Mechanical property and permeability of raw coal containing methane under unloading confining pressure

Based on domestic-developed triaxial servo-controlled seepage equipment for thermal-hydrologicalmechanical coupling of coal containing methane,an experimental study was carried out to investigate mechanical property and gas permeability of raw coal,under the situation of conventional triaxial compression and unloading confining pressure tests in different gas pressure conditions.Triaxial unloading confining pressure process was reducing confining pressure while increasing axial pressure.The research results show that,compared with the peak intensity of conventional triaxial loading,the ultimate strength of coal samples of triaxial unloading confining pressure was lower,deformation under loading was far less than unloading,dilation caused by unloading was more obvious than loading.The change trend of volumetric strain would embody change of gas permeability of coal,the permeability first reduced along with volumetric strain increase,and then raised with volume strain decrease,furthermore,the change trends of permeability of coal before and after destruction were different in the stage of decreasing volume strain due to the effect of gas pressure.When gas pressure was greater,the effective confining pressure was smaller,and the radial deformation produced by unloading was greater.When the unloading failed confining pressure difference was smaller,coal would be easier to get unstable failure.

Development and validation of THM coupling model of methane-containing coal

Based on nine necessary basic assumptions for THM coupling model,this research comprehensively applied the theories of elastic mechanics,seepage mechanics and heat transfer,and established a real three-field and two-way coupled mathematical model to reveal the connections among seepage field,deformation field and temperature field within the system of methane-containing coal.In comparison between numerical and analytical solutions,the coupling modeling for THM of methane-containing coal was proved to be correct by model application in the physical simulation experiment of coal and gas outburst.The model established in this paper was the improvement of traditional seepage theory of methane-containing coal and fluid-solid coupled model theory,which can be widely used in prevention of coal and gas outburst as well as exploitation of coal bed methane.

Calcified roasting-acid leaching process of vanadium from low-grade vanadium-containing stone coal

The low-grade vanadium-containing stone coal used in this experiment was collected from Wuxi Country, Chongqing City, China. The experiment focused on the vanadium recovery from roasted residue through optimizing the process conditions of an effective and environmentally-friendly technology, named calcified roasting-sulfuric acid leaching technology. By single-factor experiments and orthogonal experiments, the effects of roasting temperature, roasting time, sulfuric acid concentration and leaching time on the leaching ratio of vanadium were analyzed. The results showed that the leaching ratio of vanadium reached 85.5% under the proper technological conditions of roasting temperature=950℃, roasting time=4 h, 40% concentration of sulfuric acid and leaching time=6 h.

Failure modes of coal containing gas and mechanism of gas outbursts

In order to explain the mechanism for gas outburst, the process of evolving fractures in coal seams is described using system dynamics with variable boundaries. We discuss the failure modes of coal containing gas and then established the flow rules after failure. The condition under which states of deformation convert is presented and the manner in which these convert is proposed. In the end, the process of gas outbursts is explained in detail. It shows that a gas outburst is a process in which the boundaries of coal seams are variable because of coal failure. If the fractures are not connected or even closed owing to coal/rock stress, fractured zones will retain a certain level of carrying capacity because of the self-sealing gas pressure. When the accumulation of gas energy reaches its limit, coal seams will become unstable and gas outbursts take place.

Carburization of ferrochromium metals in chromium ore fines containing coal during voluminal reduction by microwave heating

Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the conditions of COFCC with n(O)-n(C) (molar ratio) as 1.00-0.84 and n(SiO2)-n(CaO) as 1.00-0.39, the samples were heated by 10 kW microwave power to reach the given temperatures and held for different times respectively. The results show that the low-C-Cr ferrochromium metal phase in the reduced materials forms before the high-C-Cr ferrochromium metal phase does. With increasing temperature the C content of ferrochromium metals is in a positive correlation with the content of Cr. The C content of ferrochromium metal in reduced materials is 0-10.07% with an average value of 4.68%. With the increase of holding time the Cr content in ferrochromium metals is in a negative correlation with the content of C, while the content of Fe changes in the contrary way. In the microwave field the kinetic conditions of carburization are closely related with the temperature of microwave heating, holding time and carbon fitting ratio.

