to the model prediction value 99.40%. The optimized carbothermal reduction conditions of phosphorus rock by the RSM are helpful to reduce the energy cost of thermal phosphoric acid process.

Study on the Method of Lime Cream to Remove Sodium from Fly Ash Red Mud by Soda-Lime Sintering Process

2013 ◽  
Vol 726-731 ◽  
pp. 2790-2794
Author(s):  
Guang Hui Bai ◽  
Lin Lv ◽  
Tong Song Wang ◽  
Peng Cheng Li ◽  
Cai Ling He
Keyword(s):  
Fly Ash ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Red Mud ◽  
Removal Rate ◽  
Soda Lime ◽  
Sodium Content ◽  
Sintering Process ◽  
Solid Ratio ◽  
Sodium Removal

It is the first time to remove sodium from the fly ash red mud by soda-lime sintering process to determine whether the fly ash red mud can be used in cement production. This paper studies the effects of the reaction time, the reaction temperature, the ratio of liquid to solid, and the amount of sodium removal agent on the removal of milk of lime method of fly ash red mud in sodium. The optimal reaction conditions are that: the reaction time is 120min, the reaction temperature is 90°C, the ratio of liquid to solid ratio is 6:1, and the ratio of sodium removal agent Ca (OH) 2 to the red mud of Na2O use ratio is 9:1. Under this condition, the sodium removal rate (Na2O, the same below) to 57.2%, the total sodium content in fly ash red mud decreases from 4.7% to 1.8% after sodium removal, achieving the expected goal.

Effect of Hydrothermal Conditions on the Cation Exchange Capacity of MSWI Fly Ash

2006 ◽  
Vol 510-511 ◽  
pp. 110-113
Author(s):  
Young Sook Shim ◽  
Woo Keun Lee
Keyword(s):  
Fly Ash ◽  
Reaction Time ◽  
Cation Exchange ◽  
Reaction Temperature ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Waste Incinerator ◽  
Liquid Ratio ◽  
Hydrothermal Conditions ◽  
Solid Liquid

In this study, we studied to find the most suitable condition for the preparation of adsorbent by hydrothermal treatment of fly ash from the municipal solid waste incinerator (MSWI). There are many variables that affect the adsorptive characteristics in our study. With the variation of which discussed the effect such as the concentration of NaOH, reaction temperature, reaction time, solid/liquid ratio, and so on. The phase of adsorbent, its morphology and cation exchange capacity (CEC) were analyzed to evaluate their effects. The phase of adsorbent after treatment was identified by X-ray diffraction (XRD), the morphology was examined by scanning electron microscopy (SEM), and the CEC was analyzed by the ammonium acetate method. The maximum CEC value was obtained under the condition of 3N NaOH, 100°C of reaction temperature, 12 hr of reaction time, and 1:10 of solid/liquid ratio. The CEC was 68 meq/100g in this condition, which was 8 times the amount of raw fly ash.

scholarly journals Two-Stage Plasma-Thermal Nitridation Processes for the Production of Aluminum Nitride Powders from Aluminum Powders

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 359 ◽  
Author(s):  
Mei-Chen Sung ◽  
Ya-Fen Wang ◽  
Shang-Che Chen ◽  
Cheng-Hsien Tsai
Keyword(s):  
Reaction Time ◽  
Aluminum Nitride ◽  
Reaction Temperature ◽  
Mass Production ◽  
Microwave Plasma ◽  
Synthesis Process ◽  
Sem Images ◽  
Nitridation Process ◽  
Low Efficiency ◽  
Thermal Nitridation

The synthesis of aluminum nitride (AlN) powders is traditionally done via the thermal nitridation process, in which the reaction temperature reaches as high as 960 °C, with more than several hours of reaction time. Moreover, the occurrence of agglomeration in melting Al particles results in poor AlN quality and a low efficiency of nitridation. In this study, an atmosphere-pressure microwave-plasma preceded the pre-synthesis process. This process operates at 550 °C for 2–10 min with the addition of NH4Cl (Al: NH4Cl = 1:1) for generating a hard AlN shell to avoid the flow and aggregation of the melting Al metals. Then, the mass production of AlN powders by the thermal nitridation process can be carried out by rapidly elevating the reaction temperature (heating rate of 15 °C/min) until 1050 °C is reached. X-Ray Diffractometer (XRD) crystal analysis shows that without the peak, Al metals can be observed by synthesizing AlN via plasma nitridation (at 550 °C for 2 min, Al: NH4Cl = 1:1), followed by thermal nitridation (at 950 °C for 1 h). Moreover, SEM images show that well-dispersed AlN powders without agglomeration were produced. Additionally, the particle size of the produced AlN powder (usually < 1 μm) tends to be reduced from 2–5 μm (Al powders), resulting in a more efficient synthesizing process (lower reaction temperature, shorter reaction time) for mass production.

