Structural properties of residual carbon in coal gasification fine slag and their influence on flotation separation and resource utilization:A review

Coal gasification fine slag(FS)is a typical solid waste generated in coal gasification.Its current disposal methods of stockpil-ing and landfilling have caused serious soil and ecological hazards.Separation recovery and the high-value utilization of residual carbon(RC)in FS are the keys to realizing the win-win situation of the coal chemical industry in terms of economic and environmental benefits.The structural properties,such as pore,surface functional group,and microcrystalline structures,of RC in FS(FS-RC)not only affect the flotation recovery efficiency of FS-RC but also form the basis for the high-value utilization of FS-RC.In this paper,the characteristics of FS-RC in terms of pore structure,surface functional groups,and microcrystalline structure are sorted out in accordance with gasification type and FS particle size.The reasons for the formation of the special structural properties of FS-RC are analyzed,and their influence on the flotation separation and high-value utilization of FS-RC is summarized.Separation methods based on the pore structural characterist-ics of FS-RC,such as ultrasonic pretreatment-pore-blocking flotation and pore breaking-flocculation flotation,are proposed to be the key development technologies for improving FS-RC recovery in the future.The design of low-cost,low-dose collectors containing polar bonds based on the surface and microcrystalline structures of FS-RC is proposed to be an important breakthrough point for strengthening the flotation efficiency of FS-RC in the future.The high-value utilization of FS should be based on the physicochemical structural proper-ties of FS-RC and should focus on the environmental impact of hazardous elements and the recyclability of chemical waste liquid to es-tablish an environmentally friendly utilization method.This review is of great theoretical importance for the comprehensive understand-ing of the unique structural properties of FS-RC,the breakthrough of the technological bottleneck in the efficient flotation separation of FS,and the expansion of the field of the high value-added utilization of FS-RC.

Mechanical mechanism of overlying strata breaking and development of fractured zone during close-distance coal seam group mining

This study mainly investigates the mechanical mechanism of overlying strata breaking and the development of fractured zones during close-distance coal seam group mining in the Gaojialiang coal mine.First,a mechanical model for the second"activation"of broken overlying strata is established,and the related mechanical"activation"conditions are obtained.A recursive formula for calculating the separation distance of overlying strata is deduced.Second,a height determining method for predicting the height of fractured zones during close-distance coal seam group mining is proposed based on two values,namely,the separation distance and ultimate subsidence value of overlying strata.This method is applied to calculate the fractured zone heights in nos.20107 and 20307 mining faces.The calculated results are almost equal to the field observation results.Third,a modified formula for calculating the height of a waterflowing fractured zone is proposed.A comparison of the calculated and observed results shows that the errors are small.The height determining method and modified formula not only build a theoretical foundation for water conservation mining at the Gaojialiang coal mine,but also provide a reference for estimating the height of water-flowing fractured zones in other coal mines with similar conditions.

The Trace Elements are Bounded by Organic Functional Groups in Coal:A Studying Result Based on FTIR Analysis

The relationship between trace elements in coal and organic functional groups of coal, also some of aromatic structure, was investigated by using curve fitting of infrared spectra. Cluster analysis was also performed according to the degree of affinity of organic groups to the trace elements. The results show that there is a possibility that trace elements, especially LREE, were bound to peripheral organic functional groups of middle rank coal macromolecule. The most possible functional group that binds trace element is the hydroxyl, and to the less degree, the asymmetric -CH3 and 〉CH2 stretching, -CH3 stretching, etc. The degree of affinity of trace elements to different functional groups varies. The tendency obeys the natural structural changing law of trace elements-- the periodic law. The deviation of some trace elements from this regular trend is attributed to the deviation of intrinsic ＂confusion degree＂ （conventional molar entropy） of the matter system of coal basin, which is affected by the inner and outer factors during the evolution.