A triaxial creep model for coal containing gas and its stability analysis

Triaxial creep tests on CCG specimens were systematically performed using aself-made creep seepage experimental apparatus for determining the creep law of CCG.An improved triaxial creep model of CCG was established on the basis of a Nishiharamodel and another visco-elasto-plastic model,parameters of which were fitted on test data.Furthermore,the creep model is validated according to the result of triaxial creep experiments,and the outcome shows that the proposed triaxial creep model can properly characterizethe properties of various creep deformation phases of CCG,especially the acceleratingcreep phase.At the same time,the instability conditions of CCG were presentedbased on the discussion of the improved model's stability in terms of stability theories ofdifferential equation solution.

Renewable conversion of coal gangue to 13-X molecular sieve for Cd^(2+)-containing wastewater adsorption performance

Using coal gangue(CG)as raw material,a new type of all solid-waste-based 13-X molecular sieve material was controllably prepared by alkali fusion-hydrothermal method.The synthetic molecular sieve was used as a solid adsorbent to treat Cd^(2+)-containing wastewater,and its adsorption behavior on Cd^(2+)in aqueous solution was studied and analyzed.The microstructure and morphology of the molecular sieve were investigated by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM)and specific surface area analyzer.The results show that the synthesized 13-X molecular sieve has higher Brunauer–Emmett–Teller(BET)specific surface area with higher crystallinity and higher adsorption capacity for the heavy metal Cd^(2+).The adsorption process of Cd^(2+)by molecular sieve conforms to the Langmuir isotherm adsorption equation and Lagergren pseudo-second-order rate equation.Combined with thermodynamic calculation,it can be concluded that the adsorption process is physically monolayer,spontaneous and exothermic.In this study,a low-cost and naturally available synthesis method of 13-X molecular sieve is reported.Combined with its adsorption mechanism for Cd^(2+),it provides a feasible and general method for removing heavy metal ions from coal gangue and also provides a new way for the utilization of coal gangue with high added value.

三轴压缩下含瓦斯煤体电阻率响应的实验研究

目的受载含瓦斯煤体变形破裂过程中电阻率的变化规律是电阻率法预测预报煤与瓦斯突出发生的理论基础。因此,研究三轴压缩条件下含瓦斯煤体破裂过程中电阻率的变化规律十分必要。方法自主研发一套测试低频条件下受载含瓦斯煤体变形破坏过程中电阻率的实验系统,测试三轴压缩条件下含瓦斯煤体电阻率的变化规律,对实验结果进行分析和解释。结果结果表明:(1)受载含瓦斯煤体的电阻率变化与所受应力存在显著的对应关系,型煤的电阻率变化规律与应力的对应关系要优于原煤的,对应力降低比较敏感;(2)受载型煤的电阻率变化规律为先上升后下降型和下降型,受载原煤的电阻率变化规律仅有下降型;(3)从原煤和型煤的物理力学以及受载过程中的变形破坏类型、受载含瓦斯煤体变形破坏过程中的煤体结构变化情况、煤的孔隙结构以及导电类型3方面分析解释受载含瓦斯煤体的电阻率变化情况;(4)对受载含瓦斯型煤电阻率变化曲线出现的2种类型进行科学合理的解释。结论研究成果可为电阻率法预测预报煤与瓦斯突出的发生提供技术支撑。

西部干旱半干旱煤矿区生态环境损伤特征及修复机制

我国煤炭开发重点已战略西移,实现煤炭资源绿色开采与生态协调发展,成为保障国家能源安全的重要举措之一。西部煤层大多数埋藏浅、上覆基岩薄、煤层厚,有利于一次采全高大规模井工开采或露天开采。但该地区气候干旱少雨、生态条件脆弱,大规模高强度对矿区及周边生态环境造成的损伤大。由于对开采过程中生态损伤演变机制及采后修复机理尚不清楚,没有成熟的修复理论和方法作指导,成为制约该地区煤炭高质量发展的重大难题。针对上述难题开展系统研究,认为精准勘测煤炭开采全周期工作面地质-水文地质条件和矿区生态演化特征,有助于阐明开采诱致上覆土岩破损机理、水资源散失富集与循环调运规律、生态损伤演变机理和承载力,并揭示采后矿区土岩层、水资源循环、生态自适应机理。采用植物-微生物组合修复方法,初步构建井工和露天矿山人工与自然协同的水-土-生立体耦合修复理论,提出了生态修复机制的新思考,在浅埋深矿区开采形成的裂缝发育犹如农田松土一般,成为生态修复新的契机,促进水-土-生再分配,并利用微生物修复技术,可促进矿区生态环境的正向协同发展,实现西部煤矿脆弱生态区开发“金山银山”,再造“绿水青山”的思维转变。

