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摘要: 针对新疆褐煤具有较高内水的问题，制备了阴离子AKD改性剂和非离子AKD改性剂，对褐煤颗粒进行疏水改性。研究了改性前后煤粒表面化学成分、孔隙分布、亲疏水性和Zeta电位等煤粒表面特性，并结合NSF分散剂在改性前后煤粒表面吸附量大小，探讨了改性前后褐煤水煤浆的成浆性、流变性和稳定性。结果表明，改性后煤粒孔隙结构降低，煤粒表面碳的相对含量增加，氧的相对含量降低，煤水界面接触角增加，煤粒疏水性能增强。NSF分散剂在改性煤表面吸附量增加，煤粒表面负电性增强。由阴离子AKD改性煤、非离子AKD改性煤制备的水煤浆最大成浆质量分数从原煤56.6%分别增加至61.0%、62.5%，浆体析水率从原煤13.97%分别降低至7.45%、7.89%，同时改性后煤粒制备的浆体均表现出剪切变稀的假塑性流体。因此，改性煤粒更容易制备高浓度、低黏度、高稳定性且易于储存和运输的水煤浆。Abstract: The abundant pore structure and large number of oxygen-containing groups cause high water content of lignite, which limit its efficient utilization. In this paper, high concentration, low viscosity and high stability coal water slurry was prepared by hydrophobic modification of low rank coal to make it have the property of high rank coal. Using anionic surfactant sodium stearate and nonionic surfactant OP-10 as emulsifier emulsified alkyl ketene dimer (AKD), anionic AKD modifier and non-ionic AKD modifier were prepared, which were coated on the surface of microwave drying coal to improve the hydrophobic properties of coal particles. The surface properties of coal particles before and after modification such as chemical composition, pore distribution, hydrophobic properties and Zeta potential were studied. Combined with the adsorption results of NSF dispersant on the surface of coal particles before and after modification, the slurryability, rheology and stability of lignite coal water slurry were discussed. It is found that surface of the modified coal particles has higher carbon content and lower oxygen content, while their pore volumes are reduced, the contact angles of coal-water interface are increased, and hydrophobicity of the coal particles is enhanced. The adsorption capacity of NSF dispersant on surface of modified coal increases, which makes the surface electronegativity of coal particles increases, and coal particles have better dispersion effect in water. The maximum concentrations of CWS prepared by anionic AKD modified coal and non-ionic AKD modified coal increase from 56.6% of raw coal to 61.0% and 62.5% respectively, and the water evolution rates of CWS decrease from 13.97% of raw coal to 7.45% and 7.89% respectively. At the same time, the CWS prepared by modified coal particles show shear-thinning pseudoplastic fluid. Overall, the physical and chemical properties of coal particles have significantly changes after modification, and high-quality slurry fuels with high solid concentration, superior pseudo-plastic behavior, and good stability are easier to be prepared.
