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.

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.

Effect of the Adjuvants on the Properties of Superfine SnO2 Powders

2018 ◽  
Vol 281 ◽  
pp. 705-709
Author(s):  
Jie Guang Song ◽  
Lin Chen ◽  
Xian Jie Zhou ◽  
Xue Yang ◽  
Xin Peng Lou ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Solar Cells ◽  
Reaction Time ◽  
Powder Material ◽  
Tin Oxide ◽  
Molar Ratio ◽  
New Type ◽  
And Performance ◽  
Holding Temperature

Ultrafine SnO2 is a new type of material, in the field of solar cells and semiconductors have a lot of use. To get different morphology and different properties of tin oxide powder material, making more applications in the field, the effect of the adjuvants on the properties of superfine SnO2 powders were distigated. Through the analysis of experimental results, the conclusions are shown the stronger the alkalinity of the auxiliary agent, the larger the grain size of the obtained particles and the more uniform the particles. When the molar ratio of salt to alkali is more than 1: 4, the amount of alkali is gradually reduced, the particle size is small, the morphology is not uniform and easy to agglomerate. When the molar ratio of salt to alkali is 1: 4, the smaller particle size is shown, the appearance morphology is uneven. The longer the reaction time, the more complete the grain, the more uniform the morphology. Under the condition of SnCl4 concentration of 0.05mol/L, reaction time is 4 days, salt and alkali molar ratio is 1: 4, holding temperature is 200°C, the auxiliary agent is NaOH, the size, shape and performance of synthesized SnO2 are the better.

Effect of the Adjuvants on the Properties of Superfine SnO2 Powders

2018 ◽  
Vol 934 ◽  
pp. 35-40
Author(s):  
Jie Guang Song ◽  
Cai Liang Pang ◽  
Yue Liu ◽  
Jia Zhang ◽  
Lin Chen ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Solar Cells ◽  
Reaction Time ◽  
Powder Material ◽  
Tin Oxide ◽  
Experimental Results ◽  
Molar Ratio ◽  
New Type ◽  
Holding Temperature

Ultrafine SnO2 is a new type of material, in the field of solar cells and semiconductors have a lot of use. To get different morphology and different properties of tin oxide powder material, making more applications in the field, the effect of the adjuvants on the properties of superfine SnO2 powders were distigated. Through the analysis of experimental results, the conclusions are shown the stronger the alkalinity of the auxiliary agent, the larger the grain size of the obtained particles and the more uniform the particles. When the molar ratio of salt to alkali is more than 1: 4, the amount of alkali is gradually reduced, the particle size is small, the morphology is not uniform and easy to agglomerate. When the molar ratio of salt to alkali is 1: 4, the smaller particle size is shown, the appearance morphology is uneven. The longer the reaction time, the more complete the grain, the more uniform the morphology. Under the condition of SnCl4 concentration of 0.05 mol/L, reaction time is 4 days, salt and alkali molar ratio is 1: 4, holding temperature is 200 °C, the auxiliary agent is NaOH, the size, shape and properties of synthesized SnO2 are the better.

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.

Looking for an Ideal Particle Size for Apatite Flotation

2008 ◽  
Vol 591-593 ◽  
pp. 805-810 ◽  
Author(s):  
R.C. Santana ◽  
A.C.C. Farnese ◽  
S.P. Ceolin ◽  
R.C. Domingues ◽  
M.C.B. Fortes ◽  
...  
Keyword(s):  
Particle Size ◽  
Phosphate Rock ◽  
Size Range ◽  
Phosphorus Recovery ◽  
Column Flotation ◽  
Low Grade ◽  
Phosphate Rocks ◽  
Particle Size Range ◽  
Apatite Group ◽  
Wide Assortment

Today, the phosphate rock processed in the world represents around some 20 billion dollars per year. Some exploitable deposits are characterizing by low grade phosphate rocks, composed of the apatite group in association with a wide assortment of accessory minerals. Usually a combination of beneficiation techniques is used to process a phosphate rock since run of mine, and then a flotation is applied to recovery apatite. This work proposes an evaluation of particle size for apatite recovery by column flotation in bench-scale. The variables collector dosage and depressant dosage were investigated experimentally applying a factorial design. According to the experimental results, the particle size range between 37&m and 105&m is an optimum size used to obtain simultaneously a product with the industry demand grade (at least 33%) and phosphorus recovery, upper than 60%.

Effect of Synthetic Technology on the Properties of Co2O3 Powder

2018 ◽  
Vol 281 ◽  
pp. 46-51
Author(s):  
Ge Xiong ◽  
Hui Min Sun ◽  
Xue Yang ◽  
Jin Shi Li ◽  
Mei Hua Chen ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Reaction Time ◽  
Hydrothermal Synthesis ◽  
Salt Solution ◽  
Average Particle Size ◽  
Particle Aggregation ◽  
Molar Ratio ◽  
Average Particle

Ultrafine Co2O3powder was prepared via hydrothermal synthesis. The effect of technology on the performance of the superfine Co2O3powders was investigated, and the hydrothermal parameters in preparing Co2O3were gradually improved. In addition, the morphology and grain size of the Co2O3powder were analyzed by FESEM. Results show that reducing the salt–alkali molar ratio resulted in more uniform Co2O3powder and smaller particles, with average particle size of approximately 40 nm. Reaction time displayed little effect on the Co2O3powder, but the particle size decreased with the reaction time. The concentration of salt solution remarkably affected the morphology of the Co2O3powder. Lower concentration resulted in smaller particle aggregation and particle size.