基于改进樽海鞘群算法的含瓦斯煤破裂过程信号特征识别

针对标准樽海鞘群算法存在的计算精度不足、易陷入局部停滞等缺陷,提出一种多策略融合的樽海鞘群算法。在初始化阶段,引入线性同余法随机发生器;利用野马算法优化樽海鞘领导者位置;采用金豺算法改进樽海鞘种群追随机制。通过测试函数寻优对比实验,证明多策略融合的樽海鞘群算法相比于其他智能算法在鲁棒性与稳定性方面均有显著提升。将多策略融合的樽海鞘群算法应用到含瓦斯煤破裂过程信号特征识别,实验结果表明:提出的含瓦斯煤破裂过程信号特征识别模型具有更好的表现,准确率可达93.33%,相比其他识别模型,识别率更高。

TG-FTIR研究煤油共热解产物逸出行为

煤油共液化过程中煤与重油先发生共热解,而后加氢转化为小分子产品。因此,阐明重油对煤热解逸出产物的影响规律是调控共液化产物组成的重要热化学基础。本研究采用TG-FTIR对比研究塔河渣油(AR)和淖毛湖煤(NMH)单独热解及其共热解过程,结合热解活化能计算,探索共热解过程中塔河渣油(AR)对淖毛湖煤(NMH)热解产物逸出产物的影响。结果表明,单独热解时AR先于NMH发生热解反应。两者1∶1(质量比)混合共热解时,相比于单独热解计算的理论值,最大失重峰温度前移7℃,失重率增加约3%,共热解平均活化能降低23.6 kJ/mol,表明AR率先热解会诱发NMH热解,降低热解反应能垒。TG-FTIR结果显示,AR产生的烷烃类自由基会与NMH热解产生的含氧自由基结合,形成醇、醚等烷基类含氧有机化合物,从而抑制煤中羧基转化为CO_(2)的过程。研究结果有助于揭示共液化反应过程中重油对煤液化产物组成的影响。

基于云平台的煤矿数据中心研究与应用

随着智能化矿山建设的逐步推进,应用系统数量逐渐增加,数据不能够完全统一、系统缺乏统筹管理、功能重复建设等问题逐渐凸显。为此,以伊敏露天煤矿数据中心为例,详细分析了煤矿数据中心的总体架构,结合工业私有云开发平台及大数据技术建立了开放式、持续集成和部署、支持高负载弹性伸缩、满足智能化露天煤矿管理理念的数据中心,基于数据中心多源数据存储架构解决了矿山领域数据采集难、数据无法统一存储、业务系统孤岛和采地测专业无法及时便捷共享数据等问题,同时综合利用已有设备及其采集的系统数据,采用数据共享和计算分析工具实现生产情况和设备状态的实时掌控,提升了管理决策能力和手段。

油酸和Span80协同煤油对低阶煤的浮选强化及分子模拟计算

低阶煤表面含有较多含氧基团,可浮性差,采用传统煤油捕收剂不仅药剂消耗大,而且分选效果差。复配捕收剂可以选择性地作用于矿物表面,从而提升浮选效果。以内蒙古色连二矿选煤厂低阶煤为研究对象,考察了传统捕收剂煤油的作用效果,并在此基础上引入含氧有机药剂油酸和Span80与其复配,考察复配药剂对低阶煤浮选的强化作用,并对其作用机理进行分析。结果表明:煤油-油酸和煤油-Span80复配药剂对实验煤样浮选均有促进作用。捕收剂用量为4000 g/t,起泡剂用量为800 g/t时,煤油-Span80复配药剂对应的精煤产率为83.17%,精煤灰分为11.78%,尾煤灰分为69.15%,可燃体回收率达到93.48%,浮选完善指标为42.18%。与煤油和煤油-油酸复配药剂相比,煤油-Span80复配药剂可显著提升尾煤灰分和可燃体回收率,达到了较为理想的分选效果。机理研究结果显示,油酸和Span80与煤油复配,可显著降低药剂在矿浆中的分散粒径,提高其与颗粒的接触概率;同时,油酸和Span80与煤作用,掩蔽了煤样表面的亲水基团,改善了煤样疏水性,使其更易在煤粒表面铺展。模拟计算发现油酸和Span80药剂的前线轨道能隙小于正十二烷(煤油)的前线轨道能隙,煤油-油酸和煤油-Span80复配药剂与煤表面的相互作用能大于正十二烷(煤油)与煤表面的相互作用能,表明复配药剂更具活性,更容易与煤表面发生吸附。

