Search

Coal spontaneous combustion (CSC) is a major safety concern affecting not just miners and businesses, but of industry in China generally. Chemical methods are already widely applied in the field of CSC prevention and plays a vital role in suppressing its negative effects. Ionic liquids (ILs) are novel and environmentally friendly solvents that have shown possible inhibitory effects on CSC through controlling the reactive groups in coal's molecular structure. To study the effects of various ILs on CSC more thoroughly, this paper examined several types of IL that had been pre-treated for different periods and examined how they performed during different phases of the combustion process. A long flame coal type was selected and immersed in four ILs [BMIM][BF4], [BMIM][NO3], [BMIM][I], and [EMIM][BF4]. Immersion periods were 2 days, 3 months, and 6 months; a raw coal sample was retained as a control. LFA 457 laser-flash apparatus determined the thermophysical properties of the samples between 30 and 300 °C. The kinetic process of the samples (30–800 °C) was deduced by thermogravimetric–differential scanning calorimetry thermal at various heating rates (2, 5, 10, and 15 °C min−1), and the thermal effect parameters were obtained. Results from this paper show that immersion treatment using ILs has an inhibitory effect on CSC, and the reliability of the thermophysical parameters was verified by uncertainty analysis. The pre-treated samples characteristics and exothermic peak temperature with different degrees of hysteresis were recorded, and statistical analysis verified the conclusions from the thermal physics experiments. The pre-treated sample with the greatest lag over various stages was found, and the apparent activation energy (Ea) of its rapid oxidation stage was calculated by Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose methods. Meanwhile, the two kinetic methods confirm each other and come to a conclusion after joint verification. The greatest Ea found here was for a 6-month immersion coal sample using the IL [BMIM][BF4]. [ABSTRACT FROM AUTHOR]

• Polyhalite ore started to decompose into anhydrite and langbeinite at 573 K. • The changes of internal models of vibration of SO 4 indicated a phase transformation. • The most probable mechanism function matched D3 Janders diffusion mechanism. • Calcination and hot-leaching could improve the extraction of potassium. In this paper, the thermal decomposition of polyhalite ore from Dayantan Playa in Qaidam Basin of China was investigated by X-ray powder diffractometry (XRD), Raman spectroscopy (Raman), and thermal analysis techniques (TG-DTG). The dehydration reaction of polyhalite ore takes place with the release of water and starts at about 510 K. The results of X-ray diffraction of roasting sample showed that polyhalite ore starts to decompose into anhydrite and langbeinite at 573 K. Raman spectroscopy, in conjunction with X-ray diffraction, was also used to follow the thermal decomposition of polyhalite ore. The changes of internal models of vibration of the SO 4 ions in sulfates indicated the phase transformation polyhalite, langbeinite, and anhydrite. The reaction kinetics of thermal decomposition of polyhalite ore were successfully modeled by a Coats-Redfern equation (ln g (α) T 2 = ln A R β E 1 − 2 R T E − E R T ) and the activation energy is found to be 208 kJ·mol−1. Additionally, the effect of roasting temperature on potassium extraction from polyhalite ore was studied. [ABSTRACT FROM AUTHOR]

Because China has emerged as the largest greenhouse gas (GHG) emitter in total annual emissions, to accelerate the pace of GHG emission reduction in China is important to the success of global efforts in addressing climate change. Carbon trading is a market mechanism and key instrument in the mitigation of climate change. This paper explores the policy process and development state to date of China׳s carbon-trade market to understand the emergence and development of that market and to understand what barriers are hampering China׳s carbon-trade market development. To achieve this goal, this paper introduces and analyzes China׳s status in the international market, examines the factors driving carbon-market launching by the Chinese government, and traces the development of mandatory carbon-emission trading and voluntary emission trading. It is argued that China׳s carbon-trading market is confronted with challenges such as the absence of a functional carbon-trading market, inaccuracy of the quota allocation, an imperfect trading mechanism, and lagging legislation. At the present stage, shortcomings such as having no real-time carbon price and dominated spot transactions differentiate China׳s trade market substantially from a functional system. A quick market integration of China׳s carbon market appears remote. It is suggested that specific measures be taken to promote the development of the Chinese carbon-trading market. [ABSTRACT FROM AUTHOR]

• Morphology, nanostructure, functional group composition, and oxidation reaction of soot particles with different fuels are analyzed. • Soot particles from WCO biodiesel combustion exhibit more disordered nanostructure. • The surface functional group content and sp3/sp2 of biodiesel soot particles are higher. • Soot particles from WCO biodiesel is easier to be oxidized than fossil diesel soot particles. • The nanostructure definite correlations with soot particles reactivity. Biodiesel is one of carbon neutral fuels for diesel engine and waste cooking oil (WCO) would be the most viable source for biodiesel production in China. This paper studied the micromorphology, nanostructure, surface functional group composition, and oxidation activity characteristics of particles emitted from a China V bus fueled by pure WCO biodiesel and petroleum diesel, respectively. Compared with petroleum diesel, the results showed that particle mass (PM) and particle number (PN) of WCO biodiesel decreased by 38.66% and 38.12%, respectively, while the proportion of nucleation mode particles increased by about 10%. The soot particles of WCO biodiesel have higher disordered nanostructure, smaller primary particle size and fringe length, larger fringe separation distance and tortuosity, and lower graphitization degree than those of petroleum diesel. Moreover, the oxygen-containing surface functional groups content and carbon atom hybrid ratio of soot particles of WCO biodiesel were higher than those of petroleum diesel under the same oxidation temperature. And then the activation energy of soot particles from WCO biodiesel which contained more lattice defect structures was 38.43 kJ/mol, 37.8% lower than petroleum diesel, which is easier to be oxidized. [ABSTRACT FROM AUTHOR]