In Situ Synthesis of β-Sialon Powder from Fly Ash

2011 ◽  
Vol 194-196 ◽  
pp. 2179-2182 ◽  
Author(s):  
Bei Yue Ma ◽  
Ying Li ◽  
Li Bing Xu ◽  
Yu Chun Zhai
Keyword(s):  
Fly Ash ◽  
Carbon Black ◽  
Carbothermal Reduction ◽  
Raw Materials ◽  
Reaction Process ◽  
Synthesis Process ◽  
Average Particle ◽  
Nitridation Reaction ◽  
Sialon Powder

β-Sialon powder was synthesized by in-situ carbothermal reduction-nitridation process, with fly ash and carbon black as raw materials. The influence of raw materials composition on synthesis process was investigated, and the phase composition and microstructure of the synthesized products were characterized by X-ray diffraction and scanning electronic microscope. The carbothermal reduction-nitridation reaction process was also discussed. It was found that increasing carbon content in a sample could promote the decomposition of mullite in fly ash and the formation of β-Sialon. The β-Sialon could be synthesized at 1550°C for 6h by heating the sample with the mass ratio of fly ash to carbon black of 100:56. The β-Sialon as-received in this study existed as granular with an average particle size of about 2μm. The carbothermal reduction-nitridation reaction process consisted of the nitridation processes of mullite, SiO2and Al2O3in fly ash as well as the conversion process of X-Sialon to β-Sialon.

Optimization of Magnesium Separation and Extraction from Boron Slurry Using Response Surface Methodology

2011 ◽  
Vol 366 ◽  
pp. 366-369
Author(s):  
Feng Gao ◽  
Rong Fu ◽  
Ming Yang Qian ◽  
Zhu Min Wang ◽  
Xiang Zhang
Keyword(s):  
Response Surface Methodology ◽  
Reaction Time ◽  
Factorial Design ◽  
Response Surface ◽  
Reaction Temperature ◽  
Fractional Factorial Design ◽  
Design Criterion ◽  
Fractional Factorial ◽  
Effective Factors

Response surface methodology was used to optimize the soaking Mg leaching ratio from the boron slurry screened by 25 fractional factorial design. Five effective factors such as H2SO4 concentrations, reaction time, reaction temperature and stir velocity were tested by using 25 fractional factorial design criterion and three effective factors H2SO4 concentrations, reaction time and reaction temperature showed significant effect(P2SO4 concentrations of 0.29mol/l, reaction time of 90 min and reaction temperature of 50°C. Three runs of additional confirmation experiments were conducted. The mixture magnesium leaching value was 58.20%.

Ring-Opening Polymerization of Lactide Using Aluminum Salen-Type Initiators

2014 ◽  
Vol 915-916 ◽  
pp. 713-716
Author(s):  
Qing Zhang ◽  
Jing Tian ◽  
Zhi Qi Cao ◽  
Ru Xia Xu ◽  
Zhen Zhen Sun ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Infrared Spectroscopy ◽  
Reaction Time ◽  
Magnetic Resonance ◽  
Schiff Bases ◽  
Reaction Temperature ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Resonance Spectroscopy ◽  
Aluminum Complex

In this investigation, Schiff bases aluminum complex was synthesized and used as the initiator in the polymerization of D,L-lactide. The aluminum complex was characterized by infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The influences of different factors, including reaction time, reaction temperature, and the ratio of D, L-lactide/Al3+ on the synthesis of polylactide were described. The results showed that Schiff bases aluminum complex could be successfully applied in the ring opening polymerization. The optimum condition of the ring opening polymerization of D,L-lactide, which included D,L-lactide/Al3+ (mol/mol) ratio of 250, reaction temperature of 120 °C, and reaction time of 16 hours.

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