活性焦孔结构与含氮官能团协同构筑对低温NO还原特性影响

低温NH_(3)-SCR是排烟温度低的非电力行业烟气脱硝的重要技术选择,低成本、结构可调性好的碳材料是最具潜力的低温NH_(3)-SCR催化剂之一,但面临脱硝效率低的瓶颈。本文以低成本、大储量准东煤为原料,基于一步催化活化工艺制备了具有典型孔隙配组与含氮官能团的活性焦催化剂,探究了活性焦孔隙配组与表面官能团对不同烟气条件下低温NH_(3)-SCR的影响。研究结果表明分级孔与含氮官能团对NH_(3)-SCR均有显著促进作用,兼具分级孔与含氮官能团的氮掺杂分级孔活性焦由于同时改善了传质通道与反应动力学,具有最优的NH_(3)-SCR性能,160℃条件下的脱硝效率高达83.5%,相比氮掺杂微孔活性焦、无掺杂分级孔焦和微孔活性焦分别提升了14.0%、26.5%和110.9%;在SO_(2)或H_(2)O存在条件下,分级孔和含氮官能团对NH_(3)-SCR性能的提升作用更加明显,微孔活性焦脱硝效率会由39.6%衰减至13.8%和34.9%,而氮掺杂分级孔焦脱硝效率有所提升,达86.4%和86.7%,这可能与官能化分级孔环境强化不同烟气组分间的协同效应有关。探明了碳基低温NH3-SCR性能与碳材料理化结构之间的依存关系,为发展高性能碳基低温NH3-SCR技术提供了新思路。

渗透剂对含瓦斯煤体置换效应实验研究

为研究渗透剂对含瓦斯煤体置换效应的变化规律,自主研制了一套高压吸附状态下解吸测试装置。选用聚乙二醇-4000和吐温-80两种非离子试剂,十二烷基苯磺酸钠和十二烷基硫酸钠两种阴离子试剂,及前者非离子与阴离子的混合试剂作为渗透剂。研究瓦斯煤体置换的全过程,分析渗透剂对瓦斯的置换量的影响,并在此基础上研究置换增幅规律。结果表明,在质量分数某一范围内,渗透剂的质量分数越高,置换瓦斯量随之增多。混合溶液的置换瓦斯能力强于阴离子溶液,阴离子溶液强于非离子溶液。

PVDF膜接触器在电厂含氨废水处理中的应用研究

燃煤电厂含氨废水具有水量大、氨氮浓度高、水质波动大的特点,常规脱氨工艺处理困难.本文采用PVDF膜接触器处理燃煤电厂高浓含氨废水,考察了膜接触器类型、水侧流量、气侧真空度、气液接触面积、进水水质等因素对脱氮效率的影响.结果表明,基于PVDF膜接触器的气液分离工艺,能够将高浓含氨废水中的氨氮浓度由1 250 mg/L降至300 mg/L以下;外压式和内压式膜接触器都有理想的应用效果;提高膜接触器水侧流量、气侧真空度能够有效提高NH3传质效率;增大传质膜面积能够显著提升循环液氨氮脱除率.提出了分离NH3在燃煤电厂的多种资源化回用途径,为膜接触器的工程化应用提供参考.

集装箱自动装煤控制系统研究

为了合理优化智能化集装箱自动装煤工作、提升装车精度、实现无人化操作,对集装箱自动装煤系统进行了研究。首先,设计了集装箱自动装煤控制系统,通过五个主要控制单元,使各单元之间相互配合协调工作。其次,对集装箱自动装煤控制系统进行模拟试验,主要测试工作效率以及装车精度,并根据试验结果判断模型实际工作效果。试验结果表明:在自动装煤阶段,前半段系统工作贴近理想工作曲线,后半段装车偏离曲线,还需改进;集装箱自动装煤控制系统装车误差小于标准误差;模型各项参数计算结果均符合要求。集装箱自动装煤控制系统能够较好地完成无人化自动装煤工作,对提高火车装车效率和精度具有较高价值。该研究在煤矿工业科技创新方面以及火车定量装车领域具有推进作用。