scholarly journals Preparation of Fly Ash/Epoxy Composites and Its Effects on Mechanical Properties

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 79 ◽  
Author(s):  
Jeesoo Sim ◽  
Youngjeong Kang ◽  
Byung Joo Kim ◽  
Yong Ho Park ◽  
Young Cheol Lee
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Tensile Strength ◽  
Fly Ash ◽  
Critical Point ◽  
Compression Strength ◽  
Industrial Waste ◽  
Epoxy Composite ◽  
The Other ◽  
Epoxy Composites

In this research, a fly ash/epoxy composite was fabricated using fly ash filler classified as industrial waste. The behavior of its mechanical properties was investigated by changing the volume of fly ash to 10, 30 and 50 vol.%. To determine the influence of particle size on the mechanical properties, we used two different sizes of the fly ash, which were separated by sieving to less than 90 μm and 53 μm. To optimize fabrication conditions, the viscosity of the fly ash/epoxy slurry was measured at various temperatures with different fly ash volume fractions. In terms of mechanical properties, tensile strength increased as the amount of fly ash increased, up to a critical point. On the other hand, the compression strength of the composite increased continuously as the amount of fly ash increased. Finally, the fracture surfaces were characterized and correlated with the mechanical properties.

Experimental Study on Performance of Green Complex Binder of Low-Grade Fly Ash and Limestone Powder

2010 ◽  
Vol 152-153 ◽  
pp. 992-995
Author(s):  
Yong Mei Sun ◽  
Juan Hong Liu
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Mineral Content ◽  
Water Requirement ◽  
Limestone Powder ◽  
Mineral Admixtures ◽  
Low Grade ◽  
Complex Binder

In this article, the effects of different content and compound ratio of low-grade fly ash and limestone powder on the strength, water requirement and adaptability with admixture of green complex binder were studied, and the influence of particle size distribution and particle morphology on its performance was analyzed. The results indicated that the strength decreased obviously with the increase of mineral content. There was an optimum ratio of fly ash and limestone powder (6:4) at a certain mineral content. Water requirement decreased, and the saturated content of admixture points became small with the increasing of limestone powder. The effects of content on the strength were much more than that of particle size distribution for composite cement with high volume of mineral admixtures.

scholarly journals Kinetics of Carbothermal Reduction Process of Different Size Phosphate Rocks

2021 ◽  
Vol 11 (1) ◽  
pp. 281-293
Author(s):  
Pengfei Li ◽  
Jian Zhang ◽  
Biwei Luo ◽  
Yan Li ◽  
Jun Ji ◽  
...  
Keyword(s):  
Particle Size ◽  
Carbothermal Reduction ◽  
Phosphate Rock ◽  
Model Fitting ◽  
Reduction Process ◽  
Integral Form ◽  
Conversion Degree ◽  
Model Free ◽  
Degree Function ◽  
Kinetics Of

Abstract The effects of particle size on the apparent kinetics of carbothermal reduction process of phosphate rock were studied by non-isothermal thermogravimetric analyses. Phosphate rock of various particle size was reacted with coke and silica under high purity argon atmosphere. The apparent kinetic model and parameters of carbothermal reduction reaction of phosphate rock with different particle sizes were derived by combination of model-free (Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Tang, Starink) and model-fitting (Coats-Redfern, Master-plots) methods. The results showed that the obtained apparent activation energy of reaction reduces from 371.74 kJ/mol to 321.11 kJ/mol as the particle size of phosphate rock decreasing from 100–150 μm to 38–48 μm. The reaction apparent kinetics was found to follow shrinking-core model and the conversion degree function equation is G ( α ) = 1 − ( 1 − α ) 1 2 G\left( \alpha \right) = 1 - {\left( {1 - \alpha } \right)^{{1 \over 2}}} (α is conversion degree and G(α) is integral form of conversion degree function).

Synthesis Parameters of Ultrafine YAG Powder Materials via Hydrothermal Precipitation Method

2018 ◽  
Vol 279 ◽  
pp. 99-103
Author(s):  
Ming Han Xu ◽  
Ai Xia Chen ◽  
Rui Hua Wang ◽  
Long Tao Liu ◽  
Zhi Hui Li ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Synthesis Process ◽  
Powder Materials ◽  
Synthesis Parameters ◽  
Hydrothermal Precipitation

YAG materials has a number of unique properties, the application is very extensive. In this paper, the superfine YAG powder materials were prepared by hydrothermal precipitation method. The influence of synthesis process on the morphology of the powder was investigated. The results showed that when the molar ratio of salt to alkali that Y3+: OH- is 1:8, the more uniform morphology of the particles can be prepared, when the molar ratio of salt to alkali is increased, the morphology of the particles will not change. The reaction time is longer, the particle size will be thicker. The smaller the concentration of Y3+ ions is, the larger the particle size will be small. The experimental results show that the rod-like particles have a poly-crystal structure at the reaction temperature of 200°C, reaction time of 2 days and the molar ratio of salt to alkali of 1:8. The diameter of the rod-like particles is most of the powders have a particle size of 1000 nm and a small amount of powder has a particle size of about 5000 nm. The purity of powder is higher through the test of XRD.

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