Stress distribution rule of roadway affected by overhead mining in gently inclined coal seams group

In light of the severe deformation and destruction of the district raise tunnel in the mining area at the northern part of the Lubanshan colliery, by the theoretic analysis and numerical simulation, both the mining stress distribution in seams group and the deformation and destruction mechanism of floor district raise were investigated. The results show that, at the maximum vertical distance of 40 m, the abutment stress has an influence on the recovery of 2# and 3# coal seam and 8# coal seam at distance of 30 m. As a result, the recovery of 8# is rather than those of 2# or 3# coal seam, which contributes to the deformation and destruction of the district raise surrounding rock. The major factors affecting the abutment stress include the mining depth, mining height, residual gob space, adjacent working faces and short spacing coal seam recovery.

Group separation of coal components and new ideas of coal utilization as petroleum

Four different groups of components were separated from coal under mild conditions of extraction and stripping process. Within these groups, and with pre-separation, individual utilization of all coal components can be realized, similar to petroleum components and enhance the inherent value and utilization value of coal, as well as increase environmental benefits. The characteristics of each component were analyzed with measurements by FTIR, GC/MS, TEM and the establishment of caking properties. The results show that coal can be separated into residues, ultra-pure coal, asphaltene components and light components by adding solvents for stripping into the CS2/NMP mixed extraction solution. Those four groups of components present great differences in the presence of carbon and hydrogen elements, in the structure of functional groups, in their macroscopic structure and micro-morphology and caking properties. Every component possesses its own inherent values and approaches. A new idea of coal processes and utilization, similar to the use of petroleum is proposed.

Group separation and analysis of a carbon disulfide-soluble fraction from Shenfu coal by column chromatography

A carbon disulfide-soluble fraction (CDSSF) from Shenfu coal was separated into five fractions by silica-gel column chromatography using hexane and n-hexane/ethyl acetate binary eluent. The five fractions include four clear group fractions and a nonpolar fraction. All the fractions were analyzed by GC/MS. A total of 204 compounds were detected from the original CDSSF and its further separated fractions, with 173 compounds more than those detected by studying the original CDSSF directly. The results demonstrate a clear group separation by column chromatography in coal organic components and a more accessibility to coal components compared with the solvent extraction only.

Numerical simulation and experimental research of surrounding rock deformation of floor roadway under short-distance coal seam group combined mining

According to the influence of the combination of short-distance coal seam groupon mining roadway, using numerical simulation software FLAC^(2D) to draw the abutmentpressure distribution ahead the working face and the area of influence in fully-mechanizedmining conditions, the variation rules of surrounding rock supporting pressure of floorroadway and the deformation rules were summarized.GYS-300 anchor dynamometer wasused to measure the roadway surface displacement, and the conclusions of numericalsimulation were verified.

Investigation into the surface active groups of coal

The oxidation heat of coal is the direct reason leading to coal spontaneous combustion. When coal is exposed in oxygen atmosphere, the physical adsorption and chemisorption happened, and then which resulting chemical reaction followed heat between coal and oxygen. Owing to the complexity and uncertain of molecular structure of coal,it was only reduced that bridge bonds, side chains and O 2 containing functional groups in coal may be prone to oxidation in last year, but not to deeply investigate into the structures and the type of the active radicals. In this paper, according to the last achievements in coal structure research, the hypomethylether bond, hypoalkyl bond of α carbon atom with hydroxyl and α carbon atom with hypomethy side chain and hypomethyl bonds linking up two aromatic hydrocarbon in bridge bonds, and methoxy,aldehyde and alkyls of α carbon atom with hydroxy in side bonds are inferred to be free radical easily to lead to oxidize coal under the ambient temperature and pressure. The order from strong to weak of oxide activation of the seven surface active groups is aldehyde side chains, hypomethylether bonds, hypoalkyl bonds of α carbon atom with hydroxyl, hypoalkyl bonds of α carbon atom with hypomethyl, hypomethyl bonds linking up two aromatic hydrocarbon,methoxy, alkyls side chains of α carbon atom with hydroxyl. Because of the two unsaturated molecular tracks of O 2, unpaired electron clouds of the part of surface active groups of coal enter molecular tracks of O 2 to lead to chemisorb on the conjugate effect and induced effect of surface active groups, and then chemical reaction followed heat happens in them. On the basis of change of bond energy, weighted average method is adopted to count the reaction heat value of each mol CO,CO 2 and H 2O. The property of coal spontaneous combustion is different for the different number and oxidability of the active structure in the coal resulting in the different oxidation heat.

