scholarly journals Mineral phase transformation in coal gangue by high temperature calcination and high-efficiency separation of alumina and silica minerals

2021 ◽  
Author(s):  
Mingzhuang Xie ◽  
Fengqin Liu ◽  
Hongliang Zhao ◽  
Chaoyang Ke ◽  
Zhiqian Xu
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
High Efficiency ◽  
Coal Gangue ◽  
Mineral Phase ◽  
High Temperature Calcination

Controllable design of double metal oxide (NiCo2O4)-modified CdS for efficient photocatalytic hydrogen production

2019 ◽  
Vol 21 (8) ◽  
pp. 4501-4512 ◽  
Author(s):  
Xian Yan ◽  
Zhiliang Jin ◽  
Yupeng Zhang ◽  
Hai Liu ◽  
Xiaoli Ma
Keyword(s):  
High Temperature ◽  
Hydrogen Production ◽  
Metal Oxide ◽  
Hydrothermal Method ◽  
High Efficiency ◽  
Composite Photocatalyst ◽  
Photocatalytic Hydrogen Production ◽  
High Temperature Calcination

In the present study, we have successfully synthesized a kind of high-efficiency NiCo2O4/CdS composite photocatalyst using the hydrothermal method and high-temperature calcination.

Preparation of Nanometer Al (OH)3 Powder Using Coal Gangue by Polyacrylamide Dispersant-Carbonization Method

2010 ◽  
Vol 160-162 ◽  
pp. 307-313
Author(s):  
Zhong Hua Tang
Keyword(s):  
High Temperature ◽  
Optimum Condition ◽  
Aluminum Hydroxide ◽  
High Efficiency ◽  
Influence Factor ◽  
Coal Gangue ◽  
The Self ◽  
Raw Material ◽  
Component Part ◽  
Aluminum Component

Polyacrylamide after the molecule degradation is used as dispersant and the coal gangue as the raw material to prepare the nanometer Al (OH)3 powder in this paper. Calcining at high temperature to activate coal gangue and controlling the change of C2S crystal were adopted to prepare the self-pulverized material of coal gangue. When the aluminum component part is distilled with NaAlO2 form from the self-pulverized material of coal gangue by using 8% Na2CO3 solution, the high-pure superfine aluminum hydroxide powder is prepared by using the high efficiency dispersant carbonization method. When the influence factor that the high efficiency dispersant carbonization method prepares high-pure superfine aluminum hydroxide powder has been studied, it has been found that the optimum condition of the high efficiency dispersant carbonization method can prepare the high-pure superfine aluminum hydroxide powder. The average granularity of aluminum hydroxide powder that has been prepared is less than 100 nm and the purity is more than 99.9%, for a new way has been opened up for the high value utilization of coal gangue.

scholarly journals Sustainable and Clean Utilization of Coal Gangue: Activation and Preparation of Citrate-Soluble Silicon Fertilizer

2021 ◽  
Author(s):  
Bo Lv ◽  
Zeya Zhao ◽  
Xiaowei Deng ◽  
Chaojun Fang ◽  
Bobing Dong
Keyword(s):  
High Temperature ◽  
High Efficiency ◽  
Coal Gangue ◽  
Effect Of Temperature ◽  
Activation Process ◽  
Corn Stalk ◽  
Efficient Manner ◽  
Silicon Fertilizer ◽  
Si Content ◽  
Soluble Silicon

Abstract Silicon (Si) fertilizer is of great significance to modern agricultural production; the citrate-soluble silicon fertilizer based on coal gangue is one way to protect the environment and meet the agricultural needs of China. In this study, we produced high-efficiency coal-gangue based silicon fertilizer by calcining a mixture of coal gangue, calcium carbonate (CaCO3) and corn stalk powder at high-temperature (i.e., high-temperature activation technology); the effect of temperature and mixing ratio on the available-Si content of activated coal gangue was studied, followed by an analysis of the mechanism of available- Si formation. The results showed that the layered structure of coal gangue was severely damaged above 600 ℃, and the kaolin began to transform into metakaolin and other substances, where the available-Si content was not high (less than 10%). When CaCO3 alone was added, the peak intensity of quartz and muscovite in coal gangue decreased significantly with the increase of CaCO3. However, CaCO3 mainly played a catalytic role in the entire calcination and activation process, forming only a small amount of calcium silicate on the contact surface with coal gangue; however, the available-Si content was still below 12.60%. When corn stalk powder alone was added, the oxides of the corn stalk ash participated in the chemical reaction involving coal gangue, forming nepheline (K(Na, K)3Al4Si4O16) and other silicates, and the available-Si content was significantly higher than that with CaCO3. When coal gangue, CaCO3, and corn stalk powder were mixed and calcined, the available-Si content was as high as 22.97% under the synergistic effect of CaCO3 and corn stalk powder; the concentration of harmful heavy metals was below 0.025 mg/L. The above is in line with the requirements of silicon fertilizer for use in agriculture, thus confirming the preparation of coal gangue-based silicon fertilizer in an efficient manner.