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Key words:
- lignite /
- hydrophobic modification /
- coal-water slurry /
- rheology /
- stability
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图 2 改性前后煤样C、O、Al、Si能谱谱图
Figure 2 Energy spectra of C, O, Al and Si in coal samples before and after modification
图 3 煤粒表面C、O、Al、Si元素分布
Figure 3 Distribution of C, O, Al and Si elements on the surface of coal particles
图 4 分散剂在改性前后煤表面等温吸附曲线
Figure 4 Adsorption isotherm curves of dispersant on coal surface before and after modification
表 1 新疆褐煤的煤质分析
Table 1 Analysis of coal elements and properties
Coal sample Proximate analysis w/% Ultimate analysis w/% Mad Aad Vdaf Cdaf Hdaf Odaf Ndaf St, d Xinjiang coal 12.25 15.26 40.27 68.80 4.27 25.80 0.81 0.32 
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表 2 改性前后煤粒孔隙变化
Table 2 Changes of coal porosity of raw coal and modified coal
Coal samples Surface area A/
(m2·g-1)Pore volume v/
(cm3·g-1)Average pore size
d/nmRaw coal 8.592 0.034 20.136 Microwave drying coal 8.525 0.031 19.682 1 % anionic AKD modified coal 3.698 0.027 19.168 2 % nonionic AKDmodified coal 3.035 0.021 18.257
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表 3 改性前后煤粒的接触角变化
Table 3 Changes of contact angle of raw coal and modified coal
表 4 等温吸附曲线拟合参数
Table 4 Isothermal adsorption curve fitting parameters
Coal samples Langmuir equation Freundlich equation Γ∞×10-6/(mol·g-1) b R2 k×10-5 n R2 Raw coal 2.18 12197 0.9831 1.31 3.83 0.7499 Microwave drying coal 2.46 11642 0.9932 1.48 3.80 0.7426 Anionic AKD modified coal 3.39 6771 0.9923 3.85 2.77 0.8213 Nonionic AKD modified coal 3.47 8450 0.9925 2.78 3.22 0.8757
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表 5 改性煤粒前后Zeta电位的变化
Table 5 Changes of Zeta potential of raw coal and modified coal
Coal samples Before adsorbing the dispersant V/mV After adsorbing the dispersant V/mV Surface potential difference before and after adsorption dispersant V/mV Raw coal -21.3 -23.1 -1.8 Microwave drying coal -19.6 -21.5 -1.9 Anionic AKD modified coal -29.6 -36.4 -6.8 Nonionic AKD modified coal -26.2 -33.7 -7.5
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表 6 水煤浆流变模型拟合方程
Table 6 Rheological data for CWS
Coal samples Concentration
w/%Viscosity
μ/(mPa·s)Herschel-Bulkley Power-law τ0/Pa k/(Pa·sn) n R2 k/(Pa·sn) n R2 Raw coal 56 893 -1.96 0.32 1.23 0.9996 0.23 1.30 0.9992 Microwave drying coal 58 803 -0.92 0.19 1.31 0.9996 0.16 1.35 0.9993 Anionic AKD modified coal 61 993 4.80 3.75 0.73 0.9989 5.08 0.67 0.9958 Nonionic AKD modified coal 62 741 3.85 1.07 0.89 0.9945 1.76 0.80 0.9915
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[1] WANG J, LIU J, WANG S, CHENG J. Slurrying property and mechanism of coal-coal gasification wastewater-slurry[J]. Energy Fuels, 2018, 32(4):4833-4840. http://cn.bing.com/academic/profile?id=93cf68e3050a0b18db439ca57127902a&encoded=0&v=paper_preview&mkt=zh-cn [2] YU J L, TAHMASEBI A, HAN Y N, YIN F K, LI X C. A review on water in low rank coals:The existence interaction with coal structure and effects on coal utilization[J]. Fuel Process Technol, 2013, 106(2):9-20. http://cn.bing.com/academic/profile?id=c69d8d7efbd6cce383fa1561b031c07c&encoded=0&v=paper_preview&mkt=zh-cn [3] 张大洲, 卢文新, 陈风敬, 夏吴, 左静, 王志刚, 商宽祥.褐煤干燥水分回收利用及其研究进展[J].