China Low Activation Martensitic (CLAM) steel is selected as the candidate structural material in Fusion Design Study (FDS) series fusion reactor conceptual designs. The creep property of CLAM steel has been studied in this paper. Creep tests have been carried out at 823 K and 873 K over a stress range of 150–230 MPa. The creep curves showed three creep regimes, primary creep, steady-state creep and tertiary creep. The relationship between minimum creep rate ( ε ̇ min ) and the applied stress ( σ ) could be described by Norton power law, and the stress exponent n was decreased with the increase of the creep temperature. The creep mechanism was analyzed with the fractographes of the rupture specimens which were examined by scanning electron microscopy (SEM). The coarsening of precipitates observed with transmission electron microscope (TEM) indicated the microstructural degradation after creep test. [ABSTRACT FROM AUTHOR]

The iron aluminide coating on China Low Activation Martensitic (CLAM) steel was prepared by pack cementation and subsequent heat treatment. A surface Fe 2 Al 5 layer was formed on CLAM substrate by pack cementation process with Fe 2 Al 5 donor powder and NH 4 Cl activator. Diffusion heat treatment was performed in order to allow the phase transformation from Fe 2 Al 5 to a phase with lower aluminum content. Morphology and composition of the coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES) and X-ray diffraction (XRD). There is a need to study the interdiffusion behaviors in these Al containing systems, as a basis for controlling the formation and subsequent degradation of the coating. In this paper, a predictive model was developed to describe the phase transformation of Fe 2 Al 5 as a function of processing parameters. The Wagner’s equation was used to calculate the interdiffusion coefficients based on the analysis of the Al concentration profiles. The results showed that the interdiffusion coefficients in the FeAl and α-Fe(Al) phase strongly depends on Al content and showed a maximum at about 28 at.% Al. [ABSTRACT FROM AUTHOR]

As the fourth-largest industry waste residue, after iron slag, steel slag, and red mud, in China, the comprehensive utilization of nickel slag is imminent. Coal-based reduction combined with magnetic separation was considered an efficient method to extract iron from nickel slag. During the coal-based reduction of Jinchuan ferronickel slag, the growth characteristics and kinetics of metallic iron were investigated in this paper. The metallisation rate and metal iron grain size gradually increased with the reduction temperature or the reaction time, and the coal-based reduction process was divided into the rapid formation period and the aggregation growth period of the metallic phase. The granularity distribution of metallic iron obeyed the Doseresp sigmoidal function, and the activation energy of grain growth at different stages were 52.482 ± 4.448 kJ·mol−1 and 26.426 ± 3.295 kJ·mol−1, respectively. Meanwhile, a mathematical growth model of the metallic iron grains was also established. [ABSTRACT FROM AUTHOR]

• The AAEMs were selected as catalysts of oil shale to study the pyrolysis process. • The yield of shale oil and gas improved with the presence of AAEMs during pyrolysis. • The AAEMs promote the release of H 2 and reduce the precipitation of C 2 H 4 and C 2 H 6. • Na+ increases the relative content of alkanes in the shale oil and declines alkenes. • The catalysts of Na and Mg reduce the E values of oil shale during pyrolysis. Changji oil shale in Xinjiang Province of China is abundant and characterized by high ash content and low oil content. While, catalytic pyrolysis is an effective method to improve pyrolysis performance. In this paper, CH 3 COONa, (CH 3 COO) 2 Ca and MgO were selected as catalysts of oil shale to investigate the its pyrolysis behavior and pyrolysates characteristics. The results reveal that the three catalysts improve the yields of shale oil and gas. They also promote the release of H 2 and reduce the precipitation of C 2 H 4 and C 2 H 6 in the pyrolysis gas. And CH 3 COONa and MgO improve the formation of CH 4 , while, CH 3 COONa and (CH 3 COO) 2 Ca enhance the yield of CO. In addition, these catalysts have little influence on the component of the spent shale because of its high ash contents. The existence of CH 3 COONa increases the relative content of alkanes in the shale oil and declines the relative content of alkenes, while (CH 3 COO) 2 Ca and MgO play the opposite role. The presence of AAEMs cations increases H/C ratio and the relative content of short-chain aliphatic hydrocarbons in shale oil, making the shale oil lightened. The catalysts of CH 3 COONa and MgO reduce the activation energy of oil shale during pyrolysis. Because Na+ and Mg2+ as polar centers, change the electron cloud distribution of C C bond. The E values of CJ, CJ + Na and CJ + Ca during pyrolysis fluctuated with the entire conversion rates and CJ + Mg exhibited a constantly increasing trend. [ABSTRACT FROM AUTHOR]

Thermal aging experiment is an effective method to evaluate the thermostability of structure materials which serve in high temperatures. But it difficult to acquire the aging data throughout service term, because it would take a long time. Hence, an accelerating thermal aging model of China low activation martensitic (CLAM) steel was built in this paper to shorten the time of the thermal aging experiment. The microstructure analysis and Charpy impact tests were conducted on CLAM steel after thermal aging with different temperatures. The results showed that raising temperature could accelerate the grain coarsening process and the main factor of ductile-to-brittle transition temperature (DBTT) increasing was grain coarsening after aging for less than 8000 h which were analyzed by fracture model. Hence, the activation energy of grain coarsening with a value of 47.4 kJ/mol could be regarded as the activation energy of thermal aging. Then a model of accelerating thermal aging was built by using Arrhenius formula to evaluate the properties degradation during thermal aging. This strategy could be used to accelerate thermal aging process of CLAM steel through raising aging temperature and it could save time and cost for aging experiment. [ABSTRACT FROM AUTHOR]