AEM of reaction-bonded SiC

1992 ◽  
Vol 50 (1) ◽  
pp. 344-345
Author(s):  
K Das Chowdhury ◽  
R. W. Carpenter ◽  
W. Braue
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
High Temperature ◽  
Epitaxial Growth ◽  
Liquid Silicon ◽  
Structural Ceramic ◽  
Few Data

Research on reaction-bonded SiC (RBSiC) is aimed at developing a reliable structural ceramic with improved mechanical properties. The starting materials for RBSiC were Si,C and α-SiC powder. The formation of the complex microstructure of RBSiC involves (i) solution of carbon in liquid silicon, (ii) nucleation and epitaxial growth of secondary β-SiC on the original α-SiC grains followed by (iii) β>α-SiC phase transformation of newly formed SiC. Due to their coherent nature, epitaxial SiC/SiC interfaces are considered to be segregation-free and “strong” with respect to their effect on the mechanical properties of RBSiC. But the “weak” Si/SiC interface limits its use in high temperature situations. However, few data exist on the structure and chemistry of these interfaces. Microanalytical results obtained by parallel EELS and HREM imaging are reported here.

Phase transformation and layer evolution in molybdenum disilicide-silicon carbide nanolayered coatings

1994 ◽  
Vol 52 ◽  
pp. 538-539
Author(s):  
H. Kung ◽  
T. R. Jervis ◽  
J.-P. Hirvonen ◽  
M. Nastasi ◽  
T. E. Mitchell ◽  
...  
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Oxidation Resistance ◽  
Elevated Temperatures ◽  
Matrix Material ◽  
Molybdenum Disilicide ◽  
High Temperature Strength ◽  
Cross Sectional ◽  
Good Oxidation Resistance ◽  
Structural Applications

MoSi2 is a potential matrix material for high temperature structural composites due to its high melting temperature and good oxidation resistance at elevated temperatures. The two major drawbacksfor structural applications are inadequate high temperature strength and poor low temperature ductility. The search for appropriate composite additions has been the focus of extensive investigations in recent years. The addition of SiC in a nanolayered configuration was shown to exhibit superior oxidation resistance and significant hardness increase through annealing at 500°C. One potential application of MoSi2- SiC multilayers is for high temperature coatings, where structural stability ofthe layering is of major concern. In this study, we have systematically investigated both the evolution of phases and the stability of layers by varying the heat treating conditions.Alternating layers of MoSi2 and SiC were synthesized by DC-magnetron and rf-diode sputtering respectively. Cross-sectional transmission electron microscopy (XTEM) was used to examine three distinct reactions in the specimens when exposed to different annealing conditions: crystallization and phase transformation of MoSi2, crystallization of SiC, and spheroidization of the layer structures.

The Potential of Photoelectrochemical Carbon Sinks

2018 ◽  
Author(s):  
Matthias May ◽  
Kira Rehfeld
Keyword(s):  
Global Warming ◽  
High Temperature ◽  
Greenhouse Gas ◽  
Large Scale ◽  
High Efficiency ◽  
Carbon Sink ◽  
Solar Fuels ◽  
Negative Emissions ◽  
Viable Approach ◽  
Low Sensitivity

Greenhouse gas emissions must be cut to limit global warming to 1.5-2C above preindustrial levels. Yet the rate of decarbonisation is currently too low to achieve this. Policy-relevant scenarios therefore rely on the permanent removal of CO<sub>2</sub> from the atmosphere. However, none of the envisaged technologies has demonstrated scalability to the decarbonization targets for the year 2050. In this analysis, we show that artificial photosynthesis for CO<sub>2</sub> reduction may deliver an efficient large-scale carbon sink. This technology is mainly developed towards solar fuels and its potential for negative emissions has been largely overlooked. With high efficiency and low sensitivity to high temperature and illumination conditions, it could, if developed towards a mature technology, present a viable approach to fill the gap in the negative emissions budget.<br>

The Potential of Photoelectrochemical Carbon Sinks

2018 ◽  
Author(s):  
Matthias May ◽  
Kira Rehfeld
Keyword(s):  
Global Warming ◽  
High Temperature ◽  
Greenhouse Gas ◽  
Large Scale ◽  
High Efficiency ◽  
Carbon Sink ◽  
Solar Fuels ◽  
Negative Emissions ◽  
Viable Approach ◽  
Low Sensitivity