Ping Ding Shah Coal Mining(Group)Co.Ltd

Ping Ding Shan Coal Mine wasestablished in 1955 and wastransformed into Ping DingShan CoalMining (group) Co. Ltd (PCMC) in 1996.The company was the first giant coal industrybase built after the founding of new China.It has over eight billion tons of coal reserves.At present, there are 12 pairs of operatingmines and three coking coal preparationplants producing 20 million tons of raw coaland smelting 3.5 million tons of clean coal ayear. The coal is provided to hundreds oflarge and medium-sized enterprises in the 11provinces and cities in the mid-south andeast of China, and part is exported abroad.Therefore the mine is known as the "coalbunker" of China.

海孜煤矿深部勘查区中组煤层气储层物性特征分析

【目的】煤层气储层的物性特征是进行煤层气开发研究的关键因子。【方法】重点对海孜煤矿深部勘探区域中组煤储层的物性参数进行调查,以对井田内中组煤储层物性特征进行研究。【结果】研究表明,煤层的物性特征适宜开采,其中有机显微组分占优,无机显微组分次之。该煤层含气量多,虽然煤层渗透率相对较小,但符合煤层气开采条件。煤层开采时的吸附作用一般,但有利于煤层气储集和缩短煤层气的开发周期。【结论】研究结果可为该研究区煤层气抽采提供可靠的技术参考。

倾斜煤层群覆岩“三场”非对称特征及靶向抽采机制

倾斜煤层群“三场”(应力场、位移场和裂隙场)演化规律较为复杂,对卸压瓦斯运移和储集具有重要意义。为了探究倾斜煤层群“三场”演化规律,研究以新疆1930煤矿为对象,开展了倾斜煤层群多重采动相似模拟实验。分析了上覆岩层垮落形态,获得了覆岩应力演化特征,分析了覆岩位移分布和移动方向特征,阐明了采动裂隙分布特征。进而探究了三场演化规律对瓦斯运移的影响,并开展了定向钻孔瓦斯抽采现场试验进行验证。研究结果表明:倾斜煤层群多重采动下,采动裂隙矩形梯台呈现明显的非对称特征。低位侧覆岩应力变化较大,随开采次数增加,卸压效应更为明显,而高位侧覆岩应力变化较小;结合重力−倾角效应,高位侧覆岩更易破坏,垮落次序优先,呈非对称特征。覆岩位移分布呈非对称特征,高位侧位移显著且移动方向变化较大。高位侧裂隙区网格内采动裂隙频数明显高于低位侧;高位侧裂隙区破断裂隙分布更多,且开度较大;采动裂隙呈“高位扩展−低位压缩”的非对称特征。多重采动使得“三场”非对称特征更为显著。此外,覆岩贯通度存在“慢速减小−快速减小”的现象。基于“三场”演化特征和瓦斯运移的关系,揭示了瓦斯抽采靶向优选机制。结合试验结果,构建了基于“三场”演化规律的裂隙带瓦斯抽采靶点区判定流程。现场瓦斯抽采效果良好,保证了工作面安全高效回采。研究结果为倾斜煤层群卸压瓦斯精准抽采提供了理论参考,旨在提高倾斜煤层群瓦斯抽采量,防止上隅角瓦斯超限,实现倾斜煤层群安全高效开采。

