煤自燃过程特性及防治技术研究进展

煤炭是我国的主体能源,但煤炭开采面临着有煤自燃灾害的严重威胁。煤自燃不仅烧毁大量煤炭资源,还易引发瓦斯燃烧、爆炸等重特大事故,造成巨大的经济损失和重大的人员伤亡。为了进一步提高煤矿企业对煤自燃灾害的防控能力,推动我国煤炭资源的安全高效开采,分析了煤自燃理论的研究现状,总结了煤自燃监测预警的主要方法和技术,对比分析了煤矿常规的防灭火技术,介绍了煤自燃防治技术的最新发展及应用效果,并提出了煤自燃过程特性及防治技术的未来研究方向。较详细地阐述了煤自燃过程及特性理论基础,主要包括煤自燃的低温氧化过程机制、煤自燃分段过程特性及特殊条件下的煤自燃特性;较全面地总结了包括标志性气体方法、测温法等多种煤自燃监测预警技术的原理以及各类技术的优缺点。在上述煤自燃理论和监测预警基础上,针对常规注浆、注惰气等技术对煤自燃防控效果有限、难以满足矿井安全高效开采的问题,研发了三相阻化泡沫、凝胶泡沫、无机固化泡沫、稠化砂浆等防灭火技术,同时介绍了液氮(液态二氧化碳)快速灭火降温技术。此外,为了满足煤矿智能化、精准化开采对矿井煤自燃防治的新要求,在矿井火灾监测指标信息化与预警智能化、火源辨识与防治技术控制精准化、防灭火材料绿色化等方面提出了下一步的研究展望。     

A Porous Skeleton-Supported Organic/Inorganic Composite Membrane for High-Efficiency Alkaline Water Electrolysis

Hydrogen energy is a truly renewable and clean energy source. Alkaline water electrolysis (AWE) is the most promising technology for green hydrogen production currently. In the AWE process, the critical part of an alkaline electrolyzer is the membrane, which acts to conduct hydroxide ions and block gases. However, developing low area resistance, high bubble point pressure and highly stable membrane for high-performance AWE is still a challenge. Herein, porous skeleton-supported composite membranes via the blade-coating method for advanced AWE are prepared. The porous composite membranes, besides having hydrophilic surface, also show ultra-low area resistance (≈0.15 Ω cm²), ultra-high bubble point pressure (≈27 bar) and excellent mechanical properties (tensile stress, ≈14 MPa). By using commercial catalysts, the composite membranes exhibit a current density of up to 1.9 A cm⁻² at the voltage of 2 V in 30 wt% KOH solution at 80 °C and achieve ultra-high H₂ purity (up to 99.996%) when applied in AWE. Notably, the composite membrane can operate for more than 1600 h without performance attenuation, demonstrating excellent stability. This study opens up the feasibility of preparing high-performance AWE membranes for large-scale hydrogen production.     

碱性硫化物浸出含锑金精矿过程中的抑金措施

在含锑难冶炼金矿碱性浸出脱锑生产工艺中的金伴随浸出是一种普遍的现象,此现象使金进入到锑浸出液中,造成了一定的损失。本文根据碱性硫化物在氧化环境中的不稳定性以及碱性多硫化物浓度对于金、锑浸出过程中的反应级数差等理论,并结合实际生产情况,研究了空气氧化、二段浸出对碱性硫化体系浸锑过程中的抑制金浸出的效果。在浸出矿浆中通入4.5L/（L*min）的空气,氧化浸出4h后,Sb浸出率63%,Au浸出率0.86%。采用两段浸出法,Sb浸出率为89%,Au损失率为浸出4.2%,相比一段浸出Au损失率降低6.0%。     

四氟乙烯基可熔融加工全氟聚合物研究进展

聚四氟乙烯(PTFE)因具有独特的物理化学性质,已成为不可缺少的一类特种材料。由于聚四氟乙烯的分子量和分子链规整度较高,使聚四氟乙烯难于熔融加工。为了获得可熔融加工的全氟材料,国内外关于聚四氟乙烯共聚改性的相关研究和报道较多。本文从可熔融加工四氟乙烯基全氟聚合物的结构和特性方面入手,综述了国内外一系列四氟乙烯与全氟第二单体共聚物的最新研究现状,并提出了全氟聚合物今后的研究发展方向。     

Spontaneous Internal Electric Field in Heterojunction Boosts Bifunctional Oxygen Electrocatalysts for Zinc–Air Batteries: Theory,Experiment, and Application

Heterojunctions are a promising class of materials for high-efficiency bifunctional oxygen electrocatalysts in both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, the conventional theories fail to explain why many catalysts behave differently in ORR and OER, despite a reversible path (^*O₂⇋^*OOH⇋^*O⇋^*OH). This study proposes the electron-/hole-rich catalytic center theory (e/h-CCT) to supplement the existing theories, it suggests that the Fermi level of catalysts determines the direction of electron transfer, which affects the direction of the oxidation/reduction reaction, and the density of states (DOS) near the Fermi level determines the accessibility for injecting electrons and holes. Additionally, heterojunctions with different Fermi levels form electron-/hole-rich catalytic centers near the Fermi levels to promote ORR/OER, respectively. To verify the universality of the e/h-CCT theory, this study reveals the randomly synthesized heterostructural Fe₃N-FeN_0.0324 (Fe_xN@PC with DFT calculations and electrochemical tests. The results show that the heterostructural F₃N-FeN_0.0324 facilitates the catalytic activities for ORR and OER simultaneously by forming an internal electron-/hole-rich interface. The rechargeable ZABs with Fe_xN@PC cathode display a high open circuit potential of 1.504 V, high power density of 223.67 mW cm⁻², high specific capacity of 766.20 mAh g⁻¹ at 5 mA cm⁻², and excellent stability for over 300 h.     

Modeling of Void-Mediated Cracking and Lithium Penetration in All-Solid-State Batteries

All-solid-state batteries (ASSBs) are expected to have an exceptional energy density and safety owing to the possibilities of direct usage of lithium as an anode and the suppression of dendrites by a solid-state electrolyte (SSE). However, recent experiments unveil discharging-induced voids in lithium-SSE interfaces and charging-induced cracks in SSE, wherein lithium penetration occurs. To avoid such cell failures, a theoretical model rendering high-credibility simulations is needed to assist ASSB designs. Herein, such a model coupling the electrochemical processes and mechanical responses of an ASSB are proposed, in which the kinetics of voids and cracks are the key ingredients. Numerical simulations based on the model reveal that void growth is the result of stripping with disparate diffusivity in the surface layer and the bulk of lithium. They bring about the non-uniform distribution of Li⁺ during electroplating, a damage zone near the interface, SSE cracking, and then lithium plating in the cracks. It is noted that the cracks and lithium dendrites revealed by the simulations are very similar to those observed in in situ experiments and that a high stack pressure cannot inhibit cracking and lithium penetration. Instead, suitable lateral compressive stresses can prevent SSE from cracking and therefore inhibit lithium dendrites.