Greenhouse gas emissions must be cut to limit global warming to 1.5-2C above preindustrial levels. Yet the rate of decarbonisation is currently too low to achieve this. Policy-relevant scenarios therefore rely on the permanent removal of CO<sub>2</sub> from the atmosphere. However, none of the envisaged technologies has demonstrated scalability to the decarbonization targets for the year 2050. In this analysis, we show that artificial photosynthesis for CO<sub>2</sub> reduction may deliver an efficient large-scale carbon sink. This technology is mainly developed towards solar fuels and its potential for negative emissions has been largely overlooked. With high efficiency and low sensitivity to high temperature and illumination conditions, it could, if developed towards a mature technology, present a viable approach to fill the gap in the negative emissions budget.<br>

scholarly journals Chemical Modification of Combusted Coal Gangue for U(VI) Adsorption: Towards a Waste Control by Waste Strategy

2021 ◽  
Vol 13 (15) ◽  
pp. 8421
Author(s):  
Yuan Gao ◽  
Jiandong Huang ◽  
Meng Li ◽  
Zhongran Dai ◽  
Rongli Jiang ◽  
...  
Keyword(s):  
Structural Analysis ◽  
High Efficiency ◽  
Low Cost ◽  
Chemical Activation ◽  
Cost Effective ◽  
Coal Gangue ◽  
Order Kinetic ◽  
Practical Applications ◽  
Detailed Structural Analysis ◽  
Alkaline Conditions

Uranium mining waste causes serious radiation-related health and environmental problems. This has encouraged efforts toward U(VI) removal with low cost and high efficiency. Typical uranium adsorbents, such as polymers, geopolymers, zeolites, and MOFs, and their associated high costs limit their practical applications. In this regard, this work found that the natural combusted coal gangue (CCG) could be a potential precursor of cheap sorbents to eliminate U(VI). The removal efficiency was modulated by chemical activation under acid and alkaline conditions, obtaining HCG (CCG activated with HCl) and KCG (CCG activated with KOH), respectively. The detailed structural analysis uncovered that those natural mineral substances, including quartz and kaolinite, were the main components in CCG and HCG. One of the key findings was that kalsilite formed in KCG under a mild synthetic condition can conspicuous enhance the affinity towards U(VI). The best equilibrium adsorption capacity with KCG was observed to be 140 mg/g under pH 6 within 120 min, following a pseudo-second-order kinetic model. To understand the improved adsorption performance, an adsorption mechanism was proposed by evaluating the pH of uranyl solutions, adsorbent dosage, as well as contact time. Combining with the structural analysis, this revealed that the uranyl adsorption process was mainly governed by chemisorption. This study gave rise to a utilization approach for CCG to obtain cost-effective adsorbents and paved a novel way towards eliminating uranium by a waste control by waste strategy.

High-temperature BaTiO3-based ternary dielectric multilayers for energy storage applications with high efficiency

2021 ◽  
Vol 414 ◽  
pp. 128760
Author(s):  
Wen-Bo Li ◽  
Di Zhou ◽  
Wen-Feng Liu ◽  
Jin-Zhan Su ◽  
Fayaz Hussain ◽  
...  
Keyword(s):  
High Temperature ◽  
Energy Storage ◽  
High Efficiency ◽  
Energy Storage Applications

Design and Evaluation of the Fresnel-Lens Based Solar Concentrator System Through a Statistical-Algorithmic Approach

2018 ◽  
Author(s):  
Hassan Qandil ◽  
Weihuan Zhao
Keyword(s):  
High Temperature ◽  
High Efficiency ◽  
Incident Light ◽  
Thermal Analyses ◽  
Solar Spectrum ◽  
Chromatic Aberration ◽  
Fresnel Lens ◽  
Optimum Number ◽  
Solar Concentrator ◽  
Receiver System

A novel non-imaging Fresnel-lens-based solar concentrator-receiver system has been investigated to achieve high-efficiency photon and heat outputs with minimized effect of chromatic aberrations. Two types of non-imaging Fresnel lenses, a spot-flat lens and a dome-shaped lens, are designed through a statistical algorithm incorporated in MATLAB. The algorithm optimizes the lens design via a statistical ray-tracing methodology of the incident light, considering the chromatic aberration of solar spectrum, the lens-receiver spacing and aperture sizes, and the optimum number of prism grooves. An equal-groove-width of the Poly-methyl-methacrylate (PMMA) prisms is adopted in the model. The main target is to maximize ray intensity on the receiver’s aperture, and therefore, achieve the highest possible heat flux and output concentration temperature. The algorithm outputs prism and system geometries of the Fresnel-lens concentrator. The lenses coupled with solar receivers are simulated by COMSOL Multiphysics. It combines both optical and thermal analyses for the lens and receiver to study the optimum lens structure for high solar flux output. The optimized solar concentrator-receiver system can be applied to various devices which require high temperature inputs, such as concentrated photovoltaics (CPV), high-temperature stirling engine, etc.

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