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。

内在矿物质对褐煤加氢热解过程中氮迁移的影响

阐明内在矿物质对褐煤加氢热解过程中氮迁移的影响对建立褐煤梯级利用过程中含氮物质污染控制方法,实现褐煤的清洁高效利用具有十分重要的指导意义。研究采用固定床反应器进行胜利褐煤加氢热解试验,考察0.1~3 MPa下内在矿物质对煤中氮向热解产物NH_(3)、HCN、N_(2)、焦油氮和半焦氮中迁移的影响以及半焦中氮官能团生成的影响。分别采用紫外分光光度计、气相色谱仪和元素分析仪分析气相中的NH_(3)、HCN、N_(2)以及焦油氮和半焦氮,采用X光电子能谱仪(XPS)表征半焦中的氮官能团。结果表明:胜利褐煤加氢热解过程中,内在矿物质催化煤中氮向NH_(3)和N_(2)迁移;内在矿物质对煤中氮向HCN迁移的影响受热解压力影响,压力为0.1 MPa时,内在矿物质明显阻碍煤中氮向HCN迁移,而压力为1~3 MPa时,内在矿物质基本不影响煤中氮向HCN迁移;内在矿物质阻碍煤中氮向半焦氮和焦油氮迁移;这是由于加氢热解过程中,内在矿物质降低煤热解反应的活化能,致使更多的自由基攻击煤中的含氮杂环,使较多的含氮杂环分解转化为了NH_(3)、N_(2)和HCN;热解反应活化能的降低促进了挥发分生成的增加,延长了挥发分从反应器中析出的时间,加强了挥发分的二次反应,进而促使挥发分中HCN和焦油氮发生二次反应生成NH_(3)。半焦中存在的内在矿物质提高了新生半焦的反应性,加速了半焦与吸附在半焦上的H的反应,促进新生半焦二次反应生成NH_(3)和N_(2)。内在矿物质促进热解半焦中吡啶型氮的生成而抑制半焦中季氮的生成。内在矿物质对褐煤加氢热解过程中氮迁移影响的研究结果将为褐煤的清洁高效利用技术的发展提供基础数据和技术支撑。

煤焦颗粒群异相反应特性的数值模拟研究

煤焦异相反应是煤粉燃烧区别于气体燃料燃烧或液体燃料燃烧的特征之一,其反应过程占整个煤粉燃烧时间约90%,对煤粉高效燃烧至关重要。通常情况下,煤粉颗粒以稠密相而非以稀疏相或单颗粒形式进入炉膛,颗粒间的相互作用会影响煤焦异相反应,因此,深入开展煤焦颗粒群异相反应行为研究对于煤的高效利用十分必要。采用准稳态的数值模拟方法研究煤焦颗粒群的异相反应行为,对比分析了煤焦单颗粒和煤焦颗粒群的反应特性,相比于煤焦单颗粒,煤焦颗粒群燃烧峰值温度升高约300 K,颗粒表面温度降低约100 K,碳消耗速率降低56%~65%,说明颗粒间作用影响了煤焦颗粒的燃烧反应进程。对3种典型分散形式下煤焦颗粒群燃烧反应特性进行研究,随着颗粒间距的增加,各分散形式的煤焦氧化反应占比增加0.22%~2.20%,碳消耗速率随之增大9.8%~26.1%,较大颗粒间距有利于O_(2)分子在颗粒间的扩散,促进了氧化反应以及煤焦消耗。探究了不同反应气氛下煤焦颗粒群的燃烧反应特性,相比于空气气氛,高CO_(2)和H_(2)O气氛下燃烧群峰值温度增加4%~30%,颗粒表面温度升高0.5%~3.7%,其中30%O_(2)/70%H_(2)O工况的碳消耗速率最大,较空气气氛高80%。综合对比,各颗粒间作用、颗粒间距和反应气氛工况下3种颗粒群分散形式的煤焦燃烧碳消耗速率依次为:形式C>形式B>形式A(形式A:颗粒群呈正方形分散;形式B:颗粒群呈正菱形分散;形式C:颗粒群呈正三角形分散),因此颗粒与气流之间的扰乱作用对煤焦的消耗产生不可忽视的影响。