化工进展, 2016, 35(2):472-478. http://d.old.wanfangdata.com.cn/Periodical/hgjz201602021ZHANG Da-zhou, LU Wen-xin, CHEN Feng-jing, XIA Wu, ZUO Jing, WANG Zhi-gang, SHANG Kuan-xiang. Recent developments in recovery and utilization of water and heat from lignite dewatering[J]. Chem Ind Eng Prog, 2016, 35(2):472-478. http://d.old.wanfangdata.com.cn/Periodical/hgjz201602021 [4] ALLARDICE D J, CLEMOW L M, FAVAS G, JACKSON W R, MARSHALL M, SAKUROVS R. The characterisation of different forms of water in low rank coals and some hydrothermally dried products[J]. Fuel, 2003, 82(6):661-667. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=3230bc5fed08f29ed7d560af0d0a8425 [5] JANGAM S V, KARTHIKEYAN M, MUJUMDAR A S. A critical assessment of industrial coal drying technologies:Role of energy, emissions, risk and sustainability[J]. Dry Technol, 2011, 29(4):395-407. http://cn.bing.com/academic/profile?id=27d9768084521a9948c09180bdd1515f&encoded=0&v=paper_preview&mkt=zh-cn [6] DINCER H, BOYLU F, SIRKECI A A, ATESOK G. The effect of chemicals on the viscosity and stability of coal water slurries[J]. Int J Miner Process, 2003, 70(1):41-51. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=4dbe11c741e56926788520cb270d3c1b [7] 吴君宏.褐煤水热提质改善水煤浆的成浆性、流变性和稳定性的实验研究[J].燃料化学学报, 2019, 47(3):25-32. http://www.ccspublishing.org.cn/article/id/a96ca5b2-a796-40bd-8fd9-ae6196a7961dWU Jun-hong. Hydrothermal dewatering of lignite to improve the slurry-ability, rheology, and stability of coal-water slurry[J]. J Fuel Chem Technol, 2019, 47(3):25-32. http://www.ccspublishing.org.cn/article/id/a96ca5b2-a796-40bd-8fd9-ae6196a7961d [8] FU J, WANG J. Enhanced slurryability and rheological behaviors of two low-rank coals by thermal and hydrothermal pretreatments[J]. Power Technol, 2014, 266:183-190. http://cn.bing.com/academic/profile?id=4421ceea176169d34c0c57b1a7ee1d31&encoded=0&v=paper_preview&mkt=zh-cn [9] MEIKAP B C, PUROHIT N K, MAHADEVAN V. Effect of microwave pretreatment of coal for improvement of rheological characteristics of coal-water slurries[J]. J Colloid Interface Sci, 2005, 281(1):225-235. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=96c261baa9277ff4c9b613285b5a04dc [10] LIU J, WU J, ZHU J, WANG Z, ZHOU J, CEN K. Removal of oxygen functional groups in lignite by hydrothermal dewatering:An experimental and DFT study[J]. Fuel, 2016, 178(15):85-92. http://cn.bing.com/academic/profile?id=bd4ff8e88292e47137cabb5089dd4e18&encoded=0&v=paper_preview&mkt=zh-cn [11] ZHANG X P, ZHANG C, TAN P, LI X, FANG Q Y, CHEN G. Effects of hydrothermal upgrading on the physicochemical structure and gasification characteristics of Zhundong coal[J]. Fuel Process Technol, 2018, 172:200-208. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=b21ee7c6ce633fda7b29fbece0640290 [12] ZHOU Z J, LI X, LIANG J, LIANG J M, LIU J Z. Surface coating improves coal-water slurry formation of Shangwan coal[J]. Energy Fuels, 2011, 25(8):3590-3597. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=4a49f57f7bcc64081f81503c03abf831 [13] GANI A, MORISHITA K, NISHIKAWA K, NARUSE I. Characteristics of co-combustion of low-rank coal with biomass[J]. Energy Fuels, 2005, 19(4):1652-1659. http://cn.bing.com/academic/profile?id=96c2d3fb7d99c9c531e61d570f0d45e6&encoded=0&v=paper_preview&mkt=zh-cn [14] BAE J S, LEE D W, LEE Y J, PARKET S J, PARK J H, HONG J C, KIM J G, YOON S P, KIM H T, HAN C, CHOI Y C. Improvement in coal content of coal-water slurry using hybrid coal impregnated with molasses[J]. Power Technol, 2014, 254:72-77. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=9bbb6459ca683e6700644cc5977e44fa [15] 郭晶, 张光华, 张万斌, 朱军峰, 吴江, 杜伦.烷基烯酮二聚体对褐煤疏水改性及成浆性能的影响[J].化工进展, 2019, 38(10):4705-4711. http://d.old.wanfangdata.com.cn/Periodical/hgjz201910038GUO Jing, ZHANG Guang-hua, ZHANG Wan-bin, ZHU Jun-feng, WU Jiang, DU Lun. Effect on surface hydrophobic modification and slurribility of lignite coal by alkyl ketone dimer[J]. Chem Ind Eng Progress, 2019, 38(10):4705-4711. http://d.old.wanfangdata.com.cn/Periodical/hgjz201910038 [16] GU T Y, WU G G, LI Q H, SUN Z Q, ZENG F, WANG G Y, MENG X L. Blended coals for improved coal water slurries[J]. J China Univ Min Technol, 2008, 18(1):50-54. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=zgkydxxb-e200801011 [17] PARK J H, LEE J H, JIN M H, PARK S J, LEE D W, BAE J S, KIM J G, SONG K H, CHOI Y C. Enhancement of slurryability and heating value of coal water slurry (CWS) by torrefaction treatment of low rank coal (LRC)[J]. Fuel, 2017, 203(1):403-410. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=2c6fe014a1b5f130fd0dd567eb4db885 [18] GAO Z F, ZHU S Q, ZHENG M D, WU Z J, LU H H, LIU W M. Effects of fractal surface on rheological behavior and combustion kinetics of modified brown coal water slurries[J]. J China Coal Soc, 2015, 3(3):211-222. http://cn.bing.com/academic/profile?id=81bba8505c158dbbab03604002824e99&encoded=0&v=paper_preview&mkt=zh-cn [19] 朱军峰, 李元博, 张光华, 王睿.聚羧酸盐侧链长度对水煤浆分散性能的影响及其作用机理[J].化工学报, 2015, 66(10):4202-4210. http://d.old.wanfangdata.com.cn/Periodical/hgxb201510050ZHU Jun-feng, LI Yuan-bo, ZHANG Guang-hua, WANG Rui. Action mechanism and effect of side chain length of polycarboxylate dispersant on disperse-on of coal-water slurries[J]. Chem Ind, 2015, 66(10):4202-4210. http://d.old.wanfangdata.com.cn/Periodical/hgxb201510050 [20] 杨东杰, 郭闻源, 李旭昭.不同相对分子质量对接枝磺化木质素水煤浆分散剂吸附分散性能的影响[J].燃料化学学报, 2013, 41(1):20-25. http://d.old.wanfangdata.com.cn/Periodical/rlhxxb201301004YANG Dong-jie, GUO Wen-yuan, LI Xu-zhao. Effects of molecular weight of grafted sulfonated lignin on its dispersion and adsorption properties as a dispersant for coal water slurries[J]. J Fuel Chem Technol, 2013, 41(1):20-25. http://d.old.wanfangdata.com.cn/Periodical/rlhxxb201301004 [21] WANG R K, MA Q Q, YE X M, LI C X, ZHAO ZH. Preparing coal slurry from coking wastewater to achieve resource utilization:slurrying mechanism of coking wastewater-coal slurry[J]. Sci Tot Environ, 2019, 650(2):1678-1687. http://cn.bing.com/academic/profile?id=664101c207332f1cbc9aa58c6ce4fd4b&encoded=0&v=paper_preview&mkt=zh-cn [22] LI D, LIU J Z, WANG J Q, BAI Q C, CHENG J, CEN K F. Experimental studies on coal water slurries prepared from coal gasification wastewater[J]. Asia-Pac J Chem Eng, 2017, 13(1). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=10.1002/apj.2162 [23] 但盼, 邱学青, 周明松.温度及剪切时间对水煤浆表观黏度及流变性影响[J].煤炭科学技术, 2008, 36(6):103-106. http://d.old.wanfangdata.com.cn/Periodical/mtkxjs200806030DAN Pan, QIU Xue-qing, ZHOU Ming-song. Temperature and shearing time influenced to viscosity and rheological behavior of coal water slurry[J]. Coal Sci Technol, 2008, 36(6):103-106. http://d.old.wanfangdata.com.cn/Periodical/mtkxjs200806030 -
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