济宁煤田鹿洼煤矿上组煤层水文地质特征分析

鹿洼煤矿已开采上组煤20余年,水文地质条件发生了变化,为了总结影响鹿洼煤矿上组煤开采的水害因素,在研究济宁煤田和鹿洼煤矿矿井水文地质条件的基础上,对上组煤层开采的充水因素进行了分析,并根据多年监测数据,利用“大井法”公式反演求解了导水裂隙带含水层渗透系数,采用解析法和比拟法预测了矿井涌水量。研究结果表明,鹿洼煤矿开采上组煤的主要充水水源为第四系下组下段孔隙水、老空水、侏罗系砂砾岩水、3煤顶底板砂岩水、三灰水和奥灰水,主要充水通道为断层、采动裂隙、封闭不良钻孔、岩溶陷落柱等;采用解析法预测的上组煤层正常涌水量为158.5 m^(3)/h,符合矿井实际,但建议采用比拟法预测的上组煤层正常涌水量219.23 m^(3)/h,最大涌水量328.85 m^(3)/h,提出了矿井水害防治建议。

基于空洞卷积自注意力机制的煤岩显微组分组识别模型

基于深度学习的识别模型是目前解决煤岩显微组分组识别问题的主要手段,但这些模型在计算过程中参数不断堆叠,导致模型的算力需求增加,影响模型的训练效率。针对上述问题,构建了一种基于空洞卷积自注意力(DCSA)机制的改进Swin-Transformer模型——DA-ViT。首先,为了在加强煤岩显微组分组图像的局部特征信息的同时保留其二维空间信息,提出了DCSA机制,通过对煤岩显微图像的大尺寸卷积核进行多尺度分解,加强了煤岩显微图像不同区域像素之间的联系,显著降低了图像注意力的参数量,降低率为81.18%。然后,为了加强煤岩显微组分组图像间的形态特征关联性,将DCSA和改进的Swin-Transformer框架相结合,提出了DA-ViT识别模型。实验验证结果表明,与现有的其他识别模型相比,DA-ViT模型在提高预测结果准确率的同时,可显著降低模型的算力需求,其像素准确率(PA)和平均交并比(mIoU)的最大值分别为92.14%和63.18%,模型参数总量(Params)和浮点运算次数(FLOPs)的最小值分别为4.95×106和8.99×109。

淮北1/3焦煤与不同地域同类炼焦煤的差异性研究

选取4种淮北典型1/3焦煤和4种不同地域同类1/3焦煤为研究对象,对比分析了不同煤样官能团结构、化学性质和工艺性质的差异。结果表明,4种淮北1/3焦煤煤样总体挥发分和硫分相对较低,灰分偏高,而灰成分中矿物质催化指数MCI相对较低,碱金属含量低;其中,许疃、杨柳和孙疃1/3焦煤的活惰比、b值和Y值相对较高,且煤样软化温度低,软固区间温度宽,最大流动度高于其它煤样,表明煤样胶质体的流动性和热稳定性较好,可以替代部分优质肥煤使用。与印尼1/3焦煤相比,国内7种1/3焦煤整体的芳香缩合度较高,变质程度高,煤中SiO_(2)含量较高,其中淮北煤样中的杨柳、孙疃1/3焦煤的羟基含量高,而芦岭、许疃1/3焦煤的SiO_(2)含量相对较高。

神东矿区浅埋煤层开采地表裂隙分布及动态演化特征研究

神东矿区浅埋煤层群开采导致地表裂隙发育良好,立体漏风复杂。为研究神东矿区地表裂隙分布特征及动态演化规律,以大柳塔煤矿活鸡兔井和补连塔煤矿浅埋藏开采为工程背景,采用现场无人机定点观测、红外、地质雷达等技术相结合的方法,研究地表宏观裂隙、隐蔽裂隙分布特征,并对裂隙动态演化规律进行分析。结果表明:神东矿区浅埋煤层开采工作面采空区对地表走向裂隙的影响相比于倾向裂隙较大,其中活鸡兔井12下206工作面101条裂隙有效影响范围35 m,补连塔煤矿22310工作面122条裂隙为62 m,走向裂隙最大裂隙宽度达到80 cm,倾向裂隙普遍在10 cm以下;随工作面的推进,裂隙宽度逐渐变大,直至发育完全,裂缝位置不连续断面间距变大,落差增大;宽度较大的裂隙(裂隙宽度大于10 cm),如果距离工作面较近,随着工作面的推进,裂隙宽度会逐渐缩小,甚至可能闭合。

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。